Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/fs/namei.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * Some corrections by tytso. | |
9 | */ | |
10 | ||
11 | /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname | |
12 | * lookup logic. | |
13 | */ | |
14 | /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. | |
15 | */ | |
16 | ||
17 | #include <linux/init.h> | |
630d9c47 | 18 | #include <linux/export.h> |
44696908 | 19 | #include <linux/kernel.h> |
1da177e4 LT |
20 | #include <linux/slab.h> |
21 | #include <linux/fs.h> | |
22 | #include <linux/namei.h> | |
1da177e4 | 23 | #include <linux/pagemap.h> |
0eeca283 | 24 | #include <linux/fsnotify.h> |
1da177e4 LT |
25 | #include <linux/personality.h> |
26 | #include <linux/security.h> | |
6146f0d5 | 27 | #include <linux/ima.h> |
1da177e4 LT |
28 | #include <linux/syscalls.h> |
29 | #include <linux/mount.h> | |
30 | #include <linux/audit.h> | |
16f7e0fe | 31 | #include <linux/capability.h> |
834f2a4a | 32 | #include <linux/file.h> |
5590ff0d | 33 | #include <linux/fcntl.h> |
08ce5f16 | 34 | #include <linux/device_cgroup.h> |
5ad4e53b | 35 | #include <linux/fs_struct.h> |
e77819e5 | 36 | #include <linux/posix_acl.h> |
99d263d4 | 37 | #include <linux/hash.h> |
2a18da7a | 38 | #include <linux/bitops.h> |
1da177e4 LT |
39 | #include <asm/uaccess.h> |
40 | ||
e81e3f4d | 41 | #include "internal.h" |
c7105365 | 42 | #include "mount.h" |
e81e3f4d | 43 | |
1da177e4 LT |
44 | /* [Feb-1997 T. Schoebel-Theuer] |
45 | * Fundamental changes in the pathname lookup mechanisms (namei) | |
46 | * were necessary because of omirr. The reason is that omirr needs | |
47 | * to know the _real_ pathname, not the user-supplied one, in case | |
48 | * of symlinks (and also when transname replacements occur). | |
49 | * | |
50 | * The new code replaces the old recursive symlink resolution with | |
51 | * an iterative one (in case of non-nested symlink chains). It does | |
52 | * this with calls to <fs>_follow_link(). | |
53 | * As a side effect, dir_namei(), _namei() and follow_link() are now | |
54 | * replaced with a single function lookup_dentry() that can handle all | |
55 | * the special cases of the former code. | |
56 | * | |
57 | * With the new dcache, the pathname is stored at each inode, at least as | |
58 | * long as the refcount of the inode is positive. As a side effect, the | |
59 | * size of the dcache depends on the inode cache and thus is dynamic. | |
60 | * | |
61 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink | |
62 | * resolution to correspond with current state of the code. | |
63 | * | |
64 | * Note that the symlink resolution is not *completely* iterative. | |
65 | * There is still a significant amount of tail- and mid- recursion in | |
66 | * the algorithm. Also, note that <fs>_readlink() is not used in | |
67 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() | |
68 | * may return different results than <fs>_follow_link(). Many virtual | |
69 | * filesystems (including /proc) exhibit this behavior. | |
70 | */ | |
71 | ||
72 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: | |
73 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL | |
74 | * and the name already exists in form of a symlink, try to create the new | |
75 | * name indicated by the symlink. The old code always complained that the | |
76 | * name already exists, due to not following the symlink even if its target | |
77 | * is nonexistent. The new semantics affects also mknod() and link() when | |
25985edc | 78 | * the name is a symlink pointing to a non-existent name. |
1da177e4 LT |
79 | * |
80 | * I don't know which semantics is the right one, since I have no access | |
81 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" | |
82 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the | |
83 | * "old" one. Personally, I think the new semantics is much more logical. | |
84 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing | |
85 | * file does succeed in both HP-UX and SunOs, but not in Solaris | |
86 | * and in the old Linux semantics. | |
87 | */ | |
88 | ||
89 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink | |
90 | * semantics. See the comments in "open_namei" and "do_link" below. | |
91 | * | |
92 | * [10-Sep-98 Alan Modra] Another symlink change. | |
93 | */ | |
94 | ||
95 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: | |
96 | * inside the path - always follow. | |
97 | * in the last component in creation/removal/renaming - never follow. | |
98 | * if LOOKUP_FOLLOW passed - follow. | |
99 | * if the pathname has trailing slashes - follow. | |
100 | * otherwise - don't follow. | |
101 | * (applied in that order). | |
102 | * | |
103 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT | |
104 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. | |
105 | * During the 2.4 we need to fix the userland stuff depending on it - | |
106 | * hopefully we will be able to get rid of that wart in 2.5. So far only | |
107 | * XEmacs seems to be relying on it... | |
108 | */ | |
109 | /* | |
110 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) | |
a11f3a05 | 111 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
1da177e4 LT |
112 | * any extra contention... |
113 | */ | |
114 | ||
115 | /* In order to reduce some races, while at the same time doing additional | |
116 | * checking and hopefully speeding things up, we copy filenames to the | |
117 | * kernel data space before using them.. | |
118 | * | |
119 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). | |
120 | * PATH_MAX includes the nul terminator --RR. | |
121 | */ | |
91a27b2a | 122 | |
fd2f7cb5 | 123 | #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) |
7950e385 | 124 | |
51f39a1f | 125 | struct filename * |
91a27b2a JL |
126 | getname_flags(const char __user *filename, int flags, int *empty) |
127 | { | |
94b5d262 | 128 | struct filename *result; |
7950e385 | 129 | char *kname; |
94b5d262 | 130 | int len; |
4043cde8 | 131 | |
7ac86265 JL |
132 | result = audit_reusename(filename); |
133 | if (result) | |
134 | return result; | |
135 | ||
7950e385 | 136 | result = __getname(); |
3f9f0aa6 | 137 | if (unlikely(!result)) |
4043cde8 EP |
138 | return ERR_PTR(-ENOMEM); |
139 | ||
7950e385 JL |
140 | /* |
141 | * First, try to embed the struct filename inside the names_cache | |
142 | * allocation | |
143 | */ | |
fd2f7cb5 | 144 | kname = (char *)result->iname; |
91a27b2a | 145 | result->name = kname; |
7950e385 | 146 | |
94b5d262 | 147 | len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); |
91a27b2a | 148 | if (unlikely(len < 0)) { |
94b5d262 AV |
149 | __putname(result); |
150 | return ERR_PTR(len); | |
91a27b2a | 151 | } |
3f9f0aa6 | 152 | |
7950e385 JL |
153 | /* |
154 | * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a | |
155 | * separate struct filename so we can dedicate the entire | |
156 | * names_cache allocation for the pathname, and re-do the copy from | |
157 | * userland. | |
158 | */ | |
94b5d262 | 159 | if (unlikely(len == EMBEDDED_NAME_MAX)) { |
fd2f7cb5 | 160 | const size_t size = offsetof(struct filename, iname[1]); |
7950e385 JL |
161 | kname = (char *)result; |
162 | ||
fd2f7cb5 AV |
163 | /* |
164 | * size is chosen that way we to guarantee that | |
165 | * result->iname[0] is within the same object and that | |
166 | * kname can't be equal to result->iname, no matter what. | |
167 | */ | |
168 | result = kzalloc(size, GFP_KERNEL); | |
94b5d262 AV |
169 | if (unlikely(!result)) { |
170 | __putname(kname); | |
171 | return ERR_PTR(-ENOMEM); | |
7950e385 JL |
172 | } |
173 | result->name = kname; | |
94b5d262 AV |
174 | len = strncpy_from_user(kname, filename, PATH_MAX); |
175 | if (unlikely(len < 0)) { | |
176 | __putname(kname); | |
177 | kfree(result); | |
178 | return ERR_PTR(len); | |
179 | } | |
180 | if (unlikely(len == PATH_MAX)) { | |
181 | __putname(kname); | |
182 | kfree(result); | |
183 | return ERR_PTR(-ENAMETOOLONG); | |
184 | } | |
7950e385 JL |
185 | } |
186 | ||
94b5d262 | 187 | result->refcnt = 1; |
3f9f0aa6 LT |
188 | /* The empty path is special. */ |
189 | if (unlikely(!len)) { | |
190 | if (empty) | |
4043cde8 | 191 | *empty = 1; |
94b5d262 AV |
192 | if (!(flags & LOOKUP_EMPTY)) { |
193 | putname(result); | |
194 | return ERR_PTR(-ENOENT); | |
195 | } | |
1da177e4 | 196 | } |
3f9f0aa6 | 197 | |
7950e385 | 198 | result->uptr = filename; |
c4ad8f98 | 199 | result->aname = NULL; |
7950e385 JL |
200 | audit_getname(result); |
201 | return result; | |
1da177e4 LT |
202 | } |
203 | ||
91a27b2a JL |
204 | struct filename * |
205 | getname(const char __user * filename) | |
f52e0c11 | 206 | { |
f7493e5d | 207 | return getname_flags(filename, 0, NULL); |
f52e0c11 AV |
208 | } |
209 | ||
c4ad8f98 LT |
210 | struct filename * |
211 | getname_kernel(const char * filename) | |
212 | { | |
213 | struct filename *result; | |
08518549 | 214 | int len = strlen(filename) + 1; |
c4ad8f98 LT |
215 | |
216 | result = __getname(); | |
217 | if (unlikely(!result)) | |
218 | return ERR_PTR(-ENOMEM); | |
219 | ||
08518549 | 220 | if (len <= EMBEDDED_NAME_MAX) { |
fd2f7cb5 | 221 | result->name = (char *)result->iname; |
08518549 PM |
222 | } else if (len <= PATH_MAX) { |
223 | struct filename *tmp; | |
224 | ||
225 | tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); | |
226 | if (unlikely(!tmp)) { | |
227 | __putname(result); | |
228 | return ERR_PTR(-ENOMEM); | |
229 | } | |
230 | tmp->name = (char *)result; | |
08518549 PM |
231 | result = tmp; |
232 | } else { | |
233 | __putname(result); | |
234 | return ERR_PTR(-ENAMETOOLONG); | |
235 | } | |
236 | memcpy((char *)result->name, filename, len); | |
c4ad8f98 LT |
237 | result->uptr = NULL; |
238 | result->aname = NULL; | |
55422d0b | 239 | result->refcnt = 1; |
fd3522fd | 240 | audit_getname(result); |
c4ad8f98 | 241 | |
c4ad8f98 LT |
242 | return result; |
243 | } | |
244 | ||
91a27b2a | 245 | void putname(struct filename *name) |
1da177e4 | 246 | { |
55422d0b PM |
247 | BUG_ON(name->refcnt <= 0); |
248 | ||
249 | if (--name->refcnt > 0) | |
250 | return; | |
251 | ||
fd2f7cb5 | 252 | if (name->name != name->iname) { |
55422d0b PM |
253 | __putname(name->name); |
254 | kfree(name); | |
255 | } else | |
256 | __putname(name); | |
1da177e4 | 257 | } |
1da177e4 | 258 | |
e77819e5 LT |
259 | static int check_acl(struct inode *inode, int mask) |
260 | { | |
84635d68 | 261 | #ifdef CONFIG_FS_POSIX_ACL |
e77819e5 LT |
262 | struct posix_acl *acl; |
263 | ||
e77819e5 | 264 | if (mask & MAY_NOT_BLOCK) { |
3567866b AV |
265 | acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); |
266 | if (!acl) | |
e77819e5 | 267 | return -EAGAIN; |
3567866b | 268 | /* no ->get_acl() calls in RCU mode... */ |
b8a7a3a6 | 269 | if (is_uncached_acl(acl)) |
3567866b | 270 | return -ECHILD; |
206b1d09 | 271 | return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); |
e77819e5 LT |
272 | } |
273 | ||
2982baa2 CH |
274 | acl = get_acl(inode, ACL_TYPE_ACCESS); |
275 | if (IS_ERR(acl)) | |
276 | return PTR_ERR(acl); | |
e77819e5 LT |
277 | if (acl) { |
278 | int error = posix_acl_permission(inode, acl, mask); | |
279 | posix_acl_release(acl); | |
280 | return error; | |
281 | } | |
84635d68 | 282 | #endif |
e77819e5 LT |
283 | |
284 | return -EAGAIN; | |
285 | } | |
286 | ||
5909ccaa | 287 | /* |
948409c7 | 288 | * This does the basic permission checking |
1da177e4 | 289 | */ |
7e40145e | 290 | static int acl_permission_check(struct inode *inode, int mask) |
1da177e4 | 291 | { |
26cf46be | 292 | unsigned int mode = inode->i_mode; |
1da177e4 | 293 | |
8e96e3b7 | 294 | if (likely(uid_eq(current_fsuid(), inode->i_uid))) |
1da177e4 LT |
295 | mode >>= 6; |
296 | else { | |
e77819e5 | 297 | if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { |
7e40145e | 298 | int error = check_acl(inode, mask); |
b74c79e9 NP |
299 | if (error != -EAGAIN) |
300 | return error; | |
1da177e4 LT |
301 | } |
302 | ||
303 | if (in_group_p(inode->i_gid)) | |
304 | mode >>= 3; | |
305 | } | |
306 | ||
307 | /* | |
308 | * If the DACs are ok we don't need any capability check. | |
309 | */ | |
9c2c7039 | 310 | if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) |
1da177e4 | 311 | return 0; |
5909ccaa LT |
312 | return -EACCES; |
313 | } | |
314 | ||
315 | /** | |
b74c79e9 | 316 | * generic_permission - check for access rights on a Posix-like filesystem |
5909ccaa | 317 | * @inode: inode to check access rights for |
8fd90c8d | 318 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) |
5909ccaa LT |
319 | * |
320 | * Used to check for read/write/execute permissions on a file. | |
321 | * We use "fsuid" for this, letting us set arbitrary permissions | |
322 | * for filesystem access without changing the "normal" uids which | |
b74c79e9 NP |
323 | * are used for other things. |
324 | * | |
325 | * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk | |
326 | * request cannot be satisfied (eg. requires blocking or too much complexity). | |
327 | * It would then be called again in ref-walk mode. | |
5909ccaa | 328 | */ |
2830ba7f | 329 | int generic_permission(struct inode *inode, int mask) |
5909ccaa LT |
330 | { |
331 | int ret; | |
332 | ||
333 | /* | |
948409c7 | 334 | * Do the basic permission checks. |
5909ccaa | 335 | */ |
7e40145e | 336 | ret = acl_permission_check(inode, mask); |
5909ccaa LT |
337 | if (ret != -EACCES) |
338 | return ret; | |
1da177e4 | 339 | |
d594e7ec AV |
340 | if (S_ISDIR(inode->i_mode)) { |
341 | /* DACs are overridable for directories */ | |
23adbe12 | 342 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) |
d594e7ec AV |
343 | return 0; |
344 | if (!(mask & MAY_WRITE)) | |
23adbe12 AL |
345 | if (capable_wrt_inode_uidgid(inode, |
346 | CAP_DAC_READ_SEARCH)) | |
d594e7ec AV |
347 | return 0; |
348 | return -EACCES; | |
349 | } | |
1da177e4 LT |
350 | /* |
351 | * Read/write DACs are always overridable. | |
d594e7ec AV |
352 | * Executable DACs are overridable when there is |
353 | * at least one exec bit set. | |
1da177e4 | 354 | */ |
d594e7ec | 355 | if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) |
23adbe12 | 356 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) |
1da177e4 LT |
357 | return 0; |
358 | ||
359 | /* | |
360 | * Searching includes executable on directories, else just read. | |
361 | */ | |
7ea66001 | 362 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
d594e7ec | 363 | if (mask == MAY_READ) |
23adbe12 | 364 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) |
1da177e4 LT |
365 | return 0; |
366 | ||
367 | return -EACCES; | |
368 | } | |
4d359507 | 369 | EXPORT_SYMBOL(generic_permission); |
1da177e4 | 370 | |
3ddcd056 LT |
371 | /* |
372 | * We _really_ want to just do "generic_permission()" without | |
373 | * even looking at the inode->i_op values. So we keep a cache | |
374 | * flag in inode->i_opflags, that says "this has not special | |
375 | * permission function, use the fast case". | |
376 | */ | |
377 | static inline int do_inode_permission(struct inode *inode, int mask) | |
378 | { | |
379 | if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { | |
380 | if (likely(inode->i_op->permission)) | |
381 | return inode->i_op->permission(inode, mask); | |
382 | ||
383 | /* This gets set once for the inode lifetime */ | |
384 | spin_lock(&inode->i_lock); | |
385 | inode->i_opflags |= IOP_FASTPERM; | |
386 | spin_unlock(&inode->i_lock); | |
387 | } | |
388 | return generic_permission(inode, mask); | |
389 | } | |
390 | ||
cb23beb5 | 391 | /** |
0bdaea90 DH |
392 | * __inode_permission - Check for access rights to a given inode |
393 | * @inode: Inode to check permission on | |
394 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
cb23beb5 | 395 | * |
0bdaea90 | 396 | * Check for read/write/execute permissions on an inode. |
948409c7 AG |
397 | * |
398 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
0bdaea90 DH |
399 | * |
400 | * This does not check for a read-only file system. You probably want | |
401 | * inode_permission(). | |
cb23beb5 | 402 | */ |
0bdaea90 | 403 | int __inode_permission(struct inode *inode, int mask) |
1da177e4 | 404 | { |
e6305c43 | 405 | int retval; |
1da177e4 | 406 | |
3ddcd056 | 407 | if (unlikely(mask & MAY_WRITE)) { |
1da177e4 LT |
408 | /* |
409 | * Nobody gets write access to an immutable file. | |
410 | */ | |
411 | if (IS_IMMUTABLE(inode)) | |
412 | return -EACCES; | |
0bd23d09 EB |
413 | |
414 | /* | |
415 | * Updating mtime will likely cause i_uid and i_gid to be | |
416 | * written back improperly if their true value is unknown | |
417 | * to the vfs. | |
418 | */ | |
419 | if (HAS_UNMAPPED_ID(inode)) | |
420 | return -EACCES; | |
1da177e4 LT |
421 | } |
422 | ||
3ddcd056 | 423 | retval = do_inode_permission(inode, mask); |
1da177e4 LT |
424 | if (retval) |
425 | return retval; | |
426 | ||
08ce5f16 SH |
427 | retval = devcgroup_inode_permission(inode, mask); |
428 | if (retval) | |
429 | return retval; | |
430 | ||
d09ca739 | 431 | return security_inode_permission(inode, mask); |
1da177e4 | 432 | } |
bd5d0856 | 433 | EXPORT_SYMBOL(__inode_permission); |
1da177e4 | 434 | |
0bdaea90 DH |
435 | /** |
436 | * sb_permission - Check superblock-level permissions | |
437 | * @sb: Superblock of inode to check permission on | |
55852635 | 438 | * @inode: Inode to check permission on |
0bdaea90 DH |
439 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
440 | * | |
441 | * Separate out file-system wide checks from inode-specific permission checks. | |
442 | */ | |
443 | static int sb_permission(struct super_block *sb, struct inode *inode, int mask) | |
444 | { | |
445 | if (unlikely(mask & MAY_WRITE)) { | |
446 | umode_t mode = inode->i_mode; | |
447 | ||
448 | /* Nobody gets write access to a read-only fs. */ | |
449 | if ((sb->s_flags & MS_RDONLY) && | |
450 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
451 | return -EROFS; | |
452 | } | |
453 | return 0; | |
454 | } | |
455 | ||
456 | /** | |
457 | * inode_permission - Check for access rights to a given inode | |
458 | * @inode: Inode to check permission on | |
459 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
460 | * | |
461 | * Check for read/write/execute permissions on an inode. We use fs[ug]id for | |
462 | * this, letting us set arbitrary permissions for filesystem access without | |
463 | * changing the "normal" UIDs which are used for other things. | |
464 | * | |
465 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
466 | */ | |
467 | int inode_permission(struct inode *inode, int mask) | |
468 | { | |
469 | int retval; | |
470 | ||
471 | retval = sb_permission(inode->i_sb, inode, mask); | |
472 | if (retval) | |
473 | return retval; | |
474 | return __inode_permission(inode, mask); | |
475 | } | |
4d359507 | 476 | EXPORT_SYMBOL(inode_permission); |
0bdaea90 | 477 | |
5dd784d0 JB |
478 | /** |
479 | * path_get - get a reference to a path | |
480 | * @path: path to get the reference to | |
481 | * | |
482 | * Given a path increment the reference count to the dentry and the vfsmount. | |
483 | */ | |
dcf787f3 | 484 | void path_get(const struct path *path) |
5dd784d0 JB |
485 | { |
486 | mntget(path->mnt); | |
487 | dget(path->dentry); | |
488 | } | |
489 | EXPORT_SYMBOL(path_get); | |
490 | ||
1d957f9b JB |
491 | /** |
492 | * path_put - put a reference to a path | |
493 | * @path: path to put the reference to | |
494 | * | |
495 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
496 | */ | |
dcf787f3 | 497 | void path_put(const struct path *path) |
1da177e4 | 498 | { |
1d957f9b JB |
499 | dput(path->dentry); |
500 | mntput(path->mnt); | |
1da177e4 | 501 | } |
1d957f9b | 502 | EXPORT_SYMBOL(path_put); |
1da177e4 | 503 | |
894bc8c4 | 504 | #define EMBEDDED_LEVELS 2 |
1f55a6ec AV |
505 | struct nameidata { |
506 | struct path path; | |
1cf2665b | 507 | struct qstr last; |
1f55a6ec AV |
508 | struct path root; |
509 | struct inode *inode; /* path.dentry.d_inode */ | |
510 | unsigned int flags; | |
9883d185 | 511 | unsigned seq, m_seq; |
1f55a6ec AV |
512 | int last_type; |
513 | unsigned depth; | |
756daf26 | 514 | int total_link_count; |
697fc6ca AV |
515 | struct saved { |
516 | struct path link; | |
fceef393 | 517 | struct delayed_call done; |
697fc6ca | 518 | const char *name; |
0450b2d1 | 519 | unsigned seq; |
894bc8c4 | 520 | } *stack, internal[EMBEDDED_LEVELS]; |
9883d185 AV |
521 | struct filename *name; |
522 | struct nameidata *saved; | |
fceef393 | 523 | struct inode *link_inode; |
9883d185 AV |
524 | unsigned root_seq; |
525 | int dfd; | |
1f55a6ec AV |
526 | }; |
527 | ||
9883d185 | 528 | static void set_nameidata(struct nameidata *p, int dfd, struct filename *name) |
894bc8c4 | 529 | { |
756daf26 N |
530 | struct nameidata *old = current->nameidata; |
531 | p->stack = p->internal; | |
c8a53ee5 AV |
532 | p->dfd = dfd; |
533 | p->name = name; | |
756daf26 | 534 | p->total_link_count = old ? old->total_link_count : 0; |
9883d185 | 535 | p->saved = old; |
756daf26 | 536 | current->nameidata = p; |
894bc8c4 AV |
537 | } |
538 | ||
9883d185 | 539 | static void restore_nameidata(void) |
894bc8c4 | 540 | { |
9883d185 | 541 | struct nameidata *now = current->nameidata, *old = now->saved; |
756daf26 N |
542 | |
543 | current->nameidata = old; | |
544 | if (old) | |
545 | old->total_link_count = now->total_link_count; | |
e1a63bbc | 546 | if (now->stack != now->internal) |
756daf26 | 547 | kfree(now->stack); |
894bc8c4 AV |
548 | } |
549 | ||
550 | static int __nd_alloc_stack(struct nameidata *nd) | |
551 | { | |
bc40aee0 AV |
552 | struct saved *p; |
553 | ||
554 | if (nd->flags & LOOKUP_RCU) { | |
555 | p= kmalloc(MAXSYMLINKS * sizeof(struct saved), | |
556 | GFP_ATOMIC); | |
557 | if (unlikely(!p)) | |
558 | return -ECHILD; | |
559 | } else { | |
560 | p= kmalloc(MAXSYMLINKS * sizeof(struct saved), | |
894bc8c4 | 561 | GFP_KERNEL); |
bc40aee0 AV |
562 | if (unlikely(!p)) |
563 | return -ENOMEM; | |
564 | } | |
894bc8c4 AV |
565 | memcpy(p, nd->internal, sizeof(nd->internal)); |
566 | nd->stack = p; | |
567 | return 0; | |
568 | } | |
569 | ||
397d425d EB |
570 | /** |
571 | * path_connected - Verify that a path->dentry is below path->mnt.mnt_root | |
572 | * @path: nameidate to verify | |
573 | * | |
574 | * Rename can sometimes move a file or directory outside of a bind | |
575 | * mount, path_connected allows those cases to be detected. | |
576 | */ | |
577 | static bool path_connected(const struct path *path) | |
578 | { | |
579 | struct vfsmount *mnt = path->mnt; | |
580 | ||
581 | /* Only bind mounts can have disconnected paths */ | |
582 | if (mnt->mnt_root == mnt->mnt_sb->s_root) | |
583 | return true; | |
584 | ||
585 | return is_subdir(path->dentry, mnt->mnt_root); | |
586 | } | |
587 | ||
894bc8c4 AV |
588 | static inline int nd_alloc_stack(struct nameidata *nd) |
589 | { | |
da4e0be0 | 590 | if (likely(nd->depth != EMBEDDED_LEVELS)) |
894bc8c4 AV |
591 | return 0; |
592 | if (likely(nd->stack != nd->internal)) | |
593 | return 0; | |
594 | return __nd_alloc_stack(nd); | |
595 | } | |
596 | ||
7973387a AV |
597 | static void drop_links(struct nameidata *nd) |
598 | { | |
599 | int i = nd->depth; | |
600 | while (i--) { | |
601 | struct saved *last = nd->stack + i; | |
fceef393 AV |
602 | do_delayed_call(&last->done); |
603 | clear_delayed_call(&last->done); | |
7973387a AV |
604 | } |
605 | } | |
606 | ||
607 | static void terminate_walk(struct nameidata *nd) | |
608 | { | |
609 | drop_links(nd); | |
610 | if (!(nd->flags & LOOKUP_RCU)) { | |
611 | int i; | |
612 | path_put(&nd->path); | |
613 | for (i = 0; i < nd->depth; i++) | |
614 | path_put(&nd->stack[i].link); | |
102b8af2 AV |
615 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
616 | path_put(&nd->root); | |
617 | nd->root.mnt = NULL; | |
618 | } | |
7973387a AV |
619 | } else { |
620 | nd->flags &= ~LOOKUP_RCU; | |
621 | if (!(nd->flags & LOOKUP_ROOT)) | |
622 | nd->root.mnt = NULL; | |
623 | rcu_read_unlock(); | |
624 | } | |
625 | nd->depth = 0; | |
626 | } | |
627 | ||
628 | /* path_put is needed afterwards regardless of success or failure */ | |
629 | static bool legitimize_path(struct nameidata *nd, | |
630 | struct path *path, unsigned seq) | |
631 | { | |
632 | int res = __legitimize_mnt(path->mnt, nd->m_seq); | |
633 | if (unlikely(res)) { | |
634 | if (res > 0) | |
635 | path->mnt = NULL; | |
636 | path->dentry = NULL; | |
637 | return false; | |
638 | } | |
639 | if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { | |
640 | path->dentry = NULL; | |
641 | return false; | |
642 | } | |
643 | return !read_seqcount_retry(&path->dentry->d_seq, seq); | |
644 | } | |
645 | ||
646 | static bool legitimize_links(struct nameidata *nd) | |
647 | { | |
648 | int i; | |
649 | for (i = 0; i < nd->depth; i++) { | |
650 | struct saved *last = nd->stack + i; | |
651 | if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { | |
652 | drop_links(nd); | |
653 | nd->depth = i + 1; | |
654 | return false; | |
655 | } | |
656 | } | |
657 | return true; | |
658 | } | |
659 | ||
19660af7 | 660 | /* |
31e6b01f | 661 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
19660af7 AV |
662 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
663 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab | |
57e3715c | 664 | * normal reference counts on dentries and vfsmounts to transition to ref-walk |
19660af7 AV |
665 | * mode. Refcounts are grabbed at the last known good point before rcu-walk |
666 | * got stuck, so ref-walk may continue from there. If this is not successful | |
667 | * (eg. a seqcount has changed), then failure is returned and it's up to caller | |
668 | * to restart the path walk from the beginning in ref-walk mode. | |
31e6b01f | 669 | */ |
31e6b01f NP |
670 | |
671 | /** | |
19660af7 AV |
672 | * unlazy_walk - try to switch to ref-walk mode. |
673 | * @nd: nameidata pathwalk data | |
674 | * @dentry: child of nd->path.dentry or NULL | |
6e9918b7 | 675 | * @seq: seq number to check dentry against |
39191628 | 676 | * Returns: 0 on success, -ECHILD on failure |
31e6b01f | 677 | * |
19660af7 AV |
678 | * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry |
679 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on | |
680 | * @nd or NULL. Must be called from rcu-walk context. | |
7973387a AV |
681 | * Nothing should touch nameidata between unlazy_walk() failure and |
682 | * terminate_walk(). | |
31e6b01f | 683 | */ |
6e9918b7 | 684 | static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) |
31e6b01f | 685 | { |
31e6b01f NP |
686 | struct dentry *parent = nd->path.dentry; |
687 | ||
688 | BUG_ON(!(nd->flags & LOOKUP_RCU)); | |
e5c832d5 | 689 | |
e5c832d5 | 690 | nd->flags &= ~LOOKUP_RCU; |
7973387a AV |
691 | if (unlikely(!legitimize_links(nd))) |
692 | goto out2; | |
693 | if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) | |
694 | goto out2; | |
695 | if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) | |
696 | goto out1; | |
48a066e7 | 697 | |
15570086 LT |
698 | /* |
699 | * For a negative lookup, the lookup sequence point is the parents | |
700 | * sequence point, and it only needs to revalidate the parent dentry. | |
701 | * | |
702 | * For a positive lookup, we need to move both the parent and the | |
703 | * dentry from the RCU domain to be properly refcounted. And the | |
704 | * sequence number in the dentry validates *both* dentry counters, | |
705 | * since we checked the sequence number of the parent after we got | |
706 | * the child sequence number. So we know the parent must still | |
707 | * be valid if the child sequence number is still valid. | |
708 | */ | |
19660af7 | 709 | if (!dentry) { |
e5c832d5 LT |
710 | if (read_seqcount_retry(&parent->d_seq, nd->seq)) |
711 | goto out; | |
19660af7 AV |
712 | BUG_ON(nd->inode != parent->d_inode); |
713 | } else { | |
e5c832d5 LT |
714 | if (!lockref_get_not_dead(&dentry->d_lockref)) |
715 | goto out; | |
6e9918b7 | 716 | if (read_seqcount_retry(&dentry->d_seq, seq)) |
e5c832d5 | 717 | goto drop_dentry; |
19660af7 | 718 | } |
e5c832d5 LT |
719 | |
720 | /* | |
721 | * Sequence counts matched. Now make sure that the root is | |
722 | * still valid and get it if required. | |
723 | */ | |
724 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { | |
5a8d87e8 AV |
725 | if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { |
726 | rcu_read_unlock(); | |
727 | dput(dentry); | |
728 | return -ECHILD; | |
7973387a | 729 | } |
31e6b01f | 730 | } |
31e6b01f | 731 | |
8b61e74f | 732 | rcu_read_unlock(); |
31e6b01f | 733 | return 0; |
19660af7 | 734 | |
e5c832d5 | 735 | drop_dentry: |
8b61e74f | 736 | rcu_read_unlock(); |
15570086 | 737 | dput(dentry); |
d0d27277 | 738 | goto drop_root_mnt; |
7973387a AV |
739 | out2: |
740 | nd->path.mnt = NULL; | |
741 | out1: | |
742 | nd->path.dentry = NULL; | |
e5c832d5 | 743 | out: |
8b61e74f | 744 | rcu_read_unlock(); |
d0d27277 LT |
745 | drop_root_mnt: |
746 | if (!(nd->flags & LOOKUP_ROOT)) | |
747 | nd->root.mnt = NULL; | |
31e6b01f NP |
748 | return -ECHILD; |
749 | } | |
750 | ||
7973387a AV |
751 | static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) |
752 | { | |
753 | if (unlikely(!legitimize_path(nd, link, seq))) { | |
754 | drop_links(nd); | |
755 | nd->depth = 0; | |
756 | nd->flags &= ~LOOKUP_RCU; | |
757 | nd->path.mnt = NULL; | |
758 | nd->path.dentry = NULL; | |
759 | if (!(nd->flags & LOOKUP_ROOT)) | |
760 | nd->root.mnt = NULL; | |
761 | rcu_read_unlock(); | |
762 | } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { | |
763 | return 0; | |
764 | } | |
765 | path_put(link); | |
766 | return -ECHILD; | |
767 | } | |
768 | ||
4ce16ef3 | 769 | static inline int d_revalidate(struct dentry *dentry, unsigned int flags) |
34286d66 | 770 | { |
4ce16ef3 | 771 | return dentry->d_op->d_revalidate(dentry, flags); |
34286d66 NP |
772 | } |
773 | ||
9f1fafee AV |
774 | /** |
775 | * complete_walk - successful completion of path walk | |
776 | * @nd: pointer nameidata | |
39159de2 | 777 | * |
9f1fafee AV |
778 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
779 | * Revalidate the final result, unless we'd already done that during | |
780 | * the path walk or the filesystem doesn't ask for it. Return 0 on | |
781 | * success, -error on failure. In case of failure caller does not | |
782 | * need to drop nd->path. | |
39159de2 | 783 | */ |
9f1fafee | 784 | static int complete_walk(struct nameidata *nd) |
39159de2 | 785 | { |
16c2cd71 | 786 | struct dentry *dentry = nd->path.dentry; |
39159de2 | 787 | int status; |
39159de2 | 788 | |
9f1fafee | 789 | if (nd->flags & LOOKUP_RCU) { |
9f1fafee AV |
790 | if (!(nd->flags & LOOKUP_ROOT)) |
791 | nd->root.mnt = NULL; | |
6e9918b7 | 792 | if (unlikely(unlazy_walk(nd, NULL, 0))) |
9f1fafee | 793 | return -ECHILD; |
9f1fafee AV |
794 | } |
795 | ||
16c2cd71 AV |
796 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
797 | return 0; | |
798 | ||
ecf3d1f1 | 799 | if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) |
39159de2 JL |
800 | return 0; |
801 | ||
ecf3d1f1 | 802 | status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); |
39159de2 JL |
803 | if (status > 0) |
804 | return 0; | |
805 | ||
16c2cd71 | 806 | if (!status) |
39159de2 | 807 | status = -ESTALE; |
16c2cd71 | 808 | |
39159de2 JL |
809 | return status; |
810 | } | |
811 | ||
18d8c860 | 812 | static void set_root(struct nameidata *nd) |
31e6b01f | 813 | { |
7bd88377 | 814 | struct fs_struct *fs = current->fs; |
c28cc364 | 815 | |
9e6697e2 AV |
816 | if (nd->flags & LOOKUP_RCU) { |
817 | unsigned seq; | |
818 | ||
819 | do { | |
820 | seq = read_seqcount_begin(&fs->seq); | |
821 | nd->root = fs->root; | |
822 | nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); | |
823 | } while (read_seqcount_retry(&fs->seq, seq)); | |
824 | } else { | |
825 | get_fs_root(fs, &nd->root); | |
826 | } | |
31e6b01f NP |
827 | } |
828 | ||
1d957f9b | 829 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
830 | { |
831 | dput(path->dentry); | |
4ac91378 | 832 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
833 | mntput(path->mnt); |
834 | } | |
835 | ||
7b9337aa NP |
836 | static inline void path_to_nameidata(const struct path *path, |
837 | struct nameidata *nd) | |
051d3812 | 838 | { |
31e6b01f NP |
839 | if (!(nd->flags & LOOKUP_RCU)) { |
840 | dput(nd->path.dentry); | |
841 | if (nd->path.mnt != path->mnt) | |
842 | mntput(nd->path.mnt); | |
9a229683 | 843 | } |
31e6b01f | 844 | nd->path.mnt = path->mnt; |
4ac91378 | 845 | nd->path.dentry = path->dentry; |
051d3812 IK |
846 | } |
847 | ||
248fb5b9 AV |
848 | static int nd_jump_root(struct nameidata *nd) |
849 | { | |
850 | if (nd->flags & LOOKUP_RCU) { | |
851 | struct dentry *d; | |
852 | nd->path = nd->root; | |
853 | d = nd->path.dentry; | |
854 | nd->inode = d->d_inode; | |
855 | nd->seq = nd->root_seq; | |
856 | if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) | |
857 | return -ECHILD; | |
858 | } else { | |
859 | path_put(&nd->path); | |
860 | nd->path = nd->root; | |
861 | path_get(&nd->path); | |
862 | nd->inode = nd->path.dentry->d_inode; | |
863 | } | |
864 | nd->flags |= LOOKUP_JUMPED; | |
865 | return 0; | |
866 | } | |
867 | ||
b5fb63c1 | 868 | /* |
6b255391 | 869 | * Helper to directly jump to a known parsed path from ->get_link, |
b5fb63c1 CH |
870 | * caller must have taken a reference to path beforehand. |
871 | */ | |
6e77137b | 872 | void nd_jump_link(struct path *path) |
b5fb63c1 | 873 | { |
6e77137b | 874 | struct nameidata *nd = current->nameidata; |
b5fb63c1 CH |
875 | path_put(&nd->path); |
876 | ||
877 | nd->path = *path; | |
878 | nd->inode = nd->path.dentry->d_inode; | |
879 | nd->flags |= LOOKUP_JUMPED; | |
b5fb63c1 CH |
880 | } |
881 | ||
b9ff4429 | 882 | static inline void put_link(struct nameidata *nd) |
574197e0 | 883 | { |
21c3003d | 884 | struct saved *last = nd->stack + --nd->depth; |
fceef393 | 885 | do_delayed_call(&last->done); |
6548fae2 AV |
886 | if (!(nd->flags & LOOKUP_RCU)) |
887 | path_put(&last->link); | |
574197e0 AV |
888 | } |
889 | ||
561ec64a LT |
890 | int sysctl_protected_symlinks __read_mostly = 0; |
891 | int sysctl_protected_hardlinks __read_mostly = 0; | |
800179c9 KC |
892 | |
893 | /** | |
894 | * may_follow_link - Check symlink following for unsafe situations | |
55852635 | 895 | * @nd: nameidata pathwalk data |
800179c9 KC |
896 | * |
897 | * In the case of the sysctl_protected_symlinks sysctl being enabled, | |
898 | * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is | |
899 | * in a sticky world-writable directory. This is to protect privileged | |
900 | * processes from failing races against path names that may change out | |
901 | * from under them by way of other users creating malicious symlinks. | |
902 | * It will permit symlinks to be followed only when outside a sticky | |
903 | * world-writable directory, or when the uid of the symlink and follower | |
904 | * match, or when the directory owner matches the symlink's owner. | |
905 | * | |
906 | * Returns 0 if following the symlink is allowed, -ve on error. | |
907 | */ | |
fec2fa24 | 908 | static inline int may_follow_link(struct nameidata *nd) |
800179c9 KC |
909 | { |
910 | const struct inode *inode; | |
911 | const struct inode *parent; | |
2d7f9e2a | 912 | kuid_t puid; |
800179c9 KC |
913 | |
914 | if (!sysctl_protected_symlinks) | |
915 | return 0; | |
916 | ||
917 | /* Allowed if owner and follower match. */ | |
fceef393 | 918 | inode = nd->link_inode; |
81abe27b | 919 | if (uid_eq(current_cred()->fsuid, inode->i_uid)) |
800179c9 KC |
920 | return 0; |
921 | ||
922 | /* Allowed if parent directory not sticky and world-writable. */ | |
aa65fa35 | 923 | parent = nd->inode; |
800179c9 KC |
924 | if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) |
925 | return 0; | |
926 | ||
927 | /* Allowed if parent directory and link owner match. */ | |
2d7f9e2a SF |
928 | puid = parent->i_uid; |
929 | if (uid_valid(puid) && uid_eq(puid, inode->i_uid)) | |
800179c9 KC |
930 | return 0; |
931 | ||
31956502 AV |
932 | if (nd->flags & LOOKUP_RCU) |
933 | return -ECHILD; | |
934 | ||
1cf2665b | 935 | audit_log_link_denied("follow_link", &nd->stack[0].link); |
800179c9 KC |
936 | return -EACCES; |
937 | } | |
938 | ||
939 | /** | |
940 | * safe_hardlink_source - Check for safe hardlink conditions | |
941 | * @inode: the source inode to hardlink from | |
942 | * | |
943 | * Return false if at least one of the following conditions: | |
944 | * - inode is not a regular file | |
945 | * - inode is setuid | |
946 | * - inode is setgid and group-exec | |
947 | * - access failure for read and write | |
948 | * | |
949 | * Otherwise returns true. | |
950 | */ | |
951 | static bool safe_hardlink_source(struct inode *inode) | |
952 | { | |
953 | umode_t mode = inode->i_mode; | |
954 | ||
955 | /* Special files should not get pinned to the filesystem. */ | |
956 | if (!S_ISREG(mode)) | |
957 | return false; | |
958 | ||
959 | /* Setuid files should not get pinned to the filesystem. */ | |
960 | if (mode & S_ISUID) | |
961 | return false; | |
962 | ||
963 | /* Executable setgid files should not get pinned to the filesystem. */ | |
964 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) | |
965 | return false; | |
966 | ||
967 | /* Hardlinking to unreadable or unwritable sources is dangerous. */ | |
968 | if (inode_permission(inode, MAY_READ | MAY_WRITE)) | |
969 | return false; | |
970 | ||
971 | return true; | |
972 | } | |
973 | ||
974 | /** | |
975 | * may_linkat - Check permissions for creating a hardlink | |
976 | * @link: the source to hardlink from | |
977 | * | |
978 | * Block hardlink when all of: | |
979 | * - sysctl_protected_hardlinks enabled | |
980 | * - fsuid does not match inode | |
981 | * - hardlink source is unsafe (see safe_hardlink_source() above) | |
f2ca3796 | 982 | * - not CAP_FOWNER in a namespace with the inode owner uid mapped |
800179c9 KC |
983 | * |
984 | * Returns 0 if successful, -ve on error. | |
985 | */ | |
986 | static int may_linkat(struct path *link) | |
987 | { | |
800179c9 KC |
988 | struct inode *inode; |
989 | ||
990 | if (!sysctl_protected_hardlinks) | |
991 | return 0; | |
992 | ||
800179c9 KC |
993 | inode = link->dentry->d_inode; |
994 | ||
995 | /* Source inode owner (or CAP_FOWNER) can hardlink all they like, | |
996 | * otherwise, it must be a safe source. | |
997 | */ | |
f2ca3796 | 998 | if (inode_owner_or_capable(inode) || safe_hardlink_source(inode)) |
800179c9 KC |
999 | return 0; |
1000 | ||
a51d9eaa | 1001 | audit_log_link_denied("linkat", link); |
800179c9 KC |
1002 | return -EPERM; |
1003 | } | |
1004 | ||
3b2e7f75 AV |
1005 | static __always_inline |
1006 | const char *get_link(struct nameidata *nd) | |
1da177e4 | 1007 | { |
ab104923 | 1008 | struct saved *last = nd->stack + nd->depth - 1; |
1cf2665b | 1009 | struct dentry *dentry = last->link.dentry; |
fceef393 | 1010 | struct inode *inode = nd->link_inode; |
6d7b5aae | 1011 | int error; |
0a959df5 | 1012 | const char *res; |
1da177e4 | 1013 | |
8fa9dd24 N |
1014 | if (!(nd->flags & LOOKUP_RCU)) { |
1015 | touch_atime(&last->link); | |
1016 | cond_resched(); | |
1017 | } else if (atime_needs_update(&last->link, inode)) { | |
bc40aee0 AV |
1018 | if (unlikely(unlazy_walk(nd, NULL, 0))) |
1019 | return ERR_PTR(-ECHILD); | |
8fa9dd24 | 1020 | touch_atime(&last->link); |
bc40aee0 | 1021 | } |
574197e0 | 1022 | |
bda0be7a N |
1023 | error = security_inode_follow_link(dentry, inode, |
1024 | nd->flags & LOOKUP_RCU); | |
1025 | if (unlikely(error)) | |
6920a440 | 1026 | return ERR_PTR(error); |
36f3b4f6 | 1027 | |
86acdca1 | 1028 | nd->last_type = LAST_BIND; |
d4dee48b AV |
1029 | res = inode->i_link; |
1030 | if (!res) { | |
fceef393 AV |
1031 | const char * (*get)(struct dentry *, struct inode *, |
1032 | struct delayed_call *); | |
1033 | get = inode->i_op->get_link; | |
8c1b4566 | 1034 | if (nd->flags & LOOKUP_RCU) { |
fceef393 | 1035 | res = get(NULL, inode, &last->done); |
6b255391 AV |
1036 | if (res == ERR_PTR(-ECHILD)) { |
1037 | if (unlikely(unlazy_walk(nd, NULL, 0))) | |
1038 | return ERR_PTR(-ECHILD); | |
fceef393 | 1039 | res = get(dentry, inode, &last->done); |
6b255391 AV |
1040 | } |
1041 | } else { | |
fceef393 | 1042 | res = get(dentry, inode, &last->done); |
8c1b4566 | 1043 | } |
fceef393 | 1044 | if (IS_ERR_OR_NULL(res)) |
fab51e8a | 1045 | return res; |
fab51e8a AV |
1046 | } |
1047 | if (*res == '/') { | |
9e6697e2 AV |
1048 | if (!nd->root.mnt) |
1049 | set_root(nd); | |
248fb5b9 AV |
1050 | if (unlikely(nd_jump_root(nd))) |
1051 | return ERR_PTR(-ECHILD); | |
fab51e8a AV |
1052 | while (unlikely(*++res == '/')) |
1053 | ; | |
1da177e4 | 1054 | } |
fab51e8a AV |
1055 | if (!*res) |
1056 | res = NULL; | |
0a959df5 AV |
1057 | return res; |
1058 | } | |
6d7b5aae | 1059 | |
f015f126 DH |
1060 | /* |
1061 | * follow_up - Find the mountpoint of path's vfsmount | |
1062 | * | |
1063 | * Given a path, find the mountpoint of its source file system. | |
1064 | * Replace @path with the path of the mountpoint in the parent mount. | |
1065 | * Up is towards /. | |
1066 | * | |
1067 | * Return 1 if we went up a level and 0 if we were already at the | |
1068 | * root. | |
1069 | */ | |
bab77ebf | 1070 | int follow_up(struct path *path) |
1da177e4 | 1071 | { |
0714a533 AV |
1072 | struct mount *mnt = real_mount(path->mnt); |
1073 | struct mount *parent; | |
1da177e4 | 1074 | struct dentry *mountpoint; |
99b7db7b | 1075 | |
48a066e7 | 1076 | read_seqlock_excl(&mount_lock); |
0714a533 | 1077 | parent = mnt->mnt_parent; |
3c0a6163 | 1078 | if (parent == mnt) { |
48a066e7 | 1079 | read_sequnlock_excl(&mount_lock); |
1da177e4 LT |
1080 | return 0; |
1081 | } | |
0714a533 | 1082 | mntget(&parent->mnt); |
a73324da | 1083 | mountpoint = dget(mnt->mnt_mountpoint); |
48a066e7 | 1084 | read_sequnlock_excl(&mount_lock); |
bab77ebf AV |
1085 | dput(path->dentry); |
1086 | path->dentry = mountpoint; | |
1087 | mntput(path->mnt); | |
0714a533 | 1088 | path->mnt = &parent->mnt; |
1da177e4 LT |
1089 | return 1; |
1090 | } | |
4d359507 | 1091 | EXPORT_SYMBOL(follow_up); |
1da177e4 | 1092 | |
b5c84bf6 | 1093 | /* |
9875cf80 DH |
1094 | * Perform an automount |
1095 | * - return -EISDIR to tell follow_managed() to stop and return the path we | |
1096 | * were called with. | |
1da177e4 | 1097 | */ |
756daf26 | 1098 | static int follow_automount(struct path *path, struct nameidata *nd, |
9875cf80 | 1099 | bool *need_mntput) |
31e6b01f | 1100 | { |
9875cf80 | 1101 | struct vfsmount *mnt; |
ea5b778a | 1102 | int err; |
9875cf80 DH |
1103 | |
1104 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) | |
1105 | return -EREMOTE; | |
1106 | ||
0ec26fd0 MS |
1107 | /* We don't want to mount if someone's just doing a stat - |
1108 | * unless they're stat'ing a directory and appended a '/' to | |
1109 | * the name. | |
1110 | * | |
1111 | * We do, however, want to mount if someone wants to open or | |
1112 | * create a file of any type under the mountpoint, wants to | |
1113 | * traverse through the mountpoint or wants to open the | |
1114 | * mounted directory. Also, autofs may mark negative dentries | |
1115 | * as being automount points. These will need the attentions | |
1116 | * of the daemon to instantiate them before they can be used. | |
9875cf80 | 1117 | */ |
756daf26 N |
1118 | if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
1119 | LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && | |
0ec26fd0 MS |
1120 | path->dentry->d_inode) |
1121 | return -EISDIR; | |
1122 | ||
756daf26 N |
1123 | nd->total_link_count++; |
1124 | if (nd->total_link_count >= 40) | |
9875cf80 DH |
1125 | return -ELOOP; |
1126 | ||
1127 | mnt = path->dentry->d_op->d_automount(path); | |
1128 | if (IS_ERR(mnt)) { | |
1129 | /* | |
1130 | * The filesystem is allowed to return -EISDIR here to indicate | |
1131 | * it doesn't want to automount. For instance, autofs would do | |
1132 | * this so that its userspace daemon can mount on this dentry. | |
1133 | * | |
1134 | * However, we can only permit this if it's a terminal point in | |
1135 | * the path being looked up; if it wasn't then the remainder of | |
1136 | * the path is inaccessible and we should say so. | |
1137 | */ | |
756daf26 | 1138 | if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) |
9875cf80 DH |
1139 | return -EREMOTE; |
1140 | return PTR_ERR(mnt); | |
31e6b01f | 1141 | } |
ea5b778a | 1142 | |
9875cf80 DH |
1143 | if (!mnt) /* mount collision */ |
1144 | return 0; | |
31e6b01f | 1145 | |
8aef1884 AV |
1146 | if (!*need_mntput) { |
1147 | /* lock_mount() may release path->mnt on error */ | |
1148 | mntget(path->mnt); | |
1149 | *need_mntput = true; | |
1150 | } | |
19a167af | 1151 | err = finish_automount(mnt, path); |
9875cf80 | 1152 | |
ea5b778a DH |
1153 | switch (err) { |
1154 | case -EBUSY: | |
1155 | /* Someone else made a mount here whilst we were busy */ | |
19a167af | 1156 | return 0; |
ea5b778a | 1157 | case 0: |
8aef1884 | 1158 | path_put(path); |
ea5b778a DH |
1159 | path->mnt = mnt; |
1160 | path->dentry = dget(mnt->mnt_root); | |
ea5b778a | 1161 | return 0; |
19a167af AV |
1162 | default: |
1163 | return err; | |
ea5b778a | 1164 | } |
19a167af | 1165 | |
463ffb2e AV |
1166 | } |
1167 | ||
9875cf80 DH |
1168 | /* |
1169 | * Handle a dentry that is managed in some way. | |
cc53ce53 | 1170 | * - Flagged for transit management (autofs) |
9875cf80 DH |
1171 | * - Flagged as mountpoint |
1172 | * - Flagged as automount point | |
1173 | * | |
1174 | * This may only be called in refwalk mode. | |
1175 | * | |
1176 | * Serialization is taken care of in namespace.c | |
1177 | */ | |
756daf26 | 1178 | static int follow_managed(struct path *path, struct nameidata *nd) |
1da177e4 | 1179 | { |
8aef1884 | 1180 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
9875cf80 DH |
1181 | unsigned managed; |
1182 | bool need_mntput = false; | |
8aef1884 | 1183 | int ret = 0; |
9875cf80 DH |
1184 | |
1185 | /* Given that we're not holding a lock here, we retain the value in a | |
1186 | * local variable for each dentry as we look at it so that we don't see | |
1187 | * the components of that value change under us */ | |
1188 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1189 | managed &= DCACHE_MANAGED_DENTRY, | |
1190 | unlikely(managed != 0)) { | |
cc53ce53 DH |
1191 | /* Allow the filesystem to manage the transit without i_mutex |
1192 | * being held. */ | |
1193 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1194 | BUG_ON(!path->dentry->d_op); | |
1195 | BUG_ON(!path->dentry->d_op->d_manage); | |
1aed3e42 | 1196 | ret = path->dentry->d_op->d_manage(path->dentry, false); |
cc53ce53 | 1197 | if (ret < 0) |
8aef1884 | 1198 | break; |
cc53ce53 DH |
1199 | } |
1200 | ||
9875cf80 DH |
1201 | /* Transit to a mounted filesystem. */ |
1202 | if (managed & DCACHE_MOUNTED) { | |
1203 | struct vfsmount *mounted = lookup_mnt(path); | |
1204 | if (mounted) { | |
1205 | dput(path->dentry); | |
1206 | if (need_mntput) | |
1207 | mntput(path->mnt); | |
1208 | path->mnt = mounted; | |
1209 | path->dentry = dget(mounted->mnt_root); | |
1210 | need_mntput = true; | |
1211 | continue; | |
1212 | } | |
1213 | ||
1214 | /* Something is mounted on this dentry in another | |
1215 | * namespace and/or whatever was mounted there in this | |
48a066e7 AV |
1216 | * namespace got unmounted before lookup_mnt() could |
1217 | * get it */ | |
9875cf80 DH |
1218 | } |
1219 | ||
1220 | /* Handle an automount point */ | |
1221 | if (managed & DCACHE_NEED_AUTOMOUNT) { | |
756daf26 | 1222 | ret = follow_automount(path, nd, &need_mntput); |
9875cf80 | 1223 | if (ret < 0) |
8aef1884 | 1224 | break; |
9875cf80 DH |
1225 | continue; |
1226 | } | |
1227 | ||
1228 | /* We didn't change the current path point */ | |
1229 | break; | |
1da177e4 | 1230 | } |
8aef1884 AV |
1231 | |
1232 | if (need_mntput && path->mnt == mnt) | |
1233 | mntput(path->mnt); | |
e9742b53 AV |
1234 | if (ret == -EISDIR || !ret) |
1235 | ret = 1; | |
8402752e AV |
1236 | if (need_mntput) |
1237 | nd->flags |= LOOKUP_JUMPED; | |
1238 | if (unlikely(ret < 0)) | |
1239 | path_put_conditional(path, nd); | |
1240 | return ret; | |
1da177e4 LT |
1241 | } |
1242 | ||
cc53ce53 | 1243 | int follow_down_one(struct path *path) |
1da177e4 LT |
1244 | { |
1245 | struct vfsmount *mounted; | |
1246 | ||
1c755af4 | 1247 | mounted = lookup_mnt(path); |
1da177e4 | 1248 | if (mounted) { |
9393bd07 AV |
1249 | dput(path->dentry); |
1250 | mntput(path->mnt); | |
1251 | path->mnt = mounted; | |
1252 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
1253 | return 1; |
1254 | } | |
1255 | return 0; | |
1256 | } | |
4d359507 | 1257 | EXPORT_SYMBOL(follow_down_one); |
1da177e4 | 1258 | |
b8faf035 | 1259 | static inline int managed_dentry_rcu(struct dentry *dentry) |
62a7375e | 1260 | { |
b8faf035 N |
1261 | return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? |
1262 | dentry->d_op->d_manage(dentry, true) : 0; | |
62a7375e IK |
1263 | } |
1264 | ||
9875cf80 | 1265 | /* |
287548e4 AV |
1266 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
1267 | * we meet a managed dentry that would need blocking. | |
9875cf80 DH |
1268 | */ |
1269 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, | |
254cf582 | 1270 | struct inode **inode, unsigned *seqp) |
9875cf80 | 1271 | { |
62a7375e | 1272 | for (;;) { |
c7105365 | 1273 | struct mount *mounted; |
62a7375e IK |
1274 | /* |
1275 | * Don't forget we might have a non-mountpoint managed dentry | |
1276 | * that wants to block transit. | |
1277 | */ | |
b8faf035 N |
1278 | switch (managed_dentry_rcu(path->dentry)) { |
1279 | case -ECHILD: | |
1280 | default: | |
ab90911f | 1281 | return false; |
b8faf035 N |
1282 | case -EISDIR: |
1283 | return true; | |
1284 | case 0: | |
1285 | break; | |
1286 | } | |
62a7375e IK |
1287 | |
1288 | if (!d_mountpoint(path->dentry)) | |
b8faf035 | 1289 | return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); |
62a7375e | 1290 | |
474279dc | 1291 | mounted = __lookup_mnt(path->mnt, path->dentry); |
9875cf80 DH |
1292 | if (!mounted) |
1293 | break; | |
c7105365 AV |
1294 | path->mnt = &mounted->mnt; |
1295 | path->dentry = mounted->mnt.mnt_root; | |
a3fbbde7 | 1296 | nd->flags |= LOOKUP_JUMPED; |
254cf582 | 1297 | *seqp = read_seqcount_begin(&path->dentry->d_seq); |
59430262 LT |
1298 | /* |
1299 | * Update the inode too. We don't need to re-check the | |
1300 | * dentry sequence number here after this d_inode read, | |
1301 | * because a mount-point is always pinned. | |
1302 | */ | |
1303 | *inode = path->dentry->d_inode; | |
9875cf80 | 1304 | } |
f5be3e29 | 1305 | return !read_seqretry(&mount_lock, nd->m_seq) && |
b8faf035 | 1306 | !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); |
287548e4 AV |
1307 | } |
1308 | ||
31e6b01f NP |
1309 | static int follow_dotdot_rcu(struct nameidata *nd) |
1310 | { | |
4023bfc9 | 1311 | struct inode *inode = nd->inode; |
31e6b01f | 1312 | |
9875cf80 | 1313 | while (1) { |
aed434ad | 1314 | if (path_equal(&nd->path, &nd->root)) |
31e6b01f | 1315 | break; |
31e6b01f NP |
1316 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
1317 | struct dentry *old = nd->path.dentry; | |
1318 | struct dentry *parent = old->d_parent; | |
1319 | unsigned seq; | |
1320 | ||
4023bfc9 | 1321 | inode = parent->d_inode; |
31e6b01f | 1322 | seq = read_seqcount_begin(&parent->d_seq); |
aed434ad AV |
1323 | if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) |
1324 | return -ECHILD; | |
31e6b01f NP |
1325 | nd->path.dentry = parent; |
1326 | nd->seq = seq; | |
397d425d EB |
1327 | if (unlikely(!path_connected(&nd->path))) |
1328 | return -ENOENT; | |
31e6b01f | 1329 | break; |
aed434ad AV |
1330 | } else { |
1331 | struct mount *mnt = real_mount(nd->path.mnt); | |
1332 | struct mount *mparent = mnt->mnt_parent; | |
1333 | struct dentry *mountpoint = mnt->mnt_mountpoint; | |
1334 | struct inode *inode2 = mountpoint->d_inode; | |
1335 | unsigned seq = read_seqcount_begin(&mountpoint->d_seq); | |
1336 | if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) | |
1337 | return -ECHILD; | |
1338 | if (&mparent->mnt == nd->path.mnt) | |
1339 | break; | |
1340 | /* we know that mountpoint was pinned */ | |
1341 | nd->path.dentry = mountpoint; | |
1342 | nd->path.mnt = &mparent->mnt; | |
1343 | inode = inode2; | |
1344 | nd->seq = seq; | |
31e6b01f | 1345 | } |
31e6b01f | 1346 | } |
aed434ad | 1347 | while (unlikely(d_mountpoint(nd->path.dentry))) { |
b37199e6 AV |
1348 | struct mount *mounted; |
1349 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); | |
aed434ad AV |
1350 | if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) |
1351 | return -ECHILD; | |
b37199e6 AV |
1352 | if (!mounted) |
1353 | break; | |
1354 | nd->path.mnt = &mounted->mnt; | |
1355 | nd->path.dentry = mounted->mnt.mnt_root; | |
4023bfc9 | 1356 | inode = nd->path.dentry->d_inode; |
b37199e6 | 1357 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); |
b37199e6 | 1358 | } |
4023bfc9 | 1359 | nd->inode = inode; |
31e6b01f NP |
1360 | return 0; |
1361 | } | |
1362 | ||
cc53ce53 DH |
1363 | /* |
1364 | * Follow down to the covering mount currently visible to userspace. At each | |
1365 | * point, the filesystem owning that dentry may be queried as to whether the | |
1366 | * caller is permitted to proceed or not. | |
cc53ce53 | 1367 | */ |
7cc90cc3 | 1368 | int follow_down(struct path *path) |
cc53ce53 DH |
1369 | { |
1370 | unsigned managed; | |
1371 | int ret; | |
1372 | ||
1373 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1374 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { | |
1375 | /* Allow the filesystem to manage the transit without i_mutex | |
1376 | * being held. | |
1377 | * | |
1378 | * We indicate to the filesystem if someone is trying to mount | |
1379 | * something here. This gives autofs the chance to deny anyone | |
1380 | * other than its daemon the right to mount on its | |
1381 | * superstructure. | |
1382 | * | |
1383 | * The filesystem may sleep at this point. | |
1384 | */ | |
1385 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1386 | BUG_ON(!path->dentry->d_op); | |
1387 | BUG_ON(!path->dentry->d_op->d_manage); | |
ab90911f | 1388 | ret = path->dentry->d_op->d_manage( |
1aed3e42 | 1389 | path->dentry, false); |
cc53ce53 DH |
1390 | if (ret < 0) |
1391 | return ret == -EISDIR ? 0 : ret; | |
1392 | } | |
1393 | ||
1394 | /* Transit to a mounted filesystem. */ | |
1395 | if (managed & DCACHE_MOUNTED) { | |
1396 | struct vfsmount *mounted = lookup_mnt(path); | |
1397 | if (!mounted) | |
1398 | break; | |
1399 | dput(path->dentry); | |
1400 | mntput(path->mnt); | |
1401 | path->mnt = mounted; | |
1402 | path->dentry = dget(mounted->mnt_root); | |
1403 | continue; | |
1404 | } | |
1405 | ||
1406 | /* Don't handle automount points here */ | |
1407 | break; | |
1408 | } | |
1409 | return 0; | |
1410 | } | |
4d359507 | 1411 | EXPORT_SYMBOL(follow_down); |
cc53ce53 | 1412 | |
9875cf80 DH |
1413 | /* |
1414 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() | |
1415 | */ | |
1416 | static void follow_mount(struct path *path) | |
1417 | { | |
1418 | while (d_mountpoint(path->dentry)) { | |
1419 | struct vfsmount *mounted = lookup_mnt(path); | |
1420 | if (!mounted) | |
1421 | break; | |
1422 | dput(path->dentry); | |
1423 | mntput(path->mnt); | |
1424 | path->mnt = mounted; | |
1425 | path->dentry = dget(mounted->mnt_root); | |
1426 | } | |
1427 | } | |
1428 | ||
eedf265a EB |
1429 | static int path_parent_directory(struct path *path) |
1430 | { | |
1431 | struct dentry *old = path->dentry; | |
1432 | /* rare case of legitimate dget_parent()... */ | |
1433 | path->dentry = dget_parent(path->dentry); | |
1434 | dput(old); | |
1435 | if (unlikely(!path_connected(path))) | |
1436 | return -ENOENT; | |
1437 | return 0; | |
1438 | } | |
1439 | ||
397d425d | 1440 | static int follow_dotdot(struct nameidata *nd) |
1da177e4 LT |
1441 | { |
1442 | while(1) { | |
2a737871 AV |
1443 | if (nd->path.dentry == nd->root.dentry && |
1444 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
1445 | break; |
1446 | } | |
4ac91378 | 1447 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
eedf265a EB |
1448 | int ret = path_parent_directory(&nd->path); |
1449 | if (ret) | |
1450 | return ret; | |
1da177e4 LT |
1451 | break; |
1452 | } | |
3088dd70 | 1453 | if (!follow_up(&nd->path)) |
1da177e4 | 1454 | break; |
1da177e4 | 1455 | } |
79ed0226 | 1456 | follow_mount(&nd->path); |
31e6b01f | 1457 | nd->inode = nd->path.dentry->d_inode; |
397d425d | 1458 | return 0; |
1da177e4 LT |
1459 | } |
1460 | ||
baa03890 | 1461 | /* |
bad61189 MS |
1462 | * This looks up the name in dcache, possibly revalidates the old dentry and |
1463 | * allocates a new one if not found or not valid. In the need_lookup argument | |
1464 | * returns whether i_op->lookup is necessary. | |
baa03890 | 1465 | */ |
e3c13928 AV |
1466 | static struct dentry *lookup_dcache(const struct qstr *name, |
1467 | struct dentry *dir, | |
6c51e513 | 1468 | unsigned int flags) |
baa03890 | 1469 | { |
baa03890 | 1470 | struct dentry *dentry; |
bad61189 | 1471 | int error; |
baa03890 | 1472 | |
bad61189 MS |
1473 | dentry = d_lookup(dir, name); |
1474 | if (dentry) { | |
39e3c955 | 1475 | if (dentry->d_flags & DCACHE_OP_REVALIDATE) { |
201f956e | 1476 | error = d_revalidate(dentry, flags); |
bad61189 | 1477 | if (unlikely(error <= 0)) { |
74ff0ffc | 1478 | if (!error) |
5542aa2f | 1479 | d_invalidate(dentry); |
74ff0ffc AV |
1480 | dput(dentry); |
1481 | return ERR_PTR(error); | |
bad61189 MS |
1482 | } |
1483 | } | |
1484 | } | |
baa03890 NP |
1485 | return dentry; |
1486 | } | |
1487 | ||
44396f4b | 1488 | /* |
13a2c3be BF |
1489 | * Call i_op->lookup on the dentry. The dentry must be negative and |
1490 | * unhashed. | |
bad61189 MS |
1491 | * |
1492 | * dir->d_inode->i_mutex must be held | |
44396f4b | 1493 | */ |
bad61189 | 1494 | static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, |
72bd866a | 1495 | unsigned int flags) |
44396f4b | 1496 | { |
44396f4b JB |
1497 | struct dentry *old; |
1498 | ||
1499 | /* Don't create child dentry for a dead directory. */ | |
bad61189 | 1500 | if (unlikely(IS_DEADDIR(dir))) { |
e188dc02 | 1501 | dput(dentry); |
44396f4b | 1502 | return ERR_PTR(-ENOENT); |
e188dc02 | 1503 | } |
44396f4b | 1504 | |
72bd866a | 1505 | old = dir->i_op->lookup(dir, dentry, flags); |
44396f4b JB |
1506 | if (unlikely(old)) { |
1507 | dput(dentry); | |
1508 | dentry = old; | |
1509 | } | |
1510 | return dentry; | |
1511 | } | |
1512 | ||
e3c13928 | 1513 | static struct dentry *__lookup_hash(const struct qstr *name, |
72bd866a | 1514 | struct dentry *base, unsigned int flags) |
a3255546 | 1515 | { |
6c51e513 | 1516 | struct dentry *dentry = lookup_dcache(name, base, flags); |
a3255546 | 1517 | |
6c51e513 | 1518 | if (dentry) |
bad61189 | 1519 | return dentry; |
a3255546 | 1520 | |
6c51e513 AV |
1521 | dentry = d_alloc(base, name); |
1522 | if (unlikely(!dentry)) | |
1523 | return ERR_PTR(-ENOMEM); | |
1524 | ||
72bd866a | 1525 | return lookup_real(base->d_inode, dentry, flags); |
a3255546 AV |
1526 | } |
1527 | ||
e97cdc87 | 1528 | static int lookup_fast(struct nameidata *nd, |
254cf582 AV |
1529 | struct path *path, struct inode **inode, |
1530 | unsigned *seqp) | |
1da177e4 | 1531 | { |
4ac91378 | 1532 | struct vfsmount *mnt = nd->path.mnt; |
31e6b01f | 1533 | struct dentry *dentry, *parent = nd->path.dentry; |
5a18fff2 | 1534 | int status = 1; |
9875cf80 DH |
1535 | int err; |
1536 | ||
b04f784e NP |
1537 | /* |
1538 | * Rename seqlock is not required here because in the off chance | |
5d0f49c1 AV |
1539 | * of a false negative due to a concurrent rename, the caller is |
1540 | * going to fall back to non-racy lookup. | |
b04f784e | 1541 | */ |
31e6b01f NP |
1542 | if (nd->flags & LOOKUP_RCU) { |
1543 | unsigned seq; | |
766c4cbf | 1544 | bool negative; |
da53be12 | 1545 | dentry = __d_lookup_rcu(parent, &nd->last, &seq); |
5d0f49c1 AV |
1546 | if (unlikely(!dentry)) { |
1547 | if (unlazy_walk(nd, NULL, 0)) | |
1548 | return -ECHILD; | |
e9742b53 | 1549 | return 0; |
5d0f49c1 | 1550 | } |
5a18fff2 | 1551 | |
12f8ad4b LT |
1552 | /* |
1553 | * This sequence count validates that the inode matches | |
1554 | * the dentry name information from lookup. | |
1555 | */ | |
63afdfc7 | 1556 | *inode = d_backing_inode(dentry); |
766c4cbf | 1557 | negative = d_is_negative(dentry); |
5d0f49c1 | 1558 | if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) |
12f8ad4b LT |
1559 | return -ECHILD; |
1560 | ||
1561 | /* | |
1562 | * This sequence count validates that the parent had no | |
1563 | * changes while we did the lookup of the dentry above. | |
1564 | * | |
1565 | * The memory barrier in read_seqcount_begin of child is | |
1566 | * enough, we can use __read_seqcount_retry here. | |
1567 | */ | |
5d0f49c1 | 1568 | if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq))) |
31e6b01f | 1569 | return -ECHILD; |
5a18fff2 | 1570 | |
254cf582 | 1571 | *seqp = seq; |
5d0f49c1 | 1572 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) |
4ce16ef3 | 1573 | status = d_revalidate(dentry, nd->flags); |
5d0f49c1 AV |
1574 | if (unlikely(status <= 0)) { |
1575 | if (unlazy_walk(nd, dentry, seq)) | |
1576 | return -ECHILD; | |
1577 | if (status == -ECHILD) | |
1578 | status = d_revalidate(dentry, nd->flags); | |
1579 | } else { | |
1580 | /* | |
1581 | * Note: do negative dentry check after revalidation in | |
1582 | * case that drops it. | |
1583 | */ | |
1584 | if (unlikely(negative)) | |
1585 | return -ENOENT; | |
1586 | path->mnt = mnt; | |
1587 | path->dentry = dentry; | |
1588 | if (likely(__follow_mount_rcu(nd, path, inode, seqp))) | |
e9742b53 | 1589 | return 1; |
5d0f49c1 AV |
1590 | if (unlazy_walk(nd, dentry, seq)) |
1591 | return -ECHILD; | |
24643087 | 1592 | } |
5a18fff2 | 1593 | } else { |
e97cdc87 | 1594 | dentry = __d_lookup(parent, &nd->last); |
5d0f49c1 | 1595 | if (unlikely(!dentry)) |
e9742b53 | 1596 | return 0; |
5d0f49c1 AV |
1597 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) |
1598 | status = d_revalidate(dentry, nd->flags); | |
9875cf80 | 1599 | } |
5a18fff2 | 1600 | if (unlikely(status <= 0)) { |
e9742b53 | 1601 | if (!status) |
5d0f49c1 | 1602 | d_invalidate(dentry); |
5542aa2f | 1603 | dput(dentry); |
5d0f49c1 | 1604 | return status; |
24643087 | 1605 | } |
766c4cbf AV |
1606 | if (unlikely(d_is_negative(dentry))) { |
1607 | dput(dentry); | |
1608 | return -ENOENT; | |
1609 | } | |
5d0f49c1 | 1610 | |
9875cf80 DH |
1611 | path->mnt = mnt; |
1612 | path->dentry = dentry; | |
756daf26 | 1613 | err = follow_managed(path, nd); |
e9742b53 | 1614 | if (likely(err > 0)) |
63afdfc7 | 1615 | *inode = d_backing_inode(path->dentry); |
8402752e | 1616 | return err; |
697f514d MS |
1617 | } |
1618 | ||
1619 | /* Fast lookup failed, do it the slow way */ | |
e3c13928 AV |
1620 | static struct dentry *lookup_slow(const struct qstr *name, |
1621 | struct dentry *dir, | |
1622 | unsigned int flags) | |
697f514d | 1623 | { |
94bdd655 | 1624 | struct dentry *dentry = ERR_PTR(-ENOENT), *old; |
1936386e | 1625 | struct inode *inode = dir->d_inode; |
d9171b93 | 1626 | DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); |
1936386e | 1627 | |
9902af79 | 1628 | inode_lock_shared(inode); |
1936386e | 1629 | /* Don't go there if it's already dead */ |
94bdd655 AV |
1630 | if (unlikely(IS_DEADDIR(inode))) |
1631 | goto out; | |
1632 | again: | |
d9171b93 | 1633 | dentry = d_alloc_parallel(dir, name, &wq); |
94bdd655 AV |
1634 | if (IS_ERR(dentry)) |
1635 | goto out; | |
1636 | if (unlikely(!d_in_lookup(dentry))) { | |
949a852e AV |
1637 | if ((dentry->d_flags & DCACHE_OP_REVALIDATE) && |
1638 | !(flags & LOOKUP_NO_REVAL)) { | |
1639 | int error = d_revalidate(dentry, flags); | |
1640 | if (unlikely(error <= 0)) { | |
94bdd655 | 1641 | if (!error) { |
949a852e | 1642 | d_invalidate(dentry); |
94bdd655 AV |
1643 | dput(dentry); |
1644 | goto again; | |
1645 | } | |
949a852e AV |
1646 | dput(dentry); |
1647 | dentry = ERR_PTR(error); | |
1648 | } | |
1649 | } | |
94bdd655 AV |
1650 | } else { |
1651 | old = inode->i_op->lookup(inode, dentry, flags); | |
1652 | d_lookup_done(dentry); | |
1653 | if (unlikely(old)) { | |
1654 | dput(dentry); | |
1655 | dentry = old; | |
949a852e AV |
1656 | } |
1657 | } | |
94bdd655 | 1658 | out: |
9902af79 | 1659 | inode_unlock_shared(inode); |
e3c13928 | 1660 | return dentry; |
1da177e4 LT |
1661 | } |
1662 | ||
52094c8a AV |
1663 | static inline int may_lookup(struct nameidata *nd) |
1664 | { | |
1665 | if (nd->flags & LOOKUP_RCU) { | |
4ad5abb3 | 1666 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
52094c8a AV |
1667 | if (err != -ECHILD) |
1668 | return err; | |
6e9918b7 | 1669 | if (unlazy_walk(nd, NULL, 0)) |
52094c8a AV |
1670 | return -ECHILD; |
1671 | } | |
4ad5abb3 | 1672 | return inode_permission(nd->inode, MAY_EXEC); |
52094c8a AV |
1673 | } |
1674 | ||
9856fa1b AV |
1675 | static inline int handle_dots(struct nameidata *nd, int type) |
1676 | { | |
1677 | if (type == LAST_DOTDOT) { | |
9e6697e2 AV |
1678 | if (!nd->root.mnt) |
1679 | set_root(nd); | |
9856fa1b | 1680 | if (nd->flags & LOOKUP_RCU) { |
70291aec | 1681 | return follow_dotdot_rcu(nd); |
9856fa1b | 1682 | } else |
397d425d | 1683 | return follow_dotdot(nd); |
9856fa1b AV |
1684 | } |
1685 | return 0; | |
1686 | } | |
1687 | ||
181548c0 AV |
1688 | static int pick_link(struct nameidata *nd, struct path *link, |
1689 | struct inode *inode, unsigned seq) | |
d63ff28f | 1690 | { |
626de996 | 1691 | int error; |
1cf2665b | 1692 | struct saved *last; |
756daf26 | 1693 | if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { |
626de996 AV |
1694 | path_to_nameidata(link, nd); |
1695 | return -ELOOP; | |
1696 | } | |
bc40aee0 | 1697 | if (!(nd->flags & LOOKUP_RCU)) { |
7973387a AV |
1698 | if (link->mnt == nd->path.mnt) |
1699 | mntget(link->mnt); | |
d63ff28f | 1700 | } |
626de996 AV |
1701 | error = nd_alloc_stack(nd); |
1702 | if (unlikely(error)) { | |
bc40aee0 AV |
1703 | if (error == -ECHILD) { |
1704 | if (unlikely(unlazy_link(nd, link, seq))) | |
1705 | return -ECHILD; | |
1706 | error = nd_alloc_stack(nd); | |
1707 | } | |
1708 | if (error) { | |
1709 | path_put(link); | |
1710 | return error; | |
1711 | } | |
626de996 AV |
1712 | } |
1713 | ||
ab104923 | 1714 | last = nd->stack + nd->depth++; |
1cf2665b | 1715 | last->link = *link; |
fceef393 AV |
1716 | clear_delayed_call(&last->done); |
1717 | nd->link_inode = inode; | |
0450b2d1 | 1718 | last->seq = seq; |
d63ff28f AV |
1719 | return 1; |
1720 | } | |
1721 | ||
3ddcd056 LT |
1722 | /* |
1723 | * Do we need to follow links? We _really_ want to be able | |
1724 | * to do this check without having to look at inode->i_op, | |
1725 | * so we keep a cache of "no, this doesn't need follow_link" | |
1726 | * for the common case. | |
1727 | */ | |
254cf582 | 1728 | static inline int should_follow_link(struct nameidata *nd, struct path *link, |
181548c0 AV |
1729 | int follow, |
1730 | struct inode *inode, unsigned seq) | |
3ddcd056 | 1731 | { |
d63ff28f AV |
1732 | if (likely(!d_is_symlink(link->dentry))) |
1733 | return 0; | |
1734 | if (!follow) | |
1735 | return 0; | |
a7f77542 AV |
1736 | /* make sure that d_is_symlink above matches inode */ |
1737 | if (nd->flags & LOOKUP_RCU) { | |
1738 | if (read_seqcount_retry(&link->dentry->d_seq, seq)) | |
1739 | return -ECHILD; | |
1740 | } | |
181548c0 | 1741 | return pick_link(nd, link, inode, seq); |
3ddcd056 LT |
1742 | } |
1743 | ||
4693a547 AV |
1744 | enum {WALK_GET = 1, WALK_PUT = 2}; |
1745 | ||
1746 | static int walk_component(struct nameidata *nd, int flags) | |
ce57dfc1 | 1747 | { |
caa85634 | 1748 | struct path path; |
ce57dfc1 | 1749 | struct inode *inode; |
254cf582 | 1750 | unsigned seq; |
ce57dfc1 AV |
1751 | int err; |
1752 | /* | |
1753 | * "." and ".." are special - ".." especially so because it has | |
1754 | * to be able to know about the current root directory and | |
1755 | * parent relationships. | |
1756 | */ | |
4693a547 AV |
1757 | if (unlikely(nd->last_type != LAST_NORM)) { |
1758 | err = handle_dots(nd, nd->last_type); | |
1759 | if (flags & WALK_PUT) | |
1760 | put_link(nd); | |
1761 | return err; | |
1762 | } | |
254cf582 | 1763 | err = lookup_fast(nd, &path, &inode, &seq); |
e9742b53 | 1764 | if (unlikely(err <= 0)) { |
697f514d | 1765 | if (err < 0) |
f0a9ba70 | 1766 | return err; |
e3c13928 AV |
1767 | path.dentry = lookup_slow(&nd->last, nd->path.dentry, |
1768 | nd->flags); | |
1769 | if (IS_ERR(path.dentry)) | |
1770 | return PTR_ERR(path.dentry); | |
7500c38a | 1771 | |
e3c13928 AV |
1772 | path.mnt = nd->path.mnt; |
1773 | err = follow_managed(&path, nd); | |
1774 | if (unlikely(err < 0)) | |
f0a9ba70 | 1775 | return err; |
697f514d | 1776 | |
7500c38a AV |
1777 | if (unlikely(d_is_negative(path.dentry))) { |
1778 | path_to_nameidata(&path, nd); | |
1779 | return -ENOENT; | |
1780 | } | |
1781 | ||
254cf582 | 1782 | seq = 0; /* we are already out of RCU mode */ |
d4565649 | 1783 | inode = d_backing_inode(path.dentry); |
ce57dfc1 | 1784 | } |
697f514d | 1785 | |
4693a547 AV |
1786 | if (flags & WALK_PUT) |
1787 | put_link(nd); | |
181548c0 | 1788 | err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); |
d63ff28f AV |
1789 | if (unlikely(err)) |
1790 | return err; | |
caa85634 | 1791 | path_to_nameidata(&path, nd); |
ce57dfc1 | 1792 | nd->inode = inode; |
254cf582 | 1793 | nd->seq = seq; |
ce57dfc1 AV |
1794 | return 0; |
1795 | } | |
1796 | ||
bfcfaa77 LT |
1797 | /* |
1798 | * We can do the critical dentry name comparison and hashing | |
1799 | * operations one word at a time, but we are limited to: | |
1800 | * | |
1801 | * - Architectures with fast unaligned word accesses. We could | |
1802 | * do a "get_unaligned()" if this helps and is sufficiently | |
1803 | * fast. | |
1804 | * | |
bfcfaa77 LT |
1805 | * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we |
1806 | * do not trap on the (extremely unlikely) case of a page | |
1807 | * crossing operation. | |
1808 | * | |
1809 | * - Furthermore, we need an efficient 64-bit compile for the | |
1810 | * 64-bit case in order to generate the "number of bytes in | |
1811 | * the final mask". Again, that could be replaced with a | |
1812 | * efficient population count instruction or similar. | |
1813 | */ | |
1814 | #ifdef CONFIG_DCACHE_WORD_ACCESS | |
1815 | ||
f68e556e | 1816 | #include <asm/word-at-a-time.h> |
bfcfaa77 | 1817 | |
468a9428 | 1818 | #ifdef HASH_MIX |
bfcfaa77 | 1819 | |
468a9428 | 1820 | /* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */ |
bfcfaa77 | 1821 | |
468a9428 | 1822 | #elif defined(CONFIG_64BIT) |
0fed3ac8 | 1823 | /* |
2a18da7a GS |
1824 | * Register pressure in the mixing function is an issue, particularly |
1825 | * on 32-bit x86, but almost any function requires one state value and | |
1826 | * one temporary. Instead, use a function designed for two state values | |
1827 | * and no temporaries. | |
1828 | * | |
1829 | * This function cannot create a collision in only two iterations, so | |
1830 | * we have two iterations to achieve avalanche. In those two iterations, | |
1831 | * we have six layers of mixing, which is enough to spread one bit's | |
1832 | * influence out to 2^6 = 64 state bits. | |
1833 | * | |
1834 | * Rotate constants are scored by considering either 64 one-bit input | |
1835 | * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the | |
1836 | * probability of that delta causing a change to each of the 128 output | |
1837 | * bits, using a sample of random initial states. | |
1838 | * | |
1839 | * The Shannon entropy of the computed probabilities is then summed | |
1840 | * to produce a score. Ideally, any input change has a 50% chance of | |
1841 | * toggling any given output bit. | |
1842 | * | |
1843 | * Mixing scores (in bits) for (12,45): | |
1844 | * Input delta: 1-bit 2-bit | |
1845 | * 1 round: 713.3 42542.6 | |
1846 | * 2 rounds: 2753.7 140389.8 | |
1847 | * 3 rounds: 5954.1 233458.2 | |
1848 | * 4 rounds: 7862.6 256672.2 | |
1849 | * Perfect: 8192 258048 | |
1850 | * (64*128) (64*63/2 * 128) | |
0fed3ac8 | 1851 | */ |
2a18da7a GS |
1852 | #define HASH_MIX(x, y, a) \ |
1853 | ( x ^= (a), \ | |
1854 | y ^= x, x = rol64(x,12),\ | |
1855 | x += y, y = rol64(y,45),\ | |
1856 | y *= 9 ) | |
bfcfaa77 | 1857 | |
0fed3ac8 | 1858 | /* |
2a18da7a GS |
1859 | * Fold two longs into one 32-bit hash value. This must be fast, but |
1860 | * latency isn't quite as critical, as there is a fair bit of additional | |
1861 | * work done before the hash value is used. | |
0fed3ac8 | 1862 | */ |
2a18da7a | 1863 | static inline unsigned int fold_hash(unsigned long x, unsigned long y) |
0fed3ac8 | 1864 | { |
2a18da7a GS |
1865 | y ^= x * GOLDEN_RATIO_64; |
1866 | y *= GOLDEN_RATIO_64; | |
1867 | return y >> 32; | |
0fed3ac8 GS |
1868 | } |
1869 | ||
bfcfaa77 LT |
1870 | #else /* 32-bit case */ |
1871 | ||
2a18da7a GS |
1872 | /* |
1873 | * Mixing scores (in bits) for (7,20): | |
1874 | * Input delta: 1-bit 2-bit | |
1875 | * 1 round: 330.3 9201.6 | |
1876 | * 2 rounds: 1246.4 25475.4 | |
1877 | * 3 rounds: 1907.1 31295.1 | |
1878 | * 4 rounds: 2042.3 31718.6 | |
1879 | * Perfect: 2048 31744 | |
1880 | * (32*64) (32*31/2 * 64) | |
1881 | */ | |
1882 | #define HASH_MIX(x, y, a) \ | |
1883 | ( x ^= (a), \ | |
1884 | y ^= x, x = rol32(x, 7),\ | |
1885 | x += y, y = rol32(y,20),\ | |
1886 | y *= 9 ) | |
bfcfaa77 | 1887 | |
2a18da7a | 1888 | static inline unsigned int fold_hash(unsigned long x, unsigned long y) |
0fed3ac8 | 1889 | { |
2a18da7a GS |
1890 | /* Use arch-optimized multiply if one exists */ |
1891 | return __hash_32(y ^ __hash_32(x)); | |
0fed3ac8 GS |
1892 | } |
1893 | ||
bfcfaa77 LT |
1894 | #endif |
1895 | ||
2a18da7a GS |
1896 | /* |
1897 | * Return the hash of a string of known length. This is carfully | |
1898 | * designed to match hash_name(), which is the more critical function. | |
1899 | * In particular, we must end by hashing a final word containing 0..7 | |
1900 | * payload bytes, to match the way that hash_name() iterates until it | |
1901 | * finds the delimiter after the name. | |
1902 | */ | |
fcfd2fbf | 1903 | unsigned int full_name_hash(const char *name, unsigned int len) |
bfcfaa77 | 1904 | { |
2a18da7a | 1905 | unsigned long a, x = 0, y = 0; |
bfcfaa77 LT |
1906 | |
1907 | for (;;) { | |
fcfd2fbf GS |
1908 | if (!len) |
1909 | goto done; | |
e419b4cc | 1910 | a = load_unaligned_zeropad(name); |
bfcfaa77 LT |
1911 | if (len < sizeof(unsigned long)) |
1912 | break; | |
2a18da7a | 1913 | HASH_MIX(x, y, a); |
bfcfaa77 LT |
1914 | name += sizeof(unsigned long); |
1915 | len -= sizeof(unsigned long); | |
bfcfaa77 | 1916 | } |
2a18da7a | 1917 | x ^= a & bytemask_from_count(len); |
bfcfaa77 | 1918 | done: |
2a18da7a | 1919 | return fold_hash(x, y); |
bfcfaa77 LT |
1920 | } |
1921 | EXPORT_SYMBOL(full_name_hash); | |
1922 | ||
fcfd2fbf GS |
1923 | /* Return the "hash_len" (hash and length) of a null-terminated string */ |
1924 | u64 hashlen_string(const char *name) | |
1925 | { | |
2a18da7a | 1926 | unsigned long a = 0, x = 0, y = 0, adata, mask, len; |
fcfd2fbf GS |
1927 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; |
1928 | ||
fcfd2fbf GS |
1929 | len = -sizeof(unsigned long); |
1930 | do { | |
2a18da7a | 1931 | HASH_MIX(x, y, a); |
fcfd2fbf GS |
1932 | len += sizeof(unsigned long); |
1933 | a = load_unaligned_zeropad(name+len); | |
1934 | } while (!has_zero(a, &adata, &constants)); | |
1935 | ||
1936 | adata = prep_zero_mask(a, adata, &constants); | |
1937 | mask = create_zero_mask(adata); | |
2a18da7a | 1938 | x ^= a & zero_bytemask(mask); |
fcfd2fbf | 1939 | |
2a18da7a | 1940 | return hashlen_create(fold_hash(x, y), len + find_zero(mask)); |
fcfd2fbf GS |
1941 | } |
1942 | EXPORT_SYMBOL(hashlen_string); | |
1943 | ||
bfcfaa77 LT |
1944 | /* |
1945 | * Calculate the length and hash of the path component, and | |
d6bb3e90 | 1946 | * return the "hash_len" as the result. |
bfcfaa77 | 1947 | */ |
d6bb3e90 | 1948 | static inline u64 hash_name(const char *name) |
bfcfaa77 | 1949 | { |
2a18da7a | 1950 | unsigned long a = 0, b, x = 0, y = 0, adata, bdata, mask, len; |
36126f8f | 1951 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; |
bfcfaa77 | 1952 | |
bfcfaa77 LT |
1953 | len = -sizeof(unsigned long); |
1954 | do { | |
2a18da7a | 1955 | HASH_MIX(x, y, a); |
bfcfaa77 | 1956 | len += sizeof(unsigned long); |
e419b4cc | 1957 | a = load_unaligned_zeropad(name+len); |
36126f8f LT |
1958 | b = a ^ REPEAT_BYTE('/'); |
1959 | } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); | |
1960 | ||
1961 | adata = prep_zero_mask(a, adata, &constants); | |
1962 | bdata = prep_zero_mask(b, bdata, &constants); | |
36126f8f | 1963 | mask = create_zero_mask(adata | bdata); |
2a18da7a | 1964 | x ^= a & zero_bytemask(mask); |
36126f8f | 1965 | |
2a18da7a | 1966 | return hashlen_create(fold_hash(x, y), len + find_zero(mask)); |
bfcfaa77 LT |
1967 | } |
1968 | ||
2a18da7a | 1969 | #else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */ |
bfcfaa77 | 1970 | |
fcfd2fbf GS |
1971 | /* Return the hash of a string of known length */ |
1972 | unsigned int full_name_hash(const char *name, unsigned int len) | |
0145acc2 LT |
1973 | { |
1974 | unsigned long hash = init_name_hash(); | |
1975 | while (len--) | |
fcfd2fbf | 1976 | hash = partial_name_hash((unsigned char)*name++, hash); |
0145acc2 LT |
1977 | return end_name_hash(hash); |
1978 | } | |
ae942ae7 | 1979 | EXPORT_SYMBOL(full_name_hash); |
0145acc2 | 1980 | |
fcfd2fbf | 1981 | /* Return the "hash_len" (hash and length) of a null-terminated string */ |
f2a031b6 | 1982 | u64 hashlen_string(const char *name) |
fcfd2fbf GS |
1983 | { |
1984 | unsigned long hash = init_name_hash(); | |
1985 | unsigned long len = 0, c; | |
1986 | ||
1987 | c = (unsigned char)*name; | |
e0ab7af9 | 1988 | while (c) { |
fcfd2fbf GS |
1989 | len++; |
1990 | hash = partial_name_hash(c, hash); | |
1991 | c = (unsigned char)name[len]; | |
e0ab7af9 | 1992 | } |
fcfd2fbf GS |
1993 | return hashlen_create(end_name_hash(hash), len); |
1994 | } | |
f2a031b6 | 1995 | EXPORT_SYMBOL(hashlen_string); |
fcfd2fbf | 1996 | |
200e9ef7 LT |
1997 | /* |
1998 | * We know there's a real path component here of at least | |
1999 | * one character. | |
2000 | */ | |
d6bb3e90 | 2001 | static inline u64 hash_name(const char *name) |
200e9ef7 LT |
2002 | { |
2003 | unsigned long hash = init_name_hash(); | |
2004 | unsigned long len = 0, c; | |
2005 | ||
2006 | c = (unsigned char)*name; | |
2007 | do { | |
2008 | len++; | |
2009 | hash = partial_name_hash(c, hash); | |
2010 | c = (unsigned char)name[len]; | |
2011 | } while (c && c != '/'); | |
d6bb3e90 | 2012 | return hashlen_create(end_name_hash(hash), len); |
200e9ef7 LT |
2013 | } |
2014 | ||
bfcfaa77 LT |
2015 | #endif |
2016 | ||
1da177e4 LT |
2017 | /* |
2018 | * Name resolution. | |
ea3834d9 PM |
2019 | * This is the basic name resolution function, turning a pathname into |
2020 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 2021 | * |
ea3834d9 PM |
2022 | * Returns 0 and nd will have valid dentry and mnt on success. |
2023 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 2024 | */ |
6de88d72 | 2025 | static int link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 | 2026 | { |
1da177e4 | 2027 | int err; |
32cd7468 | 2028 | |
1da177e4 LT |
2029 | while (*name=='/') |
2030 | name++; | |
2031 | if (!*name) | |
9e18f10a | 2032 | return 0; |
1da177e4 | 2033 | |
1da177e4 LT |
2034 | /* At this point we know we have a real path component. */ |
2035 | for(;;) { | |
d6bb3e90 | 2036 | u64 hash_len; |
fe479a58 | 2037 | int type; |
1da177e4 | 2038 | |
52094c8a | 2039 | err = may_lookup(nd); |
2a18da7a | 2040 | if (err) |
3595e234 | 2041 | return err; |
1da177e4 | 2042 | |
d6bb3e90 | 2043 | hash_len = hash_name(name); |
1da177e4 | 2044 | |
fe479a58 | 2045 | type = LAST_NORM; |
d6bb3e90 | 2046 | if (name[0] == '.') switch (hashlen_len(hash_len)) { |
fe479a58 | 2047 | case 2: |
200e9ef7 | 2048 | if (name[1] == '.') { |
fe479a58 | 2049 | type = LAST_DOTDOT; |
16c2cd71 AV |
2050 | nd->flags |= LOOKUP_JUMPED; |
2051 | } | |
fe479a58 AV |
2052 | break; |
2053 | case 1: | |
2054 | type = LAST_DOT; | |
2055 | } | |
5a202bcd AV |
2056 | if (likely(type == LAST_NORM)) { |
2057 | struct dentry *parent = nd->path.dentry; | |
16c2cd71 | 2058 | nd->flags &= ~LOOKUP_JUMPED; |
5a202bcd | 2059 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
a060dc50 | 2060 | struct qstr this = { { .hash_len = hash_len }, .name = name }; |
da53be12 | 2061 | err = parent->d_op->d_hash(parent, &this); |
5a202bcd | 2062 | if (err < 0) |
3595e234 | 2063 | return err; |
d6bb3e90 LT |
2064 | hash_len = this.hash_len; |
2065 | name = this.name; | |
5a202bcd AV |
2066 | } |
2067 | } | |
fe479a58 | 2068 | |
d6bb3e90 LT |
2069 | nd->last.hash_len = hash_len; |
2070 | nd->last.name = name; | |
5f4a6a69 AV |
2071 | nd->last_type = type; |
2072 | ||
d6bb3e90 LT |
2073 | name += hashlen_len(hash_len); |
2074 | if (!*name) | |
bdf6cbf1 | 2075 | goto OK; |
200e9ef7 LT |
2076 | /* |
2077 | * If it wasn't NUL, we know it was '/'. Skip that | |
2078 | * slash, and continue until no more slashes. | |
2079 | */ | |
2080 | do { | |
d6bb3e90 LT |
2081 | name++; |
2082 | } while (unlikely(*name == '/')); | |
8620c238 AV |
2083 | if (unlikely(!*name)) { |
2084 | OK: | |
368ee9ba | 2085 | /* pathname body, done */ |
8620c238 AV |
2086 | if (!nd->depth) |
2087 | return 0; | |
2088 | name = nd->stack[nd->depth - 1].name; | |
368ee9ba | 2089 | /* trailing symlink, done */ |
8620c238 AV |
2090 | if (!name) |
2091 | return 0; | |
2092 | /* last component of nested symlink */ | |
4693a547 | 2093 | err = walk_component(nd, WALK_GET | WALK_PUT); |
8620c238 | 2094 | } else { |
4693a547 | 2095 | err = walk_component(nd, WALK_GET); |
8620c238 | 2096 | } |
ce57dfc1 | 2097 | if (err < 0) |
3595e234 | 2098 | return err; |
1da177e4 | 2099 | |
ce57dfc1 | 2100 | if (err) { |
626de996 | 2101 | const char *s = get_link(nd); |
5a460275 | 2102 | |
a1c83681 | 2103 | if (IS_ERR(s)) |
3595e234 | 2104 | return PTR_ERR(s); |
d40bcc09 AV |
2105 | err = 0; |
2106 | if (unlikely(!s)) { | |
2107 | /* jumped */ | |
b9ff4429 | 2108 | put_link(nd); |
d40bcc09 | 2109 | } else { |
fab51e8a AV |
2110 | nd->stack[nd->depth - 1].name = name; |
2111 | name = s; | |
2112 | continue; | |
d40bcc09 | 2113 | } |
31e6b01f | 2114 | } |
97242f99 AV |
2115 | if (unlikely(!d_can_lookup(nd->path.dentry))) { |
2116 | if (nd->flags & LOOKUP_RCU) { | |
2117 | if (unlazy_walk(nd, NULL, 0)) | |
2118 | return -ECHILD; | |
2119 | } | |
3595e234 | 2120 | return -ENOTDIR; |
97242f99 | 2121 | } |
1da177e4 | 2122 | } |
1da177e4 LT |
2123 | } |
2124 | ||
c8a53ee5 | 2125 | static const char *path_init(struct nameidata *nd, unsigned flags) |
31e6b01f NP |
2126 | { |
2127 | int retval = 0; | |
c8a53ee5 | 2128 | const char *s = nd->name->name; |
31e6b01f NP |
2129 | |
2130 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
980f3ea2 | 2131 | nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; |
31e6b01f | 2132 | nd->depth = 0; |
5b6ca027 | 2133 | if (flags & LOOKUP_ROOT) { |
b18825a7 DH |
2134 | struct dentry *root = nd->root.dentry; |
2135 | struct inode *inode = root->d_inode; | |
fd2f7cb5 | 2136 | if (*s) { |
44b1d530 | 2137 | if (!d_can_lookup(root)) |
368ee9ba | 2138 | return ERR_PTR(-ENOTDIR); |
73d049a4 AV |
2139 | retval = inode_permission(inode, MAY_EXEC); |
2140 | if (retval) | |
368ee9ba | 2141 | return ERR_PTR(retval); |
73d049a4 | 2142 | } |
5b6ca027 AV |
2143 | nd->path = nd->root; |
2144 | nd->inode = inode; | |
2145 | if (flags & LOOKUP_RCU) { | |
8b61e74f | 2146 | rcu_read_lock(); |
5b6ca027 | 2147 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
8f47a016 | 2148 | nd->root_seq = nd->seq; |
48a066e7 | 2149 | nd->m_seq = read_seqbegin(&mount_lock); |
5b6ca027 AV |
2150 | } else { |
2151 | path_get(&nd->path); | |
2152 | } | |
368ee9ba | 2153 | return s; |
5b6ca027 AV |
2154 | } |
2155 | ||
31e6b01f | 2156 | nd->root.mnt = NULL; |
248fb5b9 AV |
2157 | nd->path.mnt = NULL; |
2158 | nd->path.dentry = NULL; | |
31e6b01f | 2159 | |
48a066e7 | 2160 | nd->m_seq = read_seqbegin(&mount_lock); |
fd2f7cb5 | 2161 | if (*s == '/') { |
9e6697e2 | 2162 | if (flags & LOOKUP_RCU) |
8b61e74f | 2163 | rcu_read_lock(); |
9e6697e2 | 2164 | set_root(nd); |
248fb5b9 | 2165 | if (likely(!nd_jump_root(nd))) |
ef55d917 | 2166 | return s; |
248fb5b9 | 2167 | nd->root.mnt = NULL; |
ef55d917 AV |
2168 | rcu_read_unlock(); |
2169 | return ERR_PTR(-ECHILD); | |
c8a53ee5 | 2170 | } else if (nd->dfd == AT_FDCWD) { |
e41f7d4e AV |
2171 | if (flags & LOOKUP_RCU) { |
2172 | struct fs_struct *fs = current->fs; | |
2173 | unsigned seq; | |
31e6b01f | 2174 | |
8b61e74f | 2175 | rcu_read_lock(); |
c28cc364 | 2176 | |
e41f7d4e AV |
2177 | do { |
2178 | seq = read_seqcount_begin(&fs->seq); | |
2179 | nd->path = fs->pwd; | |
ef55d917 | 2180 | nd->inode = nd->path.dentry->d_inode; |
e41f7d4e AV |
2181 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
2182 | } while (read_seqcount_retry(&fs->seq, seq)); | |
2183 | } else { | |
2184 | get_fs_pwd(current->fs, &nd->path); | |
ef55d917 | 2185 | nd->inode = nd->path.dentry->d_inode; |
e41f7d4e | 2186 | } |
ef55d917 | 2187 | return s; |
31e6b01f | 2188 | } else { |
582aa64a | 2189 | /* Caller must check execute permissions on the starting path component */ |
c8a53ee5 | 2190 | struct fd f = fdget_raw(nd->dfd); |
31e6b01f NP |
2191 | struct dentry *dentry; |
2192 | ||
2903ff01 | 2193 | if (!f.file) |
368ee9ba | 2194 | return ERR_PTR(-EBADF); |
31e6b01f | 2195 | |
2903ff01 | 2196 | dentry = f.file->f_path.dentry; |
31e6b01f | 2197 | |
fd2f7cb5 | 2198 | if (*s) { |
44b1d530 | 2199 | if (!d_can_lookup(dentry)) { |
2903ff01 | 2200 | fdput(f); |
368ee9ba | 2201 | return ERR_PTR(-ENOTDIR); |
2903ff01 | 2202 | } |
f52e0c11 | 2203 | } |
31e6b01f | 2204 | |
2903ff01 | 2205 | nd->path = f.file->f_path; |
e41f7d4e | 2206 | if (flags & LOOKUP_RCU) { |
8b61e74f | 2207 | rcu_read_lock(); |
34a26b99 AV |
2208 | nd->inode = nd->path.dentry->d_inode; |
2209 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
e41f7d4e | 2210 | } else { |
2903ff01 | 2211 | path_get(&nd->path); |
34a26b99 | 2212 | nd->inode = nd->path.dentry->d_inode; |
e41f7d4e | 2213 | } |
34a26b99 | 2214 | fdput(f); |
368ee9ba | 2215 | return s; |
31e6b01f | 2216 | } |
9b4a9b14 AV |
2217 | } |
2218 | ||
3bdba28b | 2219 | static const char *trailing_symlink(struct nameidata *nd) |
95fa25d9 AV |
2220 | { |
2221 | const char *s; | |
fec2fa24 | 2222 | int error = may_follow_link(nd); |
deb106c6 | 2223 | if (unlikely(error)) |
3bdba28b | 2224 | return ERR_PTR(error); |
95fa25d9 | 2225 | nd->flags |= LOOKUP_PARENT; |
fab51e8a | 2226 | nd->stack[0].name = NULL; |
3b2e7f75 | 2227 | s = get_link(nd); |
deb106c6 | 2228 | return s ? s : ""; |
95fa25d9 AV |
2229 | } |
2230 | ||
caa85634 | 2231 | static inline int lookup_last(struct nameidata *nd) |
bd92d7fe AV |
2232 | { |
2233 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) | |
2234 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
2235 | ||
2236 | nd->flags &= ~LOOKUP_PARENT; | |
deb106c6 | 2237 | return walk_component(nd, |
4693a547 AV |
2238 | nd->flags & LOOKUP_FOLLOW |
2239 | ? nd->depth | |
2240 | ? WALK_PUT | WALK_GET | |
2241 | : WALK_GET | |
2242 | : 0); | |
bd92d7fe AV |
2243 | } |
2244 | ||
9b4a9b14 | 2245 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
c8a53ee5 | 2246 | static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path) |
9b4a9b14 | 2247 | { |
c8a53ee5 | 2248 | const char *s = path_init(nd, flags); |
bd92d7fe | 2249 | int err; |
31e6b01f | 2250 | |
368ee9ba AV |
2251 | if (IS_ERR(s)) |
2252 | return PTR_ERR(s); | |
3bdba28b AV |
2253 | while (!(err = link_path_walk(s, nd)) |
2254 | && ((err = lookup_last(nd)) > 0)) { | |
2255 | s = trailing_symlink(nd); | |
2256 | if (IS_ERR(s)) { | |
2257 | err = PTR_ERR(s); | |
2258 | break; | |
bd92d7fe AV |
2259 | } |
2260 | } | |
9f1fafee AV |
2261 | if (!err) |
2262 | err = complete_walk(nd); | |
bd92d7fe | 2263 | |
deb106c6 AV |
2264 | if (!err && nd->flags & LOOKUP_DIRECTORY) |
2265 | if (!d_can_lookup(nd->path.dentry)) | |
bd23a539 | 2266 | err = -ENOTDIR; |
625b6d10 AV |
2267 | if (!err) { |
2268 | *path = nd->path; | |
2269 | nd->path.mnt = NULL; | |
2270 | nd->path.dentry = NULL; | |
2271 | } | |
2272 | terminate_walk(nd); | |
bd92d7fe | 2273 | return err; |
ee0827cd | 2274 | } |
31e6b01f | 2275 | |
625b6d10 | 2276 | static int filename_lookup(int dfd, struct filename *name, unsigned flags, |
9ad1aaa6 | 2277 | struct path *path, struct path *root) |
ee0827cd | 2278 | { |
894bc8c4 | 2279 | int retval; |
9883d185 | 2280 | struct nameidata nd; |
abc9f5be AV |
2281 | if (IS_ERR(name)) |
2282 | return PTR_ERR(name); | |
9ad1aaa6 AV |
2283 | if (unlikely(root)) { |
2284 | nd.root = *root; | |
2285 | flags |= LOOKUP_ROOT; | |
2286 | } | |
9883d185 | 2287 | set_nameidata(&nd, dfd, name); |
c8a53ee5 | 2288 | retval = path_lookupat(&nd, flags | LOOKUP_RCU, path); |
ee0827cd | 2289 | if (unlikely(retval == -ECHILD)) |
c8a53ee5 | 2290 | retval = path_lookupat(&nd, flags, path); |
ee0827cd | 2291 | if (unlikely(retval == -ESTALE)) |
c8a53ee5 | 2292 | retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path); |
31e6b01f | 2293 | |
f78570dd | 2294 | if (likely(!retval)) |
625b6d10 | 2295 | audit_inode(name, path->dentry, flags & LOOKUP_PARENT); |
9883d185 | 2296 | restore_nameidata(); |
e4bd1c1a | 2297 | putname(name); |
170aa3d0 | 2298 | return retval; |
1da177e4 LT |
2299 | } |
2300 | ||
8bcb77fa | 2301 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
c8a53ee5 | 2302 | static int path_parentat(struct nameidata *nd, unsigned flags, |
391172c4 | 2303 | struct path *parent) |
8bcb77fa | 2304 | { |
c8a53ee5 | 2305 | const char *s = path_init(nd, flags); |
368ee9ba AV |
2306 | int err; |
2307 | if (IS_ERR(s)) | |
2308 | return PTR_ERR(s); | |
2309 | err = link_path_walk(s, nd); | |
8bcb77fa AV |
2310 | if (!err) |
2311 | err = complete_walk(nd); | |
391172c4 AV |
2312 | if (!err) { |
2313 | *parent = nd->path; | |
2314 | nd->path.mnt = NULL; | |
2315 | nd->path.dentry = NULL; | |
2316 | } | |
2317 | terminate_walk(nd); | |
8bcb77fa AV |
2318 | return err; |
2319 | } | |
2320 | ||
5c31b6ce | 2321 | static struct filename *filename_parentat(int dfd, struct filename *name, |
391172c4 AV |
2322 | unsigned int flags, struct path *parent, |
2323 | struct qstr *last, int *type) | |
8bcb77fa AV |
2324 | { |
2325 | int retval; | |
9883d185 | 2326 | struct nameidata nd; |
8bcb77fa | 2327 | |
5c31b6ce AV |
2328 | if (IS_ERR(name)) |
2329 | return name; | |
9883d185 | 2330 | set_nameidata(&nd, dfd, name); |
c8a53ee5 | 2331 | retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); |
8bcb77fa | 2332 | if (unlikely(retval == -ECHILD)) |
c8a53ee5 | 2333 | retval = path_parentat(&nd, flags, parent); |
8bcb77fa | 2334 | if (unlikely(retval == -ESTALE)) |
c8a53ee5 | 2335 | retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent); |
391172c4 AV |
2336 | if (likely(!retval)) { |
2337 | *last = nd.last; | |
2338 | *type = nd.last_type; | |
2339 | audit_inode(name, parent->dentry, LOOKUP_PARENT); | |
5c31b6ce AV |
2340 | } else { |
2341 | putname(name); | |
2342 | name = ERR_PTR(retval); | |
391172c4 | 2343 | } |
9883d185 | 2344 | restore_nameidata(); |
5c31b6ce | 2345 | return name; |
8bcb77fa AV |
2346 | } |
2347 | ||
79714f72 AV |
2348 | /* does lookup, returns the object with parent locked */ |
2349 | struct dentry *kern_path_locked(const char *name, struct path *path) | |
5590ff0d | 2350 | { |
5c31b6ce AV |
2351 | struct filename *filename; |
2352 | struct dentry *d; | |
391172c4 AV |
2353 | struct qstr last; |
2354 | int type; | |
51689104 | 2355 | |
5c31b6ce AV |
2356 | filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, |
2357 | &last, &type); | |
51689104 PM |
2358 | if (IS_ERR(filename)) |
2359 | return ERR_CAST(filename); | |
5c31b6ce | 2360 | if (unlikely(type != LAST_NORM)) { |
391172c4 | 2361 | path_put(path); |
5c31b6ce AV |
2362 | putname(filename); |
2363 | return ERR_PTR(-EINVAL); | |
79714f72 | 2364 | } |
5955102c | 2365 | inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); |
391172c4 | 2366 | d = __lookup_hash(&last, path->dentry, 0); |
79714f72 | 2367 | if (IS_ERR(d)) { |
5955102c | 2368 | inode_unlock(path->dentry->d_inode); |
391172c4 | 2369 | path_put(path); |
79714f72 | 2370 | } |
51689104 | 2371 | putname(filename); |
79714f72 | 2372 | return d; |
5590ff0d UD |
2373 | } |
2374 | ||
d1811465 AV |
2375 | int kern_path(const char *name, unsigned int flags, struct path *path) |
2376 | { | |
abc9f5be AV |
2377 | return filename_lookup(AT_FDCWD, getname_kernel(name), |
2378 | flags, path, NULL); | |
d1811465 | 2379 | } |
4d359507 | 2380 | EXPORT_SYMBOL(kern_path); |
d1811465 | 2381 | |
16f18200 JJS |
2382 | /** |
2383 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
2384 | * @dentry: pointer to dentry of the base directory | |
2385 | * @mnt: pointer to vfs mount of the base directory | |
2386 | * @name: pointer to file name | |
2387 | * @flags: lookup flags | |
e0a01249 | 2388 | * @path: pointer to struct path to fill |
16f18200 JJS |
2389 | */ |
2390 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
2391 | const char *name, unsigned int flags, | |
e0a01249 | 2392 | struct path *path) |
16f18200 | 2393 | { |
9ad1aaa6 | 2394 | struct path root = {.mnt = mnt, .dentry = dentry}; |
9ad1aaa6 | 2395 | /* the first argument of filename_lookup() is ignored with root */ |
abc9f5be AV |
2396 | return filename_lookup(AT_FDCWD, getname_kernel(name), |
2397 | flags , path, &root); | |
16f18200 | 2398 | } |
4d359507 | 2399 | EXPORT_SYMBOL(vfs_path_lookup); |
16f18200 | 2400 | |
3c9fe8cd MS |
2401 | /** |
2402 | * lookup_hash - lookup single pathname component on already hashed name | |
2403 | * @name: name and hash to lookup | |
2404 | * @base: base directory to lookup from | |
2405 | * | |
2406 | * The name must have been verified and hashed (see lookup_one_len()). Using | |
2407 | * this after just full_name_hash() is unsafe. | |
2408 | * | |
2409 | * This function also doesn't check for search permission on base directory. | |
2410 | * | |
2411 | * Use lookup_one_len_unlocked() instead, unless you really know what you are | |
2412 | * doing. | |
2413 | * | |
2414 | * Do not hold i_mutex; this helper takes i_mutex if necessary. | |
2415 | */ | |
2416 | struct dentry *lookup_hash(const struct qstr *name, struct dentry *base) | |
2417 | { | |
2418 | struct dentry *ret; | |
2419 | ||
2420 | ret = lookup_dcache(name, base, 0); | |
2421 | if (!ret) | |
2422 | ret = lookup_slow(name, base, 0); | |
2423 | ||
2424 | return ret; | |
2425 | } | |
2426 | EXPORT_SYMBOL(lookup_hash); | |
2427 | ||
eead1911 | 2428 | /** |
a6b91919 | 2429 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
2430 | * @name: pathname component to lookup |
2431 | * @base: base directory to lookup from | |
2432 | * @len: maximum length @len should be interpreted to | |
2433 | * | |
a6b91919 | 2434 | * Note that this routine is purely a helper for filesystem usage and should |
9e7543e9 | 2435 | * not be called by generic code. |
bbddca8e N |
2436 | * |
2437 | * The caller must hold base->i_mutex. | |
eead1911 | 2438 | */ |
057f6c01 JM |
2439 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
2440 | { | |
057f6c01 | 2441 | struct qstr this; |
6a96ba54 | 2442 | unsigned int c; |
cda309de | 2443 | int err; |
057f6c01 | 2444 | |
5955102c | 2445 | WARN_ON_ONCE(!inode_is_locked(base->d_inode)); |
2f9092e1 | 2446 | |
6a96ba54 AV |
2447 | this.name = name; |
2448 | this.len = len; | |
0145acc2 | 2449 | this.hash = full_name_hash(name, len); |
6a96ba54 AV |
2450 | if (!len) |
2451 | return ERR_PTR(-EACCES); | |
2452 | ||
21d8a15a AV |
2453 | if (unlikely(name[0] == '.')) { |
2454 | if (len < 2 || (len == 2 && name[1] == '.')) | |
2455 | return ERR_PTR(-EACCES); | |
2456 | } | |
2457 | ||
6a96ba54 AV |
2458 | while (len--) { |
2459 | c = *(const unsigned char *)name++; | |
2460 | if (c == '/' || c == '\0') | |
2461 | return ERR_PTR(-EACCES); | |
6a96ba54 | 2462 | } |
5a202bcd AV |
2463 | /* |
2464 | * See if the low-level filesystem might want | |
2465 | * to use its own hash.. | |
2466 | */ | |
2467 | if (base->d_flags & DCACHE_OP_HASH) { | |
da53be12 | 2468 | int err = base->d_op->d_hash(base, &this); |
5a202bcd AV |
2469 | if (err < 0) |
2470 | return ERR_PTR(err); | |
2471 | } | |
eead1911 | 2472 | |
cda309de MS |
2473 | err = inode_permission(base->d_inode, MAY_EXEC); |
2474 | if (err) | |
2475 | return ERR_PTR(err); | |
2476 | ||
72bd866a | 2477 | return __lookup_hash(&this, base, 0); |
057f6c01 | 2478 | } |
4d359507 | 2479 | EXPORT_SYMBOL(lookup_one_len); |
057f6c01 | 2480 | |
bbddca8e N |
2481 | /** |
2482 | * lookup_one_len_unlocked - filesystem helper to lookup single pathname component | |
2483 | * @name: pathname component to lookup | |
2484 | * @base: base directory to lookup from | |
2485 | * @len: maximum length @len should be interpreted to | |
2486 | * | |
2487 | * Note that this routine is purely a helper for filesystem usage and should | |
2488 | * not be called by generic code. | |
2489 | * | |
2490 | * Unlike lookup_one_len, it should be called without the parent | |
2491 | * i_mutex held, and will take the i_mutex itself if necessary. | |
2492 | */ | |
2493 | struct dentry *lookup_one_len_unlocked(const char *name, | |
2494 | struct dentry *base, int len) | |
2495 | { | |
2496 | struct qstr this; | |
2497 | unsigned int c; | |
2498 | int err; | |
bbddca8e N |
2499 | |
2500 | this.name = name; | |
2501 | this.len = len; | |
2502 | this.hash = full_name_hash(name, len); | |
2503 | if (!len) | |
2504 | return ERR_PTR(-EACCES); | |
2505 | ||
2506 | if (unlikely(name[0] == '.')) { | |
2507 | if (len < 2 || (len == 2 && name[1] == '.')) | |
2508 | return ERR_PTR(-EACCES); | |
2509 | } | |
2510 | ||
2511 | while (len--) { | |
2512 | c = *(const unsigned char *)name++; | |
2513 | if (c == '/' || c == '\0') | |
2514 | return ERR_PTR(-EACCES); | |
2515 | } | |
2516 | /* | |
2517 | * See if the low-level filesystem might want | |
2518 | * to use its own hash.. | |
2519 | */ | |
2520 | if (base->d_flags & DCACHE_OP_HASH) { | |
2521 | int err = base->d_op->d_hash(base, &this); | |
2522 | if (err < 0) | |
2523 | return ERR_PTR(err); | |
2524 | } | |
2525 | ||
2526 | err = inode_permission(base->d_inode, MAY_EXEC); | |
2527 | if (err) | |
2528 | return ERR_PTR(err); | |
2529 | ||
3c9fe8cd | 2530 | return lookup_hash(&this, base); |
bbddca8e N |
2531 | } |
2532 | EXPORT_SYMBOL(lookup_one_len_unlocked); | |
2533 | ||
eedf265a EB |
2534 | #ifdef CONFIG_UNIX98_PTYS |
2535 | int path_pts(struct path *path) | |
2536 | { | |
2537 | /* Find something mounted on "pts" in the same directory as | |
2538 | * the input path. | |
2539 | */ | |
2540 | struct dentry *child, *parent; | |
2541 | struct qstr this; | |
2542 | int ret; | |
2543 | ||
2544 | ret = path_parent_directory(path); | |
2545 | if (ret) | |
2546 | return ret; | |
2547 | ||
2548 | parent = path->dentry; | |
2549 | this.name = "pts"; | |
2550 | this.len = 3; | |
2551 | child = d_hash_and_lookup(parent, &this); | |
2552 | if (!child) | |
2553 | return -ENOENT; | |
2554 | ||
2555 | path->dentry = child; | |
2556 | dput(parent); | |
2557 | follow_mount(path); | |
2558 | return 0; | |
2559 | } | |
2560 | #endif | |
2561 | ||
1fa1e7f6 AW |
2562 | int user_path_at_empty(int dfd, const char __user *name, unsigned flags, |
2563 | struct path *path, int *empty) | |
1da177e4 | 2564 | { |
abc9f5be AV |
2565 | return filename_lookup(dfd, getname_flags(name, flags, empty), |
2566 | flags, path, NULL); | |
1da177e4 | 2567 | } |
b853a161 | 2568 | EXPORT_SYMBOL(user_path_at_empty); |
1fa1e7f6 | 2569 | |
873f1eed JL |
2570 | /* |
2571 | * NB: most callers don't do anything directly with the reference to the | |
2572 | * to struct filename, but the nd->last pointer points into the name string | |
2573 | * allocated by getname. So we must hold the reference to it until all | |
2574 | * path-walking is complete. | |
2575 | */ | |
a2ec4a2d | 2576 | static inline struct filename * |
f5beed75 AV |
2577 | user_path_parent(int dfd, const char __user *path, |
2578 | struct path *parent, | |
2579 | struct qstr *last, | |
2580 | int *type, | |
9e790bd6 | 2581 | unsigned int flags) |
2ad94ae6 | 2582 | { |
9e790bd6 | 2583 | /* only LOOKUP_REVAL is allowed in extra flags */ |
5c31b6ce AV |
2584 | return filename_parentat(dfd, getname(path), flags & LOOKUP_REVAL, |
2585 | parent, last, type); | |
2ad94ae6 AV |
2586 | } |
2587 | ||
8033426e | 2588 | /** |
197df04c | 2589 | * mountpoint_last - look up last component for umount |
8033426e JL |
2590 | * @nd: pathwalk nameidata - currently pointing at parent directory of "last" |
2591 | * @path: pointer to container for result | |
2592 | * | |
2593 | * This is a special lookup_last function just for umount. In this case, we | |
2594 | * need to resolve the path without doing any revalidation. | |
2595 | * | |
2596 | * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since | |
2597 | * mountpoints are always pinned in the dcache, their ancestors are too. Thus, | |
2598 | * in almost all cases, this lookup will be served out of the dcache. The only | |
2599 | * cases where it won't are if nd->last refers to a symlink or the path is | |
2600 | * bogus and it doesn't exist. | |
2601 | * | |
2602 | * Returns: | |
2603 | * -error: if there was an error during lookup. This includes -ENOENT if the | |
2604 | * lookup found a negative dentry. The nd->path reference will also be | |
2605 | * put in this case. | |
2606 | * | |
2607 | * 0: if we successfully resolved nd->path and found it to not to be a | |
2608 | * symlink that needs to be followed. "path" will also be populated. | |
2609 | * The nd->path reference will also be put. | |
2610 | * | |
2611 | * 1: if we successfully resolved nd->last and found it to be a symlink | |
2612 | * that needs to be followed. "path" will be populated with the path | |
2613 | * to the link, and nd->path will *not* be put. | |
2614 | */ | |
2615 | static int | |
197df04c | 2616 | mountpoint_last(struct nameidata *nd, struct path *path) |
8033426e JL |
2617 | { |
2618 | int error = 0; | |
2619 | struct dentry *dentry; | |
2620 | struct dentry *dir = nd->path.dentry; | |
2621 | ||
35759521 AV |
2622 | /* If we're in rcuwalk, drop out of it to handle last component */ |
2623 | if (nd->flags & LOOKUP_RCU) { | |
6e9918b7 | 2624 | if (unlazy_walk(nd, NULL, 0)) |
deb106c6 | 2625 | return -ECHILD; |
8033426e JL |
2626 | } |
2627 | ||
2628 | nd->flags &= ~LOOKUP_PARENT; | |
2629 | ||
2630 | if (unlikely(nd->last_type != LAST_NORM)) { | |
2631 | error = handle_dots(nd, nd->last_type); | |
35759521 | 2632 | if (error) |
deb106c6 | 2633 | return error; |
35759521 | 2634 | dentry = dget(nd->path.dentry); |
949a852e AV |
2635 | } else { |
2636 | dentry = d_lookup(dir, &nd->last); | |
8033426e | 2637 | if (!dentry) { |
949a852e AV |
2638 | /* |
2639 | * No cached dentry. Mounted dentries are pinned in the | |
2640 | * cache, so that means that this dentry is probably | |
2641 | * a symlink or the path doesn't actually point | |
2642 | * to a mounted dentry. | |
2643 | */ | |
2644 | dentry = lookup_slow(&nd->last, dir, | |
2645 | nd->flags | LOOKUP_NO_REVAL); | |
2646 | if (IS_ERR(dentry)) | |
2647 | return PTR_ERR(dentry); | |
bcceeeba | 2648 | } |
8033426e | 2649 | } |
698934df | 2650 | if (d_is_negative(dentry)) { |
35759521 | 2651 | dput(dentry); |
deb106c6 | 2652 | return -ENOENT; |
8033426e | 2653 | } |
191d7f73 AV |
2654 | if (nd->depth) |
2655 | put_link(nd); | |
35759521 | 2656 | path->dentry = dentry; |
295dc39d | 2657 | path->mnt = nd->path.mnt; |
181548c0 AV |
2658 | error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, |
2659 | d_backing_inode(dentry), 0); | |
deb106c6 | 2660 | if (unlikely(error)) |
d63ff28f | 2661 | return error; |
295dc39d | 2662 | mntget(path->mnt); |
35759521 | 2663 | follow_mount(path); |
deb106c6 | 2664 | return 0; |
8033426e JL |
2665 | } |
2666 | ||
2667 | /** | |
197df04c | 2668 | * path_mountpoint - look up a path to be umounted |
2a78b857 | 2669 | * @nd: lookup context |
8033426e | 2670 | * @flags: lookup flags |
c8a53ee5 | 2671 | * @path: pointer to container for result |
8033426e JL |
2672 | * |
2673 | * Look up the given name, but don't attempt to revalidate the last component. | |
606d6fe3 | 2674 | * Returns 0 and "path" will be valid on success; Returns error otherwise. |
8033426e JL |
2675 | */ |
2676 | static int | |
c8a53ee5 | 2677 | path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path) |
8033426e | 2678 | { |
c8a53ee5 | 2679 | const char *s = path_init(nd, flags); |
368ee9ba AV |
2680 | int err; |
2681 | if (IS_ERR(s)) | |
2682 | return PTR_ERR(s); | |
3bdba28b AV |
2683 | while (!(err = link_path_walk(s, nd)) && |
2684 | (err = mountpoint_last(nd, path)) > 0) { | |
2685 | s = trailing_symlink(nd); | |
2686 | if (IS_ERR(s)) { | |
2687 | err = PTR_ERR(s); | |
8033426e | 2688 | break; |
3bdba28b | 2689 | } |
8033426e | 2690 | } |
deb106c6 | 2691 | terminate_walk(nd); |
8033426e JL |
2692 | return err; |
2693 | } | |
2694 | ||
2d864651 | 2695 | static int |
668696dc | 2696 | filename_mountpoint(int dfd, struct filename *name, struct path *path, |
2d864651 AV |
2697 | unsigned int flags) |
2698 | { | |
9883d185 | 2699 | struct nameidata nd; |
cbaab2db | 2700 | int error; |
668696dc AV |
2701 | if (IS_ERR(name)) |
2702 | return PTR_ERR(name); | |
9883d185 | 2703 | set_nameidata(&nd, dfd, name); |
c8a53ee5 | 2704 | error = path_mountpoint(&nd, flags | LOOKUP_RCU, path); |
2d864651 | 2705 | if (unlikely(error == -ECHILD)) |
c8a53ee5 | 2706 | error = path_mountpoint(&nd, flags, path); |
2d864651 | 2707 | if (unlikely(error == -ESTALE)) |
c8a53ee5 | 2708 | error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path); |
2d864651 | 2709 | if (likely(!error)) |
668696dc | 2710 | audit_inode(name, path->dentry, 0); |
9883d185 | 2711 | restore_nameidata(); |
668696dc | 2712 | putname(name); |
2d864651 AV |
2713 | return error; |
2714 | } | |
2715 | ||
8033426e | 2716 | /** |
197df04c | 2717 | * user_path_mountpoint_at - lookup a path from userland in order to umount it |
8033426e JL |
2718 | * @dfd: directory file descriptor |
2719 | * @name: pathname from userland | |
2720 | * @flags: lookup flags | |
2721 | * @path: pointer to container to hold result | |
2722 | * | |
2723 | * A umount is a special case for path walking. We're not actually interested | |
2724 | * in the inode in this situation, and ESTALE errors can be a problem. We | |
2725 | * simply want track down the dentry and vfsmount attached at the mountpoint | |
2726 | * and avoid revalidating the last component. | |
2727 | * | |
2728 | * Returns 0 and populates "path" on success. | |
2729 | */ | |
2730 | int | |
197df04c | 2731 | user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, |
8033426e JL |
2732 | struct path *path) |
2733 | { | |
cbaab2db | 2734 | return filename_mountpoint(dfd, getname(name), path, flags); |
8033426e JL |
2735 | } |
2736 | ||
2d864651 AV |
2737 | int |
2738 | kern_path_mountpoint(int dfd, const char *name, struct path *path, | |
2739 | unsigned int flags) | |
2740 | { | |
cbaab2db | 2741 | return filename_mountpoint(dfd, getname_kernel(name), path, flags); |
2d864651 AV |
2742 | } |
2743 | EXPORT_SYMBOL(kern_path_mountpoint); | |
2744 | ||
cbdf35bc | 2745 | int __check_sticky(struct inode *dir, struct inode *inode) |
1da177e4 | 2746 | { |
8e96e3b7 | 2747 | kuid_t fsuid = current_fsuid(); |
da9592ed | 2748 | |
8e96e3b7 | 2749 | if (uid_eq(inode->i_uid, fsuid)) |
1da177e4 | 2750 | return 0; |
8e96e3b7 | 2751 | if (uid_eq(dir->i_uid, fsuid)) |
1da177e4 | 2752 | return 0; |
23adbe12 | 2753 | return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); |
1da177e4 | 2754 | } |
cbdf35bc | 2755 | EXPORT_SYMBOL(__check_sticky); |
1da177e4 LT |
2756 | |
2757 | /* | |
2758 | * Check whether we can remove a link victim from directory dir, check | |
2759 | * whether the type of victim is right. | |
2760 | * 1. We can't do it if dir is read-only (done in permission()) | |
2761 | * 2. We should have write and exec permissions on dir | |
2762 | * 3. We can't remove anything from append-only dir | |
2763 | * 4. We can't do anything with immutable dir (done in permission()) | |
2764 | * 5. If the sticky bit on dir is set we should either | |
2765 | * a. be owner of dir, or | |
2766 | * b. be owner of victim, or | |
2767 | * c. have CAP_FOWNER capability | |
2768 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
2769 | * links pointing to it. | |
0bd23d09 EB |
2770 | * 7. If the victim has an unknown uid or gid we can't change the inode. |
2771 | * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
2772 | * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
2773 | * 10. We can't remove a root or mountpoint. | |
2774 | * 11. We don't allow removal of NFS sillyrenamed files; it's handled by | |
1da177e4 LT |
2775 | * nfs_async_unlink(). |
2776 | */ | |
b18825a7 | 2777 | static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) |
1da177e4 | 2778 | { |
63afdfc7 | 2779 | struct inode *inode = d_backing_inode(victim); |
1da177e4 LT |
2780 | int error; |
2781 | ||
b18825a7 | 2782 | if (d_is_negative(victim)) |
1da177e4 | 2783 | return -ENOENT; |
b18825a7 | 2784 | BUG_ON(!inode); |
1da177e4 LT |
2785 | |
2786 | BUG_ON(victim->d_parent->d_inode != dir); | |
4fa6b5ec | 2787 | audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); |
1da177e4 | 2788 | |
f419a2e3 | 2789 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2790 | if (error) |
2791 | return error; | |
2792 | if (IS_APPEND(dir)) | |
2793 | return -EPERM; | |
b18825a7 DH |
2794 | |
2795 | if (check_sticky(dir, inode) || IS_APPEND(inode) || | |
0bd23d09 | 2796 | IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode)) |
1da177e4 LT |
2797 | return -EPERM; |
2798 | if (isdir) { | |
44b1d530 | 2799 | if (!d_is_dir(victim)) |
1da177e4 LT |
2800 | return -ENOTDIR; |
2801 | if (IS_ROOT(victim)) | |
2802 | return -EBUSY; | |
44b1d530 | 2803 | } else if (d_is_dir(victim)) |
1da177e4 LT |
2804 | return -EISDIR; |
2805 | if (IS_DEADDIR(dir)) | |
2806 | return -ENOENT; | |
2807 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
2808 | return -EBUSY; | |
2809 | return 0; | |
2810 | } | |
2811 | ||
2812 | /* Check whether we can create an object with dentry child in directory | |
2813 | * dir. | |
2814 | * 1. We can't do it if child already exists (open has special treatment for | |
2815 | * this case, but since we are inlined it's OK) | |
2816 | * 2. We can't do it if dir is read-only (done in permission()) | |
036d5236 EB |
2817 | * 3. We can't do it if the fs can't represent the fsuid or fsgid. |
2818 | * 4. We should have write and exec permissions on dir | |
2819 | * 5. We can't do it if dir is immutable (done in permission()) | |
1da177e4 | 2820 | */ |
a95164d9 | 2821 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 | 2822 | { |
036d5236 | 2823 | struct user_namespace *s_user_ns; |
14e972b4 | 2824 | audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); |
1da177e4 LT |
2825 | if (child->d_inode) |
2826 | return -EEXIST; | |
2827 | if (IS_DEADDIR(dir)) | |
2828 | return -ENOENT; | |
036d5236 EB |
2829 | s_user_ns = dir->i_sb->s_user_ns; |
2830 | if (!kuid_has_mapping(s_user_ns, current_fsuid()) || | |
2831 | !kgid_has_mapping(s_user_ns, current_fsgid())) | |
2832 | return -EOVERFLOW; | |
f419a2e3 | 2833 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2834 | } |
2835 | ||
1da177e4 LT |
2836 | /* |
2837 | * p1 and p2 should be directories on the same fs. | |
2838 | */ | |
2839 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
2840 | { | |
2841 | struct dentry *p; | |
2842 | ||
2843 | if (p1 == p2) { | |
5955102c | 2844 | inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); |
1da177e4 LT |
2845 | return NULL; |
2846 | } | |
2847 | ||
fc64005c | 2848 | mutex_lock(&p1->d_sb->s_vfs_rename_mutex); |
1da177e4 | 2849 | |
e2761a11 OH |
2850 | p = d_ancestor(p2, p1); |
2851 | if (p) { | |
5955102c AV |
2852 | inode_lock_nested(p2->d_inode, I_MUTEX_PARENT); |
2853 | inode_lock_nested(p1->d_inode, I_MUTEX_CHILD); | |
e2761a11 | 2854 | return p; |
1da177e4 LT |
2855 | } |
2856 | ||
e2761a11 OH |
2857 | p = d_ancestor(p1, p2); |
2858 | if (p) { | |
5955102c AV |
2859 | inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); |
2860 | inode_lock_nested(p2->d_inode, I_MUTEX_CHILD); | |
e2761a11 | 2861 | return p; |
1da177e4 LT |
2862 | } |
2863 | ||
5955102c AV |
2864 | inode_lock_nested(p1->d_inode, I_MUTEX_PARENT); |
2865 | inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2); | |
1da177e4 LT |
2866 | return NULL; |
2867 | } | |
4d359507 | 2868 | EXPORT_SYMBOL(lock_rename); |
1da177e4 LT |
2869 | |
2870 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
2871 | { | |
5955102c | 2872 | inode_unlock(p1->d_inode); |
1da177e4 | 2873 | if (p1 != p2) { |
5955102c | 2874 | inode_unlock(p2->d_inode); |
fc64005c | 2875 | mutex_unlock(&p1->d_sb->s_vfs_rename_mutex); |
1da177e4 LT |
2876 | } |
2877 | } | |
4d359507 | 2878 | EXPORT_SYMBOL(unlock_rename); |
1da177e4 | 2879 | |
4acdaf27 | 2880 | int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
312b63fb | 2881 | bool want_excl) |
1da177e4 | 2882 | { |
a95164d9 | 2883 | int error = may_create(dir, dentry); |
1da177e4 LT |
2884 | if (error) |
2885 | return error; | |
2886 | ||
acfa4380 | 2887 | if (!dir->i_op->create) |
1da177e4 LT |
2888 | return -EACCES; /* shouldn't it be ENOSYS? */ |
2889 | mode &= S_IALLUGO; | |
2890 | mode |= S_IFREG; | |
2891 | error = security_inode_create(dir, dentry, mode); | |
2892 | if (error) | |
2893 | return error; | |
312b63fb | 2894 | error = dir->i_op->create(dir, dentry, mode, want_excl); |
a74574aa | 2895 | if (!error) |
f38aa942 | 2896 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2897 | return error; |
2898 | } | |
4d359507 | 2899 | EXPORT_SYMBOL(vfs_create); |
1da177e4 | 2900 | |
a2982cc9 EB |
2901 | bool may_open_dev(const struct path *path) |
2902 | { | |
2903 | return !(path->mnt->mnt_flags & MNT_NODEV) && | |
2904 | !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV); | |
2905 | } | |
2906 | ||
73d049a4 | 2907 | static int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 2908 | { |
3fb64190 | 2909 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
2910 | struct inode *inode = dentry->d_inode; |
2911 | int error; | |
2912 | ||
2913 | if (!inode) | |
2914 | return -ENOENT; | |
2915 | ||
c8fe8f30 CH |
2916 | switch (inode->i_mode & S_IFMT) { |
2917 | case S_IFLNK: | |
1da177e4 | 2918 | return -ELOOP; |
c8fe8f30 CH |
2919 | case S_IFDIR: |
2920 | if (acc_mode & MAY_WRITE) | |
2921 | return -EISDIR; | |
2922 | break; | |
2923 | case S_IFBLK: | |
2924 | case S_IFCHR: | |
a2982cc9 | 2925 | if (!may_open_dev(path)) |
1da177e4 | 2926 | return -EACCES; |
c8fe8f30 CH |
2927 | /*FALLTHRU*/ |
2928 | case S_IFIFO: | |
2929 | case S_IFSOCK: | |
1da177e4 | 2930 | flag &= ~O_TRUNC; |
c8fe8f30 | 2931 | break; |
4a3fd211 | 2932 | } |
b41572e9 | 2933 | |
62fb4a15 | 2934 | error = inode_permission(inode, MAY_OPEN | acc_mode); |
b41572e9 DH |
2935 | if (error) |
2936 | return error; | |
6146f0d5 | 2937 | |
1da177e4 LT |
2938 | /* |
2939 | * An append-only file must be opened in append mode for writing. | |
2940 | */ | |
2941 | if (IS_APPEND(inode)) { | |
8737c930 | 2942 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
7715b521 | 2943 | return -EPERM; |
1da177e4 | 2944 | if (flag & O_TRUNC) |
7715b521 | 2945 | return -EPERM; |
1da177e4 LT |
2946 | } |
2947 | ||
2948 | /* O_NOATIME can only be set by the owner or superuser */ | |
2e149670 | 2949 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
7715b521 | 2950 | return -EPERM; |
1da177e4 | 2951 | |
f3c7691e | 2952 | return 0; |
7715b521 | 2953 | } |
1da177e4 | 2954 | |
e1181ee6 | 2955 | static int handle_truncate(struct file *filp) |
7715b521 | 2956 | { |
e1181ee6 | 2957 | struct path *path = &filp->f_path; |
7715b521 AV |
2958 | struct inode *inode = path->dentry->d_inode; |
2959 | int error = get_write_access(inode); | |
2960 | if (error) | |
2961 | return error; | |
2962 | /* | |
2963 | * Refuse to truncate files with mandatory locks held on them. | |
2964 | */ | |
d7a06983 | 2965 | error = locks_verify_locked(filp); |
7715b521 | 2966 | if (!error) |
ea0d3ab2 | 2967 | error = security_path_truncate(path); |
7715b521 AV |
2968 | if (!error) { |
2969 | error = do_truncate(path->dentry, 0, | |
2970 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
e1181ee6 | 2971 | filp); |
7715b521 AV |
2972 | } |
2973 | put_write_access(inode); | |
acd0c935 | 2974 | return error; |
1da177e4 LT |
2975 | } |
2976 | ||
d57999e1 DH |
2977 | static inline int open_to_namei_flags(int flag) |
2978 | { | |
8a5e929d AV |
2979 | if ((flag & O_ACCMODE) == 3) |
2980 | flag--; | |
d57999e1 DH |
2981 | return flag; |
2982 | } | |
2983 | ||
d3607752 | 2984 | static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode) |
d18e9008 MS |
2985 | { |
2986 | int error = security_path_mknod(dir, dentry, mode, 0); | |
2987 | if (error) | |
2988 | return error; | |
2989 | ||
2990 | error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); | |
2991 | if (error) | |
2992 | return error; | |
2993 | ||
2994 | return security_inode_create(dir->dentry->d_inode, dentry, mode); | |
2995 | } | |
2996 | ||
1acf0af9 DH |
2997 | /* |
2998 | * Attempt to atomically look up, create and open a file from a negative | |
2999 | * dentry. | |
3000 | * | |
3001 | * Returns 0 if successful. The file will have been created and attached to | |
3002 | * @file by the filesystem calling finish_open(). | |
3003 | * | |
3004 | * Returns 1 if the file was looked up only or didn't need creating. The | |
3005 | * caller will need to perform the open themselves. @path will have been | |
3006 | * updated to point to the new dentry. This may be negative. | |
3007 | * | |
3008 | * Returns an error code otherwise. | |
3009 | */ | |
2675a4eb AV |
3010 | static int atomic_open(struct nameidata *nd, struct dentry *dentry, |
3011 | struct path *path, struct file *file, | |
3012 | const struct open_flags *op, | |
1643b43f | 3013 | int open_flag, umode_t mode, |
2675a4eb | 3014 | int *opened) |
d18e9008 | 3015 | { |
384f26e2 | 3016 | struct dentry *const DENTRY_NOT_SET = (void *) -1UL; |
d18e9008 | 3017 | struct inode *dir = nd->path.dentry->d_inode; |
d18e9008 | 3018 | int error; |
d18e9008 | 3019 | |
384f26e2 | 3020 | if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */ |
d18e9008 | 3021 | open_flag &= ~O_TRUNC; |
d18e9008 | 3022 | |
d18e9008 MS |
3023 | if (nd->flags & LOOKUP_DIRECTORY) |
3024 | open_flag |= O_DIRECTORY; | |
3025 | ||
30d90494 AV |
3026 | file->f_path.dentry = DENTRY_NOT_SET; |
3027 | file->f_path.mnt = nd->path.mnt; | |
0fb1ea09 AV |
3028 | error = dir->i_op->atomic_open(dir, dentry, file, |
3029 | open_to_namei_flags(open_flag), | |
3030 | mode, opened); | |
6fbd0714 | 3031 | d_lookup_done(dentry); |
384f26e2 AV |
3032 | if (!error) { |
3033 | /* | |
3034 | * We didn't have the inode before the open, so check open | |
3035 | * permission here. | |
3036 | */ | |
3037 | int acc_mode = op->acc_mode; | |
3038 | if (*opened & FILE_CREATED) { | |
3039 | WARN_ON(!(open_flag & O_CREAT)); | |
3040 | fsnotify_create(dir, dentry); | |
3041 | acc_mode = 0; | |
3042 | } | |
3043 | error = may_open(&file->f_path, acc_mode, open_flag); | |
3044 | if (WARN_ON(error > 0)) | |
3045 | error = -EINVAL; | |
3046 | } else if (error > 0) { | |
30d90494 | 3047 | if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { |
2675a4eb | 3048 | error = -EIO; |
03da633a | 3049 | } else { |
384f26e2 AV |
3050 | if (file->f_path.dentry) { |
3051 | dput(dentry); | |
3052 | dentry = file->f_path.dentry; | |
03da633a | 3053 | } |
384f26e2 AV |
3054 | if (*opened & FILE_CREATED) |
3055 | fsnotify_create(dir, dentry); | |
3056 | path->dentry = dentry; | |
3057 | path->mnt = nd->path.mnt; | |
3058 | return 1; | |
62b2ce96 | 3059 | } |
d18e9008 | 3060 | } |
d18e9008 | 3061 | dput(dentry); |
2675a4eb | 3062 | return error; |
d18e9008 MS |
3063 | } |
3064 | ||
d58ffd35 | 3065 | /* |
1acf0af9 | 3066 | * Look up and maybe create and open the last component. |
d58ffd35 MS |
3067 | * |
3068 | * Must be called with i_mutex held on parent. | |
3069 | * | |
1acf0af9 DH |
3070 | * Returns 0 if the file was successfully atomically created (if necessary) and |
3071 | * opened. In this case the file will be returned attached to @file. | |
3072 | * | |
3073 | * Returns 1 if the file was not completely opened at this time, though lookups | |
3074 | * and creations will have been performed and the dentry returned in @path will | |
3075 | * be positive upon return if O_CREAT was specified. If O_CREAT wasn't | |
3076 | * specified then a negative dentry may be returned. | |
3077 | * | |
3078 | * An error code is returned otherwise. | |
3079 | * | |
3080 | * FILE_CREATE will be set in @*opened if the dentry was created and will be | |
3081 | * cleared otherwise prior to returning. | |
d58ffd35 | 3082 | */ |
2675a4eb AV |
3083 | static int lookup_open(struct nameidata *nd, struct path *path, |
3084 | struct file *file, | |
3085 | const struct open_flags *op, | |
64894cf8 | 3086 | bool got_write, int *opened) |
d58ffd35 MS |
3087 | { |
3088 | struct dentry *dir = nd->path.dentry; | |
54ef4872 | 3089 | struct inode *dir_inode = dir->d_inode; |
1643b43f | 3090 | int open_flag = op->open_flag; |
d58ffd35 | 3091 | struct dentry *dentry; |
1643b43f | 3092 | int error, create_error = 0; |
1643b43f | 3093 | umode_t mode = op->mode; |
6fbd0714 | 3094 | DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); |
d58ffd35 | 3095 | |
ce8644fc AV |
3096 | if (unlikely(IS_DEADDIR(dir_inode))) |
3097 | return -ENOENT; | |
d58ffd35 | 3098 | |
47237687 | 3099 | *opened &= ~FILE_CREATED; |
6fbd0714 AV |
3100 | dentry = d_lookup(dir, &nd->last); |
3101 | for (;;) { | |
3102 | if (!dentry) { | |
3103 | dentry = d_alloc_parallel(dir, &nd->last, &wq); | |
3104 | if (IS_ERR(dentry)) | |
3105 | return PTR_ERR(dentry); | |
3106 | } | |
3107 | if (d_in_lookup(dentry)) | |
3108 | break; | |
d58ffd35 | 3109 | |
6fbd0714 AV |
3110 | if (!(dentry->d_flags & DCACHE_OP_REVALIDATE)) |
3111 | break; | |
3112 | ||
3113 | error = d_revalidate(dentry, nd->flags); | |
3114 | if (likely(error > 0)) | |
3115 | break; | |
3116 | if (error) | |
3117 | goto out_dput; | |
3118 | d_invalidate(dentry); | |
3119 | dput(dentry); | |
3120 | dentry = NULL; | |
3121 | } | |
3122 | if (dentry->d_inode) { | |
6c51e513 | 3123 | /* Cached positive dentry: will open in f_op->open */ |
d18e9008 | 3124 | goto out_no_open; |
6c51e513 | 3125 | } |
d18e9008 | 3126 | |
1643b43f AV |
3127 | /* |
3128 | * Checking write permission is tricky, bacuse we don't know if we are | |
3129 | * going to actually need it: O_CREAT opens should work as long as the | |
3130 | * file exists. But checking existence breaks atomicity. The trick is | |
3131 | * to check access and if not granted clear O_CREAT from the flags. | |
3132 | * | |
3133 | * Another problem is returing the "right" error value (e.g. for an | |
3134 | * O_EXCL open we want to return EEXIST not EROFS). | |
3135 | */ | |
3136 | if (open_flag & O_CREAT) { | |
3137 | if (!IS_POSIXACL(dir->d_inode)) | |
3138 | mode &= ~current_umask(); | |
3139 | if (unlikely(!got_write)) { | |
3140 | create_error = -EROFS; | |
3141 | open_flag &= ~O_CREAT; | |
3142 | if (open_flag & (O_EXCL | O_TRUNC)) | |
3143 | goto no_open; | |
3144 | /* No side effects, safe to clear O_CREAT */ | |
3145 | } else { | |
3146 | create_error = may_o_create(&nd->path, dentry, mode); | |
3147 | if (create_error) { | |
3148 | open_flag &= ~O_CREAT; | |
3149 | if (open_flag & O_EXCL) | |
3150 | goto no_open; | |
3151 | } | |
3152 | } | |
3153 | } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) && | |
3154 | unlikely(!got_write)) { | |
3155 | /* | |
3156 | * No O_CREATE -> atomicity not a requirement -> fall | |
3157 | * back to lookup + open | |
3158 | */ | |
3159 | goto no_open; | |
d18e9008 MS |
3160 | } |
3161 | ||
6ac08709 | 3162 | if (dir_inode->i_op->atomic_open) { |
1643b43f AV |
3163 | error = atomic_open(nd, dentry, path, file, op, open_flag, |
3164 | mode, opened); | |
3165 | if (unlikely(error == -ENOENT) && create_error) | |
3166 | error = create_error; | |
3167 | return error; | |
d18e9008 | 3168 | } |
54ef4872 | 3169 | |
1643b43f | 3170 | no_open: |
6fbd0714 | 3171 | if (d_in_lookup(dentry)) { |
12fa5e24 AV |
3172 | struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, |
3173 | nd->flags); | |
6fbd0714 | 3174 | d_lookup_done(dentry); |
12fa5e24 AV |
3175 | if (unlikely(res)) { |
3176 | if (IS_ERR(res)) { | |
3177 | error = PTR_ERR(res); | |
3178 | goto out_dput; | |
3179 | } | |
3180 | dput(dentry); | |
3181 | dentry = res; | |
3182 | } | |
54ef4872 MS |
3183 | } |
3184 | ||
d58ffd35 | 3185 | /* Negative dentry, just create the file */ |
1643b43f | 3186 | if (!dentry->d_inode && (open_flag & O_CREAT)) { |
47237687 | 3187 | *opened |= FILE_CREATED; |
ce8644fc | 3188 | audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE); |
ce8644fc AV |
3189 | if (!dir_inode->i_op->create) { |
3190 | error = -EACCES; | |
d58ffd35 | 3191 | goto out_dput; |
ce8644fc AV |
3192 | } |
3193 | error = dir_inode->i_op->create(dir_inode, dentry, mode, | |
1643b43f | 3194 | open_flag & O_EXCL); |
d58ffd35 MS |
3195 | if (error) |
3196 | goto out_dput; | |
ce8644fc | 3197 | fsnotify_create(dir_inode, dentry); |
d58ffd35 | 3198 | } |
1643b43f AV |
3199 | if (unlikely(create_error) && !dentry->d_inode) { |
3200 | error = create_error; | |
3201 | goto out_dput; | |
d58ffd35 | 3202 | } |
d18e9008 | 3203 | out_no_open: |
d58ffd35 MS |
3204 | path->dentry = dentry; |
3205 | path->mnt = nd->path.mnt; | |
2675a4eb | 3206 | return 1; |
d58ffd35 MS |
3207 | |
3208 | out_dput: | |
3209 | dput(dentry); | |
2675a4eb | 3210 | return error; |
d58ffd35 MS |
3211 | } |
3212 | ||
31e6b01f | 3213 | /* |
fe2d35ff | 3214 | * Handle the last step of open() |
31e6b01f | 3215 | */ |
896475d5 | 3216 | static int do_last(struct nameidata *nd, |
2675a4eb | 3217 | struct file *file, const struct open_flags *op, |
76ae2a5a | 3218 | int *opened) |
fb1cc555 | 3219 | { |
a1e28038 | 3220 | struct dentry *dir = nd->path.dentry; |
ca344a89 | 3221 | int open_flag = op->open_flag; |
77d660a8 | 3222 | bool will_truncate = (open_flag & O_TRUNC) != 0; |
64894cf8 | 3223 | bool got_write = false; |
bcda7652 | 3224 | int acc_mode = op->acc_mode; |
254cf582 | 3225 | unsigned seq; |
a1eb3315 | 3226 | struct inode *inode; |
16b1c1cd | 3227 | struct path save_parent = { .dentry = NULL, .mnt = NULL }; |
896475d5 | 3228 | struct path path; |
16b1c1cd | 3229 | bool retried = false; |
16c2cd71 | 3230 | int error; |
1f36f774 | 3231 | |
c3e380b0 AV |
3232 | nd->flags &= ~LOOKUP_PARENT; |
3233 | nd->flags |= op->intent; | |
3234 | ||
bc77daa7 | 3235 | if (nd->last_type != LAST_NORM) { |
fe2d35ff | 3236 | error = handle_dots(nd, nd->last_type); |
deb106c6 | 3237 | if (unlikely(error)) |
2675a4eb | 3238 | return error; |
e83db167 | 3239 | goto finish_open; |
1f36f774 | 3240 | } |
67ee3ad2 | 3241 | |
ca344a89 | 3242 | if (!(open_flag & O_CREAT)) { |
fe2d35ff AV |
3243 | if (nd->last.name[nd->last.len]) |
3244 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
3245 | /* we _can_ be in RCU mode here */ | |
254cf582 | 3246 | error = lookup_fast(nd, &path, &inode, &seq); |
e9742b53 | 3247 | if (likely(error > 0)) |
71574865 MS |
3248 | goto finish_lookup; |
3249 | ||
3250 | if (error < 0) | |
deb106c6 | 3251 | return error; |
71574865 MS |
3252 | |
3253 | BUG_ON(nd->inode != dir->d_inode); | |
6583fe22 | 3254 | BUG_ON(nd->flags & LOOKUP_RCU); |
b6183df7 MS |
3255 | } else { |
3256 | /* create side of things */ | |
3257 | /* | |
3258 | * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED | |
3259 | * has been cleared when we got to the last component we are | |
3260 | * about to look up | |
3261 | */ | |
3262 | error = complete_walk(nd); | |
e8bb73df | 3263 | if (error) |
2675a4eb | 3264 | return error; |
fe2d35ff | 3265 | |
76ae2a5a | 3266 | audit_inode(nd->name, dir, LOOKUP_PARENT); |
b6183df7 | 3267 | /* trailing slashes? */ |
deb106c6 AV |
3268 | if (unlikely(nd->last.name[nd->last.len])) |
3269 | return -EISDIR; | |
b6183df7 | 3270 | } |
a2c36b45 | 3271 | |
16b1c1cd | 3272 | retry_lookup: |
9cf843e3 | 3273 | if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { |
64894cf8 AV |
3274 | error = mnt_want_write(nd->path.mnt); |
3275 | if (!error) | |
3276 | got_write = true; | |
3277 | /* | |
3278 | * do _not_ fail yet - we might not need that or fail with | |
3279 | * a different error; let lookup_open() decide; we'll be | |
3280 | * dropping this one anyway. | |
3281 | */ | |
3282 | } | |
9cf843e3 AV |
3283 | if (open_flag & O_CREAT) |
3284 | inode_lock(dir->d_inode); | |
3285 | else | |
3286 | inode_lock_shared(dir->d_inode); | |
896475d5 | 3287 | error = lookup_open(nd, &path, file, op, got_write, opened); |
9cf843e3 AV |
3288 | if (open_flag & O_CREAT) |
3289 | inode_unlock(dir->d_inode); | |
3290 | else | |
3291 | inode_unlock_shared(dir->d_inode); | |
a1e28038 | 3292 | |
2675a4eb AV |
3293 | if (error <= 0) { |
3294 | if (error) | |
d18e9008 MS |
3295 | goto out; |
3296 | ||
47237687 | 3297 | if ((*opened & FILE_CREATED) || |
496ad9aa | 3298 | !S_ISREG(file_inode(file)->i_mode)) |
77d660a8 | 3299 | will_truncate = false; |
d18e9008 | 3300 | |
76ae2a5a | 3301 | audit_inode(nd->name, file->f_path.dentry, 0); |
d18e9008 MS |
3302 | goto opened; |
3303 | } | |
fb1cc555 | 3304 | |
47237687 | 3305 | if (*opened & FILE_CREATED) { |
9b44f1b3 | 3306 | /* Don't check for write permission, don't truncate */ |
ca344a89 | 3307 | open_flag &= ~O_TRUNC; |
77d660a8 | 3308 | will_truncate = false; |
62fb4a15 | 3309 | acc_mode = 0; |
896475d5 | 3310 | path_to_nameidata(&path, nd); |
e83db167 | 3311 | goto finish_open_created; |
fb1cc555 AV |
3312 | } |
3313 | ||
d18e9008 MS |
3314 | /* |
3315 | * If atomic_open() acquired write access it is dropped now due to | |
3316 | * possible mount and symlink following (this might be optimized away if | |
3317 | * necessary...) | |
3318 | */ | |
64894cf8 | 3319 | if (got_write) { |
d18e9008 | 3320 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 3321 | got_write = false; |
d18e9008 MS |
3322 | } |
3323 | ||
6583fe22 AV |
3324 | if (unlikely(d_is_negative(path.dentry))) { |
3325 | path_to_nameidata(&path, nd); | |
3326 | return -ENOENT; | |
3327 | } | |
3328 | ||
3329 | /* | |
3330 | * create/update audit record if it already exists. | |
3331 | */ | |
3332 | audit_inode(nd->name, path.dentry, 0); | |
3333 | ||
deb106c6 AV |
3334 | if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { |
3335 | path_to_nameidata(&path, nd); | |
3336 | return -EEXIST; | |
3337 | } | |
fb1cc555 | 3338 | |
756daf26 | 3339 | error = follow_managed(&path, nd); |
deb106c6 AV |
3340 | if (unlikely(error < 0)) |
3341 | return error; | |
a3fbbde7 | 3342 | |
254cf582 | 3343 | seq = 0; /* out of RCU mode, so the value doesn't matter */ |
d4565649 | 3344 | inode = d_backing_inode(path.dentry); |
766c4cbf | 3345 | finish_lookup: |
d63ff28f AV |
3346 | if (nd->depth) |
3347 | put_link(nd); | |
181548c0 AV |
3348 | error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, |
3349 | inode, seq); | |
deb106c6 | 3350 | if (unlikely(error)) |
d63ff28f | 3351 | return error; |
fb1cc555 | 3352 | |
896475d5 AV |
3353 | if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { |
3354 | path_to_nameidata(&path, nd); | |
16b1c1cd MS |
3355 | } else { |
3356 | save_parent.dentry = nd->path.dentry; | |
896475d5 AV |
3357 | save_parent.mnt = mntget(path.mnt); |
3358 | nd->path.dentry = path.dentry; | |
16b1c1cd MS |
3359 | |
3360 | } | |
decf3400 | 3361 | nd->inode = inode; |
254cf582 | 3362 | nd->seq = seq; |
a3fbbde7 | 3363 | /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ |
bc77daa7 | 3364 | finish_open: |
a3fbbde7 | 3365 | error = complete_walk(nd); |
16b1c1cd MS |
3366 | if (error) { |
3367 | path_put(&save_parent); | |
2675a4eb | 3368 | return error; |
16b1c1cd | 3369 | } |
76ae2a5a | 3370 | audit_inode(nd->name, nd->path.dentry, 0); |
fb1cc555 | 3371 | error = -EISDIR; |
44b1d530 | 3372 | if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) |
2675a4eb | 3373 | goto out; |
af2f5542 | 3374 | error = -ENOTDIR; |
44b1d530 | 3375 | if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) |
2675a4eb | 3376 | goto out; |
4bbcbd3b | 3377 | if (!d_is_reg(nd->path.dentry)) |
77d660a8 | 3378 | will_truncate = false; |
6c0d46c4 | 3379 | |
0f9d1a10 AV |
3380 | if (will_truncate) { |
3381 | error = mnt_want_write(nd->path.mnt); | |
3382 | if (error) | |
2675a4eb | 3383 | goto out; |
64894cf8 | 3384 | got_write = true; |
0f9d1a10 | 3385 | } |
e83db167 | 3386 | finish_open_created: |
6ac08709 AV |
3387 | error = may_open(&nd->path, acc_mode, open_flag); |
3388 | if (error) | |
3389 | goto out; | |
4aa7c634 MS |
3390 | BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ |
3391 | error = vfs_open(&nd->path, file, current_cred()); | |
3392 | if (!error) { | |
3393 | *opened |= FILE_OPENED; | |
3394 | } else { | |
30d90494 | 3395 | if (error == -EOPENSTALE) |
f60dc3db | 3396 | goto stale_open; |
015c3bbc | 3397 | goto out; |
f60dc3db | 3398 | } |
a8277b9b | 3399 | opened: |
2675a4eb | 3400 | error = open_check_o_direct(file); |
fe9ec829 AV |
3401 | if (!error) |
3402 | error = ima_file_check(file, op->acc_mode, *opened); | |
3403 | if (!error && will_truncate) | |
2675a4eb | 3404 | error = handle_truncate(file); |
ca344a89 | 3405 | out: |
fe9ec829 AV |
3406 | if (unlikely(error) && (*opened & FILE_OPENED)) |
3407 | fput(file); | |
c80567c8 AV |
3408 | if (unlikely(error > 0)) { |
3409 | WARN_ON(1); | |
3410 | error = -EINVAL; | |
3411 | } | |
64894cf8 | 3412 | if (got_write) |
0f9d1a10 | 3413 | mnt_drop_write(nd->path.mnt); |
16b1c1cd | 3414 | path_put(&save_parent); |
2675a4eb | 3415 | return error; |
fb1cc555 | 3416 | |
f60dc3db MS |
3417 | stale_open: |
3418 | /* If no saved parent or already retried then can't retry */ | |
3419 | if (!save_parent.dentry || retried) | |
3420 | goto out; | |
3421 | ||
3422 | BUG_ON(save_parent.dentry != dir); | |
3423 | path_put(&nd->path); | |
3424 | nd->path = save_parent; | |
3425 | nd->inode = dir->d_inode; | |
3426 | save_parent.mnt = NULL; | |
3427 | save_parent.dentry = NULL; | |
64894cf8 | 3428 | if (got_write) { |
f60dc3db | 3429 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 3430 | got_write = false; |
f60dc3db MS |
3431 | } |
3432 | retried = true; | |
3433 | goto retry_lookup; | |
fb1cc555 AV |
3434 | } |
3435 | ||
c8a53ee5 | 3436 | static int do_tmpfile(struct nameidata *nd, unsigned flags, |
60545d0d AV |
3437 | const struct open_flags *op, |
3438 | struct file *file, int *opened) | |
3439 | { | |
3440 | static const struct qstr name = QSTR_INIT("/", 1); | |
625b6d10 | 3441 | struct dentry *child; |
60545d0d | 3442 | struct inode *dir; |
625b6d10 | 3443 | struct path path; |
c8a53ee5 | 3444 | int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path); |
60545d0d AV |
3445 | if (unlikely(error)) |
3446 | return error; | |
625b6d10 | 3447 | error = mnt_want_write(path.mnt); |
60545d0d AV |
3448 | if (unlikely(error)) |
3449 | goto out; | |
625b6d10 | 3450 | dir = path.dentry->d_inode; |
60545d0d | 3451 | /* we want directory to be writable */ |
625b6d10 | 3452 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
60545d0d AV |
3453 | if (error) |
3454 | goto out2; | |
60545d0d AV |
3455 | if (!dir->i_op->tmpfile) { |
3456 | error = -EOPNOTSUPP; | |
3457 | goto out2; | |
3458 | } | |
625b6d10 | 3459 | child = d_alloc(path.dentry, &name); |
60545d0d AV |
3460 | if (unlikely(!child)) { |
3461 | error = -ENOMEM; | |
3462 | goto out2; | |
3463 | } | |
625b6d10 AV |
3464 | dput(path.dentry); |
3465 | path.dentry = child; | |
3466 | error = dir->i_op->tmpfile(dir, child, op->mode); | |
60545d0d AV |
3467 | if (error) |
3468 | goto out2; | |
c8a53ee5 | 3469 | audit_inode(nd->name, child, 0); |
69a91c23 | 3470 | /* Don't check for other permissions, the inode was just created */ |
62fb4a15 | 3471 | error = may_open(&path, 0, op->open_flag); |
60545d0d AV |
3472 | if (error) |
3473 | goto out2; | |
625b6d10 AV |
3474 | file->f_path.mnt = path.mnt; |
3475 | error = finish_open(file, child, NULL, opened); | |
60545d0d AV |
3476 | if (error) |
3477 | goto out2; | |
3478 | error = open_check_o_direct(file); | |
f4e0c30c | 3479 | if (error) { |
60545d0d | 3480 | fput(file); |
f4e0c30c AV |
3481 | } else if (!(op->open_flag & O_EXCL)) { |
3482 | struct inode *inode = file_inode(file); | |
3483 | spin_lock(&inode->i_lock); | |
3484 | inode->i_state |= I_LINKABLE; | |
3485 | spin_unlock(&inode->i_lock); | |
3486 | } | |
60545d0d | 3487 | out2: |
625b6d10 | 3488 | mnt_drop_write(path.mnt); |
60545d0d | 3489 | out: |
625b6d10 | 3490 | path_put(&path); |
60545d0d AV |
3491 | return error; |
3492 | } | |
3493 | ||
6ac08709 AV |
3494 | static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file) |
3495 | { | |
3496 | struct path path; | |
3497 | int error = path_lookupat(nd, flags, &path); | |
3498 | if (!error) { | |
3499 | audit_inode(nd->name, path.dentry, 0); | |
3500 | error = vfs_open(&path, file, current_cred()); | |
3501 | path_put(&path); | |
3502 | } | |
3503 | return error; | |
3504 | } | |
3505 | ||
c8a53ee5 AV |
3506 | static struct file *path_openat(struct nameidata *nd, |
3507 | const struct open_flags *op, unsigned flags) | |
1da177e4 | 3508 | { |
368ee9ba | 3509 | const char *s; |
30d90494 | 3510 | struct file *file; |
47237687 | 3511 | int opened = 0; |
13aab428 | 3512 | int error; |
31e6b01f | 3513 | |
30d90494 | 3514 | file = get_empty_filp(); |
1afc99be AV |
3515 | if (IS_ERR(file)) |
3516 | return file; | |
31e6b01f | 3517 | |
30d90494 | 3518 | file->f_flags = op->open_flag; |
31e6b01f | 3519 | |
bb458c64 | 3520 | if (unlikely(file->f_flags & __O_TMPFILE)) { |
c8a53ee5 | 3521 | error = do_tmpfile(nd, flags, op, file, &opened); |
f15133df | 3522 | goto out2; |
60545d0d AV |
3523 | } |
3524 | ||
6ac08709 AV |
3525 | if (unlikely(file->f_flags & O_PATH)) { |
3526 | error = do_o_path(nd, flags, file); | |
3527 | if (!error) | |
3528 | opened |= FILE_OPENED; | |
3529 | goto out2; | |
3530 | } | |
3531 | ||
c8a53ee5 | 3532 | s = path_init(nd, flags); |
368ee9ba AV |
3533 | if (IS_ERR(s)) { |
3534 | put_filp(file); | |
3535 | return ERR_CAST(s); | |
3536 | } | |
3bdba28b | 3537 | while (!(error = link_path_walk(s, nd)) && |
76ae2a5a | 3538 | (error = do_last(nd, file, op, &opened)) > 0) { |
73d049a4 | 3539 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); |
3bdba28b AV |
3540 | s = trailing_symlink(nd); |
3541 | if (IS_ERR(s)) { | |
3542 | error = PTR_ERR(s); | |
2675a4eb | 3543 | break; |
3bdba28b | 3544 | } |
806b681c | 3545 | } |
deb106c6 | 3546 | terminate_walk(nd); |
f15133df | 3547 | out2: |
2675a4eb AV |
3548 | if (!(opened & FILE_OPENED)) { |
3549 | BUG_ON(!error); | |
30d90494 | 3550 | put_filp(file); |
16b1c1cd | 3551 | } |
2675a4eb AV |
3552 | if (unlikely(error)) { |
3553 | if (error == -EOPENSTALE) { | |
3554 | if (flags & LOOKUP_RCU) | |
3555 | error = -ECHILD; | |
3556 | else | |
3557 | error = -ESTALE; | |
3558 | } | |
3559 | file = ERR_PTR(error); | |
3560 | } | |
3561 | return file; | |
1da177e4 LT |
3562 | } |
3563 | ||
669abf4e | 3564 | struct file *do_filp_open(int dfd, struct filename *pathname, |
f9652e10 | 3565 | const struct open_flags *op) |
13aab428 | 3566 | { |
9883d185 | 3567 | struct nameidata nd; |
f9652e10 | 3568 | int flags = op->lookup_flags; |
13aab428 AV |
3569 | struct file *filp; |
3570 | ||
9883d185 | 3571 | set_nameidata(&nd, dfd, pathname); |
c8a53ee5 | 3572 | filp = path_openat(&nd, op, flags | LOOKUP_RCU); |
13aab428 | 3573 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
c8a53ee5 | 3574 | filp = path_openat(&nd, op, flags); |
13aab428 | 3575 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
c8a53ee5 | 3576 | filp = path_openat(&nd, op, flags | LOOKUP_REVAL); |
9883d185 | 3577 | restore_nameidata(); |
13aab428 AV |
3578 | return filp; |
3579 | } | |
3580 | ||
73d049a4 | 3581 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
f9652e10 | 3582 | const char *name, const struct open_flags *op) |
73d049a4 | 3583 | { |
9883d185 | 3584 | struct nameidata nd; |
73d049a4 | 3585 | struct file *file; |
51689104 | 3586 | struct filename *filename; |
f9652e10 | 3587 | int flags = op->lookup_flags | LOOKUP_ROOT; |
73d049a4 AV |
3588 | |
3589 | nd.root.mnt = mnt; | |
3590 | nd.root.dentry = dentry; | |
3591 | ||
b18825a7 | 3592 | if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) |
73d049a4 AV |
3593 | return ERR_PTR(-ELOOP); |
3594 | ||
51689104 | 3595 | filename = getname_kernel(name); |
a1c83681 | 3596 | if (IS_ERR(filename)) |
51689104 PM |
3597 | return ERR_CAST(filename); |
3598 | ||
9883d185 | 3599 | set_nameidata(&nd, -1, filename); |
c8a53ee5 | 3600 | file = path_openat(&nd, op, flags | LOOKUP_RCU); |
73d049a4 | 3601 | if (unlikely(file == ERR_PTR(-ECHILD))) |
c8a53ee5 | 3602 | file = path_openat(&nd, op, flags); |
73d049a4 | 3603 | if (unlikely(file == ERR_PTR(-ESTALE))) |
c8a53ee5 | 3604 | file = path_openat(&nd, op, flags | LOOKUP_REVAL); |
9883d185 | 3605 | restore_nameidata(); |
51689104 | 3606 | putname(filename); |
73d049a4 AV |
3607 | return file; |
3608 | } | |
3609 | ||
fa14a0b8 | 3610 | static struct dentry *filename_create(int dfd, struct filename *name, |
1ac12b4b | 3611 | struct path *path, unsigned int lookup_flags) |
1da177e4 | 3612 | { |
c663e5d8 | 3613 | struct dentry *dentry = ERR_PTR(-EEXIST); |
391172c4 AV |
3614 | struct qstr last; |
3615 | int type; | |
c30dabfe | 3616 | int err2; |
1ac12b4b JL |
3617 | int error; |
3618 | bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); | |
3619 | ||
3620 | /* | |
3621 | * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any | |
3622 | * other flags passed in are ignored! | |
3623 | */ | |
3624 | lookup_flags &= LOOKUP_REVAL; | |
3625 | ||
5c31b6ce AV |
3626 | name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); |
3627 | if (IS_ERR(name)) | |
3628 | return ERR_CAST(name); | |
1da177e4 | 3629 | |
c663e5d8 CH |
3630 | /* |
3631 | * Yucky last component or no last component at all? | |
3632 | * (foo/., foo/.., /////) | |
3633 | */ | |
5c31b6ce | 3634 | if (unlikely(type != LAST_NORM)) |
ed75e95d | 3635 | goto out; |
c663e5d8 | 3636 | |
c30dabfe | 3637 | /* don't fail immediately if it's r/o, at least try to report other errors */ |
391172c4 | 3638 | err2 = mnt_want_write(path->mnt); |
c663e5d8 CH |
3639 | /* |
3640 | * Do the final lookup. | |
3641 | */ | |
391172c4 | 3642 | lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL; |
5955102c | 3643 | inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); |
391172c4 | 3644 | dentry = __lookup_hash(&last, path->dentry, lookup_flags); |
1da177e4 | 3645 | if (IS_ERR(dentry)) |
a8104a9f | 3646 | goto unlock; |
c663e5d8 | 3647 | |
a8104a9f | 3648 | error = -EEXIST; |
b18825a7 | 3649 | if (d_is_positive(dentry)) |
a8104a9f | 3650 | goto fail; |
b18825a7 | 3651 | |
c663e5d8 CH |
3652 | /* |
3653 | * Special case - lookup gave negative, but... we had foo/bar/ | |
3654 | * From the vfs_mknod() POV we just have a negative dentry - | |
3655 | * all is fine. Let's be bastards - you had / on the end, you've | |
3656 | * been asking for (non-existent) directory. -ENOENT for you. | |
3657 | */ | |
391172c4 | 3658 | if (unlikely(!is_dir && last.name[last.len])) { |
a8104a9f | 3659 | error = -ENOENT; |
ed75e95d | 3660 | goto fail; |
e9baf6e5 | 3661 | } |
c30dabfe JK |
3662 | if (unlikely(err2)) { |
3663 | error = err2; | |
a8104a9f | 3664 | goto fail; |
c30dabfe | 3665 | } |
181c37b6 | 3666 | putname(name); |
1da177e4 | 3667 | return dentry; |
1da177e4 | 3668 | fail: |
a8104a9f AV |
3669 | dput(dentry); |
3670 | dentry = ERR_PTR(error); | |
3671 | unlock: | |
5955102c | 3672 | inode_unlock(path->dentry->d_inode); |
c30dabfe | 3673 | if (!err2) |
391172c4 | 3674 | mnt_drop_write(path->mnt); |
ed75e95d | 3675 | out: |
391172c4 | 3676 | path_put(path); |
181c37b6 | 3677 | putname(name); |
1da177e4 LT |
3678 | return dentry; |
3679 | } | |
fa14a0b8 AV |
3680 | |
3681 | struct dentry *kern_path_create(int dfd, const char *pathname, | |
3682 | struct path *path, unsigned int lookup_flags) | |
3683 | { | |
181c37b6 AV |
3684 | return filename_create(dfd, getname_kernel(pathname), |
3685 | path, lookup_flags); | |
fa14a0b8 | 3686 | } |
dae6ad8f AV |
3687 | EXPORT_SYMBOL(kern_path_create); |
3688 | ||
921a1650 AV |
3689 | void done_path_create(struct path *path, struct dentry *dentry) |
3690 | { | |
3691 | dput(dentry); | |
5955102c | 3692 | inode_unlock(path->dentry->d_inode); |
a8104a9f | 3693 | mnt_drop_write(path->mnt); |
921a1650 AV |
3694 | path_put(path); |
3695 | } | |
3696 | EXPORT_SYMBOL(done_path_create); | |
3697 | ||
520ae687 | 3698 | inline struct dentry *user_path_create(int dfd, const char __user *pathname, |
1ac12b4b | 3699 | struct path *path, unsigned int lookup_flags) |
dae6ad8f | 3700 | { |
181c37b6 | 3701 | return filename_create(dfd, getname(pathname), path, lookup_flags); |
dae6ad8f AV |
3702 | } |
3703 | EXPORT_SYMBOL(user_path_create); | |
3704 | ||
1a67aafb | 3705 | int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
1da177e4 | 3706 | { |
a95164d9 | 3707 | int error = may_create(dir, dentry); |
1da177e4 LT |
3708 | |
3709 | if (error) | |
3710 | return error; | |
3711 | ||
975d6b39 | 3712 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) |
1da177e4 LT |
3713 | return -EPERM; |
3714 | ||
acfa4380 | 3715 | if (!dir->i_op->mknod) |
1da177e4 LT |
3716 | return -EPERM; |
3717 | ||
08ce5f16 SH |
3718 | error = devcgroup_inode_mknod(mode, dev); |
3719 | if (error) | |
3720 | return error; | |
3721 | ||
1da177e4 LT |
3722 | error = security_inode_mknod(dir, dentry, mode, dev); |
3723 | if (error) | |
3724 | return error; | |
3725 | ||
1da177e4 | 3726 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 3727 | if (!error) |
f38aa942 | 3728 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3729 | return error; |
3730 | } | |
4d359507 | 3731 | EXPORT_SYMBOL(vfs_mknod); |
1da177e4 | 3732 | |
f69aac00 | 3733 | static int may_mknod(umode_t mode) |
463c3197 DH |
3734 | { |
3735 | switch (mode & S_IFMT) { | |
3736 | case S_IFREG: | |
3737 | case S_IFCHR: | |
3738 | case S_IFBLK: | |
3739 | case S_IFIFO: | |
3740 | case S_IFSOCK: | |
3741 | case 0: /* zero mode translates to S_IFREG */ | |
3742 | return 0; | |
3743 | case S_IFDIR: | |
3744 | return -EPERM; | |
3745 | default: | |
3746 | return -EINVAL; | |
3747 | } | |
3748 | } | |
3749 | ||
8208a22b | 3750 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, |
2e4d0924 | 3751 | unsigned, dev) |
1da177e4 | 3752 | { |
2ad94ae6 | 3753 | struct dentry *dentry; |
dae6ad8f AV |
3754 | struct path path; |
3755 | int error; | |
972567f1 | 3756 | unsigned int lookup_flags = 0; |
1da177e4 | 3757 | |
8e4bfca1 AV |
3758 | error = may_mknod(mode); |
3759 | if (error) | |
3760 | return error; | |
972567f1 JL |
3761 | retry: |
3762 | dentry = user_path_create(dfd, filename, &path, lookup_flags); | |
dae6ad8f AV |
3763 | if (IS_ERR(dentry)) |
3764 | return PTR_ERR(dentry); | |
2ad94ae6 | 3765 | |
dae6ad8f | 3766 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3767 | mode &= ~current_umask(); |
dae6ad8f | 3768 | error = security_path_mknod(&path, dentry, mode, dev); |
be6d3e56 | 3769 | if (error) |
a8104a9f | 3770 | goto out; |
463c3197 | 3771 | switch (mode & S_IFMT) { |
1da177e4 | 3772 | case 0: case S_IFREG: |
312b63fb | 3773 | error = vfs_create(path.dentry->d_inode,dentry,mode,true); |
05d1a717 MZ |
3774 | if (!error) |
3775 | ima_post_path_mknod(dentry); | |
1da177e4 LT |
3776 | break; |
3777 | case S_IFCHR: case S_IFBLK: | |
dae6ad8f | 3778 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
3779 | new_decode_dev(dev)); |
3780 | break; | |
3781 | case S_IFIFO: case S_IFSOCK: | |
dae6ad8f | 3782 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 3783 | break; |
1da177e4 | 3784 | } |
a8104a9f | 3785 | out: |
921a1650 | 3786 | done_path_create(&path, dentry); |
972567f1 JL |
3787 | if (retry_estale(error, lookup_flags)) { |
3788 | lookup_flags |= LOOKUP_REVAL; | |
3789 | goto retry; | |
3790 | } | |
1da177e4 LT |
3791 | return error; |
3792 | } | |
3793 | ||
8208a22b | 3794 | SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) |
5590ff0d UD |
3795 | { |
3796 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
3797 | } | |
3798 | ||
18bb1db3 | 3799 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
1da177e4 | 3800 | { |
a95164d9 | 3801 | int error = may_create(dir, dentry); |
8de52778 | 3802 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
3803 | |
3804 | if (error) | |
3805 | return error; | |
3806 | ||
acfa4380 | 3807 | if (!dir->i_op->mkdir) |
1da177e4 LT |
3808 | return -EPERM; |
3809 | ||
3810 | mode &= (S_IRWXUGO|S_ISVTX); | |
3811 | error = security_inode_mkdir(dir, dentry, mode); | |
3812 | if (error) | |
3813 | return error; | |
3814 | ||
8de52778 AV |
3815 | if (max_links && dir->i_nlink >= max_links) |
3816 | return -EMLINK; | |
3817 | ||
1da177e4 | 3818 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 3819 | if (!error) |
f38aa942 | 3820 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
3821 | return error; |
3822 | } | |
4d359507 | 3823 | EXPORT_SYMBOL(vfs_mkdir); |
1da177e4 | 3824 | |
a218d0fd | 3825 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) |
1da177e4 | 3826 | { |
6902d925 | 3827 | struct dentry *dentry; |
dae6ad8f AV |
3828 | struct path path; |
3829 | int error; | |
b76d8b82 | 3830 | unsigned int lookup_flags = LOOKUP_DIRECTORY; |
1da177e4 | 3831 | |
b76d8b82 JL |
3832 | retry: |
3833 | dentry = user_path_create(dfd, pathname, &path, lookup_flags); | |
6902d925 | 3834 | if (IS_ERR(dentry)) |
dae6ad8f | 3835 | return PTR_ERR(dentry); |
1da177e4 | 3836 | |
dae6ad8f | 3837 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3838 | mode &= ~current_umask(); |
dae6ad8f | 3839 | error = security_path_mkdir(&path, dentry, mode); |
a8104a9f AV |
3840 | if (!error) |
3841 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); | |
921a1650 | 3842 | done_path_create(&path, dentry); |
b76d8b82 JL |
3843 | if (retry_estale(error, lookup_flags)) { |
3844 | lookup_flags |= LOOKUP_REVAL; | |
3845 | goto retry; | |
3846 | } | |
1da177e4 LT |
3847 | return error; |
3848 | } | |
3849 | ||
a218d0fd | 3850 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) |
5590ff0d UD |
3851 | { |
3852 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
3853 | } | |
3854 | ||
1da177e4 LT |
3855 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) |
3856 | { | |
3857 | int error = may_delete(dir, dentry, 1); | |
3858 | ||
3859 | if (error) | |
3860 | return error; | |
3861 | ||
acfa4380 | 3862 | if (!dir->i_op->rmdir) |
1da177e4 LT |
3863 | return -EPERM; |
3864 | ||
1d2ef590 | 3865 | dget(dentry); |
5955102c | 3866 | inode_lock(dentry->d_inode); |
912dbc15 SW |
3867 | |
3868 | error = -EBUSY; | |
7af1364f | 3869 | if (is_local_mountpoint(dentry)) |
912dbc15 SW |
3870 | goto out; |
3871 | ||
3872 | error = security_inode_rmdir(dir, dentry); | |
3873 | if (error) | |
3874 | goto out; | |
3875 | ||
3cebde24 | 3876 | shrink_dcache_parent(dentry); |
912dbc15 SW |
3877 | error = dir->i_op->rmdir(dir, dentry); |
3878 | if (error) | |
3879 | goto out; | |
3880 | ||
3881 | dentry->d_inode->i_flags |= S_DEAD; | |
3882 | dont_mount(dentry); | |
8ed936b5 | 3883 | detach_mounts(dentry); |
912dbc15 SW |
3884 | |
3885 | out: | |
5955102c | 3886 | inode_unlock(dentry->d_inode); |
1d2ef590 | 3887 | dput(dentry); |
912dbc15 | 3888 | if (!error) |
1da177e4 | 3889 | d_delete(dentry); |
1da177e4 LT |
3890 | return error; |
3891 | } | |
4d359507 | 3892 | EXPORT_SYMBOL(vfs_rmdir); |
1da177e4 | 3893 | |
5590ff0d | 3894 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
3895 | { |
3896 | int error = 0; | |
91a27b2a | 3897 | struct filename *name; |
1da177e4 | 3898 | struct dentry *dentry; |
f5beed75 AV |
3899 | struct path path; |
3900 | struct qstr last; | |
3901 | int type; | |
c6ee9206 JL |
3902 | unsigned int lookup_flags = 0; |
3903 | retry: | |
f5beed75 AV |
3904 | name = user_path_parent(dfd, pathname, |
3905 | &path, &last, &type, lookup_flags); | |
91a27b2a JL |
3906 | if (IS_ERR(name)) |
3907 | return PTR_ERR(name); | |
1da177e4 | 3908 | |
f5beed75 | 3909 | switch (type) { |
0612d9fb OH |
3910 | case LAST_DOTDOT: |
3911 | error = -ENOTEMPTY; | |
3912 | goto exit1; | |
3913 | case LAST_DOT: | |
3914 | error = -EINVAL; | |
3915 | goto exit1; | |
3916 | case LAST_ROOT: | |
3917 | error = -EBUSY; | |
3918 | goto exit1; | |
1da177e4 | 3919 | } |
0612d9fb | 3920 | |
f5beed75 | 3921 | error = mnt_want_write(path.mnt); |
c30dabfe JK |
3922 | if (error) |
3923 | goto exit1; | |
0612d9fb | 3924 | |
5955102c | 3925 | inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); |
f5beed75 | 3926 | dentry = __lookup_hash(&last, path.dentry, lookup_flags); |
1da177e4 | 3927 | error = PTR_ERR(dentry); |
6902d925 DH |
3928 | if (IS_ERR(dentry)) |
3929 | goto exit2; | |
e6bc45d6 TT |
3930 | if (!dentry->d_inode) { |
3931 | error = -ENOENT; | |
3932 | goto exit3; | |
3933 | } | |
f5beed75 | 3934 | error = security_path_rmdir(&path, dentry); |
be6d3e56 | 3935 | if (error) |
c30dabfe | 3936 | goto exit3; |
f5beed75 | 3937 | error = vfs_rmdir(path.dentry->d_inode, dentry); |
0622753b | 3938 | exit3: |
6902d925 DH |
3939 | dput(dentry); |
3940 | exit2: | |
5955102c | 3941 | inode_unlock(path.dentry->d_inode); |
f5beed75 | 3942 | mnt_drop_write(path.mnt); |
1da177e4 | 3943 | exit1: |
f5beed75 | 3944 | path_put(&path); |
1da177e4 | 3945 | putname(name); |
c6ee9206 JL |
3946 | if (retry_estale(error, lookup_flags)) { |
3947 | lookup_flags |= LOOKUP_REVAL; | |
3948 | goto retry; | |
3949 | } | |
1da177e4 LT |
3950 | return error; |
3951 | } | |
3952 | ||
3cdad428 | 3953 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
3954 | { |
3955 | return do_rmdir(AT_FDCWD, pathname); | |
3956 | } | |
3957 | ||
b21996e3 BF |
3958 | /** |
3959 | * vfs_unlink - unlink a filesystem object | |
3960 | * @dir: parent directory | |
3961 | * @dentry: victim | |
3962 | * @delegated_inode: returns victim inode, if the inode is delegated. | |
3963 | * | |
3964 | * The caller must hold dir->i_mutex. | |
3965 | * | |
3966 | * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and | |
3967 | * return a reference to the inode in delegated_inode. The caller | |
3968 | * should then break the delegation on that inode and retry. Because | |
3969 | * breaking a delegation may take a long time, the caller should drop | |
3970 | * dir->i_mutex before doing so. | |
3971 | * | |
3972 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
3973 | * be appropriate for callers that expect the underlying filesystem not | |
3974 | * to be NFS exported. | |
3975 | */ | |
3976 | int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) | |
1da177e4 | 3977 | { |
9accbb97 | 3978 | struct inode *target = dentry->d_inode; |
1da177e4 LT |
3979 | int error = may_delete(dir, dentry, 0); |
3980 | ||
3981 | if (error) | |
3982 | return error; | |
3983 | ||
acfa4380 | 3984 | if (!dir->i_op->unlink) |
1da177e4 LT |
3985 | return -EPERM; |
3986 | ||
5955102c | 3987 | inode_lock(target); |
8ed936b5 | 3988 | if (is_local_mountpoint(dentry)) |
1da177e4 LT |
3989 | error = -EBUSY; |
3990 | else { | |
3991 | error = security_inode_unlink(dir, dentry); | |
bec1052e | 3992 | if (!error) { |
5a14696c BF |
3993 | error = try_break_deleg(target, delegated_inode); |
3994 | if (error) | |
b21996e3 | 3995 | goto out; |
1da177e4 | 3996 | error = dir->i_op->unlink(dir, dentry); |
8ed936b5 | 3997 | if (!error) { |
d83c49f3 | 3998 | dont_mount(dentry); |
8ed936b5 EB |
3999 | detach_mounts(dentry); |
4000 | } | |
bec1052e | 4001 | } |
1da177e4 | 4002 | } |
b21996e3 | 4003 | out: |
5955102c | 4004 | inode_unlock(target); |
1da177e4 LT |
4005 | |
4006 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
4007 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
9accbb97 | 4008 | fsnotify_link_count(target); |
e234f35c | 4009 | d_delete(dentry); |
1da177e4 | 4010 | } |
0eeca283 | 4011 | |
1da177e4 LT |
4012 | return error; |
4013 | } | |
4d359507 | 4014 | EXPORT_SYMBOL(vfs_unlink); |
1da177e4 LT |
4015 | |
4016 | /* | |
4017 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 4018 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
4019 | * writeout happening, and we don't want to prevent access to the directory |
4020 | * while waiting on the I/O. | |
4021 | */ | |
5590ff0d | 4022 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 4023 | { |
2ad94ae6 | 4024 | int error; |
91a27b2a | 4025 | struct filename *name; |
1da177e4 | 4026 | struct dentry *dentry; |
f5beed75 AV |
4027 | struct path path; |
4028 | struct qstr last; | |
4029 | int type; | |
1da177e4 | 4030 | struct inode *inode = NULL; |
b21996e3 | 4031 | struct inode *delegated_inode = NULL; |
5d18f813 JL |
4032 | unsigned int lookup_flags = 0; |
4033 | retry: | |
f5beed75 AV |
4034 | name = user_path_parent(dfd, pathname, |
4035 | &path, &last, &type, lookup_flags); | |
91a27b2a JL |
4036 | if (IS_ERR(name)) |
4037 | return PTR_ERR(name); | |
2ad94ae6 | 4038 | |
1da177e4 | 4039 | error = -EISDIR; |
f5beed75 | 4040 | if (type != LAST_NORM) |
1da177e4 | 4041 | goto exit1; |
0612d9fb | 4042 | |
f5beed75 | 4043 | error = mnt_want_write(path.mnt); |
c30dabfe JK |
4044 | if (error) |
4045 | goto exit1; | |
b21996e3 | 4046 | retry_deleg: |
5955102c | 4047 | inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); |
f5beed75 | 4048 | dentry = __lookup_hash(&last, path.dentry, lookup_flags); |
1da177e4 LT |
4049 | error = PTR_ERR(dentry); |
4050 | if (!IS_ERR(dentry)) { | |
4051 | /* Why not before? Because we want correct error value */ | |
f5beed75 | 4052 | if (last.name[last.len]) |
50338b88 | 4053 | goto slashes; |
1da177e4 | 4054 | inode = dentry->d_inode; |
b18825a7 | 4055 | if (d_is_negative(dentry)) |
e6bc45d6 TT |
4056 | goto slashes; |
4057 | ihold(inode); | |
f5beed75 | 4058 | error = security_path_unlink(&path, dentry); |
be6d3e56 | 4059 | if (error) |
c30dabfe | 4060 | goto exit2; |
f5beed75 | 4061 | error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); |
c30dabfe | 4062 | exit2: |
1da177e4 LT |
4063 | dput(dentry); |
4064 | } | |
5955102c | 4065 | inode_unlock(path.dentry->d_inode); |
1da177e4 LT |
4066 | if (inode) |
4067 | iput(inode); /* truncate the inode here */ | |
b21996e3 BF |
4068 | inode = NULL; |
4069 | if (delegated_inode) { | |
5a14696c | 4070 | error = break_deleg_wait(&delegated_inode); |
b21996e3 BF |
4071 | if (!error) |
4072 | goto retry_deleg; | |
4073 | } | |
f5beed75 | 4074 | mnt_drop_write(path.mnt); |
1da177e4 | 4075 | exit1: |
f5beed75 | 4076 | path_put(&path); |
1da177e4 | 4077 | putname(name); |
5d18f813 JL |
4078 | if (retry_estale(error, lookup_flags)) { |
4079 | lookup_flags |= LOOKUP_REVAL; | |
4080 | inode = NULL; | |
4081 | goto retry; | |
4082 | } | |
1da177e4 LT |
4083 | return error; |
4084 | ||
4085 | slashes: | |
b18825a7 DH |
4086 | if (d_is_negative(dentry)) |
4087 | error = -ENOENT; | |
44b1d530 | 4088 | else if (d_is_dir(dentry)) |
b18825a7 DH |
4089 | error = -EISDIR; |
4090 | else | |
4091 | error = -ENOTDIR; | |
1da177e4 LT |
4092 | goto exit2; |
4093 | } | |
4094 | ||
2e4d0924 | 4095 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
4096 | { |
4097 | if ((flag & ~AT_REMOVEDIR) != 0) | |
4098 | return -EINVAL; | |
4099 | ||
4100 | if (flag & AT_REMOVEDIR) | |
4101 | return do_rmdir(dfd, pathname); | |
4102 | ||
4103 | return do_unlinkat(dfd, pathname); | |
4104 | } | |
4105 | ||
3480b257 | 4106 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
4107 | { |
4108 | return do_unlinkat(AT_FDCWD, pathname); | |
4109 | } | |
4110 | ||
db2e747b | 4111 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 4112 | { |
a95164d9 | 4113 | int error = may_create(dir, dentry); |
1da177e4 LT |
4114 | |
4115 | if (error) | |
4116 | return error; | |
4117 | ||
acfa4380 | 4118 | if (!dir->i_op->symlink) |
1da177e4 LT |
4119 | return -EPERM; |
4120 | ||
4121 | error = security_inode_symlink(dir, dentry, oldname); | |
4122 | if (error) | |
4123 | return error; | |
4124 | ||
1da177e4 | 4125 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 4126 | if (!error) |
f38aa942 | 4127 | fsnotify_create(dir, dentry); |
1da177e4 LT |
4128 | return error; |
4129 | } | |
4d359507 | 4130 | EXPORT_SYMBOL(vfs_symlink); |
1da177e4 | 4131 | |
2e4d0924 HC |
4132 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
4133 | int, newdfd, const char __user *, newname) | |
1da177e4 | 4134 | { |
2ad94ae6 | 4135 | int error; |
91a27b2a | 4136 | struct filename *from; |
6902d925 | 4137 | struct dentry *dentry; |
dae6ad8f | 4138 | struct path path; |
f46d3567 | 4139 | unsigned int lookup_flags = 0; |
1da177e4 LT |
4140 | |
4141 | from = getname(oldname); | |
2ad94ae6 | 4142 | if (IS_ERR(from)) |
1da177e4 | 4143 | return PTR_ERR(from); |
f46d3567 JL |
4144 | retry: |
4145 | dentry = user_path_create(newdfd, newname, &path, lookup_flags); | |
6902d925 DH |
4146 | error = PTR_ERR(dentry); |
4147 | if (IS_ERR(dentry)) | |
dae6ad8f | 4148 | goto out_putname; |
6902d925 | 4149 | |
91a27b2a | 4150 | error = security_path_symlink(&path, dentry, from->name); |
a8104a9f | 4151 | if (!error) |
91a27b2a | 4152 | error = vfs_symlink(path.dentry->d_inode, dentry, from->name); |
921a1650 | 4153 | done_path_create(&path, dentry); |
f46d3567 JL |
4154 | if (retry_estale(error, lookup_flags)) { |
4155 | lookup_flags |= LOOKUP_REVAL; | |
4156 | goto retry; | |
4157 | } | |
6902d925 | 4158 | out_putname: |
1da177e4 LT |
4159 | putname(from); |
4160 | return error; | |
4161 | } | |
4162 | ||
3480b257 | 4163 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
4164 | { |
4165 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
4166 | } | |
4167 | ||
146a8595 BF |
4168 | /** |
4169 | * vfs_link - create a new link | |
4170 | * @old_dentry: object to be linked | |
4171 | * @dir: new parent | |
4172 | * @new_dentry: where to create the new link | |
4173 | * @delegated_inode: returns inode needing a delegation break | |
4174 | * | |
4175 | * The caller must hold dir->i_mutex | |
4176 | * | |
4177 | * If vfs_link discovers a delegation on the to-be-linked file in need | |
4178 | * of breaking, it will return -EWOULDBLOCK and return a reference to the | |
4179 | * inode in delegated_inode. The caller should then break the delegation | |
4180 | * and retry. Because breaking a delegation may take a long time, the | |
4181 | * caller should drop the i_mutex before doing so. | |
4182 | * | |
4183 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
4184 | * be appropriate for callers that expect the underlying filesystem not | |
4185 | * to be NFS exported. | |
4186 | */ | |
4187 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) | |
1da177e4 LT |
4188 | { |
4189 | struct inode *inode = old_dentry->d_inode; | |
8de52778 | 4190 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
4191 | int error; |
4192 | ||
4193 | if (!inode) | |
4194 | return -ENOENT; | |
4195 | ||
a95164d9 | 4196 | error = may_create(dir, new_dentry); |
1da177e4 LT |
4197 | if (error) |
4198 | return error; | |
4199 | ||
4200 | if (dir->i_sb != inode->i_sb) | |
4201 | return -EXDEV; | |
4202 | ||
4203 | /* | |
4204 | * A link to an append-only or immutable file cannot be created. | |
4205 | */ | |
4206 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
4207 | return -EPERM; | |
0bd23d09 EB |
4208 | /* |
4209 | * Updating the link count will likely cause i_uid and i_gid to | |
4210 | * be writen back improperly if their true value is unknown to | |
4211 | * the vfs. | |
4212 | */ | |
4213 | if (HAS_UNMAPPED_ID(inode)) | |
4214 | return -EPERM; | |
acfa4380 | 4215 | if (!dir->i_op->link) |
1da177e4 | 4216 | return -EPERM; |
7e79eedb | 4217 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
4218 | return -EPERM; |
4219 | ||
4220 | error = security_inode_link(old_dentry, dir, new_dentry); | |
4221 | if (error) | |
4222 | return error; | |
4223 | ||
5955102c | 4224 | inode_lock(inode); |
aae8a97d | 4225 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
f4e0c30c | 4226 | if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) |
aae8a97d | 4227 | error = -ENOENT; |
8de52778 AV |
4228 | else if (max_links && inode->i_nlink >= max_links) |
4229 | error = -EMLINK; | |
146a8595 BF |
4230 | else { |
4231 | error = try_break_deleg(inode, delegated_inode); | |
4232 | if (!error) | |
4233 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
4234 | } | |
f4e0c30c AV |
4235 | |
4236 | if (!error && (inode->i_state & I_LINKABLE)) { | |
4237 | spin_lock(&inode->i_lock); | |
4238 | inode->i_state &= ~I_LINKABLE; | |
4239 | spin_unlock(&inode->i_lock); | |
4240 | } | |
5955102c | 4241 | inode_unlock(inode); |
e31e14ec | 4242 | if (!error) |
7e79eedb | 4243 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
4244 | return error; |
4245 | } | |
4d359507 | 4246 | EXPORT_SYMBOL(vfs_link); |
1da177e4 LT |
4247 | |
4248 | /* | |
4249 | * Hardlinks are often used in delicate situations. We avoid | |
4250 | * security-related surprises by not following symlinks on the | |
4251 | * newname. --KAB | |
4252 | * | |
4253 | * We don't follow them on the oldname either to be compatible | |
4254 | * with linux 2.0, and to avoid hard-linking to directories | |
4255 | * and other special files. --ADM | |
4256 | */ | |
2e4d0924 HC |
4257 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
4258 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
4259 | { |
4260 | struct dentry *new_dentry; | |
dae6ad8f | 4261 | struct path old_path, new_path; |
146a8595 | 4262 | struct inode *delegated_inode = NULL; |
11a7b371 | 4263 | int how = 0; |
1da177e4 | 4264 | int error; |
1da177e4 | 4265 | |
11a7b371 | 4266 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
c04030e1 | 4267 | return -EINVAL; |
11a7b371 | 4268 | /* |
f0cc6ffb LT |
4269 | * To use null names we require CAP_DAC_READ_SEARCH |
4270 | * This ensures that not everyone will be able to create | |
4271 | * handlink using the passed filedescriptor. | |
11a7b371 | 4272 | */ |
f0cc6ffb LT |
4273 | if (flags & AT_EMPTY_PATH) { |
4274 | if (!capable(CAP_DAC_READ_SEARCH)) | |
4275 | return -ENOENT; | |
11a7b371 | 4276 | how = LOOKUP_EMPTY; |
f0cc6ffb | 4277 | } |
11a7b371 AK |
4278 | |
4279 | if (flags & AT_SYMLINK_FOLLOW) | |
4280 | how |= LOOKUP_FOLLOW; | |
442e31ca | 4281 | retry: |
11a7b371 | 4282 | error = user_path_at(olddfd, oldname, how, &old_path); |
1da177e4 | 4283 | if (error) |
2ad94ae6 AV |
4284 | return error; |
4285 | ||
442e31ca JL |
4286 | new_dentry = user_path_create(newdfd, newname, &new_path, |
4287 | (how & LOOKUP_REVAL)); | |
1da177e4 | 4288 | error = PTR_ERR(new_dentry); |
6902d925 | 4289 | if (IS_ERR(new_dentry)) |
dae6ad8f AV |
4290 | goto out; |
4291 | ||
4292 | error = -EXDEV; | |
4293 | if (old_path.mnt != new_path.mnt) | |
4294 | goto out_dput; | |
800179c9 KC |
4295 | error = may_linkat(&old_path); |
4296 | if (unlikely(error)) | |
4297 | goto out_dput; | |
dae6ad8f | 4298 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
be6d3e56 | 4299 | if (error) |
a8104a9f | 4300 | goto out_dput; |
146a8595 | 4301 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); |
75c3f29d | 4302 | out_dput: |
921a1650 | 4303 | done_path_create(&new_path, new_dentry); |
146a8595 BF |
4304 | if (delegated_inode) { |
4305 | error = break_deleg_wait(&delegated_inode); | |
d22e6338 OD |
4306 | if (!error) { |
4307 | path_put(&old_path); | |
146a8595 | 4308 | goto retry; |
d22e6338 | 4309 | } |
146a8595 | 4310 | } |
442e31ca | 4311 | if (retry_estale(error, how)) { |
d22e6338 | 4312 | path_put(&old_path); |
442e31ca JL |
4313 | how |= LOOKUP_REVAL; |
4314 | goto retry; | |
4315 | } | |
1da177e4 | 4316 | out: |
2d8f3038 | 4317 | path_put(&old_path); |
1da177e4 LT |
4318 | |
4319 | return error; | |
4320 | } | |
4321 | ||
3480b257 | 4322 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 4323 | { |
c04030e1 | 4324 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
4325 | } |
4326 | ||
bc27027a MS |
4327 | /** |
4328 | * vfs_rename - rename a filesystem object | |
4329 | * @old_dir: parent of source | |
4330 | * @old_dentry: source | |
4331 | * @new_dir: parent of destination | |
4332 | * @new_dentry: destination | |
4333 | * @delegated_inode: returns an inode needing a delegation break | |
520c8b16 | 4334 | * @flags: rename flags |
bc27027a MS |
4335 | * |
4336 | * The caller must hold multiple mutexes--see lock_rename()). | |
4337 | * | |
4338 | * If vfs_rename discovers a delegation in need of breaking at either | |
4339 | * the source or destination, it will return -EWOULDBLOCK and return a | |
4340 | * reference to the inode in delegated_inode. The caller should then | |
4341 | * break the delegation and retry. Because breaking a delegation may | |
4342 | * take a long time, the caller should drop all locks before doing | |
4343 | * so. | |
4344 | * | |
4345 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
4346 | * be appropriate for callers that expect the underlying filesystem not | |
4347 | * to be NFS exported. | |
4348 | * | |
1da177e4 LT |
4349 | * The worst of all namespace operations - renaming directory. "Perverted" |
4350 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
4351 | * Problems: | |
d03b29a2 | 4352 | * a) we can get into loop creation. |
1da177e4 LT |
4353 | * b) race potential - two innocent renames can create a loop together. |
4354 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 4355 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 | 4356 | * story. |
6cedba89 BF |
4357 | * c) we have to lock _four_ objects - parents and victim (if it exists), |
4358 | * and source (if it is not a directory). | |
1b1dcc1b | 4359 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
4360 | * whether the target exists). Solution: try to be smart with locking |
4361 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 4362 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
4363 | * move will be locked. Thus we can rank directories by the tree |
4364 | * (ancestors first) and rank all non-directories after them. | |
4365 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 4366 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
4367 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
4368 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
4369 | * we'd better make sure that there's no link(2) for them. | |
e4eaac06 | 4370 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
1b1dcc1b | 4371 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 4372 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
c41b20e7 | 4373 | * ->i_mutex on parents, which works but leads to some truly excessive |
1da177e4 LT |
4374 | * locking]. |
4375 | */ | |
bc27027a MS |
4376 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, |
4377 | struct inode *new_dir, struct dentry *new_dentry, | |
520c8b16 | 4378 | struct inode **delegated_inode, unsigned int flags) |
1da177e4 | 4379 | { |
bc27027a MS |
4380 | int error; |
4381 | bool is_dir = d_is_dir(old_dentry); | |
4382 | const unsigned char *old_name; | |
4383 | struct inode *source = old_dentry->d_inode; | |
9055cba7 | 4384 | struct inode *target = new_dentry->d_inode; |
da1ce067 MS |
4385 | bool new_is_dir = false; |
4386 | unsigned max_links = new_dir->i_sb->s_max_links; | |
bc27027a | 4387 | |
9409e22a MS |
4388 | /* |
4389 | * Check source == target. | |
4390 | * On overlayfs need to look at underlying inodes. | |
4391 | */ | |
4392 | if (vfs_select_inode(old_dentry, 0) == vfs_select_inode(new_dentry, 0)) | |
bc27027a MS |
4393 | return 0; |
4394 | ||
4395 | error = may_delete(old_dir, old_dentry, is_dir); | |
4396 | if (error) | |
4397 | return error; | |
4398 | ||
da1ce067 | 4399 | if (!target) { |
bc27027a | 4400 | error = may_create(new_dir, new_dentry); |
da1ce067 MS |
4401 | } else { |
4402 | new_is_dir = d_is_dir(new_dentry); | |
4403 | ||
4404 | if (!(flags & RENAME_EXCHANGE)) | |
4405 | error = may_delete(new_dir, new_dentry, is_dir); | |
4406 | else | |
4407 | error = may_delete(new_dir, new_dentry, new_is_dir); | |
4408 | } | |
bc27027a MS |
4409 | if (error) |
4410 | return error; | |
4411 | ||
7177a9c4 | 4412 | if (!old_dir->i_op->rename && !old_dir->i_op->rename2) |
bc27027a | 4413 | return -EPERM; |
1da177e4 | 4414 | |
520c8b16 MS |
4415 | if (flags && !old_dir->i_op->rename2) |
4416 | return -EINVAL; | |
4417 | ||
1da177e4 LT |
4418 | /* |
4419 | * If we are going to change the parent - check write permissions, | |
4420 | * we'll need to flip '..'. | |
4421 | */ | |
da1ce067 MS |
4422 | if (new_dir != old_dir) { |
4423 | if (is_dir) { | |
4424 | error = inode_permission(source, MAY_WRITE); | |
4425 | if (error) | |
4426 | return error; | |
4427 | } | |
4428 | if ((flags & RENAME_EXCHANGE) && new_is_dir) { | |
4429 | error = inode_permission(target, MAY_WRITE); | |
4430 | if (error) | |
4431 | return error; | |
4432 | } | |
1da177e4 LT |
4433 | } |
4434 | ||
0b3974eb MS |
4435 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, |
4436 | flags); | |
1da177e4 LT |
4437 | if (error) |
4438 | return error; | |
4439 | ||
bc27027a | 4440 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
1d2ef590 | 4441 | dget(new_dentry); |
da1ce067 | 4442 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
bc27027a MS |
4443 | lock_two_nondirectories(source, target); |
4444 | else if (target) | |
5955102c | 4445 | inode_lock(target); |
9055cba7 SW |
4446 | |
4447 | error = -EBUSY; | |
7af1364f | 4448 | if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) |
9055cba7 SW |
4449 | goto out; |
4450 | ||
da1ce067 | 4451 | if (max_links && new_dir != old_dir) { |
bc27027a | 4452 | error = -EMLINK; |
da1ce067 | 4453 | if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) |
bc27027a | 4454 | goto out; |
da1ce067 MS |
4455 | if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && |
4456 | old_dir->i_nlink >= max_links) | |
4457 | goto out; | |
4458 | } | |
4459 | if (is_dir && !(flags & RENAME_EXCHANGE) && target) | |
4460 | shrink_dcache_parent(new_dentry); | |
4461 | if (!is_dir) { | |
bc27027a | 4462 | error = try_break_deleg(source, delegated_inode); |
8e6d782c BF |
4463 | if (error) |
4464 | goto out; | |
da1ce067 MS |
4465 | } |
4466 | if (target && !new_is_dir) { | |
4467 | error = try_break_deleg(target, delegated_inode); | |
4468 | if (error) | |
4469 | goto out; | |
8e6d782c | 4470 | } |
7177a9c4 | 4471 | if (!old_dir->i_op->rename2) { |
520c8b16 MS |
4472 | error = old_dir->i_op->rename(old_dir, old_dentry, |
4473 | new_dir, new_dentry); | |
4474 | } else { | |
7177a9c4 | 4475 | WARN_ON(old_dir->i_op->rename != NULL); |
520c8b16 MS |
4476 | error = old_dir->i_op->rename2(old_dir, old_dentry, |
4477 | new_dir, new_dentry, flags); | |
4478 | } | |
51892bbb SW |
4479 | if (error) |
4480 | goto out; | |
4481 | ||
da1ce067 | 4482 | if (!(flags & RENAME_EXCHANGE) && target) { |
bc27027a MS |
4483 | if (is_dir) |
4484 | target->i_flags |= S_DEAD; | |
51892bbb | 4485 | dont_mount(new_dentry); |
8ed936b5 | 4486 | detach_mounts(new_dentry); |
bc27027a | 4487 | } |
da1ce067 MS |
4488 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { |
4489 | if (!(flags & RENAME_EXCHANGE)) | |
4490 | d_move(old_dentry, new_dentry); | |
4491 | else | |
4492 | d_exchange(old_dentry, new_dentry); | |
4493 | } | |
51892bbb | 4494 | out: |
da1ce067 | 4495 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
bc27027a MS |
4496 | unlock_two_nondirectories(source, target); |
4497 | else if (target) | |
5955102c | 4498 | inode_unlock(target); |
1da177e4 | 4499 | dput(new_dentry); |
da1ce067 | 4500 | if (!error) { |
123df294 | 4501 | fsnotify_move(old_dir, new_dir, old_name, is_dir, |
da1ce067 MS |
4502 | !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); |
4503 | if (flags & RENAME_EXCHANGE) { | |
4504 | fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, | |
4505 | new_is_dir, NULL, new_dentry); | |
4506 | } | |
4507 | } | |
0eeca283 RL |
4508 | fsnotify_oldname_free(old_name); |
4509 | ||
1da177e4 LT |
4510 | return error; |
4511 | } | |
4d359507 | 4512 | EXPORT_SYMBOL(vfs_rename); |
1da177e4 | 4513 | |
520c8b16 MS |
4514 | SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, |
4515 | int, newdfd, const char __user *, newname, unsigned int, flags) | |
1da177e4 | 4516 | { |
2ad94ae6 AV |
4517 | struct dentry *old_dentry, *new_dentry; |
4518 | struct dentry *trap; | |
f5beed75 AV |
4519 | struct path old_path, new_path; |
4520 | struct qstr old_last, new_last; | |
4521 | int old_type, new_type; | |
8e6d782c | 4522 | struct inode *delegated_inode = NULL; |
91a27b2a JL |
4523 | struct filename *from; |
4524 | struct filename *to; | |
f5beed75 | 4525 | unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; |
c6a94284 | 4526 | bool should_retry = false; |
2ad94ae6 | 4527 | int error; |
520c8b16 | 4528 | |
0d7a8555 | 4529 | if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) |
da1ce067 MS |
4530 | return -EINVAL; |
4531 | ||
0d7a8555 MS |
4532 | if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && |
4533 | (flags & RENAME_EXCHANGE)) | |
520c8b16 MS |
4534 | return -EINVAL; |
4535 | ||
0d7a8555 MS |
4536 | if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) |
4537 | return -EPERM; | |
4538 | ||
f5beed75 AV |
4539 | if (flags & RENAME_EXCHANGE) |
4540 | target_flags = 0; | |
4541 | ||
c6a94284 | 4542 | retry: |
f5beed75 AV |
4543 | from = user_path_parent(olddfd, oldname, |
4544 | &old_path, &old_last, &old_type, lookup_flags); | |
91a27b2a JL |
4545 | if (IS_ERR(from)) { |
4546 | error = PTR_ERR(from); | |
1da177e4 | 4547 | goto exit; |
91a27b2a | 4548 | } |
1da177e4 | 4549 | |
f5beed75 AV |
4550 | to = user_path_parent(newdfd, newname, |
4551 | &new_path, &new_last, &new_type, lookup_flags); | |
91a27b2a JL |
4552 | if (IS_ERR(to)) { |
4553 | error = PTR_ERR(to); | |
1da177e4 | 4554 | goto exit1; |
91a27b2a | 4555 | } |
1da177e4 LT |
4556 | |
4557 | error = -EXDEV; | |
f5beed75 | 4558 | if (old_path.mnt != new_path.mnt) |
1da177e4 LT |
4559 | goto exit2; |
4560 | ||
1da177e4 | 4561 | error = -EBUSY; |
f5beed75 | 4562 | if (old_type != LAST_NORM) |
1da177e4 LT |
4563 | goto exit2; |
4564 | ||
0a7c3937 MS |
4565 | if (flags & RENAME_NOREPLACE) |
4566 | error = -EEXIST; | |
f5beed75 | 4567 | if (new_type != LAST_NORM) |
1da177e4 LT |
4568 | goto exit2; |
4569 | ||
f5beed75 | 4570 | error = mnt_want_write(old_path.mnt); |
c30dabfe JK |
4571 | if (error) |
4572 | goto exit2; | |
4573 | ||
8e6d782c | 4574 | retry_deleg: |
f5beed75 | 4575 | trap = lock_rename(new_path.dentry, old_path.dentry); |
1da177e4 | 4576 | |
f5beed75 | 4577 | old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); |
1da177e4 LT |
4578 | error = PTR_ERR(old_dentry); |
4579 | if (IS_ERR(old_dentry)) | |
4580 | goto exit3; | |
4581 | /* source must exist */ | |
4582 | error = -ENOENT; | |
b18825a7 | 4583 | if (d_is_negative(old_dentry)) |
1da177e4 | 4584 | goto exit4; |
f5beed75 | 4585 | new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); |
0a7c3937 MS |
4586 | error = PTR_ERR(new_dentry); |
4587 | if (IS_ERR(new_dentry)) | |
4588 | goto exit4; | |
4589 | error = -EEXIST; | |
4590 | if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) | |
4591 | goto exit5; | |
da1ce067 MS |
4592 | if (flags & RENAME_EXCHANGE) { |
4593 | error = -ENOENT; | |
4594 | if (d_is_negative(new_dentry)) | |
4595 | goto exit5; | |
4596 | ||
4597 | if (!d_is_dir(new_dentry)) { | |
4598 | error = -ENOTDIR; | |
f5beed75 | 4599 | if (new_last.name[new_last.len]) |
da1ce067 MS |
4600 | goto exit5; |
4601 | } | |
4602 | } | |
1da177e4 | 4603 | /* unless the source is a directory trailing slashes give -ENOTDIR */ |
44b1d530 | 4604 | if (!d_is_dir(old_dentry)) { |
1da177e4 | 4605 | error = -ENOTDIR; |
f5beed75 | 4606 | if (old_last.name[old_last.len]) |
0a7c3937 | 4607 | goto exit5; |
f5beed75 | 4608 | if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) |
0a7c3937 | 4609 | goto exit5; |
1da177e4 LT |
4610 | } |
4611 | /* source should not be ancestor of target */ | |
4612 | error = -EINVAL; | |
4613 | if (old_dentry == trap) | |
0a7c3937 | 4614 | goto exit5; |
1da177e4 | 4615 | /* target should not be an ancestor of source */ |
da1ce067 MS |
4616 | if (!(flags & RENAME_EXCHANGE)) |
4617 | error = -ENOTEMPTY; | |
1da177e4 LT |
4618 | if (new_dentry == trap) |
4619 | goto exit5; | |
4620 | ||
f5beed75 AV |
4621 | error = security_path_rename(&old_path, old_dentry, |
4622 | &new_path, new_dentry, flags); | |
be6d3e56 | 4623 | if (error) |
c30dabfe | 4624 | goto exit5; |
f5beed75 AV |
4625 | error = vfs_rename(old_path.dentry->d_inode, old_dentry, |
4626 | new_path.dentry->d_inode, new_dentry, | |
520c8b16 | 4627 | &delegated_inode, flags); |
1da177e4 LT |
4628 | exit5: |
4629 | dput(new_dentry); | |
4630 | exit4: | |
4631 | dput(old_dentry); | |
4632 | exit3: | |
f5beed75 | 4633 | unlock_rename(new_path.dentry, old_path.dentry); |
8e6d782c BF |
4634 | if (delegated_inode) { |
4635 | error = break_deleg_wait(&delegated_inode); | |
4636 | if (!error) | |
4637 | goto retry_deleg; | |
4638 | } | |
f5beed75 | 4639 | mnt_drop_write(old_path.mnt); |
1da177e4 | 4640 | exit2: |
c6a94284 JL |
4641 | if (retry_estale(error, lookup_flags)) |
4642 | should_retry = true; | |
f5beed75 | 4643 | path_put(&new_path); |
2ad94ae6 | 4644 | putname(to); |
1da177e4 | 4645 | exit1: |
f5beed75 | 4646 | path_put(&old_path); |
1da177e4 | 4647 | putname(from); |
c6a94284 JL |
4648 | if (should_retry) { |
4649 | should_retry = false; | |
4650 | lookup_flags |= LOOKUP_REVAL; | |
4651 | goto retry; | |
4652 | } | |
2ad94ae6 | 4653 | exit: |
1da177e4 LT |
4654 | return error; |
4655 | } | |
4656 | ||
520c8b16 MS |
4657 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
4658 | int, newdfd, const char __user *, newname) | |
4659 | { | |
4660 | return sys_renameat2(olddfd, oldname, newdfd, newname, 0); | |
4661 | } | |
4662 | ||
a26eab24 | 4663 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 4664 | { |
520c8b16 | 4665 | return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
4666 | } |
4667 | ||
787fb6bc MS |
4668 | int vfs_whiteout(struct inode *dir, struct dentry *dentry) |
4669 | { | |
4670 | int error = may_create(dir, dentry); | |
4671 | if (error) | |
4672 | return error; | |
4673 | ||
4674 | if (!dir->i_op->mknod) | |
4675 | return -EPERM; | |
4676 | ||
4677 | return dir->i_op->mknod(dir, dentry, | |
4678 | S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); | |
4679 | } | |
4680 | EXPORT_SYMBOL(vfs_whiteout); | |
4681 | ||
5d826c84 | 4682 | int readlink_copy(char __user *buffer, int buflen, const char *link) |
1da177e4 | 4683 | { |
5d826c84 | 4684 | int len = PTR_ERR(link); |
1da177e4 LT |
4685 | if (IS_ERR(link)) |
4686 | goto out; | |
4687 | ||
4688 | len = strlen(link); | |
4689 | if (len > (unsigned) buflen) | |
4690 | len = buflen; | |
4691 | if (copy_to_user(buffer, link, len)) | |
4692 | len = -EFAULT; | |
4693 | out: | |
4694 | return len; | |
4695 | } | |
4696 | ||
4697 | /* | |
4698 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
6b255391 AV |
4699 | * have ->get_link() not calling nd_jump_link(). Using (or not using) it |
4700 | * for any given inode is up to filesystem. | |
1da177e4 LT |
4701 | */ |
4702 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4703 | { | |
fceef393 | 4704 | DEFINE_DELAYED_CALL(done); |
5f2c4179 AV |
4705 | struct inode *inode = d_inode(dentry); |
4706 | const char *link = inode->i_link; | |
694a1764 | 4707 | int res; |
cc314eef | 4708 | |
d4dee48b | 4709 | if (!link) { |
fceef393 | 4710 | link = inode->i_op->get_link(dentry, inode, &done); |
d4dee48b AV |
4711 | if (IS_ERR(link)) |
4712 | return PTR_ERR(link); | |
4713 | } | |
680baacb | 4714 | res = readlink_copy(buffer, buflen, link); |
fceef393 | 4715 | do_delayed_call(&done); |
694a1764 | 4716 | return res; |
1da177e4 | 4717 | } |
4d359507 | 4718 | EXPORT_SYMBOL(generic_readlink); |
1da177e4 | 4719 | |
1da177e4 | 4720 | /* get the link contents into pagecache */ |
6b255391 | 4721 | const char *page_get_link(struct dentry *dentry, struct inode *inode, |
fceef393 | 4722 | struct delayed_call *callback) |
1da177e4 | 4723 | { |
ebd09abb DG |
4724 | char *kaddr; |
4725 | struct page *page; | |
6b255391 AV |
4726 | struct address_space *mapping = inode->i_mapping; |
4727 | ||
d3883d4f AV |
4728 | if (!dentry) { |
4729 | page = find_get_page(mapping, 0); | |
4730 | if (!page) | |
4731 | return ERR_PTR(-ECHILD); | |
4732 | if (!PageUptodate(page)) { | |
4733 | put_page(page); | |
4734 | return ERR_PTR(-ECHILD); | |
4735 | } | |
4736 | } else { | |
4737 | page = read_mapping_page(mapping, 0, NULL); | |
4738 | if (IS_ERR(page)) | |
4739 | return (char*)page; | |
4740 | } | |
fceef393 | 4741 | set_delayed_call(callback, page_put_link, page); |
21fc61c7 AV |
4742 | BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM); |
4743 | kaddr = page_address(page); | |
6b255391 | 4744 | nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1); |
ebd09abb | 4745 | return kaddr; |
1da177e4 LT |
4746 | } |
4747 | ||
6b255391 | 4748 | EXPORT_SYMBOL(page_get_link); |
1da177e4 | 4749 | |
fceef393 | 4750 | void page_put_link(void *arg) |
1da177e4 | 4751 | { |
fceef393 | 4752 | put_page(arg); |
1da177e4 | 4753 | } |
4d359507 | 4754 | EXPORT_SYMBOL(page_put_link); |
1da177e4 | 4755 | |
aa80deab AV |
4756 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) |
4757 | { | |
fceef393 | 4758 | DEFINE_DELAYED_CALL(done); |
6b255391 AV |
4759 | int res = readlink_copy(buffer, buflen, |
4760 | page_get_link(dentry, d_inode(dentry), | |
fceef393 AV |
4761 | &done)); |
4762 | do_delayed_call(&done); | |
aa80deab AV |
4763 | return res; |
4764 | } | |
4765 | EXPORT_SYMBOL(page_readlink); | |
4766 | ||
54566b2c NP |
4767 | /* |
4768 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
4769 | */ | |
4770 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
4771 | { |
4772 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 4773 | struct page *page; |
afddba49 | 4774 | void *fsdata; |
beb497ab | 4775 | int err; |
54566b2c NP |
4776 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
4777 | if (nofs) | |
4778 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 4779 | |
7e53cac4 | 4780 | retry: |
afddba49 | 4781 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 4782 | flags, &page, &fsdata); |
1da177e4 | 4783 | if (err) |
afddba49 NP |
4784 | goto fail; |
4785 | ||
21fc61c7 | 4786 | memcpy(page_address(page), symname, len-1); |
afddba49 NP |
4787 | |
4788 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
4789 | page, fsdata); | |
1da177e4 LT |
4790 | if (err < 0) |
4791 | goto fail; | |
afddba49 NP |
4792 | if (err < len-1) |
4793 | goto retry; | |
4794 | ||
1da177e4 LT |
4795 | mark_inode_dirty(inode); |
4796 | return 0; | |
1da177e4 LT |
4797 | fail: |
4798 | return err; | |
4799 | } | |
4d359507 | 4800 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 | 4801 | |
0adb25d2 KK |
4802 | int page_symlink(struct inode *inode, const char *symname, int len) |
4803 | { | |
4804 | return __page_symlink(inode, symname, len, | |
c62d2555 | 4805 | !mapping_gfp_constraint(inode->i_mapping, __GFP_FS)); |
0adb25d2 | 4806 | } |
4d359507 | 4807 | EXPORT_SYMBOL(page_symlink); |
0adb25d2 | 4808 | |
92e1d5be | 4809 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 | 4810 | .readlink = generic_readlink, |
6b255391 | 4811 | .get_link = page_get_link, |
1da177e4 | 4812 | }; |
1da177e4 | 4813 | EXPORT_SYMBOL(page_symlink_inode_operations); |