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> |
1da177e4 LT |
38 | #include <asm/uaccess.h> |
39 | ||
e81e3f4d | 40 | #include "internal.h" |
c7105365 | 41 | #include "mount.h" |
e81e3f4d | 42 | |
1da177e4 LT |
43 | /* [Feb-1997 T. Schoebel-Theuer] |
44 | * Fundamental changes in the pathname lookup mechanisms (namei) | |
45 | * were necessary because of omirr. The reason is that omirr needs | |
46 | * to know the _real_ pathname, not the user-supplied one, in case | |
47 | * of symlinks (and also when transname replacements occur). | |
48 | * | |
49 | * The new code replaces the old recursive symlink resolution with | |
50 | * an iterative one (in case of non-nested symlink chains). It does | |
51 | * this with calls to <fs>_follow_link(). | |
52 | * As a side effect, dir_namei(), _namei() and follow_link() are now | |
53 | * replaced with a single function lookup_dentry() that can handle all | |
54 | * the special cases of the former code. | |
55 | * | |
56 | * With the new dcache, the pathname is stored at each inode, at least as | |
57 | * long as the refcount of the inode is positive. As a side effect, the | |
58 | * size of the dcache depends on the inode cache and thus is dynamic. | |
59 | * | |
60 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink | |
61 | * resolution to correspond with current state of the code. | |
62 | * | |
63 | * Note that the symlink resolution is not *completely* iterative. | |
64 | * There is still a significant amount of tail- and mid- recursion in | |
65 | * the algorithm. Also, note that <fs>_readlink() is not used in | |
66 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() | |
67 | * may return different results than <fs>_follow_link(). Many virtual | |
68 | * filesystems (including /proc) exhibit this behavior. | |
69 | */ | |
70 | ||
71 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: | |
72 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL | |
73 | * and the name already exists in form of a symlink, try to create the new | |
74 | * name indicated by the symlink. The old code always complained that the | |
75 | * name already exists, due to not following the symlink even if its target | |
76 | * is nonexistent. The new semantics affects also mknod() and link() when | |
25985edc | 77 | * the name is a symlink pointing to a non-existent name. |
1da177e4 LT |
78 | * |
79 | * I don't know which semantics is the right one, since I have no access | |
80 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" | |
81 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the | |
82 | * "old" one. Personally, I think the new semantics is much more logical. | |
83 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing | |
84 | * file does succeed in both HP-UX and SunOs, but not in Solaris | |
85 | * and in the old Linux semantics. | |
86 | */ | |
87 | ||
88 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink | |
89 | * semantics. See the comments in "open_namei" and "do_link" below. | |
90 | * | |
91 | * [10-Sep-98 Alan Modra] Another symlink change. | |
92 | */ | |
93 | ||
94 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: | |
95 | * inside the path - always follow. | |
96 | * in the last component in creation/removal/renaming - never follow. | |
97 | * if LOOKUP_FOLLOW passed - follow. | |
98 | * if the pathname has trailing slashes - follow. | |
99 | * otherwise - don't follow. | |
100 | * (applied in that order). | |
101 | * | |
102 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT | |
103 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. | |
104 | * During the 2.4 we need to fix the userland stuff depending on it - | |
105 | * hopefully we will be able to get rid of that wart in 2.5. So far only | |
106 | * XEmacs seems to be relying on it... | |
107 | */ | |
108 | /* | |
109 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) | |
a11f3a05 | 110 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
1da177e4 LT |
111 | * any extra contention... |
112 | */ | |
113 | ||
114 | /* In order to reduce some races, while at the same time doing additional | |
115 | * checking and hopefully speeding things up, we copy filenames to the | |
116 | * kernel data space before using them.. | |
117 | * | |
118 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). | |
119 | * PATH_MAX includes the nul terminator --RR. | |
120 | */ | |
91a27b2a | 121 | |
7950e385 JL |
122 | #define EMBEDDED_NAME_MAX (PATH_MAX - sizeof(struct filename)) |
123 | ||
51f39a1f | 124 | struct filename * |
91a27b2a JL |
125 | getname_flags(const char __user *filename, int flags, int *empty) |
126 | { | |
94b5d262 | 127 | struct filename *result; |
7950e385 | 128 | char *kname; |
94b5d262 | 129 | int len; |
4043cde8 | 130 | |
7ac86265 JL |
131 | result = audit_reusename(filename); |
132 | if (result) | |
133 | return result; | |
134 | ||
7950e385 | 135 | result = __getname(); |
3f9f0aa6 | 136 | if (unlikely(!result)) |
4043cde8 EP |
137 | return ERR_PTR(-ENOMEM); |
138 | ||
7950e385 JL |
139 | /* |
140 | * First, try to embed the struct filename inside the names_cache | |
141 | * allocation | |
142 | */ | |
143 | kname = (char *)result + sizeof(*result); | |
91a27b2a | 144 | result->name = kname; |
7950e385 | 145 | result->separate = false; |
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)) { |
7950e385 JL |
160 | kname = (char *)result; |
161 | ||
162 | result = kzalloc(sizeof(*result), GFP_KERNEL); | |
94b5d262 AV |
163 | if (unlikely(!result)) { |
164 | __putname(kname); | |
165 | return ERR_PTR(-ENOMEM); | |
7950e385 JL |
166 | } |
167 | result->name = kname; | |
168 | result->separate = true; | |
94b5d262 AV |
169 | len = strncpy_from_user(kname, filename, PATH_MAX); |
170 | if (unlikely(len < 0)) { | |
171 | __putname(kname); | |
172 | kfree(result); | |
173 | return ERR_PTR(len); | |
174 | } | |
175 | if (unlikely(len == PATH_MAX)) { | |
176 | __putname(kname); | |
177 | kfree(result); | |
178 | return ERR_PTR(-ENAMETOOLONG); | |
179 | } | |
7950e385 JL |
180 | } |
181 | ||
94b5d262 | 182 | result->refcnt = 1; |
3f9f0aa6 LT |
183 | /* The empty path is special. */ |
184 | if (unlikely(!len)) { | |
185 | if (empty) | |
4043cde8 | 186 | *empty = 1; |
94b5d262 AV |
187 | if (!(flags & LOOKUP_EMPTY)) { |
188 | putname(result); | |
189 | return ERR_PTR(-ENOENT); | |
190 | } | |
1da177e4 | 191 | } |
3f9f0aa6 | 192 | |
7950e385 | 193 | result->uptr = filename; |
c4ad8f98 | 194 | result->aname = NULL; |
7950e385 JL |
195 | audit_getname(result); |
196 | return result; | |
1da177e4 LT |
197 | } |
198 | ||
91a27b2a JL |
199 | struct filename * |
200 | getname(const char __user * filename) | |
f52e0c11 | 201 | { |
f7493e5d | 202 | return getname_flags(filename, 0, NULL); |
f52e0c11 AV |
203 | } |
204 | ||
c4ad8f98 LT |
205 | struct filename * |
206 | getname_kernel(const char * filename) | |
207 | { | |
208 | struct filename *result; | |
08518549 | 209 | int len = strlen(filename) + 1; |
c4ad8f98 LT |
210 | |
211 | result = __getname(); | |
212 | if (unlikely(!result)) | |
213 | return ERR_PTR(-ENOMEM); | |
214 | ||
08518549 PM |
215 | if (len <= EMBEDDED_NAME_MAX) { |
216 | result->name = (char *)(result) + sizeof(*result); | |
217 | result->separate = false; | |
218 | } else if (len <= PATH_MAX) { | |
219 | struct filename *tmp; | |
220 | ||
221 | tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); | |
222 | if (unlikely(!tmp)) { | |
223 | __putname(result); | |
224 | return ERR_PTR(-ENOMEM); | |
225 | } | |
226 | tmp->name = (char *)result; | |
227 | tmp->separate = true; | |
228 | result = tmp; | |
229 | } else { | |
230 | __putname(result); | |
231 | return ERR_PTR(-ENAMETOOLONG); | |
232 | } | |
233 | memcpy((char *)result->name, filename, len); | |
c4ad8f98 LT |
234 | result->uptr = NULL; |
235 | result->aname = NULL; | |
55422d0b | 236 | result->refcnt = 1; |
fd3522fd | 237 | audit_getname(result); |
c4ad8f98 | 238 | |
c4ad8f98 LT |
239 | return result; |
240 | } | |
241 | ||
91a27b2a | 242 | void putname(struct filename *name) |
1da177e4 | 243 | { |
55422d0b PM |
244 | BUG_ON(name->refcnt <= 0); |
245 | ||
246 | if (--name->refcnt > 0) | |
247 | return; | |
248 | ||
249 | if (name->separate) { | |
250 | __putname(name->name); | |
251 | kfree(name); | |
252 | } else | |
253 | __putname(name); | |
1da177e4 | 254 | } |
1da177e4 | 255 | |
e77819e5 LT |
256 | static int check_acl(struct inode *inode, int mask) |
257 | { | |
84635d68 | 258 | #ifdef CONFIG_FS_POSIX_ACL |
e77819e5 LT |
259 | struct posix_acl *acl; |
260 | ||
e77819e5 | 261 | if (mask & MAY_NOT_BLOCK) { |
3567866b AV |
262 | acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); |
263 | if (!acl) | |
e77819e5 | 264 | return -EAGAIN; |
3567866b AV |
265 | /* no ->get_acl() calls in RCU mode... */ |
266 | if (acl == ACL_NOT_CACHED) | |
267 | return -ECHILD; | |
206b1d09 | 268 | return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); |
e77819e5 LT |
269 | } |
270 | ||
2982baa2 CH |
271 | acl = get_acl(inode, ACL_TYPE_ACCESS); |
272 | if (IS_ERR(acl)) | |
273 | return PTR_ERR(acl); | |
e77819e5 LT |
274 | if (acl) { |
275 | int error = posix_acl_permission(inode, acl, mask); | |
276 | posix_acl_release(acl); | |
277 | return error; | |
278 | } | |
84635d68 | 279 | #endif |
e77819e5 LT |
280 | |
281 | return -EAGAIN; | |
282 | } | |
283 | ||
5909ccaa | 284 | /* |
948409c7 | 285 | * This does the basic permission checking |
1da177e4 | 286 | */ |
7e40145e | 287 | static int acl_permission_check(struct inode *inode, int mask) |
1da177e4 | 288 | { |
26cf46be | 289 | unsigned int mode = inode->i_mode; |
1da177e4 | 290 | |
8e96e3b7 | 291 | if (likely(uid_eq(current_fsuid(), inode->i_uid))) |
1da177e4 LT |
292 | mode >>= 6; |
293 | else { | |
e77819e5 | 294 | if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { |
7e40145e | 295 | int error = check_acl(inode, mask); |
b74c79e9 NP |
296 | if (error != -EAGAIN) |
297 | return error; | |
1da177e4 LT |
298 | } |
299 | ||
300 | if (in_group_p(inode->i_gid)) | |
301 | mode >>= 3; | |
302 | } | |
303 | ||
304 | /* | |
305 | * If the DACs are ok we don't need any capability check. | |
306 | */ | |
9c2c7039 | 307 | if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) |
1da177e4 | 308 | return 0; |
5909ccaa LT |
309 | return -EACCES; |
310 | } | |
311 | ||
312 | /** | |
b74c79e9 | 313 | * generic_permission - check for access rights on a Posix-like filesystem |
5909ccaa | 314 | * @inode: inode to check access rights for |
8fd90c8d | 315 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) |
5909ccaa LT |
316 | * |
317 | * Used to check for read/write/execute permissions on a file. | |
318 | * We use "fsuid" for this, letting us set arbitrary permissions | |
319 | * for filesystem access without changing the "normal" uids which | |
b74c79e9 NP |
320 | * are used for other things. |
321 | * | |
322 | * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk | |
323 | * request cannot be satisfied (eg. requires blocking or too much complexity). | |
324 | * It would then be called again in ref-walk mode. | |
5909ccaa | 325 | */ |
2830ba7f | 326 | int generic_permission(struct inode *inode, int mask) |
5909ccaa LT |
327 | { |
328 | int ret; | |
329 | ||
330 | /* | |
948409c7 | 331 | * Do the basic permission checks. |
5909ccaa | 332 | */ |
7e40145e | 333 | ret = acl_permission_check(inode, mask); |
5909ccaa LT |
334 | if (ret != -EACCES) |
335 | return ret; | |
1da177e4 | 336 | |
d594e7ec AV |
337 | if (S_ISDIR(inode->i_mode)) { |
338 | /* DACs are overridable for directories */ | |
23adbe12 | 339 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) |
d594e7ec AV |
340 | return 0; |
341 | if (!(mask & MAY_WRITE)) | |
23adbe12 AL |
342 | if (capable_wrt_inode_uidgid(inode, |
343 | CAP_DAC_READ_SEARCH)) | |
d594e7ec AV |
344 | return 0; |
345 | return -EACCES; | |
346 | } | |
1da177e4 LT |
347 | /* |
348 | * Read/write DACs are always overridable. | |
d594e7ec AV |
349 | * Executable DACs are overridable when there is |
350 | * at least one exec bit set. | |
1da177e4 | 351 | */ |
d594e7ec | 352 | if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) |
23adbe12 | 353 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) |
1da177e4 LT |
354 | return 0; |
355 | ||
356 | /* | |
357 | * Searching includes executable on directories, else just read. | |
358 | */ | |
7ea66001 | 359 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
d594e7ec | 360 | if (mask == MAY_READ) |
23adbe12 | 361 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) |
1da177e4 LT |
362 | return 0; |
363 | ||
364 | return -EACCES; | |
365 | } | |
4d359507 | 366 | EXPORT_SYMBOL(generic_permission); |
1da177e4 | 367 | |
3ddcd056 LT |
368 | /* |
369 | * We _really_ want to just do "generic_permission()" without | |
370 | * even looking at the inode->i_op values. So we keep a cache | |
371 | * flag in inode->i_opflags, that says "this has not special | |
372 | * permission function, use the fast case". | |
373 | */ | |
374 | static inline int do_inode_permission(struct inode *inode, int mask) | |
375 | { | |
376 | if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { | |
377 | if (likely(inode->i_op->permission)) | |
378 | return inode->i_op->permission(inode, mask); | |
379 | ||
380 | /* This gets set once for the inode lifetime */ | |
381 | spin_lock(&inode->i_lock); | |
382 | inode->i_opflags |= IOP_FASTPERM; | |
383 | spin_unlock(&inode->i_lock); | |
384 | } | |
385 | return generic_permission(inode, mask); | |
386 | } | |
387 | ||
cb23beb5 | 388 | /** |
0bdaea90 DH |
389 | * __inode_permission - Check for access rights to a given inode |
390 | * @inode: Inode to check permission on | |
391 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
cb23beb5 | 392 | * |
0bdaea90 | 393 | * Check for read/write/execute permissions on an inode. |
948409c7 AG |
394 | * |
395 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
0bdaea90 DH |
396 | * |
397 | * This does not check for a read-only file system. You probably want | |
398 | * inode_permission(). | |
cb23beb5 | 399 | */ |
0bdaea90 | 400 | int __inode_permission(struct inode *inode, int mask) |
1da177e4 | 401 | { |
e6305c43 | 402 | int retval; |
1da177e4 | 403 | |
3ddcd056 | 404 | if (unlikely(mask & MAY_WRITE)) { |
1da177e4 LT |
405 | /* |
406 | * Nobody gets write access to an immutable file. | |
407 | */ | |
408 | if (IS_IMMUTABLE(inode)) | |
409 | return -EACCES; | |
410 | } | |
411 | ||
3ddcd056 | 412 | retval = do_inode_permission(inode, mask); |
1da177e4 LT |
413 | if (retval) |
414 | return retval; | |
415 | ||
08ce5f16 SH |
416 | retval = devcgroup_inode_permission(inode, mask); |
417 | if (retval) | |
418 | return retval; | |
419 | ||
d09ca739 | 420 | return security_inode_permission(inode, mask); |
1da177e4 | 421 | } |
bd5d0856 | 422 | EXPORT_SYMBOL(__inode_permission); |
1da177e4 | 423 | |
0bdaea90 DH |
424 | /** |
425 | * sb_permission - Check superblock-level permissions | |
426 | * @sb: Superblock of inode to check permission on | |
55852635 | 427 | * @inode: Inode to check permission on |
0bdaea90 DH |
428 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
429 | * | |
430 | * Separate out file-system wide checks from inode-specific permission checks. | |
431 | */ | |
432 | static int sb_permission(struct super_block *sb, struct inode *inode, int mask) | |
433 | { | |
434 | if (unlikely(mask & MAY_WRITE)) { | |
435 | umode_t mode = inode->i_mode; | |
436 | ||
437 | /* Nobody gets write access to a read-only fs. */ | |
438 | if ((sb->s_flags & MS_RDONLY) && | |
439 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
440 | return -EROFS; | |
441 | } | |
442 | return 0; | |
443 | } | |
444 | ||
445 | /** | |
446 | * inode_permission - Check for access rights to a given inode | |
447 | * @inode: Inode to check permission on | |
448 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
449 | * | |
450 | * Check for read/write/execute permissions on an inode. We use fs[ug]id for | |
451 | * this, letting us set arbitrary permissions for filesystem access without | |
452 | * changing the "normal" UIDs which are used for other things. | |
453 | * | |
454 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
455 | */ | |
456 | int inode_permission(struct inode *inode, int mask) | |
457 | { | |
458 | int retval; | |
459 | ||
460 | retval = sb_permission(inode->i_sb, inode, mask); | |
461 | if (retval) | |
462 | return retval; | |
463 | return __inode_permission(inode, mask); | |
464 | } | |
4d359507 | 465 | EXPORT_SYMBOL(inode_permission); |
0bdaea90 | 466 | |
5dd784d0 JB |
467 | /** |
468 | * path_get - get a reference to a path | |
469 | * @path: path to get the reference to | |
470 | * | |
471 | * Given a path increment the reference count to the dentry and the vfsmount. | |
472 | */ | |
dcf787f3 | 473 | void path_get(const struct path *path) |
5dd784d0 JB |
474 | { |
475 | mntget(path->mnt); | |
476 | dget(path->dentry); | |
477 | } | |
478 | EXPORT_SYMBOL(path_get); | |
479 | ||
1d957f9b JB |
480 | /** |
481 | * path_put - put a reference to a path | |
482 | * @path: path to put the reference to | |
483 | * | |
484 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
485 | */ | |
dcf787f3 | 486 | void path_put(const struct path *path) |
1da177e4 | 487 | { |
1d957f9b JB |
488 | dput(path->dentry); |
489 | mntput(path->mnt); | |
1da177e4 | 490 | } |
1d957f9b | 491 | EXPORT_SYMBOL(path_put); |
1da177e4 | 492 | |
1f55a6ec AV |
493 | struct nameidata { |
494 | struct path path; | |
495 | struct qstr last; | |
496 | struct path root; | |
497 | struct inode *inode; /* path.dentry.d_inode */ | |
498 | unsigned int flags; | |
499 | unsigned seq, m_seq; | |
500 | int last_type; | |
501 | unsigned depth; | |
5e53084d | 502 | struct file *base; |
1f55a6ec AV |
503 | char *saved_names[MAX_NESTED_LINKS + 1]; |
504 | }; | |
505 | ||
19660af7 | 506 | /* |
31e6b01f | 507 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
19660af7 AV |
508 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
509 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab | |
510 | * normal reference counts on dentries and vfsmounts to transition to rcu-walk | |
511 | * mode. Refcounts are grabbed at the last known good point before rcu-walk | |
512 | * got stuck, so ref-walk may continue from there. If this is not successful | |
513 | * (eg. a seqcount has changed), then failure is returned and it's up to caller | |
514 | * to restart the path walk from the beginning in ref-walk mode. | |
31e6b01f | 515 | */ |
31e6b01f NP |
516 | |
517 | /** | |
19660af7 AV |
518 | * unlazy_walk - try to switch to ref-walk mode. |
519 | * @nd: nameidata pathwalk data | |
520 | * @dentry: child of nd->path.dentry or NULL | |
39191628 | 521 | * Returns: 0 on success, -ECHILD on failure |
31e6b01f | 522 | * |
19660af7 AV |
523 | * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry |
524 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on | |
525 | * @nd or NULL. Must be called from rcu-walk context. | |
31e6b01f | 526 | */ |
19660af7 | 527 | static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) |
31e6b01f NP |
528 | { |
529 | struct fs_struct *fs = current->fs; | |
530 | struct dentry *parent = nd->path.dentry; | |
531 | ||
532 | BUG_ON(!(nd->flags & LOOKUP_RCU)); | |
e5c832d5 LT |
533 | |
534 | /* | |
48a066e7 AV |
535 | * After legitimizing the bastards, terminate_walk() |
536 | * will do the right thing for non-RCU mode, and all our | |
537 | * subsequent exit cases should rcu_read_unlock() | |
538 | * before returning. Do vfsmount first; if dentry | |
539 | * can't be legitimized, just set nd->path.dentry to NULL | |
540 | * and rely on dput(NULL) being a no-op. | |
e5c832d5 | 541 | */ |
48a066e7 | 542 | if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) |
e5c832d5 | 543 | return -ECHILD; |
e5c832d5 | 544 | nd->flags &= ~LOOKUP_RCU; |
15570086 | 545 | |
48a066e7 AV |
546 | if (!lockref_get_not_dead(&parent->d_lockref)) { |
547 | nd->path.dentry = NULL; | |
d870b4a1 | 548 | goto out; |
48a066e7 AV |
549 | } |
550 | ||
15570086 LT |
551 | /* |
552 | * For a negative lookup, the lookup sequence point is the parents | |
553 | * sequence point, and it only needs to revalidate the parent dentry. | |
554 | * | |
555 | * For a positive lookup, we need to move both the parent and the | |
556 | * dentry from the RCU domain to be properly refcounted. And the | |
557 | * sequence number in the dentry validates *both* dentry counters, | |
558 | * since we checked the sequence number of the parent after we got | |
559 | * the child sequence number. So we know the parent must still | |
560 | * be valid if the child sequence number is still valid. | |
561 | */ | |
19660af7 | 562 | if (!dentry) { |
e5c832d5 LT |
563 | if (read_seqcount_retry(&parent->d_seq, nd->seq)) |
564 | goto out; | |
19660af7 AV |
565 | BUG_ON(nd->inode != parent->d_inode); |
566 | } else { | |
e5c832d5 LT |
567 | if (!lockref_get_not_dead(&dentry->d_lockref)) |
568 | goto out; | |
569 | if (read_seqcount_retry(&dentry->d_seq, nd->seq)) | |
570 | goto drop_dentry; | |
19660af7 | 571 | } |
e5c832d5 LT |
572 | |
573 | /* | |
574 | * Sequence counts matched. Now make sure that the root is | |
575 | * still valid and get it if required. | |
576 | */ | |
577 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { | |
578 | spin_lock(&fs->lock); | |
579 | if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) | |
580 | goto unlock_and_drop_dentry; | |
31e6b01f NP |
581 | path_get(&nd->root); |
582 | spin_unlock(&fs->lock); | |
583 | } | |
31e6b01f | 584 | |
8b61e74f | 585 | rcu_read_unlock(); |
31e6b01f | 586 | return 0; |
19660af7 | 587 | |
e5c832d5 LT |
588 | unlock_and_drop_dentry: |
589 | spin_unlock(&fs->lock); | |
590 | drop_dentry: | |
8b61e74f | 591 | rcu_read_unlock(); |
15570086 | 592 | dput(dentry); |
d0d27277 | 593 | goto drop_root_mnt; |
e5c832d5 | 594 | out: |
8b61e74f | 595 | rcu_read_unlock(); |
d0d27277 LT |
596 | drop_root_mnt: |
597 | if (!(nd->flags & LOOKUP_ROOT)) | |
598 | nd->root.mnt = NULL; | |
31e6b01f NP |
599 | return -ECHILD; |
600 | } | |
601 | ||
4ce16ef3 | 602 | static inline int d_revalidate(struct dentry *dentry, unsigned int flags) |
34286d66 | 603 | { |
4ce16ef3 | 604 | return dentry->d_op->d_revalidate(dentry, flags); |
34286d66 NP |
605 | } |
606 | ||
9f1fafee AV |
607 | /** |
608 | * complete_walk - successful completion of path walk | |
609 | * @nd: pointer nameidata | |
39159de2 | 610 | * |
9f1fafee AV |
611 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
612 | * Revalidate the final result, unless we'd already done that during | |
613 | * the path walk or the filesystem doesn't ask for it. Return 0 on | |
614 | * success, -error on failure. In case of failure caller does not | |
615 | * need to drop nd->path. | |
39159de2 | 616 | */ |
9f1fafee | 617 | static int complete_walk(struct nameidata *nd) |
39159de2 | 618 | { |
16c2cd71 | 619 | struct dentry *dentry = nd->path.dentry; |
39159de2 | 620 | int status; |
39159de2 | 621 | |
9f1fafee AV |
622 | if (nd->flags & LOOKUP_RCU) { |
623 | nd->flags &= ~LOOKUP_RCU; | |
624 | if (!(nd->flags & LOOKUP_ROOT)) | |
625 | nd->root.mnt = NULL; | |
15570086 | 626 | |
48a066e7 | 627 | if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { |
8b61e74f | 628 | rcu_read_unlock(); |
48a066e7 AV |
629 | return -ECHILD; |
630 | } | |
e5c832d5 | 631 | if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { |
8b61e74f | 632 | rcu_read_unlock(); |
48a066e7 | 633 | mntput(nd->path.mnt); |
e5c832d5 LT |
634 | return -ECHILD; |
635 | } | |
636 | if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { | |
8b61e74f | 637 | rcu_read_unlock(); |
e5c832d5 | 638 | dput(dentry); |
48a066e7 | 639 | mntput(nd->path.mnt); |
9f1fafee AV |
640 | return -ECHILD; |
641 | } | |
8b61e74f | 642 | rcu_read_unlock(); |
9f1fafee AV |
643 | } |
644 | ||
16c2cd71 AV |
645 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
646 | return 0; | |
647 | ||
ecf3d1f1 | 648 | if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) |
39159de2 JL |
649 | return 0; |
650 | ||
ecf3d1f1 | 651 | status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); |
39159de2 JL |
652 | if (status > 0) |
653 | return 0; | |
654 | ||
16c2cd71 | 655 | if (!status) |
39159de2 | 656 | status = -ESTALE; |
16c2cd71 | 657 | |
9f1fafee | 658 | path_put(&nd->path); |
39159de2 JL |
659 | return status; |
660 | } | |
661 | ||
2a737871 AV |
662 | static __always_inline void set_root(struct nameidata *nd) |
663 | { | |
7bd88377 | 664 | get_fs_root(current->fs, &nd->root); |
2a737871 AV |
665 | } |
666 | ||
6de88d72 AV |
667 | static int link_path_walk(const char *, struct nameidata *); |
668 | ||
7bd88377 | 669 | static __always_inline unsigned set_root_rcu(struct nameidata *nd) |
31e6b01f | 670 | { |
7bd88377 AV |
671 | struct fs_struct *fs = current->fs; |
672 | unsigned seq, res; | |
c28cc364 | 673 | |
7bd88377 AV |
674 | do { |
675 | seq = read_seqcount_begin(&fs->seq); | |
676 | nd->root = fs->root; | |
677 | res = __read_seqcount_begin(&nd->root.dentry->d_seq); | |
678 | } while (read_seqcount_retry(&fs->seq, seq)); | |
679 | return res; | |
31e6b01f NP |
680 | } |
681 | ||
1d957f9b | 682 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
683 | { |
684 | dput(path->dentry); | |
4ac91378 | 685 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
686 | mntput(path->mnt); |
687 | } | |
688 | ||
7b9337aa NP |
689 | static inline void path_to_nameidata(const struct path *path, |
690 | struct nameidata *nd) | |
051d3812 | 691 | { |
31e6b01f NP |
692 | if (!(nd->flags & LOOKUP_RCU)) { |
693 | dput(nd->path.dentry); | |
694 | if (nd->path.mnt != path->mnt) | |
695 | mntput(nd->path.mnt); | |
9a229683 | 696 | } |
31e6b01f | 697 | nd->path.mnt = path->mnt; |
4ac91378 | 698 | nd->path.dentry = path->dentry; |
051d3812 IK |
699 | } |
700 | ||
b5fb63c1 CH |
701 | /* |
702 | * Helper to directly jump to a known parsed path from ->follow_link, | |
703 | * caller must have taken a reference to path beforehand. | |
704 | */ | |
705 | void nd_jump_link(struct nameidata *nd, struct path *path) | |
706 | { | |
707 | path_put(&nd->path); | |
708 | ||
709 | nd->path = *path; | |
710 | nd->inode = nd->path.dentry->d_inode; | |
711 | nd->flags |= LOOKUP_JUMPED; | |
b5fb63c1 CH |
712 | } |
713 | ||
1f55a6ec AV |
714 | void nd_set_link(struct nameidata *nd, char *path) |
715 | { | |
716 | nd->saved_names[nd->depth] = path; | |
717 | } | |
718 | EXPORT_SYMBOL(nd_set_link); | |
719 | ||
720 | char *nd_get_link(struct nameidata *nd) | |
721 | { | |
722 | return nd->saved_names[nd->depth]; | |
723 | } | |
724 | EXPORT_SYMBOL(nd_get_link); | |
725 | ||
574197e0 AV |
726 | static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) |
727 | { | |
728 | struct inode *inode = link->dentry->d_inode; | |
6d7b5aae | 729 | if (inode->i_op->put_link) |
574197e0 AV |
730 | inode->i_op->put_link(link->dentry, nd, cookie); |
731 | path_put(link); | |
732 | } | |
733 | ||
561ec64a LT |
734 | int sysctl_protected_symlinks __read_mostly = 0; |
735 | int sysctl_protected_hardlinks __read_mostly = 0; | |
800179c9 KC |
736 | |
737 | /** | |
738 | * may_follow_link - Check symlink following for unsafe situations | |
739 | * @link: The path of the symlink | |
55852635 | 740 | * @nd: nameidata pathwalk data |
800179c9 KC |
741 | * |
742 | * In the case of the sysctl_protected_symlinks sysctl being enabled, | |
743 | * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is | |
744 | * in a sticky world-writable directory. This is to protect privileged | |
745 | * processes from failing races against path names that may change out | |
746 | * from under them by way of other users creating malicious symlinks. | |
747 | * It will permit symlinks to be followed only when outside a sticky | |
748 | * world-writable directory, or when the uid of the symlink and follower | |
749 | * match, or when the directory owner matches the symlink's owner. | |
750 | * | |
751 | * Returns 0 if following the symlink is allowed, -ve on error. | |
752 | */ | |
753 | static inline int may_follow_link(struct path *link, struct nameidata *nd) | |
754 | { | |
755 | const struct inode *inode; | |
756 | const struct inode *parent; | |
757 | ||
758 | if (!sysctl_protected_symlinks) | |
759 | return 0; | |
760 | ||
761 | /* Allowed if owner and follower match. */ | |
762 | inode = link->dentry->d_inode; | |
81abe27b | 763 | if (uid_eq(current_cred()->fsuid, inode->i_uid)) |
800179c9 KC |
764 | return 0; |
765 | ||
766 | /* Allowed if parent directory not sticky and world-writable. */ | |
767 | parent = nd->path.dentry->d_inode; | |
768 | if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) | |
769 | return 0; | |
770 | ||
771 | /* Allowed if parent directory and link owner match. */ | |
81abe27b | 772 | if (uid_eq(parent->i_uid, inode->i_uid)) |
800179c9 KC |
773 | return 0; |
774 | ||
ffd8d101 | 775 | audit_log_link_denied("follow_link", link); |
800179c9 KC |
776 | path_put_conditional(link, nd); |
777 | path_put(&nd->path); | |
778 | return -EACCES; | |
779 | } | |
780 | ||
781 | /** | |
782 | * safe_hardlink_source - Check for safe hardlink conditions | |
783 | * @inode: the source inode to hardlink from | |
784 | * | |
785 | * Return false if at least one of the following conditions: | |
786 | * - inode is not a regular file | |
787 | * - inode is setuid | |
788 | * - inode is setgid and group-exec | |
789 | * - access failure for read and write | |
790 | * | |
791 | * Otherwise returns true. | |
792 | */ | |
793 | static bool safe_hardlink_source(struct inode *inode) | |
794 | { | |
795 | umode_t mode = inode->i_mode; | |
796 | ||
797 | /* Special files should not get pinned to the filesystem. */ | |
798 | if (!S_ISREG(mode)) | |
799 | return false; | |
800 | ||
801 | /* Setuid files should not get pinned to the filesystem. */ | |
802 | if (mode & S_ISUID) | |
803 | return false; | |
804 | ||
805 | /* Executable setgid files should not get pinned to the filesystem. */ | |
806 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) | |
807 | return false; | |
808 | ||
809 | /* Hardlinking to unreadable or unwritable sources is dangerous. */ | |
810 | if (inode_permission(inode, MAY_READ | MAY_WRITE)) | |
811 | return false; | |
812 | ||
813 | return true; | |
814 | } | |
815 | ||
816 | /** | |
817 | * may_linkat - Check permissions for creating a hardlink | |
818 | * @link: the source to hardlink from | |
819 | * | |
820 | * Block hardlink when all of: | |
821 | * - sysctl_protected_hardlinks enabled | |
822 | * - fsuid does not match inode | |
823 | * - hardlink source is unsafe (see safe_hardlink_source() above) | |
824 | * - not CAP_FOWNER | |
825 | * | |
826 | * Returns 0 if successful, -ve on error. | |
827 | */ | |
828 | static int may_linkat(struct path *link) | |
829 | { | |
830 | const struct cred *cred; | |
831 | struct inode *inode; | |
832 | ||
833 | if (!sysctl_protected_hardlinks) | |
834 | return 0; | |
835 | ||
836 | cred = current_cred(); | |
837 | inode = link->dentry->d_inode; | |
838 | ||
839 | /* Source inode owner (or CAP_FOWNER) can hardlink all they like, | |
840 | * otherwise, it must be a safe source. | |
841 | */ | |
81abe27b | 842 | if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || |
800179c9 KC |
843 | capable(CAP_FOWNER)) |
844 | return 0; | |
845 | ||
a51d9eaa | 846 | audit_log_link_denied("linkat", link); |
800179c9 KC |
847 | return -EPERM; |
848 | } | |
849 | ||
def4af30 | 850 | static __always_inline int |
574197e0 | 851 | follow_link(struct path *link, struct nameidata *nd, void **p) |
1da177e4 | 852 | { |
7b9337aa | 853 | struct dentry *dentry = link->dentry; |
6d7b5aae AV |
854 | int error; |
855 | char *s; | |
1da177e4 | 856 | |
844a3917 AV |
857 | BUG_ON(nd->flags & LOOKUP_RCU); |
858 | ||
0e794589 AV |
859 | if (link->mnt == nd->path.mnt) |
860 | mntget(link->mnt); | |
861 | ||
6d7b5aae AV |
862 | error = -ELOOP; |
863 | if (unlikely(current->total_link_count >= 40)) | |
864 | goto out_put_nd_path; | |
865 | ||
574197e0 AV |
866 | cond_resched(); |
867 | current->total_link_count++; | |
868 | ||
68ac1234 | 869 | touch_atime(link); |
1da177e4 | 870 | nd_set_link(nd, NULL); |
cd4e91d3 | 871 | |
36f3b4f6 | 872 | error = security_inode_follow_link(link->dentry, nd); |
6d7b5aae AV |
873 | if (error) |
874 | goto out_put_nd_path; | |
36f3b4f6 | 875 | |
86acdca1 | 876 | nd->last_type = LAST_BIND; |
def4af30 AV |
877 | *p = dentry->d_inode->i_op->follow_link(dentry, nd); |
878 | error = PTR_ERR(*p); | |
6d7b5aae | 879 | if (IS_ERR(*p)) |
408ef013 | 880 | goto out_put_nd_path; |
6d7b5aae AV |
881 | |
882 | error = 0; | |
883 | s = nd_get_link(nd); | |
884 | if (s) { | |
443ed254 AV |
885 | if (unlikely(IS_ERR(s))) { |
886 | path_put(&nd->path); | |
887 | put_link(nd, link, *p); | |
888 | return PTR_ERR(s); | |
889 | } | |
890 | if (*s == '/') { | |
7bd88377 AV |
891 | if (!nd->root.mnt) |
892 | set_root(nd); | |
443ed254 AV |
893 | path_put(&nd->path); |
894 | nd->path = nd->root; | |
895 | path_get(&nd->root); | |
896 | nd->flags |= LOOKUP_JUMPED; | |
897 | } | |
898 | nd->inode = nd->path.dentry->d_inode; | |
899 | error = link_path_walk(s, nd); | |
b5fb63c1 CH |
900 | if (unlikely(error)) |
901 | put_link(nd, link, *p); | |
1da177e4 | 902 | } |
6d7b5aae AV |
903 | |
904 | return error; | |
905 | ||
906 | out_put_nd_path: | |
98f6ef64 | 907 | *p = NULL; |
6d7b5aae | 908 | path_put(&nd->path); |
6d7b5aae | 909 | path_put(link); |
1da177e4 LT |
910 | return error; |
911 | } | |
912 | ||
31e6b01f NP |
913 | static int follow_up_rcu(struct path *path) |
914 | { | |
0714a533 AV |
915 | struct mount *mnt = real_mount(path->mnt); |
916 | struct mount *parent; | |
31e6b01f NP |
917 | struct dentry *mountpoint; |
918 | ||
0714a533 AV |
919 | parent = mnt->mnt_parent; |
920 | if (&parent->mnt == path->mnt) | |
31e6b01f | 921 | return 0; |
a73324da | 922 | mountpoint = mnt->mnt_mountpoint; |
31e6b01f | 923 | path->dentry = mountpoint; |
0714a533 | 924 | path->mnt = &parent->mnt; |
31e6b01f NP |
925 | return 1; |
926 | } | |
927 | ||
f015f126 DH |
928 | /* |
929 | * follow_up - Find the mountpoint of path's vfsmount | |
930 | * | |
931 | * Given a path, find the mountpoint of its source file system. | |
932 | * Replace @path with the path of the mountpoint in the parent mount. | |
933 | * Up is towards /. | |
934 | * | |
935 | * Return 1 if we went up a level and 0 if we were already at the | |
936 | * root. | |
937 | */ | |
bab77ebf | 938 | int follow_up(struct path *path) |
1da177e4 | 939 | { |
0714a533 AV |
940 | struct mount *mnt = real_mount(path->mnt); |
941 | struct mount *parent; | |
1da177e4 | 942 | struct dentry *mountpoint; |
99b7db7b | 943 | |
48a066e7 | 944 | read_seqlock_excl(&mount_lock); |
0714a533 | 945 | parent = mnt->mnt_parent; |
3c0a6163 | 946 | if (parent == mnt) { |
48a066e7 | 947 | read_sequnlock_excl(&mount_lock); |
1da177e4 LT |
948 | return 0; |
949 | } | |
0714a533 | 950 | mntget(&parent->mnt); |
a73324da | 951 | mountpoint = dget(mnt->mnt_mountpoint); |
48a066e7 | 952 | read_sequnlock_excl(&mount_lock); |
bab77ebf AV |
953 | dput(path->dentry); |
954 | path->dentry = mountpoint; | |
955 | mntput(path->mnt); | |
0714a533 | 956 | path->mnt = &parent->mnt; |
1da177e4 LT |
957 | return 1; |
958 | } | |
4d359507 | 959 | EXPORT_SYMBOL(follow_up); |
1da177e4 | 960 | |
b5c84bf6 | 961 | /* |
9875cf80 DH |
962 | * Perform an automount |
963 | * - return -EISDIR to tell follow_managed() to stop and return the path we | |
964 | * were called with. | |
1da177e4 | 965 | */ |
9875cf80 DH |
966 | static int follow_automount(struct path *path, unsigned flags, |
967 | bool *need_mntput) | |
31e6b01f | 968 | { |
9875cf80 | 969 | struct vfsmount *mnt; |
ea5b778a | 970 | int err; |
9875cf80 DH |
971 | |
972 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) | |
973 | return -EREMOTE; | |
974 | ||
0ec26fd0 MS |
975 | /* We don't want to mount if someone's just doing a stat - |
976 | * unless they're stat'ing a directory and appended a '/' to | |
977 | * the name. | |
978 | * | |
979 | * We do, however, want to mount if someone wants to open or | |
980 | * create a file of any type under the mountpoint, wants to | |
981 | * traverse through the mountpoint or wants to open the | |
982 | * mounted directory. Also, autofs may mark negative dentries | |
983 | * as being automount points. These will need the attentions | |
984 | * of the daemon to instantiate them before they can be used. | |
9875cf80 | 985 | */ |
0ec26fd0 | 986 | if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
d94c177b | 987 | LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && |
0ec26fd0 MS |
988 | path->dentry->d_inode) |
989 | return -EISDIR; | |
990 | ||
9875cf80 DH |
991 | current->total_link_count++; |
992 | if (current->total_link_count >= 40) | |
993 | return -ELOOP; | |
994 | ||
995 | mnt = path->dentry->d_op->d_automount(path); | |
996 | if (IS_ERR(mnt)) { | |
997 | /* | |
998 | * The filesystem is allowed to return -EISDIR here to indicate | |
999 | * it doesn't want to automount. For instance, autofs would do | |
1000 | * this so that its userspace daemon can mount on this dentry. | |
1001 | * | |
1002 | * However, we can only permit this if it's a terminal point in | |
1003 | * the path being looked up; if it wasn't then the remainder of | |
1004 | * the path is inaccessible and we should say so. | |
1005 | */ | |
49084c3b | 1006 | if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) |
9875cf80 DH |
1007 | return -EREMOTE; |
1008 | return PTR_ERR(mnt); | |
31e6b01f | 1009 | } |
ea5b778a | 1010 | |
9875cf80 DH |
1011 | if (!mnt) /* mount collision */ |
1012 | return 0; | |
31e6b01f | 1013 | |
8aef1884 AV |
1014 | if (!*need_mntput) { |
1015 | /* lock_mount() may release path->mnt on error */ | |
1016 | mntget(path->mnt); | |
1017 | *need_mntput = true; | |
1018 | } | |
19a167af | 1019 | err = finish_automount(mnt, path); |
9875cf80 | 1020 | |
ea5b778a DH |
1021 | switch (err) { |
1022 | case -EBUSY: | |
1023 | /* Someone else made a mount here whilst we were busy */ | |
19a167af | 1024 | return 0; |
ea5b778a | 1025 | case 0: |
8aef1884 | 1026 | path_put(path); |
ea5b778a DH |
1027 | path->mnt = mnt; |
1028 | path->dentry = dget(mnt->mnt_root); | |
ea5b778a | 1029 | return 0; |
19a167af AV |
1030 | default: |
1031 | return err; | |
ea5b778a | 1032 | } |
19a167af | 1033 | |
463ffb2e AV |
1034 | } |
1035 | ||
9875cf80 DH |
1036 | /* |
1037 | * Handle a dentry that is managed in some way. | |
cc53ce53 | 1038 | * - Flagged for transit management (autofs) |
9875cf80 DH |
1039 | * - Flagged as mountpoint |
1040 | * - Flagged as automount point | |
1041 | * | |
1042 | * This may only be called in refwalk mode. | |
1043 | * | |
1044 | * Serialization is taken care of in namespace.c | |
1045 | */ | |
1046 | static int follow_managed(struct path *path, unsigned flags) | |
1da177e4 | 1047 | { |
8aef1884 | 1048 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
9875cf80 DH |
1049 | unsigned managed; |
1050 | bool need_mntput = false; | |
8aef1884 | 1051 | int ret = 0; |
9875cf80 DH |
1052 | |
1053 | /* Given that we're not holding a lock here, we retain the value in a | |
1054 | * local variable for each dentry as we look at it so that we don't see | |
1055 | * the components of that value change under us */ | |
1056 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1057 | managed &= DCACHE_MANAGED_DENTRY, | |
1058 | unlikely(managed != 0)) { | |
cc53ce53 DH |
1059 | /* Allow the filesystem to manage the transit without i_mutex |
1060 | * being held. */ | |
1061 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1062 | BUG_ON(!path->dentry->d_op); | |
1063 | BUG_ON(!path->dentry->d_op->d_manage); | |
1aed3e42 | 1064 | ret = path->dentry->d_op->d_manage(path->dentry, false); |
cc53ce53 | 1065 | if (ret < 0) |
8aef1884 | 1066 | break; |
cc53ce53 DH |
1067 | } |
1068 | ||
9875cf80 DH |
1069 | /* Transit to a mounted filesystem. */ |
1070 | if (managed & DCACHE_MOUNTED) { | |
1071 | struct vfsmount *mounted = lookup_mnt(path); | |
1072 | if (mounted) { | |
1073 | dput(path->dentry); | |
1074 | if (need_mntput) | |
1075 | mntput(path->mnt); | |
1076 | path->mnt = mounted; | |
1077 | path->dentry = dget(mounted->mnt_root); | |
1078 | need_mntput = true; | |
1079 | continue; | |
1080 | } | |
1081 | ||
1082 | /* Something is mounted on this dentry in another | |
1083 | * namespace and/or whatever was mounted there in this | |
48a066e7 AV |
1084 | * namespace got unmounted before lookup_mnt() could |
1085 | * get it */ | |
9875cf80 DH |
1086 | } |
1087 | ||
1088 | /* Handle an automount point */ | |
1089 | if (managed & DCACHE_NEED_AUTOMOUNT) { | |
1090 | ret = follow_automount(path, flags, &need_mntput); | |
1091 | if (ret < 0) | |
8aef1884 | 1092 | break; |
9875cf80 DH |
1093 | continue; |
1094 | } | |
1095 | ||
1096 | /* We didn't change the current path point */ | |
1097 | break; | |
1da177e4 | 1098 | } |
8aef1884 AV |
1099 | |
1100 | if (need_mntput && path->mnt == mnt) | |
1101 | mntput(path->mnt); | |
1102 | if (ret == -EISDIR) | |
1103 | ret = 0; | |
a3fbbde7 | 1104 | return ret < 0 ? ret : need_mntput; |
1da177e4 LT |
1105 | } |
1106 | ||
cc53ce53 | 1107 | int follow_down_one(struct path *path) |
1da177e4 LT |
1108 | { |
1109 | struct vfsmount *mounted; | |
1110 | ||
1c755af4 | 1111 | mounted = lookup_mnt(path); |
1da177e4 | 1112 | if (mounted) { |
9393bd07 AV |
1113 | dput(path->dentry); |
1114 | mntput(path->mnt); | |
1115 | path->mnt = mounted; | |
1116 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
1117 | return 1; |
1118 | } | |
1119 | return 0; | |
1120 | } | |
4d359507 | 1121 | EXPORT_SYMBOL(follow_down_one); |
1da177e4 | 1122 | |
b8faf035 | 1123 | static inline int managed_dentry_rcu(struct dentry *dentry) |
62a7375e | 1124 | { |
b8faf035 N |
1125 | return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? |
1126 | dentry->d_op->d_manage(dentry, true) : 0; | |
62a7375e IK |
1127 | } |
1128 | ||
9875cf80 | 1129 | /* |
287548e4 AV |
1130 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
1131 | * we meet a managed dentry that would need blocking. | |
9875cf80 DH |
1132 | */ |
1133 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, | |
287548e4 | 1134 | struct inode **inode) |
9875cf80 | 1135 | { |
62a7375e | 1136 | for (;;) { |
c7105365 | 1137 | struct mount *mounted; |
62a7375e IK |
1138 | /* |
1139 | * Don't forget we might have a non-mountpoint managed dentry | |
1140 | * that wants to block transit. | |
1141 | */ | |
b8faf035 N |
1142 | switch (managed_dentry_rcu(path->dentry)) { |
1143 | case -ECHILD: | |
1144 | default: | |
ab90911f | 1145 | return false; |
b8faf035 N |
1146 | case -EISDIR: |
1147 | return true; | |
1148 | case 0: | |
1149 | break; | |
1150 | } | |
62a7375e IK |
1151 | |
1152 | if (!d_mountpoint(path->dentry)) | |
b8faf035 | 1153 | return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); |
62a7375e | 1154 | |
474279dc | 1155 | mounted = __lookup_mnt(path->mnt, path->dentry); |
9875cf80 DH |
1156 | if (!mounted) |
1157 | break; | |
c7105365 AV |
1158 | path->mnt = &mounted->mnt; |
1159 | path->dentry = mounted->mnt.mnt_root; | |
a3fbbde7 | 1160 | nd->flags |= LOOKUP_JUMPED; |
9875cf80 | 1161 | nd->seq = read_seqcount_begin(&path->dentry->d_seq); |
59430262 LT |
1162 | /* |
1163 | * Update the inode too. We don't need to re-check the | |
1164 | * dentry sequence number here after this d_inode read, | |
1165 | * because a mount-point is always pinned. | |
1166 | */ | |
1167 | *inode = path->dentry->d_inode; | |
9875cf80 | 1168 | } |
f5be3e29 | 1169 | return !read_seqretry(&mount_lock, nd->m_seq) && |
b8faf035 | 1170 | !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); |
287548e4 AV |
1171 | } |
1172 | ||
31e6b01f NP |
1173 | static int follow_dotdot_rcu(struct nameidata *nd) |
1174 | { | |
4023bfc9 | 1175 | struct inode *inode = nd->inode; |
7bd88377 AV |
1176 | if (!nd->root.mnt) |
1177 | set_root_rcu(nd); | |
31e6b01f | 1178 | |
9875cf80 | 1179 | while (1) { |
31e6b01f NP |
1180 | if (nd->path.dentry == nd->root.dentry && |
1181 | nd->path.mnt == nd->root.mnt) { | |
1182 | break; | |
1183 | } | |
1184 | if (nd->path.dentry != nd->path.mnt->mnt_root) { | |
1185 | struct dentry *old = nd->path.dentry; | |
1186 | struct dentry *parent = old->d_parent; | |
1187 | unsigned seq; | |
1188 | ||
4023bfc9 | 1189 | inode = parent->d_inode; |
31e6b01f NP |
1190 | seq = read_seqcount_begin(&parent->d_seq); |
1191 | if (read_seqcount_retry(&old->d_seq, nd->seq)) | |
ef7562d5 | 1192 | goto failed; |
31e6b01f NP |
1193 | nd->path.dentry = parent; |
1194 | nd->seq = seq; | |
1195 | break; | |
1196 | } | |
1197 | if (!follow_up_rcu(&nd->path)) | |
1198 | break; | |
4023bfc9 | 1199 | inode = nd->path.dentry->d_inode; |
31e6b01f | 1200 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); |
31e6b01f | 1201 | } |
b37199e6 AV |
1202 | while (d_mountpoint(nd->path.dentry)) { |
1203 | struct mount *mounted; | |
1204 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); | |
1205 | if (!mounted) | |
1206 | break; | |
1207 | nd->path.mnt = &mounted->mnt; | |
1208 | nd->path.dentry = mounted->mnt.mnt_root; | |
4023bfc9 | 1209 | inode = nd->path.dentry->d_inode; |
b37199e6 | 1210 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); |
f5be3e29 | 1211 | if (read_seqretry(&mount_lock, nd->m_seq)) |
b37199e6 AV |
1212 | goto failed; |
1213 | } | |
4023bfc9 | 1214 | nd->inode = inode; |
31e6b01f | 1215 | return 0; |
ef7562d5 AV |
1216 | |
1217 | failed: | |
1218 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1219 | if (!(nd->flags & LOOKUP_ROOT)) |
1220 | nd->root.mnt = NULL; | |
8b61e74f | 1221 | rcu_read_unlock(); |
ef7562d5 | 1222 | return -ECHILD; |
31e6b01f NP |
1223 | } |
1224 | ||
cc53ce53 DH |
1225 | /* |
1226 | * Follow down to the covering mount currently visible to userspace. At each | |
1227 | * point, the filesystem owning that dentry may be queried as to whether the | |
1228 | * caller is permitted to proceed or not. | |
cc53ce53 | 1229 | */ |
7cc90cc3 | 1230 | int follow_down(struct path *path) |
cc53ce53 DH |
1231 | { |
1232 | unsigned managed; | |
1233 | int ret; | |
1234 | ||
1235 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1236 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { | |
1237 | /* Allow the filesystem to manage the transit without i_mutex | |
1238 | * being held. | |
1239 | * | |
1240 | * We indicate to the filesystem if someone is trying to mount | |
1241 | * something here. This gives autofs the chance to deny anyone | |
1242 | * other than its daemon the right to mount on its | |
1243 | * superstructure. | |
1244 | * | |
1245 | * The filesystem may sleep at this point. | |
1246 | */ | |
1247 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1248 | BUG_ON(!path->dentry->d_op); | |
1249 | BUG_ON(!path->dentry->d_op->d_manage); | |
ab90911f | 1250 | ret = path->dentry->d_op->d_manage( |
1aed3e42 | 1251 | path->dentry, false); |
cc53ce53 DH |
1252 | if (ret < 0) |
1253 | return ret == -EISDIR ? 0 : ret; | |
1254 | } | |
1255 | ||
1256 | /* Transit to a mounted filesystem. */ | |
1257 | if (managed & DCACHE_MOUNTED) { | |
1258 | struct vfsmount *mounted = lookup_mnt(path); | |
1259 | if (!mounted) | |
1260 | break; | |
1261 | dput(path->dentry); | |
1262 | mntput(path->mnt); | |
1263 | path->mnt = mounted; | |
1264 | path->dentry = dget(mounted->mnt_root); | |
1265 | continue; | |
1266 | } | |
1267 | ||
1268 | /* Don't handle automount points here */ | |
1269 | break; | |
1270 | } | |
1271 | return 0; | |
1272 | } | |
4d359507 | 1273 | EXPORT_SYMBOL(follow_down); |
cc53ce53 | 1274 | |
9875cf80 DH |
1275 | /* |
1276 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() | |
1277 | */ | |
1278 | static void follow_mount(struct path *path) | |
1279 | { | |
1280 | while (d_mountpoint(path->dentry)) { | |
1281 | struct vfsmount *mounted = lookup_mnt(path); | |
1282 | if (!mounted) | |
1283 | break; | |
1284 | dput(path->dentry); | |
1285 | mntput(path->mnt); | |
1286 | path->mnt = mounted; | |
1287 | path->dentry = dget(mounted->mnt_root); | |
1288 | } | |
1289 | } | |
1290 | ||
31e6b01f | 1291 | static void follow_dotdot(struct nameidata *nd) |
1da177e4 | 1292 | { |
7bd88377 AV |
1293 | if (!nd->root.mnt) |
1294 | set_root(nd); | |
e518ddb7 | 1295 | |
1da177e4 | 1296 | while(1) { |
4ac91378 | 1297 | struct dentry *old = nd->path.dentry; |
1da177e4 | 1298 | |
2a737871 AV |
1299 | if (nd->path.dentry == nd->root.dentry && |
1300 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
1301 | break; |
1302 | } | |
4ac91378 | 1303 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
3088dd70 AV |
1304 | /* rare case of legitimate dget_parent()... */ |
1305 | nd->path.dentry = dget_parent(nd->path.dentry); | |
1da177e4 LT |
1306 | dput(old); |
1307 | break; | |
1308 | } | |
3088dd70 | 1309 | if (!follow_up(&nd->path)) |
1da177e4 | 1310 | break; |
1da177e4 | 1311 | } |
79ed0226 | 1312 | follow_mount(&nd->path); |
31e6b01f | 1313 | nd->inode = nd->path.dentry->d_inode; |
1da177e4 LT |
1314 | } |
1315 | ||
baa03890 | 1316 | /* |
bad61189 MS |
1317 | * This looks up the name in dcache, possibly revalidates the old dentry and |
1318 | * allocates a new one if not found or not valid. In the need_lookup argument | |
1319 | * returns whether i_op->lookup is necessary. | |
1320 | * | |
1321 | * dir->d_inode->i_mutex must be held | |
baa03890 | 1322 | */ |
bad61189 | 1323 | static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, |
201f956e | 1324 | unsigned int flags, bool *need_lookup) |
baa03890 | 1325 | { |
baa03890 | 1326 | struct dentry *dentry; |
bad61189 | 1327 | int error; |
baa03890 | 1328 | |
bad61189 MS |
1329 | *need_lookup = false; |
1330 | dentry = d_lookup(dir, name); | |
1331 | if (dentry) { | |
39e3c955 | 1332 | if (dentry->d_flags & DCACHE_OP_REVALIDATE) { |
201f956e | 1333 | error = d_revalidate(dentry, flags); |
bad61189 MS |
1334 | if (unlikely(error <= 0)) { |
1335 | if (error < 0) { | |
1336 | dput(dentry); | |
1337 | return ERR_PTR(error); | |
5542aa2f EB |
1338 | } else { |
1339 | d_invalidate(dentry); | |
bad61189 MS |
1340 | dput(dentry); |
1341 | dentry = NULL; | |
1342 | } | |
1343 | } | |
1344 | } | |
1345 | } | |
baa03890 | 1346 | |
bad61189 MS |
1347 | if (!dentry) { |
1348 | dentry = d_alloc(dir, name); | |
1349 | if (unlikely(!dentry)) | |
1350 | return ERR_PTR(-ENOMEM); | |
baa03890 | 1351 | |
bad61189 | 1352 | *need_lookup = true; |
baa03890 NP |
1353 | } |
1354 | return dentry; | |
1355 | } | |
1356 | ||
44396f4b | 1357 | /* |
13a2c3be BF |
1358 | * Call i_op->lookup on the dentry. The dentry must be negative and |
1359 | * unhashed. | |
bad61189 MS |
1360 | * |
1361 | * dir->d_inode->i_mutex must be held | |
44396f4b | 1362 | */ |
bad61189 | 1363 | static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, |
72bd866a | 1364 | unsigned int flags) |
44396f4b | 1365 | { |
44396f4b JB |
1366 | struct dentry *old; |
1367 | ||
1368 | /* Don't create child dentry for a dead directory. */ | |
bad61189 | 1369 | if (unlikely(IS_DEADDIR(dir))) { |
e188dc02 | 1370 | dput(dentry); |
44396f4b | 1371 | return ERR_PTR(-ENOENT); |
e188dc02 | 1372 | } |
44396f4b | 1373 | |
72bd866a | 1374 | old = dir->i_op->lookup(dir, dentry, flags); |
44396f4b JB |
1375 | if (unlikely(old)) { |
1376 | dput(dentry); | |
1377 | dentry = old; | |
1378 | } | |
1379 | return dentry; | |
1380 | } | |
1381 | ||
a3255546 | 1382 | static struct dentry *__lookup_hash(struct qstr *name, |
72bd866a | 1383 | struct dentry *base, unsigned int flags) |
a3255546 | 1384 | { |
bad61189 | 1385 | bool need_lookup; |
a3255546 AV |
1386 | struct dentry *dentry; |
1387 | ||
72bd866a | 1388 | dentry = lookup_dcache(name, base, flags, &need_lookup); |
bad61189 MS |
1389 | if (!need_lookup) |
1390 | return dentry; | |
a3255546 | 1391 | |
72bd866a | 1392 | return lookup_real(base->d_inode, dentry, flags); |
a3255546 AV |
1393 | } |
1394 | ||
1da177e4 LT |
1395 | /* |
1396 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
1397 | * small and for now I'd prefer to have fast path as straight as possible. | |
1398 | * It _is_ time-critical. | |
1399 | */ | |
e97cdc87 | 1400 | static int lookup_fast(struct nameidata *nd, |
697f514d | 1401 | struct path *path, struct inode **inode) |
1da177e4 | 1402 | { |
4ac91378 | 1403 | struct vfsmount *mnt = nd->path.mnt; |
31e6b01f | 1404 | struct dentry *dentry, *parent = nd->path.dentry; |
5a18fff2 AV |
1405 | int need_reval = 1; |
1406 | int status = 1; | |
9875cf80 DH |
1407 | int err; |
1408 | ||
b04f784e NP |
1409 | /* |
1410 | * Rename seqlock is not required here because in the off chance | |
1411 | * of a false negative due to a concurrent rename, we're going to | |
1412 | * do the non-racy lookup, below. | |
1413 | */ | |
31e6b01f NP |
1414 | if (nd->flags & LOOKUP_RCU) { |
1415 | unsigned seq; | |
da53be12 | 1416 | dentry = __d_lookup_rcu(parent, &nd->last, &seq); |
5a18fff2 AV |
1417 | if (!dentry) |
1418 | goto unlazy; | |
1419 | ||
12f8ad4b LT |
1420 | /* |
1421 | * This sequence count validates that the inode matches | |
1422 | * the dentry name information from lookup. | |
1423 | */ | |
1424 | *inode = dentry->d_inode; | |
1425 | if (read_seqcount_retry(&dentry->d_seq, seq)) | |
1426 | return -ECHILD; | |
1427 | ||
1428 | /* | |
1429 | * This sequence count validates that the parent had no | |
1430 | * changes while we did the lookup of the dentry above. | |
1431 | * | |
1432 | * The memory barrier in read_seqcount_begin of child is | |
1433 | * enough, we can use __read_seqcount_retry here. | |
1434 | */ | |
31e6b01f NP |
1435 | if (__read_seqcount_retry(&parent->d_seq, nd->seq)) |
1436 | return -ECHILD; | |
31e6b01f | 1437 | nd->seq = seq; |
5a18fff2 | 1438 | |
24643087 | 1439 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
4ce16ef3 | 1440 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1441 | if (unlikely(status <= 0)) { |
1442 | if (status != -ECHILD) | |
1443 | need_reval = 0; | |
1444 | goto unlazy; | |
1445 | } | |
24643087 | 1446 | } |
31e6b01f NP |
1447 | path->mnt = mnt; |
1448 | path->dentry = dentry; | |
b8faf035 N |
1449 | if (likely(__follow_mount_rcu(nd, path, inode))) |
1450 | return 0; | |
5a18fff2 | 1451 | unlazy: |
19660af7 AV |
1452 | if (unlazy_walk(nd, dentry)) |
1453 | return -ECHILD; | |
5a18fff2 | 1454 | } else { |
e97cdc87 | 1455 | dentry = __d_lookup(parent, &nd->last); |
9875cf80 | 1456 | } |
5a18fff2 | 1457 | |
81e6f520 AV |
1458 | if (unlikely(!dentry)) |
1459 | goto need_lookup; | |
1460 | ||
5a18fff2 | 1461 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) |
4ce16ef3 | 1462 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1463 | if (unlikely(status <= 0)) { |
1464 | if (status < 0) { | |
1465 | dput(dentry); | |
1466 | return status; | |
1467 | } | |
5542aa2f EB |
1468 | d_invalidate(dentry); |
1469 | dput(dentry); | |
1470 | goto need_lookup; | |
24643087 | 1471 | } |
697f514d | 1472 | |
9875cf80 DH |
1473 | path->mnt = mnt; |
1474 | path->dentry = dentry; | |
1475 | err = follow_managed(path, nd->flags); | |
89312214 IK |
1476 | if (unlikely(err < 0)) { |
1477 | path_put_conditional(path, nd); | |
9875cf80 | 1478 | return err; |
89312214 | 1479 | } |
a3fbbde7 AV |
1480 | if (err) |
1481 | nd->flags |= LOOKUP_JUMPED; | |
9875cf80 | 1482 | *inode = path->dentry->d_inode; |
1da177e4 | 1483 | return 0; |
81e6f520 AV |
1484 | |
1485 | need_lookup: | |
697f514d MS |
1486 | return 1; |
1487 | } | |
1488 | ||
1489 | /* Fast lookup failed, do it the slow way */ | |
cc2a5271 | 1490 | static int lookup_slow(struct nameidata *nd, struct path *path) |
697f514d MS |
1491 | { |
1492 | struct dentry *dentry, *parent; | |
1493 | int err; | |
1494 | ||
1495 | parent = nd->path.dentry; | |
81e6f520 AV |
1496 | BUG_ON(nd->inode != parent->d_inode); |
1497 | ||
1498 | mutex_lock(&parent->d_inode->i_mutex); | |
cc2a5271 | 1499 | dentry = __lookup_hash(&nd->last, parent, nd->flags); |
81e6f520 AV |
1500 | mutex_unlock(&parent->d_inode->i_mutex); |
1501 | if (IS_ERR(dentry)) | |
1502 | return PTR_ERR(dentry); | |
697f514d MS |
1503 | path->mnt = nd->path.mnt; |
1504 | path->dentry = dentry; | |
1505 | err = follow_managed(path, nd->flags); | |
1506 | if (unlikely(err < 0)) { | |
1507 | path_put_conditional(path, nd); | |
1508 | return err; | |
1509 | } | |
1510 | if (err) | |
1511 | nd->flags |= LOOKUP_JUMPED; | |
1512 | return 0; | |
1da177e4 LT |
1513 | } |
1514 | ||
52094c8a AV |
1515 | static inline int may_lookup(struct nameidata *nd) |
1516 | { | |
1517 | if (nd->flags & LOOKUP_RCU) { | |
4ad5abb3 | 1518 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
52094c8a AV |
1519 | if (err != -ECHILD) |
1520 | return err; | |
19660af7 | 1521 | if (unlazy_walk(nd, NULL)) |
52094c8a AV |
1522 | return -ECHILD; |
1523 | } | |
4ad5abb3 | 1524 | return inode_permission(nd->inode, MAY_EXEC); |
52094c8a AV |
1525 | } |
1526 | ||
9856fa1b AV |
1527 | static inline int handle_dots(struct nameidata *nd, int type) |
1528 | { | |
1529 | if (type == LAST_DOTDOT) { | |
1530 | if (nd->flags & LOOKUP_RCU) { | |
1531 | if (follow_dotdot_rcu(nd)) | |
1532 | return -ECHILD; | |
1533 | } else | |
1534 | follow_dotdot(nd); | |
1535 | } | |
1536 | return 0; | |
1537 | } | |
1538 | ||
951361f9 AV |
1539 | static void terminate_walk(struct nameidata *nd) |
1540 | { | |
1541 | if (!(nd->flags & LOOKUP_RCU)) { | |
1542 | path_put(&nd->path); | |
1543 | } else { | |
1544 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1545 | if (!(nd->flags & LOOKUP_ROOT)) |
1546 | nd->root.mnt = NULL; | |
8b61e74f | 1547 | rcu_read_unlock(); |
951361f9 AV |
1548 | } |
1549 | } | |
1550 | ||
3ddcd056 LT |
1551 | /* |
1552 | * Do we need to follow links? We _really_ want to be able | |
1553 | * to do this check without having to look at inode->i_op, | |
1554 | * so we keep a cache of "no, this doesn't need follow_link" | |
1555 | * for the common case. | |
1556 | */ | |
b18825a7 | 1557 | static inline int should_follow_link(struct dentry *dentry, int follow) |
3ddcd056 | 1558 | { |
b18825a7 | 1559 | return unlikely(d_is_symlink(dentry)) ? follow : 0; |
3ddcd056 LT |
1560 | } |
1561 | ||
ce57dfc1 | 1562 | static inline int walk_component(struct nameidata *nd, struct path *path, |
21b9b073 | 1563 | int follow) |
ce57dfc1 AV |
1564 | { |
1565 | struct inode *inode; | |
1566 | int err; | |
1567 | /* | |
1568 | * "." and ".." are special - ".." especially so because it has | |
1569 | * to be able to know about the current root directory and | |
1570 | * parent relationships. | |
1571 | */ | |
21b9b073 AV |
1572 | if (unlikely(nd->last_type != LAST_NORM)) |
1573 | return handle_dots(nd, nd->last_type); | |
e97cdc87 | 1574 | err = lookup_fast(nd, path, &inode); |
ce57dfc1 | 1575 | if (unlikely(err)) { |
697f514d MS |
1576 | if (err < 0) |
1577 | goto out_err; | |
1578 | ||
cc2a5271 | 1579 | err = lookup_slow(nd, path); |
697f514d MS |
1580 | if (err < 0) |
1581 | goto out_err; | |
1582 | ||
1583 | inode = path->dentry->d_inode; | |
ce57dfc1 | 1584 | } |
697f514d | 1585 | err = -ENOENT; |
22213318 | 1586 | if (!inode || d_is_negative(path->dentry)) |
697f514d MS |
1587 | goto out_path_put; |
1588 | ||
b18825a7 | 1589 | if (should_follow_link(path->dentry, follow)) { |
19660af7 AV |
1590 | if (nd->flags & LOOKUP_RCU) { |
1591 | if (unlikely(unlazy_walk(nd, path->dentry))) { | |
697f514d MS |
1592 | err = -ECHILD; |
1593 | goto out_err; | |
19660af7 AV |
1594 | } |
1595 | } | |
ce57dfc1 AV |
1596 | BUG_ON(inode != path->dentry->d_inode); |
1597 | return 1; | |
1598 | } | |
1599 | path_to_nameidata(path, nd); | |
1600 | nd->inode = inode; | |
1601 | return 0; | |
697f514d MS |
1602 | |
1603 | out_path_put: | |
1604 | path_to_nameidata(path, nd); | |
1605 | out_err: | |
1606 | terminate_walk(nd); | |
1607 | return err; | |
ce57dfc1 AV |
1608 | } |
1609 | ||
b356379a AV |
1610 | /* |
1611 | * This limits recursive symlink follows to 8, while | |
1612 | * limiting consecutive symlinks to 40. | |
1613 | * | |
1614 | * Without that kind of total limit, nasty chains of consecutive | |
1615 | * symlinks can cause almost arbitrarily long lookups. | |
1616 | */ | |
1617 | static inline int nested_symlink(struct path *path, struct nameidata *nd) | |
1618 | { | |
1619 | int res; | |
1620 | ||
b356379a AV |
1621 | if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { |
1622 | path_put_conditional(path, nd); | |
1623 | path_put(&nd->path); | |
1624 | return -ELOOP; | |
1625 | } | |
1a4022f8 | 1626 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); |
b356379a AV |
1627 | |
1628 | nd->depth++; | |
1629 | current->link_count++; | |
1630 | ||
1631 | do { | |
1632 | struct path link = *path; | |
1633 | void *cookie; | |
574197e0 AV |
1634 | |
1635 | res = follow_link(&link, nd, &cookie); | |
6d7b5aae AV |
1636 | if (res) |
1637 | break; | |
21b9b073 | 1638 | res = walk_component(nd, path, LOOKUP_FOLLOW); |
574197e0 | 1639 | put_link(nd, &link, cookie); |
b356379a AV |
1640 | } while (res > 0); |
1641 | ||
1642 | current->link_count--; | |
1643 | nd->depth--; | |
1644 | return res; | |
1645 | } | |
1646 | ||
bfcfaa77 LT |
1647 | /* |
1648 | * We can do the critical dentry name comparison and hashing | |
1649 | * operations one word at a time, but we are limited to: | |
1650 | * | |
1651 | * - Architectures with fast unaligned word accesses. We could | |
1652 | * do a "get_unaligned()" if this helps and is sufficiently | |
1653 | * fast. | |
1654 | * | |
bfcfaa77 LT |
1655 | * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we |
1656 | * do not trap on the (extremely unlikely) case of a page | |
1657 | * crossing operation. | |
1658 | * | |
1659 | * - Furthermore, we need an efficient 64-bit compile for the | |
1660 | * 64-bit case in order to generate the "number of bytes in | |
1661 | * the final mask". Again, that could be replaced with a | |
1662 | * efficient population count instruction or similar. | |
1663 | */ | |
1664 | #ifdef CONFIG_DCACHE_WORD_ACCESS | |
1665 | ||
f68e556e | 1666 | #include <asm/word-at-a-time.h> |
bfcfaa77 | 1667 | |
f68e556e | 1668 | #ifdef CONFIG_64BIT |
bfcfaa77 LT |
1669 | |
1670 | static inline unsigned int fold_hash(unsigned long hash) | |
1671 | { | |
99d263d4 | 1672 | return hash_64(hash, 32); |
bfcfaa77 LT |
1673 | } |
1674 | ||
1675 | #else /* 32-bit case */ | |
1676 | ||
bfcfaa77 LT |
1677 | #define fold_hash(x) (x) |
1678 | ||
1679 | #endif | |
1680 | ||
1681 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) | |
1682 | { | |
1683 | unsigned long a, mask; | |
1684 | unsigned long hash = 0; | |
1685 | ||
1686 | for (;;) { | |
e419b4cc | 1687 | a = load_unaligned_zeropad(name); |
bfcfaa77 LT |
1688 | if (len < sizeof(unsigned long)) |
1689 | break; | |
1690 | hash += a; | |
f132c5be | 1691 | hash *= 9; |
bfcfaa77 LT |
1692 | name += sizeof(unsigned long); |
1693 | len -= sizeof(unsigned long); | |
1694 | if (!len) | |
1695 | goto done; | |
1696 | } | |
a5c21dce | 1697 | mask = bytemask_from_count(len); |
bfcfaa77 LT |
1698 | hash += mask & a; |
1699 | done: | |
1700 | return fold_hash(hash); | |
1701 | } | |
1702 | EXPORT_SYMBOL(full_name_hash); | |
1703 | ||
bfcfaa77 LT |
1704 | /* |
1705 | * Calculate the length and hash of the path component, and | |
d6bb3e90 | 1706 | * return the "hash_len" as the result. |
bfcfaa77 | 1707 | */ |
d6bb3e90 | 1708 | static inline u64 hash_name(const char *name) |
bfcfaa77 | 1709 | { |
36126f8f LT |
1710 | unsigned long a, b, adata, bdata, mask, hash, len; |
1711 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; | |
bfcfaa77 LT |
1712 | |
1713 | hash = a = 0; | |
1714 | len = -sizeof(unsigned long); | |
1715 | do { | |
1716 | hash = (hash + a) * 9; | |
1717 | len += sizeof(unsigned long); | |
e419b4cc | 1718 | a = load_unaligned_zeropad(name+len); |
36126f8f LT |
1719 | b = a ^ REPEAT_BYTE('/'); |
1720 | } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); | |
1721 | ||
1722 | adata = prep_zero_mask(a, adata, &constants); | |
1723 | bdata = prep_zero_mask(b, bdata, &constants); | |
1724 | ||
1725 | mask = create_zero_mask(adata | bdata); | |
1726 | ||
1727 | hash += a & zero_bytemask(mask); | |
9226b5b4 | 1728 | len += find_zero(mask); |
d6bb3e90 | 1729 | return hashlen_create(fold_hash(hash), len); |
bfcfaa77 LT |
1730 | } |
1731 | ||
1732 | #else | |
1733 | ||
0145acc2 LT |
1734 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) |
1735 | { | |
1736 | unsigned long hash = init_name_hash(); | |
1737 | while (len--) | |
1738 | hash = partial_name_hash(*name++, hash); | |
1739 | return end_name_hash(hash); | |
1740 | } | |
ae942ae7 | 1741 | EXPORT_SYMBOL(full_name_hash); |
0145acc2 | 1742 | |
200e9ef7 LT |
1743 | /* |
1744 | * We know there's a real path component here of at least | |
1745 | * one character. | |
1746 | */ | |
d6bb3e90 | 1747 | static inline u64 hash_name(const char *name) |
200e9ef7 LT |
1748 | { |
1749 | unsigned long hash = init_name_hash(); | |
1750 | unsigned long len = 0, c; | |
1751 | ||
1752 | c = (unsigned char)*name; | |
1753 | do { | |
1754 | len++; | |
1755 | hash = partial_name_hash(c, hash); | |
1756 | c = (unsigned char)name[len]; | |
1757 | } while (c && c != '/'); | |
d6bb3e90 | 1758 | return hashlen_create(end_name_hash(hash), len); |
200e9ef7 LT |
1759 | } |
1760 | ||
bfcfaa77 LT |
1761 | #endif |
1762 | ||
1da177e4 LT |
1763 | /* |
1764 | * Name resolution. | |
ea3834d9 PM |
1765 | * This is the basic name resolution function, turning a pathname into |
1766 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 1767 | * |
ea3834d9 PM |
1768 | * Returns 0 and nd will have valid dentry and mnt on success. |
1769 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 1770 | */ |
6de88d72 | 1771 | static int link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 LT |
1772 | { |
1773 | struct path next; | |
1da177e4 | 1774 | int err; |
1da177e4 LT |
1775 | |
1776 | while (*name=='/') | |
1777 | name++; | |
1778 | if (!*name) | |
086e183a | 1779 | return 0; |
1da177e4 | 1780 | |
1da177e4 LT |
1781 | /* At this point we know we have a real path component. */ |
1782 | for(;;) { | |
d6bb3e90 | 1783 | u64 hash_len; |
fe479a58 | 1784 | int type; |
1da177e4 | 1785 | |
52094c8a | 1786 | err = may_lookup(nd); |
1da177e4 LT |
1787 | if (err) |
1788 | break; | |
1789 | ||
d6bb3e90 | 1790 | hash_len = hash_name(name); |
1da177e4 | 1791 | |
fe479a58 | 1792 | type = LAST_NORM; |
d6bb3e90 | 1793 | if (name[0] == '.') switch (hashlen_len(hash_len)) { |
fe479a58 | 1794 | case 2: |
200e9ef7 | 1795 | if (name[1] == '.') { |
fe479a58 | 1796 | type = LAST_DOTDOT; |
16c2cd71 AV |
1797 | nd->flags |= LOOKUP_JUMPED; |
1798 | } | |
fe479a58 AV |
1799 | break; |
1800 | case 1: | |
1801 | type = LAST_DOT; | |
1802 | } | |
5a202bcd AV |
1803 | if (likely(type == LAST_NORM)) { |
1804 | struct dentry *parent = nd->path.dentry; | |
16c2cd71 | 1805 | nd->flags &= ~LOOKUP_JUMPED; |
5a202bcd | 1806 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
a060dc50 | 1807 | struct qstr this = { { .hash_len = hash_len }, .name = name }; |
da53be12 | 1808 | err = parent->d_op->d_hash(parent, &this); |
5a202bcd AV |
1809 | if (err < 0) |
1810 | break; | |
d6bb3e90 LT |
1811 | hash_len = this.hash_len; |
1812 | name = this.name; | |
5a202bcd AV |
1813 | } |
1814 | } | |
fe479a58 | 1815 | |
d6bb3e90 LT |
1816 | nd->last.hash_len = hash_len; |
1817 | nd->last.name = name; | |
5f4a6a69 AV |
1818 | nd->last_type = type; |
1819 | ||
d6bb3e90 LT |
1820 | name += hashlen_len(hash_len); |
1821 | if (!*name) | |
5f4a6a69 | 1822 | return 0; |
200e9ef7 LT |
1823 | /* |
1824 | * If it wasn't NUL, we know it was '/'. Skip that | |
1825 | * slash, and continue until no more slashes. | |
1826 | */ | |
1827 | do { | |
d6bb3e90 LT |
1828 | name++; |
1829 | } while (unlikely(*name == '/')); | |
1830 | if (!*name) | |
5f4a6a69 AV |
1831 | return 0; |
1832 | ||
21b9b073 | 1833 | err = walk_component(nd, &next, LOOKUP_FOLLOW); |
ce57dfc1 AV |
1834 | if (err < 0) |
1835 | return err; | |
1da177e4 | 1836 | |
ce57dfc1 | 1837 | if (err) { |
b356379a | 1838 | err = nested_symlink(&next, nd); |
1da177e4 | 1839 | if (err) |
a7472bab | 1840 | return err; |
31e6b01f | 1841 | } |
44b1d530 | 1842 | if (!d_can_lookup(nd->path.dentry)) { |
5f4a6a69 AV |
1843 | err = -ENOTDIR; |
1844 | break; | |
1845 | } | |
1da177e4 | 1846 | } |
951361f9 | 1847 | terminate_walk(nd); |
1da177e4 LT |
1848 | return err; |
1849 | } | |
1850 | ||
6e8a1f87 | 1851 | static int path_init(int dfd, const struct filename *name, unsigned int flags, |
5e53084d | 1852 | struct nameidata *nd) |
31e6b01f NP |
1853 | { |
1854 | int retval = 0; | |
31e6b01f NP |
1855 | |
1856 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
980f3ea2 | 1857 | nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; |
31e6b01f | 1858 | nd->depth = 0; |
5e53084d | 1859 | nd->base = NULL; |
5b6ca027 | 1860 | if (flags & LOOKUP_ROOT) { |
b18825a7 DH |
1861 | struct dentry *root = nd->root.dentry; |
1862 | struct inode *inode = root->d_inode; | |
6e8a1f87 | 1863 | if (name->name[0]) { |
44b1d530 | 1864 | if (!d_can_lookup(root)) |
73d049a4 AV |
1865 | return -ENOTDIR; |
1866 | retval = inode_permission(inode, MAY_EXEC); | |
1867 | if (retval) | |
1868 | return retval; | |
1869 | } | |
5b6ca027 AV |
1870 | nd->path = nd->root; |
1871 | nd->inode = inode; | |
1872 | if (flags & LOOKUP_RCU) { | |
8b61e74f | 1873 | rcu_read_lock(); |
5b6ca027 | 1874 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
48a066e7 | 1875 | nd->m_seq = read_seqbegin(&mount_lock); |
5b6ca027 AV |
1876 | } else { |
1877 | path_get(&nd->path); | |
1878 | } | |
d465887f | 1879 | goto done; |
5b6ca027 AV |
1880 | } |
1881 | ||
31e6b01f | 1882 | nd->root.mnt = NULL; |
31e6b01f | 1883 | |
48a066e7 | 1884 | nd->m_seq = read_seqbegin(&mount_lock); |
6e8a1f87 | 1885 | if (name->name[0] == '/') { |
e41f7d4e | 1886 | if (flags & LOOKUP_RCU) { |
8b61e74f | 1887 | rcu_read_lock(); |
7bd88377 | 1888 | nd->seq = set_root_rcu(nd); |
e41f7d4e AV |
1889 | } else { |
1890 | set_root(nd); | |
1891 | path_get(&nd->root); | |
1892 | } | |
1893 | nd->path = nd->root; | |
31e6b01f | 1894 | } else if (dfd == AT_FDCWD) { |
e41f7d4e AV |
1895 | if (flags & LOOKUP_RCU) { |
1896 | struct fs_struct *fs = current->fs; | |
1897 | unsigned seq; | |
31e6b01f | 1898 | |
8b61e74f | 1899 | rcu_read_lock(); |
c28cc364 | 1900 | |
e41f7d4e AV |
1901 | do { |
1902 | seq = read_seqcount_begin(&fs->seq); | |
1903 | nd->path = fs->pwd; | |
1904 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
1905 | } while (read_seqcount_retry(&fs->seq, seq)); | |
1906 | } else { | |
1907 | get_fs_pwd(current->fs, &nd->path); | |
1908 | } | |
31e6b01f | 1909 | } else { |
582aa64a | 1910 | /* Caller must check execute permissions on the starting path component */ |
2903ff01 | 1911 | struct fd f = fdget_raw(dfd); |
31e6b01f NP |
1912 | struct dentry *dentry; |
1913 | ||
2903ff01 AV |
1914 | if (!f.file) |
1915 | return -EBADF; | |
31e6b01f | 1916 | |
2903ff01 | 1917 | dentry = f.file->f_path.dentry; |
31e6b01f | 1918 | |
6e8a1f87 | 1919 | if (name->name[0]) { |
44b1d530 | 1920 | if (!d_can_lookup(dentry)) { |
2903ff01 AV |
1921 | fdput(f); |
1922 | return -ENOTDIR; | |
1923 | } | |
f52e0c11 | 1924 | } |
31e6b01f | 1925 | |
2903ff01 | 1926 | nd->path = f.file->f_path; |
e41f7d4e | 1927 | if (flags & LOOKUP_RCU) { |
9c225f26 | 1928 | if (f.flags & FDPUT_FPUT) |
5e53084d | 1929 | nd->base = f.file; |
e41f7d4e | 1930 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
8b61e74f | 1931 | rcu_read_lock(); |
e41f7d4e | 1932 | } else { |
2903ff01 AV |
1933 | path_get(&nd->path); |
1934 | fdput(f); | |
e41f7d4e | 1935 | } |
31e6b01f | 1936 | } |
31e6b01f | 1937 | |
31e6b01f | 1938 | nd->inode = nd->path.dentry->d_inode; |
4023bfc9 | 1939 | if (!(flags & LOOKUP_RCU)) |
d465887f | 1940 | goto done; |
4023bfc9 | 1941 | if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) |
d465887f | 1942 | goto done; |
4023bfc9 AV |
1943 | if (!(nd->flags & LOOKUP_ROOT)) |
1944 | nd->root.mnt = NULL; | |
1945 | rcu_read_unlock(); | |
1946 | return -ECHILD; | |
d465887f AV |
1947 | done: |
1948 | current->total_link_count = 0; | |
6e8a1f87 | 1949 | return link_path_walk(name->name, nd); |
9b4a9b14 AV |
1950 | } |
1951 | ||
893b7775 AV |
1952 | static void path_cleanup(struct nameidata *nd) |
1953 | { | |
1954 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { | |
1955 | path_put(&nd->root); | |
1956 | nd->root.mnt = NULL; | |
1957 | } | |
1958 | if (unlikely(nd->base)) | |
1959 | fput(nd->base); | |
9b4a9b14 AV |
1960 | } |
1961 | ||
bd92d7fe AV |
1962 | static inline int lookup_last(struct nameidata *nd, struct path *path) |
1963 | { | |
1964 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) | |
1965 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
1966 | ||
1967 | nd->flags &= ~LOOKUP_PARENT; | |
21b9b073 | 1968 | return walk_component(nd, path, nd->flags & LOOKUP_FOLLOW); |
bd92d7fe AV |
1969 | } |
1970 | ||
9b4a9b14 | 1971 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
5eb6b495 | 1972 | static int path_lookupat(int dfd, const struct filename *name, |
9b4a9b14 AV |
1973 | unsigned int flags, struct nameidata *nd) |
1974 | { | |
bd92d7fe AV |
1975 | struct path path; |
1976 | int err; | |
31e6b01f NP |
1977 | |
1978 | /* | |
1979 | * Path walking is largely split up into 2 different synchronisation | |
1980 | * schemes, rcu-walk and ref-walk (explained in | |
1981 | * Documentation/filesystems/path-lookup.txt). These share much of the | |
1982 | * path walk code, but some things particularly setup, cleanup, and | |
1983 | * following mounts are sufficiently divergent that functions are | |
1984 | * duplicated. Typically there is a function foo(), and its RCU | |
1985 | * analogue, foo_rcu(). | |
1986 | * | |
1987 | * -ECHILD is the error number of choice (just to avoid clashes) that | |
1988 | * is returned if some aspect of an rcu-walk fails. Such an error must | |
1989 | * be handled by restarting a traditional ref-walk (which will always | |
1990 | * be able to complete). | |
1991 | */ | |
6e8a1f87 | 1992 | err = path_init(dfd, name, flags, nd); |
bd92d7fe | 1993 | if (!err && !(flags & LOOKUP_PARENT)) { |
bd92d7fe AV |
1994 | err = lookup_last(nd, &path); |
1995 | while (err > 0) { | |
1996 | void *cookie; | |
1997 | struct path link = path; | |
800179c9 KC |
1998 | err = may_follow_link(&link, nd); |
1999 | if (unlikely(err)) | |
2000 | break; | |
bd92d7fe | 2001 | nd->flags |= LOOKUP_PARENT; |
574197e0 | 2002 | err = follow_link(&link, nd, &cookie); |
6d7b5aae AV |
2003 | if (err) |
2004 | break; | |
2005 | err = lookup_last(nd, &path); | |
574197e0 | 2006 | put_link(nd, &link, cookie); |
bd92d7fe AV |
2007 | } |
2008 | } | |
ee0827cd | 2009 | |
9f1fafee AV |
2010 | if (!err) |
2011 | err = complete_walk(nd); | |
bd92d7fe AV |
2012 | |
2013 | if (!err && nd->flags & LOOKUP_DIRECTORY) { | |
44b1d530 | 2014 | if (!d_can_lookup(nd->path.dentry)) { |
bd92d7fe | 2015 | path_put(&nd->path); |
bd23a539 | 2016 | err = -ENOTDIR; |
bd92d7fe AV |
2017 | } |
2018 | } | |
16c2cd71 | 2019 | |
893b7775 | 2020 | path_cleanup(nd); |
bd92d7fe | 2021 | return err; |
ee0827cd | 2022 | } |
31e6b01f | 2023 | |
873f1eed | 2024 | static int filename_lookup(int dfd, struct filename *name, |
ee0827cd AV |
2025 | unsigned int flags, struct nameidata *nd) |
2026 | { | |
5eb6b495 | 2027 | int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); |
ee0827cd | 2028 | if (unlikely(retval == -ECHILD)) |
5eb6b495 | 2029 | retval = path_lookupat(dfd, name, flags, nd); |
ee0827cd | 2030 | if (unlikely(retval == -ESTALE)) |
5eb6b495 | 2031 | retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); |
31e6b01f | 2032 | |
f78570dd | 2033 | if (likely(!retval)) |
adb5c247 | 2034 | audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); |
170aa3d0 | 2035 | return retval; |
1da177e4 LT |
2036 | } |
2037 | ||
873f1eed JL |
2038 | static int do_path_lookup(int dfd, const char *name, |
2039 | unsigned int flags, struct nameidata *nd) | |
2040 | { | |
51689104 PM |
2041 | struct filename *filename = getname_kernel(name); |
2042 | int retval = PTR_ERR(filename); | |
873f1eed | 2043 | |
51689104 PM |
2044 | if (!IS_ERR(filename)) { |
2045 | retval = filename_lookup(dfd, filename, flags, nd); | |
2046 | putname(filename); | |
2047 | } | |
2048 | return retval; | |
873f1eed JL |
2049 | } |
2050 | ||
79714f72 AV |
2051 | /* does lookup, returns the object with parent locked */ |
2052 | struct dentry *kern_path_locked(const char *name, struct path *path) | |
5590ff0d | 2053 | { |
51689104 | 2054 | struct filename *filename = getname_kernel(name); |
79714f72 AV |
2055 | struct nameidata nd; |
2056 | struct dentry *d; | |
51689104 PM |
2057 | int err; |
2058 | ||
2059 | if (IS_ERR(filename)) | |
2060 | return ERR_CAST(filename); | |
2061 | ||
2062 | err = filename_lookup(AT_FDCWD, filename, LOOKUP_PARENT, &nd); | |
2063 | if (err) { | |
2064 | d = ERR_PTR(err); | |
2065 | goto out; | |
2066 | } | |
79714f72 AV |
2067 | if (nd.last_type != LAST_NORM) { |
2068 | path_put(&nd.path); | |
51689104 PM |
2069 | d = ERR_PTR(-EINVAL); |
2070 | goto out; | |
79714f72 AV |
2071 | } |
2072 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); | |
1e0ea001 | 2073 | d = __lookup_hash(&nd.last, nd.path.dentry, 0); |
79714f72 AV |
2074 | if (IS_ERR(d)) { |
2075 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); | |
2076 | path_put(&nd.path); | |
51689104 | 2077 | goto out; |
79714f72 AV |
2078 | } |
2079 | *path = nd.path; | |
51689104 PM |
2080 | out: |
2081 | putname(filename); | |
79714f72 | 2082 | return d; |
5590ff0d UD |
2083 | } |
2084 | ||
d1811465 AV |
2085 | int kern_path(const char *name, unsigned int flags, struct path *path) |
2086 | { | |
2087 | struct nameidata nd; | |
2088 | int res = do_path_lookup(AT_FDCWD, name, flags, &nd); | |
2089 | if (!res) | |
2090 | *path = nd.path; | |
2091 | return res; | |
2092 | } | |
4d359507 | 2093 | EXPORT_SYMBOL(kern_path); |
d1811465 | 2094 | |
16f18200 JJS |
2095 | /** |
2096 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
2097 | * @dentry: pointer to dentry of the base directory | |
2098 | * @mnt: pointer to vfs mount of the base directory | |
2099 | * @name: pointer to file name | |
2100 | * @flags: lookup flags | |
e0a01249 | 2101 | * @path: pointer to struct path to fill |
16f18200 JJS |
2102 | */ |
2103 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
2104 | const char *name, unsigned int flags, | |
e0a01249 | 2105 | struct path *path) |
16f18200 | 2106 | { |
e0a01249 AV |
2107 | struct nameidata nd; |
2108 | int err; | |
2109 | nd.root.dentry = dentry; | |
2110 | nd.root.mnt = mnt; | |
2111 | BUG_ON(flags & LOOKUP_PARENT); | |
5b6ca027 | 2112 | /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ |
e0a01249 AV |
2113 | err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); |
2114 | if (!err) | |
2115 | *path = nd.path; | |
2116 | return err; | |
16f18200 | 2117 | } |
4d359507 | 2118 | EXPORT_SYMBOL(vfs_path_lookup); |
16f18200 | 2119 | |
057f6c01 JM |
2120 | /* |
2121 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
2122 | * needs parent already locked. Doesn't follow mounts. | |
2123 | * SMP-safe. | |
2124 | */ | |
eead1911 | 2125 | static struct dentry *lookup_hash(struct nameidata *nd) |
057f6c01 | 2126 | { |
72bd866a | 2127 | return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); |
1da177e4 LT |
2128 | } |
2129 | ||
eead1911 | 2130 | /** |
a6b91919 | 2131 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
2132 | * @name: pathname component to lookup |
2133 | * @base: base directory to lookup from | |
2134 | * @len: maximum length @len should be interpreted to | |
2135 | * | |
a6b91919 RD |
2136 | * Note that this routine is purely a helper for filesystem usage and should |
2137 | * not be called by generic code. Also note that by using this function the | |
eead1911 CH |
2138 | * nameidata argument is passed to the filesystem methods and a filesystem |
2139 | * using this helper needs to be prepared for that. | |
2140 | */ | |
057f6c01 JM |
2141 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
2142 | { | |
057f6c01 | 2143 | struct qstr this; |
6a96ba54 | 2144 | unsigned int c; |
cda309de | 2145 | int err; |
057f6c01 | 2146 | |
2f9092e1 DW |
2147 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
2148 | ||
6a96ba54 AV |
2149 | this.name = name; |
2150 | this.len = len; | |
0145acc2 | 2151 | this.hash = full_name_hash(name, len); |
6a96ba54 AV |
2152 | if (!len) |
2153 | return ERR_PTR(-EACCES); | |
2154 | ||
21d8a15a AV |
2155 | if (unlikely(name[0] == '.')) { |
2156 | if (len < 2 || (len == 2 && name[1] == '.')) | |
2157 | return ERR_PTR(-EACCES); | |
2158 | } | |
2159 | ||
6a96ba54 AV |
2160 | while (len--) { |
2161 | c = *(const unsigned char *)name++; | |
2162 | if (c == '/' || c == '\0') | |
2163 | return ERR_PTR(-EACCES); | |
6a96ba54 | 2164 | } |
5a202bcd AV |
2165 | /* |
2166 | * See if the low-level filesystem might want | |
2167 | * to use its own hash.. | |
2168 | */ | |
2169 | if (base->d_flags & DCACHE_OP_HASH) { | |
da53be12 | 2170 | int err = base->d_op->d_hash(base, &this); |
5a202bcd AV |
2171 | if (err < 0) |
2172 | return ERR_PTR(err); | |
2173 | } | |
eead1911 | 2174 | |
cda309de MS |
2175 | err = inode_permission(base->d_inode, MAY_EXEC); |
2176 | if (err) | |
2177 | return ERR_PTR(err); | |
2178 | ||
72bd866a | 2179 | return __lookup_hash(&this, base, 0); |
057f6c01 | 2180 | } |
4d359507 | 2181 | EXPORT_SYMBOL(lookup_one_len); |
057f6c01 | 2182 | |
1fa1e7f6 AW |
2183 | int user_path_at_empty(int dfd, const char __user *name, unsigned flags, |
2184 | struct path *path, int *empty) | |
1da177e4 | 2185 | { |
2d8f3038 | 2186 | struct nameidata nd; |
91a27b2a | 2187 | struct filename *tmp = getname_flags(name, flags, empty); |
1da177e4 | 2188 | int err = PTR_ERR(tmp); |
1da177e4 | 2189 | if (!IS_ERR(tmp)) { |
2d8f3038 AV |
2190 | |
2191 | BUG_ON(flags & LOOKUP_PARENT); | |
2192 | ||
873f1eed | 2193 | err = filename_lookup(dfd, tmp, flags, &nd); |
1da177e4 | 2194 | putname(tmp); |
2d8f3038 AV |
2195 | if (!err) |
2196 | *path = nd.path; | |
1da177e4 LT |
2197 | } |
2198 | return err; | |
2199 | } | |
2200 | ||
1fa1e7f6 AW |
2201 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
2202 | struct path *path) | |
2203 | { | |
f7493e5d | 2204 | return user_path_at_empty(dfd, name, flags, path, NULL); |
1fa1e7f6 | 2205 | } |
4d359507 | 2206 | EXPORT_SYMBOL(user_path_at); |
1fa1e7f6 | 2207 | |
873f1eed JL |
2208 | /* |
2209 | * NB: most callers don't do anything directly with the reference to the | |
2210 | * to struct filename, but the nd->last pointer points into the name string | |
2211 | * allocated by getname. So we must hold the reference to it until all | |
2212 | * path-walking is complete. | |
2213 | */ | |
91a27b2a | 2214 | static struct filename * |
9e790bd6 JL |
2215 | user_path_parent(int dfd, const char __user *path, struct nameidata *nd, |
2216 | unsigned int flags) | |
2ad94ae6 | 2217 | { |
91a27b2a | 2218 | struct filename *s = getname(path); |
2ad94ae6 AV |
2219 | int error; |
2220 | ||
9e790bd6 JL |
2221 | /* only LOOKUP_REVAL is allowed in extra flags */ |
2222 | flags &= LOOKUP_REVAL; | |
2223 | ||
2ad94ae6 | 2224 | if (IS_ERR(s)) |
91a27b2a | 2225 | return s; |
2ad94ae6 | 2226 | |
9e790bd6 | 2227 | error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd); |
91a27b2a | 2228 | if (error) { |
2ad94ae6 | 2229 | putname(s); |
91a27b2a JL |
2230 | return ERR_PTR(error); |
2231 | } | |
2ad94ae6 | 2232 | |
91a27b2a | 2233 | return s; |
2ad94ae6 AV |
2234 | } |
2235 | ||
8033426e | 2236 | /** |
197df04c | 2237 | * mountpoint_last - look up last component for umount |
8033426e JL |
2238 | * @nd: pathwalk nameidata - currently pointing at parent directory of "last" |
2239 | * @path: pointer to container for result | |
2240 | * | |
2241 | * This is a special lookup_last function just for umount. In this case, we | |
2242 | * need to resolve the path without doing any revalidation. | |
2243 | * | |
2244 | * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since | |
2245 | * mountpoints are always pinned in the dcache, their ancestors are too. Thus, | |
2246 | * in almost all cases, this lookup will be served out of the dcache. The only | |
2247 | * cases where it won't are if nd->last refers to a symlink or the path is | |
2248 | * bogus and it doesn't exist. | |
2249 | * | |
2250 | * Returns: | |
2251 | * -error: if there was an error during lookup. This includes -ENOENT if the | |
2252 | * lookup found a negative dentry. The nd->path reference will also be | |
2253 | * put in this case. | |
2254 | * | |
2255 | * 0: if we successfully resolved nd->path and found it to not to be a | |
2256 | * symlink that needs to be followed. "path" will also be populated. | |
2257 | * The nd->path reference will also be put. | |
2258 | * | |
2259 | * 1: if we successfully resolved nd->last and found it to be a symlink | |
2260 | * that needs to be followed. "path" will be populated with the path | |
2261 | * to the link, and nd->path will *not* be put. | |
2262 | */ | |
2263 | static int | |
197df04c | 2264 | mountpoint_last(struct nameidata *nd, struct path *path) |
8033426e JL |
2265 | { |
2266 | int error = 0; | |
2267 | struct dentry *dentry; | |
2268 | struct dentry *dir = nd->path.dentry; | |
2269 | ||
35759521 AV |
2270 | /* If we're in rcuwalk, drop out of it to handle last component */ |
2271 | if (nd->flags & LOOKUP_RCU) { | |
2272 | if (unlazy_walk(nd, NULL)) { | |
2273 | error = -ECHILD; | |
2274 | goto out; | |
2275 | } | |
8033426e JL |
2276 | } |
2277 | ||
2278 | nd->flags &= ~LOOKUP_PARENT; | |
2279 | ||
2280 | if (unlikely(nd->last_type != LAST_NORM)) { | |
2281 | error = handle_dots(nd, nd->last_type); | |
35759521 AV |
2282 | if (error) |
2283 | goto out; | |
2284 | dentry = dget(nd->path.dentry); | |
2285 | goto done; | |
8033426e JL |
2286 | } |
2287 | ||
2288 | mutex_lock(&dir->d_inode->i_mutex); | |
2289 | dentry = d_lookup(dir, &nd->last); | |
2290 | if (!dentry) { | |
2291 | /* | |
2292 | * No cached dentry. Mounted dentries are pinned in the cache, | |
2293 | * so that means that this dentry is probably a symlink or the | |
2294 | * path doesn't actually point to a mounted dentry. | |
2295 | */ | |
2296 | dentry = d_alloc(dir, &nd->last); | |
2297 | if (!dentry) { | |
2298 | error = -ENOMEM; | |
bcceeeba | 2299 | mutex_unlock(&dir->d_inode->i_mutex); |
35759521 | 2300 | goto out; |
8033426e | 2301 | } |
35759521 AV |
2302 | dentry = lookup_real(dir->d_inode, dentry, nd->flags); |
2303 | error = PTR_ERR(dentry); | |
bcceeeba DJ |
2304 | if (IS_ERR(dentry)) { |
2305 | mutex_unlock(&dir->d_inode->i_mutex); | |
35759521 | 2306 | goto out; |
bcceeeba | 2307 | } |
8033426e JL |
2308 | } |
2309 | mutex_unlock(&dir->d_inode->i_mutex); | |
2310 | ||
35759521 | 2311 | done: |
22213318 | 2312 | if (!dentry->d_inode || d_is_negative(dentry)) { |
35759521 AV |
2313 | error = -ENOENT; |
2314 | dput(dentry); | |
2315 | goto out; | |
8033426e | 2316 | } |
35759521 | 2317 | path->dentry = dentry; |
295dc39d | 2318 | path->mnt = nd->path.mnt; |
b18825a7 | 2319 | if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) |
35759521 | 2320 | return 1; |
295dc39d | 2321 | mntget(path->mnt); |
35759521 AV |
2322 | follow_mount(path); |
2323 | error = 0; | |
2324 | out: | |
8033426e JL |
2325 | terminate_walk(nd); |
2326 | return error; | |
2327 | } | |
2328 | ||
2329 | /** | |
197df04c | 2330 | * path_mountpoint - look up a path to be umounted |
8033426e JL |
2331 | * @dfd: directory file descriptor to start walk from |
2332 | * @name: full pathname to walk | |
606d6fe3 | 2333 | * @path: pointer to container for result |
8033426e | 2334 | * @flags: lookup flags |
8033426e JL |
2335 | * |
2336 | * Look up the given name, but don't attempt to revalidate the last component. | |
606d6fe3 | 2337 | * Returns 0 and "path" will be valid on success; Returns error otherwise. |
8033426e JL |
2338 | */ |
2339 | static int | |
668696dc AV |
2340 | path_mountpoint(int dfd, const struct filename *name, struct path *path, |
2341 | unsigned int flags) | |
8033426e | 2342 | { |
8033426e JL |
2343 | struct nameidata nd; |
2344 | int err; | |
2345 | ||
6e8a1f87 | 2346 | err = path_init(dfd, name, flags, &nd); |
8033426e | 2347 | if (unlikely(err)) |
115cbfdc | 2348 | goto out; |
8033426e | 2349 | |
197df04c | 2350 | err = mountpoint_last(&nd, path); |
8033426e JL |
2351 | while (err > 0) { |
2352 | void *cookie; | |
2353 | struct path link = *path; | |
2354 | err = may_follow_link(&link, &nd); | |
2355 | if (unlikely(err)) | |
2356 | break; | |
2357 | nd.flags |= LOOKUP_PARENT; | |
2358 | err = follow_link(&link, &nd, &cookie); | |
2359 | if (err) | |
2360 | break; | |
197df04c | 2361 | err = mountpoint_last(&nd, path); |
8033426e JL |
2362 | put_link(&nd, &link, cookie); |
2363 | } | |
2364 | out: | |
893b7775 | 2365 | path_cleanup(&nd); |
8033426e JL |
2366 | return err; |
2367 | } | |
2368 | ||
2d864651 | 2369 | static int |
668696dc | 2370 | filename_mountpoint(int dfd, struct filename *name, struct path *path, |
2d864651 AV |
2371 | unsigned int flags) |
2372 | { | |
cbaab2db | 2373 | int error; |
668696dc AV |
2374 | if (IS_ERR(name)) |
2375 | return PTR_ERR(name); | |
2376 | error = path_mountpoint(dfd, name, path, flags | LOOKUP_RCU); | |
2d864651 | 2377 | if (unlikely(error == -ECHILD)) |
668696dc | 2378 | error = path_mountpoint(dfd, name, path, flags); |
2d864651 | 2379 | if (unlikely(error == -ESTALE)) |
668696dc | 2380 | error = path_mountpoint(dfd, name, path, flags | LOOKUP_REVAL); |
2d864651 | 2381 | if (likely(!error)) |
668696dc AV |
2382 | audit_inode(name, path->dentry, 0); |
2383 | putname(name); | |
2d864651 AV |
2384 | return error; |
2385 | } | |
2386 | ||
8033426e | 2387 | /** |
197df04c | 2388 | * user_path_mountpoint_at - lookup a path from userland in order to umount it |
8033426e JL |
2389 | * @dfd: directory file descriptor |
2390 | * @name: pathname from userland | |
2391 | * @flags: lookup flags | |
2392 | * @path: pointer to container to hold result | |
2393 | * | |
2394 | * A umount is a special case for path walking. We're not actually interested | |
2395 | * in the inode in this situation, and ESTALE errors can be a problem. We | |
2396 | * simply want track down the dentry and vfsmount attached at the mountpoint | |
2397 | * and avoid revalidating the last component. | |
2398 | * | |
2399 | * Returns 0 and populates "path" on success. | |
2400 | */ | |
2401 | int | |
197df04c | 2402 | user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, |
8033426e JL |
2403 | struct path *path) |
2404 | { | |
cbaab2db | 2405 | return filename_mountpoint(dfd, getname(name), path, flags); |
8033426e JL |
2406 | } |
2407 | ||
2d864651 AV |
2408 | int |
2409 | kern_path_mountpoint(int dfd, const char *name, struct path *path, | |
2410 | unsigned int flags) | |
2411 | { | |
cbaab2db | 2412 | return filename_mountpoint(dfd, getname_kernel(name), path, flags); |
2d864651 AV |
2413 | } |
2414 | EXPORT_SYMBOL(kern_path_mountpoint); | |
2415 | ||
cbdf35bc | 2416 | int __check_sticky(struct inode *dir, struct inode *inode) |
1da177e4 | 2417 | { |
8e96e3b7 | 2418 | kuid_t fsuid = current_fsuid(); |
da9592ed | 2419 | |
8e96e3b7 | 2420 | if (uid_eq(inode->i_uid, fsuid)) |
1da177e4 | 2421 | return 0; |
8e96e3b7 | 2422 | if (uid_eq(dir->i_uid, fsuid)) |
1da177e4 | 2423 | return 0; |
23adbe12 | 2424 | return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); |
1da177e4 | 2425 | } |
cbdf35bc | 2426 | EXPORT_SYMBOL(__check_sticky); |
1da177e4 LT |
2427 | |
2428 | /* | |
2429 | * Check whether we can remove a link victim from directory dir, check | |
2430 | * whether the type of victim is right. | |
2431 | * 1. We can't do it if dir is read-only (done in permission()) | |
2432 | * 2. We should have write and exec permissions on dir | |
2433 | * 3. We can't remove anything from append-only dir | |
2434 | * 4. We can't do anything with immutable dir (done in permission()) | |
2435 | * 5. If the sticky bit on dir is set we should either | |
2436 | * a. be owner of dir, or | |
2437 | * b. be owner of victim, or | |
2438 | * c. have CAP_FOWNER capability | |
2439 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
2440 | * links pointing to it. | |
2441 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
2442 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
2443 | * 9. We can't remove a root or mountpoint. | |
2444 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
2445 | * nfs_async_unlink(). | |
2446 | */ | |
b18825a7 | 2447 | static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) |
1da177e4 | 2448 | { |
b18825a7 | 2449 | struct inode *inode = victim->d_inode; |
1da177e4 LT |
2450 | int error; |
2451 | ||
b18825a7 | 2452 | if (d_is_negative(victim)) |
1da177e4 | 2453 | return -ENOENT; |
b18825a7 | 2454 | BUG_ON(!inode); |
1da177e4 LT |
2455 | |
2456 | BUG_ON(victim->d_parent->d_inode != dir); | |
4fa6b5ec | 2457 | audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); |
1da177e4 | 2458 | |
f419a2e3 | 2459 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2460 | if (error) |
2461 | return error; | |
2462 | if (IS_APPEND(dir)) | |
2463 | return -EPERM; | |
b18825a7 DH |
2464 | |
2465 | if (check_sticky(dir, inode) || IS_APPEND(inode) || | |
2466 | IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) | |
1da177e4 LT |
2467 | return -EPERM; |
2468 | if (isdir) { | |
44b1d530 | 2469 | if (!d_is_dir(victim)) |
1da177e4 LT |
2470 | return -ENOTDIR; |
2471 | if (IS_ROOT(victim)) | |
2472 | return -EBUSY; | |
44b1d530 | 2473 | } else if (d_is_dir(victim)) |
1da177e4 LT |
2474 | return -EISDIR; |
2475 | if (IS_DEADDIR(dir)) | |
2476 | return -ENOENT; | |
2477 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
2478 | return -EBUSY; | |
2479 | return 0; | |
2480 | } | |
2481 | ||
2482 | /* Check whether we can create an object with dentry child in directory | |
2483 | * dir. | |
2484 | * 1. We can't do it if child already exists (open has special treatment for | |
2485 | * this case, but since we are inlined it's OK) | |
2486 | * 2. We can't do it if dir is read-only (done in permission()) | |
2487 | * 3. We should have write and exec permissions on dir | |
2488 | * 4. We can't do it if dir is immutable (done in permission()) | |
2489 | */ | |
a95164d9 | 2490 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 | 2491 | { |
14e972b4 | 2492 | audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); |
1da177e4 LT |
2493 | if (child->d_inode) |
2494 | return -EEXIST; | |
2495 | if (IS_DEADDIR(dir)) | |
2496 | return -ENOENT; | |
f419a2e3 | 2497 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2498 | } |
2499 | ||
1da177e4 LT |
2500 | /* |
2501 | * p1 and p2 should be directories on the same fs. | |
2502 | */ | |
2503 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
2504 | { | |
2505 | struct dentry *p; | |
2506 | ||
2507 | if (p1 == p2) { | |
f2eace23 | 2508 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
2509 | return NULL; |
2510 | } | |
2511 | ||
a11f3a05 | 2512 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 | 2513 | |
e2761a11 OH |
2514 | p = d_ancestor(p2, p1); |
2515 | if (p) { | |
2516 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); | |
2517 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
2518 | return p; | |
1da177e4 LT |
2519 | } |
2520 | ||
e2761a11 OH |
2521 | p = d_ancestor(p1, p2); |
2522 | if (p) { | |
2523 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); | |
2524 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
2525 | return p; | |
1da177e4 LT |
2526 | } |
2527 | ||
f2eace23 | 2528 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
d1b72cc6 | 2529 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); |
1da177e4 LT |
2530 | return NULL; |
2531 | } | |
4d359507 | 2532 | EXPORT_SYMBOL(lock_rename); |
1da177e4 LT |
2533 | |
2534 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
2535 | { | |
1b1dcc1b | 2536 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 2537 | if (p1 != p2) { |
1b1dcc1b | 2538 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 2539 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
2540 | } |
2541 | } | |
4d359507 | 2542 | EXPORT_SYMBOL(unlock_rename); |
1da177e4 | 2543 | |
4acdaf27 | 2544 | int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
312b63fb | 2545 | bool want_excl) |
1da177e4 | 2546 | { |
a95164d9 | 2547 | int error = may_create(dir, dentry); |
1da177e4 LT |
2548 | if (error) |
2549 | return error; | |
2550 | ||
acfa4380 | 2551 | if (!dir->i_op->create) |
1da177e4 LT |
2552 | return -EACCES; /* shouldn't it be ENOSYS? */ |
2553 | mode &= S_IALLUGO; | |
2554 | mode |= S_IFREG; | |
2555 | error = security_inode_create(dir, dentry, mode); | |
2556 | if (error) | |
2557 | return error; | |
312b63fb | 2558 | error = dir->i_op->create(dir, dentry, mode, want_excl); |
a74574aa | 2559 | if (!error) |
f38aa942 | 2560 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2561 | return error; |
2562 | } | |
4d359507 | 2563 | EXPORT_SYMBOL(vfs_create); |
1da177e4 | 2564 | |
73d049a4 | 2565 | static int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 2566 | { |
3fb64190 | 2567 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
2568 | struct inode *inode = dentry->d_inode; |
2569 | int error; | |
2570 | ||
bcda7652 AV |
2571 | /* O_PATH? */ |
2572 | if (!acc_mode) | |
2573 | return 0; | |
2574 | ||
1da177e4 LT |
2575 | if (!inode) |
2576 | return -ENOENT; | |
2577 | ||
c8fe8f30 CH |
2578 | switch (inode->i_mode & S_IFMT) { |
2579 | case S_IFLNK: | |
1da177e4 | 2580 | return -ELOOP; |
c8fe8f30 CH |
2581 | case S_IFDIR: |
2582 | if (acc_mode & MAY_WRITE) | |
2583 | return -EISDIR; | |
2584 | break; | |
2585 | case S_IFBLK: | |
2586 | case S_IFCHR: | |
3fb64190 | 2587 | if (path->mnt->mnt_flags & MNT_NODEV) |
1da177e4 | 2588 | return -EACCES; |
c8fe8f30 CH |
2589 | /*FALLTHRU*/ |
2590 | case S_IFIFO: | |
2591 | case S_IFSOCK: | |
1da177e4 | 2592 | flag &= ~O_TRUNC; |
c8fe8f30 | 2593 | break; |
4a3fd211 | 2594 | } |
b41572e9 | 2595 | |
3fb64190 | 2596 | error = inode_permission(inode, acc_mode); |
b41572e9 DH |
2597 | if (error) |
2598 | return error; | |
6146f0d5 | 2599 | |
1da177e4 LT |
2600 | /* |
2601 | * An append-only file must be opened in append mode for writing. | |
2602 | */ | |
2603 | if (IS_APPEND(inode)) { | |
8737c930 | 2604 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
7715b521 | 2605 | return -EPERM; |
1da177e4 | 2606 | if (flag & O_TRUNC) |
7715b521 | 2607 | return -EPERM; |
1da177e4 LT |
2608 | } |
2609 | ||
2610 | /* O_NOATIME can only be set by the owner or superuser */ | |
2e149670 | 2611 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
7715b521 | 2612 | return -EPERM; |
1da177e4 | 2613 | |
f3c7691e | 2614 | return 0; |
7715b521 | 2615 | } |
1da177e4 | 2616 | |
e1181ee6 | 2617 | static int handle_truncate(struct file *filp) |
7715b521 | 2618 | { |
e1181ee6 | 2619 | struct path *path = &filp->f_path; |
7715b521 AV |
2620 | struct inode *inode = path->dentry->d_inode; |
2621 | int error = get_write_access(inode); | |
2622 | if (error) | |
2623 | return error; | |
2624 | /* | |
2625 | * Refuse to truncate files with mandatory locks held on them. | |
2626 | */ | |
d7a06983 | 2627 | error = locks_verify_locked(filp); |
7715b521 | 2628 | if (!error) |
ea0d3ab2 | 2629 | error = security_path_truncate(path); |
7715b521 AV |
2630 | if (!error) { |
2631 | error = do_truncate(path->dentry, 0, | |
2632 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
e1181ee6 | 2633 | filp); |
7715b521 AV |
2634 | } |
2635 | put_write_access(inode); | |
acd0c935 | 2636 | return error; |
1da177e4 LT |
2637 | } |
2638 | ||
d57999e1 DH |
2639 | static inline int open_to_namei_flags(int flag) |
2640 | { | |
8a5e929d AV |
2641 | if ((flag & O_ACCMODE) == 3) |
2642 | flag--; | |
d57999e1 DH |
2643 | return flag; |
2644 | } | |
2645 | ||
d18e9008 MS |
2646 | static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) |
2647 | { | |
2648 | int error = security_path_mknod(dir, dentry, mode, 0); | |
2649 | if (error) | |
2650 | return error; | |
2651 | ||
2652 | error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); | |
2653 | if (error) | |
2654 | return error; | |
2655 | ||
2656 | return security_inode_create(dir->dentry->d_inode, dentry, mode); | |
2657 | } | |
2658 | ||
1acf0af9 DH |
2659 | /* |
2660 | * Attempt to atomically look up, create and open a file from a negative | |
2661 | * dentry. | |
2662 | * | |
2663 | * Returns 0 if successful. The file will have been created and attached to | |
2664 | * @file by the filesystem calling finish_open(). | |
2665 | * | |
2666 | * Returns 1 if the file was looked up only or didn't need creating. The | |
2667 | * caller will need to perform the open themselves. @path will have been | |
2668 | * updated to point to the new dentry. This may be negative. | |
2669 | * | |
2670 | * Returns an error code otherwise. | |
2671 | */ | |
2675a4eb AV |
2672 | static int atomic_open(struct nameidata *nd, struct dentry *dentry, |
2673 | struct path *path, struct file *file, | |
2674 | const struct open_flags *op, | |
64894cf8 | 2675 | bool got_write, bool need_lookup, |
2675a4eb | 2676 | int *opened) |
d18e9008 MS |
2677 | { |
2678 | struct inode *dir = nd->path.dentry->d_inode; | |
2679 | unsigned open_flag = open_to_namei_flags(op->open_flag); | |
2680 | umode_t mode; | |
2681 | int error; | |
2682 | int acc_mode; | |
d18e9008 MS |
2683 | int create_error = 0; |
2684 | struct dentry *const DENTRY_NOT_SET = (void *) -1UL; | |
116cc022 | 2685 | bool excl; |
d18e9008 MS |
2686 | |
2687 | BUG_ON(dentry->d_inode); | |
2688 | ||
2689 | /* Don't create child dentry for a dead directory. */ | |
2690 | if (unlikely(IS_DEADDIR(dir))) { | |
2675a4eb | 2691 | error = -ENOENT; |
d18e9008 MS |
2692 | goto out; |
2693 | } | |
2694 | ||
62b259d8 | 2695 | mode = op->mode; |
d18e9008 MS |
2696 | if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) |
2697 | mode &= ~current_umask(); | |
2698 | ||
116cc022 MS |
2699 | excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); |
2700 | if (excl) | |
d18e9008 | 2701 | open_flag &= ~O_TRUNC; |
d18e9008 MS |
2702 | |
2703 | /* | |
2704 | * Checking write permission is tricky, bacuse we don't know if we are | |
2705 | * going to actually need it: O_CREAT opens should work as long as the | |
2706 | * file exists. But checking existence breaks atomicity. The trick is | |
2707 | * to check access and if not granted clear O_CREAT from the flags. | |
2708 | * | |
2709 | * Another problem is returing the "right" error value (e.g. for an | |
2710 | * O_EXCL open we want to return EEXIST not EROFS). | |
2711 | */ | |
64894cf8 AV |
2712 | if (((open_flag & (O_CREAT | O_TRUNC)) || |
2713 | (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { | |
2714 | if (!(open_flag & O_CREAT)) { | |
d18e9008 MS |
2715 | /* |
2716 | * No O_CREATE -> atomicity not a requirement -> fall | |
2717 | * back to lookup + open | |
2718 | */ | |
2719 | goto no_open; | |
2720 | } else if (open_flag & (O_EXCL | O_TRUNC)) { | |
2721 | /* Fall back and fail with the right error */ | |
64894cf8 | 2722 | create_error = -EROFS; |
d18e9008 MS |
2723 | goto no_open; |
2724 | } else { | |
2725 | /* No side effects, safe to clear O_CREAT */ | |
64894cf8 | 2726 | create_error = -EROFS; |
d18e9008 MS |
2727 | open_flag &= ~O_CREAT; |
2728 | } | |
2729 | } | |
2730 | ||
2731 | if (open_flag & O_CREAT) { | |
38227f78 | 2732 | error = may_o_create(&nd->path, dentry, mode); |
d18e9008 MS |
2733 | if (error) { |
2734 | create_error = error; | |
2735 | if (open_flag & O_EXCL) | |
2736 | goto no_open; | |
2737 | open_flag &= ~O_CREAT; | |
2738 | } | |
2739 | } | |
2740 | ||
2741 | if (nd->flags & LOOKUP_DIRECTORY) | |
2742 | open_flag |= O_DIRECTORY; | |
2743 | ||
30d90494 AV |
2744 | file->f_path.dentry = DENTRY_NOT_SET; |
2745 | file->f_path.mnt = nd->path.mnt; | |
2746 | error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, | |
47237687 | 2747 | opened); |
d9585277 | 2748 | if (error < 0) { |
d9585277 AV |
2749 | if (create_error && error == -ENOENT) |
2750 | error = create_error; | |
d18e9008 MS |
2751 | goto out; |
2752 | } | |
2753 | ||
d9585277 | 2754 | if (error) { /* returned 1, that is */ |
30d90494 | 2755 | if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { |
2675a4eb | 2756 | error = -EIO; |
d18e9008 MS |
2757 | goto out; |
2758 | } | |
30d90494 | 2759 | if (file->f_path.dentry) { |
d18e9008 | 2760 | dput(dentry); |
30d90494 | 2761 | dentry = file->f_path.dentry; |
d18e9008 | 2762 | } |
03da633a AV |
2763 | if (*opened & FILE_CREATED) |
2764 | fsnotify_create(dir, dentry); | |
2765 | if (!dentry->d_inode) { | |
2766 | WARN_ON(*opened & FILE_CREATED); | |
2767 | if (create_error) { | |
2768 | error = create_error; | |
2769 | goto out; | |
2770 | } | |
2771 | } else { | |
2772 | if (excl && !(*opened & FILE_CREATED)) { | |
2773 | error = -EEXIST; | |
2774 | goto out; | |
2775 | } | |
62b2ce96 | 2776 | } |
d18e9008 MS |
2777 | goto looked_up; |
2778 | } | |
2779 | ||
2780 | /* | |
2781 | * We didn't have the inode before the open, so check open permission | |
2782 | * here. | |
2783 | */ | |
03da633a AV |
2784 | acc_mode = op->acc_mode; |
2785 | if (*opened & FILE_CREATED) { | |
2786 | WARN_ON(!(open_flag & O_CREAT)); | |
2787 | fsnotify_create(dir, dentry); | |
2788 | acc_mode = MAY_OPEN; | |
2789 | } | |
2675a4eb AV |
2790 | error = may_open(&file->f_path, acc_mode, open_flag); |
2791 | if (error) | |
2792 | fput(file); | |
d18e9008 MS |
2793 | |
2794 | out: | |
2795 | dput(dentry); | |
2675a4eb | 2796 | return error; |
d18e9008 | 2797 | |
d18e9008 MS |
2798 | no_open: |
2799 | if (need_lookup) { | |
72bd866a | 2800 | dentry = lookup_real(dir, dentry, nd->flags); |
d18e9008 | 2801 | if (IS_ERR(dentry)) |
2675a4eb | 2802 | return PTR_ERR(dentry); |
d18e9008 MS |
2803 | |
2804 | if (create_error) { | |
2805 | int open_flag = op->open_flag; | |
2806 | ||
2675a4eb | 2807 | error = create_error; |
d18e9008 MS |
2808 | if ((open_flag & O_EXCL)) { |
2809 | if (!dentry->d_inode) | |
2810 | goto out; | |
2811 | } else if (!dentry->d_inode) { | |
2812 | goto out; | |
2813 | } else if ((open_flag & O_TRUNC) && | |
e36cb0b8 | 2814 | d_is_reg(dentry)) { |
d18e9008 MS |
2815 | goto out; |
2816 | } | |
2817 | /* will fail later, go on to get the right error */ | |
2818 | } | |
2819 | } | |
2820 | looked_up: | |
2821 | path->dentry = dentry; | |
2822 | path->mnt = nd->path.mnt; | |
2675a4eb | 2823 | return 1; |
d18e9008 MS |
2824 | } |
2825 | ||
d58ffd35 | 2826 | /* |
1acf0af9 | 2827 | * Look up and maybe create and open the last component. |
d58ffd35 MS |
2828 | * |
2829 | * Must be called with i_mutex held on parent. | |
2830 | * | |
1acf0af9 DH |
2831 | * Returns 0 if the file was successfully atomically created (if necessary) and |
2832 | * opened. In this case the file will be returned attached to @file. | |
2833 | * | |
2834 | * Returns 1 if the file was not completely opened at this time, though lookups | |
2835 | * and creations will have been performed and the dentry returned in @path will | |
2836 | * be positive upon return if O_CREAT was specified. If O_CREAT wasn't | |
2837 | * specified then a negative dentry may be returned. | |
2838 | * | |
2839 | * An error code is returned otherwise. | |
2840 | * | |
2841 | * FILE_CREATE will be set in @*opened if the dentry was created and will be | |
2842 | * cleared otherwise prior to returning. | |
d58ffd35 | 2843 | */ |
2675a4eb AV |
2844 | static int lookup_open(struct nameidata *nd, struct path *path, |
2845 | struct file *file, | |
2846 | const struct open_flags *op, | |
64894cf8 | 2847 | bool got_write, int *opened) |
d58ffd35 MS |
2848 | { |
2849 | struct dentry *dir = nd->path.dentry; | |
54ef4872 | 2850 | struct inode *dir_inode = dir->d_inode; |
d58ffd35 MS |
2851 | struct dentry *dentry; |
2852 | int error; | |
54ef4872 | 2853 | bool need_lookup; |
d58ffd35 | 2854 | |
47237687 | 2855 | *opened &= ~FILE_CREATED; |
201f956e | 2856 | dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); |
d58ffd35 | 2857 | if (IS_ERR(dentry)) |
2675a4eb | 2858 | return PTR_ERR(dentry); |
d58ffd35 | 2859 | |
d18e9008 MS |
2860 | /* Cached positive dentry: will open in f_op->open */ |
2861 | if (!need_lookup && dentry->d_inode) | |
2862 | goto out_no_open; | |
2863 | ||
2864 | if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { | |
64894cf8 | 2865 | return atomic_open(nd, dentry, path, file, op, got_write, |
47237687 | 2866 | need_lookup, opened); |
d18e9008 MS |
2867 | } |
2868 | ||
54ef4872 MS |
2869 | if (need_lookup) { |
2870 | BUG_ON(dentry->d_inode); | |
2871 | ||
72bd866a | 2872 | dentry = lookup_real(dir_inode, dentry, nd->flags); |
54ef4872 | 2873 | if (IS_ERR(dentry)) |
2675a4eb | 2874 | return PTR_ERR(dentry); |
54ef4872 MS |
2875 | } |
2876 | ||
d58ffd35 MS |
2877 | /* Negative dentry, just create the file */ |
2878 | if (!dentry->d_inode && (op->open_flag & O_CREAT)) { | |
2879 | umode_t mode = op->mode; | |
2880 | if (!IS_POSIXACL(dir->d_inode)) | |
2881 | mode &= ~current_umask(); | |
2882 | /* | |
2883 | * This write is needed to ensure that a | |
2884 | * rw->ro transition does not occur between | |
2885 | * the time when the file is created and when | |
2886 | * a permanent write count is taken through | |
015c3bbc | 2887 | * the 'struct file' in finish_open(). |
d58ffd35 | 2888 | */ |
64894cf8 AV |
2889 | if (!got_write) { |
2890 | error = -EROFS; | |
d58ffd35 | 2891 | goto out_dput; |
64894cf8 | 2892 | } |
47237687 | 2893 | *opened |= FILE_CREATED; |
d58ffd35 MS |
2894 | error = security_path_mknod(&nd->path, dentry, mode, 0); |
2895 | if (error) | |
2896 | goto out_dput; | |
312b63fb AV |
2897 | error = vfs_create(dir->d_inode, dentry, mode, |
2898 | nd->flags & LOOKUP_EXCL); | |
d58ffd35 MS |
2899 | if (error) |
2900 | goto out_dput; | |
2901 | } | |
d18e9008 | 2902 | out_no_open: |
d58ffd35 MS |
2903 | path->dentry = dentry; |
2904 | path->mnt = nd->path.mnt; | |
2675a4eb | 2905 | return 1; |
d58ffd35 MS |
2906 | |
2907 | out_dput: | |
2908 | dput(dentry); | |
2675a4eb | 2909 | return error; |
d58ffd35 MS |
2910 | } |
2911 | ||
31e6b01f | 2912 | /* |
fe2d35ff | 2913 | * Handle the last step of open() |
31e6b01f | 2914 | */ |
2675a4eb AV |
2915 | static int do_last(struct nameidata *nd, struct path *path, |
2916 | struct file *file, const struct open_flags *op, | |
669abf4e | 2917 | int *opened, struct filename *name) |
fb1cc555 | 2918 | { |
a1e28038 | 2919 | struct dentry *dir = nd->path.dentry; |
ca344a89 | 2920 | int open_flag = op->open_flag; |
77d660a8 | 2921 | bool will_truncate = (open_flag & O_TRUNC) != 0; |
64894cf8 | 2922 | bool got_write = false; |
bcda7652 | 2923 | int acc_mode = op->acc_mode; |
a1eb3315 | 2924 | struct inode *inode; |
77d660a8 | 2925 | bool symlink_ok = false; |
16b1c1cd MS |
2926 | struct path save_parent = { .dentry = NULL, .mnt = NULL }; |
2927 | bool retried = false; | |
16c2cd71 | 2928 | int error; |
1f36f774 | 2929 | |
c3e380b0 AV |
2930 | nd->flags &= ~LOOKUP_PARENT; |
2931 | nd->flags |= op->intent; | |
2932 | ||
bc77daa7 | 2933 | if (nd->last_type != LAST_NORM) { |
fe2d35ff AV |
2934 | error = handle_dots(nd, nd->last_type); |
2935 | if (error) | |
2675a4eb | 2936 | return error; |
e83db167 | 2937 | goto finish_open; |
1f36f774 | 2938 | } |
67ee3ad2 | 2939 | |
ca344a89 | 2940 | if (!(open_flag & O_CREAT)) { |
fe2d35ff AV |
2941 | if (nd->last.name[nd->last.len]) |
2942 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
bcda7652 | 2943 | if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) |
77d660a8 | 2944 | symlink_ok = true; |
fe2d35ff | 2945 | /* we _can_ be in RCU mode here */ |
e97cdc87 | 2946 | error = lookup_fast(nd, path, &inode); |
71574865 MS |
2947 | if (likely(!error)) |
2948 | goto finish_lookup; | |
2949 | ||
2950 | if (error < 0) | |
2675a4eb | 2951 | goto out; |
71574865 MS |
2952 | |
2953 | BUG_ON(nd->inode != dir->d_inode); | |
b6183df7 MS |
2954 | } else { |
2955 | /* create side of things */ | |
2956 | /* | |
2957 | * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED | |
2958 | * has been cleared when we got to the last component we are | |
2959 | * about to look up | |
2960 | */ | |
2961 | error = complete_walk(nd); | |
2962 | if (error) | |
2675a4eb | 2963 | return error; |
fe2d35ff | 2964 | |
33e2208a | 2965 | audit_inode(name, dir, LOOKUP_PARENT); |
b6183df7 MS |
2966 | error = -EISDIR; |
2967 | /* trailing slashes? */ | |
2968 | if (nd->last.name[nd->last.len]) | |
2675a4eb | 2969 | goto out; |
b6183df7 | 2970 | } |
a2c36b45 | 2971 | |
16b1c1cd | 2972 | retry_lookup: |
64894cf8 AV |
2973 | if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { |
2974 | error = mnt_want_write(nd->path.mnt); | |
2975 | if (!error) | |
2976 | got_write = true; | |
2977 | /* | |
2978 | * do _not_ fail yet - we might not need that or fail with | |
2979 | * a different error; let lookup_open() decide; we'll be | |
2980 | * dropping this one anyway. | |
2981 | */ | |
2982 | } | |
a1e28038 | 2983 | mutex_lock(&dir->d_inode->i_mutex); |
64894cf8 | 2984 | error = lookup_open(nd, path, file, op, got_write, opened); |
d58ffd35 | 2985 | mutex_unlock(&dir->d_inode->i_mutex); |
a1e28038 | 2986 | |
2675a4eb AV |
2987 | if (error <= 0) { |
2988 | if (error) | |
d18e9008 MS |
2989 | goto out; |
2990 | ||
47237687 | 2991 | if ((*opened & FILE_CREATED) || |
496ad9aa | 2992 | !S_ISREG(file_inode(file)->i_mode)) |
77d660a8 | 2993 | will_truncate = false; |
d18e9008 | 2994 | |
adb5c247 | 2995 | audit_inode(name, file->f_path.dentry, 0); |
d18e9008 MS |
2996 | goto opened; |
2997 | } | |
fb1cc555 | 2998 | |
47237687 | 2999 | if (*opened & FILE_CREATED) { |
9b44f1b3 | 3000 | /* Don't check for write permission, don't truncate */ |
ca344a89 | 3001 | open_flag &= ~O_TRUNC; |
77d660a8 | 3002 | will_truncate = false; |
bcda7652 | 3003 | acc_mode = MAY_OPEN; |
d58ffd35 | 3004 | path_to_nameidata(path, nd); |
e83db167 | 3005 | goto finish_open_created; |
fb1cc555 AV |
3006 | } |
3007 | ||
3008 | /* | |
3134f37e | 3009 | * create/update audit record if it already exists. |
fb1cc555 | 3010 | */ |
b18825a7 | 3011 | if (d_is_positive(path->dentry)) |
adb5c247 | 3012 | audit_inode(name, path->dentry, 0); |
fb1cc555 | 3013 | |
d18e9008 MS |
3014 | /* |
3015 | * If atomic_open() acquired write access it is dropped now due to | |
3016 | * possible mount and symlink following (this might be optimized away if | |
3017 | * necessary...) | |
3018 | */ | |
64894cf8 | 3019 | if (got_write) { |
d18e9008 | 3020 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 3021 | got_write = false; |
d18e9008 MS |
3022 | } |
3023 | ||
fb1cc555 | 3024 | error = -EEXIST; |
f8310c59 | 3025 | if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) |
fb1cc555 AV |
3026 | goto exit_dput; |
3027 | ||
9875cf80 DH |
3028 | error = follow_managed(path, nd->flags); |
3029 | if (error < 0) | |
3030 | goto exit_dput; | |
fb1cc555 | 3031 | |
a3fbbde7 AV |
3032 | if (error) |
3033 | nd->flags |= LOOKUP_JUMPED; | |
3034 | ||
decf3400 MS |
3035 | BUG_ON(nd->flags & LOOKUP_RCU); |
3036 | inode = path->dentry->d_inode; | |
5f5daac1 MS |
3037 | finish_lookup: |
3038 | /* we _can_ be in RCU mode here */ | |
fb1cc555 | 3039 | error = -ENOENT; |
22213318 | 3040 | if (!inode || d_is_negative(path->dentry)) { |
54c33e7f | 3041 | path_to_nameidata(path, nd); |
2675a4eb | 3042 | goto out; |
54c33e7f | 3043 | } |
9e67f361 | 3044 | |
b18825a7 | 3045 | if (should_follow_link(path->dentry, !symlink_ok)) { |
d45ea867 MS |
3046 | if (nd->flags & LOOKUP_RCU) { |
3047 | if (unlikely(unlazy_walk(nd, path->dentry))) { | |
3048 | error = -ECHILD; | |
2675a4eb | 3049 | goto out; |
d45ea867 MS |
3050 | } |
3051 | } | |
3052 | BUG_ON(inode != path->dentry->d_inode); | |
2675a4eb | 3053 | return 1; |
d45ea867 | 3054 | } |
fb1cc555 | 3055 | |
16b1c1cd MS |
3056 | if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { |
3057 | path_to_nameidata(path, nd); | |
3058 | } else { | |
3059 | save_parent.dentry = nd->path.dentry; | |
3060 | save_parent.mnt = mntget(path->mnt); | |
3061 | nd->path.dentry = path->dentry; | |
3062 | ||
3063 | } | |
decf3400 | 3064 | nd->inode = inode; |
a3fbbde7 | 3065 | /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ |
bc77daa7 | 3066 | finish_open: |
a3fbbde7 | 3067 | error = complete_walk(nd); |
16b1c1cd MS |
3068 | if (error) { |
3069 | path_put(&save_parent); | |
2675a4eb | 3070 | return error; |
16b1c1cd | 3071 | } |
bc77daa7 | 3072 | audit_inode(name, nd->path.dentry, 0); |
fb1cc555 | 3073 | error = -EISDIR; |
44b1d530 | 3074 | if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) |
2675a4eb | 3075 | goto out; |
af2f5542 | 3076 | error = -ENOTDIR; |
44b1d530 | 3077 | if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) |
2675a4eb | 3078 | goto out; |
6c0d46c4 | 3079 | if (!S_ISREG(nd->inode->i_mode)) |
77d660a8 | 3080 | will_truncate = false; |
6c0d46c4 | 3081 | |
0f9d1a10 AV |
3082 | if (will_truncate) { |
3083 | error = mnt_want_write(nd->path.mnt); | |
3084 | if (error) | |
2675a4eb | 3085 | goto out; |
64894cf8 | 3086 | got_write = true; |
0f9d1a10 | 3087 | } |
e83db167 | 3088 | finish_open_created: |
bcda7652 | 3089 | error = may_open(&nd->path, acc_mode, open_flag); |
ca344a89 | 3090 | if (error) |
2675a4eb | 3091 | goto out; |
4aa7c634 MS |
3092 | |
3093 | BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ | |
3094 | error = vfs_open(&nd->path, file, current_cred()); | |
3095 | if (!error) { | |
3096 | *opened |= FILE_OPENED; | |
3097 | } else { | |
30d90494 | 3098 | if (error == -EOPENSTALE) |
f60dc3db | 3099 | goto stale_open; |
015c3bbc | 3100 | goto out; |
f60dc3db | 3101 | } |
a8277b9b | 3102 | opened: |
2675a4eb | 3103 | error = open_check_o_direct(file); |
015c3bbc MS |
3104 | if (error) |
3105 | goto exit_fput; | |
3034a146 | 3106 | error = ima_file_check(file, op->acc_mode, *opened); |
aa4caadb MS |
3107 | if (error) |
3108 | goto exit_fput; | |
3109 | ||
3110 | if (will_truncate) { | |
2675a4eb | 3111 | error = handle_truncate(file); |
aa4caadb MS |
3112 | if (error) |
3113 | goto exit_fput; | |
0f9d1a10 | 3114 | } |
ca344a89 | 3115 | out: |
64894cf8 | 3116 | if (got_write) |
0f9d1a10 | 3117 | mnt_drop_write(nd->path.mnt); |
16b1c1cd | 3118 | path_put(&save_parent); |
e276ae67 | 3119 | terminate_walk(nd); |
2675a4eb | 3120 | return error; |
fb1cc555 | 3121 | |
fb1cc555 AV |
3122 | exit_dput: |
3123 | path_put_conditional(path, nd); | |
ca344a89 | 3124 | goto out; |
015c3bbc | 3125 | exit_fput: |
2675a4eb AV |
3126 | fput(file); |
3127 | goto out; | |
015c3bbc | 3128 | |
f60dc3db MS |
3129 | stale_open: |
3130 | /* If no saved parent or already retried then can't retry */ | |
3131 | if (!save_parent.dentry || retried) | |
3132 | goto out; | |
3133 | ||
3134 | BUG_ON(save_parent.dentry != dir); | |
3135 | path_put(&nd->path); | |
3136 | nd->path = save_parent; | |
3137 | nd->inode = dir->d_inode; | |
3138 | save_parent.mnt = NULL; | |
3139 | save_parent.dentry = NULL; | |
64894cf8 | 3140 | if (got_write) { |
f60dc3db | 3141 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 3142 | got_write = false; |
f60dc3db MS |
3143 | } |
3144 | retried = true; | |
3145 | goto retry_lookup; | |
fb1cc555 AV |
3146 | } |
3147 | ||
60545d0d AV |
3148 | static int do_tmpfile(int dfd, struct filename *pathname, |
3149 | struct nameidata *nd, int flags, | |
3150 | const struct open_flags *op, | |
3151 | struct file *file, int *opened) | |
3152 | { | |
3153 | static const struct qstr name = QSTR_INIT("/", 1); | |
3154 | struct dentry *dentry, *child; | |
3155 | struct inode *dir; | |
5eb6b495 | 3156 | int error = path_lookupat(dfd, pathname, |
60545d0d AV |
3157 | flags | LOOKUP_DIRECTORY, nd); |
3158 | if (unlikely(error)) | |
3159 | return error; | |
3160 | error = mnt_want_write(nd->path.mnt); | |
3161 | if (unlikely(error)) | |
3162 | goto out; | |
3163 | /* we want directory to be writable */ | |
3164 | error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); | |
3165 | if (error) | |
3166 | goto out2; | |
3167 | dentry = nd->path.dentry; | |
3168 | dir = dentry->d_inode; | |
3169 | if (!dir->i_op->tmpfile) { | |
3170 | error = -EOPNOTSUPP; | |
3171 | goto out2; | |
3172 | } | |
3173 | child = d_alloc(dentry, &name); | |
3174 | if (unlikely(!child)) { | |
3175 | error = -ENOMEM; | |
3176 | goto out2; | |
3177 | } | |
3178 | nd->flags &= ~LOOKUP_DIRECTORY; | |
3179 | nd->flags |= op->intent; | |
3180 | dput(nd->path.dentry); | |
3181 | nd->path.dentry = child; | |
3182 | error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); | |
3183 | if (error) | |
3184 | goto out2; | |
3185 | audit_inode(pathname, nd->path.dentry, 0); | |
69a91c23 ER |
3186 | /* Don't check for other permissions, the inode was just created */ |
3187 | error = may_open(&nd->path, MAY_OPEN, op->open_flag); | |
60545d0d AV |
3188 | if (error) |
3189 | goto out2; | |
3190 | file->f_path.mnt = nd->path.mnt; | |
3191 | error = finish_open(file, nd->path.dentry, NULL, opened); | |
3192 | if (error) | |
3193 | goto out2; | |
3194 | error = open_check_o_direct(file); | |
f4e0c30c | 3195 | if (error) { |
60545d0d | 3196 | fput(file); |
f4e0c30c AV |
3197 | } else if (!(op->open_flag & O_EXCL)) { |
3198 | struct inode *inode = file_inode(file); | |
3199 | spin_lock(&inode->i_lock); | |
3200 | inode->i_state |= I_LINKABLE; | |
3201 | spin_unlock(&inode->i_lock); | |
3202 | } | |
60545d0d AV |
3203 | out2: |
3204 | mnt_drop_write(nd->path.mnt); | |
3205 | out: | |
3206 | path_put(&nd->path); | |
3207 | return error; | |
3208 | } | |
3209 | ||
669abf4e | 3210 | static struct file *path_openat(int dfd, struct filename *pathname, |
73d049a4 | 3211 | struct nameidata *nd, const struct open_flags *op, int flags) |
1da177e4 | 3212 | { |
30d90494 | 3213 | struct file *file; |
9850c056 | 3214 | struct path path; |
47237687 | 3215 | int opened = 0; |
13aab428 | 3216 | int error; |
31e6b01f | 3217 | |
30d90494 | 3218 | file = get_empty_filp(); |
1afc99be AV |
3219 | if (IS_ERR(file)) |
3220 | return file; | |
31e6b01f | 3221 | |
30d90494 | 3222 | file->f_flags = op->open_flag; |
31e6b01f | 3223 | |
bb458c64 | 3224 | if (unlikely(file->f_flags & __O_TMPFILE)) { |
60545d0d AV |
3225 | error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); |
3226 | goto out; | |
3227 | } | |
3228 | ||
6e8a1f87 | 3229 | error = path_init(dfd, pathname, flags, nd); |
31e6b01f | 3230 | if (unlikely(error)) |
2675a4eb | 3231 | goto out; |
1da177e4 | 3232 | |
2675a4eb AV |
3233 | error = do_last(nd, &path, file, op, &opened, pathname); |
3234 | while (unlikely(error > 0)) { /* trailing symlink */ | |
7b9337aa | 3235 | struct path link = path; |
def4af30 | 3236 | void *cookie; |
574197e0 | 3237 | if (!(nd->flags & LOOKUP_FOLLOW)) { |
73d049a4 AV |
3238 | path_put_conditional(&path, nd); |
3239 | path_put(&nd->path); | |
2675a4eb | 3240 | error = -ELOOP; |
40b39136 AV |
3241 | break; |
3242 | } | |
800179c9 KC |
3243 | error = may_follow_link(&link, nd); |
3244 | if (unlikely(error)) | |
3245 | break; | |
73d049a4 AV |
3246 | nd->flags |= LOOKUP_PARENT; |
3247 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); | |
574197e0 | 3248 | error = follow_link(&link, nd, &cookie); |
c3e380b0 | 3249 | if (unlikely(error)) |
2675a4eb AV |
3250 | break; |
3251 | error = do_last(nd, &path, file, op, &opened, pathname); | |
574197e0 | 3252 | put_link(nd, &link, cookie); |
806b681c | 3253 | } |
10fa8e62 | 3254 | out: |
893b7775 | 3255 | path_cleanup(nd); |
2675a4eb AV |
3256 | if (!(opened & FILE_OPENED)) { |
3257 | BUG_ON(!error); | |
30d90494 | 3258 | put_filp(file); |
16b1c1cd | 3259 | } |
2675a4eb AV |
3260 | if (unlikely(error)) { |
3261 | if (error == -EOPENSTALE) { | |
3262 | if (flags & LOOKUP_RCU) | |
3263 | error = -ECHILD; | |
3264 | else | |
3265 | error = -ESTALE; | |
3266 | } | |
3267 | file = ERR_PTR(error); | |
3268 | } | |
3269 | return file; | |
1da177e4 LT |
3270 | } |
3271 | ||
669abf4e | 3272 | struct file *do_filp_open(int dfd, struct filename *pathname, |
f9652e10 | 3273 | const struct open_flags *op) |
13aab428 | 3274 | { |
73d049a4 | 3275 | struct nameidata nd; |
f9652e10 | 3276 | int flags = op->lookup_flags; |
13aab428 AV |
3277 | struct file *filp; |
3278 | ||
73d049a4 | 3279 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); |
13aab428 | 3280 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
73d049a4 | 3281 | filp = path_openat(dfd, pathname, &nd, op, flags); |
13aab428 | 3282 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
73d049a4 | 3283 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); |
13aab428 AV |
3284 | return filp; |
3285 | } | |
3286 | ||
73d049a4 | 3287 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
f9652e10 | 3288 | const char *name, const struct open_flags *op) |
73d049a4 AV |
3289 | { |
3290 | struct nameidata nd; | |
3291 | struct file *file; | |
51689104 | 3292 | struct filename *filename; |
f9652e10 | 3293 | int flags = op->lookup_flags | LOOKUP_ROOT; |
73d049a4 AV |
3294 | |
3295 | nd.root.mnt = mnt; | |
3296 | nd.root.dentry = dentry; | |
3297 | ||
b18825a7 | 3298 | if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) |
73d049a4 AV |
3299 | return ERR_PTR(-ELOOP); |
3300 | ||
51689104 PM |
3301 | filename = getname_kernel(name); |
3302 | if (unlikely(IS_ERR(filename))) | |
3303 | return ERR_CAST(filename); | |
3304 | ||
3305 | file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); | |
73d049a4 | 3306 | if (unlikely(file == ERR_PTR(-ECHILD))) |
51689104 | 3307 | file = path_openat(-1, filename, &nd, op, flags); |
73d049a4 | 3308 | if (unlikely(file == ERR_PTR(-ESTALE))) |
51689104 PM |
3309 | file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); |
3310 | putname(filename); | |
73d049a4 AV |
3311 | return file; |
3312 | } | |
3313 | ||
fa14a0b8 | 3314 | static struct dentry *filename_create(int dfd, struct filename *name, |
1ac12b4b | 3315 | struct path *path, unsigned int lookup_flags) |
1da177e4 | 3316 | { |
c663e5d8 | 3317 | struct dentry *dentry = ERR_PTR(-EEXIST); |
ed75e95d | 3318 | struct nameidata nd; |
c30dabfe | 3319 | int err2; |
1ac12b4b JL |
3320 | int error; |
3321 | bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); | |
3322 | ||
3323 | /* | |
3324 | * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any | |
3325 | * other flags passed in are ignored! | |
3326 | */ | |
3327 | lookup_flags &= LOOKUP_REVAL; | |
3328 | ||
fa14a0b8 | 3329 | error = filename_lookup(dfd, name, LOOKUP_PARENT|lookup_flags, &nd); |
ed75e95d AV |
3330 | if (error) |
3331 | return ERR_PTR(error); | |
1da177e4 | 3332 | |
c663e5d8 CH |
3333 | /* |
3334 | * Yucky last component or no last component at all? | |
3335 | * (foo/., foo/.., /////) | |
3336 | */ | |
ed75e95d AV |
3337 | if (nd.last_type != LAST_NORM) |
3338 | goto out; | |
3339 | nd.flags &= ~LOOKUP_PARENT; | |
3340 | nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; | |
c663e5d8 | 3341 | |
c30dabfe JK |
3342 | /* don't fail immediately if it's r/o, at least try to report other errors */ |
3343 | err2 = mnt_want_write(nd.path.mnt); | |
c663e5d8 CH |
3344 | /* |
3345 | * Do the final lookup. | |
3346 | */ | |
ed75e95d AV |
3347 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
3348 | dentry = lookup_hash(&nd); | |
1da177e4 | 3349 | if (IS_ERR(dentry)) |
a8104a9f | 3350 | goto unlock; |
c663e5d8 | 3351 | |
a8104a9f | 3352 | error = -EEXIST; |
b18825a7 | 3353 | if (d_is_positive(dentry)) |
a8104a9f | 3354 | goto fail; |
b18825a7 | 3355 | |
c663e5d8 CH |
3356 | /* |
3357 | * Special case - lookup gave negative, but... we had foo/bar/ | |
3358 | * From the vfs_mknod() POV we just have a negative dentry - | |
3359 | * all is fine. Let's be bastards - you had / on the end, you've | |
3360 | * been asking for (non-existent) directory. -ENOENT for you. | |
3361 | */ | |
ed75e95d | 3362 | if (unlikely(!is_dir && nd.last.name[nd.last.len])) { |
a8104a9f | 3363 | error = -ENOENT; |
ed75e95d | 3364 | goto fail; |
e9baf6e5 | 3365 | } |
c30dabfe JK |
3366 | if (unlikely(err2)) { |
3367 | error = err2; | |
a8104a9f | 3368 | goto fail; |
c30dabfe | 3369 | } |
ed75e95d | 3370 | *path = nd.path; |
1da177e4 | 3371 | return dentry; |
1da177e4 | 3372 | fail: |
a8104a9f AV |
3373 | dput(dentry); |
3374 | dentry = ERR_PTR(error); | |
3375 | unlock: | |
ed75e95d | 3376 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
c30dabfe JK |
3377 | if (!err2) |
3378 | mnt_drop_write(nd.path.mnt); | |
ed75e95d AV |
3379 | out: |
3380 | path_put(&nd.path); | |
1da177e4 LT |
3381 | return dentry; |
3382 | } | |
fa14a0b8 AV |
3383 | |
3384 | struct dentry *kern_path_create(int dfd, const char *pathname, | |
3385 | struct path *path, unsigned int lookup_flags) | |
3386 | { | |
51689104 PM |
3387 | struct filename *filename = getname_kernel(pathname); |
3388 | struct dentry *res; | |
3389 | ||
3390 | if (IS_ERR(filename)) | |
3391 | return ERR_CAST(filename); | |
3392 | res = filename_create(dfd, filename, path, lookup_flags); | |
3393 | putname(filename); | |
3394 | return res; | |
fa14a0b8 | 3395 | } |
dae6ad8f AV |
3396 | EXPORT_SYMBOL(kern_path_create); |
3397 | ||
921a1650 AV |
3398 | void done_path_create(struct path *path, struct dentry *dentry) |
3399 | { | |
3400 | dput(dentry); | |
3401 | mutex_unlock(&path->dentry->d_inode->i_mutex); | |
a8104a9f | 3402 | mnt_drop_write(path->mnt); |
921a1650 AV |
3403 | path_put(path); |
3404 | } | |
3405 | EXPORT_SYMBOL(done_path_create); | |
3406 | ||
1ac12b4b JL |
3407 | struct dentry *user_path_create(int dfd, const char __user *pathname, |
3408 | struct path *path, unsigned int lookup_flags) | |
dae6ad8f | 3409 | { |
91a27b2a | 3410 | struct filename *tmp = getname(pathname); |
dae6ad8f AV |
3411 | struct dentry *res; |
3412 | if (IS_ERR(tmp)) | |
3413 | return ERR_CAST(tmp); | |
fa14a0b8 | 3414 | res = filename_create(dfd, tmp, path, lookup_flags); |
dae6ad8f AV |
3415 | putname(tmp); |
3416 | return res; | |
3417 | } | |
3418 | EXPORT_SYMBOL(user_path_create); | |
3419 | ||
1a67aafb | 3420 | int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
1da177e4 | 3421 | { |
a95164d9 | 3422 | int error = may_create(dir, dentry); |
1da177e4 LT |
3423 | |
3424 | if (error) | |
3425 | return error; | |
3426 | ||
975d6b39 | 3427 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) |
1da177e4 LT |
3428 | return -EPERM; |
3429 | ||
acfa4380 | 3430 | if (!dir->i_op->mknod) |
1da177e4 LT |
3431 | return -EPERM; |
3432 | ||
08ce5f16 SH |
3433 | error = devcgroup_inode_mknod(mode, dev); |
3434 | if (error) | |
3435 | return error; | |
3436 | ||
1da177e4 LT |
3437 | error = security_inode_mknod(dir, dentry, mode, dev); |
3438 | if (error) | |
3439 | return error; | |
3440 | ||
1da177e4 | 3441 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 3442 | if (!error) |
f38aa942 | 3443 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3444 | return error; |
3445 | } | |
4d359507 | 3446 | EXPORT_SYMBOL(vfs_mknod); |
1da177e4 | 3447 | |
f69aac00 | 3448 | static int may_mknod(umode_t mode) |
463c3197 DH |
3449 | { |
3450 | switch (mode & S_IFMT) { | |
3451 | case S_IFREG: | |
3452 | case S_IFCHR: | |
3453 | case S_IFBLK: | |
3454 | case S_IFIFO: | |
3455 | case S_IFSOCK: | |
3456 | case 0: /* zero mode translates to S_IFREG */ | |
3457 | return 0; | |
3458 | case S_IFDIR: | |
3459 | return -EPERM; | |
3460 | default: | |
3461 | return -EINVAL; | |
3462 | } | |
3463 | } | |
3464 | ||
8208a22b | 3465 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, |
2e4d0924 | 3466 | unsigned, dev) |
1da177e4 | 3467 | { |
2ad94ae6 | 3468 | struct dentry *dentry; |
dae6ad8f AV |
3469 | struct path path; |
3470 | int error; | |
972567f1 | 3471 | unsigned int lookup_flags = 0; |
1da177e4 | 3472 | |
8e4bfca1 AV |
3473 | error = may_mknod(mode); |
3474 | if (error) | |
3475 | return error; | |
972567f1 JL |
3476 | retry: |
3477 | dentry = user_path_create(dfd, filename, &path, lookup_flags); | |
dae6ad8f AV |
3478 | if (IS_ERR(dentry)) |
3479 | return PTR_ERR(dentry); | |
2ad94ae6 | 3480 | |
dae6ad8f | 3481 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3482 | mode &= ~current_umask(); |
dae6ad8f | 3483 | error = security_path_mknod(&path, dentry, mode, dev); |
be6d3e56 | 3484 | if (error) |
a8104a9f | 3485 | goto out; |
463c3197 | 3486 | switch (mode & S_IFMT) { |
1da177e4 | 3487 | case 0: case S_IFREG: |
312b63fb | 3488 | error = vfs_create(path.dentry->d_inode,dentry,mode,true); |
1da177e4 LT |
3489 | break; |
3490 | case S_IFCHR: case S_IFBLK: | |
dae6ad8f | 3491 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
3492 | new_decode_dev(dev)); |
3493 | break; | |
3494 | case S_IFIFO: case S_IFSOCK: | |
dae6ad8f | 3495 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 3496 | break; |
1da177e4 | 3497 | } |
a8104a9f | 3498 | out: |
921a1650 | 3499 | done_path_create(&path, dentry); |
972567f1 JL |
3500 | if (retry_estale(error, lookup_flags)) { |
3501 | lookup_flags |= LOOKUP_REVAL; | |
3502 | goto retry; | |
3503 | } | |
1da177e4 LT |
3504 | return error; |
3505 | } | |
3506 | ||
8208a22b | 3507 | SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) |
5590ff0d UD |
3508 | { |
3509 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
3510 | } | |
3511 | ||
18bb1db3 | 3512 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
1da177e4 | 3513 | { |
a95164d9 | 3514 | int error = may_create(dir, dentry); |
8de52778 | 3515 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
3516 | |
3517 | if (error) | |
3518 | return error; | |
3519 | ||
acfa4380 | 3520 | if (!dir->i_op->mkdir) |
1da177e4 LT |
3521 | return -EPERM; |
3522 | ||
3523 | mode &= (S_IRWXUGO|S_ISVTX); | |
3524 | error = security_inode_mkdir(dir, dentry, mode); | |
3525 | if (error) | |
3526 | return error; | |
3527 | ||
8de52778 AV |
3528 | if (max_links && dir->i_nlink >= max_links) |
3529 | return -EMLINK; | |
3530 | ||
1da177e4 | 3531 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 3532 | if (!error) |
f38aa942 | 3533 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
3534 | return error; |
3535 | } | |
4d359507 | 3536 | EXPORT_SYMBOL(vfs_mkdir); |
1da177e4 | 3537 | |
a218d0fd | 3538 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) |
1da177e4 | 3539 | { |
6902d925 | 3540 | struct dentry *dentry; |
dae6ad8f AV |
3541 | struct path path; |
3542 | int error; | |
b76d8b82 | 3543 | unsigned int lookup_flags = LOOKUP_DIRECTORY; |
1da177e4 | 3544 | |
b76d8b82 JL |
3545 | retry: |
3546 | dentry = user_path_create(dfd, pathname, &path, lookup_flags); | |
6902d925 | 3547 | if (IS_ERR(dentry)) |
dae6ad8f | 3548 | return PTR_ERR(dentry); |
1da177e4 | 3549 | |
dae6ad8f | 3550 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3551 | mode &= ~current_umask(); |
dae6ad8f | 3552 | error = security_path_mkdir(&path, dentry, mode); |
a8104a9f AV |
3553 | if (!error) |
3554 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); | |
921a1650 | 3555 | done_path_create(&path, dentry); |
b76d8b82 JL |
3556 | if (retry_estale(error, lookup_flags)) { |
3557 | lookup_flags |= LOOKUP_REVAL; | |
3558 | goto retry; | |
3559 | } | |
1da177e4 LT |
3560 | return error; |
3561 | } | |
3562 | ||
a218d0fd | 3563 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) |
5590ff0d UD |
3564 | { |
3565 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
3566 | } | |
3567 | ||
1da177e4 | 3568 | /* |
a71905f0 | 3569 | * The dentry_unhash() helper will try to drop the dentry early: we |
c0d02594 | 3570 | * should have a usage count of 1 if we're the only user of this |
a71905f0 SW |
3571 | * dentry, and if that is true (possibly after pruning the dcache), |
3572 | * then we drop the dentry now. | |
1da177e4 LT |
3573 | * |
3574 | * A low-level filesystem can, if it choses, legally | |
3575 | * do a | |
3576 | * | |
3577 | * if (!d_unhashed(dentry)) | |
3578 | * return -EBUSY; | |
3579 | * | |
3580 | * if it cannot handle the case of removing a directory | |
3581 | * that is still in use by something else.. | |
3582 | */ | |
3583 | void dentry_unhash(struct dentry *dentry) | |
3584 | { | |
dc168427 | 3585 | shrink_dcache_parent(dentry); |
1da177e4 | 3586 | spin_lock(&dentry->d_lock); |
98474236 | 3587 | if (dentry->d_lockref.count == 1) |
1da177e4 LT |
3588 | __d_drop(dentry); |
3589 | spin_unlock(&dentry->d_lock); | |
1da177e4 | 3590 | } |
4d359507 | 3591 | EXPORT_SYMBOL(dentry_unhash); |
1da177e4 LT |
3592 | |
3593 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
3594 | { | |
3595 | int error = may_delete(dir, dentry, 1); | |
3596 | ||
3597 | if (error) | |
3598 | return error; | |
3599 | ||
acfa4380 | 3600 | if (!dir->i_op->rmdir) |
1da177e4 LT |
3601 | return -EPERM; |
3602 | ||
1d2ef590 | 3603 | dget(dentry); |
1b1dcc1b | 3604 | mutex_lock(&dentry->d_inode->i_mutex); |
912dbc15 SW |
3605 | |
3606 | error = -EBUSY; | |
7af1364f | 3607 | if (is_local_mountpoint(dentry)) |
912dbc15 SW |
3608 | goto out; |
3609 | ||
3610 | error = security_inode_rmdir(dir, dentry); | |
3611 | if (error) | |
3612 | goto out; | |
3613 | ||
3cebde24 | 3614 | shrink_dcache_parent(dentry); |
912dbc15 SW |
3615 | error = dir->i_op->rmdir(dir, dentry); |
3616 | if (error) | |
3617 | goto out; | |
3618 | ||
3619 | dentry->d_inode->i_flags |= S_DEAD; | |
3620 | dont_mount(dentry); | |
8ed936b5 | 3621 | detach_mounts(dentry); |
912dbc15 SW |
3622 | |
3623 | out: | |
1b1dcc1b | 3624 | mutex_unlock(&dentry->d_inode->i_mutex); |
1d2ef590 | 3625 | dput(dentry); |
912dbc15 | 3626 | if (!error) |
1da177e4 | 3627 | d_delete(dentry); |
1da177e4 LT |
3628 | return error; |
3629 | } | |
4d359507 | 3630 | EXPORT_SYMBOL(vfs_rmdir); |
1da177e4 | 3631 | |
5590ff0d | 3632 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
3633 | { |
3634 | int error = 0; | |
91a27b2a | 3635 | struct filename *name; |
1da177e4 LT |
3636 | struct dentry *dentry; |
3637 | struct nameidata nd; | |
c6ee9206 JL |
3638 | unsigned int lookup_flags = 0; |
3639 | retry: | |
3640 | name = user_path_parent(dfd, pathname, &nd, lookup_flags); | |
91a27b2a JL |
3641 | if (IS_ERR(name)) |
3642 | return PTR_ERR(name); | |
1da177e4 LT |
3643 | |
3644 | switch(nd.last_type) { | |
0612d9fb OH |
3645 | case LAST_DOTDOT: |
3646 | error = -ENOTEMPTY; | |
3647 | goto exit1; | |
3648 | case LAST_DOT: | |
3649 | error = -EINVAL; | |
3650 | goto exit1; | |
3651 | case LAST_ROOT: | |
3652 | error = -EBUSY; | |
3653 | goto exit1; | |
1da177e4 | 3654 | } |
0612d9fb OH |
3655 | |
3656 | nd.flags &= ~LOOKUP_PARENT; | |
c30dabfe JK |
3657 | error = mnt_want_write(nd.path.mnt); |
3658 | if (error) | |
3659 | goto exit1; | |
0612d9fb | 3660 | |
4ac91378 | 3661 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 3662 | dentry = lookup_hash(&nd); |
1da177e4 | 3663 | error = PTR_ERR(dentry); |
6902d925 DH |
3664 | if (IS_ERR(dentry)) |
3665 | goto exit2; | |
e6bc45d6 TT |
3666 | if (!dentry->d_inode) { |
3667 | error = -ENOENT; | |
3668 | goto exit3; | |
3669 | } | |
be6d3e56 KT |
3670 | error = security_path_rmdir(&nd.path, dentry); |
3671 | if (error) | |
c30dabfe | 3672 | goto exit3; |
4ac91378 | 3673 | error = vfs_rmdir(nd.path.dentry->d_inode, dentry); |
0622753b | 3674 | exit3: |
6902d925 DH |
3675 | dput(dentry); |
3676 | exit2: | |
4ac91378 | 3677 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
c30dabfe | 3678 | mnt_drop_write(nd.path.mnt); |
1da177e4 | 3679 | exit1: |
1d957f9b | 3680 | path_put(&nd.path); |
1da177e4 | 3681 | putname(name); |
c6ee9206 JL |
3682 | if (retry_estale(error, lookup_flags)) { |
3683 | lookup_flags |= LOOKUP_REVAL; | |
3684 | goto retry; | |
3685 | } | |
1da177e4 LT |
3686 | return error; |
3687 | } | |
3688 | ||
3cdad428 | 3689 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
3690 | { |
3691 | return do_rmdir(AT_FDCWD, pathname); | |
3692 | } | |
3693 | ||
b21996e3 BF |
3694 | /** |
3695 | * vfs_unlink - unlink a filesystem object | |
3696 | * @dir: parent directory | |
3697 | * @dentry: victim | |
3698 | * @delegated_inode: returns victim inode, if the inode is delegated. | |
3699 | * | |
3700 | * The caller must hold dir->i_mutex. | |
3701 | * | |
3702 | * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and | |
3703 | * return a reference to the inode in delegated_inode. The caller | |
3704 | * should then break the delegation on that inode and retry. Because | |
3705 | * breaking a delegation may take a long time, the caller should drop | |
3706 | * dir->i_mutex before doing so. | |
3707 | * | |
3708 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
3709 | * be appropriate for callers that expect the underlying filesystem not | |
3710 | * to be NFS exported. | |
3711 | */ | |
3712 | int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) | |
1da177e4 | 3713 | { |
9accbb97 | 3714 | struct inode *target = dentry->d_inode; |
1da177e4 LT |
3715 | int error = may_delete(dir, dentry, 0); |
3716 | ||
3717 | if (error) | |
3718 | return error; | |
3719 | ||
acfa4380 | 3720 | if (!dir->i_op->unlink) |
1da177e4 LT |
3721 | return -EPERM; |
3722 | ||
9accbb97 | 3723 | mutex_lock(&target->i_mutex); |
8ed936b5 | 3724 | if (is_local_mountpoint(dentry)) |
1da177e4 LT |
3725 | error = -EBUSY; |
3726 | else { | |
3727 | error = security_inode_unlink(dir, dentry); | |
bec1052e | 3728 | if (!error) { |
5a14696c BF |
3729 | error = try_break_deleg(target, delegated_inode); |
3730 | if (error) | |
b21996e3 | 3731 | goto out; |
1da177e4 | 3732 | error = dir->i_op->unlink(dir, dentry); |
8ed936b5 | 3733 | if (!error) { |
d83c49f3 | 3734 | dont_mount(dentry); |
8ed936b5 EB |
3735 | detach_mounts(dentry); |
3736 | } | |
bec1052e | 3737 | } |
1da177e4 | 3738 | } |
b21996e3 | 3739 | out: |
9accbb97 | 3740 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
3741 | |
3742 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
3743 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
9accbb97 | 3744 | fsnotify_link_count(target); |
e234f35c | 3745 | d_delete(dentry); |
1da177e4 | 3746 | } |
0eeca283 | 3747 | |
1da177e4 LT |
3748 | return error; |
3749 | } | |
4d359507 | 3750 | EXPORT_SYMBOL(vfs_unlink); |
1da177e4 LT |
3751 | |
3752 | /* | |
3753 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 3754 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
3755 | * writeout happening, and we don't want to prevent access to the directory |
3756 | * while waiting on the I/O. | |
3757 | */ | |
5590ff0d | 3758 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 3759 | { |
2ad94ae6 | 3760 | int error; |
91a27b2a | 3761 | struct filename *name; |
1da177e4 LT |
3762 | struct dentry *dentry; |
3763 | struct nameidata nd; | |
3764 | struct inode *inode = NULL; | |
b21996e3 | 3765 | struct inode *delegated_inode = NULL; |
5d18f813 JL |
3766 | unsigned int lookup_flags = 0; |
3767 | retry: | |
3768 | name = user_path_parent(dfd, pathname, &nd, lookup_flags); | |
91a27b2a JL |
3769 | if (IS_ERR(name)) |
3770 | return PTR_ERR(name); | |
2ad94ae6 | 3771 | |
1da177e4 LT |
3772 | error = -EISDIR; |
3773 | if (nd.last_type != LAST_NORM) | |
3774 | goto exit1; | |
0612d9fb OH |
3775 | |
3776 | nd.flags &= ~LOOKUP_PARENT; | |
c30dabfe JK |
3777 | error = mnt_want_write(nd.path.mnt); |
3778 | if (error) | |
3779 | goto exit1; | |
b21996e3 | 3780 | retry_deleg: |
4ac91378 | 3781 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 3782 | dentry = lookup_hash(&nd); |
1da177e4 LT |
3783 | error = PTR_ERR(dentry); |
3784 | if (!IS_ERR(dentry)) { | |
3785 | /* Why not before? Because we want correct error value */ | |
50338b88 TE |
3786 | if (nd.last.name[nd.last.len]) |
3787 | goto slashes; | |
1da177e4 | 3788 | inode = dentry->d_inode; |
b18825a7 | 3789 | if (d_is_negative(dentry)) |
e6bc45d6 TT |
3790 | goto slashes; |
3791 | ihold(inode); | |
be6d3e56 KT |
3792 | error = security_path_unlink(&nd.path, dentry); |
3793 | if (error) | |
c30dabfe | 3794 | goto exit2; |
b21996e3 | 3795 | error = vfs_unlink(nd.path.dentry->d_inode, dentry, &delegated_inode); |
c30dabfe | 3796 | exit2: |
1da177e4 LT |
3797 | dput(dentry); |
3798 | } | |
4ac91378 | 3799 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 LT |
3800 | if (inode) |
3801 | iput(inode); /* truncate the inode here */ | |
b21996e3 BF |
3802 | inode = NULL; |
3803 | if (delegated_inode) { | |
5a14696c | 3804 | error = break_deleg_wait(&delegated_inode); |
b21996e3 BF |
3805 | if (!error) |
3806 | goto retry_deleg; | |
3807 | } | |
c30dabfe | 3808 | mnt_drop_write(nd.path.mnt); |
1da177e4 | 3809 | exit1: |
1d957f9b | 3810 | path_put(&nd.path); |
1da177e4 | 3811 | putname(name); |
5d18f813 JL |
3812 | if (retry_estale(error, lookup_flags)) { |
3813 | lookup_flags |= LOOKUP_REVAL; | |
3814 | inode = NULL; | |
3815 | goto retry; | |
3816 | } | |
1da177e4 LT |
3817 | return error; |
3818 | ||
3819 | slashes: | |
b18825a7 DH |
3820 | if (d_is_negative(dentry)) |
3821 | error = -ENOENT; | |
44b1d530 | 3822 | else if (d_is_dir(dentry)) |
b18825a7 DH |
3823 | error = -EISDIR; |
3824 | else | |
3825 | error = -ENOTDIR; | |
1da177e4 LT |
3826 | goto exit2; |
3827 | } | |
3828 | ||
2e4d0924 | 3829 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
3830 | { |
3831 | if ((flag & ~AT_REMOVEDIR) != 0) | |
3832 | return -EINVAL; | |
3833 | ||
3834 | if (flag & AT_REMOVEDIR) | |
3835 | return do_rmdir(dfd, pathname); | |
3836 | ||
3837 | return do_unlinkat(dfd, pathname); | |
3838 | } | |
3839 | ||
3480b257 | 3840 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
3841 | { |
3842 | return do_unlinkat(AT_FDCWD, pathname); | |
3843 | } | |
3844 | ||
db2e747b | 3845 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 3846 | { |
a95164d9 | 3847 | int error = may_create(dir, dentry); |
1da177e4 LT |
3848 | |
3849 | if (error) | |
3850 | return error; | |
3851 | ||
acfa4380 | 3852 | if (!dir->i_op->symlink) |
1da177e4 LT |
3853 | return -EPERM; |
3854 | ||
3855 | error = security_inode_symlink(dir, dentry, oldname); | |
3856 | if (error) | |
3857 | return error; | |
3858 | ||
1da177e4 | 3859 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 3860 | if (!error) |
f38aa942 | 3861 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3862 | return error; |
3863 | } | |
4d359507 | 3864 | EXPORT_SYMBOL(vfs_symlink); |
1da177e4 | 3865 | |
2e4d0924 HC |
3866 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
3867 | int, newdfd, const char __user *, newname) | |
1da177e4 | 3868 | { |
2ad94ae6 | 3869 | int error; |
91a27b2a | 3870 | struct filename *from; |
6902d925 | 3871 | struct dentry *dentry; |
dae6ad8f | 3872 | struct path path; |
f46d3567 | 3873 | unsigned int lookup_flags = 0; |
1da177e4 LT |
3874 | |
3875 | from = getname(oldname); | |
2ad94ae6 | 3876 | if (IS_ERR(from)) |
1da177e4 | 3877 | return PTR_ERR(from); |
f46d3567 JL |
3878 | retry: |
3879 | dentry = user_path_create(newdfd, newname, &path, lookup_flags); | |
6902d925 DH |
3880 | error = PTR_ERR(dentry); |
3881 | if (IS_ERR(dentry)) | |
dae6ad8f | 3882 | goto out_putname; |
6902d925 | 3883 | |
91a27b2a | 3884 | error = security_path_symlink(&path, dentry, from->name); |
a8104a9f | 3885 | if (!error) |
91a27b2a | 3886 | error = vfs_symlink(path.dentry->d_inode, dentry, from->name); |
921a1650 | 3887 | done_path_create(&path, dentry); |
f46d3567 JL |
3888 | if (retry_estale(error, lookup_flags)) { |
3889 | lookup_flags |= LOOKUP_REVAL; | |
3890 | goto retry; | |
3891 | } | |
6902d925 | 3892 | out_putname: |
1da177e4 LT |
3893 | putname(from); |
3894 | return error; | |
3895 | } | |
3896 | ||
3480b257 | 3897 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
3898 | { |
3899 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
3900 | } | |
3901 | ||
146a8595 BF |
3902 | /** |
3903 | * vfs_link - create a new link | |
3904 | * @old_dentry: object to be linked | |
3905 | * @dir: new parent | |
3906 | * @new_dentry: where to create the new link | |
3907 | * @delegated_inode: returns inode needing a delegation break | |
3908 | * | |
3909 | * The caller must hold dir->i_mutex | |
3910 | * | |
3911 | * If vfs_link discovers a delegation on the to-be-linked file in need | |
3912 | * of breaking, it will return -EWOULDBLOCK and return a reference to the | |
3913 | * inode in delegated_inode. The caller should then break the delegation | |
3914 | * and retry. Because breaking a delegation may take a long time, the | |
3915 | * caller should drop the i_mutex before doing so. | |
3916 | * | |
3917 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
3918 | * be appropriate for callers that expect the underlying filesystem not | |
3919 | * to be NFS exported. | |
3920 | */ | |
3921 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) | |
1da177e4 LT |
3922 | { |
3923 | struct inode *inode = old_dentry->d_inode; | |
8de52778 | 3924 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
3925 | int error; |
3926 | ||
3927 | if (!inode) | |
3928 | return -ENOENT; | |
3929 | ||
a95164d9 | 3930 | error = may_create(dir, new_dentry); |
1da177e4 LT |
3931 | if (error) |
3932 | return error; | |
3933 | ||
3934 | if (dir->i_sb != inode->i_sb) | |
3935 | return -EXDEV; | |
3936 | ||
3937 | /* | |
3938 | * A link to an append-only or immutable file cannot be created. | |
3939 | */ | |
3940 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
3941 | return -EPERM; | |
acfa4380 | 3942 | if (!dir->i_op->link) |
1da177e4 | 3943 | return -EPERM; |
7e79eedb | 3944 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
3945 | return -EPERM; |
3946 | ||
3947 | error = security_inode_link(old_dentry, dir, new_dentry); | |
3948 | if (error) | |
3949 | return error; | |
3950 | ||
7e79eedb | 3951 | mutex_lock(&inode->i_mutex); |
aae8a97d | 3952 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
f4e0c30c | 3953 | if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) |
aae8a97d | 3954 | error = -ENOENT; |
8de52778 AV |
3955 | else if (max_links && inode->i_nlink >= max_links) |
3956 | error = -EMLINK; | |
146a8595 BF |
3957 | else { |
3958 | error = try_break_deleg(inode, delegated_inode); | |
3959 | if (!error) | |
3960 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
3961 | } | |
f4e0c30c AV |
3962 | |
3963 | if (!error && (inode->i_state & I_LINKABLE)) { | |
3964 | spin_lock(&inode->i_lock); | |
3965 | inode->i_state &= ~I_LINKABLE; | |
3966 | spin_unlock(&inode->i_lock); | |
3967 | } | |
7e79eedb | 3968 | mutex_unlock(&inode->i_mutex); |
e31e14ec | 3969 | if (!error) |
7e79eedb | 3970 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
3971 | return error; |
3972 | } | |
4d359507 | 3973 | EXPORT_SYMBOL(vfs_link); |
1da177e4 LT |
3974 | |
3975 | /* | |
3976 | * Hardlinks are often used in delicate situations. We avoid | |
3977 | * security-related surprises by not following symlinks on the | |
3978 | * newname. --KAB | |
3979 | * | |
3980 | * We don't follow them on the oldname either to be compatible | |
3981 | * with linux 2.0, and to avoid hard-linking to directories | |
3982 | * and other special files. --ADM | |
3983 | */ | |
2e4d0924 HC |
3984 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
3985 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
3986 | { |
3987 | struct dentry *new_dentry; | |
dae6ad8f | 3988 | struct path old_path, new_path; |
146a8595 | 3989 | struct inode *delegated_inode = NULL; |
11a7b371 | 3990 | int how = 0; |
1da177e4 | 3991 | int error; |
1da177e4 | 3992 | |
11a7b371 | 3993 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
c04030e1 | 3994 | return -EINVAL; |
11a7b371 | 3995 | /* |
f0cc6ffb LT |
3996 | * To use null names we require CAP_DAC_READ_SEARCH |
3997 | * This ensures that not everyone will be able to create | |
3998 | * handlink using the passed filedescriptor. | |
11a7b371 | 3999 | */ |
f0cc6ffb LT |
4000 | if (flags & AT_EMPTY_PATH) { |
4001 | if (!capable(CAP_DAC_READ_SEARCH)) | |
4002 | return -ENOENT; | |
11a7b371 | 4003 | how = LOOKUP_EMPTY; |
f0cc6ffb | 4004 | } |
11a7b371 AK |
4005 | |
4006 | if (flags & AT_SYMLINK_FOLLOW) | |
4007 | how |= LOOKUP_FOLLOW; | |
442e31ca | 4008 | retry: |
11a7b371 | 4009 | error = user_path_at(olddfd, oldname, how, &old_path); |
1da177e4 | 4010 | if (error) |
2ad94ae6 AV |
4011 | return error; |
4012 | ||
442e31ca JL |
4013 | new_dentry = user_path_create(newdfd, newname, &new_path, |
4014 | (how & LOOKUP_REVAL)); | |
1da177e4 | 4015 | error = PTR_ERR(new_dentry); |
6902d925 | 4016 | if (IS_ERR(new_dentry)) |
dae6ad8f AV |
4017 | goto out; |
4018 | ||
4019 | error = -EXDEV; | |
4020 | if (old_path.mnt != new_path.mnt) | |
4021 | goto out_dput; | |
800179c9 KC |
4022 | error = may_linkat(&old_path); |
4023 | if (unlikely(error)) | |
4024 | goto out_dput; | |
dae6ad8f | 4025 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
be6d3e56 | 4026 | if (error) |
a8104a9f | 4027 | goto out_dput; |
146a8595 | 4028 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); |
75c3f29d | 4029 | out_dput: |
921a1650 | 4030 | done_path_create(&new_path, new_dentry); |
146a8595 BF |
4031 | if (delegated_inode) { |
4032 | error = break_deleg_wait(&delegated_inode); | |
d22e6338 OD |
4033 | if (!error) { |
4034 | path_put(&old_path); | |
146a8595 | 4035 | goto retry; |
d22e6338 | 4036 | } |
146a8595 | 4037 | } |
442e31ca | 4038 | if (retry_estale(error, how)) { |
d22e6338 | 4039 | path_put(&old_path); |
442e31ca JL |
4040 | how |= LOOKUP_REVAL; |
4041 | goto retry; | |
4042 | } | |
1da177e4 | 4043 | out: |
2d8f3038 | 4044 | path_put(&old_path); |
1da177e4 LT |
4045 | |
4046 | return error; | |
4047 | } | |
4048 | ||
3480b257 | 4049 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 4050 | { |
c04030e1 | 4051 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
4052 | } |
4053 | ||
bc27027a MS |
4054 | /** |
4055 | * vfs_rename - rename a filesystem object | |
4056 | * @old_dir: parent of source | |
4057 | * @old_dentry: source | |
4058 | * @new_dir: parent of destination | |
4059 | * @new_dentry: destination | |
4060 | * @delegated_inode: returns an inode needing a delegation break | |
520c8b16 | 4061 | * @flags: rename flags |
bc27027a MS |
4062 | * |
4063 | * The caller must hold multiple mutexes--see lock_rename()). | |
4064 | * | |
4065 | * If vfs_rename discovers a delegation in need of breaking at either | |
4066 | * the source or destination, it will return -EWOULDBLOCK and return a | |
4067 | * reference to the inode in delegated_inode. The caller should then | |
4068 | * break the delegation and retry. Because breaking a delegation may | |
4069 | * take a long time, the caller should drop all locks before doing | |
4070 | * so. | |
4071 | * | |
4072 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
4073 | * be appropriate for callers that expect the underlying filesystem not | |
4074 | * to be NFS exported. | |
4075 | * | |
1da177e4 LT |
4076 | * The worst of all namespace operations - renaming directory. "Perverted" |
4077 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
4078 | * Problems: | |
d03b29a2 | 4079 | * a) we can get into loop creation. |
1da177e4 LT |
4080 | * b) race potential - two innocent renames can create a loop together. |
4081 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 4082 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 | 4083 | * story. |
6cedba89 BF |
4084 | * c) we have to lock _four_ objects - parents and victim (if it exists), |
4085 | * and source (if it is not a directory). | |
1b1dcc1b | 4086 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
4087 | * whether the target exists). Solution: try to be smart with locking |
4088 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 4089 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
4090 | * move will be locked. Thus we can rank directories by the tree |
4091 | * (ancestors first) and rank all non-directories after them. | |
4092 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 4093 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
4094 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
4095 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
4096 | * we'd better make sure that there's no link(2) for them. | |
e4eaac06 | 4097 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
1b1dcc1b | 4098 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 4099 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
c41b20e7 | 4100 | * ->i_mutex on parents, which works but leads to some truly excessive |
1da177e4 LT |
4101 | * locking]. |
4102 | */ | |
bc27027a MS |
4103 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, |
4104 | struct inode *new_dir, struct dentry *new_dentry, | |
520c8b16 | 4105 | struct inode **delegated_inode, unsigned int flags) |
1da177e4 | 4106 | { |
bc27027a MS |
4107 | int error; |
4108 | bool is_dir = d_is_dir(old_dentry); | |
4109 | const unsigned char *old_name; | |
4110 | struct inode *source = old_dentry->d_inode; | |
9055cba7 | 4111 | struct inode *target = new_dentry->d_inode; |
da1ce067 MS |
4112 | bool new_is_dir = false; |
4113 | unsigned max_links = new_dir->i_sb->s_max_links; | |
bc27027a MS |
4114 | |
4115 | if (source == target) | |
4116 | return 0; | |
4117 | ||
4118 | error = may_delete(old_dir, old_dentry, is_dir); | |
4119 | if (error) | |
4120 | return error; | |
4121 | ||
da1ce067 | 4122 | if (!target) { |
bc27027a | 4123 | error = may_create(new_dir, new_dentry); |
da1ce067 MS |
4124 | } else { |
4125 | new_is_dir = d_is_dir(new_dentry); | |
4126 | ||
4127 | if (!(flags & RENAME_EXCHANGE)) | |
4128 | error = may_delete(new_dir, new_dentry, is_dir); | |
4129 | else | |
4130 | error = may_delete(new_dir, new_dentry, new_is_dir); | |
4131 | } | |
bc27027a MS |
4132 | if (error) |
4133 | return error; | |
4134 | ||
7177a9c4 | 4135 | if (!old_dir->i_op->rename && !old_dir->i_op->rename2) |
bc27027a | 4136 | return -EPERM; |
1da177e4 | 4137 | |
520c8b16 MS |
4138 | if (flags && !old_dir->i_op->rename2) |
4139 | return -EINVAL; | |
4140 | ||
1da177e4 LT |
4141 | /* |
4142 | * If we are going to change the parent - check write permissions, | |
4143 | * we'll need to flip '..'. | |
4144 | */ | |
da1ce067 MS |
4145 | if (new_dir != old_dir) { |
4146 | if (is_dir) { | |
4147 | error = inode_permission(source, MAY_WRITE); | |
4148 | if (error) | |
4149 | return error; | |
4150 | } | |
4151 | if ((flags & RENAME_EXCHANGE) && new_is_dir) { | |
4152 | error = inode_permission(target, MAY_WRITE); | |
4153 | if (error) | |
4154 | return error; | |
4155 | } | |
1da177e4 LT |
4156 | } |
4157 | ||
0b3974eb MS |
4158 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, |
4159 | flags); | |
1da177e4 LT |
4160 | if (error) |
4161 | return error; | |
4162 | ||
bc27027a | 4163 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
1d2ef590 | 4164 | dget(new_dentry); |
da1ce067 | 4165 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
bc27027a MS |
4166 | lock_two_nondirectories(source, target); |
4167 | else if (target) | |
1b1dcc1b | 4168 | mutex_lock(&target->i_mutex); |
9055cba7 SW |
4169 | |
4170 | error = -EBUSY; | |
7af1364f | 4171 | if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) |
9055cba7 SW |
4172 | goto out; |
4173 | ||
da1ce067 | 4174 | if (max_links && new_dir != old_dir) { |
bc27027a | 4175 | error = -EMLINK; |
da1ce067 | 4176 | if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) |
bc27027a | 4177 | goto out; |
da1ce067 MS |
4178 | if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && |
4179 | old_dir->i_nlink >= max_links) | |
4180 | goto out; | |
4181 | } | |
4182 | if (is_dir && !(flags & RENAME_EXCHANGE) && target) | |
4183 | shrink_dcache_parent(new_dentry); | |
4184 | if (!is_dir) { | |
bc27027a | 4185 | error = try_break_deleg(source, delegated_inode); |
8e6d782c BF |
4186 | if (error) |
4187 | goto out; | |
da1ce067 MS |
4188 | } |
4189 | if (target && !new_is_dir) { | |
4190 | error = try_break_deleg(target, delegated_inode); | |
4191 | if (error) | |
4192 | goto out; | |
8e6d782c | 4193 | } |
7177a9c4 | 4194 | if (!old_dir->i_op->rename2) { |
520c8b16 MS |
4195 | error = old_dir->i_op->rename(old_dir, old_dentry, |
4196 | new_dir, new_dentry); | |
4197 | } else { | |
7177a9c4 | 4198 | WARN_ON(old_dir->i_op->rename != NULL); |
520c8b16 MS |
4199 | error = old_dir->i_op->rename2(old_dir, old_dentry, |
4200 | new_dir, new_dentry, flags); | |
4201 | } | |
51892bbb SW |
4202 | if (error) |
4203 | goto out; | |
4204 | ||
da1ce067 | 4205 | if (!(flags & RENAME_EXCHANGE) && target) { |
bc27027a MS |
4206 | if (is_dir) |
4207 | target->i_flags |= S_DEAD; | |
51892bbb | 4208 | dont_mount(new_dentry); |
8ed936b5 | 4209 | detach_mounts(new_dentry); |
bc27027a | 4210 | } |
da1ce067 MS |
4211 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { |
4212 | if (!(flags & RENAME_EXCHANGE)) | |
4213 | d_move(old_dentry, new_dentry); | |
4214 | else | |
4215 | d_exchange(old_dentry, new_dentry); | |
4216 | } | |
51892bbb | 4217 | out: |
da1ce067 | 4218 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
bc27027a MS |
4219 | unlock_two_nondirectories(source, target); |
4220 | else if (target) | |
4221 | mutex_unlock(&target->i_mutex); | |
1da177e4 | 4222 | dput(new_dentry); |
da1ce067 | 4223 | if (!error) { |
123df294 | 4224 | fsnotify_move(old_dir, new_dir, old_name, is_dir, |
da1ce067 MS |
4225 | !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); |
4226 | if (flags & RENAME_EXCHANGE) { | |
4227 | fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, | |
4228 | new_is_dir, NULL, new_dentry); | |
4229 | } | |
4230 | } | |
0eeca283 RL |
4231 | fsnotify_oldname_free(old_name); |
4232 | ||
1da177e4 LT |
4233 | return error; |
4234 | } | |
4d359507 | 4235 | EXPORT_SYMBOL(vfs_rename); |
1da177e4 | 4236 | |
520c8b16 MS |
4237 | SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, |
4238 | int, newdfd, const char __user *, newname, unsigned int, flags) | |
1da177e4 | 4239 | { |
2ad94ae6 AV |
4240 | struct dentry *old_dir, *new_dir; |
4241 | struct dentry *old_dentry, *new_dentry; | |
4242 | struct dentry *trap; | |
1da177e4 | 4243 | struct nameidata oldnd, newnd; |
8e6d782c | 4244 | struct inode *delegated_inode = NULL; |
91a27b2a JL |
4245 | struct filename *from; |
4246 | struct filename *to; | |
c6a94284 JL |
4247 | unsigned int lookup_flags = 0; |
4248 | bool should_retry = false; | |
2ad94ae6 | 4249 | int error; |
520c8b16 | 4250 | |
0d7a8555 | 4251 | if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) |
da1ce067 MS |
4252 | return -EINVAL; |
4253 | ||
0d7a8555 MS |
4254 | if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && |
4255 | (flags & RENAME_EXCHANGE)) | |
520c8b16 MS |
4256 | return -EINVAL; |
4257 | ||
0d7a8555 MS |
4258 | if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) |
4259 | return -EPERM; | |
4260 | ||
c6a94284 JL |
4261 | retry: |
4262 | from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags); | |
91a27b2a JL |
4263 | if (IS_ERR(from)) { |
4264 | error = PTR_ERR(from); | |
1da177e4 | 4265 | goto exit; |
91a27b2a | 4266 | } |
1da177e4 | 4267 | |
c6a94284 | 4268 | to = user_path_parent(newdfd, newname, &newnd, lookup_flags); |
91a27b2a JL |
4269 | if (IS_ERR(to)) { |
4270 | error = PTR_ERR(to); | |
1da177e4 | 4271 | goto exit1; |
91a27b2a | 4272 | } |
1da177e4 LT |
4273 | |
4274 | error = -EXDEV; | |
4ac91378 | 4275 | if (oldnd.path.mnt != newnd.path.mnt) |
1da177e4 LT |
4276 | goto exit2; |
4277 | ||
4ac91378 | 4278 | old_dir = oldnd.path.dentry; |
1da177e4 LT |
4279 | error = -EBUSY; |
4280 | if (oldnd.last_type != LAST_NORM) | |
4281 | goto exit2; | |
4282 | ||
4ac91378 | 4283 | new_dir = newnd.path.dentry; |
0a7c3937 MS |
4284 | if (flags & RENAME_NOREPLACE) |
4285 | error = -EEXIST; | |
1da177e4 LT |
4286 | if (newnd.last_type != LAST_NORM) |
4287 | goto exit2; | |
4288 | ||
c30dabfe JK |
4289 | error = mnt_want_write(oldnd.path.mnt); |
4290 | if (error) | |
4291 | goto exit2; | |
4292 | ||
0612d9fb OH |
4293 | oldnd.flags &= ~LOOKUP_PARENT; |
4294 | newnd.flags &= ~LOOKUP_PARENT; | |
da1ce067 MS |
4295 | if (!(flags & RENAME_EXCHANGE)) |
4296 | newnd.flags |= LOOKUP_RENAME_TARGET; | |
0612d9fb | 4297 | |
8e6d782c | 4298 | retry_deleg: |
1da177e4 LT |
4299 | trap = lock_rename(new_dir, old_dir); |
4300 | ||
49705b77 | 4301 | old_dentry = lookup_hash(&oldnd); |
1da177e4 LT |
4302 | error = PTR_ERR(old_dentry); |
4303 | if (IS_ERR(old_dentry)) | |
4304 | goto exit3; | |
4305 | /* source must exist */ | |
4306 | error = -ENOENT; | |
b18825a7 | 4307 | if (d_is_negative(old_dentry)) |
1da177e4 | 4308 | goto exit4; |
0a7c3937 MS |
4309 | new_dentry = lookup_hash(&newnd); |
4310 | error = PTR_ERR(new_dentry); | |
4311 | if (IS_ERR(new_dentry)) | |
4312 | goto exit4; | |
4313 | error = -EEXIST; | |
4314 | if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) | |
4315 | goto exit5; | |
da1ce067 MS |
4316 | if (flags & RENAME_EXCHANGE) { |
4317 | error = -ENOENT; | |
4318 | if (d_is_negative(new_dentry)) | |
4319 | goto exit5; | |
4320 | ||
4321 | if (!d_is_dir(new_dentry)) { | |
4322 | error = -ENOTDIR; | |
4323 | if (newnd.last.name[newnd.last.len]) | |
4324 | goto exit5; | |
4325 | } | |
4326 | } | |
1da177e4 | 4327 | /* unless the source is a directory trailing slashes give -ENOTDIR */ |
44b1d530 | 4328 | if (!d_is_dir(old_dentry)) { |
1da177e4 LT |
4329 | error = -ENOTDIR; |
4330 | if (oldnd.last.name[oldnd.last.len]) | |
0a7c3937 | 4331 | goto exit5; |
da1ce067 | 4332 | if (!(flags & RENAME_EXCHANGE) && newnd.last.name[newnd.last.len]) |
0a7c3937 | 4333 | goto exit5; |
1da177e4 LT |
4334 | } |
4335 | /* source should not be ancestor of target */ | |
4336 | error = -EINVAL; | |
4337 | if (old_dentry == trap) | |
0a7c3937 | 4338 | goto exit5; |
1da177e4 | 4339 | /* target should not be an ancestor of source */ |
da1ce067 MS |
4340 | if (!(flags & RENAME_EXCHANGE)) |
4341 | error = -ENOTEMPTY; | |
1da177e4 LT |
4342 | if (new_dentry == trap) |
4343 | goto exit5; | |
4344 | ||
be6d3e56 | 4345 | error = security_path_rename(&oldnd.path, old_dentry, |
0b3974eb | 4346 | &newnd.path, new_dentry, flags); |
be6d3e56 | 4347 | if (error) |
c30dabfe | 4348 | goto exit5; |
1da177e4 | 4349 | error = vfs_rename(old_dir->d_inode, old_dentry, |
520c8b16 MS |
4350 | new_dir->d_inode, new_dentry, |
4351 | &delegated_inode, flags); | |
1da177e4 LT |
4352 | exit5: |
4353 | dput(new_dentry); | |
4354 | exit4: | |
4355 | dput(old_dentry); | |
4356 | exit3: | |
4357 | unlock_rename(new_dir, old_dir); | |
8e6d782c BF |
4358 | if (delegated_inode) { |
4359 | error = break_deleg_wait(&delegated_inode); | |
4360 | if (!error) | |
4361 | goto retry_deleg; | |
4362 | } | |
c30dabfe | 4363 | mnt_drop_write(oldnd.path.mnt); |
1da177e4 | 4364 | exit2: |
c6a94284 JL |
4365 | if (retry_estale(error, lookup_flags)) |
4366 | should_retry = true; | |
1d957f9b | 4367 | path_put(&newnd.path); |
2ad94ae6 | 4368 | putname(to); |
1da177e4 | 4369 | exit1: |
1d957f9b | 4370 | path_put(&oldnd.path); |
1da177e4 | 4371 | putname(from); |
c6a94284 JL |
4372 | if (should_retry) { |
4373 | should_retry = false; | |
4374 | lookup_flags |= LOOKUP_REVAL; | |
4375 | goto retry; | |
4376 | } | |
2ad94ae6 | 4377 | exit: |
1da177e4 LT |
4378 | return error; |
4379 | } | |
4380 | ||
520c8b16 MS |
4381 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
4382 | int, newdfd, const char __user *, newname) | |
4383 | { | |
4384 | return sys_renameat2(olddfd, oldname, newdfd, newname, 0); | |
4385 | } | |
4386 | ||
a26eab24 | 4387 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 4388 | { |
520c8b16 | 4389 | return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
4390 | } |
4391 | ||
787fb6bc MS |
4392 | int vfs_whiteout(struct inode *dir, struct dentry *dentry) |
4393 | { | |
4394 | int error = may_create(dir, dentry); | |
4395 | if (error) | |
4396 | return error; | |
4397 | ||
4398 | if (!dir->i_op->mknod) | |
4399 | return -EPERM; | |
4400 | ||
4401 | return dir->i_op->mknod(dir, dentry, | |
4402 | S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); | |
4403 | } | |
4404 | EXPORT_SYMBOL(vfs_whiteout); | |
4405 | ||
5d826c84 | 4406 | int readlink_copy(char __user *buffer, int buflen, const char *link) |
1da177e4 | 4407 | { |
5d826c84 | 4408 | int len = PTR_ERR(link); |
1da177e4 LT |
4409 | if (IS_ERR(link)) |
4410 | goto out; | |
4411 | ||
4412 | len = strlen(link); | |
4413 | if (len > (unsigned) buflen) | |
4414 | len = buflen; | |
4415 | if (copy_to_user(buffer, link, len)) | |
4416 | len = -EFAULT; | |
4417 | out: | |
4418 | return len; | |
4419 | } | |
5d826c84 | 4420 | EXPORT_SYMBOL(readlink_copy); |
1da177e4 LT |
4421 | |
4422 | /* | |
4423 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
4424 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
4425 | * using) it for any given inode is up to filesystem. | |
4426 | */ | |
4427 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4428 | { | |
4429 | struct nameidata nd; | |
cc314eef | 4430 | void *cookie; |
694a1764 | 4431 | int res; |
cc314eef | 4432 | |
1da177e4 | 4433 | nd.depth = 0; |
cc314eef | 4434 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
694a1764 MS |
4435 | if (IS_ERR(cookie)) |
4436 | return PTR_ERR(cookie); | |
4437 | ||
5d826c84 | 4438 | res = readlink_copy(buffer, buflen, nd_get_link(&nd)); |
694a1764 MS |
4439 | if (dentry->d_inode->i_op->put_link) |
4440 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); | |
4441 | return res; | |
1da177e4 | 4442 | } |
4d359507 | 4443 | EXPORT_SYMBOL(generic_readlink); |
1da177e4 | 4444 | |
1da177e4 LT |
4445 | /* get the link contents into pagecache */ |
4446 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
4447 | { | |
ebd09abb DG |
4448 | char *kaddr; |
4449 | struct page *page; | |
1da177e4 | 4450 | struct address_space *mapping = dentry->d_inode->i_mapping; |
090d2b18 | 4451 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 4452 | if (IS_ERR(page)) |
6fe6900e | 4453 | return (char*)page; |
1da177e4 | 4454 | *ppage = page; |
ebd09abb DG |
4455 | kaddr = kmap(page); |
4456 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); | |
4457 | return kaddr; | |
1da177e4 LT |
4458 | } |
4459 | ||
4460 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4461 | { | |
4462 | struct page *page = NULL; | |
5d826c84 | 4463 | int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); |
1da177e4 LT |
4464 | if (page) { |
4465 | kunmap(page); | |
4466 | page_cache_release(page); | |
4467 | } | |
4468 | return res; | |
4469 | } | |
4d359507 | 4470 | EXPORT_SYMBOL(page_readlink); |
1da177e4 | 4471 | |
cc314eef | 4472 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 4473 | { |
cc314eef | 4474 | struct page *page = NULL; |
1da177e4 | 4475 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 4476 | return page; |
1da177e4 | 4477 | } |
4d359507 | 4478 | EXPORT_SYMBOL(page_follow_link_light); |
1da177e4 | 4479 | |
cc314eef | 4480 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 4481 | { |
cc314eef LT |
4482 | struct page *page = cookie; |
4483 | ||
4484 | if (page) { | |
1da177e4 LT |
4485 | kunmap(page); |
4486 | page_cache_release(page); | |
1da177e4 LT |
4487 | } |
4488 | } | |
4d359507 | 4489 | EXPORT_SYMBOL(page_put_link); |
1da177e4 | 4490 | |
54566b2c NP |
4491 | /* |
4492 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
4493 | */ | |
4494 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
4495 | { |
4496 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 4497 | struct page *page; |
afddba49 | 4498 | void *fsdata; |
beb497ab | 4499 | int err; |
1da177e4 | 4500 | char *kaddr; |
54566b2c NP |
4501 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
4502 | if (nofs) | |
4503 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 4504 | |
7e53cac4 | 4505 | retry: |
afddba49 | 4506 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 4507 | flags, &page, &fsdata); |
1da177e4 | 4508 | if (err) |
afddba49 NP |
4509 | goto fail; |
4510 | ||
e8e3c3d6 | 4511 | kaddr = kmap_atomic(page); |
1da177e4 | 4512 | memcpy(kaddr, symname, len-1); |
e8e3c3d6 | 4513 | kunmap_atomic(kaddr); |
afddba49 NP |
4514 | |
4515 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
4516 | page, fsdata); | |
1da177e4 LT |
4517 | if (err < 0) |
4518 | goto fail; | |
afddba49 NP |
4519 | if (err < len-1) |
4520 | goto retry; | |
4521 | ||
1da177e4 LT |
4522 | mark_inode_dirty(inode); |
4523 | return 0; | |
1da177e4 LT |
4524 | fail: |
4525 | return err; | |
4526 | } | |
4d359507 | 4527 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 | 4528 | |
0adb25d2 KK |
4529 | int page_symlink(struct inode *inode, const char *symname, int len) |
4530 | { | |
4531 | return __page_symlink(inode, symname, len, | |
54566b2c | 4532 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
0adb25d2 | 4533 | } |
4d359507 | 4534 | EXPORT_SYMBOL(page_symlink); |
0adb25d2 | 4535 | |
92e1d5be | 4536 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
4537 | .readlink = generic_readlink, |
4538 | .follow_link = page_follow_link_light, | |
4539 | .put_link = page_put_link, | |
4540 | }; | |
1da177e4 | 4541 | EXPORT_SYMBOL(page_symlink_inode_operations); |