Commit | Line | Data |
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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> |
1da177e4 LT |
37 | #include <asm/uaccess.h> |
38 | ||
e81e3f4d | 39 | #include "internal.h" |
c7105365 | 40 | #include "mount.h" |
e81e3f4d | 41 | |
1da177e4 LT |
42 | /* [Feb-1997 T. Schoebel-Theuer] |
43 | * Fundamental changes in the pathname lookup mechanisms (namei) | |
44 | * were necessary because of omirr. The reason is that omirr needs | |
45 | * to know the _real_ pathname, not the user-supplied one, in case | |
46 | * of symlinks (and also when transname replacements occur). | |
47 | * | |
48 | * The new code replaces the old recursive symlink resolution with | |
49 | * an iterative one (in case of non-nested symlink chains). It does | |
50 | * this with calls to <fs>_follow_link(). | |
51 | * As a side effect, dir_namei(), _namei() and follow_link() are now | |
52 | * replaced with a single function lookup_dentry() that can handle all | |
53 | * the special cases of the former code. | |
54 | * | |
55 | * With the new dcache, the pathname is stored at each inode, at least as | |
56 | * long as the refcount of the inode is positive. As a side effect, the | |
57 | * size of the dcache depends on the inode cache and thus is dynamic. | |
58 | * | |
59 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink | |
60 | * resolution to correspond with current state of the code. | |
61 | * | |
62 | * Note that the symlink resolution is not *completely* iterative. | |
63 | * There is still a significant amount of tail- and mid- recursion in | |
64 | * the algorithm. Also, note that <fs>_readlink() is not used in | |
65 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() | |
66 | * may return different results than <fs>_follow_link(). Many virtual | |
67 | * filesystems (including /proc) exhibit this behavior. | |
68 | */ | |
69 | ||
70 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: | |
71 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL | |
72 | * and the name already exists in form of a symlink, try to create the new | |
73 | * name indicated by the symlink. The old code always complained that the | |
74 | * name already exists, due to not following the symlink even if its target | |
75 | * is nonexistent. The new semantics affects also mknod() and link() when | |
25985edc | 76 | * the name is a symlink pointing to a non-existent name. |
1da177e4 LT |
77 | * |
78 | * I don't know which semantics is the right one, since I have no access | |
79 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" | |
80 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the | |
81 | * "old" one. Personally, I think the new semantics is much more logical. | |
82 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing | |
83 | * file does succeed in both HP-UX and SunOs, but not in Solaris | |
84 | * and in the old Linux semantics. | |
85 | */ | |
86 | ||
87 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink | |
88 | * semantics. See the comments in "open_namei" and "do_link" below. | |
89 | * | |
90 | * [10-Sep-98 Alan Modra] Another symlink change. | |
91 | */ | |
92 | ||
93 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: | |
94 | * inside the path - always follow. | |
95 | * in the last component in creation/removal/renaming - never follow. | |
96 | * if LOOKUP_FOLLOW passed - follow. | |
97 | * if the pathname has trailing slashes - follow. | |
98 | * otherwise - don't follow. | |
99 | * (applied in that order). | |
100 | * | |
101 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT | |
102 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. | |
103 | * During the 2.4 we need to fix the userland stuff depending on it - | |
104 | * hopefully we will be able to get rid of that wart in 2.5. So far only | |
105 | * XEmacs seems to be relying on it... | |
106 | */ | |
107 | /* | |
108 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) | |
a11f3a05 | 109 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
1da177e4 LT |
110 | * any extra contention... |
111 | */ | |
112 | ||
113 | /* In order to reduce some races, while at the same time doing additional | |
114 | * checking and hopefully speeding things up, we copy filenames to the | |
115 | * kernel data space before using them.. | |
116 | * | |
117 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). | |
118 | * PATH_MAX includes the nul terminator --RR. | |
119 | */ | |
91a27b2a | 120 | void final_putname(struct filename *name) |
1da177e4 | 121 | { |
7950e385 JL |
122 | if (name->separate) { |
123 | __putname(name->name); | |
124 | kfree(name); | |
125 | } else { | |
126 | __putname(name); | |
127 | } | |
91a27b2a JL |
128 | } |
129 | ||
7950e385 JL |
130 | #define EMBEDDED_NAME_MAX (PATH_MAX - sizeof(struct filename)) |
131 | ||
91a27b2a JL |
132 | static struct filename * |
133 | getname_flags(const char __user *filename, int flags, int *empty) | |
134 | { | |
135 | struct filename *result, *err; | |
3f9f0aa6 | 136 | int len; |
7950e385 JL |
137 | long max; |
138 | char *kname; | |
4043cde8 | 139 | |
7ac86265 JL |
140 | result = audit_reusename(filename); |
141 | if (result) | |
142 | return result; | |
143 | ||
7950e385 | 144 | result = __getname(); |
3f9f0aa6 | 145 | if (unlikely(!result)) |
4043cde8 EP |
146 | return ERR_PTR(-ENOMEM); |
147 | ||
7950e385 JL |
148 | /* |
149 | * First, try to embed the struct filename inside the names_cache | |
150 | * allocation | |
151 | */ | |
152 | kname = (char *)result + sizeof(*result); | |
91a27b2a | 153 | result->name = kname; |
7950e385 JL |
154 | result->separate = false; |
155 | max = EMBEDDED_NAME_MAX; | |
156 | ||
157 | recopy: | |
158 | len = strncpy_from_user(kname, filename, max); | |
91a27b2a JL |
159 | if (unlikely(len < 0)) { |
160 | err = ERR_PTR(len); | |
3f9f0aa6 | 161 | goto error; |
91a27b2a | 162 | } |
3f9f0aa6 | 163 | |
7950e385 JL |
164 | /* |
165 | * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a | |
166 | * separate struct filename so we can dedicate the entire | |
167 | * names_cache allocation for the pathname, and re-do the copy from | |
168 | * userland. | |
169 | */ | |
170 | if (len == EMBEDDED_NAME_MAX && max == EMBEDDED_NAME_MAX) { | |
171 | kname = (char *)result; | |
172 | ||
173 | result = kzalloc(sizeof(*result), GFP_KERNEL); | |
174 | if (!result) { | |
175 | err = ERR_PTR(-ENOMEM); | |
176 | result = (struct filename *)kname; | |
177 | goto error; | |
178 | } | |
179 | result->name = kname; | |
180 | result->separate = true; | |
181 | max = PATH_MAX; | |
182 | goto recopy; | |
183 | } | |
184 | ||
3f9f0aa6 LT |
185 | /* The empty path is special. */ |
186 | if (unlikely(!len)) { | |
187 | if (empty) | |
4043cde8 | 188 | *empty = 1; |
3f9f0aa6 LT |
189 | err = ERR_PTR(-ENOENT); |
190 | if (!(flags & LOOKUP_EMPTY)) | |
191 | goto error; | |
1da177e4 | 192 | } |
3f9f0aa6 LT |
193 | |
194 | err = ERR_PTR(-ENAMETOOLONG); | |
7950e385 JL |
195 | if (unlikely(len >= PATH_MAX)) |
196 | goto error; | |
197 | ||
198 | result->uptr = filename; | |
199 | audit_getname(result); | |
200 | return result; | |
3f9f0aa6 LT |
201 | |
202 | error: | |
7950e385 | 203 | final_putname(result); |
3f9f0aa6 | 204 | return err; |
1da177e4 LT |
205 | } |
206 | ||
91a27b2a JL |
207 | struct filename * |
208 | getname(const char __user * filename) | |
f52e0c11 | 209 | { |
f7493e5d | 210 | return getname_flags(filename, 0, NULL); |
f52e0c11 | 211 | } |
91a27b2a | 212 | EXPORT_SYMBOL(getname); |
f52e0c11 | 213 | |
1da177e4 | 214 | #ifdef CONFIG_AUDITSYSCALL |
91a27b2a | 215 | void putname(struct filename *name) |
1da177e4 | 216 | { |
5ac3a9c2 | 217 | if (unlikely(!audit_dummy_context())) |
91a27b2a JL |
218 | return audit_putname(name); |
219 | final_putname(name); | |
1da177e4 | 220 | } |
1da177e4 LT |
221 | #endif |
222 | ||
e77819e5 LT |
223 | static int check_acl(struct inode *inode, int mask) |
224 | { | |
84635d68 | 225 | #ifdef CONFIG_FS_POSIX_ACL |
e77819e5 LT |
226 | struct posix_acl *acl; |
227 | ||
e77819e5 | 228 | if (mask & MAY_NOT_BLOCK) { |
3567866b AV |
229 | acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); |
230 | if (!acl) | |
e77819e5 | 231 | return -EAGAIN; |
3567866b AV |
232 | /* no ->get_acl() calls in RCU mode... */ |
233 | if (acl == ACL_NOT_CACHED) | |
234 | return -ECHILD; | |
206b1d09 | 235 | return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); |
e77819e5 LT |
236 | } |
237 | ||
238 | acl = get_cached_acl(inode, ACL_TYPE_ACCESS); | |
239 | ||
240 | /* | |
4e34e719 CH |
241 | * A filesystem can force a ACL callback by just never filling the |
242 | * ACL cache. But normally you'd fill the cache either at inode | |
243 | * instantiation time, or on the first ->get_acl call. | |
e77819e5 | 244 | * |
4e34e719 CH |
245 | * If the filesystem doesn't have a get_acl() function at all, we'll |
246 | * just create the negative cache entry. | |
e77819e5 LT |
247 | */ |
248 | if (acl == ACL_NOT_CACHED) { | |
4e34e719 CH |
249 | if (inode->i_op->get_acl) { |
250 | acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS); | |
251 | if (IS_ERR(acl)) | |
252 | return PTR_ERR(acl); | |
253 | } else { | |
254 | set_cached_acl(inode, ACL_TYPE_ACCESS, NULL); | |
255 | return -EAGAIN; | |
256 | } | |
e77819e5 LT |
257 | } |
258 | ||
259 | if (acl) { | |
260 | int error = posix_acl_permission(inode, acl, mask); | |
261 | posix_acl_release(acl); | |
262 | return error; | |
263 | } | |
84635d68 | 264 | #endif |
e77819e5 LT |
265 | |
266 | return -EAGAIN; | |
267 | } | |
268 | ||
5909ccaa | 269 | /* |
948409c7 | 270 | * This does the basic permission checking |
1da177e4 | 271 | */ |
7e40145e | 272 | static int acl_permission_check(struct inode *inode, int mask) |
1da177e4 | 273 | { |
26cf46be | 274 | unsigned int mode = inode->i_mode; |
1da177e4 | 275 | |
8e96e3b7 | 276 | if (likely(uid_eq(current_fsuid(), inode->i_uid))) |
1da177e4 LT |
277 | mode >>= 6; |
278 | else { | |
e77819e5 | 279 | if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { |
7e40145e | 280 | int error = check_acl(inode, mask); |
b74c79e9 NP |
281 | if (error != -EAGAIN) |
282 | return error; | |
1da177e4 LT |
283 | } |
284 | ||
285 | if (in_group_p(inode->i_gid)) | |
286 | mode >>= 3; | |
287 | } | |
288 | ||
289 | /* | |
290 | * If the DACs are ok we don't need any capability check. | |
291 | */ | |
9c2c7039 | 292 | if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) |
1da177e4 | 293 | return 0; |
5909ccaa LT |
294 | return -EACCES; |
295 | } | |
296 | ||
297 | /** | |
b74c79e9 | 298 | * generic_permission - check for access rights on a Posix-like filesystem |
5909ccaa | 299 | * @inode: inode to check access rights for |
8fd90c8d | 300 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) |
5909ccaa LT |
301 | * |
302 | * Used to check for read/write/execute permissions on a file. | |
303 | * We use "fsuid" for this, letting us set arbitrary permissions | |
304 | * for filesystem access without changing the "normal" uids which | |
b74c79e9 NP |
305 | * are used for other things. |
306 | * | |
307 | * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk | |
308 | * request cannot be satisfied (eg. requires blocking or too much complexity). | |
309 | * It would then be called again in ref-walk mode. | |
5909ccaa | 310 | */ |
2830ba7f | 311 | int generic_permission(struct inode *inode, int mask) |
5909ccaa LT |
312 | { |
313 | int ret; | |
314 | ||
315 | /* | |
948409c7 | 316 | * Do the basic permission checks. |
5909ccaa | 317 | */ |
7e40145e | 318 | ret = acl_permission_check(inode, mask); |
5909ccaa LT |
319 | if (ret != -EACCES) |
320 | return ret; | |
1da177e4 | 321 | |
d594e7ec AV |
322 | if (S_ISDIR(inode->i_mode)) { |
323 | /* DACs are overridable for directories */ | |
1a48e2ac | 324 | if (inode_capable(inode, CAP_DAC_OVERRIDE)) |
d594e7ec AV |
325 | return 0; |
326 | if (!(mask & MAY_WRITE)) | |
1a48e2ac | 327 | if (inode_capable(inode, CAP_DAC_READ_SEARCH)) |
d594e7ec AV |
328 | return 0; |
329 | return -EACCES; | |
330 | } | |
1da177e4 LT |
331 | /* |
332 | * Read/write DACs are always overridable. | |
d594e7ec AV |
333 | * Executable DACs are overridable when there is |
334 | * at least one exec bit set. | |
1da177e4 | 335 | */ |
d594e7ec | 336 | if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) |
1a48e2ac | 337 | if (inode_capable(inode, CAP_DAC_OVERRIDE)) |
1da177e4 LT |
338 | return 0; |
339 | ||
340 | /* | |
341 | * Searching includes executable on directories, else just read. | |
342 | */ | |
7ea66001 | 343 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
d594e7ec | 344 | if (mask == MAY_READ) |
1a48e2ac | 345 | if (inode_capable(inode, CAP_DAC_READ_SEARCH)) |
1da177e4 LT |
346 | return 0; |
347 | ||
348 | return -EACCES; | |
349 | } | |
350 | ||
3ddcd056 LT |
351 | /* |
352 | * We _really_ want to just do "generic_permission()" without | |
353 | * even looking at the inode->i_op values. So we keep a cache | |
354 | * flag in inode->i_opflags, that says "this has not special | |
355 | * permission function, use the fast case". | |
356 | */ | |
357 | static inline int do_inode_permission(struct inode *inode, int mask) | |
358 | { | |
359 | if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { | |
360 | if (likely(inode->i_op->permission)) | |
361 | return inode->i_op->permission(inode, mask); | |
362 | ||
363 | /* This gets set once for the inode lifetime */ | |
364 | spin_lock(&inode->i_lock); | |
365 | inode->i_opflags |= IOP_FASTPERM; | |
366 | spin_unlock(&inode->i_lock); | |
367 | } | |
368 | return generic_permission(inode, mask); | |
369 | } | |
370 | ||
cb23beb5 | 371 | /** |
0bdaea90 DH |
372 | * __inode_permission - Check for access rights to a given inode |
373 | * @inode: Inode to check permission on | |
374 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
cb23beb5 | 375 | * |
0bdaea90 | 376 | * Check for read/write/execute permissions on an inode. |
948409c7 AG |
377 | * |
378 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
0bdaea90 DH |
379 | * |
380 | * This does not check for a read-only file system. You probably want | |
381 | * inode_permission(). | |
cb23beb5 | 382 | */ |
0bdaea90 | 383 | int __inode_permission(struct inode *inode, int mask) |
1da177e4 | 384 | { |
e6305c43 | 385 | int retval; |
1da177e4 | 386 | |
3ddcd056 | 387 | if (unlikely(mask & MAY_WRITE)) { |
1da177e4 LT |
388 | /* |
389 | * Nobody gets write access to an immutable file. | |
390 | */ | |
391 | if (IS_IMMUTABLE(inode)) | |
392 | return -EACCES; | |
393 | } | |
394 | ||
3ddcd056 | 395 | retval = do_inode_permission(inode, mask); |
1da177e4 LT |
396 | if (retval) |
397 | return retval; | |
398 | ||
08ce5f16 SH |
399 | retval = devcgroup_inode_permission(inode, mask); |
400 | if (retval) | |
401 | return retval; | |
402 | ||
d09ca739 | 403 | return security_inode_permission(inode, mask); |
1da177e4 LT |
404 | } |
405 | ||
0bdaea90 DH |
406 | /** |
407 | * sb_permission - Check superblock-level permissions | |
408 | * @sb: Superblock of inode to check permission on | |
55852635 | 409 | * @inode: Inode to check permission on |
0bdaea90 DH |
410 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
411 | * | |
412 | * Separate out file-system wide checks from inode-specific permission checks. | |
413 | */ | |
414 | static int sb_permission(struct super_block *sb, struct inode *inode, int mask) | |
415 | { | |
416 | if (unlikely(mask & MAY_WRITE)) { | |
417 | umode_t mode = inode->i_mode; | |
418 | ||
419 | /* Nobody gets write access to a read-only fs. */ | |
420 | if ((sb->s_flags & MS_RDONLY) && | |
421 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
422 | return -EROFS; | |
423 | } | |
424 | return 0; | |
425 | } | |
426 | ||
427 | /** | |
428 | * inode_permission - Check for access rights to a given inode | |
429 | * @inode: Inode to check permission on | |
430 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
431 | * | |
432 | * Check for read/write/execute permissions on an inode. We use fs[ug]id for | |
433 | * this, letting us set arbitrary permissions for filesystem access without | |
434 | * changing the "normal" UIDs which are used for other things. | |
435 | * | |
436 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
437 | */ | |
438 | int inode_permission(struct inode *inode, int mask) | |
439 | { | |
440 | int retval; | |
441 | ||
442 | retval = sb_permission(inode->i_sb, inode, mask); | |
443 | if (retval) | |
444 | return retval; | |
445 | return __inode_permission(inode, mask); | |
446 | } | |
447 | ||
5dd784d0 JB |
448 | /** |
449 | * path_get - get a reference to a path | |
450 | * @path: path to get the reference to | |
451 | * | |
452 | * Given a path increment the reference count to the dentry and the vfsmount. | |
453 | */ | |
dcf787f3 | 454 | void path_get(const struct path *path) |
5dd784d0 JB |
455 | { |
456 | mntget(path->mnt); | |
457 | dget(path->dentry); | |
458 | } | |
459 | EXPORT_SYMBOL(path_get); | |
460 | ||
1d957f9b JB |
461 | /** |
462 | * path_put - put a reference to a path | |
463 | * @path: path to put the reference to | |
464 | * | |
465 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
466 | */ | |
dcf787f3 | 467 | void path_put(const struct path *path) |
1da177e4 | 468 | { |
1d957f9b JB |
469 | dput(path->dentry); |
470 | mntput(path->mnt); | |
1da177e4 | 471 | } |
1d957f9b | 472 | EXPORT_SYMBOL(path_put); |
1da177e4 | 473 | |
19660af7 | 474 | /* |
31e6b01f | 475 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
19660af7 AV |
476 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
477 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab | |
478 | * normal reference counts on dentries and vfsmounts to transition to rcu-walk | |
479 | * mode. Refcounts are grabbed at the last known good point before rcu-walk | |
480 | * got stuck, so ref-walk may continue from there. If this is not successful | |
481 | * (eg. a seqcount has changed), then failure is returned and it's up to caller | |
482 | * to restart the path walk from the beginning in ref-walk mode. | |
31e6b01f | 483 | */ |
31e6b01f | 484 | |
32a7991b AV |
485 | static inline void lock_rcu_walk(void) |
486 | { | |
487 | br_read_lock(&vfsmount_lock); | |
488 | rcu_read_lock(); | |
489 | } | |
490 | ||
491 | static inline void unlock_rcu_walk(void) | |
492 | { | |
493 | rcu_read_unlock(); | |
494 | br_read_unlock(&vfsmount_lock); | |
495 | } | |
496 | ||
15570086 LT |
497 | /* |
498 | * When we move over from the RCU domain to properly refcounted | |
499 | * long-lived dentries, we need to check the sequence numbers | |
500 | * we got before lookup very carefully. | |
501 | * | |
502 | * We cannot blindly increment a dentry refcount - even if it | |
503 | * is not locked - if it is zero, because it may have gone | |
504 | * through the final d_kill() logic already. | |
505 | * | |
506 | * So for a zero refcount, we need to get the spinlock (which is | |
507 | * safe even for a dead dentry because the de-allocation is | |
508 | * RCU-delayed), and check the sequence count under the lock. | |
509 | * | |
510 | * Once we have checked the sequence count, we know it is live, | |
511 | * and since we hold the spinlock it cannot die from under us. | |
512 | * | |
513 | * In contrast, if the reference count wasn't zero, we can just | |
514 | * increment the lockref without having to take the spinlock. | |
515 | * Even if the sequence number ends up being stale, we haven't | |
516 | * gone through the final dput() and killed the dentry yet. | |
517 | */ | |
518 | static inline int d_rcu_to_refcount(struct dentry *dentry, seqcount_t *validate, unsigned seq) | |
519 | { | |
520 | int gotref; | |
521 | ||
522 | gotref = lockref_get_or_lock(&dentry->d_lockref); | |
523 | ||
524 | /* Does the sequence number still match? */ | |
525 | if (read_seqcount_retry(validate, seq)) { | |
526 | if (gotref) | |
527 | dput(dentry); | |
528 | else | |
529 | spin_unlock(&dentry->d_lock); | |
530 | return -ECHILD; | |
531 | } | |
532 | ||
533 | /* Get the ref now, if we couldn't get it originally */ | |
534 | if (!gotref) { | |
535 | dentry->d_lockref.count++; | |
536 | spin_unlock(&dentry->d_lock); | |
537 | } | |
538 | return 0; | |
539 | } | |
540 | ||
31e6b01f | 541 | /** |
19660af7 AV |
542 | * unlazy_walk - try to switch to ref-walk mode. |
543 | * @nd: nameidata pathwalk data | |
544 | * @dentry: child of nd->path.dentry or NULL | |
39191628 | 545 | * Returns: 0 on success, -ECHILD on failure |
31e6b01f | 546 | * |
19660af7 AV |
547 | * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry |
548 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on | |
549 | * @nd or NULL. Must be called from rcu-walk context. | |
31e6b01f | 550 | */ |
19660af7 | 551 | static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) |
31e6b01f NP |
552 | { |
553 | struct fs_struct *fs = current->fs; | |
554 | struct dentry *parent = nd->path.dentry; | |
5b6ca027 | 555 | int want_root = 0; |
31e6b01f NP |
556 | |
557 | BUG_ON(!(nd->flags & LOOKUP_RCU)); | |
5b6ca027 AV |
558 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
559 | want_root = 1; | |
31e6b01f NP |
560 | spin_lock(&fs->lock); |
561 | if (nd->root.mnt != fs->root.mnt || | |
562 | nd->root.dentry != fs->root.dentry) | |
563 | goto err_root; | |
564 | } | |
15570086 LT |
565 | |
566 | /* | |
567 | * For a negative lookup, the lookup sequence point is the parents | |
568 | * sequence point, and it only needs to revalidate the parent dentry. | |
569 | * | |
570 | * For a positive lookup, we need to move both the parent and the | |
571 | * dentry from the RCU domain to be properly refcounted. And the | |
572 | * sequence number in the dentry validates *both* dentry counters, | |
573 | * since we checked the sequence number of the parent after we got | |
574 | * the child sequence number. So we know the parent must still | |
575 | * be valid if the child sequence number is still valid. | |
576 | */ | |
19660af7 | 577 | if (!dentry) { |
15570086 LT |
578 | if (d_rcu_to_refcount(parent, &parent->d_seq, nd->seq) < 0) |
579 | goto err_root; | |
19660af7 AV |
580 | BUG_ON(nd->inode != parent->d_inode); |
581 | } else { | |
15570086 LT |
582 | if (d_rcu_to_refcount(dentry, &dentry->d_seq, nd->seq) < 0) |
583 | goto err_root; | |
584 | if (d_rcu_to_refcount(parent, &dentry->d_seq, nd->seq) < 0) | |
94c0d4ec | 585 | goto err_parent; |
19660af7 | 586 | } |
5b6ca027 | 587 | if (want_root) { |
31e6b01f NP |
588 | path_get(&nd->root); |
589 | spin_unlock(&fs->lock); | |
590 | } | |
591 | mntget(nd->path.mnt); | |
592 | ||
32a7991b | 593 | unlock_rcu_walk(); |
31e6b01f NP |
594 | nd->flags &= ~LOOKUP_RCU; |
595 | return 0; | |
19660af7 | 596 | |
19660af7 | 597 | err_parent: |
15570086 | 598 | dput(dentry); |
31e6b01f | 599 | err_root: |
5b6ca027 | 600 | if (want_root) |
31e6b01f NP |
601 | spin_unlock(&fs->lock); |
602 | return -ECHILD; | |
603 | } | |
604 | ||
4ce16ef3 | 605 | static inline int d_revalidate(struct dentry *dentry, unsigned int flags) |
34286d66 | 606 | { |
4ce16ef3 | 607 | return dentry->d_op->d_revalidate(dentry, flags); |
34286d66 NP |
608 | } |
609 | ||
9f1fafee AV |
610 | /** |
611 | * complete_walk - successful completion of path walk | |
612 | * @nd: pointer nameidata | |
39159de2 | 613 | * |
9f1fafee AV |
614 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
615 | * Revalidate the final result, unless we'd already done that during | |
616 | * the path walk or the filesystem doesn't ask for it. Return 0 on | |
617 | * success, -error on failure. In case of failure caller does not | |
618 | * need to drop nd->path. | |
39159de2 | 619 | */ |
9f1fafee | 620 | static int complete_walk(struct nameidata *nd) |
39159de2 | 621 | { |
16c2cd71 | 622 | struct dentry *dentry = nd->path.dentry; |
39159de2 | 623 | int status; |
39159de2 | 624 | |
9f1fafee AV |
625 | if (nd->flags & LOOKUP_RCU) { |
626 | nd->flags &= ~LOOKUP_RCU; | |
627 | if (!(nd->flags & LOOKUP_ROOT)) | |
628 | nd->root.mnt = NULL; | |
15570086 LT |
629 | |
630 | if (d_rcu_to_refcount(dentry, &dentry->d_seq, nd->seq) < 0) { | |
32a7991b | 631 | unlock_rcu_walk(); |
9f1fafee AV |
632 | return -ECHILD; |
633 | } | |
9f1fafee | 634 | mntget(nd->path.mnt); |
32a7991b | 635 | unlock_rcu_walk(); |
9f1fafee AV |
636 | } |
637 | ||
16c2cd71 AV |
638 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
639 | return 0; | |
640 | ||
ecf3d1f1 | 641 | if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) |
39159de2 JL |
642 | return 0; |
643 | ||
ecf3d1f1 | 644 | status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); |
39159de2 JL |
645 | if (status > 0) |
646 | return 0; | |
647 | ||
16c2cd71 | 648 | if (!status) |
39159de2 | 649 | status = -ESTALE; |
16c2cd71 | 650 | |
9f1fafee | 651 | path_put(&nd->path); |
39159de2 JL |
652 | return status; |
653 | } | |
654 | ||
2a737871 AV |
655 | static __always_inline void set_root(struct nameidata *nd) |
656 | { | |
f7ad3c6b MS |
657 | if (!nd->root.mnt) |
658 | get_fs_root(current->fs, &nd->root); | |
2a737871 AV |
659 | } |
660 | ||
6de88d72 AV |
661 | static int link_path_walk(const char *, struct nameidata *); |
662 | ||
31e6b01f NP |
663 | static __always_inline void set_root_rcu(struct nameidata *nd) |
664 | { | |
665 | if (!nd->root.mnt) { | |
666 | struct fs_struct *fs = current->fs; | |
c28cc364 NP |
667 | unsigned seq; |
668 | ||
669 | do { | |
670 | seq = read_seqcount_begin(&fs->seq); | |
671 | nd->root = fs->root; | |
c1530019 | 672 | nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); |
c28cc364 | 673 | } while (read_seqcount_retry(&fs->seq, seq)); |
31e6b01f NP |
674 | } |
675 | } | |
676 | ||
f1662356 | 677 | static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
1da177e4 | 678 | { |
31e6b01f NP |
679 | int ret; |
680 | ||
1da177e4 LT |
681 | if (IS_ERR(link)) |
682 | goto fail; | |
683 | ||
684 | if (*link == '/') { | |
2a737871 | 685 | set_root(nd); |
1d957f9b | 686 | path_put(&nd->path); |
2a737871 AV |
687 | nd->path = nd->root; |
688 | path_get(&nd->root); | |
16c2cd71 | 689 | nd->flags |= LOOKUP_JUMPED; |
1da177e4 | 690 | } |
31e6b01f | 691 | nd->inode = nd->path.dentry->d_inode; |
b4091d5f | 692 | |
31e6b01f NP |
693 | ret = link_path_walk(link, nd); |
694 | return ret; | |
1da177e4 | 695 | fail: |
1d957f9b | 696 | path_put(&nd->path); |
1da177e4 LT |
697 | return PTR_ERR(link); |
698 | } | |
699 | ||
1d957f9b | 700 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
701 | { |
702 | dput(path->dentry); | |
4ac91378 | 703 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
704 | mntput(path->mnt); |
705 | } | |
706 | ||
7b9337aa NP |
707 | static inline void path_to_nameidata(const struct path *path, |
708 | struct nameidata *nd) | |
051d3812 | 709 | { |
31e6b01f NP |
710 | if (!(nd->flags & LOOKUP_RCU)) { |
711 | dput(nd->path.dentry); | |
712 | if (nd->path.mnt != path->mnt) | |
713 | mntput(nd->path.mnt); | |
9a229683 | 714 | } |
31e6b01f | 715 | nd->path.mnt = path->mnt; |
4ac91378 | 716 | nd->path.dentry = path->dentry; |
051d3812 IK |
717 | } |
718 | ||
b5fb63c1 CH |
719 | /* |
720 | * Helper to directly jump to a known parsed path from ->follow_link, | |
721 | * caller must have taken a reference to path beforehand. | |
722 | */ | |
723 | void nd_jump_link(struct nameidata *nd, struct path *path) | |
724 | { | |
725 | path_put(&nd->path); | |
726 | ||
727 | nd->path = *path; | |
728 | nd->inode = nd->path.dentry->d_inode; | |
729 | nd->flags |= LOOKUP_JUMPED; | |
b5fb63c1 CH |
730 | } |
731 | ||
574197e0 AV |
732 | static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) |
733 | { | |
734 | struct inode *inode = link->dentry->d_inode; | |
6d7b5aae | 735 | if (inode->i_op->put_link) |
574197e0 AV |
736 | inode->i_op->put_link(link->dentry, nd, cookie); |
737 | path_put(link); | |
738 | } | |
739 | ||
561ec64a LT |
740 | int sysctl_protected_symlinks __read_mostly = 0; |
741 | int sysctl_protected_hardlinks __read_mostly = 0; | |
800179c9 KC |
742 | |
743 | /** | |
744 | * may_follow_link - Check symlink following for unsafe situations | |
745 | * @link: The path of the symlink | |
55852635 | 746 | * @nd: nameidata pathwalk data |
800179c9 KC |
747 | * |
748 | * In the case of the sysctl_protected_symlinks sysctl being enabled, | |
749 | * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is | |
750 | * in a sticky world-writable directory. This is to protect privileged | |
751 | * processes from failing races against path names that may change out | |
752 | * from under them by way of other users creating malicious symlinks. | |
753 | * It will permit symlinks to be followed only when outside a sticky | |
754 | * world-writable directory, or when the uid of the symlink and follower | |
755 | * match, or when the directory owner matches the symlink's owner. | |
756 | * | |
757 | * Returns 0 if following the symlink is allowed, -ve on error. | |
758 | */ | |
759 | static inline int may_follow_link(struct path *link, struct nameidata *nd) | |
760 | { | |
761 | const struct inode *inode; | |
762 | const struct inode *parent; | |
763 | ||
764 | if (!sysctl_protected_symlinks) | |
765 | return 0; | |
766 | ||
767 | /* Allowed if owner and follower match. */ | |
768 | inode = link->dentry->d_inode; | |
81abe27b | 769 | if (uid_eq(current_cred()->fsuid, inode->i_uid)) |
800179c9 KC |
770 | return 0; |
771 | ||
772 | /* Allowed if parent directory not sticky and world-writable. */ | |
773 | parent = nd->path.dentry->d_inode; | |
774 | if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) | |
775 | return 0; | |
776 | ||
777 | /* Allowed if parent directory and link owner match. */ | |
81abe27b | 778 | if (uid_eq(parent->i_uid, inode->i_uid)) |
800179c9 KC |
779 | return 0; |
780 | ||
ffd8d101 | 781 | audit_log_link_denied("follow_link", link); |
800179c9 KC |
782 | path_put_conditional(link, nd); |
783 | path_put(&nd->path); | |
784 | return -EACCES; | |
785 | } | |
786 | ||
787 | /** | |
788 | * safe_hardlink_source - Check for safe hardlink conditions | |
789 | * @inode: the source inode to hardlink from | |
790 | * | |
791 | * Return false if at least one of the following conditions: | |
792 | * - inode is not a regular file | |
793 | * - inode is setuid | |
794 | * - inode is setgid and group-exec | |
795 | * - access failure for read and write | |
796 | * | |
797 | * Otherwise returns true. | |
798 | */ | |
799 | static bool safe_hardlink_source(struct inode *inode) | |
800 | { | |
801 | umode_t mode = inode->i_mode; | |
802 | ||
803 | /* Special files should not get pinned to the filesystem. */ | |
804 | if (!S_ISREG(mode)) | |
805 | return false; | |
806 | ||
807 | /* Setuid files should not get pinned to the filesystem. */ | |
808 | if (mode & S_ISUID) | |
809 | return false; | |
810 | ||
811 | /* Executable setgid files should not get pinned to the filesystem. */ | |
812 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) | |
813 | return false; | |
814 | ||
815 | /* Hardlinking to unreadable or unwritable sources is dangerous. */ | |
816 | if (inode_permission(inode, MAY_READ | MAY_WRITE)) | |
817 | return false; | |
818 | ||
819 | return true; | |
820 | } | |
821 | ||
822 | /** | |
823 | * may_linkat - Check permissions for creating a hardlink | |
824 | * @link: the source to hardlink from | |
825 | * | |
826 | * Block hardlink when all of: | |
827 | * - sysctl_protected_hardlinks enabled | |
828 | * - fsuid does not match inode | |
829 | * - hardlink source is unsafe (see safe_hardlink_source() above) | |
830 | * - not CAP_FOWNER | |
831 | * | |
832 | * Returns 0 if successful, -ve on error. | |
833 | */ | |
834 | static int may_linkat(struct path *link) | |
835 | { | |
836 | const struct cred *cred; | |
837 | struct inode *inode; | |
838 | ||
839 | if (!sysctl_protected_hardlinks) | |
840 | return 0; | |
841 | ||
842 | cred = current_cred(); | |
843 | inode = link->dentry->d_inode; | |
844 | ||
845 | /* Source inode owner (or CAP_FOWNER) can hardlink all they like, | |
846 | * otherwise, it must be a safe source. | |
847 | */ | |
81abe27b | 848 | if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || |
800179c9 KC |
849 | capable(CAP_FOWNER)) |
850 | return 0; | |
851 | ||
a51d9eaa | 852 | audit_log_link_denied("linkat", link); |
800179c9 KC |
853 | return -EPERM; |
854 | } | |
855 | ||
def4af30 | 856 | static __always_inline int |
574197e0 | 857 | follow_link(struct path *link, struct nameidata *nd, void **p) |
1da177e4 | 858 | { |
7b9337aa | 859 | struct dentry *dentry = link->dentry; |
6d7b5aae AV |
860 | int error; |
861 | char *s; | |
1da177e4 | 862 | |
844a3917 AV |
863 | BUG_ON(nd->flags & LOOKUP_RCU); |
864 | ||
0e794589 AV |
865 | if (link->mnt == nd->path.mnt) |
866 | mntget(link->mnt); | |
867 | ||
6d7b5aae AV |
868 | error = -ELOOP; |
869 | if (unlikely(current->total_link_count >= 40)) | |
870 | goto out_put_nd_path; | |
871 | ||
574197e0 AV |
872 | cond_resched(); |
873 | current->total_link_count++; | |
874 | ||
68ac1234 | 875 | touch_atime(link); |
1da177e4 | 876 | nd_set_link(nd, NULL); |
cd4e91d3 | 877 | |
36f3b4f6 | 878 | error = security_inode_follow_link(link->dentry, nd); |
6d7b5aae AV |
879 | if (error) |
880 | goto out_put_nd_path; | |
36f3b4f6 | 881 | |
86acdca1 | 882 | nd->last_type = LAST_BIND; |
def4af30 AV |
883 | *p = dentry->d_inode->i_op->follow_link(dentry, nd); |
884 | error = PTR_ERR(*p); | |
6d7b5aae | 885 | if (IS_ERR(*p)) |
408ef013 | 886 | goto out_put_nd_path; |
6d7b5aae AV |
887 | |
888 | error = 0; | |
889 | s = nd_get_link(nd); | |
890 | if (s) { | |
891 | error = __vfs_follow_link(nd, s); | |
b5fb63c1 CH |
892 | if (unlikely(error)) |
893 | put_link(nd, link, *p); | |
1da177e4 | 894 | } |
6d7b5aae AV |
895 | |
896 | return error; | |
897 | ||
898 | out_put_nd_path: | |
98f6ef64 | 899 | *p = NULL; |
6d7b5aae | 900 | path_put(&nd->path); |
6d7b5aae | 901 | path_put(link); |
1da177e4 LT |
902 | return error; |
903 | } | |
904 | ||
31e6b01f NP |
905 | static int follow_up_rcu(struct path *path) |
906 | { | |
0714a533 AV |
907 | struct mount *mnt = real_mount(path->mnt); |
908 | struct mount *parent; | |
31e6b01f NP |
909 | struct dentry *mountpoint; |
910 | ||
0714a533 AV |
911 | parent = mnt->mnt_parent; |
912 | if (&parent->mnt == path->mnt) | |
31e6b01f | 913 | return 0; |
a73324da | 914 | mountpoint = mnt->mnt_mountpoint; |
31e6b01f | 915 | path->dentry = mountpoint; |
0714a533 | 916 | path->mnt = &parent->mnt; |
31e6b01f NP |
917 | return 1; |
918 | } | |
919 | ||
f015f126 DH |
920 | /* |
921 | * follow_up - Find the mountpoint of path's vfsmount | |
922 | * | |
923 | * Given a path, find the mountpoint of its source file system. | |
924 | * Replace @path with the path of the mountpoint in the parent mount. | |
925 | * Up is towards /. | |
926 | * | |
927 | * Return 1 if we went up a level and 0 if we were already at the | |
928 | * root. | |
929 | */ | |
bab77ebf | 930 | int follow_up(struct path *path) |
1da177e4 | 931 | { |
0714a533 AV |
932 | struct mount *mnt = real_mount(path->mnt); |
933 | struct mount *parent; | |
1da177e4 | 934 | struct dentry *mountpoint; |
99b7db7b | 935 | |
962830df | 936 | br_read_lock(&vfsmount_lock); |
0714a533 | 937 | parent = mnt->mnt_parent; |
3c0a6163 | 938 | if (parent == mnt) { |
962830df | 939 | br_read_unlock(&vfsmount_lock); |
1da177e4 LT |
940 | return 0; |
941 | } | |
0714a533 | 942 | mntget(&parent->mnt); |
a73324da | 943 | mountpoint = dget(mnt->mnt_mountpoint); |
962830df | 944 | br_read_unlock(&vfsmount_lock); |
bab77ebf AV |
945 | dput(path->dentry); |
946 | path->dentry = mountpoint; | |
947 | mntput(path->mnt); | |
0714a533 | 948 | path->mnt = &parent->mnt; |
1da177e4 LT |
949 | return 1; |
950 | } | |
951 | ||
b5c84bf6 | 952 | /* |
9875cf80 DH |
953 | * Perform an automount |
954 | * - return -EISDIR to tell follow_managed() to stop and return the path we | |
955 | * were called with. | |
1da177e4 | 956 | */ |
9875cf80 DH |
957 | static int follow_automount(struct path *path, unsigned flags, |
958 | bool *need_mntput) | |
31e6b01f | 959 | { |
9875cf80 | 960 | struct vfsmount *mnt; |
ea5b778a | 961 | int err; |
9875cf80 DH |
962 | |
963 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) | |
964 | return -EREMOTE; | |
965 | ||
0ec26fd0 MS |
966 | /* We don't want to mount if someone's just doing a stat - |
967 | * unless they're stat'ing a directory and appended a '/' to | |
968 | * the name. | |
969 | * | |
970 | * We do, however, want to mount if someone wants to open or | |
971 | * create a file of any type under the mountpoint, wants to | |
972 | * traverse through the mountpoint or wants to open the | |
973 | * mounted directory. Also, autofs may mark negative dentries | |
974 | * as being automount points. These will need the attentions | |
975 | * of the daemon to instantiate them before they can be used. | |
9875cf80 | 976 | */ |
0ec26fd0 | 977 | if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
d94c177b | 978 | LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && |
0ec26fd0 MS |
979 | path->dentry->d_inode) |
980 | return -EISDIR; | |
981 | ||
9875cf80 DH |
982 | current->total_link_count++; |
983 | if (current->total_link_count >= 40) | |
984 | return -ELOOP; | |
985 | ||
986 | mnt = path->dentry->d_op->d_automount(path); | |
987 | if (IS_ERR(mnt)) { | |
988 | /* | |
989 | * The filesystem is allowed to return -EISDIR here to indicate | |
990 | * it doesn't want to automount. For instance, autofs would do | |
991 | * this so that its userspace daemon can mount on this dentry. | |
992 | * | |
993 | * However, we can only permit this if it's a terminal point in | |
994 | * the path being looked up; if it wasn't then the remainder of | |
995 | * the path is inaccessible and we should say so. | |
996 | */ | |
49084c3b | 997 | if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) |
9875cf80 DH |
998 | return -EREMOTE; |
999 | return PTR_ERR(mnt); | |
31e6b01f | 1000 | } |
ea5b778a | 1001 | |
9875cf80 DH |
1002 | if (!mnt) /* mount collision */ |
1003 | return 0; | |
31e6b01f | 1004 | |
8aef1884 AV |
1005 | if (!*need_mntput) { |
1006 | /* lock_mount() may release path->mnt on error */ | |
1007 | mntget(path->mnt); | |
1008 | *need_mntput = true; | |
1009 | } | |
19a167af | 1010 | err = finish_automount(mnt, path); |
9875cf80 | 1011 | |
ea5b778a DH |
1012 | switch (err) { |
1013 | case -EBUSY: | |
1014 | /* Someone else made a mount here whilst we were busy */ | |
19a167af | 1015 | return 0; |
ea5b778a | 1016 | case 0: |
8aef1884 | 1017 | path_put(path); |
ea5b778a DH |
1018 | path->mnt = mnt; |
1019 | path->dentry = dget(mnt->mnt_root); | |
ea5b778a | 1020 | return 0; |
19a167af AV |
1021 | default: |
1022 | return err; | |
ea5b778a | 1023 | } |
19a167af | 1024 | |
463ffb2e AV |
1025 | } |
1026 | ||
9875cf80 DH |
1027 | /* |
1028 | * Handle a dentry that is managed in some way. | |
cc53ce53 | 1029 | * - Flagged for transit management (autofs) |
9875cf80 DH |
1030 | * - Flagged as mountpoint |
1031 | * - Flagged as automount point | |
1032 | * | |
1033 | * This may only be called in refwalk mode. | |
1034 | * | |
1035 | * Serialization is taken care of in namespace.c | |
1036 | */ | |
1037 | static int follow_managed(struct path *path, unsigned flags) | |
1da177e4 | 1038 | { |
8aef1884 | 1039 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
9875cf80 DH |
1040 | unsigned managed; |
1041 | bool need_mntput = false; | |
8aef1884 | 1042 | int ret = 0; |
9875cf80 DH |
1043 | |
1044 | /* Given that we're not holding a lock here, we retain the value in a | |
1045 | * local variable for each dentry as we look at it so that we don't see | |
1046 | * the components of that value change under us */ | |
1047 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1048 | managed &= DCACHE_MANAGED_DENTRY, | |
1049 | unlikely(managed != 0)) { | |
cc53ce53 DH |
1050 | /* Allow the filesystem to manage the transit without i_mutex |
1051 | * being held. */ | |
1052 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1053 | BUG_ON(!path->dentry->d_op); | |
1054 | BUG_ON(!path->dentry->d_op->d_manage); | |
1aed3e42 | 1055 | ret = path->dentry->d_op->d_manage(path->dentry, false); |
cc53ce53 | 1056 | if (ret < 0) |
8aef1884 | 1057 | break; |
cc53ce53 DH |
1058 | } |
1059 | ||
9875cf80 DH |
1060 | /* Transit to a mounted filesystem. */ |
1061 | if (managed & DCACHE_MOUNTED) { | |
1062 | struct vfsmount *mounted = lookup_mnt(path); | |
1063 | if (mounted) { | |
1064 | dput(path->dentry); | |
1065 | if (need_mntput) | |
1066 | mntput(path->mnt); | |
1067 | path->mnt = mounted; | |
1068 | path->dentry = dget(mounted->mnt_root); | |
1069 | need_mntput = true; | |
1070 | continue; | |
1071 | } | |
1072 | ||
1073 | /* Something is mounted on this dentry in another | |
1074 | * namespace and/or whatever was mounted there in this | |
1075 | * namespace got unmounted before we managed to get the | |
1076 | * vfsmount_lock */ | |
1077 | } | |
1078 | ||
1079 | /* Handle an automount point */ | |
1080 | if (managed & DCACHE_NEED_AUTOMOUNT) { | |
1081 | ret = follow_automount(path, flags, &need_mntput); | |
1082 | if (ret < 0) | |
8aef1884 | 1083 | break; |
9875cf80 DH |
1084 | continue; |
1085 | } | |
1086 | ||
1087 | /* We didn't change the current path point */ | |
1088 | break; | |
1da177e4 | 1089 | } |
8aef1884 AV |
1090 | |
1091 | if (need_mntput && path->mnt == mnt) | |
1092 | mntput(path->mnt); | |
1093 | if (ret == -EISDIR) | |
1094 | ret = 0; | |
a3fbbde7 | 1095 | return ret < 0 ? ret : need_mntput; |
1da177e4 LT |
1096 | } |
1097 | ||
cc53ce53 | 1098 | int follow_down_one(struct path *path) |
1da177e4 LT |
1099 | { |
1100 | struct vfsmount *mounted; | |
1101 | ||
1c755af4 | 1102 | mounted = lookup_mnt(path); |
1da177e4 | 1103 | if (mounted) { |
9393bd07 AV |
1104 | dput(path->dentry); |
1105 | mntput(path->mnt); | |
1106 | path->mnt = mounted; | |
1107 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
1108 | return 1; |
1109 | } | |
1110 | return 0; | |
1111 | } | |
1112 | ||
62a7375e IK |
1113 | static inline bool managed_dentry_might_block(struct dentry *dentry) |
1114 | { | |
1115 | return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && | |
1116 | dentry->d_op->d_manage(dentry, true) < 0); | |
1117 | } | |
1118 | ||
9875cf80 | 1119 | /* |
287548e4 AV |
1120 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
1121 | * we meet a managed dentry that would need blocking. | |
9875cf80 DH |
1122 | */ |
1123 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, | |
287548e4 | 1124 | struct inode **inode) |
9875cf80 | 1125 | { |
62a7375e | 1126 | for (;;) { |
c7105365 | 1127 | struct mount *mounted; |
62a7375e IK |
1128 | /* |
1129 | * Don't forget we might have a non-mountpoint managed dentry | |
1130 | * that wants to block transit. | |
1131 | */ | |
287548e4 | 1132 | if (unlikely(managed_dentry_might_block(path->dentry))) |
ab90911f | 1133 | return false; |
62a7375e IK |
1134 | |
1135 | if (!d_mountpoint(path->dentry)) | |
1136 | break; | |
1137 | ||
9875cf80 DH |
1138 | mounted = __lookup_mnt(path->mnt, path->dentry, 1); |
1139 | if (!mounted) | |
1140 | break; | |
c7105365 AV |
1141 | path->mnt = &mounted->mnt; |
1142 | path->dentry = mounted->mnt.mnt_root; | |
a3fbbde7 | 1143 | nd->flags |= LOOKUP_JUMPED; |
9875cf80 | 1144 | nd->seq = read_seqcount_begin(&path->dentry->d_seq); |
59430262 LT |
1145 | /* |
1146 | * Update the inode too. We don't need to re-check the | |
1147 | * dentry sequence number here after this d_inode read, | |
1148 | * because a mount-point is always pinned. | |
1149 | */ | |
1150 | *inode = path->dentry->d_inode; | |
9875cf80 | 1151 | } |
9875cf80 DH |
1152 | return true; |
1153 | } | |
1154 | ||
dea39376 | 1155 | static void follow_mount_rcu(struct nameidata *nd) |
287548e4 | 1156 | { |
dea39376 | 1157 | while (d_mountpoint(nd->path.dentry)) { |
c7105365 | 1158 | struct mount *mounted; |
dea39376 | 1159 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); |
287548e4 AV |
1160 | if (!mounted) |
1161 | break; | |
c7105365 AV |
1162 | nd->path.mnt = &mounted->mnt; |
1163 | nd->path.dentry = mounted->mnt.mnt_root; | |
dea39376 | 1164 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); |
287548e4 AV |
1165 | } |
1166 | } | |
1167 | ||
31e6b01f NP |
1168 | static int follow_dotdot_rcu(struct nameidata *nd) |
1169 | { | |
31e6b01f NP |
1170 | set_root_rcu(nd); |
1171 | ||
9875cf80 | 1172 | while (1) { |
31e6b01f NP |
1173 | if (nd->path.dentry == nd->root.dentry && |
1174 | nd->path.mnt == nd->root.mnt) { | |
1175 | break; | |
1176 | } | |
1177 | if (nd->path.dentry != nd->path.mnt->mnt_root) { | |
1178 | struct dentry *old = nd->path.dentry; | |
1179 | struct dentry *parent = old->d_parent; | |
1180 | unsigned seq; | |
1181 | ||
1182 | seq = read_seqcount_begin(&parent->d_seq); | |
1183 | if (read_seqcount_retry(&old->d_seq, nd->seq)) | |
ef7562d5 | 1184 | goto failed; |
31e6b01f NP |
1185 | nd->path.dentry = parent; |
1186 | nd->seq = seq; | |
1187 | break; | |
1188 | } | |
1189 | if (!follow_up_rcu(&nd->path)) | |
1190 | break; | |
1191 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
31e6b01f | 1192 | } |
dea39376 AV |
1193 | follow_mount_rcu(nd); |
1194 | nd->inode = nd->path.dentry->d_inode; | |
31e6b01f | 1195 | return 0; |
ef7562d5 AV |
1196 | |
1197 | failed: | |
1198 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1199 | if (!(nd->flags & LOOKUP_ROOT)) |
1200 | nd->root.mnt = NULL; | |
32a7991b | 1201 | unlock_rcu_walk(); |
ef7562d5 | 1202 | return -ECHILD; |
31e6b01f NP |
1203 | } |
1204 | ||
cc53ce53 DH |
1205 | /* |
1206 | * Follow down to the covering mount currently visible to userspace. At each | |
1207 | * point, the filesystem owning that dentry may be queried as to whether the | |
1208 | * caller is permitted to proceed or not. | |
cc53ce53 | 1209 | */ |
7cc90cc3 | 1210 | int follow_down(struct path *path) |
cc53ce53 DH |
1211 | { |
1212 | unsigned managed; | |
1213 | int ret; | |
1214 | ||
1215 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1216 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { | |
1217 | /* Allow the filesystem to manage the transit without i_mutex | |
1218 | * being held. | |
1219 | * | |
1220 | * We indicate to the filesystem if someone is trying to mount | |
1221 | * something here. This gives autofs the chance to deny anyone | |
1222 | * other than its daemon the right to mount on its | |
1223 | * superstructure. | |
1224 | * | |
1225 | * The filesystem may sleep at this point. | |
1226 | */ | |
1227 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1228 | BUG_ON(!path->dentry->d_op); | |
1229 | BUG_ON(!path->dentry->d_op->d_manage); | |
ab90911f | 1230 | ret = path->dentry->d_op->d_manage( |
1aed3e42 | 1231 | path->dentry, false); |
cc53ce53 DH |
1232 | if (ret < 0) |
1233 | return ret == -EISDIR ? 0 : ret; | |
1234 | } | |
1235 | ||
1236 | /* Transit to a mounted filesystem. */ | |
1237 | if (managed & DCACHE_MOUNTED) { | |
1238 | struct vfsmount *mounted = lookup_mnt(path); | |
1239 | if (!mounted) | |
1240 | break; | |
1241 | dput(path->dentry); | |
1242 | mntput(path->mnt); | |
1243 | path->mnt = mounted; | |
1244 | path->dentry = dget(mounted->mnt_root); | |
1245 | continue; | |
1246 | } | |
1247 | ||
1248 | /* Don't handle automount points here */ | |
1249 | break; | |
1250 | } | |
1251 | return 0; | |
1252 | } | |
1253 | ||
9875cf80 DH |
1254 | /* |
1255 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() | |
1256 | */ | |
1257 | static void follow_mount(struct path *path) | |
1258 | { | |
1259 | while (d_mountpoint(path->dentry)) { | |
1260 | struct vfsmount *mounted = lookup_mnt(path); | |
1261 | if (!mounted) | |
1262 | break; | |
1263 | dput(path->dentry); | |
1264 | mntput(path->mnt); | |
1265 | path->mnt = mounted; | |
1266 | path->dentry = dget(mounted->mnt_root); | |
1267 | } | |
1268 | } | |
1269 | ||
31e6b01f | 1270 | static void follow_dotdot(struct nameidata *nd) |
1da177e4 | 1271 | { |
2a737871 | 1272 | set_root(nd); |
e518ddb7 | 1273 | |
1da177e4 | 1274 | while(1) { |
4ac91378 | 1275 | struct dentry *old = nd->path.dentry; |
1da177e4 | 1276 | |
2a737871 AV |
1277 | if (nd->path.dentry == nd->root.dentry && |
1278 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
1279 | break; |
1280 | } | |
4ac91378 | 1281 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
3088dd70 AV |
1282 | /* rare case of legitimate dget_parent()... */ |
1283 | nd->path.dentry = dget_parent(nd->path.dentry); | |
1da177e4 LT |
1284 | dput(old); |
1285 | break; | |
1286 | } | |
3088dd70 | 1287 | if (!follow_up(&nd->path)) |
1da177e4 | 1288 | break; |
1da177e4 | 1289 | } |
79ed0226 | 1290 | follow_mount(&nd->path); |
31e6b01f | 1291 | nd->inode = nd->path.dentry->d_inode; |
1da177e4 LT |
1292 | } |
1293 | ||
baa03890 | 1294 | /* |
bad61189 MS |
1295 | * This looks up the name in dcache, possibly revalidates the old dentry and |
1296 | * allocates a new one if not found or not valid. In the need_lookup argument | |
1297 | * returns whether i_op->lookup is necessary. | |
1298 | * | |
1299 | * dir->d_inode->i_mutex must be held | |
baa03890 | 1300 | */ |
bad61189 | 1301 | static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, |
201f956e | 1302 | unsigned int flags, bool *need_lookup) |
baa03890 | 1303 | { |
baa03890 | 1304 | struct dentry *dentry; |
bad61189 | 1305 | int error; |
baa03890 | 1306 | |
bad61189 MS |
1307 | *need_lookup = false; |
1308 | dentry = d_lookup(dir, name); | |
1309 | if (dentry) { | |
39e3c955 | 1310 | if (dentry->d_flags & DCACHE_OP_REVALIDATE) { |
201f956e | 1311 | error = d_revalidate(dentry, flags); |
bad61189 MS |
1312 | if (unlikely(error <= 0)) { |
1313 | if (error < 0) { | |
1314 | dput(dentry); | |
1315 | return ERR_PTR(error); | |
1316 | } else if (!d_invalidate(dentry)) { | |
1317 | dput(dentry); | |
1318 | dentry = NULL; | |
1319 | } | |
1320 | } | |
1321 | } | |
1322 | } | |
baa03890 | 1323 | |
bad61189 MS |
1324 | if (!dentry) { |
1325 | dentry = d_alloc(dir, name); | |
1326 | if (unlikely(!dentry)) | |
1327 | return ERR_PTR(-ENOMEM); | |
baa03890 | 1328 | |
bad61189 | 1329 | *need_lookup = true; |
baa03890 NP |
1330 | } |
1331 | return dentry; | |
1332 | } | |
1333 | ||
44396f4b | 1334 | /* |
bad61189 MS |
1335 | * Call i_op->lookup on the dentry. The dentry must be negative but may be |
1336 | * hashed if it was pouplated with DCACHE_NEED_LOOKUP. | |
1337 | * | |
1338 | * dir->d_inode->i_mutex must be held | |
44396f4b | 1339 | */ |
bad61189 | 1340 | static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, |
72bd866a | 1341 | unsigned int flags) |
44396f4b | 1342 | { |
44396f4b JB |
1343 | struct dentry *old; |
1344 | ||
1345 | /* Don't create child dentry for a dead directory. */ | |
bad61189 | 1346 | if (unlikely(IS_DEADDIR(dir))) { |
e188dc02 | 1347 | dput(dentry); |
44396f4b | 1348 | return ERR_PTR(-ENOENT); |
e188dc02 | 1349 | } |
44396f4b | 1350 | |
72bd866a | 1351 | old = dir->i_op->lookup(dir, dentry, flags); |
44396f4b JB |
1352 | if (unlikely(old)) { |
1353 | dput(dentry); | |
1354 | dentry = old; | |
1355 | } | |
1356 | return dentry; | |
1357 | } | |
1358 | ||
a3255546 | 1359 | static struct dentry *__lookup_hash(struct qstr *name, |
72bd866a | 1360 | struct dentry *base, unsigned int flags) |
a3255546 | 1361 | { |
bad61189 | 1362 | bool need_lookup; |
a3255546 AV |
1363 | struct dentry *dentry; |
1364 | ||
72bd866a | 1365 | dentry = lookup_dcache(name, base, flags, &need_lookup); |
bad61189 MS |
1366 | if (!need_lookup) |
1367 | return dentry; | |
a3255546 | 1368 | |
72bd866a | 1369 | return lookup_real(base->d_inode, dentry, flags); |
a3255546 AV |
1370 | } |
1371 | ||
1da177e4 LT |
1372 | /* |
1373 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
1374 | * small and for now I'd prefer to have fast path as straight as possible. | |
1375 | * It _is_ time-critical. | |
1376 | */ | |
e97cdc87 | 1377 | static int lookup_fast(struct nameidata *nd, |
697f514d | 1378 | struct path *path, struct inode **inode) |
1da177e4 | 1379 | { |
4ac91378 | 1380 | struct vfsmount *mnt = nd->path.mnt; |
31e6b01f | 1381 | struct dentry *dentry, *parent = nd->path.dentry; |
5a18fff2 AV |
1382 | int need_reval = 1; |
1383 | int status = 1; | |
9875cf80 DH |
1384 | int err; |
1385 | ||
b04f784e NP |
1386 | /* |
1387 | * Rename seqlock is not required here because in the off chance | |
1388 | * of a false negative due to a concurrent rename, we're going to | |
1389 | * do the non-racy lookup, below. | |
1390 | */ | |
31e6b01f NP |
1391 | if (nd->flags & LOOKUP_RCU) { |
1392 | unsigned seq; | |
da53be12 | 1393 | dentry = __d_lookup_rcu(parent, &nd->last, &seq); |
5a18fff2 AV |
1394 | if (!dentry) |
1395 | goto unlazy; | |
1396 | ||
12f8ad4b LT |
1397 | /* |
1398 | * This sequence count validates that the inode matches | |
1399 | * the dentry name information from lookup. | |
1400 | */ | |
1401 | *inode = dentry->d_inode; | |
1402 | if (read_seqcount_retry(&dentry->d_seq, seq)) | |
1403 | return -ECHILD; | |
1404 | ||
1405 | /* | |
1406 | * This sequence count validates that the parent had no | |
1407 | * changes while we did the lookup of the dentry above. | |
1408 | * | |
1409 | * The memory barrier in read_seqcount_begin of child is | |
1410 | * enough, we can use __read_seqcount_retry here. | |
1411 | */ | |
31e6b01f NP |
1412 | if (__read_seqcount_retry(&parent->d_seq, nd->seq)) |
1413 | return -ECHILD; | |
31e6b01f | 1414 | nd->seq = seq; |
5a18fff2 | 1415 | |
24643087 | 1416 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
4ce16ef3 | 1417 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1418 | if (unlikely(status <= 0)) { |
1419 | if (status != -ECHILD) | |
1420 | need_reval = 0; | |
1421 | goto unlazy; | |
1422 | } | |
24643087 | 1423 | } |
31e6b01f NP |
1424 | path->mnt = mnt; |
1425 | path->dentry = dentry; | |
d6e9bd25 AV |
1426 | if (unlikely(!__follow_mount_rcu(nd, path, inode))) |
1427 | goto unlazy; | |
1428 | if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) | |
1429 | goto unlazy; | |
1430 | return 0; | |
5a18fff2 | 1431 | unlazy: |
19660af7 AV |
1432 | if (unlazy_walk(nd, dentry)) |
1433 | return -ECHILD; | |
5a18fff2 | 1434 | } else { |
e97cdc87 | 1435 | dentry = __d_lookup(parent, &nd->last); |
9875cf80 | 1436 | } |
5a18fff2 | 1437 | |
81e6f520 AV |
1438 | if (unlikely(!dentry)) |
1439 | goto need_lookup; | |
1440 | ||
5a18fff2 | 1441 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) |
4ce16ef3 | 1442 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1443 | if (unlikely(status <= 0)) { |
1444 | if (status < 0) { | |
1445 | dput(dentry); | |
1446 | return status; | |
1447 | } | |
1448 | if (!d_invalidate(dentry)) { | |
1449 | dput(dentry); | |
81e6f520 | 1450 | goto need_lookup; |
5a18fff2 | 1451 | } |
24643087 | 1452 | } |
697f514d | 1453 | |
9875cf80 DH |
1454 | path->mnt = mnt; |
1455 | path->dentry = dentry; | |
1456 | err = follow_managed(path, nd->flags); | |
89312214 IK |
1457 | if (unlikely(err < 0)) { |
1458 | path_put_conditional(path, nd); | |
9875cf80 | 1459 | return err; |
89312214 | 1460 | } |
a3fbbde7 AV |
1461 | if (err) |
1462 | nd->flags |= LOOKUP_JUMPED; | |
9875cf80 | 1463 | *inode = path->dentry->d_inode; |
1da177e4 | 1464 | return 0; |
81e6f520 AV |
1465 | |
1466 | need_lookup: | |
697f514d MS |
1467 | return 1; |
1468 | } | |
1469 | ||
1470 | /* Fast lookup failed, do it the slow way */ | |
cc2a5271 | 1471 | static int lookup_slow(struct nameidata *nd, struct path *path) |
697f514d MS |
1472 | { |
1473 | struct dentry *dentry, *parent; | |
1474 | int err; | |
1475 | ||
1476 | parent = nd->path.dentry; | |
81e6f520 AV |
1477 | BUG_ON(nd->inode != parent->d_inode); |
1478 | ||
1479 | mutex_lock(&parent->d_inode->i_mutex); | |
cc2a5271 | 1480 | dentry = __lookup_hash(&nd->last, parent, nd->flags); |
81e6f520 AV |
1481 | mutex_unlock(&parent->d_inode->i_mutex); |
1482 | if (IS_ERR(dentry)) | |
1483 | return PTR_ERR(dentry); | |
697f514d MS |
1484 | path->mnt = nd->path.mnt; |
1485 | path->dentry = dentry; | |
1486 | err = follow_managed(path, nd->flags); | |
1487 | if (unlikely(err < 0)) { | |
1488 | path_put_conditional(path, nd); | |
1489 | return err; | |
1490 | } | |
1491 | if (err) | |
1492 | nd->flags |= LOOKUP_JUMPED; | |
1493 | return 0; | |
1da177e4 LT |
1494 | } |
1495 | ||
52094c8a AV |
1496 | static inline int may_lookup(struct nameidata *nd) |
1497 | { | |
1498 | if (nd->flags & LOOKUP_RCU) { | |
4ad5abb3 | 1499 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
52094c8a AV |
1500 | if (err != -ECHILD) |
1501 | return err; | |
19660af7 | 1502 | if (unlazy_walk(nd, NULL)) |
52094c8a AV |
1503 | return -ECHILD; |
1504 | } | |
4ad5abb3 | 1505 | return inode_permission(nd->inode, MAY_EXEC); |
52094c8a AV |
1506 | } |
1507 | ||
9856fa1b AV |
1508 | static inline int handle_dots(struct nameidata *nd, int type) |
1509 | { | |
1510 | if (type == LAST_DOTDOT) { | |
1511 | if (nd->flags & LOOKUP_RCU) { | |
1512 | if (follow_dotdot_rcu(nd)) | |
1513 | return -ECHILD; | |
1514 | } else | |
1515 | follow_dotdot(nd); | |
1516 | } | |
1517 | return 0; | |
1518 | } | |
1519 | ||
951361f9 AV |
1520 | static void terminate_walk(struct nameidata *nd) |
1521 | { | |
1522 | if (!(nd->flags & LOOKUP_RCU)) { | |
1523 | path_put(&nd->path); | |
1524 | } else { | |
1525 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1526 | if (!(nd->flags & LOOKUP_ROOT)) |
1527 | nd->root.mnt = NULL; | |
32a7991b | 1528 | unlock_rcu_walk(); |
951361f9 AV |
1529 | } |
1530 | } | |
1531 | ||
3ddcd056 LT |
1532 | /* |
1533 | * Do we need to follow links? We _really_ want to be able | |
1534 | * to do this check without having to look at inode->i_op, | |
1535 | * so we keep a cache of "no, this doesn't need follow_link" | |
1536 | * for the common case. | |
1537 | */ | |
7813b94a | 1538 | static inline int should_follow_link(struct inode *inode, int follow) |
3ddcd056 LT |
1539 | { |
1540 | if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { | |
1541 | if (likely(inode->i_op->follow_link)) | |
1542 | return follow; | |
1543 | ||
1544 | /* This gets set once for the inode lifetime */ | |
1545 | spin_lock(&inode->i_lock); | |
1546 | inode->i_opflags |= IOP_NOFOLLOW; | |
1547 | spin_unlock(&inode->i_lock); | |
1548 | } | |
1549 | return 0; | |
1550 | } | |
1551 | ||
ce57dfc1 | 1552 | static inline int walk_component(struct nameidata *nd, struct path *path, |
21b9b073 | 1553 | int follow) |
ce57dfc1 AV |
1554 | { |
1555 | struct inode *inode; | |
1556 | int err; | |
1557 | /* | |
1558 | * "." and ".." are special - ".." especially so because it has | |
1559 | * to be able to know about the current root directory and | |
1560 | * parent relationships. | |
1561 | */ | |
21b9b073 AV |
1562 | if (unlikely(nd->last_type != LAST_NORM)) |
1563 | return handle_dots(nd, nd->last_type); | |
e97cdc87 | 1564 | err = lookup_fast(nd, path, &inode); |
ce57dfc1 | 1565 | if (unlikely(err)) { |
697f514d MS |
1566 | if (err < 0) |
1567 | goto out_err; | |
1568 | ||
cc2a5271 | 1569 | err = lookup_slow(nd, path); |
697f514d MS |
1570 | if (err < 0) |
1571 | goto out_err; | |
1572 | ||
1573 | inode = path->dentry->d_inode; | |
ce57dfc1 | 1574 | } |
697f514d MS |
1575 | err = -ENOENT; |
1576 | if (!inode) | |
1577 | goto out_path_put; | |
1578 | ||
7813b94a | 1579 | if (should_follow_link(inode, follow)) { |
19660af7 AV |
1580 | if (nd->flags & LOOKUP_RCU) { |
1581 | if (unlikely(unlazy_walk(nd, path->dentry))) { | |
697f514d MS |
1582 | err = -ECHILD; |
1583 | goto out_err; | |
19660af7 AV |
1584 | } |
1585 | } | |
ce57dfc1 AV |
1586 | BUG_ON(inode != path->dentry->d_inode); |
1587 | return 1; | |
1588 | } | |
1589 | path_to_nameidata(path, nd); | |
1590 | nd->inode = inode; | |
1591 | return 0; | |
697f514d MS |
1592 | |
1593 | out_path_put: | |
1594 | path_to_nameidata(path, nd); | |
1595 | out_err: | |
1596 | terminate_walk(nd); | |
1597 | return err; | |
ce57dfc1 AV |
1598 | } |
1599 | ||
b356379a AV |
1600 | /* |
1601 | * This limits recursive symlink follows to 8, while | |
1602 | * limiting consecutive symlinks to 40. | |
1603 | * | |
1604 | * Without that kind of total limit, nasty chains of consecutive | |
1605 | * symlinks can cause almost arbitrarily long lookups. | |
1606 | */ | |
1607 | static inline int nested_symlink(struct path *path, struct nameidata *nd) | |
1608 | { | |
1609 | int res; | |
1610 | ||
b356379a AV |
1611 | if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { |
1612 | path_put_conditional(path, nd); | |
1613 | path_put(&nd->path); | |
1614 | return -ELOOP; | |
1615 | } | |
1a4022f8 | 1616 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); |
b356379a AV |
1617 | |
1618 | nd->depth++; | |
1619 | current->link_count++; | |
1620 | ||
1621 | do { | |
1622 | struct path link = *path; | |
1623 | void *cookie; | |
574197e0 AV |
1624 | |
1625 | res = follow_link(&link, nd, &cookie); | |
6d7b5aae AV |
1626 | if (res) |
1627 | break; | |
21b9b073 | 1628 | res = walk_component(nd, path, LOOKUP_FOLLOW); |
574197e0 | 1629 | put_link(nd, &link, cookie); |
b356379a AV |
1630 | } while (res > 0); |
1631 | ||
1632 | current->link_count--; | |
1633 | nd->depth--; | |
1634 | return res; | |
1635 | } | |
1636 | ||
3ddcd056 LT |
1637 | /* |
1638 | * We really don't want to look at inode->i_op->lookup | |
1639 | * when we don't have to. So we keep a cache bit in | |
1640 | * the inode ->i_opflags field that says "yes, we can | |
1641 | * do lookup on this inode". | |
1642 | */ | |
1643 | static inline int can_lookup(struct inode *inode) | |
1644 | { | |
1645 | if (likely(inode->i_opflags & IOP_LOOKUP)) | |
1646 | return 1; | |
1647 | if (likely(!inode->i_op->lookup)) | |
1648 | return 0; | |
1649 | ||
1650 | /* We do this once for the lifetime of the inode */ | |
1651 | spin_lock(&inode->i_lock); | |
1652 | inode->i_opflags |= IOP_LOOKUP; | |
1653 | spin_unlock(&inode->i_lock); | |
1654 | return 1; | |
1655 | } | |
1656 | ||
bfcfaa77 LT |
1657 | /* |
1658 | * We can do the critical dentry name comparison and hashing | |
1659 | * operations one word at a time, but we are limited to: | |
1660 | * | |
1661 | * - Architectures with fast unaligned word accesses. We could | |
1662 | * do a "get_unaligned()" if this helps and is sufficiently | |
1663 | * fast. | |
1664 | * | |
1665 | * - Little-endian machines (so that we can generate the mask | |
1666 | * of low bytes efficiently). Again, we *could* do a byte | |
1667 | * swapping load on big-endian architectures if that is not | |
1668 | * expensive enough to make the optimization worthless. | |
1669 | * | |
1670 | * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we | |
1671 | * do not trap on the (extremely unlikely) case of a page | |
1672 | * crossing operation. | |
1673 | * | |
1674 | * - Furthermore, we need an efficient 64-bit compile for the | |
1675 | * 64-bit case in order to generate the "number of bytes in | |
1676 | * the final mask". Again, that could be replaced with a | |
1677 | * efficient population count instruction or similar. | |
1678 | */ | |
1679 | #ifdef CONFIG_DCACHE_WORD_ACCESS | |
1680 | ||
f68e556e | 1681 | #include <asm/word-at-a-time.h> |
bfcfaa77 | 1682 | |
f68e556e | 1683 | #ifdef CONFIG_64BIT |
bfcfaa77 LT |
1684 | |
1685 | static inline unsigned int fold_hash(unsigned long hash) | |
1686 | { | |
1687 | hash += hash >> (8*sizeof(int)); | |
1688 | return hash; | |
1689 | } | |
1690 | ||
1691 | #else /* 32-bit case */ | |
1692 | ||
bfcfaa77 LT |
1693 | #define fold_hash(x) (x) |
1694 | ||
1695 | #endif | |
1696 | ||
1697 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) | |
1698 | { | |
1699 | unsigned long a, mask; | |
1700 | unsigned long hash = 0; | |
1701 | ||
1702 | for (;;) { | |
e419b4cc | 1703 | a = load_unaligned_zeropad(name); |
bfcfaa77 LT |
1704 | if (len < sizeof(unsigned long)) |
1705 | break; | |
1706 | hash += a; | |
f132c5be | 1707 | hash *= 9; |
bfcfaa77 LT |
1708 | name += sizeof(unsigned long); |
1709 | len -= sizeof(unsigned long); | |
1710 | if (!len) | |
1711 | goto done; | |
1712 | } | |
1713 | mask = ~(~0ul << len*8); | |
1714 | hash += mask & a; | |
1715 | done: | |
1716 | return fold_hash(hash); | |
1717 | } | |
1718 | EXPORT_SYMBOL(full_name_hash); | |
1719 | ||
bfcfaa77 LT |
1720 | /* |
1721 | * Calculate the length and hash of the path component, and | |
1722 | * return the length of the component; | |
1723 | */ | |
1724 | static inline unsigned long hash_name(const char *name, unsigned int *hashp) | |
1725 | { | |
36126f8f LT |
1726 | unsigned long a, b, adata, bdata, mask, hash, len; |
1727 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; | |
bfcfaa77 LT |
1728 | |
1729 | hash = a = 0; | |
1730 | len = -sizeof(unsigned long); | |
1731 | do { | |
1732 | hash = (hash + a) * 9; | |
1733 | len += sizeof(unsigned long); | |
e419b4cc | 1734 | a = load_unaligned_zeropad(name+len); |
36126f8f LT |
1735 | b = a ^ REPEAT_BYTE('/'); |
1736 | } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); | |
1737 | ||
1738 | adata = prep_zero_mask(a, adata, &constants); | |
1739 | bdata = prep_zero_mask(b, bdata, &constants); | |
1740 | ||
1741 | mask = create_zero_mask(adata | bdata); | |
1742 | ||
1743 | hash += a & zero_bytemask(mask); | |
bfcfaa77 LT |
1744 | *hashp = fold_hash(hash); |
1745 | ||
36126f8f | 1746 | return len + find_zero(mask); |
bfcfaa77 LT |
1747 | } |
1748 | ||
1749 | #else | |
1750 | ||
0145acc2 LT |
1751 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) |
1752 | { | |
1753 | unsigned long hash = init_name_hash(); | |
1754 | while (len--) | |
1755 | hash = partial_name_hash(*name++, hash); | |
1756 | return end_name_hash(hash); | |
1757 | } | |
ae942ae7 | 1758 | EXPORT_SYMBOL(full_name_hash); |
0145acc2 | 1759 | |
200e9ef7 LT |
1760 | /* |
1761 | * We know there's a real path component here of at least | |
1762 | * one character. | |
1763 | */ | |
1764 | static inline unsigned long hash_name(const char *name, unsigned int *hashp) | |
1765 | { | |
1766 | unsigned long hash = init_name_hash(); | |
1767 | unsigned long len = 0, c; | |
1768 | ||
1769 | c = (unsigned char)*name; | |
1770 | do { | |
1771 | len++; | |
1772 | hash = partial_name_hash(c, hash); | |
1773 | c = (unsigned char)name[len]; | |
1774 | } while (c && c != '/'); | |
1775 | *hashp = end_name_hash(hash); | |
1776 | return len; | |
1777 | } | |
1778 | ||
bfcfaa77 LT |
1779 | #endif |
1780 | ||
1da177e4 LT |
1781 | /* |
1782 | * Name resolution. | |
ea3834d9 PM |
1783 | * This is the basic name resolution function, turning a pathname into |
1784 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 1785 | * |
ea3834d9 PM |
1786 | * Returns 0 and nd will have valid dentry and mnt on success. |
1787 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 1788 | */ |
6de88d72 | 1789 | static int link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 LT |
1790 | { |
1791 | struct path next; | |
1da177e4 | 1792 | int err; |
1da177e4 LT |
1793 | |
1794 | while (*name=='/') | |
1795 | name++; | |
1796 | if (!*name) | |
086e183a | 1797 | return 0; |
1da177e4 | 1798 | |
1da177e4 LT |
1799 | /* At this point we know we have a real path component. */ |
1800 | for(;;) { | |
1da177e4 | 1801 | struct qstr this; |
200e9ef7 | 1802 | long len; |
fe479a58 | 1803 | int type; |
1da177e4 | 1804 | |
52094c8a | 1805 | err = may_lookup(nd); |
1da177e4 LT |
1806 | if (err) |
1807 | break; | |
1808 | ||
200e9ef7 | 1809 | len = hash_name(name, &this.hash); |
1da177e4 | 1810 | this.name = name; |
200e9ef7 | 1811 | this.len = len; |
1da177e4 | 1812 | |
fe479a58 | 1813 | type = LAST_NORM; |
200e9ef7 | 1814 | if (name[0] == '.') switch (len) { |
fe479a58 | 1815 | case 2: |
200e9ef7 | 1816 | if (name[1] == '.') { |
fe479a58 | 1817 | type = LAST_DOTDOT; |
16c2cd71 AV |
1818 | nd->flags |= LOOKUP_JUMPED; |
1819 | } | |
fe479a58 AV |
1820 | break; |
1821 | case 1: | |
1822 | type = LAST_DOT; | |
1823 | } | |
5a202bcd AV |
1824 | if (likely(type == LAST_NORM)) { |
1825 | struct dentry *parent = nd->path.dentry; | |
16c2cd71 | 1826 | nd->flags &= ~LOOKUP_JUMPED; |
5a202bcd | 1827 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
da53be12 | 1828 | err = parent->d_op->d_hash(parent, &this); |
5a202bcd AV |
1829 | if (err < 0) |
1830 | break; | |
1831 | } | |
1832 | } | |
fe479a58 | 1833 | |
5f4a6a69 AV |
1834 | nd->last = this; |
1835 | nd->last_type = type; | |
1836 | ||
200e9ef7 | 1837 | if (!name[len]) |
5f4a6a69 | 1838 | return 0; |
200e9ef7 LT |
1839 | /* |
1840 | * If it wasn't NUL, we know it was '/'. Skip that | |
1841 | * slash, and continue until no more slashes. | |
1842 | */ | |
1843 | do { | |
1844 | len++; | |
1845 | } while (unlikely(name[len] == '/')); | |
1846 | if (!name[len]) | |
5f4a6a69 AV |
1847 | return 0; |
1848 | ||
200e9ef7 | 1849 | name += len; |
1da177e4 | 1850 | |
21b9b073 | 1851 | err = walk_component(nd, &next, LOOKUP_FOLLOW); |
ce57dfc1 AV |
1852 | if (err < 0) |
1853 | return err; | |
1da177e4 | 1854 | |
ce57dfc1 | 1855 | if (err) { |
b356379a | 1856 | err = nested_symlink(&next, nd); |
1da177e4 | 1857 | if (err) |
a7472bab | 1858 | return err; |
31e6b01f | 1859 | } |
5f4a6a69 AV |
1860 | if (!can_lookup(nd->inode)) { |
1861 | err = -ENOTDIR; | |
1862 | break; | |
1863 | } | |
1da177e4 | 1864 | } |
951361f9 | 1865 | terminate_walk(nd); |
1da177e4 LT |
1866 | return err; |
1867 | } | |
1868 | ||
70e9b357 AV |
1869 | static int path_init(int dfd, const char *name, unsigned int flags, |
1870 | struct nameidata *nd, struct file **fp) | |
31e6b01f NP |
1871 | { |
1872 | int retval = 0; | |
31e6b01f NP |
1873 | |
1874 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
16c2cd71 | 1875 | nd->flags = flags | LOOKUP_JUMPED; |
31e6b01f | 1876 | nd->depth = 0; |
5b6ca027 AV |
1877 | if (flags & LOOKUP_ROOT) { |
1878 | struct inode *inode = nd->root.dentry->d_inode; | |
73d049a4 | 1879 | if (*name) { |
741b7c3f | 1880 | if (!can_lookup(inode)) |
73d049a4 AV |
1881 | return -ENOTDIR; |
1882 | retval = inode_permission(inode, MAY_EXEC); | |
1883 | if (retval) | |
1884 | return retval; | |
1885 | } | |
5b6ca027 AV |
1886 | nd->path = nd->root; |
1887 | nd->inode = inode; | |
1888 | if (flags & LOOKUP_RCU) { | |
32a7991b | 1889 | lock_rcu_walk(); |
5b6ca027 AV |
1890 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
1891 | } else { | |
1892 | path_get(&nd->path); | |
1893 | } | |
1894 | return 0; | |
1895 | } | |
1896 | ||
31e6b01f | 1897 | nd->root.mnt = NULL; |
31e6b01f NP |
1898 | |
1899 | if (*name=='/') { | |
e41f7d4e | 1900 | if (flags & LOOKUP_RCU) { |
32a7991b | 1901 | lock_rcu_walk(); |
e41f7d4e AV |
1902 | set_root_rcu(nd); |
1903 | } else { | |
1904 | set_root(nd); | |
1905 | path_get(&nd->root); | |
1906 | } | |
1907 | nd->path = nd->root; | |
31e6b01f | 1908 | } else if (dfd == AT_FDCWD) { |
e41f7d4e AV |
1909 | if (flags & LOOKUP_RCU) { |
1910 | struct fs_struct *fs = current->fs; | |
1911 | unsigned seq; | |
31e6b01f | 1912 | |
32a7991b | 1913 | lock_rcu_walk(); |
c28cc364 | 1914 | |
e41f7d4e AV |
1915 | do { |
1916 | seq = read_seqcount_begin(&fs->seq); | |
1917 | nd->path = fs->pwd; | |
1918 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
1919 | } while (read_seqcount_retry(&fs->seq, seq)); | |
1920 | } else { | |
1921 | get_fs_pwd(current->fs, &nd->path); | |
1922 | } | |
31e6b01f | 1923 | } else { |
582aa64a | 1924 | /* Caller must check execute permissions on the starting path component */ |
2903ff01 | 1925 | struct fd f = fdget_raw(dfd); |
31e6b01f NP |
1926 | struct dentry *dentry; |
1927 | ||
2903ff01 AV |
1928 | if (!f.file) |
1929 | return -EBADF; | |
31e6b01f | 1930 | |
2903ff01 | 1931 | dentry = f.file->f_path.dentry; |
31e6b01f | 1932 | |
f52e0c11 | 1933 | if (*name) { |
741b7c3f | 1934 | if (!can_lookup(dentry->d_inode)) { |
2903ff01 AV |
1935 | fdput(f); |
1936 | return -ENOTDIR; | |
1937 | } | |
f52e0c11 | 1938 | } |
31e6b01f | 1939 | |
2903ff01 | 1940 | nd->path = f.file->f_path; |
e41f7d4e | 1941 | if (flags & LOOKUP_RCU) { |
2903ff01 AV |
1942 | if (f.need_put) |
1943 | *fp = f.file; | |
e41f7d4e | 1944 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
32a7991b | 1945 | lock_rcu_walk(); |
e41f7d4e | 1946 | } else { |
2903ff01 AV |
1947 | path_get(&nd->path); |
1948 | fdput(f); | |
e41f7d4e | 1949 | } |
31e6b01f | 1950 | } |
31e6b01f | 1951 | |
31e6b01f | 1952 | nd->inode = nd->path.dentry->d_inode; |
9b4a9b14 | 1953 | return 0; |
9b4a9b14 AV |
1954 | } |
1955 | ||
bd92d7fe AV |
1956 | static inline int lookup_last(struct nameidata *nd, struct path *path) |
1957 | { | |
1958 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) | |
1959 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
1960 | ||
1961 | nd->flags &= ~LOOKUP_PARENT; | |
21b9b073 | 1962 | return walk_component(nd, path, nd->flags & LOOKUP_FOLLOW); |
bd92d7fe AV |
1963 | } |
1964 | ||
9b4a9b14 | 1965 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
ee0827cd | 1966 | static int path_lookupat(int dfd, const char *name, |
9b4a9b14 AV |
1967 | unsigned int flags, struct nameidata *nd) |
1968 | { | |
70e9b357 | 1969 | struct file *base = NULL; |
bd92d7fe AV |
1970 | struct path path; |
1971 | int err; | |
31e6b01f NP |
1972 | |
1973 | /* | |
1974 | * Path walking is largely split up into 2 different synchronisation | |
1975 | * schemes, rcu-walk and ref-walk (explained in | |
1976 | * Documentation/filesystems/path-lookup.txt). These share much of the | |
1977 | * path walk code, but some things particularly setup, cleanup, and | |
1978 | * following mounts are sufficiently divergent that functions are | |
1979 | * duplicated. Typically there is a function foo(), and its RCU | |
1980 | * analogue, foo_rcu(). | |
1981 | * | |
1982 | * -ECHILD is the error number of choice (just to avoid clashes) that | |
1983 | * is returned if some aspect of an rcu-walk fails. Such an error must | |
1984 | * be handled by restarting a traditional ref-walk (which will always | |
1985 | * be able to complete). | |
1986 | */ | |
bd92d7fe | 1987 | err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); |
ee0827cd | 1988 | |
bd92d7fe AV |
1989 | if (unlikely(err)) |
1990 | return err; | |
ee0827cd AV |
1991 | |
1992 | current->total_link_count = 0; | |
bd92d7fe AV |
1993 | err = link_path_walk(name, nd); |
1994 | ||
1995 | if (!err && !(flags & LOOKUP_PARENT)) { | |
bd92d7fe AV |
1996 | err = lookup_last(nd, &path); |
1997 | while (err > 0) { | |
1998 | void *cookie; | |
1999 | struct path link = path; | |
800179c9 KC |
2000 | err = may_follow_link(&link, nd); |
2001 | if (unlikely(err)) | |
2002 | break; | |
bd92d7fe | 2003 | nd->flags |= LOOKUP_PARENT; |
574197e0 | 2004 | err = follow_link(&link, nd, &cookie); |
6d7b5aae AV |
2005 | if (err) |
2006 | break; | |
2007 | err = lookup_last(nd, &path); | |
574197e0 | 2008 | put_link(nd, &link, cookie); |
bd92d7fe AV |
2009 | } |
2010 | } | |
ee0827cd | 2011 | |
9f1fafee AV |
2012 | if (!err) |
2013 | err = complete_walk(nd); | |
bd92d7fe AV |
2014 | |
2015 | if (!err && nd->flags & LOOKUP_DIRECTORY) { | |
05252901 | 2016 | if (!can_lookup(nd->inode)) { |
bd92d7fe | 2017 | path_put(&nd->path); |
bd23a539 | 2018 | err = -ENOTDIR; |
bd92d7fe AV |
2019 | } |
2020 | } | |
16c2cd71 | 2021 | |
70e9b357 AV |
2022 | if (base) |
2023 | fput(base); | |
ee0827cd | 2024 | |
5b6ca027 | 2025 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
2a737871 AV |
2026 | path_put(&nd->root); |
2027 | nd->root.mnt = NULL; | |
2028 | } | |
bd92d7fe | 2029 | return err; |
ee0827cd | 2030 | } |
31e6b01f | 2031 | |
873f1eed | 2032 | static int filename_lookup(int dfd, struct filename *name, |
ee0827cd AV |
2033 | unsigned int flags, struct nameidata *nd) |
2034 | { | |
873f1eed | 2035 | int retval = path_lookupat(dfd, name->name, flags | LOOKUP_RCU, nd); |
ee0827cd | 2036 | if (unlikely(retval == -ECHILD)) |
873f1eed | 2037 | retval = path_lookupat(dfd, name->name, flags, nd); |
ee0827cd | 2038 | if (unlikely(retval == -ESTALE)) |
873f1eed JL |
2039 | retval = path_lookupat(dfd, name->name, |
2040 | flags | LOOKUP_REVAL, nd); | |
31e6b01f | 2041 | |
f78570dd | 2042 | if (likely(!retval)) |
adb5c247 | 2043 | audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); |
170aa3d0 | 2044 | return retval; |
1da177e4 LT |
2045 | } |
2046 | ||
873f1eed JL |
2047 | static int do_path_lookup(int dfd, const char *name, |
2048 | unsigned int flags, struct nameidata *nd) | |
2049 | { | |
2050 | struct filename filename = { .name = name }; | |
2051 | ||
2052 | return filename_lookup(dfd, &filename, flags, nd); | |
2053 | } | |
2054 | ||
79714f72 AV |
2055 | /* does lookup, returns the object with parent locked */ |
2056 | struct dentry *kern_path_locked(const char *name, struct path *path) | |
5590ff0d | 2057 | { |
79714f72 AV |
2058 | struct nameidata nd; |
2059 | struct dentry *d; | |
2060 | int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd); | |
2061 | if (err) | |
2062 | return ERR_PTR(err); | |
2063 | if (nd.last_type != LAST_NORM) { | |
2064 | path_put(&nd.path); | |
2065 | return ERR_PTR(-EINVAL); | |
2066 | } | |
2067 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); | |
1e0ea001 | 2068 | d = __lookup_hash(&nd.last, nd.path.dentry, 0); |
79714f72 AV |
2069 | if (IS_ERR(d)) { |
2070 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); | |
2071 | path_put(&nd.path); | |
2072 | return d; | |
2073 | } | |
2074 | *path = nd.path; | |
2075 | return d; | |
5590ff0d UD |
2076 | } |
2077 | ||
d1811465 AV |
2078 | int kern_path(const char *name, unsigned int flags, struct path *path) |
2079 | { | |
2080 | struct nameidata nd; | |
2081 | int res = do_path_lookup(AT_FDCWD, name, flags, &nd); | |
2082 | if (!res) | |
2083 | *path = nd.path; | |
2084 | return res; | |
2085 | } | |
2086 | ||
16f18200 JJS |
2087 | /** |
2088 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
2089 | * @dentry: pointer to dentry of the base directory | |
2090 | * @mnt: pointer to vfs mount of the base directory | |
2091 | * @name: pointer to file name | |
2092 | * @flags: lookup flags | |
e0a01249 | 2093 | * @path: pointer to struct path to fill |
16f18200 JJS |
2094 | */ |
2095 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
2096 | const char *name, unsigned int flags, | |
e0a01249 | 2097 | struct path *path) |
16f18200 | 2098 | { |
e0a01249 AV |
2099 | struct nameidata nd; |
2100 | int err; | |
2101 | nd.root.dentry = dentry; | |
2102 | nd.root.mnt = mnt; | |
2103 | BUG_ON(flags & LOOKUP_PARENT); | |
5b6ca027 | 2104 | /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ |
e0a01249 AV |
2105 | err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); |
2106 | if (!err) | |
2107 | *path = nd.path; | |
2108 | return err; | |
16f18200 JJS |
2109 | } |
2110 | ||
057f6c01 JM |
2111 | /* |
2112 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
2113 | * needs parent already locked. Doesn't follow mounts. | |
2114 | * SMP-safe. | |
2115 | */ | |
eead1911 | 2116 | static struct dentry *lookup_hash(struct nameidata *nd) |
057f6c01 | 2117 | { |
72bd866a | 2118 | return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); |
1da177e4 LT |
2119 | } |
2120 | ||
eead1911 | 2121 | /** |
a6b91919 | 2122 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
2123 | * @name: pathname component to lookup |
2124 | * @base: base directory to lookup from | |
2125 | * @len: maximum length @len should be interpreted to | |
2126 | * | |
a6b91919 RD |
2127 | * Note that this routine is purely a helper for filesystem usage and should |
2128 | * not be called by generic code. Also note that by using this function the | |
eead1911 CH |
2129 | * nameidata argument is passed to the filesystem methods and a filesystem |
2130 | * using this helper needs to be prepared for that. | |
2131 | */ | |
057f6c01 JM |
2132 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
2133 | { | |
057f6c01 | 2134 | struct qstr this; |
6a96ba54 | 2135 | unsigned int c; |
cda309de | 2136 | int err; |
057f6c01 | 2137 | |
2f9092e1 DW |
2138 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
2139 | ||
6a96ba54 AV |
2140 | this.name = name; |
2141 | this.len = len; | |
0145acc2 | 2142 | this.hash = full_name_hash(name, len); |
6a96ba54 AV |
2143 | if (!len) |
2144 | return ERR_PTR(-EACCES); | |
2145 | ||
21d8a15a AV |
2146 | if (unlikely(name[0] == '.')) { |
2147 | if (len < 2 || (len == 2 && name[1] == '.')) | |
2148 | return ERR_PTR(-EACCES); | |
2149 | } | |
2150 | ||
6a96ba54 AV |
2151 | while (len--) { |
2152 | c = *(const unsigned char *)name++; | |
2153 | if (c == '/' || c == '\0') | |
2154 | return ERR_PTR(-EACCES); | |
6a96ba54 | 2155 | } |
5a202bcd AV |
2156 | /* |
2157 | * See if the low-level filesystem might want | |
2158 | * to use its own hash.. | |
2159 | */ | |
2160 | if (base->d_flags & DCACHE_OP_HASH) { | |
da53be12 | 2161 | int err = base->d_op->d_hash(base, &this); |
5a202bcd AV |
2162 | if (err < 0) |
2163 | return ERR_PTR(err); | |
2164 | } | |
eead1911 | 2165 | |
cda309de MS |
2166 | err = inode_permission(base->d_inode, MAY_EXEC); |
2167 | if (err) | |
2168 | return ERR_PTR(err); | |
2169 | ||
72bd866a | 2170 | return __lookup_hash(&this, base, 0); |
057f6c01 JM |
2171 | } |
2172 | ||
1fa1e7f6 AW |
2173 | int user_path_at_empty(int dfd, const char __user *name, unsigned flags, |
2174 | struct path *path, int *empty) | |
1da177e4 | 2175 | { |
2d8f3038 | 2176 | struct nameidata nd; |
91a27b2a | 2177 | struct filename *tmp = getname_flags(name, flags, empty); |
1da177e4 | 2178 | int err = PTR_ERR(tmp); |
1da177e4 | 2179 | if (!IS_ERR(tmp)) { |
2d8f3038 AV |
2180 | |
2181 | BUG_ON(flags & LOOKUP_PARENT); | |
2182 | ||
873f1eed | 2183 | err = filename_lookup(dfd, tmp, flags, &nd); |
1da177e4 | 2184 | putname(tmp); |
2d8f3038 AV |
2185 | if (!err) |
2186 | *path = nd.path; | |
1da177e4 LT |
2187 | } |
2188 | return err; | |
2189 | } | |
2190 | ||
1fa1e7f6 AW |
2191 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
2192 | struct path *path) | |
2193 | { | |
f7493e5d | 2194 | return user_path_at_empty(dfd, name, flags, path, NULL); |
1fa1e7f6 AW |
2195 | } |
2196 | ||
873f1eed JL |
2197 | /* |
2198 | * NB: most callers don't do anything directly with the reference to the | |
2199 | * to struct filename, but the nd->last pointer points into the name string | |
2200 | * allocated by getname. So we must hold the reference to it until all | |
2201 | * path-walking is complete. | |
2202 | */ | |
91a27b2a | 2203 | static struct filename * |
9e790bd6 JL |
2204 | user_path_parent(int dfd, const char __user *path, struct nameidata *nd, |
2205 | unsigned int flags) | |
2ad94ae6 | 2206 | { |
91a27b2a | 2207 | struct filename *s = getname(path); |
2ad94ae6 AV |
2208 | int error; |
2209 | ||
9e790bd6 JL |
2210 | /* only LOOKUP_REVAL is allowed in extra flags */ |
2211 | flags &= LOOKUP_REVAL; | |
2212 | ||
2ad94ae6 | 2213 | if (IS_ERR(s)) |
91a27b2a | 2214 | return s; |
2ad94ae6 | 2215 | |
9e790bd6 | 2216 | error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd); |
91a27b2a | 2217 | if (error) { |
2ad94ae6 | 2218 | putname(s); |
91a27b2a JL |
2219 | return ERR_PTR(error); |
2220 | } | |
2ad94ae6 | 2221 | |
91a27b2a | 2222 | return s; |
2ad94ae6 AV |
2223 | } |
2224 | ||
1da177e4 LT |
2225 | /* |
2226 | * It's inline, so penalty for filesystems that don't use sticky bit is | |
2227 | * minimal. | |
2228 | */ | |
2229 | static inline int check_sticky(struct inode *dir, struct inode *inode) | |
2230 | { | |
8e96e3b7 | 2231 | kuid_t fsuid = current_fsuid(); |
da9592ed | 2232 | |
1da177e4 LT |
2233 | if (!(dir->i_mode & S_ISVTX)) |
2234 | return 0; | |
8e96e3b7 | 2235 | if (uid_eq(inode->i_uid, fsuid)) |
1da177e4 | 2236 | return 0; |
8e96e3b7 | 2237 | if (uid_eq(dir->i_uid, fsuid)) |
1da177e4 | 2238 | return 0; |
1a48e2ac | 2239 | return !inode_capable(inode, CAP_FOWNER); |
1da177e4 LT |
2240 | } |
2241 | ||
2242 | /* | |
2243 | * Check whether we can remove a link victim from directory dir, check | |
2244 | * whether the type of victim is right. | |
2245 | * 1. We can't do it if dir is read-only (done in permission()) | |
2246 | * 2. We should have write and exec permissions on dir | |
2247 | * 3. We can't remove anything from append-only dir | |
2248 | * 4. We can't do anything with immutable dir (done in permission()) | |
2249 | * 5. If the sticky bit on dir is set we should either | |
2250 | * a. be owner of dir, or | |
2251 | * b. be owner of victim, or | |
2252 | * c. have CAP_FOWNER capability | |
2253 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
2254 | * links pointing to it. | |
2255 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
2256 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
2257 | * 9. We can't remove a root or mountpoint. | |
2258 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
2259 | * nfs_async_unlink(). | |
2260 | */ | |
858119e1 | 2261 | static int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
1da177e4 LT |
2262 | { |
2263 | int error; | |
2264 | ||
2265 | if (!victim->d_inode) | |
2266 | return -ENOENT; | |
2267 | ||
2268 | BUG_ON(victim->d_parent->d_inode != dir); | |
4fa6b5ec | 2269 | audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); |
1da177e4 | 2270 | |
f419a2e3 | 2271 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2272 | if (error) |
2273 | return error; | |
2274 | if (IS_APPEND(dir)) | |
2275 | return -EPERM; | |
2276 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| | |
f9454548 | 2277 | IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) |
1da177e4 LT |
2278 | return -EPERM; |
2279 | if (isdir) { | |
2280 | if (!S_ISDIR(victim->d_inode->i_mode)) | |
2281 | return -ENOTDIR; | |
2282 | if (IS_ROOT(victim)) | |
2283 | return -EBUSY; | |
2284 | } else if (S_ISDIR(victim->d_inode->i_mode)) | |
2285 | return -EISDIR; | |
2286 | if (IS_DEADDIR(dir)) | |
2287 | return -ENOENT; | |
2288 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
2289 | return -EBUSY; | |
2290 | return 0; | |
2291 | } | |
2292 | ||
2293 | /* Check whether we can create an object with dentry child in directory | |
2294 | * dir. | |
2295 | * 1. We can't do it if child already exists (open has special treatment for | |
2296 | * this case, but since we are inlined it's OK) | |
2297 | * 2. We can't do it if dir is read-only (done in permission()) | |
2298 | * 3. We should have write and exec permissions on dir | |
2299 | * 4. We can't do it if dir is immutable (done in permission()) | |
2300 | */ | |
a95164d9 | 2301 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 LT |
2302 | { |
2303 | if (child->d_inode) | |
2304 | return -EEXIST; | |
2305 | if (IS_DEADDIR(dir)) | |
2306 | return -ENOENT; | |
f419a2e3 | 2307 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2308 | } |
2309 | ||
1da177e4 LT |
2310 | /* |
2311 | * p1 and p2 should be directories on the same fs. | |
2312 | */ | |
2313 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
2314 | { | |
2315 | struct dentry *p; | |
2316 | ||
2317 | if (p1 == p2) { | |
f2eace23 | 2318 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
2319 | return NULL; |
2320 | } | |
2321 | ||
a11f3a05 | 2322 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 | 2323 | |
e2761a11 OH |
2324 | p = d_ancestor(p2, p1); |
2325 | if (p) { | |
2326 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); | |
2327 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
2328 | return p; | |
1da177e4 LT |
2329 | } |
2330 | ||
e2761a11 OH |
2331 | p = d_ancestor(p1, p2); |
2332 | if (p) { | |
2333 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); | |
2334 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
2335 | return p; | |
1da177e4 LT |
2336 | } |
2337 | ||
f2eace23 IM |
2338 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
2339 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1da177e4 LT |
2340 | return NULL; |
2341 | } | |
2342 | ||
2343 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
2344 | { | |
1b1dcc1b | 2345 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 2346 | if (p1 != p2) { |
1b1dcc1b | 2347 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 2348 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
2349 | } |
2350 | } | |
2351 | ||
4acdaf27 | 2352 | int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
312b63fb | 2353 | bool want_excl) |
1da177e4 | 2354 | { |
a95164d9 | 2355 | int error = may_create(dir, dentry); |
1da177e4 LT |
2356 | if (error) |
2357 | return error; | |
2358 | ||
acfa4380 | 2359 | if (!dir->i_op->create) |
1da177e4 LT |
2360 | return -EACCES; /* shouldn't it be ENOSYS? */ |
2361 | mode &= S_IALLUGO; | |
2362 | mode |= S_IFREG; | |
2363 | error = security_inode_create(dir, dentry, mode); | |
2364 | if (error) | |
2365 | return error; | |
312b63fb | 2366 | error = dir->i_op->create(dir, dentry, mode, want_excl); |
a74574aa | 2367 | if (!error) |
f38aa942 | 2368 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2369 | return error; |
2370 | } | |
2371 | ||
73d049a4 | 2372 | static int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 2373 | { |
3fb64190 | 2374 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
2375 | struct inode *inode = dentry->d_inode; |
2376 | int error; | |
2377 | ||
bcda7652 AV |
2378 | /* O_PATH? */ |
2379 | if (!acc_mode) | |
2380 | return 0; | |
2381 | ||
1da177e4 LT |
2382 | if (!inode) |
2383 | return -ENOENT; | |
2384 | ||
c8fe8f30 CH |
2385 | switch (inode->i_mode & S_IFMT) { |
2386 | case S_IFLNK: | |
1da177e4 | 2387 | return -ELOOP; |
c8fe8f30 CH |
2388 | case S_IFDIR: |
2389 | if (acc_mode & MAY_WRITE) | |
2390 | return -EISDIR; | |
2391 | break; | |
2392 | case S_IFBLK: | |
2393 | case S_IFCHR: | |
3fb64190 | 2394 | if (path->mnt->mnt_flags & MNT_NODEV) |
1da177e4 | 2395 | return -EACCES; |
c8fe8f30 CH |
2396 | /*FALLTHRU*/ |
2397 | case S_IFIFO: | |
2398 | case S_IFSOCK: | |
1da177e4 | 2399 | flag &= ~O_TRUNC; |
c8fe8f30 | 2400 | break; |
4a3fd211 | 2401 | } |
b41572e9 | 2402 | |
3fb64190 | 2403 | error = inode_permission(inode, acc_mode); |
b41572e9 DH |
2404 | if (error) |
2405 | return error; | |
6146f0d5 | 2406 | |
1da177e4 LT |
2407 | /* |
2408 | * An append-only file must be opened in append mode for writing. | |
2409 | */ | |
2410 | if (IS_APPEND(inode)) { | |
8737c930 | 2411 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
7715b521 | 2412 | return -EPERM; |
1da177e4 | 2413 | if (flag & O_TRUNC) |
7715b521 | 2414 | return -EPERM; |
1da177e4 LT |
2415 | } |
2416 | ||
2417 | /* O_NOATIME can only be set by the owner or superuser */ | |
2e149670 | 2418 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
7715b521 | 2419 | return -EPERM; |
1da177e4 | 2420 | |
f3c7691e | 2421 | return 0; |
7715b521 | 2422 | } |
1da177e4 | 2423 | |
e1181ee6 | 2424 | static int handle_truncate(struct file *filp) |
7715b521 | 2425 | { |
e1181ee6 | 2426 | struct path *path = &filp->f_path; |
7715b521 AV |
2427 | struct inode *inode = path->dentry->d_inode; |
2428 | int error = get_write_access(inode); | |
2429 | if (error) | |
2430 | return error; | |
2431 | /* | |
2432 | * Refuse to truncate files with mandatory locks held on them. | |
2433 | */ | |
2434 | error = locks_verify_locked(inode); | |
2435 | if (!error) | |
ea0d3ab2 | 2436 | error = security_path_truncate(path); |
7715b521 AV |
2437 | if (!error) { |
2438 | error = do_truncate(path->dentry, 0, | |
2439 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
e1181ee6 | 2440 | filp); |
7715b521 AV |
2441 | } |
2442 | put_write_access(inode); | |
acd0c935 | 2443 | return error; |
1da177e4 LT |
2444 | } |
2445 | ||
d57999e1 DH |
2446 | static inline int open_to_namei_flags(int flag) |
2447 | { | |
8a5e929d AV |
2448 | if ((flag & O_ACCMODE) == 3) |
2449 | flag--; | |
d57999e1 DH |
2450 | return flag; |
2451 | } | |
2452 | ||
d18e9008 MS |
2453 | static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) |
2454 | { | |
2455 | int error = security_path_mknod(dir, dentry, mode, 0); | |
2456 | if (error) | |
2457 | return error; | |
2458 | ||
2459 | error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); | |
2460 | if (error) | |
2461 | return error; | |
2462 | ||
2463 | return security_inode_create(dir->dentry->d_inode, dentry, mode); | |
2464 | } | |
2465 | ||
1acf0af9 DH |
2466 | /* |
2467 | * Attempt to atomically look up, create and open a file from a negative | |
2468 | * dentry. | |
2469 | * | |
2470 | * Returns 0 if successful. The file will have been created and attached to | |
2471 | * @file by the filesystem calling finish_open(). | |
2472 | * | |
2473 | * Returns 1 if the file was looked up only or didn't need creating. The | |
2474 | * caller will need to perform the open themselves. @path will have been | |
2475 | * updated to point to the new dentry. This may be negative. | |
2476 | * | |
2477 | * Returns an error code otherwise. | |
2478 | */ | |
2675a4eb AV |
2479 | static int atomic_open(struct nameidata *nd, struct dentry *dentry, |
2480 | struct path *path, struct file *file, | |
2481 | const struct open_flags *op, | |
64894cf8 | 2482 | bool got_write, bool need_lookup, |
2675a4eb | 2483 | int *opened) |
d18e9008 MS |
2484 | { |
2485 | struct inode *dir = nd->path.dentry->d_inode; | |
2486 | unsigned open_flag = open_to_namei_flags(op->open_flag); | |
2487 | umode_t mode; | |
2488 | int error; | |
2489 | int acc_mode; | |
d18e9008 MS |
2490 | int create_error = 0; |
2491 | struct dentry *const DENTRY_NOT_SET = (void *) -1UL; | |
2492 | ||
2493 | BUG_ON(dentry->d_inode); | |
2494 | ||
2495 | /* Don't create child dentry for a dead directory. */ | |
2496 | if (unlikely(IS_DEADDIR(dir))) { | |
2675a4eb | 2497 | error = -ENOENT; |
d18e9008 MS |
2498 | goto out; |
2499 | } | |
2500 | ||
62b259d8 | 2501 | mode = op->mode; |
d18e9008 MS |
2502 | if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) |
2503 | mode &= ~current_umask(); | |
2504 | ||
f8310c59 | 2505 | if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) { |
d18e9008 | 2506 | open_flag &= ~O_TRUNC; |
47237687 | 2507 | *opened |= FILE_CREATED; |
d18e9008 MS |
2508 | } |
2509 | ||
2510 | /* | |
2511 | * Checking write permission is tricky, bacuse we don't know if we are | |
2512 | * going to actually need it: O_CREAT opens should work as long as the | |
2513 | * file exists. But checking existence breaks atomicity. The trick is | |
2514 | * to check access and if not granted clear O_CREAT from the flags. | |
2515 | * | |
2516 | * Another problem is returing the "right" error value (e.g. for an | |
2517 | * O_EXCL open we want to return EEXIST not EROFS). | |
2518 | */ | |
64894cf8 AV |
2519 | if (((open_flag & (O_CREAT | O_TRUNC)) || |
2520 | (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { | |
2521 | if (!(open_flag & O_CREAT)) { | |
d18e9008 MS |
2522 | /* |
2523 | * No O_CREATE -> atomicity not a requirement -> fall | |
2524 | * back to lookup + open | |
2525 | */ | |
2526 | goto no_open; | |
2527 | } else if (open_flag & (O_EXCL | O_TRUNC)) { | |
2528 | /* Fall back and fail with the right error */ | |
64894cf8 | 2529 | create_error = -EROFS; |
d18e9008 MS |
2530 | goto no_open; |
2531 | } else { | |
2532 | /* No side effects, safe to clear O_CREAT */ | |
64894cf8 | 2533 | create_error = -EROFS; |
d18e9008 MS |
2534 | open_flag &= ~O_CREAT; |
2535 | } | |
2536 | } | |
2537 | ||
2538 | if (open_flag & O_CREAT) { | |
38227f78 | 2539 | error = may_o_create(&nd->path, dentry, mode); |
d18e9008 MS |
2540 | if (error) { |
2541 | create_error = error; | |
2542 | if (open_flag & O_EXCL) | |
2543 | goto no_open; | |
2544 | open_flag &= ~O_CREAT; | |
2545 | } | |
2546 | } | |
2547 | ||
2548 | if (nd->flags & LOOKUP_DIRECTORY) | |
2549 | open_flag |= O_DIRECTORY; | |
2550 | ||
30d90494 AV |
2551 | file->f_path.dentry = DENTRY_NOT_SET; |
2552 | file->f_path.mnt = nd->path.mnt; | |
2553 | error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, | |
47237687 | 2554 | opened); |
d9585277 | 2555 | if (error < 0) { |
d9585277 AV |
2556 | if (create_error && error == -ENOENT) |
2557 | error = create_error; | |
d18e9008 MS |
2558 | goto out; |
2559 | } | |
2560 | ||
2561 | acc_mode = op->acc_mode; | |
47237687 | 2562 | if (*opened & FILE_CREATED) { |
d18e9008 MS |
2563 | fsnotify_create(dir, dentry); |
2564 | acc_mode = MAY_OPEN; | |
2565 | } | |
2566 | ||
d9585277 | 2567 | if (error) { /* returned 1, that is */ |
30d90494 | 2568 | if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { |
2675a4eb | 2569 | error = -EIO; |
d18e9008 MS |
2570 | goto out; |
2571 | } | |
30d90494 | 2572 | if (file->f_path.dentry) { |
d18e9008 | 2573 | dput(dentry); |
30d90494 | 2574 | dentry = file->f_path.dentry; |
d18e9008 | 2575 | } |
62b2ce96 SW |
2576 | if (create_error && dentry->d_inode == NULL) { |
2577 | error = create_error; | |
2578 | goto out; | |
2579 | } | |
d18e9008 MS |
2580 | goto looked_up; |
2581 | } | |
2582 | ||
2583 | /* | |
2584 | * We didn't have the inode before the open, so check open permission | |
2585 | * here. | |
2586 | */ | |
2675a4eb AV |
2587 | error = may_open(&file->f_path, acc_mode, open_flag); |
2588 | if (error) | |
2589 | fput(file); | |
d18e9008 MS |
2590 | |
2591 | out: | |
2592 | dput(dentry); | |
2675a4eb | 2593 | return error; |
d18e9008 | 2594 | |
d18e9008 MS |
2595 | no_open: |
2596 | if (need_lookup) { | |
72bd866a | 2597 | dentry = lookup_real(dir, dentry, nd->flags); |
d18e9008 | 2598 | if (IS_ERR(dentry)) |
2675a4eb | 2599 | return PTR_ERR(dentry); |
d18e9008 MS |
2600 | |
2601 | if (create_error) { | |
2602 | int open_flag = op->open_flag; | |
2603 | ||
2675a4eb | 2604 | error = create_error; |
d18e9008 MS |
2605 | if ((open_flag & O_EXCL)) { |
2606 | if (!dentry->d_inode) | |
2607 | goto out; | |
2608 | } else if (!dentry->d_inode) { | |
2609 | goto out; | |
2610 | } else if ((open_flag & O_TRUNC) && | |
2611 | S_ISREG(dentry->d_inode->i_mode)) { | |
2612 | goto out; | |
2613 | } | |
2614 | /* will fail later, go on to get the right error */ | |
2615 | } | |
2616 | } | |
2617 | looked_up: | |
2618 | path->dentry = dentry; | |
2619 | path->mnt = nd->path.mnt; | |
2675a4eb | 2620 | return 1; |
d18e9008 MS |
2621 | } |
2622 | ||
d58ffd35 | 2623 | /* |
1acf0af9 | 2624 | * Look up and maybe create and open the last component. |
d58ffd35 MS |
2625 | * |
2626 | * Must be called with i_mutex held on parent. | |
2627 | * | |
1acf0af9 DH |
2628 | * Returns 0 if the file was successfully atomically created (if necessary) and |
2629 | * opened. In this case the file will be returned attached to @file. | |
2630 | * | |
2631 | * Returns 1 if the file was not completely opened at this time, though lookups | |
2632 | * and creations will have been performed and the dentry returned in @path will | |
2633 | * be positive upon return if O_CREAT was specified. If O_CREAT wasn't | |
2634 | * specified then a negative dentry may be returned. | |
2635 | * | |
2636 | * An error code is returned otherwise. | |
2637 | * | |
2638 | * FILE_CREATE will be set in @*opened if the dentry was created and will be | |
2639 | * cleared otherwise prior to returning. | |
d58ffd35 | 2640 | */ |
2675a4eb AV |
2641 | static int lookup_open(struct nameidata *nd, struct path *path, |
2642 | struct file *file, | |
2643 | const struct open_flags *op, | |
64894cf8 | 2644 | bool got_write, int *opened) |
d58ffd35 MS |
2645 | { |
2646 | struct dentry *dir = nd->path.dentry; | |
54ef4872 | 2647 | struct inode *dir_inode = dir->d_inode; |
d58ffd35 MS |
2648 | struct dentry *dentry; |
2649 | int error; | |
54ef4872 | 2650 | bool need_lookup; |
d58ffd35 | 2651 | |
47237687 | 2652 | *opened &= ~FILE_CREATED; |
201f956e | 2653 | dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); |
d58ffd35 | 2654 | if (IS_ERR(dentry)) |
2675a4eb | 2655 | return PTR_ERR(dentry); |
d58ffd35 | 2656 | |
d18e9008 MS |
2657 | /* Cached positive dentry: will open in f_op->open */ |
2658 | if (!need_lookup && dentry->d_inode) | |
2659 | goto out_no_open; | |
2660 | ||
2661 | if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { | |
64894cf8 | 2662 | return atomic_open(nd, dentry, path, file, op, got_write, |
47237687 | 2663 | need_lookup, opened); |
d18e9008 MS |
2664 | } |
2665 | ||
54ef4872 MS |
2666 | if (need_lookup) { |
2667 | BUG_ON(dentry->d_inode); | |
2668 | ||
72bd866a | 2669 | dentry = lookup_real(dir_inode, dentry, nd->flags); |
54ef4872 | 2670 | if (IS_ERR(dentry)) |
2675a4eb | 2671 | return PTR_ERR(dentry); |
54ef4872 MS |
2672 | } |
2673 | ||
d58ffd35 MS |
2674 | /* Negative dentry, just create the file */ |
2675 | if (!dentry->d_inode && (op->open_flag & O_CREAT)) { | |
2676 | umode_t mode = op->mode; | |
2677 | if (!IS_POSIXACL(dir->d_inode)) | |
2678 | mode &= ~current_umask(); | |
2679 | /* | |
2680 | * This write is needed to ensure that a | |
2681 | * rw->ro transition does not occur between | |
2682 | * the time when the file is created and when | |
2683 | * a permanent write count is taken through | |
015c3bbc | 2684 | * the 'struct file' in finish_open(). |
d58ffd35 | 2685 | */ |
64894cf8 AV |
2686 | if (!got_write) { |
2687 | error = -EROFS; | |
d58ffd35 | 2688 | goto out_dput; |
64894cf8 | 2689 | } |
47237687 | 2690 | *opened |= FILE_CREATED; |
d58ffd35 MS |
2691 | error = security_path_mknod(&nd->path, dentry, mode, 0); |
2692 | if (error) | |
2693 | goto out_dput; | |
312b63fb AV |
2694 | error = vfs_create(dir->d_inode, dentry, mode, |
2695 | nd->flags & LOOKUP_EXCL); | |
d58ffd35 MS |
2696 | if (error) |
2697 | goto out_dput; | |
2698 | } | |
d18e9008 | 2699 | out_no_open: |
d58ffd35 MS |
2700 | path->dentry = dentry; |
2701 | path->mnt = nd->path.mnt; | |
2675a4eb | 2702 | return 1; |
d58ffd35 MS |
2703 | |
2704 | out_dput: | |
2705 | dput(dentry); | |
2675a4eb | 2706 | return error; |
d58ffd35 MS |
2707 | } |
2708 | ||
31e6b01f | 2709 | /* |
fe2d35ff | 2710 | * Handle the last step of open() |
31e6b01f | 2711 | */ |
2675a4eb AV |
2712 | static int do_last(struct nameidata *nd, struct path *path, |
2713 | struct file *file, const struct open_flags *op, | |
669abf4e | 2714 | int *opened, struct filename *name) |
fb1cc555 | 2715 | { |
a1e28038 | 2716 | struct dentry *dir = nd->path.dentry; |
ca344a89 | 2717 | int open_flag = op->open_flag; |
77d660a8 | 2718 | bool will_truncate = (open_flag & O_TRUNC) != 0; |
64894cf8 | 2719 | bool got_write = false; |
bcda7652 | 2720 | int acc_mode = op->acc_mode; |
a1eb3315 | 2721 | struct inode *inode; |
77d660a8 | 2722 | bool symlink_ok = false; |
16b1c1cd MS |
2723 | struct path save_parent = { .dentry = NULL, .mnt = NULL }; |
2724 | bool retried = false; | |
16c2cd71 | 2725 | int error; |
1f36f774 | 2726 | |
c3e380b0 AV |
2727 | nd->flags &= ~LOOKUP_PARENT; |
2728 | nd->flags |= op->intent; | |
2729 | ||
bc77daa7 | 2730 | if (nd->last_type != LAST_NORM) { |
fe2d35ff AV |
2731 | error = handle_dots(nd, nd->last_type); |
2732 | if (error) | |
2675a4eb | 2733 | return error; |
e83db167 | 2734 | goto finish_open; |
1f36f774 | 2735 | } |
67ee3ad2 | 2736 | |
ca344a89 | 2737 | if (!(open_flag & O_CREAT)) { |
fe2d35ff AV |
2738 | if (nd->last.name[nd->last.len]) |
2739 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
bcda7652 | 2740 | if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) |
77d660a8 | 2741 | symlink_ok = true; |
fe2d35ff | 2742 | /* we _can_ be in RCU mode here */ |
e97cdc87 | 2743 | error = lookup_fast(nd, path, &inode); |
71574865 MS |
2744 | if (likely(!error)) |
2745 | goto finish_lookup; | |
2746 | ||
2747 | if (error < 0) | |
2675a4eb | 2748 | goto out; |
71574865 MS |
2749 | |
2750 | BUG_ON(nd->inode != dir->d_inode); | |
b6183df7 MS |
2751 | } else { |
2752 | /* create side of things */ | |
2753 | /* | |
2754 | * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED | |
2755 | * has been cleared when we got to the last component we are | |
2756 | * about to look up | |
2757 | */ | |
2758 | error = complete_walk(nd); | |
2759 | if (error) | |
2675a4eb | 2760 | return error; |
fe2d35ff | 2761 | |
33e2208a | 2762 | audit_inode(name, dir, LOOKUP_PARENT); |
b6183df7 MS |
2763 | error = -EISDIR; |
2764 | /* trailing slashes? */ | |
2765 | if (nd->last.name[nd->last.len]) | |
2675a4eb | 2766 | goto out; |
b6183df7 | 2767 | } |
a2c36b45 | 2768 | |
16b1c1cd | 2769 | retry_lookup: |
64894cf8 AV |
2770 | if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { |
2771 | error = mnt_want_write(nd->path.mnt); | |
2772 | if (!error) | |
2773 | got_write = true; | |
2774 | /* | |
2775 | * do _not_ fail yet - we might not need that or fail with | |
2776 | * a different error; let lookup_open() decide; we'll be | |
2777 | * dropping this one anyway. | |
2778 | */ | |
2779 | } | |
a1e28038 | 2780 | mutex_lock(&dir->d_inode->i_mutex); |
64894cf8 | 2781 | error = lookup_open(nd, path, file, op, got_write, opened); |
d58ffd35 | 2782 | mutex_unlock(&dir->d_inode->i_mutex); |
a1e28038 | 2783 | |
2675a4eb AV |
2784 | if (error <= 0) { |
2785 | if (error) | |
d18e9008 MS |
2786 | goto out; |
2787 | ||
47237687 | 2788 | if ((*opened & FILE_CREATED) || |
496ad9aa | 2789 | !S_ISREG(file_inode(file)->i_mode)) |
77d660a8 | 2790 | will_truncate = false; |
d18e9008 | 2791 | |
adb5c247 | 2792 | audit_inode(name, file->f_path.dentry, 0); |
d18e9008 MS |
2793 | goto opened; |
2794 | } | |
fb1cc555 | 2795 | |
47237687 | 2796 | if (*opened & FILE_CREATED) { |
9b44f1b3 | 2797 | /* Don't check for write permission, don't truncate */ |
ca344a89 | 2798 | open_flag &= ~O_TRUNC; |
77d660a8 | 2799 | will_truncate = false; |
bcda7652 | 2800 | acc_mode = MAY_OPEN; |
d58ffd35 | 2801 | path_to_nameidata(path, nd); |
e83db167 | 2802 | goto finish_open_created; |
fb1cc555 AV |
2803 | } |
2804 | ||
2805 | /* | |
3134f37e | 2806 | * create/update audit record if it already exists. |
fb1cc555 | 2807 | */ |
3134f37e | 2808 | if (path->dentry->d_inode) |
adb5c247 | 2809 | audit_inode(name, path->dentry, 0); |
fb1cc555 | 2810 | |
d18e9008 MS |
2811 | /* |
2812 | * If atomic_open() acquired write access it is dropped now due to | |
2813 | * possible mount and symlink following (this might be optimized away if | |
2814 | * necessary...) | |
2815 | */ | |
64894cf8 | 2816 | if (got_write) { |
d18e9008 | 2817 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 2818 | got_write = false; |
d18e9008 MS |
2819 | } |
2820 | ||
fb1cc555 | 2821 | error = -EEXIST; |
f8310c59 | 2822 | if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) |
fb1cc555 AV |
2823 | goto exit_dput; |
2824 | ||
9875cf80 DH |
2825 | error = follow_managed(path, nd->flags); |
2826 | if (error < 0) | |
2827 | goto exit_dput; | |
fb1cc555 | 2828 | |
a3fbbde7 AV |
2829 | if (error) |
2830 | nd->flags |= LOOKUP_JUMPED; | |
2831 | ||
decf3400 MS |
2832 | BUG_ON(nd->flags & LOOKUP_RCU); |
2833 | inode = path->dentry->d_inode; | |
5f5daac1 MS |
2834 | finish_lookup: |
2835 | /* we _can_ be in RCU mode here */ | |
fb1cc555 | 2836 | error = -ENOENT; |
54c33e7f MS |
2837 | if (!inode) { |
2838 | path_to_nameidata(path, nd); | |
2675a4eb | 2839 | goto out; |
54c33e7f | 2840 | } |
9e67f361 | 2841 | |
d45ea867 MS |
2842 | if (should_follow_link(inode, !symlink_ok)) { |
2843 | if (nd->flags & LOOKUP_RCU) { | |
2844 | if (unlikely(unlazy_walk(nd, path->dentry))) { | |
2845 | error = -ECHILD; | |
2675a4eb | 2846 | goto out; |
d45ea867 MS |
2847 | } |
2848 | } | |
2849 | BUG_ON(inode != path->dentry->d_inode); | |
2675a4eb | 2850 | return 1; |
d45ea867 | 2851 | } |
fb1cc555 | 2852 | |
16b1c1cd MS |
2853 | if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { |
2854 | path_to_nameidata(path, nd); | |
2855 | } else { | |
2856 | save_parent.dentry = nd->path.dentry; | |
2857 | save_parent.mnt = mntget(path->mnt); | |
2858 | nd->path.dentry = path->dentry; | |
2859 | ||
2860 | } | |
decf3400 | 2861 | nd->inode = inode; |
a3fbbde7 | 2862 | /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ |
bc77daa7 | 2863 | finish_open: |
a3fbbde7 | 2864 | error = complete_walk(nd); |
16b1c1cd MS |
2865 | if (error) { |
2866 | path_put(&save_parent); | |
2675a4eb | 2867 | return error; |
16b1c1cd | 2868 | } |
bc77daa7 | 2869 | audit_inode(name, nd->path.dentry, 0); |
fb1cc555 | 2870 | error = -EISDIR; |
050ac841 | 2871 | if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode)) |
2675a4eb | 2872 | goto out; |
af2f5542 | 2873 | error = -ENOTDIR; |
05252901 | 2874 | if ((nd->flags & LOOKUP_DIRECTORY) && !can_lookup(nd->inode)) |
2675a4eb | 2875 | goto out; |
6c0d46c4 | 2876 | if (!S_ISREG(nd->inode->i_mode)) |
77d660a8 | 2877 | will_truncate = false; |
6c0d46c4 | 2878 | |
0f9d1a10 AV |
2879 | if (will_truncate) { |
2880 | error = mnt_want_write(nd->path.mnt); | |
2881 | if (error) | |
2675a4eb | 2882 | goto out; |
64894cf8 | 2883 | got_write = true; |
0f9d1a10 | 2884 | } |
e83db167 | 2885 | finish_open_created: |
bcda7652 | 2886 | error = may_open(&nd->path, acc_mode, open_flag); |
ca344a89 | 2887 | if (error) |
2675a4eb | 2888 | goto out; |
30d90494 AV |
2889 | file->f_path.mnt = nd->path.mnt; |
2890 | error = finish_open(file, nd->path.dentry, NULL, opened); | |
2891 | if (error) { | |
30d90494 | 2892 | if (error == -EOPENSTALE) |
f60dc3db | 2893 | goto stale_open; |
015c3bbc | 2894 | goto out; |
f60dc3db | 2895 | } |
a8277b9b | 2896 | opened: |
2675a4eb | 2897 | error = open_check_o_direct(file); |
015c3bbc MS |
2898 | if (error) |
2899 | goto exit_fput; | |
2675a4eb | 2900 | error = ima_file_check(file, op->acc_mode); |
aa4caadb MS |
2901 | if (error) |
2902 | goto exit_fput; | |
2903 | ||
2904 | if (will_truncate) { | |
2675a4eb | 2905 | error = handle_truncate(file); |
aa4caadb MS |
2906 | if (error) |
2907 | goto exit_fput; | |
0f9d1a10 | 2908 | } |
ca344a89 | 2909 | out: |
64894cf8 | 2910 | if (got_write) |
0f9d1a10 | 2911 | mnt_drop_write(nd->path.mnt); |
16b1c1cd | 2912 | path_put(&save_parent); |
e276ae67 | 2913 | terminate_walk(nd); |
2675a4eb | 2914 | return error; |
fb1cc555 | 2915 | |
fb1cc555 AV |
2916 | exit_dput: |
2917 | path_put_conditional(path, nd); | |
ca344a89 | 2918 | goto out; |
015c3bbc | 2919 | exit_fput: |
2675a4eb AV |
2920 | fput(file); |
2921 | goto out; | |
015c3bbc | 2922 | |
f60dc3db MS |
2923 | stale_open: |
2924 | /* If no saved parent or already retried then can't retry */ | |
2925 | if (!save_parent.dentry || retried) | |
2926 | goto out; | |
2927 | ||
2928 | BUG_ON(save_parent.dentry != dir); | |
2929 | path_put(&nd->path); | |
2930 | nd->path = save_parent; | |
2931 | nd->inode = dir->d_inode; | |
2932 | save_parent.mnt = NULL; | |
2933 | save_parent.dentry = NULL; | |
64894cf8 | 2934 | if (got_write) { |
f60dc3db | 2935 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 2936 | got_write = false; |
f60dc3db MS |
2937 | } |
2938 | retried = true; | |
2939 | goto retry_lookup; | |
fb1cc555 AV |
2940 | } |
2941 | ||
60545d0d AV |
2942 | static int do_tmpfile(int dfd, struct filename *pathname, |
2943 | struct nameidata *nd, int flags, | |
2944 | const struct open_flags *op, | |
2945 | struct file *file, int *opened) | |
2946 | { | |
2947 | static const struct qstr name = QSTR_INIT("/", 1); | |
2948 | struct dentry *dentry, *child; | |
2949 | struct inode *dir; | |
2950 | int error = path_lookupat(dfd, pathname->name, | |
2951 | flags | LOOKUP_DIRECTORY, nd); | |
2952 | if (unlikely(error)) | |
2953 | return error; | |
2954 | error = mnt_want_write(nd->path.mnt); | |
2955 | if (unlikely(error)) | |
2956 | goto out; | |
2957 | /* we want directory to be writable */ | |
2958 | error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); | |
2959 | if (error) | |
2960 | goto out2; | |
2961 | dentry = nd->path.dentry; | |
2962 | dir = dentry->d_inode; | |
2963 | if (!dir->i_op->tmpfile) { | |
2964 | error = -EOPNOTSUPP; | |
2965 | goto out2; | |
2966 | } | |
2967 | child = d_alloc(dentry, &name); | |
2968 | if (unlikely(!child)) { | |
2969 | error = -ENOMEM; | |
2970 | goto out2; | |
2971 | } | |
2972 | nd->flags &= ~LOOKUP_DIRECTORY; | |
2973 | nd->flags |= op->intent; | |
2974 | dput(nd->path.dentry); | |
2975 | nd->path.dentry = child; | |
2976 | error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); | |
2977 | if (error) | |
2978 | goto out2; | |
2979 | audit_inode(pathname, nd->path.dentry, 0); | |
2980 | error = may_open(&nd->path, op->acc_mode, op->open_flag); | |
2981 | if (error) | |
2982 | goto out2; | |
2983 | file->f_path.mnt = nd->path.mnt; | |
2984 | error = finish_open(file, nd->path.dentry, NULL, opened); | |
2985 | if (error) | |
2986 | goto out2; | |
2987 | error = open_check_o_direct(file); | |
f4e0c30c | 2988 | if (error) { |
60545d0d | 2989 | fput(file); |
f4e0c30c AV |
2990 | } else if (!(op->open_flag & O_EXCL)) { |
2991 | struct inode *inode = file_inode(file); | |
2992 | spin_lock(&inode->i_lock); | |
2993 | inode->i_state |= I_LINKABLE; | |
2994 | spin_unlock(&inode->i_lock); | |
2995 | } | |
60545d0d AV |
2996 | out2: |
2997 | mnt_drop_write(nd->path.mnt); | |
2998 | out: | |
2999 | path_put(&nd->path); | |
3000 | return error; | |
3001 | } | |
3002 | ||
669abf4e | 3003 | static struct file *path_openat(int dfd, struct filename *pathname, |
73d049a4 | 3004 | struct nameidata *nd, const struct open_flags *op, int flags) |
1da177e4 | 3005 | { |
fe2d35ff | 3006 | struct file *base = NULL; |
30d90494 | 3007 | struct file *file; |
9850c056 | 3008 | struct path path; |
47237687 | 3009 | int opened = 0; |
13aab428 | 3010 | int error; |
31e6b01f | 3011 | |
30d90494 | 3012 | file = get_empty_filp(); |
1afc99be AV |
3013 | if (IS_ERR(file)) |
3014 | return file; | |
31e6b01f | 3015 | |
30d90494 | 3016 | file->f_flags = op->open_flag; |
31e6b01f | 3017 | |
bb458c64 | 3018 | if (unlikely(file->f_flags & __O_TMPFILE)) { |
60545d0d AV |
3019 | error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); |
3020 | goto out; | |
3021 | } | |
3022 | ||
669abf4e | 3023 | error = path_init(dfd, pathname->name, flags | LOOKUP_PARENT, nd, &base); |
31e6b01f | 3024 | if (unlikely(error)) |
2675a4eb | 3025 | goto out; |
31e6b01f | 3026 | |
fe2d35ff | 3027 | current->total_link_count = 0; |
669abf4e | 3028 | error = link_path_walk(pathname->name, nd); |
31e6b01f | 3029 | if (unlikely(error)) |
2675a4eb | 3030 | goto out; |
1da177e4 | 3031 | |
2675a4eb AV |
3032 | error = do_last(nd, &path, file, op, &opened, pathname); |
3033 | while (unlikely(error > 0)) { /* trailing symlink */ | |
7b9337aa | 3034 | struct path link = path; |
def4af30 | 3035 | void *cookie; |
574197e0 | 3036 | if (!(nd->flags & LOOKUP_FOLLOW)) { |
73d049a4 AV |
3037 | path_put_conditional(&path, nd); |
3038 | path_put(&nd->path); | |
2675a4eb | 3039 | error = -ELOOP; |
40b39136 AV |
3040 | break; |
3041 | } | |
800179c9 KC |
3042 | error = may_follow_link(&link, nd); |
3043 | if (unlikely(error)) | |
3044 | break; | |
73d049a4 AV |
3045 | nd->flags |= LOOKUP_PARENT; |
3046 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); | |
574197e0 | 3047 | error = follow_link(&link, nd, &cookie); |
c3e380b0 | 3048 | if (unlikely(error)) |
2675a4eb AV |
3049 | break; |
3050 | error = do_last(nd, &path, file, op, &opened, pathname); | |
574197e0 | 3051 | put_link(nd, &link, cookie); |
806b681c | 3052 | } |
10fa8e62 | 3053 | out: |
73d049a4 AV |
3054 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) |
3055 | path_put(&nd->root); | |
fe2d35ff AV |
3056 | if (base) |
3057 | fput(base); | |
2675a4eb AV |
3058 | if (!(opened & FILE_OPENED)) { |
3059 | BUG_ON(!error); | |
30d90494 | 3060 | put_filp(file); |
16b1c1cd | 3061 | } |
2675a4eb AV |
3062 | if (unlikely(error)) { |
3063 | if (error == -EOPENSTALE) { | |
3064 | if (flags & LOOKUP_RCU) | |
3065 | error = -ECHILD; | |
3066 | else | |
3067 | error = -ESTALE; | |
3068 | } | |
3069 | file = ERR_PTR(error); | |
3070 | } | |
3071 | return file; | |
1da177e4 LT |
3072 | } |
3073 | ||
669abf4e | 3074 | struct file *do_filp_open(int dfd, struct filename *pathname, |
f9652e10 | 3075 | const struct open_flags *op) |
13aab428 | 3076 | { |
73d049a4 | 3077 | struct nameidata nd; |
f9652e10 | 3078 | int flags = op->lookup_flags; |
13aab428 AV |
3079 | struct file *filp; |
3080 | ||
73d049a4 | 3081 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); |
13aab428 | 3082 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
73d049a4 | 3083 | filp = path_openat(dfd, pathname, &nd, op, flags); |
13aab428 | 3084 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
73d049a4 | 3085 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); |
13aab428 AV |
3086 | return filp; |
3087 | } | |
3088 | ||
73d049a4 | 3089 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
f9652e10 | 3090 | const char *name, const struct open_flags *op) |
73d049a4 AV |
3091 | { |
3092 | struct nameidata nd; | |
3093 | struct file *file; | |
669abf4e | 3094 | struct filename filename = { .name = name }; |
f9652e10 | 3095 | int flags = op->lookup_flags | LOOKUP_ROOT; |
73d049a4 AV |
3096 | |
3097 | nd.root.mnt = mnt; | |
3098 | nd.root.dentry = dentry; | |
3099 | ||
bcda7652 | 3100 | if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) |
73d049a4 AV |
3101 | return ERR_PTR(-ELOOP); |
3102 | ||
669abf4e | 3103 | file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU); |
73d049a4 | 3104 | if (unlikely(file == ERR_PTR(-ECHILD))) |
669abf4e | 3105 | file = path_openat(-1, &filename, &nd, op, flags); |
73d049a4 | 3106 | if (unlikely(file == ERR_PTR(-ESTALE))) |
669abf4e | 3107 | file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_REVAL); |
73d049a4 AV |
3108 | return file; |
3109 | } | |
3110 | ||
1ac12b4b JL |
3111 | struct dentry *kern_path_create(int dfd, const char *pathname, |
3112 | struct path *path, unsigned int lookup_flags) | |
1da177e4 | 3113 | { |
c663e5d8 | 3114 | struct dentry *dentry = ERR_PTR(-EEXIST); |
ed75e95d | 3115 | struct nameidata nd; |
c30dabfe | 3116 | int err2; |
1ac12b4b JL |
3117 | int error; |
3118 | bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); | |
3119 | ||
3120 | /* | |
3121 | * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any | |
3122 | * other flags passed in are ignored! | |
3123 | */ | |
3124 | lookup_flags &= LOOKUP_REVAL; | |
3125 | ||
3126 | error = do_path_lookup(dfd, pathname, LOOKUP_PARENT|lookup_flags, &nd); | |
ed75e95d AV |
3127 | if (error) |
3128 | return ERR_PTR(error); | |
1da177e4 | 3129 | |
c663e5d8 CH |
3130 | /* |
3131 | * Yucky last component or no last component at all? | |
3132 | * (foo/., foo/.., /////) | |
3133 | */ | |
ed75e95d AV |
3134 | if (nd.last_type != LAST_NORM) |
3135 | goto out; | |
3136 | nd.flags &= ~LOOKUP_PARENT; | |
3137 | nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; | |
c663e5d8 | 3138 | |
c30dabfe JK |
3139 | /* don't fail immediately if it's r/o, at least try to report other errors */ |
3140 | err2 = mnt_want_write(nd.path.mnt); | |
c663e5d8 CH |
3141 | /* |
3142 | * Do the final lookup. | |
3143 | */ | |
ed75e95d AV |
3144 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
3145 | dentry = lookup_hash(&nd); | |
1da177e4 | 3146 | if (IS_ERR(dentry)) |
a8104a9f | 3147 | goto unlock; |
c663e5d8 | 3148 | |
a8104a9f | 3149 | error = -EEXIST; |
e9baf6e5 | 3150 | if (dentry->d_inode) |
a8104a9f | 3151 | goto fail; |
c663e5d8 CH |
3152 | /* |
3153 | * Special case - lookup gave negative, but... we had foo/bar/ | |
3154 | * From the vfs_mknod() POV we just have a negative dentry - | |
3155 | * all is fine. Let's be bastards - you had / on the end, you've | |
3156 | * been asking for (non-existent) directory. -ENOENT for you. | |
3157 | */ | |
ed75e95d | 3158 | if (unlikely(!is_dir && nd.last.name[nd.last.len])) { |
a8104a9f | 3159 | error = -ENOENT; |
ed75e95d | 3160 | goto fail; |
e9baf6e5 | 3161 | } |
c30dabfe JK |
3162 | if (unlikely(err2)) { |
3163 | error = err2; | |
a8104a9f | 3164 | goto fail; |
c30dabfe | 3165 | } |
ed75e95d | 3166 | *path = nd.path; |
1da177e4 | 3167 | return dentry; |
1da177e4 | 3168 | fail: |
a8104a9f AV |
3169 | dput(dentry); |
3170 | dentry = ERR_PTR(error); | |
3171 | unlock: | |
ed75e95d | 3172 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
c30dabfe JK |
3173 | if (!err2) |
3174 | mnt_drop_write(nd.path.mnt); | |
ed75e95d AV |
3175 | out: |
3176 | path_put(&nd.path); | |
1da177e4 LT |
3177 | return dentry; |
3178 | } | |
dae6ad8f AV |
3179 | EXPORT_SYMBOL(kern_path_create); |
3180 | ||
921a1650 AV |
3181 | void done_path_create(struct path *path, struct dentry *dentry) |
3182 | { | |
3183 | dput(dentry); | |
3184 | mutex_unlock(&path->dentry->d_inode->i_mutex); | |
a8104a9f | 3185 | mnt_drop_write(path->mnt); |
921a1650 AV |
3186 | path_put(path); |
3187 | } | |
3188 | EXPORT_SYMBOL(done_path_create); | |
3189 | ||
1ac12b4b JL |
3190 | struct dentry *user_path_create(int dfd, const char __user *pathname, |
3191 | struct path *path, unsigned int lookup_flags) | |
dae6ad8f | 3192 | { |
91a27b2a | 3193 | struct filename *tmp = getname(pathname); |
dae6ad8f AV |
3194 | struct dentry *res; |
3195 | if (IS_ERR(tmp)) | |
3196 | return ERR_CAST(tmp); | |
1ac12b4b | 3197 | res = kern_path_create(dfd, tmp->name, path, lookup_flags); |
dae6ad8f AV |
3198 | putname(tmp); |
3199 | return res; | |
3200 | } | |
3201 | EXPORT_SYMBOL(user_path_create); | |
3202 | ||
1a67aafb | 3203 | int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
1da177e4 | 3204 | { |
a95164d9 | 3205 | int error = may_create(dir, dentry); |
1da177e4 LT |
3206 | |
3207 | if (error) | |
3208 | return error; | |
3209 | ||
975d6b39 | 3210 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) |
1da177e4 LT |
3211 | return -EPERM; |
3212 | ||
acfa4380 | 3213 | if (!dir->i_op->mknod) |
1da177e4 LT |
3214 | return -EPERM; |
3215 | ||
08ce5f16 SH |
3216 | error = devcgroup_inode_mknod(mode, dev); |
3217 | if (error) | |
3218 | return error; | |
3219 | ||
1da177e4 LT |
3220 | error = security_inode_mknod(dir, dentry, mode, dev); |
3221 | if (error) | |
3222 | return error; | |
3223 | ||
1da177e4 | 3224 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 3225 | if (!error) |
f38aa942 | 3226 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3227 | return error; |
3228 | } | |
3229 | ||
f69aac00 | 3230 | static int may_mknod(umode_t mode) |
463c3197 DH |
3231 | { |
3232 | switch (mode & S_IFMT) { | |
3233 | case S_IFREG: | |
3234 | case S_IFCHR: | |
3235 | case S_IFBLK: | |
3236 | case S_IFIFO: | |
3237 | case S_IFSOCK: | |
3238 | case 0: /* zero mode translates to S_IFREG */ | |
3239 | return 0; | |
3240 | case S_IFDIR: | |
3241 | return -EPERM; | |
3242 | default: | |
3243 | return -EINVAL; | |
3244 | } | |
3245 | } | |
3246 | ||
8208a22b | 3247 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, |
2e4d0924 | 3248 | unsigned, dev) |
1da177e4 | 3249 | { |
2ad94ae6 | 3250 | struct dentry *dentry; |
dae6ad8f AV |
3251 | struct path path; |
3252 | int error; | |
972567f1 | 3253 | unsigned int lookup_flags = 0; |
1da177e4 | 3254 | |
8e4bfca1 AV |
3255 | error = may_mknod(mode); |
3256 | if (error) | |
3257 | return error; | |
972567f1 JL |
3258 | retry: |
3259 | dentry = user_path_create(dfd, filename, &path, lookup_flags); | |
dae6ad8f AV |
3260 | if (IS_ERR(dentry)) |
3261 | return PTR_ERR(dentry); | |
2ad94ae6 | 3262 | |
dae6ad8f | 3263 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3264 | mode &= ~current_umask(); |
dae6ad8f | 3265 | error = security_path_mknod(&path, dentry, mode, dev); |
be6d3e56 | 3266 | if (error) |
a8104a9f | 3267 | goto out; |
463c3197 | 3268 | switch (mode & S_IFMT) { |
1da177e4 | 3269 | case 0: case S_IFREG: |
312b63fb | 3270 | error = vfs_create(path.dentry->d_inode,dentry,mode,true); |
1da177e4 LT |
3271 | break; |
3272 | case S_IFCHR: case S_IFBLK: | |
dae6ad8f | 3273 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
3274 | new_decode_dev(dev)); |
3275 | break; | |
3276 | case S_IFIFO: case S_IFSOCK: | |
dae6ad8f | 3277 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 3278 | break; |
1da177e4 | 3279 | } |
a8104a9f | 3280 | out: |
921a1650 | 3281 | done_path_create(&path, dentry); |
972567f1 JL |
3282 | if (retry_estale(error, lookup_flags)) { |
3283 | lookup_flags |= LOOKUP_REVAL; | |
3284 | goto retry; | |
3285 | } | |
1da177e4 LT |
3286 | return error; |
3287 | } | |
3288 | ||
8208a22b | 3289 | SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) |
5590ff0d UD |
3290 | { |
3291 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
3292 | } | |
3293 | ||
18bb1db3 | 3294 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
1da177e4 | 3295 | { |
a95164d9 | 3296 | int error = may_create(dir, dentry); |
8de52778 | 3297 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
3298 | |
3299 | if (error) | |
3300 | return error; | |
3301 | ||
acfa4380 | 3302 | if (!dir->i_op->mkdir) |
1da177e4 LT |
3303 | return -EPERM; |
3304 | ||
3305 | mode &= (S_IRWXUGO|S_ISVTX); | |
3306 | error = security_inode_mkdir(dir, dentry, mode); | |
3307 | if (error) | |
3308 | return error; | |
3309 | ||
8de52778 AV |
3310 | if (max_links && dir->i_nlink >= max_links) |
3311 | return -EMLINK; | |
3312 | ||
1da177e4 | 3313 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 3314 | if (!error) |
f38aa942 | 3315 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
3316 | return error; |
3317 | } | |
3318 | ||
a218d0fd | 3319 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) |
1da177e4 | 3320 | { |
6902d925 | 3321 | struct dentry *dentry; |
dae6ad8f AV |
3322 | struct path path; |
3323 | int error; | |
b76d8b82 | 3324 | unsigned int lookup_flags = LOOKUP_DIRECTORY; |
1da177e4 | 3325 | |
b76d8b82 JL |
3326 | retry: |
3327 | dentry = user_path_create(dfd, pathname, &path, lookup_flags); | |
6902d925 | 3328 | if (IS_ERR(dentry)) |
dae6ad8f | 3329 | return PTR_ERR(dentry); |
1da177e4 | 3330 | |
dae6ad8f | 3331 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3332 | mode &= ~current_umask(); |
dae6ad8f | 3333 | error = security_path_mkdir(&path, dentry, mode); |
a8104a9f AV |
3334 | if (!error) |
3335 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); | |
921a1650 | 3336 | done_path_create(&path, dentry); |
b76d8b82 JL |
3337 | if (retry_estale(error, lookup_flags)) { |
3338 | lookup_flags |= LOOKUP_REVAL; | |
3339 | goto retry; | |
3340 | } | |
1da177e4 LT |
3341 | return error; |
3342 | } | |
3343 | ||
a218d0fd | 3344 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) |
5590ff0d UD |
3345 | { |
3346 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
3347 | } | |
3348 | ||
1da177e4 | 3349 | /* |
a71905f0 | 3350 | * The dentry_unhash() helper will try to drop the dentry early: we |
c0d02594 | 3351 | * should have a usage count of 1 if we're the only user of this |
a71905f0 SW |
3352 | * dentry, and if that is true (possibly after pruning the dcache), |
3353 | * then we drop the dentry now. | |
1da177e4 LT |
3354 | * |
3355 | * A low-level filesystem can, if it choses, legally | |
3356 | * do a | |
3357 | * | |
3358 | * if (!d_unhashed(dentry)) | |
3359 | * return -EBUSY; | |
3360 | * | |
3361 | * if it cannot handle the case of removing a directory | |
3362 | * that is still in use by something else.. | |
3363 | */ | |
3364 | void dentry_unhash(struct dentry *dentry) | |
3365 | { | |
dc168427 | 3366 | shrink_dcache_parent(dentry); |
1da177e4 | 3367 | spin_lock(&dentry->d_lock); |
98474236 | 3368 | if (dentry->d_lockref.count == 1) |
1da177e4 LT |
3369 | __d_drop(dentry); |
3370 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
3371 | } |
3372 | ||
3373 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
3374 | { | |
3375 | int error = may_delete(dir, dentry, 1); | |
3376 | ||
3377 | if (error) | |
3378 | return error; | |
3379 | ||
acfa4380 | 3380 | if (!dir->i_op->rmdir) |
1da177e4 LT |
3381 | return -EPERM; |
3382 | ||
1d2ef590 | 3383 | dget(dentry); |
1b1dcc1b | 3384 | mutex_lock(&dentry->d_inode->i_mutex); |
912dbc15 SW |
3385 | |
3386 | error = -EBUSY; | |
1da177e4 | 3387 | if (d_mountpoint(dentry)) |
912dbc15 SW |
3388 | goto out; |
3389 | ||
3390 | error = security_inode_rmdir(dir, dentry); | |
3391 | if (error) | |
3392 | goto out; | |
3393 | ||
3cebde24 | 3394 | shrink_dcache_parent(dentry); |
912dbc15 SW |
3395 | error = dir->i_op->rmdir(dir, dentry); |
3396 | if (error) | |
3397 | goto out; | |
3398 | ||
3399 | dentry->d_inode->i_flags |= S_DEAD; | |
3400 | dont_mount(dentry); | |
3401 | ||
3402 | out: | |
1b1dcc1b | 3403 | mutex_unlock(&dentry->d_inode->i_mutex); |
1d2ef590 | 3404 | dput(dentry); |
912dbc15 | 3405 | if (!error) |
1da177e4 | 3406 | d_delete(dentry); |
1da177e4 LT |
3407 | return error; |
3408 | } | |
3409 | ||
5590ff0d | 3410 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
3411 | { |
3412 | int error = 0; | |
91a27b2a | 3413 | struct filename *name; |
1da177e4 LT |
3414 | struct dentry *dentry; |
3415 | struct nameidata nd; | |
c6ee9206 JL |
3416 | unsigned int lookup_flags = 0; |
3417 | retry: | |
3418 | name = user_path_parent(dfd, pathname, &nd, lookup_flags); | |
91a27b2a JL |
3419 | if (IS_ERR(name)) |
3420 | return PTR_ERR(name); | |
1da177e4 LT |
3421 | |
3422 | switch(nd.last_type) { | |
0612d9fb OH |
3423 | case LAST_DOTDOT: |
3424 | error = -ENOTEMPTY; | |
3425 | goto exit1; | |
3426 | case LAST_DOT: | |
3427 | error = -EINVAL; | |
3428 | goto exit1; | |
3429 | case LAST_ROOT: | |
3430 | error = -EBUSY; | |
3431 | goto exit1; | |
1da177e4 | 3432 | } |
0612d9fb OH |
3433 | |
3434 | nd.flags &= ~LOOKUP_PARENT; | |
c30dabfe JK |
3435 | error = mnt_want_write(nd.path.mnt); |
3436 | if (error) | |
3437 | goto exit1; | |
0612d9fb | 3438 | |
4ac91378 | 3439 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 3440 | dentry = lookup_hash(&nd); |
1da177e4 | 3441 | error = PTR_ERR(dentry); |
6902d925 DH |
3442 | if (IS_ERR(dentry)) |
3443 | goto exit2; | |
e6bc45d6 TT |
3444 | if (!dentry->d_inode) { |
3445 | error = -ENOENT; | |
3446 | goto exit3; | |
3447 | } | |
be6d3e56 KT |
3448 | error = security_path_rmdir(&nd.path, dentry); |
3449 | if (error) | |
c30dabfe | 3450 | goto exit3; |
4ac91378 | 3451 | error = vfs_rmdir(nd.path.dentry->d_inode, dentry); |
0622753b | 3452 | exit3: |
6902d925 DH |
3453 | dput(dentry); |
3454 | exit2: | |
4ac91378 | 3455 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
c30dabfe | 3456 | mnt_drop_write(nd.path.mnt); |
1da177e4 | 3457 | exit1: |
1d957f9b | 3458 | path_put(&nd.path); |
1da177e4 | 3459 | putname(name); |
c6ee9206 JL |
3460 | if (retry_estale(error, lookup_flags)) { |
3461 | lookup_flags |= LOOKUP_REVAL; | |
3462 | goto retry; | |
3463 | } | |
1da177e4 LT |
3464 | return error; |
3465 | } | |
3466 | ||
3cdad428 | 3467 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
3468 | { |
3469 | return do_rmdir(AT_FDCWD, pathname); | |
3470 | } | |
3471 | ||
1da177e4 LT |
3472 | int vfs_unlink(struct inode *dir, struct dentry *dentry) |
3473 | { | |
3474 | int error = may_delete(dir, dentry, 0); | |
3475 | ||
3476 | if (error) | |
3477 | return error; | |
3478 | ||
acfa4380 | 3479 | if (!dir->i_op->unlink) |
1da177e4 LT |
3480 | return -EPERM; |
3481 | ||
1b1dcc1b | 3482 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
3483 | if (d_mountpoint(dentry)) |
3484 | error = -EBUSY; | |
3485 | else { | |
3486 | error = security_inode_unlink(dir, dentry); | |
bec1052e | 3487 | if (!error) { |
1da177e4 | 3488 | error = dir->i_op->unlink(dir, dentry); |
bec1052e | 3489 | if (!error) |
d83c49f3 | 3490 | dont_mount(dentry); |
bec1052e | 3491 | } |
1da177e4 | 3492 | } |
1b1dcc1b | 3493 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
3494 | |
3495 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
3496 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
ece95912 | 3497 | fsnotify_link_count(dentry->d_inode); |
e234f35c | 3498 | d_delete(dentry); |
1da177e4 | 3499 | } |
0eeca283 | 3500 | |
1da177e4 LT |
3501 | return error; |
3502 | } | |
3503 | ||
3504 | /* | |
3505 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 3506 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
3507 | * writeout happening, and we don't want to prevent access to the directory |
3508 | * while waiting on the I/O. | |
3509 | */ | |
5590ff0d | 3510 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 3511 | { |
2ad94ae6 | 3512 | int error; |
91a27b2a | 3513 | struct filename *name; |
1da177e4 LT |
3514 | struct dentry *dentry; |
3515 | struct nameidata nd; | |
3516 | struct inode *inode = NULL; | |
5d18f813 JL |
3517 | unsigned int lookup_flags = 0; |
3518 | retry: | |
3519 | name = user_path_parent(dfd, pathname, &nd, lookup_flags); | |
91a27b2a JL |
3520 | if (IS_ERR(name)) |
3521 | return PTR_ERR(name); | |
2ad94ae6 | 3522 | |
1da177e4 LT |
3523 | error = -EISDIR; |
3524 | if (nd.last_type != LAST_NORM) | |
3525 | goto exit1; | |
0612d9fb OH |
3526 | |
3527 | nd.flags &= ~LOOKUP_PARENT; | |
c30dabfe JK |
3528 | error = mnt_want_write(nd.path.mnt); |
3529 | if (error) | |
3530 | goto exit1; | |
0612d9fb | 3531 | |
4ac91378 | 3532 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 3533 | dentry = lookup_hash(&nd); |
1da177e4 LT |
3534 | error = PTR_ERR(dentry); |
3535 | if (!IS_ERR(dentry)) { | |
3536 | /* Why not before? Because we want correct error value */ | |
50338b88 TE |
3537 | if (nd.last.name[nd.last.len]) |
3538 | goto slashes; | |
1da177e4 | 3539 | inode = dentry->d_inode; |
50338b88 | 3540 | if (!inode) |
e6bc45d6 TT |
3541 | goto slashes; |
3542 | ihold(inode); | |
be6d3e56 KT |
3543 | error = security_path_unlink(&nd.path, dentry); |
3544 | if (error) | |
c30dabfe | 3545 | goto exit2; |
4ac91378 | 3546 | error = vfs_unlink(nd.path.dentry->d_inode, dentry); |
c30dabfe | 3547 | exit2: |
1da177e4 LT |
3548 | dput(dentry); |
3549 | } | |
4ac91378 | 3550 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 LT |
3551 | if (inode) |
3552 | iput(inode); /* truncate the inode here */ | |
c30dabfe | 3553 | mnt_drop_write(nd.path.mnt); |
1da177e4 | 3554 | exit1: |
1d957f9b | 3555 | path_put(&nd.path); |
1da177e4 | 3556 | putname(name); |
5d18f813 JL |
3557 | if (retry_estale(error, lookup_flags)) { |
3558 | lookup_flags |= LOOKUP_REVAL; | |
3559 | inode = NULL; | |
3560 | goto retry; | |
3561 | } | |
1da177e4 LT |
3562 | return error; |
3563 | ||
3564 | slashes: | |
3565 | error = !dentry->d_inode ? -ENOENT : | |
3566 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; | |
3567 | goto exit2; | |
3568 | } | |
3569 | ||
2e4d0924 | 3570 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
3571 | { |
3572 | if ((flag & ~AT_REMOVEDIR) != 0) | |
3573 | return -EINVAL; | |
3574 | ||
3575 | if (flag & AT_REMOVEDIR) | |
3576 | return do_rmdir(dfd, pathname); | |
3577 | ||
3578 | return do_unlinkat(dfd, pathname); | |
3579 | } | |
3580 | ||
3480b257 | 3581 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
3582 | { |
3583 | return do_unlinkat(AT_FDCWD, pathname); | |
3584 | } | |
3585 | ||
db2e747b | 3586 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 3587 | { |
a95164d9 | 3588 | int error = may_create(dir, dentry); |
1da177e4 LT |
3589 | |
3590 | if (error) | |
3591 | return error; | |
3592 | ||
acfa4380 | 3593 | if (!dir->i_op->symlink) |
1da177e4 LT |
3594 | return -EPERM; |
3595 | ||
3596 | error = security_inode_symlink(dir, dentry, oldname); | |
3597 | if (error) | |
3598 | return error; | |
3599 | ||
1da177e4 | 3600 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 3601 | if (!error) |
f38aa942 | 3602 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3603 | return error; |
3604 | } | |
3605 | ||
2e4d0924 HC |
3606 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
3607 | int, newdfd, const char __user *, newname) | |
1da177e4 | 3608 | { |
2ad94ae6 | 3609 | int error; |
91a27b2a | 3610 | struct filename *from; |
6902d925 | 3611 | struct dentry *dentry; |
dae6ad8f | 3612 | struct path path; |
f46d3567 | 3613 | unsigned int lookup_flags = 0; |
1da177e4 LT |
3614 | |
3615 | from = getname(oldname); | |
2ad94ae6 | 3616 | if (IS_ERR(from)) |
1da177e4 | 3617 | return PTR_ERR(from); |
f46d3567 JL |
3618 | retry: |
3619 | dentry = user_path_create(newdfd, newname, &path, lookup_flags); | |
6902d925 DH |
3620 | error = PTR_ERR(dentry); |
3621 | if (IS_ERR(dentry)) | |
dae6ad8f | 3622 | goto out_putname; |
6902d925 | 3623 | |
91a27b2a | 3624 | error = security_path_symlink(&path, dentry, from->name); |
a8104a9f | 3625 | if (!error) |
91a27b2a | 3626 | error = vfs_symlink(path.dentry->d_inode, dentry, from->name); |
921a1650 | 3627 | done_path_create(&path, dentry); |
f46d3567 JL |
3628 | if (retry_estale(error, lookup_flags)) { |
3629 | lookup_flags |= LOOKUP_REVAL; | |
3630 | goto retry; | |
3631 | } | |
6902d925 | 3632 | out_putname: |
1da177e4 LT |
3633 | putname(from); |
3634 | return error; | |
3635 | } | |
3636 | ||
3480b257 | 3637 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
3638 | { |
3639 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
3640 | } | |
3641 | ||
1da177e4 LT |
3642 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
3643 | { | |
3644 | struct inode *inode = old_dentry->d_inode; | |
8de52778 | 3645 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
3646 | int error; |
3647 | ||
3648 | if (!inode) | |
3649 | return -ENOENT; | |
3650 | ||
a95164d9 | 3651 | error = may_create(dir, new_dentry); |
1da177e4 LT |
3652 | if (error) |
3653 | return error; | |
3654 | ||
3655 | if (dir->i_sb != inode->i_sb) | |
3656 | return -EXDEV; | |
3657 | ||
3658 | /* | |
3659 | * A link to an append-only or immutable file cannot be created. | |
3660 | */ | |
3661 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
3662 | return -EPERM; | |
acfa4380 | 3663 | if (!dir->i_op->link) |
1da177e4 | 3664 | return -EPERM; |
7e79eedb | 3665 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
3666 | return -EPERM; |
3667 | ||
3668 | error = security_inode_link(old_dentry, dir, new_dentry); | |
3669 | if (error) | |
3670 | return error; | |
3671 | ||
7e79eedb | 3672 | mutex_lock(&inode->i_mutex); |
aae8a97d | 3673 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
f4e0c30c | 3674 | if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) |
aae8a97d | 3675 | error = -ENOENT; |
8de52778 AV |
3676 | else if (max_links && inode->i_nlink >= max_links) |
3677 | error = -EMLINK; | |
aae8a97d AK |
3678 | else |
3679 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
f4e0c30c AV |
3680 | |
3681 | if (!error && (inode->i_state & I_LINKABLE)) { | |
3682 | spin_lock(&inode->i_lock); | |
3683 | inode->i_state &= ~I_LINKABLE; | |
3684 | spin_unlock(&inode->i_lock); | |
3685 | } | |
7e79eedb | 3686 | mutex_unlock(&inode->i_mutex); |
e31e14ec | 3687 | if (!error) |
7e79eedb | 3688 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
3689 | return error; |
3690 | } | |
3691 | ||
3692 | /* | |
3693 | * Hardlinks are often used in delicate situations. We avoid | |
3694 | * security-related surprises by not following symlinks on the | |
3695 | * newname. --KAB | |
3696 | * | |
3697 | * We don't follow them on the oldname either to be compatible | |
3698 | * with linux 2.0, and to avoid hard-linking to directories | |
3699 | * and other special files. --ADM | |
3700 | */ | |
2e4d0924 HC |
3701 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
3702 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
3703 | { |
3704 | struct dentry *new_dentry; | |
dae6ad8f | 3705 | struct path old_path, new_path; |
11a7b371 | 3706 | int how = 0; |
1da177e4 | 3707 | int error; |
1da177e4 | 3708 | |
11a7b371 | 3709 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
c04030e1 | 3710 | return -EINVAL; |
11a7b371 | 3711 | /* |
f0cc6ffb LT |
3712 | * To use null names we require CAP_DAC_READ_SEARCH |
3713 | * This ensures that not everyone will be able to create | |
3714 | * handlink using the passed filedescriptor. | |
11a7b371 | 3715 | */ |
f0cc6ffb LT |
3716 | if (flags & AT_EMPTY_PATH) { |
3717 | if (!capable(CAP_DAC_READ_SEARCH)) | |
3718 | return -ENOENT; | |
11a7b371 | 3719 | how = LOOKUP_EMPTY; |
f0cc6ffb | 3720 | } |
11a7b371 AK |
3721 | |
3722 | if (flags & AT_SYMLINK_FOLLOW) | |
3723 | how |= LOOKUP_FOLLOW; | |
442e31ca | 3724 | retry: |
11a7b371 | 3725 | error = user_path_at(olddfd, oldname, how, &old_path); |
1da177e4 | 3726 | if (error) |
2ad94ae6 AV |
3727 | return error; |
3728 | ||
442e31ca JL |
3729 | new_dentry = user_path_create(newdfd, newname, &new_path, |
3730 | (how & LOOKUP_REVAL)); | |
1da177e4 | 3731 | error = PTR_ERR(new_dentry); |
6902d925 | 3732 | if (IS_ERR(new_dentry)) |
dae6ad8f AV |
3733 | goto out; |
3734 | ||
3735 | error = -EXDEV; | |
3736 | if (old_path.mnt != new_path.mnt) | |
3737 | goto out_dput; | |
800179c9 KC |
3738 | error = may_linkat(&old_path); |
3739 | if (unlikely(error)) | |
3740 | goto out_dput; | |
dae6ad8f | 3741 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
be6d3e56 | 3742 | if (error) |
a8104a9f | 3743 | goto out_dput; |
dae6ad8f | 3744 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); |
75c3f29d | 3745 | out_dput: |
921a1650 | 3746 | done_path_create(&new_path, new_dentry); |
442e31ca JL |
3747 | if (retry_estale(error, how)) { |
3748 | how |= LOOKUP_REVAL; | |
3749 | goto retry; | |
3750 | } | |
1da177e4 | 3751 | out: |
2d8f3038 | 3752 | path_put(&old_path); |
1da177e4 LT |
3753 | |
3754 | return error; | |
3755 | } | |
3756 | ||
3480b257 | 3757 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 3758 | { |
c04030e1 | 3759 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
3760 | } |
3761 | ||
1da177e4 LT |
3762 | /* |
3763 | * The worst of all namespace operations - renaming directory. "Perverted" | |
3764 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
3765 | * Problems: | |
3766 | * a) we can get into loop creation. Check is done in is_subdir(). | |
3767 | * b) race potential - two innocent renames can create a loop together. | |
3768 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 3769 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 LT |
3770 | * story. |
3771 | * c) we have to lock _three_ objects - parents and victim (if it exists). | |
1b1dcc1b | 3772 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
3773 | * whether the target exists). Solution: try to be smart with locking |
3774 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 3775 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
3776 | * move will be locked. Thus we can rank directories by the tree |
3777 | * (ancestors first) and rank all non-directories after them. | |
3778 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 3779 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
3780 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
3781 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
3782 | * we'd better make sure that there's no link(2) for them. | |
e4eaac06 | 3783 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
1b1dcc1b | 3784 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 3785 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
c41b20e7 | 3786 | * ->i_mutex on parents, which works but leads to some truly excessive |
1da177e4 LT |
3787 | * locking]. |
3788 | */ | |
75c96f85 AB |
3789 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
3790 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
3791 | { |
3792 | int error = 0; | |
9055cba7 | 3793 | struct inode *target = new_dentry->d_inode; |
8de52778 | 3794 | unsigned max_links = new_dir->i_sb->s_max_links; |
1da177e4 LT |
3795 | |
3796 | /* | |
3797 | * If we are going to change the parent - check write permissions, | |
3798 | * we'll need to flip '..'. | |
3799 | */ | |
3800 | if (new_dir != old_dir) { | |
f419a2e3 | 3801 | error = inode_permission(old_dentry->d_inode, MAY_WRITE); |
1da177e4 LT |
3802 | if (error) |
3803 | return error; | |
3804 | } | |
3805 | ||
3806 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
3807 | if (error) | |
3808 | return error; | |
3809 | ||
1d2ef590 | 3810 | dget(new_dentry); |
d83c49f3 | 3811 | if (target) |
1b1dcc1b | 3812 | mutex_lock(&target->i_mutex); |
9055cba7 SW |
3813 | |
3814 | error = -EBUSY; | |
3815 | if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) | |
3816 | goto out; | |
3817 | ||
8de52778 AV |
3818 | error = -EMLINK; |
3819 | if (max_links && !target && new_dir != old_dir && | |
3820 | new_dir->i_nlink >= max_links) | |
3821 | goto out; | |
3822 | ||
3cebde24 SW |
3823 | if (target) |
3824 | shrink_dcache_parent(new_dentry); | |
9055cba7 SW |
3825 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
3826 | if (error) | |
3827 | goto out; | |
3828 | ||
1da177e4 | 3829 | if (target) { |
9055cba7 SW |
3830 | target->i_flags |= S_DEAD; |
3831 | dont_mount(new_dentry); | |
1da177e4 | 3832 | } |
9055cba7 SW |
3833 | out: |
3834 | if (target) | |
3835 | mutex_unlock(&target->i_mutex); | |
1d2ef590 | 3836 | dput(new_dentry); |
e31e14ec | 3837 | if (!error) |
349457cc MF |
3838 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
3839 | d_move(old_dentry,new_dentry); | |
1da177e4 LT |
3840 | return error; |
3841 | } | |
3842 | ||
75c96f85 AB |
3843 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
3844 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 | 3845 | { |
51892bbb | 3846 | struct inode *target = new_dentry->d_inode; |
1da177e4 LT |
3847 | int error; |
3848 | ||
3849 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
3850 | if (error) | |
3851 | return error; | |
3852 | ||
3853 | dget(new_dentry); | |
1da177e4 | 3854 | if (target) |
1b1dcc1b | 3855 | mutex_lock(&target->i_mutex); |
51892bbb SW |
3856 | |
3857 | error = -EBUSY; | |
1da177e4 | 3858 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
51892bbb SW |
3859 | goto out; |
3860 | ||
3861 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
3862 | if (error) | |
3863 | goto out; | |
3864 | ||
3865 | if (target) | |
3866 | dont_mount(new_dentry); | |
3867 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) | |
3868 | d_move(old_dentry, new_dentry); | |
3869 | out: | |
1da177e4 | 3870 | if (target) |
1b1dcc1b | 3871 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
3872 | dput(new_dentry); |
3873 | return error; | |
3874 | } | |
3875 | ||
3876 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, | |
3877 | struct inode *new_dir, struct dentry *new_dentry) | |
3878 | { | |
3879 | int error; | |
3880 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); | |
59b0df21 | 3881 | const unsigned char *old_name; |
1da177e4 LT |
3882 | |
3883 | if (old_dentry->d_inode == new_dentry->d_inode) | |
3884 | return 0; | |
3885 | ||
3886 | error = may_delete(old_dir, old_dentry, is_dir); | |
3887 | if (error) | |
3888 | return error; | |
3889 | ||
3890 | if (!new_dentry->d_inode) | |
a95164d9 | 3891 | error = may_create(new_dir, new_dentry); |
1da177e4 LT |
3892 | else |
3893 | error = may_delete(new_dir, new_dentry, is_dir); | |
3894 | if (error) | |
3895 | return error; | |
3896 | ||
acfa4380 | 3897 | if (!old_dir->i_op->rename) |
1da177e4 LT |
3898 | return -EPERM; |
3899 | ||
0eeca283 RL |
3900 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
3901 | ||
1da177e4 LT |
3902 | if (is_dir) |
3903 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); | |
3904 | else | |
3905 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); | |
123df294 AV |
3906 | if (!error) |
3907 | fsnotify_move(old_dir, new_dir, old_name, is_dir, | |
5a190ae6 | 3908 | new_dentry->d_inode, old_dentry); |
0eeca283 RL |
3909 | fsnotify_oldname_free(old_name); |
3910 | ||
1da177e4 LT |
3911 | return error; |
3912 | } | |
3913 | ||
2e4d0924 HC |
3914 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
3915 | int, newdfd, const char __user *, newname) | |
1da177e4 | 3916 | { |
2ad94ae6 AV |
3917 | struct dentry *old_dir, *new_dir; |
3918 | struct dentry *old_dentry, *new_dentry; | |
3919 | struct dentry *trap; | |
1da177e4 | 3920 | struct nameidata oldnd, newnd; |
91a27b2a JL |
3921 | struct filename *from; |
3922 | struct filename *to; | |
c6a94284 JL |
3923 | unsigned int lookup_flags = 0; |
3924 | bool should_retry = false; | |
2ad94ae6 | 3925 | int error; |
c6a94284 JL |
3926 | retry: |
3927 | from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags); | |
91a27b2a JL |
3928 | if (IS_ERR(from)) { |
3929 | error = PTR_ERR(from); | |
1da177e4 | 3930 | goto exit; |
91a27b2a | 3931 | } |
1da177e4 | 3932 | |
c6a94284 | 3933 | to = user_path_parent(newdfd, newname, &newnd, lookup_flags); |
91a27b2a JL |
3934 | if (IS_ERR(to)) { |
3935 | error = PTR_ERR(to); | |
1da177e4 | 3936 | goto exit1; |
91a27b2a | 3937 | } |
1da177e4 LT |
3938 | |
3939 | error = -EXDEV; | |
4ac91378 | 3940 | if (oldnd.path.mnt != newnd.path.mnt) |
1da177e4 LT |
3941 | goto exit2; |
3942 | ||
4ac91378 | 3943 | old_dir = oldnd.path.dentry; |
1da177e4 LT |
3944 | error = -EBUSY; |
3945 | if (oldnd.last_type != LAST_NORM) | |
3946 | goto exit2; | |
3947 | ||
4ac91378 | 3948 | new_dir = newnd.path.dentry; |
1da177e4 LT |
3949 | if (newnd.last_type != LAST_NORM) |
3950 | goto exit2; | |
3951 | ||
c30dabfe JK |
3952 | error = mnt_want_write(oldnd.path.mnt); |
3953 | if (error) | |
3954 | goto exit2; | |
3955 | ||
0612d9fb OH |
3956 | oldnd.flags &= ~LOOKUP_PARENT; |
3957 | newnd.flags &= ~LOOKUP_PARENT; | |
4e9ed2f8 | 3958 | newnd.flags |= LOOKUP_RENAME_TARGET; |
0612d9fb | 3959 | |
1da177e4 LT |
3960 | trap = lock_rename(new_dir, old_dir); |
3961 | ||
49705b77 | 3962 | old_dentry = lookup_hash(&oldnd); |
1da177e4 LT |
3963 | error = PTR_ERR(old_dentry); |
3964 | if (IS_ERR(old_dentry)) | |
3965 | goto exit3; | |
3966 | /* source must exist */ | |
3967 | error = -ENOENT; | |
3968 | if (!old_dentry->d_inode) | |
3969 | goto exit4; | |
3970 | /* unless the source is a directory trailing slashes give -ENOTDIR */ | |
3971 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { | |
3972 | error = -ENOTDIR; | |
3973 | if (oldnd.last.name[oldnd.last.len]) | |
3974 | goto exit4; | |
3975 | if (newnd.last.name[newnd.last.len]) | |
3976 | goto exit4; | |
3977 | } | |
3978 | /* source should not be ancestor of target */ | |
3979 | error = -EINVAL; | |
3980 | if (old_dentry == trap) | |
3981 | goto exit4; | |
49705b77 | 3982 | new_dentry = lookup_hash(&newnd); |
1da177e4 LT |
3983 | error = PTR_ERR(new_dentry); |
3984 | if (IS_ERR(new_dentry)) | |
3985 | goto exit4; | |
3986 | /* target should not be an ancestor of source */ | |
3987 | error = -ENOTEMPTY; | |
3988 | if (new_dentry == trap) | |
3989 | goto exit5; | |
3990 | ||
be6d3e56 KT |
3991 | error = security_path_rename(&oldnd.path, old_dentry, |
3992 | &newnd.path, new_dentry); | |
3993 | if (error) | |
c30dabfe | 3994 | goto exit5; |
1da177e4 LT |
3995 | error = vfs_rename(old_dir->d_inode, old_dentry, |
3996 | new_dir->d_inode, new_dentry); | |
3997 | exit5: | |
3998 | dput(new_dentry); | |
3999 | exit4: | |
4000 | dput(old_dentry); | |
4001 | exit3: | |
4002 | unlock_rename(new_dir, old_dir); | |
c30dabfe | 4003 | mnt_drop_write(oldnd.path.mnt); |
1da177e4 | 4004 | exit2: |
c6a94284 JL |
4005 | if (retry_estale(error, lookup_flags)) |
4006 | should_retry = true; | |
1d957f9b | 4007 | path_put(&newnd.path); |
2ad94ae6 | 4008 | putname(to); |
1da177e4 | 4009 | exit1: |
1d957f9b | 4010 | path_put(&oldnd.path); |
1da177e4 | 4011 | putname(from); |
c6a94284 JL |
4012 | if (should_retry) { |
4013 | should_retry = false; | |
4014 | lookup_flags |= LOOKUP_REVAL; | |
4015 | goto retry; | |
4016 | } | |
2ad94ae6 | 4017 | exit: |
1da177e4 LT |
4018 | return error; |
4019 | } | |
4020 | ||
a26eab24 | 4021 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
4022 | { |
4023 | return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); | |
4024 | } | |
4025 | ||
1da177e4 LT |
4026 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
4027 | { | |
4028 | int len; | |
4029 | ||
4030 | len = PTR_ERR(link); | |
4031 | if (IS_ERR(link)) | |
4032 | goto out; | |
4033 | ||
4034 | len = strlen(link); | |
4035 | if (len > (unsigned) buflen) | |
4036 | len = buflen; | |
4037 | if (copy_to_user(buffer, link, len)) | |
4038 | len = -EFAULT; | |
4039 | out: | |
4040 | return len; | |
4041 | } | |
4042 | ||
4043 | /* | |
4044 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
4045 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
4046 | * using) it for any given inode is up to filesystem. | |
4047 | */ | |
4048 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4049 | { | |
4050 | struct nameidata nd; | |
cc314eef | 4051 | void *cookie; |
694a1764 | 4052 | int res; |
cc314eef | 4053 | |
1da177e4 | 4054 | nd.depth = 0; |
cc314eef | 4055 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
694a1764 MS |
4056 | if (IS_ERR(cookie)) |
4057 | return PTR_ERR(cookie); | |
4058 | ||
4059 | res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); | |
4060 | if (dentry->d_inode->i_op->put_link) | |
4061 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); | |
4062 | return res; | |
1da177e4 LT |
4063 | } |
4064 | ||
4065 | int vfs_follow_link(struct nameidata *nd, const char *link) | |
4066 | { | |
4067 | return __vfs_follow_link(nd, link); | |
4068 | } | |
4069 | ||
4070 | /* get the link contents into pagecache */ | |
4071 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
4072 | { | |
ebd09abb DG |
4073 | char *kaddr; |
4074 | struct page *page; | |
1da177e4 | 4075 | struct address_space *mapping = dentry->d_inode->i_mapping; |
090d2b18 | 4076 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 4077 | if (IS_ERR(page)) |
6fe6900e | 4078 | return (char*)page; |
1da177e4 | 4079 | *ppage = page; |
ebd09abb DG |
4080 | kaddr = kmap(page); |
4081 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); | |
4082 | return kaddr; | |
1da177e4 LT |
4083 | } |
4084 | ||
4085 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4086 | { | |
4087 | struct page *page = NULL; | |
4088 | char *s = page_getlink(dentry, &page); | |
4089 | int res = vfs_readlink(dentry,buffer,buflen,s); | |
4090 | if (page) { | |
4091 | kunmap(page); | |
4092 | page_cache_release(page); | |
4093 | } | |
4094 | return res; | |
4095 | } | |
4096 | ||
cc314eef | 4097 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 4098 | { |
cc314eef | 4099 | struct page *page = NULL; |
1da177e4 | 4100 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 4101 | return page; |
1da177e4 LT |
4102 | } |
4103 | ||
cc314eef | 4104 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 4105 | { |
cc314eef LT |
4106 | struct page *page = cookie; |
4107 | ||
4108 | if (page) { | |
1da177e4 LT |
4109 | kunmap(page); |
4110 | page_cache_release(page); | |
1da177e4 LT |
4111 | } |
4112 | } | |
4113 | ||
54566b2c NP |
4114 | /* |
4115 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
4116 | */ | |
4117 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
4118 | { |
4119 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 4120 | struct page *page; |
afddba49 | 4121 | void *fsdata; |
beb497ab | 4122 | int err; |
1da177e4 | 4123 | char *kaddr; |
54566b2c NP |
4124 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
4125 | if (nofs) | |
4126 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 4127 | |
7e53cac4 | 4128 | retry: |
afddba49 | 4129 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 4130 | flags, &page, &fsdata); |
1da177e4 | 4131 | if (err) |
afddba49 NP |
4132 | goto fail; |
4133 | ||
e8e3c3d6 | 4134 | kaddr = kmap_atomic(page); |
1da177e4 | 4135 | memcpy(kaddr, symname, len-1); |
e8e3c3d6 | 4136 | kunmap_atomic(kaddr); |
afddba49 NP |
4137 | |
4138 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
4139 | page, fsdata); | |
1da177e4 LT |
4140 | if (err < 0) |
4141 | goto fail; | |
afddba49 NP |
4142 | if (err < len-1) |
4143 | goto retry; | |
4144 | ||
1da177e4 LT |
4145 | mark_inode_dirty(inode); |
4146 | return 0; | |
1da177e4 LT |
4147 | fail: |
4148 | return err; | |
4149 | } | |
4150 | ||
0adb25d2 KK |
4151 | int page_symlink(struct inode *inode, const char *symname, int len) |
4152 | { | |
4153 | return __page_symlink(inode, symname, len, | |
54566b2c | 4154 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
0adb25d2 KK |
4155 | } |
4156 | ||
92e1d5be | 4157 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
4158 | .readlink = generic_readlink, |
4159 | .follow_link = page_follow_link_light, | |
4160 | .put_link = page_put_link, | |
4161 | }; | |
4162 | ||
2d8f3038 | 4163 | EXPORT_SYMBOL(user_path_at); |
cc53ce53 | 4164 | EXPORT_SYMBOL(follow_down_one); |
1da177e4 LT |
4165 | EXPORT_SYMBOL(follow_down); |
4166 | EXPORT_SYMBOL(follow_up); | |
f6d2ac5c | 4167 | EXPORT_SYMBOL(get_write_access); /* nfsd */ |
1da177e4 | 4168 | EXPORT_SYMBOL(lock_rename); |
1da177e4 LT |
4169 | EXPORT_SYMBOL(lookup_one_len); |
4170 | EXPORT_SYMBOL(page_follow_link_light); | |
4171 | EXPORT_SYMBOL(page_put_link); | |
4172 | EXPORT_SYMBOL(page_readlink); | |
0adb25d2 | 4173 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 LT |
4174 | EXPORT_SYMBOL(page_symlink); |
4175 | EXPORT_SYMBOL(page_symlink_inode_operations); | |
d1811465 | 4176 | EXPORT_SYMBOL(kern_path); |
16f18200 | 4177 | EXPORT_SYMBOL(vfs_path_lookup); |
f419a2e3 | 4178 | EXPORT_SYMBOL(inode_permission); |
1da177e4 LT |
4179 | EXPORT_SYMBOL(unlock_rename); |
4180 | EXPORT_SYMBOL(vfs_create); | |
4181 | EXPORT_SYMBOL(vfs_follow_link); | |
4182 | EXPORT_SYMBOL(vfs_link); | |
4183 | EXPORT_SYMBOL(vfs_mkdir); | |
4184 | EXPORT_SYMBOL(vfs_mknod); | |
4185 | EXPORT_SYMBOL(generic_permission); | |
4186 | EXPORT_SYMBOL(vfs_readlink); | |
4187 | EXPORT_SYMBOL(vfs_rename); | |
4188 | EXPORT_SYMBOL(vfs_rmdir); | |
4189 | EXPORT_SYMBOL(vfs_symlink); | |
4190 | EXPORT_SYMBOL(vfs_unlink); | |
4191 | EXPORT_SYMBOL(dentry_unhash); | |
4192 | EXPORT_SYMBOL(generic_readlink); |