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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> | |
18 | #include <linux/module.h> | |
19 | #include <linux/slab.h> | |
20 | #include <linux/fs.h> | |
21 | #include <linux/namei.h> | |
1da177e4 | 22 | #include <linux/pagemap.h> |
0eeca283 | 23 | #include <linux/fsnotify.h> |
1da177e4 LT |
24 | #include <linux/personality.h> |
25 | #include <linux/security.h> | |
6146f0d5 | 26 | #include <linux/ima.h> |
1da177e4 LT |
27 | #include <linux/syscalls.h> |
28 | #include <linux/mount.h> | |
29 | #include <linux/audit.h> | |
16f7e0fe | 30 | #include <linux/capability.h> |
834f2a4a | 31 | #include <linux/file.h> |
5590ff0d | 32 | #include <linux/fcntl.h> |
08ce5f16 | 33 | #include <linux/device_cgroup.h> |
5ad4e53b | 34 | #include <linux/fs_struct.h> |
e77819e5 | 35 | #include <linux/posix_acl.h> |
1da177e4 LT |
36 | #include <asm/uaccess.h> |
37 | ||
e81e3f4d EP |
38 | #include "internal.h" |
39 | ||
1da177e4 LT |
40 | /* [Feb-1997 T. Schoebel-Theuer] |
41 | * Fundamental changes in the pathname lookup mechanisms (namei) | |
42 | * were necessary because of omirr. The reason is that omirr needs | |
43 | * to know the _real_ pathname, not the user-supplied one, in case | |
44 | * of symlinks (and also when transname replacements occur). | |
45 | * | |
46 | * The new code replaces the old recursive symlink resolution with | |
47 | * an iterative one (in case of non-nested symlink chains). It does | |
48 | * this with calls to <fs>_follow_link(). | |
49 | * As a side effect, dir_namei(), _namei() and follow_link() are now | |
50 | * replaced with a single function lookup_dentry() that can handle all | |
51 | * the special cases of the former code. | |
52 | * | |
53 | * With the new dcache, the pathname is stored at each inode, at least as | |
54 | * long as the refcount of the inode is positive. As a side effect, the | |
55 | * size of the dcache depends on the inode cache and thus is dynamic. | |
56 | * | |
57 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink | |
58 | * resolution to correspond with current state of the code. | |
59 | * | |
60 | * Note that the symlink resolution is not *completely* iterative. | |
61 | * There is still a significant amount of tail- and mid- recursion in | |
62 | * the algorithm. Also, note that <fs>_readlink() is not used in | |
63 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() | |
64 | * may return different results than <fs>_follow_link(). Many virtual | |
65 | * filesystems (including /proc) exhibit this behavior. | |
66 | */ | |
67 | ||
68 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: | |
69 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL | |
70 | * and the name already exists in form of a symlink, try to create the new | |
71 | * name indicated by the symlink. The old code always complained that the | |
72 | * name already exists, due to not following the symlink even if its target | |
73 | * is nonexistent. The new semantics affects also mknod() and link() when | |
25985edc | 74 | * the name is a symlink pointing to a non-existent name. |
1da177e4 LT |
75 | * |
76 | * I don't know which semantics is the right one, since I have no access | |
77 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" | |
78 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the | |
79 | * "old" one. Personally, I think the new semantics is much more logical. | |
80 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing | |
81 | * file does succeed in both HP-UX and SunOs, but not in Solaris | |
82 | * and in the old Linux semantics. | |
83 | */ | |
84 | ||
85 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink | |
86 | * semantics. See the comments in "open_namei" and "do_link" below. | |
87 | * | |
88 | * [10-Sep-98 Alan Modra] Another symlink change. | |
89 | */ | |
90 | ||
91 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: | |
92 | * inside the path - always follow. | |
93 | * in the last component in creation/removal/renaming - never follow. | |
94 | * if LOOKUP_FOLLOW passed - follow. | |
95 | * if the pathname has trailing slashes - follow. | |
96 | * otherwise - don't follow. | |
97 | * (applied in that order). | |
98 | * | |
99 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT | |
100 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. | |
101 | * During the 2.4 we need to fix the userland stuff depending on it - | |
102 | * hopefully we will be able to get rid of that wart in 2.5. So far only | |
103 | * XEmacs seems to be relying on it... | |
104 | */ | |
105 | /* | |
106 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) | |
a11f3a05 | 107 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
1da177e4 LT |
108 | * any extra contention... |
109 | */ | |
110 | ||
111 | /* In order to reduce some races, while at the same time doing additional | |
112 | * checking and hopefully speeding things up, we copy filenames to the | |
113 | * kernel data space before using them.. | |
114 | * | |
115 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). | |
116 | * PATH_MAX includes the nul terminator --RR. | |
117 | */ | |
858119e1 | 118 | static int do_getname(const char __user *filename, char *page) |
1da177e4 LT |
119 | { |
120 | int retval; | |
121 | unsigned long len = PATH_MAX; | |
122 | ||
123 | if (!segment_eq(get_fs(), KERNEL_DS)) { | |
124 | if ((unsigned long) filename >= TASK_SIZE) | |
125 | return -EFAULT; | |
126 | if (TASK_SIZE - (unsigned long) filename < PATH_MAX) | |
127 | len = TASK_SIZE - (unsigned long) filename; | |
128 | } | |
129 | ||
130 | retval = strncpy_from_user(page, filename, len); | |
131 | if (retval > 0) { | |
132 | if (retval < len) | |
133 | return 0; | |
134 | return -ENAMETOOLONG; | |
135 | } else if (!retval) | |
136 | retval = -ENOENT; | |
137 | return retval; | |
138 | } | |
139 | ||
f52e0c11 | 140 | static char *getname_flags(const char __user * filename, int flags) |
1da177e4 LT |
141 | { |
142 | char *tmp, *result; | |
143 | ||
144 | result = ERR_PTR(-ENOMEM); | |
145 | tmp = __getname(); | |
146 | if (tmp) { | |
147 | int retval = do_getname(filename, tmp); | |
148 | ||
149 | result = tmp; | |
150 | if (retval < 0) { | |
f52e0c11 AV |
151 | if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) { |
152 | __putname(tmp); | |
153 | result = ERR_PTR(retval); | |
154 | } | |
1da177e4 LT |
155 | } |
156 | } | |
157 | audit_getname(result); | |
158 | return result; | |
159 | } | |
160 | ||
f52e0c11 AV |
161 | char *getname(const char __user * filename) |
162 | { | |
163 | return getname_flags(filename, 0); | |
164 | } | |
165 | ||
1da177e4 LT |
166 | #ifdef CONFIG_AUDITSYSCALL |
167 | void putname(const char *name) | |
168 | { | |
5ac3a9c2 | 169 | if (unlikely(!audit_dummy_context())) |
1da177e4 LT |
170 | audit_putname(name); |
171 | else | |
172 | __putname(name); | |
173 | } | |
174 | EXPORT_SYMBOL(putname); | |
175 | #endif | |
176 | ||
e77819e5 LT |
177 | static int check_acl(struct inode *inode, int mask) |
178 | { | |
179 | struct posix_acl *acl; | |
180 | ||
181 | /* | |
182 | * Under RCU walk, we cannot even do a "get_cached_acl()", | |
183 | * because that involves locking and getting a refcount on | |
184 | * a cached ACL. | |
185 | * | |
186 | * So the only case we handle during RCU walking is the | |
187 | * case of a cached "no ACL at all", which needs no locks | |
188 | * or refcounts. | |
189 | */ | |
190 | if (mask & MAY_NOT_BLOCK) { | |
191 | if (negative_cached_acl(inode, ACL_TYPE_ACCESS)) | |
192 | return -EAGAIN; | |
193 | return -ECHILD; | |
194 | } | |
195 | ||
196 | acl = get_cached_acl(inode, ACL_TYPE_ACCESS); | |
197 | ||
198 | /* | |
199 | * A filesystem can force a ACL callback by just never | |
200 | * filling the ACL cache. But normally you'd fill the | |
201 | * cache either at inode instantiation time, or on the | |
202 | * first ->check_acl call. | |
203 | * | |
204 | * If the filesystem doesn't have a check_acl() function | |
205 | * at all, we'll just create the negative cache entry. | |
206 | */ | |
207 | if (acl == ACL_NOT_CACHED) { | |
208 | if (inode->i_op->check_acl) | |
209 | return inode->i_op->check_acl(inode, mask); | |
210 | ||
211 | set_cached_acl(inode, ACL_TYPE_ACCESS, NULL); | |
212 | return -EAGAIN; | |
213 | } | |
214 | ||
215 | if (acl) { | |
216 | int error = posix_acl_permission(inode, acl, mask); | |
217 | posix_acl_release(acl); | |
218 | return error; | |
219 | } | |
220 | ||
221 | return -EAGAIN; | |
222 | } | |
223 | ||
5909ccaa LT |
224 | /* |
225 | * This does basic POSIX ACL permission checking | |
1da177e4 | 226 | */ |
7e40145e | 227 | static int acl_permission_check(struct inode *inode, int mask) |
1da177e4 | 228 | { |
26cf46be | 229 | unsigned int mode = inode->i_mode; |
1da177e4 | 230 | |
9c2c7039 | 231 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK; |
e6305c43 | 232 | |
e795b717 SH |
233 | if (current_user_ns() != inode_userns(inode)) |
234 | goto other_perms; | |
235 | ||
da9592ed | 236 | if (current_fsuid() == inode->i_uid) |
1da177e4 LT |
237 | mode >>= 6; |
238 | else { | |
e77819e5 | 239 | if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { |
7e40145e | 240 | int error = check_acl(inode, mask); |
b74c79e9 NP |
241 | if (error != -EAGAIN) |
242 | return error; | |
1da177e4 LT |
243 | } |
244 | ||
245 | if (in_group_p(inode->i_gid)) | |
246 | mode >>= 3; | |
247 | } | |
248 | ||
e795b717 | 249 | other_perms: |
1da177e4 LT |
250 | /* |
251 | * If the DACs are ok we don't need any capability check. | |
252 | */ | |
9c2c7039 | 253 | if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) |
1da177e4 | 254 | return 0; |
5909ccaa LT |
255 | return -EACCES; |
256 | } | |
257 | ||
258 | /** | |
b74c79e9 | 259 | * generic_permission - check for access rights on a Posix-like filesystem |
5909ccaa LT |
260 | * @inode: inode to check access rights for |
261 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
5909ccaa LT |
262 | * |
263 | * Used to check for read/write/execute permissions on a file. | |
264 | * We use "fsuid" for this, letting us set arbitrary permissions | |
265 | * for filesystem access without changing the "normal" uids which | |
b74c79e9 NP |
266 | * are used for other things. |
267 | * | |
268 | * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk | |
269 | * request cannot be satisfied (eg. requires blocking or too much complexity). | |
270 | * It would then be called again in ref-walk mode. | |
5909ccaa | 271 | */ |
2830ba7f | 272 | int generic_permission(struct inode *inode, int mask) |
5909ccaa LT |
273 | { |
274 | int ret; | |
275 | ||
276 | /* | |
277 | * Do the basic POSIX ACL permission checks. | |
278 | */ | |
7e40145e | 279 | ret = acl_permission_check(inode, mask); |
5909ccaa LT |
280 | if (ret != -EACCES) |
281 | return ret; | |
1da177e4 | 282 | |
d594e7ec AV |
283 | if (S_ISDIR(inode->i_mode)) { |
284 | /* DACs are overridable for directories */ | |
285 | if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) | |
286 | return 0; | |
287 | if (!(mask & MAY_WRITE)) | |
288 | if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) | |
289 | return 0; | |
290 | return -EACCES; | |
291 | } | |
1da177e4 LT |
292 | /* |
293 | * Read/write DACs are always overridable. | |
d594e7ec AV |
294 | * Executable DACs are overridable when there is |
295 | * at least one exec bit set. | |
1da177e4 | 296 | */ |
d594e7ec | 297 | if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) |
e795b717 | 298 | if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) |
1da177e4 LT |
299 | return 0; |
300 | ||
301 | /* | |
302 | * Searching includes executable on directories, else just read. | |
303 | */ | |
7ea66001 | 304 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
d594e7ec | 305 | if (mask == MAY_READ) |
e795b717 | 306 | if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) |
1da177e4 LT |
307 | return 0; |
308 | ||
309 | return -EACCES; | |
310 | } | |
311 | ||
cb23beb5 CH |
312 | /** |
313 | * inode_permission - check for access rights to a given inode | |
314 | * @inode: inode to check permission on | |
315 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
316 | * | |
317 | * Used to check for read/write/execute permissions on an inode. | |
318 | * We use "fsuid" for this, letting us set arbitrary permissions | |
319 | * for filesystem access without changing the "normal" uids which | |
320 | * are used for other things. | |
321 | */ | |
f419a2e3 | 322 | int inode_permission(struct inode *inode, int mask) |
1da177e4 | 323 | { |
e6305c43 | 324 | int retval; |
1da177e4 LT |
325 | |
326 | if (mask & MAY_WRITE) { | |
22590e41 | 327 | umode_t mode = inode->i_mode; |
1da177e4 LT |
328 | |
329 | /* | |
330 | * Nobody gets write access to a read-only fs. | |
331 | */ | |
332 | if (IS_RDONLY(inode) && | |
333 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
334 | return -EROFS; | |
335 | ||
336 | /* | |
337 | * Nobody gets write access to an immutable file. | |
338 | */ | |
339 | if (IS_IMMUTABLE(inode)) | |
340 | return -EACCES; | |
341 | } | |
342 | ||
acfa4380 | 343 | if (inode->i_op->permission) |
10556cb2 | 344 | retval = inode->i_op->permission(inode, mask); |
f696a365 | 345 | else |
2830ba7f | 346 | retval = generic_permission(inode, mask); |
f696a365 | 347 | |
1da177e4 LT |
348 | if (retval) |
349 | return retval; | |
350 | ||
08ce5f16 SH |
351 | retval = devcgroup_inode_permission(inode, mask); |
352 | if (retval) | |
353 | return retval; | |
354 | ||
d09ca739 | 355 | return security_inode_permission(inode, mask); |
1da177e4 LT |
356 | } |
357 | ||
5dd784d0 JB |
358 | /** |
359 | * path_get - get a reference to a path | |
360 | * @path: path to get the reference to | |
361 | * | |
362 | * Given a path increment the reference count to the dentry and the vfsmount. | |
363 | */ | |
364 | void path_get(struct path *path) | |
365 | { | |
366 | mntget(path->mnt); | |
367 | dget(path->dentry); | |
368 | } | |
369 | EXPORT_SYMBOL(path_get); | |
370 | ||
1d957f9b JB |
371 | /** |
372 | * path_put - put a reference to a path | |
373 | * @path: path to put the reference to | |
374 | * | |
375 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
376 | */ | |
377 | void path_put(struct path *path) | |
1da177e4 | 378 | { |
1d957f9b JB |
379 | dput(path->dentry); |
380 | mntput(path->mnt); | |
1da177e4 | 381 | } |
1d957f9b | 382 | EXPORT_SYMBOL(path_put); |
1da177e4 | 383 | |
19660af7 | 384 | /* |
31e6b01f | 385 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
19660af7 AV |
386 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
387 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab | |
388 | * normal reference counts on dentries and vfsmounts to transition to rcu-walk | |
389 | * mode. Refcounts are grabbed at the last known good point before rcu-walk | |
390 | * got stuck, so ref-walk may continue from there. If this is not successful | |
391 | * (eg. a seqcount has changed), then failure is returned and it's up to caller | |
392 | * to restart the path walk from the beginning in ref-walk mode. | |
31e6b01f | 393 | */ |
31e6b01f NP |
394 | |
395 | /** | |
19660af7 AV |
396 | * unlazy_walk - try to switch to ref-walk mode. |
397 | * @nd: nameidata pathwalk data | |
398 | * @dentry: child of nd->path.dentry or NULL | |
39191628 | 399 | * Returns: 0 on success, -ECHILD on failure |
31e6b01f | 400 | * |
19660af7 AV |
401 | * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry |
402 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on | |
403 | * @nd or NULL. Must be called from rcu-walk context. | |
31e6b01f | 404 | */ |
19660af7 | 405 | static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) |
31e6b01f NP |
406 | { |
407 | struct fs_struct *fs = current->fs; | |
408 | struct dentry *parent = nd->path.dentry; | |
5b6ca027 | 409 | int want_root = 0; |
31e6b01f NP |
410 | |
411 | BUG_ON(!(nd->flags & LOOKUP_RCU)); | |
5b6ca027 AV |
412 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
413 | want_root = 1; | |
31e6b01f NP |
414 | spin_lock(&fs->lock); |
415 | if (nd->root.mnt != fs->root.mnt || | |
416 | nd->root.dentry != fs->root.dentry) | |
417 | goto err_root; | |
418 | } | |
419 | spin_lock(&parent->d_lock); | |
19660af7 AV |
420 | if (!dentry) { |
421 | if (!__d_rcu_to_refcount(parent, nd->seq)) | |
422 | goto err_parent; | |
423 | BUG_ON(nd->inode != parent->d_inode); | |
424 | } else { | |
94c0d4ec AV |
425 | if (dentry->d_parent != parent) |
426 | goto err_parent; | |
19660af7 AV |
427 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
428 | if (!__d_rcu_to_refcount(dentry, nd->seq)) | |
429 | goto err_child; | |
430 | /* | |
431 | * If the sequence check on the child dentry passed, then | |
432 | * the child has not been removed from its parent. This | |
433 | * means the parent dentry must be valid and able to take | |
434 | * a reference at this point. | |
435 | */ | |
436 | BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); | |
437 | BUG_ON(!parent->d_count); | |
438 | parent->d_count++; | |
439 | spin_unlock(&dentry->d_lock); | |
440 | } | |
31e6b01f | 441 | spin_unlock(&parent->d_lock); |
5b6ca027 | 442 | if (want_root) { |
31e6b01f NP |
443 | path_get(&nd->root); |
444 | spin_unlock(&fs->lock); | |
445 | } | |
446 | mntget(nd->path.mnt); | |
447 | ||
448 | rcu_read_unlock(); | |
449 | br_read_unlock(vfsmount_lock); | |
450 | nd->flags &= ~LOOKUP_RCU; | |
451 | return 0; | |
19660af7 AV |
452 | |
453 | err_child: | |
31e6b01f | 454 | spin_unlock(&dentry->d_lock); |
19660af7 | 455 | err_parent: |
31e6b01f NP |
456 | spin_unlock(&parent->d_lock); |
457 | err_root: | |
5b6ca027 | 458 | if (want_root) |
31e6b01f NP |
459 | spin_unlock(&fs->lock); |
460 | return -ECHILD; | |
461 | } | |
462 | ||
834f2a4a TM |
463 | /** |
464 | * release_open_intent - free up open intent resources | |
465 | * @nd: pointer to nameidata | |
466 | */ | |
467 | void release_open_intent(struct nameidata *nd) | |
468 | { | |
2dab5974 LT |
469 | struct file *file = nd->intent.open.file; |
470 | ||
471 | if (file && !IS_ERR(file)) { | |
472 | if (file->f_path.dentry == NULL) | |
473 | put_filp(file); | |
474 | else | |
475 | fput(file); | |
476 | } | |
834f2a4a TM |
477 | } |
478 | ||
f60aef7e | 479 | static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) |
34286d66 | 480 | { |
f60aef7e | 481 | return dentry->d_op->d_revalidate(dentry, nd); |
34286d66 NP |
482 | } |
483 | ||
9f1fafee AV |
484 | /** |
485 | * complete_walk - successful completion of path walk | |
486 | * @nd: pointer nameidata | |
39159de2 | 487 | * |
9f1fafee AV |
488 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
489 | * Revalidate the final result, unless we'd already done that during | |
490 | * the path walk or the filesystem doesn't ask for it. Return 0 on | |
491 | * success, -error on failure. In case of failure caller does not | |
492 | * need to drop nd->path. | |
39159de2 | 493 | */ |
9f1fafee | 494 | static int complete_walk(struct nameidata *nd) |
39159de2 | 495 | { |
16c2cd71 | 496 | struct dentry *dentry = nd->path.dentry; |
39159de2 | 497 | int status; |
39159de2 | 498 | |
9f1fafee AV |
499 | if (nd->flags & LOOKUP_RCU) { |
500 | nd->flags &= ~LOOKUP_RCU; | |
501 | if (!(nd->flags & LOOKUP_ROOT)) | |
502 | nd->root.mnt = NULL; | |
503 | spin_lock(&dentry->d_lock); | |
504 | if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { | |
505 | spin_unlock(&dentry->d_lock); | |
506 | rcu_read_unlock(); | |
507 | br_read_unlock(vfsmount_lock); | |
508 | return -ECHILD; | |
509 | } | |
510 | BUG_ON(nd->inode != dentry->d_inode); | |
511 | spin_unlock(&dentry->d_lock); | |
512 | mntget(nd->path.mnt); | |
513 | rcu_read_unlock(); | |
514 | br_read_unlock(vfsmount_lock); | |
515 | } | |
516 | ||
16c2cd71 AV |
517 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
518 | return 0; | |
519 | ||
520 | if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) | |
39159de2 JL |
521 | return 0; |
522 | ||
16c2cd71 AV |
523 | if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) |
524 | return 0; | |
525 | ||
526 | /* Note: we do not d_invalidate() */ | |
34286d66 | 527 | status = d_revalidate(dentry, nd); |
39159de2 JL |
528 | if (status > 0) |
529 | return 0; | |
530 | ||
16c2cd71 | 531 | if (!status) |
39159de2 | 532 | status = -ESTALE; |
16c2cd71 | 533 | |
9f1fafee | 534 | path_put(&nd->path); |
39159de2 JL |
535 | return status; |
536 | } | |
537 | ||
2a737871 AV |
538 | static __always_inline void set_root(struct nameidata *nd) |
539 | { | |
f7ad3c6b MS |
540 | if (!nd->root.mnt) |
541 | get_fs_root(current->fs, &nd->root); | |
2a737871 AV |
542 | } |
543 | ||
6de88d72 AV |
544 | static int link_path_walk(const char *, struct nameidata *); |
545 | ||
31e6b01f NP |
546 | static __always_inline void set_root_rcu(struct nameidata *nd) |
547 | { | |
548 | if (!nd->root.mnt) { | |
549 | struct fs_struct *fs = current->fs; | |
c28cc364 NP |
550 | unsigned seq; |
551 | ||
552 | do { | |
553 | seq = read_seqcount_begin(&fs->seq); | |
554 | nd->root = fs->root; | |
c1530019 | 555 | nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); |
c28cc364 | 556 | } while (read_seqcount_retry(&fs->seq, seq)); |
31e6b01f NP |
557 | } |
558 | } | |
559 | ||
f1662356 | 560 | static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
1da177e4 | 561 | { |
31e6b01f NP |
562 | int ret; |
563 | ||
1da177e4 LT |
564 | if (IS_ERR(link)) |
565 | goto fail; | |
566 | ||
567 | if (*link == '/') { | |
2a737871 | 568 | set_root(nd); |
1d957f9b | 569 | path_put(&nd->path); |
2a737871 AV |
570 | nd->path = nd->root; |
571 | path_get(&nd->root); | |
16c2cd71 | 572 | nd->flags |= LOOKUP_JUMPED; |
1da177e4 | 573 | } |
31e6b01f | 574 | nd->inode = nd->path.dentry->d_inode; |
b4091d5f | 575 | |
31e6b01f NP |
576 | ret = link_path_walk(link, nd); |
577 | return ret; | |
1da177e4 | 578 | fail: |
1d957f9b | 579 | path_put(&nd->path); |
1da177e4 LT |
580 | return PTR_ERR(link); |
581 | } | |
582 | ||
1d957f9b | 583 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
584 | { |
585 | dput(path->dentry); | |
4ac91378 | 586 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
587 | mntput(path->mnt); |
588 | } | |
589 | ||
7b9337aa NP |
590 | static inline void path_to_nameidata(const struct path *path, |
591 | struct nameidata *nd) | |
051d3812 | 592 | { |
31e6b01f NP |
593 | if (!(nd->flags & LOOKUP_RCU)) { |
594 | dput(nd->path.dentry); | |
595 | if (nd->path.mnt != path->mnt) | |
596 | mntput(nd->path.mnt); | |
9a229683 | 597 | } |
31e6b01f | 598 | nd->path.mnt = path->mnt; |
4ac91378 | 599 | nd->path.dentry = path->dentry; |
051d3812 IK |
600 | } |
601 | ||
574197e0 AV |
602 | static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) |
603 | { | |
604 | struct inode *inode = link->dentry->d_inode; | |
605 | if (!IS_ERR(cookie) && inode->i_op->put_link) | |
606 | inode->i_op->put_link(link->dentry, nd, cookie); | |
607 | path_put(link); | |
608 | } | |
609 | ||
def4af30 | 610 | static __always_inline int |
574197e0 | 611 | follow_link(struct path *link, struct nameidata *nd, void **p) |
1da177e4 LT |
612 | { |
613 | int error; | |
7b9337aa | 614 | struct dentry *dentry = link->dentry; |
1da177e4 | 615 | |
844a3917 AV |
616 | BUG_ON(nd->flags & LOOKUP_RCU); |
617 | ||
0e794589 AV |
618 | if (link->mnt == nd->path.mnt) |
619 | mntget(link->mnt); | |
620 | ||
574197e0 AV |
621 | if (unlikely(current->total_link_count >= 40)) { |
622 | *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ | |
574197e0 AV |
623 | path_put(&nd->path); |
624 | return -ELOOP; | |
625 | } | |
626 | cond_resched(); | |
627 | current->total_link_count++; | |
628 | ||
7b9337aa | 629 | touch_atime(link->mnt, dentry); |
1da177e4 | 630 | nd_set_link(nd, NULL); |
cd4e91d3 | 631 | |
36f3b4f6 AV |
632 | error = security_inode_follow_link(link->dentry, nd); |
633 | if (error) { | |
634 | *p = ERR_PTR(error); /* no ->put_link(), please */ | |
635 | path_put(&nd->path); | |
636 | return error; | |
637 | } | |
638 | ||
86acdca1 | 639 | nd->last_type = LAST_BIND; |
def4af30 AV |
640 | *p = dentry->d_inode->i_op->follow_link(dentry, nd); |
641 | error = PTR_ERR(*p); | |
642 | if (!IS_ERR(*p)) { | |
1da177e4 | 643 | char *s = nd_get_link(nd); |
cc314eef | 644 | error = 0; |
1da177e4 LT |
645 | if (s) |
646 | error = __vfs_follow_link(nd, s); | |
bcda7652 | 647 | else if (nd->last_type == LAST_BIND) { |
16c2cd71 | 648 | nd->flags |= LOOKUP_JUMPED; |
b21041d0 AV |
649 | nd->inode = nd->path.dentry->d_inode; |
650 | if (nd->inode->i_op->follow_link) { | |
bcda7652 AV |
651 | /* stepped on a _really_ weird one */ |
652 | path_put(&nd->path); | |
653 | error = -ELOOP; | |
654 | } | |
655 | } | |
1da177e4 | 656 | } |
1da177e4 LT |
657 | return error; |
658 | } | |
659 | ||
31e6b01f NP |
660 | static int follow_up_rcu(struct path *path) |
661 | { | |
662 | struct vfsmount *parent; | |
663 | struct dentry *mountpoint; | |
664 | ||
665 | parent = path->mnt->mnt_parent; | |
666 | if (parent == path->mnt) | |
667 | return 0; | |
668 | mountpoint = path->mnt->mnt_mountpoint; | |
669 | path->dentry = mountpoint; | |
670 | path->mnt = parent; | |
671 | return 1; | |
672 | } | |
673 | ||
bab77ebf | 674 | int follow_up(struct path *path) |
1da177e4 LT |
675 | { |
676 | struct vfsmount *parent; | |
677 | struct dentry *mountpoint; | |
99b7db7b NP |
678 | |
679 | br_read_lock(vfsmount_lock); | |
bab77ebf AV |
680 | parent = path->mnt->mnt_parent; |
681 | if (parent == path->mnt) { | |
99b7db7b | 682 | br_read_unlock(vfsmount_lock); |
1da177e4 LT |
683 | return 0; |
684 | } | |
685 | mntget(parent); | |
bab77ebf | 686 | mountpoint = dget(path->mnt->mnt_mountpoint); |
99b7db7b | 687 | br_read_unlock(vfsmount_lock); |
bab77ebf AV |
688 | dput(path->dentry); |
689 | path->dentry = mountpoint; | |
690 | mntput(path->mnt); | |
691 | path->mnt = parent; | |
1da177e4 LT |
692 | return 1; |
693 | } | |
694 | ||
b5c84bf6 | 695 | /* |
9875cf80 DH |
696 | * Perform an automount |
697 | * - return -EISDIR to tell follow_managed() to stop and return the path we | |
698 | * were called with. | |
1da177e4 | 699 | */ |
9875cf80 DH |
700 | static int follow_automount(struct path *path, unsigned flags, |
701 | bool *need_mntput) | |
31e6b01f | 702 | { |
9875cf80 | 703 | struct vfsmount *mnt; |
ea5b778a | 704 | int err; |
9875cf80 DH |
705 | |
706 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) | |
707 | return -EREMOTE; | |
708 | ||
6f45b656 DH |
709 | /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT |
710 | * and this is the terminal part of the path. | |
711 | */ | |
49084c3b | 712 | if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_PARENT)) |
6f45b656 DH |
713 | return -EISDIR; /* we actually want to stop here */ |
714 | ||
9875cf80 DH |
715 | /* We want to mount if someone is trying to open/create a file of any |
716 | * type under the mountpoint, wants to traverse through the mountpoint | |
717 | * or wants to open the mounted directory. | |
718 | * | |
719 | * We don't want to mount if someone's just doing a stat and they've | |
720 | * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and | |
721 | * appended a '/' to the name. | |
722 | */ | |
723 | if (!(flags & LOOKUP_FOLLOW) && | |
49084c3b | 724 | !(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
9875cf80 DH |
725 | LOOKUP_OPEN | LOOKUP_CREATE))) |
726 | return -EISDIR; | |
727 | ||
728 | current->total_link_count++; | |
729 | if (current->total_link_count >= 40) | |
730 | return -ELOOP; | |
731 | ||
732 | mnt = path->dentry->d_op->d_automount(path); | |
733 | if (IS_ERR(mnt)) { | |
734 | /* | |
735 | * The filesystem is allowed to return -EISDIR here to indicate | |
736 | * it doesn't want to automount. For instance, autofs would do | |
737 | * this so that its userspace daemon can mount on this dentry. | |
738 | * | |
739 | * However, we can only permit this if it's a terminal point in | |
740 | * the path being looked up; if it wasn't then the remainder of | |
741 | * the path is inaccessible and we should say so. | |
742 | */ | |
49084c3b | 743 | if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) |
9875cf80 DH |
744 | return -EREMOTE; |
745 | return PTR_ERR(mnt); | |
31e6b01f | 746 | } |
ea5b778a | 747 | |
9875cf80 DH |
748 | if (!mnt) /* mount collision */ |
749 | return 0; | |
31e6b01f | 750 | |
8aef1884 AV |
751 | if (!*need_mntput) { |
752 | /* lock_mount() may release path->mnt on error */ | |
753 | mntget(path->mnt); | |
754 | *need_mntput = true; | |
755 | } | |
19a167af | 756 | err = finish_automount(mnt, path); |
9875cf80 | 757 | |
ea5b778a DH |
758 | switch (err) { |
759 | case -EBUSY: | |
760 | /* Someone else made a mount here whilst we were busy */ | |
19a167af | 761 | return 0; |
ea5b778a | 762 | case 0: |
8aef1884 | 763 | path_put(path); |
ea5b778a DH |
764 | path->mnt = mnt; |
765 | path->dentry = dget(mnt->mnt_root); | |
ea5b778a | 766 | return 0; |
19a167af AV |
767 | default: |
768 | return err; | |
ea5b778a | 769 | } |
19a167af | 770 | |
463ffb2e AV |
771 | } |
772 | ||
9875cf80 DH |
773 | /* |
774 | * Handle a dentry that is managed in some way. | |
cc53ce53 | 775 | * - Flagged for transit management (autofs) |
9875cf80 DH |
776 | * - Flagged as mountpoint |
777 | * - Flagged as automount point | |
778 | * | |
779 | * This may only be called in refwalk mode. | |
780 | * | |
781 | * Serialization is taken care of in namespace.c | |
782 | */ | |
783 | static int follow_managed(struct path *path, unsigned flags) | |
1da177e4 | 784 | { |
8aef1884 | 785 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
9875cf80 DH |
786 | unsigned managed; |
787 | bool need_mntput = false; | |
8aef1884 | 788 | int ret = 0; |
9875cf80 DH |
789 | |
790 | /* Given that we're not holding a lock here, we retain the value in a | |
791 | * local variable for each dentry as we look at it so that we don't see | |
792 | * the components of that value change under us */ | |
793 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
794 | managed &= DCACHE_MANAGED_DENTRY, | |
795 | unlikely(managed != 0)) { | |
cc53ce53 DH |
796 | /* Allow the filesystem to manage the transit without i_mutex |
797 | * being held. */ | |
798 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
799 | BUG_ON(!path->dentry->d_op); | |
800 | BUG_ON(!path->dentry->d_op->d_manage); | |
1aed3e42 | 801 | ret = path->dentry->d_op->d_manage(path->dentry, false); |
cc53ce53 | 802 | if (ret < 0) |
8aef1884 | 803 | break; |
cc53ce53 DH |
804 | } |
805 | ||
9875cf80 DH |
806 | /* Transit to a mounted filesystem. */ |
807 | if (managed & DCACHE_MOUNTED) { | |
808 | struct vfsmount *mounted = lookup_mnt(path); | |
809 | if (mounted) { | |
810 | dput(path->dentry); | |
811 | if (need_mntput) | |
812 | mntput(path->mnt); | |
813 | path->mnt = mounted; | |
814 | path->dentry = dget(mounted->mnt_root); | |
815 | need_mntput = true; | |
816 | continue; | |
817 | } | |
818 | ||
819 | /* Something is mounted on this dentry in another | |
820 | * namespace and/or whatever was mounted there in this | |
821 | * namespace got unmounted before we managed to get the | |
822 | * vfsmount_lock */ | |
823 | } | |
824 | ||
825 | /* Handle an automount point */ | |
826 | if (managed & DCACHE_NEED_AUTOMOUNT) { | |
827 | ret = follow_automount(path, flags, &need_mntput); | |
828 | if (ret < 0) | |
8aef1884 | 829 | break; |
9875cf80 DH |
830 | continue; |
831 | } | |
832 | ||
833 | /* We didn't change the current path point */ | |
834 | break; | |
1da177e4 | 835 | } |
8aef1884 AV |
836 | |
837 | if (need_mntput && path->mnt == mnt) | |
838 | mntput(path->mnt); | |
839 | if (ret == -EISDIR) | |
840 | ret = 0; | |
841 | return ret; | |
1da177e4 LT |
842 | } |
843 | ||
cc53ce53 | 844 | int follow_down_one(struct path *path) |
1da177e4 LT |
845 | { |
846 | struct vfsmount *mounted; | |
847 | ||
1c755af4 | 848 | mounted = lookup_mnt(path); |
1da177e4 | 849 | if (mounted) { |
9393bd07 AV |
850 | dput(path->dentry); |
851 | mntput(path->mnt); | |
852 | path->mnt = mounted; | |
853 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
854 | return 1; |
855 | } | |
856 | return 0; | |
857 | } | |
858 | ||
62a7375e IK |
859 | static inline bool managed_dentry_might_block(struct dentry *dentry) |
860 | { | |
861 | return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && | |
862 | dentry->d_op->d_manage(dentry, true) < 0); | |
863 | } | |
864 | ||
9875cf80 | 865 | /* |
287548e4 AV |
866 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
867 | * we meet a managed dentry that would need blocking. | |
9875cf80 DH |
868 | */ |
869 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, | |
287548e4 | 870 | struct inode **inode) |
9875cf80 | 871 | { |
62a7375e | 872 | for (;;) { |
9875cf80 | 873 | struct vfsmount *mounted; |
62a7375e IK |
874 | /* |
875 | * Don't forget we might have a non-mountpoint managed dentry | |
876 | * that wants to block transit. | |
877 | */ | |
287548e4 | 878 | if (unlikely(managed_dentry_might_block(path->dentry))) |
ab90911f | 879 | return false; |
62a7375e IK |
880 | |
881 | if (!d_mountpoint(path->dentry)) | |
882 | break; | |
883 | ||
9875cf80 DH |
884 | mounted = __lookup_mnt(path->mnt, path->dentry, 1); |
885 | if (!mounted) | |
886 | break; | |
887 | path->mnt = mounted; | |
888 | path->dentry = mounted->mnt_root; | |
889 | nd->seq = read_seqcount_begin(&path->dentry->d_seq); | |
59430262 LT |
890 | /* |
891 | * Update the inode too. We don't need to re-check the | |
892 | * dentry sequence number here after this d_inode read, | |
893 | * because a mount-point is always pinned. | |
894 | */ | |
895 | *inode = path->dentry->d_inode; | |
9875cf80 | 896 | } |
9875cf80 DH |
897 | return true; |
898 | } | |
899 | ||
dea39376 | 900 | static void follow_mount_rcu(struct nameidata *nd) |
287548e4 | 901 | { |
dea39376 | 902 | while (d_mountpoint(nd->path.dentry)) { |
287548e4 | 903 | struct vfsmount *mounted; |
dea39376 | 904 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); |
287548e4 AV |
905 | if (!mounted) |
906 | break; | |
dea39376 AV |
907 | nd->path.mnt = mounted; |
908 | nd->path.dentry = mounted->mnt_root; | |
909 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
287548e4 AV |
910 | } |
911 | } | |
912 | ||
31e6b01f NP |
913 | static int follow_dotdot_rcu(struct nameidata *nd) |
914 | { | |
31e6b01f NP |
915 | set_root_rcu(nd); |
916 | ||
9875cf80 | 917 | while (1) { |
31e6b01f NP |
918 | if (nd->path.dentry == nd->root.dentry && |
919 | nd->path.mnt == nd->root.mnt) { | |
920 | break; | |
921 | } | |
922 | if (nd->path.dentry != nd->path.mnt->mnt_root) { | |
923 | struct dentry *old = nd->path.dentry; | |
924 | struct dentry *parent = old->d_parent; | |
925 | unsigned seq; | |
926 | ||
927 | seq = read_seqcount_begin(&parent->d_seq); | |
928 | if (read_seqcount_retry(&old->d_seq, nd->seq)) | |
ef7562d5 | 929 | goto failed; |
31e6b01f NP |
930 | nd->path.dentry = parent; |
931 | nd->seq = seq; | |
932 | break; | |
933 | } | |
934 | if (!follow_up_rcu(&nd->path)) | |
935 | break; | |
936 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
31e6b01f | 937 | } |
dea39376 AV |
938 | follow_mount_rcu(nd); |
939 | nd->inode = nd->path.dentry->d_inode; | |
31e6b01f | 940 | return 0; |
ef7562d5 AV |
941 | |
942 | failed: | |
943 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
944 | if (!(nd->flags & LOOKUP_ROOT)) |
945 | nd->root.mnt = NULL; | |
ef7562d5 AV |
946 | rcu_read_unlock(); |
947 | br_read_unlock(vfsmount_lock); | |
948 | return -ECHILD; | |
31e6b01f NP |
949 | } |
950 | ||
cc53ce53 DH |
951 | /* |
952 | * Follow down to the covering mount currently visible to userspace. At each | |
953 | * point, the filesystem owning that dentry may be queried as to whether the | |
954 | * caller is permitted to proceed or not. | |
cc53ce53 | 955 | */ |
7cc90cc3 | 956 | int follow_down(struct path *path) |
cc53ce53 DH |
957 | { |
958 | unsigned managed; | |
959 | int ret; | |
960 | ||
961 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
962 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { | |
963 | /* Allow the filesystem to manage the transit without i_mutex | |
964 | * being held. | |
965 | * | |
966 | * We indicate to the filesystem if someone is trying to mount | |
967 | * something here. This gives autofs the chance to deny anyone | |
968 | * other than its daemon the right to mount on its | |
969 | * superstructure. | |
970 | * | |
971 | * The filesystem may sleep at this point. | |
972 | */ | |
973 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
974 | BUG_ON(!path->dentry->d_op); | |
975 | BUG_ON(!path->dentry->d_op->d_manage); | |
ab90911f | 976 | ret = path->dentry->d_op->d_manage( |
1aed3e42 | 977 | path->dentry, false); |
cc53ce53 DH |
978 | if (ret < 0) |
979 | return ret == -EISDIR ? 0 : ret; | |
980 | } | |
981 | ||
982 | /* Transit to a mounted filesystem. */ | |
983 | if (managed & DCACHE_MOUNTED) { | |
984 | struct vfsmount *mounted = lookup_mnt(path); | |
985 | if (!mounted) | |
986 | break; | |
987 | dput(path->dentry); | |
988 | mntput(path->mnt); | |
989 | path->mnt = mounted; | |
990 | path->dentry = dget(mounted->mnt_root); | |
991 | continue; | |
992 | } | |
993 | ||
994 | /* Don't handle automount points here */ | |
995 | break; | |
996 | } | |
997 | return 0; | |
998 | } | |
999 | ||
9875cf80 DH |
1000 | /* |
1001 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() | |
1002 | */ | |
1003 | static void follow_mount(struct path *path) | |
1004 | { | |
1005 | while (d_mountpoint(path->dentry)) { | |
1006 | struct vfsmount *mounted = lookup_mnt(path); | |
1007 | if (!mounted) | |
1008 | break; | |
1009 | dput(path->dentry); | |
1010 | mntput(path->mnt); | |
1011 | path->mnt = mounted; | |
1012 | path->dentry = dget(mounted->mnt_root); | |
1013 | } | |
1014 | } | |
1015 | ||
31e6b01f | 1016 | static void follow_dotdot(struct nameidata *nd) |
1da177e4 | 1017 | { |
2a737871 | 1018 | set_root(nd); |
e518ddb7 | 1019 | |
1da177e4 | 1020 | while(1) { |
4ac91378 | 1021 | struct dentry *old = nd->path.dentry; |
1da177e4 | 1022 | |
2a737871 AV |
1023 | if (nd->path.dentry == nd->root.dentry && |
1024 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
1025 | break; |
1026 | } | |
4ac91378 | 1027 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
3088dd70 AV |
1028 | /* rare case of legitimate dget_parent()... */ |
1029 | nd->path.dentry = dget_parent(nd->path.dentry); | |
1da177e4 LT |
1030 | dput(old); |
1031 | break; | |
1032 | } | |
3088dd70 | 1033 | if (!follow_up(&nd->path)) |
1da177e4 | 1034 | break; |
1da177e4 | 1035 | } |
79ed0226 | 1036 | follow_mount(&nd->path); |
31e6b01f | 1037 | nd->inode = nd->path.dentry->d_inode; |
1da177e4 LT |
1038 | } |
1039 | ||
baa03890 NP |
1040 | /* |
1041 | * Allocate a dentry with name and parent, and perform a parent | |
1042 | * directory ->lookup on it. Returns the new dentry, or ERR_PTR | |
1043 | * on error. parent->d_inode->i_mutex must be held. d_lookup must | |
1044 | * have verified that no child exists while under i_mutex. | |
1045 | */ | |
1046 | static struct dentry *d_alloc_and_lookup(struct dentry *parent, | |
1047 | struct qstr *name, struct nameidata *nd) | |
1048 | { | |
1049 | struct inode *inode = parent->d_inode; | |
1050 | struct dentry *dentry; | |
1051 | struct dentry *old; | |
1052 | ||
1053 | /* Don't create child dentry for a dead directory. */ | |
1054 | if (unlikely(IS_DEADDIR(inode))) | |
1055 | return ERR_PTR(-ENOENT); | |
1056 | ||
1057 | dentry = d_alloc(parent, name); | |
1058 | if (unlikely(!dentry)) | |
1059 | return ERR_PTR(-ENOMEM); | |
1060 | ||
1061 | old = inode->i_op->lookup(inode, dentry, nd); | |
1062 | if (unlikely(old)) { | |
1063 | dput(dentry); | |
1064 | dentry = old; | |
1065 | } | |
1066 | return dentry; | |
1067 | } | |
1068 | ||
44396f4b JB |
1069 | /* |
1070 | * We already have a dentry, but require a lookup to be performed on the parent | |
1071 | * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error. | |
1072 | * parent->d_inode->i_mutex must be held. d_lookup must have verified that no | |
1073 | * child exists while under i_mutex. | |
1074 | */ | |
1075 | static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry, | |
1076 | struct nameidata *nd) | |
1077 | { | |
1078 | struct inode *inode = parent->d_inode; | |
1079 | struct dentry *old; | |
1080 | ||
1081 | /* Don't create child dentry for a dead directory. */ | |
1082 | if (unlikely(IS_DEADDIR(inode))) | |
1083 | return ERR_PTR(-ENOENT); | |
1084 | ||
1085 | old = inode->i_op->lookup(inode, dentry, nd); | |
1086 | if (unlikely(old)) { | |
1087 | dput(dentry); | |
1088 | dentry = old; | |
1089 | } | |
1090 | return dentry; | |
1091 | } | |
1092 | ||
1da177e4 LT |
1093 | /* |
1094 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
1095 | * small and for now I'd prefer to have fast path as straight as possible. | |
1096 | * It _is_ time-critical. | |
1097 | */ | |
1098 | static int do_lookup(struct nameidata *nd, struct qstr *name, | |
31e6b01f | 1099 | struct path *path, struct inode **inode) |
1da177e4 | 1100 | { |
4ac91378 | 1101 | struct vfsmount *mnt = nd->path.mnt; |
31e6b01f | 1102 | struct dentry *dentry, *parent = nd->path.dentry; |
5a18fff2 AV |
1103 | int need_reval = 1; |
1104 | int status = 1; | |
9875cf80 DH |
1105 | int err; |
1106 | ||
b04f784e NP |
1107 | /* |
1108 | * Rename seqlock is not required here because in the off chance | |
1109 | * of a false negative due to a concurrent rename, we're going to | |
1110 | * do the non-racy lookup, below. | |
1111 | */ | |
31e6b01f NP |
1112 | if (nd->flags & LOOKUP_RCU) { |
1113 | unsigned seq; | |
31e6b01f NP |
1114 | *inode = nd->inode; |
1115 | dentry = __d_lookup_rcu(parent, name, &seq, inode); | |
5a18fff2 AV |
1116 | if (!dentry) |
1117 | goto unlazy; | |
1118 | ||
31e6b01f NP |
1119 | /* Memory barrier in read_seqcount_begin of child is enough */ |
1120 | if (__read_seqcount_retry(&parent->d_seq, nd->seq)) | |
1121 | return -ECHILD; | |
31e6b01f | 1122 | nd->seq = seq; |
5a18fff2 | 1123 | |
24643087 | 1124 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
5a18fff2 AV |
1125 | status = d_revalidate(dentry, nd); |
1126 | if (unlikely(status <= 0)) { | |
1127 | if (status != -ECHILD) | |
1128 | need_reval = 0; | |
1129 | goto unlazy; | |
1130 | } | |
24643087 | 1131 | } |
44396f4b JB |
1132 | if (unlikely(d_need_lookup(dentry))) |
1133 | goto unlazy; | |
31e6b01f NP |
1134 | path->mnt = mnt; |
1135 | path->dentry = dentry; | |
d6e9bd25 AV |
1136 | if (unlikely(!__follow_mount_rcu(nd, path, inode))) |
1137 | goto unlazy; | |
1138 | if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) | |
1139 | goto unlazy; | |
1140 | return 0; | |
5a18fff2 | 1141 | unlazy: |
19660af7 AV |
1142 | if (unlazy_walk(nd, dentry)) |
1143 | return -ECHILD; | |
5a18fff2 AV |
1144 | } else { |
1145 | dentry = __d_lookup(parent, name); | |
9875cf80 | 1146 | } |
5a18fff2 | 1147 | |
44396f4b JB |
1148 | if (dentry && unlikely(d_need_lookup(dentry))) { |
1149 | dput(dentry); | |
1150 | dentry = NULL; | |
1151 | } | |
5a18fff2 AV |
1152 | retry: |
1153 | if (unlikely(!dentry)) { | |
1154 | struct inode *dir = parent->d_inode; | |
1155 | BUG_ON(nd->inode != dir); | |
1156 | ||
1157 | mutex_lock(&dir->i_mutex); | |
1158 | dentry = d_lookup(parent, name); | |
1159 | if (likely(!dentry)) { | |
1160 | dentry = d_alloc_and_lookup(parent, name, nd); | |
1161 | if (IS_ERR(dentry)) { | |
1162 | mutex_unlock(&dir->i_mutex); | |
1163 | return PTR_ERR(dentry); | |
1164 | } | |
1165 | /* known good */ | |
1166 | need_reval = 0; | |
1167 | status = 1; | |
44396f4b JB |
1168 | } else if (unlikely(d_need_lookup(dentry))) { |
1169 | dentry = d_inode_lookup(parent, dentry, nd); | |
1170 | if (IS_ERR(dentry)) { | |
1171 | mutex_unlock(&dir->i_mutex); | |
1172 | return PTR_ERR(dentry); | |
1173 | } | |
1174 | /* known good */ | |
1175 | need_reval = 0; | |
1176 | status = 1; | |
5a18fff2 AV |
1177 | } |
1178 | mutex_unlock(&dir->i_mutex); | |
1179 | } | |
1180 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) | |
1181 | status = d_revalidate(dentry, nd); | |
1182 | if (unlikely(status <= 0)) { | |
1183 | if (status < 0) { | |
1184 | dput(dentry); | |
1185 | return status; | |
1186 | } | |
1187 | if (!d_invalidate(dentry)) { | |
1188 | dput(dentry); | |
1189 | dentry = NULL; | |
1190 | need_reval = 1; | |
1191 | goto retry; | |
1192 | } | |
24643087 | 1193 | } |
5a18fff2 | 1194 | |
9875cf80 DH |
1195 | path->mnt = mnt; |
1196 | path->dentry = dentry; | |
1197 | err = follow_managed(path, nd->flags); | |
89312214 IK |
1198 | if (unlikely(err < 0)) { |
1199 | path_put_conditional(path, nd); | |
9875cf80 | 1200 | return err; |
89312214 | 1201 | } |
9875cf80 | 1202 | *inode = path->dentry->d_inode; |
1da177e4 | 1203 | return 0; |
1da177e4 LT |
1204 | } |
1205 | ||
52094c8a AV |
1206 | static inline int may_lookup(struct nameidata *nd) |
1207 | { | |
1208 | if (nd->flags & LOOKUP_RCU) { | |
4ad5abb3 | 1209 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
52094c8a AV |
1210 | if (err != -ECHILD) |
1211 | return err; | |
19660af7 | 1212 | if (unlazy_walk(nd, NULL)) |
52094c8a AV |
1213 | return -ECHILD; |
1214 | } | |
4ad5abb3 | 1215 | return inode_permission(nd->inode, MAY_EXEC); |
52094c8a AV |
1216 | } |
1217 | ||
9856fa1b AV |
1218 | static inline int handle_dots(struct nameidata *nd, int type) |
1219 | { | |
1220 | if (type == LAST_DOTDOT) { | |
1221 | if (nd->flags & LOOKUP_RCU) { | |
1222 | if (follow_dotdot_rcu(nd)) | |
1223 | return -ECHILD; | |
1224 | } else | |
1225 | follow_dotdot(nd); | |
1226 | } | |
1227 | return 0; | |
1228 | } | |
1229 | ||
951361f9 AV |
1230 | static void terminate_walk(struct nameidata *nd) |
1231 | { | |
1232 | if (!(nd->flags & LOOKUP_RCU)) { | |
1233 | path_put(&nd->path); | |
1234 | } else { | |
1235 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1236 | if (!(nd->flags & LOOKUP_ROOT)) |
1237 | nd->root.mnt = NULL; | |
951361f9 AV |
1238 | rcu_read_unlock(); |
1239 | br_read_unlock(vfsmount_lock); | |
1240 | } | |
1241 | } | |
1242 | ||
ce57dfc1 AV |
1243 | static inline int walk_component(struct nameidata *nd, struct path *path, |
1244 | struct qstr *name, int type, int follow) | |
1245 | { | |
1246 | struct inode *inode; | |
1247 | int err; | |
1248 | /* | |
1249 | * "." and ".." are special - ".." especially so because it has | |
1250 | * to be able to know about the current root directory and | |
1251 | * parent relationships. | |
1252 | */ | |
1253 | if (unlikely(type != LAST_NORM)) | |
1254 | return handle_dots(nd, type); | |
1255 | err = do_lookup(nd, name, path, &inode); | |
1256 | if (unlikely(err)) { | |
1257 | terminate_walk(nd); | |
1258 | return err; | |
1259 | } | |
1260 | if (!inode) { | |
1261 | path_to_nameidata(path, nd); | |
1262 | terminate_walk(nd); | |
1263 | return -ENOENT; | |
1264 | } | |
1265 | if (unlikely(inode->i_op->follow_link) && follow) { | |
19660af7 AV |
1266 | if (nd->flags & LOOKUP_RCU) { |
1267 | if (unlikely(unlazy_walk(nd, path->dentry))) { | |
1268 | terminate_walk(nd); | |
1269 | return -ECHILD; | |
1270 | } | |
1271 | } | |
ce57dfc1 AV |
1272 | BUG_ON(inode != path->dentry->d_inode); |
1273 | return 1; | |
1274 | } | |
1275 | path_to_nameidata(path, nd); | |
1276 | nd->inode = inode; | |
1277 | return 0; | |
1278 | } | |
1279 | ||
b356379a AV |
1280 | /* |
1281 | * This limits recursive symlink follows to 8, while | |
1282 | * limiting consecutive symlinks to 40. | |
1283 | * | |
1284 | * Without that kind of total limit, nasty chains of consecutive | |
1285 | * symlinks can cause almost arbitrarily long lookups. | |
1286 | */ | |
1287 | static inline int nested_symlink(struct path *path, struct nameidata *nd) | |
1288 | { | |
1289 | int res; | |
1290 | ||
b356379a AV |
1291 | if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { |
1292 | path_put_conditional(path, nd); | |
1293 | path_put(&nd->path); | |
1294 | return -ELOOP; | |
1295 | } | |
1a4022f8 | 1296 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); |
b356379a AV |
1297 | |
1298 | nd->depth++; | |
1299 | current->link_count++; | |
1300 | ||
1301 | do { | |
1302 | struct path link = *path; | |
1303 | void *cookie; | |
574197e0 AV |
1304 | |
1305 | res = follow_link(&link, nd, &cookie); | |
b356379a AV |
1306 | if (!res) |
1307 | res = walk_component(nd, path, &nd->last, | |
1308 | nd->last_type, LOOKUP_FOLLOW); | |
574197e0 | 1309 | put_link(nd, &link, cookie); |
b356379a AV |
1310 | } while (res > 0); |
1311 | ||
1312 | current->link_count--; | |
1313 | nd->depth--; | |
1314 | return res; | |
1315 | } | |
1316 | ||
1da177e4 LT |
1317 | /* |
1318 | * Name resolution. | |
ea3834d9 PM |
1319 | * This is the basic name resolution function, turning a pathname into |
1320 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 1321 | * |
ea3834d9 PM |
1322 | * Returns 0 and nd will have valid dentry and mnt on success. |
1323 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 1324 | */ |
6de88d72 | 1325 | static int link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 LT |
1326 | { |
1327 | struct path next; | |
1da177e4 | 1328 | int err; |
1da177e4 LT |
1329 | |
1330 | while (*name=='/') | |
1331 | name++; | |
1332 | if (!*name) | |
086e183a | 1333 | return 0; |
1da177e4 | 1334 | |
1da177e4 LT |
1335 | /* At this point we know we have a real path component. */ |
1336 | for(;;) { | |
1337 | unsigned long hash; | |
1338 | struct qstr this; | |
1339 | unsigned int c; | |
fe479a58 | 1340 | int type; |
1da177e4 | 1341 | |
52094c8a | 1342 | err = may_lookup(nd); |
1da177e4 LT |
1343 | if (err) |
1344 | break; | |
1345 | ||
1346 | this.name = name; | |
1347 | c = *(const unsigned char *)name; | |
1348 | ||
1349 | hash = init_name_hash(); | |
1350 | do { | |
1351 | name++; | |
1352 | hash = partial_name_hash(c, hash); | |
1353 | c = *(const unsigned char *)name; | |
1354 | } while (c && (c != '/')); | |
1355 | this.len = name - (const char *) this.name; | |
1356 | this.hash = end_name_hash(hash); | |
1357 | ||
fe479a58 AV |
1358 | type = LAST_NORM; |
1359 | if (this.name[0] == '.') switch (this.len) { | |
1360 | case 2: | |
16c2cd71 | 1361 | if (this.name[1] == '.') { |
fe479a58 | 1362 | type = LAST_DOTDOT; |
16c2cd71 AV |
1363 | nd->flags |= LOOKUP_JUMPED; |
1364 | } | |
fe479a58 AV |
1365 | break; |
1366 | case 1: | |
1367 | type = LAST_DOT; | |
1368 | } | |
5a202bcd AV |
1369 | if (likely(type == LAST_NORM)) { |
1370 | struct dentry *parent = nd->path.dentry; | |
16c2cd71 | 1371 | nd->flags &= ~LOOKUP_JUMPED; |
5a202bcd AV |
1372 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
1373 | err = parent->d_op->d_hash(parent, nd->inode, | |
1374 | &this); | |
1375 | if (err < 0) | |
1376 | break; | |
1377 | } | |
1378 | } | |
fe479a58 | 1379 | |
1da177e4 LT |
1380 | /* remove trailing slashes? */ |
1381 | if (!c) | |
1382 | goto last_component; | |
1383 | while (*++name == '/'); | |
1384 | if (!*name) | |
b356379a | 1385 | goto last_component; |
1da177e4 | 1386 | |
ce57dfc1 AV |
1387 | err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); |
1388 | if (err < 0) | |
1389 | return err; | |
1da177e4 | 1390 | |
ce57dfc1 | 1391 | if (err) { |
b356379a | 1392 | err = nested_symlink(&next, nd); |
1da177e4 | 1393 | if (err) |
a7472bab | 1394 | return err; |
31e6b01f | 1395 | } |
1da177e4 | 1396 | err = -ENOTDIR; |
31e6b01f | 1397 | if (!nd->inode->i_op->lookup) |
1da177e4 LT |
1398 | break; |
1399 | continue; | |
1400 | /* here ends the main loop */ | |
1401 | ||
1da177e4 | 1402 | last_component: |
b356379a AV |
1403 | nd->last = this; |
1404 | nd->last_type = type; | |
086e183a | 1405 | return 0; |
1da177e4 | 1406 | } |
951361f9 | 1407 | terminate_walk(nd); |
1da177e4 LT |
1408 | return err; |
1409 | } | |
1410 | ||
70e9b357 AV |
1411 | static int path_init(int dfd, const char *name, unsigned int flags, |
1412 | struct nameidata *nd, struct file **fp) | |
31e6b01f NP |
1413 | { |
1414 | int retval = 0; | |
1415 | int fput_needed; | |
1416 | struct file *file; | |
1417 | ||
1418 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
16c2cd71 | 1419 | nd->flags = flags | LOOKUP_JUMPED; |
31e6b01f | 1420 | nd->depth = 0; |
5b6ca027 AV |
1421 | if (flags & LOOKUP_ROOT) { |
1422 | struct inode *inode = nd->root.dentry->d_inode; | |
73d049a4 AV |
1423 | if (*name) { |
1424 | if (!inode->i_op->lookup) | |
1425 | return -ENOTDIR; | |
1426 | retval = inode_permission(inode, MAY_EXEC); | |
1427 | if (retval) | |
1428 | return retval; | |
1429 | } | |
5b6ca027 AV |
1430 | nd->path = nd->root; |
1431 | nd->inode = inode; | |
1432 | if (flags & LOOKUP_RCU) { | |
1433 | br_read_lock(vfsmount_lock); | |
1434 | rcu_read_lock(); | |
1435 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
1436 | } else { | |
1437 | path_get(&nd->path); | |
1438 | } | |
1439 | return 0; | |
1440 | } | |
1441 | ||
31e6b01f | 1442 | nd->root.mnt = NULL; |
31e6b01f NP |
1443 | |
1444 | if (*name=='/') { | |
e41f7d4e AV |
1445 | if (flags & LOOKUP_RCU) { |
1446 | br_read_lock(vfsmount_lock); | |
1447 | rcu_read_lock(); | |
1448 | set_root_rcu(nd); | |
1449 | } else { | |
1450 | set_root(nd); | |
1451 | path_get(&nd->root); | |
1452 | } | |
1453 | nd->path = nd->root; | |
31e6b01f | 1454 | } else if (dfd == AT_FDCWD) { |
e41f7d4e AV |
1455 | if (flags & LOOKUP_RCU) { |
1456 | struct fs_struct *fs = current->fs; | |
1457 | unsigned seq; | |
31e6b01f | 1458 | |
e41f7d4e AV |
1459 | br_read_lock(vfsmount_lock); |
1460 | rcu_read_lock(); | |
c28cc364 | 1461 | |
e41f7d4e AV |
1462 | do { |
1463 | seq = read_seqcount_begin(&fs->seq); | |
1464 | nd->path = fs->pwd; | |
1465 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
1466 | } while (read_seqcount_retry(&fs->seq, seq)); | |
1467 | } else { | |
1468 | get_fs_pwd(current->fs, &nd->path); | |
1469 | } | |
31e6b01f NP |
1470 | } else { |
1471 | struct dentry *dentry; | |
1472 | ||
1abf0c71 | 1473 | file = fget_raw_light(dfd, &fput_needed); |
31e6b01f NP |
1474 | retval = -EBADF; |
1475 | if (!file) | |
1476 | goto out_fail; | |
1477 | ||
1478 | dentry = file->f_path.dentry; | |
1479 | ||
f52e0c11 AV |
1480 | if (*name) { |
1481 | retval = -ENOTDIR; | |
1482 | if (!S_ISDIR(dentry->d_inode->i_mode)) | |
1483 | goto fput_fail; | |
31e6b01f | 1484 | |
4ad5abb3 | 1485 | retval = inode_permission(dentry->d_inode, MAY_EXEC); |
f52e0c11 AV |
1486 | if (retval) |
1487 | goto fput_fail; | |
1488 | } | |
31e6b01f NP |
1489 | |
1490 | nd->path = file->f_path; | |
e41f7d4e AV |
1491 | if (flags & LOOKUP_RCU) { |
1492 | if (fput_needed) | |
70e9b357 | 1493 | *fp = file; |
e41f7d4e AV |
1494 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
1495 | br_read_lock(vfsmount_lock); | |
1496 | rcu_read_lock(); | |
1497 | } else { | |
1498 | path_get(&file->f_path); | |
1499 | fput_light(file, fput_needed); | |
1500 | } | |
31e6b01f | 1501 | } |
31e6b01f | 1502 | |
31e6b01f | 1503 | nd->inode = nd->path.dentry->d_inode; |
9b4a9b14 | 1504 | return 0; |
2dfdd266 | 1505 | |
9b4a9b14 AV |
1506 | fput_fail: |
1507 | fput_light(file, fput_needed); | |
1508 | out_fail: | |
1509 | return retval; | |
1510 | } | |
1511 | ||
bd92d7fe AV |
1512 | static inline int lookup_last(struct nameidata *nd, struct path *path) |
1513 | { | |
1514 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) | |
1515 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
1516 | ||
1517 | nd->flags &= ~LOOKUP_PARENT; | |
1518 | return walk_component(nd, path, &nd->last, nd->last_type, | |
1519 | nd->flags & LOOKUP_FOLLOW); | |
1520 | } | |
1521 | ||
9b4a9b14 | 1522 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
ee0827cd | 1523 | static int path_lookupat(int dfd, const char *name, |
9b4a9b14 AV |
1524 | unsigned int flags, struct nameidata *nd) |
1525 | { | |
70e9b357 | 1526 | struct file *base = NULL; |
bd92d7fe AV |
1527 | struct path path; |
1528 | int err; | |
31e6b01f NP |
1529 | |
1530 | /* | |
1531 | * Path walking is largely split up into 2 different synchronisation | |
1532 | * schemes, rcu-walk and ref-walk (explained in | |
1533 | * Documentation/filesystems/path-lookup.txt). These share much of the | |
1534 | * path walk code, but some things particularly setup, cleanup, and | |
1535 | * following mounts are sufficiently divergent that functions are | |
1536 | * duplicated. Typically there is a function foo(), and its RCU | |
1537 | * analogue, foo_rcu(). | |
1538 | * | |
1539 | * -ECHILD is the error number of choice (just to avoid clashes) that | |
1540 | * is returned if some aspect of an rcu-walk fails. Such an error must | |
1541 | * be handled by restarting a traditional ref-walk (which will always | |
1542 | * be able to complete). | |
1543 | */ | |
bd92d7fe | 1544 | err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); |
ee0827cd | 1545 | |
bd92d7fe AV |
1546 | if (unlikely(err)) |
1547 | return err; | |
ee0827cd AV |
1548 | |
1549 | current->total_link_count = 0; | |
bd92d7fe AV |
1550 | err = link_path_walk(name, nd); |
1551 | ||
1552 | if (!err && !(flags & LOOKUP_PARENT)) { | |
bd92d7fe AV |
1553 | err = lookup_last(nd, &path); |
1554 | while (err > 0) { | |
1555 | void *cookie; | |
1556 | struct path link = path; | |
bd92d7fe | 1557 | nd->flags |= LOOKUP_PARENT; |
574197e0 | 1558 | err = follow_link(&link, nd, &cookie); |
bd92d7fe AV |
1559 | if (!err) |
1560 | err = lookup_last(nd, &path); | |
574197e0 | 1561 | put_link(nd, &link, cookie); |
bd92d7fe AV |
1562 | } |
1563 | } | |
ee0827cd | 1564 | |
9f1fafee AV |
1565 | if (!err) |
1566 | err = complete_walk(nd); | |
bd92d7fe AV |
1567 | |
1568 | if (!err && nd->flags & LOOKUP_DIRECTORY) { | |
1569 | if (!nd->inode->i_op->lookup) { | |
1570 | path_put(&nd->path); | |
bd23a539 | 1571 | err = -ENOTDIR; |
bd92d7fe AV |
1572 | } |
1573 | } | |
16c2cd71 | 1574 | |
70e9b357 AV |
1575 | if (base) |
1576 | fput(base); | |
ee0827cd | 1577 | |
5b6ca027 | 1578 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
2a737871 AV |
1579 | path_put(&nd->root); |
1580 | nd->root.mnt = NULL; | |
1581 | } | |
bd92d7fe | 1582 | return err; |
ee0827cd | 1583 | } |
31e6b01f | 1584 | |
ee0827cd AV |
1585 | static int do_path_lookup(int dfd, const char *name, |
1586 | unsigned int flags, struct nameidata *nd) | |
1587 | { | |
1588 | int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); | |
1589 | if (unlikely(retval == -ECHILD)) | |
1590 | retval = path_lookupat(dfd, name, flags, nd); | |
1591 | if (unlikely(retval == -ESTALE)) | |
1592 | retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); | |
31e6b01f NP |
1593 | |
1594 | if (likely(!retval)) { | |
1595 | if (unlikely(!audit_dummy_context())) { | |
1596 | if (nd->path.dentry && nd->inode) | |
1597 | audit_inode(name, nd->path.dentry); | |
1598 | } | |
1599 | } | |
170aa3d0 | 1600 | return retval; |
1da177e4 LT |
1601 | } |
1602 | ||
c9c6cac0 | 1603 | int kern_path_parent(const char *name, struct nameidata *nd) |
5590ff0d | 1604 | { |
c9c6cac0 | 1605 | return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); |
5590ff0d UD |
1606 | } |
1607 | ||
d1811465 AV |
1608 | int kern_path(const char *name, unsigned int flags, struct path *path) |
1609 | { | |
1610 | struct nameidata nd; | |
1611 | int res = do_path_lookup(AT_FDCWD, name, flags, &nd); | |
1612 | if (!res) | |
1613 | *path = nd.path; | |
1614 | return res; | |
1615 | } | |
1616 | ||
16f18200 JJS |
1617 | /** |
1618 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
1619 | * @dentry: pointer to dentry of the base directory | |
1620 | * @mnt: pointer to vfs mount of the base directory | |
1621 | * @name: pointer to file name | |
1622 | * @flags: lookup flags | |
e0a01249 | 1623 | * @path: pointer to struct path to fill |
16f18200 JJS |
1624 | */ |
1625 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
1626 | const char *name, unsigned int flags, | |
e0a01249 | 1627 | struct path *path) |
16f18200 | 1628 | { |
e0a01249 AV |
1629 | struct nameidata nd; |
1630 | int err; | |
1631 | nd.root.dentry = dentry; | |
1632 | nd.root.mnt = mnt; | |
1633 | BUG_ON(flags & LOOKUP_PARENT); | |
5b6ca027 | 1634 | /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ |
e0a01249 AV |
1635 | err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); |
1636 | if (!err) | |
1637 | *path = nd.path; | |
1638 | return err; | |
16f18200 JJS |
1639 | } |
1640 | ||
eead1911 CH |
1641 | static struct dentry *__lookup_hash(struct qstr *name, |
1642 | struct dentry *base, struct nameidata *nd) | |
1da177e4 | 1643 | { |
81fca444 | 1644 | struct inode *inode = base->d_inode; |
057f6c01 | 1645 | struct dentry *dentry; |
1da177e4 LT |
1646 | int err; |
1647 | ||
4ad5abb3 | 1648 | err = inode_permission(inode, MAY_EXEC); |
81fca444 CH |
1649 | if (err) |
1650 | return ERR_PTR(err); | |
1da177e4 | 1651 | |
b04f784e NP |
1652 | /* |
1653 | * Don't bother with __d_lookup: callers are for creat as | |
1654 | * well as unlink, so a lot of the time it would cost | |
1655 | * a double lookup. | |
6e6b1bd1 | 1656 | */ |
b04f784e | 1657 | dentry = d_lookup(base, name); |
6e6b1bd1 | 1658 | |
44396f4b JB |
1659 | if (dentry && d_need_lookup(dentry)) { |
1660 | /* | |
1661 | * __lookup_hash is called with the parent dir's i_mutex already | |
1662 | * held, so we are good to go here. | |
1663 | */ | |
1664 | dentry = d_inode_lookup(base, dentry, nd); | |
1665 | if (IS_ERR(dentry)) | |
1666 | return dentry; | |
1667 | } | |
1668 | ||
d2d9e9fb AV |
1669 | if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
1670 | int status = d_revalidate(dentry, nd); | |
1671 | if (unlikely(status <= 0)) { | |
1672 | /* | |
1673 | * The dentry failed validation. | |
1674 | * If d_revalidate returned 0 attempt to invalidate | |
1675 | * the dentry otherwise d_revalidate is asking us | |
1676 | * to return a fail status. | |
1677 | */ | |
1678 | if (status < 0) { | |
1679 | dput(dentry); | |
1680 | return ERR_PTR(status); | |
1681 | } else if (!d_invalidate(dentry)) { | |
1682 | dput(dentry); | |
1683 | dentry = NULL; | |
1684 | } | |
1685 | } | |
1686 | } | |
6e6b1bd1 | 1687 | |
baa03890 NP |
1688 | if (!dentry) |
1689 | dentry = d_alloc_and_lookup(base, name, nd); | |
5a202bcd | 1690 | |
1da177e4 LT |
1691 | return dentry; |
1692 | } | |
1693 | ||
057f6c01 JM |
1694 | /* |
1695 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
1696 | * needs parent already locked. Doesn't follow mounts. | |
1697 | * SMP-safe. | |
1698 | */ | |
eead1911 | 1699 | static struct dentry *lookup_hash(struct nameidata *nd) |
057f6c01 | 1700 | { |
4ac91378 | 1701 | return __lookup_hash(&nd->last, nd->path.dentry, nd); |
1da177e4 LT |
1702 | } |
1703 | ||
eead1911 | 1704 | /** |
a6b91919 | 1705 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
1706 | * @name: pathname component to lookup |
1707 | * @base: base directory to lookup from | |
1708 | * @len: maximum length @len should be interpreted to | |
1709 | * | |
a6b91919 RD |
1710 | * Note that this routine is purely a helper for filesystem usage and should |
1711 | * not be called by generic code. Also note that by using this function the | |
eead1911 CH |
1712 | * nameidata argument is passed to the filesystem methods and a filesystem |
1713 | * using this helper needs to be prepared for that. | |
1714 | */ | |
057f6c01 JM |
1715 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
1716 | { | |
057f6c01 | 1717 | struct qstr this; |
6a96ba54 AV |
1718 | unsigned long hash; |
1719 | unsigned int c; | |
057f6c01 | 1720 | |
2f9092e1 DW |
1721 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
1722 | ||
6a96ba54 AV |
1723 | this.name = name; |
1724 | this.len = len; | |
1725 | if (!len) | |
1726 | return ERR_PTR(-EACCES); | |
1727 | ||
1728 | hash = init_name_hash(); | |
1729 | while (len--) { | |
1730 | c = *(const unsigned char *)name++; | |
1731 | if (c == '/' || c == '\0') | |
1732 | return ERR_PTR(-EACCES); | |
1733 | hash = partial_name_hash(c, hash); | |
1734 | } | |
1735 | this.hash = end_name_hash(hash); | |
5a202bcd AV |
1736 | /* |
1737 | * See if the low-level filesystem might want | |
1738 | * to use its own hash.. | |
1739 | */ | |
1740 | if (base->d_flags & DCACHE_OP_HASH) { | |
1741 | int err = base->d_op->d_hash(base, base->d_inode, &this); | |
1742 | if (err < 0) | |
1743 | return ERR_PTR(err); | |
1744 | } | |
eead1911 | 1745 | |
49705b77 | 1746 | return __lookup_hash(&this, base, NULL); |
057f6c01 JM |
1747 | } |
1748 | ||
2d8f3038 AV |
1749 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
1750 | struct path *path) | |
1da177e4 | 1751 | { |
2d8f3038 | 1752 | struct nameidata nd; |
f52e0c11 | 1753 | char *tmp = getname_flags(name, flags); |
1da177e4 | 1754 | int err = PTR_ERR(tmp); |
1da177e4 | 1755 | if (!IS_ERR(tmp)) { |
2d8f3038 AV |
1756 | |
1757 | BUG_ON(flags & LOOKUP_PARENT); | |
1758 | ||
1759 | err = do_path_lookup(dfd, tmp, flags, &nd); | |
1da177e4 | 1760 | putname(tmp); |
2d8f3038 AV |
1761 | if (!err) |
1762 | *path = nd.path; | |
1da177e4 LT |
1763 | } |
1764 | return err; | |
1765 | } | |
1766 | ||
2ad94ae6 AV |
1767 | static int user_path_parent(int dfd, const char __user *path, |
1768 | struct nameidata *nd, char **name) | |
1769 | { | |
1770 | char *s = getname(path); | |
1771 | int error; | |
1772 | ||
1773 | if (IS_ERR(s)) | |
1774 | return PTR_ERR(s); | |
1775 | ||
1776 | error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); | |
1777 | if (error) | |
1778 | putname(s); | |
1779 | else | |
1780 | *name = s; | |
1781 | ||
1782 | return error; | |
1783 | } | |
1784 | ||
1da177e4 LT |
1785 | /* |
1786 | * It's inline, so penalty for filesystems that don't use sticky bit is | |
1787 | * minimal. | |
1788 | */ | |
1789 | static inline int check_sticky(struct inode *dir, struct inode *inode) | |
1790 | { | |
da9592ed DH |
1791 | uid_t fsuid = current_fsuid(); |
1792 | ||
1da177e4 LT |
1793 | if (!(dir->i_mode & S_ISVTX)) |
1794 | return 0; | |
e795b717 SH |
1795 | if (current_user_ns() != inode_userns(inode)) |
1796 | goto other_userns; | |
da9592ed | 1797 | if (inode->i_uid == fsuid) |
1da177e4 | 1798 | return 0; |
da9592ed | 1799 | if (dir->i_uid == fsuid) |
1da177e4 | 1800 | return 0; |
e795b717 SH |
1801 | |
1802 | other_userns: | |
1803 | return !ns_capable(inode_userns(inode), CAP_FOWNER); | |
1da177e4 LT |
1804 | } |
1805 | ||
1806 | /* | |
1807 | * Check whether we can remove a link victim from directory dir, check | |
1808 | * whether the type of victim is right. | |
1809 | * 1. We can't do it if dir is read-only (done in permission()) | |
1810 | * 2. We should have write and exec permissions on dir | |
1811 | * 3. We can't remove anything from append-only dir | |
1812 | * 4. We can't do anything with immutable dir (done in permission()) | |
1813 | * 5. If the sticky bit on dir is set we should either | |
1814 | * a. be owner of dir, or | |
1815 | * b. be owner of victim, or | |
1816 | * c. have CAP_FOWNER capability | |
1817 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
1818 | * links pointing to it. | |
1819 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
1820 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
1821 | * 9. We can't remove a root or mountpoint. | |
1822 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
1823 | * nfs_async_unlink(). | |
1824 | */ | |
858119e1 | 1825 | static int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
1da177e4 LT |
1826 | { |
1827 | int error; | |
1828 | ||
1829 | if (!victim->d_inode) | |
1830 | return -ENOENT; | |
1831 | ||
1832 | BUG_ON(victim->d_parent->d_inode != dir); | |
cccc6bba | 1833 | audit_inode_child(victim, dir); |
1da177e4 | 1834 | |
f419a2e3 | 1835 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
1836 | if (error) |
1837 | return error; | |
1838 | if (IS_APPEND(dir)) | |
1839 | return -EPERM; | |
1840 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| | |
f9454548 | 1841 | IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) |
1da177e4 LT |
1842 | return -EPERM; |
1843 | if (isdir) { | |
1844 | if (!S_ISDIR(victim->d_inode->i_mode)) | |
1845 | return -ENOTDIR; | |
1846 | if (IS_ROOT(victim)) | |
1847 | return -EBUSY; | |
1848 | } else if (S_ISDIR(victim->d_inode->i_mode)) | |
1849 | return -EISDIR; | |
1850 | if (IS_DEADDIR(dir)) | |
1851 | return -ENOENT; | |
1852 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
1853 | return -EBUSY; | |
1854 | return 0; | |
1855 | } | |
1856 | ||
1857 | /* Check whether we can create an object with dentry child in directory | |
1858 | * dir. | |
1859 | * 1. We can't do it if child already exists (open has special treatment for | |
1860 | * this case, but since we are inlined it's OK) | |
1861 | * 2. We can't do it if dir is read-only (done in permission()) | |
1862 | * 3. We should have write and exec permissions on dir | |
1863 | * 4. We can't do it if dir is immutable (done in permission()) | |
1864 | */ | |
a95164d9 | 1865 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 LT |
1866 | { |
1867 | if (child->d_inode) | |
1868 | return -EEXIST; | |
1869 | if (IS_DEADDIR(dir)) | |
1870 | return -ENOENT; | |
f419a2e3 | 1871 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
1872 | } |
1873 | ||
1da177e4 LT |
1874 | /* |
1875 | * p1 and p2 should be directories on the same fs. | |
1876 | */ | |
1877 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
1878 | { | |
1879 | struct dentry *p; | |
1880 | ||
1881 | if (p1 == p2) { | |
f2eace23 | 1882 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
1883 | return NULL; |
1884 | } | |
1885 | ||
a11f3a05 | 1886 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 | 1887 | |
e2761a11 OH |
1888 | p = d_ancestor(p2, p1); |
1889 | if (p) { | |
1890 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); | |
1891 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
1892 | return p; | |
1da177e4 LT |
1893 | } |
1894 | ||
e2761a11 OH |
1895 | p = d_ancestor(p1, p2); |
1896 | if (p) { | |
1897 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); | |
1898 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1899 | return p; | |
1da177e4 LT |
1900 | } |
1901 | ||
f2eace23 IM |
1902 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1903 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1da177e4 LT |
1904 | return NULL; |
1905 | } | |
1906 | ||
1907 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
1908 | { | |
1b1dcc1b | 1909 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 1910 | if (p1 != p2) { |
1b1dcc1b | 1911 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 1912 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
1913 | } |
1914 | } | |
1915 | ||
1916 | int vfs_create(struct inode *dir, struct dentry *dentry, int mode, | |
1917 | struct nameidata *nd) | |
1918 | { | |
a95164d9 | 1919 | int error = may_create(dir, dentry); |
1da177e4 LT |
1920 | |
1921 | if (error) | |
1922 | return error; | |
1923 | ||
acfa4380 | 1924 | if (!dir->i_op->create) |
1da177e4 LT |
1925 | return -EACCES; /* shouldn't it be ENOSYS? */ |
1926 | mode &= S_IALLUGO; | |
1927 | mode |= S_IFREG; | |
1928 | error = security_inode_create(dir, dentry, mode); | |
1929 | if (error) | |
1930 | return error; | |
1da177e4 | 1931 | error = dir->i_op->create(dir, dentry, mode, nd); |
a74574aa | 1932 | if (!error) |
f38aa942 | 1933 | fsnotify_create(dir, dentry); |
1da177e4 LT |
1934 | return error; |
1935 | } | |
1936 | ||
73d049a4 | 1937 | static int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 1938 | { |
3fb64190 | 1939 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
1940 | struct inode *inode = dentry->d_inode; |
1941 | int error; | |
1942 | ||
bcda7652 AV |
1943 | /* O_PATH? */ |
1944 | if (!acc_mode) | |
1945 | return 0; | |
1946 | ||
1da177e4 LT |
1947 | if (!inode) |
1948 | return -ENOENT; | |
1949 | ||
c8fe8f30 CH |
1950 | switch (inode->i_mode & S_IFMT) { |
1951 | case S_IFLNK: | |
1da177e4 | 1952 | return -ELOOP; |
c8fe8f30 CH |
1953 | case S_IFDIR: |
1954 | if (acc_mode & MAY_WRITE) | |
1955 | return -EISDIR; | |
1956 | break; | |
1957 | case S_IFBLK: | |
1958 | case S_IFCHR: | |
3fb64190 | 1959 | if (path->mnt->mnt_flags & MNT_NODEV) |
1da177e4 | 1960 | return -EACCES; |
c8fe8f30 CH |
1961 | /*FALLTHRU*/ |
1962 | case S_IFIFO: | |
1963 | case S_IFSOCK: | |
1da177e4 | 1964 | flag &= ~O_TRUNC; |
c8fe8f30 | 1965 | break; |
4a3fd211 | 1966 | } |
b41572e9 | 1967 | |
3fb64190 | 1968 | error = inode_permission(inode, acc_mode); |
b41572e9 DH |
1969 | if (error) |
1970 | return error; | |
6146f0d5 | 1971 | |
1da177e4 LT |
1972 | /* |
1973 | * An append-only file must be opened in append mode for writing. | |
1974 | */ | |
1975 | if (IS_APPEND(inode)) { | |
8737c930 | 1976 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
7715b521 | 1977 | return -EPERM; |
1da177e4 | 1978 | if (flag & O_TRUNC) |
7715b521 | 1979 | return -EPERM; |
1da177e4 LT |
1980 | } |
1981 | ||
1982 | /* O_NOATIME can only be set by the owner or superuser */ | |
2e149670 | 1983 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
7715b521 | 1984 | return -EPERM; |
1da177e4 LT |
1985 | |
1986 | /* | |
1987 | * Ensure there are no outstanding leases on the file. | |
1988 | */ | |
b65a9cfc | 1989 | return break_lease(inode, flag); |
7715b521 | 1990 | } |
1da177e4 | 1991 | |
e1181ee6 | 1992 | static int handle_truncate(struct file *filp) |
7715b521 | 1993 | { |
e1181ee6 | 1994 | struct path *path = &filp->f_path; |
7715b521 AV |
1995 | struct inode *inode = path->dentry->d_inode; |
1996 | int error = get_write_access(inode); | |
1997 | if (error) | |
1998 | return error; | |
1999 | /* | |
2000 | * Refuse to truncate files with mandatory locks held on them. | |
2001 | */ | |
2002 | error = locks_verify_locked(inode); | |
2003 | if (!error) | |
ea0d3ab2 | 2004 | error = security_path_truncate(path); |
7715b521 AV |
2005 | if (!error) { |
2006 | error = do_truncate(path->dentry, 0, | |
2007 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
e1181ee6 | 2008 | filp); |
7715b521 AV |
2009 | } |
2010 | put_write_access(inode); | |
acd0c935 | 2011 | return error; |
1da177e4 LT |
2012 | } |
2013 | ||
d57999e1 DH |
2014 | static inline int open_to_namei_flags(int flag) |
2015 | { | |
8a5e929d AV |
2016 | if ((flag & O_ACCMODE) == 3) |
2017 | flag--; | |
d57999e1 DH |
2018 | return flag; |
2019 | } | |
2020 | ||
31e6b01f | 2021 | /* |
fe2d35ff | 2022 | * Handle the last step of open() |
31e6b01f | 2023 | */ |
fb1cc555 | 2024 | static struct file *do_last(struct nameidata *nd, struct path *path, |
c3e380b0 | 2025 | const struct open_flags *op, const char *pathname) |
fb1cc555 | 2026 | { |
a1e28038 | 2027 | struct dentry *dir = nd->path.dentry; |
6c0d46c4 | 2028 | struct dentry *dentry; |
ca344a89 | 2029 | int open_flag = op->open_flag; |
6c0d46c4 | 2030 | int will_truncate = open_flag & O_TRUNC; |
ca344a89 | 2031 | int want_write = 0; |
bcda7652 | 2032 | int acc_mode = op->acc_mode; |
fb1cc555 | 2033 | struct file *filp; |
16c2cd71 | 2034 | int error; |
1f36f774 | 2035 | |
c3e380b0 AV |
2036 | nd->flags &= ~LOOKUP_PARENT; |
2037 | nd->flags |= op->intent; | |
2038 | ||
1f36f774 AV |
2039 | switch (nd->last_type) { |
2040 | case LAST_DOTDOT: | |
176306f5 | 2041 | case LAST_DOT: |
fe2d35ff AV |
2042 | error = handle_dots(nd, nd->last_type); |
2043 | if (error) | |
2044 | return ERR_PTR(error); | |
1f36f774 | 2045 | /* fallthrough */ |
1f36f774 | 2046 | case LAST_ROOT: |
9f1fafee | 2047 | error = complete_walk(nd); |
16c2cd71 | 2048 | if (error) |
9f1fafee | 2049 | return ERR_PTR(error); |
fe2d35ff | 2050 | audit_inode(pathname, nd->path.dentry); |
ca344a89 | 2051 | if (open_flag & O_CREAT) { |
fe2d35ff AV |
2052 | error = -EISDIR; |
2053 | goto exit; | |
2054 | } | |
2055 | goto ok; | |
1f36f774 | 2056 | case LAST_BIND: |
9f1fafee | 2057 | error = complete_walk(nd); |
16c2cd71 | 2058 | if (error) |
9f1fafee | 2059 | return ERR_PTR(error); |
1f36f774 | 2060 | audit_inode(pathname, dir); |
67ee3ad2 | 2061 | goto ok; |
1f36f774 | 2062 | } |
67ee3ad2 | 2063 | |
ca344a89 | 2064 | if (!(open_flag & O_CREAT)) { |
bcda7652 | 2065 | int symlink_ok = 0; |
fe2d35ff AV |
2066 | if (nd->last.name[nd->last.len]) |
2067 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
bcda7652 AV |
2068 | if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) |
2069 | symlink_ok = 1; | |
fe2d35ff | 2070 | /* we _can_ be in RCU mode here */ |
ce57dfc1 AV |
2071 | error = walk_component(nd, path, &nd->last, LAST_NORM, |
2072 | !symlink_ok); | |
2073 | if (error < 0) | |
fe2d35ff | 2074 | return ERR_PTR(error); |
ce57dfc1 | 2075 | if (error) /* symlink */ |
fe2d35ff | 2076 | return NULL; |
fe2d35ff | 2077 | /* sayonara */ |
9f1fafee AV |
2078 | error = complete_walk(nd); |
2079 | if (error) | |
2080 | return ERR_PTR(-ECHILD); | |
fe2d35ff AV |
2081 | |
2082 | error = -ENOTDIR; | |
2083 | if (nd->flags & LOOKUP_DIRECTORY) { | |
ce57dfc1 | 2084 | if (!nd->inode->i_op->lookup) |
fe2d35ff AV |
2085 | goto exit; |
2086 | } | |
2087 | audit_inode(pathname, nd->path.dentry); | |
2088 | goto ok; | |
2089 | } | |
2090 | ||
2091 | /* create side of things */ | |
9f1fafee AV |
2092 | error = complete_walk(nd); |
2093 | if (error) | |
2094 | return ERR_PTR(error); | |
fe2d35ff AV |
2095 | |
2096 | audit_inode(pathname, dir); | |
16c2cd71 | 2097 | error = -EISDIR; |
1f36f774 | 2098 | /* trailing slashes? */ |
31e6b01f NP |
2099 | if (nd->last.name[nd->last.len]) |
2100 | goto exit; | |
a2c36b45 | 2101 | |
a1e28038 AV |
2102 | mutex_lock(&dir->d_inode->i_mutex); |
2103 | ||
6c0d46c4 AV |
2104 | dentry = lookup_hash(nd); |
2105 | error = PTR_ERR(dentry); | |
2106 | if (IS_ERR(dentry)) { | |
fb1cc555 AV |
2107 | mutex_unlock(&dir->d_inode->i_mutex); |
2108 | goto exit; | |
2109 | } | |
2110 | ||
6c0d46c4 AV |
2111 | path->dentry = dentry; |
2112 | path->mnt = nd->path.mnt; | |
2113 | ||
fb1cc555 | 2114 | /* Negative dentry, just create the file */ |
6c0d46c4 AV |
2115 | if (!dentry->d_inode) { |
2116 | int mode = op->mode; | |
2117 | if (!IS_POSIXACL(dir->d_inode)) | |
2118 | mode &= ~current_umask(); | |
fb1cc555 AV |
2119 | /* |
2120 | * This write is needed to ensure that a | |
6c0d46c4 | 2121 | * rw->ro transition does not occur between |
fb1cc555 AV |
2122 | * the time when the file is created and when |
2123 | * a permanent write count is taken through | |
2124 | * the 'struct file' in nameidata_to_filp(). | |
2125 | */ | |
2126 | error = mnt_want_write(nd->path.mnt); | |
2127 | if (error) | |
2128 | goto exit_mutex_unlock; | |
ca344a89 | 2129 | want_write = 1; |
9b44f1b3 | 2130 | /* Don't check for write permission, don't truncate */ |
ca344a89 | 2131 | open_flag &= ~O_TRUNC; |
6c0d46c4 | 2132 | will_truncate = 0; |
bcda7652 | 2133 | acc_mode = MAY_OPEN; |
6c0d46c4 AV |
2134 | error = security_path_mknod(&nd->path, dentry, mode, 0); |
2135 | if (error) | |
2136 | goto exit_mutex_unlock; | |
2137 | error = vfs_create(dir->d_inode, dentry, mode, nd); | |
2138 | if (error) | |
2139 | goto exit_mutex_unlock; | |
2140 | mutex_unlock(&dir->d_inode->i_mutex); | |
2141 | dput(nd->path.dentry); | |
2142 | nd->path.dentry = dentry; | |
ca344a89 | 2143 | goto common; |
fb1cc555 AV |
2144 | } |
2145 | ||
2146 | /* | |
2147 | * It already exists. | |
2148 | */ | |
2149 | mutex_unlock(&dir->d_inode->i_mutex); | |
2150 | audit_inode(pathname, path->dentry); | |
2151 | ||
2152 | error = -EEXIST; | |
ca344a89 | 2153 | if (open_flag & O_EXCL) |
fb1cc555 AV |
2154 | goto exit_dput; |
2155 | ||
9875cf80 DH |
2156 | error = follow_managed(path, nd->flags); |
2157 | if (error < 0) | |
2158 | goto exit_dput; | |
fb1cc555 AV |
2159 | |
2160 | error = -ENOENT; | |
2161 | if (!path->dentry->d_inode) | |
2162 | goto exit_dput; | |
9e67f361 AV |
2163 | |
2164 | if (path->dentry->d_inode->i_op->follow_link) | |
fb1cc555 | 2165 | return NULL; |
fb1cc555 AV |
2166 | |
2167 | path_to_nameidata(path, nd); | |
31e6b01f | 2168 | nd->inode = path->dentry->d_inode; |
fb1cc555 | 2169 | error = -EISDIR; |
31e6b01f | 2170 | if (S_ISDIR(nd->inode->i_mode)) |
fb1cc555 | 2171 | goto exit; |
67ee3ad2 | 2172 | ok: |
6c0d46c4 AV |
2173 | if (!S_ISREG(nd->inode->i_mode)) |
2174 | will_truncate = 0; | |
2175 | ||
0f9d1a10 AV |
2176 | if (will_truncate) { |
2177 | error = mnt_want_write(nd->path.mnt); | |
2178 | if (error) | |
2179 | goto exit; | |
ca344a89 | 2180 | want_write = 1; |
0f9d1a10 | 2181 | } |
ca344a89 | 2182 | common: |
bcda7652 | 2183 | error = may_open(&nd->path, acc_mode, open_flag); |
ca344a89 | 2184 | if (error) |
0f9d1a10 | 2185 | goto exit; |
0f9d1a10 AV |
2186 | filp = nameidata_to_filp(nd); |
2187 | if (!IS_ERR(filp)) { | |
2188 | error = ima_file_check(filp, op->acc_mode); | |
2189 | if (error) { | |
2190 | fput(filp); | |
2191 | filp = ERR_PTR(error); | |
2192 | } | |
2193 | } | |
2194 | if (!IS_ERR(filp)) { | |
2195 | if (will_truncate) { | |
2196 | error = handle_truncate(filp); | |
2197 | if (error) { | |
2198 | fput(filp); | |
2199 | filp = ERR_PTR(error); | |
2200 | } | |
2201 | } | |
2202 | } | |
ca344a89 AV |
2203 | out: |
2204 | if (want_write) | |
0f9d1a10 AV |
2205 | mnt_drop_write(nd->path.mnt); |
2206 | path_put(&nd->path); | |
fb1cc555 AV |
2207 | return filp; |
2208 | ||
2209 | exit_mutex_unlock: | |
2210 | mutex_unlock(&dir->d_inode->i_mutex); | |
2211 | exit_dput: | |
2212 | path_put_conditional(path, nd); | |
2213 | exit: | |
ca344a89 AV |
2214 | filp = ERR_PTR(error); |
2215 | goto out; | |
fb1cc555 AV |
2216 | } |
2217 | ||
13aab428 | 2218 | static struct file *path_openat(int dfd, const char *pathname, |
73d049a4 | 2219 | struct nameidata *nd, const struct open_flags *op, int flags) |
1da177e4 | 2220 | { |
fe2d35ff | 2221 | struct file *base = NULL; |
4a3fd211 | 2222 | struct file *filp; |
9850c056 | 2223 | struct path path; |
13aab428 | 2224 | int error; |
31e6b01f NP |
2225 | |
2226 | filp = get_empty_filp(); | |
2227 | if (!filp) | |
2228 | return ERR_PTR(-ENFILE); | |
2229 | ||
47c805dc | 2230 | filp->f_flags = op->open_flag; |
73d049a4 AV |
2231 | nd->intent.open.file = filp; |
2232 | nd->intent.open.flags = open_to_namei_flags(op->open_flag); | |
2233 | nd->intent.open.create_mode = op->mode; | |
31e6b01f | 2234 | |
73d049a4 | 2235 | error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); |
31e6b01f | 2236 | if (unlikely(error)) |
13aab428 | 2237 | goto out_filp; |
31e6b01f | 2238 | |
fe2d35ff | 2239 | current->total_link_count = 0; |
73d049a4 | 2240 | error = link_path_walk(pathname, nd); |
31e6b01f NP |
2241 | if (unlikely(error)) |
2242 | goto out_filp; | |
1da177e4 | 2243 | |
73d049a4 | 2244 | filp = do_last(nd, &path, op, pathname); |
806b681c | 2245 | while (unlikely(!filp)) { /* trailing symlink */ |
7b9337aa | 2246 | struct path link = path; |
def4af30 | 2247 | void *cookie; |
574197e0 | 2248 | if (!(nd->flags & LOOKUP_FOLLOW)) { |
73d049a4 AV |
2249 | path_put_conditional(&path, nd); |
2250 | path_put(&nd->path); | |
40b39136 AV |
2251 | filp = ERR_PTR(-ELOOP); |
2252 | break; | |
2253 | } | |
73d049a4 AV |
2254 | nd->flags |= LOOKUP_PARENT; |
2255 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); | |
574197e0 | 2256 | error = follow_link(&link, nd, &cookie); |
c3e380b0 | 2257 | if (unlikely(error)) |
f1afe9ef | 2258 | filp = ERR_PTR(error); |
c3e380b0 | 2259 | else |
73d049a4 | 2260 | filp = do_last(nd, &path, op, pathname); |
574197e0 | 2261 | put_link(nd, &link, cookie); |
806b681c | 2262 | } |
10fa8e62 | 2263 | out: |
73d049a4 AV |
2264 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) |
2265 | path_put(&nd->root); | |
fe2d35ff AV |
2266 | if (base) |
2267 | fput(base); | |
73d049a4 | 2268 | release_open_intent(nd); |
10fa8e62 | 2269 | return filp; |
1da177e4 | 2270 | |
31e6b01f | 2271 | out_filp: |
806b681c | 2272 | filp = ERR_PTR(error); |
10fa8e62 | 2273 | goto out; |
1da177e4 LT |
2274 | } |
2275 | ||
13aab428 AV |
2276 | struct file *do_filp_open(int dfd, const char *pathname, |
2277 | const struct open_flags *op, int flags) | |
2278 | { | |
73d049a4 | 2279 | struct nameidata nd; |
13aab428 AV |
2280 | struct file *filp; |
2281 | ||
73d049a4 | 2282 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); |
13aab428 | 2283 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
73d049a4 | 2284 | filp = path_openat(dfd, pathname, &nd, op, flags); |
13aab428 | 2285 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
73d049a4 | 2286 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); |
13aab428 AV |
2287 | return filp; |
2288 | } | |
2289 | ||
73d049a4 AV |
2290 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
2291 | const char *name, const struct open_flags *op, int flags) | |
2292 | { | |
2293 | struct nameidata nd; | |
2294 | struct file *file; | |
2295 | ||
2296 | nd.root.mnt = mnt; | |
2297 | nd.root.dentry = dentry; | |
2298 | ||
2299 | flags |= LOOKUP_ROOT; | |
2300 | ||
bcda7652 | 2301 | if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) |
73d049a4 AV |
2302 | return ERR_PTR(-ELOOP); |
2303 | ||
2304 | file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); | |
2305 | if (unlikely(file == ERR_PTR(-ECHILD))) | |
2306 | file = path_openat(-1, name, &nd, op, flags); | |
2307 | if (unlikely(file == ERR_PTR(-ESTALE))) | |
2308 | file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); | |
2309 | return file; | |
2310 | } | |
2311 | ||
ed75e95d | 2312 | struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) |
1da177e4 | 2313 | { |
c663e5d8 | 2314 | struct dentry *dentry = ERR_PTR(-EEXIST); |
ed75e95d AV |
2315 | struct nameidata nd; |
2316 | int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); | |
2317 | if (error) | |
2318 | return ERR_PTR(error); | |
1da177e4 | 2319 | |
c663e5d8 CH |
2320 | /* |
2321 | * Yucky last component or no last component at all? | |
2322 | * (foo/., foo/.., /////) | |
2323 | */ | |
ed75e95d AV |
2324 | if (nd.last_type != LAST_NORM) |
2325 | goto out; | |
2326 | nd.flags &= ~LOOKUP_PARENT; | |
2327 | nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; | |
2328 | nd.intent.open.flags = O_EXCL; | |
c663e5d8 CH |
2329 | |
2330 | /* | |
2331 | * Do the final lookup. | |
2332 | */ | |
ed75e95d AV |
2333 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
2334 | dentry = lookup_hash(&nd); | |
1da177e4 LT |
2335 | if (IS_ERR(dentry)) |
2336 | goto fail; | |
c663e5d8 | 2337 | |
e9baf6e5 AV |
2338 | if (dentry->d_inode) |
2339 | goto eexist; | |
c663e5d8 CH |
2340 | /* |
2341 | * Special case - lookup gave negative, but... we had foo/bar/ | |
2342 | * From the vfs_mknod() POV we just have a negative dentry - | |
2343 | * all is fine. Let's be bastards - you had / on the end, you've | |
2344 | * been asking for (non-existent) directory. -ENOENT for you. | |
2345 | */ | |
ed75e95d | 2346 | if (unlikely(!is_dir && nd.last.name[nd.last.len])) { |
e9baf6e5 AV |
2347 | dput(dentry); |
2348 | dentry = ERR_PTR(-ENOENT); | |
ed75e95d | 2349 | goto fail; |
e9baf6e5 | 2350 | } |
ed75e95d | 2351 | *path = nd.path; |
1da177e4 | 2352 | return dentry; |
e9baf6e5 | 2353 | eexist: |
1da177e4 | 2354 | dput(dentry); |
e9baf6e5 | 2355 | dentry = ERR_PTR(-EEXIST); |
1da177e4 | 2356 | fail: |
ed75e95d AV |
2357 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
2358 | out: | |
2359 | path_put(&nd.path); | |
1da177e4 LT |
2360 | return dentry; |
2361 | } | |
dae6ad8f AV |
2362 | EXPORT_SYMBOL(kern_path_create); |
2363 | ||
2364 | struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) | |
2365 | { | |
2366 | char *tmp = getname(pathname); | |
2367 | struct dentry *res; | |
2368 | if (IS_ERR(tmp)) | |
2369 | return ERR_CAST(tmp); | |
2370 | res = kern_path_create(dfd, tmp, path, is_dir); | |
2371 | putname(tmp); | |
2372 | return res; | |
2373 | } | |
2374 | EXPORT_SYMBOL(user_path_create); | |
2375 | ||
1da177e4 LT |
2376 | int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) |
2377 | { | |
a95164d9 | 2378 | int error = may_create(dir, dentry); |
1da177e4 LT |
2379 | |
2380 | if (error) | |
2381 | return error; | |
2382 | ||
e795b717 SH |
2383 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && |
2384 | !ns_capable(inode_userns(dir), CAP_MKNOD)) | |
1da177e4 LT |
2385 | return -EPERM; |
2386 | ||
acfa4380 | 2387 | if (!dir->i_op->mknod) |
1da177e4 LT |
2388 | return -EPERM; |
2389 | ||
08ce5f16 SH |
2390 | error = devcgroup_inode_mknod(mode, dev); |
2391 | if (error) | |
2392 | return error; | |
2393 | ||
1da177e4 LT |
2394 | error = security_inode_mknod(dir, dentry, mode, dev); |
2395 | if (error) | |
2396 | return error; | |
2397 | ||
1da177e4 | 2398 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 2399 | if (!error) |
f38aa942 | 2400 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2401 | return error; |
2402 | } | |
2403 | ||
463c3197 DH |
2404 | static int may_mknod(mode_t mode) |
2405 | { | |
2406 | switch (mode & S_IFMT) { | |
2407 | case S_IFREG: | |
2408 | case S_IFCHR: | |
2409 | case S_IFBLK: | |
2410 | case S_IFIFO: | |
2411 | case S_IFSOCK: | |
2412 | case 0: /* zero mode translates to S_IFREG */ | |
2413 | return 0; | |
2414 | case S_IFDIR: | |
2415 | return -EPERM; | |
2416 | default: | |
2417 | return -EINVAL; | |
2418 | } | |
2419 | } | |
2420 | ||
2e4d0924 HC |
2421 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, |
2422 | unsigned, dev) | |
1da177e4 | 2423 | { |
2ad94ae6 | 2424 | struct dentry *dentry; |
dae6ad8f AV |
2425 | struct path path; |
2426 | int error; | |
1da177e4 LT |
2427 | |
2428 | if (S_ISDIR(mode)) | |
2429 | return -EPERM; | |
1da177e4 | 2430 | |
dae6ad8f AV |
2431 | dentry = user_path_create(dfd, filename, &path, 0); |
2432 | if (IS_ERR(dentry)) | |
2433 | return PTR_ERR(dentry); | |
2ad94ae6 | 2434 | |
dae6ad8f | 2435 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 2436 | mode &= ~current_umask(); |
463c3197 DH |
2437 | error = may_mknod(mode); |
2438 | if (error) | |
2439 | goto out_dput; | |
dae6ad8f | 2440 | error = mnt_want_write(path.mnt); |
463c3197 DH |
2441 | if (error) |
2442 | goto out_dput; | |
dae6ad8f | 2443 | error = security_path_mknod(&path, dentry, mode, dev); |
be6d3e56 KT |
2444 | if (error) |
2445 | goto out_drop_write; | |
463c3197 | 2446 | switch (mode & S_IFMT) { |
1da177e4 | 2447 | case 0: case S_IFREG: |
dae6ad8f | 2448 | error = vfs_create(path.dentry->d_inode,dentry,mode,NULL); |
1da177e4 LT |
2449 | break; |
2450 | case S_IFCHR: case S_IFBLK: | |
dae6ad8f | 2451 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
2452 | new_decode_dev(dev)); |
2453 | break; | |
2454 | case S_IFIFO: case S_IFSOCK: | |
dae6ad8f | 2455 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 2456 | break; |
1da177e4 | 2457 | } |
be6d3e56 | 2458 | out_drop_write: |
dae6ad8f | 2459 | mnt_drop_write(path.mnt); |
463c3197 DH |
2460 | out_dput: |
2461 | dput(dentry); | |
dae6ad8f AV |
2462 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
2463 | path_put(&path); | |
1da177e4 LT |
2464 | |
2465 | return error; | |
2466 | } | |
2467 | ||
3480b257 | 2468 | SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) |
5590ff0d UD |
2469 | { |
2470 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
2471 | } | |
2472 | ||
1da177e4 LT |
2473 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
2474 | { | |
a95164d9 | 2475 | int error = may_create(dir, dentry); |
1da177e4 LT |
2476 | |
2477 | if (error) | |
2478 | return error; | |
2479 | ||
acfa4380 | 2480 | if (!dir->i_op->mkdir) |
1da177e4 LT |
2481 | return -EPERM; |
2482 | ||
2483 | mode &= (S_IRWXUGO|S_ISVTX); | |
2484 | error = security_inode_mkdir(dir, dentry, mode); | |
2485 | if (error) | |
2486 | return error; | |
2487 | ||
1da177e4 | 2488 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 2489 | if (!error) |
f38aa942 | 2490 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
2491 | return error; |
2492 | } | |
2493 | ||
2e4d0924 | 2494 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) |
1da177e4 | 2495 | { |
6902d925 | 2496 | struct dentry *dentry; |
dae6ad8f AV |
2497 | struct path path; |
2498 | int error; | |
1da177e4 | 2499 | |
dae6ad8f | 2500 | dentry = user_path_create(dfd, pathname, &path, 1); |
6902d925 | 2501 | if (IS_ERR(dentry)) |
dae6ad8f | 2502 | return PTR_ERR(dentry); |
1da177e4 | 2503 | |
dae6ad8f | 2504 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 2505 | mode &= ~current_umask(); |
dae6ad8f | 2506 | error = mnt_want_write(path.mnt); |
463c3197 DH |
2507 | if (error) |
2508 | goto out_dput; | |
dae6ad8f | 2509 | error = security_path_mkdir(&path, dentry, mode); |
be6d3e56 KT |
2510 | if (error) |
2511 | goto out_drop_write; | |
dae6ad8f | 2512 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); |
be6d3e56 | 2513 | out_drop_write: |
dae6ad8f | 2514 | mnt_drop_write(path.mnt); |
463c3197 | 2515 | out_dput: |
6902d925 | 2516 | dput(dentry); |
dae6ad8f AV |
2517 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
2518 | path_put(&path); | |
1da177e4 LT |
2519 | return error; |
2520 | } | |
2521 | ||
3cdad428 | 2522 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) |
5590ff0d UD |
2523 | { |
2524 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
2525 | } | |
2526 | ||
1da177e4 | 2527 | /* |
a71905f0 SW |
2528 | * The dentry_unhash() helper will try to drop the dentry early: we |
2529 | * should have a usage count of 2 if we're the only user of this | |
2530 | * dentry, and if that is true (possibly after pruning the dcache), | |
2531 | * then we drop the dentry now. | |
1da177e4 LT |
2532 | * |
2533 | * A low-level filesystem can, if it choses, legally | |
2534 | * do a | |
2535 | * | |
2536 | * if (!d_unhashed(dentry)) | |
2537 | * return -EBUSY; | |
2538 | * | |
2539 | * if it cannot handle the case of removing a directory | |
2540 | * that is still in use by something else.. | |
2541 | */ | |
2542 | void dentry_unhash(struct dentry *dentry) | |
2543 | { | |
dc168427 | 2544 | shrink_dcache_parent(dentry); |
1da177e4 | 2545 | spin_lock(&dentry->d_lock); |
64252c75 | 2546 | if (dentry->d_count == 1) |
1da177e4 LT |
2547 | __d_drop(dentry); |
2548 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
2549 | } |
2550 | ||
2551 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
2552 | { | |
2553 | int error = may_delete(dir, dentry, 1); | |
2554 | ||
2555 | if (error) | |
2556 | return error; | |
2557 | ||
acfa4380 | 2558 | if (!dir->i_op->rmdir) |
1da177e4 LT |
2559 | return -EPERM; |
2560 | ||
1b1dcc1b | 2561 | mutex_lock(&dentry->d_inode->i_mutex); |
912dbc15 SW |
2562 | |
2563 | error = -EBUSY; | |
1da177e4 | 2564 | if (d_mountpoint(dentry)) |
912dbc15 SW |
2565 | goto out; |
2566 | ||
2567 | error = security_inode_rmdir(dir, dentry); | |
2568 | if (error) | |
2569 | goto out; | |
2570 | ||
3cebde24 | 2571 | shrink_dcache_parent(dentry); |
912dbc15 SW |
2572 | error = dir->i_op->rmdir(dir, dentry); |
2573 | if (error) | |
2574 | goto out; | |
2575 | ||
2576 | dentry->d_inode->i_flags |= S_DEAD; | |
2577 | dont_mount(dentry); | |
2578 | ||
2579 | out: | |
1b1dcc1b | 2580 | mutex_unlock(&dentry->d_inode->i_mutex); |
912dbc15 | 2581 | if (!error) |
1da177e4 | 2582 | d_delete(dentry); |
1da177e4 LT |
2583 | return error; |
2584 | } | |
2585 | ||
5590ff0d | 2586 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
2587 | { |
2588 | int error = 0; | |
2589 | char * name; | |
2590 | struct dentry *dentry; | |
2591 | struct nameidata nd; | |
2592 | ||
2ad94ae6 | 2593 | error = user_path_parent(dfd, pathname, &nd, &name); |
1da177e4 | 2594 | if (error) |
2ad94ae6 | 2595 | return error; |
1da177e4 LT |
2596 | |
2597 | switch(nd.last_type) { | |
0612d9fb OH |
2598 | case LAST_DOTDOT: |
2599 | error = -ENOTEMPTY; | |
2600 | goto exit1; | |
2601 | case LAST_DOT: | |
2602 | error = -EINVAL; | |
2603 | goto exit1; | |
2604 | case LAST_ROOT: | |
2605 | error = -EBUSY; | |
2606 | goto exit1; | |
1da177e4 | 2607 | } |
0612d9fb OH |
2608 | |
2609 | nd.flags &= ~LOOKUP_PARENT; | |
2610 | ||
4ac91378 | 2611 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2612 | dentry = lookup_hash(&nd); |
1da177e4 | 2613 | error = PTR_ERR(dentry); |
6902d925 DH |
2614 | if (IS_ERR(dentry)) |
2615 | goto exit2; | |
e6bc45d6 TT |
2616 | if (!dentry->d_inode) { |
2617 | error = -ENOENT; | |
2618 | goto exit3; | |
2619 | } | |
0622753b DH |
2620 | error = mnt_want_write(nd.path.mnt); |
2621 | if (error) | |
2622 | goto exit3; | |
be6d3e56 KT |
2623 | error = security_path_rmdir(&nd.path, dentry); |
2624 | if (error) | |
2625 | goto exit4; | |
4ac91378 | 2626 | error = vfs_rmdir(nd.path.dentry->d_inode, dentry); |
be6d3e56 | 2627 | exit4: |
0622753b DH |
2628 | mnt_drop_write(nd.path.mnt); |
2629 | exit3: | |
6902d925 DH |
2630 | dput(dentry); |
2631 | exit2: | |
4ac91378 | 2632 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 | 2633 | exit1: |
1d957f9b | 2634 | path_put(&nd.path); |
1da177e4 LT |
2635 | putname(name); |
2636 | return error; | |
2637 | } | |
2638 | ||
3cdad428 | 2639 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
2640 | { |
2641 | return do_rmdir(AT_FDCWD, pathname); | |
2642 | } | |
2643 | ||
1da177e4 LT |
2644 | int vfs_unlink(struct inode *dir, struct dentry *dentry) |
2645 | { | |
2646 | int error = may_delete(dir, dentry, 0); | |
2647 | ||
2648 | if (error) | |
2649 | return error; | |
2650 | ||
acfa4380 | 2651 | if (!dir->i_op->unlink) |
1da177e4 LT |
2652 | return -EPERM; |
2653 | ||
1b1dcc1b | 2654 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2655 | if (d_mountpoint(dentry)) |
2656 | error = -EBUSY; | |
2657 | else { | |
2658 | error = security_inode_unlink(dir, dentry); | |
bec1052e | 2659 | if (!error) { |
1da177e4 | 2660 | error = dir->i_op->unlink(dir, dentry); |
bec1052e | 2661 | if (!error) |
d83c49f3 | 2662 | dont_mount(dentry); |
bec1052e | 2663 | } |
1da177e4 | 2664 | } |
1b1dcc1b | 2665 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2666 | |
2667 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
2668 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
ece95912 | 2669 | fsnotify_link_count(dentry->d_inode); |
e234f35c | 2670 | d_delete(dentry); |
1da177e4 | 2671 | } |
0eeca283 | 2672 | |
1da177e4 LT |
2673 | return error; |
2674 | } | |
2675 | ||
2676 | /* | |
2677 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 2678 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
2679 | * writeout happening, and we don't want to prevent access to the directory |
2680 | * while waiting on the I/O. | |
2681 | */ | |
5590ff0d | 2682 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 2683 | { |
2ad94ae6 AV |
2684 | int error; |
2685 | char *name; | |
1da177e4 LT |
2686 | struct dentry *dentry; |
2687 | struct nameidata nd; | |
2688 | struct inode *inode = NULL; | |
2689 | ||
2ad94ae6 | 2690 | error = user_path_parent(dfd, pathname, &nd, &name); |
1da177e4 | 2691 | if (error) |
2ad94ae6 AV |
2692 | return error; |
2693 | ||
1da177e4 LT |
2694 | error = -EISDIR; |
2695 | if (nd.last_type != LAST_NORM) | |
2696 | goto exit1; | |
0612d9fb OH |
2697 | |
2698 | nd.flags &= ~LOOKUP_PARENT; | |
2699 | ||
4ac91378 | 2700 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2701 | dentry = lookup_hash(&nd); |
1da177e4 LT |
2702 | error = PTR_ERR(dentry); |
2703 | if (!IS_ERR(dentry)) { | |
2704 | /* Why not before? Because we want correct error value */ | |
50338b88 TE |
2705 | if (nd.last.name[nd.last.len]) |
2706 | goto slashes; | |
1da177e4 | 2707 | inode = dentry->d_inode; |
50338b88 | 2708 | if (!inode) |
e6bc45d6 TT |
2709 | goto slashes; |
2710 | ihold(inode); | |
0622753b DH |
2711 | error = mnt_want_write(nd.path.mnt); |
2712 | if (error) | |
2713 | goto exit2; | |
be6d3e56 KT |
2714 | error = security_path_unlink(&nd.path, dentry); |
2715 | if (error) | |
2716 | goto exit3; | |
4ac91378 | 2717 | error = vfs_unlink(nd.path.dentry->d_inode, dentry); |
be6d3e56 | 2718 | exit3: |
0622753b | 2719 | mnt_drop_write(nd.path.mnt); |
1da177e4 LT |
2720 | exit2: |
2721 | dput(dentry); | |
2722 | } | |
4ac91378 | 2723 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 LT |
2724 | if (inode) |
2725 | iput(inode); /* truncate the inode here */ | |
2726 | exit1: | |
1d957f9b | 2727 | path_put(&nd.path); |
1da177e4 LT |
2728 | putname(name); |
2729 | return error; | |
2730 | ||
2731 | slashes: | |
2732 | error = !dentry->d_inode ? -ENOENT : | |
2733 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; | |
2734 | goto exit2; | |
2735 | } | |
2736 | ||
2e4d0924 | 2737 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
2738 | { |
2739 | if ((flag & ~AT_REMOVEDIR) != 0) | |
2740 | return -EINVAL; | |
2741 | ||
2742 | if (flag & AT_REMOVEDIR) | |
2743 | return do_rmdir(dfd, pathname); | |
2744 | ||
2745 | return do_unlinkat(dfd, pathname); | |
2746 | } | |
2747 | ||
3480b257 | 2748 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
2749 | { |
2750 | return do_unlinkat(AT_FDCWD, pathname); | |
2751 | } | |
2752 | ||
db2e747b | 2753 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 2754 | { |
a95164d9 | 2755 | int error = may_create(dir, dentry); |
1da177e4 LT |
2756 | |
2757 | if (error) | |
2758 | return error; | |
2759 | ||
acfa4380 | 2760 | if (!dir->i_op->symlink) |
1da177e4 LT |
2761 | return -EPERM; |
2762 | ||
2763 | error = security_inode_symlink(dir, dentry, oldname); | |
2764 | if (error) | |
2765 | return error; | |
2766 | ||
1da177e4 | 2767 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 2768 | if (!error) |
f38aa942 | 2769 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2770 | return error; |
2771 | } | |
2772 | ||
2e4d0924 HC |
2773 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
2774 | int, newdfd, const char __user *, newname) | |
1da177e4 | 2775 | { |
2ad94ae6 AV |
2776 | int error; |
2777 | char *from; | |
6902d925 | 2778 | struct dentry *dentry; |
dae6ad8f | 2779 | struct path path; |
1da177e4 LT |
2780 | |
2781 | from = getname(oldname); | |
2ad94ae6 | 2782 | if (IS_ERR(from)) |
1da177e4 | 2783 | return PTR_ERR(from); |
1da177e4 | 2784 | |
dae6ad8f | 2785 | dentry = user_path_create(newdfd, newname, &path, 0); |
6902d925 DH |
2786 | error = PTR_ERR(dentry); |
2787 | if (IS_ERR(dentry)) | |
dae6ad8f | 2788 | goto out_putname; |
6902d925 | 2789 | |
dae6ad8f | 2790 | error = mnt_want_write(path.mnt); |
75c3f29d DH |
2791 | if (error) |
2792 | goto out_dput; | |
dae6ad8f | 2793 | error = security_path_symlink(&path, dentry, from); |
be6d3e56 KT |
2794 | if (error) |
2795 | goto out_drop_write; | |
dae6ad8f | 2796 | error = vfs_symlink(path.dentry->d_inode, dentry, from); |
be6d3e56 | 2797 | out_drop_write: |
dae6ad8f | 2798 | mnt_drop_write(path.mnt); |
75c3f29d | 2799 | out_dput: |
6902d925 | 2800 | dput(dentry); |
dae6ad8f AV |
2801 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
2802 | path_put(&path); | |
6902d925 | 2803 | out_putname: |
1da177e4 LT |
2804 | putname(from); |
2805 | return error; | |
2806 | } | |
2807 | ||
3480b257 | 2808 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
2809 | { |
2810 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
2811 | } | |
2812 | ||
1da177e4 LT |
2813 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
2814 | { | |
2815 | struct inode *inode = old_dentry->d_inode; | |
2816 | int error; | |
2817 | ||
2818 | if (!inode) | |
2819 | return -ENOENT; | |
2820 | ||
a95164d9 | 2821 | error = may_create(dir, new_dentry); |
1da177e4 LT |
2822 | if (error) |
2823 | return error; | |
2824 | ||
2825 | if (dir->i_sb != inode->i_sb) | |
2826 | return -EXDEV; | |
2827 | ||
2828 | /* | |
2829 | * A link to an append-only or immutable file cannot be created. | |
2830 | */ | |
2831 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
2832 | return -EPERM; | |
acfa4380 | 2833 | if (!dir->i_op->link) |
1da177e4 | 2834 | return -EPERM; |
7e79eedb | 2835 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
2836 | return -EPERM; |
2837 | ||
2838 | error = security_inode_link(old_dentry, dir, new_dentry); | |
2839 | if (error) | |
2840 | return error; | |
2841 | ||
7e79eedb | 2842 | mutex_lock(&inode->i_mutex); |
aae8a97d AK |
2843 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
2844 | if (inode->i_nlink == 0) | |
2845 | error = -ENOENT; | |
2846 | else | |
2847 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
7e79eedb | 2848 | mutex_unlock(&inode->i_mutex); |
e31e14ec | 2849 | if (!error) |
7e79eedb | 2850 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
2851 | return error; |
2852 | } | |
2853 | ||
2854 | /* | |
2855 | * Hardlinks are often used in delicate situations. We avoid | |
2856 | * security-related surprises by not following symlinks on the | |
2857 | * newname. --KAB | |
2858 | * | |
2859 | * We don't follow them on the oldname either to be compatible | |
2860 | * with linux 2.0, and to avoid hard-linking to directories | |
2861 | * and other special files. --ADM | |
2862 | */ | |
2e4d0924 HC |
2863 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
2864 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
2865 | { |
2866 | struct dentry *new_dentry; | |
dae6ad8f | 2867 | struct path old_path, new_path; |
11a7b371 | 2868 | int how = 0; |
1da177e4 | 2869 | int error; |
1da177e4 | 2870 | |
11a7b371 | 2871 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
c04030e1 | 2872 | return -EINVAL; |
11a7b371 AK |
2873 | /* |
2874 | * To use null names we require CAP_DAC_READ_SEARCH | |
2875 | * This ensures that not everyone will be able to create | |
2876 | * handlink using the passed filedescriptor. | |
2877 | */ | |
2878 | if (flags & AT_EMPTY_PATH) { | |
2879 | if (!capable(CAP_DAC_READ_SEARCH)) | |
2880 | return -ENOENT; | |
2881 | how = LOOKUP_EMPTY; | |
2882 | } | |
2883 | ||
2884 | if (flags & AT_SYMLINK_FOLLOW) | |
2885 | how |= LOOKUP_FOLLOW; | |
c04030e1 | 2886 | |
11a7b371 | 2887 | error = user_path_at(olddfd, oldname, how, &old_path); |
1da177e4 | 2888 | if (error) |
2ad94ae6 AV |
2889 | return error; |
2890 | ||
dae6ad8f | 2891 | new_dentry = user_path_create(newdfd, newname, &new_path, 0); |
1da177e4 | 2892 | error = PTR_ERR(new_dentry); |
6902d925 | 2893 | if (IS_ERR(new_dentry)) |
dae6ad8f AV |
2894 | goto out; |
2895 | ||
2896 | error = -EXDEV; | |
2897 | if (old_path.mnt != new_path.mnt) | |
2898 | goto out_dput; | |
2899 | error = mnt_want_write(new_path.mnt); | |
75c3f29d DH |
2900 | if (error) |
2901 | goto out_dput; | |
dae6ad8f | 2902 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
be6d3e56 KT |
2903 | if (error) |
2904 | goto out_drop_write; | |
dae6ad8f | 2905 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); |
be6d3e56 | 2906 | out_drop_write: |
dae6ad8f | 2907 | mnt_drop_write(new_path.mnt); |
75c3f29d | 2908 | out_dput: |
6902d925 | 2909 | dput(new_dentry); |
dae6ad8f AV |
2910 | mutex_unlock(&new_path.dentry->d_inode->i_mutex); |
2911 | path_put(&new_path); | |
1da177e4 | 2912 | out: |
2d8f3038 | 2913 | path_put(&old_path); |
1da177e4 LT |
2914 | |
2915 | return error; | |
2916 | } | |
2917 | ||
3480b257 | 2918 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 2919 | { |
c04030e1 | 2920 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
2921 | } |
2922 | ||
1da177e4 LT |
2923 | /* |
2924 | * The worst of all namespace operations - renaming directory. "Perverted" | |
2925 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
2926 | * Problems: | |
2927 | * a) we can get into loop creation. Check is done in is_subdir(). | |
2928 | * b) race potential - two innocent renames can create a loop together. | |
2929 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 2930 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 LT |
2931 | * story. |
2932 | * c) we have to lock _three_ objects - parents and victim (if it exists). | |
1b1dcc1b | 2933 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
2934 | * whether the target exists). Solution: try to be smart with locking |
2935 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 2936 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
2937 | * move will be locked. Thus we can rank directories by the tree |
2938 | * (ancestors first) and rank all non-directories after them. | |
2939 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 2940 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
2941 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
2942 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
2943 | * we'd better make sure that there's no link(2) for them. | |
e4eaac06 | 2944 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
1b1dcc1b | 2945 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 2946 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
c41b20e7 | 2947 | * ->i_mutex on parents, which works but leads to some truly excessive |
1da177e4 LT |
2948 | * locking]. |
2949 | */ | |
75c96f85 AB |
2950 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
2951 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2952 | { |
2953 | int error = 0; | |
9055cba7 | 2954 | struct inode *target = new_dentry->d_inode; |
1da177e4 LT |
2955 | |
2956 | /* | |
2957 | * If we are going to change the parent - check write permissions, | |
2958 | * we'll need to flip '..'. | |
2959 | */ | |
2960 | if (new_dir != old_dir) { | |
f419a2e3 | 2961 | error = inode_permission(old_dentry->d_inode, MAY_WRITE); |
1da177e4 LT |
2962 | if (error) |
2963 | return error; | |
2964 | } | |
2965 | ||
2966 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2967 | if (error) | |
2968 | return error; | |
2969 | ||
d83c49f3 | 2970 | if (target) |
1b1dcc1b | 2971 | mutex_lock(&target->i_mutex); |
9055cba7 SW |
2972 | |
2973 | error = -EBUSY; | |
2974 | if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) | |
2975 | goto out; | |
2976 | ||
3cebde24 SW |
2977 | if (target) |
2978 | shrink_dcache_parent(new_dentry); | |
9055cba7 SW |
2979 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
2980 | if (error) | |
2981 | goto out; | |
2982 | ||
1da177e4 | 2983 | if (target) { |
9055cba7 SW |
2984 | target->i_flags |= S_DEAD; |
2985 | dont_mount(new_dentry); | |
1da177e4 | 2986 | } |
9055cba7 SW |
2987 | out: |
2988 | if (target) | |
2989 | mutex_unlock(&target->i_mutex); | |
e31e14ec | 2990 | if (!error) |
349457cc MF |
2991 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
2992 | d_move(old_dentry,new_dentry); | |
1da177e4 LT |
2993 | return error; |
2994 | } | |
2995 | ||
75c96f85 AB |
2996 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
2997 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 | 2998 | { |
51892bbb | 2999 | struct inode *target = new_dentry->d_inode; |
1da177e4 LT |
3000 | int error; |
3001 | ||
3002 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
3003 | if (error) | |
3004 | return error; | |
3005 | ||
3006 | dget(new_dentry); | |
1da177e4 | 3007 | if (target) |
1b1dcc1b | 3008 | mutex_lock(&target->i_mutex); |
51892bbb SW |
3009 | |
3010 | error = -EBUSY; | |
1da177e4 | 3011 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
51892bbb SW |
3012 | goto out; |
3013 | ||
3014 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
3015 | if (error) | |
3016 | goto out; | |
3017 | ||
3018 | if (target) | |
3019 | dont_mount(new_dentry); | |
3020 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) | |
3021 | d_move(old_dentry, new_dentry); | |
3022 | out: | |
1da177e4 | 3023 | if (target) |
1b1dcc1b | 3024 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
3025 | dput(new_dentry); |
3026 | return error; | |
3027 | } | |
3028 | ||
3029 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, | |
3030 | struct inode *new_dir, struct dentry *new_dentry) | |
3031 | { | |
3032 | int error; | |
3033 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); | |
59b0df21 | 3034 | const unsigned char *old_name; |
1da177e4 LT |
3035 | |
3036 | if (old_dentry->d_inode == new_dentry->d_inode) | |
3037 | return 0; | |
3038 | ||
3039 | error = may_delete(old_dir, old_dentry, is_dir); | |
3040 | if (error) | |
3041 | return error; | |
3042 | ||
3043 | if (!new_dentry->d_inode) | |
a95164d9 | 3044 | error = may_create(new_dir, new_dentry); |
1da177e4 LT |
3045 | else |
3046 | error = may_delete(new_dir, new_dentry, is_dir); | |
3047 | if (error) | |
3048 | return error; | |
3049 | ||
acfa4380 | 3050 | if (!old_dir->i_op->rename) |
1da177e4 LT |
3051 | return -EPERM; |
3052 | ||
0eeca283 RL |
3053 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
3054 | ||
1da177e4 LT |
3055 | if (is_dir) |
3056 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); | |
3057 | else | |
3058 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); | |
123df294 AV |
3059 | if (!error) |
3060 | fsnotify_move(old_dir, new_dir, old_name, is_dir, | |
5a190ae6 | 3061 | new_dentry->d_inode, old_dentry); |
0eeca283 RL |
3062 | fsnotify_oldname_free(old_name); |
3063 | ||
1da177e4 LT |
3064 | return error; |
3065 | } | |
3066 | ||
2e4d0924 HC |
3067 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
3068 | int, newdfd, const char __user *, newname) | |
1da177e4 | 3069 | { |
2ad94ae6 AV |
3070 | struct dentry *old_dir, *new_dir; |
3071 | struct dentry *old_dentry, *new_dentry; | |
3072 | struct dentry *trap; | |
1da177e4 | 3073 | struct nameidata oldnd, newnd; |
2ad94ae6 AV |
3074 | char *from; |
3075 | char *to; | |
3076 | int error; | |
1da177e4 | 3077 | |
2ad94ae6 | 3078 | error = user_path_parent(olddfd, oldname, &oldnd, &from); |
1da177e4 LT |
3079 | if (error) |
3080 | goto exit; | |
3081 | ||
2ad94ae6 | 3082 | error = user_path_parent(newdfd, newname, &newnd, &to); |
1da177e4 LT |
3083 | if (error) |
3084 | goto exit1; | |
3085 | ||
3086 | error = -EXDEV; | |
4ac91378 | 3087 | if (oldnd.path.mnt != newnd.path.mnt) |
1da177e4 LT |
3088 | goto exit2; |
3089 | ||
4ac91378 | 3090 | old_dir = oldnd.path.dentry; |
1da177e4 LT |
3091 | error = -EBUSY; |
3092 | if (oldnd.last_type != LAST_NORM) | |
3093 | goto exit2; | |
3094 | ||
4ac91378 | 3095 | new_dir = newnd.path.dentry; |
1da177e4 LT |
3096 | if (newnd.last_type != LAST_NORM) |
3097 | goto exit2; | |
3098 | ||
0612d9fb OH |
3099 | oldnd.flags &= ~LOOKUP_PARENT; |
3100 | newnd.flags &= ~LOOKUP_PARENT; | |
4e9ed2f8 | 3101 | newnd.flags |= LOOKUP_RENAME_TARGET; |
0612d9fb | 3102 | |
1da177e4 LT |
3103 | trap = lock_rename(new_dir, old_dir); |
3104 | ||
49705b77 | 3105 | old_dentry = lookup_hash(&oldnd); |
1da177e4 LT |
3106 | error = PTR_ERR(old_dentry); |
3107 | if (IS_ERR(old_dentry)) | |
3108 | goto exit3; | |
3109 | /* source must exist */ | |
3110 | error = -ENOENT; | |
3111 | if (!old_dentry->d_inode) | |
3112 | goto exit4; | |
3113 | /* unless the source is a directory trailing slashes give -ENOTDIR */ | |
3114 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { | |
3115 | error = -ENOTDIR; | |
3116 | if (oldnd.last.name[oldnd.last.len]) | |
3117 | goto exit4; | |
3118 | if (newnd.last.name[newnd.last.len]) | |
3119 | goto exit4; | |
3120 | } | |
3121 | /* source should not be ancestor of target */ | |
3122 | error = -EINVAL; | |
3123 | if (old_dentry == trap) | |
3124 | goto exit4; | |
49705b77 | 3125 | new_dentry = lookup_hash(&newnd); |
1da177e4 LT |
3126 | error = PTR_ERR(new_dentry); |
3127 | if (IS_ERR(new_dentry)) | |
3128 | goto exit4; | |
3129 | /* target should not be an ancestor of source */ | |
3130 | error = -ENOTEMPTY; | |
3131 | if (new_dentry == trap) | |
3132 | goto exit5; | |
3133 | ||
9079b1eb DH |
3134 | error = mnt_want_write(oldnd.path.mnt); |
3135 | if (error) | |
3136 | goto exit5; | |
be6d3e56 KT |
3137 | error = security_path_rename(&oldnd.path, old_dentry, |
3138 | &newnd.path, new_dentry); | |
3139 | if (error) | |
3140 | goto exit6; | |
1da177e4 LT |
3141 | error = vfs_rename(old_dir->d_inode, old_dentry, |
3142 | new_dir->d_inode, new_dentry); | |
be6d3e56 | 3143 | exit6: |
9079b1eb | 3144 | mnt_drop_write(oldnd.path.mnt); |
1da177e4 LT |
3145 | exit5: |
3146 | dput(new_dentry); | |
3147 | exit4: | |
3148 | dput(old_dentry); | |
3149 | exit3: | |
3150 | unlock_rename(new_dir, old_dir); | |
3151 | exit2: | |
1d957f9b | 3152 | path_put(&newnd.path); |
2ad94ae6 | 3153 | putname(to); |
1da177e4 | 3154 | exit1: |
1d957f9b | 3155 | path_put(&oldnd.path); |
1da177e4 | 3156 | putname(from); |
2ad94ae6 | 3157 | exit: |
1da177e4 LT |
3158 | return error; |
3159 | } | |
3160 | ||
a26eab24 | 3161 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
3162 | { |
3163 | return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); | |
3164 | } | |
3165 | ||
1da177e4 LT |
3166 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
3167 | { | |
3168 | int len; | |
3169 | ||
3170 | len = PTR_ERR(link); | |
3171 | if (IS_ERR(link)) | |
3172 | goto out; | |
3173 | ||
3174 | len = strlen(link); | |
3175 | if (len > (unsigned) buflen) | |
3176 | len = buflen; | |
3177 | if (copy_to_user(buffer, link, len)) | |
3178 | len = -EFAULT; | |
3179 | out: | |
3180 | return len; | |
3181 | } | |
3182 | ||
3183 | /* | |
3184 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
3185 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
3186 | * using) it for any given inode is up to filesystem. | |
3187 | */ | |
3188 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
3189 | { | |
3190 | struct nameidata nd; | |
cc314eef | 3191 | void *cookie; |
694a1764 | 3192 | int res; |
cc314eef | 3193 | |
1da177e4 | 3194 | nd.depth = 0; |
cc314eef | 3195 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
694a1764 MS |
3196 | if (IS_ERR(cookie)) |
3197 | return PTR_ERR(cookie); | |
3198 | ||
3199 | res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); | |
3200 | if (dentry->d_inode->i_op->put_link) | |
3201 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); | |
3202 | return res; | |
1da177e4 LT |
3203 | } |
3204 | ||
3205 | int vfs_follow_link(struct nameidata *nd, const char *link) | |
3206 | { | |
3207 | return __vfs_follow_link(nd, link); | |
3208 | } | |
3209 | ||
3210 | /* get the link contents into pagecache */ | |
3211 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
3212 | { | |
ebd09abb DG |
3213 | char *kaddr; |
3214 | struct page *page; | |
1da177e4 | 3215 | struct address_space *mapping = dentry->d_inode->i_mapping; |
090d2b18 | 3216 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 3217 | if (IS_ERR(page)) |
6fe6900e | 3218 | return (char*)page; |
1da177e4 | 3219 | *ppage = page; |
ebd09abb DG |
3220 | kaddr = kmap(page); |
3221 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); | |
3222 | return kaddr; | |
1da177e4 LT |
3223 | } |
3224 | ||
3225 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
3226 | { | |
3227 | struct page *page = NULL; | |
3228 | char *s = page_getlink(dentry, &page); | |
3229 | int res = vfs_readlink(dentry,buffer,buflen,s); | |
3230 | if (page) { | |
3231 | kunmap(page); | |
3232 | page_cache_release(page); | |
3233 | } | |
3234 | return res; | |
3235 | } | |
3236 | ||
cc314eef | 3237 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 3238 | { |
cc314eef | 3239 | struct page *page = NULL; |
1da177e4 | 3240 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 3241 | return page; |
1da177e4 LT |
3242 | } |
3243 | ||
cc314eef | 3244 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 3245 | { |
cc314eef LT |
3246 | struct page *page = cookie; |
3247 | ||
3248 | if (page) { | |
1da177e4 LT |
3249 | kunmap(page); |
3250 | page_cache_release(page); | |
1da177e4 LT |
3251 | } |
3252 | } | |
3253 | ||
54566b2c NP |
3254 | /* |
3255 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
3256 | */ | |
3257 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
3258 | { |
3259 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 3260 | struct page *page; |
afddba49 | 3261 | void *fsdata; |
beb497ab | 3262 | int err; |
1da177e4 | 3263 | char *kaddr; |
54566b2c NP |
3264 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
3265 | if (nofs) | |
3266 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 3267 | |
7e53cac4 | 3268 | retry: |
afddba49 | 3269 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 3270 | flags, &page, &fsdata); |
1da177e4 | 3271 | if (err) |
afddba49 NP |
3272 | goto fail; |
3273 | ||
1da177e4 LT |
3274 | kaddr = kmap_atomic(page, KM_USER0); |
3275 | memcpy(kaddr, symname, len-1); | |
3276 | kunmap_atomic(kaddr, KM_USER0); | |
afddba49 NP |
3277 | |
3278 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
3279 | page, fsdata); | |
1da177e4 LT |
3280 | if (err < 0) |
3281 | goto fail; | |
afddba49 NP |
3282 | if (err < len-1) |
3283 | goto retry; | |
3284 | ||
1da177e4 LT |
3285 | mark_inode_dirty(inode); |
3286 | return 0; | |
1da177e4 LT |
3287 | fail: |
3288 | return err; | |
3289 | } | |
3290 | ||
0adb25d2 KK |
3291 | int page_symlink(struct inode *inode, const char *symname, int len) |
3292 | { | |
3293 | return __page_symlink(inode, symname, len, | |
54566b2c | 3294 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
0adb25d2 KK |
3295 | } |
3296 | ||
92e1d5be | 3297 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
3298 | .readlink = generic_readlink, |
3299 | .follow_link = page_follow_link_light, | |
3300 | .put_link = page_put_link, | |
3301 | }; | |
3302 | ||
2d8f3038 | 3303 | EXPORT_SYMBOL(user_path_at); |
cc53ce53 | 3304 | EXPORT_SYMBOL(follow_down_one); |
1da177e4 LT |
3305 | EXPORT_SYMBOL(follow_down); |
3306 | EXPORT_SYMBOL(follow_up); | |
3307 | EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ | |
3308 | EXPORT_SYMBOL(getname); | |
3309 | EXPORT_SYMBOL(lock_rename); | |
1da177e4 LT |
3310 | EXPORT_SYMBOL(lookup_one_len); |
3311 | EXPORT_SYMBOL(page_follow_link_light); | |
3312 | EXPORT_SYMBOL(page_put_link); | |
3313 | EXPORT_SYMBOL(page_readlink); | |
0adb25d2 | 3314 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 LT |
3315 | EXPORT_SYMBOL(page_symlink); |
3316 | EXPORT_SYMBOL(page_symlink_inode_operations); | |
d1811465 | 3317 | EXPORT_SYMBOL(kern_path); |
16f18200 | 3318 | EXPORT_SYMBOL(vfs_path_lookup); |
f419a2e3 | 3319 | EXPORT_SYMBOL(inode_permission); |
1da177e4 LT |
3320 | EXPORT_SYMBOL(unlock_rename); |
3321 | EXPORT_SYMBOL(vfs_create); | |
3322 | EXPORT_SYMBOL(vfs_follow_link); | |
3323 | EXPORT_SYMBOL(vfs_link); | |
3324 | EXPORT_SYMBOL(vfs_mkdir); | |
3325 | EXPORT_SYMBOL(vfs_mknod); | |
3326 | EXPORT_SYMBOL(generic_permission); | |
3327 | EXPORT_SYMBOL(vfs_readlink); | |
3328 | EXPORT_SYMBOL(vfs_rename); | |
3329 | EXPORT_SYMBOL(vfs_rmdir); | |
3330 | EXPORT_SYMBOL(vfs_symlink); | |
3331 | EXPORT_SYMBOL(vfs_unlink); | |
3332 | EXPORT_SYMBOL(dentry_unhash); | |
3333 | EXPORT_SYMBOL(generic_readlink); |