Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/fs/namei.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * Some corrections by tytso. | |
9 | */ | |
10 | ||
11 | /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname | |
12 | * lookup logic. | |
13 | */ | |
14 | /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. | |
15 | */ | |
16 | ||
17 | #include <linux/init.h> | |
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 | { | |
84635d68 | 179 | #ifdef CONFIG_FS_POSIX_ACL |
e77819e5 LT |
180 | struct posix_acl *acl; |
181 | ||
e77819e5 | 182 | if (mask & MAY_NOT_BLOCK) { |
3567866b AV |
183 | acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); |
184 | if (!acl) | |
e77819e5 | 185 | return -EAGAIN; |
3567866b AV |
186 | /* no ->get_acl() calls in RCU mode... */ |
187 | if (acl == ACL_NOT_CACHED) | |
188 | return -ECHILD; | |
206b1d09 | 189 | return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); |
e77819e5 LT |
190 | } |
191 | ||
192 | acl = get_cached_acl(inode, ACL_TYPE_ACCESS); | |
193 | ||
194 | /* | |
4e34e719 CH |
195 | * A filesystem can force a ACL callback by just never filling the |
196 | * ACL cache. But normally you'd fill the cache either at inode | |
197 | * instantiation time, or on the first ->get_acl call. | |
e77819e5 | 198 | * |
4e34e719 CH |
199 | * If the filesystem doesn't have a get_acl() function at all, we'll |
200 | * just create the negative cache entry. | |
e77819e5 LT |
201 | */ |
202 | if (acl == ACL_NOT_CACHED) { | |
4e34e719 CH |
203 | if (inode->i_op->get_acl) { |
204 | acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS); | |
205 | if (IS_ERR(acl)) | |
206 | return PTR_ERR(acl); | |
207 | } else { | |
208 | set_cached_acl(inode, ACL_TYPE_ACCESS, NULL); | |
209 | return -EAGAIN; | |
210 | } | |
e77819e5 LT |
211 | } |
212 | ||
213 | if (acl) { | |
214 | int error = posix_acl_permission(inode, acl, mask); | |
215 | posix_acl_release(acl); | |
216 | return error; | |
217 | } | |
84635d68 | 218 | #endif |
e77819e5 LT |
219 | |
220 | return -EAGAIN; | |
221 | } | |
222 | ||
5909ccaa | 223 | /* |
948409c7 | 224 | * This does the basic permission checking |
1da177e4 | 225 | */ |
7e40145e | 226 | static int acl_permission_check(struct inode *inode, int mask) |
1da177e4 | 227 | { |
26cf46be | 228 | unsigned int mode = inode->i_mode; |
1da177e4 | 229 | |
e795b717 SH |
230 | if (current_user_ns() != inode_userns(inode)) |
231 | goto other_perms; | |
232 | ||
14067ff5 | 233 | if (likely(current_fsuid() == inode->i_uid)) |
1da177e4 LT |
234 | mode >>= 6; |
235 | else { | |
e77819e5 | 236 | if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { |
7e40145e | 237 | int error = check_acl(inode, mask); |
b74c79e9 NP |
238 | if (error != -EAGAIN) |
239 | return error; | |
1da177e4 LT |
240 | } |
241 | ||
242 | if (in_group_p(inode->i_gid)) | |
243 | mode >>= 3; | |
244 | } | |
245 | ||
e795b717 | 246 | other_perms: |
1da177e4 LT |
247 | /* |
248 | * If the DACs are ok we don't need any capability check. | |
249 | */ | |
9c2c7039 | 250 | if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) |
1da177e4 | 251 | return 0; |
5909ccaa LT |
252 | return -EACCES; |
253 | } | |
254 | ||
255 | /** | |
b74c79e9 | 256 | * generic_permission - check for access rights on a Posix-like filesystem |
5909ccaa | 257 | * @inode: inode to check access rights for |
8fd90c8d | 258 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) |
5909ccaa LT |
259 | * |
260 | * Used to check for read/write/execute permissions on a file. | |
261 | * We use "fsuid" for this, letting us set arbitrary permissions | |
262 | * for filesystem access without changing the "normal" uids which | |
b74c79e9 NP |
263 | * are used for other things. |
264 | * | |
265 | * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk | |
266 | * request cannot be satisfied (eg. requires blocking or too much complexity). | |
267 | * It would then be called again in ref-walk mode. | |
5909ccaa | 268 | */ |
2830ba7f | 269 | int generic_permission(struct inode *inode, int mask) |
5909ccaa LT |
270 | { |
271 | int ret; | |
272 | ||
273 | /* | |
948409c7 | 274 | * Do the basic permission checks. |
5909ccaa | 275 | */ |
7e40145e | 276 | ret = acl_permission_check(inode, mask); |
5909ccaa LT |
277 | if (ret != -EACCES) |
278 | return ret; | |
1da177e4 | 279 | |
d594e7ec AV |
280 | if (S_ISDIR(inode->i_mode)) { |
281 | /* DACs are overridable for directories */ | |
282 | if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) | |
283 | return 0; | |
284 | if (!(mask & MAY_WRITE)) | |
285 | if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) | |
286 | return 0; | |
287 | return -EACCES; | |
288 | } | |
1da177e4 LT |
289 | /* |
290 | * Read/write DACs are always overridable. | |
d594e7ec AV |
291 | * Executable DACs are overridable when there is |
292 | * at least one exec bit set. | |
1da177e4 | 293 | */ |
d594e7ec | 294 | if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) |
e795b717 | 295 | if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) |
1da177e4 LT |
296 | return 0; |
297 | ||
298 | /* | |
299 | * Searching includes executable on directories, else just read. | |
300 | */ | |
7ea66001 | 301 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
d594e7ec | 302 | if (mask == MAY_READ) |
e795b717 | 303 | if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) |
1da177e4 LT |
304 | return 0; |
305 | ||
306 | return -EACCES; | |
307 | } | |
308 | ||
3ddcd056 LT |
309 | /* |
310 | * We _really_ want to just do "generic_permission()" without | |
311 | * even looking at the inode->i_op values. So we keep a cache | |
312 | * flag in inode->i_opflags, that says "this has not special | |
313 | * permission function, use the fast case". | |
314 | */ | |
315 | static inline int do_inode_permission(struct inode *inode, int mask) | |
316 | { | |
317 | if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { | |
318 | if (likely(inode->i_op->permission)) | |
319 | return inode->i_op->permission(inode, mask); | |
320 | ||
321 | /* This gets set once for the inode lifetime */ | |
322 | spin_lock(&inode->i_lock); | |
323 | inode->i_opflags |= IOP_FASTPERM; | |
324 | spin_unlock(&inode->i_lock); | |
325 | } | |
326 | return generic_permission(inode, mask); | |
327 | } | |
328 | ||
cb23beb5 CH |
329 | /** |
330 | * inode_permission - check for access rights to a given inode | |
331 | * @inode: inode to check permission on | |
8fd90c8d | 332 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) |
cb23beb5 CH |
333 | * |
334 | * Used to check for read/write/execute permissions on an inode. | |
335 | * We use "fsuid" for this, letting us set arbitrary permissions | |
336 | * for filesystem access without changing the "normal" uids which | |
337 | * are used for other things. | |
948409c7 AG |
338 | * |
339 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
cb23beb5 | 340 | */ |
f419a2e3 | 341 | int inode_permission(struct inode *inode, int mask) |
1da177e4 | 342 | { |
e6305c43 | 343 | int retval; |
1da177e4 | 344 | |
3ddcd056 | 345 | if (unlikely(mask & MAY_WRITE)) { |
22590e41 | 346 | umode_t mode = inode->i_mode; |
1da177e4 LT |
347 | |
348 | /* | |
349 | * Nobody gets write access to a read-only fs. | |
350 | */ | |
351 | if (IS_RDONLY(inode) && | |
352 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
353 | return -EROFS; | |
354 | ||
355 | /* | |
356 | * Nobody gets write access to an immutable file. | |
357 | */ | |
358 | if (IS_IMMUTABLE(inode)) | |
359 | return -EACCES; | |
360 | } | |
361 | ||
3ddcd056 | 362 | retval = do_inode_permission(inode, mask); |
1da177e4 LT |
363 | if (retval) |
364 | return retval; | |
365 | ||
08ce5f16 SH |
366 | retval = devcgroup_inode_permission(inode, mask); |
367 | if (retval) | |
368 | return retval; | |
369 | ||
d09ca739 | 370 | return security_inode_permission(inode, mask); |
1da177e4 LT |
371 | } |
372 | ||
5dd784d0 JB |
373 | /** |
374 | * path_get - get a reference to a path | |
375 | * @path: path to get the reference to | |
376 | * | |
377 | * Given a path increment the reference count to the dentry and the vfsmount. | |
378 | */ | |
379 | void path_get(struct path *path) | |
380 | { | |
381 | mntget(path->mnt); | |
382 | dget(path->dentry); | |
383 | } | |
384 | EXPORT_SYMBOL(path_get); | |
385 | ||
1d957f9b JB |
386 | /** |
387 | * path_put - put a reference to a path | |
388 | * @path: path to put the reference to | |
389 | * | |
390 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
391 | */ | |
392 | void path_put(struct path *path) | |
1da177e4 | 393 | { |
1d957f9b JB |
394 | dput(path->dentry); |
395 | mntput(path->mnt); | |
1da177e4 | 396 | } |
1d957f9b | 397 | EXPORT_SYMBOL(path_put); |
1da177e4 | 398 | |
19660af7 | 399 | /* |
31e6b01f | 400 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
19660af7 AV |
401 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
402 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab | |
403 | * normal reference counts on dentries and vfsmounts to transition to rcu-walk | |
404 | * mode. Refcounts are grabbed at the last known good point before rcu-walk | |
405 | * got stuck, so ref-walk may continue from there. If this is not successful | |
406 | * (eg. a seqcount has changed), then failure is returned and it's up to caller | |
407 | * to restart the path walk from the beginning in ref-walk mode. | |
31e6b01f | 408 | */ |
31e6b01f NP |
409 | |
410 | /** | |
19660af7 AV |
411 | * unlazy_walk - try to switch to ref-walk mode. |
412 | * @nd: nameidata pathwalk data | |
413 | * @dentry: child of nd->path.dentry or NULL | |
39191628 | 414 | * Returns: 0 on success, -ECHILD on failure |
31e6b01f | 415 | * |
19660af7 AV |
416 | * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry |
417 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on | |
418 | * @nd or NULL. Must be called from rcu-walk context. | |
31e6b01f | 419 | */ |
19660af7 | 420 | static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) |
31e6b01f NP |
421 | { |
422 | struct fs_struct *fs = current->fs; | |
423 | struct dentry *parent = nd->path.dentry; | |
5b6ca027 | 424 | int want_root = 0; |
31e6b01f NP |
425 | |
426 | BUG_ON(!(nd->flags & LOOKUP_RCU)); | |
5b6ca027 AV |
427 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
428 | want_root = 1; | |
31e6b01f NP |
429 | spin_lock(&fs->lock); |
430 | if (nd->root.mnt != fs->root.mnt || | |
431 | nd->root.dentry != fs->root.dentry) | |
432 | goto err_root; | |
433 | } | |
434 | spin_lock(&parent->d_lock); | |
19660af7 AV |
435 | if (!dentry) { |
436 | if (!__d_rcu_to_refcount(parent, nd->seq)) | |
437 | goto err_parent; | |
438 | BUG_ON(nd->inode != parent->d_inode); | |
439 | } else { | |
94c0d4ec AV |
440 | if (dentry->d_parent != parent) |
441 | goto err_parent; | |
19660af7 AV |
442 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
443 | if (!__d_rcu_to_refcount(dentry, nd->seq)) | |
444 | goto err_child; | |
445 | /* | |
446 | * If the sequence check on the child dentry passed, then | |
447 | * the child has not been removed from its parent. This | |
448 | * means the parent dentry must be valid and able to take | |
449 | * a reference at this point. | |
450 | */ | |
451 | BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); | |
452 | BUG_ON(!parent->d_count); | |
453 | parent->d_count++; | |
454 | spin_unlock(&dentry->d_lock); | |
455 | } | |
31e6b01f | 456 | spin_unlock(&parent->d_lock); |
5b6ca027 | 457 | if (want_root) { |
31e6b01f NP |
458 | path_get(&nd->root); |
459 | spin_unlock(&fs->lock); | |
460 | } | |
461 | mntget(nd->path.mnt); | |
462 | ||
463 | rcu_read_unlock(); | |
464 | br_read_unlock(vfsmount_lock); | |
465 | nd->flags &= ~LOOKUP_RCU; | |
466 | return 0; | |
19660af7 AV |
467 | |
468 | err_child: | |
31e6b01f | 469 | spin_unlock(&dentry->d_lock); |
19660af7 | 470 | err_parent: |
31e6b01f NP |
471 | spin_unlock(&parent->d_lock); |
472 | err_root: | |
5b6ca027 | 473 | if (want_root) |
31e6b01f NP |
474 | spin_unlock(&fs->lock); |
475 | return -ECHILD; | |
476 | } | |
477 | ||
834f2a4a TM |
478 | /** |
479 | * release_open_intent - free up open intent resources | |
480 | * @nd: pointer to nameidata | |
481 | */ | |
482 | void release_open_intent(struct nameidata *nd) | |
483 | { | |
2dab5974 LT |
484 | struct file *file = nd->intent.open.file; |
485 | ||
486 | if (file && !IS_ERR(file)) { | |
487 | if (file->f_path.dentry == NULL) | |
488 | put_filp(file); | |
489 | else | |
490 | fput(file); | |
491 | } | |
834f2a4a TM |
492 | } |
493 | ||
f60aef7e | 494 | static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) |
34286d66 | 495 | { |
f60aef7e | 496 | return dentry->d_op->d_revalidate(dentry, nd); |
34286d66 NP |
497 | } |
498 | ||
9f1fafee AV |
499 | /** |
500 | * complete_walk - successful completion of path walk | |
501 | * @nd: pointer nameidata | |
39159de2 | 502 | * |
9f1fafee AV |
503 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
504 | * Revalidate the final result, unless we'd already done that during | |
505 | * the path walk or the filesystem doesn't ask for it. Return 0 on | |
506 | * success, -error on failure. In case of failure caller does not | |
507 | * need to drop nd->path. | |
39159de2 | 508 | */ |
9f1fafee | 509 | static int complete_walk(struct nameidata *nd) |
39159de2 | 510 | { |
16c2cd71 | 511 | struct dentry *dentry = nd->path.dentry; |
39159de2 | 512 | int status; |
39159de2 | 513 | |
9f1fafee AV |
514 | if (nd->flags & LOOKUP_RCU) { |
515 | nd->flags &= ~LOOKUP_RCU; | |
516 | if (!(nd->flags & LOOKUP_ROOT)) | |
517 | nd->root.mnt = NULL; | |
518 | spin_lock(&dentry->d_lock); | |
519 | if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { | |
520 | spin_unlock(&dentry->d_lock); | |
521 | rcu_read_unlock(); | |
522 | br_read_unlock(vfsmount_lock); | |
523 | return -ECHILD; | |
524 | } | |
525 | BUG_ON(nd->inode != dentry->d_inode); | |
526 | spin_unlock(&dentry->d_lock); | |
527 | mntget(nd->path.mnt); | |
528 | rcu_read_unlock(); | |
529 | br_read_unlock(vfsmount_lock); | |
530 | } | |
531 | ||
16c2cd71 AV |
532 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
533 | return 0; | |
534 | ||
535 | if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) | |
39159de2 JL |
536 | return 0; |
537 | ||
16c2cd71 AV |
538 | if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) |
539 | return 0; | |
540 | ||
541 | /* Note: we do not d_invalidate() */ | |
34286d66 | 542 | status = d_revalidate(dentry, nd); |
39159de2 JL |
543 | if (status > 0) |
544 | return 0; | |
545 | ||
16c2cd71 | 546 | if (!status) |
39159de2 | 547 | status = -ESTALE; |
16c2cd71 | 548 | |
9f1fafee | 549 | path_put(&nd->path); |
39159de2 JL |
550 | return status; |
551 | } | |
552 | ||
2a737871 AV |
553 | static __always_inline void set_root(struct nameidata *nd) |
554 | { | |
f7ad3c6b MS |
555 | if (!nd->root.mnt) |
556 | get_fs_root(current->fs, &nd->root); | |
2a737871 AV |
557 | } |
558 | ||
6de88d72 AV |
559 | static int link_path_walk(const char *, struct nameidata *); |
560 | ||
31e6b01f NP |
561 | static __always_inline void set_root_rcu(struct nameidata *nd) |
562 | { | |
563 | if (!nd->root.mnt) { | |
564 | struct fs_struct *fs = current->fs; | |
c28cc364 NP |
565 | unsigned seq; |
566 | ||
567 | do { | |
568 | seq = read_seqcount_begin(&fs->seq); | |
569 | nd->root = fs->root; | |
c1530019 | 570 | nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); |
c28cc364 | 571 | } while (read_seqcount_retry(&fs->seq, seq)); |
31e6b01f NP |
572 | } |
573 | } | |
574 | ||
f1662356 | 575 | static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
1da177e4 | 576 | { |
31e6b01f NP |
577 | int ret; |
578 | ||
1da177e4 LT |
579 | if (IS_ERR(link)) |
580 | goto fail; | |
581 | ||
582 | if (*link == '/') { | |
2a737871 | 583 | set_root(nd); |
1d957f9b | 584 | path_put(&nd->path); |
2a737871 AV |
585 | nd->path = nd->root; |
586 | path_get(&nd->root); | |
16c2cd71 | 587 | nd->flags |= LOOKUP_JUMPED; |
1da177e4 | 588 | } |
31e6b01f | 589 | nd->inode = nd->path.dentry->d_inode; |
b4091d5f | 590 | |
31e6b01f NP |
591 | ret = link_path_walk(link, nd); |
592 | return ret; | |
1da177e4 | 593 | fail: |
1d957f9b | 594 | path_put(&nd->path); |
1da177e4 LT |
595 | return PTR_ERR(link); |
596 | } | |
597 | ||
1d957f9b | 598 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
599 | { |
600 | dput(path->dentry); | |
4ac91378 | 601 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
602 | mntput(path->mnt); |
603 | } | |
604 | ||
7b9337aa NP |
605 | static inline void path_to_nameidata(const struct path *path, |
606 | struct nameidata *nd) | |
051d3812 | 607 | { |
31e6b01f NP |
608 | if (!(nd->flags & LOOKUP_RCU)) { |
609 | dput(nd->path.dentry); | |
610 | if (nd->path.mnt != path->mnt) | |
611 | mntput(nd->path.mnt); | |
9a229683 | 612 | } |
31e6b01f | 613 | nd->path.mnt = path->mnt; |
4ac91378 | 614 | nd->path.dentry = path->dentry; |
051d3812 IK |
615 | } |
616 | ||
574197e0 AV |
617 | static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) |
618 | { | |
619 | struct inode *inode = link->dentry->d_inode; | |
620 | if (!IS_ERR(cookie) && inode->i_op->put_link) | |
621 | inode->i_op->put_link(link->dentry, nd, cookie); | |
622 | path_put(link); | |
623 | } | |
624 | ||
def4af30 | 625 | static __always_inline int |
574197e0 | 626 | follow_link(struct path *link, struct nameidata *nd, void **p) |
1da177e4 LT |
627 | { |
628 | int error; | |
7b9337aa | 629 | struct dentry *dentry = link->dentry; |
1da177e4 | 630 | |
844a3917 AV |
631 | BUG_ON(nd->flags & LOOKUP_RCU); |
632 | ||
0e794589 AV |
633 | if (link->mnt == nd->path.mnt) |
634 | mntget(link->mnt); | |
635 | ||
574197e0 AV |
636 | if (unlikely(current->total_link_count >= 40)) { |
637 | *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ | |
574197e0 AV |
638 | path_put(&nd->path); |
639 | return -ELOOP; | |
640 | } | |
641 | cond_resched(); | |
642 | current->total_link_count++; | |
643 | ||
7b9337aa | 644 | touch_atime(link->mnt, dentry); |
1da177e4 | 645 | nd_set_link(nd, NULL); |
cd4e91d3 | 646 | |
36f3b4f6 AV |
647 | error = security_inode_follow_link(link->dentry, nd); |
648 | if (error) { | |
649 | *p = ERR_PTR(error); /* no ->put_link(), please */ | |
650 | path_put(&nd->path); | |
651 | return error; | |
652 | } | |
653 | ||
86acdca1 | 654 | nd->last_type = LAST_BIND; |
def4af30 AV |
655 | *p = dentry->d_inode->i_op->follow_link(dentry, nd); |
656 | error = PTR_ERR(*p); | |
657 | if (!IS_ERR(*p)) { | |
1da177e4 | 658 | char *s = nd_get_link(nd); |
cc314eef | 659 | error = 0; |
1da177e4 LT |
660 | if (s) |
661 | error = __vfs_follow_link(nd, s); | |
bcda7652 | 662 | else if (nd->last_type == LAST_BIND) { |
16c2cd71 | 663 | nd->flags |= LOOKUP_JUMPED; |
b21041d0 AV |
664 | nd->inode = nd->path.dentry->d_inode; |
665 | if (nd->inode->i_op->follow_link) { | |
bcda7652 AV |
666 | /* stepped on a _really_ weird one */ |
667 | path_put(&nd->path); | |
668 | error = -ELOOP; | |
669 | } | |
670 | } | |
1da177e4 | 671 | } |
1da177e4 LT |
672 | return error; |
673 | } | |
674 | ||
31e6b01f NP |
675 | static int follow_up_rcu(struct path *path) |
676 | { | |
677 | struct vfsmount *parent; | |
678 | struct dentry *mountpoint; | |
679 | ||
680 | parent = path->mnt->mnt_parent; | |
681 | if (parent == path->mnt) | |
682 | return 0; | |
683 | mountpoint = path->mnt->mnt_mountpoint; | |
684 | path->dentry = mountpoint; | |
685 | path->mnt = parent; | |
686 | return 1; | |
687 | } | |
688 | ||
bab77ebf | 689 | int follow_up(struct path *path) |
1da177e4 LT |
690 | { |
691 | struct vfsmount *parent; | |
692 | struct dentry *mountpoint; | |
99b7db7b NP |
693 | |
694 | br_read_lock(vfsmount_lock); | |
bab77ebf AV |
695 | parent = path->mnt->mnt_parent; |
696 | if (parent == path->mnt) { | |
99b7db7b | 697 | br_read_unlock(vfsmount_lock); |
1da177e4 LT |
698 | return 0; |
699 | } | |
700 | mntget(parent); | |
bab77ebf | 701 | mountpoint = dget(path->mnt->mnt_mountpoint); |
99b7db7b | 702 | br_read_unlock(vfsmount_lock); |
bab77ebf AV |
703 | dput(path->dentry); |
704 | path->dentry = mountpoint; | |
705 | mntput(path->mnt); | |
706 | path->mnt = parent; | |
1da177e4 LT |
707 | return 1; |
708 | } | |
709 | ||
b5c84bf6 | 710 | /* |
9875cf80 DH |
711 | * Perform an automount |
712 | * - return -EISDIR to tell follow_managed() to stop and return the path we | |
713 | * were called with. | |
1da177e4 | 714 | */ |
9875cf80 DH |
715 | static int follow_automount(struct path *path, unsigned flags, |
716 | bool *need_mntput) | |
31e6b01f | 717 | { |
9875cf80 | 718 | struct vfsmount *mnt; |
ea5b778a | 719 | int err; |
9875cf80 DH |
720 | |
721 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) | |
722 | return -EREMOTE; | |
723 | ||
0ec26fd0 MS |
724 | /* We don't want to mount if someone's just doing a stat - |
725 | * unless they're stat'ing a directory and appended a '/' to | |
726 | * the name. | |
727 | * | |
728 | * We do, however, want to mount if someone wants to open or | |
729 | * create a file of any type under the mountpoint, wants to | |
730 | * traverse through the mountpoint or wants to open the | |
731 | * mounted directory. Also, autofs may mark negative dentries | |
732 | * as being automount points. These will need the attentions | |
733 | * of the daemon to instantiate them before they can be used. | |
9875cf80 | 734 | */ |
0ec26fd0 | 735 | if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
d94c177b | 736 | LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && |
0ec26fd0 MS |
737 | path->dentry->d_inode) |
738 | return -EISDIR; | |
739 | ||
9875cf80 DH |
740 | current->total_link_count++; |
741 | if (current->total_link_count >= 40) | |
742 | return -ELOOP; | |
743 | ||
744 | mnt = path->dentry->d_op->d_automount(path); | |
745 | if (IS_ERR(mnt)) { | |
746 | /* | |
747 | * The filesystem is allowed to return -EISDIR here to indicate | |
748 | * it doesn't want to automount. For instance, autofs would do | |
749 | * this so that its userspace daemon can mount on this dentry. | |
750 | * | |
751 | * However, we can only permit this if it's a terminal point in | |
752 | * the path being looked up; if it wasn't then the remainder of | |
753 | * the path is inaccessible and we should say so. | |
754 | */ | |
49084c3b | 755 | if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) |
9875cf80 DH |
756 | return -EREMOTE; |
757 | return PTR_ERR(mnt); | |
31e6b01f | 758 | } |
ea5b778a | 759 | |
9875cf80 DH |
760 | if (!mnt) /* mount collision */ |
761 | return 0; | |
31e6b01f | 762 | |
8aef1884 AV |
763 | if (!*need_mntput) { |
764 | /* lock_mount() may release path->mnt on error */ | |
765 | mntget(path->mnt); | |
766 | *need_mntput = true; | |
767 | } | |
19a167af | 768 | err = finish_automount(mnt, path); |
9875cf80 | 769 | |
ea5b778a DH |
770 | switch (err) { |
771 | case -EBUSY: | |
772 | /* Someone else made a mount here whilst we were busy */ | |
19a167af | 773 | return 0; |
ea5b778a | 774 | case 0: |
8aef1884 | 775 | path_put(path); |
ea5b778a DH |
776 | path->mnt = mnt; |
777 | path->dentry = dget(mnt->mnt_root); | |
ea5b778a | 778 | return 0; |
19a167af AV |
779 | default: |
780 | return err; | |
ea5b778a | 781 | } |
19a167af | 782 | |
463ffb2e AV |
783 | } |
784 | ||
9875cf80 DH |
785 | /* |
786 | * Handle a dentry that is managed in some way. | |
cc53ce53 | 787 | * - Flagged for transit management (autofs) |
9875cf80 DH |
788 | * - Flagged as mountpoint |
789 | * - Flagged as automount point | |
790 | * | |
791 | * This may only be called in refwalk mode. | |
792 | * | |
793 | * Serialization is taken care of in namespace.c | |
794 | */ | |
795 | static int follow_managed(struct path *path, unsigned flags) | |
1da177e4 | 796 | { |
8aef1884 | 797 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
9875cf80 DH |
798 | unsigned managed; |
799 | bool need_mntput = false; | |
8aef1884 | 800 | int ret = 0; |
9875cf80 DH |
801 | |
802 | /* Given that we're not holding a lock here, we retain the value in a | |
803 | * local variable for each dentry as we look at it so that we don't see | |
804 | * the components of that value change under us */ | |
805 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
806 | managed &= DCACHE_MANAGED_DENTRY, | |
807 | unlikely(managed != 0)) { | |
cc53ce53 DH |
808 | /* Allow the filesystem to manage the transit without i_mutex |
809 | * being held. */ | |
810 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
811 | BUG_ON(!path->dentry->d_op); | |
812 | BUG_ON(!path->dentry->d_op->d_manage); | |
1aed3e42 | 813 | ret = path->dentry->d_op->d_manage(path->dentry, false); |
cc53ce53 | 814 | if (ret < 0) |
8aef1884 | 815 | break; |
cc53ce53 DH |
816 | } |
817 | ||
9875cf80 DH |
818 | /* Transit to a mounted filesystem. */ |
819 | if (managed & DCACHE_MOUNTED) { | |
820 | struct vfsmount *mounted = lookup_mnt(path); | |
821 | if (mounted) { | |
822 | dput(path->dentry); | |
823 | if (need_mntput) | |
824 | mntput(path->mnt); | |
825 | path->mnt = mounted; | |
826 | path->dentry = dget(mounted->mnt_root); | |
827 | need_mntput = true; | |
828 | continue; | |
829 | } | |
830 | ||
831 | /* Something is mounted on this dentry in another | |
832 | * namespace and/or whatever was mounted there in this | |
833 | * namespace got unmounted before we managed to get the | |
834 | * vfsmount_lock */ | |
835 | } | |
836 | ||
837 | /* Handle an automount point */ | |
838 | if (managed & DCACHE_NEED_AUTOMOUNT) { | |
839 | ret = follow_automount(path, flags, &need_mntput); | |
840 | if (ret < 0) | |
8aef1884 | 841 | break; |
9875cf80 DH |
842 | continue; |
843 | } | |
844 | ||
845 | /* We didn't change the current path point */ | |
846 | break; | |
1da177e4 | 847 | } |
8aef1884 AV |
848 | |
849 | if (need_mntput && path->mnt == mnt) | |
850 | mntput(path->mnt); | |
851 | if (ret == -EISDIR) | |
852 | ret = 0; | |
853 | return ret; | |
1da177e4 LT |
854 | } |
855 | ||
cc53ce53 | 856 | int follow_down_one(struct path *path) |
1da177e4 LT |
857 | { |
858 | struct vfsmount *mounted; | |
859 | ||
1c755af4 | 860 | mounted = lookup_mnt(path); |
1da177e4 | 861 | if (mounted) { |
9393bd07 AV |
862 | dput(path->dentry); |
863 | mntput(path->mnt); | |
864 | path->mnt = mounted; | |
865 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
866 | return 1; |
867 | } | |
868 | return 0; | |
869 | } | |
870 | ||
62a7375e IK |
871 | static inline bool managed_dentry_might_block(struct dentry *dentry) |
872 | { | |
873 | return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && | |
874 | dentry->d_op->d_manage(dentry, true) < 0); | |
875 | } | |
876 | ||
9875cf80 | 877 | /* |
287548e4 AV |
878 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
879 | * we meet a managed dentry that would need blocking. | |
9875cf80 DH |
880 | */ |
881 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, | |
287548e4 | 882 | struct inode **inode) |
9875cf80 | 883 | { |
62a7375e | 884 | for (;;) { |
9875cf80 | 885 | struct vfsmount *mounted; |
62a7375e IK |
886 | /* |
887 | * Don't forget we might have a non-mountpoint managed dentry | |
888 | * that wants to block transit. | |
889 | */ | |
287548e4 | 890 | if (unlikely(managed_dentry_might_block(path->dentry))) |
ab90911f | 891 | return false; |
62a7375e IK |
892 | |
893 | if (!d_mountpoint(path->dentry)) | |
894 | break; | |
895 | ||
9875cf80 DH |
896 | mounted = __lookup_mnt(path->mnt, path->dentry, 1); |
897 | if (!mounted) | |
898 | break; | |
899 | path->mnt = mounted; | |
900 | path->dentry = mounted->mnt_root; | |
901 | nd->seq = read_seqcount_begin(&path->dentry->d_seq); | |
59430262 LT |
902 | /* |
903 | * Update the inode too. We don't need to re-check the | |
904 | * dentry sequence number here after this d_inode read, | |
905 | * because a mount-point is always pinned. | |
906 | */ | |
907 | *inode = path->dentry->d_inode; | |
9875cf80 | 908 | } |
9875cf80 DH |
909 | return true; |
910 | } | |
911 | ||
dea39376 | 912 | static void follow_mount_rcu(struct nameidata *nd) |
287548e4 | 913 | { |
dea39376 | 914 | while (d_mountpoint(nd->path.dentry)) { |
287548e4 | 915 | struct vfsmount *mounted; |
dea39376 | 916 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); |
287548e4 AV |
917 | if (!mounted) |
918 | break; | |
dea39376 AV |
919 | nd->path.mnt = mounted; |
920 | nd->path.dentry = mounted->mnt_root; | |
921 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
287548e4 AV |
922 | } |
923 | } | |
924 | ||
31e6b01f NP |
925 | static int follow_dotdot_rcu(struct nameidata *nd) |
926 | { | |
31e6b01f NP |
927 | set_root_rcu(nd); |
928 | ||
9875cf80 | 929 | while (1) { |
31e6b01f NP |
930 | if (nd->path.dentry == nd->root.dentry && |
931 | nd->path.mnt == nd->root.mnt) { | |
932 | break; | |
933 | } | |
934 | if (nd->path.dentry != nd->path.mnt->mnt_root) { | |
935 | struct dentry *old = nd->path.dentry; | |
936 | struct dentry *parent = old->d_parent; | |
937 | unsigned seq; | |
938 | ||
939 | seq = read_seqcount_begin(&parent->d_seq); | |
940 | if (read_seqcount_retry(&old->d_seq, nd->seq)) | |
ef7562d5 | 941 | goto failed; |
31e6b01f NP |
942 | nd->path.dentry = parent; |
943 | nd->seq = seq; | |
944 | break; | |
945 | } | |
946 | if (!follow_up_rcu(&nd->path)) | |
947 | break; | |
948 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
31e6b01f | 949 | } |
dea39376 AV |
950 | follow_mount_rcu(nd); |
951 | nd->inode = nd->path.dentry->d_inode; | |
31e6b01f | 952 | return 0; |
ef7562d5 AV |
953 | |
954 | failed: | |
955 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
956 | if (!(nd->flags & LOOKUP_ROOT)) |
957 | nd->root.mnt = NULL; | |
ef7562d5 AV |
958 | rcu_read_unlock(); |
959 | br_read_unlock(vfsmount_lock); | |
960 | return -ECHILD; | |
31e6b01f NP |
961 | } |
962 | ||
cc53ce53 DH |
963 | /* |
964 | * Follow down to the covering mount currently visible to userspace. At each | |
965 | * point, the filesystem owning that dentry may be queried as to whether the | |
966 | * caller is permitted to proceed or not. | |
cc53ce53 | 967 | */ |
7cc90cc3 | 968 | int follow_down(struct path *path) |
cc53ce53 DH |
969 | { |
970 | unsigned managed; | |
971 | int ret; | |
972 | ||
973 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
974 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { | |
975 | /* Allow the filesystem to manage the transit without i_mutex | |
976 | * being held. | |
977 | * | |
978 | * We indicate to the filesystem if someone is trying to mount | |
979 | * something here. This gives autofs the chance to deny anyone | |
980 | * other than its daemon the right to mount on its | |
981 | * superstructure. | |
982 | * | |
983 | * The filesystem may sleep at this point. | |
984 | */ | |
985 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
986 | BUG_ON(!path->dentry->d_op); | |
987 | BUG_ON(!path->dentry->d_op->d_manage); | |
ab90911f | 988 | ret = path->dentry->d_op->d_manage( |
1aed3e42 | 989 | path->dentry, false); |
cc53ce53 DH |
990 | if (ret < 0) |
991 | return ret == -EISDIR ? 0 : ret; | |
992 | } | |
993 | ||
994 | /* Transit to a mounted filesystem. */ | |
995 | if (managed & DCACHE_MOUNTED) { | |
996 | struct vfsmount *mounted = lookup_mnt(path); | |
997 | if (!mounted) | |
998 | break; | |
999 | dput(path->dentry); | |
1000 | mntput(path->mnt); | |
1001 | path->mnt = mounted; | |
1002 | path->dentry = dget(mounted->mnt_root); | |
1003 | continue; | |
1004 | } | |
1005 | ||
1006 | /* Don't handle automount points here */ | |
1007 | break; | |
1008 | } | |
1009 | return 0; | |
1010 | } | |
1011 | ||
9875cf80 DH |
1012 | /* |
1013 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() | |
1014 | */ | |
1015 | static void follow_mount(struct path *path) | |
1016 | { | |
1017 | while (d_mountpoint(path->dentry)) { | |
1018 | struct vfsmount *mounted = lookup_mnt(path); | |
1019 | if (!mounted) | |
1020 | break; | |
1021 | dput(path->dentry); | |
1022 | mntput(path->mnt); | |
1023 | path->mnt = mounted; | |
1024 | path->dentry = dget(mounted->mnt_root); | |
1025 | } | |
1026 | } | |
1027 | ||
31e6b01f | 1028 | static void follow_dotdot(struct nameidata *nd) |
1da177e4 | 1029 | { |
2a737871 | 1030 | set_root(nd); |
e518ddb7 | 1031 | |
1da177e4 | 1032 | while(1) { |
4ac91378 | 1033 | struct dentry *old = nd->path.dentry; |
1da177e4 | 1034 | |
2a737871 AV |
1035 | if (nd->path.dentry == nd->root.dentry && |
1036 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
1037 | break; |
1038 | } | |
4ac91378 | 1039 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
3088dd70 AV |
1040 | /* rare case of legitimate dget_parent()... */ |
1041 | nd->path.dentry = dget_parent(nd->path.dentry); | |
1da177e4 LT |
1042 | dput(old); |
1043 | break; | |
1044 | } | |
3088dd70 | 1045 | if (!follow_up(&nd->path)) |
1da177e4 | 1046 | break; |
1da177e4 | 1047 | } |
79ed0226 | 1048 | follow_mount(&nd->path); |
31e6b01f | 1049 | nd->inode = nd->path.dentry->d_inode; |
1da177e4 LT |
1050 | } |
1051 | ||
baa03890 NP |
1052 | /* |
1053 | * Allocate a dentry with name and parent, and perform a parent | |
1054 | * directory ->lookup on it. Returns the new dentry, or ERR_PTR | |
1055 | * on error. parent->d_inode->i_mutex must be held. d_lookup must | |
1056 | * have verified that no child exists while under i_mutex. | |
1057 | */ | |
1058 | static struct dentry *d_alloc_and_lookup(struct dentry *parent, | |
1059 | struct qstr *name, struct nameidata *nd) | |
1060 | { | |
1061 | struct inode *inode = parent->d_inode; | |
1062 | struct dentry *dentry; | |
1063 | struct dentry *old; | |
1064 | ||
1065 | /* Don't create child dentry for a dead directory. */ | |
1066 | if (unlikely(IS_DEADDIR(inode))) | |
1067 | return ERR_PTR(-ENOENT); | |
1068 | ||
1069 | dentry = d_alloc(parent, name); | |
1070 | if (unlikely(!dentry)) | |
1071 | return ERR_PTR(-ENOMEM); | |
1072 | ||
1073 | old = inode->i_op->lookup(inode, dentry, nd); | |
1074 | if (unlikely(old)) { | |
1075 | dput(dentry); | |
1076 | dentry = old; | |
1077 | } | |
1078 | return dentry; | |
1079 | } | |
1080 | ||
44396f4b JB |
1081 | /* |
1082 | * We already have a dentry, but require a lookup to be performed on the parent | |
1083 | * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error. | |
1084 | * parent->d_inode->i_mutex must be held. d_lookup must have verified that no | |
1085 | * child exists while under i_mutex. | |
1086 | */ | |
1087 | static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry, | |
1088 | struct nameidata *nd) | |
1089 | { | |
1090 | struct inode *inode = parent->d_inode; | |
1091 | struct dentry *old; | |
1092 | ||
1093 | /* Don't create child dentry for a dead directory. */ | |
1094 | if (unlikely(IS_DEADDIR(inode))) | |
1095 | return ERR_PTR(-ENOENT); | |
1096 | ||
1097 | old = inode->i_op->lookup(inode, dentry, nd); | |
1098 | if (unlikely(old)) { | |
1099 | dput(dentry); | |
1100 | dentry = old; | |
1101 | } | |
1102 | return dentry; | |
1103 | } | |
1104 | ||
1da177e4 LT |
1105 | /* |
1106 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
1107 | * small and for now I'd prefer to have fast path as straight as possible. | |
1108 | * It _is_ time-critical. | |
1109 | */ | |
1110 | static int do_lookup(struct nameidata *nd, struct qstr *name, | |
31e6b01f | 1111 | struct path *path, struct inode **inode) |
1da177e4 | 1112 | { |
4ac91378 | 1113 | struct vfsmount *mnt = nd->path.mnt; |
31e6b01f | 1114 | struct dentry *dentry, *parent = nd->path.dentry; |
5a18fff2 AV |
1115 | int need_reval = 1; |
1116 | int status = 1; | |
9875cf80 DH |
1117 | int err; |
1118 | ||
b04f784e NP |
1119 | /* |
1120 | * Rename seqlock is not required here because in the off chance | |
1121 | * of a false negative due to a concurrent rename, we're going to | |
1122 | * do the non-racy lookup, below. | |
1123 | */ | |
31e6b01f NP |
1124 | if (nd->flags & LOOKUP_RCU) { |
1125 | unsigned seq; | |
31e6b01f NP |
1126 | *inode = nd->inode; |
1127 | dentry = __d_lookup_rcu(parent, name, &seq, inode); | |
5a18fff2 AV |
1128 | if (!dentry) |
1129 | goto unlazy; | |
1130 | ||
31e6b01f NP |
1131 | /* Memory barrier in read_seqcount_begin of child is enough */ |
1132 | if (__read_seqcount_retry(&parent->d_seq, nd->seq)) | |
1133 | return -ECHILD; | |
31e6b01f | 1134 | nd->seq = seq; |
5a18fff2 | 1135 | |
24643087 | 1136 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
5a18fff2 AV |
1137 | status = d_revalidate(dentry, nd); |
1138 | if (unlikely(status <= 0)) { | |
1139 | if (status != -ECHILD) | |
1140 | need_reval = 0; | |
1141 | goto unlazy; | |
1142 | } | |
24643087 | 1143 | } |
44396f4b JB |
1144 | if (unlikely(d_need_lookup(dentry))) |
1145 | goto unlazy; | |
31e6b01f NP |
1146 | path->mnt = mnt; |
1147 | path->dentry = dentry; | |
d6e9bd25 AV |
1148 | if (unlikely(!__follow_mount_rcu(nd, path, inode))) |
1149 | goto unlazy; | |
1150 | if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) | |
1151 | goto unlazy; | |
1152 | return 0; | |
5a18fff2 | 1153 | unlazy: |
19660af7 AV |
1154 | if (unlazy_walk(nd, dentry)) |
1155 | return -ECHILD; | |
5a18fff2 AV |
1156 | } else { |
1157 | dentry = __d_lookup(parent, name); | |
9875cf80 | 1158 | } |
5a18fff2 | 1159 | |
44396f4b JB |
1160 | if (dentry && unlikely(d_need_lookup(dentry))) { |
1161 | dput(dentry); | |
1162 | dentry = NULL; | |
1163 | } | |
5a18fff2 AV |
1164 | retry: |
1165 | if (unlikely(!dentry)) { | |
1166 | struct inode *dir = parent->d_inode; | |
1167 | BUG_ON(nd->inode != dir); | |
1168 | ||
1169 | mutex_lock(&dir->i_mutex); | |
1170 | dentry = d_lookup(parent, name); | |
1171 | if (likely(!dentry)) { | |
1172 | dentry = d_alloc_and_lookup(parent, name, nd); | |
1173 | if (IS_ERR(dentry)) { | |
1174 | mutex_unlock(&dir->i_mutex); | |
1175 | return PTR_ERR(dentry); | |
1176 | } | |
1177 | /* known good */ | |
1178 | need_reval = 0; | |
1179 | status = 1; | |
44396f4b JB |
1180 | } else if (unlikely(d_need_lookup(dentry))) { |
1181 | dentry = d_inode_lookup(parent, dentry, nd); | |
1182 | if (IS_ERR(dentry)) { | |
1183 | mutex_unlock(&dir->i_mutex); | |
1184 | return PTR_ERR(dentry); | |
1185 | } | |
1186 | /* known good */ | |
1187 | need_reval = 0; | |
1188 | status = 1; | |
5a18fff2 AV |
1189 | } |
1190 | mutex_unlock(&dir->i_mutex); | |
1191 | } | |
1192 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) | |
1193 | status = d_revalidate(dentry, nd); | |
1194 | if (unlikely(status <= 0)) { | |
1195 | if (status < 0) { | |
1196 | dput(dentry); | |
1197 | return status; | |
1198 | } | |
1199 | if (!d_invalidate(dentry)) { | |
1200 | dput(dentry); | |
1201 | dentry = NULL; | |
1202 | need_reval = 1; | |
1203 | goto retry; | |
1204 | } | |
24643087 | 1205 | } |
5a18fff2 | 1206 | |
9875cf80 DH |
1207 | path->mnt = mnt; |
1208 | path->dentry = dentry; | |
1209 | err = follow_managed(path, nd->flags); | |
89312214 IK |
1210 | if (unlikely(err < 0)) { |
1211 | path_put_conditional(path, nd); | |
9875cf80 | 1212 | return err; |
89312214 | 1213 | } |
9875cf80 | 1214 | *inode = path->dentry->d_inode; |
1da177e4 | 1215 | return 0; |
1da177e4 LT |
1216 | } |
1217 | ||
52094c8a AV |
1218 | static inline int may_lookup(struct nameidata *nd) |
1219 | { | |
1220 | if (nd->flags & LOOKUP_RCU) { | |
4ad5abb3 | 1221 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
52094c8a AV |
1222 | if (err != -ECHILD) |
1223 | return err; | |
19660af7 | 1224 | if (unlazy_walk(nd, NULL)) |
52094c8a AV |
1225 | return -ECHILD; |
1226 | } | |
4ad5abb3 | 1227 | return inode_permission(nd->inode, MAY_EXEC); |
52094c8a AV |
1228 | } |
1229 | ||
9856fa1b AV |
1230 | static inline int handle_dots(struct nameidata *nd, int type) |
1231 | { | |
1232 | if (type == LAST_DOTDOT) { | |
1233 | if (nd->flags & LOOKUP_RCU) { | |
1234 | if (follow_dotdot_rcu(nd)) | |
1235 | return -ECHILD; | |
1236 | } else | |
1237 | follow_dotdot(nd); | |
1238 | } | |
1239 | return 0; | |
1240 | } | |
1241 | ||
951361f9 AV |
1242 | static void terminate_walk(struct nameidata *nd) |
1243 | { | |
1244 | if (!(nd->flags & LOOKUP_RCU)) { | |
1245 | path_put(&nd->path); | |
1246 | } else { | |
1247 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1248 | if (!(nd->flags & LOOKUP_ROOT)) |
1249 | nd->root.mnt = NULL; | |
951361f9 AV |
1250 | rcu_read_unlock(); |
1251 | br_read_unlock(vfsmount_lock); | |
1252 | } | |
1253 | } | |
1254 | ||
3ddcd056 LT |
1255 | /* |
1256 | * Do we need to follow links? We _really_ want to be able | |
1257 | * to do this check without having to look at inode->i_op, | |
1258 | * so we keep a cache of "no, this doesn't need follow_link" | |
1259 | * for the common case. | |
1260 | */ | |
7813b94a | 1261 | static inline int should_follow_link(struct inode *inode, int follow) |
3ddcd056 LT |
1262 | { |
1263 | if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { | |
1264 | if (likely(inode->i_op->follow_link)) | |
1265 | return follow; | |
1266 | ||
1267 | /* This gets set once for the inode lifetime */ | |
1268 | spin_lock(&inode->i_lock); | |
1269 | inode->i_opflags |= IOP_NOFOLLOW; | |
1270 | spin_unlock(&inode->i_lock); | |
1271 | } | |
1272 | return 0; | |
1273 | } | |
1274 | ||
ce57dfc1 AV |
1275 | static inline int walk_component(struct nameidata *nd, struct path *path, |
1276 | struct qstr *name, int type, int follow) | |
1277 | { | |
1278 | struct inode *inode; | |
1279 | int err; | |
1280 | /* | |
1281 | * "." and ".." are special - ".." especially so because it has | |
1282 | * to be able to know about the current root directory and | |
1283 | * parent relationships. | |
1284 | */ | |
1285 | if (unlikely(type != LAST_NORM)) | |
1286 | return handle_dots(nd, type); | |
1287 | err = do_lookup(nd, name, path, &inode); | |
1288 | if (unlikely(err)) { | |
1289 | terminate_walk(nd); | |
1290 | return err; | |
1291 | } | |
1292 | if (!inode) { | |
1293 | path_to_nameidata(path, nd); | |
1294 | terminate_walk(nd); | |
1295 | return -ENOENT; | |
1296 | } | |
7813b94a | 1297 | if (should_follow_link(inode, follow)) { |
19660af7 AV |
1298 | if (nd->flags & LOOKUP_RCU) { |
1299 | if (unlikely(unlazy_walk(nd, path->dentry))) { | |
1300 | terminate_walk(nd); | |
1301 | return -ECHILD; | |
1302 | } | |
1303 | } | |
ce57dfc1 AV |
1304 | BUG_ON(inode != path->dentry->d_inode); |
1305 | return 1; | |
1306 | } | |
1307 | path_to_nameidata(path, nd); | |
1308 | nd->inode = inode; | |
1309 | return 0; | |
1310 | } | |
1311 | ||
b356379a AV |
1312 | /* |
1313 | * This limits recursive symlink follows to 8, while | |
1314 | * limiting consecutive symlinks to 40. | |
1315 | * | |
1316 | * Without that kind of total limit, nasty chains of consecutive | |
1317 | * symlinks can cause almost arbitrarily long lookups. | |
1318 | */ | |
1319 | static inline int nested_symlink(struct path *path, struct nameidata *nd) | |
1320 | { | |
1321 | int res; | |
1322 | ||
b356379a AV |
1323 | if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { |
1324 | path_put_conditional(path, nd); | |
1325 | path_put(&nd->path); | |
1326 | return -ELOOP; | |
1327 | } | |
1a4022f8 | 1328 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); |
b356379a AV |
1329 | |
1330 | nd->depth++; | |
1331 | current->link_count++; | |
1332 | ||
1333 | do { | |
1334 | struct path link = *path; | |
1335 | void *cookie; | |
574197e0 AV |
1336 | |
1337 | res = follow_link(&link, nd, &cookie); | |
b356379a AV |
1338 | if (!res) |
1339 | res = walk_component(nd, path, &nd->last, | |
1340 | nd->last_type, LOOKUP_FOLLOW); | |
574197e0 | 1341 | put_link(nd, &link, cookie); |
b356379a AV |
1342 | } while (res > 0); |
1343 | ||
1344 | current->link_count--; | |
1345 | nd->depth--; | |
1346 | return res; | |
1347 | } | |
1348 | ||
3ddcd056 LT |
1349 | /* |
1350 | * We really don't want to look at inode->i_op->lookup | |
1351 | * when we don't have to. So we keep a cache bit in | |
1352 | * the inode ->i_opflags field that says "yes, we can | |
1353 | * do lookup on this inode". | |
1354 | */ | |
1355 | static inline int can_lookup(struct inode *inode) | |
1356 | { | |
1357 | if (likely(inode->i_opflags & IOP_LOOKUP)) | |
1358 | return 1; | |
1359 | if (likely(!inode->i_op->lookup)) | |
1360 | return 0; | |
1361 | ||
1362 | /* We do this once for the lifetime of the inode */ | |
1363 | spin_lock(&inode->i_lock); | |
1364 | inode->i_opflags |= IOP_LOOKUP; | |
1365 | spin_unlock(&inode->i_lock); | |
1366 | return 1; | |
1367 | } | |
1368 | ||
1da177e4 LT |
1369 | /* |
1370 | * Name resolution. | |
ea3834d9 PM |
1371 | * This is the basic name resolution function, turning a pathname into |
1372 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 1373 | * |
ea3834d9 PM |
1374 | * Returns 0 and nd will have valid dentry and mnt on success. |
1375 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 1376 | */ |
6de88d72 | 1377 | static int link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 LT |
1378 | { |
1379 | struct path next; | |
1da177e4 | 1380 | int err; |
1da177e4 LT |
1381 | |
1382 | while (*name=='/') | |
1383 | name++; | |
1384 | if (!*name) | |
086e183a | 1385 | return 0; |
1da177e4 | 1386 | |
1da177e4 LT |
1387 | /* At this point we know we have a real path component. */ |
1388 | for(;;) { | |
1389 | unsigned long hash; | |
1390 | struct qstr this; | |
1391 | unsigned int c; | |
fe479a58 | 1392 | int type; |
1da177e4 | 1393 | |
52094c8a | 1394 | err = may_lookup(nd); |
1da177e4 LT |
1395 | if (err) |
1396 | break; | |
1397 | ||
1398 | this.name = name; | |
1399 | c = *(const unsigned char *)name; | |
1400 | ||
1401 | hash = init_name_hash(); | |
1402 | do { | |
1403 | name++; | |
1404 | hash = partial_name_hash(c, hash); | |
1405 | c = *(const unsigned char *)name; | |
1406 | } while (c && (c != '/')); | |
1407 | this.len = name - (const char *) this.name; | |
1408 | this.hash = end_name_hash(hash); | |
1409 | ||
fe479a58 AV |
1410 | type = LAST_NORM; |
1411 | if (this.name[0] == '.') switch (this.len) { | |
1412 | case 2: | |
16c2cd71 | 1413 | if (this.name[1] == '.') { |
fe479a58 | 1414 | type = LAST_DOTDOT; |
16c2cd71 AV |
1415 | nd->flags |= LOOKUP_JUMPED; |
1416 | } | |
fe479a58 AV |
1417 | break; |
1418 | case 1: | |
1419 | type = LAST_DOT; | |
1420 | } | |
5a202bcd AV |
1421 | if (likely(type == LAST_NORM)) { |
1422 | struct dentry *parent = nd->path.dentry; | |
16c2cd71 | 1423 | nd->flags &= ~LOOKUP_JUMPED; |
5a202bcd AV |
1424 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
1425 | err = parent->d_op->d_hash(parent, nd->inode, | |
1426 | &this); | |
1427 | if (err < 0) | |
1428 | break; | |
1429 | } | |
1430 | } | |
fe479a58 | 1431 | |
1da177e4 LT |
1432 | /* remove trailing slashes? */ |
1433 | if (!c) | |
1434 | goto last_component; | |
1435 | while (*++name == '/'); | |
1436 | if (!*name) | |
b356379a | 1437 | goto last_component; |
1da177e4 | 1438 | |
ce57dfc1 AV |
1439 | err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); |
1440 | if (err < 0) | |
1441 | return err; | |
1da177e4 | 1442 | |
ce57dfc1 | 1443 | if (err) { |
b356379a | 1444 | err = nested_symlink(&next, nd); |
1da177e4 | 1445 | if (err) |
a7472bab | 1446 | return err; |
31e6b01f | 1447 | } |
3ddcd056 LT |
1448 | if (can_lookup(nd->inode)) |
1449 | continue; | |
1da177e4 | 1450 | err = -ENOTDIR; |
3ddcd056 | 1451 | break; |
1da177e4 LT |
1452 | /* here ends the main loop */ |
1453 | ||
1da177e4 | 1454 | last_component: |
b356379a AV |
1455 | nd->last = this; |
1456 | nd->last_type = type; | |
086e183a | 1457 | return 0; |
1da177e4 | 1458 | } |
951361f9 | 1459 | terminate_walk(nd); |
1da177e4 LT |
1460 | return err; |
1461 | } | |
1462 | ||
70e9b357 AV |
1463 | static int path_init(int dfd, const char *name, unsigned int flags, |
1464 | struct nameidata *nd, struct file **fp) | |
31e6b01f NP |
1465 | { |
1466 | int retval = 0; | |
1467 | int fput_needed; | |
1468 | struct file *file; | |
1469 | ||
1470 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
16c2cd71 | 1471 | nd->flags = flags | LOOKUP_JUMPED; |
31e6b01f | 1472 | nd->depth = 0; |
5b6ca027 AV |
1473 | if (flags & LOOKUP_ROOT) { |
1474 | struct inode *inode = nd->root.dentry->d_inode; | |
73d049a4 AV |
1475 | if (*name) { |
1476 | if (!inode->i_op->lookup) | |
1477 | return -ENOTDIR; | |
1478 | retval = inode_permission(inode, MAY_EXEC); | |
1479 | if (retval) | |
1480 | return retval; | |
1481 | } | |
5b6ca027 AV |
1482 | nd->path = nd->root; |
1483 | nd->inode = inode; | |
1484 | if (flags & LOOKUP_RCU) { | |
1485 | br_read_lock(vfsmount_lock); | |
1486 | rcu_read_lock(); | |
1487 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
1488 | } else { | |
1489 | path_get(&nd->path); | |
1490 | } | |
1491 | return 0; | |
1492 | } | |
1493 | ||
31e6b01f | 1494 | nd->root.mnt = NULL; |
31e6b01f NP |
1495 | |
1496 | if (*name=='/') { | |
e41f7d4e AV |
1497 | if (flags & LOOKUP_RCU) { |
1498 | br_read_lock(vfsmount_lock); | |
1499 | rcu_read_lock(); | |
1500 | set_root_rcu(nd); | |
1501 | } else { | |
1502 | set_root(nd); | |
1503 | path_get(&nd->root); | |
1504 | } | |
1505 | nd->path = nd->root; | |
31e6b01f | 1506 | } else if (dfd == AT_FDCWD) { |
e41f7d4e AV |
1507 | if (flags & LOOKUP_RCU) { |
1508 | struct fs_struct *fs = current->fs; | |
1509 | unsigned seq; | |
31e6b01f | 1510 | |
e41f7d4e AV |
1511 | br_read_lock(vfsmount_lock); |
1512 | rcu_read_lock(); | |
c28cc364 | 1513 | |
e41f7d4e AV |
1514 | do { |
1515 | seq = read_seqcount_begin(&fs->seq); | |
1516 | nd->path = fs->pwd; | |
1517 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
1518 | } while (read_seqcount_retry(&fs->seq, seq)); | |
1519 | } else { | |
1520 | get_fs_pwd(current->fs, &nd->path); | |
1521 | } | |
31e6b01f NP |
1522 | } else { |
1523 | struct dentry *dentry; | |
1524 | ||
1abf0c71 | 1525 | file = fget_raw_light(dfd, &fput_needed); |
31e6b01f NP |
1526 | retval = -EBADF; |
1527 | if (!file) | |
1528 | goto out_fail; | |
1529 | ||
1530 | dentry = file->f_path.dentry; | |
1531 | ||
f52e0c11 AV |
1532 | if (*name) { |
1533 | retval = -ENOTDIR; | |
1534 | if (!S_ISDIR(dentry->d_inode->i_mode)) | |
1535 | goto fput_fail; | |
31e6b01f | 1536 | |
4ad5abb3 | 1537 | retval = inode_permission(dentry->d_inode, MAY_EXEC); |
f52e0c11 AV |
1538 | if (retval) |
1539 | goto fput_fail; | |
1540 | } | |
31e6b01f NP |
1541 | |
1542 | nd->path = file->f_path; | |
e41f7d4e AV |
1543 | if (flags & LOOKUP_RCU) { |
1544 | if (fput_needed) | |
70e9b357 | 1545 | *fp = file; |
e41f7d4e AV |
1546 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
1547 | br_read_lock(vfsmount_lock); | |
1548 | rcu_read_lock(); | |
1549 | } else { | |
1550 | path_get(&file->f_path); | |
1551 | fput_light(file, fput_needed); | |
1552 | } | |
31e6b01f | 1553 | } |
31e6b01f | 1554 | |
31e6b01f | 1555 | nd->inode = nd->path.dentry->d_inode; |
9b4a9b14 | 1556 | return 0; |
2dfdd266 | 1557 | |
9b4a9b14 AV |
1558 | fput_fail: |
1559 | fput_light(file, fput_needed); | |
1560 | out_fail: | |
1561 | return retval; | |
1562 | } | |
1563 | ||
bd92d7fe AV |
1564 | static inline int lookup_last(struct nameidata *nd, struct path *path) |
1565 | { | |
1566 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) | |
1567 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
1568 | ||
1569 | nd->flags &= ~LOOKUP_PARENT; | |
1570 | return walk_component(nd, path, &nd->last, nd->last_type, | |
1571 | nd->flags & LOOKUP_FOLLOW); | |
1572 | } | |
1573 | ||
9b4a9b14 | 1574 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
ee0827cd | 1575 | static int path_lookupat(int dfd, const char *name, |
9b4a9b14 AV |
1576 | unsigned int flags, struct nameidata *nd) |
1577 | { | |
70e9b357 | 1578 | struct file *base = NULL; |
bd92d7fe AV |
1579 | struct path path; |
1580 | int err; | |
31e6b01f NP |
1581 | |
1582 | /* | |
1583 | * Path walking is largely split up into 2 different synchronisation | |
1584 | * schemes, rcu-walk and ref-walk (explained in | |
1585 | * Documentation/filesystems/path-lookup.txt). These share much of the | |
1586 | * path walk code, but some things particularly setup, cleanup, and | |
1587 | * following mounts are sufficiently divergent that functions are | |
1588 | * duplicated. Typically there is a function foo(), and its RCU | |
1589 | * analogue, foo_rcu(). | |
1590 | * | |
1591 | * -ECHILD is the error number of choice (just to avoid clashes) that | |
1592 | * is returned if some aspect of an rcu-walk fails. Such an error must | |
1593 | * be handled by restarting a traditional ref-walk (which will always | |
1594 | * be able to complete). | |
1595 | */ | |
bd92d7fe | 1596 | err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); |
ee0827cd | 1597 | |
bd92d7fe AV |
1598 | if (unlikely(err)) |
1599 | return err; | |
ee0827cd AV |
1600 | |
1601 | current->total_link_count = 0; | |
bd92d7fe AV |
1602 | err = link_path_walk(name, nd); |
1603 | ||
1604 | if (!err && !(flags & LOOKUP_PARENT)) { | |
bd92d7fe AV |
1605 | err = lookup_last(nd, &path); |
1606 | while (err > 0) { | |
1607 | void *cookie; | |
1608 | struct path link = path; | |
bd92d7fe | 1609 | nd->flags |= LOOKUP_PARENT; |
574197e0 | 1610 | err = follow_link(&link, nd, &cookie); |
bd92d7fe AV |
1611 | if (!err) |
1612 | err = lookup_last(nd, &path); | |
574197e0 | 1613 | put_link(nd, &link, cookie); |
bd92d7fe AV |
1614 | } |
1615 | } | |
ee0827cd | 1616 | |
9f1fafee AV |
1617 | if (!err) |
1618 | err = complete_walk(nd); | |
bd92d7fe AV |
1619 | |
1620 | if (!err && nd->flags & LOOKUP_DIRECTORY) { | |
1621 | if (!nd->inode->i_op->lookup) { | |
1622 | path_put(&nd->path); | |
bd23a539 | 1623 | err = -ENOTDIR; |
bd92d7fe AV |
1624 | } |
1625 | } | |
16c2cd71 | 1626 | |
70e9b357 AV |
1627 | if (base) |
1628 | fput(base); | |
ee0827cd | 1629 | |
5b6ca027 | 1630 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
2a737871 AV |
1631 | path_put(&nd->root); |
1632 | nd->root.mnt = NULL; | |
1633 | } | |
bd92d7fe | 1634 | return err; |
ee0827cd | 1635 | } |
31e6b01f | 1636 | |
ee0827cd AV |
1637 | static int do_path_lookup(int dfd, const char *name, |
1638 | unsigned int flags, struct nameidata *nd) | |
1639 | { | |
1640 | int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); | |
1641 | if (unlikely(retval == -ECHILD)) | |
1642 | retval = path_lookupat(dfd, name, flags, nd); | |
1643 | if (unlikely(retval == -ESTALE)) | |
1644 | retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); | |
31e6b01f NP |
1645 | |
1646 | if (likely(!retval)) { | |
1647 | if (unlikely(!audit_dummy_context())) { | |
1648 | if (nd->path.dentry && nd->inode) | |
1649 | audit_inode(name, nd->path.dentry); | |
1650 | } | |
1651 | } | |
170aa3d0 | 1652 | return retval; |
1da177e4 LT |
1653 | } |
1654 | ||
c9c6cac0 | 1655 | int kern_path_parent(const char *name, struct nameidata *nd) |
5590ff0d | 1656 | { |
c9c6cac0 | 1657 | return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); |
5590ff0d UD |
1658 | } |
1659 | ||
d1811465 AV |
1660 | int kern_path(const char *name, unsigned int flags, struct path *path) |
1661 | { | |
1662 | struct nameidata nd; | |
1663 | int res = do_path_lookup(AT_FDCWD, name, flags, &nd); | |
1664 | if (!res) | |
1665 | *path = nd.path; | |
1666 | return res; | |
1667 | } | |
1668 | ||
16f18200 JJS |
1669 | /** |
1670 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
1671 | * @dentry: pointer to dentry of the base directory | |
1672 | * @mnt: pointer to vfs mount of the base directory | |
1673 | * @name: pointer to file name | |
1674 | * @flags: lookup flags | |
e0a01249 | 1675 | * @path: pointer to struct path to fill |
16f18200 JJS |
1676 | */ |
1677 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
1678 | const char *name, unsigned int flags, | |
e0a01249 | 1679 | struct path *path) |
16f18200 | 1680 | { |
e0a01249 AV |
1681 | struct nameidata nd; |
1682 | int err; | |
1683 | nd.root.dentry = dentry; | |
1684 | nd.root.mnt = mnt; | |
1685 | BUG_ON(flags & LOOKUP_PARENT); | |
5b6ca027 | 1686 | /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ |
e0a01249 AV |
1687 | err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); |
1688 | if (!err) | |
1689 | *path = nd.path; | |
1690 | return err; | |
16f18200 JJS |
1691 | } |
1692 | ||
eead1911 CH |
1693 | static struct dentry *__lookup_hash(struct qstr *name, |
1694 | struct dentry *base, struct nameidata *nd) | |
1da177e4 | 1695 | { |
81fca444 | 1696 | struct inode *inode = base->d_inode; |
057f6c01 | 1697 | struct dentry *dentry; |
1da177e4 LT |
1698 | int err; |
1699 | ||
4ad5abb3 | 1700 | err = inode_permission(inode, MAY_EXEC); |
81fca444 CH |
1701 | if (err) |
1702 | return ERR_PTR(err); | |
1da177e4 | 1703 | |
b04f784e NP |
1704 | /* |
1705 | * Don't bother with __d_lookup: callers are for creat as | |
1706 | * well as unlink, so a lot of the time it would cost | |
1707 | * a double lookup. | |
6e6b1bd1 | 1708 | */ |
b04f784e | 1709 | dentry = d_lookup(base, name); |
6e6b1bd1 | 1710 | |
44396f4b JB |
1711 | if (dentry && d_need_lookup(dentry)) { |
1712 | /* | |
1713 | * __lookup_hash is called with the parent dir's i_mutex already | |
1714 | * held, so we are good to go here. | |
1715 | */ | |
1716 | dentry = d_inode_lookup(base, dentry, nd); | |
1717 | if (IS_ERR(dentry)) | |
1718 | return dentry; | |
1719 | } | |
1720 | ||
d2d9e9fb AV |
1721 | if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
1722 | int status = d_revalidate(dentry, nd); | |
1723 | if (unlikely(status <= 0)) { | |
1724 | /* | |
1725 | * The dentry failed validation. | |
1726 | * If d_revalidate returned 0 attempt to invalidate | |
1727 | * the dentry otherwise d_revalidate is asking us | |
1728 | * to return a fail status. | |
1729 | */ | |
1730 | if (status < 0) { | |
1731 | dput(dentry); | |
1732 | return ERR_PTR(status); | |
1733 | } else if (!d_invalidate(dentry)) { | |
1734 | dput(dentry); | |
1735 | dentry = NULL; | |
1736 | } | |
1737 | } | |
1738 | } | |
6e6b1bd1 | 1739 | |
baa03890 NP |
1740 | if (!dentry) |
1741 | dentry = d_alloc_and_lookup(base, name, nd); | |
5a202bcd | 1742 | |
1da177e4 LT |
1743 | return dentry; |
1744 | } | |
1745 | ||
057f6c01 JM |
1746 | /* |
1747 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
1748 | * needs parent already locked. Doesn't follow mounts. | |
1749 | * SMP-safe. | |
1750 | */ | |
eead1911 | 1751 | static struct dentry *lookup_hash(struct nameidata *nd) |
057f6c01 | 1752 | { |
4ac91378 | 1753 | return __lookup_hash(&nd->last, nd->path.dentry, nd); |
1da177e4 LT |
1754 | } |
1755 | ||
eead1911 | 1756 | /** |
a6b91919 | 1757 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
1758 | * @name: pathname component to lookup |
1759 | * @base: base directory to lookup from | |
1760 | * @len: maximum length @len should be interpreted to | |
1761 | * | |
a6b91919 RD |
1762 | * Note that this routine is purely a helper for filesystem usage and should |
1763 | * not be called by generic code. Also note that by using this function the | |
eead1911 CH |
1764 | * nameidata argument is passed to the filesystem methods and a filesystem |
1765 | * using this helper needs to be prepared for that. | |
1766 | */ | |
057f6c01 JM |
1767 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
1768 | { | |
057f6c01 | 1769 | struct qstr this; |
6a96ba54 AV |
1770 | unsigned long hash; |
1771 | unsigned int c; | |
057f6c01 | 1772 | |
2f9092e1 DW |
1773 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
1774 | ||
6a96ba54 AV |
1775 | this.name = name; |
1776 | this.len = len; | |
1777 | if (!len) | |
1778 | return ERR_PTR(-EACCES); | |
1779 | ||
1780 | hash = init_name_hash(); | |
1781 | while (len--) { | |
1782 | c = *(const unsigned char *)name++; | |
1783 | if (c == '/' || c == '\0') | |
1784 | return ERR_PTR(-EACCES); | |
1785 | hash = partial_name_hash(c, hash); | |
1786 | } | |
1787 | this.hash = end_name_hash(hash); | |
5a202bcd AV |
1788 | /* |
1789 | * See if the low-level filesystem might want | |
1790 | * to use its own hash.. | |
1791 | */ | |
1792 | if (base->d_flags & DCACHE_OP_HASH) { | |
1793 | int err = base->d_op->d_hash(base, base->d_inode, &this); | |
1794 | if (err < 0) | |
1795 | return ERR_PTR(err); | |
1796 | } | |
eead1911 | 1797 | |
49705b77 | 1798 | return __lookup_hash(&this, base, NULL); |
057f6c01 JM |
1799 | } |
1800 | ||
2d8f3038 AV |
1801 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
1802 | struct path *path) | |
1da177e4 | 1803 | { |
2d8f3038 | 1804 | struct nameidata nd; |
f52e0c11 | 1805 | char *tmp = getname_flags(name, flags); |
1da177e4 | 1806 | int err = PTR_ERR(tmp); |
1da177e4 | 1807 | if (!IS_ERR(tmp)) { |
2d8f3038 AV |
1808 | |
1809 | BUG_ON(flags & LOOKUP_PARENT); | |
1810 | ||
1811 | err = do_path_lookup(dfd, tmp, flags, &nd); | |
1da177e4 | 1812 | putname(tmp); |
2d8f3038 AV |
1813 | if (!err) |
1814 | *path = nd.path; | |
1da177e4 LT |
1815 | } |
1816 | return err; | |
1817 | } | |
1818 | ||
2ad94ae6 AV |
1819 | static int user_path_parent(int dfd, const char __user *path, |
1820 | struct nameidata *nd, char **name) | |
1821 | { | |
1822 | char *s = getname(path); | |
1823 | int error; | |
1824 | ||
1825 | if (IS_ERR(s)) | |
1826 | return PTR_ERR(s); | |
1827 | ||
1828 | error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); | |
1829 | if (error) | |
1830 | putname(s); | |
1831 | else | |
1832 | *name = s; | |
1833 | ||
1834 | return error; | |
1835 | } | |
1836 | ||
1da177e4 LT |
1837 | /* |
1838 | * It's inline, so penalty for filesystems that don't use sticky bit is | |
1839 | * minimal. | |
1840 | */ | |
1841 | static inline int check_sticky(struct inode *dir, struct inode *inode) | |
1842 | { | |
da9592ed DH |
1843 | uid_t fsuid = current_fsuid(); |
1844 | ||
1da177e4 LT |
1845 | if (!(dir->i_mode & S_ISVTX)) |
1846 | return 0; | |
e795b717 SH |
1847 | if (current_user_ns() != inode_userns(inode)) |
1848 | goto other_userns; | |
da9592ed | 1849 | if (inode->i_uid == fsuid) |
1da177e4 | 1850 | return 0; |
da9592ed | 1851 | if (dir->i_uid == fsuid) |
1da177e4 | 1852 | return 0; |
e795b717 SH |
1853 | |
1854 | other_userns: | |
1855 | return !ns_capable(inode_userns(inode), CAP_FOWNER); | |
1da177e4 LT |
1856 | } |
1857 | ||
1858 | /* | |
1859 | * Check whether we can remove a link victim from directory dir, check | |
1860 | * whether the type of victim is right. | |
1861 | * 1. We can't do it if dir is read-only (done in permission()) | |
1862 | * 2. We should have write and exec permissions on dir | |
1863 | * 3. We can't remove anything from append-only dir | |
1864 | * 4. We can't do anything with immutable dir (done in permission()) | |
1865 | * 5. If the sticky bit on dir is set we should either | |
1866 | * a. be owner of dir, or | |
1867 | * b. be owner of victim, or | |
1868 | * c. have CAP_FOWNER capability | |
1869 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
1870 | * links pointing to it. | |
1871 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
1872 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
1873 | * 9. We can't remove a root or mountpoint. | |
1874 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
1875 | * nfs_async_unlink(). | |
1876 | */ | |
858119e1 | 1877 | static int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
1da177e4 LT |
1878 | { |
1879 | int error; | |
1880 | ||
1881 | if (!victim->d_inode) | |
1882 | return -ENOENT; | |
1883 | ||
1884 | BUG_ON(victim->d_parent->d_inode != dir); | |
cccc6bba | 1885 | audit_inode_child(victim, dir); |
1da177e4 | 1886 | |
f419a2e3 | 1887 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
1888 | if (error) |
1889 | return error; | |
1890 | if (IS_APPEND(dir)) | |
1891 | return -EPERM; | |
1892 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| | |
f9454548 | 1893 | IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) |
1da177e4 LT |
1894 | return -EPERM; |
1895 | if (isdir) { | |
1896 | if (!S_ISDIR(victim->d_inode->i_mode)) | |
1897 | return -ENOTDIR; | |
1898 | if (IS_ROOT(victim)) | |
1899 | return -EBUSY; | |
1900 | } else if (S_ISDIR(victim->d_inode->i_mode)) | |
1901 | return -EISDIR; | |
1902 | if (IS_DEADDIR(dir)) | |
1903 | return -ENOENT; | |
1904 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
1905 | return -EBUSY; | |
1906 | return 0; | |
1907 | } | |
1908 | ||
1909 | /* Check whether we can create an object with dentry child in directory | |
1910 | * dir. | |
1911 | * 1. We can't do it if child already exists (open has special treatment for | |
1912 | * this case, but since we are inlined it's OK) | |
1913 | * 2. We can't do it if dir is read-only (done in permission()) | |
1914 | * 3. We should have write and exec permissions on dir | |
1915 | * 4. We can't do it if dir is immutable (done in permission()) | |
1916 | */ | |
a95164d9 | 1917 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 LT |
1918 | { |
1919 | if (child->d_inode) | |
1920 | return -EEXIST; | |
1921 | if (IS_DEADDIR(dir)) | |
1922 | return -ENOENT; | |
f419a2e3 | 1923 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
1924 | } |
1925 | ||
1da177e4 LT |
1926 | /* |
1927 | * p1 and p2 should be directories on the same fs. | |
1928 | */ | |
1929 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
1930 | { | |
1931 | struct dentry *p; | |
1932 | ||
1933 | if (p1 == p2) { | |
f2eace23 | 1934 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
1935 | return NULL; |
1936 | } | |
1937 | ||
a11f3a05 | 1938 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 | 1939 | |
e2761a11 OH |
1940 | p = d_ancestor(p2, p1); |
1941 | if (p) { | |
1942 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); | |
1943 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
1944 | return p; | |
1da177e4 LT |
1945 | } |
1946 | ||
e2761a11 OH |
1947 | p = d_ancestor(p1, p2); |
1948 | if (p) { | |
1949 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); | |
1950 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1951 | return p; | |
1da177e4 LT |
1952 | } |
1953 | ||
f2eace23 IM |
1954 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1955 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1da177e4 LT |
1956 | return NULL; |
1957 | } | |
1958 | ||
1959 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
1960 | { | |
1b1dcc1b | 1961 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 1962 | if (p1 != p2) { |
1b1dcc1b | 1963 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 1964 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
1965 | } |
1966 | } | |
1967 | ||
1968 | int vfs_create(struct inode *dir, struct dentry *dentry, int mode, | |
1969 | struct nameidata *nd) | |
1970 | { | |
a95164d9 | 1971 | int error = may_create(dir, dentry); |
1da177e4 LT |
1972 | |
1973 | if (error) | |
1974 | return error; | |
1975 | ||
acfa4380 | 1976 | if (!dir->i_op->create) |
1da177e4 LT |
1977 | return -EACCES; /* shouldn't it be ENOSYS? */ |
1978 | mode &= S_IALLUGO; | |
1979 | mode |= S_IFREG; | |
1980 | error = security_inode_create(dir, dentry, mode); | |
1981 | if (error) | |
1982 | return error; | |
1da177e4 | 1983 | error = dir->i_op->create(dir, dentry, mode, nd); |
a74574aa | 1984 | if (!error) |
f38aa942 | 1985 | fsnotify_create(dir, dentry); |
1da177e4 LT |
1986 | return error; |
1987 | } | |
1988 | ||
73d049a4 | 1989 | static int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 1990 | { |
3fb64190 | 1991 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
1992 | struct inode *inode = dentry->d_inode; |
1993 | int error; | |
1994 | ||
bcda7652 AV |
1995 | /* O_PATH? */ |
1996 | if (!acc_mode) | |
1997 | return 0; | |
1998 | ||
1da177e4 LT |
1999 | if (!inode) |
2000 | return -ENOENT; | |
2001 | ||
c8fe8f30 CH |
2002 | switch (inode->i_mode & S_IFMT) { |
2003 | case S_IFLNK: | |
1da177e4 | 2004 | return -ELOOP; |
c8fe8f30 CH |
2005 | case S_IFDIR: |
2006 | if (acc_mode & MAY_WRITE) | |
2007 | return -EISDIR; | |
2008 | break; | |
2009 | case S_IFBLK: | |
2010 | case S_IFCHR: | |
3fb64190 | 2011 | if (path->mnt->mnt_flags & MNT_NODEV) |
1da177e4 | 2012 | return -EACCES; |
c8fe8f30 CH |
2013 | /*FALLTHRU*/ |
2014 | case S_IFIFO: | |
2015 | case S_IFSOCK: | |
1da177e4 | 2016 | flag &= ~O_TRUNC; |
c8fe8f30 | 2017 | break; |
4a3fd211 | 2018 | } |
b41572e9 | 2019 | |
3fb64190 | 2020 | error = inode_permission(inode, acc_mode); |
b41572e9 DH |
2021 | if (error) |
2022 | return error; | |
6146f0d5 | 2023 | |
1da177e4 LT |
2024 | /* |
2025 | * An append-only file must be opened in append mode for writing. | |
2026 | */ | |
2027 | if (IS_APPEND(inode)) { | |
8737c930 | 2028 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
7715b521 | 2029 | return -EPERM; |
1da177e4 | 2030 | if (flag & O_TRUNC) |
7715b521 | 2031 | return -EPERM; |
1da177e4 LT |
2032 | } |
2033 | ||
2034 | /* O_NOATIME can only be set by the owner or superuser */ | |
2e149670 | 2035 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
7715b521 | 2036 | return -EPERM; |
1da177e4 | 2037 | |
f3c7691e | 2038 | return 0; |
7715b521 | 2039 | } |
1da177e4 | 2040 | |
e1181ee6 | 2041 | static int handle_truncate(struct file *filp) |
7715b521 | 2042 | { |
e1181ee6 | 2043 | struct path *path = &filp->f_path; |
7715b521 AV |
2044 | struct inode *inode = path->dentry->d_inode; |
2045 | int error = get_write_access(inode); | |
2046 | if (error) | |
2047 | return error; | |
2048 | /* | |
2049 | * Refuse to truncate files with mandatory locks held on them. | |
2050 | */ | |
2051 | error = locks_verify_locked(inode); | |
2052 | if (!error) | |
ea0d3ab2 | 2053 | error = security_path_truncate(path); |
7715b521 AV |
2054 | if (!error) { |
2055 | error = do_truncate(path->dentry, 0, | |
2056 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
e1181ee6 | 2057 | filp); |
7715b521 AV |
2058 | } |
2059 | put_write_access(inode); | |
acd0c935 | 2060 | return error; |
1da177e4 LT |
2061 | } |
2062 | ||
d57999e1 DH |
2063 | static inline int open_to_namei_flags(int flag) |
2064 | { | |
8a5e929d AV |
2065 | if ((flag & O_ACCMODE) == 3) |
2066 | flag--; | |
d57999e1 DH |
2067 | return flag; |
2068 | } | |
2069 | ||
31e6b01f | 2070 | /* |
fe2d35ff | 2071 | * Handle the last step of open() |
31e6b01f | 2072 | */ |
fb1cc555 | 2073 | static struct file *do_last(struct nameidata *nd, struct path *path, |
c3e380b0 | 2074 | const struct open_flags *op, const char *pathname) |
fb1cc555 | 2075 | { |
a1e28038 | 2076 | struct dentry *dir = nd->path.dentry; |
6c0d46c4 | 2077 | struct dentry *dentry; |
ca344a89 | 2078 | int open_flag = op->open_flag; |
6c0d46c4 | 2079 | int will_truncate = open_flag & O_TRUNC; |
ca344a89 | 2080 | int want_write = 0; |
bcda7652 | 2081 | int acc_mode = op->acc_mode; |
fb1cc555 | 2082 | struct file *filp; |
16c2cd71 | 2083 | int error; |
1f36f774 | 2084 | |
c3e380b0 AV |
2085 | nd->flags &= ~LOOKUP_PARENT; |
2086 | nd->flags |= op->intent; | |
2087 | ||
1f36f774 AV |
2088 | switch (nd->last_type) { |
2089 | case LAST_DOTDOT: | |
176306f5 | 2090 | case LAST_DOT: |
fe2d35ff AV |
2091 | error = handle_dots(nd, nd->last_type); |
2092 | if (error) | |
2093 | return ERR_PTR(error); | |
1f36f774 | 2094 | /* fallthrough */ |
1f36f774 | 2095 | case LAST_ROOT: |
9f1fafee | 2096 | error = complete_walk(nd); |
16c2cd71 | 2097 | if (error) |
9f1fafee | 2098 | return ERR_PTR(error); |
fe2d35ff | 2099 | audit_inode(pathname, nd->path.dentry); |
ca344a89 | 2100 | if (open_flag & O_CREAT) { |
fe2d35ff AV |
2101 | error = -EISDIR; |
2102 | goto exit; | |
2103 | } | |
2104 | goto ok; | |
1f36f774 | 2105 | case LAST_BIND: |
9f1fafee | 2106 | error = complete_walk(nd); |
16c2cd71 | 2107 | if (error) |
9f1fafee | 2108 | return ERR_PTR(error); |
1f36f774 | 2109 | audit_inode(pathname, dir); |
67ee3ad2 | 2110 | goto ok; |
1f36f774 | 2111 | } |
67ee3ad2 | 2112 | |
ca344a89 | 2113 | if (!(open_flag & O_CREAT)) { |
bcda7652 | 2114 | int symlink_ok = 0; |
fe2d35ff AV |
2115 | if (nd->last.name[nd->last.len]) |
2116 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
bcda7652 AV |
2117 | if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) |
2118 | symlink_ok = 1; | |
fe2d35ff | 2119 | /* we _can_ be in RCU mode here */ |
ce57dfc1 AV |
2120 | error = walk_component(nd, path, &nd->last, LAST_NORM, |
2121 | !symlink_ok); | |
2122 | if (error < 0) | |
fe2d35ff | 2123 | return ERR_PTR(error); |
ce57dfc1 | 2124 | if (error) /* symlink */ |
fe2d35ff | 2125 | return NULL; |
fe2d35ff | 2126 | /* sayonara */ |
9f1fafee AV |
2127 | error = complete_walk(nd); |
2128 | if (error) | |
2129 | return ERR_PTR(-ECHILD); | |
fe2d35ff AV |
2130 | |
2131 | error = -ENOTDIR; | |
2132 | if (nd->flags & LOOKUP_DIRECTORY) { | |
ce57dfc1 | 2133 | if (!nd->inode->i_op->lookup) |
fe2d35ff AV |
2134 | goto exit; |
2135 | } | |
2136 | audit_inode(pathname, nd->path.dentry); | |
2137 | goto ok; | |
2138 | } | |
2139 | ||
2140 | /* create side of things */ | |
9f1fafee AV |
2141 | error = complete_walk(nd); |
2142 | if (error) | |
2143 | return ERR_PTR(error); | |
fe2d35ff AV |
2144 | |
2145 | audit_inode(pathname, dir); | |
16c2cd71 | 2146 | error = -EISDIR; |
1f36f774 | 2147 | /* trailing slashes? */ |
31e6b01f NP |
2148 | if (nd->last.name[nd->last.len]) |
2149 | goto exit; | |
a2c36b45 | 2150 | |
a1e28038 AV |
2151 | mutex_lock(&dir->d_inode->i_mutex); |
2152 | ||
6c0d46c4 AV |
2153 | dentry = lookup_hash(nd); |
2154 | error = PTR_ERR(dentry); | |
2155 | if (IS_ERR(dentry)) { | |
fb1cc555 AV |
2156 | mutex_unlock(&dir->d_inode->i_mutex); |
2157 | goto exit; | |
2158 | } | |
2159 | ||
6c0d46c4 AV |
2160 | path->dentry = dentry; |
2161 | path->mnt = nd->path.mnt; | |
2162 | ||
fb1cc555 | 2163 | /* Negative dentry, just create the file */ |
6c0d46c4 AV |
2164 | if (!dentry->d_inode) { |
2165 | int mode = op->mode; | |
2166 | if (!IS_POSIXACL(dir->d_inode)) | |
2167 | mode &= ~current_umask(); | |
fb1cc555 AV |
2168 | /* |
2169 | * This write is needed to ensure that a | |
6c0d46c4 | 2170 | * rw->ro transition does not occur between |
fb1cc555 AV |
2171 | * the time when the file is created and when |
2172 | * a permanent write count is taken through | |
2173 | * the 'struct file' in nameidata_to_filp(). | |
2174 | */ | |
2175 | error = mnt_want_write(nd->path.mnt); | |
2176 | if (error) | |
2177 | goto exit_mutex_unlock; | |
ca344a89 | 2178 | want_write = 1; |
9b44f1b3 | 2179 | /* Don't check for write permission, don't truncate */ |
ca344a89 | 2180 | open_flag &= ~O_TRUNC; |
6c0d46c4 | 2181 | will_truncate = 0; |
bcda7652 | 2182 | acc_mode = MAY_OPEN; |
6c0d46c4 AV |
2183 | error = security_path_mknod(&nd->path, dentry, mode, 0); |
2184 | if (error) | |
2185 | goto exit_mutex_unlock; | |
2186 | error = vfs_create(dir->d_inode, dentry, mode, nd); | |
2187 | if (error) | |
2188 | goto exit_mutex_unlock; | |
2189 | mutex_unlock(&dir->d_inode->i_mutex); | |
2190 | dput(nd->path.dentry); | |
2191 | nd->path.dentry = dentry; | |
ca344a89 | 2192 | goto common; |
fb1cc555 AV |
2193 | } |
2194 | ||
2195 | /* | |
2196 | * It already exists. | |
2197 | */ | |
2198 | mutex_unlock(&dir->d_inode->i_mutex); | |
2199 | audit_inode(pathname, path->dentry); | |
2200 | ||
2201 | error = -EEXIST; | |
ca344a89 | 2202 | if (open_flag & O_EXCL) |
fb1cc555 AV |
2203 | goto exit_dput; |
2204 | ||
9875cf80 DH |
2205 | error = follow_managed(path, nd->flags); |
2206 | if (error < 0) | |
2207 | goto exit_dput; | |
fb1cc555 AV |
2208 | |
2209 | error = -ENOENT; | |
2210 | if (!path->dentry->d_inode) | |
2211 | goto exit_dput; | |
9e67f361 AV |
2212 | |
2213 | if (path->dentry->d_inode->i_op->follow_link) | |
fb1cc555 | 2214 | return NULL; |
fb1cc555 AV |
2215 | |
2216 | path_to_nameidata(path, nd); | |
31e6b01f | 2217 | nd->inode = path->dentry->d_inode; |
fb1cc555 | 2218 | error = -EISDIR; |
31e6b01f | 2219 | if (S_ISDIR(nd->inode->i_mode)) |
fb1cc555 | 2220 | goto exit; |
67ee3ad2 | 2221 | ok: |
6c0d46c4 AV |
2222 | if (!S_ISREG(nd->inode->i_mode)) |
2223 | will_truncate = 0; | |
2224 | ||
0f9d1a10 AV |
2225 | if (will_truncate) { |
2226 | error = mnt_want_write(nd->path.mnt); | |
2227 | if (error) | |
2228 | goto exit; | |
ca344a89 | 2229 | want_write = 1; |
0f9d1a10 | 2230 | } |
ca344a89 | 2231 | common: |
bcda7652 | 2232 | error = may_open(&nd->path, acc_mode, open_flag); |
ca344a89 | 2233 | if (error) |
0f9d1a10 | 2234 | goto exit; |
0f9d1a10 AV |
2235 | filp = nameidata_to_filp(nd); |
2236 | if (!IS_ERR(filp)) { | |
2237 | error = ima_file_check(filp, op->acc_mode); | |
2238 | if (error) { | |
2239 | fput(filp); | |
2240 | filp = ERR_PTR(error); | |
2241 | } | |
2242 | } | |
2243 | if (!IS_ERR(filp)) { | |
2244 | if (will_truncate) { | |
2245 | error = handle_truncate(filp); | |
2246 | if (error) { | |
2247 | fput(filp); | |
2248 | filp = ERR_PTR(error); | |
2249 | } | |
2250 | } | |
2251 | } | |
ca344a89 AV |
2252 | out: |
2253 | if (want_write) | |
0f9d1a10 AV |
2254 | mnt_drop_write(nd->path.mnt); |
2255 | path_put(&nd->path); | |
fb1cc555 AV |
2256 | return filp; |
2257 | ||
2258 | exit_mutex_unlock: | |
2259 | mutex_unlock(&dir->d_inode->i_mutex); | |
2260 | exit_dput: | |
2261 | path_put_conditional(path, nd); | |
2262 | exit: | |
ca344a89 AV |
2263 | filp = ERR_PTR(error); |
2264 | goto out; | |
fb1cc555 AV |
2265 | } |
2266 | ||
13aab428 | 2267 | static struct file *path_openat(int dfd, const char *pathname, |
73d049a4 | 2268 | struct nameidata *nd, const struct open_flags *op, int flags) |
1da177e4 | 2269 | { |
fe2d35ff | 2270 | struct file *base = NULL; |
4a3fd211 | 2271 | struct file *filp; |
9850c056 | 2272 | struct path path; |
13aab428 | 2273 | int error; |
31e6b01f NP |
2274 | |
2275 | filp = get_empty_filp(); | |
2276 | if (!filp) | |
2277 | return ERR_PTR(-ENFILE); | |
2278 | ||
47c805dc | 2279 | filp->f_flags = op->open_flag; |
73d049a4 AV |
2280 | nd->intent.open.file = filp; |
2281 | nd->intent.open.flags = open_to_namei_flags(op->open_flag); | |
2282 | nd->intent.open.create_mode = op->mode; | |
31e6b01f | 2283 | |
73d049a4 | 2284 | error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); |
31e6b01f | 2285 | if (unlikely(error)) |
13aab428 | 2286 | goto out_filp; |
31e6b01f | 2287 | |
fe2d35ff | 2288 | current->total_link_count = 0; |
73d049a4 | 2289 | error = link_path_walk(pathname, nd); |
31e6b01f NP |
2290 | if (unlikely(error)) |
2291 | goto out_filp; | |
1da177e4 | 2292 | |
73d049a4 | 2293 | filp = do_last(nd, &path, op, pathname); |
806b681c | 2294 | while (unlikely(!filp)) { /* trailing symlink */ |
7b9337aa | 2295 | struct path link = path; |
def4af30 | 2296 | void *cookie; |
574197e0 | 2297 | if (!(nd->flags & LOOKUP_FOLLOW)) { |
73d049a4 AV |
2298 | path_put_conditional(&path, nd); |
2299 | path_put(&nd->path); | |
40b39136 AV |
2300 | filp = ERR_PTR(-ELOOP); |
2301 | break; | |
2302 | } | |
73d049a4 AV |
2303 | nd->flags |= LOOKUP_PARENT; |
2304 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); | |
574197e0 | 2305 | error = follow_link(&link, nd, &cookie); |
c3e380b0 | 2306 | if (unlikely(error)) |
f1afe9ef | 2307 | filp = ERR_PTR(error); |
c3e380b0 | 2308 | else |
73d049a4 | 2309 | filp = do_last(nd, &path, op, pathname); |
574197e0 | 2310 | put_link(nd, &link, cookie); |
806b681c | 2311 | } |
10fa8e62 | 2312 | out: |
73d049a4 AV |
2313 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) |
2314 | path_put(&nd->root); | |
fe2d35ff AV |
2315 | if (base) |
2316 | fput(base); | |
73d049a4 | 2317 | release_open_intent(nd); |
10fa8e62 | 2318 | return filp; |
1da177e4 | 2319 | |
31e6b01f | 2320 | out_filp: |
806b681c | 2321 | filp = ERR_PTR(error); |
10fa8e62 | 2322 | goto out; |
1da177e4 LT |
2323 | } |
2324 | ||
13aab428 AV |
2325 | struct file *do_filp_open(int dfd, const char *pathname, |
2326 | const struct open_flags *op, int flags) | |
2327 | { | |
73d049a4 | 2328 | struct nameidata nd; |
13aab428 AV |
2329 | struct file *filp; |
2330 | ||
73d049a4 | 2331 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); |
13aab428 | 2332 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
73d049a4 | 2333 | filp = path_openat(dfd, pathname, &nd, op, flags); |
13aab428 | 2334 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
73d049a4 | 2335 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); |
13aab428 AV |
2336 | return filp; |
2337 | } | |
2338 | ||
73d049a4 AV |
2339 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
2340 | const char *name, const struct open_flags *op, int flags) | |
2341 | { | |
2342 | struct nameidata nd; | |
2343 | struct file *file; | |
2344 | ||
2345 | nd.root.mnt = mnt; | |
2346 | nd.root.dentry = dentry; | |
2347 | ||
2348 | flags |= LOOKUP_ROOT; | |
2349 | ||
bcda7652 | 2350 | if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) |
73d049a4 AV |
2351 | return ERR_PTR(-ELOOP); |
2352 | ||
2353 | file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); | |
2354 | if (unlikely(file == ERR_PTR(-ECHILD))) | |
2355 | file = path_openat(-1, name, &nd, op, flags); | |
2356 | if (unlikely(file == ERR_PTR(-ESTALE))) | |
2357 | file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); | |
2358 | return file; | |
2359 | } | |
2360 | ||
ed75e95d | 2361 | struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) |
1da177e4 | 2362 | { |
c663e5d8 | 2363 | struct dentry *dentry = ERR_PTR(-EEXIST); |
ed75e95d AV |
2364 | struct nameidata nd; |
2365 | int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); | |
2366 | if (error) | |
2367 | return ERR_PTR(error); | |
1da177e4 | 2368 | |
c663e5d8 CH |
2369 | /* |
2370 | * Yucky last component or no last component at all? | |
2371 | * (foo/., foo/.., /////) | |
2372 | */ | |
ed75e95d AV |
2373 | if (nd.last_type != LAST_NORM) |
2374 | goto out; | |
2375 | nd.flags &= ~LOOKUP_PARENT; | |
2376 | nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; | |
2377 | nd.intent.open.flags = O_EXCL; | |
c663e5d8 CH |
2378 | |
2379 | /* | |
2380 | * Do the final lookup. | |
2381 | */ | |
ed75e95d AV |
2382 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
2383 | dentry = lookup_hash(&nd); | |
1da177e4 LT |
2384 | if (IS_ERR(dentry)) |
2385 | goto fail; | |
c663e5d8 | 2386 | |
e9baf6e5 AV |
2387 | if (dentry->d_inode) |
2388 | goto eexist; | |
c663e5d8 CH |
2389 | /* |
2390 | * Special case - lookup gave negative, but... we had foo/bar/ | |
2391 | * From the vfs_mknod() POV we just have a negative dentry - | |
2392 | * all is fine. Let's be bastards - you had / on the end, you've | |
2393 | * been asking for (non-existent) directory. -ENOENT for you. | |
2394 | */ | |
ed75e95d | 2395 | if (unlikely(!is_dir && nd.last.name[nd.last.len])) { |
e9baf6e5 AV |
2396 | dput(dentry); |
2397 | dentry = ERR_PTR(-ENOENT); | |
ed75e95d | 2398 | goto fail; |
e9baf6e5 | 2399 | } |
ed75e95d | 2400 | *path = nd.path; |
1da177e4 | 2401 | return dentry; |
e9baf6e5 | 2402 | eexist: |
1da177e4 | 2403 | dput(dentry); |
e9baf6e5 | 2404 | dentry = ERR_PTR(-EEXIST); |
1da177e4 | 2405 | fail: |
ed75e95d AV |
2406 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
2407 | out: | |
2408 | path_put(&nd.path); | |
1da177e4 LT |
2409 | return dentry; |
2410 | } | |
dae6ad8f AV |
2411 | EXPORT_SYMBOL(kern_path_create); |
2412 | ||
2413 | struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) | |
2414 | { | |
2415 | char *tmp = getname(pathname); | |
2416 | struct dentry *res; | |
2417 | if (IS_ERR(tmp)) | |
2418 | return ERR_CAST(tmp); | |
2419 | res = kern_path_create(dfd, tmp, path, is_dir); | |
2420 | putname(tmp); | |
2421 | return res; | |
2422 | } | |
2423 | EXPORT_SYMBOL(user_path_create); | |
2424 | ||
1da177e4 LT |
2425 | int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) |
2426 | { | |
a95164d9 | 2427 | int error = may_create(dir, dentry); |
1da177e4 LT |
2428 | |
2429 | if (error) | |
2430 | return error; | |
2431 | ||
e795b717 SH |
2432 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && |
2433 | !ns_capable(inode_userns(dir), CAP_MKNOD)) | |
1da177e4 LT |
2434 | return -EPERM; |
2435 | ||
acfa4380 | 2436 | if (!dir->i_op->mknod) |
1da177e4 LT |
2437 | return -EPERM; |
2438 | ||
08ce5f16 SH |
2439 | error = devcgroup_inode_mknod(mode, dev); |
2440 | if (error) | |
2441 | return error; | |
2442 | ||
1da177e4 LT |
2443 | error = security_inode_mknod(dir, dentry, mode, dev); |
2444 | if (error) | |
2445 | return error; | |
2446 | ||
1da177e4 | 2447 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 2448 | if (!error) |
f38aa942 | 2449 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2450 | return error; |
2451 | } | |
2452 | ||
463c3197 DH |
2453 | static int may_mknod(mode_t mode) |
2454 | { | |
2455 | switch (mode & S_IFMT) { | |
2456 | case S_IFREG: | |
2457 | case S_IFCHR: | |
2458 | case S_IFBLK: | |
2459 | case S_IFIFO: | |
2460 | case S_IFSOCK: | |
2461 | case 0: /* zero mode translates to S_IFREG */ | |
2462 | return 0; | |
2463 | case S_IFDIR: | |
2464 | return -EPERM; | |
2465 | default: | |
2466 | return -EINVAL; | |
2467 | } | |
2468 | } | |
2469 | ||
2e4d0924 HC |
2470 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, |
2471 | unsigned, dev) | |
1da177e4 | 2472 | { |
2ad94ae6 | 2473 | struct dentry *dentry; |
dae6ad8f AV |
2474 | struct path path; |
2475 | int error; | |
1da177e4 LT |
2476 | |
2477 | if (S_ISDIR(mode)) | |
2478 | return -EPERM; | |
1da177e4 | 2479 | |
dae6ad8f AV |
2480 | dentry = user_path_create(dfd, filename, &path, 0); |
2481 | if (IS_ERR(dentry)) | |
2482 | return PTR_ERR(dentry); | |
2ad94ae6 | 2483 | |
dae6ad8f | 2484 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 2485 | mode &= ~current_umask(); |
463c3197 DH |
2486 | error = may_mknod(mode); |
2487 | if (error) | |
2488 | goto out_dput; | |
dae6ad8f | 2489 | error = mnt_want_write(path.mnt); |
463c3197 DH |
2490 | if (error) |
2491 | goto out_dput; | |
dae6ad8f | 2492 | error = security_path_mknod(&path, dentry, mode, dev); |
be6d3e56 KT |
2493 | if (error) |
2494 | goto out_drop_write; | |
463c3197 | 2495 | switch (mode & S_IFMT) { |
1da177e4 | 2496 | case 0: case S_IFREG: |
dae6ad8f | 2497 | error = vfs_create(path.dentry->d_inode,dentry,mode,NULL); |
1da177e4 LT |
2498 | break; |
2499 | case S_IFCHR: case S_IFBLK: | |
dae6ad8f | 2500 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
2501 | new_decode_dev(dev)); |
2502 | break; | |
2503 | case S_IFIFO: case S_IFSOCK: | |
dae6ad8f | 2504 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 2505 | break; |
1da177e4 | 2506 | } |
be6d3e56 | 2507 | out_drop_write: |
dae6ad8f | 2508 | mnt_drop_write(path.mnt); |
463c3197 DH |
2509 | out_dput: |
2510 | dput(dentry); | |
dae6ad8f AV |
2511 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
2512 | path_put(&path); | |
1da177e4 LT |
2513 | |
2514 | return error; | |
2515 | } | |
2516 | ||
3480b257 | 2517 | SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) |
5590ff0d UD |
2518 | { |
2519 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
2520 | } | |
2521 | ||
1da177e4 LT |
2522 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
2523 | { | |
a95164d9 | 2524 | int error = may_create(dir, dentry); |
1da177e4 LT |
2525 | |
2526 | if (error) | |
2527 | return error; | |
2528 | ||
acfa4380 | 2529 | if (!dir->i_op->mkdir) |
1da177e4 LT |
2530 | return -EPERM; |
2531 | ||
2532 | mode &= (S_IRWXUGO|S_ISVTX); | |
2533 | error = security_inode_mkdir(dir, dentry, mode); | |
2534 | if (error) | |
2535 | return error; | |
2536 | ||
1da177e4 | 2537 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 2538 | if (!error) |
f38aa942 | 2539 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
2540 | return error; |
2541 | } | |
2542 | ||
2e4d0924 | 2543 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) |
1da177e4 | 2544 | { |
6902d925 | 2545 | struct dentry *dentry; |
dae6ad8f AV |
2546 | struct path path; |
2547 | int error; | |
1da177e4 | 2548 | |
dae6ad8f | 2549 | dentry = user_path_create(dfd, pathname, &path, 1); |
6902d925 | 2550 | if (IS_ERR(dentry)) |
dae6ad8f | 2551 | return PTR_ERR(dentry); |
1da177e4 | 2552 | |
dae6ad8f | 2553 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 2554 | mode &= ~current_umask(); |
dae6ad8f | 2555 | error = mnt_want_write(path.mnt); |
463c3197 DH |
2556 | if (error) |
2557 | goto out_dput; | |
dae6ad8f | 2558 | error = security_path_mkdir(&path, dentry, mode); |
be6d3e56 KT |
2559 | if (error) |
2560 | goto out_drop_write; | |
dae6ad8f | 2561 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); |
be6d3e56 | 2562 | out_drop_write: |
dae6ad8f | 2563 | mnt_drop_write(path.mnt); |
463c3197 | 2564 | out_dput: |
6902d925 | 2565 | dput(dentry); |
dae6ad8f AV |
2566 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
2567 | path_put(&path); | |
1da177e4 LT |
2568 | return error; |
2569 | } | |
2570 | ||
3cdad428 | 2571 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) |
5590ff0d UD |
2572 | { |
2573 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
2574 | } | |
2575 | ||
1da177e4 | 2576 | /* |
a71905f0 SW |
2577 | * The dentry_unhash() helper will try to drop the dentry early: we |
2578 | * should have a usage count of 2 if we're the only user of this | |
2579 | * dentry, and if that is true (possibly after pruning the dcache), | |
2580 | * then we drop the dentry now. | |
1da177e4 LT |
2581 | * |
2582 | * A low-level filesystem can, if it choses, legally | |
2583 | * do a | |
2584 | * | |
2585 | * if (!d_unhashed(dentry)) | |
2586 | * return -EBUSY; | |
2587 | * | |
2588 | * if it cannot handle the case of removing a directory | |
2589 | * that is still in use by something else.. | |
2590 | */ | |
2591 | void dentry_unhash(struct dentry *dentry) | |
2592 | { | |
dc168427 | 2593 | shrink_dcache_parent(dentry); |
1da177e4 | 2594 | spin_lock(&dentry->d_lock); |
64252c75 | 2595 | if (dentry->d_count == 1) |
1da177e4 LT |
2596 | __d_drop(dentry); |
2597 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
2598 | } |
2599 | ||
2600 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
2601 | { | |
2602 | int error = may_delete(dir, dentry, 1); | |
2603 | ||
2604 | if (error) | |
2605 | return error; | |
2606 | ||
acfa4380 | 2607 | if (!dir->i_op->rmdir) |
1da177e4 LT |
2608 | return -EPERM; |
2609 | ||
1d2ef590 | 2610 | dget(dentry); |
1b1dcc1b | 2611 | mutex_lock(&dentry->d_inode->i_mutex); |
912dbc15 SW |
2612 | |
2613 | error = -EBUSY; | |
1da177e4 | 2614 | if (d_mountpoint(dentry)) |
912dbc15 SW |
2615 | goto out; |
2616 | ||
2617 | error = security_inode_rmdir(dir, dentry); | |
2618 | if (error) | |
2619 | goto out; | |
2620 | ||
3cebde24 | 2621 | shrink_dcache_parent(dentry); |
912dbc15 SW |
2622 | error = dir->i_op->rmdir(dir, dentry); |
2623 | if (error) | |
2624 | goto out; | |
2625 | ||
2626 | dentry->d_inode->i_flags |= S_DEAD; | |
2627 | dont_mount(dentry); | |
2628 | ||
2629 | out: | |
1b1dcc1b | 2630 | mutex_unlock(&dentry->d_inode->i_mutex); |
1d2ef590 | 2631 | dput(dentry); |
912dbc15 | 2632 | if (!error) |
1da177e4 | 2633 | d_delete(dentry); |
1da177e4 LT |
2634 | return error; |
2635 | } | |
2636 | ||
5590ff0d | 2637 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
2638 | { |
2639 | int error = 0; | |
2640 | char * name; | |
2641 | struct dentry *dentry; | |
2642 | struct nameidata nd; | |
2643 | ||
2ad94ae6 | 2644 | error = user_path_parent(dfd, pathname, &nd, &name); |
1da177e4 | 2645 | if (error) |
2ad94ae6 | 2646 | return error; |
1da177e4 LT |
2647 | |
2648 | switch(nd.last_type) { | |
0612d9fb OH |
2649 | case LAST_DOTDOT: |
2650 | error = -ENOTEMPTY; | |
2651 | goto exit1; | |
2652 | case LAST_DOT: | |
2653 | error = -EINVAL; | |
2654 | goto exit1; | |
2655 | case LAST_ROOT: | |
2656 | error = -EBUSY; | |
2657 | goto exit1; | |
1da177e4 | 2658 | } |
0612d9fb OH |
2659 | |
2660 | nd.flags &= ~LOOKUP_PARENT; | |
2661 | ||
4ac91378 | 2662 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2663 | dentry = lookup_hash(&nd); |
1da177e4 | 2664 | error = PTR_ERR(dentry); |
6902d925 DH |
2665 | if (IS_ERR(dentry)) |
2666 | goto exit2; | |
e6bc45d6 TT |
2667 | if (!dentry->d_inode) { |
2668 | error = -ENOENT; | |
2669 | goto exit3; | |
2670 | } | |
0622753b DH |
2671 | error = mnt_want_write(nd.path.mnt); |
2672 | if (error) | |
2673 | goto exit3; | |
be6d3e56 KT |
2674 | error = security_path_rmdir(&nd.path, dentry); |
2675 | if (error) | |
2676 | goto exit4; | |
4ac91378 | 2677 | error = vfs_rmdir(nd.path.dentry->d_inode, dentry); |
be6d3e56 | 2678 | exit4: |
0622753b DH |
2679 | mnt_drop_write(nd.path.mnt); |
2680 | exit3: | |
6902d925 DH |
2681 | dput(dentry); |
2682 | exit2: | |
4ac91378 | 2683 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 | 2684 | exit1: |
1d957f9b | 2685 | path_put(&nd.path); |
1da177e4 LT |
2686 | putname(name); |
2687 | return error; | |
2688 | } | |
2689 | ||
3cdad428 | 2690 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
2691 | { |
2692 | return do_rmdir(AT_FDCWD, pathname); | |
2693 | } | |
2694 | ||
1da177e4 LT |
2695 | int vfs_unlink(struct inode *dir, struct dentry *dentry) |
2696 | { | |
2697 | int error = may_delete(dir, dentry, 0); | |
2698 | ||
2699 | if (error) | |
2700 | return error; | |
2701 | ||
acfa4380 | 2702 | if (!dir->i_op->unlink) |
1da177e4 LT |
2703 | return -EPERM; |
2704 | ||
1b1dcc1b | 2705 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2706 | if (d_mountpoint(dentry)) |
2707 | error = -EBUSY; | |
2708 | else { | |
2709 | error = security_inode_unlink(dir, dentry); | |
bec1052e | 2710 | if (!error) { |
1da177e4 | 2711 | error = dir->i_op->unlink(dir, dentry); |
bec1052e | 2712 | if (!error) |
d83c49f3 | 2713 | dont_mount(dentry); |
bec1052e | 2714 | } |
1da177e4 | 2715 | } |
1b1dcc1b | 2716 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2717 | |
2718 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
2719 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
ece95912 | 2720 | fsnotify_link_count(dentry->d_inode); |
e234f35c | 2721 | d_delete(dentry); |
1da177e4 | 2722 | } |
0eeca283 | 2723 | |
1da177e4 LT |
2724 | return error; |
2725 | } | |
2726 | ||
2727 | /* | |
2728 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 2729 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
2730 | * writeout happening, and we don't want to prevent access to the directory |
2731 | * while waiting on the I/O. | |
2732 | */ | |
5590ff0d | 2733 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 2734 | { |
2ad94ae6 AV |
2735 | int error; |
2736 | char *name; | |
1da177e4 LT |
2737 | struct dentry *dentry; |
2738 | struct nameidata nd; | |
2739 | struct inode *inode = NULL; | |
2740 | ||
2ad94ae6 | 2741 | error = user_path_parent(dfd, pathname, &nd, &name); |
1da177e4 | 2742 | if (error) |
2ad94ae6 AV |
2743 | return error; |
2744 | ||
1da177e4 LT |
2745 | error = -EISDIR; |
2746 | if (nd.last_type != LAST_NORM) | |
2747 | goto exit1; | |
0612d9fb OH |
2748 | |
2749 | nd.flags &= ~LOOKUP_PARENT; | |
2750 | ||
4ac91378 | 2751 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2752 | dentry = lookup_hash(&nd); |
1da177e4 LT |
2753 | error = PTR_ERR(dentry); |
2754 | if (!IS_ERR(dentry)) { | |
2755 | /* Why not before? Because we want correct error value */ | |
50338b88 TE |
2756 | if (nd.last.name[nd.last.len]) |
2757 | goto slashes; | |
1da177e4 | 2758 | inode = dentry->d_inode; |
50338b88 | 2759 | if (!inode) |
e6bc45d6 TT |
2760 | goto slashes; |
2761 | ihold(inode); | |
0622753b DH |
2762 | error = mnt_want_write(nd.path.mnt); |
2763 | if (error) | |
2764 | goto exit2; | |
be6d3e56 KT |
2765 | error = security_path_unlink(&nd.path, dentry); |
2766 | if (error) | |
2767 | goto exit3; | |
4ac91378 | 2768 | error = vfs_unlink(nd.path.dentry->d_inode, dentry); |
be6d3e56 | 2769 | exit3: |
0622753b | 2770 | mnt_drop_write(nd.path.mnt); |
1da177e4 LT |
2771 | exit2: |
2772 | dput(dentry); | |
2773 | } | |
4ac91378 | 2774 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 LT |
2775 | if (inode) |
2776 | iput(inode); /* truncate the inode here */ | |
2777 | exit1: | |
1d957f9b | 2778 | path_put(&nd.path); |
1da177e4 LT |
2779 | putname(name); |
2780 | return error; | |
2781 | ||
2782 | slashes: | |
2783 | error = !dentry->d_inode ? -ENOENT : | |
2784 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; | |
2785 | goto exit2; | |
2786 | } | |
2787 | ||
2e4d0924 | 2788 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
2789 | { |
2790 | if ((flag & ~AT_REMOVEDIR) != 0) | |
2791 | return -EINVAL; | |
2792 | ||
2793 | if (flag & AT_REMOVEDIR) | |
2794 | return do_rmdir(dfd, pathname); | |
2795 | ||
2796 | return do_unlinkat(dfd, pathname); | |
2797 | } | |
2798 | ||
3480b257 | 2799 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
2800 | { |
2801 | return do_unlinkat(AT_FDCWD, pathname); | |
2802 | } | |
2803 | ||
db2e747b | 2804 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 2805 | { |
a95164d9 | 2806 | int error = may_create(dir, dentry); |
1da177e4 LT |
2807 | |
2808 | if (error) | |
2809 | return error; | |
2810 | ||
acfa4380 | 2811 | if (!dir->i_op->symlink) |
1da177e4 LT |
2812 | return -EPERM; |
2813 | ||
2814 | error = security_inode_symlink(dir, dentry, oldname); | |
2815 | if (error) | |
2816 | return error; | |
2817 | ||
1da177e4 | 2818 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 2819 | if (!error) |
f38aa942 | 2820 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2821 | return error; |
2822 | } | |
2823 | ||
2e4d0924 HC |
2824 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
2825 | int, newdfd, const char __user *, newname) | |
1da177e4 | 2826 | { |
2ad94ae6 AV |
2827 | int error; |
2828 | char *from; | |
6902d925 | 2829 | struct dentry *dentry; |
dae6ad8f | 2830 | struct path path; |
1da177e4 LT |
2831 | |
2832 | from = getname(oldname); | |
2ad94ae6 | 2833 | if (IS_ERR(from)) |
1da177e4 | 2834 | return PTR_ERR(from); |
1da177e4 | 2835 | |
dae6ad8f | 2836 | dentry = user_path_create(newdfd, newname, &path, 0); |
6902d925 DH |
2837 | error = PTR_ERR(dentry); |
2838 | if (IS_ERR(dentry)) | |
dae6ad8f | 2839 | goto out_putname; |
6902d925 | 2840 | |
dae6ad8f | 2841 | error = mnt_want_write(path.mnt); |
75c3f29d DH |
2842 | if (error) |
2843 | goto out_dput; | |
dae6ad8f | 2844 | error = security_path_symlink(&path, dentry, from); |
be6d3e56 KT |
2845 | if (error) |
2846 | goto out_drop_write; | |
dae6ad8f | 2847 | error = vfs_symlink(path.dentry->d_inode, dentry, from); |
be6d3e56 | 2848 | out_drop_write: |
dae6ad8f | 2849 | mnt_drop_write(path.mnt); |
75c3f29d | 2850 | out_dput: |
6902d925 | 2851 | dput(dentry); |
dae6ad8f AV |
2852 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
2853 | path_put(&path); | |
6902d925 | 2854 | out_putname: |
1da177e4 LT |
2855 | putname(from); |
2856 | return error; | |
2857 | } | |
2858 | ||
3480b257 | 2859 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
2860 | { |
2861 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
2862 | } | |
2863 | ||
1da177e4 LT |
2864 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
2865 | { | |
2866 | struct inode *inode = old_dentry->d_inode; | |
2867 | int error; | |
2868 | ||
2869 | if (!inode) | |
2870 | return -ENOENT; | |
2871 | ||
a95164d9 | 2872 | error = may_create(dir, new_dentry); |
1da177e4 LT |
2873 | if (error) |
2874 | return error; | |
2875 | ||
2876 | if (dir->i_sb != inode->i_sb) | |
2877 | return -EXDEV; | |
2878 | ||
2879 | /* | |
2880 | * A link to an append-only or immutable file cannot be created. | |
2881 | */ | |
2882 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
2883 | return -EPERM; | |
acfa4380 | 2884 | if (!dir->i_op->link) |
1da177e4 | 2885 | return -EPERM; |
7e79eedb | 2886 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
2887 | return -EPERM; |
2888 | ||
2889 | error = security_inode_link(old_dentry, dir, new_dentry); | |
2890 | if (error) | |
2891 | return error; | |
2892 | ||
7e79eedb | 2893 | mutex_lock(&inode->i_mutex); |
aae8a97d AK |
2894 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
2895 | if (inode->i_nlink == 0) | |
2896 | error = -ENOENT; | |
2897 | else | |
2898 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
7e79eedb | 2899 | mutex_unlock(&inode->i_mutex); |
e31e14ec | 2900 | if (!error) |
7e79eedb | 2901 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
2902 | return error; |
2903 | } | |
2904 | ||
2905 | /* | |
2906 | * Hardlinks are often used in delicate situations. We avoid | |
2907 | * security-related surprises by not following symlinks on the | |
2908 | * newname. --KAB | |
2909 | * | |
2910 | * We don't follow them on the oldname either to be compatible | |
2911 | * with linux 2.0, and to avoid hard-linking to directories | |
2912 | * and other special files. --ADM | |
2913 | */ | |
2e4d0924 HC |
2914 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
2915 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
2916 | { |
2917 | struct dentry *new_dentry; | |
dae6ad8f | 2918 | struct path old_path, new_path; |
11a7b371 | 2919 | int how = 0; |
1da177e4 | 2920 | int error; |
1da177e4 | 2921 | |
11a7b371 | 2922 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
c04030e1 | 2923 | return -EINVAL; |
11a7b371 AK |
2924 | /* |
2925 | * To use null names we require CAP_DAC_READ_SEARCH | |
2926 | * This ensures that not everyone will be able to create | |
2927 | * handlink using the passed filedescriptor. | |
2928 | */ | |
2929 | if (flags & AT_EMPTY_PATH) { | |
2930 | if (!capable(CAP_DAC_READ_SEARCH)) | |
2931 | return -ENOENT; | |
2932 | how = LOOKUP_EMPTY; | |
2933 | } | |
2934 | ||
2935 | if (flags & AT_SYMLINK_FOLLOW) | |
2936 | how |= LOOKUP_FOLLOW; | |
c04030e1 | 2937 | |
11a7b371 | 2938 | error = user_path_at(olddfd, oldname, how, &old_path); |
1da177e4 | 2939 | if (error) |
2ad94ae6 AV |
2940 | return error; |
2941 | ||
dae6ad8f | 2942 | new_dentry = user_path_create(newdfd, newname, &new_path, 0); |
1da177e4 | 2943 | error = PTR_ERR(new_dentry); |
6902d925 | 2944 | if (IS_ERR(new_dentry)) |
dae6ad8f AV |
2945 | goto out; |
2946 | ||
2947 | error = -EXDEV; | |
2948 | if (old_path.mnt != new_path.mnt) | |
2949 | goto out_dput; | |
2950 | error = mnt_want_write(new_path.mnt); | |
75c3f29d DH |
2951 | if (error) |
2952 | goto out_dput; | |
dae6ad8f | 2953 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
be6d3e56 KT |
2954 | if (error) |
2955 | goto out_drop_write; | |
dae6ad8f | 2956 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); |
be6d3e56 | 2957 | out_drop_write: |
dae6ad8f | 2958 | mnt_drop_write(new_path.mnt); |
75c3f29d | 2959 | out_dput: |
6902d925 | 2960 | dput(new_dentry); |
dae6ad8f AV |
2961 | mutex_unlock(&new_path.dentry->d_inode->i_mutex); |
2962 | path_put(&new_path); | |
1da177e4 | 2963 | out: |
2d8f3038 | 2964 | path_put(&old_path); |
1da177e4 LT |
2965 | |
2966 | return error; | |
2967 | } | |
2968 | ||
3480b257 | 2969 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 2970 | { |
c04030e1 | 2971 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
2972 | } |
2973 | ||
1da177e4 LT |
2974 | /* |
2975 | * The worst of all namespace operations - renaming directory. "Perverted" | |
2976 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
2977 | * Problems: | |
2978 | * a) we can get into loop creation. Check is done in is_subdir(). | |
2979 | * b) race potential - two innocent renames can create a loop together. | |
2980 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 2981 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 LT |
2982 | * story. |
2983 | * c) we have to lock _three_ objects - parents and victim (if it exists). | |
1b1dcc1b | 2984 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
2985 | * whether the target exists). Solution: try to be smart with locking |
2986 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 2987 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
2988 | * move will be locked. Thus we can rank directories by the tree |
2989 | * (ancestors first) and rank all non-directories after them. | |
2990 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 2991 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
2992 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
2993 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
2994 | * we'd better make sure that there's no link(2) for them. | |
e4eaac06 | 2995 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
1b1dcc1b | 2996 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 2997 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
c41b20e7 | 2998 | * ->i_mutex on parents, which works but leads to some truly excessive |
1da177e4 LT |
2999 | * locking]. |
3000 | */ | |
75c96f85 AB |
3001 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
3002 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
3003 | { |
3004 | int error = 0; | |
9055cba7 | 3005 | struct inode *target = new_dentry->d_inode; |
1da177e4 LT |
3006 | |
3007 | /* | |
3008 | * If we are going to change the parent - check write permissions, | |
3009 | * we'll need to flip '..'. | |
3010 | */ | |
3011 | if (new_dir != old_dir) { | |
f419a2e3 | 3012 | error = inode_permission(old_dentry->d_inode, MAY_WRITE); |
1da177e4 LT |
3013 | if (error) |
3014 | return error; | |
3015 | } | |
3016 | ||
3017 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
3018 | if (error) | |
3019 | return error; | |
3020 | ||
1d2ef590 | 3021 | dget(new_dentry); |
d83c49f3 | 3022 | if (target) |
1b1dcc1b | 3023 | mutex_lock(&target->i_mutex); |
9055cba7 SW |
3024 | |
3025 | error = -EBUSY; | |
3026 | if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) | |
3027 | goto out; | |
3028 | ||
3cebde24 SW |
3029 | if (target) |
3030 | shrink_dcache_parent(new_dentry); | |
9055cba7 SW |
3031 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
3032 | if (error) | |
3033 | goto out; | |
3034 | ||
1da177e4 | 3035 | if (target) { |
9055cba7 SW |
3036 | target->i_flags |= S_DEAD; |
3037 | dont_mount(new_dentry); | |
1da177e4 | 3038 | } |
9055cba7 SW |
3039 | out: |
3040 | if (target) | |
3041 | mutex_unlock(&target->i_mutex); | |
1d2ef590 | 3042 | dput(new_dentry); |
e31e14ec | 3043 | if (!error) |
349457cc MF |
3044 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
3045 | d_move(old_dentry,new_dentry); | |
1da177e4 LT |
3046 | return error; |
3047 | } | |
3048 | ||
75c96f85 AB |
3049 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
3050 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 | 3051 | { |
51892bbb | 3052 | struct inode *target = new_dentry->d_inode; |
1da177e4 LT |
3053 | int error; |
3054 | ||
3055 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
3056 | if (error) | |
3057 | return error; | |
3058 | ||
3059 | dget(new_dentry); | |
1da177e4 | 3060 | if (target) |
1b1dcc1b | 3061 | mutex_lock(&target->i_mutex); |
51892bbb SW |
3062 | |
3063 | error = -EBUSY; | |
1da177e4 | 3064 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
51892bbb SW |
3065 | goto out; |
3066 | ||
3067 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
3068 | if (error) | |
3069 | goto out; | |
3070 | ||
3071 | if (target) | |
3072 | dont_mount(new_dentry); | |
3073 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) | |
3074 | d_move(old_dentry, new_dentry); | |
3075 | out: | |
1da177e4 | 3076 | if (target) |
1b1dcc1b | 3077 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
3078 | dput(new_dentry); |
3079 | return error; | |
3080 | } | |
3081 | ||
3082 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, | |
3083 | struct inode *new_dir, struct dentry *new_dentry) | |
3084 | { | |
3085 | int error; | |
3086 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); | |
59b0df21 | 3087 | const unsigned char *old_name; |
1da177e4 LT |
3088 | |
3089 | if (old_dentry->d_inode == new_dentry->d_inode) | |
3090 | return 0; | |
3091 | ||
3092 | error = may_delete(old_dir, old_dentry, is_dir); | |
3093 | if (error) | |
3094 | return error; | |
3095 | ||
3096 | if (!new_dentry->d_inode) | |
a95164d9 | 3097 | error = may_create(new_dir, new_dentry); |
1da177e4 LT |
3098 | else |
3099 | error = may_delete(new_dir, new_dentry, is_dir); | |
3100 | if (error) | |
3101 | return error; | |
3102 | ||
acfa4380 | 3103 | if (!old_dir->i_op->rename) |
1da177e4 LT |
3104 | return -EPERM; |
3105 | ||
0eeca283 RL |
3106 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
3107 | ||
1da177e4 LT |
3108 | if (is_dir) |
3109 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); | |
3110 | else | |
3111 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); | |
123df294 AV |
3112 | if (!error) |
3113 | fsnotify_move(old_dir, new_dir, old_name, is_dir, | |
5a190ae6 | 3114 | new_dentry->d_inode, old_dentry); |
0eeca283 RL |
3115 | fsnotify_oldname_free(old_name); |
3116 | ||
1da177e4 LT |
3117 | return error; |
3118 | } | |
3119 | ||
2e4d0924 HC |
3120 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
3121 | int, newdfd, const char __user *, newname) | |
1da177e4 | 3122 | { |
2ad94ae6 AV |
3123 | struct dentry *old_dir, *new_dir; |
3124 | struct dentry *old_dentry, *new_dentry; | |
3125 | struct dentry *trap; | |
1da177e4 | 3126 | struct nameidata oldnd, newnd; |
2ad94ae6 AV |
3127 | char *from; |
3128 | char *to; | |
3129 | int error; | |
1da177e4 | 3130 | |
2ad94ae6 | 3131 | error = user_path_parent(olddfd, oldname, &oldnd, &from); |
1da177e4 LT |
3132 | if (error) |
3133 | goto exit; | |
3134 | ||
2ad94ae6 | 3135 | error = user_path_parent(newdfd, newname, &newnd, &to); |
1da177e4 LT |
3136 | if (error) |
3137 | goto exit1; | |
3138 | ||
3139 | error = -EXDEV; | |
4ac91378 | 3140 | if (oldnd.path.mnt != newnd.path.mnt) |
1da177e4 LT |
3141 | goto exit2; |
3142 | ||
4ac91378 | 3143 | old_dir = oldnd.path.dentry; |
1da177e4 LT |
3144 | error = -EBUSY; |
3145 | if (oldnd.last_type != LAST_NORM) | |
3146 | goto exit2; | |
3147 | ||
4ac91378 | 3148 | new_dir = newnd.path.dentry; |
1da177e4 LT |
3149 | if (newnd.last_type != LAST_NORM) |
3150 | goto exit2; | |
3151 | ||
0612d9fb OH |
3152 | oldnd.flags &= ~LOOKUP_PARENT; |
3153 | newnd.flags &= ~LOOKUP_PARENT; | |
4e9ed2f8 | 3154 | newnd.flags |= LOOKUP_RENAME_TARGET; |
0612d9fb | 3155 | |
1da177e4 LT |
3156 | trap = lock_rename(new_dir, old_dir); |
3157 | ||
49705b77 | 3158 | old_dentry = lookup_hash(&oldnd); |
1da177e4 LT |
3159 | error = PTR_ERR(old_dentry); |
3160 | if (IS_ERR(old_dentry)) | |
3161 | goto exit3; | |
3162 | /* source must exist */ | |
3163 | error = -ENOENT; | |
3164 | if (!old_dentry->d_inode) | |
3165 | goto exit4; | |
3166 | /* unless the source is a directory trailing slashes give -ENOTDIR */ | |
3167 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { | |
3168 | error = -ENOTDIR; | |
3169 | if (oldnd.last.name[oldnd.last.len]) | |
3170 | goto exit4; | |
3171 | if (newnd.last.name[newnd.last.len]) | |
3172 | goto exit4; | |
3173 | } | |
3174 | /* source should not be ancestor of target */ | |
3175 | error = -EINVAL; | |
3176 | if (old_dentry == trap) | |
3177 | goto exit4; | |
49705b77 | 3178 | new_dentry = lookup_hash(&newnd); |
1da177e4 LT |
3179 | error = PTR_ERR(new_dentry); |
3180 | if (IS_ERR(new_dentry)) | |
3181 | goto exit4; | |
3182 | /* target should not be an ancestor of source */ | |
3183 | error = -ENOTEMPTY; | |
3184 | if (new_dentry == trap) | |
3185 | goto exit5; | |
3186 | ||
9079b1eb DH |
3187 | error = mnt_want_write(oldnd.path.mnt); |
3188 | if (error) | |
3189 | goto exit5; | |
be6d3e56 KT |
3190 | error = security_path_rename(&oldnd.path, old_dentry, |
3191 | &newnd.path, new_dentry); | |
3192 | if (error) | |
3193 | goto exit6; | |
1da177e4 LT |
3194 | error = vfs_rename(old_dir->d_inode, old_dentry, |
3195 | new_dir->d_inode, new_dentry); | |
be6d3e56 | 3196 | exit6: |
9079b1eb | 3197 | mnt_drop_write(oldnd.path.mnt); |
1da177e4 LT |
3198 | exit5: |
3199 | dput(new_dentry); | |
3200 | exit4: | |
3201 | dput(old_dentry); | |
3202 | exit3: | |
3203 | unlock_rename(new_dir, old_dir); | |
3204 | exit2: | |
1d957f9b | 3205 | path_put(&newnd.path); |
2ad94ae6 | 3206 | putname(to); |
1da177e4 | 3207 | exit1: |
1d957f9b | 3208 | path_put(&oldnd.path); |
1da177e4 | 3209 | putname(from); |
2ad94ae6 | 3210 | exit: |
1da177e4 LT |
3211 | return error; |
3212 | } | |
3213 | ||
a26eab24 | 3214 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
3215 | { |
3216 | return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); | |
3217 | } | |
3218 | ||
1da177e4 LT |
3219 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
3220 | { | |
3221 | int len; | |
3222 | ||
3223 | len = PTR_ERR(link); | |
3224 | if (IS_ERR(link)) | |
3225 | goto out; | |
3226 | ||
3227 | len = strlen(link); | |
3228 | if (len > (unsigned) buflen) | |
3229 | len = buflen; | |
3230 | if (copy_to_user(buffer, link, len)) | |
3231 | len = -EFAULT; | |
3232 | out: | |
3233 | return len; | |
3234 | } | |
3235 | ||
3236 | /* | |
3237 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
3238 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
3239 | * using) it for any given inode is up to filesystem. | |
3240 | */ | |
3241 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
3242 | { | |
3243 | struct nameidata nd; | |
cc314eef | 3244 | void *cookie; |
694a1764 | 3245 | int res; |
cc314eef | 3246 | |
1da177e4 | 3247 | nd.depth = 0; |
cc314eef | 3248 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
694a1764 MS |
3249 | if (IS_ERR(cookie)) |
3250 | return PTR_ERR(cookie); | |
3251 | ||
3252 | res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); | |
3253 | if (dentry->d_inode->i_op->put_link) | |
3254 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); | |
3255 | return res; | |
1da177e4 LT |
3256 | } |
3257 | ||
3258 | int vfs_follow_link(struct nameidata *nd, const char *link) | |
3259 | { | |
3260 | return __vfs_follow_link(nd, link); | |
3261 | } | |
3262 | ||
3263 | /* get the link contents into pagecache */ | |
3264 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
3265 | { | |
ebd09abb DG |
3266 | char *kaddr; |
3267 | struct page *page; | |
1da177e4 | 3268 | struct address_space *mapping = dentry->d_inode->i_mapping; |
090d2b18 | 3269 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 3270 | if (IS_ERR(page)) |
6fe6900e | 3271 | return (char*)page; |
1da177e4 | 3272 | *ppage = page; |
ebd09abb DG |
3273 | kaddr = kmap(page); |
3274 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); | |
3275 | return kaddr; | |
1da177e4 LT |
3276 | } |
3277 | ||
3278 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
3279 | { | |
3280 | struct page *page = NULL; | |
3281 | char *s = page_getlink(dentry, &page); | |
3282 | int res = vfs_readlink(dentry,buffer,buflen,s); | |
3283 | if (page) { | |
3284 | kunmap(page); | |
3285 | page_cache_release(page); | |
3286 | } | |
3287 | return res; | |
3288 | } | |
3289 | ||
cc314eef | 3290 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 3291 | { |
cc314eef | 3292 | struct page *page = NULL; |
1da177e4 | 3293 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 3294 | return page; |
1da177e4 LT |
3295 | } |
3296 | ||
cc314eef | 3297 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 3298 | { |
cc314eef LT |
3299 | struct page *page = cookie; |
3300 | ||
3301 | if (page) { | |
1da177e4 LT |
3302 | kunmap(page); |
3303 | page_cache_release(page); | |
1da177e4 LT |
3304 | } |
3305 | } | |
3306 | ||
54566b2c NP |
3307 | /* |
3308 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
3309 | */ | |
3310 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
3311 | { |
3312 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 3313 | struct page *page; |
afddba49 | 3314 | void *fsdata; |
beb497ab | 3315 | int err; |
1da177e4 | 3316 | char *kaddr; |
54566b2c NP |
3317 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
3318 | if (nofs) | |
3319 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 3320 | |
7e53cac4 | 3321 | retry: |
afddba49 | 3322 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 3323 | flags, &page, &fsdata); |
1da177e4 | 3324 | if (err) |
afddba49 NP |
3325 | goto fail; |
3326 | ||
1da177e4 LT |
3327 | kaddr = kmap_atomic(page, KM_USER0); |
3328 | memcpy(kaddr, symname, len-1); | |
3329 | kunmap_atomic(kaddr, KM_USER0); | |
afddba49 NP |
3330 | |
3331 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
3332 | page, fsdata); | |
1da177e4 LT |
3333 | if (err < 0) |
3334 | goto fail; | |
afddba49 NP |
3335 | if (err < len-1) |
3336 | goto retry; | |
3337 | ||
1da177e4 LT |
3338 | mark_inode_dirty(inode); |
3339 | return 0; | |
1da177e4 LT |
3340 | fail: |
3341 | return err; | |
3342 | } | |
3343 | ||
0adb25d2 KK |
3344 | int page_symlink(struct inode *inode, const char *symname, int len) |
3345 | { | |
3346 | return __page_symlink(inode, symname, len, | |
54566b2c | 3347 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
0adb25d2 KK |
3348 | } |
3349 | ||
92e1d5be | 3350 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
3351 | .readlink = generic_readlink, |
3352 | .follow_link = page_follow_link_light, | |
3353 | .put_link = page_put_link, | |
3354 | }; | |
3355 | ||
2d8f3038 | 3356 | EXPORT_SYMBOL(user_path_at); |
cc53ce53 | 3357 | EXPORT_SYMBOL(follow_down_one); |
1da177e4 LT |
3358 | EXPORT_SYMBOL(follow_down); |
3359 | EXPORT_SYMBOL(follow_up); | |
3360 | EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ | |
3361 | EXPORT_SYMBOL(getname); | |
3362 | EXPORT_SYMBOL(lock_rename); | |
1da177e4 LT |
3363 | EXPORT_SYMBOL(lookup_one_len); |
3364 | EXPORT_SYMBOL(page_follow_link_light); | |
3365 | EXPORT_SYMBOL(page_put_link); | |
3366 | EXPORT_SYMBOL(page_readlink); | |
0adb25d2 | 3367 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 LT |
3368 | EXPORT_SYMBOL(page_symlink); |
3369 | EXPORT_SYMBOL(page_symlink_inode_operations); | |
d1811465 | 3370 | EXPORT_SYMBOL(kern_path); |
16f18200 | 3371 | EXPORT_SYMBOL(vfs_path_lookup); |
f419a2e3 | 3372 | EXPORT_SYMBOL(inode_permission); |
1da177e4 LT |
3373 | EXPORT_SYMBOL(unlock_rename); |
3374 | EXPORT_SYMBOL(vfs_create); | |
3375 | EXPORT_SYMBOL(vfs_follow_link); | |
3376 | EXPORT_SYMBOL(vfs_link); | |
3377 | EXPORT_SYMBOL(vfs_mkdir); | |
3378 | EXPORT_SYMBOL(vfs_mknod); | |
3379 | EXPORT_SYMBOL(generic_permission); | |
3380 | EXPORT_SYMBOL(vfs_readlink); | |
3381 | EXPORT_SYMBOL(vfs_rename); | |
3382 | EXPORT_SYMBOL(vfs_rmdir); | |
3383 | EXPORT_SYMBOL(vfs_symlink); | |
3384 | EXPORT_SYMBOL(vfs_unlink); | |
3385 | EXPORT_SYMBOL(dentry_unhash); | |
3386 | EXPORT_SYMBOL(generic_readlink); |