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 LT |
223 | /* |
224 | * This does basic POSIX ACL 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 | /* | |
274 | * Do the basic POSIX ACL permission checks. | |
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. | |
338 | */ | |
f419a2e3 | 339 | int inode_permission(struct inode *inode, int mask) |
1da177e4 | 340 | { |
e6305c43 | 341 | int retval; |
1da177e4 | 342 | |
3ddcd056 | 343 | if (unlikely(mask & MAY_WRITE)) { |
22590e41 | 344 | umode_t mode = inode->i_mode; |
1da177e4 LT |
345 | |
346 | /* | |
347 | * Nobody gets write access to a read-only fs. | |
348 | */ | |
349 | if (IS_RDONLY(inode) && | |
350 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
351 | return -EROFS; | |
352 | ||
353 | /* | |
354 | * Nobody gets write access to an immutable file. | |
355 | */ | |
356 | if (IS_IMMUTABLE(inode)) | |
357 | return -EACCES; | |
358 | } | |
359 | ||
3ddcd056 | 360 | retval = do_inode_permission(inode, mask); |
1da177e4 LT |
361 | if (retval) |
362 | return retval; | |
363 | ||
08ce5f16 SH |
364 | retval = devcgroup_inode_permission(inode, mask); |
365 | if (retval) | |
366 | return retval; | |
367 | ||
d09ca739 | 368 | return security_inode_permission(inode, mask); |
1da177e4 LT |
369 | } |
370 | ||
5dd784d0 JB |
371 | /** |
372 | * path_get - get a reference to a path | |
373 | * @path: path to get the reference to | |
374 | * | |
375 | * Given a path increment the reference count to the dentry and the vfsmount. | |
376 | */ | |
377 | void path_get(struct path *path) | |
378 | { | |
379 | mntget(path->mnt); | |
380 | dget(path->dentry); | |
381 | } | |
382 | EXPORT_SYMBOL(path_get); | |
383 | ||
1d957f9b JB |
384 | /** |
385 | * path_put - put a reference to a path | |
386 | * @path: path to put the reference to | |
387 | * | |
388 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
389 | */ | |
390 | void path_put(struct path *path) | |
1da177e4 | 391 | { |
1d957f9b JB |
392 | dput(path->dentry); |
393 | mntput(path->mnt); | |
1da177e4 | 394 | } |
1d957f9b | 395 | EXPORT_SYMBOL(path_put); |
1da177e4 | 396 | |
19660af7 | 397 | /* |
31e6b01f | 398 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
19660af7 AV |
399 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
400 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab | |
401 | * normal reference counts on dentries and vfsmounts to transition to rcu-walk | |
402 | * mode. Refcounts are grabbed at the last known good point before rcu-walk | |
403 | * got stuck, so ref-walk may continue from there. If this is not successful | |
404 | * (eg. a seqcount has changed), then failure is returned and it's up to caller | |
405 | * to restart the path walk from the beginning in ref-walk mode. | |
31e6b01f | 406 | */ |
31e6b01f NP |
407 | |
408 | /** | |
19660af7 AV |
409 | * unlazy_walk - try to switch to ref-walk mode. |
410 | * @nd: nameidata pathwalk data | |
411 | * @dentry: child of nd->path.dentry or NULL | |
39191628 | 412 | * Returns: 0 on success, -ECHILD on failure |
31e6b01f | 413 | * |
19660af7 AV |
414 | * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry |
415 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on | |
416 | * @nd or NULL. Must be called from rcu-walk context. | |
31e6b01f | 417 | */ |
19660af7 | 418 | static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) |
31e6b01f NP |
419 | { |
420 | struct fs_struct *fs = current->fs; | |
421 | struct dentry *parent = nd->path.dentry; | |
5b6ca027 | 422 | int want_root = 0; |
31e6b01f NP |
423 | |
424 | BUG_ON(!(nd->flags & LOOKUP_RCU)); | |
5b6ca027 AV |
425 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
426 | want_root = 1; | |
31e6b01f NP |
427 | spin_lock(&fs->lock); |
428 | if (nd->root.mnt != fs->root.mnt || | |
429 | nd->root.dentry != fs->root.dentry) | |
430 | goto err_root; | |
431 | } | |
432 | spin_lock(&parent->d_lock); | |
19660af7 AV |
433 | if (!dentry) { |
434 | if (!__d_rcu_to_refcount(parent, nd->seq)) | |
435 | goto err_parent; | |
436 | BUG_ON(nd->inode != parent->d_inode); | |
437 | } else { | |
94c0d4ec AV |
438 | if (dentry->d_parent != parent) |
439 | goto err_parent; | |
19660af7 AV |
440 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
441 | if (!__d_rcu_to_refcount(dentry, nd->seq)) | |
442 | goto err_child; | |
443 | /* | |
444 | * If the sequence check on the child dentry passed, then | |
445 | * the child has not been removed from its parent. This | |
446 | * means the parent dentry must be valid and able to take | |
447 | * a reference at this point. | |
448 | */ | |
449 | BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); | |
450 | BUG_ON(!parent->d_count); | |
451 | parent->d_count++; | |
452 | spin_unlock(&dentry->d_lock); | |
453 | } | |
31e6b01f | 454 | spin_unlock(&parent->d_lock); |
5b6ca027 | 455 | if (want_root) { |
31e6b01f NP |
456 | path_get(&nd->root); |
457 | spin_unlock(&fs->lock); | |
458 | } | |
459 | mntget(nd->path.mnt); | |
460 | ||
461 | rcu_read_unlock(); | |
462 | br_read_unlock(vfsmount_lock); | |
463 | nd->flags &= ~LOOKUP_RCU; | |
464 | return 0; | |
19660af7 AV |
465 | |
466 | err_child: | |
31e6b01f | 467 | spin_unlock(&dentry->d_lock); |
19660af7 | 468 | err_parent: |
31e6b01f NP |
469 | spin_unlock(&parent->d_lock); |
470 | err_root: | |
5b6ca027 | 471 | if (want_root) |
31e6b01f NP |
472 | spin_unlock(&fs->lock); |
473 | return -ECHILD; | |
474 | } | |
475 | ||
834f2a4a TM |
476 | /** |
477 | * release_open_intent - free up open intent resources | |
478 | * @nd: pointer to nameidata | |
479 | */ | |
480 | void release_open_intent(struct nameidata *nd) | |
481 | { | |
2dab5974 LT |
482 | struct file *file = nd->intent.open.file; |
483 | ||
484 | if (file && !IS_ERR(file)) { | |
485 | if (file->f_path.dentry == NULL) | |
486 | put_filp(file); | |
487 | else | |
488 | fput(file); | |
489 | } | |
834f2a4a TM |
490 | } |
491 | ||
f60aef7e | 492 | static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) |
34286d66 | 493 | { |
f60aef7e | 494 | return dentry->d_op->d_revalidate(dentry, nd); |
34286d66 NP |
495 | } |
496 | ||
9f1fafee AV |
497 | /** |
498 | * complete_walk - successful completion of path walk | |
499 | * @nd: pointer nameidata | |
39159de2 | 500 | * |
9f1fafee AV |
501 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
502 | * Revalidate the final result, unless we'd already done that during | |
503 | * the path walk or the filesystem doesn't ask for it. Return 0 on | |
504 | * success, -error on failure. In case of failure caller does not | |
505 | * need to drop nd->path. | |
39159de2 | 506 | */ |
9f1fafee | 507 | static int complete_walk(struct nameidata *nd) |
39159de2 | 508 | { |
16c2cd71 | 509 | struct dentry *dentry = nd->path.dentry; |
39159de2 | 510 | int status; |
39159de2 | 511 | |
9f1fafee AV |
512 | if (nd->flags & LOOKUP_RCU) { |
513 | nd->flags &= ~LOOKUP_RCU; | |
514 | if (!(nd->flags & LOOKUP_ROOT)) | |
515 | nd->root.mnt = NULL; | |
516 | spin_lock(&dentry->d_lock); | |
517 | if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { | |
518 | spin_unlock(&dentry->d_lock); | |
519 | rcu_read_unlock(); | |
520 | br_read_unlock(vfsmount_lock); | |
521 | return -ECHILD; | |
522 | } | |
523 | BUG_ON(nd->inode != dentry->d_inode); | |
524 | spin_unlock(&dentry->d_lock); | |
525 | mntget(nd->path.mnt); | |
526 | rcu_read_unlock(); | |
527 | br_read_unlock(vfsmount_lock); | |
528 | } | |
529 | ||
16c2cd71 AV |
530 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
531 | return 0; | |
532 | ||
533 | if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) | |
39159de2 JL |
534 | return 0; |
535 | ||
16c2cd71 AV |
536 | if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) |
537 | return 0; | |
538 | ||
539 | /* Note: we do not d_invalidate() */ | |
34286d66 | 540 | status = d_revalidate(dentry, nd); |
39159de2 JL |
541 | if (status > 0) |
542 | return 0; | |
543 | ||
16c2cd71 | 544 | if (!status) |
39159de2 | 545 | status = -ESTALE; |
16c2cd71 | 546 | |
9f1fafee | 547 | path_put(&nd->path); |
39159de2 JL |
548 | return status; |
549 | } | |
550 | ||
2a737871 AV |
551 | static __always_inline void set_root(struct nameidata *nd) |
552 | { | |
f7ad3c6b MS |
553 | if (!nd->root.mnt) |
554 | get_fs_root(current->fs, &nd->root); | |
2a737871 AV |
555 | } |
556 | ||
6de88d72 AV |
557 | static int link_path_walk(const char *, struct nameidata *); |
558 | ||
31e6b01f NP |
559 | static __always_inline void set_root_rcu(struct nameidata *nd) |
560 | { | |
561 | if (!nd->root.mnt) { | |
562 | struct fs_struct *fs = current->fs; | |
c28cc364 NP |
563 | unsigned seq; |
564 | ||
565 | do { | |
566 | seq = read_seqcount_begin(&fs->seq); | |
567 | nd->root = fs->root; | |
c1530019 | 568 | nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); |
c28cc364 | 569 | } while (read_seqcount_retry(&fs->seq, seq)); |
31e6b01f NP |
570 | } |
571 | } | |
572 | ||
f1662356 | 573 | static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
1da177e4 | 574 | { |
31e6b01f NP |
575 | int ret; |
576 | ||
1da177e4 LT |
577 | if (IS_ERR(link)) |
578 | goto fail; | |
579 | ||
580 | if (*link == '/') { | |
2a737871 | 581 | set_root(nd); |
1d957f9b | 582 | path_put(&nd->path); |
2a737871 AV |
583 | nd->path = nd->root; |
584 | path_get(&nd->root); | |
16c2cd71 | 585 | nd->flags |= LOOKUP_JUMPED; |
1da177e4 | 586 | } |
31e6b01f | 587 | nd->inode = nd->path.dentry->d_inode; |
b4091d5f | 588 | |
31e6b01f NP |
589 | ret = link_path_walk(link, nd); |
590 | return ret; | |
1da177e4 | 591 | fail: |
1d957f9b | 592 | path_put(&nd->path); |
1da177e4 LT |
593 | return PTR_ERR(link); |
594 | } | |
595 | ||
1d957f9b | 596 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
597 | { |
598 | dput(path->dentry); | |
4ac91378 | 599 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
600 | mntput(path->mnt); |
601 | } | |
602 | ||
7b9337aa NP |
603 | static inline void path_to_nameidata(const struct path *path, |
604 | struct nameidata *nd) | |
051d3812 | 605 | { |
31e6b01f NP |
606 | if (!(nd->flags & LOOKUP_RCU)) { |
607 | dput(nd->path.dentry); | |
608 | if (nd->path.mnt != path->mnt) | |
609 | mntput(nd->path.mnt); | |
9a229683 | 610 | } |
31e6b01f | 611 | nd->path.mnt = path->mnt; |
4ac91378 | 612 | nd->path.dentry = path->dentry; |
051d3812 IK |
613 | } |
614 | ||
574197e0 AV |
615 | static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) |
616 | { | |
617 | struct inode *inode = link->dentry->d_inode; | |
618 | if (!IS_ERR(cookie) && inode->i_op->put_link) | |
619 | inode->i_op->put_link(link->dentry, nd, cookie); | |
620 | path_put(link); | |
621 | } | |
622 | ||
def4af30 | 623 | static __always_inline int |
574197e0 | 624 | follow_link(struct path *link, struct nameidata *nd, void **p) |
1da177e4 LT |
625 | { |
626 | int error; | |
7b9337aa | 627 | struct dentry *dentry = link->dentry; |
1da177e4 | 628 | |
844a3917 AV |
629 | BUG_ON(nd->flags & LOOKUP_RCU); |
630 | ||
0e794589 AV |
631 | if (link->mnt == nd->path.mnt) |
632 | mntget(link->mnt); | |
633 | ||
574197e0 AV |
634 | if (unlikely(current->total_link_count >= 40)) { |
635 | *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ | |
574197e0 AV |
636 | path_put(&nd->path); |
637 | return -ELOOP; | |
638 | } | |
639 | cond_resched(); | |
640 | current->total_link_count++; | |
641 | ||
7b9337aa | 642 | touch_atime(link->mnt, dentry); |
1da177e4 | 643 | nd_set_link(nd, NULL); |
cd4e91d3 | 644 | |
36f3b4f6 AV |
645 | error = security_inode_follow_link(link->dentry, nd); |
646 | if (error) { | |
647 | *p = ERR_PTR(error); /* no ->put_link(), please */ | |
648 | path_put(&nd->path); | |
649 | return error; | |
650 | } | |
651 | ||
86acdca1 | 652 | nd->last_type = LAST_BIND; |
def4af30 AV |
653 | *p = dentry->d_inode->i_op->follow_link(dentry, nd); |
654 | error = PTR_ERR(*p); | |
655 | if (!IS_ERR(*p)) { | |
1da177e4 | 656 | char *s = nd_get_link(nd); |
cc314eef | 657 | error = 0; |
1da177e4 LT |
658 | if (s) |
659 | error = __vfs_follow_link(nd, s); | |
bcda7652 | 660 | else if (nd->last_type == LAST_BIND) { |
16c2cd71 | 661 | nd->flags |= LOOKUP_JUMPED; |
b21041d0 AV |
662 | nd->inode = nd->path.dentry->d_inode; |
663 | if (nd->inode->i_op->follow_link) { | |
bcda7652 AV |
664 | /* stepped on a _really_ weird one */ |
665 | path_put(&nd->path); | |
666 | error = -ELOOP; | |
667 | } | |
668 | } | |
1da177e4 | 669 | } |
1da177e4 LT |
670 | return error; |
671 | } | |
672 | ||
31e6b01f NP |
673 | static int follow_up_rcu(struct path *path) |
674 | { | |
675 | struct vfsmount *parent; | |
676 | struct dentry *mountpoint; | |
677 | ||
678 | parent = path->mnt->mnt_parent; | |
679 | if (parent == path->mnt) | |
680 | return 0; | |
681 | mountpoint = path->mnt->mnt_mountpoint; | |
682 | path->dentry = mountpoint; | |
683 | path->mnt = parent; | |
684 | return 1; | |
685 | } | |
686 | ||
bab77ebf | 687 | int follow_up(struct path *path) |
1da177e4 LT |
688 | { |
689 | struct vfsmount *parent; | |
690 | struct dentry *mountpoint; | |
99b7db7b NP |
691 | |
692 | br_read_lock(vfsmount_lock); | |
bab77ebf AV |
693 | parent = path->mnt->mnt_parent; |
694 | if (parent == path->mnt) { | |
99b7db7b | 695 | br_read_unlock(vfsmount_lock); |
1da177e4 LT |
696 | return 0; |
697 | } | |
698 | mntget(parent); | |
bab77ebf | 699 | mountpoint = dget(path->mnt->mnt_mountpoint); |
99b7db7b | 700 | br_read_unlock(vfsmount_lock); |
bab77ebf AV |
701 | dput(path->dentry); |
702 | path->dentry = mountpoint; | |
703 | mntput(path->mnt); | |
704 | path->mnt = parent; | |
1da177e4 LT |
705 | return 1; |
706 | } | |
707 | ||
b5c84bf6 | 708 | /* |
9875cf80 DH |
709 | * Perform an automount |
710 | * - return -EISDIR to tell follow_managed() to stop and return the path we | |
711 | * were called with. | |
1da177e4 | 712 | */ |
9875cf80 DH |
713 | static int follow_automount(struct path *path, unsigned flags, |
714 | bool *need_mntput) | |
31e6b01f | 715 | { |
9875cf80 | 716 | struct vfsmount *mnt; |
ea5b778a | 717 | int err; |
9875cf80 DH |
718 | |
719 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) | |
720 | return -EREMOTE; | |
721 | ||
0ec26fd0 MS |
722 | /* We don't want to mount if someone's just doing a stat - |
723 | * unless they're stat'ing a directory and appended a '/' to | |
724 | * the name. | |
725 | * | |
726 | * We do, however, want to mount if someone wants to open or | |
727 | * create a file of any type under the mountpoint, wants to | |
728 | * traverse through the mountpoint or wants to open the | |
729 | * mounted directory. Also, autofs may mark negative dentries | |
730 | * as being automount points. These will need the attentions | |
731 | * of the daemon to instantiate them before they can be used. | |
9875cf80 | 732 | */ |
0ec26fd0 | 733 | if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
d94c177b | 734 | LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && |
0ec26fd0 MS |
735 | path->dentry->d_inode) |
736 | return -EISDIR; | |
737 | ||
9875cf80 DH |
738 | current->total_link_count++; |
739 | if (current->total_link_count >= 40) | |
740 | return -ELOOP; | |
741 | ||
742 | mnt = path->dentry->d_op->d_automount(path); | |
743 | if (IS_ERR(mnt)) { | |
744 | /* | |
745 | * The filesystem is allowed to return -EISDIR here to indicate | |
746 | * it doesn't want to automount. For instance, autofs would do | |
747 | * this so that its userspace daemon can mount on this dentry. | |
748 | * | |
749 | * However, we can only permit this if it's a terminal point in | |
750 | * the path being looked up; if it wasn't then the remainder of | |
751 | * the path is inaccessible and we should say so. | |
752 | */ | |
49084c3b | 753 | if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) |
9875cf80 DH |
754 | return -EREMOTE; |
755 | return PTR_ERR(mnt); | |
31e6b01f | 756 | } |
ea5b778a | 757 | |
9875cf80 DH |
758 | if (!mnt) /* mount collision */ |
759 | return 0; | |
31e6b01f | 760 | |
8aef1884 AV |
761 | if (!*need_mntput) { |
762 | /* lock_mount() may release path->mnt on error */ | |
763 | mntget(path->mnt); | |
764 | *need_mntput = true; | |
765 | } | |
19a167af | 766 | err = finish_automount(mnt, path); |
9875cf80 | 767 | |
ea5b778a DH |
768 | switch (err) { |
769 | case -EBUSY: | |
770 | /* Someone else made a mount here whilst we were busy */ | |
19a167af | 771 | return 0; |
ea5b778a | 772 | case 0: |
8aef1884 | 773 | path_put(path); |
ea5b778a DH |
774 | path->mnt = mnt; |
775 | path->dentry = dget(mnt->mnt_root); | |
ea5b778a | 776 | return 0; |
19a167af AV |
777 | default: |
778 | return err; | |
ea5b778a | 779 | } |
19a167af | 780 | |
463ffb2e AV |
781 | } |
782 | ||
9875cf80 DH |
783 | /* |
784 | * Handle a dentry that is managed in some way. | |
cc53ce53 | 785 | * - Flagged for transit management (autofs) |
9875cf80 DH |
786 | * - Flagged as mountpoint |
787 | * - Flagged as automount point | |
788 | * | |
789 | * This may only be called in refwalk mode. | |
790 | * | |
791 | * Serialization is taken care of in namespace.c | |
792 | */ | |
793 | static int follow_managed(struct path *path, unsigned flags) | |
1da177e4 | 794 | { |
8aef1884 | 795 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
9875cf80 DH |
796 | unsigned managed; |
797 | bool need_mntput = false; | |
8aef1884 | 798 | int ret = 0; |
9875cf80 DH |
799 | |
800 | /* Given that we're not holding a lock here, we retain the value in a | |
801 | * local variable for each dentry as we look at it so that we don't see | |
802 | * the components of that value change under us */ | |
803 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
804 | managed &= DCACHE_MANAGED_DENTRY, | |
805 | unlikely(managed != 0)) { | |
cc53ce53 DH |
806 | /* Allow the filesystem to manage the transit without i_mutex |
807 | * being held. */ | |
808 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
809 | BUG_ON(!path->dentry->d_op); | |
810 | BUG_ON(!path->dentry->d_op->d_manage); | |
1aed3e42 | 811 | ret = path->dentry->d_op->d_manage(path->dentry, false); |
cc53ce53 | 812 | if (ret < 0) |
8aef1884 | 813 | break; |
cc53ce53 DH |
814 | } |
815 | ||
9875cf80 DH |
816 | /* Transit to a mounted filesystem. */ |
817 | if (managed & DCACHE_MOUNTED) { | |
818 | struct vfsmount *mounted = lookup_mnt(path); | |
819 | if (mounted) { | |
820 | dput(path->dentry); | |
821 | if (need_mntput) | |
822 | mntput(path->mnt); | |
823 | path->mnt = mounted; | |
824 | path->dentry = dget(mounted->mnt_root); | |
825 | need_mntput = true; | |
826 | continue; | |
827 | } | |
828 | ||
829 | /* Something is mounted on this dentry in another | |
830 | * namespace and/or whatever was mounted there in this | |
831 | * namespace got unmounted before we managed to get the | |
832 | * vfsmount_lock */ | |
833 | } | |
834 | ||
835 | /* Handle an automount point */ | |
836 | if (managed & DCACHE_NEED_AUTOMOUNT) { | |
837 | ret = follow_automount(path, flags, &need_mntput); | |
838 | if (ret < 0) | |
8aef1884 | 839 | break; |
9875cf80 DH |
840 | continue; |
841 | } | |
842 | ||
843 | /* We didn't change the current path point */ | |
844 | break; | |
1da177e4 | 845 | } |
8aef1884 AV |
846 | |
847 | if (need_mntput && path->mnt == mnt) | |
848 | mntput(path->mnt); | |
849 | if (ret == -EISDIR) | |
850 | ret = 0; | |
851 | return ret; | |
1da177e4 LT |
852 | } |
853 | ||
cc53ce53 | 854 | int follow_down_one(struct path *path) |
1da177e4 LT |
855 | { |
856 | struct vfsmount *mounted; | |
857 | ||
1c755af4 | 858 | mounted = lookup_mnt(path); |
1da177e4 | 859 | if (mounted) { |
9393bd07 AV |
860 | dput(path->dentry); |
861 | mntput(path->mnt); | |
862 | path->mnt = mounted; | |
863 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
864 | return 1; |
865 | } | |
866 | return 0; | |
867 | } | |
868 | ||
62a7375e IK |
869 | static inline bool managed_dentry_might_block(struct dentry *dentry) |
870 | { | |
871 | return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && | |
872 | dentry->d_op->d_manage(dentry, true) < 0); | |
873 | } | |
874 | ||
9875cf80 | 875 | /* |
287548e4 AV |
876 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
877 | * we meet a managed dentry that would need blocking. | |
9875cf80 DH |
878 | */ |
879 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, | |
287548e4 | 880 | struct inode **inode) |
9875cf80 | 881 | { |
62a7375e | 882 | for (;;) { |
9875cf80 | 883 | struct vfsmount *mounted; |
62a7375e IK |
884 | /* |
885 | * Don't forget we might have a non-mountpoint managed dentry | |
886 | * that wants to block transit. | |
887 | */ | |
287548e4 | 888 | if (unlikely(managed_dentry_might_block(path->dentry))) |
ab90911f | 889 | return false; |
62a7375e IK |
890 | |
891 | if (!d_mountpoint(path->dentry)) | |
892 | break; | |
893 | ||
9875cf80 DH |
894 | mounted = __lookup_mnt(path->mnt, path->dentry, 1); |
895 | if (!mounted) | |
896 | break; | |
897 | path->mnt = mounted; | |
898 | path->dentry = mounted->mnt_root; | |
899 | nd->seq = read_seqcount_begin(&path->dentry->d_seq); | |
59430262 LT |
900 | /* |
901 | * Update the inode too. We don't need to re-check the | |
902 | * dentry sequence number here after this d_inode read, | |
903 | * because a mount-point is always pinned. | |
904 | */ | |
905 | *inode = path->dentry->d_inode; | |
9875cf80 | 906 | } |
9875cf80 DH |
907 | return true; |
908 | } | |
909 | ||
dea39376 | 910 | static void follow_mount_rcu(struct nameidata *nd) |
287548e4 | 911 | { |
dea39376 | 912 | while (d_mountpoint(nd->path.dentry)) { |
287548e4 | 913 | struct vfsmount *mounted; |
dea39376 | 914 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); |
287548e4 AV |
915 | if (!mounted) |
916 | break; | |
dea39376 AV |
917 | nd->path.mnt = mounted; |
918 | nd->path.dentry = mounted->mnt_root; | |
919 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
287548e4 AV |
920 | } |
921 | } | |
922 | ||
31e6b01f NP |
923 | static int follow_dotdot_rcu(struct nameidata *nd) |
924 | { | |
31e6b01f NP |
925 | set_root_rcu(nd); |
926 | ||
9875cf80 | 927 | while (1) { |
31e6b01f NP |
928 | if (nd->path.dentry == nd->root.dentry && |
929 | nd->path.mnt == nd->root.mnt) { | |
930 | break; | |
931 | } | |
932 | if (nd->path.dentry != nd->path.mnt->mnt_root) { | |
933 | struct dentry *old = nd->path.dentry; | |
934 | struct dentry *parent = old->d_parent; | |
935 | unsigned seq; | |
936 | ||
937 | seq = read_seqcount_begin(&parent->d_seq); | |
938 | if (read_seqcount_retry(&old->d_seq, nd->seq)) | |
ef7562d5 | 939 | goto failed; |
31e6b01f NP |
940 | nd->path.dentry = parent; |
941 | nd->seq = seq; | |
942 | break; | |
943 | } | |
944 | if (!follow_up_rcu(&nd->path)) | |
945 | break; | |
946 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
31e6b01f | 947 | } |
dea39376 AV |
948 | follow_mount_rcu(nd); |
949 | nd->inode = nd->path.dentry->d_inode; | |
31e6b01f | 950 | return 0; |
ef7562d5 AV |
951 | |
952 | failed: | |
953 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
954 | if (!(nd->flags & LOOKUP_ROOT)) |
955 | nd->root.mnt = NULL; | |
ef7562d5 AV |
956 | rcu_read_unlock(); |
957 | br_read_unlock(vfsmount_lock); | |
958 | return -ECHILD; | |
31e6b01f NP |
959 | } |
960 | ||
cc53ce53 DH |
961 | /* |
962 | * Follow down to the covering mount currently visible to userspace. At each | |
963 | * point, the filesystem owning that dentry may be queried as to whether the | |
964 | * caller is permitted to proceed or not. | |
cc53ce53 | 965 | */ |
7cc90cc3 | 966 | int follow_down(struct path *path) |
cc53ce53 DH |
967 | { |
968 | unsigned managed; | |
969 | int ret; | |
970 | ||
971 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
972 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { | |
973 | /* Allow the filesystem to manage the transit without i_mutex | |
974 | * being held. | |
975 | * | |
976 | * We indicate to the filesystem if someone is trying to mount | |
977 | * something here. This gives autofs the chance to deny anyone | |
978 | * other than its daemon the right to mount on its | |
979 | * superstructure. | |
980 | * | |
981 | * The filesystem may sleep at this point. | |
982 | */ | |
983 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
984 | BUG_ON(!path->dentry->d_op); | |
985 | BUG_ON(!path->dentry->d_op->d_manage); | |
ab90911f | 986 | ret = path->dentry->d_op->d_manage( |
1aed3e42 | 987 | path->dentry, false); |
cc53ce53 DH |
988 | if (ret < 0) |
989 | return ret == -EISDIR ? 0 : ret; | |
990 | } | |
991 | ||
992 | /* Transit to a mounted filesystem. */ | |
993 | if (managed & DCACHE_MOUNTED) { | |
994 | struct vfsmount *mounted = lookup_mnt(path); | |
995 | if (!mounted) | |
996 | break; | |
997 | dput(path->dentry); | |
998 | mntput(path->mnt); | |
999 | path->mnt = mounted; | |
1000 | path->dentry = dget(mounted->mnt_root); | |
1001 | continue; | |
1002 | } | |
1003 | ||
1004 | /* Don't handle automount points here */ | |
1005 | break; | |
1006 | } | |
1007 | return 0; | |
1008 | } | |
1009 | ||
9875cf80 DH |
1010 | /* |
1011 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() | |
1012 | */ | |
1013 | static void follow_mount(struct path *path) | |
1014 | { | |
1015 | while (d_mountpoint(path->dentry)) { | |
1016 | struct vfsmount *mounted = lookup_mnt(path); | |
1017 | if (!mounted) | |
1018 | break; | |
1019 | dput(path->dentry); | |
1020 | mntput(path->mnt); | |
1021 | path->mnt = mounted; | |
1022 | path->dentry = dget(mounted->mnt_root); | |
1023 | } | |
1024 | } | |
1025 | ||
31e6b01f | 1026 | static void follow_dotdot(struct nameidata *nd) |
1da177e4 | 1027 | { |
2a737871 | 1028 | set_root(nd); |
e518ddb7 | 1029 | |
1da177e4 | 1030 | while(1) { |
4ac91378 | 1031 | struct dentry *old = nd->path.dentry; |
1da177e4 | 1032 | |
2a737871 AV |
1033 | if (nd->path.dentry == nd->root.dentry && |
1034 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
1035 | break; |
1036 | } | |
4ac91378 | 1037 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
3088dd70 AV |
1038 | /* rare case of legitimate dget_parent()... */ |
1039 | nd->path.dentry = dget_parent(nd->path.dentry); | |
1da177e4 LT |
1040 | dput(old); |
1041 | break; | |
1042 | } | |
3088dd70 | 1043 | if (!follow_up(&nd->path)) |
1da177e4 | 1044 | break; |
1da177e4 | 1045 | } |
79ed0226 | 1046 | follow_mount(&nd->path); |
31e6b01f | 1047 | nd->inode = nd->path.dentry->d_inode; |
1da177e4 LT |
1048 | } |
1049 | ||
baa03890 NP |
1050 | /* |
1051 | * Allocate a dentry with name and parent, and perform a parent | |
1052 | * directory ->lookup on it. Returns the new dentry, or ERR_PTR | |
1053 | * on error. parent->d_inode->i_mutex must be held. d_lookup must | |
1054 | * have verified that no child exists while under i_mutex. | |
1055 | */ | |
1056 | static struct dentry *d_alloc_and_lookup(struct dentry *parent, | |
1057 | struct qstr *name, struct nameidata *nd) | |
1058 | { | |
1059 | struct inode *inode = parent->d_inode; | |
1060 | struct dentry *dentry; | |
1061 | struct dentry *old; | |
1062 | ||
1063 | /* Don't create child dentry for a dead directory. */ | |
1064 | if (unlikely(IS_DEADDIR(inode))) | |
1065 | return ERR_PTR(-ENOENT); | |
1066 | ||
1067 | dentry = d_alloc(parent, name); | |
1068 | if (unlikely(!dentry)) | |
1069 | return ERR_PTR(-ENOMEM); | |
1070 | ||
1071 | old = inode->i_op->lookup(inode, dentry, nd); | |
1072 | if (unlikely(old)) { | |
1073 | dput(dentry); | |
1074 | dentry = old; | |
1075 | } | |
1076 | return dentry; | |
1077 | } | |
1078 | ||
44396f4b JB |
1079 | /* |
1080 | * We already have a dentry, but require a lookup to be performed on the parent | |
1081 | * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error. | |
1082 | * parent->d_inode->i_mutex must be held. d_lookup must have verified that no | |
1083 | * child exists while under i_mutex. | |
1084 | */ | |
1085 | static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry, | |
1086 | struct nameidata *nd) | |
1087 | { | |
1088 | struct inode *inode = parent->d_inode; | |
1089 | struct dentry *old; | |
1090 | ||
1091 | /* Don't create child dentry for a dead directory. */ | |
1092 | if (unlikely(IS_DEADDIR(inode))) | |
1093 | return ERR_PTR(-ENOENT); | |
1094 | ||
1095 | old = inode->i_op->lookup(inode, dentry, nd); | |
1096 | if (unlikely(old)) { | |
1097 | dput(dentry); | |
1098 | dentry = old; | |
1099 | } | |
1100 | return dentry; | |
1101 | } | |
1102 | ||
1da177e4 LT |
1103 | /* |
1104 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
1105 | * small and for now I'd prefer to have fast path as straight as possible. | |
1106 | * It _is_ time-critical. | |
1107 | */ | |
1108 | static int do_lookup(struct nameidata *nd, struct qstr *name, | |
31e6b01f | 1109 | struct path *path, struct inode **inode) |
1da177e4 | 1110 | { |
4ac91378 | 1111 | struct vfsmount *mnt = nd->path.mnt; |
31e6b01f | 1112 | struct dentry *dentry, *parent = nd->path.dentry; |
5a18fff2 AV |
1113 | int need_reval = 1; |
1114 | int status = 1; | |
9875cf80 DH |
1115 | int err; |
1116 | ||
b04f784e NP |
1117 | /* |
1118 | * Rename seqlock is not required here because in the off chance | |
1119 | * of a false negative due to a concurrent rename, we're going to | |
1120 | * do the non-racy lookup, below. | |
1121 | */ | |
31e6b01f NP |
1122 | if (nd->flags & LOOKUP_RCU) { |
1123 | unsigned seq; | |
31e6b01f NP |
1124 | *inode = nd->inode; |
1125 | dentry = __d_lookup_rcu(parent, name, &seq, inode); | |
5a18fff2 AV |
1126 | if (!dentry) |
1127 | goto unlazy; | |
1128 | ||
31e6b01f NP |
1129 | /* Memory barrier in read_seqcount_begin of child is enough */ |
1130 | if (__read_seqcount_retry(&parent->d_seq, nd->seq)) | |
1131 | return -ECHILD; | |
31e6b01f | 1132 | nd->seq = seq; |
5a18fff2 | 1133 | |
24643087 | 1134 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
5a18fff2 AV |
1135 | status = d_revalidate(dentry, nd); |
1136 | if (unlikely(status <= 0)) { | |
1137 | if (status != -ECHILD) | |
1138 | need_reval = 0; | |
1139 | goto unlazy; | |
1140 | } | |
24643087 | 1141 | } |
44396f4b JB |
1142 | if (unlikely(d_need_lookup(dentry))) |
1143 | goto unlazy; | |
31e6b01f NP |
1144 | path->mnt = mnt; |
1145 | path->dentry = dentry; | |
d6e9bd25 AV |
1146 | if (unlikely(!__follow_mount_rcu(nd, path, inode))) |
1147 | goto unlazy; | |
1148 | if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) | |
1149 | goto unlazy; | |
1150 | return 0; | |
5a18fff2 | 1151 | unlazy: |
19660af7 AV |
1152 | if (unlazy_walk(nd, dentry)) |
1153 | return -ECHILD; | |
5a18fff2 AV |
1154 | } else { |
1155 | dentry = __d_lookup(parent, name); | |
9875cf80 | 1156 | } |
5a18fff2 | 1157 | |
44396f4b JB |
1158 | if (dentry && unlikely(d_need_lookup(dentry))) { |
1159 | dput(dentry); | |
1160 | dentry = NULL; | |
1161 | } | |
5a18fff2 AV |
1162 | retry: |
1163 | if (unlikely(!dentry)) { | |
1164 | struct inode *dir = parent->d_inode; | |
1165 | BUG_ON(nd->inode != dir); | |
1166 | ||
1167 | mutex_lock(&dir->i_mutex); | |
1168 | dentry = d_lookup(parent, name); | |
1169 | if (likely(!dentry)) { | |
1170 | dentry = d_alloc_and_lookup(parent, name, nd); | |
1171 | if (IS_ERR(dentry)) { | |
1172 | mutex_unlock(&dir->i_mutex); | |
1173 | return PTR_ERR(dentry); | |
1174 | } | |
1175 | /* known good */ | |
1176 | need_reval = 0; | |
1177 | status = 1; | |
44396f4b JB |
1178 | } else if (unlikely(d_need_lookup(dentry))) { |
1179 | dentry = d_inode_lookup(parent, dentry, nd); | |
1180 | if (IS_ERR(dentry)) { | |
1181 | mutex_unlock(&dir->i_mutex); | |
1182 | return PTR_ERR(dentry); | |
1183 | } | |
1184 | /* known good */ | |
1185 | need_reval = 0; | |
1186 | status = 1; | |
5a18fff2 AV |
1187 | } |
1188 | mutex_unlock(&dir->i_mutex); | |
1189 | } | |
1190 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) | |
1191 | status = d_revalidate(dentry, nd); | |
1192 | if (unlikely(status <= 0)) { | |
1193 | if (status < 0) { | |
1194 | dput(dentry); | |
1195 | return status; | |
1196 | } | |
1197 | if (!d_invalidate(dentry)) { | |
1198 | dput(dentry); | |
1199 | dentry = NULL; | |
1200 | need_reval = 1; | |
1201 | goto retry; | |
1202 | } | |
24643087 | 1203 | } |
5a18fff2 | 1204 | |
9875cf80 DH |
1205 | path->mnt = mnt; |
1206 | path->dentry = dentry; | |
1207 | err = follow_managed(path, nd->flags); | |
89312214 IK |
1208 | if (unlikely(err < 0)) { |
1209 | path_put_conditional(path, nd); | |
9875cf80 | 1210 | return err; |
89312214 | 1211 | } |
9875cf80 | 1212 | *inode = path->dentry->d_inode; |
1da177e4 | 1213 | return 0; |
1da177e4 LT |
1214 | } |
1215 | ||
52094c8a AV |
1216 | static inline int may_lookup(struct nameidata *nd) |
1217 | { | |
1218 | if (nd->flags & LOOKUP_RCU) { | |
4ad5abb3 | 1219 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
52094c8a AV |
1220 | if (err != -ECHILD) |
1221 | return err; | |
19660af7 | 1222 | if (unlazy_walk(nd, NULL)) |
52094c8a AV |
1223 | return -ECHILD; |
1224 | } | |
4ad5abb3 | 1225 | return inode_permission(nd->inode, MAY_EXEC); |
52094c8a AV |
1226 | } |
1227 | ||
9856fa1b AV |
1228 | static inline int handle_dots(struct nameidata *nd, int type) |
1229 | { | |
1230 | if (type == LAST_DOTDOT) { | |
1231 | if (nd->flags & LOOKUP_RCU) { | |
1232 | if (follow_dotdot_rcu(nd)) | |
1233 | return -ECHILD; | |
1234 | } else | |
1235 | follow_dotdot(nd); | |
1236 | } | |
1237 | return 0; | |
1238 | } | |
1239 | ||
951361f9 AV |
1240 | static void terminate_walk(struct nameidata *nd) |
1241 | { | |
1242 | if (!(nd->flags & LOOKUP_RCU)) { | |
1243 | path_put(&nd->path); | |
1244 | } else { | |
1245 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1246 | if (!(nd->flags & LOOKUP_ROOT)) |
1247 | nd->root.mnt = NULL; | |
951361f9 AV |
1248 | rcu_read_unlock(); |
1249 | br_read_unlock(vfsmount_lock); | |
1250 | } | |
1251 | } | |
1252 | ||
3ddcd056 LT |
1253 | /* |
1254 | * Do we need to follow links? We _really_ want to be able | |
1255 | * to do this check without having to look at inode->i_op, | |
1256 | * so we keep a cache of "no, this doesn't need follow_link" | |
1257 | * for the common case. | |
1258 | */ | |
7813b94a | 1259 | static inline int should_follow_link(struct inode *inode, int follow) |
3ddcd056 LT |
1260 | { |
1261 | if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { | |
1262 | if (likely(inode->i_op->follow_link)) | |
1263 | return follow; | |
1264 | ||
1265 | /* This gets set once for the inode lifetime */ | |
1266 | spin_lock(&inode->i_lock); | |
1267 | inode->i_opflags |= IOP_NOFOLLOW; | |
1268 | spin_unlock(&inode->i_lock); | |
1269 | } | |
1270 | return 0; | |
1271 | } | |
1272 | ||
ce57dfc1 AV |
1273 | static inline int walk_component(struct nameidata *nd, struct path *path, |
1274 | struct qstr *name, int type, int follow) | |
1275 | { | |
1276 | struct inode *inode; | |
1277 | int err; | |
1278 | /* | |
1279 | * "." and ".." are special - ".." especially so because it has | |
1280 | * to be able to know about the current root directory and | |
1281 | * parent relationships. | |
1282 | */ | |
1283 | if (unlikely(type != LAST_NORM)) | |
1284 | return handle_dots(nd, type); | |
1285 | err = do_lookup(nd, name, path, &inode); | |
1286 | if (unlikely(err)) { | |
1287 | terminate_walk(nd); | |
1288 | return err; | |
1289 | } | |
1290 | if (!inode) { | |
1291 | path_to_nameidata(path, nd); | |
1292 | terminate_walk(nd); | |
1293 | return -ENOENT; | |
1294 | } | |
7813b94a | 1295 | if (should_follow_link(inode, follow)) { |
19660af7 AV |
1296 | if (nd->flags & LOOKUP_RCU) { |
1297 | if (unlikely(unlazy_walk(nd, path->dentry))) { | |
1298 | terminate_walk(nd); | |
1299 | return -ECHILD; | |
1300 | } | |
1301 | } | |
ce57dfc1 AV |
1302 | BUG_ON(inode != path->dentry->d_inode); |
1303 | return 1; | |
1304 | } | |
1305 | path_to_nameidata(path, nd); | |
1306 | nd->inode = inode; | |
1307 | return 0; | |
1308 | } | |
1309 | ||
b356379a AV |
1310 | /* |
1311 | * This limits recursive symlink follows to 8, while | |
1312 | * limiting consecutive symlinks to 40. | |
1313 | * | |
1314 | * Without that kind of total limit, nasty chains of consecutive | |
1315 | * symlinks can cause almost arbitrarily long lookups. | |
1316 | */ | |
1317 | static inline int nested_symlink(struct path *path, struct nameidata *nd) | |
1318 | { | |
1319 | int res; | |
1320 | ||
b356379a AV |
1321 | if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { |
1322 | path_put_conditional(path, nd); | |
1323 | path_put(&nd->path); | |
1324 | return -ELOOP; | |
1325 | } | |
1a4022f8 | 1326 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); |
b356379a AV |
1327 | |
1328 | nd->depth++; | |
1329 | current->link_count++; | |
1330 | ||
1331 | do { | |
1332 | struct path link = *path; | |
1333 | void *cookie; | |
574197e0 AV |
1334 | |
1335 | res = follow_link(&link, nd, &cookie); | |
b356379a AV |
1336 | if (!res) |
1337 | res = walk_component(nd, path, &nd->last, | |
1338 | nd->last_type, LOOKUP_FOLLOW); | |
574197e0 | 1339 | put_link(nd, &link, cookie); |
b356379a AV |
1340 | } while (res > 0); |
1341 | ||
1342 | current->link_count--; | |
1343 | nd->depth--; | |
1344 | return res; | |
1345 | } | |
1346 | ||
3ddcd056 LT |
1347 | /* |
1348 | * We really don't want to look at inode->i_op->lookup | |
1349 | * when we don't have to. So we keep a cache bit in | |
1350 | * the inode ->i_opflags field that says "yes, we can | |
1351 | * do lookup on this inode". | |
1352 | */ | |
1353 | static inline int can_lookup(struct inode *inode) | |
1354 | { | |
1355 | if (likely(inode->i_opflags & IOP_LOOKUP)) | |
1356 | return 1; | |
1357 | if (likely(!inode->i_op->lookup)) | |
1358 | return 0; | |
1359 | ||
1360 | /* We do this once for the lifetime of the inode */ | |
1361 | spin_lock(&inode->i_lock); | |
1362 | inode->i_opflags |= IOP_LOOKUP; | |
1363 | spin_unlock(&inode->i_lock); | |
1364 | return 1; | |
1365 | } | |
1366 | ||
1da177e4 LT |
1367 | /* |
1368 | * Name resolution. | |
ea3834d9 PM |
1369 | * This is the basic name resolution function, turning a pathname into |
1370 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 1371 | * |
ea3834d9 PM |
1372 | * Returns 0 and nd will have valid dentry and mnt on success. |
1373 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 1374 | */ |
6de88d72 | 1375 | static int link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 LT |
1376 | { |
1377 | struct path next; | |
1da177e4 | 1378 | int err; |
1da177e4 LT |
1379 | |
1380 | while (*name=='/') | |
1381 | name++; | |
1382 | if (!*name) | |
086e183a | 1383 | return 0; |
1da177e4 | 1384 | |
1da177e4 LT |
1385 | /* At this point we know we have a real path component. */ |
1386 | for(;;) { | |
1387 | unsigned long hash; | |
1388 | struct qstr this; | |
1389 | unsigned int c; | |
fe479a58 | 1390 | int type; |
1da177e4 | 1391 | |
52094c8a | 1392 | err = may_lookup(nd); |
1da177e4 LT |
1393 | if (err) |
1394 | break; | |
1395 | ||
1396 | this.name = name; | |
1397 | c = *(const unsigned char *)name; | |
1398 | ||
1399 | hash = init_name_hash(); | |
1400 | do { | |
1401 | name++; | |
1402 | hash = partial_name_hash(c, hash); | |
1403 | c = *(const unsigned char *)name; | |
1404 | } while (c && (c != '/')); | |
1405 | this.len = name - (const char *) this.name; | |
1406 | this.hash = end_name_hash(hash); | |
1407 | ||
fe479a58 AV |
1408 | type = LAST_NORM; |
1409 | if (this.name[0] == '.') switch (this.len) { | |
1410 | case 2: | |
16c2cd71 | 1411 | if (this.name[1] == '.') { |
fe479a58 | 1412 | type = LAST_DOTDOT; |
16c2cd71 AV |
1413 | nd->flags |= LOOKUP_JUMPED; |
1414 | } | |
fe479a58 AV |
1415 | break; |
1416 | case 1: | |
1417 | type = LAST_DOT; | |
1418 | } | |
5a202bcd AV |
1419 | if (likely(type == LAST_NORM)) { |
1420 | struct dentry *parent = nd->path.dentry; | |
16c2cd71 | 1421 | nd->flags &= ~LOOKUP_JUMPED; |
5a202bcd AV |
1422 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
1423 | err = parent->d_op->d_hash(parent, nd->inode, | |
1424 | &this); | |
1425 | if (err < 0) | |
1426 | break; | |
1427 | } | |
1428 | } | |
fe479a58 | 1429 | |
1da177e4 LT |
1430 | /* remove trailing slashes? */ |
1431 | if (!c) | |
1432 | goto last_component; | |
1433 | while (*++name == '/'); | |
1434 | if (!*name) | |
b356379a | 1435 | goto last_component; |
1da177e4 | 1436 | |
ce57dfc1 AV |
1437 | err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); |
1438 | if (err < 0) | |
1439 | return err; | |
1da177e4 | 1440 | |
ce57dfc1 | 1441 | if (err) { |
b356379a | 1442 | err = nested_symlink(&next, nd); |
1da177e4 | 1443 | if (err) |
a7472bab | 1444 | return err; |
31e6b01f | 1445 | } |
3ddcd056 LT |
1446 | if (can_lookup(nd->inode)) |
1447 | continue; | |
1da177e4 | 1448 | err = -ENOTDIR; |
3ddcd056 | 1449 | break; |
1da177e4 LT |
1450 | /* here ends the main loop */ |
1451 | ||
1da177e4 | 1452 | last_component: |
b356379a AV |
1453 | nd->last = this; |
1454 | nd->last_type = type; | |
086e183a | 1455 | return 0; |
1da177e4 | 1456 | } |
951361f9 | 1457 | terminate_walk(nd); |
1da177e4 LT |
1458 | return err; |
1459 | } | |
1460 | ||
70e9b357 AV |
1461 | static int path_init(int dfd, const char *name, unsigned int flags, |
1462 | struct nameidata *nd, struct file **fp) | |
31e6b01f NP |
1463 | { |
1464 | int retval = 0; | |
1465 | int fput_needed; | |
1466 | struct file *file; | |
1467 | ||
1468 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
16c2cd71 | 1469 | nd->flags = flags | LOOKUP_JUMPED; |
31e6b01f | 1470 | nd->depth = 0; |
5b6ca027 AV |
1471 | if (flags & LOOKUP_ROOT) { |
1472 | struct inode *inode = nd->root.dentry->d_inode; | |
73d049a4 AV |
1473 | if (*name) { |
1474 | if (!inode->i_op->lookup) | |
1475 | return -ENOTDIR; | |
1476 | retval = inode_permission(inode, MAY_EXEC); | |
1477 | if (retval) | |
1478 | return retval; | |
1479 | } | |
5b6ca027 AV |
1480 | nd->path = nd->root; |
1481 | nd->inode = inode; | |
1482 | if (flags & LOOKUP_RCU) { | |
1483 | br_read_lock(vfsmount_lock); | |
1484 | rcu_read_lock(); | |
1485 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
1486 | } else { | |
1487 | path_get(&nd->path); | |
1488 | } | |
1489 | return 0; | |
1490 | } | |
1491 | ||
31e6b01f | 1492 | nd->root.mnt = NULL; |
31e6b01f NP |
1493 | |
1494 | if (*name=='/') { | |
e41f7d4e AV |
1495 | if (flags & LOOKUP_RCU) { |
1496 | br_read_lock(vfsmount_lock); | |
1497 | rcu_read_lock(); | |
1498 | set_root_rcu(nd); | |
1499 | } else { | |
1500 | set_root(nd); | |
1501 | path_get(&nd->root); | |
1502 | } | |
1503 | nd->path = nd->root; | |
31e6b01f | 1504 | } else if (dfd == AT_FDCWD) { |
e41f7d4e AV |
1505 | if (flags & LOOKUP_RCU) { |
1506 | struct fs_struct *fs = current->fs; | |
1507 | unsigned seq; | |
31e6b01f | 1508 | |
e41f7d4e AV |
1509 | br_read_lock(vfsmount_lock); |
1510 | rcu_read_lock(); | |
c28cc364 | 1511 | |
e41f7d4e AV |
1512 | do { |
1513 | seq = read_seqcount_begin(&fs->seq); | |
1514 | nd->path = fs->pwd; | |
1515 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
1516 | } while (read_seqcount_retry(&fs->seq, seq)); | |
1517 | } else { | |
1518 | get_fs_pwd(current->fs, &nd->path); | |
1519 | } | |
31e6b01f NP |
1520 | } else { |
1521 | struct dentry *dentry; | |
1522 | ||
1abf0c71 | 1523 | file = fget_raw_light(dfd, &fput_needed); |
31e6b01f NP |
1524 | retval = -EBADF; |
1525 | if (!file) | |
1526 | goto out_fail; | |
1527 | ||
1528 | dentry = file->f_path.dentry; | |
1529 | ||
f52e0c11 AV |
1530 | if (*name) { |
1531 | retval = -ENOTDIR; | |
1532 | if (!S_ISDIR(dentry->d_inode->i_mode)) | |
1533 | goto fput_fail; | |
31e6b01f | 1534 | |
4ad5abb3 | 1535 | retval = inode_permission(dentry->d_inode, MAY_EXEC); |
f52e0c11 AV |
1536 | if (retval) |
1537 | goto fput_fail; | |
1538 | } | |
31e6b01f NP |
1539 | |
1540 | nd->path = file->f_path; | |
e41f7d4e AV |
1541 | if (flags & LOOKUP_RCU) { |
1542 | if (fput_needed) | |
70e9b357 | 1543 | *fp = file; |
e41f7d4e AV |
1544 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
1545 | br_read_lock(vfsmount_lock); | |
1546 | rcu_read_lock(); | |
1547 | } else { | |
1548 | path_get(&file->f_path); | |
1549 | fput_light(file, fput_needed); | |
1550 | } | |
31e6b01f | 1551 | } |
31e6b01f | 1552 | |
31e6b01f | 1553 | nd->inode = nd->path.dentry->d_inode; |
9b4a9b14 | 1554 | return 0; |
2dfdd266 | 1555 | |
9b4a9b14 AV |
1556 | fput_fail: |
1557 | fput_light(file, fput_needed); | |
1558 | out_fail: | |
1559 | return retval; | |
1560 | } | |
1561 | ||
bd92d7fe AV |
1562 | static inline int lookup_last(struct nameidata *nd, struct path *path) |
1563 | { | |
1564 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) | |
1565 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
1566 | ||
1567 | nd->flags &= ~LOOKUP_PARENT; | |
1568 | return walk_component(nd, path, &nd->last, nd->last_type, | |
1569 | nd->flags & LOOKUP_FOLLOW); | |
1570 | } | |
1571 | ||
9b4a9b14 | 1572 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
ee0827cd | 1573 | static int path_lookupat(int dfd, const char *name, |
9b4a9b14 AV |
1574 | unsigned int flags, struct nameidata *nd) |
1575 | { | |
70e9b357 | 1576 | struct file *base = NULL; |
bd92d7fe AV |
1577 | struct path path; |
1578 | int err; | |
31e6b01f NP |
1579 | |
1580 | /* | |
1581 | * Path walking is largely split up into 2 different synchronisation | |
1582 | * schemes, rcu-walk and ref-walk (explained in | |
1583 | * Documentation/filesystems/path-lookup.txt). These share much of the | |
1584 | * path walk code, but some things particularly setup, cleanup, and | |
1585 | * following mounts are sufficiently divergent that functions are | |
1586 | * duplicated. Typically there is a function foo(), and its RCU | |
1587 | * analogue, foo_rcu(). | |
1588 | * | |
1589 | * -ECHILD is the error number of choice (just to avoid clashes) that | |
1590 | * is returned if some aspect of an rcu-walk fails. Such an error must | |
1591 | * be handled by restarting a traditional ref-walk (which will always | |
1592 | * be able to complete). | |
1593 | */ | |
bd92d7fe | 1594 | err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); |
ee0827cd | 1595 | |
bd92d7fe AV |
1596 | if (unlikely(err)) |
1597 | return err; | |
ee0827cd AV |
1598 | |
1599 | current->total_link_count = 0; | |
bd92d7fe AV |
1600 | err = link_path_walk(name, nd); |
1601 | ||
1602 | if (!err && !(flags & LOOKUP_PARENT)) { | |
bd92d7fe AV |
1603 | err = lookup_last(nd, &path); |
1604 | while (err > 0) { | |
1605 | void *cookie; | |
1606 | struct path link = path; | |
bd92d7fe | 1607 | nd->flags |= LOOKUP_PARENT; |
574197e0 | 1608 | err = follow_link(&link, nd, &cookie); |
bd92d7fe AV |
1609 | if (!err) |
1610 | err = lookup_last(nd, &path); | |
574197e0 | 1611 | put_link(nd, &link, cookie); |
bd92d7fe AV |
1612 | } |
1613 | } | |
ee0827cd | 1614 | |
9f1fafee AV |
1615 | if (!err) |
1616 | err = complete_walk(nd); | |
bd92d7fe AV |
1617 | |
1618 | if (!err && nd->flags & LOOKUP_DIRECTORY) { | |
1619 | if (!nd->inode->i_op->lookup) { | |
1620 | path_put(&nd->path); | |
bd23a539 | 1621 | err = -ENOTDIR; |
bd92d7fe AV |
1622 | } |
1623 | } | |
16c2cd71 | 1624 | |
70e9b357 AV |
1625 | if (base) |
1626 | fput(base); | |
ee0827cd | 1627 | |
5b6ca027 | 1628 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
2a737871 AV |
1629 | path_put(&nd->root); |
1630 | nd->root.mnt = NULL; | |
1631 | } | |
bd92d7fe | 1632 | return err; |
ee0827cd | 1633 | } |
31e6b01f | 1634 | |
ee0827cd AV |
1635 | static int do_path_lookup(int dfd, const char *name, |
1636 | unsigned int flags, struct nameidata *nd) | |
1637 | { | |
1638 | int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); | |
1639 | if (unlikely(retval == -ECHILD)) | |
1640 | retval = path_lookupat(dfd, name, flags, nd); | |
1641 | if (unlikely(retval == -ESTALE)) | |
1642 | retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); | |
31e6b01f NP |
1643 | |
1644 | if (likely(!retval)) { | |
1645 | if (unlikely(!audit_dummy_context())) { | |
1646 | if (nd->path.dentry && nd->inode) | |
1647 | audit_inode(name, nd->path.dentry); | |
1648 | } | |
1649 | } | |
170aa3d0 | 1650 | return retval; |
1da177e4 LT |
1651 | } |
1652 | ||
c9c6cac0 | 1653 | int kern_path_parent(const char *name, struct nameidata *nd) |
5590ff0d | 1654 | { |
c9c6cac0 | 1655 | return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); |
5590ff0d UD |
1656 | } |
1657 | ||
d1811465 AV |
1658 | int kern_path(const char *name, unsigned int flags, struct path *path) |
1659 | { | |
1660 | struct nameidata nd; | |
1661 | int res = do_path_lookup(AT_FDCWD, name, flags, &nd); | |
1662 | if (!res) | |
1663 | *path = nd.path; | |
1664 | return res; | |
1665 | } | |
1666 | ||
16f18200 JJS |
1667 | /** |
1668 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
1669 | * @dentry: pointer to dentry of the base directory | |
1670 | * @mnt: pointer to vfs mount of the base directory | |
1671 | * @name: pointer to file name | |
1672 | * @flags: lookup flags | |
e0a01249 | 1673 | * @path: pointer to struct path to fill |
16f18200 JJS |
1674 | */ |
1675 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
1676 | const char *name, unsigned int flags, | |
e0a01249 | 1677 | struct path *path) |
16f18200 | 1678 | { |
e0a01249 AV |
1679 | struct nameidata nd; |
1680 | int err; | |
1681 | nd.root.dentry = dentry; | |
1682 | nd.root.mnt = mnt; | |
1683 | BUG_ON(flags & LOOKUP_PARENT); | |
5b6ca027 | 1684 | /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ |
e0a01249 AV |
1685 | err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); |
1686 | if (!err) | |
1687 | *path = nd.path; | |
1688 | return err; | |
16f18200 JJS |
1689 | } |
1690 | ||
eead1911 CH |
1691 | static struct dentry *__lookup_hash(struct qstr *name, |
1692 | struct dentry *base, struct nameidata *nd) | |
1da177e4 | 1693 | { |
81fca444 | 1694 | struct inode *inode = base->d_inode; |
057f6c01 | 1695 | struct dentry *dentry; |
1da177e4 LT |
1696 | int err; |
1697 | ||
4ad5abb3 | 1698 | err = inode_permission(inode, MAY_EXEC); |
81fca444 CH |
1699 | if (err) |
1700 | return ERR_PTR(err); | |
1da177e4 | 1701 | |
b04f784e NP |
1702 | /* |
1703 | * Don't bother with __d_lookup: callers are for creat as | |
1704 | * well as unlink, so a lot of the time it would cost | |
1705 | * a double lookup. | |
6e6b1bd1 | 1706 | */ |
b04f784e | 1707 | dentry = d_lookup(base, name); |
6e6b1bd1 | 1708 | |
44396f4b JB |
1709 | if (dentry && d_need_lookup(dentry)) { |
1710 | /* | |
1711 | * __lookup_hash is called with the parent dir's i_mutex already | |
1712 | * held, so we are good to go here. | |
1713 | */ | |
1714 | dentry = d_inode_lookup(base, dentry, nd); | |
1715 | if (IS_ERR(dentry)) | |
1716 | return dentry; | |
1717 | } | |
1718 | ||
d2d9e9fb AV |
1719 | if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
1720 | int status = d_revalidate(dentry, nd); | |
1721 | if (unlikely(status <= 0)) { | |
1722 | /* | |
1723 | * The dentry failed validation. | |
1724 | * If d_revalidate returned 0 attempt to invalidate | |
1725 | * the dentry otherwise d_revalidate is asking us | |
1726 | * to return a fail status. | |
1727 | */ | |
1728 | if (status < 0) { | |
1729 | dput(dentry); | |
1730 | return ERR_PTR(status); | |
1731 | } else if (!d_invalidate(dentry)) { | |
1732 | dput(dentry); | |
1733 | dentry = NULL; | |
1734 | } | |
1735 | } | |
1736 | } | |
6e6b1bd1 | 1737 | |
baa03890 NP |
1738 | if (!dentry) |
1739 | dentry = d_alloc_and_lookup(base, name, nd); | |
5a202bcd | 1740 | |
1da177e4 LT |
1741 | return dentry; |
1742 | } | |
1743 | ||
057f6c01 JM |
1744 | /* |
1745 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
1746 | * needs parent already locked. Doesn't follow mounts. | |
1747 | * SMP-safe. | |
1748 | */ | |
eead1911 | 1749 | static struct dentry *lookup_hash(struct nameidata *nd) |
057f6c01 | 1750 | { |
4ac91378 | 1751 | return __lookup_hash(&nd->last, nd->path.dentry, nd); |
1da177e4 LT |
1752 | } |
1753 | ||
eead1911 | 1754 | /** |
a6b91919 | 1755 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
1756 | * @name: pathname component to lookup |
1757 | * @base: base directory to lookup from | |
1758 | * @len: maximum length @len should be interpreted to | |
1759 | * | |
a6b91919 RD |
1760 | * Note that this routine is purely a helper for filesystem usage and should |
1761 | * not be called by generic code. Also note that by using this function the | |
eead1911 CH |
1762 | * nameidata argument is passed to the filesystem methods and a filesystem |
1763 | * using this helper needs to be prepared for that. | |
1764 | */ | |
057f6c01 JM |
1765 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
1766 | { | |
057f6c01 | 1767 | struct qstr this; |
6a96ba54 AV |
1768 | unsigned long hash; |
1769 | unsigned int c; | |
057f6c01 | 1770 | |
2f9092e1 DW |
1771 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
1772 | ||
6a96ba54 AV |
1773 | this.name = name; |
1774 | this.len = len; | |
1775 | if (!len) | |
1776 | return ERR_PTR(-EACCES); | |
1777 | ||
1778 | hash = init_name_hash(); | |
1779 | while (len--) { | |
1780 | c = *(const unsigned char *)name++; | |
1781 | if (c == '/' || c == '\0') | |
1782 | return ERR_PTR(-EACCES); | |
1783 | hash = partial_name_hash(c, hash); | |
1784 | } | |
1785 | this.hash = end_name_hash(hash); | |
5a202bcd AV |
1786 | /* |
1787 | * See if the low-level filesystem might want | |
1788 | * to use its own hash.. | |
1789 | */ | |
1790 | if (base->d_flags & DCACHE_OP_HASH) { | |
1791 | int err = base->d_op->d_hash(base, base->d_inode, &this); | |
1792 | if (err < 0) | |
1793 | return ERR_PTR(err); | |
1794 | } | |
eead1911 | 1795 | |
49705b77 | 1796 | return __lookup_hash(&this, base, NULL); |
057f6c01 JM |
1797 | } |
1798 | ||
2d8f3038 AV |
1799 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
1800 | struct path *path) | |
1da177e4 | 1801 | { |
2d8f3038 | 1802 | struct nameidata nd; |
f52e0c11 | 1803 | char *tmp = getname_flags(name, flags); |
1da177e4 | 1804 | int err = PTR_ERR(tmp); |
1da177e4 | 1805 | if (!IS_ERR(tmp)) { |
2d8f3038 AV |
1806 | |
1807 | BUG_ON(flags & LOOKUP_PARENT); | |
1808 | ||
1809 | err = do_path_lookup(dfd, tmp, flags, &nd); | |
1da177e4 | 1810 | putname(tmp); |
2d8f3038 AV |
1811 | if (!err) |
1812 | *path = nd.path; | |
1da177e4 LT |
1813 | } |
1814 | return err; | |
1815 | } | |
1816 | ||
2ad94ae6 AV |
1817 | static int user_path_parent(int dfd, const char __user *path, |
1818 | struct nameidata *nd, char **name) | |
1819 | { | |
1820 | char *s = getname(path); | |
1821 | int error; | |
1822 | ||
1823 | if (IS_ERR(s)) | |
1824 | return PTR_ERR(s); | |
1825 | ||
1826 | error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); | |
1827 | if (error) | |
1828 | putname(s); | |
1829 | else | |
1830 | *name = s; | |
1831 | ||
1832 | return error; | |
1833 | } | |
1834 | ||
1da177e4 LT |
1835 | /* |
1836 | * It's inline, so penalty for filesystems that don't use sticky bit is | |
1837 | * minimal. | |
1838 | */ | |
1839 | static inline int check_sticky(struct inode *dir, struct inode *inode) | |
1840 | { | |
da9592ed DH |
1841 | uid_t fsuid = current_fsuid(); |
1842 | ||
1da177e4 LT |
1843 | if (!(dir->i_mode & S_ISVTX)) |
1844 | return 0; | |
e795b717 SH |
1845 | if (current_user_ns() != inode_userns(inode)) |
1846 | goto other_userns; | |
da9592ed | 1847 | if (inode->i_uid == fsuid) |
1da177e4 | 1848 | return 0; |
da9592ed | 1849 | if (dir->i_uid == fsuid) |
1da177e4 | 1850 | return 0; |
e795b717 SH |
1851 | |
1852 | other_userns: | |
1853 | return !ns_capable(inode_userns(inode), CAP_FOWNER); | |
1da177e4 LT |
1854 | } |
1855 | ||
1856 | /* | |
1857 | * Check whether we can remove a link victim from directory dir, check | |
1858 | * whether the type of victim is right. | |
1859 | * 1. We can't do it if dir is read-only (done in permission()) | |
1860 | * 2. We should have write and exec permissions on dir | |
1861 | * 3. We can't remove anything from append-only dir | |
1862 | * 4. We can't do anything with immutable dir (done in permission()) | |
1863 | * 5. If the sticky bit on dir is set we should either | |
1864 | * a. be owner of dir, or | |
1865 | * b. be owner of victim, or | |
1866 | * c. have CAP_FOWNER capability | |
1867 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
1868 | * links pointing to it. | |
1869 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
1870 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
1871 | * 9. We can't remove a root or mountpoint. | |
1872 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
1873 | * nfs_async_unlink(). | |
1874 | */ | |
858119e1 | 1875 | static int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
1da177e4 LT |
1876 | { |
1877 | int error; | |
1878 | ||
1879 | if (!victim->d_inode) | |
1880 | return -ENOENT; | |
1881 | ||
1882 | BUG_ON(victim->d_parent->d_inode != dir); | |
cccc6bba | 1883 | audit_inode_child(victim, dir); |
1da177e4 | 1884 | |
f419a2e3 | 1885 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
1886 | if (error) |
1887 | return error; | |
1888 | if (IS_APPEND(dir)) | |
1889 | return -EPERM; | |
1890 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| | |
f9454548 | 1891 | IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) |
1da177e4 LT |
1892 | return -EPERM; |
1893 | if (isdir) { | |
1894 | if (!S_ISDIR(victim->d_inode->i_mode)) | |
1895 | return -ENOTDIR; | |
1896 | if (IS_ROOT(victim)) | |
1897 | return -EBUSY; | |
1898 | } else if (S_ISDIR(victim->d_inode->i_mode)) | |
1899 | return -EISDIR; | |
1900 | if (IS_DEADDIR(dir)) | |
1901 | return -ENOENT; | |
1902 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
1903 | return -EBUSY; | |
1904 | return 0; | |
1905 | } | |
1906 | ||
1907 | /* Check whether we can create an object with dentry child in directory | |
1908 | * dir. | |
1909 | * 1. We can't do it if child already exists (open has special treatment for | |
1910 | * this case, but since we are inlined it's OK) | |
1911 | * 2. We can't do it if dir is read-only (done in permission()) | |
1912 | * 3. We should have write and exec permissions on dir | |
1913 | * 4. We can't do it if dir is immutable (done in permission()) | |
1914 | */ | |
a95164d9 | 1915 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 LT |
1916 | { |
1917 | if (child->d_inode) | |
1918 | return -EEXIST; | |
1919 | if (IS_DEADDIR(dir)) | |
1920 | return -ENOENT; | |
f419a2e3 | 1921 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
1922 | } |
1923 | ||
1da177e4 LT |
1924 | /* |
1925 | * p1 and p2 should be directories on the same fs. | |
1926 | */ | |
1927 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
1928 | { | |
1929 | struct dentry *p; | |
1930 | ||
1931 | if (p1 == p2) { | |
f2eace23 | 1932 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
1933 | return NULL; |
1934 | } | |
1935 | ||
a11f3a05 | 1936 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 | 1937 | |
e2761a11 OH |
1938 | p = d_ancestor(p2, p1); |
1939 | if (p) { | |
1940 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); | |
1941 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
1942 | return p; | |
1da177e4 LT |
1943 | } |
1944 | ||
e2761a11 OH |
1945 | p = d_ancestor(p1, p2); |
1946 | if (p) { | |
1947 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); | |
1948 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1949 | return p; | |
1da177e4 LT |
1950 | } |
1951 | ||
f2eace23 IM |
1952 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1953 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1da177e4 LT |
1954 | return NULL; |
1955 | } | |
1956 | ||
1957 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
1958 | { | |
1b1dcc1b | 1959 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 1960 | if (p1 != p2) { |
1b1dcc1b | 1961 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 1962 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
1963 | } |
1964 | } | |
1965 | ||
1966 | int vfs_create(struct inode *dir, struct dentry *dentry, int mode, | |
1967 | struct nameidata *nd) | |
1968 | { | |
a95164d9 | 1969 | int error = may_create(dir, dentry); |
1da177e4 LT |
1970 | |
1971 | if (error) | |
1972 | return error; | |
1973 | ||
acfa4380 | 1974 | if (!dir->i_op->create) |
1da177e4 LT |
1975 | return -EACCES; /* shouldn't it be ENOSYS? */ |
1976 | mode &= S_IALLUGO; | |
1977 | mode |= S_IFREG; | |
1978 | error = security_inode_create(dir, dentry, mode); | |
1979 | if (error) | |
1980 | return error; | |
1da177e4 | 1981 | error = dir->i_op->create(dir, dentry, mode, nd); |
a74574aa | 1982 | if (!error) |
f38aa942 | 1983 | fsnotify_create(dir, dentry); |
1da177e4 LT |
1984 | return error; |
1985 | } | |
1986 | ||
73d049a4 | 1987 | static int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 1988 | { |
3fb64190 | 1989 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
1990 | struct inode *inode = dentry->d_inode; |
1991 | int error; | |
1992 | ||
bcda7652 AV |
1993 | /* O_PATH? */ |
1994 | if (!acc_mode) | |
1995 | return 0; | |
1996 | ||
1da177e4 LT |
1997 | if (!inode) |
1998 | return -ENOENT; | |
1999 | ||
c8fe8f30 CH |
2000 | switch (inode->i_mode & S_IFMT) { |
2001 | case S_IFLNK: | |
1da177e4 | 2002 | return -ELOOP; |
c8fe8f30 CH |
2003 | case S_IFDIR: |
2004 | if (acc_mode & MAY_WRITE) | |
2005 | return -EISDIR; | |
2006 | break; | |
2007 | case S_IFBLK: | |
2008 | case S_IFCHR: | |
3fb64190 | 2009 | if (path->mnt->mnt_flags & MNT_NODEV) |
1da177e4 | 2010 | return -EACCES; |
c8fe8f30 CH |
2011 | /*FALLTHRU*/ |
2012 | case S_IFIFO: | |
2013 | case S_IFSOCK: | |
1da177e4 | 2014 | flag &= ~O_TRUNC; |
c8fe8f30 | 2015 | break; |
4a3fd211 | 2016 | } |
b41572e9 | 2017 | |
3fb64190 | 2018 | error = inode_permission(inode, acc_mode); |
b41572e9 DH |
2019 | if (error) |
2020 | return error; | |
6146f0d5 | 2021 | |
1da177e4 LT |
2022 | /* |
2023 | * An append-only file must be opened in append mode for writing. | |
2024 | */ | |
2025 | if (IS_APPEND(inode)) { | |
8737c930 | 2026 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
7715b521 | 2027 | return -EPERM; |
1da177e4 | 2028 | if (flag & O_TRUNC) |
7715b521 | 2029 | return -EPERM; |
1da177e4 LT |
2030 | } |
2031 | ||
2032 | /* O_NOATIME can only be set by the owner or superuser */ | |
2e149670 | 2033 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
7715b521 | 2034 | return -EPERM; |
1da177e4 LT |
2035 | |
2036 | /* | |
2037 | * Ensure there are no outstanding leases on the file. | |
2038 | */ | |
b65a9cfc | 2039 | return break_lease(inode, flag); |
7715b521 | 2040 | } |
1da177e4 | 2041 | |
e1181ee6 | 2042 | static int handle_truncate(struct file *filp) |
7715b521 | 2043 | { |
e1181ee6 | 2044 | struct path *path = &filp->f_path; |
7715b521 AV |
2045 | struct inode *inode = path->dentry->d_inode; |
2046 | int error = get_write_access(inode); | |
2047 | if (error) | |
2048 | return error; | |
2049 | /* | |
2050 | * Refuse to truncate files with mandatory locks held on them. | |
2051 | */ | |
2052 | error = locks_verify_locked(inode); | |
2053 | if (!error) | |
ea0d3ab2 | 2054 | error = security_path_truncate(path); |
7715b521 AV |
2055 | if (!error) { |
2056 | error = do_truncate(path->dentry, 0, | |
2057 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
e1181ee6 | 2058 | filp); |
7715b521 AV |
2059 | } |
2060 | put_write_access(inode); | |
acd0c935 | 2061 | return error; |
1da177e4 LT |
2062 | } |
2063 | ||
d57999e1 DH |
2064 | static inline int open_to_namei_flags(int flag) |
2065 | { | |
8a5e929d AV |
2066 | if ((flag & O_ACCMODE) == 3) |
2067 | flag--; | |
d57999e1 DH |
2068 | return flag; |
2069 | } | |
2070 | ||
31e6b01f | 2071 | /* |
fe2d35ff | 2072 | * Handle the last step of open() |
31e6b01f | 2073 | */ |
fb1cc555 | 2074 | static struct file *do_last(struct nameidata *nd, struct path *path, |
c3e380b0 | 2075 | const struct open_flags *op, const char *pathname) |
fb1cc555 | 2076 | { |
a1e28038 | 2077 | struct dentry *dir = nd->path.dentry; |
6c0d46c4 | 2078 | struct dentry *dentry; |
ca344a89 | 2079 | int open_flag = op->open_flag; |
6c0d46c4 | 2080 | int will_truncate = open_flag & O_TRUNC; |
ca344a89 | 2081 | int want_write = 0; |
bcda7652 | 2082 | int acc_mode = op->acc_mode; |
fb1cc555 | 2083 | struct file *filp; |
16c2cd71 | 2084 | int error; |
1f36f774 | 2085 | |
c3e380b0 AV |
2086 | nd->flags &= ~LOOKUP_PARENT; |
2087 | nd->flags |= op->intent; | |
2088 | ||
1f36f774 AV |
2089 | switch (nd->last_type) { |
2090 | case LAST_DOTDOT: | |
176306f5 | 2091 | case LAST_DOT: |
fe2d35ff AV |
2092 | error = handle_dots(nd, nd->last_type); |
2093 | if (error) | |
2094 | return ERR_PTR(error); | |
1f36f774 | 2095 | /* fallthrough */ |
1f36f774 | 2096 | case LAST_ROOT: |
9f1fafee | 2097 | error = complete_walk(nd); |
16c2cd71 | 2098 | if (error) |
9f1fafee | 2099 | return ERR_PTR(error); |
fe2d35ff | 2100 | audit_inode(pathname, nd->path.dentry); |
ca344a89 | 2101 | if (open_flag & O_CREAT) { |
fe2d35ff AV |
2102 | error = -EISDIR; |
2103 | goto exit; | |
2104 | } | |
2105 | goto ok; | |
1f36f774 | 2106 | case LAST_BIND: |
9f1fafee | 2107 | error = complete_walk(nd); |
16c2cd71 | 2108 | if (error) |
9f1fafee | 2109 | return ERR_PTR(error); |
1f36f774 | 2110 | audit_inode(pathname, dir); |
67ee3ad2 | 2111 | goto ok; |
1f36f774 | 2112 | } |
67ee3ad2 | 2113 | |
ca344a89 | 2114 | if (!(open_flag & O_CREAT)) { |
bcda7652 | 2115 | int symlink_ok = 0; |
fe2d35ff AV |
2116 | if (nd->last.name[nd->last.len]) |
2117 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
bcda7652 AV |
2118 | if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) |
2119 | symlink_ok = 1; | |
fe2d35ff | 2120 | /* we _can_ be in RCU mode here */ |
ce57dfc1 AV |
2121 | error = walk_component(nd, path, &nd->last, LAST_NORM, |
2122 | !symlink_ok); | |
2123 | if (error < 0) | |
fe2d35ff | 2124 | return ERR_PTR(error); |
ce57dfc1 | 2125 | if (error) /* symlink */ |
fe2d35ff | 2126 | return NULL; |
fe2d35ff | 2127 | /* sayonara */ |
9f1fafee AV |
2128 | error = complete_walk(nd); |
2129 | if (error) | |
2130 | return ERR_PTR(-ECHILD); | |
fe2d35ff AV |
2131 | |
2132 | error = -ENOTDIR; | |
2133 | if (nd->flags & LOOKUP_DIRECTORY) { | |
ce57dfc1 | 2134 | if (!nd->inode->i_op->lookup) |
fe2d35ff AV |
2135 | goto exit; |
2136 | } | |
2137 | audit_inode(pathname, nd->path.dentry); | |
2138 | goto ok; | |
2139 | } | |
2140 | ||
2141 | /* create side of things */ | |
9f1fafee AV |
2142 | error = complete_walk(nd); |
2143 | if (error) | |
2144 | return ERR_PTR(error); | |
fe2d35ff AV |
2145 | |
2146 | audit_inode(pathname, dir); | |
16c2cd71 | 2147 | error = -EISDIR; |
1f36f774 | 2148 | /* trailing slashes? */ |
31e6b01f NP |
2149 | if (nd->last.name[nd->last.len]) |
2150 | goto exit; | |
a2c36b45 | 2151 | |
a1e28038 AV |
2152 | mutex_lock(&dir->d_inode->i_mutex); |
2153 | ||
6c0d46c4 AV |
2154 | dentry = lookup_hash(nd); |
2155 | error = PTR_ERR(dentry); | |
2156 | if (IS_ERR(dentry)) { | |
fb1cc555 AV |
2157 | mutex_unlock(&dir->d_inode->i_mutex); |
2158 | goto exit; | |
2159 | } | |
2160 | ||
6c0d46c4 AV |
2161 | path->dentry = dentry; |
2162 | path->mnt = nd->path.mnt; | |
2163 | ||
fb1cc555 | 2164 | /* Negative dentry, just create the file */ |
6c0d46c4 AV |
2165 | if (!dentry->d_inode) { |
2166 | int mode = op->mode; | |
2167 | if (!IS_POSIXACL(dir->d_inode)) | |
2168 | mode &= ~current_umask(); | |
fb1cc555 AV |
2169 | /* |
2170 | * This write is needed to ensure that a | |
6c0d46c4 | 2171 | * rw->ro transition does not occur between |
fb1cc555 AV |
2172 | * the time when the file is created and when |
2173 | * a permanent write count is taken through | |
2174 | * the 'struct file' in nameidata_to_filp(). | |
2175 | */ | |
2176 | error = mnt_want_write(nd->path.mnt); | |
2177 | if (error) | |
2178 | goto exit_mutex_unlock; | |
ca344a89 | 2179 | want_write = 1; |
9b44f1b3 | 2180 | /* Don't check for write permission, don't truncate */ |
ca344a89 | 2181 | open_flag &= ~O_TRUNC; |
6c0d46c4 | 2182 | will_truncate = 0; |
bcda7652 | 2183 | acc_mode = MAY_OPEN; |
6c0d46c4 AV |
2184 | error = security_path_mknod(&nd->path, dentry, mode, 0); |
2185 | if (error) | |
2186 | goto exit_mutex_unlock; | |
2187 | error = vfs_create(dir->d_inode, dentry, mode, nd); | |
2188 | if (error) | |
2189 | goto exit_mutex_unlock; | |
2190 | mutex_unlock(&dir->d_inode->i_mutex); | |
2191 | dput(nd->path.dentry); | |
2192 | nd->path.dentry = dentry; | |
ca344a89 | 2193 | goto common; |
fb1cc555 AV |
2194 | } |
2195 | ||
2196 | /* | |
2197 | * It already exists. | |
2198 | */ | |
2199 | mutex_unlock(&dir->d_inode->i_mutex); | |
2200 | audit_inode(pathname, path->dentry); | |
2201 | ||
2202 | error = -EEXIST; | |
ca344a89 | 2203 | if (open_flag & O_EXCL) |
fb1cc555 AV |
2204 | goto exit_dput; |
2205 | ||
9875cf80 DH |
2206 | error = follow_managed(path, nd->flags); |
2207 | if (error < 0) | |
2208 | goto exit_dput; | |
fb1cc555 AV |
2209 | |
2210 | error = -ENOENT; | |
2211 | if (!path->dentry->d_inode) | |
2212 | goto exit_dput; | |
9e67f361 AV |
2213 | |
2214 | if (path->dentry->d_inode->i_op->follow_link) | |
fb1cc555 | 2215 | return NULL; |
fb1cc555 AV |
2216 | |
2217 | path_to_nameidata(path, nd); | |
31e6b01f | 2218 | nd->inode = path->dentry->d_inode; |
fb1cc555 | 2219 | error = -EISDIR; |
31e6b01f | 2220 | if (S_ISDIR(nd->inode->i_mode)) |
fb1cc555 | 2221 | goto exit; |
67ee3ad2 | 2222 | ok: |
6c0d46c4 AV |
2223 | if (!S_ISREG(nd->inode->i_mode)) |
2224 | will_truncate = 0; | |
2225 | ||
0f9d1a10 AV |
2226 | if (will_truncate) { |
2227 | error = mnt_want_write(nd->path.mnt); | |
2228 | if (error) | |
2229 | goto exit; | |
ca344a89 | 2230 | want_write = 1; |
0f9d1a10 | 2231 | } |
ca344a89 | 2232 | common: |
bcda7652 | 2233 | error = may_open(&nd->path, acc_mode, open_flag); |
ca344a89 | 2234 | if (error) |
0f9d1a10 | 2235 | goto exit; |
0f9d1a10 AV |
2236 | filp = nameidata_to_filp(nd); |
2237 | if (!IS_ERR(filp)) { | |
2238 | error = ima_file_check(filp, op->acc_mode); | |
2239 | if (error) { | |
2240 | fput(filp); | |
2241 | filp = ERR_PTR(error); | |
2242 | } | |
2243 | } | |
2244 | if (!IS_ERR(filp)) { | |
2245 | if (will_truncate) { | |
2246 | error = handle_truncate(filp); | |
2247 | if (error) { | |
2248 | fput(filp); | |
2249 | filp = ERR_PTR(error); | |
2250 | } | |
2251 | } | |
2252 | } | |
ca344a89 AV |
2253 | out: |
2254 | if (want_write) | |
0f9d1a10 AV |
2255 | mnt_drop_write(nd->path.mnt); |
2256 | path_put(&nd->path); | |
fb1cc555 AV |
2257 | return filp; |
2258 | ||
2259 | exit_mutex_unlock: | |
2260 | mutex_unlock(&dir->d_inode->i_mutex); | |
2261 | exit_dput: | |
2262 | path_put_conditional(path, nd); | |
2263 | exit: | |
ca344a89 AV |
2264 | filp = ERR_PTR(error); |
2265 | goto out; | |
fb1cc555 AV |
2266 | } |
2267 | ||
13aab428 | 2268 | static struct file *path_openat(int dfd, const char *pathname, |
73d049a4 | 2269 | struct nameidata *nd, const struct open_flags *op, int flags) |
1da177e4 | 2270 | { |
fe2d35ff | 2271 | struct file *base = NULL; |
4a3fd211 | 2272 | struct file *filp; |
9850c056 | 2273 | struct path path; |
13aab428 | 2274 | int error; |
31e6b01f NP |
2275 | |
2276 | filp = get_empty_filp(); | |
2277 | if (!filp) | |
2278 | return ERR_PTR(-ENFILE); | |
2279 | ||
47c805dc | 2280 | filp->f_flags = op->open_flag; |
73d049a4 AV |
2281 | nd->intent.open.file = filp; |
2282 | nd->intent.open.flags = open_to_namei_flags(op->open_flag); | |
2283 | nd->intent.open.create_mode = op->mode; | |
31e6b01f | 2284 | |
73d049a4 | 2285 | error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); |
31e6b01f | 2286 | if (unlikely(error)) |
13aab428 | 2287 | goto out_filp; |
31e6b01f | 2288 | |
fe2d35ff | 2289 | current->total_link_count = 0; |
73d049a4 | 2290 | error = link_path_walk(pathname, nd); |
31e6b01f NP |
2291 | if (unlikely(error)) |
2292 | goto out_filp; | |
1da177e4 | 2293 | |
73d049a4 | 2294 | filp = do_last(nd, &path, op, pathname); |
806b681c | 2295 | while (unlikely(!filp)) { /* trailing symlink */ |
7b9337aa | 2296 | struct path link = path; |
def4af30 | 2297 | void *cookie; |
574197e0 | 2298 | if (!(nd->flags & LOOKUP_FOLLOW)) { |
73d049a4 AV |
2299 | path_put_conditional(&path, nd); |
2300 | path_put(&nd->path); | |
40b39136 AV |
2301 | filp = ERR_PTR(-ELOOP); |
2302 | break; | |
2303 | } | |
73d049a4 AV |
2304 | nd->flags |= LOOKUP_PARENT; |
2305 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); | |
574197e0 | 2306 | error = follow_link(&link, nd, &cookie); |
c3e380b0 | 2307 | if (unlikely(error)) |
f1afe9ef | 2308 | filp = ERR_PTR(error); |
c3e380b0 | 2309 | else |
73d049a4 | 2310 | filp = do_last(nd, &path, op, pathname); |
574197e0 | 2311 | put_link(nd, &link, cookie); |
806b681c | 2312 | } |
10fa8e62 | 2313 | out: |
73d049a4 AV |
2314 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) |
2315 | path_put(&nd->root); | |
fe2d35ff AV |
2316 | if (base) |
2317 | fput(base); | |
73d049a4 | 2318 | release_open_intent(nd); |
10fa8e62 | 2319 | return filp; |
1da177e4 | 2320 | |
31e6b01f | 2321 | out_filp: |
806b681c | 2322 | filp = ERR_PTR(error); |
10fa8e62 | 2323 | goto out; |
1da177e4 LT |
2324 | } |
2325 | ||
13aab428 AV |
2326 | struct file *do_filp_open(int dfd, const char *pathname, |
2327 | const struct open_flags *op, int flags) | |
2328 | { | |
73d049a4 | 2329 | struct nameidata nd; |
13aab428 AV |
2330 | struct file *filp; |
2331 | ||
73d049a4 | 2332 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); |
13aab428 | 2333 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
73d049a4 | 2334 | filp = path_openat(dfd, pathname, &nd, op, flags); |
13aab428 | 2335 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
73d049a4 | 2336 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); |
13aab428 AV |
2337 | return filp; |
2338 | } | |
2339 | ||
73d049a4 AV |
2340 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
2341 | const char *name, const struct open_flags *op, int flags) | |
2342 | { | |
2343 | struct nameidata nd; | |
2344 | struct file *file; | |
2345 | ||
2346 | nd.root.mnt = mnt; | |
2347 | nd.root.dentry = dentry; | |
2348 | ||
2349 | flags |= LOOKUP_ROOT; | |
2350 | ||
bcda7652 | 2351 | if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) |
73d049a4 AV |
2352 | return ERR_PTR(-ELOOP); |
2353 | ||
2354 | file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); | |
2355 | if (unlikely(file == ERR_PTR(-ECHILD))) | |
2356 | file = path_openat(-1, name, &nd, op, flags); | |
2357 | if (unlikely(file == ERR_PTR(-ESTALE))) | |
2358 | file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); | |
2359 | return file; | |
2360 | } | |
2361 | ||
ed75e95d | 2362 | struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) |
1da177e4 | 2363 | { |
c663e5d8 | 2364 | struct dentry *dentry = ERR_PTR(-EEXIST); |
ed75e95d AV |
2365 | struct nameidata nd; |
2366 | int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); | |
2367 | if (error) | |
2368 | return ERR_PTR(error); | |
1da177e4 | 2369 | |
c663e5d8 CH |
2370 | /* |
2371 | * Yucky last component or no last component at all? | |
2372 | * (foo/., foo/.., /////) | |
2373 | */ | |
ed75e95d AV |
2374 | if (nd.last_type != LAST_NORM) |
2375 | goto out; | |
2376 | nd.flags &= ~LOOKUP_PARENT; | |
2377 | nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; | |
2378 | nd.intent.open.flags = O_EXCL; | |
c663e5d8 CH |
2379 | |
2380 | /* | |
2381 | * Do the final lookup. | |
2382 | */ | |
ed75e95d AV |
2383 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
2384 | dentry = lookup_hash(&nd); | |
1da177e4 LT |
2385 | if (IS_ERR(dentry)) |
2386 | goto fail; | |
c663e5d8 | 2387 | |
e9baf6e5 AV |
2388 | if (dentry->d_inode) |
2389 | goto eexist; | |
c663e5d8 CH |
2390 | /* |
2391 | * Special case - lookup gave negative, but... we had foo/bar/ | |
2392 | * From the vfs_mknod() POV we just have a negative dentry - | |
2393 | * all is fine. Let's be bastards - you had / on the end, you've | |
2394 | * been asking for (non-existent) directory. -ENOENT for you. | |
2395 | */ | |
ed75e95d | 2396 | if (unlikely(!is_dir && nd.last.name[nd.last.len])) { |
e9baf6e5 AV |
2397 | dput(dentry); |
2398 | dentry = ERR_PTR(-ENOENT); | |
ed75e95d | 2399 | goto fail; |
e9baf6e5 | 2400 | } |
ed75e95d | 2401 | *path = nd.path; |
1da177e4 | 2402 | return dentry; |
e9baf6e5 | 2403 | eexist: |
1da177e4 | 2404 | dput(dentry); |
e9baf6e5 | 2405 | dentry = ERR_PTR(-EEXIST); |
1da177e4 | 2406 | fail: |
ed75e95d AV |
2407 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
2408 | out: | |
2409 | path_put(&nd.path); | |
1da177e4 LT |
2410 | return dentry; |
2411 | } | |
dae6ad8f AV |
2412 | EXPORT_SYMBOL(kern_path_create); |
2413 | ||
2414 | struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) | |
2415 | { | |
2416 | char *tmp = getname(pathname); | |
2417 | struct dentry *res; | |
2418 | if (IS_ERR(tmp)) | |
2419 | return ERR_CAST(tmp); | |
2420 | res = kern_path_create(dfd, tmp, path, is_dir); | |
2421 | putname(tmp); | |
2422 | return res; | |
2423 | } | |
2424 | EXPORT_SYMBOL(user_path_create); | |
2425 | ||
1da177e4 LT |
2426 | int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) |
2427 | { | |
a95164d9 | 2428 | int error = may_create(dir, dentry); |
1da177e4 LT |
2429 | |
2430 | if (error) | |
2431 | return error; | |
2432 | ||
e795b717 SH |
2433 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && |
2434 | !ns_capable(inode_userns(dir), CAP_MKNOD)) | |
1da177e4 LT |
2435 | return -EPERM; |
2436 | ||
acfa4380 | 2437 | if (!dir->i_op->mknod) |
1da177e4 LT |
2438 | return -EPERM; |
2439 | ||
08ce5f16 SH |
2440 | error = devcgroup_inode_mknod(mode, dev); |
2441 | if (error) | |
2442 | return error; | |
2443 | ||
1da177e4 LT |
2444 | error = security_inode_mknod(dir, dentry, mode, dev); |
2445 | if (error) | |
2446 | return error; | |
2447 | ||
1da177e4 | 2448 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 2449 | if (!error) |
f38aa942 | 2450 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2451 | return error; |
2452 | } | |
2453 | ||
463c3197 DH |
2454 | static int may_mknod(mode_t mode) |
2455 | { | |
2456 | switch (mode & S_IFMT) { | |
2457 | case S_IFREG: | |
2458 | case S_IFCHR: | |
2459 | case S_IFBLK: | |
2460 | case S_IFIFO: | |
2461 | case S_IFSOCK: | |
2462 | case 0: /* zero mode translates to S_IFREG */ | |
2463 | return 0; | |
2464 | case S_IFDIR: | |
2465 | return -EPERM; | |
2466 | default: | |
2467 | return -EINVAL; | |
2468 | } | |
2469 | } | |
2470 | ||
2e4d0924 HC |
2471 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, |
2472 | unsigned, dev) | |
1da177e4 | 2473 | { |
2ad94ae6 | 2474 | struct dentry *dentry; |
dae6ad8f AV |
2475 | struct path path; |
2476 | int error; | |
1da177e4 LT |
2477 | |
2478 | if (S_ISDIR(mode)) | |
2479 | return -EPERM; | |
1da177e4 | 2480 | |
dae6ad8f AV |
2481 | dentry = user_path_create(dfd, filename, &path, 0); |
2482 | if (IS_ERR(dentry)) | |
2483 | return PTR_ERR(dentry); | |
2ad94ae6 | 2484 | |
dae6ad8f | 2485 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 2486 | mode &= ~current_umask(); |
463c3197 DH |
2487 | error = may_mknod(mode); |
2488 | if (error) | |
2489 | goto out_dput; | |
dae6ad8f | 2490 | error = mnt_want_write(path.mnt); |
463c3197 DH |
2491 | if (error) |
2492 | goto out_dput; | |
dae6ad8f | 2493 | error = security_path_mknod(&path, dentry, mode, dev); |
be6d3e56 KT |
2494 | if (error) |
2495 | goto out_drop_write; | |
463c3197 | 2496 | switch (mode & S_IFMT) { |
1da177e4 | 2497 | case 0: case S_IFREG: |
dae6ad8f | 2498 | error = vfs_create(path.dentry->d_inode,dentry,mode,NULL); |
1da177e4 LT |
2499 | break; |
2500 | case S_IFCHR: case S_IFBLK: | |
dae6ad8f | 2501 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
2502 | new_decode_dev(dev)); |
2503 | break; | |
2504 | case S_IFIFO: case S_IFSOCK: | |
dae6ad8f | 2505 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 2506 | break; |
1da177e4 | 2507 | } |
be6d3e56 | 2508 | out_drop_write: |
dae6ad8f | 2509 | mnt_drop_write(path.mnt); |
463c3197 DH |
2510 | out_dput: |
2511 | dput(dentry); | |
dae6ad8f AV |
2512 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
2513 | path_put(&path); | |
1da177e4 LT |
2514 | |
2515 | return error; | |
2516 | } | |
2517 | ||
3480b257 | 2518 | SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) |
5590ff0d UD |
2519 | { |
2520 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
2521 | } | |
2522 | ||
1da177e4 LT |
2523 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
2524 | { | |
a95164d9 | 2525 | int error = may_create(dir, dentry); |
1da177e4 LT |
2526 | |
2527 | if (error) | |
2528 | return error; | |
2529 | ||
acfa4380 | 2530 | if (!dir->i_op->mkdir) |
1da177e4 LT |
2531 | return -EPERM; |
2532 | ||
2533 | mode &= (S_IRWXUGO|S_ISVTX); | |
2534 | error = security_inode_mkdir(dir, dentry, mode); | |
2535 | if (error) | |
2536 | return error; | |
2537 | ||
1da177e4 | 2538 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 2539 | if (!error) |
f38aa942 | 2540 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
2541 | return error; |
2542 | } | |
2543 | ||
2e4d0924 | 2544 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) |
1da177e4 | 2545 | { |
6902d925 | 2546 | struct dentry *dentry; |
dae6ad8f AV |
2547 | struct path path; |
2548 | int error; | |
1da177e4 | 2549 | |
dae6ad8f | 2550 | dentry = user_path_create(dfd, pathname, &path, 1); |
6902d925 | 2551 | if (IS_ERR(dentry)) |
dae6ad8f | 2552 | return PTR_ERR(dentry); |
1da177e4 | 2553 | |
dae6ad8f | 2554 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 2555 | mode &= ~current_umask(); |
dae6ad8f | 2556 | error = mnt_want_write(path.mnt); |
463c3197 DH |
2557 | if (error) |
2558 | goto out_dput; | |
dae6ad8f | 2559 | error = security_path_mkdir(&path, dentry, mode); |
be6d3e56 KT |
2560 | if (error) |
2561 | goto out_drop_write; | |
dae6ad8f | 2562 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); |
be6d3e56 | 2563 | out_drop_write: |
dae6ad8f | 2564 | mnt_drop_write(path.mnt); |
463c3197 | 2565 | out_dput: |
6902d925 | 2566 | dput(dentry); |
dae6ad8f AV |
2567 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
2568 | path_put(&path); | |
1da177e4 LT |
2569 | return error; |
2570 | } | |
2571 | ||
3cdad428 | 2572 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) |
5590ff0d UD |
2573 | { |
2574 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
2575 | } | |
2576 | ||
1da177e4 | 2577 | /* |
a71905f0 SW |
2578 | * The dentry_unhash() helper will try to drop the dentry early: we |
2579 | * should have a usage count of 2 if we're the only user of this | |
2580 | * dentry, and if that is true (possibly after pruning the dcache), | |
2581 | * then we drop the dentry now. | |
1da177e4 LT |
2582 | * |
2583 | * A low-level filesystem can, if it choses, legally | |
2584 | * do a | |
2585 | * | |
2586 | * if (!d_unhashed(dentry)) | |
2587 | * return -EBUSY; | |
2588 | * | |
2589 | * if it cannot handle the case of removing a directory | |
2590 | * that is still in use by something else.. | |
2591 | */ | |
2592 | void dentry_unhash(struct dentry *dentry) | |
2593 | { | |
dc168427 | 2594 | shrink_dcache_parent(dentry); |
1da177e4 | 2595 | spin_lock(&dentry->d_lock); |
64252c75 | 2596 | if (dentry->d_count == 1) |
1da177e4 LT |
2597 | __d_drop(dentry); |
2598 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
2599 | } |
2600 | ||
2601 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
2602 | { | |
2603 | int error = may_delete(dir, dentry, 1); | |
2604 | ||
2605 | if (error) | |
2606 | return error; | |
2607 | ||
acfa4380 | 2608 | if (!dir->i_op->rmdir) |
1da177e4 LT |
2609 | return -EPERM; |
2610 | ||
1d2ef590 | 2611 | dget(dentry); |
1b1dcc1b | 2612 | mutex_lock(&dentry->d_inode->i_mutex); |
912dbc15 SW |
2613 | |
2614 | error = -EBUSY; | |
1da177e4 | 2615 | if (d_mountpoint(dentry)) |
912dbc15 SW |
2616 | goto out; |
2617 | ||
2618 | error = security_inode_rmdir(dir, dentry); | |
2619 | if (error) | |
2620 | goto out; | |
2621 | ||
3cebde24 | 2622 | shrink_dcache_parent(dentry); |
912dbc15 SW |
2623 | error = dir->i_op->rmdir(dir, dentry); |
2624 | if (error) | |
2625 | goto out; | |
2626 | ||
2627 | dentry->d_inode->i_flags |= S_DEAD; | |
2628 | dont_mount(dentry); | |
2629 | ||
2630 | out: | |
1b1dcc1b | 2631 | mutex_unlock(&dentry->d_inode->i_mutex); |
1d2ef590 | 2632 | dput(dentry); |
912dbc15 | 2633 | if (!error) |
1da177e4 | 2634 | d_delete(dentry); |
1da177e4 LT |
2635 | return error; |
2636 | } | |
2637 | ||
5590ff0d | 2638 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
2639 | { |
2640 | int error = 0; | |
2641 | char * name; | |
2642 | struct dentry *dentry; | |
2643 | struct nameidata nd; | |
2644 | ||
2ad94ae6 | 2645 | error = user_path_parent(dfd, pathname, &nd, &name); |
1da177e4 | 2646 | if (error) |
2ad94ae6 | 2647 | return error; |
1da177e4 LT |
2648 | |
2649 | switch(nd.last_type) { | |
0612d9fb OH |
2650 | case LAST_DOTDOT: |
2651 | error = -ENOTEMPTY; | |
2652 | goto exit1; | |
2653 | case LAST_DOT: | |
2654 | error = -EINVAL; | |
2655 | goto exit1; | |
2656 | case LAST_ROOT: | |
2657 | error = -EBUSY; | |
2658 | goto exit1; | |
1da177e4 | 2659 | } |
0612d9fb OH |
2660 | |
2661 | nd.flags &= ~LOOKUP_PARENT; | |
2662 | ||
4ac91378 | 2663 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2664 | dentry = lookup_hash(&nd); |
1da177e4 | 2665 | error = PTR_ERR(dentry); |
6902d925 DH |
2666 | if (IS_ERR(dentry)) |
2667 | goto exit2; | |
e6bc45d6 TT |
2668 | if (!dentry->d_inode) { |
2669 | error = -ENOENT; | |
2670 | goto exit3; | |
2671 | } | |
0622753b DH |
2672 | error = mnt_want_write(nd.path.mnt); |
2673 | if (error) | |
2674 | goto exit3; | |
be6d3e56 KT |
2675 | error = security_path_rmdir(&nd.path, dentry); |
2676 | if (error) | |
2677 | goto exit4; | |
4ac91378 | 2678 | error = vfs_rmdir(nd.path.dentry->d_inode, dentry); |
be6d3e56 | 2679 | exit4: |
0622753b DH |
2680 | mnt_drop_write(nd.path.mnt); |
2681 | exit3: | |
6902d925 DH |
2682 | dput(dentry); |
2683 | exit2: | |
4ac91378 | 2684 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 | 2685 | exit1: |
1d957f9b | 2686 | path_put(&nd.path); |
1da177e4 LT |
2687 | putname(name); |
2688 | return error; | |
2689 | } | |
2690 | ||
3cdad428 | 2691 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
2692 | { |
2693 | return do_rmdir(AT_FDCWD, pathname); | |
2694 | } | |
2695 | ||
1da177e4 LT |
2696 | int vfs_unlink(struct inode *dir, struct dentry *dentry) |
2697 | { | |
2698 | int error = may_delete(dir, dentry, 0); | |
2699 | ||
2700 | if (error) | |
2701 | return error; | |
2702 | ||
acfa4380 | 2703 | if (!dir->i_op->unlink) |
1da177e4 LT |
2704 | return -EPERM; |
2705 | ||
1b1dcc1b | 2706 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2707 | if (d_mountpoint(dentry)) |
2708 | error = -EBUSY; | |
2709 | else { | |
2710 | error = security_inode_unlink(dir, dentry); | |
bec1052e | 2711 | if (!error) { |
1da177e4 | 2712 | error = dir->i_op->unlink(dir, dentry); |
bec1052e | 2713 | if (!error) |
d83c49f3 | 2714 | dont_mount(dentry); |
bec1052e | 2715 | } |
1da177e4 | 2716 | } |
1b1dcc1b | 2717 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2718 | |
2719 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
2720 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
ece95912 | 2721 | fsnotify_link_count(dentry->d_inode); |
e234f35c | 2722 | d_delete(dentry); |
1da177e4 | 2723 | } |
0eeca283 | 2724 | |
1da177e4 LT |
2725 | return error; |
2726 | } | |
2727 | ||
2728 | /* | |
2729 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 2730 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
2731 | * writeout happening, and we don't want to prevent access to the directory |
2732 | * while waiting on the I/O. | |
2733 | */ | |
5590ff0d | 2734 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 2735 | { |
2ad94ae6 AV |
2736 | int error; |
2737 | char *name; | |
1da177e4 LT |
2738 | struct dentry *dentry; |
2739 | struct nameidata nd; | |
2740 | struct inode *inode = NULL; | |
2741 | ||
2ad94ae6 | 2742 | error = user_path_parent(dfd, pathname, &nd, &name); |
1da177e4 | 2743 | if (error) |
2ad94ae6 AV |
2744 | return error; |
2745 | ||
1da177e4 LT |
2746 | error = -EISDIR; |
2747 | if (nd.last_type != LAST_NORM) | |
2748 | goto exit1; | |
0612d9fb OH |
2749 | |
2750 | nd.flags &= ~LOOKUP_PARENT; | |
2751 | ||
4ac91378 | 2752 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2753 | dentry = lookup_hash(&nd); |
1da177e4 LT |
2754 | error = PTR_ERR(dentry); |
2755 | if (!IS_ERR(dentry)) { | |
2756 | /* Why not before? Because we want correct error value */ | |
50338b88 TE |
2757 | if (nd.last.name[nd.last.len]) |
2758 | goto slashes; | |
1da177e4 | 2759 | inode = dentry->d_inode; |
50338b88 | 2760 | if (!inode) |
e6bc45d6 TT |
2761 | goto slashes; |
2762 | ihold(inode); | |
0622753b DH |
2763 | error = mnt_want_write(nd.path.mnt); |
2764 | if (error) | |
2765 | goto exit2; | |
be6d3e56 KT |
2766 | error = security_path_unlink(&nd.path, dentry); |
2767 | if (error) | |
2768 | goto exit3; | |
4ac91378 | 2769 | error = vfs_unlink(nd.path.dentry->d_inode, dentry); |
be6d3e56 | 2770 | exit3: |
0622753b | 2771 | mnt_drop_write(nd.path.mnt); |
1da177e4 LT |
2772 | exit2: |
2773 | dput(dentry); | |
2774 | } | |
4ac91378 | 2775 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 LT |
2776 | if (inode) |
2777 | iput(inode); /* truncate the inode here */ | |
2778 | exit1: | |
1d957f9b | 2779 | path_put(&nd.path); |
1da177e4 LT |
2780 | putname(name); |
2781 | return error; | |
2782 | ||
2783 | slashes: | |
2784 | error = !dentry->d_inode ? -ENOENT : | |
2785 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; | |
2786 | goto exit2; | |
2787 | } | |
2788 | ||
2e4d0924 | 2789 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
2790 | { |
2791 | if ((flag & ~AT_REMOVEDIR) != 0) | |
2792 | return -EINVAL; | |
2793 | ||
2794 | if (flag & AT_REMOVEDIR) | |
2795 | return do_rmdir(dfd, pathname); | |
2796 | ||
2797 | return do_unlinkat(dfd, pathname); | |
2798 | } | |
2799 | ||
3480b257 | 2800 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
2801 | { |
2802 | return do_unlinkat(AT_FDCWD, pathname); | |
2803 | } | |
2804 | ||
db2e747b | 2805 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 2806 | { |
a95164d9 | 2807 | int error = may_create(dir, dentry); |
1da177e4 LT |
2808 | |
2809 | if (error) | |
2810 | return error; | |
2811 | ||
acfa4380 | 2812 | if (!dir->i_op->symlink) |
1da177e4 LT |
2813 | return -EPERM; |
2814 | ||
2815 | error = security_inode_symlink(dir, dentry, oldname); | |
2816 | if (error) | |
2817 | return error; | |
2818 | ||
1da177e4 | 2819 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 2820 | if (!error) |
f38aa942 | 2821 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2822 | return error; |
2823 | } | |
2824 | ||
2e4d0924 HC |
2825 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
2826 | int, newdfd, const char __user *, newname) | |
1da177e4 | 2827 | { |
2ad94ae6 AV |
2828 | int error; |
2829 | char *from; | |
6902d925 | 2830 | struct dentry *dentry; |
dae6ad8f | 2831 | struct path path; |
1da177e4 LT |
2832 | |
2833 | from = getname(oldname); | |
2ad94ae6 | 2834 | if (IS_ERR(from)) |
1da177e4 | 2835 | return PTR_ERR(from); |
1da177e4 | 2836 | |
dae6ad8f | 2837 | dentry = user_path_create(newdfd, newname, &path, 0); |
6902d925 DH |
2838 | error = PTR_ERR(dentry); |
2839 | if (IS_ERR(dentry)) | |
dae6ad8f | 2840 | goto out_putname; |
6902d925 | 2841 | |
dae6ad8f | 2842 | error = mnt_want_write(path.mnt); |
75c3f29d DH |
2843 | if (error) |
2844 | goto out_dput; | |
dae6ad8f | 2845 | error = security_path_symlink(&path, dentry, from); |
be6d3e56 KT |
2846 | if (error) |
2847 | goto out_drop_write; | |
dae6ad8f | 2848 | error = vfs_symlink(path.dentry->d_inode, dentry, from); |
be6d3e56 | 2849 | out_drop_write: |
dae6ad8f | 2850 | mnt_drop_write(path.mnt); |
75c3f29d | 2851 | out_dput: |
6902d925 | 2852 | dput(dentry); |
dae6ad8f AV |
2853 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
2854 | path_put(&path); | |
6902d925 | 2855 | out_putname: |
1da177e4 LT |
2856 | putname(from); |
2857 | return error; | |
2858 | } | |
2859 | ||
3480b257 | 2860 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
2861 | { |
2862 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
2863 | } | |
2864 | ||
1da177e4 LT |
2865 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
2866 | { | |
2867 | struct inode *inode = old_dentry->d_inode; | |
2868 | int error; | |
2869 | ||
2870 | if (!inode) | |
2871 | return -ENOENT; | |
2872 | ||
a95164d9 | 2873 | error = may_create(dir, new_dentry); |
1da177e4 LT |
2874 | if (error) |
2875 | return error; | |
2876 | ||
2877 | if (dir->i_sb != inode->i_sb) | |
2878 | return -EXDEV; | |
2879 | ||
2880 | /* | |
2881 | * A link to an append-only or immutable file cannot be created. | |
2882 | */ | |
2883 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
2884 | return -EPERM; | |
acfa4380 | 2885 | if (!dir->i_op->link) |
1da177e4 | 2886 | return -EPERM; |
7e79eedb | 2887 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
2888 | return -EPERM; |
2889 | ||
2890 | error = security_inode_link(old_dentry, dir, new_dentry); | |
2891 | if (error) | |
2892 | return error; | |
2893 | ||
7e79eedb | 2894 | mutex_lock(&inode->i_mutex); |
aae8a97d AK |
2895 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
2896 | if (inode->i_nlink == 0) | |
2897 | error = -ENOENT; | |
2898 | else | |
2899 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
7e79eedb | 2900 | mutex_unlock(&inode->i_mutex); |
e31e14ec | 2901 | if (!error) |
7e79eedb | 2902 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
2903 | return error; |
2904 | } | |
2905 | ||
2906 | /* | |
2907 | * Hardlinks are often used in delicate situations. We avoid | |
2908 | * security-related surprises by not following symlinks on the | |
2909 | * newname. --KAB | |
2910 | * | |
2911 | * We don't follow them on the oldname either to be compatible | |
2912 | * with linux 2.0, and to avoid hard-linking to directories | |
2913 | * and other special files. --ADM | |
2914 | */ | |
2e4d0924 HC |
2915 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
2916 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
2917 | { |
2918 | struct dentry *new_dentry; | |
dae6ad8f | 2919 | struct path old_path, new_path; |
11a7b371 | 2920 | int how = 0; |
1da177e4 | 2921 | int error; |
1da177e4 | 2922 | |
11a7b371 | 2923 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
c04030e1 | 2924 | return -EINVAL; |
11a7b371 AK |
2925 | /* |
2926 | * To use null names we require CAP_DAC_READ_SEARCH | |
2927 | * This ensures that not everyone will be able to create | |
2928 | * handlink using the passed filedescriptor. | |
2929 | */ | |
2930 | if (flags & AT_EMPTY_PATH) { | |
2931 | if (!capable(CAP_DAC_READ_SEARCH)) | |
2932 | return -ENOENT; | |
2933 | how = LOOKUP_EMPTY; | |
2934 | } | |
2935 | ||
2936 | if (flags & AT_SYMLINK_FOLLOW) | |
2937 | how |= LOOKUP_FOLLOW; | |
c04030e1 | 2938 | |
11a7b371 | 2939 | error = user_path_at(olddfd, oldname, how, &old_path); |
1da177e4 | 2940 | if (error) |
2ad94ae6 AV |
2941 | return error; |
2942 | ||
dae6ad8f | 2943 | new_dentry = user_path_create(newdfd, newname, &new_path, 0); |
1da177e4 | 2944 | error = PTR_ERR(new_dentry); |
6902d925 | 2945 | if (IS_ERR(new_dentry)) |
dae6ad8f AV |
2946 | goto out; |
2947 | ||
2948 | error = -EXDEV; | |
2949 | if (old_path.mnt != new_path.mnt) | |
2950 | goto out_dput; | |
2951 | error = mnt_want_write(new_path.mnt); | |
75c3f29d DH |
2952 | if (error) |
2953 | goto out_dput; | |
dae6ad8f | 2954 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
be6d3e56 KT |
2955 | if (error) |
2956 | goto out_drop_write; | |
dae6ad8f | 2957 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); |
be6d3e56 | 2958 | out_drop_write: |
dae6ad8f | 2959 | mnt_drop_write(new_path.mnt); |
75c3f29d | 2960 | out_dput: |
6902d925 | 2961 | dput(new_dentry); |
dae6ad8f AV |
2962 | mutex_unlock(&new_path.dentry->d_inode->i_mutex); |
2963 | path_put(&new_path); | |
1da177e4 | 2964 | out: |
2d8f3038 | 2965 | path_put(&old_path); |
1da177e4 LT |
2966 | |
2967 | return error; | |
2968 | } | |
2969 | ||
3480b257 | 2970 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 2971 | { |
c04030e1 | 2972 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
2973 | } |
2974 | ||
1da177e4 LT |
2975 | /* |
2976 | * The worst of all namespace operations - renaming directory. "Perverted" | |
2977 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
2978 | * Problems: | |
2979 | * a) we can get into loop creation. Check is done in is_subdir(). | |
2980 | * b) race potential - two innocent renames can create a loop together. | |
2981 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 2982 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 LT |
2983 | * story. |
2984 | * c) we have to lock _three_ objects - parents and victim (if it exists). | |
1b1dcc1b | 2985 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
2986 | * whether the target exists). Solution: try to be smart with locking |
2987 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 2988 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
2989 | * move will be locked. Thus we can rank directories by the tree |
2990 | * (ancestors first) and rank all non-directories after them. | |
2991 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 2992 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
2993 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
2994 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
2995 | * we'd better make sure that there's no link(2) for them. | |
e4eaac06 | 2996 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
1b1dcc1b | 2997 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 2998 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
c41b20e7 | 2999 | * ->i_mutex on parents, which works but leads to some truly excessive |
1da177e4 LT |
3000 | * locking]. |
3001 | */ | |
75c96f85 AB |
3002 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
3003 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
3004 | { |
3005 | int error = 0; | |
9055cba7 | 3006 | struct inode *target = new_dentry->d_inode; |
1da177e4 LT |
3007 | |
3008 | /* | |
3009 | * If we are going to change the parent - check write permissions, | |
3010 | * we'll need to flip '..'. | |
3011 | */ | |
3012 | if (new_dir != old_dir) { | |
f419a2e3 | 3013 | error = inode_permission(old_dentry->d_inode, MAY_WRITE); |
1da177e4 LT |
3014 | if (error) |
3015 | return error; | |
3016 | } | |
3017 | ||
3018 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
3019 | if (error) | |
3020 | return error; | |
3021 | ||
1d2ef590 | 3022 | dget(new_dentry); |
d83c49f3 | 3023 | if (target) |
1b1dcc1b | 3024 | mutex_lock(&target->i_mutex); |
9055cba7 SW |
3025 | |
3026 | error = -EBUSY; | |
3027 | if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) | |
3028 | goto out; | |
3029 | ||
3cebde24 SW |
3030 | if (target) |
3031 | shrink_dcache_parent(new_dentry); | |
9055cba7 SW |
3032 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
3033 | if (error) | |
3034 | goto out; | |
3035 | ||
1da177e4 | 3036 | if (target) { |
9055cba7 SW |
3037 | target->i_flags |= S_DEAD; |
3038 | dont_mount(new_dentry); | |
1da177e4 | 3039 | } |
9055cba7 SW |
3040 | out: |
3041 | if (target) | |
3042 | mutex_unlock(&target->i_mutex); | |
1d2ef590 | 3043 | dput(new_dentry); |
e31e14ec | 3044 | if (!error) |
349457cc MF |
3045 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
3046 | d_move(old_dentry,new_dentry); | |
1da177e4 LT |
3047 | return error; |
3048 | } | |
3049 | ||
75c96f85 AB |
3050 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
3051 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 | 3052 | { |
51892bbb | 3053 | struct inode *target = new_dentry->d_inode; |
1da177e4 LT |
3054 | int error; |
3055 | ||
3056 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
3057 | if (error) | |
3058 | return error; | |
3059 | ||
3060 | dget(new_dentry); | |
1da177e4 | 3061 | if (target) |
1b1dcc1b | 3062 | mutex_lock(&target->i_mutex); |
51892bbb SW |
3063 | |
3064 | error = -EBUSY; | |
1da177e4 | 3065 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
51892bbb SW |
3066 | goto out; |
3067 | ||
3068 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
3069 | if (error) | |
3070 | goto out; | |
3071 | ||
3072 | if (target) | |
3073 | dont_mount(new_dentry); | |
3074 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) | |
3075 | d_move(old_dentry, new_dentry); | |
3076 | out: | |
1da177e4 | 3077 | if (target) |
1b1dcc1b | 3078 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
3079 | dput(new_dentry); |
3080 | return error; | |
3081 | } | |
3082 | ||
3083 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, | |
3084 | struct inode *new_dir, struct dentry *new_dentry) | |
3085 | { | |
3086 | int error; | |
3087 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); | |
59b0df21 | 3088 | const unsigned char *old_name; |
1da177e4 LT |
3089 | |
3090 | if (old_dentry->d_inode == new_dentry->d_inode) | |
3091 | return 0; | |
3092 | ||
3093 | error = may_delete(old_dir, old_dentry, is_dir); | |
3094 | if (error) | |
3095 | return error; | |
3096 | ||
3097 | if (!new_dentry->d_inode) | |
a95164d9 | 3098 | error = may_create(new_dir, new_dentry); |
1da177e4 LT |
3099 | else |
3100 | error = may_delete(new_dir, new_dentry, is_dir); | |
3101 | if (error) | |
3102 | return error; | |
3103 | ||
acfa4380 | 3104 | if (!old_dir->i_op->rename) |
1da177e4 LT |
3105 | return -EPERM; |
3106 | ||
0eeca283 RL |
3107 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
3108 | ||
1da177e4 LT |
3109 | if (is_dir) |
3110 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); | |
3111 | else | |
3112 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); | |
123df294 AV |
3113 | if (!error) |
3114 | fsnotify_move(old_dir, new_dir, old_name, is_dir, | |
5a190ae6 | 3115 | new_dentry->d_inode, old_dentry); |
0eeca283 RL |
3116 | fsnotify_oldname_free(old_name); |
3117 | ||
1da177e4 LT |
3118 | return error; |
3119 | } | |
3120 | ||
2e4d0924 HC |
3121 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
3122 | int, newdfd, const char __user *, newname) | |
1da177e4 | 3123 | { |
2ad94ae6 AV |
3124 | struct dentry *old_dir, *new_dir; |
3125 | struct dentry *old_dentry, *new_dentry; | |
3126 | struct dentry *trap; | |
1da177e4 | 3127 | struct nameidata oldnd, newnd; |
2ad94ae6 AV |
3128 | char *from; |
3129 | char *to; | |
3130 | int error; | |
1da177e4 | 3131 | |
2ad94ae6 | 3132 | error = user_path_parent(olddfd, oldname, &oldnd, &from); |
1da177e4 LT |
3133 | if (error) |
3134 | goto exit; | |
3135 | ||
2ad94ae6 | 3136 | error = user_path_parent(newdfd, newname, &newnd, &to); |
1da177e4 LT |
3137 | if (error) |
3138 | goto exit1; | |
3139 | ||
3140 | error = -EXDEV; | |
4ac91378 | 3141 | if (oldnd.path.mnt != newnd.path.mnt) |
1da177e4 LT |
3142 | goto exit2; |
3143 | ||
4ac91378 | 3144 | old_dir = oldnd.path.dentry; |
1da177e4 LT |
3145 | error = -EBUSY; |
3146 | if (oldnd.last_type != LAST_NORM) | |
3147 | goto exit2; | |
3148 | ||
4ac91378 | 3149 | new_dir = newnd.path.dentry; |
1da177e4 LT |
3150 | if (newnd.last_type != LAST_NORM) |
3151 | goto exit2; | |
3152 | ||
0612d9fb OH |
3153 | oldnd.flags &= ~LOOKUP_PARENT; |
3154 | newnd.flags &= ~LOOKUP_PARENT; | |
4e9ed2f8 | 3155 | newnd.flags |= LOOKUP_RENAME_TARGET; |
0612d9fb | 3156 | |
1da177e4 LT |
3157 | trap = lock_rename(new_dir, old_dir); |
3158 | ||
49705b77 | 3159 | old_dentry = lookup_hash(&oldnd); |
1da177e4 LT |
3160 | error = PTR_ERR(old_dentry); |
3161 | if (IS_ERR(old_dentry)) | |
3162 | goto exit3; | |
3163 | /* source must exist */ | |
3164 | error = -ENOENT; | |
3165 | if (!old_dentry->d_inode) | |
3166 | goto exit4; | |
3167 | /* unless the source is a directory trailing slashes give -ENOTDIR */ | |
3168 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { | |
3169 | error = -ENOTDIR; | |
3170 | if (oldnd.last.name[oldnd.last.len]) | |
3171 | goto exit4; | |
3172 | if (newnd.last.name[newnd.last.len]) | |
3173 | goto exit4; | |
3174 | } | |
3175 | /* source should not be ancestor of target */ | |
3176 | error = -EINVAL; | |
3177 | if (old_dentry == trap) | |
3178 | goto exit4; | |
49705b77 | 3179 | new_dentry = lookup_hash(&newnd); |
1da177e4 LT |
3180 | error = PTR_ERR(new_dentry); |
3181 | if (IS_ERR(new_dentry)) | |
3182 | goto exit4; | |
3183 | /* target should not be an ancestor of source */ | |
3184 | error = -ENOTEMPTY; | |
3185 | if (new_dentry == trap) | |
3186 | goto exit5; | |
3187 | ||
9079b1eb DH |
3188 | error = mnt_want_write(oldnd.path.mnt); |
3189 | if (error) | |
3190 | goto exit5; | |
be6d3e56 KT |
3191 | error = security_path_rename(&oldnd.path, old_dentry, |
3192 | &newnd.path, new_dentry); | |
3193 | if (error) | |
3194 | goto exit6; | |
1da177e4 LT |
3195 | error = vfs_rename(old_dir->d_inode, old_dentry, |
3196 | new_dir->d_inode, new_dentry); | |
be6d3e56 | 3197 | exit6: |
9079b1eb | 3198 | mnt_drop_write(oldnd.path.mnt); |
1da177e4 LT |
3199 | exit5: |
3200 | dput(new_dentry); | |
3201 | exit4: | |
3202 | dput(old_dentry); | |
3203 | exit3: | |
3204 | unlock_rename(new_dir, old_dir); | |
3205 | exit2: | |
1d957f9b | 3206 | path_put(&newnd.path); |
2ad94ae6 | 3207 | putname(to); |
1da177e4 | 3208 | exit1: |
1d957f9b | 3209 | path_put(&oldnd.path); |
1da177e4 | 3210 | putname(from); |
2ad94ae6 | 3211 | exit: |
1da177e4 LT |
3212 | return error; |
3213 | } | |
3214 | ||
a26eab24 | 3215 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
3216 | { |
3217 | return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); | |
3218 | } | |
3219 | ||
1da177e4 LT |
3220 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
3221 | { | |
3222 | int len; | |
3223 | ||
3224 | len = PTR_ERR(link); | |
3225 | if (IS_ERR(link)) | |
3226 | goto out; | |
3227 | ||
3228 | len = strlen(link); | |
3229 | if (len > (unsigned) buflen) | |
3230 | len = buflen; | |
3231 | if (copy_to_user(buffer, link, len)) | |
3232 | len = -EFAULT; | |
3233 | out: | |
3234 | return len; | |
3235 | } | |
3236 | ||
3237 | /* | |
3238 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
3239 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
3240 | * using) it for any given inode is up to filesystem. | |
3241 | */ | |
3242 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
3243 | { | |
3244 | struct nameidata nd; | |
cc314eef | 3245 | void *cookie; |
694a1764 | 3246 | int res; |
cc314eef | 3247 | |
1da177e4 | 3248 | nd.depth = 0; |
cc314eef | 3249 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
694a1764 MS |
3250 | if (IS_ERR(cookie)) |
3251 | return PTR_ERR(cookie); | |
3252 | ||
3253 | res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); | |
3254 | if (dentry->d_inode->i_op->put_link) | |
3255 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); | |
3256 | return res; | |
1da177e4 LT |
3257 | } |
3258 | ||
3259 | int vfs_follow_link(struct nameidata *nd, const char *link) | |
3260 | { | |
3261 | return __vfs_follow_link(nd, link); | |
3262 | } | |
3263 | ||
3264 | /* get the link contents into pagecache */ | |
3265 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
3266 | { | |
ebd09abb DG |
3267 | char *kaddr; |
3268 | struct page *page; | |
1da177e4 | 3269 | struct address_space *mapping = dentry->d_inode->i_mapping; |
090d2b18 | 3270 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 3271 | if (IS_ERR(page)) |
6fe6900e | 3272 | return (char*)page; |
1da177e4 | 3273 | *ppage = page; |
ebd09abb DG |
3274 | kaddr = kmap(page); |
3275 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); | |
3276 | return kaddr; | |
1da177e4 LT |
3277 | } |
3278 | ||
3279 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
3280 | { | |
3281 | struct page *page = NULL; | |
3282 | char *s = page_getlink(dentry, &page); | |
3283 | int res = vfs_readlink(dentry,buffer,buflen,s); | |
3284 | if (page) { | |
3285 | kunmap(page); | |
3286 | page_cache_release(page); | |
3287 | } | |
3288 | return res; | |
3289 | } | |
3290 | ||
cc314eef | 3291 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 3292 | { |
cc314eef | 3293 | struct page *page = NULL; |
1da177e4 | 3294 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 3295 | return page; |
1da177e4 LT |
3296 | } |
3297 | ||
cc314eef | 3298 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 3299 | { |
cc314eef LT |
3300 | struct page *page = cookie; |
3301 | ||
3302 | if (page) { | |
1da177e4 LT |
3303 | kunmap(page); |
3304 | page_cache_release(page); | |
1da177e4 LT |
3305 | } |
3306 | } | |
3307 | ||
54566b2c NP |
3308 | /* |
3309 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
3310 | */ | |
3311 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
3312 | { |
3313 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 3314 | struct page *page; |
afddba49 | 3315 | void *fsdata; |
beb497ab | 3316 | int err; |
1da177e4 | 3317 | char *kaddr; |
54566b2c NP |
3318 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
3319 | if (nofs) | |
3320 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 3321 | |
7e53cac4 | 3322 | retry: |
afddba49 | 3323 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 3324 | flags, &page, &fsdata); |
1da177e4 | 3325 | if (err) |
afddba49 NP |
3326 | goto fail; |
3327 | ||
1da177e4 LT |
3328 | kaddr = kmap_atomic(page, KM_USER0); |
3329 | memcpy(kaddr, symname, len-1); | |
3330 | kunmap_atomic(kaddr, KM_USER0); | |
afddba49 NP |
3331 | |
3332 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
3333 | page, fsdata); | |
1da177e4 LT |
3334 | if (err < 0) |
3335 | goto fail; | |
afddba49 NP |
3336 | if (err < len-1) |
3337 | goto retry; | |
3338 | ||
1da177e4 LT |
3339 | mark_inode_dirty(inode); |
3340 | return 0; | |
1da177e4 LT |
3341 | fail: |
3342 | return err; | |
3343 | } | |
3344 | ||
0adb25d2 KK |
3345 | int page_symlink(struct inode *inode, const char *symname, int len) |
3346 | { | |
3347 | return __page_symlink(inode, symname, len, | |
54566b2c | 3348 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
0adb25d2 KK |
3349 | } |
3350 | ||
92e1d5be | 3351 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
3352 | .readlink = generic_readlink, |
3353 | .follow_link = page_follow_link_light, | |
3354 | .put_link = page_put_link, | |
3355 | }; | |
3356 | ||
2d8f3038 | 3357 | EXPORT_SYMBOL(user_path_at); |
cc53ce53 | 3358 | EXPORT_SYMBOL(follow_down_one); |
1da177e4 LT |
3359 | EXPORT_SYMBOL(follow_down); |
3360 | EXPORT_SYMBOL(follow_up); | |
3361 | EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ | |
3362 | EXPORT_SYMBOL(getname); | |
3363 | EXPORT_SYMBOL(lock_rename); | |
1da177e4 LT |
3364 | EXPORT_SYMBOL(lookup_one_len); |
3365 | EXPORT_SYMBOL(page_follow_link_light); | |
3366 | EXPORT_SYMBOL(page_put_link); | |
3367 | EXPORT_SYMBOL(page_readlink); | |
0adb25d2 | 3368 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 LT |
3369 | EXPORT_SYMBOL(page_symlink); |
3370 | EXPORT_SYMBOL(page_symlink_inode_operations); | |
d1811465 | 3371 | EXPORT_SYMBOL(kern_path); |
16f18200 | 3372 | EXPORT_SYMBOL(vfs_path_lookup); |
f419a2e3 | 3373 | EXPORT_SYMBOL(inode_permission); |
1da177e4 LT |
3374 | EXPORT_SYMBOL(unlock_rename); |
3375 | EXPORT_SYMBOL(vfs_create); | |
3376 | EXPORT_SYMBOL(vfs_follow_link); | |
3377 | EXPORT_SYMBOL(vfs_link); | |
3378 | EXPORT_SYMBOL(vfs_mkdir); | |
3379 | EXPORT_SYMBOL(vfs_mknod); | |
3380 | EXPORT_SYMBOL(generic_permission); | |
3381 | EXPORT_SYMBOL(vfs_readlink); | |
3382 | EXPORT_SYMBOL(vfs_rename); | |
3383 | EXPORT_SYMBOL(vfs_rmdir); | |
3384 | EXPORT_SYMBOL(vfs_symlink); | |
3385 | EXPORT_SYMBOL(vfs_unlink); | |
3386 | EXPORT_SYMBOL(dentry_unhash); | |
3387 | EXPORT_SYMBOL(generic_readlink); |