Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/namei.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * Some corrections by tytso. | |
9 | */ | |
10 | ||
11 | /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname | |
12 | * lookup logic. | |
13 | */ | |
14 | /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. | |
15 | */ | |
16 | ||
17 | #include <linux/init.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/slab.h> | |
20 | #include <linux/fs.h> | |
21 | #include <linux/namei.h> | |
1da177e4 | 22 | #include <linux/pagemap.h> |
0eeca283 | 23 | #include <linux/fsnotify.h> |
1da177e4 LT |
24 | #include <linux/personality.h> |
25 | #include <linux/security.h> | |
6146f0d5 | 26 | #include <linux/ima.h> |
1da177e4 LT |
27 | #include <linux/syscalls.h> |
28 | #include <linux/mount.h> | |
29 | #include <linux/audit.h> | |
16f7e0fe | 30 | #include <linux/capability.h> |
834f2a4a | 31 | #include <linux/file.h> |
5590ff0d | 32 | #include <linux/fcntl.h> |
08ce5f16 | 33 | #include <linux/device_cgroup.h> |
5ad4e53b | 34 | #include <linux/fs_struct.h> |
1da177e4 LT |
35 | #include <asm/uaccess.h> |
36 | ||
e81e3f4d EP |
37 | #include "internal.h" |
38 | ||
1da177e4 LT |
39 | /* [Feb-1997 T. Schoebel-Theuer] |
40 | * Fundamental changes in the pathname lookup mechanisms (namei) | |
41 | * were necessary because of omirr. The reason is that omirr needs | |
42 | * to know the _real_ pathname, not the user-supplied one, in case | |
43 | * of symlinks (and also when transname replacements occur). | |
44 | * | |
45 | * The new code replaces the old recursive symlink resolution with | |
46 | * an iterative one (in case of non-nested symlink chains). It does | |
47 | * this with calls to <fs>_follow_link(). | |
48 | * As a side effect, dir_namei(), _namei() and follow_link() are now | |
49 | * replaced with a single function lookup_dentry() that can handle all | |
50 | * the special cases of the former code. | |
51 | * | |
52 | * With the new dcache, the pathname is stored at each inode, at least as | |
53 | * long as the refcount of the inode is positive. As a side effect, the | |
54 | * size of the dcache depends on the inode cache and thus is dynamic. | |
55 | * | |
56 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink | |
57 | * resolution to correspond with current state of the code. | |
58 | * | |
59 | * Note that the symlink resolution is not *completely* iterative. | |
60 | * There is still a significant amount of tail- and mid- recursion in | |
61 | * the algorithm. Also, note that <fs>_readlink() is not used in | |
62 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() | |
63 | * may return different results than <fs>_follow_link(). Many virtual | |
64 | * filesystems (including /proc) exhibit this behavior. | |
65 | */ | |
66 | ||
67 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: | |
68 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL | |
69 | * and the name already exists in form of a symlink, try to create the new | |
70 | * name indicated by the symlink. The old code always complained that the | |
71 | * name already exists, due to not following the symlink even if its target | |
72 | * is nonexistent. The new semantics affects also mknod() and link() when | |
25985edc | 73 | * the name is a symlink pointing to a non-existent name. |
1da177e4 LT |
74 | * |
75 | * I don't know which semantics is the right one, since I have no access | |
76 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" | |
77 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the | |
78 | * "old" one. Personally, I think the new semantics is much more logical. | |
79 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing | |
80 | * file does succeed in both HP-UX and SunOs, but not in Solaris | |
81 | * and in the old Linux semantics. | |
82 | */ | |
83 | ||
84 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink | |
85 | * semantics. See the comments in "open_namei" and "do_link" below. | |
86 | * | |
87 | * [10-Sep-98 Alan Modra] Another symlink change. | |
88 | */ | |
89 | ||
90 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: | |
91 | * inside the path - always follow. | |
92 | * in the last component in creation/removal/renaming - never follow. | |
93 | * if LOOKUP_FOLLOW passed - follow. | |
94 | * if the pathname has trailing slashes - follow. | |
95 | * otherwise - don't follow. | |
96 | * (applied in that order). | |
97 | * | |
98 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT | |
99 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. | |
100 | * During the 2.4 we need to fix the userland stuff depending on it - | |
101 | * hopefully we will be able to get rid of that wart in 2.5. So far only | |
102 | * XEmacs seems to be relying on it... | |
103 | */ | |
104 | /* | |
105 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) | |
a11f3a05 | 106 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
1da177e4 LT |
107 | * any extra contention... |
108 | */ | |
109 | ||
110 | /* In order to reduce some races, while at the same time doing additional | |
111 | * checking and hopefully speeding things up, we copy filenames to the | |
112 | * kernel data space before using them.. | |
113 | * | |
114 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). | |
115 | * PATH_MAX includes the nul terminator --RR. | |
116 | */ | |
858119e1 | 117 | static int do_getname(const char __user *filename, char *page) |
1da177e4 LT |
118 | { |
119 | int retval; | |
120 | unsigned long len = PATH_MAX; | |
121 | ||
122 | if (!segment_eq(get_fs(), KERNEL_DS)) { | |
123 | if ((unsigned long) filename >= TASK_SIZE) | |
124 | return -EFAULT; | |
125 | if (TASK_SIZE - (unsigned long) filename < PATH_MAX) | |
126 | len = TASK_SIZE - (unsigned long) filename; | |
127 | } | |
128 | ||
129 | retval = strncpy_from_user(page, filename, len); | |
130 | if (retval > 0) { | |
131 | if (retval < len) | |
132 | return 0; | |
133 | return -ENAMETOOLONG; | |
134 | } else if (!retval) | |
135 | retval = -ENOENT; | |
136 | return retval; | |
137 | } | |
138 | ||
f52e0c11 | 139 | static char *getname_flags(const char __user * filename, int flags) |
1da177e4 LT |
140 | { |
141 | char *tmp, *result; | |
142 | ||
143 | result = ERR_PTR(-ENOMEM); | |
144 | tmp = __getname(); | |
145 | if (tmp) { | |
146 | int retval = do_getname(filename, tmp); | |
147 | ||
148 | result = tmp; | |
149 | if (retval < 0) { | |
f52e0c11 AV |
150 | if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) { |
151 | __putname(tmp); | |
152 | result = ERR_PTR(retval); | |
153 | } | |
1da177e4 LT |
154 | } |
155 | } | |
156 | audit_getname(result); | |
157 | return result; | |
158 | } | |
159 | ||
f52e0c11 AV |
160 | char *getname(const char __user * filename) |
161 | { | |
162 | return getname_flags(filename, 0); | |
163 | } | |
164 | ||
1da177e4 LT |
165 | #ifdef CONFIG_AUDITSYSCALL |
166 | void putname(const char *name) | |
167 | { | |
5ac3a9c2 | 168 | if (unlikely(!audit_dummy_context())) |
1da177e4 LT |
169 | audit_putname(name); |
170 | else | |
171 | __putname(name); | |
172 | } | |
173 | EXPORT_SYMBOL(putname); | |
174 | #endif | |
175 | ||
5909ccaa LT |
176 | /* |
177 | * This does basic POSIX ACL permission checking | |
1da177e4 | 178 | */ |
7e40145e | 179 | static int acl_permission_check(struct inode *inode, int mask) |
1da177e4 | 180 | { |
7e40145e | 181 | int (*check_acl)(struct inode *inode, int mask); |
26cf46be | 182 | unsigned int mode = inode->i_mode; |
1da177e4 | 183 | |
9c2c7039 | 184 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC | MAY_NOT_BLOCK; |
e6305c43 | 185 | |
e795b717 SH |
186 | if (current_user_ns() != inode_userns(inode)) |
187 | goto other_perms; | |
188 | ||
da9592ed | 189 | if (current_fsuid() == inode->i_uid) |
1da177e4 LT |
190 | mode >>= 6; |
191 | else { | |
178ea735 | 192 | check_acl = inode->i_op->check_acl; |
1da177e4 | 193 | if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { |
7e40145e | 194 | int error = check_acl(inode, mask); |
b74c79e9 NP |
195 | if (error != -EAGAIN) |
196 | return error; | |
1da177e4 LT |
197 | } |
198 | ||
199 | if (in_group_p(inode->i_gid)) | |
200 | mode >>= 3; | |
201 | } | |
202 | ||
e795b717 | 203 | other_perms: |
1da177e4 LT |
204 | /* |
205 | * If the DACs are ok we don't need any capability check. | |
206 | */ | |
9c2c7039 | 207 | if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) |
1da177e4 | 208 | return 0; |
5909ccaa LT |
209 | return -EACCES; |
210 | } | |
211 | ||
212 | /** | |
b74c79e9 | 213 | * generic_permission - check for access rights on a Posix-like filesystem |
5909ccaa LT |
214 | * @inode: inode to check access rights for |
215 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
39191628 | 216 | * @flags: IPERM_FLAG_ flags. |
5909ccaa LT |
217 | * |
218 | * Used to check for read/write/execute permissions on a file. | |
219 | * We use "fsuid" for this, letting us set arbitrary permissions | |
220 | * for filesystem access without changing the "normal" uids which | |
b74c79e9 NP |
221 | * are used for other things. |
222 | * | |
223 | * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk | |
224 | * request cannot be satisfied (eg. requires blocking or too much complexity). | |
225 | * It would then be called again in ref-walk mode. | |
5909ccaa | 226 | */ |
2830ba7f | 227 | int generic_permission(struct inode *inode, int mask) |
5909ccaa LT |
228 | { |
229 | int ret; | |
230 | ||
231 | /* | |
232 | * Do the basic POSIX ACL permission checks. | |
233 | */ | |
7e40145e | 234 | ret = acl_permission_check(inode, mask); |
5909ccaa LT |
235 | if (ret != -EACCES) |
236 | return ret; | |
1da177e4 | 237 | |
d594e7ec AV |
238 | if (S_ISDIR(inode->i_mode)) { |
239 | /* DACs are overridable for directories */ | |
240 | if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) | |
241 | return 0; | |
242 | if (!(mask & MAY_WRITE)) | |
243 | if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) | |
244 | return 0; | |
245 | return -EACCES; | |
246 | } | |
1da177e4 LT |
247 | /* |
248 | * Read/write DACs are always overridable. | |
d594e7ec AV |
249 | * Executable DACs are overridable when there is |
250 | * at least one exec bit set. | |
1da177e4 | 251 | */ |
d594e7ec | 252 | if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) |
e795b717 | 253 | if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) |
1da177e4 LT |
254 | return 0; |
255 | ||
256 | /* | |
257 | * Searching includes executable on directories, else just read. | |
258 | */ | |
7ea66001 | 259 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
d594e7ec | 260 | if (mask == MAY_READ) |
e795b717 | 261 | if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH)) |
1da177e4 LT |
262 | return 0; |
263 | ||
264 | return -EACCES; | |
265 | } | |
266 | ||
cb23beb5 CH |
267 | /** |
268 | * inode_permission - check for access rights to a given inode | |
269 | * @inode: inode to check permission on | |
270 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
271 | * | |
272 | * Used to check for read/write/execute permissions on an inode. | |
273 | * We use "fsuid" for this, letting us set arbitrary permissions | |
274 | * for filesystem access without changing the "normal" uids which | |
275 | * are used for other things. | |
276 | */ | |
f419a2e3 | 277 | int inode_permission(struct inode *inode, int mask) |
1da177e4 | 278 | { |
e6305c43 | 279 | int retval; |
1da177e4 LT |
280 | |
281 | if (mask & MAY_WRITE) { | |
22590e41 | 282 | umode_t mode = inode->i_mode; |
1da177e4 LT |
283 | |
284 | /* | |
285 | * Nobody gets write access to a read-only fs. | |
286 | */ | |
287 | if (IS_RDONLY(inode) && | |
288 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
289 | return -EROFS; | |
290 | ||
291 | /* | |
292 | * Nobody gets write access to an immutable file. | |
293 | */ | |
294 | if (IS_IMMUTABLE(inode)) | |
295 | return -EACCES; | |
296 | } | |
297 | ||
acfa4380 | 298 | if (inode->i_op->permission) |
10556cb2 | 299 | retval = inode->i_op->permission(inode, mask); |
f696a365 | 300 | else |
2830ba7f | 301 | retval = generic_permission(inode, mask); |
f696a365 | 302 | |
1da177e4 LT |
303 | if (retval) |
304 | return retval; | |
305 | ||
08ce5f16 SH |
306 | retval = devcgroup_inode_permission(inode, mask); |
307 | if (retval) | |
308 | return retval; | |
309 | ||
d09ca739 | 310 | return security_inode_permission(inode, mask); |
1da177e4 LT |
311 | } |
312 | ||
5dd784d0 JB |
313 | /** |
314 | * path_get - get a reference to a path | |
315 | * @path: path to get the reference to | |
316 | * | |
317 | * Given a path increment the reference count to the dentry and the vfsmount. | |
318 | */ | |
319 | void path_get(struct path *path) | |
320 | { | |
321 | mntget(path->mnt); | |
322 | dget(path->dentry); | |
323 | } | |
324 | EXPORT_SYMBOL(path_get); | |
325 | ||
1d957f9b JB |
326 | /** |
327 | * path_put - put a reference to a path | |
328 | * @path: path to put the reference to | |
329 | * | |
330 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
331 | */ | |
332 | void path_put(struct path *path) | |
1da177e4 | 333 | { |
1d957f9b JB |
334 | dput(path->dentry); |
335 | mntput(path->mnt); | |
1da177e4 | 336 | } |
1d957f9b | 337 | EXPORT_SYMBOL(path_put); |
1da177e4 | 338 | |
19660af7 | 339 | /* |
31e6b01f | 340 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
19660af7 AV |
341 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
342 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab | |
343 | * normal reference counts on dentries and vfsmounts to transition to rcu-walk | |
344 | * mode. Refcounts are grabbed at the last known good point before rcu-walk | |
345 | * got stuck, so ref-walk may continue from there. If this is not successful | |
346 | * (eg. a seqcount has changed), then failure is returned and it's up to caller | |
347 | * to restart the path walk from the beginning in ref-walk mode. | |
31e6b01f | 348 | */ |
31e6b01f NP |
349 | |
350 | /** | |
19660af7 AV |
351 | * unlazy_walk - try to switch to ref-walk mode. |
352 | * @nd: nameidata pathwalk data | |
353 | * @dentry: child of nd->path.dentry or NULL | |
39191628 | 354 | * Returns: 0 on success, -ECHILD on failure |
31e6b01f | 355 | * |
19660af7 AV |
356 | * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry |
357 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on | |
358 | * @nd or NULL. Must be called from rcu-walk context. | |
31e6b01f | 359 | */ |
19660af7 | 360 | static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) |
31e6b01f NP |
361 | { |
362 | struct fs_struct *fs = current->fs; | |
363 | struct dentry *parent = nd->path.dentry; | |
5b6ca027 | 364 | int want_root = 0; |
31e6b01f NP |
365 | |
366 | BUG_ON(!(nd->flags & LOOKUP_RCU)); | |
5b6ca027 AV |
367 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
368 | want_root = 1; | |
31e6b01f NP |
369 | spin_lock(&fs->lock); |
370 | if (nd->root.mnt != fs->root.mnt || | |
371 | nd->root.dentry != fs->root.dentry) | |
372 | goto err_root; | |
373 | } | |
374 | spin_lock(&parent->d_lock); | |
19660af7 AV |
375 | if (!dentry) { |
376 | if (!__d_rcu_to_refcount(parent, nd->seq)) | |
377 | goto err_parent; | |
378 | BUG_ON(nd->inode != parent->d_inode); | |
379 | } else { | |
94c0d4ec AV |
380 | if (dentry->d_parent != parent) |
381 | goto err_parent; | |
19660af7 AV |
382 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
383 | if (!__d_rcu_to_refcount(dentry, nd->seq)) | |
384 | goto err_child; | |
385 | /* | |
386 | * If the sequence check on the child dentry passed, then | |
387 | * the child has not been removed from its parent. This | |
388 | * means the parent dentry must be valid and able to take | |
389 | * a reference at this point. | |
390 | */ | |
391 | BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); | |
392 | BUG_ON(!parent->d_count); | |
393 | parent->d_count++; | |
394 | spin_unlock(&dentry->d_lock); | |
395 | } | |
31e6b01f | 396 | spin_unlock(&parent->d_lock); |
5b6ca027 | 397 | if (want_root) { |
31e6b01f NP |
398 | path_get(&nd->root); |
399 | spin_unlock(&fs->lock); | |
400 | } | |
401 | mntget(nd->path.mnt); | |
402 | ||
403 | rcu_read_unlock(); | |
404 | br_read_unlock(vfsmount_lock); | |
405 | nd->flags &= ~LOOKUP_RCU; | |
406 | return 0; | |
19660af7 AV |
407 | |
408 | err_child: | |
31e6b01f | 409 | spin_unlock(&dentry->d_lock); |
19660af7 | 410 | err_parent: |
31e6b01f NP |
411 | spin_unlock(&parent->d_lock); |
412 | err_root: | |
5b6ca027 | 413 | if (want_root) |
31e6b01f NP |
414 | spin_unlock(&fs->lock); |
415 | return -ECHILD; | |
416 | } | |
417 | ||
834f2a4a TM |
418 | /** |
419 | * release_open_intent - free up open intent resources | |
420 | * @nd: pointer to nameidata | |
421 | */ | |
422 | void release_open_intent(struct nameidata *nd) | |
423 | { | |
2dab5974 LT |
424 | struct file *file = nd->intent.open.file; |
425 | ||
426 | if (file && !IS_ERR(file)) { | |
427 | if (file->f_path.dentry == NULL) | |
428 | put_filp(file); | |
429 | else | |
430 | fput(file); | |
431 | } | |
834f2a4a TM |
432 | } |
433 | ||
f60aef7e | 434 | static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd) |
34286d66 | 435 | { |
f60aef7e | 436 | return dentry->d_op->d_revalidate(dentry, nd); |
34286d66 NP |
437 | } |
438 | ||
9f1fafee AV |
439 | /** |
440 | * complete_walk - successful completion of path walk | |
441 | * @nd: pointer nameidata | |
39159de2 | 442 | * |
9f1fafee AV |
443 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
444 | * Revalidate the final result, unless we'd already done that during | |
445 | * the path walk or the filesystem doesn't ask for it. Return 0 on | |
446 | * success, -error on failure. In case of failure caller does not | |
447 | * need to drop nd->path. | |
39159de2 | 448 | */ |
9f1fafee | 449 | static int complete_walk(struct nameidata *nd) |
39159de2 | 450 | { |
16c2cd71 | 451 | struct dentry *dentry = nd->path.dentry; |
39159de2 | 452 | int status; |
39159de2 | 453 | |
9f1fafee AV |
454 | if (nd->flags & LOOKUP_RCU) { |
455 | nd->flags &= ~LOOKUP_RCU; | |
456 | if (!(nd->flags & LOOKUP_ROOT)) | |
457 | nd->root.mnt = NULL; | |
458 | spin_lock(&dentry->d_lock); | |
459 | if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { | |
460 | spin_unlock(&dentry->d_lock); | |
461 | rcu_read_unlock(); | |
462 | br_read_unlock(vfsmount_lock); | |
463 | return -ECHILD; | |
464 | } | |
465 | BUG_ON(nd->inode != dentry->d_inode); | |
466 | spin_unlock(&dentry->d_lock); | |
467 | mntget(nd->path.mnt); | |
468 | rcu_read_unlock(); | |
469 | br_read_unlock(vfsmount_lock); | |
470 | } | |
471 | ||
16c2cd71 AV |
472 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
473 | return 0; | |
474 | ||
475 | if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) | |
39159de2 JL |
476 | return 0; |
477 | ||
16c2cd71 AV |
478 | if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) |
479 | return 0; | |
480 | ||
481 | /* Note: we do not d_invalidate() */ | |
34286d66 | 482 | status = d_revalidate(dentry, nd); |
39159de2 JL |
483 | if (status > 0) |
484 | return 0; | |
485 | ||
16c2cd71 | 486 | if (!status) |
39159de2 | 487 | status = -ESTALE; |
16c2cd71 | 488 | |
9f1fafee | 489 | path_put(&nd->path); |
39159de2 JL |
490 | return status; |
491 | } | |
492 | ||
2a737871 AV |
493 | static __always_inline void set_root(struct nameidata *nd) |
494 | { | |
f7ad3c6b MS |
495 | if (!nd->root.mnt) |
496 | get_fs_root(current->fs, &nd->root); | |
2a737871 AV |
497 | } |
498 | ||
6de88d72 AV |
499 | static int link_path_walk(const char *, struct nameidata *); |
500 | ||
31e6b01f NP |
501 | static __always_inline void set_root_rcu(struct nameidata *nd) |
502 | { | |
503 | if (!nd->root.mnt) { | |
504 | struct fs_struct *fs = current->fs; | |
c28cc364 NP |
505 | unsigned seq; |
506 | ||
507 | do { | |
508 | seq = read_seqcount_begin(&fs->seq); | |
509 | nd->root = fs->root; | |
c1530019 | 510 | nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); |
c28cc364 | 511 | } while (read_seqcount_retry(&fs->seq, seq)); |
31e6b01f NP |
512 | } |
513 | } | |
514 | ||
f1662356 | 515 | static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
1da177e4 | 516 | { |
31e6b01f NP |
517 | int ret; |
518 | ||
1da177e4 LT |
519 | if (IS_ERR(link)) |
520 | goto fail; | |
521 | ||
522 | if (*link == '/') { | |
2a737871 | 523 | set_root(nd); |
1d957f9b | 524 | path_put(&nd->path); |
2a737871 AV |
525 | nd->path = nd->root; |
526 | path_get(&nd->root); | |
16c2cd71 | 527 | nd->flags |= LOOKUP_JUMPED; |
1da177e4 | 528 | } |
31e6b01f | 529 | nd->inode = nd->path.dentry->d_inode; |
b4091d5f | 530 | |
31e6b01f NP |
531 | ret = link_path_walk(link, nd); |
532 | return ret; | |
1da177e4 | 533 | fail: |
1d957f9b | 534 | path_put(&nd->path); |
1da177e4 LT |
535 | return PTR_ERR(link); |
536 | } | |
537 | ||
1d957f9b | 538 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
539 | { |
540 | dput(path->dentry); | |
4ac91378 | 541 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
542 | mntput(path->mnt); |
543 | } | |
544 | ||
7b9337aa NP |
545 | static inline void path_to_nameidata(const struct path *path, |
546 | struct nameidata *nd) | |
051d3812 | 547 | { |
31e6b01f NP |
548 | if (!(nd->flags & LOOKUP_RCU)) { |
549 | dput(nd->path.dentry); | |
550 | if (nd->path.mnt != path->mnt) | |
551 | mntput(nd->path.mnt); | |
9a229683 | 552 | } |
31e6b01f | 553 | nd->path.mnt = path->mnt; |
4ac91378 | 554 | nd->path.dentry = path->dentry; |
051d3812 IK |
555 | } |
556 | ||
574197e0 AV |
557 | static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) |
558 | { | |
559 | struct inode *inode = link->dentry->d_inode; | |
560 | if (!IS_ERR(cookie) && inode->i_op->put_link) | |
561 | inode->i_op->put_link(link->dentry, nd, cookie); | |
562 | path_put(link); | |
563 | } | |
564 | ||
def4af30 | 565 | static __always_inline int |
574197e0 | 566 | follow_link(struct path *link, struct nameidata *nd, void **p) |
1da177e4 LT |
567 | { |
568 | int error; | |
7b9337aa | 569 | struct dentry *dentry = link->dentry; |
1da177e4 | 570 | |
844a3917 AV |
571 | BUG_ON(nd->flags & LOOKUP_RCU); |
572 | ||
0e794589 AV |
573 | if (link->mnt == nd->path.mnt) |
574 | mntget(link->mnt); | |
575 | ||
574197e0 AV |
576 | if (unlikely(current->total_link_count >= 40)) { |
577 | *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */ | |
574197e0 AV |
578 | path_put(&nd->path); |
579 | return -ELOOP; | |
580 | } | |
581 | cond_resched(); | |
582 | current->total_link_count++; | |
583 | ||
7b9337aa | 584 | touch_atime(link->mnt, dentry); |
1da177e4 | 585 | nd_set_link(nd, NULL); |
cd4e91d3 | 586 | |
36f3b4f6 AV |
587 | error = security_inode_follow_link(link->dentry, nd); |
588 | if (error) { | |
589 | *p = ERR_PTR(error); /* no ->put_link(), please */ | |
590 | path_put(&nd->path); | |
591 | return error; | |
592 | } | |
593 | ||
86acdca1 | 594 | nd->last_type = LAST_BIND; |
def4af30 AV |
595 | *p = dentry->d_inode->i_op->follow_link(dentry, nd); |
596 | error = PTR_ERR(*p); | |
597 | if (!IS_ERR(*p)) { | |
1da177e4 | 598 | char *s = nd_get_link(nd); |
cc314eef | 599 | error = 0; |
1da177e4 LT |
600 | if (s) |
601 | error = __vfs_follow_link(nd, s); | |
bcda7652 | 602 | else if (nd->last_type == LAST_BIND) { |
16c2cd71 | 603 | nd->flags |= LOOKUP_JUMPED; |
b21041d0 AV |
604 | nd->inode = nd->path.dentry->d_inode; |
605 | if (nd->inode->i_op->follow_link) { | |
bcda7652 AV |
606 | /* stepped on a _really_ weird one */ |
607 | path_put(&nd->path); | |
608 | error = -ELOOP; | |
609 | } | |
610 | } | |
1da177e4 | 611 | } |
1da177e4 LT |
612 | return error; |
613 | } | |
614 | ||
31e6b01f NP |
615 | static int follow_up_rcu(struct path *path) |
616 | { | |
617 | struct vfsmount *parent; | |
618 | struct dentry *mountpoint; | |
619 | ||
620 | parent = path->mnt->mnt_parent; | |
621 | if (parent == path->mnt) | |
622 | return 0; | |
623 | mountpoint = path->mnt->mnt_mountpoint; | |
624 | path->dentry = mountpoint; | |
625 | path->mnt = parent; | |
626 | return 1; | |
627 | } | |
628 | ||
bab77ebf | 629 | int follow_up(struct path *path) |
1da177e4 LT |
630 | { |
631 | struct vfsmount *parent; | |
632 | struct dentry *mountpoint; | |
99b7db7b NP |
633 | |
634 | br_read_lock(vfsmount_lock); | |
bab77ebf AV |
635 | parent = path->mnt->mnt_parent; |
636 | if (parent == path->mnt) { | |
99b7db7b | 637 | br_read_unlock(vfsmount_lock); |
1da177e4 LT |
638 | return 0; |
639 | } | |
640 | mntget(parent); | |
bab77ebf | 641 | mountpoint = dget(path->mnt->mnt_mountpoint); |
99b7db7b | 642 | br_read_unlock(vfsmount_lock); |
bab77ebf AV |
643 | dput(path->dentry); |
644 | path->dentry = mountpoint; | |
645 | mntput(path->mnt); | |
646 | path->mnt = parent; | |
1da177e4 LT |
647 | return 1; |
648 | } | |
649 | ||
b5c84bf6 | 650 | /* |
9875cf80 DH |
651 | * Perform an automount |
652 | * - return -EISDIR to tell follow_managed() to stop and return the path we | |
653 | * were called with. | |
1da177e4 | 654 | */ |
9875cf80 DH |
655 | static int follow_automount(struct path *path, unsigned flags, |
656 | bool *need_mntput) | |
31e6b01f | 657 | { |
9875cf80 | 658 | struct vfsmount *mnt; |
ea5b778a | 659 | int err; |
9875cf80 DH |
660 | |
661 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) | |
662 | return -EREMOTE; | |
663 | ||
6f45b656 DH |
664 | /* We don't want to mount if someone supplied AT_NO_AUTOMOUNT |
665 | * and this is the terminal part of the path. | |
666 | */ | |
49084c3b | 667 | if ((flags & LOOKUP_NO_AUTOMOUNT) && !(flags & LOOKUP_PARENT)) |
6f45b656 DH |
668 | return -EISDIR; /* we actually want to stop here */ |
669 | ||
9875cf80 DH |
670 | /* We want to mount if someone is trying to open/create a file of any |
671 | * type under the mountpoint, wants to traverse through the mountpoint | |
672 | * or wants to open the mounted directory. | |
673 | * | |
674 | * We don't want to mount if someone's just doing a stat and they've | |
675 | * set AT_SYMLINK_NOFOLLOW - unless they're stat'ing a directory and | |
676 | * appended a '/' to the name. | |
677 | */ | |
678 | if (!(flags & LOOKUP_FOLLOW) && | |
49084c3b | 679 | !(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
9875cf80 DH |
680 | LOOKUP_OPEN | LOOKUP_CREATE))) |
681 | return -EISDIR; | |
682 | ||
683 | current->total_link_count++; | |
684 | if (current->total_link_count >= 40) | |
685 | return -ELOOP; | |
686 | ||
687 | mnt = path->dentry->d_op->d_automount(path); | |
688 | if (IS_ERR(mnt)) { | |
689 | /* | |
690 | * The filesystem is allowed to return -EISDIR here to indicate | |
691 | * it doesn't want to automount. For instance, autofs would do | |
692 | * this so that its userspace daemon can mount on this dentry. | |
693 | * | |
694 | * However, we can only permit this if it's a terminal point in | |
695 | * the path being looked up; if it wasn't then the remainder of | |
696 | * the path is inaccessible and we should say so. | |
697 | */ | |
49084c3b | 698 | if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) |
9875cf80 DH |
699 | return -EREMOTE; |
700 | return PTR_ERR(mnt); | |
31e6b01f | 701 | } |
ea5b778a | 702 | |
9875cf80 DH |
703 | if (!mnt) /* mount collision */ |
704 | return 0; | |
31e6b01f | 705 | |
8aef1884 AV |
706 | if (!*need_mntput) { |
707 | /* lock_mount() may release path->mnt on error */ | |
708 | mntget(path->mnt); | |
709 | *need_mntput = true; | |
710 | } | |
19a167af | 711 | err = finish_automount(mnt, path); |
9875cf80 | 712 | |
ea5b778a DH |
713 | switch (err) { |
714 | case -EBUSY: | |
715 | /* Someone else made a mount here whilst we were busy */ | |
19a167af | 716 | return 0; |
ea5b778a | 717 | case 0: |
8aef1884 | 718 | path_put(path); |
ea5b778a DH |
719 | path->mnt = mnt; |
720 | path->dentry = dget(mnt->mnt_root); | |
ea5b778a | 721 | return 0; |
19a167af AV |
722 | default: |
723 | return err; | |
ea5b778a | 724 | } |
19a167af | 725 | |
463ffb2e AV |
726 | } |
727 | ||
9875cf80 DH |
728 | /* |
729 | * Handle a dentry that is managed in some way. | |
cc53ce53 | 730 | * - Flagged for transit management (autofs) |
9875cf80 DH |
731 | * - Flagged as mountpoint |
732 | * - Flagged as automount point | |
733 | * | |
734 | * This may only be called in refwalk mode. | |
735 | * | |
736 | * Serialization is taken care of in namespace.c | |
737 | */ | |
738 | static int follow_managed(struct path *path, unsigned flags) | |
1da177e4 | 739 | { |
8aef1884 | 740 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
9875cf80 DH |
741 | unsigned managed; |
742 | bool need_mntput = false; | |
8aef1884 | 743 | int ret = 0; |
9875cf80 DH |
744 | |
745 | /* Given that we're not holding a lock here, we retain the value in a | |
746 | * local variable for each dentry as we look at it so that we don't see | |
747 | * the components of that value change under us */ | |
748 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
749 | managed &= DCACHE_MANAGED_DENTRY, | |
750 | unlikely(managed != 0)) { | |
cc53ce53 DH |
751 | /* Allow the filesystem to manage the transit without i_mutex |
752 | * being held. */ | |
753 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
754 | BUG_ON(!path->dentry->d_op); | |
755 | BUG_ON(!path->dentry->d_op->d_manage); | |
1aed3e42 | 756 | ret = path->dentry->d_op->d_manage(path->dentry, false); |
cc53ce53 | 757 | if (ret < 0) |
8aef1884 | 758 | break; |
cc53ce53 DH |
759 | } |
760 | ||
9875cf80 DH |
761 | /* Transit to a mounted filesystem. */ |
762 | if (managed & DCACHE_MOUNTED) { | |
763 | struct vfsmount *mounted = lookup_mnt(path); | |
764 | if (mounted) { | |
765 | dput(path->dentry); | |
766 | if (need_mntput) | |
767 | mntput(path->mnt); | |
768 | path->mnt = mounted; | |
769 | path->dentry = dget(mounted->mnt_root); | |
770 | need_mntput = true; | |
771 | continue; | |
772 | } | |
773 | ||
774 | /* Something is mounted on this dentry in another | |
775 | * namespace and/or whatever was mounted there in this | |
776 | * namespace got unmounted before we managed to get the | |
777 | * vfsmount_lock */ | |
778 | } | |
779 | ||
780 | /* Handle an automount point */ | |
781 | if (managed & DCACHE_NEED_AUTOMOUNT) { | |
782 | ret = follow_automount(path, flags, &need_mntput); | |
783 | if (ret < 0) | |
8aef1884 | 784 | break; |
9875cf80 DH |
785 | continue; |
786 | } | |
787 | ||
788 | /* We didn't change the current path point */ | |
789 | break; | |
1da177e4 | 790 | } |
8aef1884 AV |
791 | |
792 | if (need_mntput && path->mnt == mnt) | |
793 | mntput(path->mnt); | |
794 | if (ret == -EISDIR) | |
795 | ret = 0; | |
796 | return ret; | |
1da177e4 LT |
797 | } |
798 | ||
cc53ce53 | 799 | int follow_down_one(struct path *path) |
1da177e4 LT |
800 | { |
801 | struct vfsmount *mounted; | |
802 | ||
1c755af4 | 803 | mounted = lookup_mnt(path); |
1da177e4 | 804 | if (mounted) { |
9393bd07 AV |
805 | dput(path->dentry); |
806 | mntput(path->mnt); | |
807 | path->mnt = mounted; | |
808 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
809 | return 1; |
810 | } | |
811 | return 0; | |
812 | } | |
813 | ||
62a7375e IK |
814 | static inline bool managed_dentry_might_block(struct dentry *dentry) |
815 | { | |
816 | return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && | |
817 | dentry->d_op->d_manage(dentry, true) < 0); | |
818 | } | |
819 | ||
9875cf80 | 820 | /* |
287548e4 AV |
821 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
822 | * we meet a managed dentry that would need blocking. | |
9875cf80 DH |
823 | */ |
824 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, | |
287548e4 | 825 | struct inode **inode) |
9875cf80 | 826 | { |
62a7375e | 827 | for (;;) { |
9875cf80 | 828 | struct vfsmount *mounted; |
62a7375e IK |
829 | /* |
830 | * Don't forget we might have a non-mountpoint managed dentry | |
831 | * that wants to block transit. | |
832 | */ | |
287548e4 | 833 | if (unlikely(managed_dentry_might_block(path->dentry))) |
ab90911f | 834 | return false; |
62a7375e IK |
835 | |
836 | if (!d_mountpoint(path->dentry)) | |
837 | break; | |
838 | ||
9875cf80 DH |
839 | mounted = __lookup_mnt(path->mnt, path->dentry, 1); |
840 | if (!mounted) | |
841 | break; | |
842 | path->mnt = mounted; | |
843 | path->dentry = mounted->mnt_root; | |
844 | nd->seq = read_seqcount_begin(&path->dentry->d_seq); | |
59430262 LT |
845 | /* |
846 | * Update the inode too. We don't need to re-check the | |
847 | * dentry sequence number here after this d_inode read, | |
848 | * because a mount-point is always pinned. | |
849 | */ | |
850 | *inode = path->dentry->d_inode; | |
9875cf80 | 851 | } |
9875cf80 DH |
852 | return true; |
853 | } | |
854 | ||
dea39376 | 855 | static void follow_mount_rcu(struct nameidata *nd) |
287548e4 | 856 | { |
dea39376 | 857 | while (d_mountpoint(nd->path.dentry)) { |
287548e4 | 858 | struct vfsmount *mounted; |
dea39376 | 859 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); |
287548e4 AV |
860 | if (!mounted) |
861 | break; | |
dea39376 AV |
862 | nd->path.mnt = mounted; |
863 | nd->path.dentry = mounted->mnt_root; | |
864 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
287548e4 AV |
865 | } |
866 | } | |
867 | ||
31e6b01f NP |
868 | static int follow_dotdot_rcu(struct nameidata *nd) |
869 | { | |
31e6b01f NP |
870 | set_root_rcu(nd); |
871 | ||
9875cf80 | 872 | while (1) { |
31e6b01f NP |
873 | if (nd->path.dentry == nd->root.dentry && |
874 | nd->path.mnt == nd->root.mnt) { | |
875 | break; | |
876 | } | |
877 | if (nd->path.dentry != nd->path.mnt->mnt_root) { | |
878 | struct dentry *old = nd->path.dentry; | |
879 | struct dentry *parent = old->d_parent; | |
880 | unsigned seq; | |
881 | ||
882 | seq = read_seqcount_begin(&parent->d_seq); | |
883 | if (read_seqcount_retry(&old->d_seq, nd->seq)) | |
ef7562d5 | 884 | goto failed; |
31e6b01f NP |
885 | nd->path.dentry = parent; |
886 | nd->seq = seq; | |
887 | break; | |
888 | } | |
889 | if (!follow_up_rcu(&nd->path)) | |
890 | break; | |
891 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
31e6b01f | 892 | } |
dea39376 AV |
893 | follow_mount_rcu(nd); |
894 | nd->inode = nd->path.dentry->d_inode; | |
31e6b01f | 895 | return 0; |
ef7562d5 AV |
896 | |
897 | failed: | |
898 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
899 | if (!(nd->flags & LOOKUP_ROOT)) |
900 | nd->root.mnt = NULL; | |
ef7562d5 AV |
901 | rcu_read_unlock(); |
902 | br_read_unlock(vfsmount_lock); | |
903 | return -ECHILD; | |
31e6b01f NP |
904 | } |
905 | ||
cc53ce53 DH |
906 | /* |
907 | * Follow down to the covering mount currently visible to userspace. At each | |
908 | * point, the filesystem owning that dentry may be queried as to whether the | |
909 | * caller is permitted to proceed or not. | |
cc53ce53 | 910 | */ |
7cc90cc3 | 911 | int follow_down(struct path *path) |
cc53ce53 DH |
912 | { |
913 | unsigned managed; | |
914 | int ret; | |
915 | ||
916 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
917 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { | |
918 | /* Allow the filesystem to manage the transit without i_mutex | |
919 | * being held. | |
920 | * | |
921 | * We indicate to the filesystem if someone is trying to mount | |
922 | * something here. This gives autofs the chance to deny anyone | |
923 | * other than its daemon the right to mount on its | |
924 | * superstructure. | |
925 | * | |
926 | * The filesystem may sleep at this point. | |
927 | */ | |
928 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
929 | BUG_ON(!path->dentry->d_op); | |
930 | BUG_ON(!path->dentry->d_op->d_manage); | |
ab90911f | 931 | ret = path->dentry->d_op->d_manage( |
1aed3e42 | 932 | path->dentry, false); |
cc53ce53 DH |
933 | if (ret < 0) |
934 | return ret == -EISDIR ? 0 : ret; | |
935 | } | |
936 | ||
937 | /* Transit to a mounted filesystem. */ | |
938 | if (managed & DCACHE_MOUNTED) { | |
939 | struct vfsmount *mounted = lookup_mnt(path); | |
940 | if (!mounted) | |
941 | break; | |
942 | dput(path->dentry); | |
943 | mntput(path->mnt); | |
944 | path->mnt = mounted; | |
945 | path->dentry = dget(mounted->mnt_root); | |
946 | continue; | |
947 | } | |
948 | ||
949 | /* Don't handle automount points here */ | |
950 | break; | |
951 | } | |
952 | return 0; | |
953 | } | |
954 | ||
9875cf80 DH |
955 | /* |
956 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() | |
957 | */ | |
958 | static void follow_mount(struct path *path) | |
959 | { | |
960 | while (d_mountpoint(path->dentry)) { | |
961 | struct vfsmount *mounted = lookup_mnt(path); | |
962 | if (!mounted) | |
963 | break; | |
964 | dput(path->dentry); | |
965 | mntput(path->mnt); | |
966 | path->mnt = mounted; | |
967 | path->dentry = dget(mounted->mnt_root); | |
968 | } | |
969 | } | |
970 | ||
31e6b01f | 971 | static void follow_dotdot(struct nameidata *nd) |
1da177e4 | 972 | { |
2a737871 | 973 | set_root(nd); |
e518ddb7 | 974 | |
1da177e4 | 975 | while(1) { |
4ac91378 | 976 | struct dentry *old = nd->path.dentry; |
1da177e4 | 977 | |
2a737871 AV |
978 | if (nd->path.dentry == nd->root.dentry && |
979 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
980 | break; |
981 | } | |
4ac91378 | 982 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
3088dd70 AV |
983 | /* rare case of legitimate dget_parent()... */ |
984 | nd->path.dentry = dget_parent(nd->path.dentry); | |
1da177e4 LT |
985 | dput(old); |
986 | break; | |
987 | } | |
3088dd70 | 988 | if (!follow_up(&nd->path)) |
1da177e4 | 989 | break; |
1da177e4 | 990 | } |
79ed0226 | 991 | follow_mount(&nd->path); |
31e6b01f | 992 | nd->inode = nd->path.dentry->d_inode; |
1da177e4 LT |
993 | } |
994 | ||
baa03890 NP |
995 | /* |
996 | * Allocate a dentry with name and parent, and perform a parent | |
997 | * directory ->lookup on it. Returns the new dentry, or ERR_PTR | |
998 | * on error. parent->d_inode->i_mutex must be held. d_lookup must | |
999 | * have verified that no child exists while under i_mutex. | |
1000 | */ | |
1001 | static struct dentry *d_alloc_and_lookup(struct dentry *parent, | |
1002 | struct qstr *name, struct nameidata *nd) | |
1003 | { | |
1004 | struct inode *inode = parent->d_inode; | |
1005 | struct dentry *dentry; | |
1006 | struct dentry *old; | |
1007 | ||
1008 | /* Don't create child dentry for a dead directory. */ | |
1009 | if (unlikely(IS_DEADDIR(inode))) | |
1010 | return ERR_PTR(-ENOENT); | |
1011 | ||
1012 | dentry = d_alloc(parent, name); | |
1013 | if (unlikely(!dentry)) | |
1014 | return ERR_PTR(-ENOMEM); | |
1015 | ||
1016 | old = inode->i_op->lookup(inode, dentry, nd); | |
1017 | if (unlikely(old)) { | |
1018 | dput(dentry); | |
1019 | dentry = old; | |
1020 | } | |
1021 | return dentry; | |
1022 | } | |
1023 | ||
44396f4b JB |
1024 | /* |
1025 | * We already have a dentry, but require a lookup to be performed on the parent | |
1026 | * directory to fill in d_inode. Returns the new dentry, or ERR_PTR on error. | |
1027 | * parent->d_inode->i_mutex must be held. d_lookup must have verified that no | |
1028 | * child exists while under i_mutex. | |
1029 | */ | |
1030 | static struct dentry *d_inode_lookup(struct dentry *parent, struct dentry *dentry, | |
1031 | struct nameidata *nd) | |
1032 | { | |
1033 | struct inode *inode = parent->d_inode; | |
1034 | struct dentry *old; | |
1035 | ||
1036 | /* Don't create child dentry for a dead directory. */ | |
1037 | if (unlikely(IS_DEADDIR(inode))) | |
1038 | return ERR_PTR(-ENOENT); | |
1039 | ||
1040 | old = inode->i_op->lookup(inode, dentry, nd); | |
1041 | if (unlikely(old)) { | |
1042 | dput(dentry); | |
1043 | dentry = old; | |
1044 | } | |
1045 | return dentry; | |
1046 | } | |
1047 | ||
1da177e4 LT |
1048 | /* |
1049 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
1050 | * small and for now I'd prefer to have fast path as straight as possible. | |
1051 | * It _is_ time-critical. | |
1052 | */ | |
1053 | static int do_lookup(struct nameidata *nd, struct qstr *name, | |
31e6b01f | 1054 | struct path *path, struct inode **inode) |
1da177e4 | 1055 | { |
4ac91378 | 1056 | struct vfsmount *mnt = nd->path.mnt; |
31e6b01f | 1057 | struct dentry *dentry, *parent = nd->path.dentry; |
5a18fff2 AV |
1058 | int need_reval = 1; |
1059 | int status = 1; | |
9875cf80 DH |
1060 | int err; |
1061 | ||
b04f784e NP |
1062 | /* |
1063 | * Rename seqlock is not required here because in the off chance | |
1064 | * of a false negative due to a concurrent rename, we're going to | |
1065 | * do the non-racy lookup, below. | |
1066 | */ | |
31e6b01f NP |
1067 | if (nd->flags & LOOKUP_RCU) { |
1068 | unsigned seq; | |
31e6b01f NP |
1069 | *inode = nd->inode; |
1070 | dentry = __d_lookup_rcu(parent, name, &seq, inode); | |
5a18fff2 AV |
1071 | if (!dentry) |
1072 | goto unlazy; | |
1073 | ||
31e6b01f NP |
1074 | /* Memory barrier in read_seqcount_begin of child is enough */ |
1075 | if (__read_seqcount_retry(&parent->d_seq, nd->seq)) | |
1076 | return -ECHILD; | |
31e6b01f | 1077 | nd->seq = seq; |
5a18fff2 | 1078 | |
24643087 | 1079 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
5a18fff2 AV |
1080 | status = d_revalidate(dentry, nd); |
1081 | if (unlikely(status <= 0)) { | |
1082 | if (status != -ECHILD) | |
1083 | need_reval = 0; | |
1084 | goto unlazy; | |
1085 | } | |
24643087 | 1086 | } |
44396f4b JB |
1087 | if (unlikely(d_need_lookup(dentry))) |
1088 | goto unlazy; | |
31e6b01f NP |
1089 | path->mnt = mnt; |
1090 | path->dentry = dentry; | |
d6e9bd25 AV |
1091 | if (unlikely(!__follow_mount_rcu(nd, path, inode))) |
1092 | goto unlazy; | |
1093 | if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) | |
1094 | goto unlazy; | |
1095 | return 0; | |
5a18fff2 | 1096 | unlazy: |
19660af7 AV |
1097 | if (unlazy_walk(nd, dentry)) |
1098 | return -ECHILD; | |
5a18fff2 AV |
1099 | } else { |
1100 | dentry = __d_lookup(parent, name); | |
9875cf80 | 1101 | } |
5a18fff2 | 1102 | |
44396f4b JB |
1103 | if (dentry && unlikely(d_need_lookup(dentry))) { |
1104 | dput(dentry); | |
1105 | dentry = NULL; | |
1106 | } | |
5a18fff2 AV |
1107 | retry: |
1108 | if (unlikely(!dentry)) { | |
1109 | struct inode *dir = parent->d_inode; | |
1110 | BUG_ON(nd->inode != dir); | |
1111 | ||
1112 | mutex_lock(&dir->i_mutex); | |
1113 | dentry = d_lookup(parent, name); | |
1114 | if (likely(!dentry)) { | |
1115 | dentry = d_alloc_and_lookup(parent, name, nd); | |
1116 | if (IS_ERR(dentry)) { | |
1117 | mutex_unlock(&dir->i_mutex); | |
1118 | return PTR_ERR(dentry); | |
1119 | } | |
1120 | /* known good */ | |
1121 | need_reval = 0; | |
1122 | status = 1; | |
44396f4b JB |
1123 | } else if (unlikely(d_need_lookup(dentry))) { |
1124 | dentry = d_inode_lookup(parent, dentry, nd); | |
1125 | if (IS_ERR(dentry)) { | |
1126 | mutex_unlock(&dir->i_mutex); | |
1127 | return PTR_ERR(dentry); | |
1128 | } | |
1129 | /* known good */ | |
1130 | need_reval = 0; | |
1131 | status = 1; | |
5a18fff2 AV |
1132 | } |
1133 | mutex_unlock(&dir->i_mutex); | |
1134 | } | |
1135 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) | |
1136 | status = d_revalidate(dentry, nd); | |
1137 | if (unlikely(status <= 0)) { | |
1138 | if (status < 0) { | |
1139 | dput(dentry); | |
1140 | return status; | |
1141 | } | |
1142 | if (!d_invalidate(dentry)) { | |
1143 | dput(dentry); | |
1144 | dentry = NULL; | |
1145 | need_reval = 1; | |
1146 | goto retry; | |
1147 | } | |
24643087 | 1148 | } |
5a18fff2 | 1149 | |
9875cf80 DH |
1150 | path->mnt = mnt; |
1151 | path->dentry = dentry; | |
1152 | err = follow_managed(path, nd->flags); | |
89312214 IK |
1153 | if (unlikely(err < 0)) { |
1154 | path_put_conditional(path, nd); | |
9875cf80 | 1155 | return err; |
89312214 | 1156 | } |
9875cf80 | 1157 | *inode = path->dentry->d_inode; |
1da177e4 | 1158 | return 0; |
1da177e4 LT |
1159 | } |
1160 | ||
52094c8a AV |
1161 | static inline int may_lookup(struct nameidata *nd) |
1162 | { | |
1163 | if (nd->flags & LOOKUP_RCU) { | |
4ad5abb3 | 1164 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
52094c8a AV |
1165 | if (err != -ECHILD) |
1166 | return err; | |
19660af7 | 1167 | if (unlazy_walk(nd, NULL)) |
52094c8a AV |
1168 | return -ECHILD; |
1169 | } | |
4ad5abb3 | 1170 | return inode_permission(nd->inode, MAY_EXEC); |
52094c8a AV |
1171 | } |
1172 | ||
9856fa1b AV |
1173 | static inline int handle_dots(struct nameidata *nd, int type) |
1174 | { | |
1175 | if (type == LAST_DOTDOT) { | |
1176 | if (nd->flags & LOOKUP_RCU) { | |
1177 | if (follow_dotdot_rcu(nd)) | |
1178 | return -ECHILD; | |
1179 | } else | |
1180 | follow_dotdot(nd); | |
1181 | } | |
1182 | return 0; | |
1183 | } | |
1184 | ||
951361f9 AV |
1185 | static void terminate_walk(struct nameidata *nd) |
1186 | { | |
1187 | if (!(nd->flags & LOOKUP_RCU)) { | |
1188 | path_put(&nd->path); | |
1189 | } else { | |
1190 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1191 | if (!(nd->flags & LOOKUP_ROOT)) |
1192 | nd->root.mnt = NULL; | |
951361f9 AV |
1193 | rcu_read_unlock(); |
1194 | br_read_unlock(vfsmount_lock); | |
1195 | } | |
1196 | } | |
1197 | ||
ce57dfc1 AV |
1198 | static inline int walk_component(struct nameidata *nd, struct path *path, |
1199 | struct qstr *name, int type, int follow) | |
1200 | { | |
1201 | struct inode *inode; | |
1202 | int err; | |
1203 | /* | |
1204 | * "." and ".." are special - ".." especially so because it has | |
1205 | * to be able to know about the current root directory and | |
1206 | * parent relationships. | |
1207 | */ | |
1208 | if (unlikely(type != LAST_NORM)) | |
1209 | return handle_dots(nd, type); | |
1210 | err = do_lookup(nd, name, path, &inode); | |
1211 | if (unlikely(err)) { | |
1212 | terminate_walk(nd); | |
1213 | return err; | |
1214 | } | |
1215 | if (!inode) { | |
1216 | path_to_nameidata(path, nd); | |
1217 | terminate_walk(nd); | |
1218 | return -ENOENT; | |
1219 | } | |
1220 | if (unlikely(inode->i_op->follow_link) && follow) { | |
19660af7 AV |
1221 | if (nd->flags & LOOKUP_RCU) { |
1222 | if (unlikely(unlazy_walk(nd, path->dentry))) { | |
1223 | terminate_walk(nd); | |
1224 | return -ECHILD; | |
1225 | } | |
1226 | } | |
ce57dfc1 AV |
1227 | BUG_ON(inode != path->dentry->d_inode); |
1228 | return 1; | |
1229 | } | |
1230 | path_to_nameidata(path, nd); | |
1231 | nd->inode = inode; | |
1232 | return 0; | |
1233 | } | |
1234 | ||
b356379a AV |
1235 | /* |
1236 | * This limits recursive symlink follows to 8, while | |
1237 | * limiting consecutive symlinks to 40. | |
1238 | * | |
1239 | * Without that kind of total limit, nasty chains of consecutive | |
1240 | * symlinks can cause almost arbitrarily long lookups. | |
1241 | */ | |
1242 | static inline int nested_symlink(struct path *path, struct nameidata *nd) | |
1243 | { | |
1244 | int res; | |
1245 | ||
b356379a AV |
1246 | if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { |
1247 | path_put_conditional(path, nd); | |
1248 | path_put(&nd->path); | |
1249 | return -ELOOP; | |
1250 | } | |
1a4022f8 | 1251 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); |
b356379a AV |
1252 | |
1253 | nd->depth++; | |
1254 | current->link_count++; | |
1255 | ||
1256 | do { | |
1257 | struct path link = *path; | |
1258 | void *cookie; | |
574197e0 AV |
1259 | |
1260 | res = follow_link(&link, nd, &cookie); | |
b356379a AV |
1261 | if (!res) |
1262 | res = walk_component(nd, path, &nd->last, | |
1263 | nd->last_type, LOOKUP_FOLLOW); | |
574197e0 | 1264 | put_link(nd, &link, cookie); |
b356379a AV |
1265 | } while (res > 0); |
1266 | ||
1267 | current->link_count--; | |
1268 | nd->depth--; | |
1269 | return res; | |
1270 | } | |
1271 | ||
1da177e4 LT |
1272 | /* |
1273 | * Name resolution. | |
ea3834d9 PM |
1274 | * This is the basic name resolution function, turning a pathname into |
1275 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 1276 | * |
ea3834d9 PM |
1277 | * Returns 0 and nd will have valid dentry and mnt on success. |
1278 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 1279 | */ |
6de88d72 | 1280 | static int link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 LT |
1281 | { |
1282 | struct path next; | |
1da177e4 | 1283 | int err; |
1da177e4 LT |
1284 | |
1285 | while (*name=='/') | |
1286 | name++; | |
1287 | if (!*name) | |
086e183a | 1288 | return 0; |
1da177e4 | 1289 | |
1da177e4 LT |
1290 | /* At this point we know we have a real path component. */ |
1291 | for(;;) { | |
1292 | unsigned long hash; | |
1293 | struct qstr this; | |
1294 | unsigned int c; | |
fe479a58 | 1295 | int type; |
1da177e4 | 1296 | |
52094c8a | 1297 | err = may_lookup(nd); |
1da177e4 LT |
1298 | if (err) |
1299 | break; | |
1300 | ||
1301 | this.name = name; | |
1302 | c = *(const unsigned char *)name; | |
1303 | ||
1304 | hash = init_name_hash(); | |
1305 | do { | |
1306 | name++; | |
1307 | hash = partial_name_hash(c, hash); | |
1308 | c = *(const unsigned char *)name; | |
1309 | } while (c && (c != '/')); | |
1310 | this.len = name - (const char *) this.name; | |
1311 | this.hash = end_name_hash(hash); | |
1312 | ||
fe479a58 AV |
1313 | type = LAST_NORM; |
1314 | if (this.name[0] == '.') switch (this.len) { | |
1315 | case 2: | |
16c2cd71 | 1316 | if (this.name[1] == '.') { |
fe479a58 | 1317 | type = LAST_DOTDOT; |
16c2cd71 AV |
1318 | nd->flags |= LOOKUP_JUMPED; |
1319 | } | |
fe479a58 AV |
1320 | break; |
1321 | case 1: | |
1322 | type = LAST_DOT; | |
1323 | } | |
5a202bcd AV |
1324 | if (likely(type == LAST_NORM)) { |
1325 | struct dentry *parent = nd->path.dentry; | |
16c2cd71 | 1326 | nd->flags &= ~LOOKUP_JUMPED; |
5a202bcd AV |
1327 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
1328 | err = parent->d_op->d_hash(parent, nd->inode, | |
1329 | &this); | |
1330 | if (err < 0) | |
1331 | break; | |
1332 | } | |
1333 | } | |
fe479a58 | 1334 | |
1da177e4 LT |
1335 | /* remove trailing slashes? */ |
1336 | if (!c) | |
1337 | goto last_component; | |
1338 | while (*++name == '/'); | |
1339 | if (!*name) | |
b356379a | 1340 | goto last_component; |
1da177e4 | 1341 | |
ce57dfc1 AV |
1342 | err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); |
1343 | if (err < 0) | |
1344 | return err; | |
1da177e4 | 1345 | |
ce57dfc1 | 1346 | if (err) { |
b356379a | 1347 | err = nested_symlink(&next, nd); |
1da177e4 | 1348 | if (err) |
a7472bab | 1349 | return err; |
31e6b01f | 1350 | } |
1da177e4 | 1351 | err = -ENOTDIR; |
31e6b01f | 1352 | if (!nd->inode->i_op->lookup) |
1da177e4 LT |
1353 | break; |
1354 | continue; | |
1355 | /* here ends the main loop */ | |
1356 | ||
1da177e4 | 1357 | last_component: |
b356379a AV |
1358 | nd->last = this; |
1359 | nd->last_type = type; | |
086e183a | 1360 | return 0; |
1da177e4 | 1361 | } |
951361f9 | 1362 | terminate_walk(nd); |
1da177e4 LT |
1363 | return err; |
1364 | } | |
1365 | ||
70e9b357 AV |
1366 | static int path_init(int dfd, const char *name, unsigned int flags, |
1367 | struct nameidata *nd, struct file **fp) | |
31e6b01f NP |
1368 | { |
1369 | int retval = 0; | |
1370 | int fput_needed; | |
1371 | struct file *file; | |
1372 | ||
1373 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
16c2cd71 | 1374 | nd->flags = flags | LOOKUP_JUMPED; |
31e6b01f | 1375 | nd->depth = 0; |
5b6ca027 AV |
1376 | if (flags & LOOKUP_ROOT) { |
1377 | struct inode *inode = nd->root.dentry->d_inode; | |
73d049a4 AV |
1378 | if (*name) { |
1379 | if (!inode->i_op->lookup) | |
1380 | return -ENOTDIR; | |
1381 | retval = inode_permission(inode, MAY_EXEC); | |
1382 | if (retval) | |
1383 | return retval; | |
1384 | } | |
5b6ca027 AV |
1385 | nd->path = nd->root; |
1386 | nd->inode = inode; | |
1387 | if (flags & LOOKUP_RCU) { | |
1388 | br_read_lock(vfsmount_lock); | |
1389 | rcu_read_lock(); | |
1390 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
1391 | } else { | |
1392 | path_get(&nd->path); | |
1393 | } | |
1394 | return 0; | |
1395 | } | |
1396 | ||
31e6b01f | 1397 | nd->root.mnt = NULL; |
31e6b01f NP |
1398 | |
1399 | if (*name=='/') { | |
e41f7d4e AV |
1400 | if (flags & LOOKUP_RCU) { |
1401 | br_read_lock(vfsmount_lock); | |
1402 | rcu_read_lock(); | |
1403 | set_root_rcu(nd); | |
1404 | } else { | |
1405 | set_root(nd); | |
1406 | path_get(&nd->root); | |
1407 | } | |
1408 | nd->path = nd->root; | |
31e6b01f | 1409 | } else if (dfd == AT_FDCWD) { |
e41f7d4e AV |
1410 | if (flags & LOOKUP_RCU) { |
1411 | struct fs_struct *fs = current->fs; | |
1412 | unsigned seq; | |
31e6b01f | 1413 | |
e41f7d4e AV |
1414 | br_read_lock(vfsmount_lock); |
1415 | rcu_read_lock(); | |
c28cc364 | 1416 | |
e41f7d4e AV |
1417 | do { |
1418 | seq = read_seqcount_begin(&fs->seq); | |
1419 | nd->path = fs->pwd; | |
1420 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
1421 | } while (read_seqcount_retry(&fs->seq, seq)); | |
1422 | } else { | |
1423 | get_fs_pwd(current->fs, &nd->path); | |
1424 | } | |
31e6b01f NP |
1425 | } else { |
1426 | struct dentry *dentry; | |
1427 | ||
1abf0c71 | 1428 | file = fget_raw_light(dfd, &fput_needed); |
31e6b01f NP |
1429 | retval = -EBADF; |
1430 | if (!file) | |
1431 | goto out_fail; | |
1432 | ||
1433 | dentry = file->f_path.dentry; | |
1434 | ||
f52e0c11 AV |
1435 | if (*name) { |
1436 | retval = -ENOTDIR; | |
1437 | if (!S_ISDIR(dentry->d_inode->i_mode)) | |
1438 | goto fput_fail; | |
31e6b01f | 1439 | |
4ad5abb3 | 1440 | retval = inode_permission(dentry->d_inode, MAY_EXEC); |
f52e0c11 AV |
1441 | if (retval) |
1442 | goto fput_fail; | |
1443 | } | |
31e6b01f NP |
1444 | |
1445 | nd->path = file->f_path; | |
e41f7d4e AV |
1446 | if (flags & LOOKUP_RCU) { |
1447 | if (fput_needed) | |
70e9b357 | 1448 | *fp = file; |
e41f7d4e AV |
1449 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
1450 | br_read_lock(vfsmount_lock); | |
1451 | rcu_read_lock(); | |
1452 | } else { | |
1453 | path_get(&file->f_path); | |
1454 | fput_light(file, fput_needed); | |
1455 | } | |
31e6b01f | 1456 | } |
31e6b01f | 1457 | |
31e6b01f | 1458 | nd->inode = nd->path.dentry->d_inode; |
9b4a9b14 | 1459 | return 0; |
2dfdd266 | 1460 | |
9b4a9b14 AV |
1461 | fput_fail: |
1462 | fput_light(file, fput_needed); | |
1463 | out_fail: | |
1464 | return retval; | |
1465 | } | |
1466 | ||
bd92d7fe AV |
1467 | static inline int lookup_last(struct nameidata *nd, struct path *path) |
1468 | { | |
1469 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) | |
1470 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
1471 | ||
1472 | nd->flags &= ~LOOKUP_PARENT; | |
1473 | return walk_component(nd, path, &nd->last, nd->last_type, | |
1474 | nd->flags & LOOKUP_FOLLOW); | |
1475 | } | |
1476 | ||
9b4a9b14 | 1477 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
ee0827cd | 1478 | static int path_lookupat(int dfd, const char *name, |
9b4a9b14 AV |
1479 | unsigned int flags, struct nameidata *nd) |
1480 | { | |
70e9b357 | 1481 | struct file *base = NULL; |
bd92d7fe AV |
1482 | struct path path; |
1483 | int err; | |
31e6b01f NP |
1484 | |
1485 | /* | |
1486 | * Path walking is largely split up into 2 different synchronisation | |
1487 | * schemes, rcu-walk and ref-walk (explained in | |
1488 | * Documentation/filesystems/path-lookup.txt). These share much of the | |
1489 | * path walk code, but some things particularly setup, cleanup, and | |
1490 | * following mounts are sufficiently divergent that functions are | |
1491 | * duplicated. Typically there is a function foo(), and its RCU | |
1492 | * analogue, foo_rcu(). | |
1493 | * | |
1494 | * -ECHILD is the error number of choice (just to avoid clashes) that | |
1495 | * is returned if some aspect of an rcu-walk fails. Such an error must | |
1496 | * be handled by restarting a traditional ref-walk (which will always | |
1497 | * be able to complete). | |
1498 | */ | |
bd92d7fe | 1499 | err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); |
ee0827cd | 1500 | |
bd92d7fe AV |
1501 | if (unlikely(err)) |
1502 | return err; | |
ee0827cd AV |
1503 | |
1504 | current->total_link_count = 0; | |
bd92d7fe AV |
1505 | err = link_path_walk(name, nd); |
1506 | ||
1507 | if (!err && !(flags & LOOKUP_PARENT)) { | |
bd92d7fe AV |
1508 | err = lookup_last(nd, &path); |
1509 | while (err > 0) { | |
1510 | void *cookie; | |
1511 | struct path link = path; | |
bd92d7fe | 1512 | nd->flags |= LOOKUP_PARENT; |
574197e0 | 1513 | err = follow_link(&link, nd, &cookie); |
bd92d7fe AV |
1514 | if (!err) |
1515 | err = lookup_last(nd, &path); | |
574197e0 | 1516 | put_link(nd, &link, cookie); |
bd92d7fe AV |
1517 | } |
1518 | } | |
ee0827cd | 1519 | |
9f1fafee AV |
1520 | if (!err) |
1521 | err = complete_walk(nd); | |
bd92d7fe AV |
1522 | |
1523 | if (!err && nd->flags & LOOKUP_DIRECTORY) { | |
1524 | if (!nd->inode->i_op->lookup) { | |
1525 | path_put(&nd->path); | |
bd23a539 | 1526 | err = -ENOTDIR; |
bd92d7fe AV |
1527 | } |
1528 | } | |
16c2cd71 | 1529 | |
70e9b357 AV |
1530 | if (base) |
1531 | fput(base); | |
ee0827cd | 1532 | |
5b6ca027 | 1533 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
2a737871 AV |
1534 | path_put(&nd->root); |
1535 | nd->root.mnt = NULL; | |
1536 | } | |
bd92d7fe | 1537 | return err; |
ee0827cd | 1538 | } |
31e6b01f | 1539 | |
ee0827cd AV |
1540 | static int do_path_lookup(int dfd, const char *name, |
1541 | unsigned int flags, struct nameidata *nd) | |
1542 | { | |
1543 | int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); | |
1544 | if (unlikely(retval == -ECHILD)) | |
1545 | retval = path_lookupat(dfd, name, flags, nd); | |
1546 | if (unlikely(retval == -ESTALE)) | |
1547 | retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); | |
31e6b01f NP |
1548 | |
1549 | if (likely(!retval)) { | |
1550 | if (unlikely(!audit_dummy_context())) { | |
1551 | if (nd->path.dentry && nd->inode) | |
1552 | audit_inode(name, nd->path.dentry); | |
1553 | } | |
1554 | } | |
170aa3d0 | 1555 | return retval; |
1da177e4 LT |
1556 | } |
1557 | ||
c9c6cac0 | 1558 | int kern_path_parent(const char *name, struct nameidata *nd) |
5590ff0d | 1559 | { |
c9c6cac0 | 1560 | return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd); |
5590ff0d UD |
1561 | } |
1562 | ||
d1811465 AV |
1563 | int kern_path(const char *name, unsigned int flags, struct path *path) |
1564 | { | |
1565 | struct nameidata nd; | |
1566 | int res = do_path_lookup(AT_FDCWD, name, flags, &nd); | |
1567 | if (!res) | |
1568 | *path = nd.path; | |
1569 | return res; | |
1570 | } | |
1571 | ||
16f18200 JJS |
1572 | /** |
1573 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
1574 | * @dentry: pointer to dentry of the base directory | |
1575 | * @mnt: pointer to vfs mount of the base directory | |
1576 | * @name: pointer to file name | |
1577 | * @flags: lookup flags | |
1578 | * @nd: pointer to nameidata | |
1579 | */ | |
1580 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
1581 | const char *name, unsigned int flags, | |
1582 | struct nameidata *nd) | |
1583 | { | |
5b6ca027 AV |
1584 | nd->root.dentry = dentry; |
1585 | nd->root.mnt = mnt; | |
1586 | /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ | |
1587 | return do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, nd); | |
16f18200 JJS |
1588 | } |
1589 | ||
eead1911 CH |
1590 | static struct dentry *__lookup_hash(struct qstr *name, |
1591 | struct dentry *base, struct nameidata *nd) | |
1da177e4 | 1592 | { |
81fca444 | 1593 | struct inode *inode = base->d_inode; |
057f6c01 | 1594 | struct dentry *dentry; |
1da177e4 LT |
1595 | int err; |
1596 | ||
4ad5abb3 | 1597 | err = inode_permission(inode, MAY_EXEC); |
81fca444 CH |
1598 | if (err) |
1599 | return ERR_PTR(err); | |
1da177e4 | 1600 | |
b04f784e NP |
1601 | /* |
1602 | * Don't bother with __d_lookup: callers are for creat as | |
1603 | * well as unlink, so a lot of the time it would cost | |
1604 | * a double lookup. | |
6e6b1bd1 | 1605 | */ |
b04f784e | 1606 | dentry = d_lookup(base, name); |
6e6b1bd1 | 1607 | |
44396f4b JB |
1608 | if (dentry && d_need_lookup(dentry)) { |
1609 | /* | |
1610 | * __lookup_hash is called with the parent dir's i_mutex already | |
1611 | * held, so we are good to go here. | |
1612 | */ | |
1613 | dentry = d_inode_lookup(base, dentry, nd); | |
1614 | if (IS_ERR(dentry)) | |
1615 | return dentry; | |
1616 | } | |
1617 | ||
d2d9e9fb AV |
1618 | if (dentry && (dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
1619 | int status = d_revalidate(dentry, nd); | |
1620 | if (unlikely(status <= 0)) { | |
1621 | /* | |
1622 | * The dentry failed validation. | |
1623 | * If d_revalidate returned 0 attempt to invalidate | |
1624 | * the dentry otherwise d_revalidate is asking us | |
1625 | * to return a fail status. | |
1626 | */ | |
1627 | if (status < 0) { | |
1628 | dput(dentry); | |
1629 | return ERR_PTR(status); | |
1630 | } else if (!d_invalidate(dentry)) { | |
1631 | dput(dentry); | |
1632 | dentry = NULL; | |
1633 | } | |
1634 | } | |
1635 | } | |
6e6b1bd1 | 1636 | |
baa03890 NP |
1637 | if (!dentry) |
1638 | dentry = d_alloc_and_lookup(base, name, nd); | |
5a202bcd | 1639 | |
1da177e4 LT |
1640 | return dentry; |
1641 | } | |
1642 | ||
057f6c01 JM |
1643 | /* |
1644 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
1645 | * needs parent already locked. Doesn't follow mounts. | |
1646 | * SMP-safe. | |
1647 | */ | |
eead1911 | 1648 | static struct dentry *lookup_hash(struct nameidata *nd) |
057f6c01 | 1649 | { |
4ac91378 | 1650 | return __lookup_hash(&nd->last, nd->path.dentry, nd); |
1da177e4 LT |
1651 | } |
1652 | ||
eead1911 | 1653 | /** |
a6b91919 | 1654 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
1655 | * @name: pathname component to lookup |
1656 | * @base: base directory to lookup from | |
1657 | * @len: maximum length @len should be interpreted to | |
1658 | * | |
a6b91919 RD |
1659 | * Note that this routine is purely a helper for filesystem usage and should |
1660 | * not be called by generic code. Also note that by using this function the | |
eead1911 CH |
1661 | * nameidata argument is passed to the filesystem methods and a filesystem |
1662 | * using this helper needs to be prepared for that. | |
1663 | */ | |
057f6c01 JM |
1664 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
1665 | { | |
057f6c01 | 1666 | struct qstr this; |
6a96ba54 AV |
1667 | unsigned long hash; |
1668 | unsigned int c; | |
057f6c01 | 1669 | |
2f9092e1 DW |
1670 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
1671 | ||
6a96ba54 AV |
1672 | this.name = name; |
1673 | this.len = len; | |
1674 | if (!len) | |
1675 | return ERR_PTR(-EACCES); | |
1676 | ||
1677 | hash = init_name_hash(); | |
1678 | while (len--) { | |
1679 | c = *(const unsigned char *)name++; | |
1680 | if (c == '/' || c == '\0') | |
1681 | return ERR_PTR(-EACCES); | |
1682 | hash = partial_name_hash(c, hash); | |
1683 | } | |
1684 | this.hash = end_name_hash(hash); | |
5a202bcd AV |
1685 | /* |
1686 | * See if the low-level filesystem might want | |
1687 | * to use its own hash.. | |
1688 | */ | |
1689 | if (base->d_flags & DCACHE_OP_HASH) { | |
1690 | int err = base->d_op->d_hash(base, base->d_inode, &this); | |
1691 | if (err < 0) | |
1692 | return ERR_PTR(err); | |
1693 | } | |
eead1911 | 1694 | |
49705b77 | 1695 | return __lookup_hash(&this, base, NULL); |
057f6c01 JM |
1696 | } |
1697 | ||
2d8f3038 AV |
1698 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
1699 | struct path *path) | |
1da177e4 | 1700 | { |
2d8f3038 | 1701 | struct nameidata nd; |
f52e0c11 | 1702 | char *tmp = getname_flags(name, flags); |
1da177e4 | 1703 | int err = PTR_ERR(tmp); |
1da177e4 | 1704 | if (!IS_ERR(tmp)) { |
2d8f3038 AV |
1705 | |
1706 | BUG_ON(flags & LOOKUP_PARENT); | |
1707 | ||
1708 | err = do_path_lookup(dfd, tmp, flags, &nd); | |
1da177e4 | 1709 | putname(tmp); |
2d8f3038 AV |
1710 | if (!err) |
1711 | *path = nd.path; | |
1da177e4 LT |
1712 | } |
1713 | return err; | |
1714 | } | |
1715 | ||
2ad94ae6 AV |
1716 | static int user_path_parent(int dfd, const char __user *path, |
1717 | struct nameidata *nd, char **name) | |
1718 | { | |
1719 | char *s = getname(path); | |
1720 | int error; | |
1721 | ||
1722 | if (IS_ERR(s)) | |
1723 | return PTR_ERR(s); | |
1724 | ||
1725 | error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); | |
1726 | if (error) | |
1727 | putname(s); | |
1728 | else | |
1729 | *name = s; | |
1730 | ||
1731 | return error; | |
1732 | } | |
1733 | ||
1da177e4 LT |
1734 | /* |
1735 | * It's inline, so penalty for filesystems that don't use sticky bit is | |
1736 | * minimal. | |
1737 | */ | |
1738 | static inline int check_sticky(struct inode *dir, struct inode *inode) | |
1739 | { | |
da9592ed DH |
1740 | uid_t fsuid = current_fsuid(); |
1741 | ||
1da177e4 LT |
1742 | if (!(dir->i_mode & S_ISVTX)) |
1743 | return 0; | |
e795b717 SH |
1744 | if (current_user_ns() != inode_userns(inode)) |
1745 | goto other_userns; | |
da9592ed | 1746 | if (inode->i_uid == fsuid) |
1da177e4 | 1747 | return 0; |
da9592ed | 1748 | if (dir->i_uid == fsuid) |
1da177e4 | 1749 | return 0; |
e795b717 SH |
1750 | |
1751 | other_userns: | |
1752 | return !ns_capable(inode_userns(inode), CAP_FOWNER); | |
1da177e4 LT |
1753 | } |
1754 | ||
1755 | /* | |
1756 | * Check whether we can remove a link victim from directory dir, check | |
1757 | * whether the type of victim is right. | |
1758 | * 1. We can't do it if dir is read-only (done in permission()) | |
1759 | * 2. We should have write and exec permissions on dir | |
1760 | * 3. We can't remove anything from append-only dir | |
1761 | * 4. We can't do anything with immutable dir (done in permission()) | |
1762 | * 5. If the sticky bit on dir is set we should either | |
1763 | * a. be owner of dir, or | |
1764 | * b. be owner of victim, or | |
1765 | * c. have CAP_FOWNER capability | |
1766 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
1767 | * links pointing to it. | |
1768 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
1769 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
1770 | * 9. We can't remove a root or mountpoint. | |
1771 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
1772 | * nfs_async_unlink(). | |
1773 | */ | |
858119e1 | 1774 | static int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
1da177e4 LT |
1775 | { |
1776 | int error; | |
1777 | ||
1778 | if (!victim->d_inode) | |
1779 | return -ENOENT; | |
1780 | ||
1781 | BUG_ON(victim->d_parent->d_inode != dir); | |
cccc6bba | 1782 | audit_inode_child(victim, dir); |
1da177e4 | 1783 | |
f419a2e3 | 1784 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
1785 | if (error) |
1786 | return error; | |
1787 | if (IS_APPEND(dir)) | |
1788 | return -EPERM; | |
1789 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| | |
f9454548 | 1790 | IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) |
1da177e4 LT |
1791 | return -EPERM; |
1792 | if (isdir) { | |
1793 | if (!S_ISDIR(victim->d_inode->i_mode)) | |
1794 | return -ENOTDIR; | |
1795 | if (IS_ROOT(victim)) | |
1796 | return -EBUSY; | |
1797 | } else if (S_ISDIR(victim->d_inode->i_mode)) | |
1798 | return -EISDIR; | |
1799 | if (IS_DEADDIR(dir)) | |
1800 | return -ENOENT; | |
1801 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
1802 | return -EBUSY; | |
1803 | return 0; | |
1804 | } | |
1805 | ||
1806 | /* Check whether we can create an object with dentry child in directory | |
1807 | * dir. | |
1808 | * 1. We can't do it if child already exists (open has special treatment for | |
1809 | * this case, but since we are inlined it's OK) | |
1810 | * 2. We can't do it if dir is read-only (done in permission()) | |
1811 | * 3. We should have write and exec permissions on dir | |
1812 | * 4. We can't do it if dir is immutable (done in permission()) | |
1813 | */ | |
a95164d9 | 1814 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 LT |
1815 | { |
1816 | if (child->d_inode) | |
1817 | return -EEXIST; | |
1818 | if (IS_DEADDIR(dir)) | |
1819 | return -ENOENT; | |
f419a2e3 | 1820 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
1821 | } |
1822 | ||
1da177e4 LT |
1823 | /* |
1824 | * p1 and p2 should be directories on the same fs. | |
1825 | */ | |
1826 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
1827 | { | |
1828 | struct dentry *p; | |
1829 | ||
1830 | if (p1 == p2) { | |
f2eace23 | 1831 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
1832 | return NULL; |
1833 | } | |
1834 | ||
a11f3a05 | 1835 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 | 1836 | |
e2761a11 OH |
1837 | p = d_ancestor(p2, p1); |
1838 | if (p) { | |
1839 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); | |
1840 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
1841 | return p; | |
1da177e4 LT |
1842 | } |
1843 | ||
e2761a11 OH |
1844 | p = d_ancestor(p1, p2); |
1845 | if (p) { | |
1846 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); | |
1847 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1848 | return p; | |
1da177e4 LT |
1849 | } |
1850 | ||
f2eace23 IM |
1851 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1852 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1da177e4 LT |
1853 | return NULL; |
1854 | } | |
1855 | ||
1856 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
1857 | { | |
1b1dcc1b | 1858 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 1859 | if (p1 != p2) { |
1b1dcc1b | 1860 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 1861 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
1862 | } |
1863 | } | |
1864 | ||
1865 | int vfs_create(struct inode *dir, struct dentry *dentry, int mode, | |
1866 | struct nameidata *nd) | |
1867 | { | |
a95164d9 | 1868 | int error = may_create(dir, dentry); |
1da177e4 LT |
1869 | |
1870 | if (error) | |
1871 | return error; | |
1872 | ||
acfa4380 | 1873 | if (!dir->i_op->create) |
1da177e4 LT |
1874 | return -EACCES; /* shouldn't it be ENOSYS? */ |
1875 | mode &= S_IALLUGO; | |
1876 | mode |= S_IFREG; | |
1877 | error = security_inode_create(dir, dentry, mode); | |
1878 | if (error) | |
1879 | return error; | |
1da177e4 | 1880 | error = dir->i_op->create(dir, dentry, mode, nd); |
a74574aa | 1881 | if (!error) |
f38aa942 | 1882 | fsnotify_create(dir, dentry); |
1da177e4 LT |
1883 | return error; |
1884 | } | |
1885 | ||
73d049a4 | 1886 | static int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 1887 | { |
3fb64190 | 1888 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
1889 | struct inode *inode = dentry->d_inode; |
1890 | int error; | |
1891 | ||
bcda7652 AV |
1892 | /* O_PATH? */ |
1893 | if (!acc_mode) | |
1894 | return 0; | |
1895 | ||
1da177e4 LT |
1896 | if (!inode) |
1897 | return -ENOENT; | |
1898 | ||
c8fe8f30 CH |
1899 | switch (inode->i_mode & S_IFMT) { |
1900 | case S_IFLNK: | |
1da177e4 | 1901 | return -ELOOP; |
c8fe8f30 CH |
1902 | case S_IFDIR: |
1903 | if (acc_mode & MAY_WRITE) | |
1904 | return -EISDIR; | |
1905 | break; | |
1906 | case S_IFBLK: | |
1907 | case S_IFCHR: | |
3fb64190 | 1908 | if (path->mnt->mnt_flags & MNT_NODEV) |
1da177e4 | 1909 | return -EACCES; |
c8fe8f30 CH |
1910 | /*FALLTHRU*/ |
1911 | case S_IFIFO: | |
1912 | case S_IFSOCK: | |
1da177e4 | 1913 | flag &= ~O_TRUNC; |
c8fe8f30 | 1914 | break; |
4a3fd211 | 1915 | } |
b41572e9 | 1916 | |
3fb64190 | 1917 | error = inode_permission(inode, acc_mode); |
b41572e9 DH |
1918 | if (error) |
1919 | return error; | |
6146f0d5 | 1920 | |
1da177e4 LT |
1921 | /* |
1922 | * An append-only file must be opened in append mode for writing. | |
1923 | */ | |
1924 | if (IS_APPEND(inode)) { | |
8737c930 | 1925 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
7715b521 | 1926 | return -EPERM; |
1da177e4 | 1927 | if (flag & O_TRUNC) |
7715b521 | 1928 | return -EPERM; |
1da177e4 LT |
1929 | } |
1930 | ||
1931 | /* O_NOATIME can only be set by the owner or superuser */ | |
2e149670 | 1932 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
7715b521 | 1933 | return -EPERM; |
1da177e4 LT |
1934 | |
1935 | /* | |
1936 | * Ensure there are no outstanding leases on the file. | |
1937 | */ | |
b65a9cfc | 1938 | return break_lease(inode, flag); |
7715b521 | 1939 | } |
1da177e4 | 1940 | |
e1181ee6 | 1941 | static int handle_truncate(struct file *filp) |
7715b521 | 1942 | { |
e1181ee6 | 1943 | struct path *path = &filp->f_path; |
7715b521 AV |
1944 | struct inode *inode = path->dentry->d_inode; |
1945 | int error = get_write_access(inode); | |
1946 | if (error) | |
1947 | return error; | |
1948 | /* | |
1949 | * Refuse to truncate files with mandatory locks held on them. | |
1950 | */ | |
1951 | error = locks_verify_locked(inode); | |
1952 | if (!error) | |
ea0d3ab2 | 1953 | error = security_path_truncate(path); |
7715b521 AV |
1954 | if (!error) { |
1955 | error = do_truncate(path->dentry, 0, | |
1956 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
e1181ee6 | 1957 | filp); |
7715b521 AV |
1958 | } |
1959 | put_write_access(inode); | |
acd0c935 | 1960 | return error; |
1da177e4 LT |
1961 | } |
1962 | ||
d57999e1 DH |
1963 | static inline int open_to_namei_flags(int flag) |
1964 | { | |
8a5e929d AV |
1965 | if ((flag & O_ACCMODE) == 3) |
1966 | flag--; | |
d57999e1 DH |
1967 | return flag; |
1968 | } | |
1969 | ||
31e6b01f | 1970 | /* |
fe2d35ff | 1971 | * Handle the last step of open() |
31e6b01f | 1972 | */ |
fb1cc555 | 1973 | static struct file *do_last(struct nameidata *nd, struct path *path, |
c3e380b0 | 1974 | const struct open_flags *op, const char *pathname) |
fb1cc555 | 1975 | { |
a1e28038 | 1976 | struct dentry *dir = nd->path.dentry; |
6c0d46c4 | 1977 | struct dentry *dentry; |
ca344a89 | 1978 | int open_flag = op->open_flag; |
6c0d46c4 | 1979 | int will_truncate = open_flag & O_TRUNC; |
ca344a89 | 1980 | int want_write = 0; |
bcda7652 | 1981 | int acc_mode = op->acc_mode; |
fb1cc555 | 1982 | struct file *filp; |
16c2cd71 | 1983 | int error; |
1f36f774 | 1984 | |
c3e380b0 AV |
1985 | nd->flags &= ~LOOKUP_PARENT; |
1986 | nd->flags |= op->intent; | |
1987 | ||
1f36f774 AV |
1988 | switch (nd->last_type) { |
1989 | case LAST_DOTDOT: | |
176306f5 | 1990 | case LAST_DOT: |
fe2d35ff AV |
1991 | error = handle_dots(nd, nd->last_type); |
1992 | if (error) | |
1993 | return ERR_PTR(error); | |
1f36f774 | 1994 | /* fallthrough */ |
1f36f774 | 1995 | case LAST_ROOT: |
9f1fafee | 1996 | error = complete_walk(nd); |
16c2cd71 | 1997 | if (error) |
9f1fafee | 1998 | return ERR_PTR(error); |
fe2d35ff | 1999 | audit_inode(pathname, nd->path.dentry); |
ca344a89 | 2000 | if (open_flag & O_CREAT) { |
fe2d35ff AV |
2001 | error = -EISDIR; |
2002 | goto exit; | |
2003 | } | |
2004 | goto ok; | |
1f36f774 | 2005 | case LAST_BIND: |
9f1fafee | 2006 | error = complete_walk(nd); |
16c2cd71 | 2007 | if (error) |
9f1fafee | 2008 | return ERR_PTR(error); |
1f36f774 | 2009 | audit_inode(pathname, dir); |
67ee3ad2 | 2010 | goto ok; |
1f36f774 | 2011 | } |
67ee3ad2 | 2012 | |
ca344a89 | 2013 | if (!(open_flag & O_CREAT)) { |
bcda7652 | 2014 | int symlink_ok = 0; |
fe2d35ff AV |
2015 | if (nd->last.name[nd->last.len]) |
2016 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
bcda7652 AV |
2017 | if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) |
2018 | symlink_ok = 1; | |
fe2d35ff | 2019 | /* we _can_ be in RCU mode here */ |
ce57dfc1 AV |
2020 | error = walk_component(nd, path, &nd->last, LAST_NORM, |
2021 | !symlink_ok); | |
2022 | if (error < 0) | |
fe2d35ff | 2023 | return ERR_PTR(error); |
ce57dfc1 | 2024 | if (error) /* symlink */ |
fe2d35ff | 2025 | return NULL; |
fe2d35ff | 2026 | /* sayonara */ |
9f1fafee AV |
2027 | error = complete_walk(nd); |
2028 | if (error) | |
2029 | return ERR_PTR(-ECHILD); | |
fe2d35ff AV |
2030 | |
2031 | error = -ENOTDIR; | |
2032 | if (nd->flags & LOOKUP_DIRECTORY) { | |
ce57dfc1 | 2033 | if (!nd->inode->i_op->lookup) |
fe2d35ff AV |
2034 | goto exit; |
2035 | } | |
2036 | audit_inode(pathname, nd->path.dentry); | |
2037 | goto ok; | |
2038 | } | |
2039 | ||
2040 | /* create side of things */ | |
9f1fafee AV |
2041 | error = complete_walk(nd); |
2042 | if (error) | |
2043 | return ERR_PTR(error); | |
fe2d35ff AV |
2044 | |
2045 | audit_inode(pathname, dir); | |
16c2cd71 | 2046 | error = -EISDIR; |
1f36f774 | 2047 | /* trailing slashes? */ |
31e6b01f NP |
2048 | if (nd->last.name[nd->last.len]) |
2049 | goto exit; | |
a2c36b45 | 2050 | |
a1e28038 AV |
2051 | mutex_lock(&dir->d_inode->i_mutex); |
2052 | ||
6c0d46c4 AV |
2053 | dentry = lookup_hash(nd); |
2054 | error = PTR_ERR(dentry); | |
2055 | if (IS_ERR(dentry)) { | |
fb1cc555 AV |
2056 | mutex_unlock(&dir->d_inode->i_mutex); |
2057 | goto exit; | |
2058 | } | |
2059 | ||
6c0d46c4 AV |
2060 | path->dentry = dentry; |
2061 | path->mnt = nd->path.mnt; | |
2062 | ||
fb1cc555 | 2063 | /* Negative dentry, just create the file */ |
6c0d46c4 AV |
2064 | if (!dentry->d_inode) { |
2065 | int mode = op->mode; | |
2066 | if (!IS_POSIXACL(dir->d_inode)) | |
2067 | mode &= ~current_umask(); | |
fb1cc555 AV |
2068 | /* |
2069 | * This write is needed to ensure that a | |
6c0d46c4 | 2070 | * rw->ro transition does not occur between |
fb1cc555 AV |
2071 | * the time when the file is created and when |
2072 | * a permanent write count is taken through | |
2073 | * the 'struct file' in nameidata_to_filp(). | |
2074 | */ | |
2075 | error = mnt_want_write(nd->path.mnt); | |
2076 | if (error) | |
2077 | goto exit_mutex_unlock; | |
ca344a89 | 2078 | want_write = 1; |
9b44f1b3 | 2079 | /* Don't check for write permission, don't truncate */ |
ca344a89 | 2080 | open_flag &= ~O_TRUNC; |
6c0d46c4 | 2081 | will_truncate = 0; |
bcda7652 | 2082 | acc_mode = MAY_OPEN; |
6c0d46c4 AV |
2083 | error = security_path_mknod(&nd->path, dentry, mode, 0); |
2084 | if (error) | |
2085 | goto exit_mutex_unlock; | |
2086 | error = vfs_create(dir->d_inode, dentry, mode, nd); | |
2087 | if (error) | |
2088 | goto exit_mutex_unlock; | |
2089 | mutex_unlock(&dir->d_inode->i_mutex); | |
2090 | dput(nd->path.dentry); | |
2091 | nd->path.dentry = dentry; | |
ca344a89 | 2092 | goto common; |
fb1cc555 AV |
2093 | } |
2094 | ||
2095 | /* | |
2096 | * It already exists. | |
2097 | */ | |
2098 | mutex_unlock(&dir->d_inode->i_mutex); | |
2099 | audit_inode(pathname, path->dentry); | |
2100 | ||
2101 | error = -EEXIST; | |
ca344a89 | 2102 | if (open_flag & O_EXCL) |
fb1cc555 AV |
2103 | goto exit_dput; |
2104 | ||
9875cf80 DH |
2105 | error = follow_managed(path, nd->flags); |
2106 | if (error < 0) | |
2107 | goto exit_dput; | |
fb1cc555 AV |
2108 | |
2109 | error = -ENOENT; | |
2110 | if (!path->dentry->d_inode) | |
2111 | goto exit_dput; | |
9e67f361 AV |
2112 | |
2113 | if (path->dentry->d_inode->i_op->follow_link) | |
fb1cc555 | 2114 | return NULL; |
fb1cc555 AV |
2115 | |
2116 | path_to_nameidata(path, nd); | |
31e6b01f | 2117 | nd->inode = path->dentry->d_inode; |
fb1cc555 | 2118 | error = -EISDIR; |
31e6b01f | 2119 | if (S_ISDIR(nd->inode->i_mode)) |
fb1cc555 | 2120 | goto exit; |
67ee3ad2 | 2121 | ok: |
6c0d46c4 AV |
2122 | if (!S_ISREG(nd->inode->i_mode)) |
2123 | will_truncate = 0; | |
2124 | ||
0f9d1a10 AV |
2125 | if (will_truncate) { |
2126 | error = mnt_want_write(nd->path.mnt); | |
2127 | if (error) | |
2128 | goto exit; | |
ca344a89 | 2129 | want_write = 1; |
0f9d1a10 | 2130 | } |
ca344a89 | 2131 | common: |
bcda7652 | 2132 | error = may_open(&nd->path, acc_mode, open_flag); |
ca344a89 | 2133 | if (error) |
0f9d1a10 | 2134 | goto exit; |
0f9d1a10 AV |
2135 | filp = nameidata_to_filp(nd); |
2136 | if (!IS_ERR(filp)) { | |
2137 | error = ima_file_check(filp, op->acc_mode); | |
2138 | if (error) { | |
2139 | fput(filp); | |
2140 | filp = ERR_PTR(error); | |
2141 | } | |
2142 | } | |
2143 | if (!IS_ERR(filp)) { | |
2144 | if (will_truncate) { | |
2145 | error = handle_truncate(filp); | |
2146 | if (error) { | |
2147 | fput(filp); | |
2148 | filp = ERR_PTR(error); | |
2149 | } | |
2150 | } | |
2151 | } | |
ca344a89 AV |
2152 | out: |
2153 | if (want_write) | |
0f9d1a10 AV |
2154 | mnt_drop_write(nd->path.mnt); |
2155 | path_put(&nd->path); | |
fb1cc555 AV |
2156 | return filp; |
2157 | ||
2158 | exit_mutex_unlock: | |
2159 | mutex_unlock(&dir->d_inode->i_mutex); | |
2160 | exit_dput: | |
2161 | path_put_conditional(path, nd); | |
2162 | exit: | |
ca344a89 AV |
2163 | filp = ERR_PTR(error); |
2164 | goto out; | |
fb1cc555 AV |
2165 | } |
2166 | ||
13aab428 | 2167 | static struct file *path_openat(int dfd, const char *pathname, |
73d049a4 | 2168 | struct nameidata *nd, const struct open_flags *op, int flags) |
1da177e4 | 2169 | { |
fe2d35ff | 2170 | struct file *base = NULL; |
4a3fd211 | 2171 | struct file *filp; |
9850c056 | 2172 | struct path path; |
13aab428 | 2173 | int error; |
31e6b01f NP |
2174 | |
2175 | filp = get_empty_filp(); | |
2176 | if (!filp) | |
2177 | return ERR_PTR(-ENFILE); | |
2178 | ||
47c805dc | 2179 | filp->f_flags = op->open_flag; |
73d049a4 AV |
2180 | nd->intent.open.file = filp; |
2181 | nd->intent.open.flags = open_to_namei_flags(op->open_flag); | |
2182 | nd->intent.open.create_mode = op->mode; | |
31e6b01f | 2183 | |
73d049a4 | 2184 | error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); |
31e6b01f | 2185 | if (unlikely(error)) |
13aab428 | 2186 | goto out_filp; |
31e6b01f | 2187 | |
fe2d35ff | 2188 | current->total_link_count = 0; |
73d049a4 | 2189 | error = link_path_walk(pathname, nd); |
31e6b01f NP |
2190 | if (unlikely(error)) |
2191 | goto out_filp; | |
1da177e4 | 2192 | |
73d049a4 | 2193 | filp = do_last(nd, &path, op, pathname); |
806b681c | 2194 | while (unlikely(!filp)) { /* trailing symlink */ |
7b9337aa | 2195 | struct path link = path; |
def4af30 | 2196 | void *cookie; |
574197e0 | 2197 | if (!(nd->flags & LOOKUP_FOLLOW)) { |
73d049a4 AV |
2198 | path_put_conditional(&path, nd); |
2199 | path_put(&nd->path); | |
40b39136 AV |
2200 | filp = ERR_PTR(-ELOOP); |
2201 | break; | |
2202 | } | |
73d049a4 AV |
2203 | nd->flags |= LOOKUP_PARENT; |
2204 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); | |
574197e0 | 2205 | error = follow_link(&link, nd, &cookie); |
c3e380b0 | 2206 | if (unlikely(error)) |
f1afe9ef | 2207 | filp = ERR_PTR(error); |
c3e380b0 | 2208 | else |
73d049a4 | 2209 | filp = do_last(nd, &path, op, pathname); |
574197e0 | 2210 | put_link(nd, &link, cookie); |
806b681c | 2211 | } |
10fa8e62 | 2212 | out: |
73d049a4 AV |
2213 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) |
2214 | path_put(&nd->root); | |
fe2d35ff AV |
2215 | if (base) |
2216 | fput(base); | |
73d049a4 | 2217 | release_open_intent(nd); |
10fa8e62 | 2218 | return filp; |
1da177e4 | 2219 | |
31e6b01f | 2220 | out_filp: |
806b681c | 2221 | filp = ERR_PTR(error); |
10fa8e62 | 2222 | goto out; |
1da177e4 LT |
2223 | } |
2224 | ||
13aab428 AV |
2225 | struct file *do_filp_open(int dfd, const char *pathname, |
2226 | const struct open_flags *op, int flags) | |
2227 | { | |
73d049a4 | 2228 | struct nameidata nd; |
13aab428 AV |
2229 | struct file *filp; |
2230 | ||
73d049a4 | 2231 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); |
13aab428 | 2232 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
73d049a4 | 2233 | filp = path_openat(dfd, pathname, &nd, op, flags); |
13aab428 | 2234 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
73d049a4 | 2235 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); |
13aab428 AV |
2236 | return filp; |
2237 | } | |
2238 | ||
73d049a4 AV |
2239 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
2240 | const char *name, const struct open_flags *op, int flags) | |
2241 | { | |
2242 | struct nameidata nd; | |
2243 | struct file *file; | |
2244 | ||
2245 | nd.root.mnt = mnt; | |
2246 | nd.root.dentry = dentry; | |
2247 | ||
2248 | flags |= LOOKUP_ROOT; | |
2249 | ||
bcda7652 | 2250 | if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) |
73d049a4 AV |
2251 | return ERR_PTR(-ELOOP); |
2252 | ||
2253 | file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); | |
2254 | if (unlikely(file == ERR_PTR(-ECHILD))) | |
2255 | file = path_openat(-1, name, &nd, op, flags); | |
2256 | if (unlikely(file == ERR_PTR(-ESTALE))) | |
2257 | file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); | |
2258 | return file; | |
2259 | } | |
2260 | ||
ed75e95d | 2261 | struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) |
1da177e4 | 2262 | { |
c663e5d8 | 2263 | struct dentry *dentry = ERR_PTR(-EEXIST); |
ed75e95d AV |
2264 | struct nameidata nd; |
2265 | int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); | |
2266 | if (error) | |
2267 | return ERR_PTR(error); | |
1da177e4 | 2268 | |
c663e5d8 CH |
2269 | /* |
2270 | * Yucky last component or no last component at all? | |
2271 | * (foo/., foo/.., /////) | |
2272 | */ | |
ed75e95d AV |
2273 | if (nd.last_type != LAST_NORM) |
2274 | goto out; | |
2275 | nd.flags &= ~LOOKUP_PARENT; | |
2276 | nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; | |
2277 | nd.intent.open.flags = O_EXCL; | |
c663e5d8 CH |
2278 | |
2279 | /* | |
2280 | * Do the final lookup. | |
2281 | */ | |
ed75e95d AV |
2282 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
2283 | dentry = lookup_hash(&nd); | |
1da177e4 LT |
2284 | if (IS_ERR(dentry)) |
2285 | goto fail; | |
c663e5d8 | 2286 | |
e9baf6e5 AV |
2287 | if (dentry->d_inode) |
2288 | goto eexist; | |
c663e5d8 CH |
2289 | /* |
2290 | * Special case - lookup gave negative, but... we had foo/bar/ | |
2291 | * From the vfs_mknod() POV we just have a negative dentry - | |
2292 | * all is fine. Let's be bastards - you had / on the end, you've | |
2293 | * been asking for (non-existent) directory. -ENOENT for you. | |
2294 | */ | |
ed75e95d | 2295 | if (unlikely(!is_dir && nd.last.name[nd.last.len])) { |
e9baf6e5 AV |
2296 | dput(dentry); |
2297 | dentry = ERR_PTR(-ENOENT); | |
ed75e95d | 2298 | goto fail; |
e9baf6e5 | 2299 | } |
ed75e95d | 2300 | *path = nd.path; |
1da177e4 | 2301 | return dentry; |
e9baf6e5 | 2302 | eexist: |
1da177e4 | 2303 | dput(dentry); |
e9baf6e5 | 2304 | dentry = ERR_PTR(-EEXIST); |
1da177e4 | 2305 | fail: |
ed75e95d AV |
2306 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
2307 | out: | |
2308 | path_put(&nd.path); | |
1da177e4 LT |
2309 | return dentry; |
2310 | } | |
dae6ad8f AV |
2311 | EXPORT_SYMBOL(kern_path_create); |
2312 | ||
2313 | struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) | |
2314 | { | |
2315 | char *tmp = getname(pathname); | |
2316 | struct dentry *res; | |
2317 | if (IS_ERR(tmp)) | |
2318 | return ERR_CAST(tmp); | |
2319 | res = kern_path_create(dfd, tmp, path, is_dir); | |
2320 | putname(tmp); | |
2321 | return res; | |
2322 | } | |
2323 | EXPORT_SYMBOL(user_path_create); | |
2324 | ||
1da177e4 LT |
2325 | int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) |
2326 | { | |
a95164d9 | 2327 | int error = may_create(dir, dentry); |
1da177e4 LT |
2328 | |
2329 | if (error) | |
2330 | return error; | |
2331 | ||
e795b717 SH |
2332 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && |
2333 | !ns_capable(inode_userns(dir), CAP_MKNOD)) | |
1da177e4 LT |
2334 | return -EPERM; |
2335 | ||
acfa4380 | 2336 | if (!dir->i_op->mknod) |
1da177e4 LT |
2337 | return -EPERM; |
2338 | ||
08ce5f16 SH |
2339 | error = devcgroup_inode_mknod(mode, dev); |
2340 | if (error) | |
2341 | return error; | |
2342 | ||
1da177e4 LT |
2343 | error = security_inode_mknod(dir, dentry, mode, dev); |
2344 | if (error) | |
2345 | return error; | |
2346 | ||
1da177e4 | 2347 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 2348 | if (!error) |
f38aa942 | 2349 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2350 | return error; |
2351 | } | |
2352 | ||
463c3197 DH |
2353 | static int may_mknod(mode_t mode) |
2354 | { | |
2355 | switch (mode & S_IFMT) { | |
2356 | case S_IFREG: | |
2357 | case S_IFCHR: | |
2358 | case S_IFBLK: | |
2359 | case S_IFIFO: | |
2360 | case S_IFSOCK: | |
2361 | case 0: /* zero mode translates to S_IFREG */ | |
2362 | return 0; | |
2363 | case S_IFDIR: | |
2364 | return -EPERM; | |
2365 | default: | |
2366 | return -EINVAL; | |
2367 | } | |
2368 | } | |
2369 | ||
2e4d0924 HC |
2370 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, |
2371 | unsigned, dev) | |
1da177e4 | 2372 | { |
2ad94ae6 | 2373 | struct dentry *dentry; |
dae6ad8f AV |
2374 | struct path path; |
2375 | int error; | |
1da177e4 LT |
2376 | |
2377 | if (S_ISDIR(mode)) | |
2378 | return -EPERM; | |
1da177e4 | 2379 | |
dae6ad8f AV |
2380 | dentry = user_path_create(dfd, filename, &path, 0); |
2381 | if (IS_ERR(dentry)) | |
2382 | return PTR_ERR(dentry); | |
2ad94ae6 | 2383 | |
dae6ad8f | 2384 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 2385 | mode &= ~current_umask(); |
463c3197 DH |
2386 | error = may_mknod(mode); |
2387 | if (error) | |
2388 | goto out_dput; | |
dae6ad8f | 2389 | error = mnt_want_write(path.mnt); |
463c3197 DH |
2390 | if (error) |
2391 | goto out_dput; | |
dae6ad8f | 2392 | error = security_path_mknod(&path, dentry, mode, dev); |
be6d3e56 KT |
2393 | if (error) |
2394 | goto out_drop_write; | |
463c3197 | 2395 | switch (mode & S_IFMT) { |
1da177e4 | 2396 | case 0: case S_IFREG: |
dae6ad8f | 2397 | error = vfs_create(path.dentry->d_inode,dentry,mode,NULL); |
1da177e4 LT |
2398 | break; |
2399 | case S_IFCHR: case S_IFBLK: | |
dae6ad8f | 2400 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
2401 | new_decode_dev(dev)); |
2402 | break; | |
2403 | case S_IFIFO: case S_IFSOCK: | |
dae6ad8f | 2404 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 2405 | break; |
1da177e4 | 2406 | } |
be6d3e56 | 2407 | out_drop_write: |
dae6ad8f | 2408 | mnt_drop_write(path.mnt); |
463c3197 DH |
2409 | out_dput: |
2410 | dput(dentry); | |
dae6ad8f AV |
2411 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
2412 | path_put(&path); | |
1da177e4 LT |
2413 | |
2414 | return error; | |
2415 | } | |
2416 | ||
3480b257 | 2417 | SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) |
5590ff0d UD |
2418 | { |
2419 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
2420 | } | |
2421 | ||
1da177e4 LT |
2422 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
2423 | { | |
a95164d9 | 2424 | int error = may_create(dir, dentry); |
1da177e4 LT |
2425 | |
2426 | if (error) | |
2427 | return error; | |
2428 | ||
acfa4380 | 2429 | if (!dir->i_op->mkdir) |
1da177e4 LT |
2430 | return -EPERM; |
2431 | ||
2432 | mode &= (S_IRWXUGO|S_ISVTX); | |
2433 | error = security_inode_mkdir(dir, dentry, mode); | |
2434 | if (error) | |
2435 | return error; | |
2436 | ||
1da177e4 | 2437 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 2438 | if (!error) |
f38aa942 | 2439 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
2440 | return error; |
2441 | } | |
2442 | ||
2e4d0924 | 2443 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) |
1da177e4 | 2444 | { |
6902d925 | 2445 | struct dentry *dentry; |
dae6ad8f AV |
2446 | struct path path; |
2447 | int error; | |
1da177e4 | 2448 | |
dae6ad8f | 2449 | dentry = user_path_create(dfd, pathname, &path, 1); |
6902d925 | 2450 | if (IS_ERR(dentry)) |
dae6ad8f | 2451 | return PTR_ERR(dentry); |
1da177e4 | 2452 | |
dae6ad8f | 2453 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 2454 | mode &= ~current_umask(); |
dae6ad8f | 2455 | error = mnt_want_write(path.mnt); |
463c3197 DH |
2456 | if (error) |
2457 | goto out_dput; | |
dae6ad8f | 2458 | error = security_path_mkdir(&path, dentry, mode); |
be6d3e56 KT |
2459 | if (error) |
2460 | goto out_drop_write; | |
dae6ad8f | 2461 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); |
be6d3e56 | 2462 | out_drop_write: |
dae6ad8f | 2463 | mnt_drop_write(path.mnt); |
463c3197 | 2464 | out_dput: |
6902d925 | 2465 | dput(dentry); |
dae6ad8f AV |
2466 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
2467 | path_put(&path); | |
1da177e4 LT |
2468 | return error; |
2469 | } | |
2470 | ||
3cdad428 | 2471 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) |
5590ff0d UD |
2472 | { |
2473 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
2474 | } | |
2475 | ||
1da177e4 | 2476 | /* |
a71905f0 SW |
2477 | * The dentry_unhash() helper will try to drop the dentry early: we |
2478 | * should have a usage count of 2 if we're the only user of this | |
2479 | * dentry, and if that is true (possibly after pruning the dcache), | |
2480 | * then we drop the dentry now. | |
1da177e4 LT |
2481 | * |
2482 | * A low-level filesystem can, if it choses, legally | |
2483 | * do a | |
2484 | * | |
2485 | * if (!d_unhashed(dentry)) | |
2486 | * return -EBUSY; | |
2487 | * | |
2488 | * if it cannot handle the case of removing a directory | |
2489 | * that is still in use by something else.. | |
2490 | */ | |
2491 | void dentry_unhash(struct dentry *dentry) | |
2492 | { | |
dc168427 | 2493 | shrink_dcache_parent(dentry); |
1da177e4 | 2494 | spin_lock(&dentry->d_lock); |
64252c75 | 2495 | if (dentry->d_count == 1) |
1da177e4 LT |
2496 | __d_drop(dentry); |
2497 | spin_unlock(&dentry->d_lock); | |
1da177e4 LT |
2498 | } |
2499 | ||
2500 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
2501 | { | |
2502 | int error = may_delete(dir, dentry, 1); | |
2503 | ||
2504 | if (error) | |
2505 | return error; | |
2506 | ||
acfa4380 | 2507 | if (!dir->i_op->rmdir) |
1da177e4 LT |
2508 | return -EPERM; |
2509 | ||
1b1dcc1b | 2510 | mutex_lock(&dentry->d_inode->i_mutex); |
912dbc15 SW |
2511 | |
2512 | error = -EBUSY; | |
1da177e4 | 2513 | if (d_mountpoint(dentry)) |
912dbc15 SW |
2514 | goto out; |
2515 | ||
2516 | error = security_inode_rmdir(dir, dentry); | |
2517 | if (error) | |
2518 | goto out; | |
2519 | ||
3cebde24 | 2520 | shrink_dcache_parent(dentry); |
912dbc15 SW |
2521 | error = dir->i_op->rmdir(dir, dentry); |
2522 | if (error) | |
2523 | goto out; | |
2524 | ||
2525 | dentry->d_inode->i_flags |= S_DEAD; | |
2526 | dont_mount(dentry); | |
2527 | ||
2528 | out: | |
1b1dcc1b | 2529 | mutex_unlock(&dentry->d_inode->i_mutex); |
912dbc15 | 2530 | if (!error) |
1da177e4 | 2531 | d_delete(dentry); |
1da177e4 LT |
2532 | return error; |
2533 | } | |
2534 | ||
5590ff0d | 2535 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
2536 | { |
2537 | int error = 0; | |
2538 | char * name; | |
2539 | struct dentry *dentry; | |
2540 | struct nameidata nd; | |
2541 | ||
2ad94ae6 | 2542 | error = user_path_parent(dfd, pathname, &nd, &name); |
1da177e4 | 2543 | if (error) |
2ad94ae6 | 2544 | return error; |
1da177e4 LT |
2545 | |
2546 | switch(nd.last_type) { | |
0612d9fb OH |
2547 | case LAST_DOTDOT: |
2548 | error = -ENOTEMPTY; | |
2549 | goto exit1; | |
2550 | case LAST_DOT: | |
2551 | error = -EINVAL; | |
2552 | goto exit1; | |
2553 | case LAST_ROOT: | |
2554 | error = -EBUSY; | |
2555 | goto exit1; | |
1da177e4 | 2556 | } |
0612d9fb OH |
2557 | |
2558 | nd.flags &= ~LOOKUP_PARENT; | |
2559 | ||
4ac91378 | 2560 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2561 | dentry = lookup_hash(&nd); |
1da177e4 | 2562 | error = PTR_ERR(dentry); |
6902d925 DH |
2563 | if (IS_ERR(dentry)) |
2564 | goto exit2; | |
e6bc45d6 TT |
2565 | if (!dentry->d_inode) { |
2566 | error = -ENOENT; | |
2567 | goto exit3; | |
2568 | } | |
0622753b DH |
2569 | error = mnt_want_write(nd.path.mnt); |
2570 | if (error) | |
2571 | goto exit3; | |
be6d3e56 KT |
2572 | error = security_path_rmdir(&nd.path, dentry); |
2573 | if (error) | |
2574 | goto exit4; | |
4ac91378 | 2575 | error = vfs_rmdir(nd.path.dentry->d_inode, dentry); |
be6d3e56 | 2576 | exit4: |
0622753b DH |
2577 | mnt_drop_write(nd.path.mnt); |
2578 | exit3: | |
6902d925 DH |
2579 | dput(dentry); |
2580 | exit2: | |
4ac91378 | 2581 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 | 2582 | exit1: |
1d957f9b | 2583 | path_put(&nd.path); |
1da177e4 LT |
2584 | putname(name); |
2585 | return error; | |
2586 | } | |
2587 | ||
3cdad428 | 2588 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
2589 | { |
2590 | return do_rmdir(AT_FDCWD, pathname); | |
2591 | } | |
2592 | ||
1da177e4 LT |
2593 | int vfs_unlink(struct inode *dir, struct dentry *dentry) |
2594 | { | |
2595 | int error = may_delete(dir, dentry, 0); | |
2596 | ||
2597 | if (error) | |
2598 | return error; | |
2599 | ||
acfa4380 | 2600 | if (!dir->i_op->unlink) |
1da177e4 LT |
2601 | return -EPERM; |
2602 | ||
1b1dcc1b | 2603 | mutex_lock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2604 | if (d_mountpoint(dentry)) |
2605 | error = -EBUSY; | |
2606 | else { | |
2607 | error = security_inode_unlink(dir, dentry); | |
bec1052e | 2608 | if (!error) { |
1da177e4 | 2609 | error = dir->i_op->unlink(dir, dentry); |
bec1052e | 2610 | if (!error) |
d83c49f3 | 2611 | dont_mount(dentry); |
bec1052e | 2612 | } |
1da177e4 | 2613 | } |
1b1dcc1b | 2614 | mutex_unlock(&dentry->d_inode->i_mutex); |
1da177e4 LT |
2615 | |
2616 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
2617 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
ece95912 | 2618 | fsnotify_link_count(dentry->d_inode); |
e234f35c | 2619 | d_delete(dentry); |
1da177e4 | 2620 | } |
0eeca283 | 2621 | |
1da177e4 LT |
2622 | return error; |
2623 | } | |
2624 | ||
2625 | /* | |
2626 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 2627 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
2628 | * writeout happening, and we don't want to prevent access to the directory |
2629 | * while waiting on the I/O. | |
2630 | */ | |
5590ff0d | 2631 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 2632 | { |
2ad94ae6 AV |
2633 | int error; |
2634 | char *name; | |
1da177e4 LT |
2635 | struct dentry *dentry; |
2636 | struct nameidata nd; | |
2637 | struct inode *inode = NULL; | |
2638 | ||
2ad94ae6 | 2639 | error = user_path_parent(dfd, pathname, &nd, &name); |
1da177e4 | 2640 | if (error) |
2ad94ae6 AV |
2641 | return error; |
2642 | ||
1da177e4 LT |
2643 | error = -EISDIR; |
2644 | if (nd.last_type != LAST_NORM) | |
2645 | goto exit1; | |
0612d9fb OH |
2646 | |
2647 | nd.flags &= ~LOOKUP_PARENT; | |
2648 | ||
4ac91378 | 2649 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 2650 | dentry = lookup_hash(&nd); |
1da177e4 LT |
2651 | error = PTR_ERR(dentry); |
2652 | if (!IS_ERR(dentry)) { | |
2653 | /* Why not before? Because we want correct error value */ | |
50338b88 TE |
2654 | if (nd.last.name[nd.last.len]) |
2655 | goto slashes; | |
1da177e4 | 2656 | inode = dentry->d_inode; |
50338b88 | 2657 | if (!inode) |
e6bc45d6 TT |
2658 | goto slashes; |
2659 | ihold(inode); | |
0622753b DH |
2660 | error = mnt_want_write(nd.path.mnt); |
2661 | if (error) | |
2662 | goto exit2; | |
be6d3e56 KT |
2663 | error = security_path_unlink(&nd.path, dentry); |
2664 | if (error) | |
2665 | goto exit3; | |
4ac91378 | 2666 | error = vfs_unlink(nd.path.dentry->d_inode, dentry); |
be6d3e56 | 2667 | exit3: |
0622753b | 2668 | mnt_drop_write(nd.path.mnt); |
1da177e4 LT |
2669 | exit2: |
2670 | dput(dentry); | |
2671 | } | |
4ac91378 | 2672 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 LT |
2673 | if (inode) |
2674 | iput(inode); /* truncate the inode here */ | |
2675 | exit1: | |
1d957f9b | 2676 | path_put(&nd.path); |
1da177e4 LT |
2677 | putname(name); |
2678 | return error; | |
2679 | ||
2680 | slashes: | |
2681 | error = !dentry->d_inode ? -ENOENT : | |
2682 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; | |
2683 | goto exit2; | |
2684 | } | |
2685 | ||
2e4d0924 | 2686 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
2687 | { |
2688 | if ((flag & ~AT_REMOVEDIR) != 0) | |
2689 | return -EINVAL; | |
2690 | ||
2691 | if (flag & AT_REMOVEDIR) | |
2692 | return do_rmdir(dfd, pathname); | |
2693 | ||
2694 | return do_unlinkat(dfd, pathname); | |
2695 | } | |
2696 | ||
3480b257 | 2697 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
2698 | { |
2699 | return do_unlinkat(AT_FDCWD, pathname); | |
2700 | } | |
2701 | ||
db2e747b | 2702 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 2703 | { |
a95164d9 | 2704 | int error = may_create(dir, dentry); |
1da177e4 LT |
2705 | |
2706 | if (error) | |
2707 | return error; | |
2708 | ||
acfa4380 | 2709 | if (!dir->i_op->symlink) |
1da177e4 LT |
2710 | return -EPERM; |
2711 | ||
2712 | error = security_inode_symlink(dir, dentry, oldname); | |
2713 | if (error) | |
2714 | return error; | |
2715 | ||
1da177e4 | 2716 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 2717 | if (!error) |
f38aa942 | 2718 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2719 | return error; |
2720 | } | |
2721 | ||
2e4d0924 HC |
2722 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
2723 | int, newdfd, const char __user *, newname) | |
1da177e4 | 2724 | { |
2ad94ae6 AV |
2725 | int error; |
2726 | char *from; | |
6902d925 | 2727 | struct dentry *dentry; |
dae6ad8f | 2728 | struct path path; |
1da177e4 LT |
2729 | |
2730 | from = getname(oldname); | |
2ad94ae6 | 2731 | if (IS_ERR(from)) |
1da177e4 | 2732 | return PTR_ERR(from); |
1da177e4 | 2733 | |
dae6ad8f | 2734 | dentry = user_path_create(newdfd, newname, &path, 0); |
6902d925 DH |
2735 | error = PTR_ERR(dentry); |
2736 | if (IS_ERR(dentry)) | |
dae6ad8f | 2737 | goto out_putname; |
6902d925 | 2738 | |
dae6ad8f | 2739 | error = mnt_want_write(path.mnt); |
75c3f29d DH |
2740 | if (error) |
2741 | goto out_dput; | |
dae6ad8f | 2742 | error = security_path_symlink(&path, dentry, from); |
be6d3e56 KT |
2743 | if (error) |
2744 | goto out_drop_write; | |
dae6ad8f | 2745 | error = vfs_symlink(path.dentry->d_inode, dentry, from); |
be6d3e56 | 2746 | out_drop_write: |
dae6ad8f | 2747 | mnt_drop_write(path.mnt); |
75c3f29d | 2748 | out_dput: |
6902d925 | 2749 | dput(dentry); |
dae6ad8f AV |
2750 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
2751 | path_put(&path); | |
6902d925 | 2752 | out_putname: |
1da177e4 LT |
2753 | putname(from); |
2754 | return error; | |
2755 | } | |
2756 | ||
3480b257 | 2757 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
2758 | { |
2759 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
2760 | } | |
2761 | ||
1da177e4 LT |
2762 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
2763 | { | |
2764 | struct inode *inode = old_dentry->d_inode; | |
2765 | int error; | |
2766 | ||
2767 | if (!inode) | |
2768 | return -ENOENT; | |
2769 | ||
a95164d9 | 2770 | error = may_create(dir, new_dentry); |
1da177e4 LT |
2771 | if (error) |
2772 | return error; | |
2773 | ||
2774 | if (dir->i_sb != inode->i_sb) | |
2775 | return -EXDEV; | |
2776 | ||
2777 | /* | |
2778 | * A link to an append-only or immutable file cannot be created. | |
2779 | */ | |
2780 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
2781 | return -EPERM; | |
acfa4380 | 2782 | if (!dir->i_op->link) |
1da177e4 | 2783 | return -EPERM; |
7e79eedb | 2784 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
2785 | return -EPERM; |
2786 | ||
2787 | error = security_inode_link(old_dentry, dir, new_dentry); | |
2788 | if (error) | |
2789 | return error; | |
2790 | ||
7e79eedb | 2791 | mutex_lock(&inode->i_mutex); |
aae8a97d AK |
2792 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
2793 | if (inode->i_nlink == 0) | |
2794 | error = -ENOENT; | |
2795 | else | |
2796 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
7e79eedb | 2797 | mutex_unlock(&inode->i_mutex); |
e31e14ec | 2798 | if (!error) |
7e79eedb | 2799 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
2800 | return error; |
2801 | } | |
2802 | ||
2803 | /* | |
2804 | * Hardlinks are often used in delicate situations. We avoid | |
2805 | * security-related surprises by not following symlinks on the | |
2806 | * newname. --KAB | |
2807 | * | |
2808 | * We don't follow them on the oldname either to be compatible | |
2809 | * with linux 2.0, and to avoid hard-linking to directories | |
2810 | * and other special files. --ADM | |
2811 | */ | |
2e4d0924 HC |
2812 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
2813 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
2814 | { |
2815 | struct dentry *new_dentry; | |
dae6ad8f | 2816 | struct path old_path, new_path; |
11a7b371 | 2817 | int how = 0; |
1da177e4 | 2818 | int error; |
1da177e4 | 2819 | |
11a7b371 | 2820 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
c04030e1 | 2821 | return -EINVAL; |
11a7b371 AK |
2822 | /* |
2823 | * To use null names we require CAP_DAC_READ_SEARCH | |
2824 | * This ensures that not everyone will be able to create | |
2825 | * handlink using the passed filedescriptor. | |
2826 | */ | |
2827 | if (flags & AT_EMPTY_PATH) { | |
2828 | if (!capable(CAP_DAC_READ_SEARCH)) | |
2829 | return -ENOENT; | |
2830 | how = LOOKUP_EMPTY; | |
2831 | } | |
2832 | ||
2833 | if (flags & AT_SYMLINK_FOLLOW) | |
2834 | how |= LOOKUP_FOLLOW; | |
c04030e1 | 2835 | |
11a7b371 | 2836 | error = user_path_at(olddfd, oldname, how, &old_path); |
1da177e4 | 2837 | if (error) |
2ad94ae6 AV |
2838 | return error; |
2839 | ||
dae6ad8f | 2840 | new_dentry = user_path_create(newdfd, newname, &new_path, 0); |
1da177e4 | 2841 | error = PTR_ERR(new_dentry); |
6902d925 | 2842 | if (IS_ERR(new_dentry)) |
dae6ad8f AV |
2843 | goto out; |
2844 | ||
2845 | error = -EXDEV; | |
2846 | if (old_path.mnt != new_path.mnt) | |
2847 | goto out_dput; | |
2848 | error = mnt_want_write(new_path.mnt); | |
75c3f29d DH |
2849 | if (error) |
2850 | goto out_dput; | |
dae6ad8f | 2851 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
be6d3e56 KT |
2852 | if (error) |
2853 | goto out_drop_write; | |
dae6ad8f | 2854 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); |
be6d3e56 | 2855 | out_drop_write: |
dae6ad8f | 2856 | mnt_drop_write(new_path.mnt); |
75c3f29d | 2857 | out_dput: |
6902d925 | 2858 | dput(new_dentry); |
dae6ad8f AV |
2859 | mutex_unlock(&new_path.dentry->d_inode->i_mutex); |
2860 | path_put(&new_path); | |
1da177e4 | 2861 | out: |
2d8f3038 | 2862 | path_put(&old_path); |
1da177e4 LT |
2863 | |
2864 | return error; | |
2865 | } | |
2866 | ||
3480b257 | 2867 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 2868 | { |
c04030e1 | 2869 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
2870 | } |
2871 | ||
1da177e4 LT |
2872 | /* |
2873 | * The worst of all namespace operations - renaming directory. "Perverted" | |
2874 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
2875 | * Problems: | |
2876 | * a) we can get into loop creation. Check is done in is_subdir(). | |
2877 | * b) race potential - two innocent renames can create a loop together. | |
2878 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 2879 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 LT |
2880 | * story. |
2881 | * c) we have to lock _three_ objects - parents and victim (if it exists). | |
1b1dcc1b | 2882 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
2883 | * whether the target exists). Solution: try to be smart with locking |
2884 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 2885 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
2886 | * move will be locked. Thus we can rank directories by the tree |
2887 | * (ancestors first) and rank all non-directories after them. | |
2888 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 2889 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
2890 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
2891 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
2892 | * we'd better make sure that there's no link(2) for them. | |
e4eaac06 | 2893 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
1b1dcc1b | 2894 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 2895 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
c41b20e7 | 2896 | * ->i_mutex on parents, which works but leads to some truly excessive |
1da177e4 LT |
2897 | * locking]. |
2898 | */ | |
75c96f85 AB |
2899 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
2900 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 LT |
2901 | { |
2902 | int error = 0; | |
9055cba7 | 2903 | struct inode *target = new_dentry->d_inode; |
1da177e4 LT |
2904 | |
2905 | /* | |
2906 | * If we are going to change the parent - check write permissions, | |
2907 | * we'll need to flip '..'. | |
2908 | */ | |
2909 | if (new_dir != old_dir) { | |
f419a2e3 | 2910 | error = inode_permission(old_dentry->d_inode, MAY_WRITE); |
1da177e4 LT |
2911 | if (error) |
2912 | return error; | |
2913 | } | |
2914 | ||
2915 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2916 | if (error) | |
2917 | return error; | |
2918 | ||
d83c49f3 | 2919 | if (target) |
1b1dcc1b | 2920 | mutex_lock(&target->i_mutex); |
9055cba7 SW |
2921 | |
2922 | error = -EBUSY; | |
2923 | if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) | |
2924 | goto out; | |
2925 | ||
3cebde24 SW |
2926 | if (target) |
2927 | shrink_dcache_parent(new_dentry); | |
9055cba7 SW |
2928 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
2929 | if (error) | |
2930 | goto out; | |
2931 | ||
1da177e4 | 2932 | if (target) { |
9055cba7 SW |
2933 | target->i_flags |= S_DEAD; |
2934 | dont_mount(new_dentry); | |
1da177e4 | 2935 | } |
9055cba7 SW |
2936 | out: |
2937 | if (target) | |
2938 | mutex_unlock(&target->i_mutex); | |
e31e14ec | 2939 | if (!error) |
349457cc MF |
2940 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
2941 | d_move(old_dentry,new_dentry); | |
1da177e4 LT |
2942 | return error; |
2943 | } | |
2944 | ||
75c96f85 AB |
2945 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
2946 | struct inode *new_dir, struct dentry *new_dentry) | |
1da177e4 | 2947 | { |
51892bbb | 2948 | struct inode *target = new_dentry->d_inode; |
1da177e4 LT |
2949 | int error; |
2950 | ||
2951 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); | |
2952 | if (error) | |
2953 | return error; | |
2954 | ||
2955 | dget(new_dentry); | |
1da177e4 | 2956 | if (target) |
1b1dcc1b | 2957 | mutex_lock(&target->i_mutex); |
51892bbb SW |
2958 | |
2959 | error = -EBUSY; | |
1da177e4 | 2960 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
51892bbb SW |
2961 | goto out; |
2962 | ||
2963 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); | |
2964 | if (error) | |
2965 | goto out; | |
2966 | ||
2967 | if (target) | |
2968 | dont_mount(new_dentry); | |
2969 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) | |
2970 | d_move(old_dentry, new_dentry); | |
2971 | out: | |
1da177e4 | 2972 | if (target) |
1b1dcc1b | 2973 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
2974 | dput(new_dentry); |
2975 | return error; | |
2976 | } | |
2977 | ||
2978 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, | |
2979 | struct inode *new_dir, struct dentry *new_dentry) | |
2980 | { | |
2981 | int error; | |
2982 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); | |
59b0df21 | 2983 | const unsigned char *old_name; |
1da177e4 LT |
2984 | |
2985 | if (old_dentry->d_inode == new_dentry->d_inode) | |
2986 | return 0; | |
2987 | ||
2988 | error = may_delete(old_dir, old_dentry, is_dir); | |
2989 | if (error) | |
2990 | return error; | |
2991 | ||
2992 | if (!new_dentry->d_inode) | |
a95164d9 | 2993 | error = may_create(new_dir, new_dentry); |
1da177e4 LT |
2994 | else |
2995 | error = may_delete(new_dir, new_dentry, is_dir); | |
2996 | if (error) | |
2997 | return error; | |
2998 | ||
acfa4380 | 2999 | if (!old_dir->i_op->rename) |
1da177e4 LT |
3000 | return -EPERM; |
3001 | ||
0eeca283 RL |
3002 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
3003 | ||
1da177e4 LT |
3004 | if (is_dir) |
3005 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); | |
3006 | else | |
3007 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); | |
123df294 AV |
3008 | if (!error) |
3009 | fsnotify_move(old_dir, new_dir, old_name, is_dir, | |
5a190ae6 | 3010 | new_dentry->d_inode, old_dentry); |
0eeca283 RL |
3011 | fsnotify_oldname_free(old_name); |
3012 | ||
1da177e4 LT |
3013 | return error; |
3014 | } | |
3015 | ||
2e4d0924 HC |
3016 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
3017 | int, newdfd, const char __user *, newname) | |
1da177e4 | 3018 | { |
2ad94ae6 AV |
3019 | struct dentry *old_dir, *new_dir; |
3020 | struct dentry *old_dentry, *new_dentry; | |
3021 | struct dentry *trap; | |
1da177e4 | 3022 | struct nameidata oldnd, newnd; |
2ad94ae6 AV |
3023 | char *from; |
3024 | char *to; | |
3025 | int error; | |
1da177e4 | 3026 | |
2ad94ae6 | 3027 | error = user_path_parent(olddfd, oldname, &oldnd, &from); |
1da177e4 LT |
3028 | if (error) |
3029 | goto exit; | |
3030 | ||
2ad94ae6 | 3031 | error = user_path_parent(newdfd, newname, &newnd, &to); |
1da177e4 LT |
3032 | if (error) |
3033 | goto exit1; | |
3034 | ||
3035 | error = -EXDEV; | |
4ac91378 | 3036 | if (oldnd.path.mnt != newnd.path.mnt) |
1da177e4 LT |
3037 | goto exit2; |
3038 | ||
4ac91378 | 3039 | old_dir = oldnd.path.dentry; |
1da177e4 LT |
3040 | error = -EBUSY; |
3041 | if (oldnd.last_type != LAST_NORM) | |
3042 | goto exit2; | |
3043 | ||
4ac91378 | 3044 | new_dir = newnd.path.dentry; |
1da177e4 LT |
3045 | if (newnd.last_type != LAST_NORM) |
3046 | goto exit2; | |
3047 | ||
0612d9fb OH |
3048 | oldnd.flags &= ~LOOKUP_PARENT; |
3049 | newnd.flags &= ~LOOKUP_PARENT; | |
4e9ed2f8 | 3050 | newnd.flags |= LOOKUP_RENAME_TARGET; |
0612d9fb | 3051 | |
1da177e4 LT |
3052 | trap = lock_rename(new_dir, old_dir); |
3053 | ||
49705b77 | 3054 | old_dentry = lookup_hash(&oldnd); |
1da177e4 LT |
3055 | error = PTR_ERR(old_dentry); |
3056 | if (IS_ERR(old_dentry)) | |
3057 | goto exit3; | |
3058 | /* source must exist */ | |
3059 | error = -ENOENT; | |
3060 | if (!old_dentry->d_inode) | |
3061 | goto exit4; | |
3062 | /* unless the source is a directory trailing slashes give -ENOTDIR */ | |
3063 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { | |
3064 | error = -ENOTDIR; | |
3065 | if (oldnd.last.name[oldnd.last.len]) | |
3066 | goto exit4; | |
3067 | if (newnd.last.name[newnd.last.len]) | |
3068 | goto exit4; | |
3069 | } | |
3070 | /* source should not be ancestor of target */ | |
3071 | error = -EINVAL; | |
3072 | if (old_dentry == trap) | |
3073 | goto exit4; | |
49705b77 | 3074 | new_dentry = lookup_hash(&newnd); |
1da177e4 LT |
3075 | error = PTR_ERR(new_dentry); |
3076 | if (IS_ERR(new_dentry)) | |
3077 | goto exit4; | |
3078 | /* target should not be an ancestor of source */ | |
3079 | error = -ENOTEMPTY; | |
3080 | if (new_dentry == trap) | |
3081 | goto exit5; | |
3082 | ||
9079b1eb DH |
3083 | error = mnt_want_write(oldnd.path.mnt); |
3084 | if (error) | |
3085 | goto exit5; | |
be6d3e56 KT |
3086 | error = security_path_rename(&oldnd.path, old_dentry, |
3087 | &newnd.path, new_dentry); | |
3088 | if (error) | |
3089 | goto exit6; | |
1da177e4 LT |
3090 | error = vfs_rename(old_dir->d_inode, old_dentry, |
3091 | new_dir->d_inode, new_dentry); | |
be6d3e56 | 3092 | exit6: |
9079b1eb | 3093 | mnt_drop_write(oldnd.path.mnt); |
1da177e4 LT |
3094 | exit5: |
3095 | dput(new_dentry); | |
3096 | exit4: | |
3097 | dput(old_dentry); | |
3098 | exit3: | |
3099 | unlock_rename(new_dir, old_dir); | |
3100 | exit2: | |
1d957f9b | 3101 | path_put(&newnd.path); |
2ad94ae6 | 3102 | putname(to); |
1da177e4 | 3103 | exit1: |
1d957f9b | 3104 | path_put(&oldnd.path); |
1da177e4 | 3105 | putname(from); |
2ad94ae6 | 3106 | exit: |
1da177e4 LT |
3107 | return error; |
3108 | } | |
3109 | ||
a26eab24 | 3110 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
3111 | { |
3112 | return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); | |
3113 | } | |
3114 | ||
1da177e4 LT |
3115 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
3116 | { | |
3117 | int len; | |
3118 | ||
3119 | len = PTR_ERR(link); | |
3120 | if (IS_ERR(link)) | |
3121 | goto out; | |
3122 | ||
3123 | len = strlen(link); | |
3124 | if (len > (unsigned) buflen) | |
3125 | len = buflen; | |
3126 | if (copy_to_user(buffer, link, len)) | |
3127 | len = -EFAULT; | |
3128 | out: | |
3129 | return len; | |
3130 | } | |
3131 | ||
3132 | /* | |
3133 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
3134 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
3135 | * using) it for any given inode is up to filesystem. | |
3136 | */ | |
3137 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
3138 | { | |
3139 | struct nameidata nd; | |
cc314eef | 3140 | void *cookie; |
694a1764 | 3141 | int res; |
cc314eef | 3142 | |
1da177e4 | 3143 | nd.depth = 0; |
cc314eef | 3144 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
694a1764 MS |
3145 | if (IS_ERR(cookie)) |
3146 | return PTR_ERR(cookie); | |
3147 | ||
3148 | res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); | |
3149 | if (dentry->d_inode->i_op->put_link) | |
3150 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); | |
3151 | return res; | |
1da177e4 LT |
3152 | } |
3153 | ||
3154 | int vfs_follow_link(struct nameidata *nd, const char *link) | |
3155 | { | |
3156 | return __vfs_follow_link(nd, link); | |
3157 | } | |
3158 | ||
3159 | /* get the link contents into pagecache */ | |
3160 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
3161 | { | |
ebd09abb DG |
3162 | char *kaddr; |
3163 | struct page *page; | |
1da177e4 | 3164 | struct address_space *mapping = dentry->d_inode->i_mapping; |
090d2b18 | 3165 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 3166 | if (IS_ERR(page)) |
6fe6900e | 3167 | return (char*)page; |
1da177e4 | 3168 | *ppage = page; |
ebd09abb DG |
3169 | kaddr = kmap(page); |
3170 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); | |
3171 | return kaddr; | |
1da177e4 LT |
3172 | } |
3173 | ||
3174 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
3175 | { | |
3176 | struct page *page = NULL; | |
3177 | char *s = page_getlink(dentry, &page); | |
3178 | int res = vfs_readlink(dentry,buffer,buflen,s); | |
3179 | if (page) { | |
3180 | kunmap(page); | |
3181 | page_cache_release(page); | |
3182 | } | |
3183 | return res; | |
3184 | } | |
3185 | ||
cc314eef | 3186 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 3187 | { |
cc314eef | 3188 | struct page *page = NULL; |
1da177e4 | 3189 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 3190 | return page; |
1da177e4 LT |
3191 | } |
3192 | ||
cc314eef | 3193 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 3194 | { |
cc314eef LT |
3195 | struct page *page = cookie; |
3196 | ||
3197 | if (page) { | |
1da177e4 LT |
3198 | kunmap(page); |
3199 | page_cache_release(page); | |
1da177e4 LT |
3200 | } |
3201 | } | |
3202 | ||
54566b2c NP |
3203 | /* |
3204 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
3205 | */ | |
3206 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
3207 | { |
3208 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 3209 | struct page *page; |
afddba49 | 3210 | void *fsdata; |
beb497ab | 3211 | int err; |
1da177e4 | 3212 | char *kaddr; |
54566b2c NP |
3213 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
3214 | if (nofs) | |
3215 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 3216 | |
7e53cac4 | 3217 | retry: |
afddba49 | 3218 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 3219 | flags, &page, &fsdata); |
1da177e4 | 3220 | if (err) |
afddba49 NP |
3221 | goto fail; |
3222 | ||
1da177e4 LT |
3223 | kaddr = kmap_atomic(page, KM_USER0); |
3224 | memcpy(kaddr, symname, len-1); | |
3225 | kunmap_atomic(kaddr, KM_USER0); | |
afddba49 NP |
3226 | |
3227 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
3228 | page, fsdata); | |
1da177e4 LT |
3229 | if (err < 0) |
3230 | goto fail; | |
afddba49 NP |
3231 | if (err < len-1) |
3232 | goto retry; | |
3233 | ||
1da177e4 LT |
3234 | mark_inode_dirty(inode); |
3235 | return 0; | |
1da177e4 LT |
3236 | fail: |
3237 | return err; | |
3238 | } | |
3239 | ||
0adb25d2 KK |
3240 | int page_symlink(struct inode *inode, const char *symname, int len) |
3241 | { | |
3242 | return __page_symlink(inode, symname, len, | |
54566b2c | 3243 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
0adb25d2 KK |
3244 | } |
3245 | ||
92e1d5be | 3246 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
3247 | .readlink = generic_readlink, |
3248 | .follow_link = page_follow_link_light, | |
3249 | .put_link = page_put_link, | |
3250 | }; | |
3251 | ||
2d8f3038 | 3252 | EXPORT_SYMBOL(user_path_at); |
cc53ce53 | 3253 | EXPORT_SYMBOL(follow_down_one); |
1da177e4 LT |
3254 | EXPORT_SYMBOL(follow_down); |
3255 | EXPORT_SYMBOL(follow_up); | |
3256 | EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ | |
3257 | EXPORT_SYMBOL(getname); | |
3258 | EXPORT_SYMBOL(lock_rename); | |
1da177e4 LT |
3259 | EXPORT_SYMBOL(lookup_one_len); |
3260 | EXPORT_SYMBOL(page_follow_link_light); | |
3261 | EXPORT_SYMBOL(page_put_link); | |
3262 | EXPORT_SYMBOL(page_readlink); | |
0adb25d2 | 3263 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 LT |
3264 | EXPORT_SYMBOL(page_symlink); |
3265 | EXPORT_SYMBOL(page_symlink_inode_operations); | |
c9c6cac0 | 3266 | EXPORT_SYMBOL(kern_path_parent); |
d1811465 | 3267 | EXPORT_SYMBOL(kern_path); |
16f18200 | 3268 | EXPORT_SYMBOL(vfs_path_lookup); |
f419a2e3 | 3269 | EXPORT_SYMBOL(inode_permission); |
1da177e4 LT |
3270 | EXPORT_SYMBOL(unlock_rename); |
3271 | EXPORT_SYMBOL(vfs_create); | |
3272 | EXPORT_SYMBOL(vfs_follow_link); | |
3273 | EXPORT_SYMBOL(vfs_link); | |
3274 | EXPORT_SYMBOL(vfs_mkdir); | |
3275 | EXPORT_SYMBOL(vfs_mknod); | |
3276 | EXPORT_SYMBOL(generic_permission); | |
3277 | EXPORT_SYMBOL(vfs_readlink); | |
3278 | EXPORT_SYMBOL(vfs_rename); | |
3279 | EXPORT_SYMBOL(vfs_rmdir); | |
3280 | EXPORT_SYMBOL(vfs_symlink); | |
3281 | EXPORT_SYMBOL(vfs_unlink); | |
3282 | EXPORT_SYMBOL(dentry_unhash); | |
3283 | EXPORT_SYMBOL(generic_readlink); |