Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/fs/namei.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * Some corrections by tytso. | |
9 | */ | |
10 | ||
11 | /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname | |
12 | * lookup logic. | |
13 | */ | |
14 | /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. | |
15 | */ | |
16 | ||
17 | #include <linux/init.h> | |
630d9c47 | 18 | #include <linux/export.h> |
44696908 | 19 | #include <linux/kernel.h> |
1da177e4 LT |
20 | #include <linux/slab.h> |
21 | #include <linux/fs.h> | |
22 | #include <linux/namei.h> | |
1da177e4 | 23 | #include <linux/pagemap.h> |
0eeca283 | 24 | #include <linux/fsnotify.h> |
1da177e4 LT |
25 | #include <linux/personality.h> |
26 | #include <linux/security.h> | |
6146f0d5 | 27 | #include <linux/ima.h> |
1da177e4 LT |
28 | #include <linux/syscalls.h> |
29 | #include <linux/mount.h> | |
30 | #include <linux/audit.h> | |
16f7e0fe | 31 | #include <linux/capability.h> |
834f2a4a | 32 | #include <linux/file.h> |
5590ff0d | 33 | #include <linux/fcntl.h> |
08ce5f16 | 34 | #include <linux/device_cgroup.h> |
5ad4e53b | 35 | #include <linux/fs_struct.h> |
e77819e5 | 36 | #include <linux/posix_acl.h> |
1da177e4 LT |
37 | #include <asm/uaccess.h> |
38 | ||
e81e3f4d | 39 | #include "internal.h" |
c7105365 | 40 | #include "mount.h" |
e81e3f4d | 41 | |
1da177e4 LT |
42 | /* [Feb-1997 T. Schoebel-Theuer] |
43 | * Fundamental changes in the pathname lookup mechanisms (namei) | |
44 | * were necessary because of omirr. The reason is that omirr needs | |
45 | * to know the _real_ pathname, not the user-supplied one, in case | |
46 | * of symlinks (and also when transname replacements occur). | |
47 | * | |
48 | * The new code replaces the old recursive symlink resolution with | |
49 | * an iterative one (in case of non-nested symlink chains). It does | |
50 | * this with calls to <fs>_follow_link(). | |
51 | * As a side effect, dir_namei(), _namei() and follow_link() are now | |
52 | * replaced with a single function lookup_dentry() that can handle all | |
53 | * the special cases of the former code. | |
54 | * | |
55 | * With the new dcache, the pathname is stored at each inode, at least as | |
56 | * long as the refcount of the inode is positive. As a side effect, the | |
57 | * size of the dcache depends on the inode cache and thus is dynamic. | |
58 | * | |
59 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink | |
60 | * resolution to correspond with current state of the code. | |
61 | * | |
62 | * Note that the symlink resolution is not *completely* iterative. | |
63 | * There is still a significant amount of tail- and mid- recursion in | |
64 | * the algorithm. Also, note that <fs>_readlink() is not used in | |
65 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() | |
66 | * may return different results than <fs>_follow_link(). Many virtual | |
67 | * filesystems (including /proc) exhibit this behavior. | |
68 | */ | |
69 | ||
70 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: | |
71 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL | |
72 | * and the name already exists in form of a symlink, try to create the new | |
73 | * name indicated by the symlink. The old code always complained that the | |
74 | * name already exists, due to not following the symlink even if its target | |
75 | * is nonexistent. The new semantics affects also mknod() and link() when | |
25985edc | 76 | * the name is a symlink pointing to a non-existent name. |
1da177e4 LT |
77 | * |
78 | * I don't know which semantics is the right one, since I have no access | |
79 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" | |
80 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the | |
81 | * "old" one. Personally, I think the new semantics is much more logical. | |
82 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing | |
83 | * file does succeed in both HP-UX and SunOs, but not in Solaris | |
84 | * and in the old Linux semantics. | |
85 | */ | |
86 | ||
87 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink | |
88 | * semantics. See the comments in "open_namei" and "do_link" below. | |
89 | * | |
90 | * [10-Sep-98 Alan Modra] Another symlink change. | |
91 | */ | |
92 | ||
93 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: | |
94 | * inside the path - always follow. | |
95 | * in the last component in creation/removal/renaming - never follow. | |
96 | * if LOOKUP_FOLLOW passed - follow. | |
97 | * if the pathname has trailing slashes - follow. | |
98 | * otherwise - don't follow. | |
99 | * (applied in that order). | |
100 | * | |
101 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT | |
102 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. | |
103 | * During the 2.4 we need to fix the userland stuff depending on it - | |
104 | * hopefully we will be able to get rid of that wart in 2.5. So far only | |
105 | * XEmacs seems to be relying on it... | |
106 | */ | |
107 | /* | |
108 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) | |
a11f3a05 | 109 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
1da177e4 LT |
110 | * any extra contention... |
111 | */ | |
112 | ||
113 | /* In order to reduce some races, while at the same time doing additional | |
114 | * checking and hopefully speeding things up, we copy filenames to the | |
115 | * kernel data space before using them.. | |
116 | * | |
117 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). | |
118 | * PATH_MAX includes the nul terminator --RR. | |
119 | */ | |
91a27b2a | 120 | void final_putname(struct filename *name) |
1da177e4 | 121 | { |
7950e385 JL |
122 | if (name->separate) { |
123 | __putname(name->name); | |
124 | kfree(name); | |
125 | } else { | |
126 | __putname(name); | |
127 | } | |
91a27b2a JL |
128 | } |
129 | ||
7950e385 JL |
130 | #define EMBEDDED_NAME_MAX (PATH_MAX - sizeof(struct filename)) |
131 | ||
91a27b2a JL |
132 | static struct filename * |
133 | getname_flags(const char __user *filename, int flags, int *empty) | |
134 | { | |
135 | struct filename *result, *err; | |
3f9f0aa6 | 136 | int len; |
7950e385 JL |
137 | long max; |
138 | char *kname; | |
4043cde8 | 139 | |
7ac86265 JL |
140 | result = audit_reusename(filename); |
141 | if (result) | |
142 | return result; | |
143 | ||
7950e385 | 144 | result = __getname(); |
3f9f0aa6 | 145 | if (unlikely(!result)) |
4043cde8 EP |
146 | return ERR_PTR(-ENOMEM); |
147 | ||
7950e385 JL |
148 | /* |
149 | * First, try to embed the struct filename inside the names_cache | |
150 | * allocation | |
151 | */ | |
152 | kname = (char *)result + sizeof(*result); | |
91a27b2a | 153 | result->name = kname; |
7950e385 JL |
154 | result->separate = false; |
155 | max = EMBEDDED_NAME_MAX; | |
156 | ||
157 | recopy: | |
158 | len = strncpy_from_user(kname, filename, max); | |
91a27b2a JL |
159 | if (unlikely(len < 0)) { |
160 | err = ERR_PTR(len); | |
3f9f0aa6 | 161 | goto error; |
91a27b2a | 162 | } |
3f9f0aa6 | 163 | |
7950e385 JL |
164 | /* |
165 | * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a | |
166 | * separate struct filename so we can dedicate the entire | |
167 | * names_cache allocation for the pathname, and re-do the copy from | |
168 | * userland. | |
169 | */ | |
170 | if (len == EMBEDDED_NAME_MAX && max == EMBEDDED_NAME_MAX) { | |
171 | kname = (char *)result; | |
172 | ||
173 | result = kzalloc(sizeof(*result), GFP_KERNEL); | |
174 | if (!result) { | |
175 | err = ERR_PTR(-ENOMEM); | |
176 | result = (struct filename *)kname; | |
177 | goto error; | |
178 | } | |
179 | result->name = kname; | |
180 | result->separate = true; | |
181 | max = PATH_MAX; | |
182 | goto recopy; | |
183 | } | |
184 | ||
3f9f0aa6 LT |
185 | /* The empty path is special. */ |
186 | if (unlikely(!len)) { | |
187 | if (empty) | |
4043cde8 | 188 | *empty = 1; |
3f9f0aa6 LT |
189 | err = ERR_PTR(-ENOENT); |
190 | if (!(flags & LOOKUP_EMPTY)) | |
191 | goto error; | |
1da177e4 | 192 | } |
3f9f0aa6 LT |
193 | |
194 | err = ERR_PTR(-ENAMETOOLONG); | |
7950e385 JL |
195 | if (unlikely(len >= PATH_MAX)) |
196 | goto error; | |
197 | ||
198 | result->uptr = filename; | |
c4ad8f98 | 199 | result->aname = NULL; |
7950e385 JL |
200 | audit_getname(result); |
201 | return result; | |
3f9f0aa6 LT |
202 | |
203 | error: | |
7950e385 | 204 | final_putname(result); |
3f9f0aa6 | 205 | return err; |
1da177e4 LT |
206 | } |
207 | ||
91a27b2a JL |
208 | struct filename * |
209 | getname(const char __user * filename) | |
f52e0c11 | 210 | { |
f7493e5d | 211 | return getname_flags(filename, 0, NULL); |
f52e0c11 AV |
212 | } |
213 | ||
c4ad8f98 LT |
214 | /* |
215 | * The "getname_kernel()" interface doesn't do pathnames longer | |
216 | * than EMBEDDED_NAME_MAX. Deal with it - you're a kernel user. | |
217 | */ | |
218 | struct filename * | |
219 | getname_kernel(const char * filename) | |
220 | { | |
221 | struct filename *result; | |
222 | char *kname; | |
223 | int len; | |
224 | ||
225 | len = strlen(filename); | |
226 | if (len >= EMBEDDED_NAME_MAX) | |
227 | return ERR_PTR(-ENAMETOOLONG); | |
228 | ||
229 | result = __getname(); | |
230 | if (unlikely(!result)) | |
231 | return ERR_PTR(-ENOMEM); | |
232 | ||
233 | kname = (char *)result + sizeof(*result); | |
234 | result->name = kname; | |
235 | result->uptr = NULL; | |
236 | result->aname = NULL; | |
237 | result->separate = false; | |
238 | ||
239 | strlcpy(kname, filename, EMBEDDED_NAME_MAX); | |
240 | return result; | |
241 | } | |
242 | ||
1da177e4 | 243 | #ifdef CONFIG_AUDITSYSCALL |
91a27b2a | 244 | void putname(struct filename *name) |
1da177e4 | 245 | { |
5ac3a9c2 | 246 | if (unlikely(!audit_dummy_context())) |
91a27b2a JL |
247 | return audit_putname(name); |
248 | final_putname(name); | |
1da177e4 | 249 | } |
1da177e4 LT |
250 | #endif |
251 | ||
e77819e5 LT |
252 | static int check_acl(struct inode *inode, int mask) |
253 | { | |
84635d68 | 254 | #ifdef CONFIG_FS_POSIX_ACL |
e77819e5 LT |
255 | struct posix_acl *acl; |
256 | ||
e77819e5 | 257 | if (mask & MAY_NOT_BLOCK) { |
3567866b AV |
258 | acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); |
259 | if (!acl) | |
e77819e5 | 260 | return -EAGAIN; |
3567866b AV |
261 | /* no ->get_acl() calls in RCU mode... */ |
262 | if (acl == ACL_NOT_CACHED) | |
263 | return -ECHILD; | |
206b1d09 | 264 | return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); |
e77819e5 LT |
265 | } |
266 | ||
2982baa2 CH |
267 | acl = get_acl(inode, ACL_TYPE_ACCESS); |
268 | if (IS_ERR(acl)) | |
269 | return PTR_ERR(acl); | |
e77819e5 LT |
270 | if (acl) { |
271 | int error = posix_acl_permission(inode, acl, mask); | |
272 | posix_acl_release(acl); | |
273 | return error; | |
274 | } | |
84635d68 | 275 | #endif |
e77819e5 LT |
276 | |
277 | return -EAGAIN; | |
278 | } | |
279 | ||
5909ccaa | 280 | /* |
948409c7 | 281 | * This does the basic permission checking |
1da177e4 | 282 | */ |
7e40145e | 283 | static int acl_permission_check(struct inode *inode, int mask) |
1da177e4 | 284 | { |
26cf46be | 285 | unsigned int mode = inode->i_mode; |
1da177e4 | 286 | |
8e96e3b7 | 287 | if (likely(uid_eq(current_fsuid(), inode->i_uid))) |
1da177e4 LT |
288 | mode >>= 6; |
289 | else { | |
e77819e5 | 290 | if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { |
7e40145e | 291 | int error = check_acl(inode, mask); |
b74c79e9 NP |
292 | if (error != -EAGAIN) |
293 | return error; | |
1da177e4 LT |
294 | } |
295 | ||
296 | if (in_group_p(inode->i_gid)) | |
297 | mode >>= 3; | |
298 | } | |
299 | ||
300 | /* | |
301 | * If the DACs are ok we don't need any capability check. | |
302 | */ | |
9c2c7039 | 303 | if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) |
1da177e4 | 304 | return 0; |
5909ccaa LT |
305 | return -EACCES; |
306 | } | |
307 | ||
308 | /** | |
b74c79e9 | 309 | * generic_permission - check for access rights on a Posix-like filesystem |
5909ccaa | 310 | * @inode: inode to check access rights for |
8fd90c8d | 311 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) |
5909ccaa LT |
312 | * |
313 | * Used to check for read/write/execute permissions on a file. | |
314 | * We use "fsuid" for this, letting us set arbitrary permissions | |
315 | * for filesystem access without changing the "normal" uids which | |
b74c79e9 NP |
316 | * are used for other things. |
317 | * | |
318 | * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk | |
319 | * request cannot be satisfied (eg. requires blocking or too much complexity). | |
320 | * It would then be called again in ref-walk mode. | |
5909ccaa | 321 | */ |
2830ba7f | 322 | int generic_permission(struct inode *inode, int mask) |
5909ccaa LT |
323 | { |
324 | int ret; | |
325 | ||
326 | /* | |
948409c7 | 327 | * Do the basic permission checks. |
5909ccaa | 328 | */ |
7e40145e | 329 | ret = acl_permission_check(inode, mask); |
5909ccaa LT |
330 | if (ret != -EACCES) |
331 | return ret; | |
1da177e4 | 332 | |
d594e7ec AV |
333 | if (S_ISDIR(inode->i_mode)) { |
334 | /* DACs are overridable for directories */ | |
23adbe12 | 335 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) |
d594e7ec AV |
336 | return 0; |
337 | if (!(mask & MAY_WRITE)) | |
23adbe12 AL |
338 | if (capable_wrt_inode_uidgid(inode, |
339 | CAP_DAC_READ_SEARCH)) | |
d594e7ec AV |
340 | return 0; |
341 | return -EACCES; | |
342 | } | |
1da177e4 LT |
343 | /* |
344 | * Read/write DACs are always overridable. | |
d594e7ec AV |
345 | * Executable DACs are overridable when there is |
346 | * at least one exec bit set. | |
1da177e4 | 347 | */ |
d594e7ec | 348 | if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) |
23adbe12 | 349 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) |
1da177e4 LT |
350 | return 0; |
351 | ||
352 | /* | |
353 | * Searching includes executable on directories, else just read. | |
354 | */ | |
7ea66001 | 355 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
d594e7ec | 356 | if (mask == MAY_READ) |
23adbe12 | 357 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) |
1da177e4 LT |
358 | return 0; |
359 | ||
360 | return -EACCES; | |
361 | } | |
4d359507 | 362 | EXPORT_SYMBOL(generic_permission); |
1da177e4 | 363 | |
3ddcd056 LT |
364 | /* |
365 | * We _really_ want to just do "generic_permission()" without | |
366 | * even looking at the inode->i_op values. So we keep a cache | |
367 | * flag in inode->i_opflags, that says "this has not special | |
368 | * permission function, use the fast case". | |
369 | */ | |
370 | static inline int do_inode_permission(struct inode *inode, int mask) | |
371 | { | |
372 | if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { | |
373 | if (likely(inode->i_op->permission)) | |
374 | return inode->i_op->permission(inode, mask); | |
375 | ||
376 | /* This gets set once for the inode lifetime */ | |
377 | spin_lock(&inode->i_lock); | |
378 | inode->i_opflags |= IOP_FASTPERM; | |
379 | spin_unlock(&inode->i_lock); | |
380 | } | |
381 | return generic_permission(inode, mask); | |
382 | } | |
383 | ||
cb23beb5 | 384 | /** |
0bdaea90 DH |
385 | * __inode_permission - Check for access rights to a given inode |
386 | * @inode: Inode to check permission on | |
387 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
cb23beb5 | 388 | * |
0bdaea90 | 389 | * Check for read/write/execute permissions on an inode. |
948409c7 AG |
390 | * |
391 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
0bdaea90 DH |
392 | * |
393 | * This does not check for a read-only file system. You probably want | |
394 | * inode_permission(). | |
cb23beb5 | 395 | */ |
0bdaea90 | 396 | int __inode_permission(struct inode *inode, int mask) |
1da177e4 | 397 | { |
e6305c43 | 398 | int retval; |
1da177e4 | 399 | |
3ddcd056 | 400 | if (unlikely(mask & MAY_WRITE)) { |
1da177e4 LT |
401 | /* |
402 | * Nobody gets write access to an immutable file. | |
403 | */ | |
404 | if (IS_IMMUTABLE(inode)) | |
405 | return -EACCES; | |
406 | } | |
407 | ||
3ddcd056 | 408 | retval = do_inode_permission(inode, mask); |
1da177e4 LT |
409 | if (retval) |
410 | return retval; | |
411 | ||
08ce5f16 SH |
412 | retval = devcgroup_inode_permission(inode, mask); |
413 | if (retval) | |
414 | return retval; | |
415 | ||
d09ca739 | 416 | return security_inode_permission(inode, mask); |
1da177e4 LT |
417 | } |
418 | ||
0bdaea90 DH |
419 | /** |
420 | * sb_permission - Check superblock-level permissions | |
421 | * @sb: Superblock of inode to check permission on | |
55852635 | 422 | * @inode: Inode to check permission on |
0bdaea90 DH |
423 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
424 | * | |
425 | * Separate out file-system wide checks from inode-specific permission checks. | |
426 | */ | |
427 | static int sb_permission(struct super_block *sb, struct inode *inode, int mask) | |
428 | { | |
429 | if (unlikely(mask & MAY_WRITE)) { | |
430 | umode_t mode = inode->i_mode; | |
431 | ||
432 | /* Nobody gets write access to a read-only fs. */ | |
433 | if ((sb->s_flags & MS_RDONLY) && | |
434 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
435 | return -EROFS; | |
436 | } | |
437 | return 0; | |
438 | } | |
439 | ||
440 | /** | |
441 | * inode_permission - Check for access rights to a given inode | |
442 | * @inode: Inode to check permission on | |
443 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
444 | * | |
445 | * Check for read/write/execute permissions on an inode. We use fs[ug]id for | |
446 | * this, letting us set arbitrary permissions for filesystem access without | |
447 | * changing the "normal" UIDs which are used for other things. | |
448 | * | |
449 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
450 | */ | |
451 | int inode_permission(struct inode *inode, int mask) | |
452 | { | |
453 | int retval; | |
454 | ||
455 | retval = sb_permission(inode->i_sb, inode, mask); | |
456 | if (retval) | |
457 | return retval; | |
458 | return __inode_permission(inode, mask); | |
459 | } | |
4d359507 | 460 | EXPORT_SYMBOL(inode_permission); |
0bdaea90 | 461 | |
5dd784d0 JB |
462 | /** |
463 | * path_get - get a reference to a path | |
464 | * @path: path to get the reference to | |
465 | * | |
466 | * Given a path increment the reference count to the dentry and the vfsmount. | |
467 | */ | |
dcf787f3 | 468 | void path_get(const struct path *path) |
5dd784d0 JB |
469 | { |
470 | mntget(path->mnt); | |
471 | dget(path->dentry); | |
472 | } | |
473 | EXPORT_SYMBOL(path_get); | |
474 | ||
1d957f9b JB |
475 | /** |
476 | * path_put - put a reference to a path | |
477 | * @path: path to put the reference to | |
478 | * | |
479 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
480 | */ | |
dcf787f3 | 481 | void path_put(const struct path *path) |
1da177e4 | 482 | { |
1d957f9b JB |
483 | dput(path->dentry); |
484 | mntput(path->mnt); | |
1da177e4 | 485 | } |
1d957f9b | 486 | EXPORT_SYMBOL(path_put); |
1da177e4 | 487 | |
19660af7 | 488 | /* |
31e6b01f | 489 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
19660af7 AV |
490 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
491 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab | |
492 | * normal reference counts on dentries and vfsmounts to transition to rcu-walk | |
493 | * mode. Refcounts are grabbed at the last known good point before rcu-walk | |
494 | * got stuck, so ref-walk may continue from there. If this is not successful | |
495 | * (eg. a seqcount has changed), then failure is returned and it's up to caller | |
496 | * to restart the path walk from the beginning in ref-walk mode. | |
31e6b01f | 497 | */ |
31e6b01f NP |
498 | |
499 | /** | |
19660af7 AV |
500 | * unlazy_walk - try to switch to ref-walk mode. |
501 | * @nd: nameidata pathwalk data | |
502 | * @dentry: child of nd->path.dentry or NULL | |
39191628 | 503 | * Returns: 0 on success, -ECHILD on failure |
31e6b01f | 504 | * |
19660af7 AV |
505 | * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry |
506 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on | |
507 | * @nd or NULL. Must be called from rcu-walk context. | |
31e6b01f | 508 | */ |
19660af7 | 509 | static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) |
31e6b01f NP |
510 | { |
511 | struct fs_struct *fs = current->fs; | |
512 | struct dentry *parent = nd->path.dentry; | |
513 | ||
514 | BUG_ON(!(nd->flags & LOOKUP_RCU)); | |
e5c832d5 LT |
515 | |
516 | /* | |
48a066e7 AV |
517 | * After legitimizing the bastards, terminate_walk() |
518 | * will do the right thing for non-RCU mode, and all our | |
519 | * subsequent exit cases should rcu_read_unlock() | |
520 | * before returning. Do vfsmount first; if dentry | |
521 | * can't be legitimized, just set nd->path.dentry to NULL | |
522 | * and rely on dput(NULL) being a no-op. | |
e5c832d5 | 523 | */ |
48a066e7 | 524 | if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) |
e5c832d5 | 525 | return -ECHILD; |
e5c832d5 | 526 | nd->flags &= ~LOOKUP_RCU; |
15570086 | 527 | |
48a066e7 AV |
528 | if (!lockref_get_not_dead(&parent->d_lockref)) { |
529 | nd->path.dentry = NULL; | |
d870b4a1 | 530 | goto out; |
48a066e7 AV |
531 | } |
532 | ||
15570086 LT |
533 | /* |
534 | * For a negative lookup, the lookup sequence point is the parents | |
535 | * sequence point, and it only needs to revalidate the parent dentry. | |
536 | * | |
537 | * For a positive lookup, we need to move both the parent and the | |
538 | * dentry from the RCU domain to be properly refcounted. And the | |
539 | * sequence number in the dentry validates *both* dentry counters, | |
540 | * since we checked the sequence number of the parent after we got | |
541 | * the child sequence number. So we know the parent must still | |
542 | * be valid if the child sequence number is still valid. | |
543 | */ | |
19660af7 | 544 | if (!dentry) { |
e5c832d5 LT |
545 | if (read_seqcount_retry(&parent->d_seq, nd->seq)) |
546 | goto out; | |
19660af7 AV |
547 | BUG_ON(nd->inode != parent->d_inode); |
548 | } else { | |
e5c832d5 LT |
549 | if (!lockref_get_not_dead(&dentry->d_lockref)) |
550 | goto out; | |
551 | if (read_seqcount_retry(&dentry->d_seq, nd->seq)) | |
552 | goto drop_dentry; | |
19660af7 | 553 | } |
e5c832d5 LT |
554 | |
555 | /* | |
556 | * Sequence counts matched. Now make sure that the root is | |
557 | * still valid and get it if required. | |
558 | */ | |
559 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { | |
560 | spin_lock(&fs->lock); | |
561 | if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) | |
562 | goto unlock_and_drop_dentry; | |
31e6b01f NP |
563 | path_get(&nd->root); |
564 | spin_unlock(&fs->lock); | |
565 | } | |
31e6b01f | 566 | |
8b61e74f | 567 | rcu_read_unlock(); |
31e6b01f | 568 | return 0; |
19660af7 | 569 | |
e5c832d5 LT |
570 | unlock_and_drop_dentry: |
571 | spin_unlock(&fs->lock); | |
572 | drop_dentry: | |
8b61e74f | 573 | rcu_read_unlock(); |
15570086 | 574 | dput(dentry); |
d0d27277 | 575 | goto drop_root_mnt; |
e5c832d5 | 576 | out: |
8b61e74f | 577 | rcu_read_unlock(); |
d0d27277 LT |
578 | drop_root_mnt: |
579 | if (!(nd->flags & LOOKUP_ROOT)) | |
580 | nd->root.mnt = NULL; | |
31e6b01f NP |
581 | return -ECHILD; |
582 | } | |
583 | ||
4ce16ef3 | 584 | static inline int d_revalidate(struct dentry *dentry, unsigned int flags) |
34286d66 | 585 | { |
4ce16ef3 | 586 | return dentry->d_op->d_revalidate(dentry, flags); |
34286d66 NP |
587 | } |
588 | ||
9f1fafee AV |
589 | /** |
590 | * complete_walk - successful completion of path walk | |
591 | * @nd: pointer nameidata | |
39159de2 | 592 | * |
9f1fafee AV |
593 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
594 | * Revalidate the final result, unless we'd already done that during | |
595 | * the path walk or the filesystem doesn't ask for it. Return 0 on | |
596 | * success, -error on failure. In case of failure caller does not | |
597 | * need to drop nd->path. | |
39159de2 | 598 | */ |
9f1fafee | 599 | static int complete_walk(struct nameidata *nd) |
39159de2 | 600 | { |
16c2cd71 | 601 | struct dentry *dentry = nd->path.dentry; |
39159de2 | 602 | int status; |
39159de2 | 603 | |
9f1fafee AV |
604 | if (nd->flags & LOOKUP_RCU) { |
605 | nd->flags &= ~LOOKUP_RCU; | |
606 | if (!(nd->flags & LOOKUP_ROOT)) | |
607 | nd->root.mnt = NULL; | |
15570086 | 608 | |
48a066e7 | 609 | if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { |
8b61e74f | 610 | rcu_read_unlock(); |
48a066e7 AV |
611 | return -ECHILD; |
612 | } | |
e5c832d5 | 613 | if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { |
8b61e74f | 614 | rcu_read_unlock(); |
48a066e7 | 615 | mntput(nd->path.mnt); |
e5c832d5 LT |
616 | return -ECHILD; |
617 | } | |
618 | if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { | |
8b61e74f | 619 | rcu_read_unlock(); |
e5c832d5 | 620 | dput(dentry); |
48a066e7 | 621 | mntput(nd->path.mnt); |
9f1fafee AV |
622 | return -ECHILD; |
623 | } | |
8b61e74f | 624 | rcu_read_unlock(); |
9f1fafee AV |
625 | } |
626 | ||
16c2cd71 AV |
627 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
628 | return 0; | |
629 | ||
ecf3d1f1 | 630 | if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) |
39159de2 JL |
631 | return 0; |
632 | ||
ecf3d1f1 | 633 | status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); |
39159de2 JL |
634 | if (status > 0) |
635 | return 0; | |
636 | ||
16c2cd71 | 637 | if (!status) |
39159de2 | 638 | status = -ESTALE; |
16c2cd71 | 639 | |
9f1fafee | 640 | path_put(&nd->path); |
39159de2 JL |
641 | return status; |
642 | } | |
643 | ||
2a737871 AV |
644 | static __always_inline void set_root(struct nameidata *nd) |
645 | { | |
f7ad3c6b MS |
646 | if (!nd->root.mnt) |
647 | get_fs_root(current->fs, &nd->root); | |
2a737871 AV |
648 | } |
649 | ||
6de88d72 AV |
650 | static int link_path_walk(const char *, struct nameidata *); |
651 | ||
31e6b01f NP |
652 | static __always_inline void set_root_rcu(struct nameidata *nd) |
653 | { | |
654 | if (!nd->root.mnt) { | |
655 | struct fs_struct *fs = current->fs; | |
c28cc364 NP |
656 | unsigned seq; |
657 | ||
658 | do { | |
659 | seq = read_seqcount_begin(&fs->seq); | |
660 | nd->root = fs->root; | |
c1530019 | 661 | nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); |
c28cc364 | 662 | } while (read_seqcount_retry(&fs->seq, seq)); |
31e6b01f NP |
663 | } |
664 | } | |
665 | ||
1d957f9b | 666 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
667 | { |
668 | dput(path->dentry); | |
4ac91378 | 669 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
670 | mntput(path->mnt); |
671 | } | |
672 | ||
7b9337aa NP |
673 | static inline void path_to_nameidata(const struct path *path, |
674 | struct nameidata *nd) | |
051d3812 | 675 | { |
31e6b01f NP |
676 | if (!(nd->flags & LOOKUP_RCU)) { |
677 | dput(nd->path.dentry); | |
678 | if (nd->path.mnt != path->mnt) | |
679 | mntput(nd->path.mnt); | |
9a229683 | 680 | } |
31e6b01f | 681 | nd->path.mnt = path->mnt; |
4ac91378 | 682 | nd->path.dentry = path->dentry; |
051d3812 IK |
683 | } |
684 | ||
b5fb63c1 CH |
685 | /* |
686 | * Helper to directly jump to a known parsed path from ->follow_link, | |
687 | * caller must have taken a reference to path beforehand. | |
688 | */ | |
689 | void nd_jump_link(struct nameidata *nd, struct path *path) | |
690 | { | |
691 | path_put(&nd->path); | |
692 | ||
693 | nd->path = *path; | |
694 | nd->inode = nd->path.dentry->d_inode; | |
695 | nd->flags |= LOOKUP_JUMPED; | |
b5fb63c1 CH |
696 | } |
697 | ||
574197e0 AV |
698 | static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) |
699 | { | |
700 | struct inode *inode = link->dentry->d_inode; | |
6d7b5aae | 701 | if (inode->i_op->put_link) |
574197e0 AV |
702 | inode->i_op->put_link(link->dentry, nd, cookie); |
703 | path_put(link); | |
704 | } | |
705 | ||
561ec64a LT |
706 | int sysctl_protected_symlinks __read_mostly = 0; |
707 | int sysctl_protected_hardlinks __read_mostly = 0; | |
800179c9 KC |
708 | |
709 | /** | |
710 | * may_follow_link - Check symlink following for unsafe situations | |
711 | * @link: The path of the symlink | |
55852635 | 712 | * @nd: nameidata pathwalk data |
800179c9 KC |
713 | * |
714 | * In the case of the sysctl_protected_symlinks sysctl being enabled, | |
715 | * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is | |
716 | * in a sticky world-writable directory. This is to protect privileged | |
717 | * processes from failing races against path names that may change out | |
718 | * from under them by way of other users creating malicious symlinks. | |
719 | * It will permit symlinks to be followed only when outside a sticky | |
720 | * world-writable directory, or when the uid of the symlink and follower | |
721 | * match, or when the directory owner matches the symlink's owner. | |
722 | * | |
723 | * Returns 0 if following the symlink is allowed, -ve on error. | |
724 | */ | |
725 | static inline int may_follow_link(struct path *link, struct nameidata *nd) | |
726 | { | |
727 | const struct inode *inode; | |
728 | const struct inode *parent; | |
729 | ||
730 | if (!sysctl_protected_symlinks) | |
731 | return 0; | |
732 | ||
733 | /* Allowed if owner and follower match. */ | |
734 | inode = link->dentry->d_inode; | |
81abe27b | 735 | if (uid_eq(current_cred()->fsuid, inode->i_uid)) |
800179c9 KC |
736 | return 0; |
737 | ||
738 | /* Allowed if parent directory not sticky and world-writable. */ | |
739 | parent = nd->path.dentry->d_inode; | |
740 | if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) | |
741 | return 0; | |
742 | ||
743 | /* Allowed if parent directory and link owner match. */ | |
81abe27b | 744 | if (uid_eq(parent->i_uid, inode->i_uid)) |
800179c9 KC |
745 | return 0; |
746 | ||
ffd8d101 | 747 | audit_log_link_denied("follow_link", link); |
800179c9 KC |
748 | path_put_conditional(link, nd); |
749 | path_put(&nd->path); | |
750 | return -EACCES; | |
751 | } | |
752 | ||
753 | /** | |
754 | * safe_hardlink_source - Check for safe hardlink conditions | |
755 | * @inode: the source inode to hardlink from | |
756 | * | |
757 | * Return false if at least one of the following conditions: | |
758 | * - inode is not a regular file | |
759 | * - inode is setuid | |
760 | * - inode is setgid and group-exec | |
761 | * - access failure for read and write | |
762 | * | |
763 | * Otherwise returns true. | |
764 | */ | |
765 | static bool safe_hardlink_source(struct inode *inode) | |
766 | { | |
767 | umode_t mode = inode->i_mode; | |
768 | ||
769 | /* Special files should not get pinned to the filesystem. */ | |
770 | if (!S_ISREG(mode)) | |
771 | return false; | |
772 | ||
773 | /* Setuid files should not get pinned to the filesystem. */ | |
774 | if (mode & S_ISUID) | |
775 | return false; | |
776 | ||
777 | /* Executable setgid files should not get pinned to the filesystem. */ | |
778 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) | |
779 | return false; | |
780 | ||
781 | /* Hardlinking to unreadable or unwritable sources is dangerous. */ | |
782 | if (inode_permission(inode, MAY_READ | MAY_WRITE)) | |
783 | return false; | |
784 | ||
785 | return true; | |
786 | } | |
787 | ||
788 | /** | |
789 | * may_linkat - Check permissions for creating a hardlink | |
790 | * @link: the source to hardlink from | |
791 | * | |
792 | * Block hardlink when all of: | |
793 | * - sysctl_protected_hardlinks enabled | |
794 | * - fsuid does not match inode | |
795 | * - hardlink source is unsafe (see safe_hardlink_source() above) | |
796 | * - not CAP_FOWNER | |
797 | * | |
798 | * Returns 0 if successful, -ve on error. | |
799 | */ | |
800 | static int may_linkat(struct path *link) | |
801 | { | |
802 | const struct cred *cred; | |
803 | struct inode *inode; | |
804 | ||
805 | if (!sysctl_protected_hardlinks) | |
806 | return 0; | |
807 | ||
808 | cred = current_cred(); | |
809 | inode = link->dentry->d_inode; | |
810 | ||
811 | /* Source inode owner (or CAP_FOWNER) can hardlink all they like, | |
812 | * otherwise, it must be a safe source. | |
813 | */ | |
81abe27b | 814 | if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || |
800179c9 KC |
815 | capable(CAP_FOWNER)) |
816 | return 0; | |
817 | ||
a51d9eaa | 818 | audit_log_link_denied("linkat", link); |
800179c9 KC |
819 | return -EPERM; |
820 | } | |
821 | ||
def4af30 | 822 | static __always_inline int |
574197e0 | 823 | follow_link(struct path *link, struct nameidata *nd, void **p) |
1da177e4 | 824 | { |
7b9337aa | 825 | struct dentry *dentry = link->dentry; |
6d7b5aae AV |
826 | int error; |
827 | char *s; | |
1da177e4 | 828 | |
844a3917 AV |
829 | BUG_ON(nd->flags & LOOKUP_RCU); |
830 | ||
0e794589 AV |
831 | if (link->mnt == nd->path.mnt) |
832 | mntget(link->mnt); | |
833 | ||
6d7b5aae AV |
834 | error = -ELOOP; |
835 | if (unlikely(current->total_link_count >= 40)) | |
836 | goto out_put_nd_path; | |
837 | ||
574197e0 AV |
838 | cond_resched(); |
839 | current->total_link_count++; | |
840 | ||
68ac1234 | 841 | touch_atime(link); |
1da177e4 | 842 | nd_set_link(nd, NULL); |
cd4e91d3 | 843 | |
36f3b4f6 | 844 | error = security_inode_follow_link(link->dentry, nd); |
6d7b5aae AV |
845 | if (error) |
846 | goto out_put_nd_path; | |
36f3b4f6 | 847 | |
86acdca1 | 848 | nd->last_type = LAST_BIND; |
def4af30 AV |
849 | *p = dentry->d_inode->i_op->follow_link(dentry, nd); |
850 | error = PTR_ERR(*p); | |
6d7b5aae | 851 | if (IS_ERR(*p)) |
408ef013 | 852 | goto out_put_nd_path; |
6d7b5aae AV |
853 | |
854 | error = 0; | |
855 | s = nd_get_link(nd); | |
856 | if (s) { | |
443ed254 AV |
857 | if (unlikely(IS_ERR(s))) { |
858 | path_put(&nd->path); | |
859 | put_link(nd, link, *p); | |
860 | return PTR_ERR(s); | |
861 | } | |
862 | if (*s == '/') { | |
863 | set_root(nd); | |
864 | path_put(&nd->path); | |
865 | nd->path = nd->root; | |
866 | path_get(&nd->root); | |
867 | nd->flags |= LOOKUP_JUMPED; | |
868 | } | |
869 | nd->inode = nd->path.dentry->d_inode; | |
870 | error = link_path_walk(s, nd); | |
b5fb63c1 CH |
871 | if (unlikely(error)) |
872 | put_link(nd, link, *p); | |
1da177e4 | 873 | } |
6d7b5aae AV |
874 | |
875 | return error; | |
876 | ||
877 | out_put_nd_path: | |
98f6ef64 | 878 | *p = NULL; |
6d7b5aae | 879 | path_put(&nd->path); |
6d7b5aae | 880 | path_put(link); |
1da177e4 LT |
881 | return error; |
882 | } | |
883 | ||
31e6b01f NP |
884 | static int follow_up_rcu(struct path *path) |
885 | { | |
0714a533 AV |
886 | struct mount *mnt = real_mount(path->mnt); |
887 | struct mount *parent; | |
31e6b01f NP |
888 | struct dentry *mountpoint; |
889 | ||
0714a533 AV |
890 | parent = mnt->mnt_parent; |
891 | if (&parent->mnt == path->mnt) | |
31e6b01f | 892 | return 0; |
a73324da | 893 | mountpoint = mnt->mnt_mountpoint; |
31e6b01f | 894 | path->dentry = mountpoint; |
0714a533 | 895 | path->mnt = &parent->mnt; |
31e6b01f NP |
896 | return 1; |
897 | } | |
898 | ||
f015f126 DH |
899 | /* |
900 | * follow_up - Find the mountpoint of path's vfsmount | |
901 | * | |
902 | * Given a path, find the mountpoint of its source file system. | |
903 | * Replace @path with the path of the mountpoint in the parent mount. | |
904 | * Up is towards /. | |
905 | * | |
906 | * Return 1 if we went up a level and 0 if we were already at the | |
907 | * root. | |
908 | */ | |
bab77ebf | 909 | int follow_up(struct path *path) |
1da177e4 | 910 | { |
0714a533 AV |
911 | struct mount *mnt = real_mount(path->mnt); |
912 | struct mount *parent; | |
1da177e4 | 913 | struct dentry *mountpoint; |
99b7db7b | 914 | |
48a066e7 | 915 | read_seqlock_excl(&mount_lock); |
0714a533 | 916 | parent = mnt->mnt_parent; |
3c0a6163 | 917 | if (parent == mnt) { |
48a066e7 | 918 | read_sequnlock_excl(&mount_lock); |
1da177e4 LT |
919 | return 0; |
920 | } | |
0714a533 | 921 | mntget(&parent->mnt); |
a73324da | 922 | mountpoint = dget(mnt->mnt_mountpoint); |
48a066e7 | 923 | read_sequnlock_excl(&mount_lock); |
bab77ebf AV |
924 | dput(path->dentry); |
925 | path->dentry = mountpoint; | |
926 | mntput(path->mnt); | |
0714a533 | 927 | path->mnt = &parent->mnt; |
1da177e4 LT |
928 | return 1; |
929 | } | |
4d359507 | 930 | EXPORT_SYMBOL(follow_up); |
1da177e4 | 931 | |
b5c84bf6 | 932 | /* |
9875cf80 DH |
933 | * Perform an automount |
934 | * - return -EISDIR to tell follow_managed() to stop and return the path we | |
935 | * were called with. | |
1da177e4 | 936 | */ |
9875cf80 DH |
937 | static int follow_automount(struct path *path, unsigned flags, |
938 | bool *need_mntput) | |
31e6b01f | 939 | { |
9875cf80 | 940 | struct vfsmount *mnt; |
ea5b778a | 941 | int err; |
9875cf80 DH |
942 | |
943 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) | |
944 | return -EREMOTE; | |
945 | ||
0ec26fd0 MS |
946 | /* We don't want to mount if someone's just doing a stat - |
947 | * unless they're stat'ing a directory and appended a '/' to | |
948 | * the name. | |
949 | * | |
950 | * We do, however, want to mount if someone wants to open or | |
951 | * create a file of any type under the mountpoint, wants to | |
952 | * traverse through the mountpoint or wants to open the | |
953 | * mounted directory. Also, autofs may mark negative dentries | |
954 | * as being automount points. These will need the attentions | |
955 | * of the daemon to instantiate them before they can be used. | |
9875cf80 | 956 | */ |
0ec26fd0 | 957 | if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
d94c177b | 958 | LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && |
0ec26fd0 MS |
959 | path->dentry->d_inode) |
960 | return -EISDIR; | |
961 | ||
9875cf80 DH |
962 | current->total_link_count++; |
963 | if (current->total_link_count >= 40) | |
964 | return -ELOOP; | |
965 | ||
966 | mnt = path->dentry->d_op->d_automount(path); | |
967 | if (IS_ERR(mnt)) { | |
968 | /* | |
969 | * The filesystem is allowed to return -EISDIR here to indicate | |
970 | * it doesn't want to automount. For instance, autofs would do | |
971 | * this so that its userspace daemon can mount on this dentry. | |
972 | * | |
973 | * However, we can only permit this if it's a terminal point in | |
974 | * the path being looked up; if it wasn't then the remainder of | |
975 | * the path is inaccessible and we should say so. | |
976 | */ | |
49084c3b | 977 | if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) |
9875cf80 DH |
978 | return -EREMOTE; |
979 | return PTR_ERR(mnt); | |
31e6b01f | 980 | } |
ea5b778a | 981 | |
9875cf80 DH |
982 | if (!mnt) /* mount collision */ |
983 | return 0; | |
31e6b01f | 984 | |
8aef1884 AV |
985 | if (!*need_mntput) { |
986 | /* lock_mount() may release path->mnt on error */ | |
987 | mntget(path->mnt); | |
988 | *need_mntput = true; | |
989 | } | |
19a167af | 990 | err = finish_automount(mnt, path); |
9875cf80 | 991 | |
ea5b778a DH |
992 | switch (err) { |
993 | case -EBUSY: | |
994 | /* Someone else made a mount here whilst we were busy */ | |
19a167af | 995 | return 0; |
ea5b778a | 996 | case 0: |
8aef1884 | 997 | path_put(path); |
ea5b778a DH |
998 | path->mnt = mnt; |
999 | path->dentry = dget(mnt->mnt_root); | |
ea5b778a | 1000 | return 0; |
19a167af AV |
1001 | default: |
1002 | return err; | |
ea5b778a | 1003 | } |
19a167af | 1004 | |
463ffb2e AV |
1005 | } |
1006 | ||
9875cf80 DH |
1007 | /* |
1008 | * Handle a dentry that is managed in some way. | |
cc53ce53 | 1009 | * - Flagged for transit management (autofs) |
9875cf80 DH |
1010 | * - Flagged as mountpoint |
1011 | * - Flagged as automount point | |
1012 | * | |
1013 | * This may only be called in refwalk mode. | |
1014 | * | |
1015 | * Serialization is taken care of in namespace.c | |
1016 | */ | |
1017 | static int follow_managed(struct path *path, unsigned flags) | |
1da177e4 | 1018 | { |
8aef1884 | 1019 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
9875cf80 DH |
1020 | unsigned managed; |
1021 | bool need_mntput = false; | |
8aef1884 | 1022 | int ret = 0; |
9875cf80 DH |
1023 | |
1024 | /* Given that we're not holding a lock here, we retain the value in a | |
1025 | * local variable for each dentry as we look at it so that we don't see | |
1026 | * the components of that value change under us */ | |
1027 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1028 | managed &= DCACHE_MANAGED_DENTRY, | |
1029 | unlikely(managed != 0)) { | |
cc53ce53 DH |
1030 | /* Allow the filesystem to manage the transit without i_mutex |
1031 | * being held. */ | |
1032 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1033 | BUG_ON(!path->dentry->d_op); | |
1034 | BUG_ON(!path->dentry->d_op->d_manage); | |
1aed3e42 | 1035 | ret = path->dentry->d_op->d_manage(path->dentry, false); |
cc53ce53 | 1036 | if (ret < 0) |
8aef1884 | 1037 | break; |
cc53ce53 DH |
1038 | } |
1039 | ||
9875cf80 DH |
1040 | /* Transit to a mounted filesystem. */ |
1041 | if (managed & DCACHE_MOUNTED) { | |
1042 | struct vfsmount *mounted = lookup_mnt(path); | |
1043 | if (mounted) { | |
1044 | dput(path->dentry); | |
1045 | if (need_mntput) | |
1046 | mntput(path->mnt); | |
1047 | path->mnt = mounted; | |
1048 | path->dentry = dget(mounted->mnt_root); | |
1049 | need_mntput = true; | |
1050 | continue; | |
1051 | } | |
1052 | ||
1053 | /* Something is mounted on this dentry in another | |
1054 | * namespace and/or whatever was mounted there in this | |
48a066e7 AV |
1055 | * namespace got unmounted before lookup_mnt() could |
1056 | * get it */ | |
9875cf80 DH |
1057 | } |
1058 | ||
1059 | /* Handle an automount point */ | |
1060 | if (managed & DCACHE_NEED_AUTOMOUNT) { | |
1061 | ret = follow_automount(path, flags, &need_mntput); | |
1062 | if (ret < 0) | |
8aef1884 | 1063 | break; |
9875cf80 DH |
1064 | continue; |
1065 | } | |
1066 | ||
1067 | /* We didn't change the current path point */ | |
1068 | break; | |
1da177e4 | 1069 | } |
8aef1884 AV |
1070 | |
1071 | if (need_mntput && path->mnt == mnt) | |
1072 | mntput(path->mnt); | |
1073 | if (ret == -EISDIR) | |
1074 | ret = 0; | |
a3fbbde7 | 1075 | return ret < 0 ? ret : need_mntput; |
1da177e4 LT |
1076 | } |
1077 | ||
cc53ce53 | 1078 | int follow_down_one(struct path *path) |
1da177e4 LT |
1079 | { |
1080 | struct vfsmount *mounted; | |
1081 | ||
1c755af4 | 1082 | mounted = lookup_mnt(path); |
1da177e4 | 1083 | if (mounted) { |
9393bd07 AV |
1084 | dput(path->dentry); |
1085 | mntput(path->mnt); | |
1086 | path->mnt = mounted; | |
1087 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
1088 | return 1; |
1089 | } | |
1090 | return 0; | |
1091 | } | |
4d359507 | 1092 | EXPORT_SYMBOL(follow_down_one); |
1da177e4 | 1093 | |
62a7375e IK |
1094 | static inline bool managed_dentry_might_block(struct dentry *dentry) |
1095 | { | |
1096 | return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && | |
1097 | dentry->d_op->d_manage(dentry, true) < 0); | |
1098 | } | |
1099 | ||
9875cf80 | 1100 | /* |
287548e4 AV |
1101 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
1102 | * we meet a managed dentry that would need blocking. | |
9875cf80 DH |
1103 | */ |
1104 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, | |
287548e4 | 1105 | struct inode **inode) |
9875cf80 | 1106 | { |
62a7375e | 1107 | for (;;) { |
c7105365 | 1108 | struct mount *mounted; |
62a7375e IK |
1109 | /* |
1110 | * Don't forget we might have a non-mountpoint managed dentry | |
1111 | * that wants to block transit. | |
1112 | */ | |
287548e4 | 1113 | if (unlikely(managed_dentry_might_block(path->dentry))) |
ab90911f | 1114 | return false; |
62a7375e IK |
1115 | |
1116 | if (!d_mountpoint(path->dentry)) | |
b37199e6 | 1117 | return true; |
62a7375e | 1118 | |
474279dc | 1119 | mounted = __lookup_mnt(path->mnt, path->dentry); |
9875cf80 DH |
1120 | if (!mounted) |
1121 | break; | |
c7105365 AV |
1122 | path->mnt = &mounted->mnt; |
1123 | path->dentry = mounted->mnt.mnt_root; | |
a3fbbde7 | 1124 | nd->flags |= LOOKUP_JUMPED; |
9875cf80 | 1125 | nd->seq = read_seqcount_begin(&path->dentry->d_seq); |
59430262 LT |
1126 | /* |
1127 | * Update the inode too. We don't need to re-check the | |
1128 | * dentry sequence number here after this d_inode read, | |
1129 | * because a mount-point is always pinned. | |
1130 | */ | |
1131 | *inode = path->dentry->d_inode; | |
9875cf80 | 1132 | } |
b37199e6 | 1133 | return read_seqretry(&mount_lock, nd->m_seq); |
287548e4 AV |
1134 | } |
1135 | ||
31e6b01f NP |
1136 | static int follow_dotdot_rcu(struct nameidata *nd) |
1137 | { | |
31e6b01f NP |
1138 | set_root_rcu(nd); |
1139 | ||
9875cf80 | 1140 | while (1) { |
31e6b01f NP |
1141 | if (nd->path.dentry == nd->root.dentry && |
1142 | nd->path.mnt == nd->root.mnt) { | |
1143 | break; | |
1144 | } | |
1145 | if (nd->path.dentry != nd->path.mnt->mnt_root) { | |
1146 | struct dentry *old = nd->path.dentry; | |
1147 | struct dentry *parent = old->d_parent; | |
1148 | unsigned seq; | |
1149 | ||
1150 | seq = read_seqcount_begin(&parent->d_seq); | |
1151 | if (read_seqcount_retry(&old->d_seq, nd->seq)) | |
ef7562d5 | 1152 | goto failed; |
31e6b01f NP |
1153 | nd->path.dentry = parent; |
1154 | nd->seq = seq; | |
1155 | break; | |
1156 | } | |
1157 | if (!follow_up_rcu(&nd->path)) | |
1158 | break; | |
1159 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
31e6b01f | 1160 | } |
b37199e6 AV |
1161 | while (d_mountpoint(nd->path.dentry)) { |
1162 | struct mount *mounted; | |
1163 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); | |
1164 | if (!mounted) | |
1165 | break; | |
1166 | nd->path.mnt = &mounted->mnt; | |
1167 | nd->path.dentry = mounted->mnt.mnt_root; | |
1168 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
1169 | if (!read_seqretry(&mount_lock, nd->m_seq)) | |
1170 | goto failed; | |
1171 | } | |
dea39376 | 1172 | nd->inode = nd->path.dentry->d_inode; |
31e6b01f | 1173 | return 0; |
ef7562d5 AV |
1174 | |
1175 | failed: | |
1176 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1177 | if (!(nd->flags & LOOKUP_ROOT)) |
1178 | nd->root.mnt = NULL; | |
8b61e74f | 1179 | rcu_read_unlock(); |
ef7562d5 | 1180 | return -ECHILD; |
31e6b01f NP |
1181 | } |
1182 | ||
cc53ce53 DH |
1183 | /* |
1184 | * Follow down to the covering mount currently visible to userspace. At each | |
1185 | * point, the filesystem owning that dentry may be queried as to whether the | |
1186 | * caller is permitted to proceed or not. | |
cc53ce53 | 1187 | */ |
7cc90cc3 | 1188 | int follow_down(struct path *path) |
cc53ce53 DH |
1189 | { |
1190 | unsigned managed; | |
1191 | int ret; | |
1192 | ||
1193 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1194 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { | |
1195 | /* Allow the filesystem to manage the transit without i_mutex | |
1196 | * being held. | |
1197 | * | |
1198 | * We indicate to the filesystem if someone is trying to mount | |
1199 | * something here. This gives autofs the chance to deny anyone | |
1200 | * other than its daemon the right to mount on its | |
1201 | * superstructure. | |
1202 | * | |
1203 | * The filesystem may sleep at this point. | |
1204 | */ | |
1205 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1206 | BUG_ON(!path->dentry->d_op); | |
1207 | BUG_ON(!path->dentry->d_op->d_manage); | |
ab90911f | 1208 | ret = path->dentry->d_op->d_manage( |
1aed3e42 | 1209 | path->dentry, false); |
cc53ce53 DH |
1210 | if (ret < 0) |
1211 | return ret == -EISDIR ? 0 : ret; | |
1212 | } | |
1213 | ||
1214 | /* Transit to a mounted filesystem. */ | |
1215 | if (managed & DCACHE_MOUNTED) { | |
1216 | struct vfsmount *mounted = lookup_mnt(path); | |
1217 | if (!mounted) | |
1218 | break; | |
1219 | dput(path->dentry); | |
1220 | mntput(path->mnt); | |
1221 | path->mnt = mounted; | |
1222 | path->dentry = dget(mounted->mnt_root); | |
1223 | continue; | |
1224 | } | |
1225 | ||
1226 | /* Don't handle automount points here */ | |
1227 | break; | |
1228 | } | |
1229 | return 0; | |
1230 | } | |
4d359507 | 1231 | EXPORT_SYMBOL(follow_down); |
cc53ce53 | 1232 | |
9875cf80 DH |
1233 | /* |
1234 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() | |
1235 | */ | |
1236 | static void follow_mount(struct path *path) | |
1237 | { | |
1238 | while (d_mountpoint(path->dentry)) { | |
1239 | struct vfsmount *mounted = lookup_mnt(path); | |
1240 | if (!mounted) | |
1241 | break; | |
1242 | dput(path->dentry); | |
1243 | mntput(path->mnt); | |
1244 | path->mnt = mounted; | |
1245 | path->dentry = dget(mounted->mnt_root); | |
1246 | } | |
1247 | } | |
1248 | ||
31e6b01f | 1249 | static void follow_dotdot(struct nameidata *nd) |
1da177e4 | 1250 | { |
2a737871 | 1251 | set_root(nd); |
e518ddb7 | 1252 | |
1da177e4 | 1253 | while(1) { |
4ac91378 | 1254 | struct dentry *old = nd->path.dentry; |
1da177e4 | 1255 | |
2a737871 AV |
1256 | if (nd->path.dentry == nd->root.dentry && |
1257 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
1258 | break; |
1259 | } | |
4ac91378 | 1260 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
3088dd70 AV |
1261 | /* rare case of legitimate dget_parent()... */ |
1262 | nd->path.dentry = dget_parent(nd->path.dentry); | |
1da177e4 LT |
1263 | dput(old); |
1264 | break; | |
1265 | } | |
3088dd70 | 1266 | if (!follow_up(&nd->path)) |
1da177e4 | 1267 | break; |
1da177e4 | 1268 | } |
79ed0226 | 1269 | follow_mount(&nd->path); |
31e6b01f | 1270 | nd->inode = nd->path.dentry->d_inode; |
1da177e4 LT |
1271 | } |
1272 | ||
baa03890 | 1273 | /* |
bad61189 MS |
1274 | * This looks up the name in dcache, possibly revalidates the old dentry and |
1275 | * allocates a new one if not found or not valid. In the need_lookup argument | |
1276 | * returns whether i_op->lookup is necessary. | |
1277 | * | |
1278 | * dir->d_inode->i_mutex must be held | |
baa03890 | 1279 | */ |
bad61189 | 1280 | static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, |
201f956e | 1281 | unsigned int flags, bool *need_lookup) |
baa03890 | 1282 | { |
baa03890 | 1283 | struct dentry *dentry; |
bad61189 | 1284 | int error; |
baa03890 | 1285 | |
bad61189 MS |
1286 | *need_lookup = false; |
1287 | dentry = d_lookup(dir, name); | |
1288 | if (dentry) { | |
39e3c955 | 1289 | if (dentry->d_flags & DCACHE_OP_REVALIDATE) { |
201f956e | 1290 | error = d_revalidate(dentry, flags); |
bad61189 MS |
1291 | if (unlikely(error <= 0)) { |
1292 | if (error < 0) { | |
1293 | dput(dentry); | |
1294 | return ERR_PTR(error); | |
1295 | } else if (!d_invalidate(dentry)) { | |
1296 | dput(dentry); | |
1297 | dentry = NULL; | |
1298 | } | |
1299 | } | |
1300 | } | |
1301 | } | |
baa03890 | 1302 | |
bad61189 MS |
1303 | if (!dentry) { |
1304 | dentry = d_alloc(dir, name); | |
1305 | if (unlikely(!dentry)) | |
1306 | return ERR_PTR(-ENOMEM); | |
baa03890 | 1307 | |
bad61189 | 1308 | *need_lookup = true; |
baa03890 NP |
1309 | } |
1310 | return dentry; | |
1311 | } | |
1312 | ||
44396f4b | 1313 | /* |
13a2c3be BF |
1314 | * Call i_op->lookup on the dentry. The dentry must be negative and |
1315 | * unhashed. | |
bad61189 MS |
1316 | * |
1317 | * dir->d_inode->i_mutex must be held | |
44396f4b | 1318 | */ |
bad61189 | 1319 | static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, |
72bd866a | 1320 | unsigned int flags) |
44396f4b | 1321 | { |
44396f4b JB |
1322 | struct dentry *old; |
1323 | ||
1324 | /* Don't create child dentry for a dead directory. */ | |
bad61189 | 1325 | if (unlikely(IS_DEADDIR(dir))) { |
e188dc02 | 1326 | dput(dentry); |
44396f4b | 1327 | return ERR_PTR(-ENOENT); |
e188dc02 | 1328 | } |
44396f4b | 1329 | |
72bd866a | 1330 | old = dir->i_op->lookup(dir, dentry, flags); |
44396f4b JB |
1331 | if (unlikely(old)) { |
1332 | dput(dentry); | |
1333 | dentry = old; | |
1334 | } | |
1335 | return dentry; | |
1336 | } | |
1337 | ||
a3255546 | 1338 | static struct dentry *__lookup_hash(struct qstr *name, |
72bd866a | 1339 | struct dentry *base, unsigned int flags) |
a3255546 | 1340 | { |
bad61189 | 1341 | bool need_lookup; |
a3255546 AV |
1342 | struct dentry *dentry; |
1343 | ||
72bd866a | 1344 | dentry = lookup_dcache(name, base, flags, &need_lookup); |
bad61189 MS |
1345 | if (!need_lookup) |
1346 | return dentry; | |
a3255546 | 1347 | |
72bd866a | 1348 | return lookup_real(base->d_inode, dentry, flags); |
a3255546 AV |
1349 | } |
1350 | ||
1da177e4 LT |
1351 | /* |
1352 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
1353 | * small and for now I'd prefer to have fast path as straight as possible. | |
1354 | * It _is_ time-critical. | |
1355 | */ | |
e97cdc87 | 1356 | static int lookup_fast(struct nameidata *nd, |
697f514d | 1357 | struct path *path, struct inode **inode) |
1da177e4 | 1358 | { |
4ac91378 | 1359 | struct vfsmount *mnt = nd->path.mnt; |
31e6b01f | 1360 | struct dentry *dentry, *parent = nd->path.dentry; |
5a18fff2 AV |
1361 | int need_reval = 1; |
1362 | int status = 1; | |
9875cf80 DH |
1363 | int err; |
1364 | ||
b04f784e NP |
1365 | /* |
1366 | * Rename seqlock is not required here because in the off chance | |
1367 | * of a false negative due to a concurrent rename, we're going to | |
1368 | * do the non-racy lookup, below. | |
1369 | */ | |
31e6b01f NP |
1370 | if (nd->flags & LOOKUP_RCU) { |
1371 | unsigned seq; | |
da53be12 | 1372 | dentry = __d_lookup_rcu(parent, &nd->last, &seq); |
5a18fff2 AV |
1373 | if (!dentry) |
1374 | goto unlazy; | |
1375 | ||
12f8ad4b LT |
1376 | /* |
1377 | * This sequence count validates that the inode matches | |
1378 | * the dentry name information from lookup. | |
1379 | */ | |
1380 | *inode = dentry->d_inode; | |
1381 | if (read_seqcount_retry(&dentry->d_seq, seq)) | |
1382 | return -ECHILD; | |
1383 | ||
1384 | /* | |
1385 | * This sequence count validates that the parent had no | |
1386 | * changes while we did the lookup of the dentry above. | |
1387 | * | |
1388 | * The memory barrier in read_seqcount_begin of child is | |
1389 | * enough, we can use __read_seqcount_retry here. | |
1390 | */ | |
31e6b01f NP |
1391 | if (__read_seqcount_retry(&parent->d_seq, nd->seq)) |
1392 | return -ECHILD; | |
31e6b01f | 1393 | nd->seq = seq; |
5a18fff2 | 1394 | |
24643087 | 1395 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
4ce16ef3 | 1396 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1397 | if (unlikely(status <= 0)) { |
1398 | if (status != -ECHILD) | |
1399 | need_reval = 0; | |
1400 | goto unlazy; | |
1401 | } | |
24643087 | 1402 | } |
31e6b01f NP |
1403 | path->mnt = mnt; |
1404 | path->dentry = dentry; | |
d6e9bd25 AV |
1405 | if (unlikely(!__follow_mount_rcu(nd, path, inode))) |
1406 | goto unlazy; | |
1407 | if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) | |
1408 | goto unlazy; | |
1409 | return 0; | |
5a18fff2 | 1410 | unlazy: |
19660af7 AV |
1411 | if (unlazy_walk(nd, dentry)) |
1412 | return -ECHILD; | |
5a18fff2 | 1413 | } else { |
e97cdc87 | 1414 | dentry = __d_lookup(parent, &nd->last); |
9875cf80 | 1415 | } |
5a18fff2 | 1416 | |
81e6f520 AV |
1417 | if (unlikely(!dentry)) |
1418 | goto need_lookup; | |
1419 | ||
5a18fff2 | 1420 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) |
4ce16ef3 | 1421 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1422 | if (unlikely(status <= 0)) { |
1423 | if (status < 0) { | |
1424 | dput(dentry); | |
1425 | return status; | |
1426 | } | |
1427 | if (!d_invalidate(dentry)) { | |
1428 | dput(dentry); | |
81e6f520 | 1429 | goto need_lookup; |
5a18fff2 | 1430 | } |
24643087 | 1431 | } |
697f514d | 1432 | |
9875cf80 DH |
1433 | path->mnt = mnt; |
1434 | path->dentry = dentry; | |
1435 | err = follow_managed(path, nd->flags); | |
89312214 IK |
1436 | if (unlikely(err < 0)) { |
1437 | path_put_conditional(path, nd); | |
9875cf80 | 1438 | return err; |
89312214 | 1439 | } |
a3fbbde7 AV |
1440 | if (err) |
1441 | nd->flags |= LOOKUP_JUMPED; | |
9875cf80 | 1442 | *inode = path->dentry->d_inode; |
1da177e4 | 1443 | return 0; |
81e6f520 AV |
1444 | |
1445 | need_lookup: | |
697f514d MS |
1446 | return 1; |
1447 | } | |
1448 | ||
1449 | /* Fast lookup failed, do it the slow way */ | |
cc2a5271 | 1450 | static int lookup_slow(struct nameidata *nd, struct path *path) |
697f514d MS |
1451 | { |
1452 | struct dentry *dentry, *parent; | |
1453 | int err; | |
1454 | ||
1455 | parent = nd->path.dentry; | |
81e6f520 AV |
1456 | BUG_ON(nd->inode != parent->d_inode); |
1457 | ||
1458 | mutex_lock(&parent->d_inode->i_mutex); | |
cc2a5271 | 1459 | dentry = __lookup_hash(&nd->last, parent, nd->flags); |
81e6f520 AV |
1460 | mutex_unlock(&parent->d_inode->i_mutex); |
1461 | if (IS_ERR(dentry)) | |
1462 | return PTR_ERR(dentry); | |
697f514d MS |
1463 | path->mnt = nd->path.mnt; |
1464 | path->dentry = dentry; | |
1465 | err = follow_managed(path, nd->flags); | |
1466 | if (unlikely(err < 0)) { | |
1467 | path_put_conditional(path, nd); | |
1468 | return err; | |
1469 | } | |
1470 | if (err) | |
1471 | nd->flags |= LOOKUP_JUMPED; | |
1472 | return 0; | |
1da177e4 LT |
1473 | } |
1474 | ||
52094c8a AV |
1475 | static inline int may_lookup(struct nameidata *nd) |
1476 | { | |
1477 | if (nd->flags & LOOKUP_RCU) { | |
4ad5abb3 | 1478 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
52094c8a AV |
1479 | if (err != -ECHILD) |
1480 | return err; | |
19660af7 | 1481 | if (unlazy_walk(nd, NULL)) |
52094c8a AV |
1482 | return -ECHILD; |
1483 | } | |
4ad5abb3 | 1484 | return inode_permission(nd->inode, MAY_EXEC); |
52094c8a AV |
1485 | } |
1486 | ||
9856fa1b AV |
1487 | static inline int handle_dots(struct nameidata *nd, int type) |
1488 | { | |
1489 | if (type == LAST_DOTDOT) { | |
1490 | if (nd->flags & LOOKUP_RCU) { | |
1491 | if (follow_dotdot_rcu(nd)) | |
1492 | return -ECHILD; | |
1493 | } else | |
1494 | follow_dotdot(nd); | |
1495 | } | |
1496 | return 0; | |
1497 | } | |
1498 | ||
951361f9 AV |
1499 | static void terminate_walk(struct nameidata *nd) |
1500 | { | |
1501 | if (!(nd->flags & LOOKUP_RCU)) { | |
1502 | path_put(&nd->path); | |
1503 | } else { | |
1504 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1505 | if (!(nd->flags & LOOKUP_ROOT)) |
1506 | nd->root.mnt = NULL; | |
8b61e74f | 1507 | rcu_read_unlock(); |
951361f9 AV |
1508 | } |
1509 | } | |
1510 | ||
3ddcd056 LT |
1511 | /* |
1512 | * Do we need to follow links? We _really_ want to be able | |
1513 | * to do this check without having to look at inode->i_op, | |
1514 | * so we keep a cache of "no, this doesn't need follow_link" | |
1515 | * for the common case. | |
1516 | */ | |
b18825a7 | 1517 | static inline int should_follow_link(struct dentry *dentry, int follow) |
3ddcd056 | 1518 | { |
b18825a7 | 1519 | return unlikely(d_is_symlink(dentry)) ? follow : 0; |
3ddcd056 LT |
1520 | } |
1521 | ||
ce57dfc1 | 1522 | static inline int walk_component(struct nameidata *nd, struct path *path, |
21b9b073 | 1523 | int follow) |
ce57dfc1 AV |
1524 | { |
1525 | struct inode *inode; | |
1526 | int err; | |
1527 | /* | |
1528 | * "." and ".." are special - ".." especially so because it has | |
1529 | * to be able to know about the current root directory and | |
1530 | * parent relationships. | |
1531 | */ | |
21b9b073 AV |
1532 | if (unlikely(nd->last_type != LAST_NORM)) |
1533 | return handle_dots(nd, nd->last_type); | |
e97cdc87 | 1534 | err = lookup_fast(nd, path, &inode); |
ce57dfc1 | 1535 | if (unlikely(err)) { |
697f514d MS |
1536 | if (err < 0) |
1537 | goto out_err; | |
1538 | ||
cc2a5271 | 1539 | err = lookup_slow(nd, path); |
697f514d MS |
1540 | if (err < 0) |
1541 | goto out_err; | |
1542 | ||
1543 | inode = path->dentry->d_inode; | |
ce57dfc1 | 1544 | } |
697f514d | 1545 | err = -ENOENT; |
22213318 | 1546 | if (!inode || d_is_negative(path->dentry)) |
697f514d MS |
1547 | goto out_path_put; |
1548 | ||
b18825a7 | 1549 | if (should_follow_link(path->dentry, follow)) { |
19660af7 AV |
1550 | if (nd->flags & LOOKUP_RCU) { |
1551 | if (unlikely(unlazy_walk(nd, path->dentry))) { | |
697f514d MS |
1552 | err = -ECHILD; |
1553 | goto out_err; | |
19660af7 AV |
1554 | } |
1555 | } | |
ce57dfc1 AV |
1556 | BUG_ON(inode != path->dentry->d_inode); |
1557 | return 1; | |
1558 | } | |
1559 | path_to_nameidata(path, nd); | |
1560 | nd->inode = inode; | |
1561 | return 0; | |
697f514d MS |
1562 | |
1563 | out_path_put: | |
1564 | path_to_nameidata(path, nd); | |
1565 | out_err: | |
1566 | terminate_walk(nd); | |
1567 | return err; | |
ce57dfc1 AV |
1568 | } |
1569 | ||
b356379a AV |
1570 | /* |
1571 | * This limits recursive symlink follows to 8, while | |
1572 | * limiting consecutive symlinks to 40. | |
1573 | * | |
1574 | * Without that kind of total limit, nasty chains of consecutive | |
1575 | * symlinks can cause almost arbitrarily long lookups. | |
1576 | */ | |
1577 | static inline int nested_symlink(struct path *path, struct nameidata *nd) | |
1578 | { | |
1579 | int res; | |
1580 | ||
b356379a AV |
1581 | if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { |
1582 | path_put_conditional(path, nd); | |
1583 | path_put(&nd->path); | |
1584 | return -ELOOP; | |
1585 | } | |
1a4022f8 | 1586 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); |
b356379a AV |
1587 | |
1588 | nd->depth++; | |
1589 | current->link_count++; | |
1590 | ||
1591 | do { | |
1592 | struct path link = *path; | |
1593 | void *cookie; | |
574197e0 AV |
1594 | |
1595 | res = follow_link(&link, nd, &cookie); | |
6d7b5aae AV |
1596 | if (res) |
1597 | break; | |
21b9b073 | 1598 | res = walk_component(nd, path, LOOKUP_FOLLOW); |
574197e0 | 1599 | put_link(nd, &link, cookie); |
b356379a AV |
1600 | } while (res > 0); |
1601 | ||
1602 | current->link_count--; | |
1603 | nd->depth--; | |
1604 | return res; | |
1605 | } | |
1606 | ||
bfcfaa77 LT |
1607 | /* |
1608 | * We can do the critical dentry name comparison and hashing | |
1609 | * operations one word at a time, but we are limited to: | |
1610 | * | |
1611 | * - Architectures with fast unaligned word accesses. We could | |
1612 | * do a "get_unaligned()" if this helps and is sufficiently | |
1613 | * fast. | |
1614 | * | |
bfcfaa77 LT |
1615 | * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we |
1616 | * do not trap on the (extremely unlikely) case of a page | |
1617 | * crossing operation. | |
1618 | * | |
1619 | * - Furthermore, we need an efficient 64-bit compile for the | |
1620 | * 64-bit case in order to generate the "number of bytes in | |
1621 | * the final mask". Again, that could be replaced with a | |
1622 | * efficient population count instruction or similar. | |
1623 | */ | |
1624 | #ifdef CONFIG_DCACHE_WORD_ACCESS | |
1625 | ||
f68e556e | 1626 | #include <asm/word-at-a-time.h> |
bfcfaa77 | 1627 | |
f68e556e | 1628 | #ifdef CONFIG_64BIT |
bfcfaa77 LT |
1629 | |
1630 | static inline unsigned int fold_hash(unsigned long hash) | |
1631 | { | |
1632 | hash += hash >> (8*sizeof(int)); | |
1633 | return hash; | |
1634 | } | |
1635 | ||
1636 | #else /* 32-bit case */ | |
1637 | ||
bfcfaa77 LT |
1638 | #define fold_hash(x) (x) |
1639 | ||
1640 | #endif | |
1641 | ||
1642 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) | |
1643 | { | |
1644 | unsigned long a, mask; | |
1645 | unsigned long hash = 0; | |
1646 | ||
1647 | for (;;) { | |
e419b4cc | 1648 | a = load_unaligned_zeropad(name); |
bfcfaa77 LT |
1649 | if (len < sizeof(unsigned long)) |
1650 | break; | |
1651 | hash += a; | |
f132c5be | 1652 | hash *= 9; |
bfcfaa77 LT |
1653 | name += sizeof(unsigned long); |
1654 | len -= sizeof(unsigned long); | |
1655 | if (!len) | |
1656 | goto done; | |
1657 | } | |
a5c21dce | 1658 | mask = bytemask_from_count(len); |
bfcfaa77 LT |
1659 | hash += mask & a; |
1660 | done: | |
1661 | return fold_hash(hash); | |
1662 | } | |
1663 | EXPORT_SYMBOL(full_name_hash); | |
1664 | ||
bfcfaa77 LT |
1665 | /* |
1666 | * Calculate the length and hash of the path component, and | |
1667 | * return the length of the component; | |
1668 | */ | |
1669 | static inline unsigned long hash_name(const char *name, unsigned int *hashp) | |
1670 | { | |
36126f8f LT |
1671 | unsigned long a, b, adata, bdata, mask, hash, len; |
1672 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; | |
bfcfaa77 LT |
1673 | |
1674 | hash = a = 0; | |
1675 | len = -sizeof(unsigned long); | |
1676 | do { | |
1677 | hash = (hash + a) * 9; | |
1678 | len += sizeof(unsigned long); | |
e419b4cc | 1679 | a = load_unaligned_zeropad(name+len); |
36126f8f LT |
1680 | b = a ^ REPEAT_BYTE('/'); |
1681 | } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); | |
1682 | ||
1683 | adata = prep_zero_mask(a, adata, &constants); | |
1684 | bdata = prep_zero_mask(b, bdata, &constants); | |
1685 | ||
1686 | mask = create_zero_mask(adata | bdata); | |
1687 | ||
1688 | hash += a & zero_bytemask(mask); | |
bfcfaa77 LT |
1689 | *hashp = fold_hash(hash); |
1690 | ||
36126f8f | 1691 | return len + find_zero(mask); |
bfcfaa77 LT |
1692 | } |
1693 | ||
1694 | #else | |
1695 | ||
0145acc2 LT |
1696 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) |
1697 | { | |
1698 | unsigned long hash = init_name_hash(); | |
1699 | while (len--) | |
1700 | hash = partial_name_hash(*name++, hash); | |
1701 | return end_name_hash(hash); | |
1702 | } | |
ae942ae7 | 1703 | EXPORT_SYMBOL(full_name_hash); |
0145acc2 | 1704 | |
200e9ef7 LT |
1705 | /* |
1706 | * We know there's a real path component here of at least | |
1707 | * one character. | |
1708 | */ | |
1709 | static inline unsigned long hash_name(const char *name, unsigned int *hashp) | |
1710 | { | |
1711 | unsigned long hash = init_name_hash(); | |
1712 | unsigned long len = 0, c; | |
1713 | ||
1714 | c = (unsigned char)*name; | |
1715 | do { | |
1716 | len++; | |
1717 | hash = partial_name_hash(c, hash); | |
1718 | c = (unsigned char)name[len]; | |
1719 | } while (c && c != '/'); | |
1720 | *hashp = end_name_hash(hash); | |
1721 | return len; | |
1722 | } | |
1723 | ||
bfcfaa77 LT |
1724 | #endif |
1725 | ||
1da177e4 LT |
1726 | /* |
1727 | * Name resolution. | |
ea3834d9 PM |
1728 | * This is the basic name resolution function, turning a pathname into |
1729 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 1730 | * |
ea3834d9 PM |
1731 | * Returns 0 and nd will have valid dentry and mnt on success. |
1732 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 1733 | */ |
6de88d72 | 1734 | static int link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 LT |
1735 | { |
1736 | struct path next; | |
1da177e4 | 1737 | int err; |
1da177e4 LT |
1738 | |
1739 | while (*name=='/') | |
1740 | name++; | |
1741 | if (!*name) | |
086e183a | 1742 | return 0; |
1da177e4 | 1743 | |
1da177e4 LT |
1744 | /* At this point we know we have a real path component. */ |
1745 | for(;;) { | |
1da177e4 | 1746 | struct qstr this; |
200e9ef7 | 1747 | long len; |
fe479a58 | 1748 | int type; |
1da177e4 | 1749 | |
52094c8a | 1750 | err = may_lookup(nd); |
1da177e4 LT |
1751 | if (err) |
1752 | break; | |
1753 | ||
200e9ef7 | 1754 | len = hash_name(name, &this.hash); |
1da177e4 | 1755 | this.name = name; |
200e9ef7 | 1756 | this.len = len; |
1da177e4 | 1757 | |
fe479a58 | 1758 | type = LAST_NORM; |
200e9ef7 | 1759 | if (name[0] == '.') switch (len) { |
fe479a58 | 1760 | case 2: |
200e9ef7 | 1761 | if (name[1] == '.') { |
fe479a58 | 1762 | type = LAST_DOTDOT; |
16c2cd71 AV |
1763 | nd->flags |= LOOKUP_JUMPED; |
1764 | } | |
fe479a58 AV |
1765 | break; |
1766 | case 1: | |
1767 | type = LAST_DOT; | |
1768 | } | |
5a202bcd AV |
1769 | if (likely(type == LAST_NORM)) { |
1770 | struct dentry *parent = nd->path.dentry; | |
16c2cd71 | 1771 | nd->flags &= ~LOOKUP_JUMPED; |
5a202bcd | 1772 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
da53be12 | 1773 | err = parent->d_op->d_hash(parent, &this); |
5a202bcd AV |
1774 | if (err < 0) |
1775 | break; | |
1776 | } | |
1777 | } | |
fe479a58 | 1778 | |
5f4a6a69 AV |
1779 | nd->last = this; |
1780 | nd->last_type = type; | |
1781 | ||
200e9ef7 | 1782 | if (!name[len]) |
5f4a6a69 | 1783 | return 0; |
200e9ef7 LT |
1784 | /* |
1785 | * If it wasn't NUL, we know it was '/'. Skip that | |
1786 | * slash, and continue until no more slashes. | |
1787 | */ | |
1788 | do { | |
1789 | len++; | |
1790 | } while (unlikely(name[len] == '/')); | |
1791 | if (!name[len]) | |
5f4a6a69 AV |
1792 | return 0; |
1793 | ||
200e9ef7 | 1794 | name += len; |
1da177e4 | 1795 | |
21b9b073 | 1796 | err = walk_component(nd, &next, LOOKUP_FOLLOW); |
ce57dfc1 AV |
1797 | if (err < 0) |
1798 | return err; | |
1da177e4 | 1799 | |
ce57dfc1 | 1800 | if (err) { |
b356379a | 1801 | err = nested_symlink(&next, nd); |
1da177e4 | 1802 | if (err) |
a7472bab | 1803 | return err; |
31e6b01f | 1804 | } |
44b1d530 | 1805 | if (!d_can_lookup(nd->path.dentry)) { |
5f4a6a69 AV |
1806 | err = -ENOTDIR; |
1807 | break; | |
1808 | } | |
1da177e4 | 1809 | } |
951361f9 | 1810 | terminate_walk(nd); |
1da177e4 LT |
1811 | return err; |
1812 | } | |
1813 | ||
70e9b357 AV |
1814 | static int path_init(int dfd, const char *name, unsigned int flags, |
1815 | struct nameidata *nd, struct file **fp) | |
31e6b01f NP |
1816 | { |
1817 | int retval = 0; | |
31e6b01f NP |
1818 | |
1819 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
16c2cd71 | 1820 | nd->flags = flags | LOOKUP_JUMPED; |
31e6b01f | 1821 | nd->depth = 0; |
5b6ca027 | 1822 | if (flags & LOOKUP_ROOT) { |
b18825a7 DH |
1823 | struct dentry *root = nd->root.dentry; |
1824 | struct inode *inode = root->d_inode; | |
73d049a4 | 1825 | if (*name) { |
44b1d530 | 1826 | if (!d_can_lookup(root)) |
73d049a4 AV |
1827 | return -ENOTDIR; |
1828 | retval = inode_permission(inode, MAY_EXEC); | |
1829 | if (retval) | |
1830 | return retval; | |
1831 | } | |
5b6ca027 AV |
1832 | nd->path = nd->root; |
1833 | nd->inode = inode; | |
1834 | if (flags & LOOKUP_RCU) { | |
8b61e74f | 1835 | rcu_read_lock(); |
5b6ca027 | 1836 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
48a066e7 | 1837 | nd->m_seq = read_seqbegin(&mount_lock); |
5b6ca027 AV |
1838 | } else { |
1839 | path_get(&nd->path); | |
1840 | } | |
1841 | return 0; | |
1842 | } | |
1843 | ||
31e6b01f | 1844 | nd->root.mnt = NULL; |
31e6b01f | 1845 | |
48a066e7 | 1846 | nd->m_seq = read_seqbegin(&mount_lock); |
31e6b01f | 1847 | if (*name=='/') { |
e41f7d4e | 1848 | if (flags & LOOKUP_RCU) { |
8b61e74f | 1849 | rcu_read_lock(); |
e41f7d4e AV |
1850 | set_root_rcu(nd); |
1851 | } else { | |
1852 | set_root(nd); | |
1853 | path_get(&nd->root); | |
1854 | } | |
1855 | nd->path = nd->root; | |
31e6b01f | 1856 | } else if (dfd == AT_FDCWD) { |
e41f7d4e AV |
1857 | if (flags & LOOKUP_RCU) { |
1858 | struct fs_struct *fs = current->fs; | |
1859 | unsigned seq; | |
31e6b01f | 1860 | |
8b61e74f | 1861 | rcu_read_lock(); |
c28cc364 | 1862 | |
e41f7d4e AV |
1863 | do { |
1864 | seq = read_seqcount_begin(&fs->seq); | |
1865 | nd->path = fs->pwd; | |
1866 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
1867 | } while (read_seqcount_retry(&fs->seq, seq)); | |
1868 | } else { | |
1869 | get_fs_pwd(current->fs, &nd->path); | |
1870 | } | |
31e6b01f | 1871 | } else { |
582aa64a | 1872 | /* Caller must check execute permissions on the starting path component */ |
2903ff01 | 1873 | struct fd f = fdget_raw(dfd); |
31e6b01f NP |
1874 | struct dentry *dentry; |
1875 | ||
2903ff01 AV |
1876 | if (!f.file) |
1877 | return -EBADF; | |
31e6b01f | 1878 | |
2903ff01 | 1879 | dentry = f.file->f_path.dentry; |
31e6b01f | 1880 | |
f52e0c11 | 1881 | if (*name) { |
44b1d530 | 1882 | if (!d_can_lookup(dentry)) { |
2903ff01 AV |
1883 | fdput(f); |
1884 | return -ENOTDIR; | |
1885 | } | |
f52e0c11 | 1886 | } |
31e6b01f | 1887 | |
2903ff01 | 1888 | nd->path = f.file->f_path; |
e41f7d4e | 1889 | if (flags & LOOKUP_RCU) { |
9c225f26 | 1890 | if (f.flags & FDPUT_FPUT) |
2903ff01 | 1891 | *fp = f.file; |
e41f7d4e | 1892 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
8b61e74f | 1893 | rcu_read_lock(); |
e41f7d4e | 1894 | } else { |
2903ff01 AV |
1895 | path_get(&nd->path); |
1896 | fdput(f); | |
e41f7d4e | 1897 | } |
31e6b01f | 1898 | } |
31e6b01f | 1899 | |
31e6b01f | 1900 | nd->inode = nd->path.dentry->d_inode; |
9b4a9b14 | 1901 | return 0; |
9b4a9b14 AV |
1902 | } |
1903 | ||
bd92d7fe AV |
1904 | static inline int lookup_last(struct nameidata *nd, struct path *path) |
1905 | { | |
1906 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) | |
1907 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
1908 | ||
1909 | nd->flags &= ~LOOKUP_PARENT; | |
21b9b073 | 1910 | return walk_component(nd, path, nd->flags & LOOKUP_FOLLOW); |
bd92d7fe AV |
1911 | } |
1912 | ||
9b4a9b14 | 1913 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
ee0827cd | 1914 | static int path_lookupat(int dfd, const char *name, |
9b4a9b14 AV |
1915 | unsigned int flags, struct nameidata *nd) |
1916 | { | |
70e9b357 | 1917 | struct file *base = NULL; |
bd92d7fe AV |
1918 | struct path path; |
1919 | int err; | |
31e6b01f NP |
1920 | |
1921 | /* | |
1922 | * Path walking is largely split up into 2 different synchronisation | |
1923 | * schemes, rcu-walk and ref-walk (explained in | |
1924 | * Documentation/filesystems/path-lookup.txt). These share much of the | |
1925 | * path walk code, but some things particularly setup, cleanup, and | |
1926 | * following mounts are sufficiently divergent that functions are | |
1927 | * duplicated. Typically there is a function foo(), and its RCU | |
1928 | * analogue, foo_rcu(). | |
1929 | * | |
1930 | * -ECHILD is the error number of choice (just to avoid clashes) that | |
1931 | * is returned if some aspect of an rcu-walk fails. Such an error must | |
1932 | * be handled by restarting a traditional ref-walk (which will always | |
1933 | * be able to complete). | |
1934 | */ | |
bd92d7fe | 1935 | err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); |
ee0827cd | 1936 | |
bd92d7fe AV |
1937 | if (unlikely(err)) |
1938 | return err; | |
ee0827cd AV |
1939 | |
1940 | current->total_link_count = 0; | |
bd92d7fe AV |
1941 | err = link_path_walk(name, nd); |
1942 | ||
1943 | if (!err && !(flags & LOOKUP_PARENT)) { | |
bd92d7fe AV |
1944 | err = lookup_last(nd, &path); |
1945 | while (err > 0) { | |
1946 | void *cookie; | |
1947 | struct path link = path; | |
800179c9 KC |
1948 | err = may_follow_link(&link, nd); |
1949 | if (unlikely(err)) | |
1950 | break; | |
bd92d7fe | 1951 | nd->flags |= LOOKUP_PARENT; |
574197e0 | 1952 | err = follow_link(&link, nd, &cookie); |
6d7b5aae AV |
1953 | if (err) |
1954 | break; | |
1955 | err = lookup_last(nd, &path); | |
574197e0 | 1956 | put_link(nd, &link, cookie); |
bd92d7fe AV |
1957 | } |
1958 | } | |
ee0827cd | 1959 | |
9f1fafee AV |
1960 | if (!err) |
1961 | err = complete_walk(nd); | |
bd92d7fe AV |
1962 | |
1963 | if (!err && nd->flags & LOOKUP_DIRECTORY) { | |
44b1d530 | 1964 | if (!d_can_lookup(nd->path.dentry)) { |
bd92d7fe | 1965 | path_put(&nd->path); |
bd23a539 | 1966 | err = -ENOTDIR; |
bd92d7fe AV |
1967 | } |
1968 | } | |
16c2cd71 | 1969 | |
70e9b357 AV |
1970 | if (base) |
1971 | fput(base); | |
ee0827cd | 1972 | |
5b6ca027 | 1973 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
2a737871 AV |
1974 | path_put(&nd->root); |
1975 | nd->root.mnt = NULL; | |
1976 | } | |
bd92d7fe | 1977 | return err; |
ee0827cd | 1978 | } |
31e6b01f | 1979 | |
873f1eed | 1980 | static int filename_lookup(int dfd, struct filename *name, |
ee0827cd AV |
1981 | unsigned int flags, struct nameidata *nd) |
1982 | { | |
873f1eed | 1983 | int retval = path_lookupat(dfd, name->name, flags | LOOKUP_RCU, nd); |
ee0827cd | 1984 | if (unlikely(retval == -ECHILD)) |
873f1eed | 1985 | retval = path_lookupat(dfd, name->name, flags, nd); |
ee0827cd | 1986 | if (unlikely(retval == -ESTALE)) |
873f1eed JL |
1987 | retval = path_lookupat(dfd, name->name, |
1988 | flags | LOOKUP_REVAL, nd); | |
31e6b01f | 1989 | |
f78570dd | 1990 | if (likely(!retval)) |
adb5c247 | 1991 | audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); |
170aa3d0 | 1992 | return retval; |
1da177e4 LT |
1993 | } |
1994 | ||
873f1eed JL |
1995 | static int do_path_lookup(int dfd, const char *name, |
1996 | unsigned int flags, struct nameidata *nd) | |
1997 | { | |
1998 | struct filename filename = { .name = name }; | |
1999 | ||
2000 | return filename_lookup(dfd, &filename, flags, nd); | |
2001 | } | |
2002 | ||
79714f72 AV |
2003 | /* does lookup, returns the object with parent locked */ |
2004 | struct dentry *kern_path_locked(const char *name, struct path *path) | |
5590ff0d | 2005 | { |
79714f72 AV |
2006 | struct nameidata nd; |
2007 | struct dentry *d; | |
2008 | int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd); | |
2009 | if (err) | |
2010 | return ERR_PTR(err); | |
2011 | if (nd.last_type != LAST_NORM) { | |
2012 | path_put(&nd.path); | |
2013 | return ERR_PTR(-EINVAL); | |
2014 | } | |
2015 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); | |
1e0ea001 | 2016 | d = __lookup_hash(&nd.last, nd.path.dentry, 0); |
79714f72 AV |
2017 | if (IS_ERR(d)) { |
2018 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); | |
2019 | path_put(&nd.path); | |
2020 | return d; | |
2021 | } | |
2022 | *path = nd.path; | |
2023 | return d; | |
5590ff0d UD |
2024 | } |
2025 | ||
d1811465 AV |
2026 | int kern_path(const char *name, unsigned int flags, struct path *path) |
2027 | { | |
2028 | struct nameidata nd; | |
2029 | int res = do_path_lookup(AT_FDCWD, name, flags, &nd); | |
2030 | if (!res) | |
2031 | *path = nd.path; | |
2032 | return res; | |
2033 | } | |
4d359507 | 2034 | EXPORT_SYMBOL(kern_path); |
d1811465 | 2035 | |
16f18200 JJS |
2036 | /** |
2037 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
2038 | * @dentry: pointer to dentry of the base directory | |
2039 | * @mnt: pointer to vfs mount of the base directory | |
2040 | * @name: pointer to file name | |
2041 | * @flags: lookup flags | |
e0a01249 | 2042 | * @path: pointer to struct path to fill |
16f18200 JJS |
2043 | */ |
2044 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
2045 | const char *name, unsigned int flags, | |
e0a01249 | 2046 | struct path *path) |
16f18200 | 2047 | { |
e0a01249 AV |
2048 | struct nameidata nd; |
2049 | int err; | |
2050 | nd.root.dentry = dentry; | |
2051 | nd.root.mnt = mnt; | |
2052 | BUG_ON(flags & LOOKUP_PARENT); | |
5b6ca027 | 2053 | /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ |
e0a01249 AV |
2054 | err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); |
2055 | if (!err) | |
2056 | *path = nd.path; | |
2057 | return err; | |
16f18200 | 2058 | } |
4d359507 | 2059 | EXPORT_SYMBOL(vfs_path_lookup); |
16f18200 | 2060 | |
057f6c01 JM |
2061 | /* |
2062 | * Restricted form of lookup. Doesn't follow links, single-component only, | |
2063 | * needs parent already locked. Doesn't follow mounts. | |
2064 | * SMP-safe. | |
2065 | */ | |
eead1911 | 2066 | static struct dentry *lookup_hash(struct nameidata *nd) |
057f6c01 | 2067 | { |
72bd866a | 2068 | return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); |
1da177e4 LT |
2069 | } |
2070 | ||
eead1911 | 2071 | /** |
a6b91919 | 2072 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
2073 | * @name: pathname component to lookup |
2074 | * @base: base directory to lookup from | |
2075 | * @len: maximum length @len should be interpreted to | |
2076 | * | |
a6b91919 RD |
2077 | * Note that this routine is purely a helper for filesystem usage and should |
2078 | * not be called by generic code. Also note that by using this function the | |
eead1911 CH |
2079 | * nameidata argument is passed to the filesystem methods and a filesystem |
2080 | * using this helper needs to be prepared for that. | |
2081 | */ | |
057f6c01 JM |
2082 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
2083 | { | |
057f6c01 | 2084 | struct qstr this; |
6a96ba54 | 2085 | unsigned int c; |
cda309de | 2086 | int err; |
057f6c01 | 2087 | |
2f9092e1 DW |
2088 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
2089 | ||
6a96ba54 AV |
2090 | this.name = name; |
2091 | this.len = len; | |
0145acc2 | 2092 | this.hash = full_name_hash(name, len); |
6a96ba54 AV |
2093 | if (!len) |
2094 | return ERR_PTR(-EACCES); | |
2095 | ||
21d8a15a AV |
2096 | if (unlikely(name[0] == '.')) { |
2097 | if (len < 2 || (len == 2 && name[1] == '.')) | |
2098 | return ERR_PTR(-EACCES); | |
2099 | } | |
2100 | ||
6a96ba54 AV |
2101 | while (len--) { |
2102 | c = *(const unsigned char *)name++; | |
2103 | if (c == '/' || c == '\0') | |
2104 | return ERR_PTR(-EACCES); | |
6a96ba54 | 2105 | } |
5a202bcd AV |
2106 | /* |
2107 | * See if the low-level filesystem might want | |
2108 | * to use its own hash.. | |
2109 | */ | |
2110 | if (base->d_flags & DCACHE_OP_HASH) { | |
da53be12 | 2111 | int err = base->d_op->d_hash(base, &this); |
5a202bcd AV |
2112 | if (err < 0) |
2113 | return ERR_PTR(err); | |
2114 | } | |
eead1911 | 2115 | |
cda309de MS |
2116 | err = inode_permission(base->d_inode, MAY_EXEC); |
2117 | if (err) | |
2118 | return ERR_PTR(err); | |
2119 | ||
72bd866a | 2120 | return __lookup_hash(&this, base, 0); |
057f6c01 | 2121 | } |
4d359507 | 2122 | EXPORT_SYMBOL(lookup_one_len); |
057f6c01 | 2123 | |
1fa1e7f6 AW |
2124 | int user_path_at_empty(int dfd, const char __user *name, unsigned flags, |
2125 | struct path *path, int *empty) | |
1da177e4 | 2126 | { |
2d8f3038 | 2127 | struct nameidata nd; |
91a27b2a | 2128 | struct filename *tmp = getname_flags(name, flags, empty); |
1da177e4 | 2129 | int err = PTR_ERR(tmp); |
1da177e4 | 2130 | if (!IS_ERR(tmp)) { |
2d8f3038 AV |
2131 | |
2132 | BUG_ON(flags & LOOKUP_PARENT); | |
2133 | ||
873f1eed | 2134 | err = filename_lookup(dfd, tmp, flags, &nd); |
1da177e4 | 2135 | putname(tmp); |
2d8f3038 AV |
2136 | if (!err) |
2137 | *path = nd.path; | |
1da177e4 LT |
2138 | } |
2139 | return err; | |
2140 | } | |
2141 | ||
1fa1e7f6 AW |
2142 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
2143 | struct path *path) | |
2144 | { | |
f7493e5d | 2145 | return user_path_at_empty(dfd, name, flags, path, NULL); |
1fa1e7f6 | 2146 | } |
4d359507 | 2147 | EXPORT_SYMBOL(user_path_at); |
1fa1e7f6 | 2148 | |
873f1eed JL |
2149 | /* |
2150 | * NB: most callers don't do anything directly with the reference to the | |
2151 | * to struct filename, but the nd->last pointer points into the name string | |
2152 | * allocated by getname. So we must hold the reference to it until all | |
2153 | * path-walking is complete. | |
2154 | */ | |
91a27b2a | 2155 | static struct filename * |
9e790bd6 JL |
2156 | user_path_parent(int dfd, const char __user *path, struct nameidata *nd, |
2157 | unsigned int flags) | |
2ad94ae6 | 2158 | { |
91a27b2a | 2159 | struct filename *s = getname(path); |
2ad94ae6 AV |
2160 | int error; |
2161 | ||
9e790bd6 JL |
2162 | /* only LOOKUP_REVAL is allowed in extra flags */ |
2163 | flags &= LOOKUP_REVAL; | |
2164 | ||
2ad94ae6 | 2165 | if (IS_ERR(s)) |
91a27b2a | 2166 | return s; |
2ad94ae6 | 2167 | |
9e790bd6 | 2168 | error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, nd); |
91a27b2a | 2169 | if (error) { |
2ad94ae6 | 2170 | putname(s); |
91a27b2a JL |
2171 | return ERR_PTR(error); |
2172 | } | |
2ad94ae6 | 2173 | |
91a27b2a | 2174 | return s; |
2ad94ae6 AV |
2175 | } |
2176 | ||
8033426e | 2177 | /** |
197df04c | 2178 | * mountpoint_last - look up last component for umount |
8033426e JL |
2179 | * @nd: pathwalk nameidata - currently pointing at parent directory of "last" |
2180 | * @path: pointer to container for result | |
2181 | * | |
2182 | * This is a special lookup_last function just for umount. In this case, we | |
2183 | * need to resolve the path without doing any revalidation. | |
2184 | * | |
2185 | * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since | |
2186 | * mountpoints are always pinned in the dcache, their ancestors are too. Thus, | |
2187 | * in almost all cases, this lookup will be served out of the dcache. The only | |
2188 | * cases where it won't are if nd->last refers to a symlink or the path is | |
2189 | * bogus and it doesn't exist. | |
2190 | * | |
2191 | * Returns: | |
2192 | * -error: if there was an error during lookup. This includes -ENOENT if the | |
2193 | * lookup found a negative dentry. The nd->path reference will also be | |
2194 | * put in this case. | |
2195 | * | |
2196 | * 0: if we successfully resolved nd->path and found it to not to be a | |
2197 | * symlink that needs to be followed. "path" will also be populated. | |
2198 | * The nd->path reference will also be put. | |
2199 | * | |
2200 | * 1: if we successfully resolved nd->last and found it to be a symlink | |
2201 | * that needs to be followed. "path" will be populated with the path | |
2202 | * to the link, and nd->path will *not* be put. | |
2203 | */ | |
2204 | static int | |
197df04c | 2205 | mountpoint_last(struct nameidata *nd, struct path *path) |
8033426e JL |
2206 | { |
2207 | int error = 0; | |
2208 | struct dentry *dentry; | |
2209 | struct dentry *dir = nd->path.dentry; | |
2210 | ||
35759521 AV |
2211 | /* If we're in rcuwalk, drop out of it to handle last component */ |
2212 | if (nd->flags & LOOKUP_RCU) { | |
2213 | if (unlazy_walk(nd, NULL)) { | |
2214 | error = -ECHILD; | |
2215 | goto out; | |
2216 | } | |
8033426e JL |
2217 | } |
2218 | ||
2219 | nd->flags &= ~LOOKUP_PARENT; | |
2220 | ||
2221 | if (unlikely(nd->last_type != LAST_NORM)) { | |
2222 | error = handle_dots(nd, nd->last_type); | |
35759521 AV |
2223 | if (error) |
2224 | goto out; | |
2225 | dentry = dget(nd->path.dentry); | |
2226 | goto done; | |
8033426e JL |
2227 | } |
2228 | ||
2229 | mutex_lock(&dir->d_inode->i_mutex); | |
2230 | dentry = d_lookup(dir, &nd->last); | |
2231 | if (!dentry) { | |
2232 | /* | |
2233 | * No cached dentry. Mounted dentries are pinned in the cache, | |
2234 | * so that means that this dentry is probably a symlink or the | |
2235 | * path doesn't actually point to a mounted dentry. | |
2236 | */ | |
2237 | dentry = d_alloc(dir, &nd->last); | |
2238 | if (!dentry) { | |
2239 | error = -ENOMEM; | |
bcceeeba | 2240 | mutex_unlock(&dir->d_inode->i_mutex); |
35759521 | 2241 | goto out; |
8033426e | 2242 | } |
35759521 AV |
2243 | dentry = lookup_real(dir->d_inode, dentry, nd->flags); |
2244 | error = PTR_ERR(dentry); | |
bcceeeba DJ |
2245 | if (IS_ERR(dentry)) { |
2246 | mutex_unlock(&dir->d_inode->i_mutex); | |
35759521 | 2247 | goto out; |
bcceeeba | 2248 | } |
8033426e JL |
2249 | } |
2250 | mutex_unlock(&dir->d_inode->i_mutex); | |
2251 | ||
35759521 | 2252 | done: |
22213318 | 2253 | if (!dentry->d_inode || d_is_negative(dentry)) { |
35759521 AV |
2254 | error = -ENOENT; |
2255 | dput(dentry); | |
2256 | goto out; | |
8033426e | 2257 | } |
35759521 | 2258 | path->dentry = dentry; |
295dc39d | 2259 | path->mnt = nd->path.mnt; |
b18825a7 | 2260 | if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) |
35759521 | 2261 | return 1; |
295dc39d | 2262 | mntget(path->mnt); |
35759521 AV |
2263 | follow_mount(path); |
2264 | error = 0; | |
2265 | out: | |
8033426e JL |
2266 | terminate_walk(nd); |
2267 | return error; | |
2268 | } | |
2269 | ||
2270 | /** | |
197df04c | 2271 | * path_mountpoint - look up a path to be umounted |
8033426e JL |
2272 | * @dfd: directory file descriptor to start walk from |
2273 | * @name: full pathname to walk | |
606d6fe3 | 2274 | * @path: pointer to container for result |
8033426e | 2275 | * @flags: lookup flags |
8033426e JL |
2276 | * |
2277 | * Look up the given name, but don't attempt to revalidate the last component. | |
606d6fe3 | 2278 | * Returns 0 and "path" will be valid on success; Returns error otherwise. |
8033426e JL |
2279 | */ |
2280 | static int | |
197df04c | 2281 | path_mountpoint(int dfd, const char *name, struct path *path, unsigned int flags) |
8033426e JL |
2282 | { |
2283 | struct file *base = NULL; | |
2284 | struct nameidata nd; | |
2285 | int err; | |
2286 | ||
2287 | err = path_init(dfd, name, flags | LOOKUP_PARENT, &nd, &base); | |
2288 | if (unlikely(err)) | |
2289 | return err; | |
2290 | ||
2291 | current->total_link_count = 0; | |
2292 | err = link_path_walk(name, &nd); | |
2293 | if (err) | |
2294 | goto out; | |
2295 | ||
197df04c | 2296 | err = mountpoint_last(&nd, path); |
8033426e JL |
2297 | while (err > 0) { |
2298 | void *cookie; | |
2299 | struct path link = *path; | |
2300 | err = may_follow_link(&link, &nd); | |
2301 | if (unlikely(err)) | |
2302 | break; | |
2303 | nd.flags |= LOOKUP_PARENT; | |
2304 | err = follow_link(&link, &nd, &cookie); | |
2305 | if (err) | |
2306 | break; | |
197df04c | 2307 | err = mountpoint_last(&nd, path); |
8033426e JL |
2308 | put_link(&nd, &link, cookie); |
2309 | } | |
2310 | out: | |
2311 | if (base) | |
2312 | fput(base); | |
2313 | ||
2314 | if (nd.root.mnt && !(nd.flags & LOOKUP_ROOT)) | |
2315 | path_put(&nd.root); | |
2316 | ||
2317 | return err; | |
2318 | } | |
2319 | ||
2d864651 AV |
2320 | static int |
2321 | filename_mountpoint(int dfd, struct filename *s, struct path *path, | |
2322 | unsigned int flags) | |
2323 | { | |
2324 | int error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_RCU); | |
2325 | if (unlikely(error == -ECHILD)) | |
2326 | error = path_mountpoint(dfd, s->name, path, flags); | |
2327 | if (unlikely(error == -ESTALE)) | |
2328 | error = path_mountpoint(dfd, s->name, path, flags | LOOKUP_REVAL); | |
2329 | if (likely(!error)) | |
2330 | audit_inode(s, path->dentry, 0); | |
2331 | return error; | |
2332 | } | |
2333 | ||
8033426e | 2334 | /** |
197df04c | 2335 | * user_path_mountpoint_at - lookup a path from userland in order to umount it |
8033426e JL |
2336 | * @dfd: directory file descriptor |
2337 | * @name: pathname from userland | |
2338 | * @flags: lookup flags | |
2339 | * @path: pointer to container to hold result | |
2340 | * | |
2341 | * A umount is a special case for path walking. We're not actually interested | |
2342 | * in the inode in this situation, and ESTALE errors can be a problem. We | |
2343 | * simply want track down the dentry and vfsmount attached at the mountpoint | |
2344 | * and avoid revalidating the last component. | |
2345 | * | |
2346 | * Returns 0 and populates "path" on success. | |
2347 | */ | |
2348 | int | |
197df04c | 2349 | user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, |
8033426e JL |
2350 | struct path *path) |
2351 | { | |
2352 | struct filename *s = getname(name); | |
2353 | int error; | |
8033426e JL |
2354 | if (IS_ERR(s)) |
2355 | return PTR_ERR(s); | |
2d864651 | 2356 | error = filename_mountpoint(dfd, s, path, flags); |
8033426e JL |
2357 | putname(s); |
2358 | return error; | |
2359 | } | |
2360 | ||
2d864651 AV |
2361 | int |
2362 | kern_path_mountpoint(int dfd, const char *name, struct path *path, | |
2363 | unsigned int flags) | |
2364 | { | |
2365 | struct filename s = {.name = name}; | |
2366 | return filename_mountpoint(dfd, &s, path, flags); | |
2367 | } | |
2368 | EXPORT_SYMBOL(kern_path_mountpoint); | |
2369 | ||
1da177e4 LT |
2370 | /* |
2371 | * It's inline, so penalty for filesystems that don't use sticky bit is | |
2372 | * minimal. | |
2373 | */ | |
2374 | static inline int check_sticky(struct inode *dir, struct inode *inode) | |
2375 | { | |
8e96e3b7 | 2376 | kuid_t fsuid = current_fsuid(); |
da9592ed | 2377 | |
1da177e4 LT |
2378 | if (!(dir->i_mode & S_ISVTX)) |
2379 | return 0; | |
8e96e3b7 | 2380 | if (uid_eq(inode->i_uid, fsuid)) |
1da177e4 | 2381 | return 0; |
8e96e3b7 | 2382 | if (uid_eq(dir->i_uid, fsuid)) |
1da177e4 | 2383 | return 0; |
23adbe12 | 2384 | return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); |
1da177e4 LT |
2385 | } |
2386 | ||
2387 | /* | |
2388 | * Check whether we can remove a link victim from directory dir, check | |
2389 | * whether the type of victim is right. | |
2390 | * 1. We can't do it if dir is read-only (done in permission()) | |
2391 | * 2. We should have write and exec permissions on dir | |
2392 | * 3. We can't remove anything from append-only dir | |
2393 | * 4. We can't do anything with immutable dir (done in permission()) | |
2394 | * 5. If the sticky bit on dir is set we should either | |
2395 | * a. be owner of dir, or | |
2396 | * b. be owner of victim, or | |
2397 | * c. have CAP_FOWNER capability | |
2398 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
2399 | * links pointing to it. | |
2400 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
2401 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
2402 | * 9. We can't remove a root or mountpoint. | |
2403 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
2404 | * nfs_async_unlink(). | |
2405 | */ | |
b18825a7 | 2406 | static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) |
1da177e4 | 2407 | { |
b18825a7 | 2408 | struct inode *inode = victim->d_inode; |
1da177e4 LT |
2409 | int error; |
2410 | ||
b18825a7 | 2411 | if (d_is_negative(victim)) |
1da177e4 | 2412 | return -ENOENT; |
b18825a7 | 2413 | BUG_ON(!inode); |
1da177e4 LT |
2414 | |
2415 | BUG_ON(victim->d_parent->d_inode != dir); | |
4fa6b5ec | 2416 | audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); |
1da177e4 | 2417 | |
f419a2e3 | 2418 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2419 | if (error) |
2420 | return error; | |
2421 | if (IS_APPEND(dir)) | |
2422 | return -EPERM; | |
b18825a7 DH |
2423 | |
2424 | if (check_sticky(dir, inode) || IS_APPEND(inode) || | |
2425 | IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) | |
1da177e4 LT |
2426 | return -EPERM; |
2427 | if (isdir) { | |
44b1d530 | 2428 | if (!d_is_dir(victim)) |
1da177e4 LT |
2429 | return -ENOTDIR; |
2430 | if (IS_ROOT(victim)) | |
2431 | return -EBUSY; | |
44b1d530 | 2432 | } else if (d_is_dir(victim)) |
1da177e4 LT |
2433 | return -EISDIR; |
2434 | if (IS_DEADDIR(dir)) | |
2435 | return -ENOENT; | |
2436 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
2437 | return -EBUSY; | |
2438 | return 0; | |
2439 | } | |
2440 | ||
2441 | /* Check whether we can create an object with dentry child in directory | |
2442 | * dir. | |
2443 | * 1. We can't do it if child already exists (open has special treatment for | |
2444 | * this case, but since we are inlined it's OK) | |
2445 | * 2. We can't do it if dir is read-only (done in permission()) | |
2446 | * 3. We should have write and exec permissions on dir | |
2447 | * 4. We can't do it if dir is immutable (done in permission()) | |
2448 | */ | |
a95164d9 | 2449 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 | 2450 | { |
14e972b4 | 2451 | audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); |
1da177e4 LT |
2452 | if (child->d_inode) |
2453 | return -EEXIST; | |
2454 | if (IS_DEADDIR(dir)) | |
2455 | return -ENOENT; | |
f419a2e3 | 2456 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2457 | } |
2458 | ||
1da177e4 LT |
2459 | /* |
2460 | * p1 and p2 should be directories on the same fs. | |
2461 | */ | |
2462 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
2463 | { | |
2464 | struct dentry *p; | |
2465 | ||
2466 | if (p1 == p2) { | |
f2eace23 | 2467 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
2468 | return NULL; |
2469 | } | |
2470 | ||
a11f3a05 | 2471 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 | 2472 | |
e2761a11 OH |
2473 | p = d_ancestor(p2, p1); |
2474 | if (p) { | |
2475 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); | |
2476 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
2477 | return p; | |
1da177e4 LT |
2478 | } |
2479 | ||
e2761a11 OH |
2480 | p = d_ancestor(p1, p2); |
2481 | if (p) { | |
2482 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); | |
2483 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
2484 | return p; | |
1da177e4 LT |
2485 | } |
2486 | ||
f2eace23 IM |
2487 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
2488 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
1da177e4 LT |
2489 | return NULL; |
2490 | } | |
4d359507 | 2491 | EXPORT_SYMBOL(lock_rename); |
1da177e4 LT |
2492 | |
2493 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
2494 | { | |
1b1dcc1b | 2495 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 2496 | if (p1 != p2) { |
1b1dcc1b | 2497 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 2498 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
2499 | } |
2500 | } | |
4d359507 | 2501 | EXPORT_SYMBOL(unlock_rename); |
1da177e4 | 2502 | |
4acdaf27 | 2503 | int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
312b63fb | 2504 | bool want_excl) |
1da177e4 | 2505 | { |
a95164d9 | 2506 | int error = may_create(dir, dentry); |
1da177e4 LT |
2507 | if (error) |
2508 | return error; | |
2509 | ||
acfa4380 | 2510 | if (!dir->i_op->create) |
1da177e4 LT |
2511 | return -EACCES; /* shouldn't it be ENOSYS? */ |
2512 | mode &= S_IALLUGO; | |
2513 | mode |= S_IFREG; | |
2514 | error = security_inode_create(dir, dentry, mode); | |
2515 | if (error) | |
2516 | return error; | |
312b63fb | 2517 | error = dir->i_op->create(dir, dentry, mode, want_excl); |
a74574aa | 2518 | if (!error) |
f38aa942 | 2519 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2520 | return error; |
2521 | } | |
4d359507 | 2522 | EXPORT_SYMBOL(vfs_create); |
1da177e4 | 2523 | |
73d049a4 | 2524 | static int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 2525 | { |
3fb64190 | 2526 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
2527 | struct inode *inode = dentry->d_inode; |
2528 | int error; | |
2529 | ||
bcda7652 AV |
2530 | /* O_PATH? */ |
2531 | if (!acc_mode) | |
2532 | return 0; | |
2533 | ||
1da177e4 LT |
2534 | if (!inode) |
2535 | return -ENOENT; | |
2536 | ||
c8fe8f30 CH |
2537 | switch (inode->i_mode & S_IFMT) { |
2538 | case S_IFLNK: | |
1da177e4 | 2539 | return -ELOOP; |
c8fe8f30 CH |
2540 | case S_IFDIR: |
2541 | if (acc_mode & MAY_WRITE) | |
2542 | return -EISDIR; | |
2543 | break; | |
2544 | case S_IFBLK: | |
2545 | case S_IFCHR: | |
3fb64190 | 2546 | if (path->mnt->mnt_flags & MNT_NODEV) |
1da177e4 | 2547 | return -EACCES; |
c8fe8f30 CH |
2548 | /*FALLTHRU*/ |
2549 | case S_IFIFO: | |
2550 | case S_IFSOCK: | |
1da177e4 | 2551 | flag &= ~O_TRUNC; |
c8fe8f30 | 2552 | break; |
4a3fd211 | 2553 | } |
b41572e9 | 2554 | |
3fb64190 | 2555 | error = inode_permission(inode, acc_mode); |
b41572e9 DH |
2556 | if (error) |
2557 | return error; | |
6146f0d5 | 2558 | |
1da177e4 LT |
2559 | /* |
2560 | * An append-only file must be opened in append mode for writing. | |
2561 | */ | |
2562 | if (IS_APPEND(inode)) { | |
8737c930 | 2563 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
7715b521 | 2564 | return -EPERM; |
1da177e4 | 2565 | if (flag & O_TRUNC) |
7715b521 | 2566 | return -EPERM; |
1da177e4 LT |
2567 | } |
2568 | ||
2569 | /* O_NOATIME can only be set by the owner or superuser */ | |
2e149670 | 2570 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
7715b521 | 2571 | return -EPERM; |
1da177e4 | 2572 | |
f3c7691e | 2573 | return 0; |
7715b521 | 2574 | } |
1da177e4 | 2575 | |
e1181ee6 | 2576 | static int handle_truncate(struct file *filp) |
7715b521 | 2577 | { |
e1181ee6 | 2578 | struct path *path = &filp->f_path; |
7715b521 AV |
2579 | struct inode *inode = path->dentry->d_inode; |
2580 | int error = get_write_access(inode); | |
2581 | if (error) | |
2582 | return error; | |
2583 | /* | |
2584 | * Refuse to truncate files with mandatory locks held on them. | |
2585 | */ | |
d7a06983 | 2586 | error = locks_verify_locked(filp); |
7715b521 | 2587 | if (!error) |
ea0d3ab2 | 2588 | error = security_path_truncate(path); |
7715b521 AV |
2589 | if (!error) { |
2590 | error = do_truncate(path->dentry, 0, | |
2591 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
e1181ee6 | 2592 | filp); |
7715b521 AV |
2593 | } |
2594 | put_write_access(inode); | |
acd0c935 | 2595 | return error; |
1da177e4 LT |
2596 | } |
2597 | ||
d57999e1 DH |
2598 | static inline int open_to_namei_flags(int flag) |
2599 | { | |
8a5e929d AV |
2600 | if ((flag & O_ACCMODE) == 3) |
2601 | flag--; | |
d57999e1 DH |
2602 | return flag; |
2603 | } | |
2604 | ||
d18e9008 MS |
2605 | static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) |
2606 | { | |
2607 | int error = security_path_mknod(dir, dentry, mode, 0); | |
2608 | if (error) | |
2609 | return error; | |
2610 | ||
2611 | error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); | |
2612 | if (error) | |
2613 | return error; | |
2614 | ||
2615 | return security_inode_create(dir->dentry->d_inode, dentry, mode); | |
2616 | } | |
2617 | ||
1acf0af9 DH |
2618 | /* |
2619 | * Attempt to atomically look up, create and open a file from a negative | |
2620 | * dentry. | |
2621 | * | |
2622 | * Returns 0 if successful. The file will have been created and attached to | |
2623 | * @file by the filesystem calling finish_open(). | |
2624 | * | |
2625 | * Returns 1 if the file was looked up only or didn't need creating. The | |
2626 | * caller will need to perform the open themselves. @path will have been | |
2627 | * updated to point to the new dentry. This may be negative. | |
2628 | * | |
2629 | * Returns an error code otherwise. | |
2630 | */ | |
2675a4eb AV |
2631 | static int atomic_open(struct nameidata *nd, struct dentry *dentry, |
2632 | struct path *path, struct file *file, | |
2633 | const struct open_flags *op, | |
64894cf8 | 2634 | bool got_write, bool need_lookup, |
2675a4eb | 2635 | int *opened) |
d18e9008 MS |
2636 | { |
2637 | struct inode *dir = nd->path.dentry->d_inode; | |
2638 | unsigned open_flag = open_to_namei_flags(op->open_flag); | |
2639 | umode_t mode; | |
2640 | int error; | |
2641 | int acc_mode; | |
d18e9008 MS |
2642 | int create_error = 0; |
2643 | struct dentry *const DENTRY_NOT_SET = (void *) -1UL; | |
116cc022 | 2644 | bool excl; |
d18e9008 MS |
2645 | |
2646 | BUG_ON(dentry->d_inode); | |
2647 | ||
2648 | /* Don't create child dentry for a dead directory. */ | |
2649 | if (unlikely(IS_DEADDIR(dir))) { | |
2675a4eb | 2650 | error = -ENOENT; |
d18e9008 MS |
2651 | goto out; |
2652 | } | |
2653 | ||
62b259d8 | 2654 | mode = op->mode; |
d18e9008 MS |
2655 | if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) |
2656 | mode &= ~current_umask(); | |
2657 | ||
116cc022 MS |
2658 | excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); |
2659 | if (excl) | |
d18e9008 | 2660 | open_flag &= ~O_TRUNC; |
d18e9008 MS |
2661 | |
2662 | /* | |
2663 | * Checking write permission is tricky, bacuse we don't know if we are | |
2664 | * going to actually need it: O_CREAT opens should work as long as the | |
2665 | * file exists. But checking existence breaks atomicity. The trick is | |
2666 | * to check access and if not granted clear O_CREAT from the flags. | |
2667 | * | |
2668 | * Another problem is returing the "right" error value (e.g. for an | |
2669 | * O_EXCL open we want to return EEXIST not EROFS). | |
2670 | */ | |
64894cf8 AV |
2671 | if (((open_flag & (O_CREAT | O_TRUNC)) || |
2672 | (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { | |
2673 | if (!(open_flag & O_CREAT)) { | |
d18e9008 MS |
2674 | /* |
2675 | * No O_CREATE -> atomicity not a requirement -> fall | |
2676 | * back to lookup + open | |
2677 | */ | |
2678 | goto no_open; | |
2679 | } else if (open_flag & (O_EXCL | O_TRUNC)) { | |
2680 | /* Fall back and fail with the right error */ | |
64894cf8 | 2681 | create_error = -EROFS; |
d18e9008 MS |
2682 | goto no_open; |
2683 | } else { | |
2684 | /* No side effects, safe to clear O_CREAT */ | |
64894cf8 | 2685 | create_error = -EROFS; |
d18e9008 MS |
2686 | open_flag &= ~O_CREAT; |
2687 | } | |
2688 | } | |
2689 | ||
2690 | if (open_flag & O_CREAT) { | |
38227f78 | 2691 | error = may_o_create(&nd->path, dentry, mode); |
d18e9008 MS |
2692 | if (error) { |
2693 | create_error = error; | |
2694 | if (open_flag & O_EXCL) | |
2695 | goto no_open; | |
2696 | open_flag &= ~O_CREAT; | |
2697 | } | |
2698 | } | |
2699 | ||
2700 | if (nd->flags & LOOKUP_DIRECTORY) | |
2701 | open_flag |= O_DIRECTORY; | |
2702 | ||
30d90494 AV |
2703 | file->f_path.dentry = DENTRY_NOT_SET; |
2704 | file->f_path.mnt = nd->path.mnt; | |
2705 | error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, | |
47237687 | 2706 | opened); |
d9585277 | 2707 | if (error < 0) { |
d9585277 AV |
2708 | if (create_error && error == -ENOENT) |
2709 | error = create_error; | |
d18e9008 MS |
2710 | goto out; |
2711 | } | |
2712 | ||
d9585277 | 2713 | if (error) { /* returned 1, that is */ |
30d90494 | 2714 | if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { |
2675a4eb | 2715 | error = -EIO; |
d18e9008 MS |
2716 | goto out; |
2717 | } | |
30d90494 | 2718 | if (file->f_path.dentry) { |
d18e9008 | 2719 | dput(dentry); |
30d90494 | 2720 | dentry = file->f_path.dentry; |
d18e9008 | 2721 | } |
03da633a AV |
2722 | if (*opened & FILE_CREATED) |
2723 | fsnotify_create(dir, dentry); | |
2724 | if (!dentry->d_inode) { | |
2725 | WARN_ON(*opened & FILE_CREATED); | |
2726 | if (create_error) { | |
2727 | error = create_error; | |
2728 | goto out; | |
2729 | } | |
2730 | } else { | |
2731 | if (excl && !(*opened & FILE_CREATED)) { | |
2732 | error = -EEXIST; | |
2733 | goto out; | |
2734 | } | |
62b2ce96 | 2735 | } |
d18e9008 MS |
2736 | goto looked_up; |
2737 | } | |
2738 | ||
2739 | /* | |
2740 | * We didn't have the inode before the open, so check open permission | |
2741 | * here. | |
2742 | */ | |
03da633a AV |
2743 | acc_mode = op->acc_mode; |
2744 | if (*opened & FILE_CREATED) { | |
2745 | WARN_ON(!(open_flag & O_CREAT)); | |
2746 | fsnotify_create(dir, dentry); | |
2747 | acc_mode = MAY_OPEN; | |
2748 | } | |
2675a4eb AV |
2749 | error = may_open(&file->f_path, acc_mode, open_flag); |
2750 | if (error) | |
2751 | fput(file); | |
d18e9008 MS |
2752 | |
2753 | out: | |
2754 | dput(dentry); | |
2675a4eb | 2755 | return error; |
d18e9008 | 2756 | |
d18e9008 MS |
2757 | no_open: |
2758 | if (need_lookup) { | |
72bd866a | 2759 | dentry = lookup_real(dir, dentry, nd->flags); |
d18e9008 | 2760 | if (IS_ERR(dentry)) |
2675a4eb | 2761 | return PTR_ERR(dentry); |
d18e9008 MS |
2762 | |
2763 | if (create_error) { | |
2764 | int open_flag = op->open_flag; | |
2765 | ||
2675a4eb | 2766 | error = create_error; |
d18e9008 MS |
2767 | if ((open_flag & O_EXCL)) { |
2768 | if (!dentry->d_inode) | |
2769 | goto out; | |
2770 | } else if (!dentry->d_inode) { | |
2771 | goto out; | |
2772 | } else if ((open_flag & O_TRUNC) && | |
2773 | S_ISREG(dentry->d_inode->i_mode)) { | |
2774 | goto out; | |
2775 | } | |
2776 | /* will fail later, go on to get the right error */ | |
2777 | } | |
2778 | } | |
2779 | looked_up: | |
2780 | path->dentry = dentry; | |
2781 | path->mnt = nd->path.mnt; | |
2675a4eb | 2782 | return 1; |
d18e9008 MS |
2783 | } |
2784 | ||
d58ffd35 | 2785 | /* |
1acf0af9 | 2786 | * Look up and maybe create and open the last component. |
d58ffd35 MS |
2787 | * |
2788 | * Must be called with i_mutex held on parent. | |
2789 | * | |
1acf0af9 DH |
2790 | * Returns 0 if the file was successfully atomically created (if necessary) and |
2791 | * opened. In this case the file will be returned attached to @file. | |
2792 | * | |
2793 | * Returns 1 if the file was not completely opened at this time, though lookups | |
2794 | * and creations will have been performed and the dentry returned in @path will | |
2795 | * be positive upon return if O_CREAT was specified. If O_CREAT wasn't | |
2796 | * specified then a negative dentry may be returned. | |
2797 | * | |
2798 | * An error code is returned otherwise. | |
2799 | * | |
2800 | * FILE_CREATE will be set in @*opened if the dentry was created and will be | |
2801 | * cleared otherwise prior to returning. | |
d58ffd35 | 2802 | */ |
2675a4eb AV |
2803 | static int lookup_open(struct nameidata *nd, struct path *path, |
2804 | struct file *file, | |
2805 | const struct open_flags *op, | |
64894cf8 | 2806 | bool got_write, int *opened) |
d58ffd35 MS |
2807 | { |
2808 | struct dentry *dir = nd->path.dentry; | |
54ef4872 | 2809 | struct inode *dir_inode = dir->d_inode; |
d58ffd35 MS |
2810 | struct dentry *dentry; |
2811 | int error; | |
54ef4872 | 2812 | bool need_lookup; |
d58ffd35 | 2813 | |
47237687 | 2814 | *opened &= ~FILE_CREATED; |
201f956e | 2815 | dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); |
d58ffd35 | 2816 | if (IS_ERR(dentry)) |
2675a4eb | 2817 | return PTR_ERR(dentry); |
d58ffd35 | 2818 | |
d18e9008 MS |
2819 | /* Cached positive dentry: will open in f_op->open */ |
2820 | if (!need_lookup && dentry->d_inode) | |
2821 | goto out_no_open; | |
2822 | ||
2823 | if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { | |
64894cf8 | 2824 | return atomic_open(nd, dentry, path, file, op, got_write, |
47237687 | 2825 | need_lookup, opened); |
d18e9008 MS |
2826 | } |
2827 | ||
54ef4872 MS |
2828 | if (need_lookup) { |
2829 | BUG_ON(dentry->d_inode); | |
2830 | ||
72bd866a | 2831 | dentry = lookup_real(dir_inode, dentry, nd->flags); |
54ef4872 | 2832 | if (IS_ERR(dentry)) |
2675a4eb | 2833 | return PTR_ERR(dentry); |
54ef4872 MS |
2834 | } |
2835 | ||
d58ffd35 MS |
2836 | /* Negative dentry, just create the file */ |
2837 | if (!dentry->d_inode && (op->open_flag & O_CREAT)) { | |
2838 | umode_t mode = op->mode; | |
2839 | if (!IS_POSIXACL(dir->d_inode)) | |
2840 | mode &= ~current_umask(); | |
2841 | /* | |
2842 | * This write is needed to ensure that a | |
2843 | * rw->ro transition does not occur between | |
2844 | * the time when the file is created and when | |
2845 | * a permanent write count is taken through | |
015c3bbc | 2846 | * the 'struct file' in finish_open(). |
d58ffd35 | 2847 | */ |
64894cf8 AV |
2848 | if (!got_write) { |
2849 | error = -EROFS; | |
d58ffd35 | 2850 | goto out_dput; |
64894cf8 | 2851 | } |
47237687 | 2852 | *opened |= FILE_CREATED; |
d58ffd35 MS |
2853 | error = security_path_mknod(&nd->path, dentry, mode, 0); |
2854 | if (error) | |
2855 | goto out_dput; | |
312b63fb AV |
2856 | error = vfs_create(dir->d_inode, dentry, mode, |
2857 | nd->flags & LOOKUP_EXCL); | |
d58ffd35 MS |
2858 | if (error) |
2859 | goto out_dput; | |
2860 | } | |
d18e9008 | 2861 | out_no_open: |
d58ffd35 MS |
2862 | path->dentry = dentry; |
2863 | path->mnt = nd->path.mnt; | |
2675a4eb | 2864 | return 1; |
d58ffd35 MS |
2865 | |
2866 | out_dput: | |
2867 | dput(dentry); | |
2675a4eb | 2868 | return error; |
d58ffd35 MS |
2869 | } |
2870 | ||
31e6b01f | 2871 | /* |
fe2d35ff | 2872 | * Handle the last step of open() |
31e6b01f | 2873 | */ |
2675a4eb AV |
2874 | static int do_last(struct nameidata *nd, struct path *path, |
2875 | struct file *file, const struct open_flags *op, | |
669abf4e | 2876 | int *opened, struct filename *name) |
fb1cc555 | 2877 | { |
a1e28038 | 2878 | struct dentry *dir = nd->path.dentry; |
ca344a89 | 2879 | int open_flag = op->open_flag; |
77d660a8 | 2880 | bool will_truncate = (open_flag & O_TRUNC) != 0; |
64894cf8 | 2881 | bool got_write = false; |
bcda7652 | 2882 | int acc_mode = op->acc_mode; |
a1eb3315 | 2883 | struct inode *inode; |
77d660a8 | 2884 | bool symlink_ok = false; |
16b1c1cd MS |
2885 | struct path save_parent = { .dentry = NULL, .mnt = NULL }; |
2886 | bool retried = false; | |
16c2cd71 | 2887 | int error; |
1f36f774 | 2888 | |
c3e380b0 AV |
2889 | nd->flags &= ~LOOKUP_PARENT; |
2890 | nd->flags |= op->intent; | |
2891 | ||
bc77daa7 | 2892 | if (nd->last_type != LAST_NORM) { |
fe2d35ff AV |
2893 | error = handle_dots(nd, nd->last_type); |
2894 | if (error) | |
2675a4eb | 2895 | return error; |
e83db167 | 2896 | goto finish_open; |
1f36f774 | 2897 | } |
67ee3ad2 | 2898 | |
ca344a89 | 2899 | if (!(open_flag & O_CREAT)) { |
fe2d35ff AV |
2900 | if (nd->last.name[nd->last.len]) |
2901 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
bcda7652 | 2902 | if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) |
77d660a8 | 2903 | symlink_ok = true; |
fe2d35ff | 2904 | /* we _can_ be in RCU mode here */ |
e97cdc87 | 2905 | error = lookup_fast(nd, path, &inode); |
71574865 MS |
2906 | if (likely(!error)) |
2907 | goto finish_lookup; | |
2908 | ||
2909 | if (error < 0) | |
2675a4eb | 2910 | goto out; |
71574865 MS |
2911 | |
2912 | BUG_ON(nd->inode != dir->d_inode); | |
b6183df7 MS |
2913 | } else { |
2914 | /* create side of things */ | |
2915 | /* | |
2916 | * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED | |
2917 | * has been cleared when we got to the last component we are | |
2918 | * about to look up | |
2919 | */ | |
2920 | error = complete_walk(nd); | |
2921 | if (error) | |
2675a4eb | 2922 | return error; |
fe2d35ff | 2923 | |
33e2208a | 2924 | audit_inode(name, dir, LOOKUP_PARENT); |
b6183df7 MS |
2925 | error = -EISDIR; |
2926 | /* trailing slashes? */ | |
2927 | if (nd->last.name[nd->last.len]) | |
2675a4eb | 2928 | goto out; |
b6183df7 | 2929 | } |
a2c36b45 | 2930 | |
16b1c1cd | 2931 | retry_lookup: |
64894cf8 AV |
2932 | if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { |
2933 | error = mnt_want_write(nd->path.mnt); | |
2934 | if (!error) | |
2935 | got_write = true; | |
2936 | /* | |
2937 | * do _not_ fail yet - we might not need that or fail with | |
2938 | * a different error; let lookup_open() decide; we'll be | |
2939 | * dropping this one anyway. | |
2940 | */ | |
2941 | } | |
a1e28038 | 2942 | mutex_lock(&dir->d_inode->i_mutex); |
64894cf8 | 2943 | error = lookup_open(nd, path, file, op, got_write, opened); |
d58ffd35 | 2944 | mutex_unlock(&dir->d_inode->i_mutex); |
a1e28038 | 2945 | |
2675a4eb AV |
2946 | if (error <= 0) { |
2947 | if (error) | |
d18e9008 MS |
2948 | goto out; |
2949 | ||
47237687 | 2950 | if ((*opened & FILE_CREATED) || |
496ad9aa | 2951 | !S_ISREG(file_inode(file)->i_mode)) |
77d660a8 | 2952 | will_truncate = false; |
d18e9008 | 2953 | |
adb5c247 | 2954 | audit_inode(name, file->f_path.dentry, 0); |
d18e9008 MS |
2955 | goto opened; |
2956 | } | |
fb1cc555 | 2957 | |
47237687 | 2958 | if (*opened & FILE_CREATED) { |
9b44f1b3 | 2959 | /* Don't check for write permission, don't truncate */ |
ca344a89 | 2960 | open_flag &= ~O_TRUNC; |
77d660a8 | 2961 | will_truncate = false; |
bcda7652 | 2962 | acc_mode = MAY_OPEN; |
d58ffd35 | 2963 | path_to_nameidata(path, nd); |
e83db167 | 2964 | goto finish_open_created; |
fb1cc555 AV |
2965 | } |
2966 | ||
2967 | /* | |
3134f37e | 2968 | * create/update audit record if it already exists. |
fb1cc555 | 2969 | */ |
b18825a7 | 2970 | if (d_is_positive(path->dentry)) |
adb5c247 | 2971 | audit_inode(name, path->dentry, 0); |
fb1cc555 | 2972 | |
d18e9008 MS |
2973 | /* |
2974 | * If atomic_open() acquired write access it is dropped now due to | |
2975 | * possible mount and symlink following (this might be optimized away if | |
2976 | * necessary...) | |
2977 | */ | |
64894cf8 | 2978 | if (got_write) { |
d18e9008 | 2979 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 2980 | got_write = false; |
d18e9008 MS |
2981 | } |
2982 | ||
fb1cc555 | 2983 | error = -EEXIST; |
f8310c59 | 2984 | if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) |
fb1cc555 AV |
2985 | goto exit_dput; |
2986 | ||
9875cf80 DH |
2987 | error = follow_managed(path, nd->flags); |
2988 | if (error < 0) | |
2989 | goto exit_dput; | |
fb1cc555 | 2990 | |
a3fbbde7 AV |
2991 | if (error) |
2992 | nd->flags |= LOOKUP_JUMPED; | |
2993 | ||
decf3400 MS |
2994 | BUG_ON(nd->flags & LOOKUP_RCU); |
2995 | inode = path->dentry->d_inode; | |
5f5daac1 MS |
2996 | finish_lookup: |
2997 | /* we _can_ be in RCU mode here */ | |
fb1cc555 | 2998 | error = -ENOENT; |
22213318 | 2999 | if (!inode || d_is_negative(path->dentry)) { |
54c33e7f | 3000 | path_to_nameidata(path, nd); |
2675a4eb | 3001 | goto out; |
54c33e7f | 3002 | } |
9e67f361 | 3003 | |
b18825a7 | 3004 | if (should_follow_link(path->dentry, !symlink_ok)) { |
d45ea867 MS |
3005 | if (nd->flags & LOOKUP_RCU) { |
3006 | if (unlikely(unlazy_walk(nd, path->dentry))) { | |
3007 | error = -ECHILD; | |
2675a4eb | 3008 | goto out; |
d45ea867 MS |
3009 | } |
3010 | } | |
3011 | BUG_ON(inode != path->dentry->d_inode); | |
2675a4eb | 3012 | return 1; |
d45ea867 | 3013 | } |
fb1cc555 | 3014 | |
16b1c1cd MS |
3015 | if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { |
3016 | path_to_nameidata(path, nd); | |
3017 | } else { | |
3018 | save_parent.dentry = nd->path.dentry; | |
3019 | save_parent.mnt = mntget(path->mnt); | |
3020 | nd->path.dentry = path->dentry; | |
3021 | ||
3022 | } | |
decf3400 | 3023 | nd->inode = inode; |
a3fbbde7 | 3024 | /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ |
bc77daa7 | 3025 | finish_open: |
a3fbbde7 | 3026 | error = complete_walk(nd); |
16b1c1cd MS |
3027 | if (error) { |
3028 | path_put(&save_parent); | |
2675a4eb | 3029 | return error; |
16b1c1cd | 3030 | } |
bc77daa7 | 3031 | audit_inode(name, nd->path.dentry, 0); |
fb1cc555 | 3032 | error = -EISDIR; |
44b1d530 | 3033 | if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) |
2675a4eb | 3034 | goto out; |
af2f5542 | 3035 | error = -ENOTDIR; |
44b1d530 | 3036 | if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) |
2675a4eb | 3037 | goto out; |
6c0d46c4 | 3038 | if (!S_ISREG(nd->inode->i_mode)) |
77d660a8 | 3039 | will_truncate = false; |
6c0d46c4 | 3040 | |
0f9d1a10 AV |
3041 | if (will_truncate) { |
3042 | error = mnt_want_write(nd->path.mnt); | |
3043 | if (error) | |
2675a4eb | 3044 | goto out; |
64894cf8 | 3045 | got_write = true; |
0f9d1a10 | 3046 | } |
e83db167 | 3047 | finish_open_created: |
bcda7652 | 3048 | error = may_open(&nd->path, acc_mode, open_flag); |
ca344a89 | 3049 | if (error) |
2675a4eb | 3050 | goto out; |
30d90494 AV |
3051 | file->f_path.mnt = nd->path.mnt; |
3052 | error = finish_open(file, nd->path.dentry, NULL, opened); | |
3053 | if (error) { | |
30d90494 | 3054 | if (error == -EOPENSTALE) |
f60dc3db | 3055 | goto stale_open; |
015c3bbc | 3056 | goto out; |
f60dc3db | 3057 | } |
a8277b9b | 3058 | opened: |
2675a4eb | 3059 | error = open_check_o_direct(file); |
015c3bbc MS |
3060 | if (error) |
3061 | goto exit_fput; | |
2675a4eb | 3062 | error = ima_file_check(file, op->acc_mode); |
aa4caadb MS |
3063 | if (error) |
3064 | goto exit_fput; | |
3065 | ||
3066 | if (will_truncate) { | |
2675a4eb | 3067 | error = handle_truncate(file); |
aa4caadb MS |
3068 | if (error) |
3069 | goto exit_fput; | |
0f9d1a10 | 3070 | } |
ca344a89 | 3071 | out: |
64894cf8 | 3072 | if (got_write) |
0f9d1a10 | 3073 | mnt_drop_write(nd->path.mnt); |
16b1c1cd | 3074 | path_put(&save_parent); |
e276ae67 | 3075 | terminate_walk(nd); |
2675a4eb | 3076 | return error; |
fb1cc555 | 3077 | |
fb1cc555 AV |
3078 | exit_dput: |
3079 | path_put_conditional(path, nd); | |
ca344a89 | 3080 | goto out; |
015c3bbc | 3081 | exit_fput: |
2675a4eb AV |
3082 | fput(file); |
3083 | goto out; | |
015c3bbc | 3084 | |
f60dc3db MS |
3085 | stale_open: |
3086 | /* If no saved parent or already retried then can't retry */ | |
3087 | if (!save_parent.dentry || retried) | |
3088 | goto out; | |
3089 | ||
3090 | BUG_ON(save_parent.dentry != dir); | |
3091 | path_put(&nd->path); | |
3092 | nd->path = save_parent; | |
3093 | nd->inode = dir->d_inode; | |
3094 | save_parent.mnt = NULL; | |
3095 | save_parent.dentry = NULL; | |
64894cf8 | 3096 | if (got_write) { |
f60dc3db | 3097 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 3098 | got_write = false; |
f60dc3db MS |
3099 | } |
3100 | retried = true; | |
3101 | goto retry_lookup; | |
fb1cc555 AV |
3102 | } |
3103 | ||
60545d0d AV |
3104 | static int do_tmpfile(int dfd, struct filename *pathname, |
3105 | struct nameidata *nd, int flags, | |
3106 | const struct open_flags *op, | |
3107 | struct file *file, int *opened) | |
3108 | { | |
3109 | static const struct qstr name = QSTR_INIT("/", 1); | |
3110 | struct dentry *dentry, *child; | |
3111 | struct inode *dir; | |
3112 | int error = path_lookupat(dfd, pathname->name, | |
3113 | flags | LOOKUP_DIRECTORY, nd); | |
3114 | if (unlikely(error)) | |
3115 | return error; | |
3116 | error = mnt_want_write(nd->path.mnt); | |
3117 | if (unlikely(error)) | |
3118 | goto out; | |
3119 | /* we want directory to be writable */ | |
3120 | error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); | |
3121 | if (error) | |
3122 | goto out2; | |
3123 | dentry = nd->path.dentry; | |
3124 | dir = dentry->d_inode; | |
3125 | if (!dir->i_op->tmpfile) { | |
3126 | error = -EOPNOTSUPP; | |
3127 | goto out2; | |
3128 | } | |
3129 | child = d_alloc(dentry, &name); | |
3130 | if (unlikely(!child)) { | |
3131 | error = -ENOMEM; | |
3132 | goto out2; | |
3133 | } | |
3134 | nd->flags &= ~LOOKUP_DIRECTORY; | |
3135 | nd->flags |= op->intent; | |
3136 | dput(nd->path.dentry); | |
3137 | nd->path.dentry = child; | |
3138 | error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); | |
3139 | if (error) | |
3140 | goto out2; | |
3141 | audit_inode(pathname, nd->path.dentry, 0); | |
3142 | error = may_open(&nd->path, op->acc_mode, op->open_flag); | |
3143 | if (error) | |
3144 | goto out2; | |
3145 | file->f_path.mnt = nd->path.mnt; | |
3146 | error = finish_open(file, nd->path.dentry, NULL, opened); | |
3147 | if (error) | |
3148 | goto out2; | |
3149 | error = open_check_o_direct(file); | |
f4e0c30c | 3150 | if (error) { |
60545d0d | 3151 | fput(file); |
f4e0c30c AV |
3152 | } else if (!(op->open_flag & O_EXCL)) { |
3153 | struct inode *inode = file_inode(file); | |
3154 | spin_lock(&inode->i_lock); | |
3155 | inode->i_state |= I_LINKABLE; | |
3156 | spin_unlock(&inode->i_lock); | |
3157 | } | |
60545d0d AV |
3158 | out2: |
3159 | mnt_drop_write(nd->path.mnt); | |
3160 | out: | |
3161 | path_put(&nd->path); | |
3162 | return error; | |
3163 | } | |
3164 | ||
669abf4e | 3165 | static struct file *path_openat(int dfd, struct filename *pathname, |
73d049a4 | 3166 | struct nameidata *nd, const struct open_flags *op, int flags) |
1da177e4 | 3167 | { |
fe2d35ff | 3168 | struct file *base = NULL; |
30d90494 | 3169 | struct file *file; |
9850c056 | 3170 | struct path path; |
47237687 | 3171 | int opened = 0; |
13aab428 | 3172 | int error; |
31e6b01f | 3173 | |
30d90494 | 3174 | file = get_empty_filp(); |
1afc99be AV |
3175 | if (IS_ERR(file)) |
3176 | return file; | |
31e6b01f | 3177 | |
30d90494 | 3178 | file->f_flags = op->open_flag; |
31e6b01f | 3179 | |
bb458c64 | 3180 | if (unlikely(file->f_flags & __O_TMPFILE)) { |
60545d0d AV |
3181 | error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); |
3182 | goto out; | |
3183 | } | |
3184 | ||
669abf4e | 3185 | error = path_init(dfd, pathname->name, flags | LOOKUP_PARENT, nd, &base); |
31e6b01f | 3186 | if (unlikely(error)) |
2675a4eb | 3187 | goto out; |
31e6b01f | 3188 | |
fe2d35ff | 3189 | current->total_link_count = 0; |
669abf4e | 3190 | error = link_path_walk(pathname->name, nd); |
31e6b01f | 3191 | if (unlikely(error)) |
2675a4eb | 3192 | goto out; |
1da177e4 | 3193 | |
2675a4eb AV |
3194 | error = do_last(nd, &path, file, op, &opened, pathname); |
3195 | while (unlikely(error > 0)) { /* trailing symlink */ | |
7b9337aa | 3196 | struct path link = path; |
def4af30 | 3197 | void *cookie; |
574197e0 | 3198 | if (!(nd->flags & LOOKUP_FOLLOW)) { |
73d049a4 AV |
3199 | path_put_conditional(&path, nd); |
3200 | path_put(&nd->path); | |
2675a4eb | 3201 | error = -ELOOP; |
40b39136 AV |
3202 | break; |
3203 | } | |
800179c9 KC |
3204 | error = may_follow_link(&link, nd); |
3205 | if (unlikely(error)) | |
3206 | break; | |
73d049a4 AV |
3207 | nd->flags |= LOOKUP_PARENT; |
3208 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); | |
574197e0 | 3209 | error = follow_link(&link, nd, &cookie); |
c3e380b0 | 3210 | if (unlikely(error)) |
2675a4eb AV |
3211 | break; |
3212 | error = do_last(nd, &path, file, op, &opened, pathname); | |
574197e0 | 3213 | put_link(nd, &link, cookie); |
806b681c | 3214 | } |
10fa8e62 | 3215 | out: |
73d049a4 AV |
3216 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) |
3217 | path_put(&nd->root); | |
fe2d35ff AV |
3218 | if (base) |
3219 | fput(base); | |
2675a4eb AV |
3220 | if (!(opened & FILE_OPENED)) { |
3221 | BUG_ON(!error); | |
30d90494 | 3222 | put_filp(file); |
16b1c1cd | 3223 | } |
2675a4eb AV |
3224 | if (unlikely(error)) { |
3225 | if (error == -EOPENSTALE) { | |
3226 | if (flags & LOOKUP_RCU) | |
3227 | error = -ECHILD; | |
3228 | else | |
3229 | error = -ESTALE; | |
3230 | } | |
3231 | file = ERR_PTR(error); | |
3232 | } | |
3233 | return file; | |
1da177e4 LT |
3234 | } |
3235 | ||
669abf4e | 3236 | struct file *do_filp_open(int dfd, struct filename *pathname, |
f9652e10 | 3237 | const struct open_flags *op) |
13aab428 | 3238 | { |
73d049a4 | 3239 | struct nameidata nd; |
f9652e10 | 3240 | int flags = op->lookup_flags; |
13aab428 AV |
3241 | struct file *filp; |
3242 | ||
73d049a4 | 3243 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); |
13aab428 | 3244 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
73d049a4 | 3245 | filp = path_openat(dfd, pathname, &nd, op, flags); |
13aab428 | 3246 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
73d049a4 | 3247 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); |
13aab428 AV |
3248 | return filp; |
3249 | } | |
3250 | ||
73d049a4 | 3251 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
f9652e10 | 3252 | const char *name, const struct open_flags *op) |
73d049a4 AV |
3253 | { |
3254 | struct nameidata nd; | |
3255 | struct file *file; | |
669abf4e | 3256 | struct filename filename = { .name = name }; |
f9652e10 | 3257 | int flags = op->lookup_flags | LOOKUP_ROOT; |
73d049a4 AV |
3258 | |
3259 | nd.root.mnt = mnt; | |
3260 | nd.root.dentry = dentry; | |
3261 | ||
b18825a7 | 3262 | if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) |
73d049a4 AV |
3263 | return ERR_PTR(-ELOOP); |
3264 | ||
669abf4e | 3265 | file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU); |
73d049a4 | 3266 | if (unlikely(file == ERR_PTR(-ECHILD))) |
669abf4e | 3267 | file = path_openat(-1, &filename, &nd, op, flags); |
73d049a4 | 3268 | if (unlikely(file == ERR_PTR(-ESTALE))) |
669abf4e | 3269 | file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_REVAL); |
73d049a4 AV |
3270 | return file; |
3271 | } | |
3272 | ||
1ac12b4b JL |
3273 | struct dentry *kern_path_create(int dfd, const char *pathname, |
3274 | struct path *path, unsigned int lookup_flags) | |
1da177e4 | 3275 | { |
c663e5d8 | 3276 | struct dentry *dentry = ERR_PTR(-EEXIST); |
ed75e95d | 3277 | struct nameidata nd; |
c30dabfe | 3278 | int err2; |
1ac12b4b JL |
3279 | int error; |
3280 | bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); | |
3281 | ||
3282 | /* | |
3283 | * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any | |
3284 | * other flags passed in are ignored! | |
3285 | */ | |
3286 | lookup_flags &= LOOKUP_REVAL; | |
3287 | ||
3288 | error = do_path_lookup(dfd, pathname, LOOKUP_PARENT|lookup_flags, &nd); | |
ed75e95d AV |
3289 | if (error) |
3290 | return ERR_PTR(error); | |
1da177e4 | 3291 | |
c663e5d8 CH |
3292 | /* |
3293 | * Yucky last component or no last component at all? | |
3294 | * (foo/., foo/.., /////) | |
3295 | */ | |
ed75e95d AV |
3296 | if (nd.last_type != LAST_NORM) |
3297 | goto out; | |
3298 | nd.flags &= ~LOOKUP_PARENT; | |
3299 | nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; | |
c663e5d8 | 3300 | |
c30dabfe JK |
3301 | /* don't fail immediately if it's r/o, at least try to report other errors */ |
3302 | err2 = mnt_want_write(nd.path.mnt); | |
c663e5d8 CH |
3303 | /* |
3304 | * Do the final lookup. | |
3305 | */ | |
ed75e95d AV |
3306 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
3307 | dentry = lookup_hash(&nd); | |
1da177e4 | 3308 | if (IS_ERR(dentry)) |
a8104a9f | 3309 | goto unlock; |
c663e5d8 | 3310 | |
a8104a9f | 3311 | error = -EEXIST; |
b18825a7 | 3312 | if (d_is_positive(dentry)) |
a8104a9f | 3313 | goto fail; |
b18825a7 | 3314 | |
c663e5d8 CH |
3315 | /* |
3316 | * Special case - lookup gave negative, but... we had foo/bar/ | |
3317 | * From the vfs_mknod() POV we just have a negative dentry - | |
3318 | * all is fine. Let's be bastards - you had / on the end, you've | |
3319 | * been asking for (non-existent) directory. -ENOENT for you. | |
3320 | */ | |
ed75e95d | 3321 | if (unlikely(!is_dir && nd.last.name[nd.last.len])) { |
a8104a9f | 3322 | error = -ENOENT; |
ed75e95d | 3323 | goto fail; |
e9baf6e5 | 3324 | } |
c30dabfe JK |
3325 | if (unlikely(err2)) { |
3326 | error = err2; | |
a8104a9f | 3327 | goto fail; |
c30dabfe | 3328 | } |
ed75e95d | 3329 | *path = nd.path; |
1da177e4 | 3330 | return dentry; |
1da177e4 | 3331 | fail: |
a8104a9f AV |
3332 | dput(dentry); |
3333 | dentry = ERR_PTR(error); | |
3334 | unlock: | |
ed75e95d | 3335 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
c30dabfe JK |
3336 | if (!err2) |
3337 | mnt_drop_write(nd.path.mnt); | |
ed75e95d AV |
3338 | out: |
3339 | path_put(&nd.path); | |
1da177e4 LT |
3340 | return dentry; |
3341 | } | |
dae6ad8f AV |
3342 | EXPORT_SYMBOL(kern_path_create); |
3343 | ||
921a1650 AV |
3344 | void done_path_create(struct path *path, struct dentry *dentry) |
3345 | { | |
3346 | dput(dentry); | |
3347 | mutex_unlock(&path->dentry->d_inode->i_mutex); | |
a8104a9f | 3348 | mnt_drop_write(path->mnt); |
921a1650 AV |
3349 | path_put(path); |
3350 | } | |
3351 | EXPORT_SYMBOL(done_path_create); | |
3352 | ||
1ac12b4b JL |
3353 | struct dentry *user_path_create(int dfd, const char __user *pathname, |
3354 | struct path *path, unsigned int lookup_flags) | |
dae6ad8f | 3355 | { |
91a27b2a | 3356 | struct filename *tmp = getname(pathname); |
dae6ad8f AV |
3357 | struct dentry *res; |
3358 | if (IS_ERR(tmp)) | |
3359 | return ERR_CAST(tmp); | |
1ac12b4b | 3360 | res = kern_path_create(dfd, tmp->name, path, lookup_flags); |
dae6ad8f AV |
3361 | putname(tmp); |
3362 | return res; | |
3363 | } | |
3364 | EXPORT_SYMBOL(user_path_create); | |
3365 | ||
1a67aafb | 3366 | int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
1da177e4 | 3367 | { |
a95164d9 | 3368 | int error = may_create(dir, dentry); |
1da177e4 LT |
3369 | |
3370 | if (error) | |
3371 | return error; | |
3372 | ||
975d6b39 | 3373 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) |
1da177e4 LT |
3374 | return -EPERM; |
3375 | ||
acfa4380 | 3376 | if (!dir->i_op->mknod) |
1da177e4 LT |
3377 | return -EPERM; |
3378 | ||
08ce5f16 SH |
3379 | error = devcgroup_inode_mknod(mode, dev); |
3380 | if (error) | |
3381 | return error; | |
3382 | ||
1da177e4 LT |
3383 | error = security_inode_mknod(dir, dentry, mode, dev); |
3384 | if (error) | |
3385 | return error; | |
3386 | ||
1da177e4 | 3387 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 3388 | if (!error) |
f38aa942 | 3389 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3390 | return error; |
3391 | } | |
4d359507 | 3392 | EXPORT_SYMBOL(vfs_mknod); |
1da177e4 | 3393 | |
f69aac00 | 3394 | static int may_mknod(umode_t mode) |
463c3197 DH |
3395 | { |
3396 | switch (mode & S_IFMT) { | |
3397 | case S_IFREG: | |
3398 | case S_IFCHR: | |
3399 | case S_IFBLK: | |
3400 | case S_IFIFO: | |
3401 | case S_IFSOCK: | |
3402 | case 0: /* zero mode translates to S_IFREG */ | |
3403 | return 0; | |
3404 | case S_IFDIR: | |
3405 | return -EPERM; | |
3406 | default: | |
3407 | return -EINVAL; | |
3408 | } | |
3409 | } | |
3410 | ||
8208a22b | 3411 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, |
2e4d0924 | 3412 | unsigned, dev) |
1da177e4 | 3413 | { |
2ad94ae6 | 3414 | struct dentry *dentry; |
dae6ad8f AV |
3415 | struct path path; |
3416 | int error; | |
972567f1 | 3417 | unsigned int lookup_flags = 0; |
1da177e4 | 3418 | |
8e4bfca1 AV |
3419 | error = may_mknod(mode); |
3420 | if (error) | |
3421 | return error; | |
972567f1 JL |
3422 | retry: |
3423 | dentry = user_path_create(dfd, filename, &path, lookup_flags); | |
dae6ad8f AV |
3424 | if (IS_ERR(dentry)) |
3425 | return PTR_ERR(dentry); | |
2ad94ae6 | 3426 | |
dae6ad8f | 3427 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3428 | mode &= ~current_umask(); |
dae6ad8f | 3429 | error = security_path_mknod(&path, dentry, mode, dev); |
be6d3e56 | 3430 | if (error) |
a8104a9f | 3431 | goto out; |
463c3197 | 3432 | switch (mode & S_IFMT) { |
1da177e4 | 3433 | case 0: case S_IFREG: |
312b63fb | 3434 | error = vfs_create(path.dentry->d_inode,dentry,mode,true); |
1da177e4 LT |
3435 | break; |
3436 | case S_IFCHR: case S_IFBLK: | |
dae6ad8f | 3437 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
3438 | new_decode_dev(dev)); |
3439 | break; | |
3440 | case S_IFIFO: case S_IFSOCK: | |
dae6ad8f | 3441 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 3442 | break; |
1da177e4 | 3443 | } |
a8104a9f | 3444 | out: |
921a1650 | 3445 | done_path_create(&path, dentry); |
972567f1 JL |
3446 | if (retry_estale(error, lookup_flags)) { |
3447 | lookup_flags |= LOOKUP_REVAL; | |
3448 | goto retry; | |
3449 | } | |
1da177e4 LT |
3450 | return error; |
3451 | } | |
3452 | ||
8208a22b | 3453 | SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) |
5590ff0d UD |
3454 | { |
3455 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
3456 | } | |
3457 | ||
18bb1db3 | 3458 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
1da177e4 | 3459 | { |
a95164d9 | 3460 | int error = may_create(dir, dentry); |
8de52778 | 3461 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
3462 | |
3463 | if (error) | |
3464 | return error; | |
3465 | ||
acfa4380 | 3466 | if (!dir->i_op->mkdir) |
1da177e4 LT |
3467 | return -EPERM; |
3468 | ||
3469 | mode &= (S_IRWXUGO|S_ISVTX); | |
3470 | error = security_inode_mkdir(dir, dentry, mode); | |
3471 | if (error) | |
3472 | return error; | |
3473 | ||
8de52778 AV |
3474 | if (max_links && dir->i_nlink >= max_links) |
3475 | return -EMLINK; | |
3476 | ||
1da177e4 | 3477 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 3478 | if (!error) |
f38aa942 | 3479 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
3480 | return error; |
3481 | } | |
4d359507 | 3482 | EXPORT_SYMBOL(vfs_mkdir); |
1da177e4 | 3483 | |
a218d0fd | 3484 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) |
1da177e4 | 3485 | { |
6902d925 | 3486 | struct dentry *dentry; |
dae6ad8f AV |
3487 | struct path path; |
3488 | int error; | |
b76d8b82 | 3489 | unsigned int lookup_flags = LOOKUP_DIRECTORY; |
1da177e4 | 3490 | |
b76d8b82 JL |
3491 | retry: |
3492 | dentry = user_path_create(dfd, pathname, &path, lookup_flags); | |
6902d925 | 3493 | if (IS_ERR(dentry)) |
dae6ad8f | 3494 | return PTR_ERR(dentry); |
1da177e4 | 3495 | |
dae6ad8f | 3496 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3497 | mode &= ~current_umask(); |
dae6ad8f | 3498 | error = security_path_mkdir(&path, dentry, mode); |
a8104a9f AV |
3499 | if (!error) |
3500 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); | |
921a1650 | 3501 | done_path_create(&path, dentry); |
b76d8b82 JL |
3502 | if (retry_estale(error, lookup_flags)) { |
3503 | lookup_flags |= LOOKUP_REVAL; | |
3504 | goto retry; | |
3505 | } | |
1da177e4 LT |
3506 | return error; |
3507 | } | |
3508 | ||
a218d0fd | 3509 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) |
5590ff0d UD |
3510 | { |
3511 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
3512 | } | |
3513 | ||
1da177e4 | 3514 | /* |
a71905f0 | 3515 | * The dentry_unhash() helper will try to drop the dentry early: we |
c0d02594 | 3516 | * should have a usage count of 1 if we're the only user of this |
a71905f0 SW |
3517 | * dentry, and if that is true (possibly after pruning the dcache), |
3518 | * then we drop the dentry now. | |
1da177e4 LT |
3519 | * |
3520 | * A low-level filesystem can, if it choses, legally | |
3521 | * do a | |
3522 | * | |
3523 | * if (!d_unhashed(dentry)) | |
3524 | * return -EBUSY; | |
3525 | * | |
3526 | * if it cannot handle the case of removing a directory | |
3527 | * that is still in use by something else.. | |
3528 | */ | |
3529 | void dentry_unhash(struct dentry *dentry) | |
3530 | { | |
dc168427 | 3531 | shrink_dcache_parent(dentry); |
1da177e4 | 3532 | spin_lock(&dentry->d_lock); |
98474236 | 3533 | if (dentry->d_lockref.count == 1) |
1da177e4 LT |
3534 | __d_drop(dentry); |
3535 | spin_unlock(&dentry->d_lock); | |
1da177e4 | 3536 | } |
4d359507 | 3537 | EXPORT_SYMBOL(dentry_unhash); |
1da177e4 LT |
3538 | |
3539 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
3540 | { | |
3541 | int error = may_delete(dir, dentry, 1); | |
3542 | ||
3543 | if (error) | |
3544 | return error; | |
3545 | ||
acfa4380 | 3546 | if (!dir->i_op->rmdir) |
1da177e4 LT |
3547 | return -EPERM; |
3548 | ||
1d2ef590 | 3549 | dget(dentry); |
1b1dcc1b | 3550 | mutex_lock(&dentry->d_inode->i_mutex); |
912dbc15 SW |
3551 | |
3552 | error = -EBUSY; | |
1da177e4 | 3553 | if (d_mountpoint(dentry)) |
912dbc15 SW |
3554 | goto out; |
3555 | ||
3556 | error = security_inode_rmdir(dir, dentry); | |
3557 | if (error) | |
3558 | goto out; | |
3559 | ||
3cebde24 | 3560 | shrink_dcache_parent(dentry); |
912dbc15 SW |
3561 | error = dir->i_op->rmdir(dir, dentry); |
3562 | if (error) | |
3563 | goto out; | |
3564 | ||
3565 | dentry->d_inode->i_flags |= S_DEAD; | |
3566 | dont_mount(dentry); | |
3567 | ||
3568 | out: | |
1b1dcc1b | 3569 | mutex_unlock(&dentry->d_inode->i_mutex); |
1d2ef590 | 3570 | dput(dentry); |
912dbc15 | 3571 | if (!error) |
1da177e4 | 3572 | d_delete(dentry); |
1da177e4 LT |
3573 | return error; |
3574 | } | |
4d359507 | 3575 | EXPORT_SYMBOL(vfs_rmdir); |
1da177e4 | 3576 | |
5590ff0d | 3577 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
3578 | { |
3579 | int error = 0; | |
91a27b2a | 3580 | struct filename *name; |
1da177e4 LT |
3581 | struct dentry *dentry; |
3582 | struct nameidata nd; | |
c6ee9206 JL |
3583 | unsigned int lookup_flags = 0; |
3584 | retry: | |
3585 | name = user_path_parent(dfd, pathname, &nd, lookup_flags); | |
91a27b2a JL |
3586 | if (IS_ERR(name)) |
3587 | return PTR_ERR(name); | |
1da177e4 LT |
3588 | |
3589 | switch(nd.last_type) { | |
0612d9fb OH |
3590 | case LAST_DOTDOT: |
3591 | error = -ENOTEMPTY; | |
3592 | goto exit1; | |
3593 | case LAST_DOT: | |
3594 | error = -EINVAL; | |
3595 | goto exit1; | |
3596 | case LAST_ROOT: | |
3597 | error = -EBUSY; | |
3598 | goto exit1; | |
1da177e4 | 3599 | } |
0612d9fb OH |
3600 | |
3601 | nd.flags &= ~LOOKUP_PARENT; | |
c30dabfe JK |
3602 | error = mnt_want_write(nd.path.mnt); |
3603 | if (error) | |
3604 | goto exit1; | |
0612d9fb | 3605 | |
4ac91378 | 3606 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 3607 | dentry = lookup_hash(&nd); |
1da177e4 | 3608 | error = PTR_ERR(dentry); |
6902d925 DH |
3609 | if (IS_ERR(dentry)) |
3610 | goto exit2; | |
e6bc45d6 TT |
3611 | if (!dentry->d_inode) { |
3612 | error = -ENOENT; | |
3613 | goto exit3; | |
3614 | } | |
be6d3e56 KT |
3615 | error = security_path_rmdir(&nd.path, dentry); |
3616 | if (error) | |
c30dabfe | 3617 | goto exit3; |
4ac91378 | 3618 | error = vfs_rmdir(nd.path.dentry->d_inode, dentry); |
0622753b | 3619 | exit3: |
6902d925 DH |
3620 | dput(dentry); |
3621 | exit2: | |
4ac91378 | 3622 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
c30dabfe | 3623 | mnt_drop_write(nd.path.mnt); |
1da177e4 | 3624 | exit1: |
1d957f9b | 3625 | path_put(&nd.path); |
1da177e4 | 3626 | putname(name); |
c6ee9206 JL |
3627 | if (retry_estale(error, lookup_flags)) { |
3628 | lookup_flags |= LOOKUP_REVAL; | |
3629 | goto retry; | |
3630 | } | |
1da177e4 LT |
3631 | return error; |
3632 | } | |
3633 | ||
3cdad428 | 3634 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
3635 | { |
3636 | return do_rmdir(AT_FDCWD, pathname); | |
3637 | } | |
3638 | ||
b21996e3 BF |
3639 | /** |
3640 | * vfs_unlink - unlink a filesystem object | |
3641 | * @dir: parent directory | |
3642 | * @dentry: victim | |
3643 | * @delegated_inode: returns victim inode, if the inode is delegated. | |
3644 | * | |
3645 | * The caller must hold dir->i_mutex. | |
3646 | * | |
3647 | * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and | |
3648 | * return a reference to the inode in delegated_inode. The caller | |
3649 | * should then break the delegation on that inode and retry. Because | |
3650 | * breaking a delegation may take a long time, the caller should drop | |
3651 | * dir->i_mutex before doing so. | |
3652 | * | |
3653 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
3654 | * be appropriate for callers that expect the underlying filesystem not | |
3655 | * to be NFS exported. | |
3656 | */ | |
3657 | int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) | |
1da177e4 | 3658 | { |
9accbb97 | 3659 | struct inode *target = dentry->d_inode; |
1da177e4 LT |
3660 | int error = may_delete(dir, dentry, 0); |
3661 | ||
3662 | if (error) | |
3663 | return error; | |
3664 | ||
acfa4380 | 3665 | if (!dir->i_op->unlink) |
1da177e4 LT |
3666 | return -EPERM; |
3667 | ||
9accbb97 | 3668 | mutex_lock(&target->i_mutex); |
1da177e4 LT |
3669 | if (d_mountpoint(dentry)) |
3670 | error = -EBUSY; | |
3671 | else { | |
3672 | error = security_inode_unlink(dir, dentry); | |
bec1052e | 3673 | if (!error) { |
5a14696c BF |
3674 | error = try_break_deleg(target, delegated_inode); |
3675 | if (error) | |
b21996e3 | 3676 | goto out; |
1da177e4 | 3677 | error = dir->i_op->unlink(dir, dentry); |
bec1052e | 3678 | if (!error) |
d83c49f3 | 3679 | dont_mount(dentry); |
bec1052e | 3680 | } |
1da177e4 | 3681 | } |
b21996e3 | 3682 | out: |
9accbb97 | 3683 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
3684 | |
3685 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
3686 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
9accbb97 | 3687 | fsnotify_link_count(target); |
e234f35c | 3688 | d_delete(dentry); |
1da177e4 | 3689 | } |
0eeca283 | 3690 | |
1da177e4 LT |
3691 | return error; |
3692 | } | |
4d359507 | 3693 | EXPORT_SYMBOL(vfs_unlink); |
1da177e4 LT |
3694 | |
3695 | /* | |
3696 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 3697 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
3698 | * writeout happening, and we don't want to prevent access to the directory |
3699 | * while waiting on the I/O. | |
3700 | */ | |
5590ff0d | 3701 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 3702 | { |
2ad94ae6 | 3703 | int error; |
91a27b2a | 3704 | struct filename *name; |
1da177e4 LT |
3705 | struct dentry *dentry; |
3706 | struct nameidata nd; | |
3707 | struct inode *inode = NULL; | |
b21996e3 | 3708 | struct inode *delegated_inode = NULL; |
5d18f813 JL |
3709 | unsigned int lookup_flags = 0; |
3710 | retry: | |
3711 | name = user_path_parent(dfd, pathname, &nd, lookup_flags); | |
91a27b2a JL |
3712 | if (IS_ERR(name)) |
3713 | return PTR_ERR(name); | |
2ad94ae6 | 3714 | |
1da177e4 LT |
3715 | error = -EISDIR; |
3716 | if (nd.last_type != LAST_NORM) | |
3717 | goto exit1; | |
0612d9fb OH |
3718 | |
3719 | nd.flags &= ~LOOKUP_PARENT; | |
c30dabfe JK |
3720 | error = mnt_want_write(nd.path.mnt); |
3721 | if (error) | |
3722 | goto exit1; | |
b21996e3 | 3723 | retry_deleg: |
4ac91378 | 3724 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
49705b77 | 3725 | dentry = lookup_hash(&nd); |
1da177e4 LT |
3726 | error = PTR_ERR(dentry); |
3727 | if (!IS_ERR(dentry)) { | |
3728 | /* Why not before? Because we want correct error value */ | |
50338b88 TE |
3729 | if (nd.last.name[nd.last.len]) |
3730 | goto slashes; | |
1da177e4 | 3731 | inode = dentry->d_inode; |
b18825a7 | 3732 | if (d_is_negative(dentry)) |
e6bc45d6 TT |
3733 | goto slashes; |
3734 | ihold(inode); | |
be6d3e56 KT |
3735 | error = security_path_unlink(&nd.path, dentry); |
3736 | if (error) | |
c30dabfe | 3737 | goto exit2; |
b21996e3 | 3738 | error = vfs_unlink(nd.path.dentry->d_inode, dentry, &delegated_inode); |
c30dabfe | 3739 | exit2: |
1da177e4 LT |
3740 | dput(dentry); |
3741 | } | |
4ac91378 | 3742 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
1da177e4 LT |
3743 | if (inode) |
3744 | iput(inode); /* truncate the inode here */ | |
b21996e3 BF |
3745 | inode = NULL; |
3746 | if (delegated_inode) { | |
5a14696c | 3747 | error = break_deleg_wait(&delegated_inode); |
b21996e3 BF |
3748 | if (!error) |
3749 | goto retry_deleg; | |
3750 | } | |
c30dabfe | 3751 | mnt_drop_write(nd.path.mnt); |
1da177e4 | 3752 | exit1: |
1d957f9b | 3753 | path_put(&nd.path); |
1da177e4 | 3754 | putname(name); |
5d18f813 JL |
3755 | if (retry_estale(error, lookup_flags)) { |
3756 | lookup_flags |= LOOKUP_REVAL; | |
3757 | inode = NULL; | |
3758 | goto retry; | |
3759 | } | |
1da177e4 LT |
3760 | return error; |
3761 | ||
3762 | slashes: | |
b18825a7 DH |
3763 | if (d_is_negative(dentry)) |
3764 | error = -ENOENT; | |
44b1d530 | 3765 | else if (d_is_dir(dentry)) |
b18825a7 DH |
3766 | error = -EISDIR; |
3767 | else | |
3768 | error = -ENOTDIR; | |
1da177e4 LT |
3769 | goto exit2; |
3770 | } | |
3771 | ||
2e4d0924 | 3772 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
3773 | { |
3774 | if ((flag & ~AT_REMOVEDIR) != 0) | |
3775 | return -EINVAL; | |
3776 | ||
3777 | if (flag & AT_REMOVEDIR) | |
3778 | return do_rmdir(dfd, pathname); | |
3779 | ||
3780 | return do_unlinkat(dfd, pathname); | |
3781 | } | |
3782 | ||
3480b257 | 3783 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
3784 | { |
3785 | return do_unlinkat(AT_FDCWD, pathname); | |
3786 | } | |
3787 | ||
db2e747b | 3788 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 3789 | { |
a95164d9 | 3790 | int error = may_create(dir, dentry); |
1da177e4 LT |
3791 | |
3792 | if (error) | |
3793 | return error; | |
3794 | ||
acfa4380 | 3795 | if (!dir->i_op->symlink) |
1da177e4 LT |
3796 | return -EPERM; |
3797 | ||
3798 | error = security_inode_symlink(dir, dentry, oldname); | |
3799 | if (error) | |
3800 | return error; | |
3801 | ||
1da177e4 | 3802 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 3803 | if (!error) |
f38aa942 | 3804 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3805 | return error; |
3806 | } | |
4d359507 | 3807 | EXPORT_SYMBOL(vfs_symlink); |
1da177e4 | 3808 | |
2e4d0924 HC |
3809 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
3810 | int, newdfd, const char __user *, newname) | |
1da177e4 | 3811 | { |
2ad94ae6 | 3812 | int error; |
91a27b2a | 3813 | struct filename *from; |
6902d925 | 3814 | struct dentry *dentry; |
dae6ad8f | 3815 | struct path path; |
f46d3567 | 3816 | unsigned int lookup_flags = 0; |
1da177e4 LT |
3817 | |
3818 | from = getname(oldname); | |
2ad94ae6 | 3819 | if (IS_ERR(from)) |
1da177e4 | 3820 | return PTR_ERR(from); |
f46d3567 JL |
3821 | retry: |
3822 | dentry = user_path_create(newdfd, newname, &path, lookup_flags); | |
6902d925 DH |
3823 | error = PTR_ERR(dentry); |
3824 | if (IS_ERR(dentry)) | |
dae6ad8f | 3825 | goto out_putname; |
6902d925 | 3826 | |
91a27b2a | 3827 | error = security_path_symlink(&path, dentry, from->name); |
a8104a9f | 3828 | if (!error) |
91a27b2a | 3829 | error = vfs_symlink(path.dentry->d_inode, dentry, from->name); |
921a1650 | 3830 | done_path_create(&path, dentry); |
f46d3567 JL |
3831 | if (retry_estale(error, lookup_flags)) { |
3832 | lookup_flags |= LOOKUP_REVAL; | |
3833 | goto retry; | |
3834 | } | |
6902d925 | 3835 | out_putname: |
1da177e4 LT |
3836 | putname(from); |
3837 | return error; | |
3838 | } | |
3839 | ||
3480b257 | 3840 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
3841 | { |
3842 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
3843 | } | |
3844 | ||
146a8595 BF |
3845 | /** |
3846 | * vfs_link - create a new link | |
3847 | * @old_dentry: object to be linked | |
3848 | * @dir: new parent | |
3849 | * @new_dentry: where to create the new link | |
3850 | * @delegated_inode: returns inode needing a delegation break | |
3851 | * | |
3852 | * The caller must hold dir->i_mutex | |
3853 | * | |
3854 | * If vfs_link discovers a delegation on the to-be-linked file in need | |
3855 | * of breaking, it will return -EWOULDBLOCK and return a reference to the | |
3856 | * inode in delegated_inode. The caller should then break the delegation | |
3857 | * and retry. Because breaking a delegation may take a long time, the | |
3858 | * caller should drop the i_mutex before doing so. | |
3859 | * | |
3860 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
3861 | * be appropriate for callers that expect the underlying filesystem not | |
3862 | * to be NFS exported. | |
3863 | */ | |
3864 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) | |
1da177e4 LT |
3865 | { |
3866 | struct inode *inode = old_dentry->d_inode; | |
8de52778 | 3867 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
3868 | int error; |
3869 | ||
3870 | if (!inode) | |
3871 | return -ENOENT; | |
3872 | ||
a95164d9 | 3873 | error = may_create(dir, new_dentry); |
1da177e4 LT |
3874 | if (error) |
3875 | return error; | |
3876 | ||
3877 | if (dir->i_sb != inode->i_sb) | |
3878 | return -EXDEV; | |
3879 | ||
3880 | /* | |
3881 | * A link to an append-only or immutable file cannot be created. | |
3882 | */ | |
3883 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
3884 | return -EPERM; | |
acfa4380 | 3885 | if (!dir->i_op->link) |
1da177e4 | 3886 | return -EPERM; |
7e79eedb | 3887 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
3888 | return -EPERM; |
3889 | ||
3890 | error = security_inode_link(old_dentry, dir, new_dentry); | |
3891 | if (error) | |
3892 | return error; | |
3893 | ||
7e79eedb | 3894 | mutex_lock(&inode->i_mutex); |
aae8a97d | 3895 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
f4e0c30c | 3896 | if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) |
aae8a97d | 3897 | error = -ENOENT; |
8de52778 AV |
3898 | else if (max_links && inode->i_nlink >= max_links) |
3899 | error = -EMLINK; | |
146a8595 BF |
3900 | else { |
3901 | error = try_break_deleg(inode, delegated_inode); | |
3902 | if (!error) | |
3903 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
3904 | } | |
f4e0c30c AV |
3905 | |
3906 | if (!error && (inode->i_state & I_LINKABLE)) { | |
3907 | spin_lock(&inode->i_lock); | |
3908 | inode->i_state &= ~I_LINKABLE; | |
3909 | spin_unlock(&inode->i_lock); | |
3910 | } | |
7e79eedb | 3911 | mutex_unlock(&inode->i_mutex); |
e31e14ec | 3912 | if (!error) |
7e79eedb | 3913 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
3914 | return error; |
3915 | } | |
4d359507 | 3916 | EXPORT_SYMBOL(vfs_link); |
1da177e4 LT |
3917 | |
3918 | /* | |
3919 | * Hardlinks are often used in delicate situations. We avoid | |
3920 | * security-related surprises by not following symlinks on the | |
3921 | * newname. --KAB | |
3922 | * | |
3923 | * We don't follow them on the oldname either to be compatible | |
3924 | * with linux 2.0, and to avoid hard-linking to directories | |
3925 | * and other special files. --ADM | |
3926 | */ | |
2e4d0924 HC |
3927 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
3928 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
3929 | { |
3930 | struct dentry *new_dentry; | |
dae6ad8f | 3931 | struct path old_path, new_path; |
146a8595 | 3932 | struct inode *delegated_inode = NULL; |
11a7b371 | 3933 | int how = 0; |
1da177e4 | 3934 | int error; |
1da177e4 | 3935 | |
11a7b371 | 3936 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
c04030e1 | 3937 | return -EINVAL; |
11a7b371 | 3938 | /* |
f0cc6ffb LT |
3939 | * To use null names we require CAP_DAC_READ_SEARCH |
3940 | * This ensures that not everyone will be able to create | |
3941 | * handlink using the passed filedescriptor. | |
11a7b371 | 3942 | */ |
f0cc6ffb LT |
3943 | if (flags & AT_EMPTY_PATH) { |
3944 | if (!capable(CAP_DAC_READ_SEARCH)) | |
3945 | return -ENOENT; | |
11a7b371 | 3946 | how = LOOKUP_EMPTY; |
f0cc6ffb | 3947 | } |
11a7b371 AK |
3948 | |
3949 | if (flags & AT_SYMLINK_FOLLOW) | |
3950 | how |= LOOKUP_FOLLOW; | |
442e31ca | 3951 | retry: |
11a7b371 | 3952 | error = user_path_at(olddfd, oldname, how, &old_path); |
1da177e4 | 3953 | if (error) |
2ad94ae6 AV |
3954 | return error; |
3955 | ||
442e31ca JL |
3956 | new_dentry = user_path_create(newdfd, newname, &new_path, |
3957 | (how & LOOKUP_REVAL)); | |
1da177e4 | 3958 | error = PTR_ERR(new_dentry); |
6902d925 | 3959 | if (IS_ERR(new_dentry)) |
dae6ad8f AV |
3960 | goto out; |
3961 | ||
3962 | error = -EXDEV; | |
3963 | if (old_path.mnt != new_path.mnt) | |
3964 | goto out_dput; | |
800179c9 KC |
3965 | error = may_linkat(&old_path); |
3966 | if (unlikely(error)) | |
3967 | goto out_dput; | |
dae6ad8f | 3968 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
be6d3e56 | 3969 | if (error) |
a8104a9f | 3970 | goto out_dput; |
146a8595 | 3971 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); |
75c3f29d | 3972 | out_dput: |
921a1650 | 3973 | done_path_create(&new_path, new_dentry); |
146a8595 BF |
3974 | if (delegated_inode) { |
3975 | error = break_deleg_wait(&delegated_inode); | |
d22e6338 OD |
3976 | if (!error) { |
3977 | path_put(&old_path); | |
146a8595 | 3978 | goto retry; |
d22e6338 | 3979 | } |
146a8595 | 3980 | } |
442e31ca | 3981 | if (retry_estale(error, how)) { |
d22e6338 | 3982 | path_put(&old_path); |
442e31ca JL |
3983 | how |= LOOKUP_REVAL; |
3984 | goto retry; | |
3985 | } | |
1da177e4 | 3986 | out: |
2d8f3038 | 3987 | path_put(&old_path); |
1da177e4 LT |
3988 | |
3989 | return error; | |
3990 | } | |
3991 | ||
3480b257 | 3992 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 3993 | { |
c04030e1 | 3994 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
3995 | } |
3996 | ||
bc27027a MS |
3997 | /** |
3998 | * vfs_rename - rename a filesystem object | |
3999 | * @old_dir: parent of source | |
4000 | * @old_dentry: source | |
4001 | * @new_dir: parent of destination | |
4002 | * @new_dentry: destination | |
4003 | * @delegated_inode: returns an inode needing a delegation break | |
520c8b16 | 4004 | * @flags: rename flags |
bc27027a MS |
4005 | * |
4006 | * The caller must hold multiple mutexes--see lock_rename()). | |
4007 | * | |
4008 | * If vfs_rename discovers a delegation in need of breaking at either | |
4009 | * the source or destination, it will return -EWOULDBLOCK and return a | |
4010 | * reference to the inode in delegated_inode. The caller should then | |
4011 | * break the delegation and retry. Because breaking a delegation may | |
4012 | * take a long time, the caller should drop all locks before doing | |
4013 | * so. | |
4014 | * | |
4015 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
4016 | * be appropriate for callers that expect the underlying filesystem not | |
4017 | * to be NFS exported. | |
4018 | * | |
1da177e4 LT |
4019 | * The worst of all namespace operations - renaming directory. "Perverted" |
4020 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
4021 | * Problems: | |
4022 | * a) we can get into loop creation. Check is done in is_subdir(). | |
4023 | * b) race potential - two innocent renames can create a loop together. | |
4024 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 4025 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 | 4026 | * story. |
6cedba89 BF |
4027 | * c) we have to lock _four_ objects - parents and victim (if it exists), |
4028 | * and source (if it is not a directory). | |
1b1dcc1b | 4029 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
4030 | * whether the target exists). Solution: try to be smart with locking |
4031 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 4032 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
4033 | * move will be locked. Thus we can rank directories by the tree |
4034 | * (ancestors first) and rank all non-directories after them. | |
4035 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 4036 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
4037 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
4038 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
4039 | * we'd better make sure that there's no link(2) for them. | |
e4eaac06 | 4040 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
1b1dcc1b | 4041 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 4042 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
c41b20e7 | 4043 | * ->i_mutex on parents, which works but leads to some truly excessive |
1da177e4 LT |
4044 | * locking]. |
4045 | */ | |
bc27027a MS |
4046 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, |
4047 | struct inode *new_dir, struct dentry *new_dentry, | |
520c8b16 | 4048 | struct inode **delegated_inode, unsigned int flags) |
1da177e4 | 4049 | { |
bc27027a MS |
4050 | int error; |
4051 | bool is_dir = d_is_dir(old_dentry); | |
4052 | const unsigned char *old_name; | |
4053 | struct inode *source = old_dentry->d_inode; | |
9055cba7 | 4054 | struct inode *target = new_dentry->d_inode; |
da1ce067 MS |
4055 | bool new_is_dir = false; |
4056 | unsigned max_links = new_dir->i_sb->s_max_links; | |
bc27027a MS |
4057 | |
4058 | if (source == target) | |
4059 | return 0; | |
4060 | ||
4061 | error = may_delete(old_dir, old_dentry, is_dir); | |
4062 | if (error) | |
4063 | return error; | |
4064 | ||
da1ce067 | 4065 | if (!target) { |
bc27027a | 4066 | error = may_create(new_dir, new_dentry); |
da1ce067 MS |
4067 | } else { |
4068 | new_is_dir = d_is_dir(new_dentry); | |
4069 | ||
4070 | if (!(flags & RENAME_EXCHANGE)) | |
4071 | error = may_delete(new_dir, new_dentry, is_dir); | |
4072 | else | |
4073 | error = may_delete(new_dir, new_dentry, new_is_dir); | |
4074 | } | |
bc27027a MS |
4075 | if (error) |
4076 | return error; | |
4077 | ||
4078 | if (!old_dir->i_op->rename) | |
4079 | return -EPERM; | |
1da177e4 | 4080 | |
520c8b16 MS |
4081 | if (flags && !old_dir->i_op->rename2) |
4082 | return -EINVAL; | |
4083 | ||
1da177e4 LT |
4084 | /* |
4085 | * If we are going to change the parent - check write permissions, | |
4086 | * we'll need to flip '..'. | |
4087 | */ | |
da1ce067 MS |
4088 | if (new_dir != old_dir) { |
4089 | if (is_dir) { | |
4090 | error = inode_permission(source, MAY_WRITE); | |
4091 | if (error) | |
4092 | return error; | |
4093 | } | |
4094 | if ((flags & RENAME_EXCHANGE) && new_is_dir) { | |
4095 | error = inode_permission(target, MAY_WRITE); | |
4096 | if (error) | |
4097 | return error; | |
4098 | } | |
1da177e4 LT |
4099 | } |
4100 | ||
0b3974eb MS |
4101 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, |
4102 | flags); | |
1da177e4 LT |
4103 | if (error) |
4104 | return error; | |
4105 | ||
bc27027a | 4106 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
1d2ef590 | 4107 | dget(new_dentry); |
da1ce067 | 4108 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
bc27027a MS |
4109 | lock_two_nondirectories(source, target); |
4110 | else if (target) | |
1b1dcc1b | 4111 | mutex_lock(&target->i_mutex); |
9055cba7 SW |
4112 | |
4113 | error = -EBUSY; | |
4114 | if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) | |
4115 | goto out; | |
4116 | ||
da1ce067 | 4117 | if (max_links && new_dir != old_dir) { |
bc27027a | 4118 | error = -EMLINK; |
da1ce067 | 4119 | if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) |
bc27027a | 4120 | goto out; |
da1ce067 MS |
4121 | if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && |
4122 | old_dir->i_nlink >= max_links) | |
4123 | goto out; | |
4124 | } | |
4125 | if (is_dir && !(flags & RENAME_EXCHANGE) && target) | |
4126 | shrink_dcache_parent(new_dentry); | |
4127 | if (!is_dir) { | |
bc27027a | 4128 | error = try_break_deleg(source, delegated_inode); |
8e6d782c BF |
4129 | if (error) |
4130 | goto out; | |
da1ce067 MS |
4131 | } |
4132 | if (target && !new_is_dir) { | |
4133 | error = try_break_deleg(target, delegated_inode); | |
4134 | if (error) | |
4135 | goto out; | |
8e6d782c | 4136 | } |
520c8b16 MS |
4137 | if (!flags) { |
4138 | error = old_dir->i_op->rename(old_dir, old_dentry, | |
4139 | new_dir, new_dentry); | |
4140 | } else { | |
4141 | error = old_dir->i_op->rename2(old_dir, old_dentry, | |
4142 | new_dir, new_dentry, flags); | |
4143 | } | |
51892bbb SW |
4144 | if (error) |
4145 | goto out; | |
4146 | ||
da1ce067 | 4147 | if (!(flags & RENAME_EXCHANGE) && target) { |
bc27027a MS |
4148 | if (is_dir) |
4149 | target->i_flags |= S_DEAD; | |
51892bbb | 4150 | dont_mount(new_dentry); |
bc27027a | 4151 | } |
da1ce067 MS |
4152 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { |
4153 | if (!(flags & RENAME_EXCHANGE)) | |
4154 | d_move(old_dentry, new_dentry); | |
4155 | else | |
4156 | d_exchange(old_dentry, new_dentry); | |
4157 | } | |
51892bbb | 4158 | out: |
da1ce067 | 4159 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
bc27027a MS |
4160 | unlock_two_nondirectories(source, target); |
4161 | else if (target) | |
4162 | mutex_unlock(&target->i_mutex); | |
1da177e4 | 4163 | dput(new_dentry); |
da1ce067 | 4164 | if (!error) { |
123df294 | 4165 | fsnotify_move(old_dir, new_dir, old_name, is_dir, |
da1ce067 MS |
4166 | !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); |
4167 | if (flags & RENAME_EXCHANGE) { | |
4168 | fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, | |
4169 | new_is_dir, NULL, new_dentry); | |
4170 | } | |
4171 | } | |
0eeca283 RL |
4172 | fsnotify_oldname_free(old_name); |
4173 | ||
1da177e4 LT |
4174 | return error; |
4175 | } | |
4d359507 | 4176 | EXPORT_SYMBOL(vfs_rename); |
1da177e4 | 4177 | |
520c8b16 MS |
4178 | SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, |
4179 | int, newdfd, const char __user *, newname, unsigned int, flags) | |
1da177e4 | 4180 | { |
2ad94ae6 AV |
4181 | struct dentry *old_dir, *new_dir; |
4182 | struct dentry *old_dentry, *new_dentry; | |
4183 | struct dentry *trap; | |
1da177e4 | 4184 | struct nameidata oldnd, newnd; |
8e6d782c | 4185 | struct inode *delegated_inode = NULL; |
91a27b2a JL |
4186 | struct filename *from; |
4187 | struct filename *to; | |
c6a94284 JL |
4188 | unsigned int lookup_flags = 0; |
4189 | bool should_retry = false; | |
2ad94ae6 | 4190 | int error; |
520c8b16 | 4191 | |
da1ce067 MS |
4192 | if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) |
4193 | return -EINVAL; | |
4194 | ||
4195 | if ((flags & RENAME_NOREPLACE) && (flags & RENAME_EXCHANGE)) | |
520c8b16 MS |
4196 | return -EINVAL; |
4197 | ||
c6a94284 JL |
4198 | retry: |
4199 | from = user_path_parent(olddfd, oldname, &oldnd, lookup_flags); | |
91a27b2a JL |
4200 | if (IS_ERR(from)) { |
4201 | error = PTR_ERR(from); | |
1da177e4 | 4202 | goto exit; |
91a27b2a | 4203 | } |
1da177e4 | 4204 | |
c6a94284 | 4205 | to = user_path_parent(newdfd, newname, &newnd, lookup_flags); |
91a27b2a JL |
4206 | if (IS_ERR(to)) { |
4207 | error = PTR_ERR(to); | |
1da177e4 | 4208 | goto exit1; |
91a27b2a | 4209 | } |
1da177e4 LT |
4210 | |
4211 | error = -EXDEV; | |
4ac91378 | 4212 | if (oldnd.path.mnt != newnd.path.mnt) |
1da177e4 LT |
4213 | goto exit2; |
4214 | ||
4ac91378 | 4215 | old_dir = oldnd.path.dentry; |
1da177e4 LT |
4216 | error = -EBUSY; |
4217 | if (oldnd.last_type != LAST_NORM) | |
4218 | goto exit2; | |
4219 | ||
4ac91378 | 4220 | new_dir = newnd.path.dentry; |
0a7c3937 MS |
4221 | if (flags & RENAME_NOREPLACE) |
4222 | error = -EEXIST; | |
1da177e4 LT |
4223 | if (newnd.last_type != LAST_NORM) |
4224 | goto exit2; | |
4225 | ||
c30dabfe JK |
4226 | error = mnt_want_write(oldnd.path.mnt); |
4227 | if (error) | |
4228 | goto exit2; | |
4229 | ||
0612d9fb OH |
4230 | oldnd.flags &= ~LOOKUP_PARENT; |
4231 | newnd.flags &= ~LOOKUP_PARENT; | |
da1ce067 MS |
4232 | if (!(flags & RENAME_EXCHANGE)) |
4233 | newnd.flags |= LOOKUP_RENAME_TARGET; | |
0612d9fb | 4234 | |
8e6d782c | 4235 | retry_deleg: |
1da177e4 LT |
4236 | trap = lock_rename(new_dir, old_dir); |
4237 | ||
49705b77 | 4238 | old_dentry = lookup_hash(&oldnd); |
1da177e4 LT |
4239 | error = PTR_ERR(old_dentry); |
4240 | if (IS_ERR(old_dentry)) | |
4241 | goto exit3; | |
4242 | /* source must exist */ | |
4243 | error = -ENOENT; | |
b18825a7 | 4244 | if (d_is_negative(old_dentry)) |
1da177e4 | 4245 | goto exit4; |
0a7c3937 MS |
4246 | new_dentry = lookup_hash(&newnd); |
4247 | error = PTR_ERR(new_dentry); | |
4248 | if (IS_ERR(new_dentry)) | |
4249 | goto exit4; | |
4250 | error = -EEXIST; | |
4251 | if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) | |
4252 | goto exit5; | |
da1ce067 MS |
4253 | if (flags & RENAME_EXCHANGE) { |
4254 | error = -ENOENT; | |
4255 | if (d_is_negative(new_dentry)) | |
4256 | goto exit5; | |
4257 | ||
4258 | if (!d_is_dir(new_dentry)) { | |
4259 | error = -ENOTDIR; | |
4260 | if (newnd.last.name[newnd.last.len]) | |
4261 | goto exit5; | |
4262 | } | |
4263 | } | |
1da177e4 | 4264 | /* unless the source is a directory trailing slashes give -ENOTDIR */ |
44b1d530 | 4265 | if (!d_is_dir(old_dentry)) { |
1da177e4 LT |
4266 | error = -ENOTDIR; |
4267 | if (oldnd.last.name[oldnd.last.len]) | |
0a7c3937 | 4268 | goto exit5; |
da1ce067 | 4269 | if (!(flags & RENAME_EXCHANGE) && newnd.last.name[newnd.last.len]) |
0a7c3937 | 4270 | goto exit5; |
1da177e4 LT |
4271 | } |
4272 | /* source should not be ancestor of target */ | |
4273 | error = -EINVAL; | |
4274 | if (old_dentry == trap) | |
0a7c3937 | 4275 | goto exit5; |
1da177e4 | 4276 | /* target should not be an ancestor of source */ |
da1ce067 MS |
4277 | if (!(flags & RENAME_EXCHANGE)) |
4278 | error = -ENOTEMPTY; | |
1da177e4 LT |
4279 | if (new_dentry == trap) |
4280 | goto exit5; | |
4281 | ||
be6d3e56 | 4282 | error = security_path_rename(&oldnd.path, old_dentry, |
0b3974eb | 4283 | &newnd.path, new_dentry, flags); |
be6d3e56 | 4284 | if (error) |
c30dabfe | 4285 | goto exit5; |
1da177e4 | 4286 | error = vfs_rename(old_dir->d_inode, old_dentry, |
520c8b16 MS |
4287 | new_dir->d_inode, new_dentry, |
4288 | &delegated_inode, flags); | |
1da177e4 LT |
4289 | exit5: |
4290 | dput(new_dentry); | |
4291 | exit4: | |
4292 | dput(old_dentry); | |
4293 | exit3: | |
4294 | unlock_rename(new_dir, old_dir); | |
8e6d782c BF |
4295 | if (delegated_inode) { |
4296 | error = break_deleg_wait(&delegated_inode); | |
4297 | if (!error) | |
4298 | goto retry_deleg; | |
4299 | } | |
c30dabfe | 4300 | mnt_drop_write(oldnd.path.mnt); |
1da177e4 | 4301 | exit2: |
c6a94284 JL |
4302 | if (retry_estale(error, lookup_flags)) |
4303 | should_retry = true; | |
1d957f9b | 4304 | path_put(&newnd.path); |
2ad94ae6 | 4305 | putname(to); |
1da177e4 | 4306 | exit1: |
1d957f9b | 4307 | path_put(&oldnd.path); |
1da177e4 | 4308 | putname(from); |
c6a94284 JL |
4309 | if (should_retry) { |
4310 | should_retry = false; | |
4311 | lookup_flags |= LOOKUP_REVAL; | |
4312 | goto retry; | |
4313 | } | |
2ad94ae6 | 4314 | exit: |
1da177e4 LT |
4315 | return error; |
4316 | } | |
4317 | ||
520c8b16 MS |
4318 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
4319 | int, newdfd, const char __user *, newname) | |
4320 | { | |
4321 | return sys_renameat2(olddfd, oldname, newdfd, newname, 0); | |
4322 | } | |
4323 | ||
a26eab24 | 4324 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 4325 | { |
520c8b16 | 4326 | return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
4327 | } |
4328 | ||
5d826c84 | 4329 | int readlink_copy(char __user *buffer, int buflen, const char *link) |
1da177e4 | 4330 | { |
5d826c84 | 4331 | int len = PTR_ERR(link); |
1da177e4 LT |
4332 | if (IS_ERR(link)) |
4333 | goto out; | |
4334 | ||
4335 | len = strlen(link); | |
4336 | if (len > (unsigned) buflen) | |
4337 | len = buflen; | |
4338 | if (copy_to_user(buffer, link, len)) | |
4339 | len = -EFAULT; | |
4340 | out: | |
4341 | return len; | |
4342 | } | |
5d826c84 | 4343 | EXPORT_SYMBOL(readlink_copy); |
1da177e4 LT |
4344 | |
4345 | /* | |
4346 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
4347 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
4348 | * using) it for any given inode is up to filesystem. | |
4349 | */ | |
4350 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4351 | { | |
4352 | struct nameidata nd; | |
cc314eef | 4353 | void *cookie; |
694a1764 | 4354 | int res; |
cc314eef | 4355 | |
1da177e4 | 4356 | nd.depth = 0; |
cc314eef | 4357 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
694a1764 MS |
4358 | if (IS_ERR(cookie)) |
4359 | return PTR_ERR(cookie); | |
4360 | ||
5d826c84 | 4361 | res = readlink_copy(buffer, buflen, nd_get_link(&nd)); |
694a1764 MS |
4362 | if (dentry->d_inode->i_op->put_link) |
4363 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); | |
4364 | return res; | |
1da177e4 | 4365 | } |
4d359507 | 4366 | EXPORT_SYMBOL(generic_readlink); |
1da177e4 | 4367 | |
1da177e4 LT |
4368 | /* get the link contents into pagecache */ |
4369 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
4370 | { | |
ebd09abb DG |
4371 | char *kaddr; |
4372 | struct page *page; | |
1da177e4 | 4373 | struct address_space *mapping = dentry->d_inode->i_mapping; |
090d2b18 | 4374 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 4375 | if (IS_ERR(page)) |
6fe6900e | 4376 | return (char*)page; |
1da177e4 | 4377 | *ppage = page; |
ebd09abb DG |
4378 | kaddr = kmap(page); |
4379 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); | |
4380 | return kaddr; | |
1da177e4 LT |
4381 | } |
4382 | ||
4383 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4384 | { | |
4385 | struct page *page = NULL; | |
5d826c84 | 4386 | int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); |
1da177e4 LT |
4387 | if (page) { |
4388 | kunmap(page); | |
4389 | page_cache_release(page); | |
4390 | } | |
4391 | return res; | |
4392 | } | |
4d359507 | 4393 | EXPORT_SYMBOL(page_readlink); |
1da177e4 | 4394 | |
cc314eef | 4395 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
1da177e4 | 4396 | { |
cc314eef | 4397 | struct page *page = NULL; |
1da177e4 | 4398 | nd_set_link(nd, page_getlink(dentry, &page)); |
cc314eef | 4399 | return page; |
1da177e4 | 4400 | } |
4d359507 | 4401 | EXPORT_SYMBOL(page_follow_link_light); |
1da177e4 | 4402 | |
cc314eef | 4403 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1da177e4 | 4404 | { |
cc314eef LT |
4405 | struct page *page = cookie; |
4406 | ||
4407 | if (page) { | |
1da177e4 LT |
4408 | kunmap(page); |
4409 | page_cache_release(page); | |
1da177e4 LT |
4410 | } |
4411 | } | |
4d359507 | 4412 | EXPORT_SYMBOL(page_put_link); |
1da177e4 | 4413 | |
54566b2c NP |
4414 | /* |
4415 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
4416 | */ | |
4417 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
4418 | { |
4419 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 4420 | struct page *page; |
afddba49 | 4421 | void *fsdata; |
beb497ab | 4422 | int err; |
1da177e4 | 4423 | char *kaddr; |
54566b2c NP |
4424 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
4425 | if (nofs) | |
4426 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 4427 | |
7e53cac4 | 4428 | retry: |
afddba49 | 4429 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 4430 | flags, &page, &fsdata); |
1da177e4 | 4431 | if (err) |
afddba49 NP |
4432 | goto fail; |
4433 | ||
e8e3c3d6 | 4434 | kaddr = kmap_atomic(page); |
1da177e4 | 4435 | memcpy(kaddr, symname, len-1); |
e8e3c3d6 | 4436 | kunmap_atomic(kaddr); |
afddba49 NP |
4437 | |
4438 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
4439 | page, fsdata); | |
1da177e4 LT |
4440 | if (err < 0) |
4441 | goto fail; | |
afddba49 NP |
4442 | if (err < len-1) |
4443 | goto retry; | |
4444 | ||
1da177e4 LT |
4445 | mark_inode_dirty(inode); |
4446 | return 0; | |
1da177e4 LT |
4447 | fail: |
4448 | return err; | |
4449 | } | |
4d359507 | 4450 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 | 4451 | |
0adb25d2 KK |
4452 | int page_symlink(struct inode *inode, const char *symname, int len) |
4453 | { | |
4454 | return __page_symlink(inode, symname, len, | |
54566b2c | 4455 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
0adb25d2 | 4456 | } |
4d359507 | 4457 | EXPORT_SYMBOL(page_symlink); |
0adb25d2 | 4458 | |
92e1d5be | 4459 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
4460 | .readlink = generic_readlink, |
4461 | .follow_link = page_follow_link_light, | |
4462 | .put_link = page_put_link, | |
4463 | }; | |
1da177e4 | 4464 | EXPORT_SYMBOL(page_symlink_inode_operations); |