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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/namei.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * Some corrections by tytso. | |
9 | */ | |
10 | ||
11 | /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname | |
12 | * lookup logic. | |
13 | */ | |
14 | /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. | |
15 | */ | |
16 | ||
17 | #include <linux/init.h> | |
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> |
99d263d4 | 37 | #include <linux/hash.h> |
1da177e4 LT |
38 | #include <asm/uaccess.h> |
39 | ||
e81e3f4d | 40 | #include "internal.h" |
c7105365 | 41 | #include "mount.h" |
e81e3f4d | 42 | |
1da177e4 LT |
43 | /* [Feb-1997 T. Schoebel-Theuer] |
44 | * Fundamental changes in the pathname lookup mechanisms (namei) | |
45 | * were necessary because of omirr. The reason is that omirr needs | |
46 | * to know the _real_ pathname, not the user-supplied one, in case | |
47 | * of symlinks (and also when transname replacements occur). | |
48 | * | |
49 | * The new code replaces the old recursive symlink resolution with | |
50 | * an iterative one (in case of non-nested symlink chains). It does | |
51 | * this with calls to <fs>_follow_link(). | |
52 | * As a side effect, dir_namei(), _namei() and follow_link() are now | |
53 | * replaced with a single function lookup_dentry() that can handle all | |
54 | * the special cases of the former code. | |
55 | * | |
56 | * With the new dcache, the pathname is stored at each inode, at least as | |
57 | * long as the refcount of the inode is positive. As a side effect, the | |
58 | * size of the dcache depends on the inode cache and thus is dynamic. | |
59 | * | |
60 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink | |
61 | * resolution to correspond with current state of the code. | |
62 | * | |
63 | * Note that the symlink resolution is not *completely* iterative. | |
64 | * There is still a significant amount of tail- and mid- recursion in | |
65 | * the algorithm. Also, note that <fs>_readlink() is not used in | |
66 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() | |
67 | * may return different results than <fs>_follow_link(). Many virtual | |
68 | * filesystems (including /proc) exhibit this behavior. | |
69 | */ | |
70 | ||
71 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: | |
72 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL | |
73 | * and the name already exists in form of a symlink, try to create the new | |
74 | * name indicated by the symlink. The old code always complained that the | |
75 | * name already exists, due to not following the symlink even if its target | |
76 | * is nonexistent. The new semantics affects also mknod() and link() when | |
25985edc | 77 | * the name is a symlink pointing to a non-existent name. |
1da177e4 LT |
78 | * |
79 | * I don't know which semantics is the right one, since I have no access | |
80 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" | |
81 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the | |
82 | * "old" one. Personally, I think the new semantics is much more logical. | |
83 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing | |
84 | * file does succeed in both HP-UX and SunOs, but not in Solaris | |
85 | * and in the old Linux semantics. | |
86 | */ | |
87 | ||
88 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink | |
89 | * semantics. See the comments in "open_namei" and "do_link" below. | |
90 | * | |
91 | * [10-Sep-98 Alan Modra] Another symlink change. | |
92 | */ | |
93 | ||
94 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: | |
95 | * inside the path - always follow. | |
96 | * in the last component in creation/removal/renaming - never follow. | |
97 | * if LOOKUP_FOLLOW passed - follow. | |
98 | * if the pathname has trailing slashes - follow. | |
99 | * otherwise - don't follow. | |
100 | * (applied in that order). | |
101 | * | |
102 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT | |
103 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. | |
104 | * During the 2.4 we need to fix the userland stuff depending on it - | |
105 | * hopefully we will be able to get rid of that wart in 2.5. So far only | |
106 | * XEmacs seems to be relying on it... | |
107 | */ | |
108 | /* | |
109 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) | |
a11f3a05 | 110 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
1da177e4 LT |
111 | * any extra contention... |
112 | */ | |
113 | ||
114 | /* In order to reduce some races, while at the same time doing additional | |
115 | * checking and hopefully speeding things up, we copy filenames to the | |
116 | * kernel data space before using them.. | |
117 | * | |
118 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). | |
119 | * PATH_MAX includes the nul terminator --RR. | |
120 | */ | |
91a27b2a | 121 | |
fd2f7cb5 | 122 | #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) |
7950e385 | 123 | |
51f39a1f | 124 | struct filename * |
91a27b2a JL |
125 | getname_flags(const char __user *filename, int flags, int *empty) |
126 | { | |
94b5d262 | 127 | struct filename *result; |
7950e385 | 128 | char *kname; |
94b5d262 | 129 | int len; |
4043cde8 | 130 | |
7ac86265 JL |
131 | result = audit_reusename(filename); |
132 | if (result) | |
133 | return result; | |
134 | ||
7950e385 | 135 | result = __getname(); |
3f9f0aa6 | 136 | if (unlikely(!result)) |
4043cde8 EP |
137 | return ERR_PTR(-ENOMEM); |
138 | ||
7950e385 JL |
139 | /* |
140 | * First, try to embed the struct filename inside the names_cache | |
141 | * allocation | |
142 | */ | |
fd2f7cb5 | 143 | kname = (char *)result->iname; |
91a27b2a | 144 | result->name = kname; |
7950e385 | 145 | |
94b5d262 | 146 | len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); |
91a27b2a | 147 | if (unlikely(len < 0)) { |
94b5d262 AV |
148 | __putname(result); |
149 | return ERR_PTR(len); | |
91a27b2a | 150 | } |
3f9f0aa6 | 151 | |
7950e385 JL |
152 | /* |
153 | * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a | |
154 | * separate struct filename so we can dedicate the entire | |
155 | * names_cache allocation for the pathname, and re-do the copy from | |
156 | * userland. | |
157 | */ | |
94b5d262 | 158 | if (unlikely(len == EMBEDDED_NAME_MAX)) { |
fd2f7cb5 | 159 | const size_t size = offsetof(struct filename, iname[1]); |
7950e385 JL |
160 | kname = (char *)result; |
161 | ||
fd2f7cb5 AV |
162 | /* |
163 | * size is chosen that way we to guarantee that | |
164 | * result->iname[0] is within the same object and that | |
165 | * kname can't be equal to result->iname, no matter what. | |
166 | */ | |
167 | result = kzalloc(size, GFP_KERNEL); | |
94b5d262 AV |
168 | if (unlikely(!result)) { |
169 | __putname(kname); | |
170 | return ERR_PTR(-ENOMEM); | |
7950e385 JL |
171 | } |
172 | result->name = kname; | |
94b5d262 AV |
173 | len = strncpy_from_user(kname, filename, PATH_MAX); |
174 | if (unlikely(len < 0)) { | |
175 | __putname(kname); | |
176 | kfree(result); | |
177 | return ERR_PTR(len); | |
178 | } | |
179 | if (unlikely(len == PATH_MAX)) { | |
180 | __putname(kname); | |
181 | kfree(result); | |
182 | return ERR_PTR(-ENAMETOOLONG); | |
183 | } | |
7950e385 JL |
184 | } |
185 | ||
94b5d262 | 186 | result->refcnt = 1; |
3f9f0aa6 LT |
187 | /* The empty path is special. */ |
188 | if (unlikely(!len)) { | |
189 | if (empty) | |
4043cde8 | 190 | *empty = 1; |
94b5d262 AV |
191 | if (!(flags & LOOKUP_EMPTY)) { |
192 | putname(result); | |
193 | return ERR_PTR(-ENOENT); | |
194 | } | |
1da177e4 | 195 | } |
3f9f0aa6 | 196 | |
7950e385 | 197 | result->uptr = filename; |
c4ad8f98 | 198 | result->aname = NULL; |
7950e385 JL |
199 | audit_getname(result); |
200 | return result; | |
1da177e4 LT |
201 | } |
202 | ||
91a27b2a JL |
203 | struct filename * |
204 | getname(const char __user * filename) | |
f52e0c11 | 205 | { |
f7493e5d | 206 | return getname_flags(filename, 0, NULL); |
f52e0c11 AV |
207 | } |
208 | ||
c4ad8f98 LT |
209 | struct filename * |
210 | getname_kernel(const char * filename) | |
211 | { | |
212 | struct filename *result; | |
08518549 | 213 | int len = strlen(filename) + 1; |
c4ad8f98 LT |
214 | |
215 | result = __getname(); | |
216 | if (unlikely(!result)) | |
217 | return ERR_PTR(-ENOMEM); | |
218 | ||
08518549 | 219 | if (len <= EMBEDDED_NAME_MAX) { |
fd2f7cb5 | 220 | result->name = (char *)result->iname; |
08518549 PM |
221 | } else if (len <= PATH_MAX) { |
222 | struct filename *tmp; | |
223 | ||
224 | tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); | |
225 | if (unlikely(!tmp)) { | |
226 | __putname(result); | |
227 | return ERR_PTR(-ENOMEM); | |
228 | } | |
229 | tmp->name = (char *)result; | |
08518549 PM |
230 | result = tmp; |
231 | } else { | |
232 | __putname(result); | |
233 | return ERR_PTR(-ENAMETOOLONG); | |
234 | } | |
235 | memcpy((char *)result->name, filename, len); | |
c4ad8f98 LT |
236 | result->uptr = NULL; |
237 | result->aname = NULL; | |
55422d0b | 238 | result->refcnt = 1; |
fd3522fd | 239 | audit_getname(result); |
c4ad8f98 | 240 | |
c4ad8f98 LT |
241 | return result; |
242 | } | |
243 | ||
91a27b2a | 244 | void putname(struct filename *name) |
1da177e4 | 245 | { |
55422d0b PM |
246 | BUG_ON(name->refcnt <= 0); |
247 | ||
248 | if (--name->refcnt > 0) | |
249 | return; | |
250 | ||
fd2f7cb5 | 251 | if (name->name != name->iname) { |
55422d0b PM |
252 | __putname(name->name); |
253 | kfree(name); | |
254 | } else | |
255 | __putname(name); | |
1da177e4 | 256 | } |
1da177e4 | 257 | |
e77819e5 LT |
258 | static int check_acl(struct inode *inode, int mask) |
259 | { | |
84635d68 | 260 | #ifdef CONFIG_FS_POSIX_ACL |
e77819e5 LT |
261 | struct posix_acl *acl; |
262 | ||
e77819e5 | 263 | if (mask & MAY_NOT_BLOCK) { |
3567866b AV |
264 | acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); |
265 | if (!acl) | |
e77819e5 | 266 | return -EAGAIN; |
3567866b AV |
267 | /* no ->get_acl() calls in RCU mode... */ |
268 | if (acl == ACL_NOT_CACHED) | |
269 | return -ECHILD; | |
206b1d09 | 270 | return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); |
e77819e5 LT |
271 | } |
272 | ||
2982baa2 CH |
273 | acl = get_acl(inode, ACL_TYPE_ACCESS); |
274 | if (IS_ERR(acl)) | |
275 | return PTR_ERR(acl); | |
e77819e5 LT |
276 | if (acl) { |
277 | int error = posix_acl_permission(inode, acl, mask); | |
278 | posix_acl_release(acl); | |
279 | return error; | |
280 | } | |
84635d68 | 281 | #endif |
e77819e5 LT |
282 | |
283 | return -EAGAIN; | |
284 | } | |
285 | ||
5909ccaa | 286 | /* |
948409c7 | 287 | * This does the basic permission checking |
1da177e4 | 288 | */ |
7e40145e | 289 | static int acl_permission_check(struct inode *inode, int mask) |
1da177e4 | 290 | { |
26cf46be | 291 | unsigned int mode = inode->i_mode; |
1da177e4 | 292 | |
8e96e3b7 | 293 | if (likely(uid_eq(current_fsuid(), inode->i_uid))) |
1da177e4 LT |
294 | mode >>= 6; |
295 | else { | |
e77819e5 | 296 | if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { |
7e40145e | 297 | int error = check_acl(inode, mask); |
b74c79e9 NP |
298 | if (error != -EAGAIN) |
299 | return error; | |
1da177e4 LT |
300 | } |
301 | ||
302 | if (in_group_p(inode->i_gid)) | |
303 | mode >>= 3; | |
304 | } | |
305 | ||
306 | /* | |
307 | * If the DACs are ok we don't need any capability check. | |
308 | */ | |
9c2c7039 | 309 | if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) |
1da177e4 | 310 | return 0; |
5909ccaa LT |
311 | return -EACCES; |
312 | } | |
313 | ||
314 | /** | |
b74c79e9 | 315 | * generic_permission - check for access rights on a Posix-like filesystem |
5909ccaa | 316 | * @inode: inode to check access rights for |
8fd90c8d | 317 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) |
5909ccaa LT |
318 | * |
319 | * Used to check for read/write/execute permissions on a file. | |
320 | * We use "fsuid" for this, letting us set arbitrary permissions | |
321 | * for filesystem access without changing the "normal" uids which | |
b74c79e9 NP |
322 | * are used for other things. |
323 | * | |
324 | * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk | |
325 | * request cannot be satisfied (eg. requires blocking or too much complexity). | |
326 | * It would then be called again in ref-walk mode. | |
5909ccaa | 327 | */ |
2830ba7f | 328 | int generic_permission(struct inode *inode, int mask) |
5909ccaa LT |
329 | { |
330 | int ret; | |
331 | ||
332 | /* | |
948409c7 | 333 | * Do the basic permission checks. |
5909ccaa | 334 | */ |
7e40145e | 335 | ret = acl_permission_check(inode, mask); |
5909ccaa LT |
336 | if (ret != -EACCES) |
337 | return ret; | |
1da177e4 | 338 | |
d594e7ec AV |
339 | if (S_ISDIR(inode->i_mode)) { |
340 | /* DACs are overridable for directories */ | |
23adbe12 | 341 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) |
d594e7ec AV |
342 | return 0; |
343 | if (!(mask & MAY_WRITE)) | |
23adbe12 AL |
344 | if (capable_wrt_inode_uidgid(inode, |
345 | CAP_DAC_READ_SEARCH)) | |
d594e7ec AV |
346 | return 0; |
347 | return -EACCES; | |
348 | } | |
1da177e4 LT |
349 | /* |
350 | * Read/write DACs are always overridable. | |
d594e7ec AV |
351 | * Executable DACs are overridable when there is |
352 | * at least one exec bit set. | |
1da177e4 | 353 | */ |
d594e7ec | 354 | if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) |
23adbe12 | 355 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) |
1da177e4 LT |
356 | return 0; |
357 | ||
358 | /* | |
359 | * Searching includes executable on directories, else just read. | |
360 | */ | |
7ea66001 | 361 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
d594e7ec | 362 | if (mask == MAY_READ) |
23adbe12 | 363 | if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) |
1da177e4 LT |
364 | return 0; |
365 | ||
366 | return -EACCES; | |
367 | } | |
4d359507 | 368 | EXPORT_SYMBOL(generic_permission); |
1da177e4 | 369 | |
3ddcd056 LT |
370 | /* |
371 | * We _really_ want to just do "generic_permission()" without | |
372 | * even looking at the inode->i_op values. So we keep a cache | |
373 | * flag in inode->i_opflags, that says "this has not special | |
374 | * permission function, use the fast case". | |
375 | */ | |
376 | static inline int do_inode_permission(struct inode *inode, int mask) | |
377 | { | |
378 | if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { | |
379 | if (likely(inode->i_op->permission)) | |
380 | return inode->i_op->permission(inode, mask); | |
381 | ||
382 | /* This gets set once for the inode lifetime */ | |
383 | spin_lock(&inode->i_lock); | |
384 | inode->i_opflags |= IOP_FASTPERM; | |
385 | spin_unlock(&inode->i_lock); | |
386 | } | |
387 | return generic_permission(inode, mask); | |
388 | } | |
389 | ||
cb23beb5 | 390 | /** |
0bdaea90 DH |
391 | * __inode_permission - Check for access rights to a given inode |
392 | * @inode: Inode to check permission on | |
393 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
cb23beb5 | 394 | * |
0bdaea90 | 395 | * Check for read/write/execute permissions on an inode. |
948409c7 AG |
396 | * |
397 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
0bdaea90 DH |
398 | * |
399 | * This does not check for a read-only file system. You probably want | |
400 | * inode_permission(). | |
cb23beb5 | 401 | */ |
0bdaea90 | 402 | int __inode_permission(struct inode *inode, int mask) |
1da177e4 | 403 | { |
e6305c43 | 404 | int retval; |
1da177e4 | 405 | |
3ddcd056 | 406 | if (unlikely(mask & MAY_WRITE)) { |
1da177e4 LT |
407 | /* |
408 | * Nobody gets write access to an immutable file. | |
409 | */ | |
410 | if (IS_IMMUTABLE(inode)) | |
411 | return -EACCES; | |
412 | } | |
413 | ||
3ddcd056 | 414 | retval = do_inode_permission(inode, mask); |
1da177e4 LT |
415 | if (retval) |
416 | return retval; | |
417 | ||
08ce5f16 SH |
418 | retval = devcgroup_inode_permission(inode, mask); |
419 | if (retval) | |
420 | return retval; | |
421 | ||
d09ca739 | 422 | return security_inode_permission(inode, mask); |
1da177e4 | 423 | } |
bd5d0856 | 424 | EXPORT_SYMBOL(__inode_permission); |
1da177e4 | 425 | |
0bdaea90 DH |
426 | /** |
427 | * sb_permission - Check superblock-level permissions | |
428 | * @sb: Superblock of inode to check permission on | |
55852635 | 429 | * @inode: Inode to check permission on |
0bdaea90 DH |
430 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
431 | * | |
432 | * Separate out file-system wide checks from inode-specific permission checks. | |
433 | */ | |
434 | static int sb_permission(struct super_block *sb, struct inode *inode, int mask) | |
435 | { | |
436 | if (unlikely(mask & MAY_WRITE)) { | |
437 | umode_t mode = inode->i_mode; | |
438 | ||
439 | /* Nobody gets write access to a read-only fs. */ | |
440 | if ((sb->s_flags & MS_RDONLY) && | |
441 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) | |
442 | return -EROFS; | |
443 | } | |
444 | return 0; | |
445 | } | |
446 | ||
447 | /** | |
448 | * inode_permission - Check for access rights to a given inode | |
449 | * @inode: Inode to check permission on | |
450 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
451 | * | |
452 | * Check for read/write/execute permissions on an inode. We use fs[ug]id for | |
453 | * this, letting us set arbitrary permissions for filesystem access without | |
454 | * changing the "normal" UIDs which are used for other things. | |
455 | * | |
456 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. | |
457 | */ | |
458 | int inode_permission(struct inode *inode, int mask) | |
459 | { | |
460 | int retval; | |
461 | ||
462 | retval = sb_permission(inode->i_sb, inode, mask); | |
463 | if (retval) | |
464 | return retval; | |
465 | return __inode_permission(inode, mask); | |
466 | } | |
4d359507 | 467 | EXPORT_SYMBOL(inode_permission); |
0bdaea90 | 468 | |
5dd784d0 JB |
469 | /** |
470 | * path_get - get a reference to a path | |
471 | * @path: path to get the reference to | |
472 | * | |
473 | * Given a path increment the reference count to the dentry and the vfsmount. | |
474 | */ | |
dcf787f3 | 475 | void path_get(const struct path *path) |
5dd784d0 JB |
476 | { |
477 | mntget(path->mnt); | |
478 | dget(path->dentry); | |
479 | } | |
480 | EXPORT_SYMBOL(path_get); | |
481 | ||
1d957f9b JB |
482 | /** |
483 | * path_put - put a reference to a path | |
484 | * @path: path to put the reference to | |
485 | * | |
486 | * Given a path decrement the reference count to the dentry and the vfsmount. | |
487 | */ | |
dcf787f3 | 488 | void path_put(const struct path *path) |
1da177e4 | 489 | { |
1d957f9b JB |
490 | dput(path->dentry); |
491 | mntput(path->mnt); | |
1da177e4 | 492 | } |
1d957f9b | 493 | EXPORT_SYMBOL(path_put); |
1da177e4 | 494 | |
894bc8c4 | 495 | #define EMBEDDED_LEVELS 2 |
1f55a6ec AV |
496 | struct nameidata { |
497 | struct path path; | |
1cf2665b | 498 | struct qstr last; |
1f55a6ec AV |
499 | struct path root; |
500 | struct inode *inode; /* path.dentry.d_inode */ | |
501 | unsigned int flags; | |
8f47a016 | 502 | unsigned seq, m_seq, root_seq; |
1f55a6ec AV |
503 | int last_type; |
504 | unsigned depth; | |
756daf26 | 505 | int total_link_count; |
697fc6ca AV |
506 | struct saved { |
507 | struct path link; | |
508 | void *cookie; | |
509 | const char *name; | |
237d8b32 | 510 | struct inode *inode; |
0450b2d1 | 511 | unsigned seq; |
894bc8c4 | 512 | } *stack, internal[EMBEDDED_LEVELS]; |
1f55a6ec AV |
513 | }; |
514 | ||
756daf26 | 515 | static struct nameidata *set_nameidata(struct nameidata *p) |
894bc8c4 | 516 | { |
756daf26 N |
517 | struct nameidata *old = current->nameidata; |
518 | p->stack = p->internal; | |
519 | p->total_link_count = old ? old->total_link_count : 0; | |
520 | current->nameidata = p; | |
521 | return old; | |
894bc8c4 AV |
522 | } |
523 | ||
756daf26 | 524 | static void restore_nameidata(struct nameidata *old) |
894bc8c4 | 525 | { |
756daf26 N |
526 | struct nameidata *now = current->nameidata; |
527 | ||
528 | current->nameidata = old; | |
529 | if (old) | |
530 | old->total_link_count = now->total_link_count; | |
531 | if (now->stack != now->internal) { | |
532 | kfree(now->stack); | |
533 | now->stack = now->internal; | |
894bc8c4 AV |
534 | } |
535 | } | |
536 | ||
537 | static int __nd_alloc_stack(struct nameidata *nd) | |
538 | { | |
bc40aee0 AV |
539 | struct saved *p; |
540 | ||
541 | if (nd->flags & LOOKUP_RCU) { | |
542 | p= kmalloc(MAXSYMLINKS * sizeof(struct saved), | |
543 | GFP_ATOMIC); | |
544 | if (unlikely(!p)) | |
545 | return -ECHILD; | |
546 | } else { | |
547 | p= kmalloc(MAXSYMLINKS * sizeof(struct saved), | |
894bc8c4 | 548 | GFP_KERNEL); |
bc40aee0 AV |
549 | if (unlikely(!p)) |
550 | return -ENOMEM; | |
551 | } | |
894bc8c4 AV |
552 | memcpy(p, nd->internal, sizeof(nd->internal)); |
553 | nd->stack = p; | |
554 | return 0; | |
555 | } | |
556 | ||
557 | static inline int nd_alloc_stack(struct nameidata *nd) | |
558 | { | |
da4e0be0 | 559 | if (likely(nd->depth != EMBEDDED_LEVELS)) |
894bc8c4 AV |
560 | return 0; |
561 | if (likely(nd->stack != nd->internal)) | |
562 | return 0; | |
563 | return __nd_alloc_stack(nd); | |
564 | } | |
565 | ||
7973387a AV |
566 | static void drop_links(struct nameidata *nd) |
567 | { | |
568 | int i = nd->depth; | |
569 | while (i--) { | |
570 | struct saved *last = nd->stack + i; | |
571 | struct inode *inode = last->inode; | |
572 | if (last->cookie && inode->i_op->put_link) { | |
573 | inode->i_op->put_link(inode, last->cookie); | |
574 | last->cookie = NULL; | |
575 | } | |
576 | } | |
577 | } | |
578 | ||
579 | static void terminate_walk(struct nameidata *nd) | |
580 | { | |
581 | drop_links(nd); | |
582 | if (!(nd->flags & LOOKUP_RCU)) { | |
583 | int i; | |
584 | path_put(&nd->path); | |
585 | for (i = 0; i < nd->depth; i++) | |
586 | path_put(&nd->stack[i].link); | |
587 | } else { | |
588 | nd->flags &= ~LOOKUP_RCU; | |
589 | if (!(nd->flags & LOOKUP_ROOT)) | |
590 | nd->root.mnt = NULL; | |
591 | rcu_read_unlock(); | |
592 | } | |
593 | nd->depth = 0; | |
594 | } | |
595 | ||
596 | /* path_put is needed afterwards regardless of success or failure */ | |
597 | static bool legitimize_path(struct nameidata *nd, | |
598 | struct path *path, unsigned seq) | |
599 | { | |
600 | int res = __legitimize_mnt(path->mnt, nd->m_seq); | |
601 | if (unlikely(res)) { | |
602 | if (res > 0) | |
603 | path->mnt = NULL; | |
604 | path->dentry = NULL; | |
605 | return false; | |
606 | } | |
607 | if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) { | |
608 | path->dentry = NULL; | |
609 | return false; | |
610 | } | |
611 | return !read_seqcount_retry(&path->dentry->d_seq, seq); | |
612 | } | |
613 | ||
614 | static bool legitimize_links(struct nameidata *nd) | |
615 | { | |
616 | int i; | |
617 | for (i = 0; i < nd->depth; i++) { | |
618 | struct saved *last = nd->stack + i; | |
619 | if (unlikely(!legitimize_path(nd, &last->link, last->seq))) { | |
620 | drop_links(nd); | |
621 | nd->depth = i + 1; | |
622 | return false; | |
623 | } | |
624 | } | |
625 | return true; | |
626 | } | |
627 | ||
19660af7 | 628 | /* |
31e6b01f | 629 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
19660af7 AV |
630 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
631 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab | |
632 | * normal reference counts on dentries and vfsmounts to transition to rcu-walk | |
633 | * mode. Refcounts are grabbed at the last known good point before rcu-walk | |
634 | * got stuck, so ref-walk may continue from there. If this is not successful | |
635 | * (eg. a seqcount has changed), then failure is returned and it's up to caller | |
636 | * to restart the path walk from the beginning in ref-walk mode. | |
31e6b01f | 637 | */ |
31e6b01f NP |
638 | |
639 | /** | |
19660af7 AV |
640 | * unlazy_walk - try to switch to ref-walk mode. |
641 | * @nd: nameidata pathwalk data | |
642 | * @dentry: child of nd->path.dentry or NULL | |
6e9918b7 | 643 | * @seq: seq number to check dentry against |
39191628 | 644 | * Returns: 0 on success, -ECHILD on failure |
31e6b01f | 645 | * |
19660af7 AV |
646 | * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry |
647 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on | |
648 | * @nd or NULL. Must be called from rcu-walk context. | |
7973387a AV |
649 | * Nothing should touch nameidata between unlazy_walk() failure and |
650 | * terminate_walk(). | |
31e6b01f | 651 | */ |
6e9918b7 | 652 | static int unlazy_walk(struct nameidata *nd, struct dentry *dentry, unsigned seq) |
31e6b01f | 653 | { |
31e6b01f NP |
654 | struct dentry *parent = nd->path.dentry; |
655 | ||
656 | BUG_ON(!(nd->flags & LOOKUP_RCU)); | |
e5c832d5 | 657 | |
e5c832d5 | 658 | nd->flags &= ~LOOKUP_RCU; |
7973387a AV |
659 | if (unlikely(!legitimize_links(nd))) |
660 | goto out2; | |
661 | if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq))) | |
662 | goto out2; | |
663 | if (unlikely(!lockref_get_not_dead(&parent->d_lockref))) | |
664 | goto out1; | |
48a066e7 | 665 | |
15570086 LT |
666 | /* |
667 | * For a negative lookup, the lookup sequence point is the parents | |
668 | * sequence point, and it only needs to revalidate the parent dentry. | |
669 | * | |
670 | * For a positive lookup, we need to move both the parent and the | |
671 | * dentry from the RCU domain to be properly refcounted. And the | |
672 | * sequence number in the dentry validates *both* dentry counters, | |
673 | * since we checked the sequence number of the parent after we got | |
674 | * the child sequence number. So we know the parent must still | |
675 | * be valid if the child sequence number is still valid. | |
676 | */ | |
19660af7 | 677 | if (!dentry) { |
e5c832d5 LT |
678 | if (read_seqcount_retry(&parent->d_seq, nd->seq)) |
679 | goto out; | |
19660af7 AV |
680 | BUG_ON(nd->inode != parent->d_inode); |
681 | } else { | |
e5c832d5 LT |
682 | if (!lockref_get_not_dead(&dentry->d_lockref)) |
683 | goto out; | |
6e9918b7 | 684 | if (read_seqcount_retry(&dentry->d_seq, seq)) |
e5c832d5 | 685 | goto drop_dentry; |
19660af7 | 686 | } |
e5c832d5 LT |
687 | |
688 | /* | |
689 | * Sequence counts matched. Now make sure that the root is | |
690 | * still valid and get it if required. | |
691 | */ | |
692 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { | |
5a8d87e8 AV |
693 | if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) { |
694 | rcu_read_unlock(); | |
695 | dput(dentry); | |
696 | return -ECHILD; | |
7973387a | 697 | } |
31e6b01f | 698 | } |
31e6b01f | 699 | |
8b61e74f | 700 | rcu_read_unlock(); |
31e6b01f | 701 | return 0; |
19660af7 | 702 | |
e5c832d5 | 703 | drop_dentry: |
8b61e74f | 704 | rcu_read_unlock(); |
15570086 | 705 | dput(dentry); |
d0d27277 | 706 | goto drop_root_mnt; |
7973387a AV |
707 | out2: |
708 | nd->path.mnt = NULL; | |
709 | out1: | |
710 | nd->path.dentry = NULL; | |
e5c832d5 | 711 | out: |
8b61e74f | 712 | rcu_read_unlock(); |
d0d27277 LT |
713 | drop_root_mnt: |
714 | if (!(nd->flags & LOOKUP_ROOT)) | |
715 | nd->root.mnt = NULL; | |
31e6b01f NP |
716 | return -ECHILD; |
717 | } | |
718 | ||
7973387a AV |
719 | static int unlazy_link(struct nameidata *nd, struct path *link, unsigned seq) |
720 | { | |
721 | if (unlikely(!legitimize_path(nd, link, seq))) { | |
722 | drop_links(nd); | |
723 | nd->depth = 0; | |
724 | nd->flags &= ~LOOKUP_RCU; | |
725 | nd->path.mnt = NULL; | |
726 | nd->path.dentry = NULL; | |
727 | if (!(nd->flags & LOOKUP_ROOT)) | |
728 | nd->root.mnt = NULL; | |
729 | rcu_read_unlock(); | |
730 | } else if (likely(unlazy_walk(nd, NULL, 0)) == 0) { | |
731 | return 0; | |
732 | } | |
733 | path_put(link); | |
734 | return -ECHILD; | |
735 | } | |
736 | ||
4ce16ef3 | 737 | static inline int d_revalidate(struct dentry *dentry, unsigned int flags) |
34286d66 | 738 | { |
4ce16ef3 | 739 | return dentry->d_op->d_revalidate(dentry, flags); |
34286d66 NP |
740 | } |
741 | ||
9f1fafee AV |
742 | /** |
743 | * complete_walk - successful completion of path walk | |
744 | * @nd: pointer nameidata | |
39159de2 | 745 | * |
9f1fafee AV |
746 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
747 | * Revalidate the final result, unless we'd already done that during | |
748 | * the path walk or the filesystem doesn't ask for it. Return 0 on | |
749 | * success, -error on failure. In case of failure caller does not | |
750 | * need to drop nd->path. | |
39159de2 | 751 | */ |
9f1fafee | 752 | static int complete_walk(struct nameidata *nd) |
39159de2 | 753 | { |
16c2cd71 | 754 | struct dentry *dentry = nd->path.dentry; |
39159de2 | 755 | int status; |
39159de2 | 756 | |
9f1fafee | 757 | if (nd->flags & LOOKUP_RCU) { |
9f1fafee AV |
758 | if (!(nd->flags & LOOKUP_ROOT)) |
759 | nd->root.mnt = NULL; | |
6e9918b7 | 760 | if (unlikely(unlazy_walk(nd, NULL, 0))) |
9f1fafee | 761 | return -ECHILD; |
9f1fafee AV |
762 | } |
763 | ||
16c2cd71 AV |
764 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
765 | return 0; | |
766 | ||
ecf3d1f1 | 767 | if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) |
39159de2 JL |
768 | return 0; |
769 | ||
ecf3d1f1 | 770 | status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); |
39159de2 JL |
771 | if (status > 0) |
772 | return 0; | |
773 | ||
16c2cd71 | 774 | if (!status) |
39159de2 | 775 | status = -ESTALE; |
16c2cd71 | 776 | |
39159de2 JL |
777 | return status; |
778 | } | |
779 | ||
18d8c860 | 780 | static void set_root(struct nameidata *nd) |
2a737871 | 781 | { |
7bd88377 | 782 | get_fs_root(current->fs, &nd->root); |
2a737871 AV |
783 | } |
784 | ||
18d8c860 | 785 | static unsigned set_root_rcu(struct nameidata *nd) |
31e6b01f | 786 | { |
7bd88377 | 787 | struct fs_struct *fs = current->fs; |
8f47a016 | 788 | unsigned seq; |
c28cc364 | 789 | |
7bd88377 AV |
790 | do { |
791 | seq = read_seqcount_begin(&fs->seq); | |
792 | nd->root = fs->root; | |
8f47a016 | 793 | nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq); |
7bd88377 | 794 | } while (read_seqcount_retry(&fs->seq, seq)); |
8f47a016 | 795 | return nd->root_seq; |
31e6b01f NP |
796 | } |
797 | ||
1d957f9b | 798 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
799 | { |
800 | dput(path->dentry); | |
4ac91378 | 801 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
802 | mntput(path->mnt); |
803 | } | |
804 | ||
7b9337aa NP |
805 | static inline void path_to_nameidata(const struct path *path, |
806 | struct nameidata *nd) | |
051d3812 | 807 | { |
31e6b01f NP |
808 | if (!(nd->flags & LOOKUP_RCU)) { |
809 | dput(nd->path.dentry); | |
810 | if (nd->path.mnt != path->mnt) | |
811 | mntput(nd->path.mnt); | |
9a229683 | 812 | } |
31e6b01f | 813 | nd->path.mnt = path->mnt; |
4ac91378 | 814 | nd->path.dentry = path->dentry; |
051d3812 IK |
815 | } |
816 | ||
b5fb63c1 CH |
817 | /* |
818 | * Helper to directly jump to a known parsed path from ->follow_link, | |
819 | * caller must have taken a reference to path beforehand. | |
820 | */ | |
6e77137b | 821 | void nd_jump_link(struct path *path) |
b5fb63c1 | 822 | { |
6e77137b | 823 | struct nameidata *nd = current->nameidata; |
b5fb63c1 CH |
824 | path_put(&nd->path); |
825 | ||
826 | nd->path = *path; | |
827 | nd->inode = nd->path.dentry->d_inode; | |
828 | nd->flags |= LOOKUP_JUMPED; | |
b5fb63c1 CH |
829 | } |
830 | ||
b9ff4429 | 831 | static inline void put_link(struct nameidata *nd) |
574197e0 | 832 | { |
21c3003d | 833 | struct saved *last = nd->stack + --nd->depth; |
237d8b32 | 834 | struct inode *inode = last->inode; |
b9ff4429 | 835 | if (last->cookie && inode->i_op->put_link) |
5f2c4179 | 836 | inode->i_op->put_link(inode, last->cookie); |
6548fae2 AV |
837 | if (!(nd->flags & LOOKUP_RCU)) |
838 | path_put(&last->link); | |
574197e0 AV |
839 | } |
840 | ||
561ec64a LT |
841 | int sysctl_protected_symlinks __read_mostly = 0; |
842 | int sysctl_protected_hardlinks __read_mostly = 0; | |
800179c9 KC |
843 | |
844 | /** | |
845 | * may_follow_link - Check symlink following for unsafe situations | |
55852635 | 846 | * @nd: nameidata pathwalk data |
800179c9 KC |
847 | * |
848 | * In the case of the sysctl_protected_symlinks sysctl being enabled, | |
849 | * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is | |
850 | * in a sticky world-writable directory. This is to protect privileged | |
851 | * processes from failing races against path names that may change out | |
852 | * from under them by way of other users creating malicious symlinks. | |
853 | * It will permit symlinks to be followed only when outside a sticky | |
854 | * world-writable directory, or when the uid of the symlink and follower | |
855 | * match, or when the directory owner matches the symlink's owner. | |
856 | * | |
857 | * Returns 0 if following the symlink is allowed, -ve on error. | |
858 | */ | |
fec2fa24 | 859 | static inline int may_follow_link(struct nameidata *nd) |
800179c9 KC |
860 | { |
861 | const struct inode *inode; | |
862 | const struct inode *parent; | |
863 | ||
864 | if (!sysctl_protected_symlinks) | |
865 | return 0; | |
866 | ||
867 | /* Allowed if owner and follower match. */ | |
237d8b32 | 868 | inode = nd->stack[0].inode; |
81abe27b | 869 | if (uid_eq(current_cred()->fsuid, inode->i_uid)) |
800179c9 KC |
870 | return 0; |
871 | ||
872 | /* Allowed if parent directory not sticky and world-writable. */ | |
873 | parent = nd->path.dentry->d_inode; | |
874 | if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) | |
875 | return 0; | |
876 | ||
877 | /* Allowed if parent directory and link owner match. */ | |
81abe27b | 878 | if (uid_eq(parent->i_uid, inode->i_uid)) |
800179c9 KC |
879 | return 0; |
880 | ||
31956502 AV |
881 | if (nd->flags & LOOKUP_RCU) |
882 | return -ECHILD; | |
883 | ||
1cf2665b | 884 | audit_log_link_denied("follow_link", &nd->stack[0].link); |
800179c9 KC |
885 | return -EACCES; |
886 | } | |
887 | ||
888 | /** | |
889 | * safe_hardlink_source - Check for safe hardlink conditions | |
890 | * @inode: the source inode to hardlink from | |
891 | * | |
892 | * Return false if at least one of the following conditions: | |
893 | * - inode is not a regular file | |
894 | * - inode is setuid | |
895 | * - inode is setgid and group-exec | |
896 | * - access failure for read and write | |
897 | * | |
898 | * Otherwise returns true. | |
899 | */ | |
900 | static bool safe_hardlink_source(struct inode *inode) | |
901 | { | |
902 | umode_t mode = inode->i_mode; | |
903 | ||
904 | /* Special files should not get pinned to the filesystem. */ | |
905 | if (!S_ISREG(mode)) | |
906 | return false; | |
907 | ||
908 | /* Setuid files should not get pinned to the filesystem. */ | |
909 | if (mode & S_ISUID) | |
910 | return false; | |
911 | ||
912 | /* Executable setgid files should not get pinned to the filesystem. */ | |
913 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) | |
914 | return false; | |
915 | ||
916 | /* Hardlinking to unreadable or unwritable sources is dangerous. */ | |
917 | if (inode_permission(inode, MAY_READ | MAY_WRITE)) | |
918 | return false; | |
919 | ||
920 | return true; | |
921 | } | |
922 | ||
923 | /** | |
924 | * may_linkat - Check permissions for creating a hardlink | |
925 | * @link: the source to hardlink from | |
926 | * | |
927 | * Block hardlink when all of: | |
928 | * - sysctl_protected_hardlinks enabled | |
929 | * - fsuid does not match inode | |
930 | * - hardlink source is unsafe (see safe_hardlink_source() above) | |
931 | * - not CAP_FOWNER | |
932 | * | |
933 | * Returns 0 if successful, -ve on error. | |
934 | */ | |
935 | static int may_linkat(struct path *link) | |
936 | { | |
937 | const struct cred *cred; | |
938 | struct inode *inode; | |
939 | ||
940 | if (!sysctl_protected_hardlinks) | |
941 | return 0; | |
942 | ||
943 | cred = current_cred(); | |
944 | inode = link->dentry->d_inode; | |
945 | ||
946 | /* Source inode owner (or CAP_FOWNER) can hardlink all they like, | |
947 | * otherwise, it must be a safe source. | |
948 | */ | |
81abe27b | 949 | if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || |
800179c9 KC |
950 | capable(CAP_FOWNER)) |
951 | return 0; | |
952 | ||
a51d9eaa | 953 | audit_log_link_denied("linkat", link); |
800179c9 KC |
954 | return -EPERM; |
955 | } | |
956 | ||
3b2e7f75 AV |
957 | static __always_inline |
958 | const char *get_link(struct nameidata *nd) | |
1da177e4 | 959 | { |
ab104923 | 960 | struct saved *last = nd->stack + nd->depth - 1; |
1cf2665b | 961 | struct dentry *dentry = last->link.dentry; |
237d8b32 | 962 | struct inode *inode = last->inode; |
6d7b5aae | 963 | int error; |
0a959df5 | 964 | const char *res; |
1da177e4 | 965 | |
8fa9dd24 N |
966 | if (!(nd->flags & LOOKUP_RCU)) { |
967 | touch_atime(&last->link); | |
968 | cond_resched(); | |
969 | } else if (atime_needs_update(&last->link, inode)) { | |
bc40aee0 AV |
970 | if (unlikely(unlazy_walk(nd, NULL, 0))) |
971 | return ERR_PTR(-ECHILD); | |
8fa9dd24 | 972 | touch_atime(&last->link); |
bc40aee0 | 973 | } |
574197e0 | 974 | |
bda0be7a N |
975 | error = security_inode_follow_link(dentry, inode, |
976 | nd->flags & LOOKUP_RCU); | |
977 | if (unlikely(error)) | |
6920a440 | 978 | return ERR_PTR(error); |
36f3b4f6 | 979 | |
86acdca1 | 980 | nd->last_type = LAST_BIND; |
d4dee48b AV |
981 | res = inode->i_link; |
982 | if (!res) { | |
8c1b4566 AV |
983 | if (nd->flags & LOOKUP_RCU) { |
984 | if (unlikely(unlazy_walk(nd, NULL, 0))) | |
985 | return ERR_PTR(-ECHILD); | |
986 | } | |
6e77137b | 987 | res = inode->i_op->follow_link(dentry, &last->cookie); |
fab51e8a | 988 | if (IS_ERR_OR_NULL(res)) { |
6920a440 | 989 | last->cookie = NULL; |
fab51e8a AV |
990 | return res; |
991 | } | |
992 | } | |
993 | if (*res == '/') { | |
8c1b4566 | 994 | if (nd->flags & LOOKUP_RCU) { |
8f47a016 AV |
995 | struct dentry *d; |
996 | if (!nd->root.mnt) | |
997 | set_root_rcu(nd); | |
998 | nd->path = nd->root; | |
999 | d = nd->path.dentry; | |
1000 | nd->inode = d->d_inode; | |
1001 | nd->seq = nd->root_seq; | |
1002 | if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq))) | |
8c1b4566 | 1003 | return ERR_PTR(-ECHILD); |
8f47a016 AV |
1004 | } else { |
1005 | if (!nd->root.mnt) | |
1006 | set_root(nd); | |
1007 | path_put(&nd->path); | |
1008 | nd->path = nd->root; | |
1009 | path_get(&nd->root); | |
1010 | nd->inode = nd->path.dentry->d_inode; | |
8c1b4566 | 1011 | } |
fab51e8a AV |
1012 | nd->flags |= LOOKUP_JUMPED; |
1013 | while (unlikely(*++res == '/')) | |
1014 | ; | |
1da177e4 | 1015 | } |
fab51e8a AV |
1016 | if (!*res) |
1017 | res = NULL; | |
0a959df5 AV |
1018 | return res; |
1019 | } | |
6d7b5aae | 1020 | |
f015f126 DH |
1021 | /* |
1022 | * follow_up - Find the mountpoint of path's vfsmount | |
1023 | * | |
1024 | * Given a path, find the mountpoint of its source file system. | |
1025 | * Replace @path with the path of the mountpoint in the parent mount. | |
1026 | * Up is towards /. | |
1027 | * | |
1028 | * Return 1 if we went up a level and 0 if we were already at the | |
1029 | * root. | |
1030 | */ | |
bab77ebf | 1031 | int follow_up(struct path *path) |
1da177e4 | 1032 | { |
0714a533 AV |
1033 | struct mount *mnt = real_mount(path->mnt); |
1034 | struct mount *parent; | |
1da177e4 | 1035 | struct dentry *mountpoint; |
99b7db7b | 1036 | |
48a066e7 | 1037 | read_seqlock_excl(&mount_lock); |
0714a533 | 1038 | parent = mnt->mnt_parent; |
3c0a6163 | 1039 | if (parent == mnt) { |
48a066e7 | 1040 | read_sequnlock_excl(&mount_lock); |
1da177e4 LT |
1041 | return 0; |
1042 | } | |
0714a533 | 1043 | mntget(&parent->mnt); |
a73324da | 1044 | mountpoint = dget(mnt->mnt_mountpoint); |
48a066e7 | 1045 | read_sequnlock_excl(&mount_lock); |
bab77ebf AV |
1046 | dput(path->dentry); |
1047 | path->dentry = mountpoint; | |
1048 | mntput(path->mnt); | |
0714a533 | 1049 | path->mnt = &parent->mnt; |
1da177e4 LT |
1050 | return 1; |
1051 | } | |
4d359507 | 1052 | EXPORT_SYMBOL(follow_up); |
1da177e4 | 1053 | |
b5c84bf6 | 1054 | /* |
9875cf80 DH |
1055 | * Perform an automount |
1056 | * - return -EISDIR to tell follow_managed() to stop and return the path we | |
1057 | * were called with. | |
1da177e4 | 1058 | */ |
756daf26 | 1059 | static int follow_automount(struct path *path, struct nameidata *nd, |
9875cf80 | 1060 | bool *need_mntput) |
31e6b01f | 1061 | { |
9875cf80 | 1062 | struct vfsmount *mnt; |
ea5b778a | 1063 | int err; |
9875cf80 DH |
1064 | |
1065 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) | |
1066 | return -EREMOTE; | |
1067 | ||
0ec26fd0 MS |
1068 | /* We don't want to mount if someone's just doing a stat - |
1069 | * unless they're stat'ing a directory and appended a '/' to | |
1070 | * the name. | |
1071 | * | |
1072 | * We do, however, want to mount if someone wants to open or | |
1073 | * create a file of any type under the mountpoint, wants to | |
1074 | * traverse through the mountpoint or wants to open the | |
1075 | * mounted directory. Also, autofs may mark negative dentries | |
1076 | * as being automount points. These will need the attentions | |
1077 | * of the daemon to instantiate them before they can be used. | |
9875cf80 | 1078 | */ |
756daf26 N |
1079 | if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
1080 | LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && | |
0ec26fd0 MS |
1081 | path->dentry->d_inode) |
1082 | return -EISDIR; | |
1083 | ||
756daf26 N |
1084 | nd->total_link_count++; |
1085 | if (nd->total_link_count >= 40) | |
9875cf80 DH |
1086 | return -ELOOP; |
1087 | ||
1088 | mnt = path->dentry->d_op->d_automount(path); | |
1089 | if (IS_ERR(mnt)) { | |
1090 | /* | |
1091 | * The filesystem is allowed to return -EISDIR here to indicate | |
1092 | * it doesn't want to automount. For instance, autofs would do | |
1093 | * this so that its userspace daemon can mount on this dentry. | |
1094 | * | |
1095 | * However, we can only permit this if it's a terminal point in | |
1096 | * the path being looked up; if it wasn't then the remainder of | |
1097 | * the path is inaccessible and we should say so. | |
1098 | */ | |
756daf26 | 1099 | if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT)) |
9875cf80 DH |
1100 | return -EREMOTE; |
1101 | return PTR_ERR(mnt); | |
31e6b01f | 1102 | } |
ea5b778a | 1103 | |
9875cf80 DH |
1104 | if (!mnt) /* mount collision */ |
1105 | return 0; | |
31e6b01f | 1106 | |
8aef1884 AV |
1107 | if (!*need_mntput) { |
1108 | /* lock_mount() may release path->mnt on error */ | |
1109 | mntget(path->mnt); | |
1110 | *need_mntput = true; | |
1111 | } | |
19a167af | 1112 | err = finish_automount(mnt, path); |
9875cf80 | 1113 | |
ea5b778a DH |
1114 | switch (err) { |
1115 | case -EBUSY: | |
1116 | /* Someone else made a mount here whilst we were busy */ | |
19a167af | 1117 | return 0; |
ea5b778a | 1118 | case 0: |
8aef1884 | 1119 | path_put(path); |
ea5b778a DH |
1120 | path->mnt = mnt; |
1121 | path->dentry = dget(mnt->mnt_root); | |
ea5b778a | 1122 | return 0; |
19a167af AV |
1123 | default: |
1124 | return err; | |
ea5b778a | 1125 | } |
19a167af | 1126 | |
463ffb2e AV |
1127 | } |
1128 | ||
9875cf80 DH |
1129 | /* |
1130 | * Handle a dentry that is managed in some way. | |
cc53ce53 | 1131 | * - Flagged for transit management (autofs) |
9875cf80 DH |
1132 | * - Flagged as mountpoint |
1133 | * - Flagged as automount point | |
1134 | * | |
1135 | * This may only be called in refwalk mode. | |
1136 | * | |
1137 | * Serialization is taken care of in namespace.c | |
1138 | */ | |
756daf26 | 1139 | static int follow_managed(struct path *path, struct nameidata *nd) |
1da177e4 | 1140 | { |
8aef1884 | 1141 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
9875cf80 DH |
1142 | unsigned managed; |
1143 | bool need_mntput = false; | |
8aef1884 | 1144 | int ret = 0; |
9875cf80 DH |
1145 | |
1146 | /* Given that we're not holding a lock here, we retain the value in a | |
1147 | * local variable for each dentry as we look at it so that we don't see | |
1148 | * the components of that value change under us */ | |
1149 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1150 | managed &= DCACHE_MANAGED_DENTRY, | |
1151 | unlikely(managed != 0)) { | |
cc53ce53 DH |
1152 | /* Allow the filesystem to manage the transit without i_mutex |
1153 | * being held. */ | |
1154 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1155 | BUG_ON(!path->dentry->d_op); | |
1156 | BUG_ON(!path->dentry->d_op->d_manage); | |
1aed3e42 | 1157 | ret = path->dentry->d_op->d_manage(path->dentry, false); |
cc53ce53 | 1158 | if (ret < 0) |
8aef1884 | 1159 | break; |
cc53ce53 DH |
1160 | } |
1161 | ||
9875cf80 DH |
1162 | /* Transit to a mounted filesystem. */ |
1163 | if (managed & DCACHE_MOUNTED) { | |
1164 | struct vfsmount *mounted = lookup_mnt(path); | |
1165 | if (mounted) { | |
1166 | dput(path->dentry); | |
1167 | if (need_mntput) | |
1168 | mntput(path->mnt); | |
1169 | path->mnt = mounted; | |
1170 | path->dentry = dget(mounted->mnt_root); | |
1171 | need_mntput = true; | |
1172 | continue; | |
1173 | } | |
1174 | ||
1175 | /* Something is mounted on this dentry in another | |
1176 | * namespace and/or whatever was mounted there in this | |
48a066e7 AV |
1177 | * namespace got unmounted before lookup_mnt() could |
1178 | * get it */ | |
9875cf80 DH |
1179 | } |
1180 | ||
1181 | /* Handle an automount point */ | |
1182 | if (managed & DCACHE_NEED_AUTOMOUNT) { | |
756daf26 | 1183 | ret = follow_automount(path, nd, &need_mntput); |
9875cf80 | 1184 | if (ret < 0) |
8aef1884 | 1185 | break; |
9875cf80 DH |
1186 | continue; |
1187 | } | |
1188 | ||
1189 | /* We didn't change the current path point */ | |
1190 | break; | |
1da177e4 | 1191 | } |
8aef1884 AV |
1192 | |
1193 | if (need_mntput && path->mnt == mnt) | |
1194 | mntput(path->mnt); | |
1195 | if (ret == -EISDIR) | |
1196 | ret = 0; | |
8402752e AV |
1197 | if (need_mntput) |
1198 | nd->flags |= LOOKUP_JUMPED; | |
1199 | if (unlikely(ret < 0)) | |
1200 | path_put_conditional(path, nd); | |
1201 | return ret; | |
1da177e4 LT |
1202 | } |
1203 | ||
cc53ce53 | 1204 | int follow_down_one(struct path *path) |
1da177e4 LT |
1205 | { |
1206 | struct vfsmount *mounted; | |
1207 | ||
1c755af4 | 1208 | mounted = lookup_mnt(path); |
1da177e4 | 1209 | if (mounted) { |
9393bd07 AV |
1210 | dput(path->dentry); |
1211 | mntput(path->mnt); | |
1212 | path->mnt = mounted; | |
1213 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
1214 | return 1; |
1215 | } | |
1216 | return 0; | |
1217 | } | |
4d359507 | 1218 | EXPORT_SYMBOL(follow_down_one); |
1da177e4 | 1219 | |
b8faf035 | 1220 | static inline int managed_dentry_rcu(struct dentry *dentry) |
62a7375e | 1221 | { |
b8faf035 N |
1222 | return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? |
1223 | dentry->d_op->d_manage(dentry, true) : 0; | |
62a7375e IK |
1224 | } |
1225 | ||
9875cf80 | 1226 | /* |
287548e4 AV |
1227 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
1228 | * we meet a managed dentry that would need blocking. | |
9875cf80 DH |
1229 | */ |
1230 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, | |
254cf582 | 1231 | struct inode **inode, unsigned *seqp) |
9875cf80 | 1232 | { |
62a7375e | 1233 | for (;;) { |
c7105365 | 1234 | struct mount *mounted; |
62a7375e IK |
1235 | /* |
1236 | * Don't forget we might have a non-mountpoint managed dentry | |
1237 | * that wants to block transit. | |
1238 | */ | |
b8faf035 N |
1239 | switch (managed_dentry_rcu(path->dentry)) { |
1240 | case -ECHILD: | |
1241 | default: | |
ab90911f | 1242 | return false; |
b8faf035 N |
1243 | case -EISDIR: |
1244 | return true; | |
1245 | case 0: | |
1246 | break; | |
1247 | } | |
62a7375e IK |
1248 | |
1249 | if (!d_mountpoint(path->dentry)) | |
b8faf035 | 1250 | return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); |
62a7375e | 1251 | |
474279dc | 1252 | mounted = __lookup_mnt(path->mnt, path->dentry); |
9875cf80 DH |
1253 | if (!mounted) |
1254 | break; | |
c7105365 AV |
1255 | path->mnt = &mounted->mnt; |
1256 | path->dentry = mounted->mnt.mnt_root; | |
a3fbbde7 | 1257 | nd->flags |= LOOKUP_JUMPED; |
254cf582 | 1258 | *seqp = read_seqcount_begin(&path->dentry->d_seq); |
59430262 LT |
1259 | /* |
1260 | * Update the inode too. We don't need to re-check the | |
1261 | * dentry sequence number here after this d_inode read, | |
1262 | * because a mount-point is always pinned. | |
1263 | */ | |
1264 | *inode = path->dentry->d_inode; | |
9875cf80 | 1265 | } |
f5be3e29 | 1266 | return !read_seqretry(&mount_lock, nd->m_seq) && |
b8faf035 | 1267 | !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); |
287548e4 AV |
1268 | } |
1269 | ||
31e6b01f NP |
1270 | static int follow_dotdot_rcu(struct nameidata *nd) |
1271 | { | |
4023bfc9 | 1272 | struct inode *inode = nd->inode; |
7bd88377 AV |
1273 | if (!nd->root.mnt) |
1274 | set_root_rcu(nd); | |
31e6b01f | 1275 | |
9875cf80 | 1276 | while (1) { |
aed434ad | 1277 | if (path_equal(&nd->path, &nd->root)) |
31e6b01f | 1278 | break; |
31e6b01f NP |
1279 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
1280 | struct dentry *old = nd->path.dentry; | |
1281 | struct dentry *parent = old->d_parent; | |
1282 | unsigned seq; | |
1283 | ||
4023bfc9 | 1284 | inode = parent->d_inode; |
31e6b01f | 1285 | seq = read_seqcount_begin(&parent->d_seq); |
aed434ad AV |
1286 | if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq))) |
1287 | return -ECHILD; | |
31e6b01f NP |
1288 | nd->path.dentry = parent; |
1289 | nd->seq = seq; | |
1290 | break; | |
aed434ad AV |
1291 | } else { |
1292 | struct mount *mnt = real_mount(nd->path.mnt); | |
1293 | struct mount *mparent = mnt->mnt_parent; | |
1294 | struct dentry *mountpoint = mnt->mnt_mountpoint; | |
1295 | struct inode *inode2 = mountpoint->d_inode; | |
1296 | unsigned seq = read_seqcount_begin(&mountpoint->d_seq); | |
1297 | if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) | |
1298 | return -ECHILD; | |
1299 | if (&mparent->mnt == nd->path.mnt) | |
1300 | break; | |
1301 | /* we know that mountpoint was pinned */ | |
1302 | nd->path.dentry = mountpoint; | |
1303 | nd->path.mnt = &mparent->mnt; | |
1304 | inode = inode2; | |
1305 | nd->seq = seq; | |
31e6b01f | 1306 | } |
31e6b01f | 1307 | } |
aed434ad | 1308 | while (unlikely(d_mountpoint(nd->path.dentry))) { |
b37199e6 AV |
1309 | struct mount *mounted; |
1310 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); | |
aed434ad AV |
1311 | if (unlikely(read_seqretry(&mount_lock, nd->m_seq))) |
1312 | return -ECHILD; | |
b37199e6 AV |
1313 | if (!mounted) |
1314 | break; | |
1315 | nd->path.mnt = &mounted->mnt; | |
1316 | nd->path.dentry = mounted->mnt.mnt_root; | |
4023bfc9 | 1317 | inode = nd->path.dentry->d_inode; |
b37199e6 | 1318 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); |
b37199e6 | 1319 | } |
4023bfc9 | 1320 | nd->inode = inode; |
31e6b01f NP |
1321 | return 0; |
1322 | } | |
1323 | ||
cc53ce53 DH |
1324 | /* |
1325 | * Follow down to the covering mount currently visible to userspace. At each | |
1326 | * point, the filesystem owning that dentry may be queried as to whether the | |
1327 | * caller is permitted to proceed or not. | |
cc53ce53 | 1328 | */ |
7cc90cc3 | 1329 | int follow_down(struct path *path) |
cc53ce53 DH |
1330 | { |
1331 | unsigned managed; | |
1332 | int ret; | |
1333 | ||
1334 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1335 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { | |
1336 | /* Allow the filesystem to manage the transit without i_mutex | |
1337 | * being held. | |
1338 | * | |
1339 | * We indicate to the filesystem if someone is trying to mount | |
1340 | * something here. This gives autofs the chance to deny anyone | |
1341 | * other than its daemon the right to mount on its | |
1342 | * superstructure. | |
1343 | * | |
1344 | * The filesystem may sleep at this point. | |
1345 | */ | |
1346 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1347 | BUG_ON(!path->dentry->d_op); | |
1348 | BUG_ON(!path->dentry->d_op->d_manage); | |
ab90911f | 1349 | ret = path->dentry->d_op->d_manage( |
1aed3e42 | 1350 | path->dentry, false); |
cc53ce53 DH |
1351 | if (ret < 0) |
1352 | return ret == -EISDIR ? 0 : ret; | |
1353 | } | |
1354 | ||
1355 | /* Transit to a mounted filesystem. */ | |
1356 | if (managed & DCACHE_MOUNTED) { | |
1357 | struct vfsmount *mounted = lookup_mnt(path); | |
1358 | if (!mounted) | |
1359 | break; | |
1360 | dput(path->dentry); | |
1361 | mntput(path->mnt); | |
1362 | path->mnt = mounted; | |
1363 | path->dentry = dget(mounted->mnt_root); | |
1364 | continue; | |
1365 | } | |
1366 | ||
1367 | /* Don't handle automount points here */ | |
1368 | break; | |
1369 | } | |
1370 | return 0; | |
1371 | } | |
4d359507 | 1372 | EXPORT_SYMBOL(follow_down); |
cc53ce53 | 1373 | |
9875cf80 DH |
1374 | /* |
1375 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() | |
1376 | */ | |
1377 | static void follow_mount(struct path *path) | |
1378 | { | |
1379 | while (d_mountpoint(path->dentry)) { | |
1380 | struct vfsmount *mounted = lookup_mnt(path); | |
1381 | if (!mounted) | |
1382 | break; | |
1383 | dput(path->dentry); | |
1384 | mntput(path->mnt); | |
1385 | path->mnt = mounted; | |
1386 | path->dentry = dget(mounted->mnt_root); | |
1387 | } | |
1388 | } | |
1389 | ||
31e6b01f | 1390 | static void follow_dotdot(struct nameidata *nd) |
1da177e4 | 1391 | { |
7bd88377 AV |
1392 | if (!nd->root.mnt) |
1393 | set_root(nd); | |
e518ddb7 | 1394 | |
1da177e4 | 1395 | while(1) { |
4ac91378 | 1396 | struct dentry *old = nd->path.dentry; |
1da177e4 | 1397 | |
2a737871 AV |
1398 | if (nd->path.dentry == nd->root.dentry && |
1399 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
1400 | break; |
1401 | } | |
4ac91378 | 1402 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
3088dd70 AV |
1403 | /* rare case of legitimate dget_parent()... */ |
1404 | nd->path.dentry = dget_parent(nd->path.dentry); | |
1da177e4 LT |
1405 | dput(old); |
1406 | break; | |
1407 | } | |
3088dd70 | 1408 | if (!follow_up(&nd->path)) |
1da177e4 | 1409 | break; |
1da177e4 | 1410 | } |
79ed0226 | 1411 | follow_mount(&nd->path); |
31e6b01f | 1412 | nd->inode = nd->path.dentry->d_inode; |
1da177e4 LT |
1413 | } |
1414 | ||
baa03890 | 1415 | /* |
bad61189 MS |
1416 | * This looks up the name in dcache, possibly revalidates the old dentry and |
1417 | * allocates a new one if not found or not valid. In the need_lookup argument | |
1418 | * returns whether i_op->lookup is necessary. | |
1419 | * | |
1420 | * dir->d_inode->i_mutex must be held | |
baa03890 | 1421 | */ |
bad61189 | 1422 | static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, |
201f956e | 1423 | unsigned int flags, bool *need_lookup) |
baa03890 | 1424 | { |
baa03890 | 1425 | struct dentry *dentry; |
bad61189 | 1426 | int error; |
baa03890 | 1427 | |
bad61189 MS |
1428 | *need_lookup = false; |
1429 | dentry = d_lookup(dir, name); | |
1430 | if (dentry) { | |
39e3c955 | 1431 | if (dentry->d_flags & DCACHE_OP_REVALIDATE) { |
201f956e | 1432 | error = d_revalidate(dentry, flags); |
bad61189 MS |
1433 | if (unlikely(error <= 0)) { |
1434 | if (error < 0) { | |
1435 | dput(dentry); | |
1436 | return ERR_PTR(error); | |
5542aa2f EB |
1437 | } else { |
1438 | d_invalidate(dentry); | |
bad61189 MS |
1439 | dput(dentry); |
1440 | dentry = NULL; | |
1441 | } | |
1442 | } | |
1443 | } | |
1444 | } | |
baa03890 | 1445 | |
bad61189 MS |
1446 | if (!dentry) { |
1447 | dentry = d_alloc(dir, name); | |
1448 | if (unlikely(!dentry)) | |
1449 | return ERR_PTR(-ENOMEM); | |
baa03890 | 1450 | |
bad61189 | 1451 | *need_lookup = true; |
baa03890 NP |
1452 | } |
1453 | return dentry; | |
1454 | } | |
1455 | ||
44396f4b | 1456 | /* |
13a2c3be BF |
1457 | * Call i_op->lookup on the dentry. The dentry must be negative and |
1458 | * unhashed. | |
bad61189 MS |
1459 | * |
1460 | * dir->d_inode->i_mutex must be held | |
44396f4b | 1461 | */ |
bad61189 | 1462 | static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, |
72bd866a | 1463 | unsigned int flags) |
44396f4b | 1464 | { |
44396f4b JB |
1465 | struct dentry *old; |
1466 | ||
1467 | /* Don't create child dentry for a dead directory. */ | |
bad61189 | 1468 | if (unlikely(IS_DEADDIR(dir))) { |
e188dc02 | 1469 | dput(dentry); |
44396f4b | 1470 | return ERR_PTR(-ENOENT); |
e188dc02 | 1471 | } |
44396f4b | 1472 | |
72bd866a | 1473 | old = dir->i_op->lookup(dir, dentry, flags); |
44396f4b JB |
1474 | if (unlikely(old)) { |
1475 | dput(dentry); | |
1476 | dentry = old; | |
1477 | } | |
1478 | return dentry; | |
1479 | } | |
1480 | ||
a3255546 | 1481 | static struct dentry *__lookup_hash(struct qstr *name, |
72bd866a | 1482 | struct dentry *base, unsigned int flags) |
a3255546 | 1483 | { |
bad61189 | 1484 | bool need_lookup; |
a3255546 AV |
1485 | struct dentry *dentry; |
1486 | ||
72bd866a | 1487 | dentry = lookup_dcache(name, base, flags, &need_lookup); |
bad61189 MS |
1488 | if (!need_lookup) |
1489 | return dentry; | |
a3255546 | 1490 | |
72bd866a | 1491 | return lookup_real(base->d_inode, dentry, flags); |
a3255546 AV |
1492 | } |
1493 | ||
1da177e4 LT |
1494 | /* |
1495 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
1496 | * small and for now I'd prefer to have fast path as straight as possible. | |
1497 | * It _is_ time-critical. | |
1498 | */ | |
e97cdc87 | 1499 | static int lookup_fast(struct nameidata *nd, |
254cf582 AV |
1500 | struct path *path, struct inode **inode, |
1501 | unsigned *seqp) | |
1da177e4 | 1502 | { |
4ac91378 | 1503 | struct vfsmount *mnt = nd->path.mnt; |
31e6b01f | 1504 | struct dentry *dentry, *parent = nd->path.dentry; |
5a18fff2 AV |
1505 | int need_reval = 1; |
1506 | int status = 1; | |
9875cf80 DH |
1507 | int err; |
1508 | ||
b04f784e NP |
1509 | /* |
1510 | * Rename seqlock is not required here because in the off chance | |
1511 | * of a false negative due to a concurrent rename, we're going to | |
1512 | * do the non-racy lookup, below. | |
1513 | */ | |
31e6b01f NP |
1514 | if (nd->flags & LOOKUP_RCU) { |
1515 | unsigned seq; | |
766c4cbf | 1516 | bool negative; |
da53be12 | 1517 | dentry = __d_lookup_rcu(parent, &nd->last, &seq); |
5a18fff2 AV |
1518 | if (!dentry) |
1519 | goto unlazy; | |
1520 | ||
12f8ad4b LT |
1521 | /* |
1522 | * This sequence count validates that the inode matches | |
1523 | * the dentry name information from lookup. | |
1524 | */ | |
63afdfc7 | 1525 | *inode = d_backing_inode(dentry); |
766c4cbf | 1526 | negative = d_is_negative(dentry); |
12f8ad4b LT |
1527 | if (read_seqcount_retry(&dentry->d_seq, seq)) |
1528 | return -ECHILD; | |
766c4cbf AV |
1529 | if (negative) |
1530 | return -ENOENT; | |
12f8ad4b LT |
1531 | |
1532 | /* | |
1533 | * This sequence count validates that the parent had no | |
1534 | * changes while we did the lookup of the dentry above. | |
1535 | * | |
1536 | * The memory barrier in read_seqcount_begin of child is | |
1537 | * enough, we can use __read_seqcount_retry here. | |
1538 | */ | |
31e6b01f NP |
1539 | if (__read_seqcount_retry(&parent->d_seq, nd->seq)) |
1540 | return -ECHILD; | |
5a18fff2 | 1541 | |
254cf582 | 1542 | *seqp = seq; |
24643087 | 1543 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
4ce16ef3 | 1544 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1545 | if (unlikely(status <= 0)) { |
1546 | if (status != -ECHILD) | |
1547 | need_reval = 0; | |
1548 | goto unlazy; | |
1549 | } | |
24643087 | 1550 | } |
31e6b01f NP |
1551 | path->mnt = mnt; |
1552 | path->dentry = dentry; | |
254cf582 | 1553 | if (likely(__follow_mount_rcu(nd, path, inode, seqp))) |
b8faf035 | 1554 | return 0; |
5a18fff2 | 1555 | unlazy: |
254cf582 | 1556 | if (unlazy_walk(nd, dentry, seq)) |
19660af7 | 1557 | return -ECHILD; |
5a18fff2 | 1558 | } else { |
e97cdc87 | 1559 | dentry = __d_lookup(parent, &nd->last); |
9875cf80 | 1560 | } |
5a18fff2 | 1561 | |
81e6f520 AV |
1562 | if (unlikely(!dentry)) |
1563 | goto need_lookup; | |
1564 | ||
5a18fff2 | 1565 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) |
4ce16ef3 | 1566 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1567 | if (unlikely(status <= 0)) { |
1568 | if (status < 0) { | |
1569 | dput(dentry); | |
1570 | return status; | |
1571 | } | |
5542aa2f EB |
1572 | d_invalidate(dentry); |
1573 | dput(dentry); | |
1574 | goto need_lookup; | |
24643087 | 1575 | } |
697f514d | 1576 | |
766c4cbf AV |
1577 | if (unlikely(d_is_negative(dentry))) { |
1578 | dput(dentry); | |
1579 | return -ENOENT; | |
1580 | } | |
9875cf80 DH |
1581 | path->mnt = mnt; |
1582 | path->dentry = dentry; | |
756daf26 | 1583 | err = follow_managed(path, nd); |
8402752e | 1584 | if (likely(!err)) |
63afdfc7 | 1585 | *inode = d_backing_inode(path->dentry); |
8402752e | 1586 | return err; |
81e6f520 AV |
1587 | |
1588 | need_lookup: | |
697f514d MS |
1589 | return 1; |
1590 | } | |
1591 | ||
1592 | /* Fast lookup failed, do it the slow way */ | |
cc2a5271 | 1593 | static int lookup_slow(struct nameidata *nd, struct path *path) |
697f514d MS |
1594 | { |
1595 | struct dentry *dentry, *parent; | |
697f514d MS |
1596 | |
1597 | parent = nd->path.dentry; | |
81e6f520 AV |
1598 | BUG_ON(nd->inode != parent->d_inode); |
1599 | ||
1600 | mutex_lock(&parent->d_inode->i_mutex); | |
cc2a5271 | 1601 | dentry = __lookup_hash(&nd->last, parent, nd->flags); |
81e6f520 AV |
1602 | mutex_unlock(&parent->d_inode->i_mutex); |
1603 | if (IS_ERR(dentry)) | |
1604 | return PTR_ERR(dentry); | |
697f514d MS |
1605 | path->mnt = nd->path.mnt; |
1606 | path->dentry = dentry; | |
8402752e | 1607 | return follow_managed(path, nd); |
1da177e4 LT |
1608 | } |
1609 | ||
52094c8a AV |
1610 | static inline int may_lookup(struct nameidata *nd) |
1611 | { | |
1612 | if (nd->flags & LOOKUP_RCU) { | |
4ad5abb3 | 1613 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
52094c8a AV |
1614 | if (err != -ECHILD) |
1615 | return err; | |
6e9918b7 | 1616 | if (unlazy_walk(nd, NULL, 0)) |
52094c8a AV |
1617 | return -ECHILD; |
1618 | } | |
4ad5abb3 | 1619 | return inode_permission(nd->inode, MAY_EXEC); |
52094c8a AV |
1620 | } |
1621 | ||
9856fa1b AV |
1622 | static inline int handle_dots(struct nameidata *nd, int type) |
1623 | { | |
1624 | if (type == LAST_DOTDOT) { | |
1625 | if (nd->flags & LOOKUP_RCU) { | |
70291aec | 1626 | return follow_dotdot_rcu(nd); |
9856fa1b AV |
1627 | } else |
1628 | follow_dotdot(nd); | |
1629 | } | |
1630 | return 0; | |
1631 | } | |
1632 | ||
181548c0 AV |
1633 | static int pick_link(struct nameidata *nd, struct path *link, |
1634 | struct inode *inode, unsigned seq) | |
d63ff28f | 1635 | { |
626de996 | 1636 | int error; |
1cf2665b | 1637 | struct saved *last; |
756daf26 | 1638 | if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) { |
626de996 AV |
1639 | path_to_nameidata(link, nd); |
1640 | return -ELOOP; | |
1641 | } | |
bc40aee0 | 1642 | if (!(nd->flags & LOOKUP_RCU)) { |
7973387a AV |
1643 | if (link->mnt == nd->path.mnt) |
1644 | mntget(link->mnt); | |
d63ff28f | 1645 | } |
626de996 AV |
1646 | error = nd_alloc_stack(nd); |
1647 | if (unlikely(error)) { | |
bc40aee0 AV |
1648 | if (error == -ECHILD) { |
1649 | if (unlikely(unlazy_link(nd, link, seq))) | |
1650 | return -ECHILD; | |
1651 | error = nd_alloc_stack(nd); | |
1652 | } | |
1653 | if (error) { | |
1654 | path_put(link); | |
1655 | return error; | |
1656 | } | |
626de996 AV |
1657 | } |
1658 | ||
ab104923 | 1659 | last = nd->stack + nd->depth++; |
1cf2665b | 1660 | last->link = *link; |
ab104923 | 1661 | last->cookie = NULL; |
181548c0 | 1662 | last->inode = inode; |
0450b2d1 | 1663 | last->seq = seq; |
d63ff28f AV |
1664 | return 1; |
1665 | } | |
1666 | ||
3ddcd056 LT |
1667 | /* |
1668 | * Do we need to follow links? We _really_ want to be able | |
1669 | * to do this check without having to look at inode->i_op, | |
1670 | * so we keep a cache of "no, this doesn't need follow_link" | |
1671 | * for the common case. | |
1672 | */ | |
254cf582 | 1673 | static inline int should_follow_link(struct nameidata *nd, struct path *link, |
181548c0 AV |
1674 | int follow, |
1675 | struct inode *inode, unsigned seq) | |
3ddcd056 | 1676 | { |
d63ff28f AV |
1677 | if (likely(!d_is_symlink(link->dentry))) |
1678 | return 0; | |
1679 | if (!follow) | |
1680 | return 0; | |
181548c0 | 1681 | return pick_link(nd, link, inode, seq); |
3ddcd056 LT |
1682 | } |
1683 | ||
4693a547 AV |
1684 | enum {WALK_GET = 1, WALK_PUT = 2}; |
1685 | ||
1686 | static int walk_component(struct nameidata *nd, int flags) | |
ce57dfc1 | 1687 | { |
caa85634 | 1688 | struct path path; |
ce57dfc1 | 1689 | struct inode *inode; |
254cf582 | 1690 | unsigned seq; |
ce57dfc1 AV |
1691 | int err; |
1692 | /* | |
1693 | * "." and ".." are special - ".." especially so because it has | |
1694 | * to be able to know about the current root directory and | |
1695 | * parent relationships. | |
1696 | */ | |
4693a547 AV |
1697 | if (unlikely(nd->last_type != LAST_NORM)) { |
1698 | err = handle_dots(nd, nd->last_type); | |
1699 | if (flags & WALK_PUT) | |
1700 | put_link(nd); | |
1701 | return err; | |
1702 | } | |
254cf582 | 1703 | err = lookup_fast(nd, &path, &inode, &seq); |
ce57dfc1 | 1704 | if (unlikely(err)) { |
697f514d | 1705 | if (err < 0) |
f0a9ba70 | 1706 | return err; |
697f514d | 1707 | |
caa85634 | 1708 | err = lookup_slow(nd, &path); |
697f514d | 1709 | if (err < 0) |
f0a9ba70 | 1710 | return err; |
697f514d | 1711 | |
63afdfc7 | 1712 | inode = d_backing_inode(path.dentry); |
254cf582 | 1713 | seq = 0; /* we are already out of RCU mode */ |
766c4cbf | 1714 | err = -ENOENT; |
caa85634 | 1715 | if (d_is_negative(path.dentry)) |
766c4cbf | 1716 | goto out_path_put; |
ce57dfc1 | 1717 | } |
697f514d | 1718 | |
4693a547 AV |
1719 | if (flags & WALK_PUT) |
1720 | put_link(nd); | |
181548c0 | 1721 | err = should_follow_link(nd, &path, flags & WALK_GET, inode, seq); |
d63ff28f AV |
1722 | if (unlikely(err)) |
1723 | return err; | |
caa85634 | 1724 | path_to_nameidata(&path, nd); |
ce57dfc1 | 1725 | nd->inode = inode; |
254cf582 | 1726 | nd->seq = seq; |
ce57dfc1 | 1727 | return 0; |
697f514d MS |
1728 | |
1729 | out_path_put: | |
caa85634 | 1730 | path_to_nameidata(&path, nd); |
697f514d | 1731 | return err; |
ce57dfc1 AV |
1732 | } |
1733 | ||
bfcfaa77 LT |
1734 | /* |
1735 | * We can do the critical dentry name comparison and hashing | |
1736 | * operations one word at a time, but we are limited to: | |
1737 | * | |
1738 | * - Architectures with fast unaligned word accesses. We could | |
1739 | * do a "get_unaligned()" if this helps and is sufficiently | |
1740 | * fast. | |
1741 | * | |
bfcfaa77 LT |
1742 | * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we |
1743 | * do not trap on the (extremely unlikely) case of a page | |
1744 | * crossing operation. | |
1745 | * | |
1746 | * - Furthermore, we need an efficient 64-bit compile for the | |
1747 | * 64-bit case in order to generate the "number of bytes in | |
1748 | * the final mask". Again, that could be replaced with a | |
1749 | * efficient population count instruction or similar. | |
1750 | */ | |
1751 | #ifdef CONFIG_DCACHE_WORD_ACCESS | |
1752 | ||
f68e556e | 1753 | #include <asm/word-at-a-time.h> |
bfcfaa77 | 1754 | |
f68e556e | 1755 | #ifdef CONFIG_64BIT |
bfcfaa77 LT |
1756 | |
1757 | static inline unsigned int fold_hash(unsigned long hash) | |
1758 | { | |
99d263d4 | 1759 | return hash_64(hash, 32); |
bfcfaa77 LT |
1760 | } |
1761 | ||
1762 | #else /* 32-bit case */ | |
1763 | ||
bfcfaa77 LT |
1764 | #define fold_hash(x) (x) |
1765 | ||
1766 | #endif | |
1767 | ||
1768 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) | |
1769 | { | |
1770 | unsigned long a, mask; | |
1771 | unsigned long hash = 0; | |
1772 | ||
1773 | for (;;) { | |
e419b4cc | 1774 | a = load_unaligned_zeropad(name); |
bfcfaa77 LT |
1775 | if (len < sizeof(unsigned long)) |
1776 | break; | |
1777 | hash += a; | |
f132c5be | 1778 | hash *= 9; |
bfcfaa77 LT |
1779 | name += sizeof(unsigned long); |
1780 | len -= sizeof(unsigned long); | |
1781 | if (!len) | |
1782 | goto done; | |
1783 | } | |
a5c21dce | 1784 | mask = bytemask_from_count(len); |
bfcfaa77 LT |
1785 | hash += mask & a; |
1786 | done: | |
1787 | return fold_hash(hash); | |
1788 | } | |
1789 | EXPORT_SYMBOL(full_name_hash); | |
1790 | ||
bfcfaa77 LT |
1791 | /* |
1792 | * Calculate the length and hash of the path component, and | |
d6bb3e90 | 1793 | * return the "hash_len" as the result. |
bfcfaa77 | 1794 | */ |
d6bb3e90 | 1795 | static inline u64 hash_name(const char *name) |
bfcfaa77 | 1796 | { |
36126f8f LT |
1797 | unsigned long a, b, adata, bdata, mask, hash, len; |
1798 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; | |
bfcfaa77 LT |
1799 | |
1800 | hash = a = 0; | |
1801 | len = -sizeof(unsigned long); | |
1802 | do { | |
1803 | hash = (hash + a) * 9; | |
1804 | len += sizeof(unsigned long); | |
e419b4cc | 1805 | a = load_unaligned_zeropad(name+len); |
36126f8f LT |
1806 | b = a ^ REPEAT_BYTE('/'); |
1807 | } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); | |
1808 | ||
1809 | adata = prep_zero_mask(a, adata, &constants); | |
1810 | bdata = prep_zero_mask(b, bdata, &constants); | |
1811 | ||
1812 | mask = create_zero_mask(adata | bdata); | |
1813 | ||
1814 | hash += a & zero_bytemask(mask); | |
9226b5b4 | 1815 | len += find_zero(mask); |
d6bb3e90 | 1816 | return hashlen_create(fold_hash(hash), len); |
bfcfaa77 LT |
1817 | } |
1818 | ||
1819 | #else | |
1820 | ||
0145acc2 LT |
1821 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) |
1822 | { | |
1823 | unsigned long hash = init_name_hash(); | |
1824 | while (len--) | |
1825 | hash = partial_name_hash(*name++, hash); | |
1826 | return end_name_hash(hash); | |
1827 | } | |
ae942ae7 | 1828 | EXPORT_SYMBOL(full_name_hash); |
0145acc2 | 1829 | |
200e9ef7 LT |
1830 | /* |
1831 | * We know there's a real path component here of at least | |
1832 | * one character. | |
1833 | */ | |
d6bb3e90 | 1834 | static inline u64 hash_name(const char *name) |
200e9ef7 LT |
1835 | { |
1836 | unsigned long hash = init_name_hash(); | |
1837 | unsigned long len = 0, c; | |
1838 | ||
1839 | c = (unsigned char)*name; | |
1840 | do { | |
1841 | len++; | |
1842 | hash = partial_name_hash(c, hash); | |
1843 | c = (unsigned char)name[len]; | |
1844 | } while (c && c != '/'); | |
d6bb3e90 | 1845 | return hashlen_create(end_name_hash(hash), len); |
200e9ef7 LT |
1846 | } |
1847 | ||
bfcfaa77 LT |
1848 | #endif |
1849 | ||
1da177e4 LT |
1850 | /* |
1851 | * Name resolution. | |
ea3834d9 PM |
1852 | * This is the basic name resolution function, turning a pathname into |
1853 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 1854 | * |
ea3834d9 PM |
1855 | * Returns 0 and nd will have valid dentry and mnt on success. |
1856 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 1857 | */ |
6de88d72 | 1858 | static int link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 | 1859 | { |
1da177e4 | 1860 | int err; |
32cd7468 | 1861 | |
1da177e4 LT |
1862 | while (*name=='/') |
1863 | name++; | |
1864 | if (!*name) | |
9e18f10a | 1865 | return 0; |
1da177e4 | 1866 | |
1da177e4 LT |
1867 | /* At this point we know we have a real path component. */ |
1868 | for(;;) { | |
d6bb3e90 | 1869 | u64 hash_len; |
fe479a58 | 1870 | int type; |
1da177e4 | 1871 | |
52094c8a | 1872 | err = may_lookup(nd); |
1da177e4 | 1873 | if (err) |
3595e234 | 1874 | return err; |
1da177e4 | 1875 | |
d6bb3e90 | 1876 | hash_len = hash_name(name); |
1da177e4 | 1877 | |
fe479a58 | 1878 | type = LAST_NORM; |
d6bb3e90 | 1879 | if (name[0] == '.') switch (hashlen_len(hash_len)) { |
fe479a58 | 1880 | case 2: |
200e9ef7 | 1881 | if (name[1] == '.') { |
fe479a58 | 1882 | type = LAST_DOTDOT; |
16c2cd71 AV |
1883 | nd->flags |= LOOKUP_JUMPED; |
1884 | } | |
fe479a58 AV |
1885 | break; |
1886 | case 1: | |
1887 | type = LAST_DOT; | |
1888 | } | |
5a202bcd AV |
1889 | if (likely(type == LAST_NORM)) { |
1890 | struct dentry *parent = nd->path.dentry; | |
16c2cd71 | 1891 | nd->flags &= ~LOOKUP_JUMPED; |
5a202bcd | 1892 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
a060dc50 | 1893 | struct qstr this = { { .hash_len = hash_len }, .name = name }; |
da53be12 | 1894 | err = parent->d_op->d_hash(parent, &this); |
5a202bcd | 1895 | if (err < 0) |
3595e234 | 1896 | return err; |
d6bb3e90 LT |
1897 | hash_len = this.hash_len; |
1898 | name = this.name; | |
5a202bcd AV |
1899 | } |
1900 | } | |
fe479a58 | 1901 | |
d6bb3e90 LT |
1902 | nd->last.hash_len = hash_len; |
1903 | nd->last.name = name; | |
5f4a6a69 AV |
1904 | nd->last_type = type; |
1905 | ||
d6bb3e90 LT |
1906 | name += hashlen_len(hash_len); |
1907 | if (!*name) | |
bdf6cbf1 | 1908 | goto OK; |
200e9ef7 LT |
1909 | /* |
1910 | * If it wasn't NUL, we know it was '/'. Skip that | |
1911 | * slash, and continue until no more slashes. | |
1912 | */ | |
1913 | do { | |
d6bb3e90 LT |
1914 | name++; |
1915 | } while (unlikely(*name == '/')); | |
8620c238 AV |
1916 | if (unlikely(!*name)) { |
1917 | OK: | |
368ee9ba | 1918 | /* pathname body, done */ |
8620c238 AV |
1919 | if (!nd->depth) |
1920 | return 0; | |
1921 | name = nd->stack[nd->depth - 1].name; | |
368ee9ba | 1922 | /* trailing symlink, done */ |
8620c238 AV |
1923 | if (!name) |
1924 | return 0; | |
1925 | /* last component of nested symlink */ | |
4693a547 | 1926 | err = walk_component(nd, WALK_GET | WALK_PUT); |
8620c238 | 1927 | } else { |
4693a547 | 1928 | err = walk_component(nd, WALK_GET); |
8620c238 | 1929 | } |
ce57dfc1 | 1930 | if (err < 0) |
3595e234 | 1931 | return err; |
1da177e4 | 1932 | |
ce57dfc1 | 1933 | if (err) { |
626de996 | 1934 | const char *s = get_link(nd); |
5a460275 | 1935 | |
3595e234 AV |
1936 | if (unlikely(IS_ERR(s))) |
1937 | return PTR_ERR(s); | |
d40bcc09 AV |
1938 | err = 0; |
1939 | if (unlikely(!s)) { | |
1940 | /* jumped */ | |
b9ff4429 | 1941 | put_link(nd); |
d40bcc09 | 1942 | } else { |
fab51e8a AV |
1943 | nd->stack[nd->depth - 1].name = name; |
1944 | name = s; | |
1945 | continue; | |
d40bcc09 | 1946 | } |
31e6b01f | 1947 | } |
3595e234 AV |
1948 | if (unlikely(!d_can_lookup(nd->path.dentry))) |
1949 | return -ENOTDIR; | |
1da177e4 | 1950 | } |
1da177e4 LT |
1951 | } |
1952 | ||
368ee9ba AV |
1953 | static const char *path_init(int dfd, const struct filename *name, |
1954 | unsigned int flags, struct nameidata *nd) | |
31e6b01f NP |
1955 | { |
1956 | int retval = 0; | |
fd2f7cb5 | 1957 | const char *s = name->name; |
31e6b01f NP |
1958 | |
1959 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
980f3ea2 | 1960 | nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; |
31e6b01f | 1961 | nd->depth = 0; |
368ee9ba | 1962 | nd->total_link_count = 0; |
5b6ca027 | 1963 | if (flags & LOOKUP_ROOT) { |
b18825a7 DH |
1964 | struct dentry *root = nd->root.dentry; |
1965 | struct inode *inode = root->d_inode; | |
fd2f7cb5 | 1966 | if (*s) { |
44b1d530 | 1967 | if (!d_can_lookup(root)) |
368ee9ba | 1968 | return ERR_PTR(-ENOTDIR); |
73d049a4 AV |
1969 | retval = inode_permission(inode, MAY_EXEC); |
1970 | if (retval) | |
368ee9ba | 1971 | return ERR_PTR(retval); |
73d049a4 | 1972 | } |
5b6ca027 AV |
1973 | nd->path = nd->root; |
1974 | nd->inode = inode; | |
1975 | if (flags & LOOKUP_RCU) { | |
8b61e74f | 1976 | rcu_read_lock(); |
5b6ca027 | 1977 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
8f47a016 | 1978 | nd->root_seq = nd->seq; |
48a066e7 | 1979 | nd->m_seq = read_seqbegin(&mount_lock); |
5b6ca027 AV |
1980 | } else { |
1981 | path_get(&nd->path); | |
1982 | } | |
368ee9ba | 1983 | return s; |
5b6ca027 AV |
1984 | } |
1985 | ||
31e6b01f | 1986 | nd->root.mnt = NULL; |
31e6b01f | 1987 | |
48a066e7 | 1988 | nd->m_seq = read_seqbegin(&mount_lock); |
fd2f7cb5 | 1989 | if (*s == '/') { |
e41f7d4e | 1990 | if (flags & LOOKUP_RCU) { |
8b61e74f | 1991 | rcu_read_lock(); |
7bd88377 | 1992 | nd->seq = set_root_rcu(nd); |
e41f7d4e AV |
1993 | } else { |
1994 | set_root(nd); | |
1995 | path_get(&nd->root); | |
1996 | } | |
1997 | nd->path = nd->root; | |
31e6b01f | 1998 | } else if (dfd == AT_FDCWD) { |
e41f7d4e AV |
1999 | if (flags & LOOKUP_RCU) { |
2000 | struct fs_struct *fs = current->fs; | |
2001 | unsigned seq; | |
31e6b01f | 2002 | |
8b61e74f | 2003 | rcu_read_lock(); |
c28cc364 | 2004 | |
e41f7d4e AV |
2005 | do { |
2006 | seq = read_seqcount_begin(&fs->seq); | |
2007 | nd->path = fs->pwd; | |
2008 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
2009 | } while (read_seqcount_retry(&fs->seq, seq)); | |
2010 | } else { | |
2011 | get_fs_pwd(current->fs, &nd->path); | |
2012 | } | |
31e6b01f | 2013 | } else { |
582aa64a | 2014 | /* Caller must check execute permissions on the starting path component */ |
2903ff01 | 2015 | struct fd f = fdget_raw(dfd); |
31e6b01f NP |
2016 | struct dentry *dentry; |
2017 | ||
2903ff01 | 2018 | if (!f.file) |
368ee9ba | 2019 | return ERR_PTR(-EBADF); |
31e6b01f | 2020 | |
2903ff01 | 2021 | dentry = f.file->f_path.dentry; |
31e6b01f | 2022 | |
fd2f7cb5 | 2023 | if (*s) { |
44b1d530 | 2024 | if (!d_can_lookup(dentry)) { |
2903ff01 | 2025 | fdput(f); |
368ee9ba | 2026 | return ERR_PTR(-ENOTDIR); |
2903ff01 | 2027 | } |
f52e0c11 | 2028 | } |
31e6b01f | 2029 | |
2903ff01 | 2030 | nd->path = f.file->f_path; |
e41f7d4e | 2031 | if (flags & LOOKUP_RCU) { |
8b61e74f | 2032 | rcu_read_lock(); |
34a26b99 AV |
2033 | nd->inode = nd->path.dentry->d_inode; |
2034 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); | |
e41f7d4e | 2035 | } else { |
2903ff01 | 2036 | path_get(&nd->path); |
34a26b99 | 2037 | nd->inode = nd->path.dentry->d_inode; |
e41f7d4e | 2038 | } |
34a26b99 | 2039 | fdput(f); |
368ee9ba | 2040 | return s; |
31e6b01f | 2041 | } |
31e6b01f | 2042 | |
31e6b01f | 2043 | nd->inode = nd->path.dentry->d_inode; |
4023bfc9 | 2044 | if (!(flags & LOOKUP_RCU)) |
368ee9ba | 2045 | return s; |
4023bfc9 | 2046 | if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) |
368ee9ba | 2047 | return s; |
4023bfc9 AV |
2048 | if (!(nd->flags & LOOKUP_ROOT)) |
2049 | nd->root.mnt = NULL; | |
2050 | rcu_read_unlock(); | |
368ee9ba | 2051 | return ERR_PTR(-ECHILD); |
9b4a9b14 AV |
2052 | } |
2053 | ||
893b7775 AV |
2054 | static void path_cleanup(struct nameidata *nd) |
2055 | { | |
2056 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { | |
2057 | path_put(&nd->root); | |
2058 | nd->root.mnt = NULL; | |
2059 | } | |
9b4a9b14 AV |
2060 | } |
2061 | ||
3bdba28b | 2062 | static const char *trailing_symlink(struct nameidata *nd) |
95fa25d9 AV |
2063 | { |
2064 | const char *s; | |
fec2fa24 | 2065 | int error = may_follow_link(nd); |
deb106c6 | 2066 | if (unlikely(error)) |
3bdba28b | 2067 | return ERR_PTR(error); |
95fa25d9 | 2068 | nd->flags |= LOOKUP_PARENT; |
fab51e8a | 2069 | nd->stack[0].name = NULL; |
3b2e7f75 | 2070 | s = get_link(nd); |
deb106c6 | 2071 | return s ? s : ""; |
95fa25d9 AV |
2072 | } |
2073 | ||
caa85634 | 2074 | static inline int lookup_last(struct nameidata *nd) |
bd92d7fe AV |
2075 | { |
2076 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) | |
2077 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
2078 | ||
2079 | nd->flags &= ~LOOKUP_PARENT; | |
deb106c6 | 2080 | return walk_component(nd, |
4693a547 AV |
2081 | nd->flags & LOOKUP_FOLLOW |
2082 | ? nd->depth | |
2083 | ? WALK_PUT | WALK_GET | |
2084 | : WALK_GET | |
2085 | : 0); | |
bd92d7fe AV |
2086 | } |
2087 | ||
9b4a9b14 | 2088 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
625b6d10 AV |
2089 | static int path_lookupat(int dfd, const struct filename *name, unsigned flags, |
2090 | struct nameidata *nd, struct path *path) | |
9b4a9b14 | 2091 | { |
368ee9ba | 2092 | const char *s = path_init(dfd, name, flags, nd); |
bd92d7fe | 2093 | int err; |
31e6b01f | 2094 | |
368ee9ba AV |
2095 | if (IS_ERR(s)) |
2096 | return PTR_ERR(s); | |
3bdba28b AV |
2097 | while (!(err = link_path_walk(s, nd)) |
2098 | && ((err = lookup_last(nd)) > 0)) { | |
2099 | s = trailing_symlink(nd); | |
2100 | if (IS_ERR(s)) { | |
2101 | err = PTR_ERR(s); | |
2102 | break; | |
bd92d7fe AV |
2103 | } |
2104 | } | |
9f1fafee AV |
2105 | if (!err) |
2106 | err = complete_walk(nd); | |
bd92d7fe | 2107 | |
deb106c6 AV |
2108 | if (!err && nd->flags & LOOKUP_DIRECTORY) |
2109 | if (!d_can_lookup(nd->path.dentry)) | |
bd23a539 | 2110 | err = -ENOTDIR; |
625b6d10 AV |
2111 | if (!err) { |
2112 | *path = nd->path; | |
2113 | nd->path.mnt = NULL; | |
2114 | nd->path.dentry = NULL; | |
2115 | } | |
2116 | terminate_walk(nd); | |
893b7775 | 2117 | path_cleanup(nd); |
bd92d7fe | 2118 | return err; |
ee0827cd | 2119 | } |
31e6b01f | 2120 | |
625b6d10 AV |
2121 | static int filename_lookup(int dfd, struct filename *name, unsigned flags, |
2122 | struct nameidata *nd, struct path *path) | |
ee0827cd | 2123 | { |
894bc8c4 | 2124 | int retval; |
756daf26 | 2125 | struct nameidata *saved_nd = set_nameidata(nd); |
894bc8c4 | 2126 | |
625b6d10 | 2127 | retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd, path); |
ee0827cd | 2128 | if (unlikely(retval == -ECHILD)) |
625b6d10 | 2129 | retval = path_lookupat(dfd, name, flags, nd, path); |
ee0827cd | 2130 | if (unlikely(retval == -ESTALE)) |
625b6d10 AV |
2131 | retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, |
2132 | nd, path); | |
31e6b01f | 2133 | |
f78570dd | 2134 | if (likely(!retval)) |
625b6d10 | 2135 | audit_inode(name, path->dentry, flags & LOOKUP_PARENT); |
756daf26 | 2136 | restore_nameidata(saved_nd); |
170aa3d0 | 2137 | return retval; |
1da177e4 LT |
2138 | } |
2139 | ||
8bcb77fa AV |
2140 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
2141 | static int path_parentat(int dfd, const struct filename *name, | |
2142 | unsigned int flags, struct nameidata *nd) | |
2143 | { | |
368ee9ba AV |
2144 | const char *s = path_init(dfd, name, flags, nd); |
2145 | int err; | |
2146 | if (IS_ERR(s)) | |
2147 | return PTR_ERR(s); | |
2148 | err = link_path_walk(s, nd); | |
8bcb77fa AV |
2149 | if (!err) |
2150 | err = complete_walk(nd); | |
deb106c6 AV |
2151 | if (err) |
2152 | terminate_walk(nd); | |
8bcb77fa AV |
2153 | path_cleanup(nd); |
2154 | return err; | |
2155 | } | |
2156 | ||
2157 | static int filename_parentat(int dfd, struct filename *name, | |
2158 | unsigned int flags, struct nameidata *nd) | |
2159 | { | |
2160 | int retval; | |
2161 | struct nameidata *saved_nd = set_nameidata(nd); | |
2162 | ||
2163 | retval = path_parentat(dfd, name, flags | LOOKUP_RCU, nd); | |
2164 | if (unlikely(retval == -ECHILD)) | |
2165 | retval = path_parentat(dfd, name, flags, nd); | |
2166 | if (unlikely(retval == -ESTALE)) | |
2167 | retval = path_parentat(dfd, name, flags | LOOKUP_REVAL, nd); | |
2168 | ||
2169 | if (likely(!retval)) | |
2170 | audit_inode(name, nd->path.dentry, LOOKUP_PARENT); | |
2171 | restore_nameidata(saved_nd); | |
2172 | return retval; | |
2173 | } | |
2174 | ||
79714f72 AV |
2175 | /* does lookup, returns the object with parent locked */ |
2176 | struct dentry *kern_path_locked(const char *name, struct path *path) | |
5590ff0d | 2177 | { |
51689104 | 2178 | struct filename *filename = getname_kernel(name); |
79714f72 AV |
2179 | struct nameidata nd; |
2180 | struct dentry *d; | |
51689104 PM |
2181 | int err; |
2182 | ||
2183 | if (IS_ERR(filename)) | |
2184 | return ERR_CAST(filename); | |
2185 | ||
8bcb77fa | 2186 | err = filename_parentat(AT_FDCWD, filename, 0, &nd); |
51689104 PM |
2187 | if (err) { |
2188 | d = ERR_PTR(err); | |
2189 | goto out; | |
2190 | } | |
79714f72 AV |
2191 | if (nd.last_type != LAST_NORM) { |
2192 | path_put(&nd.path); | |
51689104 PM |
2193 | d = ERR_PTR(-EINVAL); |
2194 | goto out; | |
79714f72 AV |
2195 | } |
2196 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); | |
1e0ea001 | 2197 | d = __lookup_hash(&nd.last, nd.path.dentry, 0); |
79714f72 AV |
2198 | if (IS_ERR(d)) { |
2199 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); | |
2200 | path_put(&nd.path); | |
51689104 | 2201 | goto out; |
79714f72 AV |
2202 | } |
2203 | *path = nd.path; | |
51689104 PM |
2204 | out: |
2205 | putname(filename); | |
79714f72 | 2206 | return d; |
5590ff0d UD |
2207 | } |
2208 | ||
d1811465 AV |
2209 | int kern_path(const char *name, unsigned int flags, struct path *path) |
2210 | { | |
2211 | struct nameidata nd; | |
74eb8cc5 AV |
2212 | struct filename *filename = getname_kernel(name); |
2213 | int res = PTR_ERR(filename); | |
2214 | ||
2215 | if (!IS_ERR(filename)) { | |
625b6d10 | 2216 | res = filename_lookup(AT_FDCWD, filename, flags, &nd, path); |
74eb8cc5 | 2217 | putname(filename); |
74eb8cc5 | 2218 | } |
d1811465 AV |
2219 | return res; |
2220 | } | |
4d359507 | 2221 | EXPORT_SYMBOL(kern_path); |
d1811465 | 2222 | |
16f18200 JJS |
2223 | /** |
2224 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
2225 | * @dentry: pointer to dentry of the base directory | |
2226 | * @mnt: pointer to vfs mount of the base directory | |
2227 | * @name: pointer to file name | |
2228 | * @flags: lookup flags | |
e0a01249 | 2229 | * @path: pointer to struct path to fill |
16f18200 JJS |
2230 | */ |
2231 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
2232 | const char *name, unsigned int flags, | |
e0a01249 | 2233 | struct path *path) |
16f18200 | 2234 | { |
74eb8cc5 AV |
2235 | struct filename *filename = getname_kernel(name); |
2236 | int err = PTR_ERR(filename); | |
2237 | ||
e0a01249 | 2238 | BUG_ON(flags & LOOKUP_PARENT); |
74eb8cc5 AV |
2239 | |
2240 | /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ | |
2241 | if (!IS_ERR(filename)) { | |
2242 | struct nameidata nd; | |
2243 | nd.root.dentry = dentry; | |
2244 | nd.root.mnt = mnt; | |
2245 | err = filename_lookup(AT_FDCWD, filename, | |
625b6d10 | 2246 | flags | LOOKUP_ROOT, &nd, path); |
74eb8cc5 AV |
2247 | putname(filename); |
2248 | } | |
e0a01249 | 2249 | return err; |
16f18200 | 2250 | } |
4d359507 | 2251 | EXPORT_SYMBOL(vfs_path_lookup); |
16f18200 | 2252 | |
eead1911 | 2253 | /** |
a6b91919 | 2254 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
2255 | * @name: pathname component to lookup |
2256 | * @base: base directory to lookup from | |
2257 | * @len: maximum length @len should be interpreted to | |
2258 | * | |
a6b91919 | 2259 | * Note that this routine is purely a helper for filesystem usage and should |
9e7543e9 | 2260 | * not be called by generic code. |
eead1911 | 2261 | */ |
057f6c01 JM |
2262 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
2263 | { | |
057f6c01 | 2264 | struct qstr this; |
6a96ba54 | 2265 | unsigned int c; |
cda309de | 2266 | int err; |
057f6c01 | 2267 | |
2f9092e1 DW |
2268 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
2269 | ||
6a96ba54 AV |
2270 | this.name = name; |
2271 | this.len = len; | |
0145acc2 | 2272 | this.hash = full_name_hash(name, len); |
6a96ba54 AV |
2273 | if (!len) |
2274 | return ERR_PTR(-EACCES); | |
2275 | ||
21d8a15a AV |
2276 | if (unlikely(name[0] == '.')) { |
2277 | if (len < 2 || (len == 2 && name[1] == '.')) | |
2278 | return ERR_PTR(-EACCES); | |
2279 | } | |
2280 | ||
6a96ba54 AV |
2281 | while (len--) { |
2282 | c = *(const unsigned char *)name++; | |
2283 | if (c == '/' || c == '\0') | |
2284 | return ERR_PTR(-EACCES); | |
6a96ba54 | 2285 | } |
5a202bcd AV |
2286 | /* |
2287 | * See if the low-level filesystem might want | |
2288 | * to use its own hash.. | |
2289 | */ | |
2290 | if (base->d_flags & DCACHE_OP_HASH) { | |
da53be12 | 2291 | int err = base->d_op->d_hash(base, &this); |
5a202bcd AV |
2292 | if (err < 0) |
2293 | return ERR_PTR(err); | |
2294 | } | |
eead1911 | 2295 | |
cda309de MS |
2296 | err = inode_permission(base->d_inode, MAY_EXEC); |
2297 | if (err) | |
2298 | return ERR_PTR(err); | |
2299 | ||
72bd866a | 2300 | return __lookup_hash(&this, base, 0); |
057f6c01 | 2301 | } |
4d359507 | 2302 | EXPORT_SYMBOL(lookup_one_len); |
057f6c01 | 2303 | |
1fa1e7f6 AW |
2304 | int user_path_at_empty(int dfd, const char __user *name, unsigned flags, |
2305 | struct path *path, int *empty) | |
1da177e4 | 2306 | { |
2d8f3038 | 2307 | struct nameidata nd; |
91a27b2a | 2308 | struct filename *tmp = getname_flags(name, flags, empty); |
1da177e4 | 2309 | int err = PTR_ERR(tmp); |
1da177e4 | 2310 | if (!IS_ERR(tmp)) { |
2d8f3038 AV |
2311 | |
2312 | BUG_ON(flags & LOOKUP_PARENT); | |
2313 | ||
625b6d10 | 2314 | err = filename_lookup(dfd, tmp, flags, &nd, path); |
1da177e4 LT |
2315 | putname(tmp); |
2316 | } | |
2317 | return err; | |
2318 | } | |
2319 | ||
1fa1e7f6 AW |
2320 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
2321 | struct path *path) | |
2322 | { | |
f7493e5d | 2323 | return user_path_at_empty(dfd, name, flags, path, NULL); |
1fa1e7f6 | 2324 | } |
4d359507 | 2325 | EXPORT_SYMBOL(user_path_at); |
1fa1e7f6 | 2326 | |
873f1eed JL |
2327 | /* |
2328 | * NB: most callers don't do anything directly with the reference to the | |
2329 | * to struct filename, but the nd->last pointer points into the name string | |
2330 | * allocated by getname. So we must hold the reference to it until all | |
2331 | * path-walking is complete. | |
2332 | */ | |
91a27b2a | 2333 | static struct filename * |
f5beed75 AV |
2334 | user_path_parent(int dfd, const char __user *path, |
2335 | struct path *parent, | |
2336 | struct qstr *last, | |
2337 | int *type, | |
9e790bd6 | 2338 | unsigned int flags) |
2ad94ae6 | 2339 | { |
f5beed75 | 2340 | struct nameidata nd; |
91a27b2a | 2341 | struct filename *s = getname(path); |
2ad94ae6 AV |
2342 | int error; |
2343 | ||
9e790bd6 JL |
2344 | /* only LOOKUP_REVAL is allowed in extra flags */ |
2345 | flags &= LOOKUP_REVAL; | |
2346 | ||
2ad94ae6 | 2347 | if (IS_ERR(s)) |
91a27b2a | 2348 | return s; |
2ad94ae6 | 2349 | |
8bcb77fa | 2350 | error = filename_parentat(dfd, s, flags, &nd); |
91a27b2a | 2351 | if (error) { |
2ad94ae6 | 2352 | putname(s); |
91a27b2a JL |
2353 | return ERR_PTR(error); |
2354 | } | |
f5beed75 AV |
2355 | *parent = nd.path; |
2356 | *last = nd.last; | |
2357 | *type = nd.last_type; | |
2ad94ae6 | 2358 | |
91a27b2a | 2359 | return s; |
2ad94ae6 AV |
2360 | } |
2361 | ||
8033426e | 2362 | /** |
197df04c | 2363 | * mountpoint_last - look up last component for umount |
8033426e JL |
2364 | * @nd: pathwalk nameidata - currently pointing at parent directory of "last" |
2365 | * @path: pointer to container for result | |
2366 | * | |
2367 | * This is a special lookup_last function just for umount. In this case, we | |
2368 | * need to resolve the path without doing any revalidation. | |
2369 | * | |
2370 | * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since | |
2371 | * mountpoints are always pinned in the dcache, their ancestors are too. Thus, | |
2372 | * in almost all cases, this lookup will be served out of the dcache. The only | |
2373 | * cases where it won't are if nd->last refers to a symlink or the path is | |
2374 | * bogus and it doesn't exist. | |
2375 | * | |
2376 | * Returns: | |
2377 | * -error: if there was an error during lookup. This includes -ENOENT if the | |
2378 | * lookup found a negative dentry. The nd->path reference will also be | |
2379 | * put in this case. | |
2380 | * | |
2381 | * 0: if we successfully resolved nd->path and found it to not to be a | |
2382 | * symlink that needs to be followed. "path" will also be populated. | |
2383 | * The nd->path reference will also be put. | |
2384 | * | |
2385 | * 1: if we successfully resolved nd->last and found it to be a symlink | |
2386 | * that needs to be followed. "path" will be populated with the path | |
2387 | * to the link, and nd->path will *not* be put. | |
2388 | */ | |
2389 | static int | |
197df04c | 2390 | mountpoint_last(struct nameidata *nd, struct path *path) |
8033426e JL |
2391 | { |
2392 | int error = 0; | |
2393 | struct dentry *dentry; | |
2394 | struct dentry *dir = nd->path.dentry; | |
2395 | ||
35759521 AV |
2396 | /* If we're in rcuwalk, drop out of it to handle last component */ |
2397 | if (nd->flags & LOOKUP_RCU) { | |
6e9918b7 | 2398 | if (unlazy_walk(nd, NULL, 0)) |
deb106c6 | 2399 | return -ECHILD; |
8033426e JL |
2400 | } |
2401 | ||
2402 | nd->flags &= ~LOOKUP_PARENT; | |
2403 | ||
2404 | if (unlikely(nd->last_type != LAST_NORM)) { | |
2405 | error = handle_dots(nd, nd->last_type); | |
35759521 | 2406 | if (error) |
deb106c6 | 2407 | return error; |
35759521 AV |
2408 | dentry = dget(nd->path.dentry); |
2409 | goto done; | |
8033426e JL |
2410 | } |
2411 | ||
2412 | mutex_lock(&dir->d_inode->i_mutex); | |
2413 | dentry = d_lookup(dir, &nd->last); | |
2414 | if (!dentry) { | |
2415 | /* | |
2416 | * No cached dentry. Mounted dentries are pinned in the cache, | |
2417 | * so that means that this dentry is probably a symlink or the | |
2418 | * path doesn't actually point to a mounted dentry. | |
2419 | */ | |
2420 | dentry = d_alloc(dir, &nd->last); | |
2421 | if (!dentry) { | |
bcceeeba | 2422 | mutex_unlock(&dir->d_inode->i_mutex); |
deb106c6 | 2423 | return -ENOMEM; |
8033426e | 2424 | } |
35759521 | 2425 | dentry = lookup_real(dir->d_inode, dentry, nd->flags); |
bcceeeba DJ |
2426 | if (IS_ERR(dentry)) { |
2427 | mutex_unlock(&dir->d_inode->i_mutex); | |
deb106c6 | 2428 | return PTR_ERR(dentry); |
bcceeeba | 2429 | } |
8033426e JL |
2430 | } |
2431 | mutex_unlock(&dir->d_inode->i_mutex); | |
2432 | ||
35759521 | 2433 | done: |
698934df | 2434 | if (d_is_negative(dentry)) { |
35759521 | 2435 | dput(dentry); |
deb106c6 | 2436 | return -ENOENT; |
8033426e | 2437 | } |
191d7f73 AV |
2438 | if (nd->depth) |
2439 | put_link(nd); | |
35759521 | 2440 | path->dentry = dentry; |
295dc39d | 2441 | path->mnt = nd->path.mnt; |
181548c0 AV |
2442 | error = should_follow_link(nd, path, nd->flags & LOOKUP_FOLLOW, |
2443 | d_backing_inode(dentry), 0); | |
deb106c6 | 2444 | if (unlikely(error)) |
d63ff28f | 2445 | return error; |
295dc39d | 2446 | mntget(path->mnt); |
35759521 | 2447 | follow_mount(path); |
deb106c6 | 2448 | return 0; |
8033426e JL |
2449 | } |
2450 | ||
2451 | /** | |
197df04c | 2452 | * path_mountpoint - look up a path to be umounted |
8033426e JL |
2453 | * @dfd: directory file descriptor to start walk from |
2454 | * @name: full pathname to walk | |
606d6fe3 | 2455 | * @path: pointer to container for result |
8033426e | 2456 | * @flags: lookup flags |
8033426e JL |
2457 | * |
2458 | * Look up the given name, but don't attempt to revalidate the last component. | |
606d6fe3 | 2459 | * Returns 0 and "path" will be valid on success; Returns error otherwise. |
8033426e JL |
2460 | */ |
2461 | static int | |
668696dc | 2462 | path_mountpoint(int dfd, const struct filename *name, struct path *path, |
46afd6f6 | 2463 | struct nameidata *nd, unsigned int flags) |
8033426e | 2464 | { |
368ee9ba AV |
2465 | const char *s = path_init(dfd, name, flags, nd); |
2466 | int err; | |
2467 | if (IS_ERR(s)) | |
2468 | return PTR_ERR(s); | |
3bdba28b AV |
2469 | while (!(err = link_path_walk(s, nd)) && |
2470 | (err = mountpoint_last(nd, path)) > 0) { | |
2471 | s = trailing_symlink(nd); | |
2472 | if (IS_ERR(s)) { | |
2473 | err = PTR_ERR(s); | |
8033426e | 2474 | break; |
3bdba28b | 2475 | } |
8033426e | 2476 | } |
deb106c6 | 2477 | terminate_walk(nd); |
46afd6f6 | 2478 | path_cleanup(nd); |
8033426e JL |
2479 | return err; |
2480 | } | |
2481 | ||
2d864651 | 2482 | static int |
668696dc | 2483 | filename_mountpoint(int dfd, struct filename *name, struct path *path, |
2d864651 AV |
2484 | unsigned int flags) |
2485 | { | |
756daf26 | 2486 | struct nameidata nd, *saved; |
cbaab2db | 2487 | int error; |
668696dc AV |
2488 | if (IS_ERR(name)) |
2489 | return PTR_ERR(name); | |
756daf26 | 2490 | saved = set_nameidata(&nd); |
46afd6f6 | 2491 | error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); |
2d864651 | 2492 | if (unlikely(error == -ECHILD)) |
46afd6f6 | 2493 | error = path_mountpoint(dfd, name, path, &nd, flags); |
2d864651 | 2494 | if (unlikely(error == -ESTALE)) |
46afd6f6 | 2495 | error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); |
2d864651 | 2496 | if (likely(!error)) |
668696dc | 2497 | audit_inode(name, path->dentry, 0); |
756daf26 | 2498 | restore_nameidata(saved); |
668696dc | 2499 | putname(name); |
2d864651 AV |
2500 | return error; |
2501 | } | |
2502 | ||
8033426e | 2503 | /** |
197df04c | 2504 | * user_path_mountpoint_at - lookup a path from userland in order to umount it |
8033426e JL |
2505 | * @dfd: directory file descriptor |
2506 | * @name: pathname from userland | |
2507 | * @flags: lookup flags | |
2508 | * @path: pointer to container to hold result | |
2509 | * | |
2510 | * A umount is a special case for path walking. We're not actually interested | |
2511 | * in the inode in this situation, and ESTALE errors can be a problem. We | |
2512 | * simply want track down the dentry and vfsmount attached at the mountpoint | |
2513 | * and avoid revalidating the last component. | |
2514 | * | |
2515 | * Returns 0 and populates "path" on success. | |
2516 | */ | |
2517 | int | |
197df04c | 2518 | user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, |
8033426e JL |
2519 | struct path *path) |
2520 | { | |
cbaab2db | 2521 | return filename_mountpoint(dfd, getname(name), path, flags); |
8033426e JL |
2522 | } |
2523 | ||
2d864651 AV |
2524 | int |
2525 | kern_path_mountpoint(int dfd, const char *name, struct path *path, | |
2526 | unsigned int flags) | |
2527 | { | |
cbaab2db | 2528 | return filename_mountpoint(dfd, getname_kernel(name), path, flags); |
2d864651 AV |
2529 | } |
2530 | EXPORT_SYMBOL(kern_path_mountpoint); | |
2531 | ||
cbdf35bc | 2532 | int __check_sticky(struct inode *dir, struct inode *inode) |
1da177e4 | 2533 | { |
8e96e3b7 | 2534 | kuid_t fsuid = current_fsuid(); |
da9592ed | 2535 | |
8e96e3b7 | 2536 | if (uid_eq(inode->i_uid, fsuid)) |
1da177e4 | 2537 | return 0; |
8e96e3b7 | 2538 | if (uid_eq(dir->i_uid, fsuid)) |
1da177e4 | 2539 | return 0; |
23adbe12 | 2540 | return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); |
1da177e4 | 2541 | } |
cbdf35bc | 2542 | EXPORT_SYMBOL(__check_sticky); |
1da177e4 LT |
2543 | |
2544 | /* | |
2545 | * Check whether we can remove a link victim from directory dir, check | |
2546 | * whether the type of victim is right. | |
2547 | * 1. We can't do it if dir is read-only (done in permission()) | |
2548 | * 2. We should have write and exec permissions on dir | |
2549 | * 3. We can't remove anything from append-only dir | |
2550 | * 4. We can't do anything with immutable dir (done in permission()) | |
2551 | * 5. If the sticky bit on dir is set we should either | |
2552 | * a. be owner of dir, or | |
2553 | * b. be owner of victim, or | |
2554 | * c. have CAP_FOWNER capability | |
2555 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
2556 | * links pointing to it. | |
2557 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
2558 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
2559 | * 9. We can't remove a root or mountpoint. | |
2560 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
2561 | * nfs_async_unlink(). | |
2562 | */ | |
b18825a7 | 2563 | static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) |
1da177e4 | 2564 | { |
63afdfc7 | 2565 | struct inode *inode = d_backing_inode(victim); |
1da177e4 LT |
2566 | int error; |
2567 | ||
b18825a7 | 2568 | if (d_is_negative(victim)) |
1da177e4 | 2569 | return -ENOENT; |
b18825a7 | 2570 | BUG_ON(!inode); |
1da177e4 LT |
2571 | |
2572 | BUG_ON(victim->d_parent->d_inode != dir); | |
4fa6b5ec | 2573 | audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); |
1da177e4 | 2574 | |
f419a2e3 | 2575 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2576 | if (error) |
2577 | return error; | |
2578 | if (IS_APPEND(dir)) | |
2579 | return -EPERM; | |
b18825a7 DH |
2580 | |
2581 | if (check_sticky(dir, inode) || IS_APPEND(inode) || | |
2582 | IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) | |
1da177e4 LT |
2583 | return -EPERM; |
2584 | if (isdir) { | |
44b1d530 | 2585 | if (!d_is_dir(victim)) |
1da177e4 LT |
2586 | return -ENOTDIR; |
2587 | if (IS_ROOT(victim)) | |
2588 | return -EBUSY; | |
44b1d530 | 2589 | } else if (d_is_dir(victim)) |
1da177e4 LT |
2590 | return -EISDIR; |
2591 | if (IS_DEADDIR(dir)) | |
2592 | return -ENOENT; | |
2593 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
2594 | return -EBUSY; | |
2595 | return 0; | |
2596 | } | |
2597 | ||
2598 | /* Check whether we can create an object with dentry child in directory | |
2599 | * dir. | |
2600 | * 1. We can't do it if child already exists (open has special treatment for | |
2601 | * this case, but since we are inlined it's OK) | |
2602 | * 2. We can't do it if dir is read-only (done in permission()) | |
2603 | * 3. We should have write and exec permissions on dir | |
2604 | * 4. We can't do it if dir is immutable (done in permission()) | |
2605 | */ | |
a95164d9 | 2606 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 | 2607 | { |
14e972b4 | 2608 | audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); |
1da177e4 LT |
2609 | if (child->d_inode) |
2610 | return -EEXIST; | |
2611 | if (IS_DEADDIR(dir)) | |
2612 | return -ENOENT; | |
f419a2e3 | 2613 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2614 | } |
2615 | ||
1da177e4 LT |
2616 | /* |
2617 | * p1 and p2 should be directories on the same fs. | |
2618 | */ | |
2619 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
2620 | { | |
2621 | struct dentry *p; | |
2622 | ||
2623 | if (p1 == p2) { | |
f2eace23 | 2624 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
2625 | return NULL; |
2626 | } | |
2627 | ||
a11f3a05 | 2628 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 | 2629 | |
e2761a11 OH |
2630 | p = d_ancestor(p2, p1); |
2631 | if (p) { | |
2632 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); | |
2633 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
2634 | return p; | |
1da177e4 LT |
2635 | } |
2636 | ||
e2761a11 OH |
2637 | p = d_ancestor(p1, p2); |
2638 | if (p) { | |
2639 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); | |
2640 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
2641 | return p; | |
1da177e4 LT |
2642 | } |
2643 | ||
f2eace23 | 2644 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
d1b72cc6 | 2645 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); |
1da177e4 LT |
2646 | return NULL; |
2647 | } | |
4d359507 | 2648 | EXPORT_SYMBOL(lock_rename); |
1da177e4 LT |
2649 | |
2650 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
2651 | { | |
1b1dcc1b | 2652 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 2653 | if (p1 != p2) { |
1b1dcc1b | 2654 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 2655 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
2656 | } |
2657 | } | |
4d359507 | 2658 | EXPORT_SYMBOL(unlock_rename); |
1da177e4 | 2659 | |
4acdaf27 | 2660 | int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
312b63fb | 2661 | bool want_excl) |
1da177e4 | 2662 | { |
a95164d9 | 2663 | int error = may_create(dir, dentry); |
1da177e4 LT |
2664 | if (error) |
2665 | return error; | |
2666 | ||
acfa4380 | 2667 | if (!dir->i_op->create) |
1da177e4 LT |
2668 | return -EACCES; /* shouldn't it be ENOSYS? */ |
2669 | mode &= S_IALLUGO; | |
2670 | mode |= S_IFREG; | |
2671 | error = security_inode_create(dir, dentry, mode); | |
2672 | if (error) | |
2673 | return error; | |
312b63fb | 2674 | error = dir->i_op->create(dir, dentry, mode, want_excl); |
a74574aa | 2675 | if (!error) |
f38aa942 | 2676 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2677 | return error; |
2678 | } | |
4d359507 | 2679 | EXPORT_SYMBOL(vfs_create); |
1da177e4 | 2680 | |
73d049a4 | 2681 | static int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 2682 | { |
3fb64190 | 2683 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
2684 | struct inode *inode = dentry->d_inode; |
2685 | int error; | |
2686 | ||
bcda7652 AV |
2687 | /* O_PATH? */ |
2688 | if (!acc_mode) | |
2689 | return 0; | |
2690 | ||
1da177e4 LT |
2691 | if (!inode) |
2692 | return -ENOENT; | |
2693 | ||
c8fe8f30 CH |
2694 | switch (inode->i_mode & S_IFMT) { |
2695 | case S_IFLNK: | |
1da177e4 | 2696 | return -ELOOP; |
c8fe8f30 CH |
2697 | case S_IFDIR: |
2698 | if (acc_mode & MAY_WRITE) | |
2699 | return -EISDIR; | |
2700 | break; | |
2701 | case S_IFBLK: | |
2702 | case S_IFCHR: | |
3fb64190 | 2703 | if (path->mnt->mnt_flags & MNT_NODEV) |
1da177e4 | 2704 | return -EACCES; |
c8fe8f30 CH |
2705 | /*FALLTHRU*/ |
2706 | case S_IFIFO: | |
2707 | case S_IFSOCK: | |
1da177e4 | 2708 | flag &= ~O_TRUNC; |
c8fe8f30 | 2709 | break; |
4a3fd211 | 2710 | } |
b41572e9 | 2711 | |
3fb64190 | 2712 | error = inode_permission(inode, acc_mode); |
b41572e9 DH |
2713 | if (error) |
2714 | return error; | |
6146f0d5 | 2715 | |
1da177e4 LT |
2716 | /* |
2717 | * An append-only file must be opened in append mode for writing. | |
2718 | */ | |
2719 | if (IS_APPEND(inode)) { | |
8737c930 | 2720 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
7715b521 | 2721 | return -EPERM; |
1da177e4 | 2722 | if (flag & O_TRUNC) |
7715b521 | 2723 | return -EPERM; |
1da177e4 LT |
2724 | } |
2725 | ||
2726 | /* O_NOATIME can only be set by the owner or superuser */ | |
2e149670 | 2727 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
7715b521 | 2728 | return -EPERM; |
1da177e4 | 2729 | |
f3c7691e | 2730 | return 0; |
7715b521 | 2731 | } |
1da177e4 | 2732 | |
e1181ee6 | 2733 | static int handle_truncate(struct file *filp) |
7715b521 | 2734 | { |
e1181ee6 | 2735 | struct path *path = &filp->f_path; |
7715b521 AV |
2736 | struct inode *inode = path->dentry->d_inode; |
2737 | int error = get_write_access(inode); | |
2738 | if (error) | |
2739 | return error; | |
2740 | /* | |
2741 | * Refuse to truncate files with mandatory locks held on them. | |
2742 | */ | |
d7a06983 | 2743 | error = locks_verify_locked(filp); |
7715b521 | 2744 | if (!error) |
ea0d3ab2 | 2745 | error = security_path_truncate(path); |
7715b521 AV |
2746 | if (!error) { |
2747 | error = do_truncate(path->dentry, 0, | |
2748 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
e1181ee6 | 2749 | filp); |
7715b521 AV |
2750 | } |
2751 | put_write_access(inode); | |
acd0c935 | 2752 | return error; |
1da177e4 LT |
2753 | } |
2754 | ||
d57999e1 DH |
2755 | static inline int open_to_namei_flags(int flag) |
2756 | { | |
8a5e929d AV |
2757 | if ((flag & O_ACCMODE) == 3) |
2758 | flag--; | |
d57999e1 DH |
2759 | return flag; |
2760 | } | |
2761 | ||
d18e9008 MS |
2762 | static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) |
2763 | { | |
2764 | int error = security_path_mknod(dir, dentry, mode, 0); | |
2765 | if (error) | |
2766 | return error; | |
2767 | ||
2768 | error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); | |
2769 | if (error) | |
2770 | return error; | |
2771 | ||
2772 | return security_inode_create(dir->dentry->d_inode, dentry, mode); | |
2773 | } | |
2774 | ||
1acf0af9 DH |
2775 | /* |
2776 | * Attempt to atomically look up, create and open a file from a negative | |
2777 | * dentry. | |
2778 | * | |
2779 | * Returns 0 if successful. The file will have been created and attached to | |
2780 | * @file by the filesystem calling finish_open(). | |
2781 | * | |
2782 | * Returns 1 if the file was looked up only or didn't need creating. The | |
2783 | * caller will need to perform the open themselves. @path will have been | |
2784 | * updated to point to the new dentry. This may be negative. | |
2785 | * | |
2786 | * Returns an error code otherwise. | |
2787 | */ | |
2675a4eb AV |
2788 | static int atomic_open(struct nameidata *nd, struct dentry *dentry, |
2789 | struct path *path, struct file *file, | |
2790 | const struct open_flags *op, | |
64894cf8 | 2791 | bool got_write, bool need_lookup, |
2675a4eb | 2792 | int *opened) |
d18e9008 MS |
2793 | { |
2794 | struct inode *dir = nd->path.dentry->d_inode; | |
2795 | unsigned open_flag = open_to_namei_flags(op->open_flag); | |
2796 | umode_t mode; | |
2797 | int error; | |
2798 | int acc_mode; | |
d18e9008 MS |
2799 | int create_error = 0; |
2800 | struct dentry *const DENTRY_NOT_SET = (void *) -1UL; | |
116cc022 | 2801 | bool excl; |
d18e9008 MS |
2802 | |
2803 | BUG_ON(dentry->d_inode); | |
2804 | ||
2805 | /* Don't create child dentry for a dead directory. */ | |
2806 | if (unlikely(IS_DEADDIR(dir))) { | |
2675a4eb | 2807 | error = -ENOENT; |
d18e9008 MS |
2808 | goto out; |
2809 | } | |
2810 | ||
62b259d8 | 2811 | mode = op->mode; |
d18e9008 MS |
2812 | if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) |
2813 | mode &= ~current_umask(); | |
2814 | ||
116cc022 MS |
2815 | excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); |
2816 | if (excl) | |
d18e9008 | 2817 | open_flag &= ~O_TRUNC; |
d18e9008 MS |
2818 | |
2819 | /* | |
2820 | * Checking write permission is tricky, bacuse we don't know if we are | |
2821 | * going to actually need it: O_CREAT opens should work as long as the | |
2822 | * file exists. But checking existence breaks atomicity. The trick is | |
2823 | * to check access and if not granted clear O_CREAT from the flags. | |
2824 | * | |
2825 | * Another problem is returing the "right" error value (e.g. for an | |
2826 | * O_EXCL open we want to return EEXIST not EROFS). | |
2827 | */ | |
64894cf8 AV |
2828 | if (((open_flag & (O_CREAT | O_TRUNC)) || |
2829 | (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { | |
2830 | if (!(open_flag & O_CREAT)) { | |
d18e9008 MS |
2831 | /* |
2832 | * No O_CREATE -> atomicity not a requirement -> fall | |
2833 | * back to lookup + open | |
2834 | */ | |
2835 | goto no_open; | |
2836 | } else if (open_flag & (O_EXCL | O_TRUNC)) { | |
2837 | /* Fall back and fail with the right error */ | |
64894cf8 | 2838 | create_error = -EROFS; |
d18e9008 MS |
2839 | goto no_open; |
2840 | } else { | |
2841 | /* No side effects, safe to clear O_CREAT */ | |
64894cf8 | 2842 | create_error = -EROFS; |
d18e9008 MS |
2843 | open_flag &= ~O_CREAT; |
2844 | } | |
2845 | } | |
2846 | ||
2847 | if (open_flag & O_CREAT) { | |
38227f78 | 2848 | error = may_o_create(&nd->path, dentry, mode); |
d18e9008 MS |
2849 | if (error) { |
2850 | create_error = error; | |
2851 | if (open_flag & O_EXCL) | |
2852 | goto no_open; | |
2853 | open_flag &= ~O_CREAT; | |
2854 | } | |
2855 | } | |
2856 | ||
2857 | if (nd->flags & LOOKUP_DIRECTORY) | |
2858 | open_flag |= O_DIRECTORY; | |
2859 | ||
30d90494 AV |
2860 | file->f_path.dentry = DENTRY_NOT_SET; |
2861 | file->f_path.mnt = nd->path.mnt; | |
2862 | error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, | |
47237687 | 2863 | opened); |
d9585277 | 2864 | if (error < 0) { |
d9585277 AV |
2865 | if (create_error && error == -ENOENT) |
2866 | error = create_error; | |
d18e9008 MS |
2867 | goto out; |
2868 | } | |
2869 | ||
d9585277 | 2870 | if (error) { /* returned 1, that is */ |
30d90494 | 2871 | if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { |
2675a4eb | 2872 | error = -EIO; |
d18e9008 MS |
2873 | goto out; |
2874 | } | |
30d90494 | 2875 | if (file->f_path.dentry) { |
d18e9008 | 2876 | dput(dentry); |
30d90494 | 2877 | dentry = file->f_path.dentry; |
d18e9008 | 2878 | } |
03da633a AV |
2879 | if (*opened & FILE_CREATED) |
2880 | fsnotify_create(dir, dentry); | |
2881 | if (!dentry->d_inode) { | |
2882 | WARN_ON(*opened & FILE_CREATED); | |
2883 | if (create_error) { | |
2884 | error = create_error; | |
2885 | goto out; | |
2886 | } | |
2887 | } else { | |
2888 | if (excl && !(*opened & FILE_CREATED)) { | |
2889 | error = -EEXIST; | |
2890 | goto out; | |
2891 | } | |
62b2ce96 | 2892 | } |
d18e9008 MS |
2893 | goto looked_up; |
2894 | } | |
2895 | ||
2896 | /* | |
2897 | * We didn't have the inode before the open, so check open permission | |
2898 | * here. | |
2899 | */ | |
03da633a AV |
2900 | acc_mode = op->acc_mode; |
2901 | if (*opened & FILE_CREATED) { | |
2902 | WARN_ON(!(open_flag & O_CREAT)); | |
2903 | fsnotify_create(dir, dentry); | |
2904 | acc_mode = MAY_OPEN; | |
2905 | } | |
2675a4eb AV |
2906 | error = may_open(&file->f_path, acc_mode, open_flag); |
2907 | if (error) | |
2908 | fput(file); | |
d18e9008 MS |
2909 | |
2910 | out: | |
2911 | dput(dentry); | |
2675a4eb | 2912 | return error; |
d18e9008 | 2913 | |
d18e9008 MS |
2914 | no_open: |
2915 | if (need_lookup) { | |
72bd866a | 2916 | dentry = lookup_real(dir, dentry, nd->flags); |
d18e9008 | 2917 | if (IS_ERR(dentry)) |
2675a4eb | 2918 | return PTR_ERR(dentry); |
d18e9008 MS |
2919 | |
2920 | if (create_error) { | |
2921 | int open_flag = op->open_flag; | |
2922 | ||
2675a4eb | 2923 | error = create_error; |
d18e9008 MS |
2924 | if ((open_flag & O_EXCL)) { |
2925 | if (!dentry->d_inode) | |
2926 | goto out; | |
2927 | } else if (!dentry->d_inode) { | |
2928 | goto out; | |
2929 | } else if ((open_flag & O_TRUNC) && | |
e36cb0b8 | 2930 | d_is_reg(dentry)) { |
d18e9008 MS |
2931 | goto out; |
2932 | } | |
2933 | /* will fail later, go on to get the right error */ | |
2934 | } | |
2935 | } | |
2936 | looked_up: | |
2937 | path->dentry = dentry; | |
2938 | path->mnt = nd->path.mnt; | |
2675a4eb | 2939 | return 1; |
d18e9008 MS |
2940 | } |
2941 | ||
d58ffd35 | 2942 | /* |
1acf0af9 | 2943 | * Look up and maybe create and open the last component. |
d58ffd35 MS |
2944 | * |
2945 | * Must be called with i_mutex held on parent. | |
2946 | * | |
1acf0af9 DH |
2947 | * Returns 0 if the file was successfully atomically created (if necessary) and |
2948 | * opened. In this case the file will be returned attached to @file. | |
2949 | * | |
2950 | * Returns 1 if the file was not completely opened at this time, though lookups | |
2951 | * and creations will have been performed and the dentry returned in @path will | |
2952 | * be positive upon return if O_CREAT was specified. If O_CREAT wasn't | |
2953 | * specified then a negative dentry may be returned. | |
2954 | * | |
2955 | * An error code is returned otherwise. | |
2956 | * | |
2957 | * FILE_CREATE will be set in @*opened if the dentry was created and will be | |
2958 | * cleared otherwise prior to returning. | |
d58ffd35 | 2959 | */ |
2675a4eb AV |
2960 | static int lookup_open(struct nameidata *nd, struct path *path, |
2961 | struct file *file, | |
2962 | const struct open_flags *op, | |
64894cf8 | 2963 | bool got_write, int *opened) |
d58ffd35 MS |
2964 | { |
2965 | struct dentry *dir = nd->path.dentry; | |
54ef4872 | 2966 | struct inode *dir_inode = dir->d_inode; |
d58ffd35 MS |
2967 | struct dentry *dentry; |
2968 | int error; | |
54ef4872 | 2969 | bool need_lookup; |
d58ffd35 | 2970 | |
47237687 | 2971 | *opened &= ~FILE_CREATED; |
201f956e | 2972 | dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); |
d58ffd35 | 2973 | if (IS_ERR(dentry)) |
2675a4eb | 2974 | return PTR_ERR(dentry); |
d58ffd35 | 2975 | |
d18e9008 MS |
2976 | /* Cached positive dentry: will open in f_op->open */ |
2977 | if (!need_lookup && dentry->d_inode) | |
2978 | goto out_no_open; | |
2979 | ||
2980 | if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { | |
64894cf8 | 2981 | return atomic_open(nd, dentry, path, file, op, got_write, |
47237687 | 2982 | need_lookup, opened); |
d18e9008 MS |
2983 | } |
2984 | ||
54ef4872 MS |
2985 | if (need_lookup) { |
2986 | BUG_ON(dentry->d_inode); | |
2987 | ||
72bd866a | 2988 | dentry = lookup_real(dir_inode, dentry, nd->flags); |
54ef4872 | 2989 | if (IS_ERR(dentry)) |
2675a4eb | 2990 | return PTR_ERR(dentry); |
54ef4872 MS |
2991 | } |
2992 | ||
d58ffd35 MS |
2993 | /* Negative dentry, just create the file */ |
2994 | if (!dentry->d_inode && (op->open_flag & O_CREAT)) { | |
2995 | umode_t mode = op->mode; | |
2996 | if (!IS_POSIXACL(dir->d_inode)) | |
2997 | mode &= ~current_umask(); | |
2998 | /* | |
2999 | * This write is needed to ensure that a | |
3000 | * rw->ro transition does not occur between | |
3001 | * the time when the file is created and when | |
3002 | * a permanent write count is taken through | |
015c3bbc | 3003 | * the 'struct file' in finish_open(). |
d58ffd35 | 3004 | */ |
64894cf8 AV |
3005 | if (!got_write) { |
3006 | error = -EROFS; | |
d58ffd35 | 3007 | goto out_dput; |
64894cf8 | 3008 | } |
47237687 | 3009 | *opened |= FILE_CREATED; |
d58ffd35 MS |
3010 | error = security_path_mknod(&nd->path, dentry, mode, 0); |
3011 | if (error) | |
3012 | goto out_dput; | |
312b63fb AV |
3013 | error = vfs_create(dir->d_inode, dentry, mode, |
3014 | nd->flags & LOOKUP_EXCL); | |
d58ffd35 MS |
3015 | if (error) |
3016 | goto out_dput; | |
3017 | } | |
d18e9008 | 3018 | out_no_open: |
d58ffd35 MS |
3019 | path->dentry = dentry; |
3020 | path->mnt = nd->path.mnt; | |
2675a4eb | 3021 | return 1; |
d58ffd35 MS |
3022 | |
3023 | out_dput: | |
3024 | dput(dentry); | |
2675a4eb | 3025 | return error; |
d58ffd35 MS |
3026 | } |
3027 | ||
31e6b01f | 3028 | /* |
fe2d35ff | 3029 | * Handle the last step of open() |
31e6b01f | 3030 | */ |
896475d5 | 3031 | static int do_last(struct nameidata *nd, |
2675a4eb | 3032 | struct file *file, const struct open_flags *op, |
669abf4e | 3033 | int *opened, struct filename *name) |
fb1cc555 | 3034 | { |
a1e28038 | 3035 | struct dentry *dir = nd->path.dentry; |
ca344a89 | 3036 | int open_flag = op->open_flag; |
77d660a8 | 3037 | bool will_truncate = (open_flag & O_TRUNC) != 0; |
64894cf8 | 3038 | bool got_write = false; |
bcda7652 | 3039 | int acc_mode = op->acc_mode; |
254cf582 | 3040 | unsigned seq; |
a1eb3315 | 3041 | struct inode *inode; |
16b1c1cd | 3042 | struct path save_parent = { .dentry = NULL, .mnt = NULL }; |
896475d5 | 3043 | struct path path; |
16b1c1cd | 3044 | bool retried = false; |
16c2cd71 | 3045 | int error; |
1f36f774 | 3046 | |
c3e380b0 AV |
3047 | nd->flags &= ~LOOKUP_PARENT; |
3048 | nd->flags |= op->intent; | |
3049 | ||
bc77daa7 | 3050 | if (nd->last_type != LAST_NORM) { |
fe2d35ff | 3051 | error = handle_dots(nd, nd->last_type); |
deb106c6 | 3052 | if (unlikely(error)) |
2675a4eb | 3053 | return error; |
e83db167 | 3054 | goto finish_open; |
1f36f774 | 3055 | } |
67ee3ad2 | 3056 | |
ca344a89 | 3057 | if (!(open_flag & O_CREAT)) { |
fe2d35ff AV |
3058 | if (nd->last.name[nd->last.len]) |
3059 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
3060 | /* we _can_ be in RCU mode here */ | |
254cf582 | 3061 | error = lookup_fast(nd, &path, &inode, &seq); |
71574865 MS |
3062 | if (likely(!error)) |
3063 | goto finish_lookup; | |
3064 | ||
3065 | if (error < 0) | |
deb106c6 | 3066 | return error; |
71574865 MS |
3067 | |
3068 | BUG_ON(nd->inode != dir->d_inode); | |
b6183df7 MS |
3069 | } else { |
3070 | /* create side of things */ | |
3071 | /* | |
3072 | * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED | |
3073 | * has been cleared when we got to the last component we are | |
3074 | * about to look up | |
3075 | */ | |
3076 | error = complete_walk(nd); | |
e8bb73df | 3077 | if (error) |
2675a4eb | 3078 | return error; |
fe2d35ff | 3079 | |
33e2208a | 3080 | audit_inode(name, dir, LOOKUP_PARENT); |
b6183df7 | 3081 | /* trailing slashes? */ |
deb106c6 AV |
3082 | if (unlikely(nd->last.name[nd->last.len])) |
3083 | return -EISDIR; | |
b6183df7 | 3084 | } |
a2c36b45 | 3085 | |
16b1c1cd | 3086 | retry_lookup: |
64894cf8 AV |
3087 | if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { |
3088 | error = mnt_want_write(nd->path.mnt); | |
3089 | if (!error) | |
3090 | got_write = true; | |
3091 | /* | |
3092 | * do _not_ fail yet - we might not need that or fail with | |
3093 | * a different error; let lookup_open() decide; we'll be | |
3094 | * dropping this one anyway. | |
3095 | */ | |
3096 | } | |
a1e28038 | 3097 | mutex_lock(&dir->d_inode->i_mutex); |
896475d5 | 3098 | error = lookup_open(nd, &path, file, op, got_write, opened); |
d58ffd35 | 3099 | mutex_unlock(&dir->d_inode->i_mutex); |
a1e28038 | 3100 | |
2675a4eb AV |
3101 | if (error <= 0) { |
3102 | if (error) | |
d18e9008 MS |
3103 | goto out; |
3104 | ||
47237687 | 3105 | if ((*opened & FILE_CREATED) || |
496ad9aa | 3106 | !S_ISREG(file_inode(file)->i_mode)) |
77d660a8 | 3107 | will_truncate = false; |
d18e9008 | 3108 | |
adb5c247 | 3109 | audit_inode(name, file->f_path.dentry, 0); |
d18e9008 MS |
3110 | goto opened; |
3111 | } | |
fb1cc555 | 3112 | |
47237687 | 3113 | if (*opened & FILE_CREATED) { |
9b44f1b3 | 3114 | /* Don't check for write permission, don't truncate */ |
ca344a89 | 3115 | open_flag &= ~O_TRUNC; |
77d660a8 | 3116 | will_truncate = false; |
bcda7652 | 3117 | acc_mode = MAY_OPEN; |
896475d5 | 3118 | path_to_nameidata(&path, nd); |
e83db167 | 3119 | goto finish_open_created; |
fb1cc555 AV |
3120 | } |
3121 | ||
3122 | /* | |
3134f37e | 3123 | * create/update audit record if it already exists. |
fb1cc555 | 3124 | */ |
896475d5 AV |
3125 | if (d_is_positive(path.dentry)) |
3126 | audit_inode(name, path.dentry, 0); | |
fb1cc555 | 3127 | |
d18e9008 MS |
3128 | /* |
3129 | * If atomic_open() acquired write access it is dropped now due to | |
3130 | * possible mount and symlink following (this might be optimized away if | |
3131 | * necessary...) | |
3132 | */ | |
64894cf8 | 3133 | if (got_write) { |
d18e9008 | 3134 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 3135 | got_write = false; |
d18e9008 MS |
3136 | } |
3137 | ||
deb106c6 AV |
3138 | if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) { |
3139 | path_to_nameidata(&path, nd); | |
3140 | return -EEXIST; | |
3141 | } | |
fb1cc555 | 3142 | |
756daf26 | 3143 | error = follow_managed(&path, nd); |
deb106c6 AV |
3144 | if (unlikely(error < 0)) |
3145 | return error; | |
a3fbbde7 | 3146 | |
decf3400 | 3147 | BUG_ON(nd->flags & LOOKUP_RCU); |
63afdfc7 | 3148 | inode = d_backing_inode(path.dentry); |
254cf582 | 3149 | seq = 0; /* out of RCU mode, so the value doesn't matter */ |
deb106c6 | 3150 | if (unlikely(d_is_negative(path.dentry))) { |
896475d5 | 3151 | path_to_nameidata(&path, nd); |
deb106c6 | 3152 | return -ENOENT; |
54c33e7f | 3153 | } |
766c4cbf | 3154 | finish_lookup: |
d63ff28f AV |
3155 | if (nd->depth) |
3156 | put_link(nd); | |
181548c0 AV |
3157 | error = should_follow_link(nd, &path, nd->flags & LOOKUP_FOLLOW, |
3158 | inode, seq); | |
deb106c6 | 3159 | if (unlikely(error)) |
d63ff28f | 3160 | return error; |
fb1cc555 | 3161 | |
896475d5 AV |
3162 | if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { |
3163 | path_to_nameidata(&path, nd); | |
deb106c6 | 3164 | return -ELOOP; |
a5cfe2d5 AV |
3165 | } |
3166 | ||
896475d5 AV |
3167 | if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { |
3168 | path_to_nameidata(&path, nd); | |
16b1c1cd MS |
3169 | } else { |
3170 | save_parent.dentry = nd->path.dentry; | |
896475d5 AV |
3171 | save_parent.mnt = mntget(path.mnt); |
3172 | nd->path.dentry = path.dentry; | |
16b1c1cd MS |
3173 | |
3174 | } | |
decf3400 | 3175 | nd->inode = inode; |
254cf582 | 3176 | nd->seq = seq; |
a3fbbde7 | 3177 | /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ |
bc77daa7 | 3178 | finish_open: |
a3fbbde7 | 3179 | error = complete_walk(nd); |
16b1c1cd MS |
3180 | if (error) { |
3181 | path_put(&save_parent); | |
2675a4eb | 3182 | return error; |
16b1c1cd | 3183 | } |
bc77daa7 | 3184 | audit_inode(name, nd->path.dentry, 0); |
fb1cc555 | 3185 | error = -EISDIR; |
44b1d530 | 3186 | if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) |
2675a4eb | 3187 | goto out; |
af2f5542 | 3188 | error = -ENOTDIR; |
44b1d530 | 3189 | if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) |
2675a4eb | 3190 | goto out; |
4bbcbd3b | 3191 | if (!d_is_reg(nd->path.dentry)) |
77d660a8 | 3192 | will_truncate = false; |
6c0d46c4 | 3193 | |
0f9d1a10 AV |
3194 | if (will_truncate) { |
3195 | error = mnt_want_write(nd->path.mnt); | |
3196 | if (error) | |
2675a4eb | 3197 | goto out; |
64894cf8 | 3198 | got_write = true; |
0f9d1a10 | 3199 | } |
e83db167 | 3200 | finish_open_created: |
bcda7652 | 3201 | error = may_open(&nd->path, acc_mode, open_flag); |
ca344a89 | 3202 | if (error) |
2675a4eb | 3203 | goto out; |
4aa7c634 MS |
3204 | |
3205 | BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ | |
3206 | error = vfs_open(&nd->path, file, current_cred()); | |
3207 | if (!error) { | |
3208 | *opened |= FILE_OPENED; | |
3209 | } else { | |
30d90494 | 3210 | if (error == -EOPENSTALE) |
f60dc3db | 3211 | goto stale_open; |
015c3bbc | 3212 | goto out; |
f60dc3db | 3213 | } |
a8277b9b | 3214 | opened: |
2675a4eb | 3215 | error = open_check_o_direct(file); |
015c3bbc MS |
3216 | if (error) |
3217 | goto exit_fput; | |
3034a146 | 3218 | error = ima_file_check(file, op->acc_mode, *opened); |
aa4caadb MS |
3219 | if (error) |
3220 | goto exit_fput; | |
3221 | ||
3222 | if (will_truncate) { | |
2675a4eb | 3223 | error = handle_truncate(file); |
aa4caadb MS |
3224 | if (error) |
3225 | goto exit_fput; | |
0f9d1a10 | 3226 | } |
ca344a89 | 3227 | out: |
64894cf8 | 3228 | if (got_write) |
0f9d1a10 | 3229 | mnt_drop_write(nd->path.mnt); |
16b1c1cd | 3230 | path_put(&save_parent); |
2675a4eb | 3231 | return error; |
fb1cc555 | 3232 | |
015c3bbc | 3233 | exit_fput: |
2675a4eb AV |
3234 | fput(file); |
3235 | goto out; | |
015c3bbc | 3236 | |
f60dc3db MS |
3237 | stale_open: |
3238 | /* If no saved parent or already retried then can't retry */ | |
3239 | if (!save_parent.dentry || retried) | |
3240 | goto out; | |
3241 | ||
3242 | BUG_ON(save_parent.dentry != dir); | |
3243 | path_put(&nd->path); | |
3244 | nd->path = save_parent; | |
3245 | nd->inode = dir->d_inode; | |
3246 | save_parent.mnt = NULL; | |
3247 | save_parent.dentry = NULL; | |
64894cf8 | 3248 | if (got_write) { |
f60dc3db | 3249 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 3250 | got_write = false; |
f60dc3db MS |
3251 | } |
3252 | retried = true; | |
3253 | goto retry_lookup; | |
fb1cc555 AV |
3254 | } |
3255 | ||
60545d0d AV |
3256 | static int do_tmpfile(int dfd, struct filename *pathname, |
3257 | struct nameidata *nd, int flags, | |
3258 | const struct open_flags *op, | |
3259 | struct file *file, int *opened) | |
3260 | { | |
3261 | static const struct qstr name = QSTR_INIT("/", 1); | |
625b6d10 | 3262 | struct dentry *child; |
60545d0d | 3263 | struct inode *dir; |
625b6d10 | 3264 | struct path path; |
5eb6b495 | 3265 | int error = path_lookupat(dfd, pathname, |
625b6d10 | 3266 | flags | LOOKUP_DIRECTORY, nd, &path); |
60545d0d AV |
3267 | if (unlikely(error)) |
3268 | return error; | |
625b6d10 | 3269 | error = mnt_want_write(path.mnt); |
60545d0d AV |
3270 | if (unlikely(error)) |
3271 | goto out; | |
625b6d10 | 3272 | dir = path.dentry->d_inode; |
60545d0d | 3273 | /* we want directory to be writable */ |
625b6d10 | 3274 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
60545d0d AV |
3275 | if (error) |
3276 | goto out2; | |
60545d0d AV |
3277 | if (!dir->i_op->tmpfile) { |
3278 | error = -EOPNOTSUPP; | |
3279 | goto out2; | |
3280 | } | |
625b6d10 | 3281 | child = d_alloc(path.dentry, &name); |
60545d0d AV |
3282 | if (unlikely(!child)) { |
3283 | error = -ENOMEM; | |
3284 | goto out2; | |
3285 | } | |
625b6d10 AV |
3286 | dput(path.dentry); |
3287 | path.dentry = child; | |
3288 | error = dir->i_op->tmpfile(dir, child, op->mode); | |
60545d0d AV |
3289 | if (error) |
3290 | goto out2; | |
625b6d10 | 3291 | audit_inode(pathname, child, 0); |
69a91c23 | 3292 | /* Don't check for other permissions, the inode was just created */ |
625b6d10 | 3293 | error = may_open(&path, MAY_OPEN, op->open_flag); |
60545d0d AV |
3294 | if (error) |
3295 | goto out2; | |
625b6d10 AV |
3296 | file->f_path.mnt = path.mnt; |
3297 | error = finish_open(file, child, NULL, opened); | |
60545d0d AV |
3298 | if (error) |
3299 | goto out2; | |
3300 | error = open_check_o_direct(file); | |
f4e0c30c | 3301 | if (error) { |
60545d0d | 3302 | fput(file); |
f4e0c30c AV |
3303 | } else if (!(op->open_flag & O_EXCL)) { |
3304 | struct inode *inode = file_inode(file); | |
3305 | spin_lock(&inode->i_lock); | |
3306 | inode->i_state |= I_LINKABLE; | |
3307 | spin_unlock(&inode->i_lock); | |
3308 | } | |
60545d0d | 3309 | out2: |
625b6d10 | 3310 | mnt_drop_write(path.mnt); |
60545d0d | 3311 | out: |
625b6d10 | 3312 | path_put(&path); |
60545d0d AV |
3313 | return error; |
3314 | } | |
3315 | ||
669abf4e | 3316 | static struct file *path_openat(int dfd, struct filename *pathname, |
73d049a4 | 3317 | struct nameidata *nd, const struct open_flags *op, int flags) |
1da177e4 | 3318 | { |
368ee9ba | 3319 | const char *s; |
30d90494 | 3320 | struct file *file; |
47237687 | 3321 | int opened = 0; |
13aab428 | 3322 | int error; |
31e6b01f | 3323 | |
30d90494 | 3324 | file = get_empty_filp(); |
1afc99be AV |
3325 | if (IS_ERR(file)) |
3326 | return file; | |
31e6b01f | 3327 | |
30d90494 | 3328 | file->f_flags = op->open_flag; |
31e6b01f | 3329 | |
bb458c64 | 3330 | if (unlikely(file->f_flags & __O_TMPFILE)) { |
60545d0d | 3331 | error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); |
f15133df | 3332 | goto out2; |
60545d0d AV |
3333 | } |
3334 | ||
368ee9ba AV |
3335 | s = path_init(dfd, pathname, flags, nd); |
3336 | if (IS_ERR(s)) { | |
3337 | put_filp(file); | |
3338 | return ERR_CAST(s); | |
3339 | } | |
3bdba28b AV |
3340 | while (!(error = link_path_walk(s, nd)) && |
3341 | (error = do_last(nd, file, op, &opened, pathname)) > 0) { | |
73d049a4 | 3342 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); |
3bdba28b AV |
3343 | s = trailing_symlink(nd); |
3344 | if (IS_ERR(s)) { | |
3345 | error = PTR_ERR(s); | |
2675a4eb | 3346 | break; |
3bdba28b | 3347 | } |
806b681c | 3348 | } |
deb106c6 | 3349 | terminate_walk(nd); |
893b7775 | 3350 | path_cleanup(nd); |
f15133df | 3351 | out2: |
2675a4eb AV |
3352 | if (!(opened & FILE_OPENED)) { |
3353 | BUG_ON(!error); | |
30d90494 | 3354 | put_filp(file); |
16b1c1cd | 3355 | } |
2675a4eb AV |
3356 | if (unlikely(error)) { |
3357 | if (error == -EOPENSTALE) { | |
3358 | if (flags & LOOKUP_RCU) | |
3359 | error = -ECHILD; | |
3360 | else | |
3361 | error = -ESTALE; | |
3362 | } | |
3363 | file = ERR_PTR(error); | |
3364 | } | |
3365 | return file; | |
1da177e4 LT |
3366 | } |
3367 | ||
669abf4e | 3368 | struct file *do_filp_open(int dfd, struct filename *pathname, |
f9652e10 | 3369 | const struct open_flags *op) |
13aab428 | 3370 | { |
756daf26 | 3371 | struct nameidata nd, *saved_nd = set_nameidata(&nd); |
f9652e10 | 3372 | int flags = op->lookup_flags; |
13aab428 AV |
3373 | struct file *filp; |
3374 | ||
73d049a4 | 3375 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); |
13aab428 | 3376 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
73d049a4 | 3377 | filp = path_openat(dfd, pathname, &nd, op, flags); |
13aab428 | 3378 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
73d049a4 | 3379 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); |
756daf26 | 3380 | restore_nameidata(saved_nd); |
13aab428 AV |
3381 | return filp; |
3382 | } | |
3383 | ||
73d049a4 | 3384 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
f9652e10 | 3385 | const char *name, const struct open_flags *op) |
73d049a4 | 3386 | { |
756daf26 | 3387 | struct nameidata nd, *saved_nd; |
73d049a4 | 3388 | struct file *file; |
51689104 | 3389 | struct filename *filename; |
f9652e10 | 3390 | int flags = op->lookup_flags | LOOKUP_ROOT; |
73d049a4 AV |
3391 | |
3392 | nd.root.mnt = mnt; | |
3393 | nd.root.dentry = dentry; | |
3394 | ||
b18825a7 | 3395 | if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) |
73d049a4 AV |
3396 | return ERR_PTR(-ELOOP); |
3397 | ||
51689104 PM |
3398 | filename = getname_kernel(name); |
3399 | if (unlikely(IS_ERR(filename))) | |
3400 | return ERR_CAST(filename); | |
3401 | ||
756daf26 | 3402 | saved_nd = set_nameidata(&nd); |
51689104 | 3403 | file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); |
73d049a4 | 3404 | if (unlikely(file == ERR_PTR(-ECHILD))) |
51689104 | 3405 | file = path_openat(-1, filename, &nd, op, flags); |
73d049a4 | 3406 | if (unlikely(file == ERR_PTR(-ESTALE))) |
51689104 | 3407 | file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); |
756daf26 | 3408 | restore_nameidata(saved_nd); |
51689104 | 3409 | putname(filename); |
73d049a4 AV |
3410 | return file; |
3411 | } | |
3412 | ||
fa14a0b8 | 3413 | static struct dentry *filename_create(int dfd, struct filename *name, |
1ac12b4b | 3414 | struct path *path, unsigned int lookup_flags) |
1da177e4 | 3415 | { |
c663e5d8 | 3416 | struct dentry *dentry = ERR_PTR(-EEXIST); |
ed75e95d | 3417 | struct nameidata nd; |
c30dabfe | 3418 | int err2; |
1ac12b4b JL |
3419 | int error; |
3420 | bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); | |
3421 | ||
3422 | /* | |
3423 | * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any | |
3424 | * other flags passed in are ignored! | |
3425 | */ | |
3426 | lookup_flags &= LOOKUP_REVAL; | |
3427 | ||
8bcb77fa | 3428 | error = filename_parentat(dfd, name, lookup_flags, &nd); |
ed75e95d AV |
3429 | if (error) |
3430 | return ERR_PTR(error); | |
1da177e4 | 3431 | |
c663e5d8 CH |
3432 | /* |
3433 | * Yucky last component or no last component at all? | |
3434 | * (foo/., foo/.., /////) | |
3435 | */ | |
ed75e95d AV |
3436 | if (nd.last_type != LAST_NORM) |
3437 | goto out; | |
3438 | nd.flags &= ~LOOKUP_PARENT; | |
3439 | nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; | |
c663e5d8 | 3440 | |
c30dabfe JK |
3441 | /* don't fail immediately if it's r/o, at least try to report other errors */ |
3442 | err2 = mnt_want_write(nd.path.mnt); | |
c663e5d8 CH |
3443 | /* |
3444 | * Do the final lookup. | |
3445 | */ | |
ed75e95d | 3446 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
6a9f40d6 | 3447 | dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); |
1da177e4 | 3448 | if (IS_ERR(dentry)) |
a8104a9f | 3449 | goto unlock; |
c663e5d8 | 3450 | |
a8104a9f | 3451 | error = -EEXIST; |
b18825a7 | 3452 | if (d_is_positive(dentry)) |
a8104a9f | 3453 | goto fail; |
b18825a7 | 3454 | |
c663e5d8 CH |
3455 | /* |
3456 | * Special case - lookup gave negative, but... we had foo/bar/ | |
3457 | * From the vfs_mknod() POV we just have a negative dentry - | |
3458 | * all is fine. Let's be bastards - you had / on the end, you've | |
3459 | * been asking for (non-existent) directory. -ENOENT for you. | |
3460 | */ | |
ed75e95d | 3461 | if (unlikely(!is_dir && nd.last.name[nd.last.len])) { |
a8104a9f | 3462 | error = -ENOENT; |
ed75e95d | 3463 | goto fail; |
e9baf6e5 | 3464 | } |
c30dabfe JK |
3465 | if (unlikely(err2)) { |
3466 | error = err2; | |
a8104a9f | 3467 | goto fail; |
c30dabfe | 3468 | } |
ed75e95d | 3469 | *path = nd.path; |
1da177e4 | 3470 | return dentry; |
1da177e4 | 3471 | fail: |
a8104a9f AV |
3472 | dput(dentry); |
3473 | dentry = ERR_PTR(error); | |
3474 | unlock: | |
ed75e95d | 3475 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
c30dabfe JK |
3476 | if (!err2) |
3477 | mnt_drop_write(nd.path.mnt); | |
ed75e95d AV |
3478 | out: |
3479 | path_put(&nd.path); | |
1da177e4 LT |
3480 | return dentry; |
3481 | } | |
fa14a0b8 AV |
3482 | |
3483 | struct dentry *kern_path_create(int dfd, const char *pathname, | |
3484 | struct path *path, unsigned int lookup_flags) | |
3485 | { | |
51689104 PM |
3486 | struct filename *filename = getname_kernel(pathname); |
3487 | struct dentry *res; | |
3488 | ||
3489 | if (IS_ERR(filename)) | |
3490 | return ERR_CAST(filename); | |
3491 | res = filename_create(dfd, filename, path, lookup_flags); | |
3492 | putname(filename); | |
3493 | return res; | |
fa14a0b8 | 3494 | } |
dae6ad8f AV |
3495 | EXPORT_SYMBOL(kern_path_create); |
3496 | ||
921a1650 AV |
3497 | void done_path_create(struct path *path, struct dentry *dentry) |
3498 | { | |
3499 | dput(dentry); | |
3500 | mutex_unlock(&path->dentry->d_inode->i_mutex); | |
a8104a9f | 3501 | mnt_drop_write(path->mnt); |
921a1650 AV |
3502 | path_put(path); |
3503 | } | |
3504 | EXPORT_SYMBOL(done_path_create); | |
3505 | ||
1ac12b4b JL |
3506 | struct dentry *user_path_create(int dfd, const char __user *pathname, |
3507 | struct path *path, unsigned int lookup_flags) | |
dae6ad8f | 3508 | { |
91a27b2a | 3509 | struct filename *tmp = getname(pathname); |
dae6ad8f AV |
3510 | struct dentry *res; |
3511 | if (IS_ERR(tmp)) | |
3512 | return ERR_CAST(tmp); | |
fa14a0b8 | 3513 | res = filename_create(dfd, tmp, path, lookup_flags); |
dae6ad8f AV |
3514 | putname(tmp); |
3515 | return res; | |
3516 | } | |
3517 | EXPORT_SYMBOL(user_path_create); | |
3518 | ||
1a67aafb | 3519 | int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
1da177e4 | 3520 | { |
a95164d9 | 3521 | int error = may_create(dir, dentry); |
1da177e4 LT |
3522 | |
3523 | if (error) | |
3524 | return error; | |
3525 | ||
975d6b39 | 3526 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) |
1da177e4 LT |
3527 | return -EPERM; |
3528 | ||
acfa4380 | 3529 | if (!dir->i_op->mknod) |
1da177e4 LT |
3530 | return -EPERM; |
3531 | ||
08ce5f16 SH |
3532 | error = devcgroup_inode_mknod(mode, dev); |
3533 | if (error) | |
3534 | return error; | |
3535 | ||
1da177e4 LT |
3536 | error = security_inode_mknod(dir, dentry, mode, dev); |
3537 | if (error) | |
3538 | return error; | |
3539 | ||
1da177e4 | 3540 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 3541 | if (!error) |
f38aa942 | 3542 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3543 | return error; |
3544 | } | |
4d359507 | 3545 | EXPORT_SYMBOL(vfs_mknod); |
1da177e4 | 3546 | |
f69aac00 | 3547 | static int may_mknod(umode_t mode) |
463c3197 DH |
3548 | { |
3549 | switch (mode & S_IFMT) { | |
3550 | case S_IFREG: | |
3551 | case S_IFCHR: | |
3552 | case S_IFBLK: | |
3553 | case S_IFIFO: | |
3554 | case S_IFSOCK: | |
3555 | case 0: /* zero mode translates to S_IFREG */ | |
3556 | return 0; | |
3557 | case S_IFDIR: | |
3558 | return -EPERM; | |
3559 | default: | |
3560 | return -EINVAL; | |
3561 | } | |
3562 | } | |
3563 | ||
8208a22b | 3564 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, |
2e4d0924 | 3565 | unsigned, dev) |
1da177e4 | 3566 | { |
2ad94ae6 | 3567 | struct dentry *dentry; |
dae6ad8f AV |
3568 | struct path path; |
3569 | int error; | |
972567f1 | 3570 | unsigned int lookup_flags = 0; |
1da177e4 | 3571 | |
8e4bfca1 AV |
3572 | error = may_mknod(mode); |
3573 | if (error) | |
3574 | return error; | |
972567f1 JL |
3575 | retry: |
3576 | dentry = user_path_create(dfd, filename, &path, lookup_flags); | |
dae6ad8f AV |
3577 | if (IS_ERR(dentry)) |
3578 | return PTR_ERR(dentry); | |
2ad94ae6 | 3579 | |
dae6ad8f | 3580 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3581 | mode &= ~current_umask(); |
dae6ad8f | 3582 | error = security_path_mknod(&path, dentry, mode, dev); |
be6d3e56 | 3583 | if (error) |
a8104a9f | 3584 | goto out; |
463c3197 | 3585 | switch (mode & S_IFMT) { |
1da177e4 | 3586 | case 0: case S_IFREG: |
312b63fb | 3587 | error = vfs_create(path.dentry->d_inode,dentry,mode,true); |
1da177e4 LT |
3588 | break; |
3589 | case S_IFCHR: case S_IFBLK: | |
dae6ad8f | 3590 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
3591 | new_decode_dev(dev)); |
3592 | break; | |
3593 | case S_IFIFO: case S_IFSOCK: | |
dae6ad8f | 3594 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 3595 | break; |
1da177e4 | 3596 | } |
a8104a9f | 3597 | out: |
921a1650 | 3598 | done_path_create(&path, dentry); |
972567f1 JL |
3599 | if (retry_estale(error, lookup_flags)) { |
3600 | lookup_flags |= LOOKUP_REVAL; | |
3601 | goto retry; | |
3602 | } | |
1da177e4 LT |
3603 | return error; |
3604 | } | |
3605 | ||
8208a22b | 3606 | SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) |
5590ff0d UD |
3607 | { |
3608 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
3609 | } | |
3610 | ||
18bb1db3 | 3611 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
1da177e4 | 3612 | { |
a95164d9 | 3613 | int error = may_create(dir, dentry); |
8de52778 | 3614 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
3615 | |
3616 | if (error) | |
3617 | return error; | |
3618 | ||
acfa4380 | 3619 | if (!dir->i_op->mkdir) |
1da177e4 LT |
3620 | return -EPERM; |
3621 | ||
3622 | mode &= (S_IRWXUGO|S_ISVTX); | |
3623 | error = security_inode_mkdir(dir, dentry, mode); | |
3624 | if (error) | |
3625 | return error; | |
3626 | ||
8de52778 AV |
3627 | if (max_links && dir->i_nlink >= max_links) |
3628 | return -EMLINK; | |
3629 | ||
1da177e4 | 3630 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 3631 | if (!error) |
f38aa942 | 3632 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
3633 | return error; |
3634 | } | |
4d359507 | 3635 | EXPORT_SYMBOL(vfs_mkdir); |
1da177e4 | 3636 | |
a218d0fd | 3637 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) |
1da177e4 | 3638 | { |
6902d925 | 3639 | struct dentry *dentry; |
dae6ad8f AV |
3640 | struct path path; |
3641 | int error; | |
b76d8b82 | 3642 | unsigned int lookup_flags = LOOKUP_DIRECTORY; |
1da177e4 | 3643 | |
b76d8b82 JL |
3644 | retry: |
3645 | dentry = user_path_create(dfd, pathname, &path, lookup_flags); | |
6902d925 | 3646 | if (IS_ERR(dentry)) |
dae6ad8f | 3647 | return PTR_ERR(dentry); |
1da177e4 | 3648 | |
dae6ad8f | 3649 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3650 | mode &= ~current_umask(); |
dae6ad8f | 3651 | error = security_path_mkdir(&path, dentry, mode); |
a8104a9f AV |
3652 | if (!error) |
3653 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); | |
921a1650 | 3654 | done_path_create(&path, dentry); |
b76d8b82 JL |
3655 | if (retry_estale(error, lookup_flags)) { |
3656 | lookup_flags |= LOOKUP_REVAL; | |
3657 | goto retry; | |
3658 | } | |
1da177e4 LT |
3659 | return error; |
3660 | } | |
3661 | ||
a218d0fd | 3662 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) |
5590ff0d UD |
3663 | { |
3664 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
3665 | } | |
3666 | ||
1da177e4 | 3667 | /* |
a71905f0 | 3668 | * The dentry_unhash() helper will try to drop the dentry early: we |
c0d02594 | 3669 | * should have a usage count of 1 if we're the only user of this |
a71905f0 SW |
3670 | * dentry, and if that is true (possibly after pruning the dcache), |
3671 | * then we drop the dentry now. | |
1da177e4 LT |
3672 | * |
3673 | * A low-level filesystem can, if it choses, legally | |
3674 | * do a | |
3675 | * | |
3676 | * if (!d_unhashed(dentry)) | |
3677 | * return -EBUSY; | |
3678 | * | |
3679 | * if it cannot handle the case of removing a directory | |
3680 | * that is still in use by something else.. | |
3681 | */ | |
3682 | void dentry_unhash(struct dentry *dentry) | |
3683 | { | |
dc168427 | 3684 | shrink_dcache_parent(dentry); |
1da177e4 | 3685 | spin_lock(&dentry->d_lock); |
98474236 | 3686 | if (dentry->d_lockref.count == 1) |
1da177e4 LT |
3687 | __d_drop(dentry); |
3688 | spin_unlock(&dentry->d_lock); | |
1da177e4 | 3689 | } |
4d359507 | 3690 | EXPORT_SYMBOL(dentry_unhash); |
1da177e4 LT |
3691 | |
3692 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
3693 | { | |
3694 | int error = may_delete(dir, dentry, 1); | |
3695 | ||
3696 | if (error) | |
3697 | return error; | |
3698 | ||
acfa4380 | 3699 | if (!dir->i_op->rmdir) |
1da177e4 LT |
3700 | return -EPERM; |
3701 | ||
1d2ef590 | 3702 | dget(dentry); |
1b1dcc1b | 3703 | mutex_lock(&dentry->d_inode->i_mutex); |
912dbc15 SW |
3704 | |
3705 | error = -EBUSY; | |
7af1364f | 3706 | if (is_local_mountpoint(dentry)) |
912dbc15 SW |
3707 | goto out; |
3708 | ||
3709 | error = security_inode_rmdir(dir, dentry); | |
3710 | if (error) | |
3711 | goto out; | |
3712 | ||
3cebde24 | 3713 | shrink_dcache_parent(dentry); |
912dbc15 SW |
3714 | error = dir->i_op->rmdir(dir, dentry); |
3715 | if (error) | |
3716 | goto out; | |
3717 | ||
3718 | dentry->d_inode->i_flags |= S_DEAD; | |
3719 | dont_mount(dentry); | |
8ed936b5 | 3720 | detach_mounts(dentry); |
912dbc15 SW |
3721 | |
3722 | out: | |
1b1dcc1b | 3723 | mutex_unlock(&dentry->d_inode->i_mutex); |
1d2ef590 | 3724 | dput(dentry); |
912dbc15 | 3725 | if (!error) |
1da177e4 | 3726 | d_delete(dentry); |
1da177e4 LT |
3727 | return error; |
3728 | } | |
4d359507 | 3729 | EXPORT_SYMBOL(vfs_rmdir); |
1da177e4 | 3730 | |
5590ff0d | 3731 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
3732 | { |
3733 | int error = 0; | |
91a27b2a | 3734 | struct filename *name; |
1da177e4 | 3735 | struct dentry *dentry; |
f5beed75 AV |
3736 | struct path path; |
3737 | struct qstr last; | |
3738 | int type; | |
c6ee9206 JL |
3739 | unsigned int lookup_flags = 0; |
3740 | retry: | |
f5beed75 AV |
3741 | name = user_path_parent(dfd, pathname, |
3742 | &path, &last, &type, lookup_flags); | |
91a27b2a JL |
3743 | if (IS_ERR(name)) |
3744 | return PTR_ERR(name); | |
1da177e4 | 3745 | |
f5beed75 | 3746 | switch (type) { |
0612d9fb OH |
3747 | case LAST_DOTDOT: |
3748 | error = -ENOTEMPTY; | |
3749 | goto exit1; | |
3750 | case LAST_DOT: | |
3751 | error = -EINVAL; | |
3752 | goto exit1; | |
3753 | case LAST_ROOT: | |
3754 | error = -EBUSY; | |
3755 | goto exit1; | |
1da177e4 | 3756 | } |
0612d9fb | 3757 | |
f5beed75 | 3758 | error = mnt_want_write(path.mnt); |
c30dabfe JK |
3759 | if (error) |
3760 | goto exit1; | |
0612d9fb | 3761 | |
f5beed75 AV |
3762 | mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
3763 | dentry = __lookup_hash(&last, path.dentry, lookup_flags); | |
1da177e4 | 3764 | error = PTR_ERR(dentry); |
6902d925 DH |
3765 | if (IS_ERR(dentry)) |
3766 | goto exit2; | |
e6bc45d6 TT |
3767 | if (!dentry->d_inode) { |
3768 | error = -ENOENT; | |
3769 | goto exit3; | |
3770 | } | |
f5beed75 | 3771 | error = security_path_rmdir(&path, dentry); |
be6d3e56 | 3772 | if (error) |
c30dabfe | 3773 | goto exit3; |
f5beed75 | 3774 | error = vfs_rmdir(path.dentry->d_inode, dentry); |
0622753b | 3775 | exit3: |
6902d925 DH |
3776 | dput(dentry); |
3777 | exit2: | |
f5beed75 AV |
3778 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
3779 | mnt_drop_write(path.mnt); | |
1da177e4 | 3780 | exit1: |
f5beed75 | 3781 | path_put(&path); |
1da177e4 | 3782 | putname(name); |
c6ee9206 JL |
3783 | if (retry_estale(error, lookup_flags)) { |
3784 | lookup_flags |= LOOKUP_REVAL; | |
3785 | goto retry; | |
3786 | } | |
1da177e4 LT |
3787 | return error; |
3788 | } | |
3789 | ||
3cdad428 | 3790 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
3791 | { |
3792 | return do_rmdir(AT_FDCWD, pathname); | |
3793 | } | |
3794 | ||
b21996e3 BF |
3795 | /** |
3796 | * vfs_unlink - unlink a filesystem object | |
3797 | * @dir: parent directory | |
3798 | * @dentry: victim | |
3799 | * @delegated_inode: returns victim inode, if the inode is delegated. | |
3800 | * | |
3801 | * The caller must hold dir->i_mutex. | |
3802 | * | |
3803 | * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and | |
3804 | * return a reference to the inode in delegated_inode. The caller | |
3805 | * should then break the delegation on that inode and retry. Because | |
3806 | * breaking a delegation may take a long time, the caller should drop | |
3807 | * dir->i_mutex before doing so. | |
3808 | * | |
3809 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
3810 | * be appropriate for callers that expect the underlying filesystem not | |
3811 | * to be NFS exported. | |
3812 | */ | |
3813 | int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) | |
1da177e4 | 3814 | { |
9accbb97 | 3815 | struct inode *target = dentry->d_inode; |
1da177e4 LT |
3816 | int error = may_delete(dir, dentry, 0); |
3817 | ||
3818 | if (error) | |
3819 | return error; | |
3820 | ||
acfa4380 | 3821 | if (!dir->i_op->unlink) |
1da177e4 LT |
3822 | return -EPERM; |
3823 | ||
9accbb97 | 3824 | mutex_lock(&target->i_mutex); |
8ed936b5 | 3825 | if (is_local_mountpoint(dentry)) |
1da177e4 LT |
3826 | error = -EBUSY; |
3827 | else { | |
3828 | error = security_inode_unlink(dir, dentry); | |
bec1052e | 3829 | if (!error) { |
5a14696c BF |
3830 | error = try_break_deleg(target, delegated_inode); |
3831 | if (error) | |
b21996e3 | 3832 | goto out; |
1da177e4 | 3833 | error = dir->i_op->unlink(dir, dentry); |
8ed936b5 | 3834 | if (!error) { |
d83c49f3 | 3835 | dont_mount(dentry); |
8ed936b5 EB |
3836 | detach_mounts(dentry); |
3837 | } | |
bec1052e | 3838 | } |
1da177e4 | 3839 | } |
b21996e3 | 3840 | out: |
9accbb97 | 3841 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
3842 | |
3843 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
3844 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
9accbb97 | 3845 | fsnotify_link_count(target); |
e234f35c | 3846 | d_delete(dentry); |
1da177e4 | 3847 | } |
0eeca283 | 3848 | |
1da177e4 LT |
3849 | return error; |
3850 | } | |
4d359507 | 3851 | EXPORT_SYMBOL(vfs_unlink); |
1da177e4 LT |
3852 | |
3853 | /* | |
3854 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 3855 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
3856 | * writeout happening, and we don't want to prevent access to the directory |
3857 | * while waiting on the I/O. | |
3858 | */ | |
5590ff0d | 3859 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 3860 | { |
2ad94ae6 | 3861 | int error; |
91a27b2a | 3862 | struct filename *name; |
1da177e4 | 3863 | struct dentry *dentry; |
f5beed75 AV |
3864 | struct path path; |
3865 | struct qstr last; | |
3866 | int type; | |
1da177e4 | 3867 | struct inode *inode = NULL; |
b21996e3 | 3868 | struct inode *delegated_inode = NULL; |
5d18f813 JL |
3869 | unsigned int lookup_flags = 0; |
3870 | retry: | |
f5beed75 AV |
3871 | name = user_path_parent(dfd, pathname, |
3872 | &path, &last, &type, lookup_flags); | |
91a27b2a JL |
3873 | if (IS_ERR(name)) |
3874 | return PTR_ERR(name); | |
2ad94ae6 | 3875 | |
1da177e4 | 3876 | error = -EISDIR; |
f5beed75 | 3877 | if (type != LAST_NORM) |
1da177e4 | 3878 | goto exit1; |
0612d9fb | 3879 | |
f5beed75 | 3880 | error = mnt_want_write(path.mnt); |
c30dabfe JK |
3881 | if (error) |
3882 | goto exit1; | |
b21996e3 | 3883 | retry_deleg: |
f5beed75 AV |
3884 | mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
3885 | dentry = __lookup_hash(&last, path.dentry, lookup_flags); | |
1da177e4 LT |
3886 | error = PTR_ERR(dentry); |
3887 | if (!IS_ERR(dentry)) { | |
3888 | /* Why not before? Because we want correct error value */ | |
f5beed75 | 3889 | if (last.name[last.len]) |
50338b88 | 3890 | goto slashes; |
1da177e4 | 3891 | inode = dentry->d_inode; |
b18825a7 | 3892 | if (d_is_negative(dentry)) |
e6bc45d6 TT |
3893 | goto slashes; |
3894 | ihold(inode); | |
f5beed75 | 3895 | error = security_path_unlink(&path, dentry); |
be6d3e56 | 3896 | if (error) |
c30dabfe | 3897 | goto exit2; |
f5beed75 | 3898 | error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); |
c30dabfe | 3899 | exit2: |
1da177e4 LT |
3900 | dput(dentry); |
3901 | } | |
f5beed75 | 3902 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
1da177e4 LT |
3903 | if (inode) |
3904 | iput(inode); /* truncate the inode here */ | |
b21996e3 BF |
3905 | inode = NULL; |
3906 | if (delegated_inode) { | |
5a14696c | 3907 | error = break_deleg_wait(&delegated_inode); |
b21996e3 BF |
3908 | if (!error) |
3909 | goto retry_deleg; | |
3910 | } | |
f5beed75 | 3911 | mnt_drop_write(path.mnt); |
1da177e4 | 3912 | exit1: |
f5beed75 | 3913 | path_put(&path); |
1da177e4 | 3914 | putname(name); |
5d18f813 JL |
3915 | if (retry_estale(error, lookup_flags)) { |
3916 | lookup_flags |= LOOKUP_REVAL; | |
3917 | inode = NULL; | |
3918 | goto retry; | |
3919 | } | |
1da177e4 LT |
3920 | return error; |
3921 | ||
3922 | slashes: | |
b18825a7 DH |
3923 | if (d_is_negative(dentry)) |
3924 | error = -ENOENT; | |
44b1d530 | 3925 | else if (d_is_dir(dentry)) |
b18825a7 DH |
3926 | error = -EISDIR; |
3927 | else | |
3928 | error = -ENOTDIR; | |
1da177e4 LT |
3929 | goto exit2; |
3930 | } | |
3931 | ||
2e4d0924 | 3932 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
3933 | { |
3934 | if ((flag & ~AT_REMOVEDIR) != 0) | |
3935 | return -EINVAL; | |
3936 | ||
3937 | if (flag & AT_REMOVEDIR) | |
3938 | return do_rmdir(dfd, pathname); | |
3939 | ||
3940 | return do_unlinkat(dfd, pathname); | |
3941 | } | |
3942 | ||
3480b257 | 3943 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
3944 | { |
3945 | return do_unlinkat(AT_FDCWD, pathname); | |
3946 | } | |
3947 | ||
db2e747b | 3948 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 3949 | { |
a95164d9 | 3950 | int error = may_create(dir, dentry); |
1da177e4 LT |
3951 | |
3952 | if (error) | |
3953 | return error; | |
3954 | ||
acfa4380 | 3955 | if (!dir->i_op->symlink) |
1da177e4 LT |
3956 | return -EPERM; |
3957 | ||
3958 | error = security_inode_symlink(dir, dentry, oldname); | |
3959 | if (error) | |
3960 | return error; | |
3961 | ||
1da177e4 | 3962 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 3963 | if (!error) |
f38aa942 | 3964 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3965 | return error; |
3966 | } | |
4d359507 | 3967 | EXPORT_SYMBOL(vfs_symlink); |
1da177e4 | 3968 | |
2e4d0924 HC |
3969 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
3970 | int, newdfd, const char __user *, newname) | |
1da177e4 | 3971 | { |
2ad94ae6 | 3972 | int error; |
91a27b2a | 3973 | struct filename *from; |
6902d925 | 3974 | struct dentry *dentry; |
dae6ad8f | 3975 | struct path path; |
f46d3567 | 3976 | unsigned int lookup_flags = 0; |
1da177e4 LT |
3977 | |
3978 | from = getname(oldname); | |
2ad94ae6 | 3979 | if (IS_ERR(from)) |
1da177e4 | 3980 | return PTR_ERR(from); |
f46d3567 JL |
3981 | retry: |
3982 | dentry = user_path_create(newdfd, newname, &path, lookup_flags); | |
6902d925 DH |
3983 | error = PTR_ERR(dentry); |
3984 | if (IS_ERR(dentry)) | |
dae6ad8f | 3985 | goto out_putname; |
6902d925 | 3986 | |
91a27b2a | 3987 | error = security_path_symlink(&path, dentry, from->name); |
a8104a9f | 3988 | if (!error) |
91a27b2a | 3989 | error = vfs_symlink(path.dentry->d_inode, dentry, from->name); |
921a1650 | 3990 | done_path_create(&path, dentry); |
f46d3567 JL |
3991 | if (retry_estale(error, lookup_flags)) { |
3992 | lookup_flags |= LOOKUP_REVAL; | |
3993 | goto retry; | |
3994 | } | |
6902d925 | 3995 | out_putname: |
1da177e4 LT |
3996 | putname(from); |
3997 | return error; | |
3998 | } | |
3999 | ||
3480b257 | 4000 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
4001 | { |
4002 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
4003 | } | |
4004 | ||
146a8595 BF |
4005 | /** |
4006 | * vfs_link - create a new link | |
4007 | * @old_dentry: object to be linked | |
4008 | * @dir: new parent | |
4009 | * @new_dentry: where to create the new link | |
4010 | * @delegated_inode: returns inode needing a delegation break | |
4011 | * | |
4012 | * The caller must hold dir->i_mutex | |
4013 | * | |
4014 | * If vfs_link discovers a delegation on the to-be-linked file in need | |
4015 | * of breaking, it will return -EWOULDBLOCK and return a reference to the | |
4016 | * inode in delegated_inode. The caller should then break the delegation | |
4017 | * and retry. Because breaking a delegation may take a long time, the | |
4018 | * caller should drop the i_mutex before doing so. | |
4019 | * | |
4020 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
4021 | * be appropriate for callers that expect the underlying filesystem not | |
4022 | * to be NFS exported. | |
4023 | */ | |
4024 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) | |
1da177e4 LT |
4025 | { |
4026 | struct inode *inode = old_dentry->d_inode; | |
8de52778 | 4027 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
4028 | int error; |
4029 | ||
4030 | if (!inode) | |
4031 | return -ENOENT; | |
4032 | ||
a95164d9 | 4033 | error = may_create(dir, new_dentry); |
1da177e4 LT |
4034 | if (error) |
4035 | return error; | |
4036 | ||
4037 | if (dir->i_sb != inode->i_sb) | |
4038 | return -EXDEV; | |
4039 | ||
4040 | /* | |
4041 | * A link to an append-only or immutable file cannot be created. | |
4042 | */ | |
4043 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
4044 | return -EPERM; | |
acfa4380 | 4045 | if (!dir->i_op->link) |
1da177e4 | 4046 | return -EPERM; |
7e79eedb | 4047 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
4048 | return -EPERM; |
4049 | ||
4050 | error = security_inode_link(old_dentry, dir, new_dentry); | |
4051 | if (error) | |
4052 | return error; | |
4053 | ||
7e79eedb | 4054 | mutex_lock(&inode->i_mutex); |
aae8a97d | 4055 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
f4e0c30c | 4056 | if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) |
aae8a97d | 4057 | error = -ENOENT; |
8de52778 AV |
4058 | else if (max_links && inode->i_nlink >= max_links) |
4059 | error = -EMLINK; | |
146a8595 BF |
4060 | else { |
4061 | error = try_break_deleg(inode, delegated_inode); | |
4062 | if (!error) | |
4063 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
4064 | } | |
f4e0c30c AV |
4065 | |
4066 | if (!error && (inode->i_state & I_LINKABLE)) { | |
4067 | spin_lock(&inode->i_lock); | |
4068 | inode->i_state &= ~I_LINKABLE; | |
4069 | spin_unlock(&inode->i_lock); | |
4070 | } | |
7e79eedb | 4071 | mutex_unlock(&inode->i_mutex); |
e31e14ec | 4072 | if (!error) |
7e79eedb | 4073 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
4074 | return error; |
4075 | } | |
4d359507 | 4076 | EXPORT_SYMBOL(vfs_link); |
1da177e4 LT |
4077 | |
4078 | /* | |
4079 | * Hardlinks are often used in delicate situations. We avoid | |
4080 | * security-related surprises by not following symlinks on the | |
4081 | * newname. --KAB | |
4082 | * | |
4083 | * We don't follow them on the oldname either to be compatible | |
4084 | * with linux 2.0, and to avoid hard-linking to directories | |
4085 | * and other special files. --ADM | |
4086 | */ | |
2e4d0924 HC |
4087 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
4088 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
4089 | { |
4090 | struct dentry *new_dentry; | |
dae6ad8f | 4091 | struct path old_path, new_path; |
146a8595 | 4092 | struct inode *delegated_inode = NULL; |
11a7b371 | 4093 | int how = 0; |
1da177e4 | 4094 | int error; |
1da177e4 | 4095 | |
11a7b371 | 4096 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
c04030e1 | 4097 | return -EINVAL; |
11a7b371 | 4098 | /* |
f0cc6ffb LT |
4099 | * To use null names we require CAP_DAC_READ_SEARCH |
4100 | * This ensures that not everyone will be able to create | |
4101 | * handlink using the passed filedescriptor. | |
11a7b371 | 4102 | */ |
f0cc6ffb LT |
4103 | if (flags & AT_EMPTY_PATH) { |
4104 | if (!capable(CAP_DAC_READ_SEARCH)) | |
4105 | return -ENOENT; | |
11a7b371 | 4106 | how = LOOKUP_EMPTY; |
f0cc6ffb | 4107 | } |
11a7b371 AK |
4108 | |
4109 | if (flags & AT_SYMLINK_FOLLOW) | |
4110 | how |= LOOKUP_FOLLOW; | |
442e31ca | 4111 | retry: |
11a7b371 | 4112 | error = user_path_at(olddfd, oldname, how, &old_path); |
1da177e4 | 4113 | if (error) |
2ad94ae6 AV |
4114 | return error; |
4115 | ||
442e31ca JL |
4116 | new_dentry = user_path_create(newdfd, newname, &new_path, |
4117 | (how & LOOKUP_REVAL)); | |
1da177e4 | 4118 | error = PTR_ERR(new_dentry); |
6902d925 | 4119 | if (IS_ERR(new_dentry)) |
dae6ad8f AV |
4120 | goto out; |
4121 | ||
4122 | error = -EXDEV; | |
4123 | if (old_path.mnt != new_path.mnt) | |
4124 | goto out_dput; | |
800179c9 KC |
4125 | error = may_linkat(&old_path); |
4126 | if (unlikely(error)) | |
4127 | goto out_dput; | |
dae6ad8f | 4128 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
be6d3e56 | 4129 | if (error) |
a8104a9f | 4130 | goto out_dput; |
146a8595 | 4131 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); |
75c3f29d | 4132 | out_dput: |
921a1650 | 4133 | done_path_create(&new_path, new_dentry); |
146a8595 BF |
4134 | if (delegated_inode) { |
4135 | error = break_deleg_wait(&delegated_inode); | |
d22e6338 OD |
4136 | if (!error) { |
4137 | path_put(&old_path); | |
146a8595 | 4138 | goto retry; |
d22e6338 | 4139 | } |
146a8595 | 4140 | } |
442e31ca | 4141 | if (retry_estale(error, how)) { |
d22e6338 | 4142 | path_put(&old_path); |
442e31ca JL |
4143 | how |= LOOKUP_REVAL; |
4144 | goto retry; | |
4145 | } | |
1da177e4 | 4146 | out: |
2d8f3038 | 4147 | path_put(&old_path); |
1da177e4 LT |
4148 | |
4149 | return error; | |
4150 | } | |
4151 | ||
3480b257 | 4152 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 4153 | { |
c04030e1 | 4154 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
4155 | } |
4156 | ||
bc27027a MS |
4157 | /** |
4158 | * vfs_rename - rename a filesystem object | |
4159 | * @old_dir: parent of source | |
4160 | * @old_dentry: source | |
4161 | * @new_dir: parent of destination | |
4162 | * @new_dentry: destination | |
4163 | * @delegated_inode: returns an inode needing a delegation break | |
520c8b16 | 4164 | * @flags: rename flags |
bc27027a MS |
4165 | * |
4166 | * The caller must hold multiple mutexes--see lock_rename()). | |
4167 | * | |
4168 | * If vfs_rename discovers a delegation in need of breaking at either | |
4169 | * the source or destination, it will return -EWOULDBLOCK and return a | |
4170 | * reference to the inode in delegated_inode. The caller should then | |
4171 | * break the delegation and retry. Because breaking a delegation may | |
4172 | * take a long time, the caller should drop all locks before doing | |
4173 | * so. | |
4174 | * | |
4175 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
4176 | * be appropriate for callers that expect the underlying filesystem not | |
4177 | * to be NFS exported. | |
4178 | * | |
1da177e4 LT |
4179 | * The worst of all namespace operations - renaming directory. "Perverted" |
4180 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
4181 | * Problems: | |
d03b29a2 | 4182 | * a) we can get into loop creation. |
1da177e4 LT |
4183 | * b) race potential - two innocent renames can create a loop together. |
4184 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 4185 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 | 4186 | * story. |
6cedba89 BF |
4187 | * c) we have to lock _four_ objects - parents and victim (if it exists), |
4188 | * and source (if it is not a directory). | |
1b1dcc1b | 4189 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
4190 | * whether the target exists). Solution: try to be smart with locking |
4191 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 4192 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
4193 | * move will be locked. Thus we can rank directories by the tree |
4194 | * (ancestors first) and rank all non-directories after them. | |
4195 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 4196 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
4197 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
4198 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
4199 | * we'd better make sure that there's no link(2) for them. | |
e4eaac06 | 4200 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
1b1dcc1b | 4201 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 4202 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
c41b20e7 | 4203 | * ->i_mutex on parents, which works but leads to some truly excessive |
1da177e4 LT |
4204 | * locking]. |
4205 | */ | |
bc27027a MS |
4206 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, |
4207 | struct inode *new_dir, struct dentry *new_dentry, | |
520c8b16 | 4208 | struct inode **delegated_inode, unsigned int flags) |
1da177e4 | 4209 | { |
bc27027a MS |
4210 | int error; |
4211 | bool is_dir = d_is_dir(old_dentry); | |
4212 | const unsigned char *old_name; | |
4213 | struct inode *source = old_dentry->d_inode; | |
9055cba7 | 4214 | struct inode *target = new_dentry->d_inode; |
da1ce067 MS |
4215 | bool new_is_dir = false; |
4216 | unsigned max_links = new_dir->i_sb->s_max_links; | |
bc27027a MS |
4217 | |
4218 | if (source == target) | |
4219 | return 0; | |
4220 | ||
4221 | error = may_delete(old_dir, old_dentry, is_dir); | |
4222 | if (error) | |
4223 | return error; | |
4224 | ||
da1ce067 | 4225 | if (!target) { |
bc27027a | 4226 | error = may_create(new_dir, new_dentry); |
da1ce067 MS |
4227 | } else { |
4228 | new_is_dir = d_is_dir(new_dentry); | |
4229 | ||
4230 | if (!(flags & RENAME_EXCHANGE)) | |
4231 | error = may_delete(new_dir, new_dentry, is_dir); | |
4232 | else | |
4233 | error = may_delete(new_dir, new_dentry, new_is_dir); | |
4234 | } | |
bc27027a MS |
4235 | if (error) |
4236 | return error; | |
4237 | ||
7177a9c4 | 4238 | if (!old_dir->i_op->rename && !old_dir->i_op->rename2) |
bc27027a | 4239 | return -EPERM; |
1da177e4 | 4240 | |
520c8b16 MS |
4241 | if (flags && !old_dir->i_op->rename2) |
4242 | return -EINVAL; | |
4243 | ||
1da177e4 LT |
4244 | /* |
4245 | * If we are going to change the parent - check write permissions, | |
4246 | * we'll need to flip '..'. | |
4247 | */ | |
da1ce067 MS |
4248 | if (new_dir != old_dir) { |
4249 | if (is_dir) { | |
4250 | error = inode_permission(source, MAY_WRITE); | |
4251 | if (error) | |
4252 | return error; | |
4253 | } | |
4254 | if ((flags & RENAME_EXCHANGE) && new_is_dir) { | |
4255 | error = inode_permission(target, MAY_WRITE); | |
4256 | if (error) | |
4257 | return error; | |
4258 | } | |
1da177e4 LT |
4259 | } |
4260 | ||
0b3974eb MS |
4261 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, |
4262 | flags); | |
1da177e4 LT |
4263 | if (error) |
4264 | return error; | |
4265 | ||
bc27027a | 4266 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
1d2ef590 | 4267 | dget(new_dentry); |
da1ce067 | 4268 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
bc27027a MS |
4269 | lock_two_nondirectories(source, target); |
4270 | else if (target) | |
1b1dcc1b | 4271 | mutex_lock(&target->i_mutex); |
9055cba7 SW |
4272 | |
4273 | error = -EBUSY; | |
7af1364f | 4274 | if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) |
9055cba7 SW |
4275 | goto out; |
4276 | ||
da1ce067 | 4277 | if (max_links && new_dir != old_dir) { |
bc27027a | 4278 | error = -EMLINK; |
da1ce067 | 4279 | if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) |
bc27027a | 4280 | goto out; |
da1ce067 MS |
4281 | if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && |
4282 | old_dir->i_nlink >= max_links) | |
4283 | goto out; | |
4284 | } | |
4285 | if (is_dir && !(flags & RENAME_EXCHANGE) && target) | |
4286 | shrink_dcache_parent(new_dentry); | |
4287 | if (!is_dir) { | |
bc27027a | 4288 | error = try_break_deleg(source, delegated_inode); |
8e6d782c BF |
4289 | if (error) |
4290 | goto out; | |
da1ce067 MS |
4291 | } |
4292 | if (target && !new_is_dir) { | |
4293 | error = try_break_deleg(target, delegated_inode); | |
4294 | if (error) | |
4295 | goto out; | |
8e6d782c | 4296 | } |
7177a9c4 | 4297 | if (!old_dir->i_op->rename2) { |
520c8b16 MS |
4298 | error = old_dir->i_op->rename(old_dir, old_dentry, |
4299 | new_dir, new_dentry); | |
4300 | } else { | |
7177a9c4 | 4301 | WARN_ON(old_dir->i_op->rename != NULL); |
520c8b16 MS |
4302 | error = old_dir->i_op->rename2(old_dir, old_dentry, |
4303 | new_dir, new_dentry, flags); | |
4304 | } | |
51892bbb SW |
4305 | if (error) |
4306 | goto out; | |
4307 | ||
da1ce067 | 4308 | if (!(flags & RENAME_EXCHANGE) && target) { |
bc27027a MS |
4309 | if (is_dir) |
4310 | target->i_flags |= S_DEAD; | |
51892bbb | 4311 | dont_mount(new_dentry); |
8ed936b5 | 4312 | detach_mounts(new_dentry); |
bc27027a | 4313 | } |
da1ce067 MS |
4314 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { |
4315 | if (!(flags & RENAME_EXCHANGE)) | |
4316 | d_move(old_dentry, new_dentry); | |
4317 | else | |
4318 | d_exchange(old_dentry, new_dentry); | |
4319 | } | |
51892bbb | 4320 | out: |
da1ce067 | 4321 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
bc27027a MS |
4322 | unlock_two_nondirectories(source, target); |
4323 | else if (target) | |
4324 | mutex_unlock(&target->i_mutex); | |
1da177e4 | 4325 | dput(new_dentry); |
da1ce067 | 4326 | if (!error) { |
123df294 | 4327 | fsnotify_move(old_dir, new_dir, old_name, is_dir, |
da1ce067 MS |
4328 | !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); |
4329 | if (flags & RENAME_EXCHANGE) { | |
4330 | fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, | |
4331 | new_is_dir, NULL, new_dentry); | |
4332 | } | |
4333 | } | |
0eeca283 RL |
4334 | fsnotify_oldname_free(old_name); |
4335 | ||
1da177e4 LT |
4336 | return error; |
4337 | } | |
4d359507 | 4338 | EXPORT_SYMBOL(vfs_rename); |
1da177e4 | 4339 | |
520c8b16 MS |
4340 | SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, |
4341 | int, newdfd, const char __user *, newname, unsigned int, flags) | |
1da177e4 | 4342 | { |
2ad94ae6 AV |
4343 | struct dentry *old_dentry, *new_dentry; |
4344 | struct dentry *trap; | |
f5beed75 AV |
4345 | struct path old_path, new_path; |
4346 | struct qstr old_last, new_last; | |
4347 | int old_type, new_type; | |
8e6d782c | 4348 | struct inode *delegated_inode = NULL; |
91a27b2a JL |
4349 | struct filename *from; |
4350 | struct filename *to; | |
f5beed75 | 4351 | unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; |
c6a94284 | 4352 | bool should_retry = false; |
2ad94ae6 | 4353 | int error; |
520c8b16 | 4354 | |
0d7a8555 | 4355 | if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) |
da1ce067 MS |
4356 | return -EINVAL; |
4357 | ||
0d7a8555 MS |
4358 | if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && |
4359 | (flags & RENAME_EXCHANGE)) | |
520c8b16 MS |
4360 | return -EINVAL; |
4361 | ||
0d7a8555 MS |
4362 | if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) |
4363 | return -EPERM; | |
4364 | ||
f5beed75 AV |
4365 | if (flags & RENAME_EXCHANGE) |
4366 | target_flags = 0; | |
4367 | ||
c6a94284 | 4368 | retry: |
f5beed75 AV |
4369 | from = user_path_parent(olddfd, oldname, |
4370 | &old_path, &old_last, &old_type, lookup_flags); | |
91a27b2a JL |
4371 | if (IS_ERR(from)) { |
4372 | error = PTR_ERR(from); | |
1da177e4 | 4373 | goto exit; |
91a27b2a | 4374 | } |
1da177e4 | 4375 | |
f5beed75 AV |
4376 | to = user_path_parent(newdfd, newname, |
4377 | &new_path, &new_last, &new_type, lookup_flags); | |
91a27b2a JL |
4378 | if (IS_ERR(to)) { |
4379 | error = PTR_ERR(to); | |
1da177e4 | 4380 | goto exit1; |
91a27b2a | 4381 | } |
1da177e4 LT |
4382 | |
4383 | error = -EXDEV; | |
f5beed75 | 4384 | if (old_path.mnt != new_path.mnt) |
1da177e4 LT |
4385 | goto exit2; |
4386 | ||
1da177e4 | 4387 | error = -EBUSY; |
f5beed75 | 4388 | if (old_type != LAST_NORM) |
1da177e4 LT |
4389 | goto exit2; |
4390 | ||
0a7c3937 MS |
4391 | if (flags & RENAME_NOREPLACE) |
4392 | error = -EEXIST; | |
f5beed75 | 4393 | if (new_type != LAST_NORM) |
1da177e4 LT |
4394 | goto exit2; |
4395 | ||
f5beed75 | 4396 | error = mnt_want_write(old_path.mnt); |
c30dabfe JK |
4397 | if (error) |
4398 | goto exit2; | |
4399 | ||
8e6d782c | 4400 | retry_deleg: |
f5beed75 | 4401 | trap = lock_rename(new_path.dentry, old_path.dentry); |
1da177e4 | 4402 | |
f5beed75 | 4403 | old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); |
1da177e4 LT |
4404 | error = PTR_ERR(old_dentry); |
4405 | if (IS_ERR(old_dentry)) | |
4406 | goto exit3; | |
4407 | /* source must exist */ | |
4408 | error = -ENOENT; | |
b18825a7 | 4409 | if (d_is_negative(old_dentry)) |
1da177e4 | 4410 | goto exit4; |
f5beed75 | 4411 | new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); |
0a7c3937 MS |
4412 | error = PTR_ERR(new_dentry); |
4413 | if (IS_ERR(new_dentry)) | |
4414 | goto exit4; | |
4415 | error = -EEXIST; | |
4416 | if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) | |
4417 | goto exit5; | |
da1ce067 MS |
4418 | if (flags & RENAME_EXCHANGE) { |
4419 | error = -ENOENT; | |
4420 | if (d_is_negative(new_dentry)) | |
4421 | goto exit5; | |
4422 | ||
4423 | if (!d_is_dir(new_dentry)) { | |
4424 | error = -ENOTDIR; | |
f5beed75 | 4425 | if (new_last.name[new_last.len]) |
da1ce067 MS |
4426 | goto exit5; |
4427 | } | |
4428 | } | |
1da177e4 | 4429 | /* unless the source is a directory trailing slashes give -ENOTDIR */ |
44b1d530 | 4430 | if (!d_is_dir(old_dentry)) { |
1da177e4 | 4431 | error = -ENOTDIR; |
f5beed75 | 4432 | if (old_last.name[old_last.len]) |
0a7c3937 | 4433 | goto exit5; |
f5beed75 | 4434 | if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) |
0a7c3937 | 4435 | goto exit5; |
1da177e4 LT |
4436 | } |
4437 | /* source should not be ancestor of target */ | |
4438 | error = -EINVAL; | |
4439 | if (old_dentry == trap) | |
0a7c3937 | 4440 | goto exit5; |
1da177e4 | 4441 | /* target should not be an ancestor of source */ |
da1ce067 MS |
4442 | if (!(flags & RENAME_EXCHANGE)) |
4443 | error = -ENOTEMPTY; | |
1da177e4 LT |
4444 | if (new_dentry == trap) |
4445 | goto exit5; | |
4446 | ||
f5beed75 AV |
4447 | error = security_path_rename(&old_path, old_dentry, |
4448 | &new_path, new_dentry, flags); | |
be6d3e56 | 4449 | if (error) |
c30dabfe | 4450 | goto exit5; |
f5beed75 AV |
4451 | error = vfs_rename(old_path.dentry->d_inode, old_dentry, |
4452 | new_path.dentry->d_inode, new_dentry, | |
520c8b16 | 4453 | &delegated_inode, flags); |
1da177e4 LT |
4454 | exit5: |
4455 | dput(new_dentry); | |
4456 | exit4: | |
4457 | dput(old_dentry); | |
4458 | exit3: | |
f5beed75 | 4459 | unlock_rename(new_path.dentry, old_path.dentry); |
8e6d782c BF |
4460 | if (delegated_inode) { |
4461 | error = break_deleg_wait(&delegated_inode); | |
4462 | if (!error) | |
4463 | goto retry_deleg; | |
4464 | } | |
f5beed75 | 4465 | mnt_drop_write(old_path.mnt); |
1da177e4 | 4466 | exit2: |
c6a94284 JL |
4467 | if (retry_estale(error, lookup_flags)) |
4468 | should_retry = true; | |
f5beed75 | 4469 | path_put(&new_path); |
2ad94ae6 | 4470 | putname(to); |
1da177e4 | 4471 | exit1: |
f5beed75 | 4472 | path_put(&old_path); |
1da177e4 | 4473 | putname(from); |
c6a94284 JL |
4474 | if (should_retry) { |
4475 | should_retry = false; | |
4476 | lookup_flags |= LOOKUP_REVAL; | |
4477 | goto retry; | |
4478 | } | |
2ad94ae6 | 4479 | exit: |
1da177e4 LT |
4480 | return error; |
4481 | } | |
4482 | ||
520c8b16 MS |
4483 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
4484 | int, newdfd, const char __user *, newname) | |
4485 | { | |
4486 | return sys_renameat2(olddfd, oldname, newdfd, newname, 0); | |
4487 | } | |
4488 | ||
a26eab24 | 4489 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 4490 | { |
520c8b16 | 4491 | return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
4492 | } |
4493 | ||
787fb6bc MS |
4494 | int vfs_whiteout(struct inode *dir, struct dentry *dentry) |
4495 | { | |
4496 | int error = may_create(dir, dentry); | |
4497 | if (error) | |
4498 | return error; | |
4499 | ||
4500 | if (!dir->i_op->mknod) | |
4501 | return -EPERM; | |
4502 | ||
4503 | return dir->i_op->mknod(dir, dentry, | |
4504 | S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); | |
4505 | } | |
4506 | EXPORT_SYMBOL(vfs_whiteout); | |
4507 | ||
5d826c84 | 4508 | int readlink_copy(char __user *buffer, int buflen, const char *link) |
1da177e4 | 4509 | { |
5d826c84 | 4510 | int len = PTR_ERR(link); |
1da177e4 LT |
4511 | if (IS_ERR(link)) |
4512 | goto out; | |
4513 | ||
4514 | len = strlen(link); | |
4515 | if (len > (unsigned) buflen) | |
4516 | len = buflen; | |
4517 | if (copy_to_user(buffer, link, len)) | |
4518 | len = -EFAULT; | |
4519 | out: | |
4520 | return len; | |
4521 | } | |
5d826c84 | 4522 | EXPORT_SYMBOL(readlink_copy); |
1da177e4 LT |
4523 | |
4524 | /* | |
4525 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
4526 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
4527 | * using) it for any given inode is up to filesystem. | |
4528 | */ | |
4529 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4530 | { | |
cc314eef | 4531 | void *cookie; |
5f2c4179 AV |
4532 | struct inode *inode = d_inode(dentry); |
4533 | const char *link = inode->i_link; | |
694a1764 | 4534 | int res; |
cc314eef | 4535 | |
d4dee48b | 4536 | if (!link) { |
5f2c4179 | 4537 | link = inode->i_op->follow_link(dentry, &cookie); |
d4dee48b AV |
4538 | if (IS_ERR(link)) |
4539 | return PTR_ERR(link); | |
4540 | } | |
680baacb | 4541 | res = readlink_copy(buffer, buflen, link); |
5f2c4179 AV |
4542 | if (inode->i_op->put_link) |
4543 | inode->i_op->put_link(inode, cookie); | |
694a1764 | 4544 | return res; |
1da177e4 | 4545 | } |
4d359507 | 4546 | EXPORT_SYMBOL(generic_readlink); |
1da177e4 | 4547 | |
1da177e4 LT |
4548 | /* get the link contents into pagecache */ |
4549 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
4550 | { | |
ebd09abb DG |
4551 | char *kaddr; |
4552 | struct page *page; | |
1da177e4 | 4553 | struct address_space *mapping = dentry->d_inode->i_mapping; |
090d2b18 | 4554 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 4555 | if (IS_ERR(page)) |
6fe6900e | 4556 | return (char*)page; |
1da177e4 | 4557 | *ppage = page; |
ebd09abb DG |
4558 | kaddr = kmap(page); |
4559 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); | |
4560 | return kaddr; | |
1da177e4 LT |
4561 | } |
4562 | ||
4563 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4564 | { | |
4565 | struct page *page = NULL; | |
5d826c84 | 4566 | int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); |
1da177e4 LT |
4567 | if (page) { |
4568 | kunmap(page); | |
4569 | page_cache_release(page); | |
4570 | } | |
4571 | return res; | |
4572 | } | |
4d359507 | 4573 | EXPORT_SYMBOL(page_readlink); |
1da177e4 | 4574 | |
6e77137b | 4575 | const char *page_follow_link_light(struct dentry *dentry, void **cookie) |
1da177e4 | 4576 | { |
cc314eef | 4577 | struct page *page = NULL; |
680baacb AV |
4578 | char *res = page_getlink(dentry, &page); |
4579 | if (!IS_ERR(res)) | |
4580 | *cookie = page; | |
4581 | return res; | |
1da177e4 | 4582 | } |
4d359507 | 4583 | EXPORT_SYMBOL(page_follow_link_light); |
1da177e4 | 4584 | |
5f2c4179 | 4585 | void page_put_link(struct inode *unused, void *cookie) |
1da177e4 | 4586 | { |
cc314eef | 4587 | struct page *page = cookie; |
680baacb AV |
4588 | kunmap(page); |
4589 | page_cache_release(page); | |
1da177e4 | 4590 | } |
4d359507 | 4591 | EXPORT_SYMBOL(page_put_link); |
1da177e4 | 4592 | |
54566b2c NP |
4593 | /* |
4594 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
4595 | */ | |
4596 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
4597 | { |
4598 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 4599 | struct page *page; |
afddba49 | 4600 | void *fsdata; |
beb497ab | 4601 | int err; |
1da177e4 | 4602 | char *kaddr; |
54566b2c NP |
4603 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
4604 | if (nofs) | |
4605 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 4606 | |
7e53cac4 | 4607 | retry: |
afddba49 | 4608 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 4609 | flags, &page, &fsdata); |
1da177e4 | 4610 | if (err) |
afddba49 NP |
4611 | goto fail; |
4612 | ||
e8e3c3d6 | 4613 | kaddr = kmap_atomic(page); |
1da177e4 | 4614 | memcpy(kaddr, symname, len-1); |
e8e3c3d6 | 4615 | kunmap_atomic(kaddr); |
afddba49 NP |
4616 | |
4617 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
4618 | page, fsdata); | |
1da177e4 LT |
4619 | if (err < 0) |
4620 | goto fail; | |
afddba49 NP |
4621 | if (err < len-1) |
4622 | goto retry; | |
4623 | ||
1da177e4 LT |
4624 | mark_inode_dirty(inode); |
4625 | return 0; | |
1da177e4 LT |
4626 | fail: |
4627 | return err; | |
4628 | } | |
4d359507 | 4629 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 | 4630 | |
0adb25d2 KK |
4631 | int page_symlink(struct inode *inode, const char *symname, int len) |
4632 | { | |
4633 | return __page_symlink(inode, symname, len, | |
54566b2c | 4634 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
0adb25d2 | 4635 | } |
4d359507 | 4636 | EXPORT_SYMBOL(page_symlink); |
0adb25d2 | 4637 | |
92e1d5be | 4638 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
4639 | .readlink = generic_readlink, |
4640 | .follow_link = page_follow_link_light, | |
4641 | .put_link = page_put_link, | |
4642 | }; | |
1da177e4 | 4643 | EXPORT_SYMBOL(page_symlink_inode_operations); |