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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 | |
1f55a6ec AV |
495 | struct nameidata { |
496 | struct path path; | |
caa85634 AV |
497 | union { |
498 | struct qstr last; | |
499 | struct path link; | |
500 | }; | |
1f55a6ec AV |
501 | struct path root; |
502 | struct inode *inode; /* path.dentry.d_inode */ | |
503 | unsigned int flags; | |
504 | unsigned seq, m_seq; | |
505 | int last_type; | |
506 | unsigned depth; | |
5e53084d | 507 | struct file *base; |
1f55a6ec AV |
508 | }; |
509 | ||
19660af7 | 510 | /* |
31e6b01f | 511 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
19660af7 AV |
512 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
513 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab | |
514 | * normal reference counts on dentries and vfsmounts to transition to rcu-walk | |
515 | * mode. Refcounts are grabbed at the last known good point before rcu-walk | |
516 | * got stuck, so ref-walk may continue from there. If this is not successful | |
517 | * (eg. a seqcount has changed), then failure is returned and it's up to caller | |
518 | * to restart the path walk from the beginning in ref-walk mode. | |
31e6b01f | 519 | */ |
31e6b01f NP |
520 | |
521 | /** | |
19660af7 AV |
522 | * unlazy_walk - try to switch to ref-walk mode. |
523 | * @nd: nameidata pathwalk data | |
524 | * @dentry: child of nd->path.dentry or NULL | |
39191628 | 525 | * Returns: 0 on success, -ECHILD on failure |
31e6b01f | 526 | * |
19660af7 AV |
527 | * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry |
528 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on | |
529 | * @nd or NULL. Must be called from rcu-walk context. | |
31e6b01f | 530 | */ |
19660af7 | 531 | static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) |
31e6b01f NP |
532 | { |
533 | struct fs_struct *fs = current->fs; | |
534 | struct dentry *parent = nd->path.dentry; | |
535 | ||
536 | BUG_ON(!(nd->flags & LOOKUP_RCU)); | |
e5c832d5 LT |
537 | |
538 | /* | |
48a066e7 AV |
539 | * After legitimizing the bastards, terminate_walk() |
540 | * will do the right thing for non-RCU mode, and all our | |
541 | * subsequent exit cases should rcu_read_unlock() | |
542 | * before returning. Do vfsmount first; if dentry | |
543 | * can't be legitimized, just set nd->path.dentry to NULL | |
544 | * and rely on dput(NULL) being a no-op. | |
e5c832d5 | 545 | */ |
48a066e7 | 546 | if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) |
e5c832d5 | 547 | return -ECHILD; |
e5c832d5 | 548 | nd->flags &= ~LOOKUP_RCU; |
15570086 | 549 | |
48a066e7 AV |
550 | if (!lockref_get_not_dead(&parent->d_lockref)) { |
551 | nd->path.dentry = NULL; | |
d870b4a1 | 552 | goto out; |
48a066e7 AV |
553 | } |
554 | ||
15570086 LT |
555 | /* |
556 | * For a negative lookup, the lookup sequence point is the parents | |
557 | * sequence point, and it only needs to revalidate the parent dentry. | |
558 | * | |
559 | * For a positive lookup, we need to move both the parent and the | |
560 | * dentry from the RCU domain to be properly refcounted. And the | |
561 | * sequence number in the dentry validates *both* dentry counters, | |
562 | * since we checked the sequence number of the parent after we got | |
563 | * the child sequence number. So we know the parent must still | |
564 | * be valid if the child sequence number is still valid. | |
565 | */ | |
19660af7 | 566 | if (!dentry) { |
e5c832d5 LT |
567 | if (read_seqcount_retry(&parent->d_seq, nd->seq)) |
568 | goto out; | |
19660af7 AV |
569 | BUG_ON(nd->inode != parent->d_inode); |
570 | } else { | |
e5c832d5 LT |
571 | if (!lockref_get_not_dead(&dentry->d_lockref)) |
572 | goto out; | |
573 | if (read_seqcount_retry(&dentry->d_seq, nd->seq)) | |
574 | goto drop_dentry; | |
19660af7 | 575 | } |
e5c832d5 LT |
576 | |
577 | /* | |
578 | * Sequence counts matched. Now make sure that the root is | |
579 | * still valid and get it if required. | |
580 | */ | |
581 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { | |
582 | spin_lock(&fs->lock); | |
583 | if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) | |
584 | goto unlock_and_drop_dentry; | |
31e6b01f NP |
585 | path_get(&nd->root); |
586 | spin_unlock(&fs->lock); | |
587 | } | |
31e6b01f | 588 | |
8b61e74f | 589 | rcu_read_unlock(); |
31e6b01f | 590 | return 0; |
19660af7 | 591 | |
e5c832d5 LT |
592 | unlock_and_drop_dentry: |
593 | spin_unlock(&fs->lock); | |
594 | drop_dentry: | |
8b61e74f | 595 | rcu_read_unlock(); |
15570086 | 596 | dput(dentry); |
d0d27277 | 597 | goto drop_root_mnt; |
e5c832d5 | 598 | out: |
8b61e74f | 599 | rcu_read_unlock(); |
d0d27277 LT |
600 | drop_root_mnt: |
601 | if (!(nd->flags & LOOKUP_ROOT)) | |
602 | nd->root.mnt = NULL; | |
31e6b01f NP |
603 | return -ECHILD; |
604 | } | |
605 | ||
4ce16ef3 | 606 | static inline int d_revalidate(struct dentry *dentry, unsigned int flags) |
34286d66 | 607 | { |
4ce16ef3 | 608 | return dentry->d_op->d_revalidate(dentry, flags); |
34286d66 NP |
609 | } |
610 | ||
9f1fafee AV |
611 | /** |
612 | * complete_walk - successful completion of path walk | |
613 | * @nd: pointer nameidata | |
39159de2 | 614 | * |
9f1fafee AV |
615 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
616 | * Revalidate the final result, unless we'd already done that during | |
617 | * the path walk or the filesystem doesn't ask for it. Return 0 on | |
618 | * success, -error on failure. In case of failure caller does not | |
619 | * need to drop nd->path. | |
39159de2 | 620 | */ |
9f1fafee | 621 | static int complete_walk(struct nameidata *nd) |
39159de2 | 622 | { |
16c2cd71 | 623 | struct dentry *dentry = nd->path.dentry; |
39159de2 | 624 | int status; |
39159de2 | 625 | |
9f1fafee AV |
626 | if (nd->flags & LOOKUP_RCU) { |
627 | nd->flags &= ~LOOKUP_RCU; | |
628 | if (!(nd->flags & LOOKUP_ROOT)) | |
629 | nd->root.mnt = NULL; | |
15570086 | 630 | |
48a066e7 | 631 | if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { |
8b61e74f | 632 | rcu_read_unlock(); |
48a066e7 AV |
633 | return -ECHILD; |
634 | } | |
e5c832d5 | 635 | if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { |
8b61e74f | 636 | rcu_read_unlock(); |
48a066e7 | 637 | mntput(nd->path.mnt); |
e5c832d5 LT |
638 | return -ECHILD; |
639 | } | |
640 | if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { | |
8b61e74f | 641 | rcu_read_unlock(); |
e5c832d5 | 642 | dput(dentry); |
48a066e7 | 643 | mntput(nd->path.mnt); |
9f1fafee AV |
644 | return -ECHILD; |
645 | } | |
8b61e74f | 646 | rcu_read_unlock(); |
9f1fafee AV |
647 | } |
648 | ||
16c2cd71 AV |
649 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
650 | return 0; | |
651 | ||
ecf3d1f1 | 652 | if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) |
39159de2 JL |
653 | return 0; |
654 | ||
ecf3d1f1 | 655 | status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); |
39159de2 JL |
656 | if (status > 0) |
657 | return 0; | |
658 | ||
16c2cd71 | 659 | if (!status) |
39159de2 | 660 | status = -ESTALE; |
16c2cd71 | 661 | |
9f1fafee | 662 | path_put(&nd->path); |
39159de2 JL |
663 | return status; |
664 | } | |
665 | ||
2a737871 AV |
666 | static __always_inline void set_root(struct nameidata *nd) |
667 | { | |
7bd88377 | 668 | get_fs_root(current->fs, &nd->root); |
2a737871 AV |
669 | } |
670 | ||
7bd88377 | 671 | static __always_inline unsigned set_root_rcu(struct nameidata *nd) |
31e6b01f | 672 | { |
7bd88377 AV |
673 | struct fs_struct *fs = current->fs; |
674 | unsigned seq, res; | |
c28cc364 | 675 | |
7bd88377 AV |
676 | do { |
677 | seq = read_seqcount_begin(&fs->seq); | |
678 | nd->root = fs->root; | |
679 | res = __read_seqcount_begin(&nd->root.dentry->d_seq); | |
680 | } while (read_seqcount_retry(&fs->seq, seq)); | |
681 | return res; | |
31e6b01f NP |
682 | } |
683 | ||
1d957f9b | 684 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
051d3812 IK |
685 | { |
686 | dput(path->dentry); | |
4ac91378 | 687 | if (path->mnt != nd->path.mnt) |
051d3812 IK |
688 | mntput(path->mnt); |
689 | } | |
690 | ||
7b9337aa NP |
691 | static inline void path_to_nameidata(const struct path *path, |
692 | struct nameidata *nd) | |
051d3812 | 693 | { |
31e6b01f NP |
694 | if (!(nd->flags & LOOKUP_RCU)) { |
695 | dput(nd->path.dentry); | |
696 | if (nd->path.mnt != path->mnt) | |
697 | mntput(nd->path.mnt); | |
9a229683 | 698 | } |
31e6b01f | 699 | nd->path.mnt = path->mnt; |
4ac91378 | 700 | nd->path.dentry = path->dentry; |
051d3812 IK |
701 | } |
702 | ||
b5fb63c1 CH |
703 | /* |
704 | * Helper to directly jump to a known parsed path from ->follow_link, | |
705 | * caller must have taken a reference to path beforehand. | |
706 | */ | |
707 | void nd_jump_link(struct nameidata *nd, struct path *path) | |
708 | { | |
709 | path_put(&nd->path); | |
710 | ||
711 | nd->path = *path; | |
712 | nd->inode = nd->path.dentry->d_inode; | |
713 | nd->flags |= LOOKUP_JUMPED; | |
b5fb63c1 CH |
714 | } |
715 | ||
574197e0 AV |
716 | static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) |
717 | { | |
718 | struct inode *inode = link->dentry->d_inode; | |
680baacb AV |
719 | if (cookie && inode->i_op->put_link) |
720 | inode->i_op->put_link(link->dentry, cookie); | |
574197e0 AV |
721 | path_put(link); |
722 | } | |
723 | ||
561ec64a LT |
724 | int sysctl_protected_symlinks __read_mostly = 0; |
725 | int sysctl_protected_hardlinks __read_mostly = 0; | |
800179c9 KC |
726 | |
727 | /** | |
728 | * may_follow_link - Check symlink following for unsafe situations | |
729 | * @link: The path of the symlink | |
55852635 | 730 | * @nd: nameidata pathwalk data |
800179c9 KC |
731 | * |
732 | * In the case of the sysctl_protected_symlinks sysctl being enabled, | |
733 | * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is | |
734 | * in a sticky world-writable directory. This is to protect privileged | |
735 | * processes from failing races against path names that may change out | |
736 | * from under them by way of other users creating malicious symlinks. | |
737 | * It will permit symlinks to be followed only when outside a sticky | |
738 | * world-writable directory, or when the uid of the symlink and follower | |
739 | * match, or when the directory owner matches the symlink's owner. | |
740 | * | |
741 | * Returns 0 if following the symlink is allowed, -ve on error. | |
742 | */ | |
743 | static inline int may_follow_link(struct path *link, struct nameidata *nd) | |
744 | { | |
745 | const struct inode *inode; | |
746 | const struct inode *parent; | |
747 | ||
748 | if (!sysctl_protected_symlinks) | |
749 | return 0; | |
750 | ||
751 | /* Allowed if owner and follower match. */ | |
752 | inode = link->dentry->d_inode; | |
81abe27b | 753 | if (uid_eq(current_cred()->fsuid, inode->i_uid)) |
800179c9 KC |
754 | return 0; |
755 | ||
756 | /* Allowed if parent directory not sticky and world-writable. */ | |
757 | parent = nd->path.dentry->d_inode; | |
758 | if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) | |
759 | return 0; | |
760 | ||
761 | /* Allowed if parent directory and link owner match. */ | |
81abe27b | 762 | if (uid_eq(parent->i_uid, inode->i_uid)) |
800179c9 KC |
763 | return 0; |
764 | ||
ffd8d101 | 765 | audit_log_link_denied("follow_link", link); |
800179c9 KC |
766 | path_put_conditional(link, nd); |
767 | path_put(&nd->path); | |
768 | return -EACCES; | |
769 | } | |
770 | ||
771 | /** | |
772 | * safe_hardlink_source - Check for safe hardlink conditions | |
773 | * @inode: the source inode to hardlink from | |
774 | * | |
775 | * Return false if at least one of the following conditions: | |
776 | * - inode is not a regular file | |
777 | * - inode is setuid | |
778 | * - inode is setgid and group-exec | |
779 | * - access failure for read and write | |
780 | * | |
781 | * Otherwise returns true. | |
782 | */ | |
783 | static bool safe_hardlink_source(struct inode *inode) | |
784 | { | |
785 | umode_t mode = inode->i_mode; | |
786 | ||
787 | /* Special files should not get pinned to the filesystem. */ | |
788 | if (!S_ISREG(mode)) | |
789 | return false; | |
790 | ||
791 | /* Setuid files should not get pinned to the filesystem. */ | |
792 | if (mode & S_ISUID) | |
793 | return false; | |
794 | ||
795 | /* Executable setgid files should not get pinned to the filesystem. */ | |
796 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) | |
797 | return false; | |
798 | ||
799 | /* Hardlinking to unreadable or unwritable sources is dangerous. */ | |
800 | if (inode_permission(inode, MAY_READ | MAY_WRITE)) | |
801 | return false; | |
802 | ||
803 | return true; | |
804 | } | |
805 | ||
806 | /** | |
807 | * may_linkat - Check permissions for creating a hardlink | |
808 | * @link: the source to hardlink from | |
809 | * | |
810 | * Block hardlink when all of: | |
811 | * - sysctl_protected_hardlinks enabled | |
812 | * - fsuid does not match inode | |
813 | * - hardlink source is unsafe (see safe_hardlink_source() above) | |
814 | * - not CAP_FOWNER | |
815 | * | |
816 | * Returns 0 if successful, -ve on error. | |
817 | */ | |
818 | static int may_linkat(struct path *link) | |
819 | { | |
820 | const struct cred *cred; | |
821 | struct inode *inode; | |
822 | ||
823 | if (!sysctl_protected_hardlinks) | |
824 | return 0; | |
825 | ||
826 | cred = current_cred(); | |
827 | inode = link->dentry->d_inode; | |
828 | ||
829 | /* Source inode owner (or CAP_FOWNER) can hardlink all they like, | |
830 | * otherwise, it must be a safe source. | |
831 | */ | |
81abe27b | 832 | if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || |
800179c9 KC |
833 | capable(CAP_FOWNER)) |
834 | return 0; | |
835 | ||
a51d9eaa | 836 | audit_log_link_denied("linkat", link); |
800179c9 KC |
837 | return -EPERM; |
838 | } | |
839 | ||
0a959df5 AV |
840 | static __always_inline const char * |
841 | get_link(struct path *link, struct nameidata *nd, void **p) | |
1da177e4 | 842 | { |
7b9337aa | 843 | struct dentry *dentry = link->dentry; |
0a959df5 | 844 | struct inode *inode = dentry->d_inode; |
6d7b5aae | 845 | int error; |
0a959df5 | 846 | const char *res; |
1da177e4 | 847 | |
844a3917 AV |
848 | BUG_ON(nd->flags & LOOKUP_RCU); |
849 | ||
0e794589 AV |
850 | if (link->mnt == nd->path.mnt) |
851 | mntget(link->mnt); | |
852 | ||
0a959df5 | 853 | res = ERR_PTR(-ELOOP); |
6d7b5aae | 854 | if (unlikely(current->total_link_count >= 40)) |
0a959df5 | 855 | goto out; |
6d7b5aae | 856 | |
574197e0 AV |
857 | cond_resched(); |
858 | current->total_link_count++; | |
859 | ||
68ac1234 | 860 | touch_atime(link); |
cd4e91d3 | 861 | |
37882db0 | 862 | error = security_inode_follow_link(dentry); |
0a959df5 | 863 | res = ERR_PTR(error); |
6d7b5aae | 864 | if (error) |
0a959df5 | 865 | goto out; |
36f3b4f6 | 866 | |
86acdca1 | 867 | nd->last_type = LAST_BIND; |
680baacb | 868 | *p = NULL; |
d4dee48b AV |
869 | res = inode->i_link; |
870 | if (!res) { | |
871 | res = inode->i_op->follow_link(dentry, p, nd); | |
872 | if (IS_ERR(res)) { | |
0a959df5 | 873 | out: |
d4dee48b AV |
874 | path_put(&nd->path); |
875 | path_put(link); | |
876 | } | |
1da177e4 | 877 | } |
0a959df5 AV |
878 | return res; |
879 | } | |
6d7b5aae | 880 | |
31e6b01f NP |
881 | static int follow_up_rcu(struct path *path) |
882 | { | |
0714a533 AV |
883 | struct mount *mnt = real_mount(path->mnt); |
884 | struct mount *parent; | |
31e6b01f NP |
885 | struct dentry *mountpoint; |
886 | ||
0714a533 AV |
887 | parent = mnt->mnt_parent; |
888 | if (&parent->mnt == path->mnt) | |
31e6b01f | 889 | return 0; |
a73324da | 890 | mountpoint = mnt->mnt_mountpoint; |
31e6b01f | 891 | path->dentry = mountpoint; |
0714a533 | 892 | path->mnt = &parent->mnt; |
31e6b01f NP |
893 | return 1; |
894 | } | |
895 | ||
f015f126 DH |
896 | /* |
897 | * follow_up - Find the mountpoint of path's vfsmount | |
898 | * | |
899 | * Given a path, find the mountpoint of its source file system. | |
900 | * Replace @path with the path of the mountpoint in the parent mount. | |
901 | * Up is towards /. | |
902 | * | |
903 | * Return 1 if we went up a level and 0 if we were already at the | |
904 | * root. | |
905 | */ | |
bab77ebf | 906 | int follow_up(struct path *path) |
1da177e4 | 907 | { |
0714a533 AV |
908 | struct mount *mnt = real_mount(path->mnt); |
909 | struct mount *parent; | |
1da177e4 | 910 | struct dentry *mountpoint; |
99b7db7b | 911 | |
48a066e7 | 912 | read_seqlock_excl(&mount_lock); |
0714a533 | 913 | parent = mnt->mnt_parent; |
3c0a6163 | 914 | if (parent == mnt) { |
48a066e7 | 915 | read_sequnlock_excl(&mount_lock); |
1da177e4 LT |
916 | return 0; |
917 | } | |
0714a533 | 918 | mntget(&parent->mnt); |
a73324da | 919 | mountpoint = dget(mnt->mnt_mountpoint); |
48a066e7 | 920 | read_sequnlock_excl(&mount_lock); |
bab77ebf AV |
921 | dput(path->dentry); |
922 | path->dentry = mountpoint; | |
923 | mntput(path->mnt); | |
0714a533 | 924 | path->mnt = &parent->mnt; |
1da177e4 LT |
925 | return 1; |
926 | } | |
4d359507 | 927 | EXPORT_SYMBOL(follow_up); |
1da177e4 | 928 | |
b5c84bf6 | 929 | /* |
9875cf80 DH |
930 | * Perform an automount |
931 | * - return -EISDIR to tell follow_managed() to stop and return the path we | |
932 | * were called with. | |
1da177e4 | 933 | */ |
9875cf80 DH |
934 | static int follow_automount(struct path *path, unsigned flags, |
935 | bool *need_mntput) | |
31e6b01f | 936 | { |
9875cf80 | 937 | struct vfsmount *mnt; |
ea5b778a | 938 | int err; |
9875cf80 DH |
939 | |
940 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) | |
941 | return -EREMOTE; | |
942 | ||
0ec26fd0 MS |
943 | /* We don't want to mount if someone's just doing a stat - |
944 | * unless they're stat'ing a directory and appended a '/' to | |
945 | * the name. | |
946 | * | |
947 | * We do, however, want to mount if someone wants to open or | |
948 | * create a file of any type under the mountpoint, wants to | |
949 | * traverse through the mountpoint or wants to open the | |
950 | * mounted directory. Also, autofs may mark negative dentries | |
951 | * as being automount points. These will need the attentions | |
952 | * of the daemon to instantiate them before they can be used. | |
9875cf80 | 953 | */ |
0ec26fd0 | 954 | if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
d94c177b | 955 | LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && |
0ec26fd0 MS |
956 | path->dentry->d_inode) |
957 | return -EISDIR; | |
958 | ||
9875cf80 DH |
959 | current->total_link_count++; |
960 | if (current->total_link_count >= 40) | |
961 | return -ELOOP; | |
962 | ||
963 | mnt = path->dentry->d_op->d_automount(path); | |
964 | if (IS_ERR(mnt)) { | |
965 | /* | |
966 | * The filesystem is allowed to return -EISDIR here to indicate | |
967 | * it doesn't want to automount. For instance, autofs would do | |
968 | * this so that its userspace daemon can mount on this dentry. | |
969 | * | |
970 | * However, we can only permit this if it's a terminal point in | |
971 | * the path being looked up; if it wasn't then the remainder of | |
972 | * the path is inaccessible and we should say so. | |
973 | */ | |
49084c3b | 974 | if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) |
9875cf80 DH |
975 | return -EREMOTE; |
976 | return PTR_ERR(mnt); | |
31e6b01f | 977 | } |
ea5b778a | 978 | |
9875cf80 DH |
979 | if (!mnt) /* mount collision */ |
980 | return 0; | |
31e6b01f | 981 | |
8aef1884 AV |
982 | if (!*need_mntput) { |
983 | /* lock_mount() may release path->mnt on error */ | |
984 | mntget(path->mnt); | |
985 | *need_mntput = true; | |
986 | } | |
19a167af | 987 | err = finish_automount(mnt, path); |
9875cf80 | 988 | |
ea5b778a DH |
989 | switch (err) { |
990 | case -EBUSY: | |
991 | /* Someone else made a mount here whilst we were busy */ | |
19a167af | 992 | return 0; |
ea5b778a | 993 | case 0: |
8aef1884 | 994 | path_put(path); |
ea5b778a DH |
995 | path->mnt = mnt; |
996 | path->dentry = dget(mnt->mnt_root); | |
ea5b778a | 997 | return 0; |
19a167af AV |
998 | default: |
999 | return err; | |
ea5b778a | 1000 | } |
19a167af | 1001 | |
463ffb2e AV |
1002 | } |
1003 | ||
9875cf80 DH |
1004 | /* |
1005 | * Handle a dentry that is managed in some way. | |
cc53ce53 | 1006 | * - Flagged for transit management (autofs) |
9875cf80 DH |
1007 | * - Flagged as mountpoint |
1008 | * - Flagged as automount point | |
1009 | * | |
1010 | * This may only be called in refwalk mode. | |
1011 | * | |
1012 | * Serialization is taken care of in namespace.c | |
1013 | */ | |
1014 | static int follow_managed(struct path *path, unsigned flags) | |
1da177e4 | 1015 | { |
8aef1884 | 1016 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
9875cf80 DH |
1017 | unsigned managed; |
1018 | bool need_mntput = false; | |
8aef1884 | 1019 | int ret = 0; |
9875cf80 DH |
1020 | |
1021 | /* Given that we're not holding a lock here, we retain the value in a | |
1022 | * local variable for each dentry as we look at it so that we don't see | |
1023 | * the components of that value change under us */ | |
1024 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1025 | managed &= DCACHE_MANAGED_DENTRY, | |
1026 | unlikely(managed != 0)) { | |
cc53ce53 DH |
1027 | /* Allow the filesystem to manage the transit without i_mutex |
1028 | * being held. */ | |
1029 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1030 | BUG_ON(!path->dentry->d_op); | |
1031 | BUG_ON(!path->dentry->d_op->d_manage); | |
1aed3e42 | 1032 | ret = path->dentry->d_op->d_manage(path->dentry, false); |
cc53ce53 | 1033 | if (ret < 0) |
8aef1884 | 1034 | break; |
cc53ce53 DH |
1035 | } |
1036 | ||
9875cf80 DH |
1037 | /* Transit to a mounted filesystem. */ |
1038 | if (managed & DCACHE_MOUNTED) { | |
1039 | struct vfsmount *mounted = lookup_mnt(path); | |
1040 | if (mounted) { | |
1041 | dput(path->dentry); | |
1042 | if (need_mntput) | |
1043 | mntput(path->mnt); | |
1044 | path->mnt = mounted; | |
1045 | path->dentry = dget(mounted->mnt_root); | |
1046 | need_mntput = true; | |
1047 | continue; | |
1048 | } | |
1049 | ||
1050 | /* Something is mounted on this dentry in another | |
1051 | * namespace and/or whatever was mounted there in this | |
48a066e7 AV |
1052 | * namespace got unmounted before lookup_mnt() could |
1053 | * get it */ | |
9875cf80 DH |
1054 | } |
1055 | ||
1056 | /* Handle an automount point */ | |
1057 | if (managed & DCACHE_NEED_AUTOMOUNT) { | |
1058 | ret = follow_automount(path, flags, &need_mntput); | |
1059 | if (ret < 0) | |
8aef1884 | 1060 | break; |
9875cf80 DH |
1061 | continue; |
1062 | } | |
1063 | ||
1064 | /* We didn't change the current path point */ | |
1065 | break; | |
1da177e4 | 1066 | } |
8aef1884 AV |
1067 | |
1068 | if (need_mntput && path->mnt == mnt) | |
1069 | mntput(path->mnt); | |
1070 | if (ret == -EISDIR) | |
1071 | ret = 0; | |
a3fbbde7 | 1072 | return ret < 0 ? ret : need_mntput; |
1da177e4 LT |
1073 | } |
1074 | ||
cc53ce53 | 1075 | int follow_down_one(struct path *path) |
1da177e4 LT |
1076 | { |
1077 | struct vfsmount *mounted; | |
1078 | ||
1c755af4 | 1079 | mounted = lookup_mnt(path); |
1da177e4 | 1080 | if (mounted) { |
9393bd07 AV |
1081 | dput(path->dentry); |
1082 | mntput(path->mnt); | |
1083 | path->mnt = mounted; | |
1084 | path->dentry = dget(mounted->mnt_root); | |
1da177e4 LT |
1085 | return 1; |
1086 | } | |
1087 | return 0; | |
1088 | } | |
4d359507 | 1089 | EXPORT_SYMBOL(follow_down_one); |
1da177e4 | 1090 | |
b8faf035 | 1091 | static inline int managed_dentry_rcu(struct dentry *dentry) |
62a7375e | 1092 | { |
b8faf035 N |
1093 | return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? |
1094 | dentry->d_op->d_manage(dentry, true) : 0; | |
62a7375e IK |
1095 | } |
1096 | ||
9875cf80 | 1097 | /* |
287548e4 AV |
1098 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
1099 | * we meet a managed dentry that would need blocking. | |
9875cf80 DH |
1100 | */ |
1101 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, | |
287548e4 | 1102 | struct inode **inode) |
9875cf80 | 1103 | { |
62a7375e | 1104 | for (;;) { |
c7105365 | 1105 | struct mount *mounted; |
62a7375e IK |
1106 | /* |
1107 | * Don't forget we might have a non-mountpoint managed dentry | |
1108 | * that wants to block transit. | |
1109 | */ | |
b8faf035 N |
1110 | switch (managed_dentry_rcu(path->dentry)) { |
1111 | case -ECHILD: | |
1112 | default: | |
ab90911f | 1113 | return false; |
b8faf035 N |
1114 | case -EISDIR: |
1115 | return true; | |
1116 | case 0: | |
1117 | break; | |
1118 | } | |
62a7375e IK |
1119 | |
1120 | if (!d_mountpoint(path->dentry)) | |
b8faf035 | 1121 | return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); |
62a7375e | 1122 | |
474279dc | 1123 | mounted = __lookup_mnt(path->mnt, path->dentry); |
9875cf80 DH |
1124 | if (!mounted) |
1125 | break; | |
c7105365 AV |
1126 | path->mnt = &mounted->mnt; |
1127 | path->dentry = mounted->mnt.mnt_root; | |
a3fbbde7 | 1128 | nd->flags |= LOOKUP_JUMPED; |
9875cf80 | 1129 | nd->seq = read_seqcount_begin(&path->dentry->d_seq); |
59430262 LT |
1130 | /* |
1131 | * Update the inode too. We don't need to re-check the | |
1132 | * dentry sequence number here after this d_inode read, | |
1133 | * because a mount-point is always pinned. | |
1134 | */ | |
1135 | *inode = path->dentry->d_inode; | |
9875cf80 | 1136 | } |
f5be3e29 | 1137 | return !read_seqretry(&mount_lock, nd->m_seq) && |
b8faf035 | 1138 | !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); |
287548e4 AV |
1139 | } |
1140 | ||
31e6b01f NP |
1141 | static int follow_dotdot_rcu(struct nameidata *nd) |
1142 | { | |
4023bfc9 | 1143 | struct inode *inode = nd->inode; |
7bd88377 AV |
1144 | if (!nd->root.mnt) |
1145 | set_root_rcu(nd); | |
31e6b01f | 1146 | |
9875cf80 | 1147 | while (1) { |
31e6b01f NP |
1148 | if (nd->path.dentry == nd->root.dentry && |
1149 | nd->path.mnt == nd->root.mnt) { | |
1150 | break; | |
1151 | } | |
1152 | if (nd->path.dentry != nd->path.mnt->mnt_root) { | |
1153 | struct dentry *old = nd->path.dentry; | |
1154 | struct dentry *parent = old->d_parent; | |
1155 | unsigned seq; | |
1156 | ||
4023bfc9 | 1157 | inode = parent->d_inode; |
31e6b01f NP |
1158 | seq = read_seqcount_begin(&parent->d_seq); |
1159 | if (read_seqcount_retry(&old->d_seq, nd->seq)) | |
ef7562d5 | 1160 | goto failed; |
31e6b01f NP |
1161 | nd->path.dentry = parent; |
1162 | nd->seq = seq; | |
1163 | break; | |
1164 | } | |
1165 | if (!follow_up_rcu(&nd->path)) | |
1166 | break; | |
4023bfc9 | 1167 | inode = nd->path.dentry->d_inode; |
31e6b01f | 1168 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); |
31e6b01f | 1169 | } |
b37199e6 AV |
1170 | while (d_mountpoint(nd->path.dentry)) { |
1171 | struct mount *mounted; | |
1172 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); | |
1173 | if (!mounted) | |
1174 | break; | |
1175 | nd->path.mnt = &mounted->mnt; | |
1176 | nd->path.dentry = mounted->mnt.mnt_root; | |
4023bfc9 | 1177 | inode = nd->path.dentry->d_inode; |
b37199e6 | 1178 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); |
f5be3e29 | 1179 | if (read_seqretry(&mount_lock, nd->m_seq)) |
b37199e6 AV |
1180 | goto failed; |
1181 | } | |
4023bfc9 | 1182 | nd->inode = inode; |
31e6b01f | 1183 | return 0; |
ef7562d5 AV |
1184 | |
1185 | failed: | |
1186 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1187 | if (!(nd->flags & LOOKUP_ROOT)) |
1188 | nd->root.mnt = NULL; | |
8b61e74f | 1189 | rcu_read_unlock(); |
ef7562d5 | 1190 | return -ECHILD; |
31e6b01f NP |
1191 | } |
1192 | ||
cc53ce53 DH |
1193 | /* |
1194 | * Follow down to the covering mount currently visible to userspace. At each | |
1195 | * point, the filesystem owning that dentry may be queried as to whether the | |
1196 | * caller is permitted to proceed or not. | |
cc53ce53 | 1197 | */ |
7cc90cc3 | 1198 | int follow_down(struct path *path) |
cc53ce53 DH |
1199 | { |
1200 | unsigned managed; | |
1201 | int ret; | |
1202 | ||
1203 | while (managed = ACCESS_ONCE(path->dentry->d_flags), | |
1204 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { | |
1205 | /* Allow the filesystem to manage the transit without i_mutex | |
1206 | * being held. | |
1207 | * | |
1208 | * We indicate to the filesystem if someone is trying to mount | |
1209 | * something here. This gives autofs the chance to deny anyone | |
1210 | * other than its daemon the right to mount on its | |
1211 | * superstructure. | |
1212 | * | |
1213 | * The filesystem may sleep at this point. | |
1214 | */ | |
1215 | if (managed & DCACHE_MANAGE_TRANSIT) { | |
1216 | BUG_ON(!path->dentry->d_op); | |
1217 | BUG_ON(!path->dentry->d_op->d_manage); | |
ab90911f | 1218 | ret = path->dentry->d_op->d_manage( |
1aed3e42 | 1219 | path->dentry, false); |
cc53ce53 DH |
1220 | if (ret < 0) |
1221 | return ret == -EISDIR ? 0 : ret; | |
1222 | } | |
1223 | ||
1224 | /* Transit to a mounted filesystem. */ | |
1225 | if (managed & DCACHE_MOUNTED) { | |
1226 | struct vfsmount *mounted = lookup_mnt(path); | |
1227 | if (!mounted) | |
1228 | break; | |
1229 | dput(path->dentry); | |
1230 | mntput(path->mnt); | |
1231 | path->mnt = mounted; | |
1232 | path->dentry = dget(mounted->mnt_root); | |
1233 | continue; | |
1234 | } | |
1235 | ||
1236 | /* Don't handle automount points here */ | |
1237 | break; | |
1238 | } | |
1239 | return 0; | |
1240 | } | |
4d359507 | 1241 | EXPORT_SYMBOL(follow_down); |
cc53ce53 | 1242 | |
9875cf80 DH |
1243 | /* |
1244 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() | |
1245 | */ | |
1246 | static void follow_mount(struct path *path) | |
1247 | { | |
1248 | while (d_mountpoint(path->dentry)) { | |
1249 | struct vfsmount *mounted = lookup_mnt(path); | |
1250 | if (!mounted) | |
1251 | break; | |
1252 | dput(path->dentry); | |
1253 | mntput(path->mnt); | |
1254 | path->mnt = mounted; | |
1255 | path->dentry = dget(mounted->mnt_root); | |
1256 | } | |
1257 | } | |
1258 | ||
31e6b01f | 1259 | static void follow_dotdot(struct nameidata *nd) |
1da177e4 | 1260 | { |
7bd88377 AV |
1261 | if (!nd->root.mnt) |
1262 | set_root(nd); | |
e518ddb7 | 1263 | |
1da177e4 | 1264 | while(1) { |
4ac91378 | 1265 | struct dentry *old = nd->path.dentry; |
1da177e4 | 1266 | |
2a737871 AV |
1267 | if (nd->path.dentry == nd->root.dentry && |
1268 | nd->path.mnt == nd->root.mnt) { | |
1da177e4 LT |
1269 | break; |
1270 | } | |
4ac91378 | 1271 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
3088dd70 AV |
1272 | /* rare case of legitimate dget_parent()... */ |
1273 | nd->path.dentry = dget_parent(nd->path.dentry); | |
1da177e4 LT |
1274 | dput(old); |
1275 | break; | |
1276 | } | |
3088dd70 | 1277 | if (!follow_up(&nd->path)) |
1da177e4 | 1278 | break; |
1da177e4 | 1279 | } |
79ed0226 | 1280 | follow_mount(&nd->path); |
31e6b01f | 1281 | nd->inode = nd->path.dentry->d_inode; |
1da177e4 LT |
1282 | } |
1283 | ||
baa03890 | 1284 | /* |
bad61189 MS |
1285 | * This looks up the name in dcache, possibly revalidates the old dentry and |
1286 | * allocates a new one if not found or not valid. In the need_lookup argument | |
1287 | * returns whether i_op->lookup is necessary. | |
1288 | * | |
1289 | * dir->d_inode->i_mutex must be held | |
baa03890 | 1290 | */ |
bad61189 | 1291 | static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, |
201f956e | 1292 | unsigned int flags, bool *need_lookup) |
baa03890 | 1293 | { |
baa03890 | 1294 | struct dentry *dentry; |
bad61189 | 1295 | int error; |
baa03890 | 1296 | |
bad61189 MS |
1297 | *need_lookup = false; |
1298 | dentry = d_lookup(dir, name); | |
1299 | if (dentry) { | |
39e3c955 | 1300 | if (dentry->d_flags & DCACHE_OP_REVALIDATE) { |
201f956e | 1301 | error = d_revalidate(dentry, flags); |
bad61189 MS |
1302 | if (unlikely(error <= 0)) { |
1303 | if (error < 0) { | |
1304 | dput(dentry); | |
1305 | return ERR_PTR(error); | |
5542aa2f EB |
1306 | } else { |
1307 | d_invalidate(dentry); | |
bad61189 MS |
1308 | dput(dentry); |
1309 | dentry = NULL; | |
1310 | } | |
1311 | } | |
1312 | } | |
1313 | } | |
baa03890 | 1314 | |
bad61189 MS |
1315 | if (!dentry) { |
1316 | dentry = d_alloc(dir, name); | |
1317 | if (unlikely(!dentry)) | |
1318 | return ERR_PTR(-ENOMEM); | |
baa03890 | 1319 | |
bad61189 | 1320 | *need_lookup = true; |
baa03890 NP |
1321 | } |
1322 | return dentry; | |
1323 | } | |
1324 | ||
44396f4b | 1325 | /* |
13a2c3be BF |
1326 | * Call i_op->lookup on the dentry. The dentry must be negative and |
1327 | * unhashed. | |
bad61189 MS |
1328 | * |
1329 | * dir->d_inode->i_mutex must be held | |
44396f4b | 1330 | */ |
bad61189 | 1331 | static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, |
72bd866a | 1332 | unsigned int flags) |
44396f4b | 1333 | { |
44396f4b JB |
1334 | struct dentry *old; |
1335 | ||
1336 | /* Don't create child dentry for a dead directory. */ | |
bad61189 | 1337 | if (unlikely(IS_DEADDIR(dir))) { |
e188dc02 | 1338 | dput(dentry); |
44396f4b | 1339 | return ERR_PTR(-ENOENT); |
e188dc02 | 1340 | } |
44396f4b | 1341 | |
72bd866a | 1342 | old = dir->i_op->lookup(dir, dentry, flags); |
44396f4b JB |
1343 | if (unlikely(old)) { |
1344 | dput(dentry); | |
1345 | dentry = old; | |
1346 | } | |
1347 | return dentry; | |
1348 | } | |
1349 | ||
a3255546 | 1350 | static struct dentry *__lookup_hash(struct qstr *name, |
72bd866a | 1351 | struct dentry *base, unsigned int flags) |
a3255546 | 1352 | { |
bad61189 | 1353 | bool need_lookup; |
a3255546 AV |
1354 | struct dentry *dentry; |
1355 | ||
72bd866a | 1356 | dentry = lookup_dcache(name, base, flags, &need_lookup); |
bad61189 MS |
1357 | if (!need_lookup) |
1358 | return dentry; | |
a3255546 | 1359 | |
72bd866a | 1360 | return lookup_real(base->d_inode, dentry, flags); |
a3255546 AV |
1361 | } |
1362 | ||
1da177e4 LT |
1363 | /* |
1364 | * It's more convoluted than I'd like it to be, but... it's still fairly | |
1365 | * small and for now I'd prefer to have fast path as straight as possible. | |
1366 | * It _is_ time-critical. | |
1367 | */ | |
e97cdc87 | 1368 | static int lookup_fast(struct nameidata *nd, |
697f514d | 1369 | struct path *path, struct inode **inode) |
1da177e4 | 1370 | { |
4ac91378 | 1371 | struct vfsmount *mnt = nd->path.mnt; |
31e6b01f | 1372 | struct dentry *dentry, *parent = nd->path.dentry; |
5a18fff2 AV |
1373 | int need_reval = 1; |
1374 | int status = 1; | |
9875cf80 DH |
1375 | int err; |
1376 | ||
b04f784e NP |
1377 | /* |
1378 | * Rename seqlock is not required here because in the off chance | |
1379 | * of a false negative due to a concurrent rename, we're going to | |
1380 | * do the non-racy lookup, below. | |
1381 | */ | |
31e6b01f NP |
1382 | if (nd->flags & LOOKUP_RCU) { |
1383 | unsigned seq; | |
766c4cbf | 1384 | bool negative; |
da53be12 | 1385 | dentry = __d_lookup_rcu(parent, &nd->last, &seq); |
5a18fff2 AV |
1386 | if (!dentry) |
1387 | goto unlazy; | |
1388 | ||
12f8ad4b LT |
1389 | /* |
1390 | * This sequence count validates that the inode matches | |
1391 | * the dentry name information from lookup. | |
1392 | */ | |
1393 | *inode = dentry->d_inode; | |
766c4cbf | 1394 | negative = d_is_negative(dentry); |
12f8ad4b LT |
1395 | if (read_seqcount_retry(&dentry->d_seq, seq)) |
1396 | return -ECHILD; | |
766c4cbf AV |
1397 | if (negative) |
1398 | return -ENOENT; | |
12f8ad4b LT |
1399 | |
1400 | /* | |
1401 | * This sequence count validates that the parent had no | |
1402 | * changes while we did the lookup of the dentry above. | |
1403 | * | |
1404 | * The memory barrier in read_seqcount_begin of child is | |
1405 | * enough, we can use __read_seqcount_retry here. | |
1406 | */ | |
31e6b01f NP |
1407 | if (__read_seqcount_retry(&parent->d_seq, nd->seq)) |
1408 | return -ECHILD; | |
31e6b01f | 1409 | nd->seq = seq; |
5a18fff2 | 1410 | |
24643087 | 1411 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
4ce16ef3 | 1412 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1413 | if (unlikely(status <= 0)) { |
1414 | if (status != -ECHILD) | |
1415 | need_reval = 0; | |
1416 | goto unlazy; | |
1417 | } | |
24643087 | 1418 | } |
31e6b01f NP |
1419 | path->mnt = mnt; |
1420 | path->dentry = dentry; | |
b8faf035 N |
1421 | if (likely(__follow_mount_rcu(nd, path, inode))) |
1422 | return 0; | |
5a18fff2 | 1423 | unlazy: |
19660af7 AV |
1424 | if (unlazy_walk(nd, dentry)) |
1425 | return -ECHILD; | |
5a18fff2 | 1426 | } else { |
e97cdc87 | 1427 | dentry = __d_lookup(parent, &nd->last); |
9875cf80 | 1428 | } |
5a18fff2 | 1429 | |
81e6f520 AV |
1430 | if (unlikely(!dentry)) |
1431 | goto need_lookup; | |
1432 | ||
5a18fff2 | 1433 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) |
4ce16ef3 | 1434 | status = d_revalidate(dentry, nd->flags); |
5a18fff2 AV |
1435 | if (unlikely(status <= 0)) { |
1436 | if (status < 0) { | |
1437 | dput(dentry); | |
1438 | return status; | |
1439 | } | |
5542aa2f EB |
1440 | d_invalidate(dentry); |
1441 | dput(dentry); | |
1442 | goto need_lookup; | |
24643087 | 1443 | } |
697f514d | 1444 | |
766c4cbf AV |
1445 | if (unlikely(d_is_negative(dentry))) { |
1446 | dput(dentry); | |
1447 | return -ENOENT; | |
1448 | } | |
9875cf80 DH |
1449 | path->mnt = mnt; |
1450 | path->dentry = dentry; | |
1451 | err = follow_managed(path, nd->flags); | |
89312214 IK |
1452 | if (unlikely(err < 0)) { |
1453 | path_put_conditional(path, nd); | |
9875cf80 | 1454 | return err; |
89312214 | 1455 | } |
a3fbbde7 AV |
1456 | if (err) |
1457 | nd->flags |= LOOKUP_JUMPED; | |
9875cf80 | 1458 | *inode = path->dentry->d_inode; |
1da177e4 | 1459 | return 0; |
81e6f520 AV |
1460 | |
1461 | need_lookup: | |
697f514d MS |
1462 | return 1; |
1463 | } | |
1464 | ||
1465 | /* Fast lookup failed, do it the slow way */ | |
cc2a5271 | 1466 | static int lookup_slow(struct nameidata *nd, struct path *path) |
697f514d MS |
1467 | { |
1468 | struct dentry *dentry, *parent; | |
1469 | int err; | |
1470 | ||
1471 | parent = nd->path.dentry; | |
81e6f520 AV |
1472 | BUG_ON(nd->inode != parent->d_inode); |
1473 | ||
1474 | mutex_lock(&parent->d_inode->i_mutex); | |
cc2a5271 | 1475 | dentry = __lookup_hash(&nd->last, parent, nd->flags); |
81e6f520 AV |
1476 | mutex_unlock(&parent->d_inode->i_mutex); |
1477 | if (IS_ERR(dentry)) | |
1478 | return PTR_ERR(dentry); | |
697f514d MS |
1479 | path->mnt = nd->path.mnt; |
1480 | path->dentry = dentry; | |
1481 | err = follow_managed(path, nd->flags); | |
1482 | if (unlikely(err < 0)) { | |
1483 | path_put_conditional(path, nd); | |
1484 | return err; | |
1485 | } | |
1486 | if (err) | |
1487 | nd->flags |= LOOKUP_JUMPED; | |
1488 | return 0; | |
1da177e4 LT |
1489 | } |
1490 | ||
52094c8a AV |
1491 | static inline int may_lookup(struct nameidata *nd) |
1492 | { | |
1493 | if (nd->flags & LOOKUP_RCU) { | |
4ad5abb3 | 1494 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
52094c8a AV |
1495 | if (err != -ECHILD) |
1496 | return err; | |
19660af7 | 1497 | if (unlazy_walk(nd, NULL)) |
52094c8a AV |
1498 | return -ECHILD; |
1499 | } | |
4ad5abb3 | 1500 | return inode_permission(nd->inode, MAY_EXEC); |
52094c8a AV |
1501 | } |
1502 | ||
9856fa1b AV |
1503 | static inline int handle_dots(struct nameidata *nd, int type) |
1504 | { | |
1505 | if (type == LAST_DOTDOT) { | |
1506 | if (nd->flags & LOOKUP_RCU) { | |
1507 | if (follow_dotdot_rcu(nd)) | |
1508 | return -ECHILD; | |
1509 | } else | |
1510 | follow_dotdot(nd); | |
1511 | } | |
1512 | return 0; | |
1513 | } | |
1514 | ||
951361f9 AV |
1515 | static void terminate_walk(struct nameidata *nd) |
1516 | { | |
1517 | if (!(nd->flags & LOOKUP_RCU)) { | |
1518 | path_put(&nd->path); | |
1519 | } else { | |
1520 | nd->flags &= ~LOOKUP_RCU; | |
5b6ca027 AV |
1521 | if (!(nd->flags & LOOKUP_ROOT)) |
1522 | nd->root.mnt = NULL; | |
8b61e74f | 1523 | rcu_read_unlock(); |
951361f9 AV |
1524 | } |
1525 | } | |
1526 | ||
3ddcd056 LT |
1527 | /* |
1528 | * Do we need to follow links? We _really_ want to be able | |
1529 | * to do this check without having to look at inode->i_op, | |
1530 | * so we keep a cache of "no, this doesn't need follow_link" | |
1531 | * for the common case. | |
1532 | */ | |
b18825a7 | 1533 | static inline int should_follow_link(struct dentry *dentry, int follow) |
3ddcd056 | 1534 | { |
b18825a7 | 1535 | return unlikely(d_is_symlink(dentry)) ? follow : 0; |
3ddcd056 LT |
1536 | } |
1537 | ||
caa85634 | 1538 | static int walk_component(struct nameidata *nd, int follow) |
ce57dfc1 | 1539 | { |
caa85634 | 1540 | struct path path; |
ce57dfc1 AV |
1541 | struct inode *inode; |
1542 | int err; | |
1543 | /* | |
1544 | * "." and ".." are special - ".." especially so because it has | |
1545 | * to be able to know about the current root directory and | |
1546 | * parent relationships. | |
1547 | */ | |
21b9b073 AV |
1548 | if (unlikely(nd->last_type != LAST_NORM)) |
1549 | return handle_dots(nd, nd->last_type); | |
caa85634 | 1550 | err = lookup_fast(nd, &path, &inode); |
ce57dfc1 | 1551 | if (unlikely(err)) { |
697f514d MS |
1552 | if (err < 0) |
1553 | goto out_err; | |
1554 | ||
caa85634 | 1555 | err = lookup_slow(nd, &path); |
697f514d MS |
1556 | if (err < 0) |
1557 | goto out_err; | |
1558 | ||
caa85634 | 1559 | inode = path.dentry->d_inode; |
766c4cbf | 1560 | err = -ENOENT; |
caa85634 | 1561 | if (d_is_negative(path.dentry)) |
766c4cbf | 1562 | goto out_path_put; |
ce57dfc1 | 1563 | } |
697f514d | 1564 | |
caa85634 | 1565 | if (should_follow_link(path.dentry, follow)) { |
19660af7 | 1566 | if (nd->flags & LOOKUP_RCU) { |
caa85634 AV |
1567 | if (unlikely(nd->path.mnt != path.mnt || |
1568 | unlazy_walk(nd, path.dentry))) { | |
697f514d MS |
1569 | err = -ECHILD; |
1570 | goto out_err; | |
19660af7 AV |
1571 | } |
1572 | } | |
caa85634 AV |
1573 | BUG_ON(inode != path.dentry->d_inode); |
1574 | nd->link = path; | |
ce57dfc1 AV |
1575 | return 1; |
1576 | } | |
caa85634 | 1577 | path_to_nameidata(&path, nd); |
ce57dfc1 AV |
1578 | nd->inode = inode; |
1579 | return 0; | |
697f514d MS |
1580 | |
1581 | out_path_put: | |
caa85634 | 1582 | path_to_nameidata(&path, nd); |
697f514d MS |
1583 | out_err: |
1584 | terminate_walk(nd); | |
1585 | return err; | |
ce57dfc1 AV |
1586 | } |
1587 | ||
bfcfaa77 LT |
1588 | /* |
1589 | * We can do the critical dentry name comparison and hashing | |
1590 | * operations one word at a time, but we are limited to: | |
1591 | * | |
1592 | * - Architectures with fast unaligned word accesses. We could | |
1593 | * do a "get_unaligned()" if this helps and is sufficiently | |
1594 | * fast. | |
1595 | * | |
bfcfaa77 LT |
1596 | * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we |
1597 | * do not trap on the (extremely unlikely) case of a page | |
1598 | * crossing operation. | |
1599 | * | |
1600 | * - Furthermore, we need an efficient 64-bit compile for the | |
1601 | * 64-bit case in order to generate the "number of bytes in | |
1602 | * the final mask". Again, that could be replaced with a | |
1603 | * efficient population count instruction or similar. | |
1604 | */ | |
1605 | #ifdef CONFIG_DCACHE_WORD_ACCESS | |
1606 | ||
f68e556e | 1607 | #include <asm/word-at-a-time.h> |
bfcfaa77 | 1608 | |
f68e556e | 1609 | #ifdef CONFIG_64BIT |
bfcfaa77 LT |
1610 | |
1611 | static inline unsigned int fold_hash(unsigned long hash) | |
1612 | { | |
99d263d4 | 1613 | return hash_64(hash, 32); |
bfcfaa77 LT |
1614 | } |
1615 | ||
1616 | #else /* 32-bit case */ | |
1617 | ||
bfcfaa77 LT |
1618 | #define fold_hash(x) (x) |
1619 | ||
1620 | #endif | |
1621 | ||
1622 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) | |
1623 | { | |
1624 | unsigned long a, mask; | |
1625 | unsigned long hash = 0; | |
1626 | ||
1627 | for (;;) { | |
e419b4cc | 1628 | a = load_unaligned_zeropad(name); |
bfcfaa77 LT |
1629 | if (len < sizeof(unsigned long)) |
1630 | break; | |
1631 | hash += a; | |
f132c5be | 1632 | hash *= 9; |
bfcfaa77 LT |
1633 | name += sizeof(unsigned long); |
1634 | len -= sizeof(unsigned long); | |
1635 | if (!len) | |
1636 | goto done; | |
1637 | } | |
a5c21dce | 1638 | mask = bytemask_from_count(len); |
bfcfaa77 LT |
1639 | hash += mask & a; |
1640 | done: | |
1641 | return fold_hash(hash); | |
1642 | } | |
1643 | EXPORT_SYMBOL(full_name_hash); | |
1644 | ||
bfcfaa77 LT |
1645 | /* |
1646 | * Calculate the length and hash of the path component, and | |
d6bb3e90 | 1647 | * return the "hash_len" as the result. |
bfcfaa77 | 1648 | */ |
d6bb3e90 | 1649 | static inline u64 hash_name(const char *name) |
bfcfaa77 | 1650 | { |
36126f8f LT |
1651 | unsigned long a, b, adata, bdata, mask, hash, len; |
1652 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; | |
bfcfaa77 LT |
1653 | |
1654 | hash = a = 0; | |
1655 | len = -sizeof(unsigned long); | |
1656 | do { | |
1657 | hash = (hash + a) * 9; | |
1658 | len += sizeof(unsigned long); | |
e419b4cc | 1659 | a = load_unaligned_zeropad(name+len); |
36126f8f LT |
1660 | b = a ^ REPEAT_BYTE('/'); |
1661 | } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); | |
1662 | ||
1663 | adata = prep_zero_mask(a, adata, &constants); | |
1664 | bdata = prep_zero_mask(b, bdata, &constants); | |
1665 | ||
1666 | mask = create_zero_mask(adata | bdata); | |
1667 | ||
1668 | hash += a & zero_bytemask(mask); | |
9226b5b4 | 1669 | len += find_zero(mask); |
d6bb3e90 | 1670 | return hashlen_create(fold_hash(hash), len); |
bfcfaa77 LT |
1671 | } |
1672 | ||
1673 | #else | |
1674 | ||
0145acc2 LT |
1675 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) |
1676 | { | |
1677 | unsigned long hash = init_name_hash(); | |
1678 | while (len--) | |
1679 | hash = partial_name_hash(*name++, hash); | |
1680 | return end_name_hash(hash); | |
1681 | } | |
ae942ae7 | 1682 | EXPORT_SYMBOL(full_name_hash); |
0145acc2 | 1683 | |
200e9ef7 LT |
1684 | /* |
1685 | * We know there's a real path component here of at least | |
1686 | * one character. | |
1687 | */ | |
d6bb3e90 | 1688 | static inline u64 hash_name(const char *name) |
200e9ef7 LT |
1689 | { |
1690 | unsigned long hash = init_name_hash(); | |
1691 | unsigned long len = 0, c; | |
1692 | ||
1693 | c = (unsigned char)*name; | |
1694 | do { | |
1695 | len++; | |
1696 | hash = partial_name_hash(c, hash); | |
1697 | c = (unsigned char)name[len]; | |
1698 | } while (c && c != '/'); | |
d6bb3e90 | 1699 | return hashlen_create(end_name_hash(hash), len); |
200e9ef7 LT |
1700 | } |
1701 | ||
bfcfaa77 LT |
1702 | #endif |
1703 | ||
1da177e4 LT |
1704 | /* |
1705 | * Name resolution. | |
ea3834d9 PM |
1706 | * This is the basic name resolution function, turning a pathname into |
1707 | * the final dentry. We expect 'base' to be positive and a directory. | |
1da177e4 | 1708 | * |
ea3834d9 PM |
1709 | * Returns 0 and nd will have valid dentry and mnt on success. |
1710 | * Returns error and drops reference to input namei data on failure. | |
1da177e4 | 1711 | */ |
6de88d72 | 1712 | static int link_path_walk(const char *name, struct nameidata *nd) |
1da177e4 | 1713 | { |
1da177e4 | 1714 | int err; |
1da177e4 LT |
1715 | |
1716 | while (*name=='/') | |
1717 | name++; | |
1718 | if (!*name) | |
086e183a | 1719 | return 0; |
1da177e4 | 1720 | |
1da177e4 LT |
1721 | /* At this point we know we have a real path component. */ |
1722 | for(;;) { | |
d6bb3e90 | 1723 | u64 hash_len; |
fe479a58 | 1724 | int type; |
1da177e4 | 1725 | |
52094c8a | 1726 | err = may_lookup(nd); |
1da177e4 LT |
1727 | if (err) |
1728 | break; | |
1729 | ||
d6bb3e90 | 1730 | hash_len = hash_name(name); |
1da177e4 | 1731 | |
fe479a58 | 1732 | type = LAST_NORM; |
d6bb3e90 | 1733 | if (name[0] == '.') switch (hashlen_len(hash_len)) { |
fe479a58 | 1734 | case 2: |
200e9ef7 | 1735 | if (name[1] == '.') { |
fe479a58 | 1736 | type = LAST_DOTDOT; |
16c2cd71 AV |
1737 | nd->flags |= LOOKUP_JUMPED; |
1738 | } | |
fe479a58 AV |
1739 | break; |
1740 | case 1: | |
1741 | type = LAST_DOT; | |
1742 | } | |
5a202bcd AV |
1743 | if (likely(type == LAST_NORM)) { |
1744 | struct dentry *parent = nd->path.dentry; | |
16c2cd71 | 1745 | nd->flags &= ~LOOKUP_JUMPED; |
5a202bcd | 1746 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
a060dc50 | 1747 | struct qstr this = { { .hash_len = hash_len }, .name = name }; |
da53be12 | 1748 | err = parent->d_op->d_hash(parent, &this); |
5a202bcd AV |
1749 | if (err < 0) |
1750 | break; | |
d6bb3e90 LT |
1751 | hash_len = this.hash_len; |
1752 | name = this.name; | |
5a202bcd AV |
1753 | } |
1754 | } | |
fe479a58 | 1755 | |
d6bb3e90 LT |
1756 | nd->last.hash_len = hash_len; |
1757 | nd->last.name = name; | |
5f4a6a69 AV |
1758 | nd->last_type = type; |
1759 | ||
d6bb3e90 LT |
1760 | name += hashlen_len(hash_len); |
1761 | if (!*name) | |
5f4a6a69 | 1762 | return 0; |
200e9ef7 LT |
1763 | /* |
1764 | * If it wasn't NUL, we know it was '/'. Skip that | |
1765 | * slash, and continue until no more slashes. | |
1766 | */ | |
1767 | do { | |
d6bb3e90 LT |
1768 | name++; |
1769 | } while (unlikely(*name == '/')); | |
1770 | if (!*name) | |
5f4a6a69 AV |
1771 | return 0; |
1772 | ||
caa85634 | 1773 | err = walk_component(nd, LOOKUP_FOLLOW); |
ce57dfc1 AV |
1774 | if (err < 0) |
1775 | return err; | |
1da177e4 | 1776 | |
ce57dfc1 | 1777 | if (err) { |
d40bcc09 AV |
1778 | struct path link; |
1779 | void *cookie; | |
1780 | const char *s; | |
1781 | ||
5a460275 AV |
1782 | if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { |
1783 | path_put_conditional(&nd->link, nd); | |
1784 | path_put(&nd->path); | |
1785 | return -ELOOP; | |
1786 | } | |
1787 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); | |
1788 | ||
1789 | nd->depth++; | |
1790 | current->link_count++; | |
1791 | ||
d40bcc09 AV |
1792 | loop: /* will be gone very soon */ |
1793 | link = nd->link; | |
1794 | s = get_link(&link, nd, &cookie); | |
5a460275 | 1795 | |
d40bcc09 AV |
1796 | if (unlikely(IS_ERR(s))) { |
1797 | err = PTR_ERR(s); | |
1798 | current->link_count--; | |
1799 | nd->depth--; | |
1800 | return err; | |
1801 | } | |
1802 | err = 0; | |
1803 | if (unlikely(!s)) { | |
1804 | /* jumped */ | |
1805 | put_link(nd, &link, cookie); | |
1806 | } else { | |
1807 | if (*s == '/') { | |
1808 | if (!nd->root.mnt) | |
1809 | set_root(nd); | |
1810 | path_put(&nd->path); | |
1811 | nd->path = nd->root; | |
1812 | path_get(&nd->root); | |
1813 | nd->flags |= LOOKUP_JUMPED; | |
172a39a0 | 1814 | } |
d40bcc09 AV |
1815 | nd->inode = nd->path.dentry->d_inode; |
1816 | err = link_path_walk(s, nd); | |
1817 | if (unlikely(err)) { | |
12b09578 | 1818 | put_link(nd, &link, cookie); |
12b09578 | 1819 | } else { |
12b09578 AV |
1820 | err = walk_component(nd, LOOKUP_FOLLOW); |
1821 | put_link(nd, &link, cookie); | |
d40bcc09 AV |
1822 | if (err > 0) |
1823 | goto loop; | |
172a39a0 | 1824 | } |
d40bcc09 | 1825 | } |
5a460275 AV |
1826 | |
1827 | current->link_count--; | |
1828 | nd->depth--; | |
1da177e4 | 1829 | if (err) |
a7472bab | 1830 | return err; |
31e6b01f | 1831 | } |
44b1d530 | 1832 | if (!d_can_lookup(nd->path.dentry)) { |
caa85634 | 1833 | err = -ENOTDIR; |
5f4a6a69 AV |
1834 | break; |
1835 | } | |
1da177e4 | 1836 | } |
951361f9 | 1837 | terminate_walk(nd); |
1da177e4 LT |
1838 | return err; |
1839 | } | |
1840 | ||
6e8a1f87 | 1841 | static int path_init(int dfd, const struct filename *name, unsigned int flags, |
5e53084d | 1842 | struct nameidata *nd) |
31e6b01f NP |
1843 | { |
1844 | int retval = 0; | |
fd2f7cb5 | 1845 | const char *s = name->name; |
31e6b01f NP |
1846 | |
1847 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ | |
980f3ea2 | 1848 | nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; |
31e6b01f | 1849 | nd->depth = 0; |
5e53084d | 1850 | nd->base = NULL; |
5b6ca027 | 1851 | if (flags & LOOKUP_ROOT) { |
b18825a7 DH |
1852 | struct dentry *root = nd->root.dentry; |
1853 | struct inode *inode = root->d_inode; | |
fd2f7cb5 | 1854 | if (*s) { |
44b1d530 | 1855 | if (!d_can_lookup(root)) |
73d049a4 AV |
1856 | return -ENOTDIR; |
1857 | retval = inode_permission(inode, MAY_EXEC); | |
1858 | if (retval) | |
1859 | return retval; | |
1860 | } | |
5b6ca027 AV |
1861 | nd->path = nd->root; |
1862 | nd->inode = inode; | |
1863 | if (flags & LOOKUP_RCU) { | |
8b61e74f | 1864 | rcu_read_lock(); |
5b6ca027 | 1865 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
48a066e7 | 1866 | nd->m_seq = read_seqbegin(&mount_lock); |
5b6ca027 AV |
1867 | } else { |
1868 | path_get(&nd->path); | |
1869 | } | |
d465887f | 1870 | goto done; |
5b6ca027 AV |
1871 | } |
1872 | ||
31e6b01f | 1873 | nd->root.mnt = NULL; |
31e6b01f | 1874 | |
48a066e7 | 1875 | nd->m_seq = read_seqbegin(&mount_lock); |
fd2f7cb5 | 1876 | if (*s == '/') { |
e41f7d4e | 1877 | if (flags & LOOKUP_RCU) { |
8b61e74f | 1878 | rcu_read_lock(); |
7bd88377 | 1879 | nd->seq = set_root_rcu(nd); |
e41f7d4e AV |
1880 | } else { |
1881 | set_root(nd); | |
1882 | path_get(&nd->root); | |
1883 | } | |
1884 | nd->path = nd->root; | |
31e6b01f | 1885 | } else if (dfd == AT_FDCWD) { |
e41f7d4e AV |
1886 | if (flags & LOOKUP_RCU) { |
1887 | struct fs_struct *fs = current->fs; | |
1888 | unsigned seq; | |
31e6b01f | 1889 | |
8b61e74f | 1890 | rcu_read_lock(); |
c28cc364 | 1891 | |
e41f7d4e AV |
1892 | do { |
1893 | seq = read_seqcount_begin(&fs->seq); | |
1894 | nd->path = fs->pwd; | |
1895 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); | |
1896 | } while (read_seqcount_retry(&fs->seq, seq)); | |
1897 | } else { | |
1898 | get_fs_pwd(current->fs, &nd->path); | |
1899 | } | |
31e6b01f | 1900 | } else { |
582aa64a | 1901 | /* Caller must check execute permissions on the starting path component */ |
2903ff01 | 1902 | struct fd f = fdget_raw(dfd); |
31e6b01f NP |
1903 | struct dentry *dentry; |
1904 | ||
2903ff01 AV |
1905 | if (!f.file) |
1906 | return -EBADF; | |
31e6b01f | 1907 | |
2903ff01 | 1908 | dentry = f.file->f_path.dentry; |
31e6b01f | 1909 | |
fd2f7cb5 | 1910 | if (*s) { |
44b1d530 | 1911 | if (!d_can_lookup(dentry)) { |
2903ff01 AV |
1912 | fdput(f); |
1913 | return -ENOTDIR; | |
1914 | } | |
f52e0c11 | 1915 | } |
31e6b01f | 1916 | |
2903ff01 | 1917 | nd->path = f.file->f_path; |
e41f7d4e | 1918 | if (flags & LOOKUP_RCU) { |
9c225f26 | 1919 | if (f.flags & FDPUT_FPUT) |
5e53084d | 1920 | nd->base = f.file; |
e41f7d4e | 1921 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
8b61e74f | 1922 | rcu_read_lock(); |
e41f7d4e | 1923 | } else { |
2903ff01 AV |
1924 | path_get(&nd->path); |
1925 | fdput(f); | |
e41f7d4e | 1926 | } |
31e6b01f | 1927 | } |
31e6b01f | 1928 | |
31e6b01f | 1929 | nd->inode = nd->path.dentry->d_inode; |
4023bfc9 | 1930 | if (!(flags & LOOKUP_RCU)) |
d465887f | 1931 | goto done; |
4023bfc9 | 1932 | if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) |
d465887f | 1933 | goto done; |
4023bfc9 AV |
1934 | if (!(nd->flags & LOOKUP_ROOT)) |
1935 | nd->root.mnt = NULL; | |
1936 | rcu_read_unlock(); | |
1937 | return -ECHILD; | |
d465887f AV |
1938 | done: |
1939 | current->total_link_count = 0; | |
fd2f7cb5 | 1940 | return link_path_walk(s, nd); |
9b4a9b14 AV |
1941 | } |
1942 | ||
893b7775 AV |
1943 | static void path_cleanup(struct nameidata *nd) |
1944 | { | |
1945 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { | |
1946 | path_put(&nd->root); | |
1947 | nd->root.mnt = NULL; | |
1948 | } | |
1949 | if (unlikely(nd->base)) | |
1950 | fput(nd->base); | |
9b4a9b14 AV |
1951 | } |
1952 | ||
95fa25d9 AV |
1953 | static int trailing_symlink(struct path *link, struct nameidata *nd, void **p) |
1954 | { | |
1955 | const char *s; | |
1956 | int error = may_follow_link(link, nd); | |
1957 | if (unlikely(error)) | |
1958 | return error; | |
1959 | nd->flags |= LOOKUP_PARENT; | |
1960 | s = get_link(link, nd, p); | |
1961 | if (unlikely(IS_ERR(s))) | |
1962 | return PTR_ERR(s); | |
1963 | if (unlikely(!s)) | |
1964 | return 0; | |
1965 | if (*s == '/') { | |
1966 | if (!nd->root.mnt) | |
1967 | set_root(nd); | |
1968 | path_put(&nd->path); | |
1969 | nd->path = nd->root; | |
1970 | path_get(&nd->root); | |
1971 | nd->flags |= LOOKUP_JUMPED; | |
1972 | } | |
1973 | nd->inode = nd->path.dentry->d_inode; | |
1974 | error = link_path_walk(s, nd); | |
1975 | if (unlikely(error)) | |
1976 | put_link(nd, link, *p); | |
1977 | return error; | |
1978 | } | |
1979 | ||
caa85634 | 1980 | static inline int lookup_last(struct nameidata *nd) |
bd92d7fe AV |
1981 | { |
1982 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) | |
1983 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
1984 | ||
1985 | nd->flags &= ~LOOKUP_PARENT; | |
caa85634 | 1986 | return walk_component(nd, nd->flags & LOOKUP_FOLLOW); |
bd92d7fe AV |
1987 | } |
1988 | ||
9b4a9b14 | 1989 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
5eb6b495 | 1990 | static int path_lookupat(int dfd, const struct filename *name, |
9b4a9b14 AV |
1991 | unsigned int flags, struct nameidata *nd) |
1992 | { | |
bd92d7fe | 1993 | int err; |
31e6b01f NP |
1994 | |
1995 | /* | |
1996 | * Path walking is largely split up into 2 different synchronisation | |
1997 | * schemes, rcu-walk and ref-walk (explained in | |
1998 | * Documentation/filesystems/path-lookup.txt). These share much of the | |
1999 | * path walk code, but some things particularly setup, cleanup, and | |
2000 | * following mounts are sufficiently divergent that functions are | |
2001 | * duplicated. Typically there is a function foo(), and its RCU | |
2002 | * analogue, foo_rcu(). | |
2003 | * | |
2004 | * -ECHILD is the error number of choice (just to avoid clashes) that | |
2005 | * is returned if some aspect of an rcu-walk fails. Such an error must | |
2006 | * be handled by restarting a traditional ref-walk (which will always | |
2007 | * be able to complete). | |
2008 | */ | |
6e8a1f87 | 2009 | err = path_init(dfd, name, flags, nd); |
bd92d7fe | 2010 | if (!err && !(flags & LOOKUP_PARENT)) { |
caa85634 | 2011 | err = lookup_last(nd); |
bd92d7fe AV |
2012 | while (err > 0) { |
2013 | void *cookie; | |
caa85634 | 2014 | struct path link = nd->link; |
95fa25d9 | 2015 | err = trailing_symlink(&link, nd, &cookie); |
6d7b5aae AV |
2016 | if (err) |
2017 | break; | |
caa85634 | 2018 | err = lookup_last(nd); |
574197e0 | 2019 | put_link(nd, &link, cookie); |
bd92d7fe AV |
2020 | } |
2021 | } | |
ee0827cd | 2022 | |
9f1fafee AV |
2023 | if (!err) |
2024 | err = complete_walk(nd); | |
bd92d7fe AV |
2025 | |
2026 | if (!err && nd->flags & LOOKUP_DIRECTORY) { | |
44b1d530 | 2027 | if (!d_can_lookup(nd->path.dentry)) { |
bd92d7fe | 2028 | path_put(&nd->path); |
bd23a539 | 2029 | err = -ENOTDIR; |
bd92d7fe AV |
2030 | } |
2031 | } | |
16c2cd71 | 2032 | |
893b7775 | 2033 | path_cleanup(nd); |
bd92d7fe | 2034 | return err; |
ee0827cd | 2035 | } |
31e6b01f | 2036 | |
873f1eed | 2037 | static int filename_lookup(int dfd, struct filename *name, |
ee0827cd AV |
2038 | unsigned int flags, struct nameidata *nd) |
2039 | { | |
5eb6b495 | 2040 | int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); |
ee0827cd | 2041 | if (unlikely(retval == -ECHILD)) |
5eb6b495 | 2042 | retval = path_lookupat(dfd, name, flags, nd); |
ee0827cd | 2043 | if (unlikely(retval == -ESTALE)) |
5eb6b495 | 2044 | retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); |
31e6b01f | 2045 | |
f78570dd | 2046 | if (likely(!retval)) |
adb5c247 | 2047 | audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); |
170aa3d0 | 2048 | return retval; |
1da177e4 LT |
2049 | } |
2050 | ||
79714f72 AV |
2051 | /* does lookup, returns the object with parent locked */ |
2052 | struct dentry *kern_path_locked(const char *name, struct path *path) | |
5590ff0d | 2053 | { |
51689104 | 2054 | struct filename *filename = getname_kernel(name); |
79714f72 AV |
2055 | struct nameidata nd; |
2056 | struct dentry *d; | |
51689104 PM |
2057 | int err; |
2058 | ||
2059 | if (IS_ERR(filename)) | |
2060 | return ERR_CAST(filename); | |
2061 | ||
2062 | err = filename_lookup(AT_FDCWD, filename, LOOKUP_PARENT, &nd); | |
2063 | if (err) { | |
2064 | d = ERR_PTR(err); | |
2065 | goto out; | |
2066 | } | |
79714f72 AV |
2067 | if (nd.last_type != LAST_NORM) { |
2068 | path_put(&nd.path); | |
51689104 PM |
2069 | d = ERR_PTR(-EINVAL); |
2070 | goto out; | |
79714f72 AV |
2071 | } |
2072 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); | |
1e0ea001 | 2073 | d = __lookup_hash(&nd.last, nd.path.dentry, 0); |
79714f72 AV |
2074 | if (IS_ERR(d)) { |
2075 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); | |
2076 | path_put(&nd.path); | |
51689104 | 2077 | goto out; |
79714f72 AV |
2078 | } |
2079 | *path = nd.path; | |
51689104 PM |
2080 | out: |
2081 | putname(filename); | |
79714f72 | 2082 | return d; |
5590ff0d UD |
2083 | } |
2084 | ||
d1811465 AV |
2085 | int kern_path(const char *name, unsigned int flags, struct path *path) |
2086 | { | |
2087 | struct nameidata nd; | |
74eb8cc5 AV |
2088 | struct filename *filename = getname_kernel(name); |
2089 | int res = PTR_ERR(filename); | |
2090 | ||
2091 | if (!IS_ERR(filename)) { | |
2092 | res = filename_lookup(AT_FDCWD, filename, flags, &nd); | |
2093 | putname(filename); | |
2094 | if (!res) | |
2095 | *path = nd.path; | |
2096 | } | |
d1811465 AV |
2097 | return res; |
2098 | } | |
4d359507 | 2099 | EXPORT_SYMBOL(kern_path); |
d1811465 | 2100 | |
16f18200 JJS |
2101 | /** |
2102 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair | |
2103 | * @dentry: pointer to dentry of the base directory | |
2104 | * @mnt: pointer to vfs mount of the base directory | |
2105 | * @name: pointer to file name | |
2106 | * @flags: lookup flags | |
e0a01249 | 2107 | * @path: pointer to struct path to fill |
16f18200 JJS |
2108 | */ |
2109 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, | |
2110 | const char *name, unsigned int flags, | |
e0a01249 | 2111 | struct path *path) |
16f18200 | 2112 | { |
74eb8cc5 AV |
2113 | struct filename *filename = getname_kernel(name); |
2114 | int err = PTR_ERR(filename); | |
2115 | ||
e0a01249 | 2116 | BUG_ON(flags & LOOKUP_PARENT); |
74eb8cc5 AV |
2117 | |
2118 | /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ | |
2119 | if (!IS_ERR(filename)) { | |
2120 | struct nameidata nd; | |
2121 | nd.root.dentry = dentry; | |
2122 | nd.root.mnt = mnt; | |
2123 | err = filename_lookup(AT_FDCWD, filename, | |
2124 | flags | LOOKUP_ROOT, &nd); | |
2125 | if (!err) | |
2126 | *path = nd.path; | |
2127 | putname(filename); | |
2128 | } | |
e0a01249 | 2129 | return err; |
16f18200 | 2130 | } |
4d359507 | 2131 | EXPORT_SYMBOL(vfs_path_lookup); |
16f18200 | 2132 | |
eead1911 | 2133 | /** |
a6b91919 | 2134 | * lookup_one_len - filesystem helper to lookup single pathname component |
eead1911 CH |
2135 | * @name: pathname component to lookup |
2136 | * @base: base directory to lookup from | |
2137 | * @len: maximum length @len should be interpreted to | |
2138 | * | |
a6b91919 | 2139 | * Note that this routine is purely a helper for filesystem usage and should |
9e7543e9 | 2140 | * not be called by generic code. |
eead1911 | 2141 | */ |
057f6c01 JM |
2142 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
2143 | { | |
057f6c01 | 2144 | struct qstr this; |
6a96ba54 | 2145 | unsigned int c; |
cda309de | 2146 | int err; |
057f6c01 | 2147 | |
2f9092e1 DW |
2148 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
2149 | ||
6a96ba54 AV |
2150 | this.name = name; |
2151 | this.len = len; | |
0145acc2 | 2152 | this.hash = full_name_hash(name, len); |
6a96ba54 AV |
2153 | if (!len) |
2154 | return ERR_PTR(-EACCES); | |
2155 | ||
21d8a15a AV |
2156 | if (unlikely(name[0] == '.')) { |
2157 | if (len < 2 || (len == 2 && name[1] == '.')) | |
2158 | return ERR_PTR(-EACCES); | |
2159 | } | |
2160 | ||
6a96ba54 AV |
2161 | while (len--) { |
2162 | c = *(const unsigned char *)name++; | |
2163 | if (c == '/' || c == '\0') | |
2164 | return ERR_PTR(-EACCES); | |
6a96ba54 | 2165 | } |
5a202bcd AV |
2166 | /* |
2167 | * See if the low-level filesystem might want | |
2168 | * to use its own hash.. | |
2169 | */ | |
2170 | if (base->d_flags & DCACHE_OP_HASH) { | |
da53be12 | 2171 | int err = base->d_op->d_hash(base, &this); |
5a202bcd AV |
2172 | if (err < 0) |
2173 | return ERR_PTR(err); | |
2174 | } | |
eead1911 | 2175 | |
cda309de MS |
2176 | err = inode_permission(base->d_inode, MAY_EXEC); |
2177 | if (err) | |
2178 | return ERR_PTR(err); | |
2179 | ||
72bd866a | 2180 | return __lookup_hash(&this, base, 0); |
057f6c01 | 2181 | } |
4d359507 | 2182 | EXPORT_SYMBOL(lookup_one_len); |
057f6c01 | 2183 | |
1fa1e7f6 AW |
2184 | int user_path_at_empty(int dfd, const char __user *name, unsigned flags, |
2185 | struct path *path, int *empty) | |
1da177e4 | 2186 | { |
2d8f3038 | 2187 | struct nameidata nd; |
91a27b2a | 2188 | struct filename *tmp = getname_flags(name, flags, empty); |
1da177e4 | 2189 | int err = PTR_ERR(tmp); |
1da177e4 | 2190 | if (!IS_ERR(tmp)) { |
2d8f3038 AV |
2191 | |
2192 | BUG_ON(flags & LOOKUP_PARENT); | |
2193 | ||
873f1eed | 2194 | err = filename_lookup(dfd, tmp, flags, &nd); |
1da177e4 | 2195 | putname(tmp); |
2d8f3038 AV |
2196 | if (!err) |
2197 | *path = nd.path; | |
1da177e4 LT |
2198 | } |
2199 | return err; | |
2200 | } | |
2201 | ||
1fa1e7f6 AW |
2202 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
2203 | struct path *path) | |
2204 | { | |
f7493e5d | 2205 | return user_path_at_empty(dfd, name, flags, path, NULL); |
1fa1e7f6 | 2206 | } |
4d359507 | 2207 | EXPORT_SYMBOL(user_path_at); |
1fa1e7f6 | 2208 | |
873f1eed JL |
2209 | /* |
2210 | * NB: most callers don't do anything directly with the reference to the | |
2211 | * to struct filename, but the nd->last pointer points into the name string | |
2212 | * allocated by getname. So we must hold the reference to it until all | |
2213 | * path-walking is complete. | |
2214 | */ | |
91a27b2a | 2215 | static struct filename * |
f5beed75 AV |
2216 | user_path_parent(int dfd, const char __user *path, |
2217 | struct path *parent, | |
2218 | struct qstr *last, | |
2219 | int *type, | |
9e790bd6 | 2220 | unsigned int flags) |
2ad94ae6 | 2221 | { |
f5beed75 | 2222 | struct nameidata nd; |
91a27b2a | 2223 | struct filename *s = getname(path); |
2ad94ae6 AV |
2224 | int error; |
2225 | ||
9e790bd6 JL |
2226 | /* only LOOKUP_REVAL is allowed in extra flags */ |
2227 | flags &= LOOKUP_REVAL; | |
2228 | ||
2ad94ae6 | 2229 | if (IS_ERR(s)) |
91a27b2a | 2230 | return s; |
2ad94ae6 | 2231 | |
f5beed75 | 2232 | error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, &nd); |
91a27b2a | 2233 | if (error) { |
2ad94ae6 | 2234 | putname(s); |
91a27b2a JL |
2235 | return ERR_PTR(error); |
2236 | } | |
f5beed75 AV |
2237 | *parent = nd.path; |
2238 | *last = nd.last; | |
2239 | *type = nd.last_type; | |
2ad94ae6 | 2240 | |
91a27b2a | 2241 | return s; |
2ad94ae6 AV |
2242 | } |
2243 | ||
8033426e | 2244 | /** |
197df04c | 2245 | * mountpoint_last - look up last component for umount |
8033426e JL |
2246 | * @nd: pathwalk nameidata - currently pointing at parent directory of "last" |
2247 | * @path: pointer to container for result | |
2248 | * | |
2249 | * This is a special lookup_last function just for umount. In this case, we | |
2250 | * need to resolve the path without doing any revalidation. | |
2251 | * | |
2252 | * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since | |
2253 | * mountpoints are always pinned in the dcache, their ancestors are too. Thus, | |
2254 | * in almost all cases, this lookup will be served out of the dcache. The only | |
2255 | * cases where it won't are if nd->last refers to a symlink or the path is | |
2256 | * bogus and it doesn't exist. | |
2257 | * | |
2258 | * Returns: | |
2259 | * -error: if there was an error during lookup. This includes -ENOENT if the | |
2260 | * lookup found a negative dentry. The nd->path reference will also be | |
2261 | * put in this case. | |
2262 | * | |
2263 | * 0: if we successfully resolved nd->path and found it to not to be a | |
2264 | * symlink that needs to be followed. "path" will also be populated. | |
2265 | * The nd->path reference will also be put. | |
2266 | * | |
2267 | * 1: if we successfully resolved nd->last and found it to be a symlink | |
2268 | * that needs to be followed. "path" will be populated with the path | |
2269 | * to the link, and nd->path will *not* be put. | |
2270 | */ | |
2271 | static int | |
197df04c | 2272 | mountpoint_last(struct nameidata *nd, struct path *path) |
8033426e JL |
2273 | { |
2274 | int error = 0; | |
2275 | struct dentry *dentry; | |
2276 | struct dentry *dir = nd->path.dentry; | |
2277 | ||
35759521 AV |
2278 | /* If we're in rcuwalk, drop out of it to handle last component */ |
2279 | if (nd->flags & LOOKUP_RCU) { | |
2280 | if (unlazy_walk(nd, NULL)) { | |
2281 | error = -ECHILD; | |
2282 | goto out; | |
2283 | } | |
8033426e JL |
2284 | } |
2285 | ||
2286 | nd->flags &= ~LOOKUP_PARENT; | |
2287 | ||
2288 | if (unlikely(nd->last_type != LAST_NORM)) { | |
2289 | error = handle_dots(nd, nd->last_type); | |
35759521 AV |
2290 | if (error) |
2291 | goto out; | |
2292 | dentry = dget(nd->path.dentry); | |
2293 | goto done; | |
8033426e JL |
2294 | } |
2295 | ||
2296 | mutex_lock(&dir->d_inode->i_mutex); | |
2297 | dentry = d_lookup(dir, &nd->last); | |
2298 | if (!dentry) { | |
2299 | /* | |
2300 | * No cached dentry. Mounted dentries are pinned in the cache, | |
2301 | * so that means that this dentry is probably a symlink or the | |
2302 | * path doesn't actually point to a mounted dentry. | |
2303 | */ | |
2304 | dentry = d_alloc(dir, &nd->last); | |
2305 | if (!dentry) { | |
2306 | error = -ENOMEM; | |
bcceeeba | 2307 | mutex_unlock(&dir->d_inode->i_mutex); |
35759521 | 2308 | goto out; |
8033426e | 2309 | } |
35759521 AV |
2310 | dentry = lookup_real(dir->d_inode, dentry, nd->flags); |
2311 | error = PTR_ERR(dentry); | |
bcceeeba DJ |
2312 | if (IS_ERR(dentry)) { |
2313 | mutex_unlock(&dir->d_inode->i_mutex); | |
35759521 | 2314 | goto out; |
bcceeeba | 2315 | } |
8033426e JL |
2316 | } |
2317 | mutex_unlock(&dir->d_inode->i_mutex); | |
2318 | ||
35759521 | 2319 | done: |
698934df | 2320 | if (d_is_negative(dentry)) { |
35759521 AV |
2321 | error = -ENOENT; |
2322 | dput(dentry); | |
2323 | goto out; | |
8033426e | 2324 | } |
35759521 | 2325 | path->dentry = dentry; |
295dc39d | 2326 | path->mnt = nd->path.mnt; |
caa85634 AV |
2327 | if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) { |
2328 | nd->link = *path; | |
35759521 | 2329 | return 1; |
caa85634 | 2330 | } |
295dc39d | 2331 | mntget(path->mnt); |
35759521 AV |
2332 | follow_mount(path); |
2333 | error = 0; | |
2334 | out: | |
8033426e JL |
2335 | terminate_walk(nd); |
2336 | return error; | |
2337 | } | |
2338 | ||
2339 | /** | |
197df04c | 2340 | * path_mountpoint - look up a path to be umounted |
8033426e JL |
2341 | * @dfd: directory file descriptor to start walk from |
2342 | * @name: full pathname to walk | |
606d6fe3 | 2343 | * @path: pointer to container for result |
8033426e | 2344 | * @flags: lookup flags |
8033426e JL |
2345 | * |
2346 | * Look up the given name, but don't attempt to revalidate the last component. | |
606d6fe3 | 2347 | * Returns 0 and "path" will be valid on success; Returns error otherwise. |
8033426e JL |
2348 | */ |
2349 | static int | |
668696dc | 2350 | path_mountpoint(int dfd, const struct filename *name, struct path *path, |
46afd6f6 | 2351 | struct nameidata *nd, unsigned int flags) |
8033426e | 2352 | { |
46afd6f6 | 2353 | int err = path_init(dfd, name, flags, nd); |
8033426e | 2354 | if (unlikely(err)) |
115cbfdc | 2355 | goto out; |
8033426e | 2356 | |
46afd6f6 | 2357 | err = mountpoint_last(nd, path); |
8033426e JL |
2358 | while (err > 0) { |
2359 | void *cookie; | |
2360 | struct path link = *path; | |
95fa25d9 | 2361 | err = trailing_symlink(&link, nd, &cookie); |
8033426e JL |
2362 | if (err) |
2363 | break; | |
46afd6f6 AV |
2364 | err = mountpoint_last(nd, path); |
2365 | put_link(nd, &link, cookie); | |
8033426e JL |
2366 | } |
2367 | out: | |
46afd6f6 | 2368 | path_cleanup(nd); |
8033426e JL |
2369 | return err; |
2370 | } | |
2371 | ||
2d864651 | 2372 | static int |
668696dc | 2373 | filename_mountpoint(int dfd, struct filename *name, struct path *path, |
2d864651 AV |
2374 | unsigned int flags) |
2375 | { | |
46afd6f6 | 2376 | struct nameidata nd; |
cbaab2db | 2377 | int error; |
668696dc AV |
2378 | if (IS_ERR(name)) |
2379 | return PTR_ERR(name); | |
46afd6f6 | 2380 | error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); |
2d864651 | 2381 | if (unlikely(error == -ECHILD)) |
46afd6f6 | 2382 | error = path_mountpoint(dfd, name, path, &nd, flags); |
2d864651 | 2383 | if (unlikely(error == -ESTALE)) |
46afd6f6 | 2384 | error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); |
2d864651 | 2385 | if (likely(!error)) |
668696dc AV |
2386 | audit_inode(name, path->dentry, 0); |
2387 | putname(name); | |
2d864651 AV |
2388 | return error; |
2389 | } | |
2390 | ||
8033426e | 2391 | /** |
197df04c | 2392 | * user_path_mountpoint_at - lookup a path from userland in order to umount it |
8033426e JL |
2393 | * @dfd: directory file descriptor |
2394 | * @name: pathname from userland | |
2395 | * @flags: lookup flags | |
2396 | * @path: pointer to container to hold result | |
2397 | * | |
2398 | * A umount is a special case for path walking. We're not actually interested | |
2399 | * in the inode in this situation, and ESTALE errors can be a problem. We | |
2400 | * simply want track down the dentry and vfsmount attached at the mountpoint | |
2401 | * and avoid revalidating the last component. | |
2402 | * | |
2403 | * Returns 0 and populates "path" on success. | |
2404 | */ | |
2405 | int | |
197df04c | 2406 | user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, |
8033426e JL |
2407 | struct path *path) |
2408 | { | |
cbaab2db | 2409 | return filename_mountpoint(dfd, getname(name), path, flags); |
8033426e JL |
2410 | } |
2411 | ||
2d864651 AV |
2412 | int |
2413 | kern_path_mountpoint(int dfd, const char *name, struct path *path, | |
2414 | unsigned int flags) | |
2415 | { | |
cbaab2db | 2416 | return filename_mountpoint(dfd, getname_kernel(name), path, flags); |
2d864651 AV |
2417 | } |
2418 | EXPORT_SYMBOL(kern_path_mountpoint); | |
2419 | ||
cbdf35bc | 2420 | int __check_sticky(struct inode *dir, struct inode *inode) |
1da177e4 | 2421 | { |
8e96e3b7 | 2422 | kuid_t fsuid = current_fsuid(); |
da9592ed | 2423 | |
8e96e3b7 | 2424 | if (uid_eq(inode->i_uid, fsuid)) |
1da177e4 | 2425 | return 0; |
8e96e3b7 | 2426 | if (uid_eq(dir->i_uid, fsuid)) |
1da177e4 | 2427 | return 0; |
23adbe12 | 2428 | return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); |
1da177e4 | 2429 | } |
cbdf35bc | 2430 | EXPORT_SYMBOL(__check_sticky); |
1da177e4 LT |
2431 | |
2432 | /* | |
2433 | * Check whether we can remove a link victim from directory dir, check | |
2434 | * whether the type of victim is right. | |
2435 | * 1. We can't do it if dir is read-only (done in permission()) | |
2436 | * 2. We should have write and exec permissions on dir | |
2437 | * 3. We can't remove anything from append-only dir | |
2438 | * 4. We can't do anything with immutable dir (done in permission()) | |
2439 | * 5. If the sticky bit on dir is set we should either | |
2440 | * a. be owner of dir, or | |
2441 | * b. be owner of victim, or | |
2442 | * c. have CAP_FOWNER capability | |
2443 | * 6. If the victim is append-only or immutable we can't do antyhing with | |
2444 | * links pointing to it. | |
2445 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. | |
2446 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. | |
2447 | * 9. We can't remove a root or mountpoint. | |
2448 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by | |
2449 | * nfs_async_unlink(). | |
2450 | */ | |
b18825a7 | 2451 | static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) |
1da177e4 | 2452 | { |
b18825a7 | 2453 | struct inode *inode = victim->d_inode; |
1da177e4 LT |
2454 | int error; |
2455 | ||
b18825a7 | 2456 | if (d_is_negative(victim)) |
1da177e4 | 2457 | return -ENOENT; |
b18825a7 | 2458 | BUG_ON(!inode); |
1da177e4 LT |
2459 | |
2460 | BUG_ON(victim->d_parent->d_inode != dir); | |
4fa6b5ec | 2461 | audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); |
1da177e4 | 2462 | |
f419a2e3 | 2463 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2464 | if (error) |
2465 | return error; | |
2466 | if (IS_APPEND(dir)) | |
2467 | return -EPERM; | |
b18825a7 DH |
2468 | |
2469 | if (check_sticky(dir, inode) || IS_APPEND(inode) || | |
2470 | IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) | |
1da177e4 LT |
2471 | return -EPERM; |
2472 | if (isdir) { | |
44b1d530 | 2473 | if (!d_is_dir(victim)) |
1da177e4 LT |
2474 | return -ENOTDIR; |
2475 | if (IS_ROOT(victim)) | |
2476 | return -EBUSY; | |
44b1d530 | 2477 | } else if (d_is_dir(victim)) |
1da177e4 LT |
2478 | return -EISDIR; |
2479 | if (IS_DEADDIR(dir)) | |
2480 | return -ENOENT; | |
2481 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) | |
2482 | return -EBUSY; | |
2483 | return 0; | |
2484 | } | |
2485 | ||
2486 | /* Check whether we can create an object with dentry child in directory | |
2487 | * dir. | |
2488 | * 1. We can't do it if child already exists (open has special treatment for | |
2489 | * this case, but since we are inlined it's OK) | |
2490 | * 2. We can't do it if dir is read-only (done in permission()) | |
2491 | * 3. We should have write and exec permissions on dir | |
2492 | * 4. We can't do it if dir is immutable (done in permission()) | |
2493 | */ | |
a95164d9 | 2494 | static inline int may_create(struct inode *dir, struct dentry *child) |
1da177e4 | 2495 | { |
14e972b4 | 2496 | audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); |
1da177e4 LT |
2497 | if (child->d_inode) |
2498 | return -EEXIST; | |
2499 | if (IS_DEADDIR(dir)) | |
2500 | return -ENOENT; | |
f419a2e3 | 2501 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1da177e4 LT |
2502 | } |
2503 | ||
1da177e4 LT |
2504 | /* |
2505 | * p1 and p2 should be directories on the same fs. | |
2506 | */ | |
2507 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) | |
2508 | { | |
2509 | struct dentry *p; | |
2510 | ||
2511 | if (p1 == p2) { | |
f2eace23 | 2512 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1da177e4 LT |
2513 | return NULL; |
2514 | } | |
2515 | ||
a11f3a05 | 2516 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 | 2517 | |
e2761a11 OH |
2518 | p = d_ancestor(p2, p1); |
2519 | if (p) { | |
2520 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); | |
2521 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); | |
2522 | return p; | |
1da177e4 LT |
2523 | } |
2524 | ||
e2761a11 OH |
2525 | p = d_ancestor(p1, p2); |
2526 | if (p) { | |
2527 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); | |
2528 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); | |
2529 | return p; | |
1da177e4 LT |
2530 | } |
2531 | ||
f2eace23 | 2532 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
d1b72cc6 | 2533 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); |
1da177e4 LT |
2534 | return NULL; |
2535 | } | |
4d359507 | 2536 | EXPORT_SYMBOL(lock_rename); |
1da177e4 LT |
2537 | |
2538 | void unlock_rename(struct dentry *p1, struct dentry *p2) | |
2539 | { | |
1b1dcc1b | 2540 | mutex_unlock(&p1->d_inode->i_mutex); |
1da177e4 | 2541 | if (p1 != p2) { |
1b1dcc1b | 2542 | mutex_unlock(&p2->d_inode->i_mutex); |
a11f3a05 | 2543 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1da177e4 LT |
2544 | } |
2545 | } | |
4d359507 | 2546 | EXPORT_SYMBOL(unlock_rename); |
1da177e4 | 2547 | |
4acdaf27 | 2548 | int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
312b63fb | 2549 | bool want_excl) |
1da177e4 | 2550 | { |
a95164d9 | 2551 | int error = may_create(dir, dentry); |
1da177e4 LT |
2552 | if (error) |
2553 | return error; | |
2554 | ||
acfa4380 | 2555 | if (!dir->i_op->create) |
1da177e4 LT |
2556 | return -EACCES; /* shouldn't it be ENOSYS? */ |
2557 | mode &= S_IALLUGO; | |
2558 | mode |= S_IFREG; | |
2559 | error = security_inode_create(dir, dentry, mode); | |
2560 | if (error) | |
2561 | return error; | |
312b63fb | 2562 | error = dir->i_op->create(dir, dentry, mode, want_excl); |
a74574aa | 2563 | if (!error) |
f38aa942 | 2564 | fsnotify_create(dir, dentry); |
1da177e4 LT |
2565 | return error; |
2566 | } | |
4d359507 | 2567 | EXPORT_SYMBOL(vfs_create); |
1da177e4 | 2568 | |
73d049a4 | 2569 | static int may_open(struct path *path, int acc_mode, int flag) |
1da177e4 | 2570 | { |
3fb64190 | 2571 | struct dentry *dentry = path->dentry; |
1da177e4 LT |
2572 | struct inode *inode = dentry->d_inode; |
2573 | int error; | |
2574 | ||
bcda7652 AV |
2575 | /* O_PATH? */ |
2576 | if (!acc_mode) | |
2577 | return 0; | |
2578 | ||
1da177e4 LT |
2579 | if (!inode) |
2580 | return -ENOENT; | |
2581 | ||
c8fe8f30 CH |
2582 | switch (inode->i_mode & S_IFMT) { |
2583 | case S_IFLNK: | |
1da177e4 | 2584 | return -ELOOP; |
c8fe8f30 CH |
2585 | case S_IFDIR: |
2586 | if (acc_mode & MAY_WRITE) | |
2587 | return -EISDIR; | |
2588 | break; | |
2589 | case S_IFBLK: | |
2590 | case S_IFCHR: | |
3fb64190 | 2591 | if (path->mnt->mnt_flags & MNT_NODEV) |
1da177e4 | 2592 | return -EACCES; |
c8fe8f30 CH |
2593 | /*FALLTHRU*/ |
2594 | case S_IFIFO: | |
2595 | case S_IFSOCK: | |
1da177e4 | 2596 | flag &= ~O_TRUNC; |
c8fe8f30 | 2597 | break; |
4a3fd211 | 2598 | } |
b41572e9 | 2599 | |
3fb64190 | 2600 | error = inode_permission(inode, acc_mode); |
b41572e9 DH |
2601 | if (error) |
2602 | return error; | |
6146f0d5 | 2603 | |
1da177e4 LT |
2604 | /* |
2605 | * An append-only file must be opened in append mode for writing. | |
2606 | */ | |
2607 | if (IS_APPEND(inode)) { | |
8737c930 | 2608 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
7715b521 | 2609 | return -EPERM; |
1da177e4 | 2610 | if (flag & O_TRUNC) |
7715b521 | 2611 | return -EPERM; |
1da177e4 LT |
2612 | } |
2613 | ||
2614 | /* O_NOATIME can only be set by the owner or superuser */ | |
2e149670 | 2615 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
7715b521 | 2616 | return -EPERM; |
1da177e4 | 2617 | |
f3c7691e | 2618 | return 0; |
7715b521 | 2619 | } |
1da177e4 | 2620 | |
e1181ee6 | 2621 | static int handle_truncate(struct file *filp) |
7715b521 | 2622 | { |
e1181ee6 | 2623 | struct path *path = &filp->f_path; |
7715b521 AV |
2624 | struct inode *inode = path->dentry->d_inode; |
2625 | int error = get_write_access(inode); | |
2626 | if (error) | |
2627 | return error; | |
2628 | /* | |
2629 | * Refuse to truncate files with mandatory locks held on them. | |
2630 | */ | |
d7a06983 | 2631 | error = locks_verify_locked(filp); |
7715b521 | 2632 | if (!error) |
ea0d3ab2 | 2633 | error = security_path_truncate(path); |
7715b521 AV |
2634 | if (!error) { |
2635 | error = do_truncate(path->dentry, 0, | |
2636 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, | |
e1181ee6 | 2637 | filp); |
7715b521 AV |
2638 | } |
2639 | put_write_access(inode); | |
acd0c935 | 2640 | return error; |
1da177e4 LT |
2641 | } |
2642 | ||
d57999e1 DH |
2643 | static inline int open_to_namei_flags(int flag) |
2644 | { | |
8a5e929d AV |
2645 | if ((flag & O_ACCMODE) == 3) |
2646 | flag--; | |
d57999e1 DH |
2647 | return flag; |
2648 | } | |
2649 | ||
d18e9008 MS |
2650 | static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) |
2651 | { | |
2652 | int error = security_path_mknod(dir, dentry, mode, 0); | |
2653 | if (error) | |
2654 | return error; | |
2655 | ||
2656 | error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); | |
2657 | if (error) | |
2658 | return error; | |
2659 | ||
2660 | return security_inode_create(dir->dentry->d_inode, dentry, mode); | |
2661 | } | |
2662 | ||
1acf0af9 DH |
2663 | /* |
2664 | * Attempt to atomically look up, create and open a file from a negative | |
2665 | * dentry. | |
2666 | * | |
2667 | * Returns 0 if successful. The file will have been created and attached to | |
2668 | * @file by the filesystem calling finish_open(). | |
2669 | * | |
2670 | * Returns 1 if the file was looked up only or didn't need creating. The | |
2671 | * caller will need to perform the open themselves. @path will have been | |
2672 | * updated to point to the new dentry. This may be negative. | |
2673 | * | |
2674 | * Returns an error code otherwise. | |
2675 | */ | |
2675a4eb AV |
2676 | static int atomic_open(struct nameidata *nd, struct dentry *dentry, |
2677 | struct path *path, struct file *file, | |
2678 | const struct open_flags *op, | |
64894cf8 | 2679 | bool got_write, bool need_lookup, |
2675a4eb | 2680 | int *opened) |
d18e9008 MS |
2681 | { |
2682 | struct inode *dir = nd->path.dentry->d_inode; | |
2683 | unsigned open_flag = open_to_namei_flags(op->open_flag); | |
2684 | umode_t mode; | |
2685 | int error; | |
2686 | int acc_mode; | |
d18e9008 MS |
2687 | int create_error = 0; |
2688 | struct dentry *const DENTRY_NOT_SET = (void *) -1UL; | |
116cc022 | 2689 | bool excl; |
d18e9008 MS |
2690 | |
2691 | BUG_ON(dentry->d_inode); | |
2692 | ||
2693 | /* Don't create child dentry for a dead directory. */ | |
2694 | if (unlikely(IS_DEADDIR(dir))) { | |
2675a4eb | 2695 | error = -ENOENT; |
d18e9008 MS |
2696 | goto out; |
2697 | } | |
2698 | ||
62b259d8 | 2699 | mode = op->mode; |
d18e9008 MS |
2700 | if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) |
2701 | mode &= ~current_umask(); | |
2702 | ||
116cc022 MS |
2703 | excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); |
2704 | if (excl) | |
d18e9008 | 2705 | open_flag &= ~O_TRUNC; |
d18e9008 MS |
2706 | |
2707 | /* | |
2708 | * Checking write permission is tricky, bacuse we don't know if we are | |
2709 | * going to actually need it: O_CREAT opens should work as long as the | |
2710 | * file exists. But checking existence breaks atomicity. The trick is | |
2711 | * to check access and if not granted clear O_CREAT from the flags. | |
2712 | * | |
2713 | * Another problem is returing the "right" error value (e.g. for an | |
2714 | * O_EXCL open we want to return EEXIST not EROFS). | |
2715 | */ | |
64894cf8 AV |
2716 | if (((open_flag & (O_CREAT | O_TRUNC)) || |
2717 | (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { | |
2718 | if (!(open_flag & O_CREAT)) { | |
d18e9008 MS |
2719 | /* |
2720 | * No O_CREATE -> atomicity not a requirement -> fall | |
2721 | * back to lookup + open | |
2722 | */ | |
2723 | goto no_open; | |
2724 | } else if (open_flag & (O_EXCL | O_TRUNC)) { | |
2725 | /* Fall back and fail with the right error */ | |
64894cf8 | 2726 | create_error = -EROFS; |
d18e9008 MS |
2727 | goto no_open; |
2728 | } else { | |
2729 | /* No side effects, safe to clear O_CREAT */ | |
64894cf8 | 2730 | create_error = -EROFS; |
d18e9008 MS |
2731 | open_flag &= ~O_CREAT; |
2732 | } | |
2733 | } | |
2734 | ||
2735 | if (open_flag & O_CREAT) { | |
38227f78 | 2736 | error = may_o_create(&nd->path, dentry, mode); |
d18e9008 MS |
2737 | if (error) { |
2738 | create_error = error; | |
2739 | if (open_flag & O_EXCL) | |
2740 | goto no_open; | |
2741 | open_flag &= ~O_CREAT; | |
2742 | } | |
2743 | } | |
2744 | ||
2745 | if (nd->flags & LOOKUP_DIRECTORY) | |
2746 | open_flag |= O_DIRECTORY; | |
2747 | ||
30d90494 AV |
2748 | file->f_path.dentry = DENTRY_NOT_SET; |
2749 | file->f_path.mnt = nd->path.mnt; | |
2750 | error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, | |
47237687 | 2751 | opened); |
d9585277 | 2752 | if (error < 0) { |
d9585277 AV |
2753 | if (create_error && error == -ENOENT) |
2754 | error = create_error; | |
d18e9008 MS |
2755 | goto out; |
2756 | } | |
2757 | ||
d9585277 | 2758 | if (error) { /* returned 1, that is */ |
30d90494 | 2759 | if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { |
2675a4eb | 2760 | error = -EIO; |
d18e9008 MS |
2761 | goto out; |
2762 | } | |
30d90494 | 2763 | if (file->f_path.dentry) { |
d18e9008 | 2764 | dput(dentry); |
30d90494 | 2765 | dentry = file->f_path.dentry; |
d18e9008 | 2766 | } |
03da633a AV |
2767 | if (*opened & FILE_CREATED) |
2768 | fsnotify_create(dir, dentry); | |
2769 | if (!dentry->d_inode) { | |
2770 | WARN_ON(*opened & FILE_CREATED); | |
2771 | if (create_error) { | |
2772 | error = create_error; | |
2773 | goto out; | |
2774 | } | |
2775 | } else { | |
2776 | if (excl && !(*opened & FILE_CREATED)) { | |
2777 | error = -EEXIST; | |
2778 | goto out; | |
2779 | } | |
62b2ce96 | 2780 | } |
d18e9008 MS |
2781 | goto looked_up; |
2782 | } | |
2783 | ||
2784 | /* | |
2785 | * We didn't have the inode before the open, so check open permission | |
2786 | * here. | |
2787 | */ | |
03da633a AV |
2788 | acc_mode = op->acc_mode; |
2789 | if (*opened & FILE_CREATED) { | |
2790 | WARN_ON(!(open_flag & O_CREAT)); | |
2791 | fsnotify_create(dir, dentry); | |
2792 | acc_mode = MAY_OPEN; | |
2793 | } | |
2675a4eb AV |
2794 | error = may_open(&file->f_path, acc_mode, open_flag); |
2795 | if (error) | |
2796 | fput(file); | |
d18e9008 MS |
2797 | |
2798 | out: | |
2799 | dput(dentry); | |
2675a4eb | 2800 | return error; |
d18e9008 | 2801 | |
d18e9008 MS |
2802 | no_open: |
2803 | if (need_lookup) { | |
72bd866a | 2804 | dentry = lookup_real(dir, dentry, nd->flags); |
d18e9008 | 2805 | if (IS_ERR(dentry)) |
2675a4eb | 2806 | return PTR_ERR(dentry); |
d18e9008 MS |
2807 | |
2808 | if (create_error) { | |
2809 | int open_flag = op->open_flag; | |
2810 | ||
2675a4eb | 2811 | error = create_error; |
d18e9008 MS |
2812 | if ((open_flag & O_EXCL)) { |
2813 | if (!dentry->d_inode) | |
2814 | goto out; | |
2815 | } else if (!dentry->d_inode) { | |
2816 | goto out; | |
2817 | } else if ((open_flag & O_TRUNC) && | |
e36cb0b8 | 2818 | d_is_reg(dentry)) { |
d18e9008 MS |
2819 | goto out; |
2820 | } | |
2821 | /* will fail later, go on to get the right error */ | |
2822 | } | |
2823 | } | |
2824 | looked_up: | |
2825 | path->dentry = dentry; | |
2826 | path->mnt = nd->path.mnt; | |
2675a4eb | 2827 | return 1; |
d18e9008 MS |
2828 | } |
2829 | ||
d58ffd35 | 2830 | /* |
1acf0af9 | 2831 | * Look up and maybe create and open the last component. |
d58ffd35 MS |
2832 | * |
2833 | * Must be called with i_mutex held on parent. | |
2834 | * | |
1acf0af9 DH |
2835 | * Returns 0 if the file was successfully atomically created (if necessary) and |
2836 | * opened. In this case the file will be returned attached to @file. | |
2837 | * | |
2838 | * Returns 1 if the file was not completely opened at this time, though lookups | |
2839 | * and creations will have been performed and the dentry returned in @path will | |
2840 | * be positive upon return if O_CREAT was specified. If O_CREAT wasn't | |
2841 | * specified then a negative dentry may be returned. | |
2842 | * | |
2843 | * An error code is returned otherwise. | |
2844 | * | |
2845 | * FILE_CREATE will be set in @*opened if the dentry was created and will be | |
2846 | * cleared otherwise prior to returning. | |
d58ffd35 | 2847 | */ |
2675a4eb AV |
2848 | static int lookup_open(struct nameidata *nd, struct path *path, |
2849 | struct file *file, | |
2850 | const struct open_flags *op, | |
64894cf8 | 2851 | bool got_write, int *opened) |
d58ffd35 MS |
2852 | { |
2853 | struct dentry *dir = nd->path.dentry; | |
54ef4872 | 2854 | struct inode *dir_inode = dir->d_inode; |
d58ffd35 MS |
2855 | struct dentry *dentry; |
2856 | int error; | |
54ef4872 | 2857 | bool need_lookup; |
d58ffd35 | 2858 | |
47237687 | 2859 | *opened &= ~FILE_CREATED; |
201f956e | 2860 | dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); |
d58ffd35 | 2861 | if (IS_ERR(dentry)) |
2675a4eb | 2862 | return PTR_ERR(dentry); |
d58ffd35 | 2863 | |
d18e9008 MS |
2864 | /* Cached positive dentry: will open in f_op->open */ |
2865 | if (!need_lookup && dentry->d_inode) | |
2866 | goto out_no_open; | |
2867 | ||
2868 | if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { | |
64894cf8 | 2869 | return atomic_open(nd, dentry, path, file, op, got_write, |
47237687 | 2870 | need_lookup, opened); |
d18e9008 MS |
2871 | } |
2872 | ||
54ef4872 MS |
2873 | if (need_lookup) { |
2874 | BUG_ON(dentry->d_inode); | |
2875 | ||
72bd866a | 2876 | dentry = lookup_real(dir_inode, dentry, nd->flags); |
54ef4872 | 2877 | if (IS_ERR(dentry)) |
2675a4eb | 2878 | return PTR_ERR(dentry); |
54ef4872 MS |
2879 | } |
2880 | ||
d58ffd35 MS |
2881 | /* Negative dentry, just create the file */ |
2882 | if (!dentry->d_inode && (op->open_flag & O_CREAT)) { | |
2883 | umode_t mode = op->mode; | |
2884 | if (!IS_POSIXACL(dir->d_inode)) | |
2885 | mode &= ~current_umask(); | |
2886 | /* | |
2887 | * This write is needed to ensure that a | |
2888 | * rw->ro transition does not occur between | |
2889 | * the time when the file is created and when | |
2890 | * a permanent write count is taken through | |
015c3bbc | 2891 | * the 'struct file' in finish_open(). |
d58ffd35 | 2892 | */ |
64894cf8 AV |
2893 | if (!got_write) { |
2894 | error = -EROFS; | |
d58ffd35 | 2895 | goto out_dput; |
64894cf8 | 2896 | } |
47237687 | 2897 | *opened |= FILE_CREATED; |
d58ffd35 MS |
2898 | error = security_path_mknod(&nd->path, dentry, mode, 0); |
2899 | if (error) | |
2900 | goto out_dput; | |
312b63fb AV |
2901 | error = vfs_create(dir->d_inode, dentry, mode, |
2902 | nd->flags & LOOKUP_EXCL); | |
d58ffd35 MS |
2903 | if (error) |
2904 | goto out_dput; | |
2905 | } | |
d18e9008 | 2906 | out_no_open: |
d58ffd35 MS |
2907 | path->dentry = dentry; |
2908 | path->mnt = nd->path.mnt; | |
2675a4eb | 2909 | return 1; |
d58ffd35 MS |
2910 | |
2911 | out_dput: | |
2912 | dput(dentry); | |
2675a4eb | 2913 | return error; |
d58ffd35 MS |
2914 | } |
2915 | ||
31e6b01f | 2916 | /* |
fe2d35ff | 2917 | * Handle the last step of open() |
31e6b01f | 2918 | */ |
896475d5 | 2919 | static int do_last(struct nameidata *nd, |
2675a4eb | 2920 | struct file *file, const struct open_flags *op, |
669abf4e | 2921 | int *opened, struct filename *name) |
fb1cc555 | 2922 | { |
a1e28038 | 2923 | struct dentry *dir = nd->path.dentry; |
ca344a89 | 2924 | int open_flag = op->open_flag; |
77d660a8 | 2925 | bool will_truncate = (open_flag & O_TRUNC) != 0; |
64894cf8 | 2926 | bool got_write = false; |
bcda7652 | 2927 | int acc_mode = op->acc_mode; |
a1eb3315 | 2928 | struct inode *inode; |
16b1c1cd | 2929 | struct path save_parent = { .dentry = NULL, .mnt = NULL }; |
896475d5 | 2930 | struct path path; |
16b1c1cd | 2931 | bool retried = false; |
16c2cd71 | 2932 | int error; |
1f36f774 | 2933 | |
c3e380b0 AV |
2934 | nd->flags &= ~LOOKUP_PARENT; |
2935 | nd->flags |= op->intent; | |
2936 | ||
bc77daa7 | 2937 | if (nd->last_type != LAST_NORM) { |
fe2d35ff AV |
2938 | error = handle_dots(nd, nd->last_type); |
2939 | if (error) | |
2675a4eb | 2940 | return error; |
e83db167 | 2941 | goto finish_open; |
1f36f774 | 2942 | } |
67ee3ad2 | 2943 | |
ca344a89 | 2944 | if (!(open_flag & O_CREAT)) { |
fe2d35ff AV |
2945 | if (nd->last.name[nd->last.len]) |
2946 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; | |
2947 | /* we _can_ be in RCU mode here */ | |
896475d5 | 2948 | error = lookup_fast(nd, &path, &inode); |
71574865 MS |
2949 | if (likely(!error)) |
2950 | goto finish_lookup; | |
2951 | ||
2952 | if (error < 0) | |
2675a4eb | 2953 | goto out; |
71574865 MS |
2954 | |
2955 | BUG_ON(nd->inode != dir->d_inode); | |
b6183df7 MS |
2956 | } else { |
2957 | /* create side of things */ | |
2958 | /* | |
2959 | * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED | |
2960 | * has been cleared when we got to the last component we are | |
2961 | * about to look up | |
2962 | */ | |
2963 | error = complete_walk(nd); | |
2964 | if (error) | |
2675a4eb | 2965 | return error; |
fe2d35ff | 2966 | |
33e2208a | 2967 | audit_inode(name, dir, LOOKUP_PARENT); |
b6183df7 MS |
2968 | error = -EISDIR; |
2969 | /* trailing slashes? */ | |
2970 | if (nd->last.name[nd->last.len]) | |
2675a4eb | 2971 | goto out; |
b6183df7 | 2972 | } |
a2c36b45 | 2973 | |
16b1c1cd | 2974 | retry_lookup: |
64894cf8 AV |
2975 | if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { |
2976 | error = mnt_want_write(nd->path.mnt); | |
2977 | if (!error) | |
2978 | got_write = true; | |
2979 | /* | |
2980 | * do _not_ fail yet - we might not need that or fail with | |
2981 | * a different error; let lookup_open() decide; we'll be | |
2982 | * dropping this one anyway. | |
2983 | */ | |
2984 | } | |
a1e28038 | 2985 | mutex_lock(&dir->d_inode->i_mutex); |
896475d5 | 2986 | error = lookup_open(nd, &path, file, op, got_write, opened); |
d58ffd35 | 2987 | mutex_unlock(&dir->d_inode->i_mutex); |
a1e28038 | 2988 | |
2675a4eb AV |
2989 | if (error <= 0) { |
2990 | if (error) | |
d18e9008 MS |
2991 | goto out; |
2992 | ||
47237687 | 2993 | if ((*opened & FILE_CREATED) || |
496ad9aa | 2994 | !S_ISREG(file_inode(file)->i_mode)) |
77d660a8 | 2995 | will_truncate = false; |
d18e9008 | 2996 | |
adb5c247 | 2997 | audit_inode(name, file->f_path.dentry, 0); |
d18e9008 MS |
2998 | goto opened; |
2999 | } | |
fb1cc555 | 3000 | |
47237687 | 3001 | if (*opened & FILE_CREATED) { |
9b44f1b3 | 3002 | /* Don't check for write permission, don't truncate */ |
ca344a89 | 3003 | open_flag &= ~O_TRUNC; |
77d660a8 | 3004 | will_truncate = false; |
bcda7652 | 3005 | acc_mode = MAY_OPEN; |
896475d5 | 3006 | path_to_nameidata(&path, nd); |
e83db167 | 3007 | goto finish_open_created; |
fb1cc555 AV |
3008 | } |
3009 | ||
3010 | /* | |
3134f37e | 3011 | * create/update audit record if it already exists. |
fb1cc555 | 3012 | */ |
896475d5 AV |
3013 | if (d_is_positive(path.dentry)) |
3014 | audit_inode(name, path.dentry, 0); | |
fb1cc555 | 3015 | |
d18e9008 MS |
3016 | /* |
3017 | * If atomic_open() acquired write access it is dropped now due to | |
3018 | * possible mount and symlink following (this might be optimized away if | |
3019 | * necessary...) | |
3020 | */ | |
64894cf8 | 3021 | if (got_write) { |
d18e9008 | 3022 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 3023 | got_write = false; |
d18e9008 MS |
3024 | } |
3025 | ||
fb1cc555 | 3026 | error = -EEXIST; |
f8310c59 | 3027 | if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) |
fb1cc555 AV |
3028 | goto exit_dput; |
3029 | ||
896475d5 | 3030 | error = follow_managed(&path, nd->flags); |
9875cf80 DH |
3031 | if (error < 0) |
3032 | goto exit_dput; | |
fb1cc555 | 3033 | |
a3fbbde7 AV |
3034 | if (error) |
3035 | nd->flags |= LOOKUP_JUMPED; | |
3036 | ||
decf3400 | 3037 | BUG_ON(nd->flags & LOOKUP_RCU); |
896475d5 | 3038 | inode = path.dentry->d_inode; |
fb1cc555 | 3039 | error = -ENOENT; |
896475d5 AV |
3040 | if (d_is_negative(path.dentry)) { |
3041 | path_to_nameidata(&path, nd); | |
2675a4eb | 3042 | goto out; |
54c33e7f | 3043 | } |
766c4cbf | 3044 | finish_lookup: |
896475d5 | 3045 | if (should_follow_link(path.dentry, nd->flags & LOOKUP_FOLLOW)) { |
d45ea867 | 3046 | if (nd->flags & LOOKUP_RCU) { |
896475d5 AV |
3047 | if (unlikely(nd->path.mnt != path.mnt || |
3048 | unlazy_walk(nd, path.dentry))) { | |
d45ea867 | 3049 | error = -ECHILD; |
2675a4eb | 3050 | goto out; |
d45ea867 MS |
3051 | } |
3052 | } | |
896475d5 AV |
3053 | BUG_ON(inode != path.dentry->d_inode); |
3054 | nd->link = path; | |
2675a4eb | 3055 | return 1; |
d45ea867 | 3056 | } |
fb1cc555 | 3057 | |
896475d5 AV |
3058 | if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { |
3059 | path_to_nameidata(&path, nd); | |
a5cfe2d5 AV |
3060 | error = -ELOOP; |
3061 | goto out; | |
3062 | } | |
3063 | ||
896475d5 AV |
3064 | if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { |
3065 | path_to_nameidata(&path, nd); | |
16b1c1cd MS |
3066 | } else { |
3067 | save_parent.dentry = nd->path.dentry; | |
896475d5 AV |
3068 | save_parent.mnt = mntget(path.mnt); |
3069 | nd->path.dentry = path.dentry; | |
16b1c1cd MS |
3070 | |
3071 | } | |
decf3400 | 3072 | nd->inode = inode; |
a3fbbde7 | 3073 | /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ |
bc77daa7 | 3074 | finish_open: |
a3fbbde7 | 3075 | error = complete_walk(nd); |
16b1c1cd MS |
3076 | if (error) { |
3077 | path_put(&save_parent); | |
2675a4eb | 3078 | return error; |
16b1c1cd | 3079 | } |
bc77daa7 | 3080 | audit_inode(name, nd->path.dentry, 0); |
fb1cc555 | 3081 | error = -EISDIR; |
44b1d530 | 3082 | if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) |
2675a4eb | 3083 | goto out; |
af2f5542 | 3084 | error = -ENOTDIR; |
44b1d530 | 3085 | if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) |
2675a4eb | 3086 | goto out; |
4bbcbd3b | 3087 | if (!d_is_reg(nd->path.dentry)) |
77d660a8 | 3088 | will_truncate = false; |
6c0d46c4 | 3089 | |
0f9d1a10 AV |
3090 | if (will_truncate) { |
3091 | error = mnt_want_write(nd->path.mnt); | |
3092 | if (error) | |
2675a4eb | 3093 | goto out; |
64894cf8 | 3094 | got_write = true; |
0f9d1a10 | 3095 | } |
e83db167 | 3096 | finish_open_created: |
bcda7652 | 3097 | error = may_open(&nd->path, acc_mode, open_flag); |
ca344a89 | 3098 | if (error) |
2675a4eb | 3099 | goto out; |
4aa7c634 MS |
3100 | |
3101 | BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ | |
3102 | error = vfs_open(&nd->path, file, current_cred()); | |
3103 | if (!error) { | |
3104 | *opened |= FILE_OPENED; | |
3105 | } else { | |
30d90494 | 3106 | if (error == -EOPENSTALE) |
f60dc3db | 3107 | goto stale_open; |
015c3bbc | 3108 | goto out; |
f60dc3db | 3109 | } |
a8277b9b | 3110 | opened: |
2675a4eb | 3111 | error = open_check_o_direct(file); |
015c3bbc MS |
3112 | if (error) |
3113 | goto exit_fput; | |
3034a146 | 3114 | error = ima_file_check(file, op->acc_mode, *opened); |
aa4caadb MS |
3115 | if (error) |
3116 | goto exit_fput; | |
3117 | ||
3118 | if (will_truncate) { | |
2675a4eb | 3119 | error = handle_truncate(file); |
aa4caadb MS |
3120 | if (error) |
3121 | goto exit_fput; | |
0f9d1a10 | 3122 | } |
ca344a89 | 3123 | out: |
64894cf8 | 3124 | if (got_write) |
0f9d1a10 | 3125 | mnt_drop_write(nd->path.mnt); |
16b1c1cd | 3126 | path_put(&save_parent); |
e276ae67 | 3127 | terminate_walk(nd); |
2675a4eb | 3128 | return error; |
fb1cc555 | 3129 | |
fb1cc555 | 3130 | exit_dput: |
896475d5 | 3131 | path_put_conditional(&path, nd); |
ca344a89 | 3132 | goto out; |
015c3bbc | 3133 | exit_fput: |
2675a4eb AV |
3134 | fput(file); |
3135 | goto out; | |
015c3bbc | 3136 | |
f60dc3db MS |
3137 | stale_open: |
3138 | /* If no saved parent or already retried then can't retry */ | |
3139 | if (!save_parent.dentry || retried) | |
3140 | goto out; | |
3141 | ||
3142 | BUG_ON(save_parent.dentry != dir); | |
3143 | path_put(&nd->path); | |
3144 | nd->path = save_parent; | |
3145 | nd->inode = dir->d_inode; | |
3146 | save_parent.mnt = NULL; | |
3147 | save_parent.dentry = NULL; | |
64894cf8 | 3148 | if (got_write) { |
f60dc3db | 3149 | mnt_drop_write(nd->path.mnt); |
64894cf8 | 3150 | got_write = false; |
f60dc3db MS |
3151 | } |
3152 | retried = true; | |
3153 | goto retry_lookup; | |
fb1cc555 AV |
3154 | } |
3155 | ||
60545d0d AV |
3156 | static int do_tmpfile(int dfd, struct filename *pathname, |
3157 | struct nameidata *nd, int flags, | |
3158 | const struct open_flags *op, | |
3159 | struct file *file, int *opened) | |
3160 | { | |
3161 | static const struct qstr name = QSTR_INIT("/", 1); | |
3162 | struct dentry *dentry, *child; | |
3163 | struct inode *dir; | |
5eb6b495 | 3164 | int error = path_lookupat(dfd, pathname, |
60545d0d AV |
3165 | flags | LOOKUP_DIRECTORY, nd); |
3166 | if (unlikely(error)) | |
3167 | return error; | |
3168 | error = mnt_want_write(nd->path.mnt); | |
3169 | if (unlikely(error)) | |
3170 | goto out; | |
3171 | /* we want directory to be writable */ | |
3172 | error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); | |
3173 | if (error) | |
3174 | goto out2; | |
3175 | dentry = nd->path.dentry; | |
3176 | dir = dentry->d_inode; | |
3177 | if (!dir->i_op->tmpfile) { | |
3178 | error = -EOPNOTSUPP; | |
3179 | goto out2; | |
3180 | } | |
3181 | child = d_alloc(dentry, &name); | |
3182 | if (unlikely(!child)) { | |
3183 | error = -ENOMEM; | |
3184 | goto out2; | |
3185 | } | |
3186 | nd->flags &= ~LOOKUP_DIRECTORY; | |
3187 | nd->flags |= op->intent; | |
3188 | dput(nd->path.dentry); | |
3189 | nd->path.dentry = child; | |
3190 | error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); | |
3191 | if (error) | |
3192 | goto out2; | |
3193 | audit_inode(pathname, nd->path.dentry, 0); | |
69a91c23 ER |
3194 | /* Don't check for other permissions, the inode was just created */ |
3195 | error = may_open(&nd->path, MAY_OPEN, op->open_flag); | |
60545d0d AV |
3196 | if (error) |
3197 | goto out2; | |
3198 | file->f_path.mnt = nd->path.mnt; | |
3199 | error = finish_open(file, nd->path.dentry, NULL, opened); | |
3200 | if (error) | |
3201 | goto out2; | |
3202 | error = open_check_o_direct(file); | |
f4e0c30c | 3203 | if (error) { |
60545d0d | 3204 | fput(file); |
f4e0c30c AV |
3205 | } else if (!(op->open_flag & O_EXCL)) { |
3206 | struct inode *inode = file_inode(file); | |
3207 | spin_lock(&inode->i_lock); | |
3208 | inode->i_state |= I_LINKABLE; | |
3209 | spin_unlock(&inode->i_lock); | |
3210 | } | |
60545d0d AV |
3211 | out2: |
3212 | mnt_drop_write(nd->path.mnt); | |
3213 | out: | |
3214 | path_put(&nd->path); | |
3215 | return error; | |
3216 | } | |
3217 | ||
669abf4e | 3218 | static struct file *path_openat(int dfd, struct filename *pathname, |
73d049a4 | 3219 | struct nameidata *nd, const struct open_flags *op, int flags) |
1da177e4 | 3220 | { |
30d90494 | 3221 | struct file *file; |
47237687 | 3222 | int opened = 0; |
13aab428 | 3223 | int error; |
31e6b01f | 3224 | |
30d90494 | 3225 | file = get_empty_filp(); |
1afc99be AV |
3226 | if (IS_ERR(file)) |
3227 | return file; | |
31e6b01f | 3228 | |
30d90494 | 3229 | file->f_flags = op->open_flag; |
31e6b01f | 3230 | |
bb458c64 | 3231 | if (unlikely(file->f_flags & __O_TMPFILE)) { |
60545d0d | 3232 | error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); |
f15133df | 3233 | goto out2; |
60545d0d AV |
3234 | } |
3235 | ||
6e8a1f87 | 3236 | error = path_init(dfd, pathname, flags, nd); |
31e6b01f | 3237 | if (unlikely(error)) |
2675a4eb | 3238 | goto out; |
1da177e4 | 3239 | |
896475d5 | 3240 | error = do_last(nd, file, op, &opened, pathname); |
2675a4eb | 3241 | while (unlikely(error > 0)) { /* trailing symlink */ |
caa85634 | 3242 | struct path link = nd->link; |
def4af30 | 3243 | void *cookie; |
73d049a4 | 3244 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); |
95fa25d9 | 3245 | error = trailing_symlink(&link, nd, &cookie); |
c3e380b0 | 3246 | if (unlikely(error)) |
2675a4eb | 3247 | break; |
896475d5 | 3248 | error = do_last(nd, file, op, &opened, pathname); |
574197e0 | 3249 | put_link(nd, &link, cookie); |
806b681c | 3250 | } |
10fa8e62 | 3251 | out: |
893b7775 | 3252 | path_cleanup(nd); |
f15133df | 3253 | out2: |
2675a4eb AV |
3254 | if (!(opened & FILE_OPENED)) { |
3255 | BUG_ON(!error); | |
30d90494 | 3256 | put_filp(file); |
16b1c1cd | 3257 | } |
2675a4eb AV |
3258 | if (unlikely(error)) { |
3259 | if (error == -EOPENSTALE) { | |
3260 | if (flags & LOOKUP_RCU) | |
3261 | error = -ECHILD; | |
3262 | else | |
3263 | error = -ESTALE; | |
3264 | } | |
3265 | file = ERR_PTR(error); | |
3266 | } | |
3267 | return file; | |
1da177e4 LT |
3268 | } |
3269 | ||
669abf4e | 3270 | struct file *do_filp_open(int dfd, struct filename *pathname, |
f9652e10 | 3271 | const struct open_flags *op) |
13aab428 | 3272 | { |
73d049a4 | 3273 | struct nameidata nd; |
f9652e10 | 3274 | int flags = op->lookup_flags; |
13aab428 AV |
3275 | struct file *filp; |
3276 | ||
73d049a4 | 3277 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); |
13aab428 | 3278 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
73d049a4 | 3279 | filp = path_openat(dfd, pathname, &nd, op, flags); |
13aab428 | 3280 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
73d049a4 | 3281 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); |
13aab428 AV |
3282 | return filp; |
3283 | } | |
3284 | ||
73d049a4 | 3285 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
f9652e10 | 3286 | const char *name, const struct open_flags *op) |
73d049a4 AV |
3287 | { |
3288 | struct nameidata nd; | |
3289 | struct file *file; | |
51689104 | 3290 | struct filename *filename; |
f9652e10 | 3291 | int flags = op->lookup_flags | LOOKUP_ROOT; |
73d049a4 AV |
3292 | |
3293 | nd.root.mnt = mnt; | |
3294 | nd.root.dentry = dentry; | |
3295 | ||
b18825a7 | 3296 | if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) |
73d049a4 AV |
3297 | return ERR_PTR(-ELOOP); |
3298 | ||
51689104 PM |
3299 | filename = getname_kernel(name); |
3300 | if (unlikely(IS_ERR(filename))) | |
3301 | return ERR_CAST(filename); | |
3302 | ||
3303 | file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); | |
73d049a4 | 3304 | if (unlikely(file == ERR_PTR(-ECHILD))) |
51689104 | 3305 | file = path_openat(-1, filename, &nd, op, flags); |
73d049a4 | 3306 | if (unlikely(file == ERR_PTR(-ESTALE))) |
51689104 PM |
3307 | file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); |
3308 | putname(filename); | |
73d049a4 AV |
3309 | return file; |
3310 | } | |
3311 | ||
fa14a0b8 | 3312 | static struct dentry *filename_create(int dfd, struct filename *name, |
1ac12b4b | 3313 | struct path *path, unsigned int lookup_flags) |
1da177e4 | 3314 | { |
c663e5d8 | 3315 | struct dentry *dentry = ERR_PTR(-EEXIST); |
ed75e95d | 3316 | struct nameidata nd; |
c30dabfe | 3317 | int err2; |
1ac12b4b JL |
3318 | int error; |
3319 | bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); | |
3320 | ||
3321 | /* | |
3322 | * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any | |
3323 | * other flags passed in are ignored! | |
3324 | */ | |
3325 | lookup_flags &= LOOKUP_REVAL; | |
3326 | ||
fa14a0b8 | 3327 | error = filename_lookup(dfd, name, LOOKUP_PARENT|lookup_flags, &nd); |
ed75e95d AV |
3328 | if (error) |
3329 | return ERR_PTR(error); | |
1da177e4 | 3330 | |
c663e5d8 CH |
3331 | /* |
3332 | * Yucky last component or no last component at all? | |
3333 | * (foo/., foo/.., /////) | |
3334 | */ | |
ed75e95d AV |
3335 | if (nd.last_type != LAST_NORM) |
3336 | goto out; | |
3337 | nd.flags &= ~LOOKUP_PARENT; | |
3338 | nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; | |
c663e5d8 | 3339 | |
c30dabfe JK |
3340 | /* don't fail immediately if it's r/o, at least try to report other errors */ |
3341 | err2 = mnt_want_write(nd.path.mnt); | |
c663e5d8 CH |
3342 | /* |
3343 | * Do the final lookup. | |
3344 | */ | |
ed75e95d | 3345 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
6a9f40d6 | 3346 | dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); |
1da177e4 | 3347 | if (IS_ERR(dentry)) |
a8104a9f | 3348 | goto unlock; |
c663e5d8 | 3349 | |
a8104a9f | 3350 | error = -EEXIST; |
b18825a7 | 3351 | if (d_is_positive(dentry)) |
a8104a9f | 3352 | goto fail; |
b18825a7 | 3353 | |
c663e5d8 CH |
3354 | /* |
3355 | * Special case - lookup gave negative, but... we had foo/bar/ | |
3356 | * From the vfs_mknod() POV we just have a negative dentry - | |
3357 | * all is fine. Let's be bastards - you had / on the end, you've | |
3358 | * been asking for (non-existent) directory. -ENOENT for you. | |
3359 | */ | |
ed75e95d | 3360 | if (unlikely(!is_dir && nd.last.name[nd.last.len])) { |
a8104a9f | 3361 | error = -ENOENT; |
ed75e95d | 3362 | goto fail; |
e9baf6e5 | 3363 | } |
c30dabfe JK |
3364 | if (unlikely(err2)) { |
3365 | error = err2; | |
a8104a9f | 3366 | goto fail; |
c30dabfe | 3367 | } |
ed75e95d | 3368 | *path = nd.path; |
1da177e4 | 3369 | return dentry; |
1da177e4 | 3370 | fail: |
a8104a9f AV |
3371 | dput(dentry); |
3372 | dentry = ERR_PTR(error); | |
3373 | unlock: | |
ed75e95d | 3374 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
c30dabfe JK |
3375 | if (!err2) |
3376 | mnt_drop_write(nd.path.mnt); | |
ed75e95d AV |
3377 | out: |
3378 | path_put(&nd.path); | |
1da177e4 LT |
3379 | return dentry; |
3380 | } | |
fa14a0b8 AV |
3381 | |
3382 | struct dentry *kern_path_create(int dfd, const char *pathname, | |
3383 | struct path *path, unsigned int lookup_flags) | |
3384 | { | |
51689104 PM |
3385 | struct filename *filename = getname_kernel(pathname); |
3386 | struct dentry *res; | |
3387 | ||
3388 | if (IS_ERR(filename)) | |
3389 | return ERR_CAST(filename); | |
3390 | res = filename_create(dfd, filename, path, lookup_flags); | |
3391 | putname(filename); | |
3392 | return res; | |
fa14a0b8 | 3393 | } |
dae6ad8f AV |
3394 | EXPORT_SYMBOL(kern_path_create); |
3395 | ||
921a1650 AV |
3396 | void done_path_create(struct path *path, struct dentry *dentry) |
3397 | { | |
3398 | dput(dentry); | |
3399 | mutex_unlock(&path->dentry->d_inode->i_mutex); | |
a8104a9f | 3400 | mnt_drop_write(path->mnt); |
921a1650 AV |
3401 | path_put(path); |
3402 | } | |
3403 | EXPORT_SYMBOL(done_path_create); | |
3404 | ||
1ac12b4b JL |
3405 | struct dentry *user_path_create(int dfd, const char __user *pathname, |
3406 | struct path *path, unsigned int lookup_flags) | |
dae6ad8f | 3407 | { |
91a27b2a | 3408 | struct filename *tmp = getname(pathname); |
dae6ad8f AV |
3409 | struct dentry *res; |
3410 | if (IS_ERR(tmp)) | |
3411 | return ERR_CAST(tmp); | |
fa14a0b8 | 3412 | res = filename_create(dfd, tmp, path, lookup_flags); |
dae6ad8f AV |
3413 | putname(tmp); |
3414 | return res; | |
3415 | } | |
3416 | EXPORT_SYMBOL(user_path_create); | |
3417 | ||
1a67aafb | 3418 | int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
1da177e4 | 3419 | { |
a95164d9 | 3420 | int error = may_create(dir, dentry); |
1da177e4 LT |
3421 | |
3422 | if (error) | |
3423 | return error; | |
3424 | ||
975d6b39 | 3425 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) |
1da177e4 LT |
3426 | return -EPERM; |
3427 | ||
acfa4380 | 3428 | if (!dir->i_op->mknod) |
1da177e4 LT |
3429 | return -EPERM; |
3430 | ||
08ce5f16 SH |
3431 | error = devcgroup_inode_mknod(mode, dev); |
3432 | if (error) | |
3433 | return error; | |
3434 | ||
1da177e4 LT |
3435 | error = security_inode_mknod(dir, dentry, mode, dev); |
3436 | if (error) | |
3437 | return error; | |
3438 | ||
1da177e4 | 3439 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
a74574aa | 3440 | if (!error) |
f38aa942 | 3441 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3442 | return error; |
3443 | } | |
4d359507 | 3444 | EXPORT_SYMBOL(vfs_mknod); |
1da177e4 | 3445 | |
f69aac00 | 3446 | static int may_mknod(umode_t mode) |
463c3197 DH |
3447 | { |
3448 | switch (mode & S_IFMT) { | |
3449 | case S_IFREG: | |
3450 | case S_IFCHR: | |
3451 | case S_IFBLK: | |
3452 | case S_IFIFO: | |
3453 | case S_IFSOCK: | |
3454 | case 0: /* zero mode translates to S_IFREG */ | |
3455 | return 0; | |
3456 | case S_IFDIR: | |
3457 | return -EPERM; | |
3458 | default: | |
3459 | return -EINVAL; | |
3460 | } | |
3461 | } | |
3462 | ||
8208a22b | 3463 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, |
2e4d0924 | 3464 | unsigned, dev) |
1da177e4 | 3465 | { |
2ad94ae6 | 3466 | struct dentry *dentry; |
dae6ad8f AV |
3467 | struct path path; |
3468 | int error; | |
972567f1 | 3469 | unsigned int lookup_flags = 0; |
1da177e4 | 3470 | |
8e4bfca1 AV |
3471 | error = may_mknod(mode); |
3472 | if (error) | |
3473 | return error; | |
972567f1 JL |
3474 | retry: |
3475 | dentry = user_path_create(dfd, filename, &path, lookup_flags); | |
dae6ad8f AV |
3476 | if (IS_ERR(dentry)) |
3477 | return PTR_ERR(dentry); | |
2ad94ae6 | 3478 | |
dae6ad8f | 3479 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3480 | mode &= ~current_umask(); |
dae6ad8f | 3481 | error = security_path_mknod(&path, dentry, mode, dev); |
be6d3e56 | 3482 | if (error) |
a8104a9f | 3483 | goto out; |
463c3197 | 3484 | switch (mode & S_IFMT) { |
1da177e4 | 3485 | case 0: case S_IFREG: |
312b63fb | 3486 | error = vfs_create(path.dentry->d_inode,dentry,mode,true); |
1da177e4 LT |
3487 | break; |
3488 | case S_IFCHR: case S_IFBLK: | |
dae6ad8f | 3489 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
1da177e4 LT |
3490 | new_decode_dev(dev)); |
3491 | break; | |
3492 | case S_IFIFO: case S_IFSOCK: | |
dae6ad8f | 3493 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
1da177e4 | 3494 | break; |
1da177e4 | 3495 | } |
a8104a9f | 3496 | out: |
921a1650 | 3497 | done_path_create(&path, dentry); |
972567f1 JL |
3498 | if (retry_estale(error, lookup_flags)) { |
3499 | lookup_flags |= LOOKUP_REVAL; | |
3500 | goto retry; | |
3501 | } | |
1da177e4 LT |
3502 | return error; |
3503 | } | |
3504 | ||
8208a22b | 3505 | SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) |
5590ff0d UD |
3506 | { |
3507 | return sys_mknodat(AT_FDCWD, filename, mode, dev); | |
3508 | } | |
3509 | ||
18bb1db3 | 3510 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
1da177e4 | 3511 | { |
a95164d9 | 3512 | int error = may_create(dir, dentry); |
8de52778 | 3513 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
3514 | |
3515 | if (error) | |
3516 | return error; | |
3517 | ||
acfa4380 | 3518 | if (!dir->i_op->mkdir) |
1da177e4 LT |
3519 | return -EPERM; |
3520 | ||
3521 | mode &= (S_IRWXUGO|S_ISVTX); | |
3522 | error = security_inode_mkdir(dir, dentry, mode); | |
3523 | if (error) | |
3524 | return error; | |
3525 | ||
8de52778 AV |
3526 | if (max_links && dir->i_nlink >= max_links) |
3527 | return -EMLINK; | |
3528 | ||
1da177e4 | 3529 | error = dir->i_op->mkdir(dir, dentry, mode); |
a74574aa | 3530 | if (!error) |
f38aa942 | 3531 | fsnotify_mkdir(dir, dentry); |
1da177e4 LT |
3532 | return error; |
3533 | } | |
4d359507 | 3534 | EXPORT_SYMBOL(vfs_mkdir); |
1da177e4 | 3535 | |
a218d0fd | 3536 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) |
1da177e4 | 3537 | { |
6902d925 | 3538 | struct dentry *dentry; |
dae6ad8f AV |
3539 | struct path path; |
3540 | int error; | |
b76d8b82 | 3541 | unsigned int lookup_flags = LOOKUP_DIRECTORY; |
1da177e4 | 3542 | |
b76d8b82 JL |
3543 | retry: |
3544 | dentry = user_path_create(dfd, pathname, &path, lookup_flags); | |
6902d925 | 3545 | if (IS_ERR(dentry)) |
dae6ad8f | 3546 | return PTR_ERR(dentry); |
1da177e4 | 3547 | |
dae6ad8f | 3548 | if (!IS_POSIXACL(path.dentry->d_inode)) |
ce3b0f8d | 3549 | mode &= ~current_umask(); |
dae6ad8f | 3550 | error = security_path_mkdir(&path, dentry, mode); |
a8104a9f AV |
3551 | if (!error) |
3552 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); | |
921a1650 | 3553 | done_path_create(&path, dentry); |
b76d8b82 JL |
3554 | if (retry_estale(error, lookup_flags)) { |
3555 | lookup_flags |= LOOKUP_REVAL; | |
3556 | goto retry; | |
3557 | } | |
1da177e4 LT |
3558 | return error; |
3559 | } | |
3560 | ||
a218d0fd | 3561 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) |
5590ff0d UD |
3562 | { |
3563 | return sys_mkdirat(AT_FDCWD, pathname, mode); | |
3564 | } | |
3565 | ||
1da177e4 | 3566 | /* |
a71905f0 | 3567 | * The dentry_unhash() helper will try to drop the dentry early: we |
c0d02594 | 3568 | * should have a usage count of 1 if we're the only user of this |
a71905f0 SW |
3569 | * dentry, and if that is true (possibly after pruning the dcache), |
3570 | * then we drop the dentry now. | |
1da177e4 LT |
3571 | * |
3572 | * A low-level filesystem can, if it choses, legally | |
3573 | * do a | |
3574 | * | |
3575 | * if (!d_unhashed(dentry)) | |
3576 | * return -EBUSY; | |
3577 | * | |
3578 | * if it cannot handle the case of removing a directory | |
3579 | * that is still in use by something else.. | |
3580 | */ | |
3581 | void dentry_unhash(struct dentry *dentry) | |
3582 | { | |
dc168427 | 3583 | shrink_dcache_parent(dentry); |
1da177e4 | 3584 | spin_lock(&dentry->d_lock); |
98474236 | 3585 | if (dentry->d_lockref.count == 1) |
1da177e4 LT |
3586 | __d_drop(dentry); |
3587 | spin_unlock(&dentry->d_lock); | |
1da177e4 | 3588 | } |
4d359507 | 3589 | EXPORT_SYMBOL(dentry_unhash); |
1da177e4 LT |
3590 | |
3591 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) | |
3592 | { | |
3593 | int error = may_delete(dir, dentry, 1); | |
3594 | ||
3595 | if (error) | |
3596 | return error; | |
3597 | ||
acfa4380 | 3598 | if (!dir->i_op->rmdir) |
1da177e4 LT |
3599 | return -EPERM; |
3600 | ||
1d2ef590 | 3601 | dget(dentry); |
1b1dcc1b | 3602 | mutex_lock(&dentry->d_inode->i_mutex); |
912dbc15 SW |
3603 | |
3604 | error = -EBUSY; | |
7af1364f | 3605 | if (is_local_mountpoint(dentry)) |
912dbc15 SW |
3606 | goto out; |
3607 | ||
3608 | error = security_inode_rmdir(dir, dentry); | |
3609 | if (error) | |
3610 | goto out; | |
3611 | ||
3cebde24 | 3612 | shrink_dcache_parent(dentry); |
912dbc15 SW |
3613 | error = dir->i_op->rmdir(dir, dentry); |
3614 | if (error) | |
3615 | goto out; | |
3616 | ||
3617 | dentry->d_inode->i_flags |= S_DEAD; | |
3618 | dont_mount(dentry); | |
8ed936b5 | 3619 | detach_mounts(dentry); |
912dbc15 SW |
3620 | |
3621 | out: | |
1b1dcc1b | 3622 | mutex_unlock(&dentry->d_inode->i_mutex); |
1d2ef590 | 3623 | dput(dentry); |
912dbc15 | 3624 | if (!error) |
1da177e4 | 3625 | d_delete(dentry); |
1da177e4 LT |
3626 | return error; |
3627 | } | |
4d359507 | 3628 | EXPORT_SYMBOL(vfs_rmdir); |
1da177e4 | 3629 | |
5590ff0d | 3630 | static long do_rmdir(int dfd, const char __user *pathname) |
1da177e4 LT |
3631 | { |
3632 | int error = 0; | |
91a27b2a | 3633 | struct filename *name; |
1da177e4 | 3634 | struct dentry *dentry; |
f5beed75 AV |
3635 | struct path path; |
3636 | struct qstr last; | |
3637 | int type; | |
c6ee9206 JL |
3638 | unsigned int lookup_flags = 0; |
3639 | retry: | |
f5beed75 AV |
3640 | name = user_path_parent(dfd, pathname, |
3641 | &path, &last, &type, lookup_flags); | |
91a27b2a JL |
3642 | if (IS_ERR(name)) |
3643 | return PTR_ERR(name); | |
1da177e4 | 3644 | |
f5beed75 | 3645 | switch (type) { |
0612d9fb OH |
3646 | case LAST_DOTDOT: |
3647 | error = -ENOTEMPTY; | |
3648 | goto exit1; | |
3649 | case LAST_DOT: | |
3650 | error = -EINVAL; | |
3651 | goto exit1; | |
3652 | case LAST_ROOT: | |
3653 | error = -EBUSY; | |
3654 | goto exit1; | |
1da177e4 | 3655 | } |
0612d9fb | 3656 | |
f5beed75 | 3657 | error = mnt_want_write(path.mnt); |
c30dabfe JK |
3658 | if (error) |
3659 | goto exit1; | |
0612d9fb | 3660 | |
f5beed75 AV |
3661 | mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
3662 | dentry = __lookup_hash(&last, path.dentry, lookup_flags); | |
1da177e4 | 3663 | error = PTR_ERR(dentry); |
6902d925 DH |
3664 | if (IS_ERR(dentry)) |
3665 | goto exit2; | |
e6bc45d6 TT |
3666 | if (!dentry->d_inode) { |
3667 | error = -ENOENT; | |
3668 | goto exit3; | |
3669 | } | |
f5beed75 | 3670 | error = security_path_rmdir(&path, dentry); |
be6d3e56 | 3671 | if (error) |
c30dabfe | 3672 | goto exit3; |
f5beed75 | 3673 | error = vfs_rmdir(path.dentry->d_inode, dentry); |
0622753b | 3674 | exit3: |
6902d925 DH |
3675 | dput(dentry); |
3676 | exit2: | |
f5beed75 AV |
3677 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
3678 | mnt_drop_write(path.mnt); | |
1da177e4 | 3679 | exit1: |
f5beed75 | 3680 | path_put(&path); |
1da177e4 | 3681 | putname(name); |
c6ee9206 JL |
3682 | if (retry_estale(error, lookup_flags)) { |
3683 | lookup_flags |= LOOKUP_REVAL; | |
3684 | goto retry; | |
3685 | } | |
1da177e4 LT |
3686 | return error; |
3687 | } | |
3688 | ||
3cdad428 | 3689 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
5590ff0d UD |
3690 | { |
3691 | return do_rmdir(AT_FDCWD, pathname); | |
3692 | } | |
3693 | ||
b21996e3 BF |
3694 | /** |
3695 | * vfs_unlink - unlink a filesystem object | |
3696 | * @dir: parent directory | |
3697 | * @dentry: victim | |
3698 | * @delegated_inode: returns victim inode, if the inode is delegated. | |
3699 | * | |
3700 | * The caller must hold dir->i_mutex. | |
3701 | * | |
3702 | * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and | |
3703 | * return a reference to the inode in delegated_inode. The caller | |
3704 | * should then break the delegation on that inode and retry. Because | |
3705 | * breaking a delegation may take a long time, the caller should drop | |
3706 | * dir->i_mutex before doing so. | |
3707 | * | |
3708 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
3709 | * be appropriate for callers that expect the underlying filesystem not | |
3710 | * to be NFS exported. | |
3711 | */ | |
3712 | int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) | |
1da177e4 | 3713 | { |
9accbb97 | 3714 | struct inode *target = dentry->d_inode; |
1da177e4 LT |
3715 | int error = may_delete(dir, dentry, 0); |
3716 | ||
3717 | if (error) | |
3718 | return error; | |
3719 | ||
acfa4380 | 3720 | if (!dir->i_op->unlink) |
1da177e4 LT |
3721 | return -EPERM; |
3722 | ||
9accbb97 | 3723 | mutex_lock(&target->i_mutex); |
8ed936b5 | 3724 | if (is_local_mountpoint(dentry)) |
1da177e4 LT |
3725 | error = -EBUSY; |
3726 | else { | |
3727 | error = security_inode_unlink(dir, dentry); | |
bec1052e | 3728 | if (!error) { |
5a14696c BF |
3729 | error = try_break_deleg(target, delegated_inode); |
3730 | if (error) | |
b21996e3 | 3731 | goto out; |
1da177e4 | 3732 | error = dir->i_op->unlink(dir, dentry); |
8ed936b5 | 3733 | if (!error) { |
d83c49f3 | 3734 | dont_mount(dentry); |
8ed936b5 EB |
3735 | detach_mounts(dentry); |
3736 | } | |
bec1052e | 3737 | } |
1da177e4 | 3738 | } |
b21996e3 | 3739 | out: |
9accbb97 | 3740 | mutex_unlock(&target->i_mutex); |
1da177e4 LT |
3741 | |
3742 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ | |
3743 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { | |
9accbb97 | 3744 | fsnotify_link_count(target); |
e234f35c | 3745 | d_delete(dentry); |
1da177e4 | 3746 | } |
0eeca283 | 3747 | |
1da177e4 LT |
3748 | return error; |
3749 | } | |
4d359507 | 3750 | EXPORT_SYMBOL(vfs_unlink); |
1da177e4 LT |
3751 | |
3752 | /* | |
3753 | * Make sure that the actual truncation of the file will occur outside its | |
1b1dcc1b | 3754 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
1da177e4 LT |
3755 | * writeout happening, and we don't want to prevent access to the directory |
3756 | * while waiting on the I/O. | |
3757 | */ | |
5590ff0d | 3758 | static long do_unlinkat(int dfd, const char __user *pathname) |
1da177e4 | 3759 | { |
2ad94ae6 | 3760 | int error; |
91a27b2a | 3761 | struct filename *name; |
1da177e4 | 3762 | struct dentry *dentry; |
f5beed75 AV |
3763 | struct path path; |
3764 | struct qstr last; | |
3765 | int type; | |
1da177e4 | 3766 | struct inode *inode = NULL; |
b21996e3 | 3767 | struct inode *delegated_inode = NULL; |
5d18f813 JL |
3768 | unsigned int lookup_flags = 0; |
3769 | retry: | |
f5beed75 AV |
3770 | name = user_path_parent(dfd, pathname, |
3771 | &path, &last, &type, lookup_flags); | |
91a27b2a JL |
3772 | if (IS_ERR(name)) |
3773 | return PTR_ERR(name); | |
2ad94ae6 | 3774 | |
1da177e4 | 3775 | error = -EISDIR; |
f5beed75 | 3776 | if (type != LAST_NORM) |
1da177e4 | 3777 | goto exit1; |
0612d9fb | 3778 | |
f5beed75 | 3779 | error = mnt_want_write(path.mnt); |
c30dabfe JK |
3780 | if (error) |
3781 | goto exit1; | |
b21996e3 | 3782 | retry_deleg: |
f5beed75 AV |
3783 | mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
3784 | dentry = __lookup_hash(&last, path.dentry, lookup_flags); | |
1da177e4 LT |
3785 | error = PTR_ERR(dentry); |
3786 | if (!IS_ERR(dentry)) { | |
3787 | /* Why not before? Because we want correct error value */ | |
f5beed75 | 3788 | if (last.name[last.len]) |
50338b88 | 3789 | goto slashes; |
1da177e4 | 3790 | inode = dentry->d_inode; |
b18825a7 | 3791 | if (d_is_negative(dentry)) |
e6bc45d6 TT |
3792 | goto slashes; |
3793 | ihold(inode); | |
f5beed75 | 3794 | error = security_path_unlink(&path, dentry); |
be6d3e56 | 3795 | if (error) |
c30dabfe | 3796 | goto exit2; |
f5beed75 | 3797 | error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); |
c30dabfe | 3798 | exit2: |
1da177e4 LT |
3799 | dput(dentry); |
3800 | } | |
f5beed75 | 3801 | mutex_unlock(&path.dentry->d_inode->i_mutex); |
1da177e4 LT |
3802 | if (inode) |
3803 | iput(inode); /* truncate the inode here */ | |
b21996e3 BF |
3804 | inode = NULL; |
3805 | if (delegated_inode) { | |
5a14696c | 3806 | error = break_deleg_wait(&delegated_inode); |
b21996e3 BF |
3807 | if (!error) |
3808 | goto retry_deleg; | |
3809 | } | |
f5beed75 | 3810 | mnt_drop_write(path.mnt); |
1da177e4 | 3811 | exit1: |
f5beed75 | 3812 | path_put(&path); |
1da177e4 | 3813 | putname(name); |
5d18f813 JL |
3814 | if (retry_estale(error, lookup_flags)) { |
3815 | lookup_flags |= LOOKUP_REVAL; | |
3816 | inode = NULL; | |
3817 | goto retry; | |
3818 | } | |
1da177e4 LT |
3819 | return error; |
3820 | ||
3821 | slashes: | |
b18825a7 DH |
3822 | if (d_is_negative(dentry)) |
3823 | error = -ENOENT; | |
44b1d530 | 3824 | else if (d_is_dir(dentry)) |
b18825a7 DH |
3825 | error = -EISDIR; |
3826 | else | |
3827 | error = -ENOTDIR; | |
1da177e4 LT |
3828 | goto exit2; |
3829 | } | |
3830 | ||
2e4d0924 | 3831 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
5590ff0d UD |
3832 | { |
3833 | if ((flag & ~AT_REMOVEDIR) != 0) | |
3834 | return -EINVAL; | |
3835 | ||
3836 | if (flag & AT_REMOVEDIR) | |
3837 | return do_rmdir(dfd, pathname); | |
3838 | ||
3839 | return do_unlinkat(dfd, pathname); | |
3840 | } | |
3841 | ||
3480b257 | 3842 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
5590ff0d UD |
3843 | { |
3844 | return do_unlinkat(AT_FDCWD, pathname); | |
3845 | } | |
3846 | ||
db2e747b | 3847 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
1da177e4 | 3848 | { |
a95164d9 | 3849 | int error = may_create(dir, dentry); |
1da177e4 LT |
3850 | |
3851 | if (error) | |
3852 | return error; | |
3853 | ||
acfa4380 | 3854 | if (!dir->i_op->symlink) |
1da177e4 LT |
3855 | return -EPERM; |
3856 | ||
3857 | error = security_inode_symlink(dir, dentry, oldname); | |
3858 | if (error) | |
3859 | return error; | |
3860 | ||
1da177e4 | 3861 | error = dir->i_op->symlink(dir, dentry, oldname); |
a74574aa | 3862 | if (!error) |
f38aa942 | 3863 | fsnotify_create(dir, dentry); |
1da177e4 LT |
3864 | return error; |
3865 | } | |
4d359507 | 3866 | EXPORT_SYMBOL(vfs_symlink); |
1da177e4 | 3867 | |
2e4d0924 HC |
3868 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
3869 | int, newdfd, const char __user *, newname) | |
1da177e4 | 3870 | { |
2ad94ae6 | 3871 | int error; |
91a27b2a | 3872 | struct filename *from; |
6902d925 | 3873 | struct dentry *dentry; |
dae6ad8f | 3874 | struct path path; |
f46d3567 | 3875 | unsigned int lookup_flags = 0; |
1da177e4 LT |
3876 | |
3877 | from = getname(oldname); | |
2ad94ae6 | 3878 | if (IS_ERR(from)) |
1da177e4 | 3879 | return PTR_ERR(from); |
f46d3567 JL |
3880 | retry: |
3881 | dentry = user_path_create(newdfd, newname, &path, lookup_flags); | |
6902d925 DH |
3882 | error = PTR_ERR(dentry); |
3883 | if (IS_ERR(dentry)) | |
dae6ad8f | 3884 | goto out_putname; |
6902d925 | 3885 | |
91a27b2a | 3886 | error = security_path_symlink(&path, dentry, from->name); |
a8104a9f | 3887 | if (!error) |
91a27b2a | 3888 | error = vfs_symlink(path.dentry->d_inode, dentry, from->name); |
921a1650 | 3889 | done_path_create(&path, dentry); |
f46d3567 JL |
3890 | if (retry_estale(error, lookup_flags)) { |
3891 | lookup_flags |= LOOKUP_REVAL; | |
3892 | goto retry; | |
3893 | } | |
6902d925 | 3894 | out_putname: |
1da177e4 LT |
3895 | putname(from); |
3896 | return error; | |
3897 | } | |
3898 | ||
3480b257 | 3899 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
5590ff0d UD |
3900 | { |
3901 | return sys_symlinkat(oldname, AT_FDCWD, newname); | |
3902 | } | |
3903 | ||
146a8595 BF |
3904 | /** |
3905 | * vfs_link - create a new link | |
3906 | * @old_dentry: object to be linked | |
3907 | * @dir: new parent | |
3908 | * @new_dentry: where to create the new link | |
3909 | * @delegated_inode: returns inode needing a delegation break | |
3910 | * | |
3911 | * The caller must hold dir->i_mutex | |
3912 | * | |
3913 | * If vfs_link discovers a delegation on the to-be-linked file in need | |
3914 | * of breaking, it will return -EWOULDBLOCK and return a reference to the | |
3915 | * inode in delegated_inode. The caller should then break the delegation | |
3916 | * and retry. Because breaking a delegation may take a long time, the | |
3917 | * caller should drop the i_mutex before doing so. | |
3918 | * | |
3919 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
3920 | * be appropriate for callers that expect the underlying filesystem not | |
3921 | * to be NFS exported. | |
3922 | */ | |
3923 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) | |
1da177e4 LT |
3924 | { |
3925 | struct inode *inode = old_dentry->d_inode; | |
8de52778 | 3926 | unsigned max_links = dir->i_sb->s_max_links; |
1da177e4 LT |
3927 | int error; |
3928 | ||
3929 | if (!inode) | |
3930 | return -ENOENT; | |
3931 | ||
a95164d9 | 3932 | error = may_create(dir, new_dentry); |
1da177e4 LT |
3933 | if (error) |
3934 | return error; | |
3935 | ||
3936 | if (dir->i_sb != inode->i_sb) | |
3937 | return -EXDEV; | |
3938 | ||
3939 | /* | |
3940 | * A link to an append-only or immutable file cannot be created. | |
3941 | */ | |
3942 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) | |
3943 | return -EPERM; | |
acfa4380 | 3944 | if (!dir->i_op->link) |
1da177e4 | 3945 | return -EPERM; |
7e79eedb | 3946 | if (S_ISDIR(inode->i_mode)) |
1da177e4 LT |
3947 | return -EPERM; |
3948 | ||
3949 | error = security_inode_link(old_dentry, dir, new_dentry); | |
3950 | if (error) | |
3951 | return error; | |
3952 | ||
7e79eedb | 3953 | mutex_lock(&inode->i_mutex); |
aae8a97d | 3954 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
f4e0c30c | 3955 | if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) |
aae8a97d | 3956 | error = -ENOENT; |
8de52778 AV |
3957 | else if (max_links && inode->i_nlink >= max_links) |
3958 | error = -EMLINK; | |
146a8595 BF |
3959 | else { |
3960 | error = try_break_deleg(inode, delegated_inode); | |
3961 | if (!error) | |
3962 | error = dir->i_op->link(old_dentry, dir, new_dentry); | |
3963 | } | |
f4e0c30c AV |
3964 | |
3965 | if (!error && (inode->i_state & I_LINKABLE)) { | |
3966 | spin_lock(&inode->i_lock); | |
3967 | inode->i_state &= ~I_LINKABLE; | |
3968 | spin_unlock(&inode->i_lock); | |
3969 | } | |
7e79eedb | 3970 | mutex_unlock(&inode->i_mutex); |
e31e14ec | 3971 | if (!error) |
7e79eedb | 3972 | fsnotify_link(dir, inode, new_dentry); |
1da177e4 LT |
3973 | return error; |
3974 | } | |
4d359507 | 3975 | EXPORT_SYMBOL(vfs_link); |
1da177e4 LT |
3976 | |
3977 | /* | |
3978 | * Hardlinks are often used in delicate situations. We avoid | |
3979 | * security-related surprises by not following symlinks on the | |
3980 | * newname. --KAB | |
3981 | * | |
3982 | * We don't follow them on the oldname either to be compatible | |
3983 | * with linux 2.0, and to avoid hard-linking to directories | |
3984 | * and other special files. --ADM | |
3985 | */ | |
2e4d0924 HC |
3986 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
3987 | int, newdfd, const char __user *, newname, int, flags) | |
1da177e4 LT |
3988 | { |
3989 | struct dentry *new_dentry; | |
dae6ad8f | 3990 | struct path old_path, new_path; |
146a8595 | 3991 | struct inode *delegated_inode = NULL; |
11a7b371 | 3992 | int how = 0; |
1da177e4 | 3993 | int error; |
1da177e4 | 3994 | |
11a7b371 | 3995 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
c04030e1 | 3996 | return -EINVAL; |
11a7b371 | 3997 | /* |
f0cc6ffb LT |
3998 | * To use null names we require CAP_DAC_READ_SEARCH |
3999 | * This ensures that not everyone will be able to create | |
4000 | * handlink using the passed filedescriptor. | |
11a7b371 | 4001 | */ |
f0cc6ffb LT |
4002 | if (flags & AT_EMPTY_PATH) { |
4003 | if (!capable(CAP_DAC_READ_SEARCH)) | |
4004 | return -ENOENT; | |
11a7b371 | 4005 | how = LOOKUP_EMPTY; |
f0cc6ffb | 4006 | } |
11a7b371 AK |
4007 | |
4008 | if (flags & AT_SYMLINK_FOLLOW) | |
4009 | how |= LOOKUP_FOLLOW; | |
442e31ca | 4010 | retry: |
11a7b371 | 4011 | error = user_path_at(olddfd, oldname, how, &old_path); |
1da177e4 | 4012 | if (error) |
2ad94ae6 AV |
4013 | return error; |
4014 | ||
442e31ca JL |
4015 | new_dentry = user_path_create(newdfd, newname, &new_path, |
4016 | (how & LOOKUP_REVAL)); | |
1da177e4 | 4017 | error = PTR_ERR(new_dentry); |
6902d925 | 4018 | if (IS_ERR(new_dentry)) |
dae6ad8f AV |
4019 | goto out; |
4020 | ||
4021 | error = -EXDEV; | |
4022 | if (old_path.mnt != new_path.mnt) | |
4023 | goto out_dput; | |
800179c9 KC |
4024 | error = may_linkat(&old_path); |
4025 | if (unlikely(error)) | |
4026 | goto out_dput; | |
dae6ad8f | 4027 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
be6d3e56 | 4028 | if (error) |
a8104a9f | 4029 | goto out_dput; |
146a8595 | 4030 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); |
75c3f29d | 4031 | out_dput: |
921a1650 | 4032 | done_path_create(&new_path, new_dentry); |
146a8595 BF |
4033 | if (delegated_inode) { |
4034 | error = break_deleg_wait(&delegated_inode); | |
d22e6338 OD |
4035 | if (!error) { |
4036 | path_put(&old_path); | |
146a8595 | 4037 | goto retry; |
d22e6338 | 4038 | } |
146a8595 | 4039 | } |
442e31ca | 4040 | if (retry_estale(error, how)) { |
d22e6338 | 4041 | path_put(&old_path); |
442e31ca JL |
4042 | how |= LOOKUP_REVAL; |
4043 | goto retry; | |
4044 | } | |
1da177e4 | 4045 | out: |
2d8f3038 | 4046 | path_put(&old_path); |
1da177e4 LT |
4047 | |
4048 | return error; | |
4049 | } | |
4050 | ||
3480b257 | 4051 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 4052 | { |
c04030e1 | 4053 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
4054 | } |
4055 | ||
bc27027a MS |
4056 | /** |
4057 | * vfs_rename - rename a filesystem object | |
4058 | * @old_dir: parent of source | |
4059 | * @old_dentry: source | |
4060 | * @new_dir: parent of destination | |
4061 | * @new_dentry: destination | |
4062 | * @delegated_inode: returns an inode needing a delegation break | |
520c8b16 | 4063 | * @flags: rename flags |
bc27027a MS |
4064 | * |
4065 | * The caller must hold multiple mutexes--see lock_rename()). | |
4066 | * | |
4067 | * If vfs_rename discovers a delegation in need of breaking at either | |
4068 | * the source or destination, it will return -EWOULDBLOCK and return a | |
4069 | * reference to the inode in delegated_inode. The caller should then | |
4070 | * break the delegation and retry. Because breaking a delegation may | |
4071 | * take a long time, the caller should drop all locks before doing | |
4072 | * so. | |
4073 | * | |
4074 | * Alternatively, a caller may pass NULL for delegated_inode. This may | |
4075 | * be appropriate for callers that expect the underlying filesystem not | |
4076 | * to be NFS exported. | |
4077 | * | |
1da177e4 LT |
4078 | * The worst of all namespace operations - renaming directory. "Perverted" |
4079 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... | |
4080 | * Problems: | |
d03b29a2 | 4081 | * a) we can get into loop creation. |
1da177e4 LT |
4082 | * b) race potential - two innocent renames can create a loop together. |
4083 | * That's where 4.4 screws up. Current fix: serialization on | |
a11f3a05 | 4084 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
1da177e4 | 4085 | * story. |
6cedba89 BF |
4086 | * c) we have to lock _four_ objects - parents and victim (if it exists), |
4087 | * and source (if it is not a directory). | |
1b1dcc1b | 4088 | * And that - after we got ->i_mutex on parents (until then we don't know |
1da177e4 LT |
4089 | * whether the target exists). Solution: try to be smart with locking |
4090 | * order for inodes. We rely on the fact that tree topology may change | |
a11f3a05 | 4091 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
1da177e4 LT |
4092 | * move will be locked. Thus we can rank directories by the tree |
4093 | * (ancestors first) and rank all non-directories after them. | |
4094 | * That works since everybody except rename does "lock parent, lookup, | |
a11f3a05 | 4095 | * lock child" and rename is under ->s_vfs_rename_mutex. |
1da177e4 LT |
4096 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
4097 | * has no more than 1 dentry. If "hybrid" objects will ever appear, | |
4098 | * we'd better make sure that there's no link(2) for them. | |
e4eaac06 | 4099 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
1b1dcc1b | 4100 | * we are removing the target. Solution: we will have to grab ->i_mutex |
1da177e4 | 4101 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
c41b20e7 | 4102 | * ->i_mutex on parents, which works but leads to some truly excessive |
1da177e4 LT |
4103 | * locking]. |
4104 | */ | |
bc27027a MS |
4105 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, |
4106 | struct inode *new_dir, struct dentry *new_dentry, | |
520c8b16 | 4107 | struct inode **delegated_inode, unsigned int flags) |
1da177e4 | 4108 | { |
bc27027a MS |
4109 | int error; |
4110 | bool is_dir = d_is_dir(old_dentry); | |
4111 | const unsigned char *old_name; | |
4112 | struct inode *source = old_dentry->d_inode; | |
9055cba7 | 4113 | struct inode *target = new_dentry->d_inode; |
da1ce067 MS |
4114 | bool new_is_dir = false; |
4115 | unsigned max_links = new_dir->i_sb->s_max_links; | |
bc27027a MS |
4116 | |
4117 | if (source == target) | |
4118 | return 0; | |
4119 | ||
4120 | error = may_delete(old_dir, old_dentry, is_dir); | |
4121 | if (error) | |
4122 | return error; | |
4123 | ||
da1ce067 | 4124 | if (!target) { |
bc27027a | 4125 | error = may_create(new_dir, new_dentry); |
da1ce067 MS |
4126 | } else { |
4127 | new_is_dir = d_is_dir(new_dentry); | |
4128 | ||
4129 | if (!(flags & RENAME_EXCHANGE)) | |
4130 | error = may_delete(new_dir, new_dentry, is_dir); | |
4131 | else | |
4132 | error = may_delete(new_dir, new_dentry, new_is_dir); | |
4133 | } | |
bc27027a MS |
4134 | if (error) |
4135 | return error; | |
4136 | ||
7177a9c4 | 4137 | if (!old_dir->i_op->rename && !old_dir->i_op->rename2) |
bc27027a | 4138 | return -EPERM; |
1da177e4 | 4139 | |
520c8b16 MS |
4140 | if (flags && !old_dir->i_op->rename2) |
4141 | return -EINVAL; | |
4142 | ||
1da177e4 LT |
4143 | /* |
4144 | * If we are going to change the parent - check write permissions, | |
4145 | * we'll need to flip '..'. | |
4146 | */ | |
da1ce067 MS |
4147 | if (new_dir != old_dir) { |
4148 | if (is_dir) { | |
4149 | error = inode_permission(source, MAY_WRITE); | |
4150 | if (error) | |
4151 | return error; | |
4152 | } | |
4153 | if ((flags & RENAME_EXCHANGE) && new_is_dir) { | |
4154 | error = inode_permission(target, MAY_WRITE); | |
4155 | if (error) | |
4156 | return error; | |
4157 | } | |
1da177e4 LT |
4158 | } |
4159 | ||
0b3974eb MS |
4160 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, |
4161 | flags); | |
1da177e4 LT |
4162 | if (error) |
4163 | return error; | |
4164 | ||
bc27027a | 4165 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
1d2ef590 | 4166 | dget(new_dentry); |
da1ce067 | 4167 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
bc27027a MS |
4168 | lock_two_nondirectories(source, target); |
4169 | else if (target) | |
1b1dcc1b | 4170 | mutex_lock(&target->i_mutex); |
9055cba7 SW |
4171 | |
4172 | error = -EBUSY; | |
7af1364f | 4173 | if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) |
9055cba7 SW |
4174 | goto out; |
4175 | ||
da1ce067 | 4176 | if (max_links && new_dir != old_dir) { |
bc27027a | 4177 | error = -EMLINK; |
da1ce067 | 4178 | if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) |
bc27027a | 4179 | goto out; |
da1ce067 MS |
4180 | if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && |
4181 | old_dir->i_nlink >= max_links) | |
4182 | goto out; | |
4183 | } | |
4184 | if (is_dir && !(flags & RENAME_EXCHANGE) && target) | |
4185 | shrink_dcache_parent(new_dentry); | |
4186 | if (!is_dir) { | |
bc27027a | 4187 | error = try_break_deleg(source, delegated_inode); |
8e6d782c BF |
4188 | if (error) |
4189 | goto out; | |
da1ce067 MS |
4190 | } |
4191 | if (target && !new_is_dir) { | |
4192 | error = try_break_deleg(target, delegated_inode); | |
4193 | if (error) | |
4194 | goto out; | |
8e6d782c | 4195 | } |
7177a9c4 | 4196 | if (!old_dir->i_op->rename2) { |
520c8b16 MS |
4197 | error = old_dir->i_op->rename(old_dir, old_dentry, |
4198 | new_dir, new_dentry); | |
4199 | } else { | |
7177a9c4 | 4200 | WARN_ON(old_dir->i_op->rename != NULL); |
520c8b16 MS |
4201 | error = old_dir->i_op->rename2(old_dir, old_dentry, |
4202 | new_dir, new_dentry, flags); | |
4203 | } | |
51892bbb SW |
4204 | if (error) |
4205 | goto out; | |
4206 | ||
da1ce067 | 4207 | if (!(flags & RENAME_EXCHANGE) && target) { |
bc27027a MS |
4208 | if (is_dir) |
4209 | target->i_flags |= S_DEAD; | |
51892bbb | 4210 | dont_mount(new_dentry); |
8ed936b5 | 4211 | detach_mounts(new_dentry); |
bc27027a | 4212 | } |
da1ce067 MS |
4213 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { |
4214 | if (!(flags & RENAME_EXCHANGE)) | |
4215 | d_move(old_dentry, new_dentry); | |
4216 | else | |
4217 | d_exchange(old_dentry, new_dentry); | |
4218 | } | |
51892bbb | 4219 | out: |
da1ce067 | 4220 | if (!is_dir || (flags & RENAME_EXCHANGE)) |
bc27027a MS |
4221 | unlock_two_nondirectories(source, target); |
4222 | else if (target) | |
4223 | mutex_unlock(&target->i_mutex); | |
1da177e4 | 4224 | dput(new_dentry); |
da1ce067 | 4225 | if (!error) { |
123df294 | 4226 | fsnotify_move(old_dir, new_dir, old_name, is_dir, |
da1ce067 MS |
4227 | !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); |
4228 | if (flags & RENAME_EXCHANGE) { | |
4229 | fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, | |
4230 | new_is_dir, NULL, new_dentry); | |
4231 | } | |
4232 | } | |
0eeca283 RL |
4233 | fsnotify_oldname_free(old_name); |
4234 | ||
1da177e4 LT |
4235 | return error; |
4236 | } | |
4d359507 | 4237 | EXPORT_SYMBOL(vfs_rename); |
1da177e4 | 4238 | |
520c8b16 MS |
4239 | SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, |
4240 | int, newdfd, const char __user *, newname, unsigned int, flags) | |
1da177e4 | 4241 | { |
2ad94ae6 AV |
4242 | struct dentry *old_dentry, *new_dentry; |
4243 | struct dentry *trap; | |
f5beed75 AV |
4244 | struct path old_path, new_path; |
4245 | struct qstr old_last, new_last; | |
4246 | int old_type, new_type; | |
8e6d782c | 4247 | struct inode *delegated_inode = NULL; |
91a27b2a JL |
4248 | struct filename *from; |
4249 | struct filename *to; | |
f5beed75 | 4250 | unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; |
c6a94284 | 4251 | bool should_retry = false; |
2ad94ae6 | 4252 | int error; |
520c8b16 | 4253 | |
0d7a8555 | 4254 | if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) |
da1ce067 MS |
4255 | return -EINVAL; |
4256 | ||
0d7a8555 MS |
4257 | if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && |
4258 | (flags & RENAME_EXCHANGE)) | |
520c8b16 MS |
4259 | return -EINVAL; |
4260 | ||
0d7a8555 MS |
4261 | if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) |
4262 | return -EPERM; | |
4263 | ||
f5beed75 AV |
4264 | if (flags & RENAME_EXCHANGE) |
4265 | target_flags = 0; | |
4266 | ||
c6a94284 | 4267 | retry: |
f5beed75 AV |
4268 | from = user_path_parent(olddfd, oldname, |
4269 | &old_path, &old_last, &old_type, lookup_flags); | |
91a27b2a JL |
4270 | if (IS_ERR(from)) { |
4271 | error = PTR_ERR(from); | |
1da177e4 | 4272 | goto exit; |
91a27b2a | 4273 | } |
1da177e4 | 4274 | |
f5beed75 AV |
4275 | to = user_path_parent(newdfd, newname, |
4276 | &new_path, &new_last, &new_type, lookup_flags); | |
91a27b2a JL |
4277 | if (IS_ERR(to)) { |
4278 | error = PTR_ERR(to); | |
1da177e4 | 4279 | goto exit1; |
91a27b2a | 4280 | } |
1da177e4 LT |
4281 | |
4282 | error = -EXDEV; | |
f5beed75 | 4283 | if (old_path.mnt != new_path.mnt) |
1da177e4 LT |
4284 | goto exit2; |
4285 | ||
1da177e4 | 4286 | error = -EBUSY; |
f5beed75 | 4287 | if (old_type != LAST_NORM) |
1da177e4 LT |
4288 | goto exit2; |
4289 | ||
0a7c3937 MS |
4290 | if (flags & RENAME_NOREPLACE) |
4291 | error = -EEXIST; | |
f5beed75 | 4292 | if (new_type != LAST_NORM) |
1da177e4 LT |
4293 | goto exit2; |
4294 | ||
f5beed75 | 4295 | error = mnt_want_write(old_path.mnt); |
c30dabfe JK |
4296 | if (error) |
4297 | goto exit2; | |
4298 | ||
8e6d782c | 4299 | retry_deleg: |
f5beed75 | 4300 | trap = lock_rename(new_path.dentry, old_path.dentry); |
1da177e4 | 4301 | |
f5beed75 | 4302 | old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); |
1da177e4 LT |
4303 | error = PTR_ERR(old_dentry); |
4304 | if (IS_ERR(old_dentry)) | |
4305 | goto exit3; | |
4306 | /* source must exist */ | |
4307 | error = -ENOENT; | |
b18825a7 | 4308 | if (d_is_negative(old_dentry)) |
1da177e4 | 4309 | goto exit4; |
f5beed75 | 4310 | new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); |
0a7c3937 MS |
4311 | error = PTR_ERR(new_dentry); |
4312 | if (IS_ERR(new_dentry)) | |
4313 | goto exit4; | |
4314 | error = -EEXIST; | |
4315 | if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) | |
4316 | goto exit5; | |
da1ce067 MS |
4317 | if (flags & RENAME_EXCHANGE) { |
4318 | error = -ENOENT; | |
4319 | if (d_is_negative(new_dentry)) | |
4320 | goto exit5; | |
4321 | ||
4322 | if (!d_is_dir(new_dentry)) { | |
4323 | error = -ENOTDIR; | |
f5beed75 | 4324 | if (new_last.name[new_last.len]) |
da1ce067 MS |
4325 | goto exit5; |
4326 | } | |
4327 | } | |
1da177e4 | 4328 | /* unless the source is a directory trailing slashes give -ENOTDIR */ |
44b1d530 | 4329 | if (!d_is_dir(old_dentry)) { |
1da177e4 | 4330 | error = -ENOTDIR; |
f5beed75 | 4331 | if (old_last.name[old_last.len]) |
0a7c3937 | 4332 | goto exit5; |
f5beed75 | 4333 | if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) |
0a7c3937 | 4334 | goto exit5; |
1da177e4 LT |
4335 | } |
4336 | /* source should not be ancestor of target */ | |
4337 | error = -EINVAL; | |
4338 | if (old_dentry == trap) | |
0a7c3937 | 4339 | goto exit5; |
1da177e4 | 4340 | /* target should not be an ancestor of source */ |
da1ce067 MS |
4341 | if (!(flags & RENAME_EXCHANGE)) |
4342 | error = -ENOTEMPTY; | |
1da177e4 LT |
4343 | if (new_dentry == trap) |
4344 | goto exit5; | |
4345 | ||
f5beed75 AV |
4346 | error = security_path_rename(&old_path, old_dentry, |
4347 | &new_path, new_dentry, flags); | |
be6d3e56 | 4348 | if (error) |
c30dabfe | 4349 | goto exit5; |
f5beed75 AV |
4350 | error = vfs_rename(old_path.dentry->d_inode, old_dentry, |
4351 | new_path.dentry->d_inode, new_dentry, | |
520c8b16 | 4352 | &delegated_inode, flags); |
1da177e4 LT |
4353 | exit5: |
4354 | dput(new_dentry); | |
4355 | exit4: | |
4356 | dput(old_dentry); | |
4357 | exit3: | |
f5beed75 | 4358 | unlock_rename(new_path.dentry, old_path.dentry); |
8e6d782c BF |
4359 | if (delegated_inode) { |
4360 | error = break_deleg_wait(&delegated_inode); | |
4361 | if (!error) | |
4362 | goto retry_deleg; | |
4363 | } | |
f5beed75 | 4364 | mnt_drop_write(old_path.mnt); |
1da177e4 | 4365 | exit2: |
c6a94284 JL |
4366 | if (retry_estale(error, lookup_flags)) |
4367 | should_retry = true; | |
f5beed75 | 4368 | path_put(&new_path); |
2ad94ae6 | 4369 | putname(to); |
1da177e4 | 4370 | exit1: |
f5beed75 | 4371 | path_put(&old_path); |
1da177e4 | 4372 | putname(from); |
c6a94284 JL |
4373 | if (should_retry) { |
4374 | should_retry = false; | |
4375 | lookup_flags |= LOOKUP_REVAL; | |
4376 | goto retry; | |
4377 | } | |
2ad94ae6 | 4378 | exit: |
1da177e4 LT |
4379 | return error; |
4380 | } | |
4381 | ||
520c8b16 MS |
4382 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
4383 | int, newdfd, const char __user *, newname) | |
4384 | { | |
4385 | return sys_renameat2(olddfd, oldname, newdfd, newname, 0); | |
4386 | } | |
4387 | ||
a26eab24 | 4388 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
5590ff0d | 4389 | { |
520c8b16 | 4390 | return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
5590ff0d UD |
4391 | } |
4392 | ||
787fb6bc MS |
4393 | int vfs_whiteout(struct inode *dir, struct dentry *dentry) |
4394 | { | |
4395 | int error = may_create(dir, dentry); | |
4396 | if (error) | |
4397 | return error; | |
4398 | ||
4399 | if (!dir->i_op->mknod) | |
4400 | return -EPERM; | |
4401 | ||
4402 | return dir->i_op->mknod(dir, dentry, | |
4403 | S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); | |
4404 | } | |
4405 | EXPORT_SYMBOL(vfs_whiteout); | |
4406 | ||
5d826c84 | 4407 | int readlink_copy(char __user *buffer, int buflen, const char *link) |
1da177e4 | 4408 | { |
5d826c84 | 4409 | int len = PTR_ERR(link); |
1da177e4 LT |
4410 | if (IS_ERR(link)) |
4411 | goto out; | |
4412 | ||
4413 | len = strlen(link); | |
4414 | if (len > (unsigned) buflen) | |
4415 | len = buflen; | |
4416 | if (copy_to_user(buffer, link, len)) | |
4417 | len = -EFAULT; | |
4418 | out: | |
4419 | return len; | |
4420 | } | |
5d826c84 | 4421 | EXPORT_SYMBOL(readlink_copy); |
1da177e4 LT |
4422 | |
4423 | /* | |
4424 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that | |
4425 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not | |
4426 | * using) it for any given inode is up to filesystem. | |
4427 | */ | |
4428 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4429 | { | |
cc314eef | 4430 | void *cookie; |
d4dee48b | 4431 | const char *link = dentry->d_inode->i_link; |
694a1764 | 4432 | int res; |
cc314eef | 4433 | |
d4dee48b AV |
4434 | if (!link) { |
4435 | link = dentry->d_inode->i_op->follow_link(dentry, &cookie, NULL); | |
4436 | if (IS_ERR(link)) | |
4437 | return PTR_ERR(link); | |
4438 | } | |
680baacb AV |
4439 | res = readlink_copy(buffer, buflen, link); |
4440 | if (cookie && dentry->d_inode->i_op->put_link) | |
4441 | dentry->d_inode->i_op->put_link(dentry, cookie); | |
694a1764 | 4442 | return res; |
1da177e4 | 4443 | } |
4d359507 | 4444 | EXPORT_SYMBOL(generic_readlink); |
1da177e4 | 4445 | |
1da177e4 LT |
4446 | /* get the link contents into pagecache */ |
4447 | static char *page_getlink(struct dentry * dentry, struct page **ppage) | |
4448 | { | |
ebd09abb DG |
4449 | char *kaddr; |
4450 | struct page *page; | |
1da177e4 | 4451 | struct address_space *mapping = dentry->d_inode->i_mapping; |
090d2b18 | 4452 | page = read_mapping_page(mapping, 0, NULL); |
1da177e4 | 4453 | if (IS_ERR(page)) |
6fe6900e | 4454 | return (char*)page; |
1da177e4 | 4455 | *ppage = page; |
ebd09abb DG |
4456 | kaddr = kmap(page); |
4457 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); | |
4458 | return kaddr; | |
1da177e4 LT |
4459 | } |
4460 | ||
4461 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) | |
4462 | { | |
4463 | struct page *page = NULL; | |
5d826c84 | 4464 | int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); |
1da177e4 LT |
4465 | if (page) { |
4466 | kunmap(page); | |
4467 | page_cache_release(page); | |
4468 | } | |
4469 | return res; | |
4470 | } | |
4d359507 | 4471 | EXPORT_SYMBOL(page_readlink); |
1da177e4 | 4472 | |
680baacb | 4473 | const char *page_follow_link_light(struct dentry *dentry, void **cookie, struct nameidata *nd) |
1da177e4 | 4474 | { |
cc314eef | 4475 | struct page *page = NULL; |
680baacb AV |
4476 | char *res = page_getlink(dentry, &page); |
4477 | if (!IS_ERR(res)) | |
4478 | *cookie = page; | |
4479 | return res; | |
1da177e4 | 4480 | } |
4d359507 | 4481 | EXPORT_SYMBOL(page_follow_link_light); |
1da177e4 | 4482 | |
680baacb | 4483 | void page_put_link(struct dentry *dentry, void *cookie) |
1da177e4 | 4484 | { |
cc314eef | 4485 | struct page *page = cookie; |
680baacb AV |
4486 | kunmap(page); |
4487 | page_cache_release(page); | |
1da177e4 | 4488 | } |
4d359507 | 4489 | EXPORT_SYMBOL(page_put_link); |
1da177e4 | 4490 | |
54566b2c NP |
4491 | /* |
4492 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS | |
4493 | */ | |
4494 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) | |
1da177e4 LT |
4495 | { |
4496 | struct address_space *mapping = inode->i_mapping; | |
0adb25d2 | 4497 | struct page *page; |
afddba49 | 4498 | void *fsdata; |
beb497ab | 4499 | int err; |
1da177e4 | 4500 | char *kaddr; |
54566b2c NP |
4501 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
4502 | if (nofs) | |
4503 | flags |= AOP_FLAG_NOFS; | |
1da177e4 | 4504 | |
7e53cac4 | 4505 | retry: |
afddba49 | 4506 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
54566b2c | 4507 | flags, &page, &fsdata); |
1da177e4 | 4508 | if (err) |
afddba49 NP |
4509 | goto fail; |
4510 | ||
e8e3c3d6 | 4511 | kaddr = kmap_atomic(page); |
1da177e4 | 4512 | memcpy(kaddr, symname, len-1); |
e8e3c3d6 | 4513 | kunmap_atomic(kaddr); |
afddba49 NP |
4514 | |
4515 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, | |
4516 | page, fsdata); | |
1da177e4 LT |
4517 | if (err < 0) |
4518 | goto fail; | |
afddba49 NP |
4519 | if (err < len-1) |
4520 | goto retry; | |
4521 | ||
1da177e4 LT |
4522 | mark_inode_dirty(inode); |
4523 | return 0; | |
1da177e4 LT |
4524 | fail: |
4525 | return err; | |
4526 | } | |
4d359507 | 4527 | EXPORT_SYMBOL(__page_symlink); |
1da177e4 | 4528 | |
0adb25d2 KK |
4529 | int page_symlink(struct inode *inode, const char *symname, int len) |
4530 | { | |
4531 | return __page_symlink(inode, symname, len, | |
54566b2c | 4532 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
0adb25d2 | 4533 | } |
4d359507 | 4534 | EXPORT_SYMBOL(page_symlink); |
0adb25d2 | 4535 | |
92e1d5be | 4536 | const struct inode_operations page_symlink_inode_operations = { |
1da177e4 LT |
4537 | .readlink = generic_readlink, |
4538 | .follow_link = page_follow_link_light, | |
4539 | .put_link = page_put_link, | |
4540 | }; | |
1da177e4 | 4541 | EXPORT_SYMBOL(page_symlink_inode_operations); |