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Source at commit cdde9cf73945d547acd3e96f9508c79e84ad0bf1 created 12 years 9 months ago. By Maarten ter Huurne, MMC: JZ4740: Added support for CPU frequency changing | |
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1 | /* |
2 | * linux/fs/namei.c |
3 | * |
4 | * Copyright (C) 1991, 1992 Linus Torvalds |
5 | */ |
6 | |
7 | /* |
8 | * Some corrections by tytso. |
9 | */ |
10 | |
11 | /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname |
12 | * lookup logic. |
13 | */ |
14 | /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. |
15 | */ |
16 | |
17 | #include <linux/init.h> |
18 | #include <linux/export.h> |
19 | #include <linux/kernel.h> |
20 | #include <linux/slab.h> |
21 | #include <linux/fs.h> |
22 | #include <linux/namei.h> |
23 | #include <linux/pagemap.h> |
24 | #include <linux/fsnotify.h> |
25 | #include <linux/personality.h> |
26 | #include <linux/security.h> |
27 | #include <linux/ima.h> |
28 | #include <linux/syscalls.h> |
29 | #include <linux/mount.h> |
30 | #include <linux/audit.h> |
31 | #include <linux/capability.h> |
32 | #include <linux/file.h> |
33 | #include <linux/fcntl.h> |
34 | #include <linux/device_cgroup.h> |
35 | #include <linux/fs_struct.h> |
36 | #include <linux/posix_acl.h> |
37 | #include <asm/uaccess.h> |
38 | |
39 | #include "internal.h" |
40 | #include "mount.h" |
41 | |
42 | /* [Feb-1997 T. Schoebel-Theuer] |
43 | * Fundamental changes in the pathname lookup mechanisms (namei) |
44 | * were necessary because of omirr. The reason is that omirr needs |
45 | * to know the _real_ pathname, not the user-supplied one, in case |
46 | * of symlinks (and also when transname replacements occur). |
47 | * |
48 | * The new code replaces the old recursive symlink resolution with |
49 | * an iterative one (in case of non-nested symlink chains). It does |
50 | * this with calls to <fs>_follow_link(). |
51 | * As a side effect, dir_namei(), _namei() and follow_link() are now |
52 | * replaced with a single function lookup_dentry() that can handle all |
53 | * the special cases of the former code. |
54 | * |
55 | * With the new dcache, the pathname is stored at each inode, at least as |
56 | * long as the refcount of the inode is positive. As a side effect, the |
57 | * size of the dcache depends on the inode cache and thus is dynamic. |
58 | * |
59 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink |
60 | * resolution to correspond with current state of the code. |
61 | * |
62 | * Note that the symlink resolution is not *completely* iterative. |
63 | * There is still a significant amount of tail- and mid- recursion in |
64 | * the algorithm. Also, note that <fs>_readlink() is not used in |
65 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() |
66 | * may return different results than <fs>_follow_link(). Many virtual |
67 | * filesystems (including /proc) exhibit this behavior. |
68 | */ |
69 | |
70 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: |
71 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL |
72 | * and the name already exists in form of a symlink, try to create the new |
73 | * name indicated by the symlink. The old code always complained that the |
74 | * name already exists, due to not following the symlink even if its target |
75 | * is nonexistent. The new semantics affects also mknod() and link() when |
76 | * the name is a symlink pointing to a non-existent name. |
77 | * |
78 | * I don't know which semantics is the right one, since I have no access |
79 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" |
80 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the |
81 | * "old" one. Personally, I think the new semantics is much more logical. |
82 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing |
83 | * file does succeed in both HP-UX and SunOs, but not in Solaris |
84 | * and in the old Linux semantics. |
85 | */ |
86 | |
87 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink |
88 | * semantics. See the comments in "open_namei" and "do_link" below. |
89 | * |
90 | * [10-Sep-98 Alan Modra] Another symlink change. |
91 | */ |
92 | |
93 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: |
94 | * inside the path - always follow. |
95 | * in the last component in creation/removal/renaming - never follow. |
96 | * if LOOKUP_FOLLOW passed - follow. |
97 | * if the pathname has trailing slashes - follow. |
98 | * otherwise - don't follow. |
99 | * (applied in that order). |
100 | * |
101 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT |
102 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. |
103 | * During the 2.4 we need to fix the userland stuff depending on it - |
104 | * hopefully we will be able to get rid of that wart in 2.5. So far only |
105 | * XEmacs seems to be relying on it... |
106 | */ |
107 | /* |
108 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) |
109 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
110 | * any extra contention... |
111 | */ |
112 | |
113 | /* In order to reduce some races, while at the same time doing additional |
114 | * checking and hopefully speeding things up, we copy filenames to the |
115 | * kernel data space before using them.. |
116 | * |
117 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). |
118 | * PATH_MAX includes the nul terminator --RR. |
119 | */ |
120 | static char *getname_flags(const char __user *filename, int flags, int *empty) |
121 | { |
122 | char *result = __getname(), *err; |
123 | int len; |
124 | |
125 | if (unlikely(!result)) |
126 | return ERR_PTR(-ENOMEM); |
127 | |
128 | len = strncpy_from_user(result, filename, PATH_MAX); |
129 | err = ERR_PTR(len); |
130 | if (unlikely(len < 0)) |
131 | goto error; |
132 | |
133 | /* The empty path is special. */ |
134 | if (unlikely(!len)) { |
135 | if (empty) |
136 | *empty = 1; |
137 | err = ERR_PTR(-ENOENT); |
138 | if (!(flags & LOOKUP_EMPTY)) |
139 | goto error; |
140 | } |
141 | |
142 | err = ERR_PTR(-ENAMETOOLONG); |
143 | if (likely(len < PATH_MAX)) { |
144 | audit_getname(result); |
145 | return result; |
146 | } |
147 | |
148 | error: |
149 | __putname(result); |
150 | return err; |
151 | } |
152 | |
153 | char *getname(const char __user * filename) |
154 | { |
155 | return getname_flags(filename, 0, NULL); |
156 | } |
157 | |
158 | #ifdef CONFIG_AUDITSYSCALL |
159 | void putname(const char *name) |
160 | { |
161 | if (unlikely(!audit_dummy_context())) |
162 | audit_putname(name); |
163 | else |
164 | __putname(name); |
165 | } |
166 | EXPORT_SYMBOL(putname); |
167 | #endif |
168 | |
169 | static int check_acl(struct inode *inode, int mask) |
170 | { |
171 | #ifdef CONFIG_FS_POSIX_ACL |
172 | struct posix_acl *acl; |
173 | |
174 | if (mask & MAY_NOT_BLOCK) { |
175 | acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); |
176 | if (!acl) |
177 | return -EAGAIN; |
178 | /* no ->get_acl() calls in RCU mode... */ |
179 | if (acl == ACL_NOT_CACHED) |
180 | return -ECHILD; |
181 | return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); |
182 | } |
183 | |
184 | acl = get_cached_acl(inode, ACL_TYPE_ACCESS); |
185 | |
186 | /* |
187 | * A filesystem can force a ACL callback by just never filling the |
188 | * ACL cache. But normally you'd fill the cache either at inode |
189 | * instantiation time, or on the first ->get_acl call. |
190 | * |
191 | * If the filesystem doesn't have a get_acl() function at all, we'll |
192 | * just create the negative cache entry. |
193 | */ |
194 | if (acl == ACL_NOT_CACHED) { |
195 | if (inode->i_op->get_acl) { |
196 | acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS); |
197 | if (IS_ERR(acl)) |
198 | return PTR_ERR(acl); |
199 | } else { |
200 | set_cached_acl(inode, ACL_TYPE_ACCESS, NULL); |
201 | return -EAGAIN; |
202 | } |
203 | } |
204 | |
205 | if (acl) { |
206 | int error = posix_acl_permission(inode, acl, mask); |
207 | posix_acl_release(acl); |
208 | return error; |
209 | } |
210 | #endif |
211 | |
212 | return -EAGAIN; |
213 | } |
214 | |
215 | /* |
216 | * This does the basic permission checking |
217 | */ |
218 | static int acl_permission_check(struct inode *inode, int mask) |
219 | { |
220 | unsigned int mode = inode->i_mode; |
221 | |
222 | if (likely(uid_eq(current_fsuid(), inode->i_uid))) |
223 | mode >>= 6; |
224 | else { |
225 | if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { |
226 | int error = check_acl(inode, mask); |
227 | if (error != -EAGAIN) |
228 | return error; |
229 | } |
230 | |
231 | if (in_group_p(inode->i_gid)) |
232 | mode >>= 3; |
233 | } |
234 | |
235 | /* |
236 | * If the DACs are ok we don't need any capability check. |
237 | */ |
238 | if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) |
239 | return 0; |
240 | return -EACCES; |
241 | } |
242 | |
243 | /** |
244 | * generic_permission - check for access rights on a Posix-like filesystem |
245 | * @inode: inode to check access rights for |
246 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) |
247 | * |
248 | * Used to check for read/write/execute permissions on a file. |
249 | * We use "fsuid" for this, letting us set arbitrary permissions |
250 | * for filesystem access without changing the "normal" uids which |
251 | * are used for other things. |
252 | * |
253 | * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk |
254 | * request cannot be satisfied (eg. requires blocking or too much complexity). |
255 | * It would then be called again in ref-walk mode. |
256 | */ |
257 | int generic_permission(struct inode *inode, int mask) |
258 | { |
259 | int ret; |
260 | |
261 | /* |
262 | * Do the basic permission checks. |
263 | */ |
264 | ret = acl_permission_check(inode, mask); |
265 | if (ret != -EACCES) |
266 | return ret; |
267 | |
268 | if (S_ISDIR(inode->i_mode)) { |
269 | /* DACs are overridable for directories */ |
270 | if (inode_capable(inode, CAP_DAC_OVERRIDE)) |
271 | return 0; |
272 | if (!(mask & MAY_WRITE)) |
273 | if (inode_capable(inode, CAP_DAC_READ_SEARCH)) |
274 | return 0; |
275 | return -EACCES; |
276 | } |
277 | /* |
278 | * Read/write DACs are always overridable. |
279 | * Executable DACs are overridable when there is |
280 | * at least one exec bit set. |
281 | */ |
282 | if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) |
283 | if (inode_capable(inode, CAP_DAC_OVERRIDE)) |
284 | return 0; |
285 | |
286 | /* |
287 | * Searching includes executable on directories, else just read. |
288 | */ |
289 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
290 | if (mask == MAY_READ) |
291 | if (inode_capable(inode, CAP_DAC_READ_SEARCH)) |
292 | return 0; |
293 | |
294 | return -EACCES; |
295 | } |
296 | |
297 | /* |
298 | * We _really_ want to just do "generic_permission()" without |
299 | * even looking at the inode->i_op values. So we keep a cache |
300 | * flag in inode->i_opflags, that says "this has not special |
301 | * permission function, use the fast case". |
302 | */ |
303 | static inline int do_inode_permission(struct inode *inode, int mask) |
304 | { |
305 | if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { |
306 | if (likely(inode->i_op->permission)) |
307 | return inode->i_op->permission(inode, mask); |
308 | |
309 | /* This gets set once for the inode lifetime */ |
310 | spin_lock(&inode->i_lock); |
311 | inode->i_opflags |= IOP_FASTPERM; |
312 | spin_unlock(&inode->i_lock); |
313 | } |
314 | return generic_permission(inode, mask); |
315 | } |
316 | |
317 | /** |
318 | * __inode_permission - Check for access rights to a given inode |
319 | * @inode: Inode to check permission on |
320 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
321 | * |
322 | * Check for read/write/execute permissions on an inode. |
323 | * |
324 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. |
325 | * |
326 | * This does not check for a read-only file system. You probably want |
327 | * inode_permission(). |
328 | */ |
329 | int __inode_permission(struct inode *inode, int mask) |
330 | { |
331 | int retval; |
332 | |
333 | if (unlikely(mask & MAY_WRITE)) { |
334 | /* |
335 | * Nobody gets write access to an immutable file. |
336 | */ |
337 | if (IS_IMMUTABLE(inode)) |
338 | return -EACCES; |
339 | } |
340 | |
341 | retval = do_inode_permission(inode, mask); |
342 | if (retval) |
343 | return retval; |
344 | |
345 | retval = devcgroup_inode_permission(inode, mask); |
346 | if (retval) |
347 | return retval; |
348 | |
349 | return security_inode_permission(inode, mask); |
350 | } |
351 | |
352 | /** |
353 | * sb_permission - Check superblock-level permissions |
354 | * @sb: Superblock of inode to check permission on |
355 | * @inode: Inode to check permission on |
356 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
357 | * |
358 | * Separate out file-system wide checks from inode-specific permission checks. |
359 | */ |
360 | static int sb_permission(struct super_block *sb, struct inode *inode, int mask) |
361 | { |
362 | if (unlikely(mask & MAY_WRITE)) { |
363 | umode_t mode = inode->i_mode; |
364 | |
365 | /* Nobody gets write access to a read-only fs. */ |
366 | if ((sb->s_flags & MS_RDONLY) && |
367 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) |
368 | return -EROFS; |
369 | } |
370 | return 0; |
371 | } |
372 | |
373 | /** |
374 | * inode_permission - Check for access rights to a given inode |
375 | * @inode: Inode to check permission on |
376 | * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
377 | * |
378 | * Check for read/write/execute permissions on an inode. We use fs[ug]id for |
379 | * this, letting us set arbitrary permissions for filesystem access without |
380 | * changing the "normal" UIDs which are used for other things. |
381 | * |
382 | * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. |
383 | */ |
384 | int inode_permission(struct inode *inode, int mask) |
385 | { |
386 | int retval; |
387 | |
388 | retval = sb_permission(inode->i_sb, inode, mask); |
389 | if (retval) |
390 | return retval; |
391 | return __inode_permission(inode, mask); |
392 | } |
393 | |
394 | /** |
395 | * path_get - get a reference to a path |
396 | * @path: path to get the reference to |
397 | * |
398 | * Given a path increment the reference count to the dentry and the vfsmount. |
399 | */ |
400 | void path_get(struct path *path) |
401 | { |
402 | mntget(path->mnt); |
403 | dget(path->dentry); |
404 | } |
405 | EXPORT_SYMBOL(path_get); |
406 | |
407 | /** |
408 | * path_put - put a reference to a path |
409 | * @path: path to put the reference to |
410 | * |
411 | * Given a path decrement the reference count to the dentry and the vfsmount. |
412 | */ |
413 | void path_put(struct path *path) |
414 | { |
415 | dput(path->dentry); |
416 | mntput(path->mnt); |
417 | } |
418 | EXPORT_SYMBOL(path_put); |
419 | |
420 | /* |
421 | * Path walking has 2 modes, rcu-walk and ref-walk (see |
422 | * Documentation/filesystems/path-lookup.txt). In situations when we can't |
423 | * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab |
424 | * normal reference counts on dentries and vfsmounts to transition to rcu-walk |
425 | * mode. Refcounts are grabbed at the last known good point before rcu-walk |
426 | * got stuck, so ref-walk may continue from there. If this is not successful |
427 | * (eg. a seqcount has changed), then failure is returned and it's up to caller |
428 | * to restart the path walk from the beginning in ref-walk mode. |
429 | */ |
430 | |
431 | static inline void lock_rcu_walk(void) |
432 | { |
433 | br_read_lock(&vfsmount_lock); |
434 | rcu_read_lock(); |
435 | } |
436 | |
437 | static inline void unlock_rcu_walk(void) |
438 | { |
439 | rcu_read_unlock(); |
440 | br_read_unlock(&vfsmount_lock); |
441 | } |
442 | |
443 | /** |
444 | * unlazy_walk - try to switch to ref-walk mode. |
445 | * @nd: nameidata pathwalk data |
446 | * @dentry: child of nd->path.dentry or NULL |
447 | * Returns: 0 on success, -ECHILD on failure |
448 | * |
449 | * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry |
450 | * for ref-walk mode. @dentry must be a path found by a do_lookup call on |
451 | * @nd or NULL. Must be called from rcu-walk context. |
452 | */ |
453 | static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) |
454 | { |
455 | struct fs_struct *fs = current->fs; |
456 | struct dentry *parent = nd->path.dentry; |
457 | int want_root = 0; |
458 | |
459 | BUG_ON(!(nd->flags & LOOKUP_RCU)); |
460 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
461 | want_root = 1; |
462 | spin_lock(&fs->lock); |
463 | if (nd->root.mnt != fs->root.mnt || |
464 | nd->root.dentry != fs->root.dentry) |
465 | goto err_root; |
466 | } |
467 | spin_lock(&parent->d_lock); |
468 | if (!dentry) { |
469 | if (!__d_rcu_to_refcount(parent, nd->seq)) |
470 | goto err_parent; |
471 | BUG_ON(nd->inode != parent->d_inode); |
472 | } else { |
473 | if (dentry->d_parent != parent) |
474 | goto err_parent; |
475 | spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); |
476 | if (!__d_rcu_to_refcount(dentry, nd->seq)) |
477 | goto err_child; |
478 | /* |
479 | * If the sequence check on the child dentry passed, then |
480 | * the child has not been removed from its parent. This |
481 | * means the parent dentry must be valid and able to take |
482 | * a reference at this point. |
483 | */ |
484 | BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); |
485 | BUG_ON(!parent->d_count); |
486 | parent->d_count++; |
487 | spin_unlock(&dentry->d_lock); |
488 | } |
489 | spin_unlock(&parent->d_lock); |
490 | if (want_root) { |
491 | path_get(&nd->root); |
492 | spin_unlock(&fs->lock); |
493 | } |
494 | mntget(nd->path.mnt); |
495 | |
496 | unlock_rcu_walk(); |
497 | nd->flags &= ~LOOKUP_RCU; |
498 | return 0; |
499 | |
500 | err_child: |
501 | spin_unlock(&dentry->d_lock); |
502 | err_parent: |
503 | spin_unlock(&parent->d_lock); |
504 | err_root: |
505 | if (want_root) |
506 | spin_unlock(&fs->lock); |
507 | return -ECHILD; |
508 | } |
509 | |
510 | static inline int d_revalidate(struct dentry *dentry, unsigned int flags) |
511 | { |
512 | return dentry->d_op->d_revalidate(dentry, flags); |
513 | } |
514 | |
515 | /** |
516 | * complete_walk - successful completion of path walk |
517 | * @nd: pointer nameidata |
518 | * |
519 | * If we had been in RCU mode, drop out of it and legitimize nd->path. |
520 | * Revalidate the final result, unless we'd already done that during |
521 | * the path walk or the filesystem doesn't ask for it. Return 0 on |
522 | * success, -error on failure. In case of failure caller does not |
523 | * need to drop nd->path. |
524 | */ |
525 | static int complete_walk(struct nameidata *nd) |
526 | { |
527 | struct dentry *dentry = nd->path.dentry; |
528 | int status; |
529 | |
530 | if (nd->flags & LOOKUP_RCU) { |
531 | nd->flags &= ~LOOKUP_RCU; |
532 | if (!(nd->flags & LOOKUP_ROOT)) |
533 | nd->root.mnt = NULL; |
534 | spin_lock(&dentry->d_lock); |
535 | if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) { |
536 | spin_unlock(&dentry->d_lock); |
537 | unlock_rcu_walk(); |
538 | return -ECHILD; |
539 | } |
540 | BUG_ON(nd->inode != dentry->d_inode); |
541 | spin_unlock(&dentry->d_lock); |
542 | mntget(nd->path.mnt); |
543 | unlock_rcu_walk(); |
544 | } |
545 | |
546 | if (likely(!(nd->flags & LOOKUP_JUMPED))) |
547 | return 0; |
548 | |
549 | if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE))) |
550 | return 0; |
551 | |
552 | if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT))) |
553 | return 0; |
554 | |
555 | /* Note: we do not d_invalidate() */ |
556 | status = d_revalidate(dentry, nd->flags); |
557 | if (status > 0) |
558 | return 0; |
559 | |
560 | if (!status) |
561 | status = -ESTALE; |
562 | |
563 | path_put(&nd->path); |
564 | return status; |
565 | } |
566 | |
567 | static __always_inline void set_root(struct nameidata *nd) |
568 | { |
569 | if (!nd->root.mnt) |
570 | get_fs_root(current->fs, &nd->root); |
571 | } |
572 | |
573 | static int link_path_walk(const char *, struct nameidata *); |
574 | |
575 | static __always_inline void set_root_rcu(struct nameidata *nd) |
576 | { |
577 | if (!nd->root.mnt) { |
578 | struct fs_struct *fs = current->fs; |
579 | unsigned seq; |
580 | |
581 | do { |
582 | seq = read_seqcount_begin(&fs->seq); |
583 | nd->root = fs->root; |
584 | nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq); |
585 | } while (read_seqcount_retry(&fs->seq, seq)); |
586 | } |
587 | } |
588 | |
589 | static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
590 | { |
591 | int ret; |
592 | |
593 | if (IS_ERR(link)) |
594 | goto fail; |
595 | |
596 | if (*link == '/') { |
597 | set_root(nd); |
598 | path_put(&nd->path); |
599 | nd->path = nd->root; |
600 | path_get(&nd->root); |
601 | nd->flags |= LOOKUP_JUMPED; |
602 | } |
603 | nd->inode = nd->path.dentry->d_inode; |
604 | |
605 | ret = link_path_walk(link, nd); |
606 | return ret; |
607 | fail: |
608 | path_put(&nd->path); |
609 | return PTR_ERR(link); |
610 | } |
611 | |
612 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
613 | { |
614 | dput(path->dentry); |
615 | if (path->mnt != nd->path.mnt) |
616 | mntput(path->mnt); |
617 | } |
618 | |
619 | static inline void path_to_nameidata(const struct path *path, |
620 | struct nameidata *nd) |
621 | { |
622 | if (!(nd->flags & LOOKUP_RCU)) { |
623 | dput(nd->path.dentry); |
624 | if (nd->path.mnt != path->mnt) |
625 | mntput(nd->path.mnt); |
626 | } |
627 | nd->path.mnt = path->mnt; |
628 | nd->path.dentry = path->dentry; |
629 | } |
630 | |
631 | /* |
632 | * Helper to directly jump to a known parsed path from ->follow_link, |
633 | * caller must have taken a reference to path beforehand. |
634 | */ |
635 | void nd_jump_link(struct nameidata *nd, struct path *path) |
636 | { |
637 | path_put(&nd->path); |
638 | |
639 | nd->path = *path; |
640 | nd->inode = nd->path.dentry->d_inode; |
641 | nd->flags |= LOOKUP_JUMPED; |
642 | |
643 | BUG_ON(nd->inode->i_op->follow_link); |
644 | } |
645 | |
646 | static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) |
647 | { |
648 | struct inode *inode = link->dentry->d_inode; |
649 | if (inode->i_op->put_link) |
650 | inode->i_op->put_link(link->dentry, nd, cookie); |
651 | path_put(link); |
652 | } |
653 | |
654 | int sysctl_protected_symlinks __read_mostly = 1; |
655 | int sysctl_protected_hardlinks __read_mostly = 1; |
656 | |
657 | /** |
658 | * may_follow_link - Check symlink following for unsafe situations |
659 | * @link: The path of the symlink |
660 | * @nd: nameidata pathwalk data |
661 | * |
662 | * In the case of the sysctl_protected_symlinks sysctl being enabled, |
663 | * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is |
664 | * in a sticky world-writable directory. This is to protect privileged |
665 | * processes from failing races against path names that may change out |
666 | * from under them by way of other users creating malicious symlinks. |
667 | * It will permit symlinks to be followed only when outside a sticky |
668 | * world-writable directory, or when the uid of the symlink and follower |
669 | * match, or when the directory owner matches the symlink's owner. |
670 | * |
671 | * Returns 0 if following the symlink is allowed, -ve on error. |
672 | */ |
673 | static inline int may_follow_link(struct path *link, struct nameidata *nd) |
674 | { |
675 | const struct inode *inode; |
676 | const struct inode *parent; |
677 | |
678 | if (!sysctl_protected_symlinks) |
679 | return 0; |
680 | |
681 | /* Allowed if owner and follower match. */ |
682 | inode = link->dentry->d_inode; |
683 | if (current_cred()->fsuid == inode->i_uid) |
684 | return 0; |
685 | |
686 | /* Allowed if parent directory not sticky and world-writable. */ |
687 | parent = nd->path.dentry->d_inode; |
688 | if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) |
689 | return 0; |
690 | |
691 | /* Allowed if parent directory and link owner match. */ |
692 | if (parent->i_uid == inode->i_uid) |
693 | return 0; |
694 | |
695 | path_put_conditional(link, nd); |
696 | path_put(&nd->path); |
697 | audit_log_link_denied("follow_link", link); |
698 | return -EACCES; |
699 | } |
700 | |
701 | /** |
702 | * safe_hardlink_source - Check for safe hardlink conditions |
703 | * @inode: the source inode to hardlink from |
704 | * |
705 | * Return false if at least one of the following conditions: |
706 | * - inode is not a regular file |
707 | * - inode is setuid |
708 | * - inode is setgid and group-exec |
709 | * - access failure for read and write |
710 | * |
711 | * Otherwise returns true. |
712 | */ |
713 | static bool safe_hardlink_source(struct inode *inode) |
714 | { |
715 | umode_t mode = inode->i_mode; |
716 | |
717 | /* Special files should not get pinned to the filesystem. */ |
718 | if (!S_ISREG(mode)) |
719 | return false; |
720 | |
721 | /* Setuid files should not get pinned to the filesystem. */ |
722 | if (mode & S_ISUID) |
723 | return false; |
724 | |
725 | /* Executable setgid files should not get pinned to the filesystem. */ |
726 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) |
727 | return false; |
728 | |
729 | /* Hardlinking to unreadable or unwritable sources is dangerous. */ |
730 | if (inode_permission(inode, MAY_READ | MAY_WRITE)) |
731 | return false; |
732 | |
733 | return true; |
734 | } |
735 | |
736 | /** |
737 | * may_linkat - Check permissions for creating a hardlink |
738 | * @link: the source to hardlink from |
739 | * |
740 | * Block hardlink when all of: |
741 | * - sysctl_protected_hardlinks enabled |
742 | * - fsuid does not match inode |
743 | * - hardlink source is unsafe (see safe_hardlink_source() above) |
744 | * - not CAP_FOWNER |
745 | * |
746 | * Returns 0 if successful, -ve on error. |
747 | */ |
748 | static int may_linkat(struct path *link) |
749 | { |
750 | const struct cred *cred; |
751 | struct inode *inode; |
752 | |
753 | if (!sysctl_protected_hardlinks) |
754 | return 0; |
755 | |
756 | cred = current_cred(); |
757 | inode = link->dentry->d_inode; |
758 | |
759 | /* Source inode owner (or CAP_FOWNER) can hardlink all they like, |
760 | * otherwise, it must be a safe source. |
761 | */ |
762 | if (cred->fsuid == inode->i_uid || safe_hardlink_source(inode) || |
763 | capable(CAP_FOWNER)) |
764 | return 0; |
765 | |
766 | audit_log_link_denied("linkat", link); |
767 | return -EPERM; |
768 | } |
769 | |
770 | static __always_inline int |
771 | follow_link(struct path *link, struct nameidata *nd, void **p) |
772 | { |
773 | struct dentry *dentry = link->dentry; |
774 | int error; |
775 | char *s; |
776 | |
777 | BUG_ON(nd->flags & LOOKUP_RCU); |
778 | |
779 | if (link->mnt == nd->path.mnt) |
780 | mntget(link->mnt); |
781 | |
782 | error = -ELOOP; |
783 | if (unlikely(current->total_link_count >= 40)) |
784 | goto out_put_nd_path; |
785 | |
786 | cond_resched(); |
787 | current->total_link_count++; |
788 | |
789 | touch_atime(link); |
790 | nd_set_link(nd, NULL); |
791 | |
792 | error = security_inode_follow_link(link->dentry, nd); |
793 | if (error) |
794 | goto out_put_nd_path; |
795 | |
796 | nd->last_type = LAST_BIND; |
797 | *p = dentry->d_inode->i_op->follow_link(dentry, nd); |
798 | error = PTR_ERR(*p); |
799 | if (IS_ERR(*p)) |
800 | goto out_put_nd_path; |
801 | |
802 | error = 0; |
803 | s = nd_get_link(nd); |
804 | if (s) { |
805 | error = __vfs_follow_link(nd, s); |
806 | if (unlikely(error)) |
807 | put_link(nd, link, *p); |
808 | } |
809 | |
810 | return error; |
811 | |
812 | out_put_nd_path: |
813 | path_put(&nd->path); |
814 | path_put(link); |
815 | return error; |
816 | } |
817 | |
818 | static int follow_up_rcu(struct path *path) |
819 | { |
820 | struct mount *mnt = real_mount(path->mnt); |
821 | struct mount *parent; |
822 | struct dentry *mountpoint; |
823 | |
824 | parent = mnt->mnt_parent; |
825 | if (&parent->mnt == path->mnt) |
826 | return 0; |
827 | mountpoint = mnt->mnt_mountpoint; |
828 | path->dentry = mountpoint; |
829 | path->mnt = &parent->mnt; |
830 | return 1; |
831 | } |
832 | |
833 | /* |
834 | * follow_up - Find the mountpoint of path's vfsmount |
835 | * |
836 | * Given a path, find the mountpoint of its source file system. |
837 | * Replace @path with the path of the mountpoint in the parent mount. |
838 | * Up is towards /. |
839 | * |
840 | * Return 1 if we went up a level and 0 if we were already at the |
841 | * root. |
842 | */ |
843 | int follow_up(struct path *path) |
844 | { |
845 | struct mount *mnt = real_mount(path->mnt); |
846 | struct mount *parent; |
847 | struct dentry *mountpoint; |
848 | |
849 | br_read_lock(&vfsmount_lock); |
850 | parent = mnt->mnt_parent; |
851 | if (parent == mnt) { |
852 | br_read_unlock(&vfsmount_lock); |
853 | return 0; |
854 | } |
855 | mntget(&parent->mnt); |
856 | mountpoint = dget(mnt->mnt_mountpoint); |
857 | br_read_unlock(&vfsmount_lock); |
858 | dput(path->dentry); |
859 | path->dentry = mountpoint; |
860 | mntput(path->mnt); |
861 | path->mnt = &parent->mnt; |
862 | return 1; |
863 | } |
864 | |
865 | /* |
866 | * Perform an automount |
867 | * - return -EISDIR to tell follow_managed() to stop and return the path we |
868 | * were called with. |
869 | */ |
870 | static int follow_automount(struct path *path, unsigned flags, |
871 | bool *need_mntput) |
872 | { |
873 | struct vfsmount *mnt; |
874 | int err; |
875 | |
876 | if (!path->dentry->d_op || !path->dentry->d_op->d_automount) |
877 | return -EREMOTE; |
878 | |
879 | /* We don't want to mount if someone's just doing a stat - |
880 | * unless they're stat'ing a directory and appended a '/' to |
881 | * the name. |
882 | * |
883 | * We do, however, want to mount if someone wants to open or |
884 | * create a file of any type under the mountpoint, wants to |
885 | * traverse through the mountpoint or wants to open the |
886 | * mounted directory. Also, autofs may mark negative dentries |
887 | * as being automount points. These will need the attentions |
888 | * of the daemon to instantiate them before they can be used. |
889 | */ |
890 | if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | |
891 | LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && |
892 | path->dentry->d_inode) |
893 | return -EISDIR; |
894 | |
895 | current->total_link_count++; |
896 | if (current->total_link_count >= 40) |
897 | return -ELOOP; |
898 | |
899 | mnt = path->dentry->d_op->d_automount(path); |
900 | if (IS_ERR(mnt)) { |
901 | /* |
902 | * The filesystem is allowed to return -EISDIR here to indicate |
903 | * it doesn't want to automount. For instance, autofs would do |
904 | * this so that its userspace daemon can mount on this dentry. |
905 | * |
906 | * However, we can only permit this if it's a terminal point in |
907 | * the path being looked up; if it wasn't then the remainder of |
908 | * the path is inaccessible and we should say so. |
909 | */ |
910 | if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) |
911 | return -EREMOTE; |
912 | return PTR_ERR(mnt); |
913 | } |
914 | |
915 | if (!mnt) /* mount collision */ |
916 | return 0; |
917 | |
918 | if (!*need_mntput) { |
919 | /* lock_mount() may release path->mnt on error */ |
920 | mntget(path->mnt); |
921 | *need_mntput = true; |
922 | } |
923 | err = finish_automount(mnt, path); |
924 | |
925 | switch (err) { |
926 | case -EBUSY: |
927 | /* Someone else made a mount here whilst we were busy */ |
928 | return 0; |
929 | case 0: |
930 | path_put(path); |
931 | path->mnt = mnt; |
932 | path->dentry = dget(mnt->mnt_root); |
933 | return 0; |
934 | default: |
935 | return err; |
936 | } |
937 | |
938 | } |
939 | |
940 | /* |
941 | * Handle a dentry that is managed in some way. |
942 | * - Flagged for transit management (autofs) |
943 | * - Flagged as mountpoint |
944 | * - Flagged as automount point |
945 | * |
946 | * This may only be called in refwalk mode. |
947 | * |
948 | * Serialization is taken care of in namespace.c |
949 | */ |
950 | static int follow_managed(struct path *path, unsigned flags) |
951 | { |
952 | struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ |
953 | unsigned managed; |
954 | bool need_mntput = false; |
955 | int ret = 0; |
956 | |
957 | /* Given that we're not holding a lock here, we retain the value in a |
958 | * local variable for each dentry as we look at it so that we don't see |
959 | * the components of that value change under us */ |
960 | while (managed = ACCESS_ONCE(path->dentry->d_flags), |
961 | managed &= DCACHE_MANAGED_DENTRY, |
962 | unlikely(managed != 0)) { |
963 | /* Allow the filesystem to manage the transit without i_mutex |
964 | * being held. */ |
965 | if (managed & DCACHE_MANAGE_TRANSIT) { |
966 | BUG_ON(!path->dentry->d_op); |
967 | BUG_ON(!path->dentry->d_op->d_manage); |
968 | ret = path->dentry->d_op->d_manage(path->dentry, false); |
969 | if (ret < 0) |
970 | break; |
971 | } |
972 | |
973 | /* Transit to a mounted filesystem. */ |
974 | if (managed & DCACHE_MOUNTED) { |
975 | struct vfsmount *mounted = lookup_mnt(path); |
976 | if (mounted) { |
977 | dput(path->dentry); |
978 | if (need_mntput) |
979 | mntput(path->mnt); |
980 | path->mnt = mounted; |
981 | path->dentry = dget(mounted->mnt_root); |
982 | need_mntput = true; |
983 | continue; |
984 | } |
985 | |
986 | /* Something is mounted on this dentry in another |
987 | * namespace and/or whatever was mounted there in this |
988 | * namespace got unmounted before we managed to get the |
989 | * vfsmount_lock */ |
990 | } |
991 | |
992 | /* Handle an automount point */ |
993 | if (managed & DCACHE_NEED_AUTOMOUNT) { |
994 | ret = follow_automount(path, flags, &need_mntput); |
995 | if (ret < 0) |
996 | break; |
997 | continue; |
998 | } |
999 | |
1000 | /* We didn't change the current path point */ |
1001 | break; |
1002 | } |
1003 | |
1004 | if (need_mntput && path->mnt == mnt) |
1005 | mntput(path->mnt); |
1006 | if (ret == -EISDIR) |
1007 | ret = 0; |
1008 | return ret < 0 ? ret : need_mntput; |
1009 | } |
1010 | |
1011 | int follow_down_one(struct path *path) |
1012 | { |
1013 | struct vfsmount *mounted; |
1014 | |
1015 | mounted = lookup_mnt(path); |
1016 | if (mounted) { |
1017 | dput(path->dentry); |
1018 | mntput(path->mnt); |
1019 | path->mnt = mounted; |
1020 | path->dentry = dget(mounted->mnt_root); |
1021 | return 1; |
1022 | } |
1023 | return 0; |
1024 | } |
1025 | |
1026 | static inline bool managed_dentry_might_block(struct dentry *dentry) |
1027 | { |
1028 | return (dentry->d_flags & DCACHE_MANAGE_TRANSIT && |
1029 | dentry->d_op->d_manage(dentry, true) < 0); |
1030 | } |
1031 | |
1032 | /* |
1033 | * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if |
1034 | * we meet a managed dentry that would need blocking. |
1035 | */ |
1036 | static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, |
1037 | struct inode **inode) |
1038 | { |
1039 | for (;;) { |
1040 | struct mount *mounted; |
1041 | /* |
1042 | * Don't forget we might have a non-mountpoint managed dentry |
1043 | * that wants to block transit. |
1044 | */ |
1045 | if (unlikely(managed_dentry_might_block(path->dentry))) |
1046 | return false; |
1047 | |
1048 | if (!d_mountpoint(path->dentry)) |
1049 | break; |
1050 | |
1051 | mounted = __lookup_mnt(path->mnt, path->dentry, 1); |
1052 | if (!mounted) |
1053 | break; |
1054 | path->mnt = &mounted->mnt; |
1055 | path->dentry = mounted->mnt.mnt_root; |
1056 | nd->flags |= LOOKUP_JUMPED; |
1057 | nd->seq = read_seqcount_begin(&path->dentry->d_seq); |
1058 | /* |
1059 | * Update the inode too. We don't need to re-check the |
1060 | * dentry sequence number here after this d_inode read, |
1061 | * because a mount-point is always pinned. |
1062 | */ |
1063 | *inode = path->dentry->d_inode; |
1064 | } |
1065 | return true; |
1066 | } |
1067 | |
1068 | static void follow_mount_rcu(struct nameidata *nd) |
1069 | { |
1070 | while (d_mountpoint(nd->path.dentry)) { |
1071 | struct mount *mounted; |
1072 | mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1); |
1073 | if (!mounted) |
1074 | break; |
1075 | nd->path.mnt = &mounted->mnt; |
1076 | nd->path.dentry = mounted->mnt.mnt_root; |
1077 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); |
1078 | } |
1079 | } |
1080 | |
1081 | static int follow_dotdot_rcu(struct nameidata *nd) |
1082 | { |
1083 | set_root_rcu(nd); |
1084 | |
1085 | while (1) { |
1086 | if (nd->path.dentry == nd->root.dentry && |
1087 | nd->path.mnt == nd->root.mnt) { |
1088 | break; |
1089 | } |
1090 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
1091 | struct dentry *old = nd->path.dentry; |
1092 | struct dentry *parent = old->d_parent; |
1093 | unsigned seq; |
1094 | |
1095 | seq = read_seqcount_begin(&parent->d_seq); |
1096 | if (read_seqcount_retry(&old->d_seq, nd->seq)) |
1097 | goto failed; |
1098 | nd->path.dentry = parent; |
1099 | nd->seq = seq; |
1100 | break; |
1101 | } |
1102 | if (!follow_up_rcu(&nd->path)) |
1103 | break; |
1104 | nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); |
1105 | } |
1106 | follow_mount_rcu(nd); |
1107 | nd->inode = nd->path.dentry->d_inode; |
1108 | return 0; |
1109 | |
1110 | failed: |
1111 | nd->flags &= ~LOOKUP_RCU; |
1112 | if (!(nd->flags & LOOKUP_ROOT)) |
1113 | nd->root.mnt = NULL; |
1114 | unlock_rcu_walk(); |
1115 | return -ECHILD; |
1116 | } |
1117 | |
1118 | /* |
1119 | * Follow down to the covering mount currently visible to userspace. At each |
1120 | * point, the filesystem owning that dentry may be queried as to whether the |
1121 | * caller is permitted to proceed or not. |
1122 | */ |
1123 | int follow_down(struct path *path) |
1124 | { |
1125 | unsigned managed; |
1126 | int ret; |
1127 | |
1128 | while (managed = ACCESS_ONCE(path->dentry->d_flags), |
1129 | unlikely(managed & DCACHE_MANAGED_DENTRY)) { |
1130 | /* Allow the filesystem to manage the transit without i_mutex |
1131 | * being held. |
1132 | * |
1133 | * We indicate to the filesystem if someone is trying to mount |
1134 | * something here. This gives autofs the chance to deny anyone |
1135 | * other than its daemon the right to mount on its |
1136 | * superstructure. |
1137 | * |
1138 | * The filesystem may sleep at this point. |
1139 | */ |
1140 | if (managed & DCACHE_MANAGE_TRANSIT) { |
1141 | BUG_ON(!path->dentry->d_op); |
1142 | BUG_ON(!path->dentry->d_op->d_manage); |
1143 | ret = path->dentry->d_op->d_manage( |
1144 | path->dentry, false); |
1145 | if (ret < 0) |
1146 | return ret == -EISDIR ? 0 : ret; |
1147 | } |
1148 | |
1149 | /* Transit to a mounted filesystem. */ |
1150 | if (managed & DCACHE_MOUNTED) { |
1151 | struct vfsmount *mounted = lookup_mnt(path); |
1152 | if (!mounted) |
1153 | break; |
1154 | dput(path->dentry); |
1155 | mntput(path->mnt); |
1156 | path->mnt = mounted; |
1157 | path->dentry = dget(mounted->mnt_root); |
1158 | continue; |
1159 | } |
1160 | |
1161 | /* Don't handle automount points here */ |
1162 | break; |
1163 | } |
1164 | return 0; |
1165 | } |
1166 | |
1167 | /* |
1168 | * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() |
1169 | */ |
1170 | static void follow_mount(struct path *path) |
1171 | { |
1172 | while (d_mountpoint(path->dentry)) { |
1173 | struct vfsmount *mounted = lookup_mnt(path); |
1174 | if (!mounted) |
1175 | break; |
1176 | dput(path->dentry); |
1177 | mntput(path->mnt); |
1178 | path->mnt = mounted; |
1179 | path->dentry = dget(mounted->mnt_root); |
1180 | } |
1181 | } |
1182 | |
1183 | static void follow_dotdot(struct nameidata *nd) |
1184 | { |
1185 | set_root(nd); |
1186 | |
1187 | while(1) { |
1188 | struct dentry *old = nd->path.dentry; |
1189 | |
1190 | if (nd->path.dentry == nd->root.dentry && |
1191 | nd->path.mnt == nd->root.mnt) { |
1192 | break; |
1193 | } |
1194 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
1195 | /* rare case of legitimate dget_parent()... */ |
1196 | nd->path.dentry = dget_parent(nd->path.dentry); |
1197 | dput(old); |
1198 | break; |
1199 | } |
1200 | if (!follow_up(&nd->path)) |
1201 | break; |
1202 | } |
1203 | follow_mount(&nd->path); |
1204 | nd->inode = nd->path.dentry->d_inode; |
1205 | } |
1206 | |
1207 | /* |
1208 | * This looks up the name in dcache, possibly revalidates the old dentry and |
1209 | * allocates a new one if not found or not valid. In the need_lookup argument |
1210 | * returns whether i_op->lookup is necessary. |
1211 | * |
1212 | * dir->d_inode->i_mutex must be held |
1213 | */ |
1214 | static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, |
1215 | unsigned int flags, bool *need_lookup) |
1216 | { |
1217 | struct dentry *dentry; |
1218 | int error; |
1219 | |
1220 | *need_lookup = false; |
1221 | dentry = d_lookup(dir, name); |
1222 | if (dentry) { |
1223 | if (d_need_lookup(dentry)) { |
1224 | *need_lookup = true; |
1225 | } else if (dentry->d_flags & DCACHE_OP_REVALIDATE) { |
1226 | error = d_revalidate(dentry, flags); |
1227 | if (unlikely(error <= 0)) { |
1228 | if (error < 0) { |
1229 | dput(dentry); |
1230 | return ERR_PTR(error); |
1231 | } else if (!d_invalidate(dentry)) { |
1232 | dput(dentry); |
1233 | dentry = NULL; |
1234 | } |
1235 | } |
1236 | } |
1237 | } |
1238 | |
1239 | if (!dentry) { |
1240 | dentry = d_alloc(dir, name); |
1241 | if (unlikely(!dentry)) |
1242 | return ERR_PTR(-ENOMEM); |
1243 | |
1244 | *need_lookup = true; |
1245 | } |
1246 | return dentry; |
1247 | } |
1248 | |
1249 | /* |
1250 | * Call i_op->lookup on the dentry. The dentry must be negative but may be |
1251 | * hashed if it was pouplated with DCACHE_NEED_LOOKUP. |
1252 | * |
1253 | * dir->d_inode->i_mutex must be held |
1254 | */ |
1255 | static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, |
1256 | unsigned int flags) |
1257 | { |
1258 | struct dentry *old; |
1259 | |
1260 | /* Don't create child dentry for a dead directory. */ |
1261 | if (unlikely(IS_DEADDIR(dir))) { |
1262 | dput(dentry); |
1263 | return ERR_PTR(-ENOENT); |
1264 | } |
1265 | |
1266 | old = dir->i_op->lookup(dir, dentry, flags); |
1267 | if (unlikely(old)) { |
1268 | dput(dentry); |
1269 | dentry = old; |
1270 | } |
1271 | return dentry; |
1272 | } |
1273 | |
1274 | static struct dentry *__lookup_hash(struct qstr *name, |
1275 | struct dentry *base, unsigned int flags) |
1276 | { |
1277 | bool need_lookup; |
1278 | struct dentry *dentry; |
1279 | |
1280 | dentry = lookup_dcache(name, base, flags, &need_lookup); |
1281 | if (!need_lookup) |
1282 | return dentry; |
1283 | |
1284 | return lookup_real(base->d_inode, dentry, flags); |
1285 | } |
1286 | |
1287 | /* |
1288 | * It's more convoluted than I'd like it to be, but... it's still fairly |
1289 | * small and for now I'd prefer to have fast path as straight as possible. |
1290 | * It _is_ time-critical. |
1291 | */ |
1292 | static int lookup_fast(struct nameidata *nd, struct qstr *name, |
1293 | struct path *path, struct inode **inode) |
1294 | { |
1295 | struct vfsmount *mnt = nd->path.mnt; |
1296 | struct dentry *dentry, *parent = nd->path.dentry; |
1297 | int need_reval = 1; |
1298 | int status = 1; |
1299 | int err; |
1300 | |
1301 | /* |
1302 | * Rename seqlock is not required here because in the off chance |
1303 | * of a false negative due to a concurrent rename, we're going to |
1304 | * do the non-racy lookup, below. |
1305 | */ |
1306 | if (nd->flags & LOOKUP_RCU) { |
1307 | unsigned seq; |
1308 | dentry = __d_lookup_rcu(parent, name, &seq, nd->inode); |
1309 | if (!dentry) |
1310 | goto unlazy; |
1311 | |
1312 | /* |
1313 | * This sequence count validates that the inode matches |
1314 | * the dentry name information from lookup. |
1315 | */ |
1316 | *inode = dentry->d_inode; |
1317 | if (read_seqcount_retry(&dentry->d_seq, seq)) |
1318 | return -ECHILD; |
1319 | |
1320 | /* |
1321 | * This sequence count validates that the parent had no |
1322 | * changes while we did the lookup of the dentry above. |
1323 | * |
1324 | * The memory barrier in read_seqcount_begin of child is |
1325 | * enough, we can use __read_seqcount_retry here. |
1326 | */ |
1327 | if (__read_seqcount_retry(&parent->d_seq, nd->seq)) |
1328 | return -ECHILD; |
1329 | nd->seq = seq; |
1330 | |
1331 | if (unlikely(d_need_lookup(dentry))) |
1332 | goto unlazy; |
1333 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { |
1334 | status = d_revalidate(dentry, nd->flags); |
1335 | if (unlikely(status <= 0)) { |
1336 | if (status != -ECHILD) |
1337 | need_reval = 0; |
1338 | goto unlazy; |
1339 | } |
1340 | } |
1341 | path->mnt = mnt; |
1342 | path->dentry = dentry; |
1343 | if (unlikely(!__follow_mount_rcu(nd, path, inode))) |
1344 | goto unlazy; |
1345 | if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT)) |
1346 | goto unlazy; |
1347 | return 0; |
1348 | unlazy: |
1349 | if (unlazy_walk(nd, dentry)) |
1350 | return -ECHILD; |
1351 | } else { |
1352 | dentry = __d_lookup(parent, name); |
1353 | } |
1354 | |
1355 | if (unlikely(!dentry)) |
1356 | goto need_lookup; |
1357 | |
1358 | if (unlikely(d_need_lookup(dentry))) { |
1359 | dput(dentry); |
1360 | goto need_lookup; |
1361 | } |
1362 | |
1363 | if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) |
1364 | status = d_revalidate(dentry, nd->flags); |
1365 | if (unlikely(status <= 0)) { |
1366 | if (status < 0) { |
1367 | dput(dentry); |
1368 | return status; |
1369 | } |
1370 | if (!d_invalidate(dentry)) { |
1371 | dput(dentry); |
1372 | goto need_lookup; |
1373 | } |
1374 | } |
1375 | |
1376 | path->mnt = mnt; |
1377 | path->dentry = dentry; |
1378 | err = follow_managed(path, nd->flags); |
1379 | if (unlikely(err < 0)) { |
1380 | path_put_conditional(path, nd); |
1381 | return err; |
1382 | } |
1383 | if (err) |
1384 | nd->flags |= LOOKUP_JUMPED; |
1385 | *inode = path->dentry->d_inode; |
1386 | return 0; |
1387 | |
1388 | need_lookup: |
1389 | return 1; |
1390 | } |
1391 | |
1392 | /* Fast lookup failed, do it the slow way */ |
1393 | static int lookup_slow(struct nameidata *nd, struct qstr *name, |
1394 | struct path *path) |
1395 | { |
1396 | struct dentry *dentry, *parent; |
1397 | int err; |
1398 | |
1399 | parent = nd->path.dentry; |
1400 | BUG_ON(nd->inode != parent->d_inode); |
1401 | |
1402 | mutex_lock(&parent->d_inode->i_mutex); |
1403 | dentry = __lookup_hash(name, parent, nd->flags); |
1404 | mutex_unlock(&parent->d_inode->i_mutex); |
1405 | if (IS_ERR(dentry)) |
1406 | return PTR_ERR(dentry); |
1407 | path->mnt = nd->path.mnt; |
1408 | path->dentry = dentry; |
1409 | err = follow_managed(path, nd->flags); |
1410 | if (unlikely(err < 0)) { |
1411 | path_put_conditional(path, nd); |
1412 | return err; |
1413 | } |
1414 | if (err) |
1415 | nd->flags |= LOOKUP_JUMPED; |
1416 | return 0; |
1417 | } |
1418 | |
1419 | static inline int may_lookup(struct nameidata *nd) |
1420 | { |
1421 | if (nd->flags & LOOKUP_RCU) { |
1422 | int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); |
1423 | if (err != -ECHILD) |
1424 | return err; |
1425 | if (unlazy_walk(nd, NULL)) |
1426 | return -ECHILD; |
1427 | } |
1428 | return inode_permission(nd->inode, MAY_EXEC); |
1429 | } |
1430 | |
1431 | static inline int handle_dots(struct nameidata *nd, int type) |
1432 | { |
1433 | if (type == LAST_DOTDOT) { |
1434 | if (nd->flags & LOOKUP_RCU) { |
1435 | if (follow_dotdot_rcu(nd)) |
1436 | return -ECHILD; |
1437 | } else |
1438 | follow_dotdot(nd); |
1439 | } |
1440 | return 0; |
1441 | } |
1442 | |
1443 | static void terminate_walk(struct nameidata *nd) |
1444 | { |
1445 | if (!(nd->flags & LOOKUP_RCU)) { |
1446 | path_put(&nd->path); |
1447 | } else { |
1448 | nd->flags &= ~LOOKUP_RCU; |
1449 | if (!(nd->flags & LOOKUP_ROOT)) |
1450 | nd->root.mnt = NULL; |
1451 | unlock_rcu_walk(); |
1452 | } |
1453 | } |
1454 | |
1455 | /* |
1456 | * Do we need to follow links? We _really_ want to be able |
1457 | * to do this check without having to look at inode->i_op, |
1458 | * so we keep a cache of "no, this doesn't need follow_link" |
1459 | * for the common case. |
1460 | */ |
1461 | static inline int should_follow_link(struct inode *inode, int follow) |
1462 | { |
1463 | if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) { |
1464 | if (likely(inode->i_op->follow_link)) |
1465 | return follow; |
1466 | |
1467 | /* This gets set once for the inode lifetime */ |
1468 | spin_lock(&inode->i_lock); |
1469 | inode->i_opflags |= IOP_NOFOLLOW; |
1470 | spin_unlock(&inode->i_lock); |
1471 | } |
1472 | return 0; |
1473 | } |
1474 | |
1475 | static inline int walk_component(struct nameidata *nd, struct path *path, |
1476 | struct qstr *name, int type, int follow) |
1477 | { |
1478 | struct inode *inode; |
1479 | int err; |
1480 | /* |
1481 | * "." and ".." are special - ".." especially so because it has |
1482 | * to be able to know about the current root directory and |
1483 | * parent relationships. |
1484 | */ |
1485 | if (unlikely(type != LAST_NORM)) |
1486 | return handle_dots(nd, type); |
1487 | err = lookup_fast(nd, name, path, &inode); |
1488 | if (unlikely(err)) { |
1489 | if (err < 0) |
1490 | goto out_err; |
1491 | |
1492 | err = lookup_slow(nd, name, path); |
1493 | if (err < 0) |
1494 | goto out_err; |
1495 | |
1496 | inode = path->dentry->d_inode; |
1497 | } |
1498 | err = -ENOENT; |
1499 | if (!inode) |
1500 | goto out_path_put; |
1501 | |
1502 | if (should_follow_link(inode, follow)) { |
1503 | if (nd->flags & LOOKUP_RCU) { |
1504 | if (unlikely(unlazy_walk(nd, path->dentry))) { |
1505 | err = -ECHILD; |
1506 | goto out_err; |
1507 | } |
1508 | } |
1509 | BUG_ON(inode != path->dentry->d_inode); |
1510 | return 1; |
1511 | } |
1512 | path_to_nameidata(path, nd); |
1513 | nd->inode = inode; |
1514 | return 0; |
1515 | |
1516 | out_path_put: |
1517 | path_to_nameidata(path, nd); |
1518 | out_err: |
1519 | terminate_walk(nd); |
1520 | return err; |
1521 | } |
1522 | |
1523 | /* |
1524 | * This limits recursive symlink follows to 8, while |
1525 | * limiting consecutive symlinks to 40. |
1526 | * |
1527 | * Without that kind of total limit, nasty chains of consecutive |
1528 | * symlinks can cause almost arbitrarily long lookups. |
1529 | */ |
1530 | static inline int nested_symlink(struct path *path, struct nameidata *nd) |
1531 | { |
1532 | int res; |
1533 | |
1534 | if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { |
1535 | path_put_conditional(path, nd); |
1536 | path_put(&nd->path); |
1537 | return -ELOOP; |
1538 | } |
1539 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); |
1540 | |
1541 | nd->depth++; |
1542 | current->link_count++; |
1543 | |
1544 | do { |
1545 | struct path link = *path; |
1546 | void *cookie; |
1547 | |
1548 | res = follow_link(&link, nd, &cookie); |
1549 | if (res) |
1550 | break; |
1551 | res = walk_component(nd, path, &nd->last, |
1552 | nd->last_type, LOOKUP_FOLLOW); |
1553 | put_link(nd, &link, cookie); |
1554 | } while (res > 0); |
1555 | |
1556 | current->link_count--; |
1557 | nd->depth--; |
1558 | return res; |
1559 | } |
1560 | |
1561 | /* |
1562 | * We really don't want to look at inode->i_op->lookup |
1563 | * when we don't have to. So we keep a cache bit in |
1564 | * the inode ->i_opflags field that says "yes, we can |
1565 | * do lookup on this inode". |
1566 | */ |
1567 | static inline int can_lookup(struct inode *inode) |
1568 | { |
1569 | if (likely(inode->i_opflags & IOP_LOOKUP)) |
1570 | return 1; |
1571 | if (likely(!inode->i_op->lookup)) |
1572 | return 0; |
1573 | |
1574 | /* We do this once for the lifetime of the inode */ |
1575 | spin_lock(&inode->i_lock); |
1576 | inode->i_opflags |= IOP_LOOKUP; |
1577 | spin_unlock(&inode->i_lock); |
1578 | return 1; |
1579 | } |
1580 | |
1581 | /* |
1582 | * We can do the critical dentry name comparison and hashing |
1583 | * operations one word at a time, but we are limited to: |
1584 | * |
1585 | * - Architectures with fast unaligned word accesses. We could |
1586 | * do a "get_unaligned()" if this helps and is sufficiently |
1587 | * fast. |
1588 | * |
1589 | * - Little-endian machines (so that we can generate the mask |
1590 | * of low bytes efficiently). Again, we *could* do a byte |
1591 | * swapping load on big-endian architectures if that is not |
1592 | * expensive enough to make the optimization worthless. |
1593 | * |
1594 | * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we |
1595 | * do not trap on the (extremely unlikely) case of a page |
1596 | * crossing operation. |
1597 | * |
1598 | * - Furthermore, we need an efficient 64-bit compile for the |
1599 | * 64-bit case in order to generate the "number of bytes in |
1600 | * the final mask". Again, that could be replaced with a |
1601 | * efficient population count instruction or similar. |
1602 | */ |
1603 | #ifdef CONFIG_DCACHE_WORD_ACCESS |
1604 | |
1605 | #include <asm/word-at-a-time.h> |
1606 | |
1607 | #ifdef CONFIG_64BIT |
1608 | |
1609 | static inline unsigned int fold_hash(unsigned long hash) |
1610 | { |
1611 | hash += hash >> (8*sizeof(int)); |
1612 | return hash; |
1613 | } |
1614 | |
1615 | #else /* 32-bit case */ |
1616 | |
1617 | #define fold_hash(x) (x) |
1618 | |
1619 | #endif |
1620 | |
1621 | unsigned int full_name_hash(const unsigned char *name, unsigned int len) |
1622 | { |
1623 | unsigned long a, mask; |
1624 | unsigned long hash = 0; |
1625 | |
1626 | for (;;) { |
1627 | a = load_unaligned_zeropad(name); |
1628 | if (len < sizeof(unsigned long)) |
1629 | break; |
1630 | hash += a; |
1631 | hash *= 9; |
1632 | name += sizeof(unsigned long); |
1633 | len -= sizeof(unsigned long); |
1634 | if (!len) |
1635 | goto done; |
1636 | } |
1637 | mask = ~(~0ul << len*8); |
1638 | hash += mask & a; |
1639 | done: |
1640 | return fold_hash(hash); |
1641 | } |
1642 | EXPORT_SYMBOL(full_name_hash); |
1643 | |
1644 | /* |
1645 | * Calculate the length and hash of the path component, and |
1646 | * return the length of the component; |
1647 | */ |
1648 | static inline unsigned long hash_name(const char *name, unsigned int *hashp) |
1649 | { |
1650 | unsigned long a, b, adata, bdata, mask, hash, len; |
1651 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; |
1652 | |
1653 | hash = a = 0; |
1654 | len = -sizeof(unsigned long); |
1655 | do { |
1656 | hash = (hash + a) * 9; |
1657 | len += sizeof(unsigned long); |
1658 | a = load_unaligned_zeropad(name+len); |
1659 | b = a ^ REPEAT_BYTE('/'); |
1660 | } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); |
1661 | |
1662 | adata = prep_zero_mask(a, adata, &constants); |
1663 | bdata = prep_zero_mask(b, bdata, &constants); |
1664 | |
1665 | mask = create_zero_mask(adata | bdata); |
1666 | |
1667 | hash += a & zero_bytemask(mask); |
1668 | *hashp = fold_hash(hash); |
1669 | |
1670 | return len + find_zero(mask); |
1671 | } |
1672 | |
1673 | #else |
1674 | |
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 | } |
1682 | EXPORT_SYMBOL(full_name_hash); |
1683 | |
1684 | /* |
1685 | * We know there's a real path component here of at least |
1686 | * one character. |
1687 | */ |
1688 | static inline unsigned long hash_name(const char *name, unsigned int *hashp) |
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 != '/'); |
1699 | *hashp = end_name_hash(hash); |
1700 | return len; |
1701 | } |
1702 | |
1703 | #endif |
1704 | |
1705 | /* |
1706 | * Name resolution. |
1707 | * This is the basic name resolution function, turning a pathname into |
1708 | * the final dentry. We expect 'base' to be positive and a directory. |
1709 | * |
1710 | * Returns 0 and nd will have valid dentry and mnt on success. |
1711 | * Returns error and drops reference to input namei data on failure. |
1712 | */ |
1713 | static int link_path_walk(const char *name, struct nameidata *nd) |
1714 | { |
1715 | struct path next; |
1716 | int err; |
1717 | |
1718 | while (*name=='/') |
1719 | name++; |
1720 | if (!*name) |
1721 | return 0; |
1722 | |
1723 | /* At this point we know we have a real path component. */ |
1724 | for(;;) { |
1725 | struct qstr this; |
1726 | long len; |
1727 | int type; |
1728 | |
1729 | err = may_lookup(nd); |
1730 | if (err) |
1731 | break; |
1732 | |
1733 | len = hash_name(name, &this.hash); |
1734 | this.name = name; |
1735 | this.len = len; |
1736 | |
1737 | type = LAST_NORM; |
1738 | if (name[0] == '.') switch (len) { |
1739 | case 2: |
1740 | if (name[1] == '.') { |
1741 | type = LAST_DOTDOT; |
1742 | nd->flags |= LOOKUP_JUMPED; |
1743 | } |
1744 | break; |
1745 | case 1: |
1746 | type = LAST_DOT; |
1747 | } |
1748 | if (likely(type == LAST_NORM)) { |
1749 | struct dentry *parent = nd->path.dentry; |
1750 | nd->flags &= ~LOOKUP_JUMPED; |
1751 | if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { |
1752 | err = parent->d_op->d_hash(parent, nd->inode, |
1753 | &this); |
1754 | if (err < 0) |
1755 | break; |
1756 | } |
1757 | } |
1758 | |
1759 | if (!name[len]) |
1760 | goto last_component; |
1761 | /* |
1762 | * If it wasn't NUL, we know it was '/'. Skip that |
1763 | * slash, and continue until no more slashes. |
1764 | */ |
1765 | do { |
1766 | len++; |
1767 | } while (unlikely(name[len] == '/')); |
1768 | if (!name[len]) |
1769 | goto last_component; |
1770 | name += len; |
1771 | |
1772 | err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW); |
1773 | if (err < 0) |
1774 | return err; |
1775 | |
1776 | if (err) { |
1777 | err = nested_symlink(&next, nd); |
1778 | if (err) |
1779 | return err; |
1780 | } |
1781 | if (can_lookup(nd->inode)) |
1782 | continue; |
1783 | err = -ENOTDIR; |
1784 | break; |
1785 | /* here ends the main loop */ |
1786 | |
1787 | last_component: |
1788 | nd->last = this; |
1789 | nd->last_type = type; |
1790 | return 0; |
1791 | } |
1792 | terminate_walk(nd); |
1793 | return err; |
1794 | } |
1795 | |
1796 | static int path_init(int dfd, const char *name, unsigned int flags, |
1797 | struct nameidata *nd, struct file **fp) |
1798 | { |
1799 | int retval = 0; |
1800 | int fput_needed; |
1801 | struct file *file; |
1802 | |
1803 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ |
1804 | nd->flags = flags | LOOKUP_JUMPED; |
1805 | nd->depth = 0; |
1806 | if (flags & LOOKUP_ROOT) { |
1807 | struct inode *inode = nd->root.dentry->d_inode; |
1808 | if (*name) { |
1809 | if (!inode->i_op->lookup) |
1810 | return -ENOTDIR; |
1811 | retval = inode_permission(inode, MAY_EXEC); |
1812 | if (retval) |
1813 | return retval; |
1814 | } |
1815 | nd->path = nd->root; |
1816 | nd->inode = inode; |
1817 | if (flags & LOOKUP_RCU) { |
1818 | lock_rcu_walk(); |
1819 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
1820 | } else { |
1821 | path_get(&nd->path); |
1822 | } |
1823 | return 0; |
1824 | } |
1825 | |
1826 | nd->root.mnt = NULL; |
1827 | |
1828 | if (*name=='/') { |
1829 | if (flags & LOOKUP_RCU) { |
1830 | lock_rcu_walk(); |
1831 | set_root_rcu(nd); |
1832 | } else { |
1833 | set_root(nd); |
1834 | path_get(&nd->root); |
1835 | } |
1836 | nd->path = nd->root; |
1837 | } else if (dfd == AT_FDCWD) { |
1838 | if (flags & LOOKUP_RCU) { |
1839 | struct fs_struct *fs = current->fs; |
1840 | unsigned seq; |
1841 | |
1842 | lock_rcu_walk(); |
1843 | |
1844 | do { |
1845 | seq = read_seqcount_begin(&fs->seq); |
1846 | nd->path = fs->pwd; |
1847 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
1848 | } while (read_seqcount_retry(&fs->seq, seq)); |
1849 | } else { |
1850 | get_fs_pwd(current->fs, &nd->path); |
1851 | } |
1852 | } else { |
1853 | struct dentry *dentry; |
1854 | |
1855 | file = fget_raw_light(dfd, &fput_needed); |
1856 | retval = -EBADF; |
1857 | if (!file) |
1858 | goto out_fail; |
1859 | |
1860 | dentry = file->f_path.dentry; |
1861 | |
1862 | if (*name) { |
1863 | retval = -ENOTDIR; |
1864 | if (!S_ISDIR(dentry->d_inode->i_mode)) |
1865 | goto fput_fail; |
1866 | |
1867 | retval = inode_permission(dentry->d_inode, MAY_EXEC); |
1868 | if (retval) |
1869 | goto fput_fail; |
1870 | } |
1871 | |
1872 | nd->path = file->f_path; |
1873 | if (flags & LOOKUP_RCU) { |
1874 | if (fput_needed) |
1875 | *fp = file; |
1876 | nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); |
1877 | lock_rcu_walk(); |
1878 | } else { |
1879 | path_get(&file->f_path); |
1880 | fput_light(file, fput_needed); |
1881 | } |
1882 | } |
1883 | |
1884 | nd->inode = nd->path.dentry->d_inode; |
1885 | return 0; |
1886 | |
1887 | fput_fail: |
1888 | fput_light(file, fput_needed); |
1889 | out_fail: |
1890 | return retval; |
1891 | } |
1892 | |
1893 | static inline int lookup_last(struct nameidata *nd, struct path *path) |
1894 | { |
1895 | if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) |
1896 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; |
1897 | |
1898 | nd->flags &= ~LOOKUP_PARENT; |
1899 | return walk_component(nd, path, &nd->last, nd->last_type, |
1900 | nd->flags & LOOKUP_FOLLOW); |
1901 | } |
1902 | |
1903 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
1904 | static int path_lookupat(int dfd, const char *name, |
1905 | unsigned int flags, struct nameidata *nd) |
1906 | { |
1907 | struct file *base = NULL; |
1908 | struct path path; |
1909 | int err; |
1910 | |
1911 | /* |
1912 | * Path walking is largely split up into 2 different synchronisation |
1913 | * schemes, rcu-walk and ref-walk (explained in |
1914 | * Documentation/filesystems/path-lookup.txt). These share much of the |
1915 | * path walk code, but some things particularly setup, cleanup, and |
1916 | * following mounts are sufficiently divergent that functions are |
1917 | * duplicated. Typically there is a function foo(), and its RCU |
1918 | * analogue, foo_rcu(). |
1919 | * |
1920 | * -ECHILD is the error number of choice (just to avoid clashes) that |
1921 | * is returned if some aspect of an rcu-walk fails. Such an error must |
1922 | * be handled by restarting a traditional ref-walk (which will always |
1923 | * be able to complete). |
1924 | */ |
1925 | err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base); |
1926 | |
1927 | if (unlikely(err)) |
1928 | return err; |
1929 | |
1930 | current->total_link_count = 0; |
1931 | err = link_path_walk(name, nd); |
1932 | |
1933 | if (!err && !(flags & LOOKUP_PARENT)) { |
1934 | err = lookup_last(nd, &path); |
1935 | while (err > 0) { |
1936 | void *cookie; |
1937 | struct path link = path; |
1938 | err = may_follow_link(&link, nd); |
1939 | if (unlikely(err)) |
1940 | break; |
1941 | nd->flags |= LOOKUP_PARENT; |
1942 | err = follow_link(&link, nd, &cookie); |
1943 | if (err) |
1944 | break; |
1945 | err = lookup_last(nd, &path); |
1946 | put_link(nd, &link, cookie); |
1947 | } |
1948 | } |
1949 | |
1950 | if (!err) |
1951 | err = complete_walk(nd); |
1952 | |
1953 | if (!err && nd->flags & LOOKUP_DIRECTORY) { |
1954 | if (!nd->inode->i_op->lookup) { |
1955 | path_put(&nd->path); |
1956 | err = -ENOTDIR; |
1957 | } |
1958 | } |
1959 | |
1960 | if (base) |
1961 | fput(base); |
1962 | |
1963 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { |
1964 | path_put(&nd->root); |
1965 | nd->root.mnt = NULL; |
1966 | } |
1967 | return err; |
1968 | } |
1969 | |
1970 | static int do_path_lookup(int dfd, const char *name, |
1971 | unsigned int flags, struct nameidata *nd) |
1972 | { |
1973 | int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); |
1974 | if (unlikely(retval == -ECHILD)) |
1975 | retval = path_lookupat(dfd, name, flags, nd); |
1976 | if (unlikely(retval == -ESTALE)) |
1977 | retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); |
1978 | |
1979 | if (likely(!retval)) { |
1980 | if (unlikely(!audit_dummy_context())) { |
1981 | if (nd->path.dentry && nd->inode) |
1982 | audit_inode(name, nd->path.dentry); |
1983 | } |
1984 | } |
1985 | return retval; |
1986 | } |
1987 | |
1988 | /* does lookup, returns the object with parent locked */ |
1989 | struct dentry *kern_path_locked(const char *name, struct path *path) |
1990 | { |
1991 | struct nameidata nd; |
1992 | struct dentry *d; |
1993 | int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd); |
1994 | if (err) |
1995 | return ERR_PTR(err); |
1996 | if (nd.last_type != LAST_NORM) { |
1997 | path_put(&nd.path); |
1998 | return ERR_PTR(-EINVAL); |
1999 | } |
2000 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
2001 | d = __lookup_hash(&nd.last, nd.path.dentry, 0); |
2002 | if (IS_ERR(d)) { |
2003 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
2004 | path_put(&nd.path); |
2005 | return d; |
2006 | } |
2007 | *path = nd.path; |
2008 | return d; |
2009 | } |
2010 | |
2011 | int kern_path(const char *name, unsigned int flags, struct path *path) |
2012 | { |
2013 | struct nameidata nd; |
2014 | int res = do_path_lookup(AT_FDCWD, name, flags, &nd); |
2015 | if (!res) |
2016 | *path = nd.path; |
2017 | return res; |
2018 | } |
2019 | |
2020 | /** |
2021 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair |
2022 | * @dentry: pointer to dentry of the base directory |
2023 | * @mnt: pointer to vfs mount of the base directory |
2024 | * @name: pointer to file name |
2025 | * @flags: lookup flags |
2026 | * @path: pointer to struct path to fill |
2027 | */ |
2028 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, |
2029 | const char *name, unsigned int flags, |
2030 | struct path *path) |
2031 | { |
2032 | struct nameidata nd; |
2033 | int err; |
2034 | nd.root.dentry = dentry; |
2035 | nd.root.mnt = mnt; |
2036 | BUG_ON(flags & LOOKUP_PARENT); |
2037 | /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */ |
2038 | err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd); |
2039 | if (!err) |
2040 | *path = nd.path; |
2041 | return err; |
2042 | } |
2043 | |
2044 | /* |
2045 | * Restricted form of lookup. Doesn't follow links, single-component only, |
2046 | * needs parent already locked. Doesn't follow mounts. |
2047 | * SMP-safe. |
2048 | */ |
2049 | static struct dentry *lookup_hash(struct nameidata *nd) |
2050 | { |
2051 | return __lookup_hash(&nd->last, nd->path.dentry, nd->flags); |
2052 | } |
2053 | |
2054 | /** |
2055 | * lookup_one_len - filesystem helper to lookup single pathname component |
2056 | * @name: pathname component to lookup |
2057 | * @base: base directory to lookup from |
2058 | * @len: maximum length @len should be interpreted to |
2059 | * |
2060 | * Note that this routine is purely a helper for filesystem usage and should |
2061 | * not be called by generic code. Also note that by using this function the |
2062 | * nameidata argument is passed to the filesystem methods and a filesystem |
2063 | * using this helper needs to be prepared for that. |
2064 | */ |
2065 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
2066 | { |
2067 | struct qstr this; |
2068 | unsigned int c; |
2069 | int err; |
2070 | |
2071 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
2072 | |
2073 | this.name = name; |
2074 | this.len = len; |
2075 | this.hash = full_name_hash(name, len); |
2076 | if (!len) |
2077 | return ERR_PTR(-EACCES); |
2078 | |
2079 | while (len--) { |
2080 | c = *(const unsigned char *)name++; |
2081 | if (c == '/' || c == '\0') |
2082 | return ERR_PTR(-EACCES); |
2083 | } |
2084 | /* |
2085 | * See if the low-level filesystem might want |
2086 | * to use its own hash.. |
2087 | */ |
2088 | if (base->d_flags & DCACHE_OP_HASH) { |
2089 | int err = base->d_op->d_hash(base, base->d_inode, &this); |
2090 | if (err < 0) |
2091 | return ERR_PTR(err); |
2092 | } |
2093 | |
2094 | err = inode_permission(base->d_inode, MAY_EXEC); |
2095 | if (err) |
2096 | return ERR_PTR(err); |
2097 | |
2098 | return __lookup_hash(&this, base, 0); |
2099 | } |
2100 | |
2101 | int user_path_at_empty(int dfd, const char __user *name, unsigned flags, |
2102 | struct path *path, int *empty) |
2103 | { |
2104 | struct nameidata nd; |
2105 | char *tmp = getname_flags(name, flags, empty); |
2106 | int err = PTR_ERR(tmp); |
2107 | if (!IS_ERR(tmp)) { |
2108 | |
2109 | BUG_ON(flags & LOOKUP_PARENT); |
2110 | |
2111 | err = do_path_lookup(dfd, tmp, flags, &nd); |
2112 | putname(tmp); |
2113 | if (!err) |
2114 | *path = nd.path; |
2115 | } |
2116 | return err; |
2117 | } |
2118 | |
2119 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
2120 | struct path *path) |
2121 | { |
2122 | return user_path_at_empty(dfd, name, flags, path, NULL); |
2123 | } |
2124 | |
2125 | static int user_path_parent(int dfd, const char __user *path, |
2126 | struct nameidata *nd, char **name) |
2127 | { |
2128 | char *s = getname(path); |
2129 | int error; |
2130 | |
2131 | if (IS_ERR(s)) |
2132 | return PTR_ERR(s); |
2133 | |
2134 | error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); |
2135 | if (error) |
2136 | putname(s); |
2137 | else |
2138 | *name = s; |
2139 | |
2140 | return error; |
2141 | } |
2142 | |
2143 | /* |
2144 | * It's inline, so penalty for filesystems that don't use sticky bit is |
2145 | * minimal. |
2146 | */ |
2147 | static inline int check_sticky(struct inode *dir, struct inode *inode) |
2148 | { |
2149 | kuid_t fsuid = current_fsuid(); |
2150 | |
2151 | if (!(dir->i_mode & S_ISVTX)) |
2152 | return 0; |
2153 | if (uid_eq(inode->i_uid, fsuid)) |
2154 | return 0; |
2155 | if (uid_eq(dir->i_uid, fsuid)) |
2156 | return 0; |
2157 | return !inode_capable(inode, CAP_FOWNER); |
2158 | } |
2159 | |
2160 | /* |
2161 | * Check whether we can remove a link victim from directory dir, check |
2162 | * whether the type of victim is right. |
2163 | * 1. We can't do it if dir is read-only (done in permission()) |
2164 | * 2. We should have write and exec permissions on dir |
2165 | * 3. We can't remove anything from append-only dir |
2166 | * 4. We can't do anything with immutable dir (done in permission()) |
2167 | * 5. If the sticky bit on dir is set we should either |
2168 | * a. be owner of dir, or |
2169 | * b. be owner of victim, or |
2170 | * c. have CAP_FOWNER capability |
2171 | * 6. If the victim is append-only or immutable we can't do antyhing with |
2172 | * links pointing to it. |
2173 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. |
2174 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. |
2175 | * 9. We can't remove a root or mountpoint. |
2176 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by |
2177 | * nfs_async_unlink(). |
2178 | */ |
2179 | static int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
2180 | { |
2181 | int error; |
2182 | |
2183 | if (!victim->d_inode) |
2184 | return -ENOENT; |
2185 | |
2186 | BUG_ON(victim->d_parent->d_inode != dir); |
2187 | audit_inode_child(victim, dir); |
2188 | |
2189 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
2190 | if (error) |
2191 | return error; |
2192 | if (IS_APPEND(dir)) |
2193 | return -EPERM; |
2194 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| |
2195 | IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) |
2196 | return -EPERM; |
2197 | if (isdir) { |
2198 | if (!S_ISDIR(victim->d_inode->i_mode)) |
2199 | return -ENOTDIR; |
2200 | if (IS_ROOT(victim)) |
2201 | return -EBUSY; |
2202 | } else if (S_ISDIR(victim->d_inode->i_mode)) |
2203 | return -EISDIR; |
2204 | if (IS_DEADDIR(dir)) |
2205 | return -ENOENT; |
2206 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) |
2207 | return -EBUSY; |
2208 | return 0; |
2209 | } |
2210 | |
2211 | /* Check whether we can create an object with dentry child in directory |
2212 | * dir. |
2213 | * 1. We can't do it if child already exists (open has special treatment for |
2214 | * this case, but since we are inlined it's OK) |
2215 | * 2. We can't do it if dir is read-only (done in permission()) |
2216 | * 3. We should have write and exec permissions on dir |
2217 | * 4. We can't do it if dir is immutable (done in permission()) |
2218 | */ |
2219 | static inline int may_create(struct inode *dir, struct dentry *child) |
2220 | { |
2221 | if (child->d_inode) |
2222 | return -EEXIST; |
2223 | if (IS_DEADDIR(dir)) |
2224 | return -ENOENT; |
2225 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
2226 | } |
2227 | |
2228 | /* |
2229 | * p1 and p2 should be directories on the same fs. |
2230 | */ |
2231 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) |
2232 | { |
2233 | struct dentry *p; |
2234 | |
2235 | if (p1 == p2) { |
2236 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
2237 | return NULL; |
2238 | } |
2239 | |
2240 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
2241 | |
2242 | p = d_ancestor(p2, p1); |
2243 | if (p) { |
2244 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); |
2245 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); |
2246 | return p; |
2247 | } |
2248 | |
2249 | p = d_ancestor(p1, p2); |
2250 | if (p) { |
2251 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
2252 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); |
2253 | return p; |
2254 | } |
2255 | |
2256 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
2257 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); |
2258 | return NULL; |
2259 | } |
2260 | |
2261 | void unlock_rename(struct dentry *p1, struct dentry *p2) |
2262 | { |
2263 | mutex_unlock(&p1->d_inode->i_mutex); |
2264 | if (p1 != p2) { |
2265 | mutex_unlock(&p2->d_inode->i_mutex); |
2266 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
2267 | } |
2268 | } |
2269 | |
2270 | int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
2271 | bool want_excl) |
2272 | { |
2273 | int error = may_create(dir, dentry); |
2274 | if (error) |
2275 | return error; |
2276 | |
2277 | if (!dir->i_op->create) |
2278 | return -EACCES; /* shouldn't it be ENOSYS? */ |
2279 | mode &= S_IALLUGO; |
2280 | mode |= S_IFREG; |
2281 | error = security_inode_create(dir, dentry, mode); |
2282 | if (error) |
2283 | return error; |
2284 | error = dir->i_op->create(dir, dentry, mode, want_excl); |
2285 | if (!error) |
2286 | fsnotify_create(dir, dentry); |
2287 | return error; |
2288 | } |
2289 | |
2290 | static int may_open(struct path *path, int acc_mode, int flag) |
2291 | { |
2292 | struct dentry *dentry = path->dentry; |
2293 | struct inode *inode = dentry->d_inode; |
2294 | int error; |
2295 | |
2296 | /* O_PATH? */ |
2297 | if (!acc_mode) |
2298 | return 0; |
2299 | |
2300 | if (!inode) |
2301 | return -ENOENT; |
2302 | |
2303 | switch (inode->i_mode & S_IFMT) { |
2304 | case S_IFLNK: |
2305 | return -ELOOP; |
2306 | case S_IFDIR: |
2307 | if (acc_mode & MAY_WRITE) |
2308 | return -EISDIR; |
2309 | break; |
2310 | case S_IFBLK: |
2311 | case S_IFCHR: |
2312 | if (path->mnt->mnt_flags & MNT_NODEV) |
2313 | return -EACCES; |
2314 | /*FALLTHRU*/ |
2315 | case S_IFIFO: |
2316 | case S_IFSOCK: |
2317 | flag &= ~O_TRUNC; |
2318 | break; |
2319 | } |
2320 | |
2321 | error = inode_permission(inode, acc_mode); |
2322 | if (error) |
2323 | return error; |
2324 | |
2325 | /* |
2326 | * An append-only file must be opened in append mode for writing. |
2327 | */ |
2328 | if (IS_APPEND(inode)) { |
2329 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
2330 | return -EPERM; |
2331 | if (flag & O_TRUNC) |
2332 | return -EPERM; |
2333 | } |
2334 | |
2335 | /* O_NOATIME can only be set by the owner or superuser */ |
2336 | if (flag & O_NOATIME && !inode_owner_or_capable(inode)) |
2337 | return -EPERM; |
2338 | |
2339 | return 0; |
2340 | } |
2341 | |
2342 | static int handle_truncate(struct file *filp) |
2343 | { |
2344 | struct path *path = &filp->f_path; |
2345 | struct inode *inode = path->dentry->d_inode; |
2346 | int error = get_write_access(inode); |
2347 | if (error) |
2348 | return error; |
2349 | /* |
2350 | * Refuse to truncate files with mandatory locks held on them. |
2351 | */ |
2352 | error = locks_verify_locked(inode); |
2353 | if (!error) |
2354 | error = security_path_truncate(path); |
2355 | if (!error) { |
2356 | error = do_truncate(path->dentry, 0, |
2357 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, |
2358 | filp); |
2359 | } |
2360 | put_write_access(inode); |
2361 | return error; |
2362 | } |
2363 | |
2364 | static inline int open_to_namei_flags(int flag) |
2365 | { |
2366 | if ((flag & O_ACCMODE) == 3) |
2367 | flag--; |
2368 | return flag; |
2369 | } |
2370 | |
2371 | static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) |
2372 | { |
2373 | int error = security_path_mknod(dir, dentry, mode, 0); |
2374 | if (error) |
2375 | return error; |
2376 | |
2377 | error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); |
2378 | if (error) |
2379 | return error; |
2380 | |
2381 | return security_inode_create(dir->dentry->d_inode, dentry, mode); |
2382 | } |
2383 | |
2384 | /* |
2385 | * Attempt to atomically look up, create and open a file from a negative |
2386 | * dentry. |
2387 | * |
2388 | * Returns 0 if successful. The file will have been created and attached to |
2389 | * @file by the filesystem calling finish_open(). |
2390 | * |
2391 | * Returns 1 if the file was looked up only or didn't need creating. The |
2392 | * caller will need to perform the open themselves. @path will have been |
2393 | * updated to point to the new dentry. This may be negative. |
2394 | * |
2395 | * Returns an error code otherwise. |
2396 | */ |
2397 | static int atomic_open(struct nameidata *nd, struct dentry *dentry, |
2398 | struct path *path, struct file *file, |
2399 | const struct open_flags *op, |
2400 | bool got_write, bool need_lookup, |
2401 | int *opened) |
2402 | { |
2403 | struct inode *dir = nd->path.dentry->d_inode; |
2404 | unsigned open_flag = open_to_namei_flags(op->open_flag); |
2405 | umode_t mode; |
2406 | int error; |
2407 | int acc_mode; |
2408 | int create_error = 0; |
2409 | struct dentry *const DENTRY_NOT_SET = (void *) -1UL; |
2410 | |
2411 | BUG_ON(dentry->d_inode); |
2412 | |
2413 | /* Don't create child dentry for a dead directory. */ |
2414 | if (unlikely(IS_DEADDIR(dir))) { |
2415 | error = -ENOENT; |
2416 | goto out; |
2417 | } |
2418 | |
2419 | mode = op->mode; |
2420 | if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) |
2421 | mode &= ~current_umask(); |
2422 | |
2423 | if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) { |
2424 | open_flag &= ~O_TRUNC; |
2425 | *opened |= FILE_CREATED; |
2426 | } |
2427 | |
2428 | /* |
2429 | * Checking write permission is tricky, bacuse we don't know if we are |
2430 | * going to actually need it: O_CREAT opens should work as long as the |
2431 | * file exists. But checking existence breaks atomicity. The trick is |
2432 | * to check access and if not granted clear O_CREAT from the flags. |
2433 | * |
2434 | * Another problem is returing the "right" error value (e.g. for an |
2435 | * O_EXCL open we want to return EEXIST not EROFS). |
2436 | */ |
2437 | if (((open_flag & (O_CREAT | O_TRUNC)) || |
2438 | (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { |
2439 | if (!(open_flag & O_CREAT)) { |
2440 | /* |
2441 | * No O_CREATE -> atomicity not a requirement -> fall |
2442 | * back to lookup + open |
2443 | */ |
2444 | goto no_open; |
2445 | } else if (open_flag & (O_EXCL | O_TRUNC)) { |
2446 | /* Fall back and fail with the right error */ |
2447 | create_error = -EROFS; |
2448 | goto no_open; |
2449 | } else { |
2450 | /* No side effects, safe to clear O_CREAT */ |
2451 | create_error = -EROFS; |
2452 | open_flag &= ~O_CREAT; |
2453 | } |
2454 | } |
2455 | |
2456 | if (open_flag & O_CREAT) { |
2457 | error = may_o_create(&nd->path, dentry, mode); |
2458 | if (error) { |
2459 | create_error = error; |
2460 | if (open_flag & O_EXCL) |
2461 | goto no_open; |
2462 | open_flag &= ~O_CREAT; |
2463 | } |
2464 | } |
2465 | |
2466 | if (nd->flags & LOOKUP_DIRECTORY) |
2467 | open_flag |= O_DIRECTORY; |
2468 | |
2469 | file->f_path.dentry = DENTRY_NOT_SET; |
2470 | file->f_path.mnt = nd->path.mnt; |
2471 | error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, |
2472 | opened); |
2473 | if (error < 0) { |
2474 | if (create_error && error == -ENOENT) |
2475 | error = create_error; |
2476 | goto out; |
2477 | } |
2478 | |
2479 | acc_mode = op->acc_mode; |
2480 | if (*opened & FILE_CREATED) { |
2481 | fsnotify_create(dir, dentry); |
2482 | acc_mode = MAY_OPEN; |
2483 | } |
2484 | |
2485 | if (error) { /* returned 1, that is */ |
2486 | if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { |
2487 | error = -EIO; |
2488 | goto out; |
2489 | } |
2490 | if (file->f_path.dentry) { |
2491 | dput(dentry); |
2492 | dentry = file->f_path.dentry; |
2493 | } |
2494 | if (create_error && dentry->d_inode == NULL) { |
2495 | error = create_error; |
2496 | goto out; |
2497 | } |
2498 | goto looked_up; |
2499 | } |
2500 | |
2501 | /* |
2502 | * We didn't have the inode before the open, so check open permission |
2503 | * here. |
2504 | */ |
2505 | error = may_open(&file->f_path, acc_mode, open_flag); |
2506 | if (error) |
2507 | fput(file); |
2508 | |
2509 | out: |
2510 | dput(dentry); |
2511 | return error; |
2512 | |
2513 | no_open: |
2514 | if (need_lookup) { |
2515 | dentry = lookup_real(dir, dentry, nd->flags); |
2516 | if (IS_ERR(dentry)) |
2517 | return PTR_ERR(dentry); |
2518 | |
2519 | if (create_error) { |
2520 | int open_flag = op->open_flag; |
2521 | |
2522 | error = create_error; |
2523 | if ((open_flag & O_EXCL)) { |
2524 | if (!dentry->d_inode) |
2525 | goto out; |
2526 | } else if (!dentry->d_inode) { |
2527 | goto out; |
2528 | } else if ((open_flag & O_TRUNC) && |
2529 | S_ISREG(dentry->d_inode->i_mode)) { |
2530 | goto out; |
2531 | } |
2532 | /* will fail later, go on to get the right error */ |
2533 | } |
2534 | } |
2535 | looked_up: |
2536 | path->dentry = dentry; |
2537 | path->mnt = nd->path.mnt; |
2538 | return 1; |
2539 | } |
2540 | |
2541 | /* |
2542 | * Look up and maybe create and open the last component. |
2543 | * |
2544 | * Must be called with i_mutex held on parent. |
2545 | * |
2546 | * Returns 0 if the file was successfully atomically created (if necessary) and |
2547 | * opened. In this case the file will be returned attached to @file. |
2548 | * |
2549 | * Returns 1 if the file was not completely opened at this time, though lookups |
2550 | * and creations will have been performed and the dentry returned in @path will |
2551 | * be positive upon return if O_CREAT was specified. If O_CREAT wasn't |
2552 | * specified then a negative dentry may be returned. |
2553 | * |
2554 | * An error code is returned otherwise. |
2555 | * |
2556 | * FILE_CREATE will be set in @*opened if the dentry was created and will be |
2557 | * cleared otherwise prior to returning. |
2558 | */ |
2559 | static int lookup_open(struct nameidata *nd, struct path *path, |
2560 | struct file *file, |
2561 | const struct open_flags *op, |
2562 | bool got_write, int *opened) |
2563 | { |
2564 | struct dentry *dir = nd->path.dentry; |
2565 | struct inode *dir_inode = dir->d_inode; |
2566 | struct dentry *dentry; |
2567 | int error; |
2568 | bool need_lookup; |
2569 | |
2570 | *opened &= ~FILE_CREATED; |
2571 | dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); |
2572 | if (IS_ERR(dentry)) |
2573 | return PTR_ERR(dentry); |
2574 | |
2575 | /* Cached positive dentry: will open in f_op->open */ |
2576 | if (!need_lookup && dentry->d_inode) |
2577 | goto out_no_open; |
2578 | |
2579 | if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { |
2580 | return atomic_open(nd, dentry, path, file, op, got_write, |
2581 | need_lookup, opened); |
2582 | } |
2583 | |
2584 | if (need_lookup) { |
2585 | BUG_ON(dentry->d_inode); |
2586 | |
2587 | dentry = lookup_real(dir_inode, dentry, nd->flags); |
2588 | if (IS_ERR(dentry)) |
2589 | return PTR_ERR(dentry); |
2590 | } |
2591 | |
2592 | /* Negative dentry, just create the file */ |
2593 | if (!dentry->d_inode && (op->open_flag & O_CREAT)) { |
2594 | umode_t mode = op->mode; |
2595 | if (!IS_POSIXACL(dir->d_inode)) |
2596 | mode &= ~current_umask(); |
2597 | /* |
2598 | * This write is needed to ensure that a |
2599 | * rw->ro transition does not occur between |
2600 | * the time when the file is created and when |
2601 | * a permanent write count is taken through |
2602 | * the 'struct file' in finish_open(). |
2603 | */ |
2604 | if (!got_write) { |
2605 | error = -EROFS; |
2606 | goto out_dput; |
2607 | } |
2608 | *opened |= FILE_CREATED; |
2609 | error = security_path_mknod(&nd->path, dentry, mode, 0); |
2610 | if (error) |
2611 | goto out_dput; |
2612 | error = vfs_create(dir->d_inode, dentry, mode, |
2613 | nd->flags & LOOKUP_EXCL); |
2614 | if (error) |
2615 | goto out_dput; |
2616 | } |
2617 | out_no_open: |
2618 | path->dentry = dentry; |
2619 | path->mnt = nd->path.mnt; |
2620 | return 1; |
2621 | |
2622 | out_dput: |
2623 | dput(dentry); |
2624 | return error; |
2625 | } |
2626 | |
2627 | /* |
2628 | * Handle the last step of open() |
2629 | */ |
2630 | static int do_last(struct nameidata *nd, struct path *path, |
2631 | struct file *file, const struct open_flags *op, |
2632 | int *opened, const char *pathname) |
2633 | { |
2634 | struct dentry *dir = nd->path.dentry; |
2635 | int open_flag = op->open_flag; |
2636 | bool will_truncate = (open_flag & O_TRUNC) != 0; |
2637 | bool got_write = false; |
2638 | int acc_mode = op->acc_mode; |
2639 | struct inode *inode; |
2640 | bool symlink_ok = false; |
2641 | struct path save_parent = { .dentry = NULL, .mnt = NULL }; |
2642 | bool retried = false; |
2643 | int error; |
2644 | |
2645 | nd->flags &= ~LOOKUP_PARENT; |
2646 | nd->flags |= op->intent; |
2647 | |
2648 | switch (nd->last_type) { |
2649 | case LAST_DOTDOT: |
2650 | case LAST_DOT: |
2651 | error = handle_dots(nd, nd->last_type); |
2652 | if (error) |
2653 | return error; |
2654 | /* fallthrough */ |
2655 | case LAST_ROOT: |
2656 | error = complete_walk(nd); |
2657 | if (error) |
2658 | return error; |
2659 | audit_inode(pathname, nd->path.dentry); |
2660 | if (open_flag & O_CREAT) { |
2661 | error = -EISDIR; |
2662 | goto out; |
2663 | } |
2664 | goto finish_open; |
2665 | case LAST_BIND: |
2666 | error = complete_walk(nd); |
2667 | if (error) |
2668 | return error; |
2669 | audit_inode(pathname, dir); |
2670 | goto finish_open; |
2671 | } |
2672 | |
2673 | if (!(open_flag & O_CREAT)) { |
2674 | if (nd->last.name[nd->last.len]) |
2675 | nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; |
2676 | if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW)) |
2677 | symlink_ok = true; |
2678 | /* we _can_ be in RCU mode here */ |
2679 | error = lookup_fast(nd, &nd->last, path, &inode); |
2680 | if (likely(!error)) |
2681 | goto finish_lookup; |
2682 | |
2683 | if (error < 0) |
2684 | goto out; |
2685 | |
2686 | BUG_ON(nd->inode != dir->d_inode); |
2687 | } else { |
2688 | /* create side of things */ |
2689 | /* |
2690 | * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED |
2691 | * has been cleared when we got to the last component we are |
2692 | * about to look up |
2693 | */ |
2694 | error = complete_walk(nd); |
2695 | if (error) |
2696 | return error; |
2697 | |
2698 | audit_inode(pathname, dir); |
2699 | error = -EISDIR; |
2700 | /* trailing slashes? */ |
2701 | if (nd->last.name[nd->last.len]) |
2702 | goto out; |
2703 | } |
2704 | |
2705 | retry_lookup: |
2706 | if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { |
2707 | error = mnt_want_write(nd->path.mnt); |
2708 | if (!error) |
2709 | got_write = true; |
2710 | /* |
2711 | * do _not_ fail yet - we might not need that or fail with |
2712 | * a different error; let lookup_open() decide; we'll be |
2713 | * dropping this one anyway. |
2714 | */ |
2715 | } |
2716 | mutex_lock(&dir->d_inode->i_mutex); |
2717 | error = lookup_open(nd, path, file, op, got_write, opened); |
2718 | mutex_unlock(&dir->d_inode->i_mutex); |
2719 | |
2720 | if (error <= 0) { |
2721 | if (error) |
2722 | goto out; |
2723 | |
2724 | if ((*opened & FILE_CREATED) || |
2725 | !S_ISREG(file->f_path.dentry->d_inode->i_mode)) |
2726 | will_truncate = false; |
2727 | |
2728 | audit_inode(pathname, file->f_path.dentry); |
2729 | goto opened; |
2730 | } |
2731 | |
2732 | if (*opened & FILE_CREATED) { |
2733 | /* Don't check for write permission, don't truncate */ |
2734 | open_flag &= ~O_TRUNC; |
2735 | will_truncate = false; |
2736 | acc_mode = MAY_OPEN; |
2737 | path_to_nameidata(path, nd); |
2738 | goto finish_open_created; |
2739 | } |
2740 | |
2741 | /* |
2742 | * create/update audit record if it already exists. |
2743 | */ |
2744 | if (path->dentry->d_inode) |
2745 | audit_inode(pathname, path->dentry); |
2746 | |
2747 | /* |
2748 | * If atomic_open() acquired write access it is dropped now due to |
2749 | * possible mount and symlink following (this might be optimized away if |
2750 | * necessary...) |
2751 | */ |
2752 | if (got_write) { |
2753 | mnt_drop_write(nd->path.mnt); |
2754 | got_write = false; |
2755 | } |
2756 | |
2757 | error = -EEXIST; |
2758 | if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) |
2759 | goto exit_dput; |
2760 | |
2761 | error = follow_managed(path, nd->flags); |
2762 | if (error < 0) |
2763 | goto exit_dput; |
2764 | |
2765 | if (error) |
2766 | nd->flags |= LOOKUP_JUMPED; |
2767 | |
2768 | BUG_ON(nd->flags & LOOKUP_RCU); |
2769 | inode = path->dentry->d_inode; |
2770 | finish_lookup: |
2771 | /* we _can_ be in RCU mode here */ |
2772 | error = -ENOENT; |
2773 | if (!inode) { |
2774 | path_to_nameidata(path, nd); |
2775 | goto out; |
2776 | } |
2777 | |
2778 | if (should_follow_link(inode, !symlink_ok)) { |
2779 | if (nd->flags & LOOKUP_RCU) { |
2780 | if (unlikely(unlazy_walk(nd, path->dentry))) { |
2781 | error = -ECHILD; |
2782 | goto out; |
2783 | } |
2784 | } |
2785 | BUG_ON(inode != path->dentry->d_inode); |
2786 | return 1; |
2787 | } |
2788 | |
2789 | if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path->mnt) { |
2790 | path_to_nameidata(path, nd); |
2791 | } else { |
2792 | save_parent.dentry = nd->path.dentry; |
2793 | save_parent.mnt = mntget(path->mnt); |
2794 | nd->path.dentry = path->dentry; |
2795 | |
2796 | } |
2797 | nd->inode = inode; |
2798 | /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ |
2799 | error = complete_walk(nd); |
2800 | if (error) { |
2801 | path_put(&save_parent); |
2802 | return error; |
2803 | } |
2804 | error = -EISDIR; |
2805 | if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode)) |
2806 | goto out; |
2807 | error = -ENOTDIR; |
2808 | if ((nd->flags & LOOKUP_DIRECTORY) && !nd->inode->i_op->lookup) |
2809 | goto out; |
2810 | audit_inode(pathname, nd->path.dentry); |
2811 | finish_open: |
2812 | if (!S_ISREG(nd->inode->i_mode)) |
2813 | will_truncate = false; |
2814 | |
2815 | if (will_truncate) { |
2816 | error = mnt_want_write(nd->path.mnt); |
2817 | if (error) |
2818 | goto out; |
2819 | got_write = true; |
2820 | } |
2821 | finish_open_created: |
2822 | error = may_open(&nd->path, acc_mode, open_flag); |
2823 | if (error) |
2824 | goto out; |
2825 | file->f_path.mnt = nd->path.mnt; |
2826 | error = finish_open(file, nd->path.dentry, NULL, opened); |
2827 | if (error) { |
2828 | if (error == -EOPENSTALE) |
2829 | goto stale_open; |
2830 | goto out; |
2831 | } |
2832 | opened: |
2833 | error = open_check_o_direct(file); |
2834 | if (error) |
2835 | goto exit_fput; |
2836 | error = ima_file_check(file, op->acc_mode); |
2837 | if (error) |
2838 | goto exit_fput; |
2839 | |
2840 | if (will_truncate) { |
2841 | error = handle_truncate(file); |
2842 | if (error) |
2843 | goto exit_fput; |
2844 | } |
2845 | out: |
2846 | if (got_write) |
2847 | mnt_drop_write(nd->path.mnt); |
2848 | path_put(&save_parent); |
2849 | terminate_walk(nd); |
2850 | return error; |
2851 | |
2852 | exit_dput: |
2853 | path_put_conditional(path, nd); |
2854 | goto out; |
2855 | exit_fput: |
2856 | fput(file); |
2857 | goto out; |
2858 | |
2859 | stale_open: |
2860 | /* If no saved parent or already retried then can't retry */ |
2861 | if (!save_parent.dentry || retried) |
2862 | goto out; |
2863 | |
2864 | BUG_ON(save_parent.dentry != dir); |
2865 | path_put(&nd->path); |
2866 | nd->path = save_parent; |
2867 | nd->inode = dir->d_inode; |
2868 | save_parent.mnt = NULL; |
2869 | save_parent.dentry = NULL; |
2870 | if (got_write) { |
2871 | mnt_drop_write(nd->path.mnt); |
2872 | got_write = false; |
2873 | } |
2874 | retried = true; |
2875 | goto retry_lookup; |
2876 | } |
2877 | |
2878 | static struct file *path_openat(int dfd, const char *pathname, |
2879 | struct nameidata *nd, const struct open_flags *op, int flags) |
2880 | { |
2881 | struct file *base = NULL; |
2882 | struct file *file; |
2883 | struct path path; |
2884 | int opened = 0; |
2885 | int error; |
2886 | |
2887 | file = get_empty_filp(); |
2888 | if (!file) |
2889 | return ERR_PTR(-ENFILE); |
2890 | |
2891 | file->f_flags = op->open_flag; |
2892 | |
2893 | error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base); |
2894 | if (unlikely(error)) |
2895 | goto out; |
2896 | |
2897 | current->total_link_count = 0; |
2898 | error = link_path_walk(pathname, nd); |
2899 | if (unlikely(error)) |
2900 | goto out; |
2901 | |
2902 | error = do_last(nd, &path, file, op, &opened, pathname); |
2903 | while (unlikely(error > 0)) { /* trailing symlink */ |
2904 | struct path link = path; |
2905 | void *cookie; |
2906 | if (!(nd->flags & LOOKUP_FOLLOW)) { |
2907 | path_put_conditional(&path, nd); |
2908 | path_put(&nd->path); |
2909 | error = -ELOOP; |
2910 | break; |
2911 | } |
2912 | error = may_follow_link(&link, nd); |
2913 | if (unlikely(error)) |
2914 | break; |
2915 | nd->flags |= LOOKUP_PARENT; |
2916 | nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); |
2917 | error = follow_link(&link, nd, &cookie); |
2918 | if (unlikely(error)) |
2919 | break; |
2920 | error = do_last(nd, &path, file, op, &opened, pathname); |
2921 | put_link(nd, &link, cookie); |
2922 | } |
2923 | out: |
2924 | if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) |
2925 | path_put(&nd->root); |
2926 | if (base) |
2927 | fput(base); |
2928 | if (!(opened & FILE_OPENED)) { |
2929 | BUG_ON(!error); |
2930 | put_filp(file); |
2931 | } |
2932 | if (unlikely(error)) { |
2933 | if (error == -EOPENSTALE) { |
2934 | if (flags & LOOKUP_RCU) |
2935 | error = -ECHILD; |
2936 | else |
2937 | error = -ESTALE; |
2938 | } |
2939 | file = ERR_PTR(error); |
2940 | } |
2941 | return file; |
2942 | } |
2943 | |
2944 | struct file *do_filp_open(int dfd, const char *pathname, |
2945 | const struct open_flags *op, int flags) |
2946 | { |
2947 | struct nameidata nd; |
2948 | struct file *filp; |
2949 | |
2950 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); |
2951 | if (unlikely(filp == ERR_PTR(-ECHILD))) |
2952 | filp = path_openat(dfd, pathname, &nd, op, flags); |
2953 | if (unlikely(filp == ERR_PTR(-ESTALE))) |
2954 | filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); |
2955 | return filp; |
2956 | } |
2957 | |
2958 | struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
2959 | const char *name, const struct open_flags *op, int flags) |
2960 | { |
2961 | struct nameidata nd; |
2962 | struct file *file; |
2963 | |
2964 | nd.root.mnt = mnt; |
2965 | nd.root.dentry = dentry; |
2966 | |
2967 | flags |= LOOKUP_ROOT; |
2968 | |
2969 | if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN) |
2970 | return ERR_PTR(-ELOOP); |
2971 | |
2972 | file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU); |
2973 | if (unlikely(file == ERR_PTR(-ECHILD))) |
2974 | file = path_openat(-1, name, &nd, op, flags); |
2975 | if (unlikely(file == ERR_PTR(-ESTALE))) |
2976 | file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL); |
2977 | return file; |
2978 | } |
2979 | |
2980 | struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir) |
2981 | { |
2982 | struct dentry *dentry = ERR_PTR(-EEXIST); |
2983 | struct nameidata nd; |
2984 | int err2; |
2985 | int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd); |
2986 | if (error) |
2987 | return ERR_PTR(error); |
2988 | |
2989 | /* |
2990 | * Yucky last component or no last component at all? |
2991 | * (foo/., foo/.., /////) |
2992 | */ |
2993 | if (nd.last_type != LAST_NORM) |
2994 | goto out; |
2995 | nd.flags &= ~LOOKUP_PARENT; |
2996 | nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; |
2997 | |
2998 | /* don't fail immediately if it's r/o, at least try to report other errors */ |
2999 | err2 = mnt_want_write(nd.path.mnt); |
3000 | /* |
3001 | * Do the final lookup. |
3002 | */ |
3003 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
3004 | dentry = lookup_hash(&nd); |
3005 | if (IS_ERR(dentry)) |
3006 | goto unlock; |
3007 | |
3008 | error = -EEXIST; |
3009 | if (dentry->d_inode) |
3010 | goto fail; |
3011 | /* |
3012 | * Special case - lookup gave negative, but... we had foo/bar/ |
3013 | * From the vfs_mknod() POV we just have a negative dentry - |
3014 | * all is fine. Let's be bastards - you had / on the end, you've |
3015 | * been asking for (non-existent) directory. -ENOENT for you. |
3016 | */ |
3017 | if (unlikely(!is_dir && nd.last.name[nd.last.len])) { |
3018 | error = -ENOENT; |
3019 | goto fail; |
3020 | } |
3021 | if (unlikely(err2)) { |
3022 | error = err2; |
3023 | goto fail; |
3024 | } |
3025 | *path = nd.path; |
3026 | return dentry; |
3027 | fail: |
3028 | dput(dentry); |
3029 | dentry = ERR_PTR(error); |
3030 | unlock: |
3031 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
3032 | if (!err2) |
3033 | mnt_drop_write(nd.path.mnt); |
3034 | out: |
3035 | path_put(&nd.path); |
3036 | return dentry; |
3037 | } |
3038 | EXPORT_SYMBOL(kern_path_create); |
3039 | |
3040 | void done_path_create(struct path *path, struct dentry *dentry) |
3041 | { |
3042 | dput(dentry); |
3043 | mutex_unlock(&path->dentry->d_inode->i_mutex); |
3044 | mnt_drop_write(path->mnt); |
3045 | path_put(path); |
3046 | } |
3047 | EXPORT_SYMBOL(done_path_create); |
3048 | |
3049 | struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir) |
3050 | { |
3051 | char *tmp = getname(pathname); |
3052 | struct dentry *res; |
3053 | if (IS_ERR(tmp)) |
3054 | return ERR_CAST(tmp); |
3055 | res = kern_path_create(dfd, tmp, path, is_dir); |
3056 | putname(tmp); |
3057 | return res; |
3058 | } |
3059 | EXPORT_SYMBOL(user_path_create); |
3060 | |
3061 | int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
3062 | { |
3063 | int error = may_create(dir, dentry); |
3064 | |
3065 | if (error) |
3066 | return error; |
3067 | |
3068 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) |
3069 | return -EPERM; |
3070 | |
3071 | if (!dir->i_op->mknod) |
3072 | return -EPERM; |
3073 | |
3074 | error = devcgroup_inode_mknod(mode, dev); |
3075 | if (error) |
3076 | return error; |
3077 | |
3078 | error = security_inode_mknod(dir, dentry, mode, dev); |
3079 | if (error) |
3080 | return error; |
3081 | |
3082 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
3083 | if (!error) |
3084 | fsnotify_create(dir, dentry); |
3085 | return error; |
3086 | } |
3087 | |
3088 | static int may_mknod(umode_t mode) |
3089 | { |
3090 | switch (mode & S_IFMT) { |
3091 | case S_IFREG: |
3092 | case S_IFCHR: |
3093 | case S_IFBLK: |
3094 | case S_IFIFO: |
3095 | case S_IFSOCK: |
3096 | case 0: /* zero mode translates to S_IFREG */ |
3097 | return 0; |
3098 | case S_IFDIR: |
3099 | return -EPERM; |
3100 | default: |
3101 | return -EINVAL; |
3102 | } |
3103 | } |
3104 | |
3105 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, |
3106 | unsigned, dev) |
3107 | { |
3108 | struct dentry *dentry; |
3109 | struct path path; |
3110 | int error; |
3111 | |
3112 | error = may_mknod(mode); |
3113 | if (error) |
3114 | return error; |
3115 | |
3116 | dentry = user_path_create(dfd, filename, &path, 0); |
3117 | if (IS_ERR(dentry)) |
3118 | return PTR_ERR(dentry); |
3119 | |
3120 | if (!IS_POSIXACL(path.dentry->d_inode)) |
3121 | mode &= ~current_umask(); |
3122 | error = security_path_mknod(&path, dentry, mode, dev); |
3123 | if (error) |
3124 | goto out; |
3125 | switch (mode & S_IFMT) { |
3126 | case 0: case S_IFREG: |
3127 | error = vfs_create(path.dentry->d_inode,dentry,mode,true); |
3128 | break; |
3129 | case S_IFCHR: case S_IFBLK: |
3130 | error = vfs_mknod(path.dentry->d_inode,dentry,mode, |
3131 | new_decode_dev(dev)); |
3132 | break; |
3133 | case S_IFIFO: case S_IFSOCK: |
3134 | error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); |
3135 | break; |
3136 | } |
3137 | out: |
3138 | done_path_create(&path, dentry); |
3139 | return error; |
3140 | } |
3141 | |
3142 | SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) |
3143 | { |
3144 | return sys_mknodat(AT_FDCWD, filename, mode, dev); |
3145 | } |
3146 | |
3147 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
3148 | { |
3149 | int error = may_create(dir, dentry); |
3150 | unsigned max_links = dir->i_sb->s_max_links; |
3151 | |
3152 | if (error) |
3153 | return error; |
3154 | |
3155 | if (!dir->i_op->mkdir) |
3156 | return -EPERM; |
3157 | |
3158 | mode &= (S_IRWXUGO|S_ISVTX); |
3159 | error = security_inode_mkdir(dir, dentry, mode); |
3160 | if (error) |
3161 | return error; |
3162 | |
3163 | if (max_links && dir->i_nlink >= max_links) |
3164 | return -EMLINK; |
3165 | |
3166 | error = dir->i_op->mkdir(dir, dentry, mode); |
3167 | if (!error) |
3168 | fsnotify_mkdir(dir, dentry); |
3169 | return error; |
3170 | } |
3171 | |
3172 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) |
3173 | { |
3174 | struct dentry *dentry; |
3175 | struct path path; |
3176 | int error; |
3177 | |
3178 | dentry = user_path_create(dfd, pathname, &path, 1); |
3179 | if (IS_ERR(dentry)) |
3180 | return PTR_ERR(dentry); |
3181 | |
3182 | if (!IS_POSIXACL(path.dentry->d_inode)) |
3183 | mode &= ~current_umask(); |
3184 | error = security_path_mkdir(&path, dentry, mode); |
3185 | if (!error) |
3186 | error = vfs_mkdir(path.dentry->d_inode, dentry, mode); |
3187 | done_path_create(&path, dentry); |
3188 | return error; |
3189 | } |
3190 | |
3191 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) |
3192 | { |
3193 | return sys_mkdirat(AT_FDCWD, pathname, mode); |
3194 | } |
3195 | |
3196 | /* |
3197 | * The dentry_unhash() helper will try to drop the dentry early: we |
3198 | * should have a usage count of 1 if we're the only user of this |
3199 | * dentry, and if that is true (possibly after pruning the dcache), |
3200 | * then we drop the dentry now. |
3201 | * |
3202 | * A low-level filesystem can, if it choses, legally |
3203 | * do a |
3204 | * |
3205 | * if (!d_unhashed(dentry)) |
3206 | * return -EBUSY; |
3207 | * |
3208 | * if it cannot handle the case of removing a directory |
3209 | * that is still in use by something else.. |
3210 | */ |
3211 | void dentry_unhash(struct dentry *dentry) |
3212 | { |
3213 | shrink_dcache_parent(dentry); |
3214 | spin_lock(&dentry->d_lock); |
3215 | if (dentry->d_count == 1) |
3216 | __d_drop(dentry); |
3217 | spin_unlock(&dentry->d_lock); |
3218 | } |
3219 | |
3220 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) |
3221 | { |
3222 | int error = may_delete(dir, dentry, 1); |
3223 | |
3224 | if (error) |
3225 | return error; |
3226 | |
3227 | if (!dir->i_op->rmdir) |
3228 | return -EPERM; |
3229 | |
3230 | dget(dentry); |
3231 | mutex_lock(&dentry->d_inode->i_mutex); |
3232 | |
3233 | error = -EBUSY; |
3234 | if (d_mountpoint(dentry)) |
3235 | goto out; |
3236 | |
3237 | error = security_inode_rmdir(dir, dentry); |
3238 | if (error) |
3239 | goto out; |
3240 | |
3241 | shrink_dcache_parent(dentry); |
3242 | error = dir->i_op->rmdir(dir, dentry); |
3243 | if (error) |
3244 | goto out; |
3245 | |
3246 | dentry->d_inode->i_flags |= S_DEAD; |
3247 | dont_mount(dentry); |
3248 | |
3249 | out: |
3250 | mutex_unlock(&dentry->d_inode->i_mutex); |
3251 | dput(dentry); |
3252 | if (!error) |
3253 | d_delete(dentry); |
3254 | return error; |
3255 | } |
3256 | |
3257 | static long do_rmdir(int dfd, const char __user *pathname) |
3258 | { |
3259 | int error = 0; |
3260 | char * name; |
3261 | struct dentry *dentry; |
3262 | struct nameidata nd; |
3263 | |
3264 | error = user_path_parent(dfd, pathname, &nd, &name); |
3265 | if (error) |
3266 | return error; |
3267 | |
3268 | switch(nd.last_type) { |
3269 | case LAST_DOTDOT: |
3270 | error = -ENOTEMPTY; |
3271 | goto exit1; |
3272 | case LAST_DOT: |
3273 | error = -EINVAL; |
3274 | goto exit1; |
3275 | case LAST_ROOT: |
3276 | error = -EBUSY; |
3277 | goto exit1; |
3278 | } |
3279 | |
3280 | nd.flags &= ~LOOKUP_PARENT; |
3281 | error = mnt_want_write(nd.path.mnt); |
3282 | if (error) |
3283 | goto exit1; |
3284 | |
3285 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
3286 | dentry = lookup_hash(&nd); |
3287 | error = PTR_ERR(dentry); |
3288 | if (IS_ERR(dentry)) |
3289 | goto exit2; |
3290 | if (!dentry->d_inode) { |
3291 | error = -ENOENT; |
3292 | goto exit3; |
3293 | } |
3294 | error = security_path_rmdir(&nd.path, dentry); |
3295 | if (error) |
3296 | goto exit3; |
3297 | error = vfs_rmdir(nd.path.dentry->d_inode, dentry); |
3298 | exit3: |
3299 | dput(dentry); |
3300 | exit2: |
3301 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
3302 | mnt_drop_write(nd.path.mnt); |
3303 | exit1: |
3304 | path_put(&nd.path); |
3305 | putname(name); |
3306 | return error; |
3307 | } |
3308 | |
3309 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
3310 | { |
3311 | return do_rmdir(AT_FDCWD, pathname); |
3312 | } |
3313 | |
3314 | int vfs_unlink(struct inode *dir, struct dentry *dentry) |
3315 | { |
3316 | int error = may_delete(dir, dentry, 0); |
3317 | |
3318 | if (error) |
3319 | return error; |
3320 | |
3321 | if (!dir->i_op->unlink) |
3322 | return -EPERM; |
3323 | |
3324 | mutex_lock(&dentry->d_inode->i_mutex); |
3325 | if (d_mountpoint(dentry)) |
3326 | error = -EBUSY; |
3327 | else { |
3328 | error = security_inode_unlink(dir, dentry); |
3329 | if (!error) { |
3330 | error = dir->i_op->unlink(dir, dentry); |
3331 | if (!error) |
3332 | dont_mount(dentry); |
3333 | } |
3334 | } |
3335 | mutex_unlock(&dentry->d_inode->i_mutex); |
3336 | |
3337 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ |
3338 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { |
3339 | fsnotify_link_count(dentry->d_inode); |
3340 | d_delete(dentry); |
3341 | } |
3342 | |
3343 | return error; |
3344 | } |
3345 | |
3346 | /* |
3347 | * Make sure that the actual truncation of the file will occur outside its |
3348 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
3349 | * writeout happening, and we don't want to prevent access to the directory |
3350 | * while waiting on the I/O. |
3351 | */ |
3352 | static long do_unlinkat(int dfd, const char __user *pathname) |
3353 | { |
3354 | int error; |
3355 | char *name; |
3356 | struct dentry *dentry; |
3357 | struct nameidata nd; |
3358 | struct inode *inode = NULL; |
3359 | |
3360 | error = user_path_parent(dfd, pathname, &nd, &name); |
3361 | if (error) |
3362 | return error; |
3363 | |
3364 | error = -EISDIR; |
3365 | if (nd.last_type != LAST_NORM) |
3366 | goto exit1; |
3367 | |
3368 | nd.flags &= ~LOOKUP_PARENT; |
3369 | error = mnt_want_write(nd.path.mnt); |
3370 | if (error) |
3371 | goto exit1; |
3372 | |
3373 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
3374 | dentry = lookup_hash(&nd); |
3375 | error = PTR_ERR(dentry); |
3376 | if (!IS_ERR(dentry)) { |
3377 | /* Why not before? Because we want correct error value */ |
3378 | if (nd.last.name[nd.last.len]) |
3379 | goto slashes; |
3380 | inode = dentry->d_inode; |
3381 | if (!inode) |
3382 | goto slashes; |
3383 | ihold(inode); |
3384 | error = security_path_unlink(&nd.path, dentry); |
3385 | if (error) |
3386 | goto exit2; |
3387 | error = vfs_unlink(nd.path.dentry->d_inode, dentry); |
3388 | exit2: |
3389 | dput(dentry); |
3390 | } |
3391 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
3392 | if (inode) |
3393 | iput(inode); /* truncate the inode here */ |
3394 | mnt_drop_write(nd.path.mnt); |
3395 | exit1: |
3396 | path_put(&nd.path); |
3397 | putname(name); |
3398 | return error; |
3399 | |
3400 | slashes: |
3401 | error = !dentry->d_inode ? -ENOENT : |
3402 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; |
3403 | goto exit2; |
3404 | } |
3405 | |
3406 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
3407 | { |
3408 | if ((flag & ~AT_REMOVEDIR) != 0) |
3409 | return -EINVAL; |
3410 | |
3411 | if (flag & AT_REMOVEDIR) |
3412 | return do_rmdir(dfd, pathname); |
3413 | |
3414 | return do_unlinkat(dfd, pathname); |
3415 | } |
3416 | |
3417 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
3418 | { |
3419 | return do_unlinkat(AT_FDCWD, pathname); |
3420 | } |
3421 | |
3422 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
3423 | { |
3424 | int error = may_create(dir, dentry); |
3425 | |
3426 | if (error) |
3427 | return error; |
3428 | |
3429 | if (!dir->i_op->symlink) |
3430 | return -EPERM; |
3431 | |
3432 | error = security_inode_symlink(dir, dentry, oldname); |
3433 | if (error) |
3434 | return error; |
3435 | |
3436 | error = dir->i_op->symlink(dir, dentry, oldname); |
3437 | if (!error) |
3438 | fsnotify_create(dir, dentry); |
3439 | return error; |
3440 | } |
3441 | |
3442 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
3443 | int, newdfd, const char __user *, newname) |
3444 | { |
3445 | int error; |
3446 | char *from; |
3447 | struct dentry *dentry; |
3448 | struct path path; |
3449 | |
3450 | from = getname(oldname); |
3451 | if (IS_ERR(from)) |
3452 | return PTR_ERR(from); |
3453 | |
3454 | dentry = user_path_create(newdfd, newname, &path, 0); |
3455 | error = PTR_ERR(dentry); |
3456 | if (IS_ERR(dentry)) |
3457 | goto out_putname; |
3458 | |
3459 | error = security_path_symlink(&path, dentry, from); |
3460 | if (!error) |
3461 | error = vfs_symlink(path.dentry->d_inode, dentry, from); |
3462 | done_path_create(&path, dentry); |
3463 | out_putname: |
3464 | putname(from); |
3465 | return error; |
3466 | } |
3467 | |
3468 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
3469 | { |
3470 | return sys_symlinkat(oldname, AT_FDCWD, newname); |
3471 | } |
3472 | |
3473 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
3474 | { |
3475 | struct inode *inode = old_dentry->d_inode; |
3476 | unsigned max_links = dir->i_sb->s_max_links; |
3477 | int error; |
3478 | |
3479 | if (!inode) |
3480 | return -ENOENT; |
3481 | |
3482 | error = may_create(dir, new_dentry); |
3483 | if (error) |
3484 | return error; |
3485 | |
3486 | if (dir->i_sb != inode->i_sb) |
3487 | return -EXDEV; |
3488 | |
3489 | /* |
3490 | * A link to an append-only or immutable file cannot be created. |
3491 | */ |
3492 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) |
3493 | return -EPERM; |
3494 | if (!dir->i_op->link) |
3495 | return -EPERM; |
3496 | if (S_ISDIR(inode->i_mode)) |
3497 | return -EPERM; |
3498 | |
3499 | error = security_inode_link(old_dentry, dir, new_dentry); |
3500 | if (error) |
3501 | return error; |
3502 | |
3503 | mutex_lock(&inode->i_mutex); |
3504 | /* Make sure we don't allow creating hardlink to an unlinked file */ |
3505 | if (inode->i_nlink == 0) |
3506 | error = -ENOENT; |
3507 | else if (max_links && inode->i_nlink >= max_links) |
3508 | error = -EMLINK; |
3509 | else |
3510 | error = dir->i_op->link(old_dentry, dir, new_dentry); |
3511 | mutex_unlock(&inode->i_mutex); |
3512 | if (!error) |
3513 | fsnotify_link(dir, inode, new_dentry); |
3514 | return error; |
3515 | } |
3516 | |
3517 | /* |
3518 | * Hardlinks are often used in delicate situations. We avoid |
3519 | * security-related surprises by not following symlinks on the |
3520 | * newname. --KAB |
3521 | * |
3522 | * We don't follow them on the oldname either to be compatible |
3523 | * with linux 2.0, and to avoid hard-linking to directories |
3524 | * and other special files. --ADM |
3525 | */ |
3526 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
3527 | int, newdfd, const char __user *, newname, int, flags) |
3528 | { |
3529 | struct dentry *new_dentry; |
3530 | struct path old_path, new_path; |
3531 | int how = 0; |
3532 | int error; |
3533 | |
3534 | if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) |
3535 | return -EINVAL; |
3536 | /* |
3537 | * To use null names we require CAP_DAC_READ_SEARCH |
3538 | * This ensures that not everyone will be able to create |
3539 | * handlink using the passed filedescriptor. |
3540 | */ |
3541 | if (flags & AT_EMPTY_PATH) { |
3542 | if (!capable(CAP_DAC_READ_SEARCH)) |
3543 | return -ENOENT; |
3544 | how = LOOKUP_EMPTY; |
3545 | } |
3546 | |
3547 | if (flags & AT_SYMLINK_FOLLOW) |
3548 | how |= LOOKUP_FOLLOW; |
3549 | |
3550 | error = user_path_at(olddfd, oldname, how, &old_path); |
3551 | if (error) |
3552 | return error; |
3553 | |
3554 | new_dentry = user_path_create(newdfd, newname, &new_path, 0); |
3555 | error = PTR_ERR(new_dentry); |
3556 | if (IS_ERR(new_dentry)) |
3557 | goto out; |
3558 | |
3559 | error = -EXDEV; |
3560 | if (old_path.mnt != new_path.mnt) |
3561 | goto out_dput; |
3562 | error = may_linkat(&old_path); |
3563 | if (unlikely(error)) |
3564 | goto out_dput; |
3565 | error = security_path_link(old_path.dentry, &new_path, new_dentry); |
3566 | if (error) |
3567 | goto out_dput; |
3568 | error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry); |
3569 | out_dput: |
3570 | done_path_create(&new_path, new_dentry); |
3571 | out: |
3572 | path_put(&old_path); |
3573 | |
3574 | return error; |
3575 | } |
3576 | |
3577 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
3578 | { |
3579 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
3580 | } |
3581 | |
3582 | /* |
3583 | * The worst of all namespace operations - renaming directory. "Perverted" |
3584 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... |
3585 | * Problems: |
3586 | * a) we can get into loop creation. Check is done in is_subdir(). |
3587 | * b) race potential - two innocent renames can create a loop together. |
3588 | * That's where 4.4 screws up. Current fix: serialization on |
3589 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
3590 | * story. |
3591 | * c) we have to lock _three_ objects - parents and victim (if it exists). |
3592 | * And that - after we got ->i_mutex on parents (until then we don't know |
3593 | * whether the target exists). Solution: try to be smart with locking |
3594 | * order for inodes. We rely on the fact that tree topology may change |
3595 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
3596 | * move will be locked. Thus we can rank directories by the tree |
3597 | * (ancestors first) and rank all non-directories after them. |
3598 | * That works since everybody except rename does "lock parent, lookup, |
3599 | * lock child" and rename is under ->s_vfs_rename_mutex. |
3600 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
3601 | * has no more than 1 dentry. If "hybrid" objects will ever appear, |
3602 | * we'd better make sure that there's no link(2) for them. |
3603 | * d) conversion from fhandle to dentry may come in the wrong moment - when |
3604 | * we are removing the target. Solution: we will have to grab ->i_mutex |
3605 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
3606 | * ->i_mutex on parents, which works but leads to some truly excessive |
3607 | * locking]. |
3608 | */ |
3609 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
3610 | struct inode *new_dir, struct dentry *new_dentry) |
3611 | { |
3612 | int error = 0; |
3613 | struct inode *target = new_dentry->d_inode; |
3614 | unsigned max_links = new_dir->i_sb->s_max_links; |
3615 | |
3616 | /* |
3617 | * If we are going to change the parent - check write permissions, |
3618 | * we'll need to flip '..'. |
3619 | */ |
3620 | if (new_dir != old_dir) { |
3621 | error = inode_permission(old_dentry->d_inode, MAY_WRITE); |
3622 | if (error) |
3623 | return error; |
3624 | } |
3625 | |
3626 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); |
3627 | if (error) |
3628 | return error; |
3629 | |
3630 | dget(new_dentry); |
3631 | if (target) |
3632 | mutex_lock(&target->i_mutex); |
3633 | |
3634 | error = -EBUSY; |
3635 | if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry)) |
3636 | goto out; |
3637 | |
3638 | error = -EMLINK; |
3639 | if (max_links && !target && new_dir != old_dir && |
3640 | new_dir->i_nlink >= max_links) |
3641 | goto out; |
3642 | |
3643 | if (target) |
3644 | shrink_dcache_parent(new_dentry); |
3645 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
3646 | if (error) |
3647 | goto out; |
3648 | |
3649 | if (target) { |
3650 | target->i_flags |= S_DEAD; |
3651 | dont_mount(new_dentry); |
3652 | } |
3653 | out: |
3654 | if (target) |
3655 | mutex_unlock(&target->i_mutex); |
3656 | dput(new_dentry); |
3657 | if (!error) |
3658 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
3659 | d_move(old_dentry,new_dentry); |
3660 | return error; |
3661 | } |
3662 | |
3663 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
3664 | struct inode *new_dir, struct dentry *new_dentry) |
3665 | { |
3666 | struct inode *target = new_dentry->d_inode; |
3667 | int error; |
3668 | |
3669 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); |
3670 | if (error) |
3671 | return error; |
3672 | |
3673 | dget(new_dentry); |
3674 | if (target) |
3675 | mutex_lock(&target->i_mutex); |
3676 | |
3677 | error = -EBUSY; |
3678 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
3679 | goto out; |
3680 | |
3681 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
3682 | if (error) |
3683 | goto out; |
3684 | |
3685 | if (target) |
3686 | dont_mount(new_dentry); |
3687 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
3688 | d_move(old_dentry, new_dentry); |
3689 | out: |
3690 | if (target) |
3691 | mutex_unlock(&target->i_mutex); |
3692 | dput(new_dentry); |
3693 | return error; |
3694 | } |
3695 | |
3696 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, |
3697 | struct inode *new_dir, struct dentry *new_dentry) |
3698 | { |
3699 | int error; |
3700 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); |
3701 | const unsigned char *old_name; |
3702 | |
3703 | if (old_dentry->d_inode == new_dentry->d_inode) |
3704 | return 0; |
3705 | |
3706 | error = may_delete(old_dir, old_dentry, is_dir); |
3707 | if (error) |
3708 | return error; |
3709 | |
3710 | if (!new_dentry->d_inode) |
3711 | error = may_create(new_dir, new_dentry); |
3712 | else |
3713 | error = may_delete(new_dir, new_dentry, is_dir); |
3714 | if (error) |
3715 | return error; |
3716 | |
3717 | if (!old_dir->i_op->rename) |
3718 | return -EPERM; |
3719 | |
3720 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
3721 | |
3722 | if (is_dir) |
3723 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); |
3724 | else |
3725 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); |
3726 | if (!error) |
3727 | fsnotify_move(old_dir, new_dir, old_name, is_dir, |
3728 | new_dentry->d_inode, old_dentry); |
3729 | fsnotify_oldname_free(old_name); |
3730 | |
3731 | return error; |
3732 | } |
3733 | |
3734 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
3735 | int, newdfd, const char __user *, newname) |
3736 | { |
3737 | struct dentry *old_dir, *new_dir; |
3738 | struct dentry *old_dentry, *new_dentry; |
3739 | struct dentry *trap; |
3740 | struct nameidata oldnd, newnd; |
3741 | char *from; |
3742 | char *to; |
3743 | int error; |
3744 | |
3745 | error = user_path_parent(olddfd, oldname, &oldnd, &from); |
3746 | if (error) |
3747 | goto exit; |
3748 | |
3749 | error = user_path_parent(newdfd, newname, &newnd, &to); |
3750 | if (error) |
3751 | goto exit1; |
3752 | |
3753 | error = -EXDEV; |
3754 | if (oldnd.path.mnt != newnd.path.mnt) |
3755 | goto exit2; |
3756 | |
3757 | old_dir = oldnd.path.dentry; |
3758 | error = -EBUSY; |
3759 | if (oldnd.last_type != LAST_NORM) |
3760 | goto exit2; |
3761 | |
3762 | new_dir = newnd.path.dentry; |
3763 | if (newnd.last_type != LAST_NORM) |
3764 | goto exit2; |
3765 | |
3766 | error = mnt_want_write(oldnd.path.mnt); |
3767 | if (error) |
3768 | goto exit2; |
3769 | |
3770 | oldnd.flags &= ~LOOKUP_PARENT; |
3771 | newnd.flags &= ~LOOKUP_PARENT; |
3772 | newnd.flags |= LOOKUP_RENAME_TARGET; |
3773 | |
3774 | trap = lock_rename(new_dir, old_dir); |
3775 | |
3776 | old_dentry = lookup_hash(&oldnd); |
3777 | error = PTR_ERR(old_dentry); |
3778 | if (IS_ERR(old_dentry)) |
3779 | goto exit3; |
3780 | /* source must exist */ |
3781 | error = -ENOENT; |
3782 | if (!old_dentry->d_inode) |
3783 | goto exit4; |
3784 | /* unless the source is a directory trailing slashes give -ENOTDIR */ |
3785 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { |
3786 | error = -ENOTDIR; |
3787 | if (oldnd.last.name[oldnd.last.len]) |
3788 | goto exit4; |
3789 | if (newnd.last.name[newnd.last.len]) |
3790 | goto exit4; |
3791 | } |
3792 | /* source should not be ancestor of target */ |
3793 | error = -EINVAL; |
3794 | if (old_dentry == trap) |
3795 | goto exit4; |
3796 | new_dentry = lookup_hash(&newnd); |
3797 | error = PTR_ERR(new_dentry); |
3798 | if (IS_ERR(new_dentry)) |
3799 | goto exit4; |
3800 | /* target should not be an ancestor of source */ |
3801 | error = -ENOTEMPTY; |
3802 | if (new_dentry == trap) |
3803 | goto exit5; |
3804 | |
3805 | error = security_path_rename(&oldnd.path, old_dentry, |
3806 | &newnd.path, new_dentry); |
3807 | if (error) |
3808 | goto exit5; |
3809 | error = vfs_rename(old_dir->d_inode, old_dentry, |
3810 | new_dir->d_inode, new_dentry); |
3811 | exit5: |
3812 | dput(new_dentry); |
3813 | exit4: |
3814 | dput(old_dentry); |
3815 | exit3: |
3816 | unlock_rename(new_dir, old_dir); |
3817 | mnt_drop_write(oldnd.path.mnt); |
3818 | exit2: |
3819 | path_put(&newnd.path); |
3820 | putname(to); |
3821 | exit1: |
3822 | path_put(&oldnd.path); |
3823 | putname(from); |
3824 | exit: |
3825 | return error; |
3826 | } |
3827 | |
3828 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
3829 | { |
3830 | return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); |
3831 | } |
3832 | |
3833 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
3834 | { |
3835 | int len; |
3836 | |
3837 | len = PTR_ERR(link); |
3838 | if (IS_ERR(link)) |
3839 | goto out; |
3840 | |
3841 | len = strlen(link); |
3842 | if (len > (unsigned) buflen) |
3843 | len = buflen; |
3844 | if (copy_to_user(buffer, link, len)) |
3845 | len = -EFAULT; |
3846 | out: |
3847 | return len; |
3848 | } |
3849 | |
3850 | /* |
3851 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that |
3852 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not |
3853 | * using) it for any given inode is up to filesystem. |
3854 | */ |
3855 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) |
3856 | { |
3857 | struct nameidata nd; |
3858 | void *cookie; |
3859 | int res; |
3860 | |
3861 | nd.depth = 0; |
3862 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
3863 | if (IS_ERR(cookie)) |
3864 | return PTR_ERR(cookie); |
3865 | |
3866 | res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); |
3867 | if (dentry->d_inode->i_op->put_link) |
3868 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); |
3869 | return res; |
3870 | } |
3871 | |
3872 | int vfs_follow_link(struct nameidata *nd, const char *link) |
3873 | { |
3874 | return __vfs_follow_link(nd, link); |
3875 | } |
3876 | |
3877 | /* get the link contents into pagecache */ |
3878 | static char *page_getlink(struct dentry * dentry, struct page **ppage) |
3879 | { |
3880 | char *kaddr; |
3881 | struct page *page; |
3882 | struct address_space *mapping = dentry->d_inode->i_mapping; |
3883 | page = read_mapping_page(mapping, 0, NULL); |
3884 | if (IS_ERR(page)) |
3885 | return (char*)page; |
3886 | *ppage = page; |
3887 | kaddr = kmap(page); |
3888 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); |
3889 | return kaddr; |
3890 | } |
3891 | |
3892 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) |
3893 | { |
3894 | struct page *page = NULL; |
3895 | char *s = page_getlink(dentry, &page); |
3896 | int res = vfs_readlink(dentry,buffer,buflen,s); |
3897 | if (page) { |
3898 | kunmap(page); |
3899 | page_cache_release(page); |
3900 | } |
3901 | return res; |
3902 | } |
3903 | |
3904 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
3905 | { |
3906 | struct page *page = NULL; |
3907 | nd_set_link(nd, page_getlink(dentry, &page)); |
3908 | return page; |
3909 | } |
3910 | |
3911 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
3912 | { |
3913 | struct page *page = cookie; |
3914 | |
3915 | if (page) { |
3916 | kunmap(page); |
3917 | page_cache_release(page); |
3918 | } |
3919 | } |
3920 | |
3921 | /* |
3922 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS |
3923 | */ |
3924 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) |
3925 | { |
3926 | struct address_space *mapping = inode->i_mapping; |
3927 | struct page *page; |
3928 | void *fsdata; |
3929 | int err; |
3930 | char *kaddr; |
3931 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
3932 | if (nofs) |
3933 | flags |= AOP_FLAG_NOFS; |
3934 | |
3935 | retry: |
3936 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
3937 | flags, &page, &fsdata); |
3938 | if (err) |
3939 | goto fail; |
3940 | |
3941 | kaddr = kmap_atomic(page); |
3942 | memcpy(kaddr, symname, len-1); |
3943 | kunmap_atomic(kaddr); |
3944 | |
3945 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, |
3946 | page, fsdata); |
3947 | if (err < 0) |
3948 | goto fail; |
3949 | if (err < len-1) |
3950 | goto retry; |
3951 | |
3952 | mark_inode_dirty(inode); |
3953 | return 0; |
3954 | fail: |
3955 | return err; |
3956 | } |
3957 | |
3958 | int page_symlink(struct inode *inode, const char *symname, int len) |
3959 | { |
3960 | return __page_symlink(inode, symname, len, |
3961 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
3962 | } |
3963 | |
3964 | const struct inode_operations page_symlink_inode_operations = { |
3965 | .readlink = generic_readlink, |
3966 | .follow_link = page_follow_link_light, |
3967 | .put_link = page_put_link, |
3968 | }; |
3969 | |
3970 | EXPORT_SYMBOL(user_path_at); |
3971 | EXPORT_SYMBOL(follow_down_one); |
3972 | EXPORT_SYMBOL(follow_down); |
3973 | EXPORT_SYMBOL(follow_up); |
3974 | EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ |
3975 | EXPORT_SYMBOL(getname); |
3976 | EXPORT_SYMBOL(lock_rename); |
3977 | EXPORT_SYMBOL(lookup_one_len); |
3978 | EXPORT_SYMBOL(page_follow_link_light); |
3979 | EXPORT_SYMBOL(page_put_link); |
3980 | EXPORT_SYMBOL(page_readlink); |
3981 | EXPORT_SYMBOL(__page_symlink); |
3982 | EXPORT_SYMBOL(page_symlink); |
3983 | EXPORT_SYMBOL(page_symlink_inode_operations); |
3984 | EXPORT_SYMBOL(kern_path); |
3985 | EXPORT_SYMBOL(vfs_path_lookup); |
3986 | EXPORT_SYMBOL(inode_permission); |
3987 | EXPORT_SYMBOL(unlock_rename); |
3988 | EXPORT_SYMBOL(vfs_create); |
3989 | EXPORT_SYMBOL(vfs_follow_link); |
3990 | EXPORT_SYMBOL(vfs_link); |
3991 | EXPORT_SYMBOL(vfs_mkdir); |
3992 | EXPORT_SYMBOL(vfs_mknod); |
3993 | EXPORT_SYMBOL(generic_permission); |
3994 | EXPORT_SYMBOL(vfs_readlink); |
3995 | EXPORT_SYMBOL(vfs_rename); |
3996 | EXPORT_SYMBOL(vfs_rmdir); |
3997 | EXPORT_SYMBOL(vfs_symlink); |
3998 | EXPORT_SYMBOL(vfs_unlink); |
3999 | EXPORT_SYMBOL(dentry_unhash); |
4000 | EXPORT_SYMBOL(generic_readlink); |
4001 |
Branches:
ben-wpan
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javiroman/ks7010
jz-2.6.34
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9