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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/module.h> |
19 | #include <linux/slab.h> |
20 | #include <linux/fs.h> |
21 | #include <linux/namei.h> |
22 | #include <linux/pagemap.h> |
23 | #include <linux/fsnotify.h> |
24 | #include <linux/personality.h> |
25 | #include <linux/security.h> |
26 | #include <linux/ima.h> |
27 | #include <linux/syscalls.h> |
28 | #include <linux/mount.h> |
29 | #include <linux/audit.h> |
30 | #include <linux/capability.h> |
31 | #include <linux/file.h> |
32 | #include <linux/fcntl.h> |
33 | #include <linux/device_cgroup.h> |
34 | #include <linux/fs_struct.h> |
35 | #include <asm/uaccess.h> |
36 | |
37 | #include "internal.h" |
38 | |
39 | /* [Feb-1997 T. Schoebel-Theuer] |
40 | * Fundamental changes in the pathname lookup mechanisms (namei) |
41 | * were necessary because of omirr. The reason is that omirr needs |
42 | * to know the _real_ pathname, not the user-supplied one, in case |
43 | * of symlinks (and also when transname replacements occur). |
44 | * |
45 | * The new code replaces the old recursive symlink resolution with |
46 | * an iterative one (in case of non-nested symlink chains). It does |
47 | * this with calls to <fs>_follow_link(). |
48 | * As a side effect, dir_namei(), _namei() and follow_link() are now |
49 | * replaced with a single function lookup_dentry() that can handle all |
50 | * the special cases of the former code. |
51 | * |
52 | * With the new dcache, the pathname is stored at each inode, at least as |
53 | * long as the refcount of the inode is positive. As a side effect, the |
54 | * size of the dcache depends on the inode cache and thus is dynamic. |
55 | * |
56 | * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink |
57 | * resolution to correspond with current state of the code. |
58 | * |
59 | * Note that the symlink resolution is not *completely* iterative. |
60 | * There is still a significant amount of tail- and mid- recursion in |
61 | * the algorithm. Also, note that <fs>_readlink() is not used in |
62 | * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() |
63 | * may return different results than <fs>_follow_link(). Many virtual |
64 | * filesystems (including /proc) exhibit this behavior. |
65 | */ |
66 | |
67 | /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: |
68 | * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL |
69 | * and the name already exists in form of a symlink, try to create the new |
70 | * name indicated by the symlink. The old code always complained that the |
71 | * name already exists, due to not following the symlink even if its target |
72 | * is nonexistent. The new semantics affects also mknod() and link() when |
73 | * the name is a symlink pointing to a non-existant name. |
74 | * |
75 | * I don't know which semantics is the right one, since I have no access |
76 | * to standards. But I found by trial that HP-UX 9.0 has the full "new" |
77 | * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the |
78 | * "old" one. Personally, I think the new semantics is much more logical. |
79 | * Note that "ln old new" where "new" is a symlink pointing to a non-existing |
80 | * file does succeed in both HP-UX and SunOs, but not in Solaris |
81 | * and in the old Linux semantics. |
82 | */ |
83 | |
84 | /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink |
85 | * semantics. See the comments in "open_namei" and "do_link" below. |
86 | * |
87 | * [10-Sep-98 Alan Modra] Another symlink change. |
88 | */ |
89 | |
90 | /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: |
91 | * inside the path - always follow. |
92 | * in the last component in creation/removal/renaming - never follow. |
93 | * if LOOKUP_FOLLOW passed - follow. |
94 | * if the pathname has trailing slashes - follow. |
95 | * otherwise - don't follow. |
96 | * (applied in that order). |
97 | * |
98 | * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT |
99 | * restored for 2.4. This is the last surviving part of old 4.2BSD bug. |
100 | * During the 2.4 we need to fix the userland stuff depending on it - |
101 | * hopefully we will be able to get rid of that wart in 2.5. So far only |
102 | * XEmacs seems to be relying on it... |
103 | */ |
104 | /* |
105 | * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) |
106 | * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives |
107 | * any extra contention... |
108 | */ |
109 | |
110 | /* In order to reduce some races, while at the same time doing additional |
111 | * checking and hopefully speeding things up, we copy filenames to the |
112 | * kernel data space before using them.. |
113 | * |
114 | * POSIX.1 2.4: an empty pathname is invalid (ENOENT). |
115 | * PATH_MAX includes the nul terminator --RR. |
116 | */ |
117 | static int do_getname(const char __user *filename, char *page) |
118 | { |
119 | int retval; |
120 | unsigned long len = PATH_MAX; |
121 | |
122 | if (!segment_eq(get_fs(), KERNEL_DS)) { |
123 | if ((unsigned long) filename >= TASK_SIZE) |
124 | return -EFAULT; |
125 | if (TASK_SIZE - (unsigned long) filename < PATH_MAX) |
126 | len = TASK_SIZE - (unsigned long) filename; |
127 | } |
128 | |
129 | retval = strncpy_from_user(page, filename, len); |
130 | if (retval > 0) { |
131 | if (retval < len) |
132 | return 0; |
133 | return -ENAMETOOLONG; |
134 | } else if (!retval) |
135 | retval = -ENOENT; |
136 | return retval; |
137 | } |
138 | |
139 | char * getname(const char __user * filename) |
140 | { |
141 | char *tmp, *result; |
142 | |
143 | result = ERR_PTR(-ENOMEM); |
144 | tmp = __getname(); |
145 | if (tmp) { |
146 | int retval = do_getname(filename, tmp); |
147 | |
148 | result = tmp; |
149 | if (retval < 0) { |
150 | __putname(tmp); |
151 | result = ERR_PTR(retval); |
152 | } |
153 | } |
154 | audit_getname(result); |
155 | return result; |
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 | /* |
170 | * This does basic POSIX ACL permission checking |
171 | */ |
172 | static int acl_permission_check(struct inode *inode, int mask, |
173 | int (*check_acl)(struct inode *inode, int mask)) |
174 | { |
175 | umode_t mode = inode->i_mode; |
176 | |
177 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
178 | |
179 | if (current_fsuid() == inode->i_uid) |
180 | mode >>= 6; |
181 | else { |
182 | if (IS_POSIXACL(inode) && (mode & S_IRWXG) && check_acl) { |
183 | int error = check_acl(inode, mask); |
184 | if (error != -EAGAIN) |
185 | return error; |
186 | } |
187 | |
188 | if (in_group_p(inode->i_gid)) |
189 | mode >>= 3; |
190 | } |
191 | |
192 | /* |
193 | * If the DACs are ok we don't need any capability check. |
194 | */ |
195 | if ((mask & ~mode) == 0) |
196 | return 0; |
197 | return -EACCES; |
198 | } |
199 | |
200 | /** |
201 | * generic_permission - check for access rights on a Posix-like filesystem |
202 | * @inode: inode to check access rights for |
203 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
204 | * @check_acl: optional callback to check for Posix ACLs |
205 | * |
206 | * Used to check for read/write/execute permissions on a file. |
207 | * We use "fsuid" for this, letting us set arbitrary permissions |
208 | * for filesystem access without changing the "normal" uids which |
209 | * are used for other things.. |
210 | */ |
211 | int generic_permission(struct inode *inode, int mask, |
212 | int (*check_acl)(struct inode *inode, int mask)) |
213 | { |
214 | int ret; |
215 | |
216 | /* |
217 | * Do the basic POSIX ACL permission checks. |
218 | */ |
219 | ret = acl_permission_check(inode, mask, check_acl); |
220 | if (ret != -EACCES) |
221 | return ret; |
222 | |
223 | /* |
224 | * Read/write DACs are always overridable. |
225 | * Executable DACs are overridable if at least one exec bit is set. |
226 | */ |
227 | if (!(mask & MAY_EXEC) || execute_ok(inode)) |
228 | if (capable(CAP_DAC_OVERRIDE)) |
229 | return 0; |
230 | |
231 | /* |
232 | * Searching includes executable on directories, else just read. |
233 | */ |
234 | mask &= MAY_READ | MAY_WRITE | MAY_EXEC; |
235 | if (mask == MAY_READ || (S_ISDIR(inode->i_mode) && !(mask & MAY_WRITE))) |
236 | if (capable(CAP_DAC_READ_SEARCH)) |
237 | return 0; |
238 | |
239 | return -EACCES; |
240 | } |
241 | |
242 | /** |
243 | * inode_permission - check for access rights to a given inode |
244 | * @inode: inode to check permission on |
245 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
246 | * |
247 | * Used to check for read/write/execute permissions on an inode. |
248 | * We use "fsuid" for this, letting us set arbitrary permissions |
249 | * for filesystem access without changing the "normal" uids which |
250 | * are used for other things. |
251 | */ |
252 | int inode_permission(struct inode *inode, int mask) |
253 | { |
254 | int retval; |
255 | |
256 | if (mask & MAY_WRITE) { |
257 | umode_t mode = inode->i_mode; |
258 | |
259 | /* |
260 | * Nobody gets write access to a read-only fs. |
261 | */ |
262 | if (IS_RDONLY(inode) && |
263 | (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) |
264 | return -EROFS; |
265 | |
266 | /* |
267 | * Nobody gets write access to an immutable file. |
268 | */ |
269 | if (IS_IMMUTABLE(inode)) |
270 | return -EACCES; |
271 | } |
272 | |
273 | if (inode->i_op->permission) |
274 | retval = inode->i_op->permission(inode, mask); |
275 | else |
276 | retval = generic_permission(inode, mask, inode->i_op->check_acl); |
277 | |
278 | if (retval) |
279 | return retval; |
280 | |
281 | retval = devcgroup_inode_permission(inode, mask); |
282 | if (retval) |
283 | return retval; |
284 | |
285 | return security_inode_permission(inode, |
286 | mask & (MAY_READ|MAY_WRITE|MAY_EXEC|MAY_APPEND)); |
287 | } |
288 | |
289 | /** |
290 | * file_permission - check for additional access rights to a given file |
291 | * @file: file to check access rights for |
292 | * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) |
293 | * |
294 | * Used to check for read/write/execute permissions on an already opened |
295 | * file. |
296 | * |
297 | * Note: |
298 | * Do not use this function in new code. All access checks should |
299 | * be done using inode_permission(). |
300 | */ |
301 | int file_permission(struct file *file, int mask) |
302 | { |
303 | return inode_permission(file->f_path.dentry->d_inode, mask); |
304 | } |
305 | |
306 | /* |
307 | * get_write_access() gets write permission for a file. |
308 | * put_write_access() releases this write permission. |
309 | * This is used for regular files. |
310 | * We cannot support write (and maybe mmap read-write shared) accesses and |
311 | * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode |
312 | * can have the following values: |
313 | * 0: no writers, no VM_DENYWRITE mappings |
314 | * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist |
315 | * > 0: (i_writecount) users are writing to the file. |
316 | * |
317 | * Normally we operate on that counter with atomic_{inc,dec} and it's safe |
318 | * except for the cases where we don't hold i_writecount yet. Then we need to |
319 | * use {get,deny}_write_access() - these functions check the sign and refuse |
320 | * to do the change if sign is wrong. Exclusion between them is provided by |
321 | * the inode->i_lock spinlock. |
322 | */ |
323 | |
324 | int get_write_access(struct inode * inode) |
325 | { |
326 | spin_lock(&inode->i_lock); |
327 | if (atomic_read(&inode->i_writecount) < 0) { |
328 | spin_unlock(&inode->i_lock); |
329 | return -ETXTBSY; |
330 | } |
331 | atomic_inc(&inode->i_writecount); |
332 | spin_unlock(&inode->i_lock); |
333 | |
334 | return 0; |
335 | } |
336 | |
337 | int deny_write_access(struct file * file) |
338 | { |
339 | struct inode *inode = file->f_path.dentry->d_inode; |
340 | |
341 | spin_lock(&inode->i_lock); |
342 | if (atomic_read(&inode->i_writecount) > 0) { |
343 | spin_unlock(&inode->i_lock); |
344 | return -ETXTBSY; |
345 | } |
346 | atomic_dec(&inode->i_writecount); |
347 | spin_unlock(&inode->i_lock); |
348 | |
349 | return 0; |
350 | } |
351 | |
352 | /** |
353 | * path_get - get a reference to a path |
354 | * @path: path to get the reference to |
355 | * |
356 | * Given a path increment the reference count to the dentry and the vfsmount. |
357 | */ |
358 | void path_get(struct path *path) |
359 | { |
360 | mntget(path->mnt); |
361 | dget(path->dentry); |
362 | } |
363 | EXPORT_SYMBOL(path_get); |
364 | |
365 | /** |
366 | * path_put - put a reference to a path |
367 | * @path: path to put the reference to |
368 | * |
369 | * Given a path decrement the reference count to the dentry and the vfsmount. |
370 | */ |
371 | void path_put(struct path *path) |
372 | { |
373 | dput(path->dentry); |
374 | mntput(path->mnt); |
375 | } |
376 | EXPORT_SYMBOL(path_put); |
377 | |
378 | /** |
379 | * release_open_intent - free up open intent resources |
380 | * @nd: pointer to nameidata |
381 | */ |
382 | void release_open_intent(struct nameidata *nd) |
383 | { |
384 | if (nd->intent.open.file->f_path.dentry == NULL) |
385 | put_filp(nd->intent.open.file); |
386 | else |
387 | fput(nd->intent.open.file); |
388 | } |
389 | |
390 | static inline struct dentry * |
391 | do_revalidate(struct dentry *dentry, struct nameidata *nd) |
392 | { |
393 | int status = dentry->d_op->d_revalidate(dentry, nd); |
394 | if (unlikely(status <= 0)) { |
395 | /* |
396 | * The dentry failed validation. |
397 | * If d_revalidate returned 0 attempt to invalidate |
398 | * the dentry otherwise d_revalidate is asking us |
399 | * to return a fail status. |
400 | */ |
401 | if (!status) { |
402 | if (!d_invalidate(dentry)) { |
403 | dput(dentry); |
404 | dentry = NULL; |
405 | } |
406 | } else { |
407 | dput(dentry); |
408 | dentry = ERR_PTR(status); |
409 | } |
410 | } |
411 | return dentry; |
412 | } |
413 | |
414 | /* |
415 | * force_reval_path - force revalidation of a dentry |
416 | * |
417 | * In some situations the path walking code will trust dentries without |
418 | * revalidating them. This causes problems for filesystems that depend on |
419 | * d_revalidate to handle file opens (e.g. NFSv4). When FS_REVAL_DOT is set |
420 | * (which indicates that it's possible for the dentry to go stale), force |
421 | * a d_revalidate call before proceeding. |
422 | * |
423 | * Returns 0 if the revalidation was successful. If the revalidation fails, |
424 | * either return the error returned by d_revalidate or -ESTALE if the |
425 | * revalidation it just returned 0. If d_revalidate returns 0, we attempt to |
426 | * invalidate the dentry. It's up to the caller to handle putting references |
427 | * to the path if necessary. |
428 | */ |
429 | static int |
430 | force_reval_path(struct path *path, struct nameidata *nd) |
431 | { |
432 | int status; |
433 | struct dentry *dentry = path->dentry; |
434 | |
435 | /* |
436 | * only check on filesystems where it's possible for the dentry to |
437 | * become stale. It's assumed that if this flag is set then the |
438 | * d_revalidate op will also be defined. |
439 | */ |
440 | if (!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) |
441 | return 0; |
442 | |
443 | status = dentry->d_op->d_revalidate(dentry, nd); |
444 | if (status > 0) |
445 | return 0; |
446 | |
447 | if (!status) { |
448 | d_invalidate(dentry); |
449 | status = -ESTALE; |
450 | } |
451 | return status; |
452 | } |
453 | |
454 | /* |
455 | * Short-cut version of permission(), for calling on directories |
456 | * during pathname resolution. Combines parts of permission() |
457 | * and generic_permission(), and tests ONLY for MAY_EXEC permission. |
458 | * |
459 | * If appropriate, check DAC only. If not appropriate, or |
460 | * short-cut DAC fails, then call ->permission() to do more |
461 | * complete permission check. |
462 | */ |
463 | static int exec_permission(struct inode *inode) |
464 | { |
465 | int ret; |
466 | |
467 | if (inode->i_op->permission) { |
468 | ret = inode->i_op->permission(inode, MAY_EXEC); |
469 | if (!ret) |
470 | goto ok; |
471 | return ret; |
472 | } |
473 | ret = acl_permission_check(inode, MAY_EXEC, inode->i_op->check_acl); |
474 | if (!ret) |
475 | goto ok; |
476 | |
477 | if (capable(CAP_DAC_OVERRIDE) || capable(CAP_DAC_READ_SEARCH)) |
478 | goto ok; |
479 | |
480 | return ret; |
481 | ok: |
482 | return security_inode_permission(inode, MAY_EXEC); |
483 | } |
484 | |
485 | static __always_inline void set_root(struct nameidata *nd) |
486 | { |
487 | if (!nd->root.mnt) { |
488 | struct fs_struct *fs = current->fs; |
489 | read_lock(&fs->lock); |
490 | nd->root = fs->root; |
491 | path_get(&nd->root); |
492 | read_unlock(&fs->lock); |
493 | } |
494 | } |
495 | |
496 | static int link_path_walk(const char *, struct nameidata *); |
497 | |
498 | static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link) |
499 | { |
500 | if (IS_ERR(link)) |
501 | goto fail; |
502 | |
503 | if (*link == '/') { |
504 | set_root(nd); |
505 | path_put(&nd->path); |
506 | nd->path = nd->root; |
507 | path_get(&nd->root); |
508 | } |
509 | |
510 | return link_path_walk(link, nd); |
511 | fail: |
512 | path_put(&nd->path); |
513 | return PTR_ERR(link); |
514 | } |
515 | |
516 | static void path_put_conditional(struct path *path, struct nameidata *nd) |
517 | { |
518 | dput(path->dentry); |
519 | if (path->mnt != nd->path.mnt) |
520 | mntput(path->mnt); |
521 | } |
522 | |
523 | static inline void path_to_nameidata(struct path *path, struct nameidata *nd) |
524 | { |
525 | dput(nd->path.dentry); |
526 | if (nd->path.mnt != path->mnt) |
527 | mntput(nd->path.mnt); |
528 | nd->path.mnt = path->mnt; |
529 | nd->path.dentry = path->dentry; |
530 | } |
531 | |
532 | static __always_inline int |
533 | __do_follow_link(struct path *path, struct nameidata *nd, void **p) |
534 | { |
535 | int error; |
536 | struct dentry *dentry = path->dentry; |
537 | |
538 | touch_atime(path->mnt, dentry); |
539 | nd_set_link(nd, NULL); |
540 | |
541 | if (path->mnt != nd->path.mnt) { |
542 | path_to_nameidata(path, nd); |
543 | dget(dentry); |
544 | } |
545 | mntget(path->mnt); |
546 | nd->last_type = LAST_BIND; |
547 | *p = dentry->d_inode->i_op->follow_link(dentry, nd); |
548 | error = PTR_ERR(*p); |
549 | if (!IS_ERR(*p)) { |
550 | char *s = nd_get_link(nd); |
551 | error = 0; |
552 | if (s) |
553 | error = __vfs_follow_link(nd, s); |
554 | else if (nd->last_type == LAST_BIND) { |
555 | error = force_reval_path(&nd->path, nd); |
556 | if (error) |
557 | path_put(&nd->path); |
558 | } |
559 | } |
560 | return error; |
561 | } |
562 | |
563 | /* |
564 | * This limits recursive symlink follows to 8, while |
565 | * limiting consecutive symlinks to 40. |
566 | * |
567 | * Without that kind of total limit, nasty chains of consecutive |
568 | * symlinks can cause almost arbitrarily long lookups. |
569 | */ |
570 | static inline int do_follow_link(struct path *path, struct nameidata *nd) |
571 | { |
572 | void *cookie; |
573 | int err = -ELOOP; |
574 | if (current->link_count >= MAX_NESTED_LINKS) |
575 | goto loop; |
576 | if (current->total_link_count >= 40) |
577 | goto loop; |
578 | BUG_ON(nd->depth >= MAX_NESTED_LINKS); |
579 | cond_resched(); |
580 | err = security_inode_follow_link(path->dentry, nd); |
581 | if (err) |
582 | goto loop; |
583 | current->link_count++; |
584 | current->total_link_count++; |
585 | nd->depth++; |
586 | err = __do_follow_link(path, nd, &cookie); |
587 | if (!IS_ERR(cookie) && path->dentry->d_inode->i_op->put_link) |
588 | path->dentry->d_inode->i_op->put_link(path->dentry, nd, cookie); |
589 | path_put(path); |
590 | current->link_count--; |
591 | nd->depth--; |
592 | return err; |
593 | loop: |
594 | path_put_conditional(path, nd); |
595 | path_put(&nd->path); |
596 | return err; |
597 | } |
598 | |
599 | int follow_up(struct path *path) |
600 | { |
601 | struct vfsmount *parent; |
602 | struct dentry *mountpoint; |
603 | spin_lock(&vfsmount_lock); |
604 | parent = path->mnt->mnt_parent; |
605 | if (parent == path->mnt) { |
606 | spin_unlock(&vfsmount_lock); |
607 | return 0; |
608 | } |
609 | mntget(parent); |
610 | mountpoint = dget(path->mnt->mnt_mountpoint); |
611 | spin_unlock(&vfsmount_lock); |
612 | dput(path->dentry); |
613 | path->dentry = mountpoint; |
614 | mntput(path->mnt); |
615 | path->mnt = parent; |
616 | return 1; |
617 | } |
618 | |
619 | /* no need for dcache_lock, as serialization is taken care in |
620 | * namespace.c |
621 | */ |
622 | static int __follow_mount(struct path *path) |
623 | { |
624 | int res = 0; |
625 | while (d_mountpoint(path->dentry)) { |
626 | struct vfsmount *mounted = lookup_mnt(path); |
627 | if (!mounted) |
628 | break; |
629 | dput(path->dentry); |
630 | if (res) |
631 | mntput(path->mnt); |
632 | path->mnt = mounted; |
633 | path->dentry = dget(mounted->mnt_root); |
634 | res = 1; |
635 | } |
636 | return res; |
637 | } |
638 | |
639 | static void follow_mount(struct path *path) |
640 | { |
641 | while (d_mountpoint(path->dentry)) { |
642 | struct vfsmount *mounted = lookup_mnt(path); |
643 | if (!mounted) |
644 | break; |
645 | dput(path->dentry); |
646 | mntput(path->mnt); |
647 | path->mnt = mounted; |
648 | path->dentry = dget(mounted->mnt_root); |
649 | } |
650 | } |
651 | |
652 | /* no need for dcache_lock, as serialization is taken care in |
653 | * namespace.c |
654 | */ |
655 | int follow_down(struct path *path) |
656 | { |
657 | struct vfsmount *mounted; |
658 | |
659 | mounted = lookup_mnt(path); |
660 | if (mounted) { |
661 | dput(path->dentry); |
662 | mntput(path->mnt); |
663 | path->mnt = mounted; |
664 | path->dentry = dget(mounted->mnt_root); |
665 | return 1; |
666 | } |
667 | return 0; |
668 | } |
669 | |
670 | static __always_inline void follow_dotdot(struct nameidata *nd) |
671 | { |
672 | set_root(nd); |
673 | |
674 | while(1) { |
675 | struct dentry *old = nd->path.dentry; |
676 | |
677 | if (nd->path.dentry == nd->root.dentry && |
678 | nd->path.mnt == nd->root.mnt) { |
679 | break; |
680 | } |
681 | if (nd->path.dentry != nd->path.mnt->mnt_root) { |
682 | /* rare case of legitimate dget_parent()... */ |
683 | nd->path.dentry = dget_parent(nd->path.dentry); |
684 | dput(old); |
685 | break; |
686 | } |
687 | if (!follow_up(&nd->path)) |
688 | break; |
689 | } |
690 | follow_mount(&nd->path); |
691 | } |
692 | |
693 | /* |
694 | * It's more convoluted than I'd like it to be, but... it's still fairly |
695 | * small and for now I'd prefer to have fast path as straight as possible. |
696 | * It _is_ time-critical. |
697 | */ |
698 | static int do_lookup(struct nameidata *nd, struct qstr *name, |
699 | struct path *path) |
700 | { |
701 | struct vfsmount *mnt = nd->path.mnt; |
702 | struct dentry *dentry, *parent; |
703 | struct inode *dir; |
704 | /* |
705 | * See if the low-level filesystem might want |
706 | * to use its own hash.. |
707 | */ |
708 | if (nd->path.dentry->d_op && nd->path.dentry->d_op->d_hash) { |
709 | int err = nd->path.dentry->d_op->d_hash(nd->path.dentry, name); |
710 | if (err < 0) |
711 | return err; |
712 | } |
713 | |
714 | dentry = __d_lookup(nd->path.dentry, name); |
715 | if (!dentry) |
716 | goto need_lookup; |
717 | if (dentry->d_op && dentry->d_op->d_revalidate) |
718 | goto need_revalidate; |
719 | done: |
720 | path->mnt = mnt; |
721 | path->dentry = dentry; |
722 | __follow_mount(path); |
723 | return 0; |
724 | |
725 | need_lookup: |
726 | parent = nd->path.dentry; |
727 | dir = parent->d_inode; |
728 | |
729 | mutex_lock(&dir->i_mutex); |
730 | /* |
731 | * First re-do the cached lookup just in case it was created |
732 | * while we waited for the directory semaphore.. |
733 | * |
734 | * FIXME! This could use version numbering or similar to |
735 | * avoid unnecessary cache lookups. |
736 | * |
737 | * The "dcache_lock" is purely to protect the RCU list walker |
738 | * from concurrent renames at this point (we mustn't get false |
739 | * negatives from the RCU list walk here, unlike the optimistic |
740 | * fast walk). |
741 | * |
742 | * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup |
743 | */ |
744 | dentry = d_lookup(parent, name); |
745 | if (!dentry) { |
746 | struct dentry *new; |
747 | |
748 | /* Don't create child dentry for a dead directory. */ |
749 | dentry = ERR_PTR(-ENOENT); |
750 | if (IS_DEADDIR(dir)) |
751 | goto out_unlock; |
752 | |
753 | new = d_alloc(parent, name); |
754 | dentry = ERR_PTR(-ENOMEM); |
755 | if (new) { |
756 | dentry = dir->i_op->lookup(dir, new, nd); |
757 | if (dentry) |
758 | dput(new); |
759 | else |
760 | dentry = new; |
761 | } |
762 | out_unlock: |
763 | mutex_unlock(&dir->i_mutex); |
764 | if (IS_ERR(dentry)) |
765 | goto fail; |
766 | goto done; |
767 | } |
768 | |
769 | /* |
770 | * Uhhuh! Nasty case: the cache was re-populated while |
771 | * we waited on the semaphore. Need to revalidate. |
772 | */ |
773 | mutex_unlock(&dir->i_mutex); |
774 | if (dentry->d_op && dentry->d_op->d_revalidate) { |
775 | dentry = do_revalidate(dentry, nd); |
776 | if (!dentry) |
777 | dentry = ERR_PTR(-ENOENT); |
778 | } |
779 | if (IS_ERR(dentry)) |
780 | goto fail; |
781 | goto done; |
782 | |
783 | need_revalidate: |
784 | dentry = do_revalidate(dentry, nd); |
785 | if (!dentry) |
786 | goto need_lookup; |
787 | if (IS_ERR(dentry)) |
788 | goto fail; |
789 | goto done; |
790 | |
791 | fail: |
792 | return PTR_ERR(dentry); |
793 | } |
794 | |
795 | /* |
796 | * This is a temporary kludge to deal with "automount" symlinks; proper |
797 | * solution is to trigger them on follow_mount(), so that do_lookup() |
798 | * would DTRT. To be killed before 2.6.34-final. |
799 | */ |
800 | static inline int follow_on_final(struct inode *inode, unsigned lookup_flags) |
801 | { |
802 | return inode && unlikely(inode->i_op->follow_link) && |
803 | ((lookup_flags & LOOKUP_FOLLOW) || S_ISDIR(inode->i_mode)); |
804 | } |
805 | |
806 | /* |
807 | * Name resolution. |
808 | * This is the basic name resolution function, turning a pathname into |
809 | * the final dentry. We expect 'base' to be positive and a directory. |
810 | * |
811 | * Returns 0 and nd will have valid dentry and mnt on success. |
812 | * Returns error and drops reference to input namei data on failure. |
813 | */ |
814 | static int link_path_walk(const char *name, struct nameidata *nd) |
815 | { |
816 | struct path next; |
817 | struct inode *inode; |
818 | int err; |
819 | unsigned int lookup_flags = nd->flags; |
820 | |
821 | while (*name=='/') |
822 | name++; |
823 | if (!*name) |
824 | goto return_reval; |
825 | |
826 | inode = nd->path.dentry->d_inode; |
827 | if (nd->depth) |
828 | lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE); |
829 | |
830 | /* At this point we know we have a real path component. */ |
831 | for(;;) { |
832 | unsigned long hash; |
833 | struct qstr this; |
834 | unsigned int c; |
835 | |
836 | nd->flags |= LOOKUP_CONTINUE; |
837 | err = exec_permission(inode); |
838 | if (err) |
839 | break; |
840 | |
841 | this.name = name; |
842 | c = *(const unsigned char *)name; |
843 | |
844 | hash = init_name_hash(); |
845 | do { |
846 | name++; |
847 | hash = partial_name_hash(c, hash); |
848 | c = *(const unsigned char *)name; |
849 | } while (c && (c != '/')); |
850 | this.len = name - (const char *) this.name; |
851 | this.hash = end_name_hash(hash); |
852 | |
853 | /* remove trailing slashes? */ |
854 | if (!c) |
855 | goto last_component; |
856 | while (*++name == '/'); |
857 | if (!*name) |
858 | goto last_with_slashes; |
859 | |
860 | /* |
861 | * "." and ".." are special - ".." especially so because it has |
862 | * to be able to know about the current root directory and |
863 | * parent relationships. |
864 | */ |
865 | if (this.name[0] == '.') switch (this.len) { |
866 | default: |
867 | break; |
868 | case 2: |
869 | if (this.name[1] != '.') |
870 | break; |
871 | follow_dotdot(nd); |
872 | inode = nd->path.dentry->d_inode; |
873 | /* fallthrough */ |
874 | case 1: |
875 | continue; |
876 | } |
877 | /* This does the actual lookups.. */ |
878 | err = do_lookup(nd, &this, &next); |
879 | if (err) |
880 | break; |
881 | |
882 | err = -ENOENT; |
883 | inode = next.dentry->d_inode; |
884 | if (!inode) |
885 | goto out_dput; |
886 | |
887 | if (inode->i_op->follow_link) { |
888 | err = do_follow_link(&next, nd); |
889 | if (err) |
890 | goto return_err; |
891 | err = -ENOENT; |
892 | inode = nd->path.dentry->d_inode; |
893 | if (!inode) |
894 | break; |
895 | } else |
896 | path_to_nameidata(&next, nd); |
897 | err = -ENOTDIR; |
898 | if (!inode->i_op->lookup) |
899 | break; |
900 | continue; |
901 | /* here ends the main loop */ |
902 | |
903 | last_with_slashes: |
904 | lookup_flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; |
905 | last_component: |
906 | /* Clear LOOKUP_CONTINUE iff it was previously unset */ |
907 | nd->flags &= lookup_flags | ~LOOKUP_CONTINUE; |
908 | if (lookup_flags & LOOKUP_PARENT) |
909 | goto lookup_parent; |
910 | if (this.name[0] == '.') switch (this.len) { |
911 | default: |
912 | break; |
913 | case 2: |
914 | if (this.name[1] != '.') |
915 | break; |
916 | follow_dotdot(nd); |
917 | inode = nd->path.dentry->d_inode; |
918 | /* fallthrough */ |
919 | case 1: |
920 | goto return_reval; |
921 | } |
922 | err = do_lookup(nd, &this, &next); |
923 | if (err) |
924 | break; |
925 | inode = next.dentry->d_inode; |
926 | if (follow_on_final(inode, lookup_flags)) { |
927 | err = do_follow_link(&next, nd); |
928 | if (err) |
929 | goto return_err; |
930 | inode = nd->path.dentry->d_inode; |
931 | } else |
932 | path_to_nameidata(&next, nd); |
933 | err = -ENOENT; |
934 | if (!inode) |
935 | break; |
936 | if (lookup_flags & LOOKUP_DIRECTORY) { |
937 | err = -ENOTDIR; |
938 | if (!inode->i_op->lookup) |
939 | break; |
940 | } |
941 | goto return_base; |
942 | lookup_parent: |
943 | nd->last = this; |
944 | nd->last_type = LAST_NORM; |
945 | if (this.name[0] != '.') |
946 | goto return_base; |
947 | if (this.len == 1) |
948 | nd->last_type = LAST_DOT; |
949 | else if (this.len == 2 && this.name[1] == '.') |
950 | nd->last_type = LAST_DOTDOT; |
951 | else |
952 | goto return_base; |
953 | return_reval: |
954 | /* |
955 | * We bypassed the ordinary revalidation routines. |
956 | * We may need to check the cached dentry for staleness. |
957 | */ |
958 | if (nd->path.dentry && nd->path.dentry->d_sb && |
959 | (nd->path.dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)) { |
960 | err = -ESTALE; |
961 | /* Note: we do not d_invalidate() */ |
962 | if (!nd->path.dentry->d_op->d_revalidate( |
963 | nd->path.dentry, nd)) |
964 | break; |
965 | } |
966 | return_base: |
967 | return 0; |
968 | out_dput: |
969 | path_put_conditional(&next, nd); |
970 | break; |
971 | } |
972 | path_put(&nd->path); |
973 | return_err: |
974 | return err; |
975 | } |
976 | |
977 | static int path_walk(const char *name, struct nameidata *nd) |
978 | { |
979 | struct path save = nd->path; |
980 | int result; |
981 | |
982 | current->total_link_count = 0; |
983 | |
984 | /* make sure the stuff we saved doesn't go away */ |
985 | path_get(&save); |
986 | |
987 | result = link_path_walk(name, nd); |
988 | if (result == -ESTALE) { |
989 | /* nd->path had been dropped */ |
990 | current->total_link_count = 0; |
991 | nd->path = save; |
992 | path_get(&nd->path); |
993 | nd->flags |= LOOKUP_REVAL; |
994 | result = link_path_walk(name, nd); |
995 | } |
996 | |
997 | path_put(&save); |
998 | |
999 | return result; |
1000 | } |
1001 | |
1002 | static int path_init(int dfd, const char *name, unsigned int flags, struct nameidata *nd) |
1003 | { |
1004 | int retval = 0; |
1005 | int fput_needed; |
1006 | struct file *file; |
1007 | |
1008 | nd->last_type = LAST_ROOT; /* if there are only slashes... */ |
1009 | nd->flags = flags; |
1010 | nd->depth = 0; |
1011 | nd->root.mnt = NULL; |
1012 | |
1013 | if (*name=='/') { |
1014 | set_root(nd); |
1015 | nd->path = nd->root; |
1016 | path_get(&nd->root); |
1017 | } else if (dfd == AT_FDCWD) { |
1018 | struct fs_struct *fs = current->fs; |
1019 | read_lock(&fs->lock); |
1020 | nd->path = fs->pwd; |
1021 | path_get(&fs->pwd); |
1022 | read_unlock(&fs->lock); |
1023 | } else { |
1024 | struct dentry *dentry; |
1025 | |
1026 | file = fget_light(dfd, &fput_needed); |
1027 | retval = -EBADF; |
1028 | if (!file) |
1029 | goto out_fail; |
1030 | |
1031 | dentry = file->f_path.dentry; |
1032 | |
1033 | retval = -ENOTDIR; |
1034 | if (!S_ISDIR(dentry->d_inode->i_mode)) |
1035 | goto fput_fail; |
1036 | |
1037 | retval = file_permission(file, MAY_EXEC); |
1038 | if (retval) |
1039 | goto fput_fail; |
1040 | |
1041 | nd->path = file->f_path; |
1042 | path_get(&file->f_path); |
1043 | |
1044 | fput_light(file, fput_needed); |
1045 | } |
1046 | return 0; |
1047 | |
1048 | fput_fail: |
1049 | fput_light(file, fput_needed); |
1050 | out_fail: |
1051 | return retval; |
1052 | } |
1053 | |
1054 | /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ |
1055 | static int do_path_lookup(int dfd, const char *name, |
1056 | unsigned int flags, struct nameidata *nd) |
1057 | { |
1058 | int retval = path_init(dfd, name, flags, nd); |
1059 | if (!retval) |
1060 | retval = path_walk(name, nd); |
1061 | if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && |
1062 | nd->path.dentry->d_inode)) |
1063 | audit_inode(name, nd->path.dentry); |
1064 | if (nd->root.mnt) { |
1065 | path_put(&nd->root); |
1066 | nd->root.mnt = NULL; |
1067 | } |
1068 | return retval; |
1069 | } |
1070 | |
1071 | int path_lookup(const char *name, unsigned int flags, |
1072 | struct nameidata *nd) |
1073 | { |
1074 | return do_path_lookup(AT_FDCWD, name, flags, nd); |
1075 | } |
1076 | |
1077 | int kern_path(const char *name, unsigned int flags, struct path *path) |
1078 | { |
1079 | struct nameidata nd; |
1080 | int res = do_path_lookup(AT_FDCWD, name, flags, &nd); |
1081 | if (!res) |
1082 | *path = nd.path; |
1083 | return res; |
1084 | } |
1085 | |
1086 | /** |
1087 | * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair |
1088 | * @dentry: pointer to dentry of the base directory |
1089 | * @mnt: pointer to vfs mount of the base directory |
1090 | * @name: pointer to file name |
1091 | * @flags: lookup flags |
1092 | * @nd: pointer to nameidata |
1093 | */ |
1094 | int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, |
1095 | const char *name, unsigned int flags, |
1096 | struct nameidata *nd) |
1097 | { |
1098 | int retval; |
1099 | |
1100 | /* same as do_path_lookup */ |
1101 | nd->last_type = LAST_ROOT; |
1102 | nd->flags = flags; |
1103 | nd->depth = 0; |
1104 | |
1105 | nd->path.dentry = dentry; |
1106 | nd->path.mnt = mnt; |
1107 | path_get(&nd->path); |
1108 | nd->root = nd->path; |
1109 | path_get(&nd->root); |
1110 | |
1111 | retval = path_walk(name, nd); |
1112 | if (unlikely(!retval && !audit_dummy_context() && nd->path.dentry && |
1113 | nd->path.dentry->d_inode)) |
1114 | audit_inode(name, nd->path.dentry); |
1115 | |
1116 | path_put(&nd->root); |
1117 | nd->root.mnt = NULL; |
1118 | |
1119 | return retval; |
1120 | } |
1121 | |
1122 | static struct dentry *__lookup_hash(struct qstr *name, |
1123 | struct dentry *base, struct nameidata *nd) |
1124 | { |
1125 | struct dentry *dentry; |
1126 | struct inode *inode; |
1127 | int err; |
1128 | |
1129 | inode = base->d_inode; |
1130 | |
1131 | /* |
1132 | * See if the low-level filesystem might want |
1133 | * to use its own hash.. |
1134 | */ |
1135 | if (base->d_op && base->d_op->d_hash) { |
1136 | err = base->d_op->d_hash(base, name); |
1137 | dentry = ERR_PTR(err); |
1138 | if (err < 0) |
1139 | goto out; |
1140 | } |
1141 | |
1142 | dentry = __d_lookup(base, name); |
1143 | |
1144 | /* lockess __d_lookup may fail due to concurrent d_move() |
1145 | * in some unrelated directory, so try with d_lookup |
1146 | */ |
1147 | if (!dentry) |
1148 | dentry = d_lookup(base, name); |
1149 | |
1150 | if (dentry && dentry->d_op && dentry->d_op->d_revalidate) |
1151 | dentry = do_revalidate(dentry, nd); |
1152 | |
1153 | if (!dentry) { |
1154 | struct dentry *new; |
1155 | |
1156 | /* Don't create child dentry for a dead directory. */ |
1157 | dentry = ERR_PTR(-ENOENT); |
1158 | if (IS_DEADDIR(inode)) |
1159 | goto out; |
1160 | |
1161 | new = d_alloc(base, name); |
1162 | dentry = ERR_PTR(-ENOMEM); |
1163 | if (!new) |
1164 | goto out; |
1165 | dentry = inode->i_op->lookup(inode, new, nd); |
1166 | if (!dentry) |
1167 | dentry = new; |
1168 | else |
1169 | dput(new); |
1170 | } |
1171 | out: |
1172 | return dentry; |
1173 | } |
1174 | |
1175 | /* |
1176 | * Restricted form of lookup. Doesn't follow links, single-component only, |
1177 | * needs parent already locked. Doesn't follow mounts. |
1178 | * SMP-safe. |
1179 | */ |
1180 | static struct dentry *lookup_hash(struct nameidata *nd) |
1181 | { |
1182 | int err; |
1183 | |
1184 | err = exec_permission(nd->path.dentry->d_inode); |
1185 | if (err) |
1186 | return ERR_PTR(err); |
1187 | return __lookup_hash(&nd->last, nd->path.dentry, nd); |
1188 | } |
1189 | |
1190 | static int __lookup_one_len(const char *name, struct qstr *this, |
1191 | struct dentry *base, int len) |
1192 | { |
1193 | unsigned long hash; |
1194 | unsigned int c; |
1195 | |
1196 | this->name = name; |
1197 | this->len = len; |
1198 | if (!len) |
1199 | return -EACCES; |
1200 | |
1201 | hash = init_name_hash(); |
1202 | while (len--) { |
1203 | c = *(const unsigned char *)name++; |
1204 | if (c == '/' || c == '\0') |
1205 | return -EACCES; |
1206 | hash = partial_name_hash(c, hash); |
1207 | } |
1208 | this->hash = end_name_hash(hash); |
1209 | return 0; |
1210 | } |
1211 | |
1212 | /** |
1213 | * lookup_one_len - filesystem helper to lookup single pathname component |
1214 | * @name: pathname component to lookup |
1215 | * @base: base directory to lookup from |
1216 | * @len: maximum length @len should be interpreted to |
1217 | * |
1218 | * Note that this routine is purely a helper for filesystem usage and should |
1219 | * not be called by generic code. Also note that by using this function the |
1220 | * nameidata argument is passed to the filesystem methods and a filesystem |
1221 | * using this helper needs to be prepared for that. |
1222 | */ |
1223 | struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) |
1224 | { |
1225 | int err; |
1226 | struct qstr this; |
1227 | |
1228 | WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); |
1229 | |
1230 | err = __lookup_one_len(name, &this, base, len); |
1231 | if (err) |
1232 | return ERR_PTR(err); |
1233 | |
1234 | err = exec_permission(base->d_inode); |
1235 | if (err) |
1236 | return ERR_PTR(err); |
1237 | return __lookup_hash(&this, base, NULL); |
1238 | } |
1239 | |
1240 | int user_path_at(int dfd, const char __user *name, unsigned flags, |
1241 | struct path *path) |
1242 | { |
1243 | struct nameidata nd; |
1244 | char *tmp = getname(name); |
1245 | int err = PTR_ERR(tmp); |
1246 | if (!IS_ERR(tmp)) { |
1247 | |
1248 | BUG_ON(flags & LOOKUP_PARENT); |
1249 | |
1250 | err = do_path_lookup(dfd, tmp, flags, &nd); |
1251 | putname(tmp); |
1252 | if (!err) |
1253 | *path = nd.path; |
1254 | } |
1255 | return err; |
1256 | } |
1257 | |
1258 | static int user_path_parent(int dfd, const char __user *path, |
1259 | struct nameidata *nd, char **name) |
1260 | { |
1261 | char *s = getname(path); |
1262 | int error; |
1263 | |
1264 | if (IS_ERR(s)) |
1265 | return PTR_ERR(s); |
1266 | |
1267 | error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd); |
1268 | if (error) |
1269 | putname(s); |
1270 | else |
1271 | *name = s; |
1272 | |
1273 | return error; |
1274 | } |
1275 | |
1276 | /* |
1277 | * It's inline, so penalty for filesystems that don't use sticky bit is |
1278 | * minimal. |
1279 | */ |
1280 | static inline int check_sticky(struct inode *dir, struct inode *inode) |
1281 | { |
1282 | uid_t fsuid = current_fsuid(); |
1283 | |
1284 | if (!(dir->i_mode & S_ISVTX)) |
1285 | return 0; |
1286 | if (inode->i_uid == fsuid) |
1287 | return 0; |
1288 | if (dir->i_uid == fsuid) |
1289 | return 0; |
1290 | return !capable(CAP_FOWNER); |
1291 | } |
1292 | |
1293 | /* |
1294 | * Check whether we can remove a link victim from directory dir, check |
1295 | * whether the type of victim is right. |
1296 | * 1. We can't do it if dir is read-only (done in permission()) |
1297 | * 2. We should have write and exec permissions on dir |
1298 | * 3. We can't remove anything from append-only dir |
1299 | * 4. We can't do anything with immutable dir (done in permission()) |
1300 | * 5. If the sticky bit on dir is set we should either |
1301 | * a. be owner of dir, or |
1302 | * b. be owner of victim, or |
1303 | * c. have CAP_FOWNER capability |
1304 | * 6. If the victim is append-only or immutable we can't do antyhing with |
1305 | * links pointing to it. |
1306 | * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. |
1307 | * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. |
1308 | * 9. We can't remove a root or mountpoint. |
1309 | * 10. We don't allow removal of NFS sillyrenamed files; it's handled by |
1310 | * nfs_async_unlink(). |
1311 | */ |
1312 | static int may_delete(struct inode *dir,struct dentry *victim,int isdir) |
1313 | { |
1314 | int error; |
1315 | |
1316 | if (!victim->d_inode) |
1317 | return -ENOENT; |
1318 | |
1319 | BUG_ON(victim->d_parent->d_inode != dir); |
1320 | audit_inode_child(victim, dir); |
1321 | |
1322 | error = inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1323 | if (error) |
1324 | return error; |
1325 | if (IS_APPEND(dir)) |
1326 | return -EPERM; |
1327 | if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)|| |
1328 | IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode)) |
1329 | return -EPERM; |
1330 | if (isdir) { |
1331 | if (!S_ISDIR(victim->d_inode->i_mode)) |
1332 | return -ENOTDIR; |
1333 | if (IS_ROOT(victim)) |
1334 | return -EBUSY; |
1335 | } else if (S_ISDIR(victim->d_inode->i_mode)) |
1336 | return -EISDIR; |
1337 | if (IS_DEADDIR(dir)) |
1338 | return -ENOENT; |
1339 | if (victim->d_flags & DCACHE_NFSFS_RENAMED) |
1340 | return -EBUSY; |
1341 | return 0; |
1342 | } |
1343 | |
1344 | /* Check whether we can create an object with dentry child in directory |
1345 | * dir. |
1346 | * 1. We can't do it if child already exists (open has special treatment for |
1347 | * this case, but since we are inlined it's OK) |
1348 | * 2. We can't do it if dir is read-only (done in permission()) |
1349 | * 3. We should have write and exec permissions on dir |
1350 | * 4. We can't do it if dir is immutable (done in permission()) |
1351 | */ |
1352 | static inline int may_create(struct inode *dir, struct dentry *child) |
1353 | { |
1354 | if (child->d_inode) |
1355 | return -EEXIST; |
1356 | if (IS_DEADDIR(dir)) |
1357 | return -ENOENT; |
1358 | return inode_permission(dir, MAY_WRITE | MAY_EXEC); |
1359 | } |
1360 | |
1361 | /* |
1362 | * p1 and p2 should be directories on the same fs. |
1363 | */ |
1364 | struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) |
1365 | { |
1366 | struct dentry *p; |
1367 | |
1368 | if (p1 == p2) { |
1369 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1370 | return NULL; |
1371 | } |
1372 | |
1373 | mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1374 | |
1375 | p = d_ancestor(p2, p1); |
1376 | if (p) { |
1377 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); |
1378 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); |
1379 | return p; |
1380 | } |
1381 | |
1382 | p = d_ancestor(p1, p2); |
1383 | if (p) { |
1384 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1385 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); |
1386 | return p; |
1387 | } |
1388 | |
1389 | mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); |
1390 | mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); |
1391 | return NULL; |
1392 | } |
1393 | |
1394 | void unlock_rename(struct dentry *p1, struct dentry *p2) |
1395 | { |
1396 | mutex_unlock(&p1->d_inode->i_mutex); |
1397 | if (p1 != p2) { |
1398 | mutex_unlock(&p2->d_inode->i_mutex); |
1399 | mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); |
1400 | } |
1401 | } |
1402 | |
1403 | int vfs_create(struct inode *dir, struct dentry *dentry, int mode, |
1404 | struct nameidata *nd) |
1405 | { |
1406 | int error = may_create(dir, dentry); |
1407 | |
1408 | if (error) |
1409 | return error; |
1410 | |
1411 | if (!dir->i_op->create) |
1412 | return -EACCES; /* shouldn't it be ENOSYS? */ |
1413 | mode &= S_IALLUGO; |
1414 | mode |= S_IFREG; |
1415 | error = security_inode_create(dir, dentry, mode); |
1416 | if (error) |
1417 | return error; |
1418 | error = dir->i_op->create(dir, dentry, mode, nd); |
1419 | if (!error) |
1420 | fsnotify_create(dir, dentry); |
1421 | return error; |
1422 | } |
1423 | |
1424 | int may_open(struct path *path, int acc_mode, int flag) |
1425 | { |
1426 | struct dentry *dentry = path->dentry; |
1427 | struct inode *inode = dentry->d_inode; |
1428 | int error; |
1429 | |
1430 | if (!inode) |
1431 | return -ENOENT; |
1432 | |
1433 | switch (inode->i_mode & S_IFMT) { |
1434 | case S_IFLNK: |
1435 | return -ELOOP; |
1436 | case S_IFDIR: |
1437 | if (acc_mode & MAY_WRITE) |
1438 | return -EISDIR; |
1439 | break; |
1440 | case S_IFBLK: |
1441 | case S_IFCHR: |
1442 | if (path->mnt->mnt_flags & MNT_NODEV) |
1443 | return -EACCES; |
1444 | /*FALLTHRU*/ |
1445 | case S_IFIFO: |
1446 | case S_IFSOCK: |
1447 | flag &= ~O_TRUNC; |
1448 | break; |
1449 | } |
1450 | |
1451 | error = inode_permission(inode, acc_mode); |
1452 | if (error) |
1453 | return error; |
1454 | |
1455 | /* |
1456 | * An append-only file must be opened in append mode for writing. |
1457 | */ |
1458 | if (IS_APPEND(inode)) { |
1459 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) |
1460 | return -EPERM; |
1461 | if (flag & O_TRUNC) |
1462 | return -EPERM; |
1463 | } |
1464 | |
1465 | /* O_NOATIME can only be set by the owner or superuser */ |
1466 | if (flag & O_NOATIME && !is_owner_or_cap(inode)) |
1467 | return -EPERM; |
1468 | |
1469 | /* |
1470 | * Ensure there are no outstanding leases on the file. |
1471 | */ |
1472 | return break_lease(inode, flag); |
1473 | } |
1474 | |
1475 | static int handle_truncate(struct path *path) |
1476 | { |
1477 | struct inode *inode = path->dentry->d_inode; |
1478 | int error = get_write_access(inode); |
1479 | if (error) |
1480 | return error; |
1481 | /* |
1482 | * Refuse to truncate files with mandatory locks held on them. |
1483 | */ |
1484 | error = locks_verify_locked(inode); |
1485 | if (!error) |
1486 | error = security_path_truncate(path, 0, |
1487 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN); |
1488 | if (!error) { |
1489 | error = do_truncate(path->dentry, 0, |
1490 | ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, |
1491 | NULL); |
1492 | } |
1493 | put_write_access(inode); |
1494 | return error; |
1495 | } |
1496 | |
1497 | /* |
1498 | * Be careful about ever adding any more callers of this |
1499 | * function. Its flags must be in the namei format, not |
1500 | * what get passed to sys_open(). |
1501 | */ |
1502 | static int __open_namei_create(struct nameidata *nd, struct path *path, |
1503 | int open_flag, int mode) |
1504 | { |
1505 | int error; |
1506 | struct dentry *dir = nd->path.dentry; |
1507 | |
1508 | if (!IS_POSIXACL(dir->d_inode)) |
1509 | mode &= ~current_umask(); |
1510 | error = security_path_mknod(&nd->path, path->dentry, mode, 0); |
1511 | if (error) |
1512 | goto out_unlock; |
1513 | error = vfs_create(dir->d_inode, path->dentry, mode, nd); |
1514 | out_unlock: |
1515 | mutex_unlock(&dir->d_inode->i_mutex); |
1516 | dput(nd->path.dentry); |
1517 | nd->path.dentry = path->dentry; |
1518 | if (error) |
1519 | return error; |
1520 | /* Don't check for write permission, don't truncate */ |
1521 | return may_open(&nd->path, 0, open_flag & ~O_TRUNC); |
1522 | } |
1523 | |
1524 | /* |
1525 | * Note that while the flag value (low two bits) for sys_open means: |
1526 | * 00 - read-only |
1527 | * 01 - write-only |
1528 | * 10 - read-write |
1529 | * 11 - special |
1530 | * it is changed into |
1531 | * 00 - no permissions needed |
1532 | * 01 - read-permission |
1533 | * 10 - write-permission |
1534 | * 11 - read-write |
1535 | * for the internal routines (ie open_namei()/follow_link() etc) |
1536 | * This is more logical, and also allows the 00 "no perm needed" |
1537 | * to be used for symlinks (where the permissions are checked |
1538 | * later). |
1539 | * |
1540 | */ |
1541 | static inline int open_to_namei_flags(int flag) |
1542 | { |
1543 | if ((flag+1) & O_ACCMODE) |
1544 | flag++; |
1545 | return flag; |
1546 | } |
1547 | |
1548 | static int open_will_truncate(int flag, struct inode *inode) |
1549 | { |
1550 | /* |
1551 | * We'll never write to the fs underlying |
1552 | * a device file. |
1553 | */ |
1554 | if (special_file(inode->i_mode)) |
1555 | return 0; |
1556 | return (flag & O_TRUNC); |
1557 | } |
1558 | |
1559 | static struct file *finish_open(struct nameidata *nd, |
1560 | int open_flag, int acc_mode) |
1561 | { |
1562 | struct file *filp; |
1563 | int will_truncate; |
1564 | int error; |
1565 | |
1566 | will_truncate = open_will_truncate(open_flag, nd->path.dentry->d_inode); |
1567 | if (will_truncate) { |
1568 | error = mnt_want_write(nd->path.mnt); |
1569 | if (error) |
1570 | goto exit; |
1571 | } |
1572 | error = may_open(&nd->path, acc_mode, open_flag); |
1573 | if (error) { |
1574 | if (will_truncate) |
1575 | mnt_drop_write(nd->path.mnt); |
1576 | goto exit; |
1577 | } |
1578 | filp = nameidata_to_filp(nd); |
1579 | if (!IS_ERR(filp)) { |
1580 | error = ima_file_check(filp, acc_mode); |
1581 | if (error) { |
1582 | fput(filp); |
1583 | filp = ERR_PTR(error); |
1584 | } |
1585 | } |
1586 | if (!IS_ERR(filp)) { |
1587 | if (will_truncate) { |
1588 | error = handle_truncate(&nd->path); |
1589 | if (error) { |
1590 | fput(filp); |
1591 | filp = ERR_PTR(error); |
1592 | } |
1593 | } |
1594 | } |
1595 | /* |
1596 | * It is now safe to drop the mnt write |
1597 | * because the filp has had a write taken |
1598 | * on its behalf. |
1599 | */ |
1600 | if (will_truncate) |
1601 | mnt_drop_write(nd->path.mnt); |
1602 | return filp; |
1603 | |
1604 | exit: |
1605 | if (!IS_ERR(nd->intent.open.file)) |
1606 | release_open_intent(nd); |
1607 | path_put(&nd->path); |
1608 | return ERR_PTR(error); |
1609 | } |
1610 | |
1611 | static struct file *do_last(struct nameidata *nd, struct path *path, |
1612 | int open_flag, int acc_mode, |
1613 | int mode, const char *pathname) |
1614 | { |
1615 | struct dentry *dir = nd->path.dentry; |
1616 | struct file *filp; |
1617 | int error = -EISDIR; |
1618 | |
1619 | switch (nd->last_type) { |
1620 | case LAST_DOTDOT: |
1621 | follow_dotdot(nd); |
1622 | dir = nd->path.dentry; |
1623 | if (nd->path.mnt->mnt_sb->s_type->fs_flags & FS_REVAL_DOT) { |
1624 | if (!dir->d_op->d_revalidate(dir, nd)) { |
1625 | error = -ESTALE; |
1626 | goto exit; |
1627 | } |
1628 | } |
1629 | /* fallthrough */ |
1630 | case LAST_DOT: |
1631 | case LAST_ROOT: |
1632 | if (open_flag & O_CREAT) |
1633 | goto exit; |
1634 | /* fallthrough */ |
1635 | case LAST_BIND: |
1636 | audit_inode(pathname, dir); |
1637 | goto ok; |
1638 | } |
1639 | |
1640 | /* trailing slashes? */ |
1641 | if (nd->last.name[nd->last.len]) { |
1642 | if (open_flag & O_CREAT) |
1643 | goto exit; |
1644 | nd->flags |= LOOKUP_DIRECTORY; |
1645 | } |
1646 | |
1647 | /* just plain open? */ |
1648 | if (!(open_flag & O_CREAT)) { |
1649 | error = do_lookup(nd, &nd->last, path); |
1650 | if (error) |
1651 | goto exit; |
1652 | error = -ENOENT; |
1653 | if (!path->dentry->d_inode) |
1654 | goto exit_dput; |
1655 | if (path->dentry->d_inode->i_op->follow_link) |
1656 | return NULL; |
1657 | error = -ENOTDIR; |
1658 | if (nd->flags & LOOKUP_DIRECTORY) { |
1659 | if (!path->dentry->d_inode->i_op->lookup) |
1660 | goto exit_dput; |
1661 | } |
1662 | path_to_nameidata(path, nd); |
1663 | audit_inode(pathname, nd->path.dentry); |
1664 | goto ok; |
1665 | } |
1666 | |
1667 | /* OK, it's O_CREAT */ |
1668 | mutex_lock(&dir->d_inode->i_mutex); |
1669 | |
1670 | path->dentry = lookup_hash(nd); |
1671 | path->mnt = nd->path.mnt; |
1672 | |
1673 | error = PTR_ERR(path->dentry); |
1674 | if (IS_ERR(path->dentry)) { |
1675 | mutex_unlock(&dir->d_inode->i_mutex); |
1676 | goto exit; |
1677 | } |
1678 | |
1679 | if (IS_ERR(nd->intent.open.file)) { |
1680 | error = PTR_ERR(nd->intent.open.file); |
1681 | goto exit_mutex_unlock; |
1682 | } |
1683 | |
1684 | /* Negative dentry, just create the file */ |
1685 | if (!path->dentry->d_inode) { |
1686 | /* |
1687 | * This write is needed to ensure that a |
1688 | * ro->rw transition does not occur between |
1689 | * the time when the file is created and when |
1690 | * a permanent write count is taken through |
1691 | * the 'struct file' in nameidata_to_filp(). |
1692 | */ |
1693 | error = mnt_want_write(nd->path.mnt); |
1694 | if (error) |
1695 | goto exit_mutex_unlock; |
1696 | error = __open_namei_create(nd, path, open_flag, mode); |
1697 | if (error) { |
1698 | mnt_drop_write(nd->path.mnt); |
1699 | goto exit; |
1700 | } |
1701 | filp = nameidata_to_filp(nd); |
1702 | mnt_drop_write(nd->path.mnt); |
1703 | if (!IS_ERR(filp)) { |
1704 | error = ima_file_check(filp, acc_mode); |
1705 | if (error) { |
1706 | fput(filp); |
1707 | filp = ERR_PTR(error); |
1708 | } |
1709 | } |
1710 | return filp; |
1711 | } |
1712 | |
1713 | /* |
1714 | * It already exists. |
1715 | */ |
1716 | mutex_unlock(&dir->d_inode->i_mutex); |
1717 | audit_inode(pathname, path->dentry); |
1718 | |
1719 | error = -EEXIST; |
1720 | if (open_flag & O_EXCL) |
1721 | goto exit_dput; |
1722 | |
1723 | if (__follow_mount(path)) { |
1724 | error = -ELOOP; |
1725 | if (open_flag & O_NOFOLLOW) |
1726 | goto exit_dput; |
1727 | } |
1728 | |
1729 | error = -ENOENT; |
1730 | if (!path->dentry->d_inode) |
1731 | goto exit_dput; |
1732 | |
1733 | if (path->dentry->d_inode->i_op->follow_link) |
1734 | return NULL; |
1735 | |
1736 | path_to_nameidata(path, nd); |
1737 | error = -EISDIR; |
1738 | if (S_ISDIR(path->dentry->d_inode->i_mode)) |
1739 | goto exit; |
1740 | ok: |
1741 | filp = finish_open(nd, open_flag, acc_mode); |
1742 | return filp; |
1743 | |
1744 | exit_mutex_unlock: |
1745 | mutex_unlock(&dir->d_inode->i_mutex); |
1746 | exit_dput: |
1747 | path_put_conditional(path, nd); |
1748 | exit: |
1749 | if (!IS_ERR(nd->intent.open.file)) |
1750 | release_open_intent(nd); |
1751 | path_put(&nd->path); |
1752 | return ERR_PTR(error); |
1753 | } |
1754 | |
1755 | /* |
1756 | * Note that the low bits of the passed in "open_flag" |
1757 | * are not the same as in the local variable "flag". See |
1758 | * open_to_namei_flags() for more details. |
1759 | */ |
1760 | struct file *do_filp_open(int dfd, const char *pathname, |
1761 | int open_flag, int mode, int acc_mode) |
1762 | { |
1763 | struct file *filp; |
1764 | struct nameidata nd; |
1765 | int error; |
1766 | struct path path; |
1767 | int count = 0; |
1768 | int flag = open_to_namei_flags(open_flag); |
1769 | int force_reval = 0; |
1770 | |
1771 | if (!(open_flag & O_CREAT)) |
1772 | mode = 0; |
1773 | |
1774 | /* |
1775 | * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only |
1776 | * check for O_DSYNC if the need any syncing at all we enforce it's |
1777 | * always set instead of having to deal with possibly weird behaviour |
1778 | * for malicious applications setting only __O_SYNC. |
1779 | */ |
1780 | if (open_flag & __O_SYNC) |
1781 | open_flag |= O_DSYNC; |
1782 | |
1783 | if (!acc_mode) |
1784 | acc_mode = MAY_OPEN | ACC_MODE(open_flag); |
1785 | |
1786 | /* O_TRUNC implies we need access checks for write permissions */ |
1787 | if (open_flag & O_TRUNC) |
1788 | acc_mode |= MAY_WRITE; |
1789 | |
1790 | /* Allow the LSM permission hook to distinguish append |
1791 | access from general write access. */ |
1792 | if (open_flag & O_APPEND) |
1793 | acc_mode |= MAY_APPEND; |
1794 | |
1795 | /* find the parent */ |
1796 | reval: |
1797 | error = path_init(dfd, pathname, LOOKUP_PARENT, &nd); |
1798 | if (error) |
1799 | return ERR_PTR(error); |
1800 | if (force_reval) |
1801 | nd.flags |= LOOKUP_REVAL; |
1802 | |
1803 | current->total_link_count = 0; |
1804 | error = link_path_walk(pathname, &nd); |
1805 | if (error) { |
1806 | filp = ERR_PTR(error); |
1807 | goto out; |
1808 | } |
1809 | if (unlikely(!audit_dummy_context()) && (open_flag & O_CREAT)) |
1810 | audit_inode(pathname, nd.path.dentry); |
1811 | |
1812 | /* |
1813 | * We have the parent and last component. |
1814 | */ |
1815 | |
1816 | error = -ENFILE; |
1817 | filp = get_empty_filp(); |
1818 | if (filp == NULL) |
1819 | goto exit_parent; |
1820 | nd.intent.open.file = filp; |
1821 | filp->f_flags = open_flag; |
1822 | nd.intent.open.flags = flag; |
1823 | nd.intent.open.create_mode = mode; |
1824 | nd.flags &= ~LOOKUP_PARENT; |
1825 | nd.flags |= LOOKUP_OPEN; |
1826 | if (open_flag & O_CREAT) { |
1827 | nd.flags |= LOOKUP_CREATE; |
1828 | if (open_flag & O_EXCL) |
1829 | nd.flags |= LOOKUP_EXCL; |
1830 | } |
1831 | if (open_flag & O_DIRECTORY) |
1832 | nd.flags |= LOOKUP_DIRECTORY; |
1833 | filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname); |
1834 | while (unlikely(!filp)) { /* trailing symlink */ |
1835 | struct path holder; |
1836 | struct inode *inode = path.dentry->d_inode; |
1837 | void *cookie; |
1838 | error = -ELOOP; |
1839 | /* S_ISDIR part is a temporary automount kludge */ |
1840 | if ((open_flag & O_NOFOLLOW) && !S_ISDIR(inode->i_mode)) |
1841 | goto exit_dput; |
1842 | if (count++ == 32) |
1843 | goto exit_dput; |
1844 | /* |
1845 | * This is subtle. Instead of calling do_follow_link() we do |
1846 | * the thing by hands. The reason is that this way we have zero |
1847 | * link_count and path_walk() (called from ->follow_link) |
1848 | * honoring LOOKUP_PARENT. After that we have the parent and |
1849 | * last component, i.e. we are in the same situation as after |
1850 | * the first path_walk(). Well, almost - if the last component |
1851 | * is normal we get its copy stored in nd->last.name and we will |
1852 | * have to putname() it when we are done. Procfs-like symlinks |
1853 | * just set LAST_BIND. |
1854 | */ |
1855 | nd.flags |= LOOKUP_PARENT; |
1856 | error = security_inode_follow_link(path.dentry, &nd); |
1857 | if (error) |
1858 | goto exit_dput; |
1859 | error = __do_follow_link(&path, &nd, &cookie); |
1860 | if (unlikely(error)) { |
1861 | /* nd.path had been dropped */ |
1862 | if (!IS_ERR(cookie) && inode->i_op->put_link) |
1863 | inode->i_op->put_link(path.dentry, &nd, cookie); |
1864 | path_put(&path); |
1865 | release_open_intent(&nd); |
1866 | filp = ERR_PTR(error); |
1867 | goto out; |
1868 | } |
1869 | holder = path; |
1870 | nd.flags &= ~LOOKUP_PARENT; |
1871 | filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname); |
1872 | if (inode->i_op->put_link) |
1873 | inode->i_op->put_link(holder.dentry, &nd, cookie); |
1874 | path_put(&holder); |
1875 | } |
1876 | out: |
1877 | if (nd.root.mnt) |
1878 | path_put(&nd.root); |
1879 | if (filp == ERR_PTR(-ESTALE) && !force_reval) { |
1880 | force_reval = 1; |
1881 | goto reval; |
1882 | } |
1883 | return filp; |
1884 | |
1885 | exit_dput: |
1886 | path_put_conditional(&path, &nd); |
1887 | if (!IS_ERR(nd.intent.open.file)) |
1888 | release_open_intent(&nd); |
1889 | exit_parent: |
1890 | path_put(&nd.path); |
1891 | filp = ERR_PTR(error); |
1892 | goto out; |
1893 | } |
1894 | |
1895 | /** |
1896 | * filp_open - open file and return file pointer |
1897 | * |
1898 | * @filename: path to open |
1899 | * @flags: open flags as per the open(2) second argument |
1900 | * @mode: mode for the new file if O_CREAT is set, else ignored |
1901 | * |
1902 | * This is the helper to open a file from kernelspace if you really |
1903 | * have to. But in generally you should not do this, so please move |
1904 | * along, nothing to see here.. |
1905 | */ |
1906 | struct file *filp_open(const char *filename, int flags, int mode) |
1907 | { |
1908 | return do_filp_open(AT_FDCWD, filename, flags, mode, 0); |
1909 | } |
1910 | EXPORT_SYMBOL(filp_open); |
1911 | |
1912 | /** |
1913 | * lookup_create - lookup a dentry, creating it if it doesn't exist |
1914 | * @nd: nameidata info |
1915 | * @is_dir: directory flag |
1916 | * |
1917 | * Simple function to lookup and return a dentry and create it |
1918 | * if it doesn't exist. Is SMP-safe. |
1919 | * |
1920 | * Returns with nd->path.dentry->d_inode->i_mutex locked. |
1921 | */ |
1922 | struct dentry *lookup_create(struct nameidata *nd, int is_dir) |
1923 | { |
1924 | struct dentry *dentry = ERR_PTR(-EEXIST); |
1925 | |
1926 | mutex_lock_nested(&nd->path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
1927 | /* |
1928 | * Yucky last component or no last component at all? |
1929 | * (foo/., foo/.., /////) |
1930 | */ |
1931 | if (nd->last_type != LAST_NORM) |
1932 | goto fail; |
1933 | nd->flags &= ~LOOKUP_PARENT; |
1934 | nd->flags |= LOOKUP_CREATE | LOOKUP_EXCL; |
1935 | nd->intent.open.flags = O_EXCL; |
1936 | |
1937 | /* |
1938 | * Do the final lookup. |
1939 | */ |
1940 | dentry = lookup_hash(nd); |
1941 | if (IS_ERR(dentry)) |
1942 | goto fail; |
1943 | |
1944 | if (dentry->d_inode) |
1945 | goto eexist; |
1946 | /* |
1947 | * Special case - lookup gave negative, but... we had foo/bar/ |
1948 | * From the vfs_mknod() POV we just have a negative dentry - |
1949 | * all is fine. Let's be bastards - you had / on the end, you've |
1950 | * been asking for (non-existent) directory. -ENOENT for you. |
1951 | */ |
1952 | if (unlikely(!is_dir && nd->last.name[nd->last.len])) { |
1953 | dput(dentry); |
1954 | dentry = ERR_PTR(-ENOENT); |
1955 | } |
1956 | return dentry; |
1957 | eexist: |
1958 | dput(dentry); |
1959 | dentry = ERR_PTR(-EEXIST); |
1960 | fail: |
1961 | return dentry; |
1962 | } |
1963 | EXPORT_SYMBOL_GPL(lookup_create); |
1964 | |
1965 | int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) |
1966 | { |
1967 | int error = may_create(dir, dentry); |
1968 | |
1969 | if (error) |
1970 | return error; |
1971 | |
1972 | if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) |
1973 | return -EPERM; |
1974 | |
1975 | if (!dir->i_op->mknod) |
1976 | return -EPERM; |
1977 | |
1978 | error = devcgroup_inode_mknod(mode, dev); |
1979 | if (error) |
1980 | return error; |
1981 | |
1982 | error = security_inode_mknod(dir, dentry, mode, dev); |
1983 | if (error) |
1984 | return error; |
1985 | |
1986 | error = dir->i_op->mknod(dir, dentry, mode, dev); |
1987 | if (!error) |
1988 | fsnotify_create(dir, dentry); |
1989 | return error; |
1990 | } |
1991 | |
1992 | static int may_mknod(mode_t mode) |
1993 | { |
1994 | switch (mode & S_IFMT) { |
1995 | case S_IFREG: |
1996 | case S_IFCHR: |
1997 | case S_IFBLK: |
1998 | case S_IFIFO: |
1999 | case S_IFSOCK: |
2000 | case 0: /* zero mode translates to S_IFREG */ |
2001 | return 0; |
2002 | case S_IFDIR: |
2003 | return -EPERM; |
2004 | default: |
2005 | return -EINVAL; |
2006 | } |
2007 | } |
2008 | |
2009 | SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, int, mode, |
2010 | unsigned, dev) |
2011 | { |
2012 | int error; |
2013 | char *tmp; |
2014 | struct dentry *dentry; |
2015 | struct nameidata nd; |
2016 | |
2017 | if (S_ISDIR(mode)) |
2018 | return -EPERM; |
2019 | |
2020 | error = user_path_parent(dfd, filename, &nd, &tmp); |
2021 | if (error) |
2022 | return error; |
2023 | |
2024 | dentry = lookup_create(&nd, 0); |
2025 | if (IS_ERR(dentry)) { |
2026 | error = PTR_ERR(dentry); |
2027 | goto out_unlock; |
2028 | } |
2029 | if (!IS_POSIXACL(nd.path.dentry->d_inode)) |
2030 | mode &= ~current_umask(); |
2031 | error = may_mknod(mode); |
2032 | if (error) |
2033 | goto out_dput; |
2034 | error = mnt_want_write(nd.path.mnt); |
2035 | if (error) |
2036 | goto out_dput; |
2037 | error = security_path_mknod(&nd.path, dentry, mode, dev); |
2038 | if (error) |
2039 | goto out_drop_write; |
2040 | switch (mode & S_IFMT) { |
2041 | case 0: case S_IFREG: |
2042 | error = vfs_create(nd.path.dentry->d_inode,dentry,mode,&nd); |
2043 | break; |
2044 | case S_IFCHR: case S_IFBLK: |
2045 | error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode, |
2046 | new_decode_dev(dev)); |
2047 | break; |
2048 | case S_IFIFO: case S_IFSOCK: |
2049 | error = vfs_mknod(nd.path.dentry->d_inode,dentry,mode,0); |
2050 | break; |
2051 | } |
2052 | out_drop_write: |
2053 | mnt_drop_write(nd.path.mnt); |
2054 | out_dput: |
2055 | dput(dentry); |
2056 | out_unlock: |
2057 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
2058 | path_put(&nd.path); |
2059 | putname(tmp); |
2060 | |
2061 | return error; |
2062 | } |
2063 | |
2064 | SYSCALL_DEFINE3(mknod, const char __user *, filename, int, mode, unsigned, dev) |
2065 | { |
2066 | return sys_mknodat(AT_FDCWD, filename, mode, dev); |
2067 | } |
2068 | |
2069 | int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
2070 | { |
2071 | int error = may_create(dir, dentry); |
2072 | |
2073 | if (error) |
2074 | return error; |
2075 | |
2076 | if (!dir->i_op->mkdir) |
2077 | return -EPERM; |
2078 | |
2079 | mode &= (S_IRWXUGO|S_ISVTX); |
2080 | error = security_inode_mkdir(dir, dentry, mode); |
2081 | if (error) |
2082 | return error; |
2083 | |
2084 | error = dir->i_op->mkdir(dir, dentry, mode); |
2085 | if (!error) |
2086 | fsnotify_mkdir(dir, dentry); |
2087 | return error; |
2088 | } |
2089 | |
2090 | SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, int, mode) |
2091 | { |
2092 | int error = 0; |
2093 | char * tmp; |
2094 | struct dentry *dentry; |
2095 | struct nameidata nd; |
2096 | |
2097 | error = user_path_parent(dfd, pathname, &nd, &tmp); |
2098 | if (error) |
2099 | goto out_err; |
2100 | |
2101 | dentry = lookup_create(&nd, 1); |
2102 | error = PTR_ERR(dentry); |
2103 | if (IS_ERR(dentry)) |
2104 | goto out_unlock; |
2105 | |
2106 | if (!IS_POSIXACL(nd.path.dentry->d_inode)) |
2107 | mode &= ~current_umask(); |
2108 | error = mnt_want_write(nd.path.mnt); |
2109 | if (error) |
2110 | goto out_dput; |
2111 | error = security_path_mkdir(&nd.path, dentry, mode); |
2112 | if (error) |
2113 | goto out_drop_write; |
2114 | error = vfs_mkdir(nd.path.dentry->d_inode, dentry, mode); |
2115 | out_drop_write: |
2116 | mnt_drop_write(nd.path.mnt); |
2117 | out_dput: |
2118 | dput(dentry); |
2119 | out_unlock: |
2120 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
2121 | path_put(&nd.path); |
2122 | putname(tmp); |
2123 | out_err: |
2124 | return error; |
2125 | } |
2126 | |
2127 | SYSCALL_DEFINE2(mkdir, const char __user *, pathname, int, mode) |
2128 | { |
2129 | return sys_mkdirat(AT_FDCWD, pathname, mode); |
2130 | } |
2131 | |
2132 | /* |
2133 | * We try to drop the dentry early: we should have |
2134 | * a usage count of 2 if we're the only user of this |
2135 | * dentry, and if that is true (possibly after pruning |
2136 | * the dcache), then we drop the dentry now. |
2137 | * |
2138 | * A low-level filesystem can, if it choses, legally |
2139 | * do a |
2140 | * |
2141 | * if (!d_unhashed(dentry)) |
2142 | * return -EBUSY; |
2143 | * |
2144 | * if it cannot handle the case of removing a directory |
2145 | * that is still in use by something else.. |
2146 | */ |
2147 | void dentry_unhash(struct dentry *dentry) |
2148 | { |
2149 | dget(dentry); |
2150 | shrink_dcache_parent(dentry); |
2151 | spin_lock(&dcache_lock); |
2152 | spin_lock(&dentry->d_lock); |
2153 | if (atomic_read(&dentry->d_count) == 2) |
2154 | __d_drop(dentry); |
2155 | spin_unlock(&dentry->d_lock); |
2156 | spin_unlock(&dcache_lock); |
2157 | } |
2158 | |
2159 | int vfs_rmdir(struct inode *dir, struct dentry *dentry) |
2160 | { |
2161 | int error = may_delete(dir, dentry, 1); |
2162 | |
2163 | if (error) |
2164 | return error; |
2165 | |
2166 | if (!dir->i_op->rmdir) |
2167 | return -EPERM; |
2168 | |
2169 | mutex_lock(&dentry->d_inode->i_mutex); |
2170 | dentry_unhash(dentry); |
2171 | if (d_mountpoint(dentry)) |
2172 | error = -EBUSY; |
2173 | else { |
2174 | error = security_inode_rmdir(dir, dentry); |
2175 | if (!error) { |
2176 | error = dir->i_op->rmdir(dir, dentry); |
2177 | if (!error) |
2178 | dentry->d_inode->i_flags |= S_DEAD; |
2179 | } |
2180 | } |
2181 | mutex_unlock(&dentry->d_inode->i_mutex); |
2182 | if (!error) { |
2183 | d_delete(dentry); |
2184 | } |
2185 | dput(dentry); |
2186 | |
2187 | return error; |
2188 | } |
2189 | |
2190 | static long do_rmdir(int dfd, const char __user *pathname) |
2191 | { |
2192 | int error = 0; |
2193 | char * name; |
2194 | struct dentry *dentry; |
2195 | struct nameidata nd; |
2196 | |
2197 | error = user_path_parent(dfd, pathname, &nd, &name); |
2198 | if (error) |
2199 | return error; |
2200 | |
2201 | switch(nd.last_type) { |
2202 | case LAST_DOTDOT: |
2203 | error = -ENOTEMPTY; |
2204 | goto exit1; |
2205 | case LAST_DOT: |
2206 | error = -EINVAL; |
2207 | goto exit1; |
2208 | case LAST_ROOT: |
2209 | error = -EBUSY; |
2210 | goto exit1; |
2211 | } |
2212 | |
2213 | nd.flags &= ~LOOKUP_PARENT; |
2214 | |
2215 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
2216 | dentry = lookup_hash(&nd); |
2217 | error = PTR_ERR(dentry); |
2218 | if (IS_ERR(dentry)) |
2219 | goto exit2; |
2220 | error = mnt_want_write(nd.path.mnt); |
2221 | if (error) |
2222 | goto exit3; |
2223 | error = security_path_rmdir(&nd.path, dentry); |
2224 | if (error) |
2225 | goto exit4; |
2226 | error = vfs_rmdir(nd.path.dentry->d_inode, dentry); |
2227 | exit4: |
2228 | mnt_drop_write(nd.path.mnt); |
2229 | exit3: |
2230 | dput(dentry); |
2231 | exit2: |
2232 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
2233 | exit1: |
2234 | path_put(&nd.path); |
2235 | putname(name); |
2236 | return error; |
2237 | } |
2238 | |
2239 | SYSCALL_DEFINE1(rmdir, const char __user *, pathname) |
2240 | { |
2241 | return do_rmdir(AT_FDCWD, pathname); |
2242 | } |
2243 | |
2244 | int vfs_unlink(struct inode *dir, struct dentry *dentry) |
2245 | { |
2246 | int error = may_delete(dir, dentry, 0); |
2247 | |
2248 | if (error) |
2249 | return error; |
2250 | |
2251 | if (!dir->i_op->unlink) |
2252 | return -EPERM; |
2253 | |
2254 | mutex_lock(&dentry->d_inode->i_mutex); |
2255 | if (d_mountpoint(dentry)) |
2256 | error = -EBUSY; |
2257 | else { |
2258 | error = security_inode_unlink(dir, dentry); |
2259 | if (!error) { |
2260 | error = dir->i_op->unlink(dir, dentry); |
2261 | if (!error) |
2262 | dentry->d_inode->i_flags |= S_DEAD; |
2263 | } |
2264 | } |
2265 | mutex_unlock(&dentry->d_inode->i_mutex); |
2266 | |
2267 | /* We don't d_delete() NFS sillyrenamed files--they still exist. */ |
2268 | if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { |
2269 | fsnotify_link_count(dentry->d_inode); |
2270 | d_delete(dentry); |
2271 | } |
2272 | |
2273 | return error; |
2274 | } |
2275 | |
2276 | /* |
2277 | * Make sure that the actual truncation of the file will occur outside its |
2278 | * directory's i_mutex. Truncate can take a long time if there is a lot of |
2279 | * writeout happening, and we don't want to prevent access to the directory |
2280 | * while waiting on the I/O. |
2281 | */ |
2282 | static long do_unlinkat(int dfd, const char __user *pathname) |
2283 | { |
2284 | int error; |
2285 | char *name; |
2286 | struct dentry *dentry; |
2287 | struct nameidata nd; |
2288 | struct inode *inode = NULL; |
2289 | |
2290 | error = user_path_parent(dfd, pathname, &nd, &name); |
2291 | if (error) |
2292 | return error; |
2293 | |
2294 | error = -EISDIR; |
2295 | if (nd.last_type != LAST_NORM) |
2296 | goto exit1; |
2297 | |
2298 | nd.flags &= ~LOOKUP_PARENT; |
2299 | |
2300 | mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); |
2301 | dentry = lookup_hash(&nd); |
2302 | error = PTR_ERR(dentry); |
2303 | if (!IS_ERR(dentry)) { |
2304 | /* Why not before? Because we want correct error value */ |
2305 | if (nd.last.name[nd.last.len]) |
2306 | goto slashes; |
2307 | inode = dentry->d_inode; |
2308 | if (inode) |
2309 | atomic_inc(&inode->i_count); |
2310 | error = mnt_want_write(nd.path.mnt); |
2311 | if (error) |
2312 | goto exit2; |
2313 | error = security_path_unlink(&nd.path, dentry); |
2314 | if (error) |
2315 | goto exit3; |
2316 | error = vfs_unlink(nd.path.dentry->d_inode, dentry); |
2317 | exit3: |
2318 | mnt_drop_write(nd.path.mnt); |
2319 | exit2: |
2320 | dput(dentry); |
2321 | } |
2322 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
2323 | if (inode) |
2324 | iput(inode); /* truncate the inode here */ |
2325 | exit1: |
2326 | path_put(&nd.path); |
2327 | putname(name); |
2328 | return error; |
2329 | |
2330 | slashes: |
2331 | error = !dentry->d_inode ? -ENOENT : |
2332 | S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR; |
2333 | goto exit2; |
2334 | } |
2335 | |
2336 | SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) |
2337 | { |
2338 | if ((flag & ~AT_REMOVEDIR) != 0) |
2339 | return -EINVAL; |
2340 | |
2341 | if (flag & AT_REMOVEDIR) |
2342 | return do_rmdir(dfd, pathname); |
2343 | |
2344 | return do_unlinkat(dfd, pathname); |
2345 | } |
2346 | |
2347 | SYSCALL_DEFINE1(unlink, const char __user *, pathname) |
2348 | { |
2349 | return do_unlinkat(AT_FDCWD, pathname); |
2350 | } |
2351 | |
2352 | int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) |
2353 | { |
2354 | int error = may_create(dir, dentry); |
2355 | |
2356 | if (error) |
2357 | return error; |
2358 | |
2359 | if (!dir->i_op->symlink) |
2360 | return -EPERM; |
2361 | |
2362 | error = security_inode_symlink(dir, dentry, oldname); |
2363 | if (error) |
2364 | return error; |
2365 | |
2366 | error = dir->i_op->symlink(dir, dentry, oldname); |
2367 | if (!error) |
2368 | fsnotify_create(dir, dentry); |
2369 | return error; |
2370 | } |
2371 | |
2372 | SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, |
2373 | int, newdfd, const char __user *, newname) |
2374 | { |
2375 | int error; |
2376 | char *from; |
2377 | char *to; |
2378 | struct dentry *dentry; |
2379 | struct nameidata nd; |
2380 | |
2381 | from = getname(oldname); |
2382 | if (IS_ERR(from)) |
2383 | return PTR_ERR(from); |
2384 | |
2385 | error = user_path_parent(newdfd, newname, &nd, &to); |
2386 | if (error) |
2387 | goto out_putname; |
2388 | |
2389 | dentry = lookup_create(&nd, 0); |
2390 | error = PTR_ERR(dentry); |
2391 | if (IS_ERR(dentry)) |
2392 | goto out_unlock; |
2393 | |
2394 | error = mnt_want_write(nd.path.mnt); |
2395 | if (error) |
2396 | goto out_dput; |
2397 | error = security_path_symlink(&nd.path, dentry, from); |
2398 | if (error) |
2399 | goto out_drop_write; |
2400 | error = vfs_symlink(nd.path.dentry->d_inode, dentry, from); |
2401 | out_drop_write: |
2402 | mnt_drop_write(nd.path.mnt); |
2403 | out_dput: |
2404 | dput(dentry); |
2405 | out_unlock: |
2406 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
2407 | path_put(&nd.path); |
2408 | putname(to); |
2409 | out_putname: |
2410 | putname(from); |
2411 | return error; |
2412 | } |
2413 | |
2414 | SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) |
2415 | { |
2416 | return sys_symlinkat(oldname, AT_FDCWD, newname); |
2417 | } |
2418 | |
2419 | int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry) |
2420 | { |
2421 | struct inode *inode = old_dentry->d_inode; |
2422 | int error; |
2423 | |
2424 | if (!inode) |
2425 | return -ENOENT; |
2426 | |
2427 | error = may_create(dir, new_dentry); |
2428 | if (error) |
2429 | return error; |
2430 | |
2431 | if (dir->i_sb != inode->i_sb) |
2432 | return -EXDEV; |
2433 | |
2434 | /* |
2435 | * A link to an append-only or immutable file cannot be created. |
2436 | */ |
2437 | if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) |
2438 | return -EPERM; |
2439 | if (!dir->i_op->link) |
2440 | return -EPERM; |
2441 | if (S_ISDIR(inode->i_mode)) |
2442 | return -EPERM; |
2443 | |
2444 | error = security_inode_link(old_dentry, dir, new_dentry); |
2445 | if (error) |
2446 | return error; |
2447 | |
2448 | mutex_lock(&inode->i_mutex); |
2449 | error = dir->i_op->link(old_dentry, dir, new_dentry); |
2450 | mutex_unlock(&inode->i_mutex); |
2451 | if (!error) |
2452 | fsnotify_link(dir, inode, new_dentry); |
2453 | return error; |
2454 | } |
2455 | |
2456 | /* |
2457 | * Hardlinks are often used in delicate situations. We avoid |
2458 | * security-related surprises by not following symlinks on the |
2459 | * newname. --KAB |
2460 | * |
2461 | * We don't follow them on the oldname either to be compatible |
2462 | * with linux 2.0, and to avoid hard-linking to directories |
2463 | * and other special files. --ADM |
2464 | */ |
2465 | SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, |
2466 | int, newdfd, const char __user *, newname, int, flags) |
2467 | { |
2468 | struct dentry *new_dentry; |
2469 | struct nameidata nd; |
2470 | struct path old_path; |
2471 | int error; |
2472 | char *to; |
2473 | |
2474 | if ((flags & ~AT_SYMLINK_FOLLOW) != 0) |
2475 | return -EINVAL; |
2476 | |
2477 | error = user_path_at(olddfd, oldname, |
2478 | flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0, |
2479 | &old_path); |
2480 | if (error) |
2481 | return error; |
2482 | |
2483 | error = user_path_parent(newdfd, newname, &nd, &to); |
2484 | if (error) |
2485 | goto out; |
2486 | error = -EXDEV; |
2487 | if (old_path.mnt != nd.path.mnt) |
2488 | goto out_release; |
2489 | new_dentry = lookup_create(&nd, 0); |
2490 | error = PTR_ERR(new_dentry); |
2491 | if (IS_ERR(new_dentry)) |
2492 | goto out_unlock; |
2493 | error = mnt_want_write(nd.path.mnt); |
2494 | if (error) |
2495 | goto out_dput; |
2496 | error = security_path_link(old_path.dentry, &nd.path, new_dentry); |
2497 | if (error) |
2498 | goto out_drop_write; |
2499 | error = vfs_link(old_path.dentry, nd.path.dentry->d_inode, new_dentry); |
2500 | out_drop_write: |
2501 | mnt_drop_write(nd.path.mnt); |
2502 | out_dput: |
2503 | dput(new_dentry); |
2504 | out_unlock: |
2505 | mutex_unlock(&nd.path.dentry->d_inode->i_mutex); |
2506 | out_release: |
2507 | path_put(&nd.path); |
2508 | putname(to); |
2509 | out: |
2510 | path_put(&old_path); |
2511 | |
2512 | return error; |
2513 | } |
2514 | |
2515 | SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) |
2516 | { |
2517 | return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); |
2518 | } |
2519 | |
2520 | /* |
2521 | * The worst of all namespace operations - renaming directory. "Perverted" |
2522 | * doesn't even start to describe it. Somebody in UCB had a heck of a trip... |
2523 | * Problems: |
2524 | * a) we can get into loop creation. Check is done in is_subdir(). |
2525 | * b) race potential - two innocent renames can create a loop together. |
2526 | * That's where 4.4 screws up. Current fix: serialization on |
2527 | * sb->s_vfs_rename_mutex. We might be more accurate, but that's another |
2528 | * story. |
2529 | * c) we have to lock _three_ objects - parents and victim (if it exists). |
2530 | * And that - after we got ->i_mutex on parents (until then we don't know |
2531 | * whether the target exists). Solution: try to be smart with locking |
2532 | * order for inodes. We rely on the fact that tree topology may change |
2533 | * only under ->s_vfs_rename_mutex _and_ that parent of the object we |
2534 | * move will be locked. Thus we can rank directories by the tree |
2535 | * (ancestors first) and rank all non-directories after them. |
2536 | * That works since everybody except rename does "lock parent, lookup, |
2537 | * lock child" and rename is under ->s_vfs_rename_mutex. |
2538 | * HOWEVER, it relies on the assumption that any object with ->lookup() |
2539 | * has no more than 1 dentry. If "hybrid" objects will ever appear, |
2540 | * we'd better make sure that there's no link(2) for them. |
2541 | * d) some filesystems don't support opened-but-unlinked directories, |
2542 | * either because of layout or because they are not ready to deal with |
2543 | * all cases correctly. The latter will be fixed (taking this sort of |
2544 | * stuff into VFS), but the former is not going away. Solution: the same |
2545 | * trick as in rmdir(). |
2546 | * e) conversion from fhandle to dentry may come in the wrong moment - when |
2547 | * we are removing the target. Solution: we will have to grab ->i_mutex |
2548 | * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on |
2549 | * ->i_mutex on parents, which works but leads to some truly excessive |
2550 | * locking]. |
2551 | */ |
2552 | static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry, |
2553 | struct inode *new_dir, struct dentry *new_dentry) |
2554 | { |
2555 | int error = 0; |
2556 | struct inode *target; |
2557 | |
2558 | /* |
2559 | * If we are going to change the parent - check write permissions, |
2560 | * we'll need to flip '..'. |
2561 | */ |
2562 | if (new_dir != old_dir) { |
2563 | error = inode_permission(old_dentry->d_inode, MAY_WRITE); |
2564 | if (error) |
2565 | return error; |
2566 | } |
2567 | |
2568 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); |
2569 | if (error) |
2570 | return error; |
2571 | |
2572 | target = new_dentry->d_inode; |
2573 | if (target) { |
2574 | mutex_lock(&target->i_mutex); |
2575 | dentry_unhash(new_dentry); |
2576 | } |
2577 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
2578 | error = -EBUSY; |
2579 | else |
2580 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
2581 | if (target) { |
2582 | if (!error) |
2583 | target->i_flags |= S_DEAD; |
2584 | mutex_unlock(&target->i_mutex); |
2585 | if (d_unhashed(new_dentry)) |
2586 | d_rehash(new_dentry); |
2587 | dput(new_dentry); |
2588 | } |
2589 | if (!error) |
2590 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
2591 | d_move(old_dentry,new_dentry); |
2592 | return error; |
2593 | } |
2594 | |
2595 | static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry, |
2596 | struct inode *new_dir, struct dentry *new_dentry) |
2597 | { |
2598 | struct inode *target; |
2599 | int error; |
2600 | |
2601 | error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry); |
2602 | if (error) |
2603 | return error; |
2604 | |
2605 | dget(new_dentry); |
2606 | target = new_dentry->d_inode; |
2607 | if (target) |
2608 | mutex_lock(&target->i_mutex); |
2609 | if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry)) |
2610 | error = -EBUSY; |
2611 | else |
2612 | error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry); |
2613 | if (!error) { |
2614 | if (target) |
2615 | target->i_flags |= S_DEAD; |
2616 | if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) |
2617 | d_move(old_dentry, new_dentry); |
2618 | } |
2619 | if (target) |
2620 | mutex_unlock(&target->i_mutex); |
2621 | dput(new_dentry); |
2622 | return error; |
2623 | } |
2624 | |
2625 | int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, |
2626 | struct inode *new_dir, struct dentry *new_dentry) |
2627 | { |
2628 | int error; |
2629 | int is_dir = S_ISDIR(old_dentry->d_inode->i_mode); |
2630 | const char *old_name; |
2631 | |
2632 | if (old_dentry->d_inode == new_dentry->d_inode) |
2633 | return 0; |
2634 | |
2635 | error = may_delete(old_dir, old_dentry, is_dir); |
2636 | if (error) |
2637 | return error; |
2638 | |
2639 | if (!new_dentry->d_inode) |
2640 | error = may_create(new_dir, new_dentry); |
2641 | else |
2642 | error = may_delete(new_dir, new_dentry, is_dir); |
2643 | if (error) |
2644 | return error; |
2645 | |
2646 | if (!old_dir->i_op->rename) |
2647 | return -EPERM; |
2648 | |
2649 | old_name = fsnotify_oldname_init(old_dentry->d_name.name); |
2650 | |
2651 | if (is_dir) |
2652 | error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry); |
2653 | else |
2654 | error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry); |
2655 | if (!error) |
2656 | fsnotify_move(old_dir, new_dir, old_name, is_dir, |
2657 | new_dentry->d_inode, old_dentry); |
2658 | fsnotify_oldname_free(old_name); |
2659 | |
2660 | return error; |
2661 | } |
2662 | |
2663 | SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, |
2664 | int, newdfd, const char __user *, newname) |
2665 | { |
2666 | struct dentry *old_dir, *new_dir; |
2667 | struct dentry *old_dentry, *new_dentry; |
2668 | struct dentry *trap; |
2669 | struct nameidata oldnd, newnd; |
2670 | char *from; |
2671 | char *to; |
2672 | int error; |
2673 | |
2674 | error = user_path_parent(olddfd, oldname, &oldnd, &from); |
2675 | if (error) |
2676 | goto exit; |
2677 | |
2678 | error = user_path_parent(newdfd, newname, &newnd, &to); |
2679 | if (error) |
2680 | goto exit1; |
2681 | |
2682 | error = -EXDEV; |
2683 | if (oldnd.path.mnt != newnd.path.mnt) |
2684 | goto exit2; |
2685 | |
2686 | old_dir = oldnd.path.dentry; |
2687 | error = -EBUSY; |
2688 | if (oldnd.last_type != LAST_NORM) |
2689 | goto exit2; |
2690 | |
2691 | new_dir = newnd.path.dentry; |
2692 | if (newnd.last_type != LAST_NORM) |
2693 | goto exit2; |
2694 | |
2695 | oldnd.flags &= ~LOOKUP_PARENT; |
2696 | newnd.flags &= ~LOOKUP_PARENT; |
2697 | newnd.flags |= LOOKUP_RENAME_TARGET; |
2698 | |
2699 | trap = lock_rename(new_dir, old_dir); |
2700 | |
2701 | old_dentry = lookup_hash(&oldnd); |
2702 | error = PTR_ERR(old_dentry); |
2703 | if (IS_ERR(old_dentry)) |
2704 | goto exit3; |
2705 | /* source must exist */ |
2706 | error = -ENOENT; |
2707 | if (!old_dentry->d_inode) |
2708 | goto exit4; |
2709 | /* unless the source is a directory trailing slashes give -ENOTDIR */ |
2710 | if (!S_ISDIR(old_dentry->d_inode->i_mode)) { |
2711 | error = -ENOTDIR; |
2712 | if (oldnd.last.name[oldnd.last.len]) |
2713 | goto exit4; |
2714 | if (newnd.last.name[newnd.last.len]) |
2715 | goto exit4; |
2716 | } |
2717 | /* source should not be ancestor of target */ |
2718 | error = -EINVAL; |
2719 | if (old_dentry == trap) |
2720 | goto exit4; |
2721 | new_dentry = lookup_hash(&newnd); |
2722 | error = PTR_ERR(new_dentry); |
2723 | if (IS_ERR(new_dentry)) |
2724 | goto exit4; |
2725 | /* target should not be an ancestor of source */ |
2726 | error = -ENOTEMPTY; |
2727 | if (new_dentry == trap) |
2728 | goto exit5; |
2729 | |
2730 | error = mnt_want_write(oldnd.path.mnt); |
2731 | if (error) |
2732 | goto exit5; |
2733 | error = security_path_rename(&oldnd.path, old_dentry, |
2734 | &newnd.path, new_dentry); |
2735 | if (error) |
2736 | goto exit6; |
2737 | error = vfs_rename(old_dir->d_inode, old_dentry, |
2738 | new_dir->d_inode, new_dentry); |
2739 | exit6: |
2740 | mnt_drop_write(oldnd.path.mnt); |
2741 | exit5: |
2742 | dput(new_dentry); |
2743 | exit4: |
2744 | dput(old_dentry); |
2745 | exit3: |
2746 | unlock_rename(new_dir, old_dir); |
2747 | exit2: |
2748 | path_put(&newnd.path); |
2749 | putname(to); |
2750 | exit1: |
2751 | path_put(&oldnd.path); |
2752 | putname(from); |
2753 | exit: |
2754 | return error; |
2755 | } |
2756 | |
2757 | SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) |
2758 | { |
2759 | return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname); |
2760 | } |
2761 | |
2762 | int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link) |
2763 | { |
2764 | int len; |
2765 | |
2766 | len = PTR_ERR(link); |
2767 | if (IS_ERR(link)) |
2768 | goto out; |
2769 | |
2770 | len = strlen(link); |
2771 | if (len > (unsigned) buflen) |
2772 | len = buflen; |
2773 | if (copy_to_user(buffer, link, len)) |
2774 | len = -EFAULT; |
2775 | out: |
2776 | return len; |
2777 | } |
2778 | |
2779 | /* |
2780 | * A helper for ->readlink(). This should be used *ONLY* for symlinks that |
2781 | * have ->follow_link() touching nd only in nd_set_link(). Using (or not |
2782 | * using) it for any given inode is up to filesystem. |
2783 | */ |
2784 | int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) |
2785 | { |
2786 | struct nameidata nd; |
2787 | void *cookie; |
2788 | int res; |
2789 | |
2790 | nd.depth = 0; |
2791 | cookie = dentry->d_inode->i_op->follow_link(dentry, &nd); |
2792 | if (IS_ERR(cookie)) |
2793 | return PTR_ERR(cookie); |
2794 | |
2795 | res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd)); |
2796 | if (dentry->d_inode->i_op->put_link) |
2797 | dentry->d_inode->i_op->put_link(dentry, &nd, cookie); |
2798 | return res; |
2799 | } |
2800 | |
2801 | int vfs_follow_link(struct nameidata *nd, const char *link) |
2802 | { |
2803 | return __vfs_follow_link(nd, link); |
2804 | } |
2805 | |
2806 | /* get the link contents into pagecache */ |
2807 | static char *page_getlink(struct dentry * dentry, struct page **ppage) |
2808 | { |
2809 | char *kaddr; |
2810 | struct page *page; |
2811 | struct address_space *mapping = dentry->d_inode->i_mapping; |
2812 | page = read_mapping_page(mapping, 0, NULL); |
2813 | if (IS_ERR(page)) |
2814 | return (char*)page; |
2815 | *ppage = page; |
2816 | kaddr = kmap(page); |
2817 | nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); |
2818 | return kaddr; |
2819 | } |
2820 | |
2821 | int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) |
2822 | { |
2823 | struct page *page = NULL; |
2824 | char *s = page_getlink(dentry, &page); |
2825 | int res = vfs_readlink(dentry,buffer,buflen,s); |
2826 | if (page) { |
2827 | kunmap(page); |
2828 | page_cache_release(page); |
2829 | } |
2830 | return res; |
2831 | } |
2832 | |
2833 | void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd) |
2834 | { |
2835 | struct page *page = NULL; |
2836 | nd_set_link(nd, page_getlink(dentry, &page)); |
2837 | return page; |
2838 | } |
2839 | |
2840 | void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
2841 | { |
2842 | struct page *page = cookie; |
2843 | |
2844 | if (page) { |
2845 | kunmap(page); |
2846 | page_cache_release(page); |
2847 | } |
2848 | } |
2849 | |
2850 | /* |
2851 | * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS |
2852 | */ |
2853 | int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) |
2854 | { |
2855 | struct address_space *mapping = inode->i_mapping; |
2856 | struct page *page; |
2857 | void *fsdata; |
2858 | int err; |
2859 | char *kaddr; |
2860 | unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; |
2861 | if (nofs) |
2862 | flags |= AOP_FLAG_NOFS; |
2863 | |
2864 | retry: |
2865 | err = pagecache_write_begin(NULL, mapping, 0, len-1, |
2866 | flags, &page, &fsdata); |
2867 | if (err) |
2868 | goto fail; |
2869 | |
2870 | kaddr = kmap_atomic(page, KM_USER0); |
2871 | memcpy(kaddr, symname, len-1); |
2872 | kunmap_atomic(kaddr, KM_USER0); |
2873 | |
2874 | err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, |
2875 | page, fsdata); |
2876 | if (err < 0) |
2877 | goto fail; |
2878 | if (err < len-1) |
2879 | goto retry; |
2880 | |
2881 | mark_inode_dirty(inode); |
2882 | return 0; |
2883 | fail: |
2884 | return err; |
2885 | } |
2886 | |
2887 | int page_symlink(struct inode *inode, const char *symname, int len) |
2888 | { |
2889 | return __page_symlink(inode, symname, len, |
2890 | !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); |
2891 | } |
2892 | |
2893 | const struct inode_operations page_symlink_inode_operations = { |
2894 | .readlink = generic_readlink, |
2895 | .follow_link = page_follow_link_light, |
2896 | .put_link = page_put_link, |
2897 | }; |
2898 | |
2899 | EXPORT_SYMBOL(user_path_at); |
2900 | EXPORT_SYMBOL(follow_down); |
2901 | EXPORT_SYMBOL(follow_up); |
2902 | EXPORT_SYMBOL(get_write_access); /* binfmt_aout */ |
2903 | EXPORT_SYMBOL(getname); |
2904 | EXPORT_SYMBOL(lock_rename); |
2905 | EXPORT_SYMBOL(lookup_one_len); |
2906 | EXPORT_SYMBOL(page_follow_link_light); |
2907 | EXPORT_SYMBOL(page_put_link); |
2908 | EXPORT_SYMBOL(page_readlink); |
2909 | EXPORT_SYMBOL(__page_symlink); |
2910 | EXPORT_SYMBOL(page_symlink); |
2911 | EXPORT_SYMBOL(page_symlink_inode_operations); |
2912 | EXPORT_SYMBOL(path_lookup); |
2913 | EXPORT_SYMBOL(kern_path); |
2914 | EXPORT_SYMBOL(vfs_path_lookup); |
2915 | EXPORT_SYMBOL(inode_permission); |
2916 | EXPORT_SYMBOL(file_permission); |
2917 | EXPORT_SYMBOL(unlock_rename); |
2918 | EXPORT_SYMBOL(vfs_create); |
2919 | EXPORT_SYMBOL(vfs_follow_link); |
2920 | EXPORT_SYMBOL(vfs_link); |
2921 | EXPORT_SYMBOL(vfs_mkdir); |
2922 | EXPORT_SYMBOL(vfs_mknod); |
2923 | EXPORT_SYMBOL(generic_permission); |
2924 | EXPORT_SYMBOL(vfs_readlink); |
2925 | EXPORT_SYMBOL(vfs_rename); |
2926 | EXPORT_SYMBOL(vfs_rmdir); |
2927 | EXPORT_SYMBOL(vfs_symlink); |
2928 | EXPORT_SYMBOL(vfs_unlink); |
2929 | EXPORT_SYMBOL(dentry_unhash); |
2930 | EXPORT_SYMBOL(generic_readlink); |
2931 |
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Tags:
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v2.6.34-rc5
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