]>
Commit | Line | Data |
---|---|---|
e9be9d5e MS |
1 | /* |
2 | * | |
3 | * Copyright (C) 2011 Novell Inc. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify it | |
6 | * under the terms of the GNU General Public License version 2 as published by | |
7 | * the Free Software Foundation. | |
8 | */ | |
9 | ||
10 | #include <linux/fs.h> | |
11 | #include <linux/namei.h> | |
12 | #include <linux/xattr.h> | |
e9be9d5e | 13 | #include <linux/mount.h> |
e9be9d5e MS |
14 | #include <linux/parser.h> |
15 | #include <linux/module.h> | |
cc259639 | 16 | #include <linux/statfs.h> |
f45827e8 | 17 | #include <linux/seq_file.h> |
d837a49b | 18 | #include <linux/posix_acl_xattr.h> |
e9be9d5e | 19 | #include "overlayfs.h" |
bbb1e54d | 20 | #include "ovl_entry.h" |
e9be9d5e MS |
21 | |
22 | MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); | |
23 | MODULE_DESCRIPTION("Overlay filesystem"); | |
24 | MODULE_LICENSE("GPL"); | |
25 | ||
e9be9d5e MS |
26 | |
27 | struct ovl_dir_cache; | |
28 | ||
a78d9f0d MS |
29 | #define OVL_MAX_STACK 500 |
30 | ||
e9be9d5e MS |
31 | |
32 | static void ovl_dentry_release(struct dentry *dentry) | |
33 | { | |
34 | struct ovl_entry *oe = dentry->d_fsdata; | |
35 | ||
36 | if (oe) { | |
dd662667 MS |
37 | unsigned int i; |
38 | ||
e9be9d5e | 39 | dput(oe->__upperdentry); |
02b69b28 | 40 | kfree(oe->redirect); |
dd662667 MS |
41 | for (i = 0; i < oe->numlower; i++) |
42 | dput(oe->lowerstack[i].dentry); | |
e9be9d5e MS |
43 | kfree_rcu(oe, rcu); |
44 | } | |
45 | } | |
46 | ||
2d902671 MS |
47 | static struct dentry *ovl_d_real(struct dentry *dentry, |
48 | const struct inode *inode, | |
49 | unsigned int open_flags) | |
d101a125 MS |
50 | { |
51 | struct dentry *real; | |
52 | ||
ca4c8a3a | 53 | if (!d_is_reg(dentry)) { |
d101a125 MS |
54 | if (!inode || inode == d_inode(dentry)) |
55 | return dentry; | |
56 | goto bug; | |
57 | } | |
58 | ||
2d902671 MS |
59 | if (d_is_negative(dentry)) |
60 | return dentry; | |
61 | ||
62 | if (open_flags) { | |
63 | int err = ovl_open_maybe_copy_up(dentry, open_flags); | |
64 | ||
65 | if (err) | |
66 | return ERR_PTR(err); | |
67 | } | |
68 | ||
d101a125 MS |
69 | real = ovl_dentry_upper(dentry); |
70 | if (real && (!inode || inode == d_inode(real))) | |
71 | return real; | |
72 | ||
73 | real = ovl_dentry_lower(dentry); | |
74 | if (!real) | |
75 | goto bug; | |
76 | ||
c4fcfc16 MS |
77 | /* Handle recursion */ |
78 | real = d_real(real, inode, open_flags); | |
79 | ||
d101a125 MS |
80 | if (!inode || inode == d_inode(real)) |
81 | return real; | |
d101a125 | 82 | bug: |
656189d2 | 83 | WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry, |
d101a125 MS |
84 | inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0); |
85 | return dentry; | |
86 | } | |
87 | ||
7c03b5d4 MS |
88 | static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) |
89 | { | |
90 | struct ovl_entry *oe = dentry->d_fsdata; | |
91 | unsigned int i; | |
92 | int ret = 1; | |
93 | ||
94 | for (i = 0; i < oe->numlower; i++) { | |
95 | struct dentry *d = oe->lowerstack[i].dentry; | |
96 | ||
97 | if (d->d_flags & DCACHE_OP_REVALIDATE) { | |
98 | ret = d->d_op->d_revalidate(d, flags); | |
99 | if (ret < 0) | |
100 | return ret; | |
101 | if (!ret) { | |
102 | if (!(flags & LOOKUP_RCU)) | |
103 | d_invalidate(d); | |
104 | return -ESTALE; | |
105 | } | |
106 | } | |
107 | } | |
108 | return 1; | |
109 | } | |
110 | ||
111 | static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) | |
112 | { | |
113 | struct ovl_entry *oe = dentry->d_fsdata; | |
114 | unsigned int i; | |
115 | int ret = 1; | |
116 | ||
117 | for (i = 0; i < oe->numlower; i++) { | |
118 | struct dentry *d = oe->lowerstack[i].dentry; | |
119 | ||
120 | if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) { | |
121 | ret = d->d_op->d_weak_revalidate(d, flags); | |
122 | if (ret <= 0) | |
123 | break; | |
124 | } | |
125 | } | |
126 | return ret; | |
127 | } | |
128 | ||
e9be9d5e MS |
129 | static const struct dentry_operations ovl_dentry_operations = { |
130 | .d_release = ovl_dentry_release, | |
d101a125 | 131 | .d_real = ovl_d_real, |
e9be9d5e MS |
132 | }; |
133 | ||
7c03b5d4 MS |
134 | static const struct dentry_operations ovl_reval_dentry_operations = { |
135 | .d_release = ovl_dentry_release, | |
d101a125 | 136 | .d_real = ovl_d_real, |
7c03b5d4 MS |
137 | .d_revalidate = ovl_dentry_revalidate, |
138 | .d_weak_revalidate = ovl_dentry_weak_revalidate, | |
139 | }; | |
140 | ||
e9be9d5e MS |
141 | static void ovl_put_super(struct super_block *sb) |
142 | { | |
143 | struct ovl_fs *ufs = sb->s_fs_info; | |
dd662667 | 144 | unsigned i; |
e9be9d5e MS |
145 | |
146 | dput(ufs->workdir); | |
147 | mntput(ufs->upper_mnt); | |
dd662667 MS |
148 | for (i = 0; i < ufs->numlower; i++) |
149 | mntput(ufs->lower_mnt[i]); | |
5ffdbe8b | 150 | kfree(ufs->lower_mnt); |
e9be9d5e | 151 | |
f45827e8 EZ |
152 | kfree(ufs->config.lowerdir); |
153 | kfree(ufs->config.upperdir); | |
154 | kfree(ufs->config.workdir); | |
3fe6e52f | 155 | put_cred(ufs->creator_cred); |
e9be9d5e MS |
156 | kfree(ufs); |
157 | } | |
158 | ||
cc259639 AW |
159 | /** |
160 | * ovl_statfs | |
161 | * @sb: The overlayfs super block | |
162 | * @buf: The struct kstatfs to fill in with stats | |
163 | * | |
164 | * Get the filesystem statistics. As writes always target the upper layer | |
4ebc5818 | 165 | * filesystem pass the statfs to the upper filesystem (if it exists) |
cc259639 AW |
166 | */ |
167 | static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) | |
168 | { | |
169 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
170 | struct dentry *root_dentry = dentry->d_sb->s_root; | |
171 | struct path path; | |
172 | int err; | |
173 | ||
4ebc5818 | 174 | ovl_path_real(root_dentry, &path); |
cc259639 AW |
175 | |
176 | err = vfs_statfs(&path, buf); | |
177 | if (!err) { | |
6b2d5fe4 | 178 | buf->f_namelen = ofs->namelen; |
cc259639 AW |
179 | buf->f_type = OVERLAYFS_SUPER_MAGIC; |
180 | } | |
181 | ||
182 | return err; | |
183 | } | |
184 | ||
f45827e8 EZ |
185 | /** |
186 | * ovl_show_options | |
187 | * | |
188 | * Prints the mount options for a given superblock. | |
189 | * Returns zero; does not fail. | |
190 | */ | |
191 | static int ovl_show_options(struct seq_file *m, struct dentry *dentry) | |
192 | { | |
193 | struct super_block *sb = dentry->d_sb; | |
194 | struct ovl_fs *ufs = sb->s_fs_info; | |
195 | ||
a068acf2 | 196 | seq_show_option(m, "lowerdir", ufs->config.lowerdir); |
53a08cb9 | 197 | if (ufs->config.upperdir) { |
a068acf2 KC |
198 | seq_show_option(m, "upperdir", ufs->config.upperdir); |
199 | seq_show_option(m, "workdir", ufs->config.workdir); | |
53a08cb9 | 200 | } |
8d3095f4 MS |
201 | if (ufs->config.default_permissions) |
202 | seq_puts(m, ",default_permissions"); | |
f45827e8 EZ |
203 | return 0; |
204 | } | |
205 | ||
3cdf6fe9 SL |
206 | static int ovl_remount(struct super_block *sb, int *flags, char *data) |
207 | { | |
208 | struct ovl_fs *ufs = sb->s_fs_info; | |
209 | ||
cc6f67bc | 210 | if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt || !ufs->workdir)) |
3cdf6fe9 SL |
211 | return -EROFS; |
212 | ||
213 | return 0; | |
214 | } | |
215 | ||
e9be9d5e MS |
216 | static const struct super_operations ovl_super_operations = { |
217 | .put_super = ovl_put_super, | |
cc259639 | 218 | .statfs = ovl_statfs, |
f45827e8 | 219 | .show_options = ovl_show_options, |
3cdf6fe9 | 220 | .remount_fs = ovl_remount, |
eead4f2d | 221 | .drop_inode = generic_delete_inode, |
e9be9d5e MS |
222 | }; |
223 | ||
224 | enum { | |
225 | OPT_LOWERDIR, | |
226 | OPT_UPPERDIR, | |
227 | OPT_WORKDIR, | |
8d3095f4 | 228 | OPT_DEFAULT_PERMISSIONS, |
a6c60655 MS |
229 | OPT_REDIRECT_DIR_ON, |
230 | OPT_REDIRECT_DIR_OFF, | |
e9be9d5e MS |
231 | OPT_ERR, |
232 | }; | |
233 | ||
234 | static const match_table_t ovl_tokens = { | |
235 | {OPT_LOWERDIR, "lowerdir=%s"}, | |
236 | {OPT_UPPERDIR, "upperdir=%s"}, | |
237 | {OPT_WORKDIR, "workdir=%s"}, | |
8d3095f4 | 238 | {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, |
a6c60655 MS |
239 | {OPT_REDIRECT_DIR_ON, "redirect_dir=on"}, |
240 | {OPT_REDIRECT_DIR_OFF, "redirect_dir=off"}, | |
e9be9d5e MS |
241 | {OPT_ERR, NULL} |
242 | }; | |
243 | ||
91c77947 MS |
244 | static char *ovl_next_opt(char **s) |
245 | { | |
246 | char *sbegin = *s; | |
247 | char *p; | |
248 | ||
249 | if (sbegin == NULL) | |
250 | return NULL; | |
251 | ||
252 | for (p = sbegin; *p; p++) { | |
253 | if (*p == '\\') { | |
254 | p++; | |
255 | if (!*p) | |
256 | break; | |
257 | } else if (*p == ',') { | |
258 | *p = '\0'; | |
259 | *s = p + 1; | |
260 | return sbegin; | |
261 | } | |
262 | } | |
263 | *s = NULL; | |
264 | return sbegin; | |
265 | } | |
266 | ||
e9be9d5e MS |
267 | static int ovl_parse_opt(char *opt, struct ovl_config *config) |
268 | { | |
269 | char *p; | |
270 | ||
91c77947 | 271 | while ((p = ovl_next_opt(&opt)) != NULL) { |
e9be9d5e MS |
272 | int token; |
273 | substring_t args[MAX_OPT_ARGS]; | |
274 | ||
275 | if (!*p) | |
276 | continue; | |
277 | ||
278 | token = match_token(p, ovl_tokens, args); | |
279 | switch (token) { | |
280 | case OPT_UPPERDIR: | |
281 | kfree(config->upperdir); | |
282 | config->upperdir = match_strdup(&args[0]); | |
283 | if (!config->upperdir) | |
284 | return -ENOMEM; | |
285 | break; | |
286 | ||
287 | case OPT_LOWERDIR: | |
288 | kfree(config->lowerdir); | |
289 | config->lowerdir = match_strdup(&args[0]); | |
290 | if (!config->lowerdir) | |
291 | return -ENOMEM; | |
292 | break; | |
293 | ||
294 | case OPT_WORKDIR: | |
295 | kfree(config->workdir); | |
296 | config->workdir = match_strdup(&args[0]); | |
297 | if (!config->workdir) | |
298 | return -ENOMEM; | |
299 | break; | |
300 | ||
8d3095f4 MS |
301 | case OPT_DEFAULT_PERMISSIONS: |
302 | config->default_permissions = true; | |
303 | break; | |
304 | ||
a6c60655 MS |
305 | case OPT_REDIRECT_DIR_ON: |
306 | config->redirect_dir = true; | |
307 | break; | |
308 | ||
309 | case OPT_REDIRECT_DIR_OFF: | |
310 | config->redirect_dir = false; | |
311 | break; | |
312 | ||
e9be9d5e | 313 | default: |
bead55ef | 314 | pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p); |
e9be9d5e MS |
315 | return -EINVAL; |
316 | } | |
317 | } | |
71cbad7e | 318 | |
319 | /* Workdir is useless in non-upper mount */ | |
320 | if (!config->upperdir && config->workdir) { | |
321 | pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n", | |
322 | config->workdir); | |
323 | kfree(config->workdir); | |
324 | config->workdir = NULL; | |
325 | } | |
326 | ||
e9be9d5e MS |
327 | return 0; |
328 | } | |
329 | ||
330 | #define OVL_WORKDIR_NAME "work" | |
331 | ||
332 | static struct dentry *ovl_workdir_create(struct vfsmount *mnt, | |
333 | struct dentry *dentry) | |
334 | { | |
335 | struct inode *dir = dentry->d_inode; | |
336 | struct dentry *work; | |
337 | int err; | |
338 | bool retried = false; | |
339 | ||
340 | err = mnt_want_write(mnt); | |
341 | if (err) | |
342 | return ERR_PTR(err); | |
343 | ||
5955102c | 344 | inode_lock_nested(dir, I_MUTEX_PARENT); |
e9be9d5e MS |
345 | retry: |
346 | work = lookup_one_len(OVL_WORKDIR_NAME, dentry, | |
347 | strlen(OVL_WORKDIR_NAME)); | |
348 | ||
349 | if (!IS_ERR(work)) { | |
350 | struct kstat stat = { | |
351 | .mode = S_IFDIR | 0, | |
352 | }; | |
c11b9fdd MS |
353 | struct iattr attr = { |
354 | .ia_valid = ATTR_MODE, | |
355 | .ia_mode = stat.mode, | |
356 | }; | |
e9be9d5e MS |
357 | |
358 | if (work->d_inode) { | |
359 | err = -EEXIST; | |
360 | if (retried) | |
361 | goto out_dput; | |
362 | ||
363 | retried = true; | |
eea2fb48 | 364 | ovl_workdir_cleanup(dir, mnt, work, 0); |
e9be9d5e MS |
365 | dput(work); |
366 | goto retry; | |
367 | } | |
368 | ||
369 | err = ovl_create_real(dir, work, &stat, NULL, NULL, true); | |
370 | if (err) | |
371 | goto out_dput; | |
c11b9fdd | 372 | |
cb348edb MS |
373 | /* |
374 | * Try to remove POSIX ACL xattrs from workdir. We are good if: | |
375 | * | |
376 | * a) success (there was a POSIX ACL xattr and was removed) | |
377 | * b) -ENODATA (there was no POSIX ACL xattr) | |
378 | * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported) | |
379 | * | |
380 | * There are various other error values that could effectively | |
381 | * mean that the xattr doesn't exist (e.g. -ERANGE is returned | |
382 | * if the xattr name is too long), but the set of filesystems | |
383 | * allowed as upper are limited to "normal" ones, where checking | |
384 | * for the above two errors is sufficient. | |
385 | */ | |
c11b9fdd | 386 | err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT); |
e1ff3dd1 | 387 | if (err && err != -ENODATA && err != -EOPNOTSUPP) |
c11b9fdd MS |
388 | goto out_dput; |
389 | ||
390 | err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_ACCESS); | |
e1ff3dd1 | 391 | if (err && err != -ENODATA && err != -EOPNOTSUPP) |
c11b9fdd MS |
392 | goto out_dput; |
393 | ||
394 | /* Clear any inherited mode bits */ | |
395 | inode_lock(work->d_inode); | |
396 | err = notify_change(work, &attr, NULL); | |
397 | inode_unlock(work->d_inode); | |
398 | if (err) | |
399 | goto out_dput; | |
e9be9d5e MS |
400 | } |
401 | out_unlock: | |
5955102c | 402 | inode_unlock(dir); |
e9be9d5e MS |
403 | mnt_drop_write(mnt); |
404 | ||
405 | return work; | |
406 | ||
407 | out_dput: | |
408 | dput(work); | |
409 | work = ERR_PTR(err); | |
410 | goto out_unlock; | |
411 | } | |
412 | ||
91c77947 MS |
413 | static void ovl_unescape(char *s) |
414 | { | |
415 | char *d = s; | |
416 | ||
417 | for (;; s++, d++) { | |
418 | if (*s == '\\') | |
419 | s++; | |
420 | *d = *s; | |
421 | if (!*s) | |
422 | break; | |
423 | } | |
424 | } | |
425 | ||
ab508822 MS |
426 | static int ovl_mount_dir_noesc(const char *name, struct path *path) |
427 | { | |
a78d9f0d | 428 | int err = -EINVAL; |
ab508822 | 429 | |
a78d9f0d MS |
430 | if (!*name) { |
431 | pr_err("overlayfs: empty lowerdir\n"); | |
432 | goto out; | |
433 | } | |
ab508822 MS |
434 | err = kern_path(name, LOOKUP_FOLLOW, path); |
435 | if (err) { | |
436 | pr_err("overlayfs: failed to resolve '%s': %i\n", name, err); | |
437 | goto out; | |
438 | } | |
439 | err = -EINVAL; | |
7c03b5d4 | 440 | if (ovl_dentry_weird(path->dentry)) { |
ab508822 MS |
441 | pr_err("overlayfs: filesystem on '%s' not supported\n", name); |
442 | goto out_put; | |
443 | } | |
2b8c30e9 | 444 | if (!d_is_dir(path->dentry)) { |
ab508822 MS |
445 | pr_err("overlayfs: '%s' not a directory\n", name); |
446 | goto out_put; | |
447 | } | |
448 | return 0; | |
449 | ||
450 | out_put: | |
451 | path_put(path); | |
452 | out: | |
453 | return err; | |
454 | } | |
455 | ||
456 | static int ovl_mount_dir(const char *name, struct path *path) | |
457 | { | |
458 | int err = -ENOMEM; | |
459 | char *tmp = kstrdup(name, GFP_KERNEL); | |
460 | ||
461 | if (tmp) { | |
462 | ovl_unescape(tmp); | |
463 | err = ovl_mount_dir_noesc(tmp, path); | |
7c03b5d4 MS |
464 | |
465 | if (!err) | |
466 | if (ovl_dentry_remote(path->dentry)) { | |
467 | pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n", | |
468 | tmp); | |
469 | path_put(path); | |
470 | err = -EINVAL; | |
471 | } | |
ab508822 MS |
472 | kfree(tmp); |
473 | } | |
474 | return err; | |
475 | } | |
476 | ||
6b2d5fe4 MS |
477 | static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs, |
478 | const char *name) | |
ab508822 | 479 | { |
ab508822 | 480 | struct kstatfs statfs; |
6b2d5fe4 MS |
481 | int err = vfs_statfs(path, &statfs); |
482 | ||
483 | if (err) | |
484 | pr_err("overlayfs: statfs failed on '%s'\n", name); | |
485 | else | |
486 | ofs->namelen = max(ofs->namelen, statfs.f_namelen); | |
487 | ||
488 | return err; | |
489 | } | |
490 | ||
491 | static int ovl_lower_dir(const char *name, struct path *path, | |
492 | struct ovl_fs *ofs, int *stack_depth, bool *remote) | |
493 | { | |
494 | int err; | |
ab508822 | 495 | |
a78d9f0d | 496 | err = ovl_mount_dir_noesc(name, path); |
ab508822 MS |
497 | if (err) |
498 | goto out; | |
499 | ||
6b2d5fe4 MS |
500 | err = ovl_check_namelen(path, ofs, name); |
501 | if (err) | |
ab508822 | 502 | goto out_put; |
6b2d5fe4 | 503 | |
ab508822 MS |
504 | *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); |
505 | ||
7c03b5d4 MS |
506 | if (ovl_dentry_remote(path->dentry)) |
507 | *remote = true; | |
508 | ||
ab508822 MS |
509 | return 0; |
510 | ||
511 | out_put: | |
512 | path_put(path); | |
513 | out: | |
514 | return err; | |
515 | } | |
516 | ||
e9be9d5e MS |
517 | /* Workdir should not be subdir of upperdir and vice versa */ |
518 | static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir) | |
519 | { | |
520 | bool ok = false; | |
521 | ||
522 | if (workdir != upperdir) { | |
523 | ok = (lock_rename(workdir, upperdir) == NULL); | |
524 | unlock_rename(workdir, upperdir); | |
525 | } | |
526 | return ok; | |
527 | } | |
528 | ||
a78d9f0d MS |
529 | static unsigned int ovl_split_lowerdirs(char *str) |
530 | { | |
531 | unsigned int ctr = 1; | |
532 | char *s, *d; | |
533 | ||
534 | for (s = d = str;; s++, d++) { | |
535 | if (*s == '\\') { | |
536 | s++; | |
537 | } else if (*s == ':') { | |
538 | *d = '\0'; | |
539 | ctr++; | |
540 | continue; | |
541 | } | |
542 | *d = *s; | |
543 | if (!*s) | |
544 | break; | |
545 | } | |
546 | return ctr; | |
547 | } | |
548 | ||
0eb45fc3 AG |
549 | static int __maybe_unused |
550 | ovl_posix_acl_xattr_get(const struct xattr_handler *handler, | |
551 | struct dentry *dentry, struct inode *inode, | |
552 | const char *name, void *buffer, size_t size) | |
553 | { | |
554 | return ovl_xattr_get(dentry, handler->name, buffer, size); | |
555 | } | |
556 | ||
0c97be22 AG |
557 | static int __maybe_unused |
558 | ovl_posix_acl_xattr_set(const struct xattr_handler *handler, | |
559 | struct dentry *dentry, struct inode *inode, | |
560 | const char *name, const void *value, | |
561 | size_t size, int flags) | |
d837a49b MS |
562 | { |
563 | struct dentry *workdir = ovl_workdir(dentry); | |
564 | struct inode *realinode = ovl_inode_real(inode, NULL); | |
565 | struct posix_acl *acl = NULL; | |
566 | int err; | |
567 | ||
568 | /* Check that everything is OK before copy-up */ | |
569 | if (value) { | |
570 | acl = posix_acl_from_xattr(&init_user_ns, value, size); | |
571 | if (IS_ERR(acl)) | |
572 | return PTR_ERR(acl); | |
573 | } | |
574 | err = -EOPNOTSUPP; | |
575 | if (!IS_POSIXACL(d_inode(workdir))) | |
576 | goto out_acl_release; | |
577 | if (!realinode->i_op->set_acl) | |
578 | goto out_acl_release; | |
579 | if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) { | |
580 | err = acl ? -EACCES : 0; | |
581 | goto out_acl_release; | |
582 | } | |
583 | err = -EPERM; | |
584 | if (!inode_owner_or_capable(inode)) | |
585 | goto out_acl_release; | |
586 | ||
587 | posix_acl_release(acl); | |
588 | ||
fd3220d3 MS |
589 | /* |
590 | * Check if sgid bit needs to be cleared (actual setacl operation will | |
591 | * be done with mounter's capabilities and so that won't do it for us). | |
592 | */ | |
593 | if (unlikely(inode->i_mode & S_ISGID) && | |
594 | handler->flags == ACL_TYPE_ACCESS && | |
595 | !in_group_p(inode->i_gid) && | |
596 | !capable_wrt_inode_uidgid(inode, CAP_FSETID)) { | |
597 | struct iattr iattr = { .ia_valid = ATTR_KILL_SGID }; | |
598 | ||
599 | err = ovl_setattr(dentry, &iattr); | |
600 | if (err) | |
601 | return err; | |
602 | } | |
603 | ||
ce31513a MS |
604 | err = ovl_xattr_set(dentry, handler->name, value, size, flags); |
605 | if (!err) | |
606 | ovl_copyattr(ovl_inode_real(inode, NULL), inode); | |
607 | ||
608 | return err; | |
d837a49b MS |
609 | |
610 | out_acl_release: | |
611 | posix_acl_release(acl); | |
612 | return err; | |
613 | } | |
614 | ||
0eb45fc3 AG |
615 | static int ovl_own_xattr_get(const struct xattr_handler *handler, |
616 | struct dentry *dentry, struct inode *inode, | |
617 | const char *name, void *buffer, size_t size) | |
618 | { | |
48fab5d7 | 619 | return -EOPNOTSUPP; |
0eb45fc3 AG |
620 | } |
621 | ||
d837a49b MS |
622 | static int ovl_own_xattr_set(const struct xattr_handler *handler, |
623 | struct dentry *dentry, struct inode *inode, | |
624 | const char *name, const void *value, | |
625 | size_t size, int flags) | |
626 | { | |
48fab5d7 | 627 | return -EOPNOTSUPP; |
d837a49b MS |
628 | } |
629 | ||
0eb45fc3 AG |
630 | static int ovl_other_xattr_get(const struct xattr_handler *handler, |
631 | struct dentry *dentry, struct inode *inode, | |
632 | const char *name, void *buffer, size_t size) | |
633 | { | |
634 | return ovl_xattr_get(dentry, name, buffer, size); | |
635 | } | |
636 | ||
0e585ccc AG |
637 | static int ovl_other_xattr_set(const struct xattr_handler *handler, |
638 | struct dentry *dentry, struct inode *inode, | |
639 | const char *name, const void *value, | |
640 | size_t size, int flags) | |
641 | { | |
642 | return ovl_xattr_set(dentry, name, value, size, flags); | |
643 | } | |
644 | ||
0c97be22 AG |
645 | static const struct xattr_handler __maybe_unused |
646 | ovl_posix_acl_access_xattr_handler = { | |
d837a49b MS |
647 | .name = XATTR_NAME_POSIX_ACL_ACCESS, |
648 | .flags = ACL_TYPE_ACCESS, | |
0eb45fc3 | 649 | .get = ovl_posix_acl_xattr_get, |
d837a49b MS |
650 | .set = ovl_posix_acl_xattr_set, |
651 | }; | |
652 | ||
0c97be22 AG |
653 | static const struct xattr_handler __maybe_unused |
654 | ovl_posix_acl_default_xattr_handler = { | |
d837a49b MS |
655 | .name = XATTR_NAME_POSIX_ACL_DEFAULT, |
656 | .flags = ACL_TYPE_DEFAULT, | |
0eb45fc3 | 657 | .get = ovl_posix_acl_xattr_get, |
d837a49b MS |
658 | .set = ovl_posix_acl_xattr_set, |
659 | }; | |
660 | ||
661 | static const struct xattr_handler ovl_own_xattr_handler = { | |
662 | .prefix = OVL_XATTR_PREFIX, | |
0eb45fc3 | 663 | .get = ovl_own_xattr_get, |
d837a49b MS |
664 | .set = ovl_own_xattr_set, |
665 | }; | |
666 | ||
667 | static const struct xattr_handler ovl_other_xattr_handler = { | |
668 | .prefix = "", /* catch all */ | |
0eb45fc3 | 669 | .get = ovl_other_xattr_get, |
d837a49b MS |
670 | .set = ovl_other_xattr_set, |
671 | }; | |
672 | ||
673 | static const struct xattr_handler *ovl_xattr_handlers[] = { | |
0c97be22 | 674 | #ifdef CONFIG_FS_POSIX_ACL |
d837a49b MS |
675 | &ovl_posix_acl_access_xattr_handler, |
676 | &ovl_posix_acl_default_xattr_handler, | |
0c97be22 | 677 | #endif |
d837a49b MS |
678 | &ovl_own_xattr_handler, |
679 | &ovl_other_xattr_handler, | |
680 | NULL | |
681 | }; | |
682 | ||
e9be9d5e MS |
683 | static int ovl_fill_super(struct super_block *sb, void *data, int silent) |
684 | { | |
53a08cb9 MS |
685 | struct path upperpath = { NULL, NULL }; |
686 | struct path workpath = { NULL, NULL }; | |
e9be9d5e | 687 | struct dentry *root_dentry; |
39b681f8 | 688 | struct inode *realinode; |
e9be9d5e MS |
689 | struct ovl_entry *oe; |
690 | struct ovl_fs *ufs; | |
a78d9f0d MS |
691 | struct path *stack = NULL; |
692 | char *lowertmp; | |
693 | char *lower; | |
694 | unsigned int numlower; | |
695 | unsigned int stacklen = 0; | |
dd662667 | 696 | unsigned int i; |
7c03b5d4 | 697 | bool remote = false; |
e9be9d5e MS |
698 | int err; |
699 | ||
f45827e8 EZ |
700 | err = -ENOMEM; |
701 | ufs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); | |
702 | if (!ufs) | |
e9be9d5e MS |
703 | goto out; |
704 | ||
f45827e8 EZ |
705 | err = ovl_parse_opt((char *) data, &ufs->config); |
706 | if (err) | |
707 | goto out_free_config; | |
708 | ||
e9be9d5e | 709 | err = -EINVAL; |
53a08cb9 | 710 | if (!ufs->config.lowerdir) { |
07f2af7b KK |
711 | if (!silent) |
712 | pr_err("overlayfs: missing 'lowerdir'\n"); | |
e9be9d5e MS |
713 | goto out_free_config; |
714 | } | |
715 | ||
53a08cb9 | 716 | sb->s_stack_depth = 0; |
cf9a6784 | 717 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
53a08cb9 | 718 | if (ufs->config.upperdir) { |
53a08cb9 MS |
719 | if (!ufs->config.workdir) { |
720 | pr_err("overlayfs: missing 'workdir'\n"); | |
721 | goto out_free_config; | |
722 | } | |
e9be9d5e | 723 | |
53a08cb9 MS |
724 | err = ovl_mount_dir(ufs->config.upperdir, &upperpath); |
725 | if (err) | |
726 | goto out_free_config; | |
e9be9d5e | 727 | |
71cbad7e | 728 | /* Upper fs should not be r/o */ |
729 | if (upperpath.mnt->mnt_sb->s_flags & MS_RDONLY) { | |
730 | pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n"); | |
731 | err = -EINVAL; | |
732 | goto out_put_upperpath; | |
733 | } | |
734 | ||
6b2d5fe4 MS |
735 | err = ovl_check_namelen(&upperpath, ufs, ufs->config.upperdir); |
736 | if (err) | |
737 | goto out_put_upperpath; | |
738 | ||
53a08cb9 MS |
739 | err = ovl_mount_dir(ufs->config.workdir, &workpath); |
740 | if (err) | |
741 | goto out_put_upperpath; | |
742 | ||
2f83fd8c | 743 | err = -EINVAL; |
53a08cb9 MS |
744 | if (upperpath.mnt != workpath.mnt) { |
745 | pr_err("overlayfs: workdir and upperdir must reside under the same mount\n"); | |
746 | goto out_put_workpath; | |
747 | } | |
748 | if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) { | |
749 | pr_err("overlayfs: workdir and upperdir must be separate subtrees\n"); | |
750 | goto out_put_workpath; | |
751 | } | |
752 | sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth; | |
cc259639 | 753 | } |
a78d9f0d MS |
754 | err = -ENOMEM; |
755 | lowertmp = kstrdup(ufs->config.lowerdir, GFP_KERNEL); | |
756 | if (!lowertmp) | |
ab508822 | 757 | goto out_put_workpath; |
69c433ed | 758 | |
a78d9f0d MS |
759 | err = -EINVAL; |
760 | stacklen = ovl_split_lowerdirs(lowertmp); | |
6be4506e | 761 | if (stacklen > OVL_MAX_STACK) { |
fd36570a | 762 | pr_err("overlayfs: too many lower directories, limit is %d\n", |
6be4506e | 763 | OVL_MAX_STACK); |
a78d9f0d | 764 | goto out_free_lowertmp; |
6be4506e | 765 | } else if (!ufs->config.upperdir && stacklen == 1) { |
766 | pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n"); | |
767 | goto out_free_lowertmp; | |
768 | } | |
a78d9f0d MS |
769 | |
770 | stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL); | |
771 | if (!stack) | |
772 | goto out_free_lowertmp; | |
773 | ||
774 | lower = lowertmp; | |
775 | for (numlower = 0; numlower < stacklen; numlower++) { | |
6b2d5fe4 MS |
776 | err = ovl_lower_dir(lower, &stack[numlower], ufs, |
777 | &sb->s_stack_depth, &remote); | |
a78d9f0d MS |
778 | if (err) |
779 | goto out_put_lowerpath; | |
780 | ||
781 | lower = strchr(lower, '\0') + 1; | |
782 | } | |
783 | ||
69c433ed | 784 | err = -EINVAL; |
ab508822 | 785 | sb->s_stack_depth++; |
69c433ed MS |
786 | if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { |
787 | pr_err("overlayfs: maximum fs stacking depth exceeded\n"); | |
3b7a9a24 | 788 | goto out_put_lowerpath; |
69c433ed MS |
789 | } |
790 | ||
53a08cb9 MS |
791 | if (ufs->config.upperdir) { |
792 | ufs->upper_mnt = clone_private_mount(&upperpath); | |
793 | err = PTR_ERR(ufs->upper_mnt); | |
794 | if (IS_ERR(ufs->upper_mnt)) { | |
795 | pr_err("overlayfs: failed to clone upperpath\n"); | |
796 | goto out_put_lowerpath; | |
797 | } | |
d719e8f2 MS |
798 | /* Don't inherit atime flags */ |
799 | ufs->upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); | |
800 | ||
801 | sb->s_time_gran = ufs->upper_mnt->mnt_sb->s_time_gran; | |
3b7a9a24 | 802 | |
53a08cb9 MS |
803 | ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry); |
804 | err = PTR_ERR(ufs->workdir); | |
805 | if (IS_ERR(ufs->workdir)) { | |
cc6f67bc MS |
806 | pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n", |
807 | ufs->config.workdir, OVL_WORKDIR_NAME, -err); | |
808 | sb->s_flags |= MS_RDONLY; | |
809 | ufs->workdir = NULL; | |
53a08cb9 | 810 | } |
45aebeaf VG |
811 | |
812 | /* | |
813 | * Upper should support d_type, else whiteouts are visible. | |
814 | * Given workdir and upper are on same fs, we can do | |
21765194 VG |
815 | * iterate_dir() on workdir. This check requires successful |
816 | * creation of workdir in previous step. | |
45aebeaf | 817 | */ |
21765194 VG |
818 | if (ufs->workdir) { |
819 | err = ovl_check_d_type_supported(&workpath); | |
820 | if (err < 0) | |
821 | goto out_put_workdir; | |
45aebeaf | 822 | |
e7c0b599 VG |
823 | /* |
824 | * We allowed this configuration and don't want to | |
825 | * break users over kernel upgrade. So warn instead | |
826 | * of erroring out. | |
827 | */ | |
828 | if (!err) | |
829 | pr_warn("overlayfs: upper fs needs to support d_type.\n"); | |
45aebeaf | 830 | } |
e9be9d5e MS |
831 | } |
832 | ||
2f83fd8c | 833 | err = -ENOMEM; |
a78d9f0d | 834 | ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL); |
dd662667 | 835 | if (ufs->lower_mnt == NULL) |
3b7a9a24 | 836 | goto out_put_workdir; |
a78d9f0d MS |
837 | for (i = 0; i < numlower; i++) { |
838 | struct vfsmount *mnt = clone_private_mount(&stack[i]); | |
dd662667 | 839 | |
2f83fd8c | 840 | err = PTR_ERR(mnt); |
a78d9f0d MS |
841 | if (IS_ERR(mnt)) { |
842 | pr_err("overlayfs: failed to clone lowerpath\n"); | |
843 | goto out_put_lower_mnt; | |
844 | } | |
845 | /* | |
846 | * Make lower_mnt R/O. That way fchmod/fchown on lower file | |
847 | * will fail instead of modifying lower fs. | |
848 | */ | |
d719e8f2 | 849 | mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME; |
dd662667 | 850 | |
a78d9f0d MS |
851 | ufs->lower_mnt[ufs->numlower] = mnt; |
852 | ufs->numlower++; | |
853 | } | |
e9be9d5e | 854 | |
71cbad7e | 855 | /* If the upper fs is nonexistent, we mark overlayfs r/o too */ |
856 | if (!ufs->upper_mnt) | |
e9be9d5e MS |
857 | sb->s_flags |= MS_RDONLY; |
858 | ||
7c03b5d4 MS |
859 | if (remote) |
860 | sb->s_d_op = &ovl_reval_dentry_operations; | |
861 | else | |
862 | sb->s_d_op = &ovl_dentry_operations; | |
e9be9d5e | 863 | |
3fe6e52f AM |
864 | ufs->creator_cred = prepare_creds(); |
865 | if (!ufs->creator_cred) | |
866 | goto out_put_lower_mnt; | |
867 | ||
e9be9d5e | 868 | err = -ENOMEM; |
a78d9f0d | 869 | oe = ovl_alloc_entry(numlower); |
3b7a9a24 | 870 | if (!oe) |
3fe6e52f | 871 | goto out_put_cred; |
e9be9d5e | 872 | |
655042cc VG |
873 | sb->s_magic = OVERLAYFS_SUPER_MAGIC; |
874 | sb->s_op = &ovl_super_operations; | |
875 | sb->s_xattr = ovl_xattr_handlers; | |
876 | sb->s_fs_info = ufs; | |
877 | sb->s_flags |= MS_POSIXACL | MS_NOREMOTELOCK; | |
878 | ||
ca4c8a3a | 879 | root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0)); |
e9be9d5e | 880 | if (!root_dentry) |
3b7a9a24 | 881 | goto out_free_oe; |
e9be9d5e MS |
882 | |
883 | mntput(upperpath.mnt); | |
a78d9f0d MS |
884 | for (i = 0; i < numlower; i++) |
885 | mntput(stack[i].mnt); | |
e9be9d5e | 886 | path_put(&workpath); |
a78d9f0d | 887 | kfree(lowertmp); |
e9be9d5e MS |
888 | |
889 | oe->__upperdentry = upperpath.dentry; | |
a78d9f0d MS |
890 | for (i = 0; i < numlower; i++) { |
891 | oe->lowerstack[i].dentry = stack[i].dentry; | |
892 | oe->lowerstack[i].mnt = ufs->lower_mnt[i]; | |
893 | } | |
0f95502a | 894 | kfree(stack); |
e9be9d5e MS |
895 | |
896 | root_dentry->d_fsdata = oe; | |
897 | ||
39b681f8 MS |
898 | realinode = d_inode(ovl_dentry_real(root_dentry)); |
899 | ovl_inode_init(d_inode(root_dentry), realinode, !!upperpath.dentry); | |
900 | ovl_copyattr(realinode, d_inode(root_dentry)); | |
ed06e069 | 901 | |
e9be9d5e | 902 | sb->s_root = root_dentry; |
e9be9d5e MS |
903 | |
904 | return 0; | |
905 | ||
3b7a9a24 MS |
906 | out_free_oe: |
907 | kfree(oe); | |
3fe6e52f AM |
908 | out_put_cred: |
909 | put_cred(ufs->creator_cred); | |
e9be9d5e | 910 | out_put_lower_mnt: |
dd662667 MS |
911 | for (i = 0; i < ufs->numlower; i++) |
912 | mntput(ufs->lower_mnt[i]); | |
913 | kfree(ufs->lower_mnt); | |
3b7a9a24 MS |
914 | out_put_workdir: |
915 | dput(ufs->workdir); | |
e9be9d5e | 916 | mntput(ufs->upper_mnt); |
e9be9d5e | 917 | out_put_lowerpath: |
a78d9f0d MS |
918 | for (i = 0; i < numlower; i++) |
919 | path_put(&stack[i]); | |
920 | kfree(stack); | |
921 | out_free_lowertmp: | |
922 | kfree(lowertmp); | |
3b7a9a24 MS |
923 | out_put_workpath: |
924 | path_put(&workpath); | |
e9be9d5e MS |
925 | out_put_upperpath: |
926 | path_put(&upperpath); | |
e9be9d5e | 927 | out_free_config: |
f45827e8 EZ |
928 | kfree(ufs->config.lowerdir); |
929 | kfree(ufs->config.upperdir); | |
930 | kfree(ufs->config.workdir); | |
931 | kfree(ufs); | |
e9be9d5e MS |
932 | out: |
933 | return err; | |
934 | } | |
935 | ||
936 | static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, | |
937 | const char *dev_name, void *raw_data) | |
938 | { | |
939 | return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); | |
940 | } | |
941 | ||
942 | static struct file_system_type ovl_fs_type = { | |
943 | .owner = THIS_MODULE, | |
ef94b186 | 944 | .name = "overlay", |
e9be9d5e MS |
945 | .mount = ovl_mount, |
946 | .kill_sb = kill_anon_super, | |
947 | }; | |
ef94b186 | 948 | MODULE_ALIAS_FS("overlay"); |
e9be9d5e MS |
949 | |
950 | static int __init ovl_init(void) | |
951 | { | |
952 | return register_filesystem(&ovl_fs_type); | |
953 | } | |
954 | ||
955 | static void __exit ovl_exit(void) | |
956 | { | |
957 | unregister_filesystem(&ovl_fs_type); | |
958 | } | |
959 | ||
960 | module_init(ovl_init); | |
961 | module_exit(ovl_exit); |