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 | ||
5b825c3a | 10 | #include <uapi/linux/magic.h> |
e9be9d5e MS |
11 | #include <linux/fs.h> |
12 | #include <linux/namei.h> | |
13 | #include <linux/xattr.h> | |
e9be9d5e | 14 | #include <linux/mount.h> |
e9be9d5e MS |
15 | #include <linux/parser.h> |
16 | #include <linux/module.h> | |
cc259639 | 17 | #include <linux/statfs.h> |
f45827e8 | 18 | #include <linux/seq_file.h> |
d837a49b | 19 | #include <linux/posix_acl_xattr.h> |
e9be9d5e | 20 | #include "overlayfs.h" |
bbb1e54d | 21 | #include "ovl_entry.h" |
e9be9d5e MS |
22 | |
23 | MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); | |
24 | MODULE_DESCRIPTION("Overlay filesystem"); | |
25 | MODULE_LICENSE("GPL"); | |
26 | ||
e9be9d5e MS |
27 | |
28 | struct ovl_dir_cache; | |
29 | ||
a78d9f0d MS |
30 | #define OVL_MAX_STACK 500 |
31 | ||
688ea0e5 MS |
32 | static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR); |
33 | module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644); | |
34 | MODULE_PARM_DESC(ovl_redirect_dir_def, | |
35 | "Default to on or off for the redirect_dir feature"); | |
e9be9d5e MS |
36 | |
37 | static void ovl_dentry_release(struct dentry *dentry) | |
38 | { | |
39 | struct ovl_entry *oe = dentry->d_fsdata; | |
40 | ||
41 | if (oe) { | |
dd662667 MS |
42 | unsigned int i; |
43 | ||
e9be9d5e | 44 | dput(oe->__upperdentry); |
02b69b28 | 45 | kfree(oe->redirect); |
dd662667 MS |
46 | for (i = 0; i < oe->numlower; i++) |
47 | dput(oe->lowerstack[i].dentry); | |
e9be9d5e MS |
48 | kfree_rcu(oe, rcu); |
49 | } | |
50 | } | |
51 | ||
2d902671 MS |
52 | static struct dentry *ovl_d_real(struct dentry *dentry, |
53 | const struct inode *inode, | |
54 | unsigned int open_flags) | |
d101a125 MS |
55 | { |
56 | struct dentry *real; | |
57 | ||
ca4c8a3a | 58 | if (!d_is_reg(dentry)) { |
d101a125 MS |
59 | if (!inode || inode == d_inode(dentry)) |
60 | return dentry; | |
61 | goto bug; | |
62 | } | |
63 | ||
2d902671 MS |
64 | if (d_is_negative(dentry)) |
65 | return dentry; | |
66 | ||
67 | if (open_flags) { | |
68 | int err = ovl_open_maybe_copy_up(dentry, open_flags); | |
69 | ||
70 | if (err) | |
71 | return ERR_PTR(err); | |
72 | } | |
73 | ||
d101a125 MS |
74 | real = ovl_dentry_upper(dentry); |
75 | if (real && (!inode || inode == d_inode(real))) | |
76 | return real; | |
77 | ||
78 | real = ovl_dentry_lower(dentry); | |
79 | if (!real) | |
80 | goto bug; | |
81 | ||
c4fcfc16 MS |
82 | /* Handle recursion */ |
83 | real = d_real(real, inode, open_flags); | |
84 | ||
d101a125 MS |
85 | if (!inode || inode == d_inode(real)) |
86 | return real; | |
d101a125 | 87 | bug: |
656189d2 | 88 | WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry, |
d101a125 MS |
89 | inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0); |
90 | return dentry; | |
91 | } | |
92 | ||
7c03b5d4 MS |
93 | static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) |
94 | { | |
95 | struct ovl_entry *oe = dentry->d_fsdata; | |
96 | unsigned int i; | |
97 | int ret = 1; | |
98 | ||
99 | for (i = 0; i < oe->numlower; i++) { | |
100 | struct dentry *d = oe->lowerstack[i].dentry; | |
101 | ||
102 | if (d->d_flags & DCACHE_OP_REVALIDATE) { | |
103 | ret = d->d_op->d_revalidate(d, flags); | |
104 | if (ret < 0) | |
105 | return ret; | |
106 | if (!ret) { | |
107 | if (!(flags & LOOKUP_RCU)) | |
108 | d_invalidate(d); | |
109 | return -ESTALE; | |
110 | } | |
111 | } | |
112 | } | |
113 | return 1; | |
114 | } | |
115 | ||
116 | static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) | |
117 | { | |
118 | struct ovl_entry *oe = dentry->d_fsdata; | |
119 | unsigned int i; | |
120 | int ret = 1; | |
121 | ||
122 | for (i = 0; i < oe->numlower; i++) { | |
123 | struct dentry *d = oe->lowerstack[i].dentry; | |
124 | ||
125 | if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) { | |
126 | ret = d->d_op->d_weak_revalidate(d, flags); | |
127 | if (ret <= 0) | |
128 | break; | |
129 | } | |
130 | } | |
131 | return ret; | |
132 | } | |
133 | ||
e9be9d5e MS |
134 | static const struct dentry_operations ovl_dentry_operations = { |
135 | .d_release = ovl_dentry_release, | |
d101a125 | 136 | .d_real = ovl_d_real, |
e9be9d5e MS |
137 | }; |
138 | ||
7c03b5d4 MS |
139 | static const struct dentry_operations ovl_reval_dentry_operations = { |
140 | .d_release = ovl_dentry_release, | |
d101a125 | 141 | .d_real = ovl_d_real, |
7c03b5d4 MS |
142 | .d_revalidate = ovl_dentry_revalidate, |
143 | .d_weak_revalidate = ovl_dentry_weak_revalidate, | |
144 | }; | |
145 | ||
e9be9d5e MS |
146 | static void ovl_put_super(struct super_block *sb) |
147 | { | |
148 | struct ovl_fs *ufs = sb->s_fs_info; | |
dd662667 | 149 | unsigned i; |
e9be9d5e MS |
150 | |
151 | dput(ufs->workdir); | |
152 | mntput(ufs->upper_mnt); | |
dd662667 MS |
153 | for (i = 0; i < ufs->numlower; i++) |
154 | mntput(ufs->lower_mnt[i]); | |
5ffdbe8b | 155 | kfree(ufs->lower_mnt); |
e9be9d5e | 156 | |
f45827e8 EZ |
157 | kfree(ufs->config.lowerdir); |
158 | kfree(ufs->config.upperdir); | |
159 | kfree(ufs->config.workdir); | |
3fe6e52f | 160 | put_cred(ufs->creator_cred); |
e9be9d5e MS |
161 | kfree(ufs); |
162 | } | |
163 | ||
e593b2bf AG |
164 | static int ovl_sync_fs(struct super_block *sb, int wait) |
165 | { | |
166 | struct ovl_fs *ufs = sb->s_fs_info; | |
167 | struct super_block *upper_sb; | |
168 | int ret; | |
169 | ||
170 | if (!ufs->upper_mnt) | |
171 | return 0; | |
172 | upper_sb = ufs->upper_mnt->mnt_sb; | |
173 | if (!upper_sb->s_op->sync_fs) | |
174 | return 0; | |
175 | ||
176 | /* real inodes have already been synced by sync_filesystem(ovl_sb) */ | |
177 | down_read(&upper_sb->s_umount); | |
178 | ret = upper_sb->s_op->sync_fs(upper_sb, wait); | |
179 | up_read(&upper_sb->s_umount); | |
180 | return ret; | |
181 | } | |
182 | ||
cc259639 AW |
183 | /** |
184 | * ovl_statfs | |
185 | * @sb: The overlayfs super block | |
186 | * @buf: The struct kstatfs to fill in with stats | |
187 | * | |
188 | * Get the filesystem statistics. As writes always target the upper layer | |
4ebc5818 | 189 | * filesystem pass the statfs to the upper filesystem (if it exists) |
cc259639 AW |
190 | */ |
191 | static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) | |
192 | { | |
193 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
194 | struct dentry *root_dentry = dentry->d_sb->s_root; | |
195 | struct path path; | |
196 | int err; | |
197 | ||
4ebc5818 | 198 | ovl_path_real(root_dentry, &path); |
cc259639 AW |
199 | |
200 | err = vfs_statfs(&path, buf); | |
201 | if (!err) { | |
6b2d5fe4 | 202 | buf->f_namelen = ofs->namelen; |
cc259639 AW |
203 | buf->f_type = OVERLAYFS_SUPER_MAGIC; |
204 | } | |
205 | ||
206 | return err; | |
207 | } | |
208 | ||
f45827e8 EZ |
209 | /** |
210 | * ovl_show_options | |
211 | * | |
212 | * Prints the mount options for a given superblock. | |
213 | * Returns zero; does not fail. | |
214 | */ | |
215 | static int ovl_show_options(struct seq_file *m, struct dentry *dentry) | |
216 | { | |
217 | struct super_block *sb = dentry->d_sb; | |
218 | struct ovl_fs *ufs = sb->s_fs_info; | |
219 | ||
a068acf2 | 220 | seq_show_option(m, "lowerdir", ufs->config.lowerdir); |
53a08cb9 | 221 | if (ufs->config.upperdir) { |
a068acf2 KC |
222 | seq_show_option(m, "upperdir", ufs->config.upperdir); |
223 | seq_show_option(m, "workdir", ufs->config.workdir); | |
53a08cb9 | 224 | } |
8d3095f4 MS |
225 | if (ufs->config.default_permissions) |
226 | seq_puts(m, ",default_permissions"); | |
c5bef3a7 AG |
227 | if (ufs->config.redirect_dir != ovl_redirect_dir_def) |
228 | seq_printf(m, ",redirect_dir=%s", | |
229 | ufs->config.redirect_dir ? "on" : "off"); | |
f45827e8 EZ |
230 | return 0; |
231 | } | |
232 | ||
3cdf6fe9 SL |
233 | static int ovl_remount(struct super_block *sb, int *flags, char *data) |
234 | { | |
235 | struct ovl_fs *ufs = sb->s_fs_info; | |
236 | ||
cc6f67bc | 237 | if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt || !ufs->workdir)) |
3cdf6fe9 SL |
238 | return -EROFS; |
239 | ||
240 | return 0; | |
241 | } | |
242 | ||
e9be9d5e MS |
243 | static const struct super_operations ovl_super_operations = { |
244 | .put_super = ovl_put_super, | |
e593b2bf | 245 | .sync_fs = ovl_sync_fs, |
cc259639 | 246 | .statfs = ovl_statfs, |
f45827e8 | 247 | .show_options = ovl_show_options, |
3cdf6fe9 | 248 | .remount_fs = ovl_remount, |
eead4f2d | 249 | .drop_inode = generic_delete_inode, |
e9be9d5e MS |
250 | }; |
251 | ||
252 | enum { | |
253 | OPT_LOWERDIR, | |
254 | OPT_UPPERDIR, | |
255 | OPT_WORKDIR, | |
8d3095f4 | 256 | OPT_DEFAULT_PERMISSIONS, |
a6c60655 MS |
257 | OPT_REDIRECT_DIR_ON, |
258 | OPT_REDIRECT_DIR_OFF, | |
e9be9d5e MS |
259 | OPT_ERR, |
260 | }; | |
261 | ||
262 | static const match_table_t ovl_tokens = { | |
263 | {OPT_LOWERDIR, "lowerdir=%s"}, | |
264 | {OPT_UPPERDIR, "upperdir=%s"}, | |
265 | {OPT_WORKDIR, "workdir=%s"}, | |
8d3095f4 | 266 | {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, |
a6c60655 MS |
267 | {OPT_REDIRECT_DIR_ON, "redirect_dir=on"}, |
268 | {OPT_REDIRECT_DIR_OFF, "redirect_dir=off"}, | |
e9be9d5e MS |
269 | {OPT_ERR, NULL} |
270 | }; | |
271 | ||
91c77947 MS |
272 | static char *ovl_next_opt(char **s) |
273 | { | |
274 | char *sbegin = *s; | |
275 | char *p; | |
276 | ||
277 | if (sbegin == NULL) | |
278 | return NULL; | |
279 | ||
280 | for (p = sbegin; *p; p++) { | |
281 | if (*p == '\\') { | |
282 | p++; | |
283 | if (!*p) | |
284 | break; | |
285 | } else if (*p == ',') { | |
286 | *p = '\0'; | |
287 | *s = p + 1; | |
288 | return sbegin; | |
289 | } | |
290 | } | |
291 | *s = NULL; | |
292 | return sbegin; | |
293 | } | |
294 | ||
e9be9d5e MS |
295 | static int ovl_parse_opt(char *opt, struct ovl_config *config) |
296 | { | |
297 | char *p; | |
298 | ||
91c77947 | 299 | while ((p = ovl_next_opt(&opt)) != NULL) { |
e9be9d5e MS |
300 | int token; |
301 | substring_t args[MAX_OPT_ARGS]; | |
302 | ||
303 | if (!*p) | |
304 | continue; | |
305 | ||
306 | token = match_token(p, ovl_tokens, args); | |
307 | switch (token) { | |
308 | case OPT_UPPERDIR: | |
309 | kfree(config->upperdir); | |
310 | config->upperdir = match_strdup(&args[0]); | |
311 | if (!config->upperdir) | |
312 | return -ENOMEM; | |
313 | break; | |
314 | ||
315 | case OPT_LOWERDIR: | |
316 | kfree(config->lowerdir); | |
317 | config->lowerdir = match_strdup(&args[0]); | |
318 | if (!config->lowerdir) | |
319 | return -ENOMEM; | |
320 | break; | |
321 | ||
322 | case OPT_WORKDIR: | |
323 | kfree(config->workdir); | |
324 | config->workdir = match_strdup(&args[0]); | |
325 | if (!config->workdir) | |
326 | return -ENOMEM; | |
327 | break; | |
328 | ||
8d3095f4 MS |
329 | case OPT_DEFAULT_PERMISSIONS: |
330 | config->default_permissions = true; | |
331 | break; | |
332 | ||
a6c60655 MS |
333 | case OPT_REDIRECT_DIR_ON: |
334 | config->redirect_dir = true; | |
335 | break; | |
336 | ||
337 | case OPT_REDIRECT_DIR_OFF: | |
338 | config->redirect_dir = false; | |
339 | break; | |
340 | ||
e9be9d5e | 341 | default: |
bead55ef | 342 | pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p); |
e9be9d5e MS |
343 | return -EINVAL; |
344 | } | |
345 | } | |
71cbad7e | 346 | |
347 | /* Workdir is useless in non-upper mount */ | |
348 | if (!config->upperdir && config->workdir) { | |
349 | pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n", | |
350 | config->workdir); | |
351 | kfree(config->workdir); | |
352 | config->workdir = NULL; | |
353 | } | |
354 | ||
e9be9d5e MS |
355 | return 0; |
356 | } | |
357 | ||
358 | #define OVL_WORKDIR_NAME "work" | |
359 | ||
360 | static struct dentry *ovl_workdir_create(struct vfsmount *mnt, | |
361 | struct dentry *dentry) | |
362 | { | |
363 | struct inode *dir = dentry->d_inode; | |
364 | struct dentry *work; | |
365 | int err; | |
366 | bool retried = false; | |
367 | ||
368 | err = mnt_want_write(mnt); | |
369 | if (err) | |
370 | return ERR_PTR(err); | |
371 | ||
5955102c | 372 | inode_lock_nested(dir, I_MUTEX_PARENT); |
e9be9d5e MS |
373 | retry: |
374 | work = lookup_one_len(OVL_WORKDIR_NAME, dentry, | |
375 | strlen(OVL_WORKDIR_NAME)); | |
376 | ||
377 | if (!IS_ERR(work)) { | |
c11b9fdd MS |
378 | struct iattr attr = { |
379 | .ia_valid = ATTR_MODE, | |
32a3d848 | 380 | .ia_mode = S_IFDIR | 0, |
c11b9fdd | 381 | }; |
e9be9d5e MS |
382 | |
383 | if (work->d_inode) { | |
384 | err = -EEXIST; | |
385 | if (retried) | |
386 | goto out_dput; | |
387 | ||
388 | retried = true; | |
eea2fb48 | 389 | ovl_workdir_cleanup(dir, mnt, work, 0); |
e9be9d5e MS |
390 | dput(work); |
391 | goto retry; | |
392 | } | |
393 | ||
32a3d848 AV |
394 | err = ovl_create_real(dir, work, |
395 | &(struct cattr){.mode = S_IFDIR | 0}, | |
396 | NULL, true); | |
e9be9d5e MS |
397 | if (err) |
398 | goto out_dput; | |
c11b9fdd | 399 | |
cb348edb MS |
400 | /* |
401 | * Try to remove POSIX ACL xattrs from workdir. We are good if: | |
402 | * | |
403 | * a) success (there was a POSIX ACL xattr and was removed) | |
404 | * b) -ENODATA (there was no POSIX ACL xattr) | |
405 | * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported) | |
406 | * | |
407 | * There are various other error values that could effectively | |
408 | * mean that the xattr doesn't exist (e.g. -ERANGE is returned | |
409 | * if the xattr name is too long), but the set of filesystems | |
410 | * allowed as upper are limited to "normal" ones, where checking | |
411 | * for the above two errors is sufficient. | |
412 | */ | |
c11b9fdd | 413 | err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT); |
e1ff3dd1 | 414 | if (err && err != -ENODATA && err != -EOPNOTSUPP) |
c11b9fdd MS |
415 | goto out_dput; |
416 | ||
417 | err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_ACCESS); | |
e1ff3dd1 | 418 | if (err && err != -ENODATA && err != -EOPNOTSUPP) |
c11b9fdd MS |
419 | goto out_dput; |
420 | ||
421 | /* Clear any inherited mode bits */ | |
422 | inode_lock(work->d_inode); | |
423 | err = notify_change(work, &attr, NULL); | |
424 | inode_unlock(work->d_inode); | |
425 | if (err) | |
426 | goto out_dput; | |
e9be9d5e MS |
427 | } |
428 | out_unlock: | |
5955102c | 429 | inode_unlock(dir); |
e9be9d5e MS |
430 | mnt_drop_write(mnt); |
431 | ||
432 | return work; | |
433 | ||
434 | out_dput: | |
435 | dput(work); | |
436 | work = ERR_PTR(err); | |
437 | goto out_unlock; | |
438 | } | |
439 | ||
91c77947 MS |
440 | static void ovl_unescape(char *s) |
441 | { | |
442 | char *d = s; | |
443 | ||
444 | for (;; s++, d++) { | |
445 | if (*s == '\\') | |
446 | s++; | |
447 | *d = *s; | |
448 | if (!*s) | |
449 | break; | |
450 | } | |
451 | } | |
452 | ||
ab508822 MS |
453 | static int ovl_mount_dir_noesc(const char *name, struct path *path) |
454 | { | |
a78d9f0d | 455 | int err = -EINVAL; |
ab508822 | 456 | |
a78d9f0d MS |
457 | if (!*name) { |
458 | pr_err("overlayfs: empty lowerdir\n"); | |
459 | goto out; | |
460 | } | |
ab508822 MS |
461 | err = kern_path(name, LOOKUP_FOLLOW, path); |
462 | if (err) { | |
463 | pr_err("overlayfs: failed to resolve '%s': %i\n", name, err); | |
464 | goto out; | |
465 | } | |
466 | err = -EINVAL; | |
7c03b5d4 | 467 | if (ovl_dentry_weird(path->dentry)) { |
ab508822 MS |
468 | pr_err("overlayfs: filesystem on '%s' not supported\n", name); |
469 | goto out_put; | |
470 | } | |
2b8c30e9 | 471 | if (!d_is_dir(path->dentry)) { |
ab508822 MS |
472 | pr_err("overlayfs: '%s' not a directory\n", name); |
473 | goto out_put; | |
474 | } | |
475 | return 0; | |
476 | ||
477 | out_put: | |
478 | path_put(path); | |
479 | out: | |
480 | return err; | |
481 | } | |
482 | ||
483 | static int ovl_mount_dir(const char *name, struct path *path) | |
484 | { | |
485 | int err = -ENOMEM; | |
486 | char *tmp = kstrdup(name, GFP_KERNEL); | |
487 | ||
488 | if (tmp) { | |
489 | ovl_unescape(tmp); | |
490 | err = ovl_mount_dir_noesc(tmp, path); | |
7c03b5d4 MS |
491 | |
492 | if (!err) | |
493 | if (ovl_dentry_remote(path->dentry)) { | |
494 | pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n", | |
495 | tmp); | |
496 | path_put(path); | |
497 | err = -EINVAL; | |
498 | } | |
ab508822 MS |
499 | kfree(tmp); |
500 | } | |
501 | return err; | |
502 | } | |
503 | ||
6b2d5fe4 MS |
504 | static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs, |
505 | const char *name) | |
ab508822 | 506 | { |
ab508822 | 507 | struct kstatfs statfs; |
6b2d5fe4 MS |
508 | int err = vfs_statfs(path, &statfs); |
509 | ||
510 | if (err) | |
511 | pr_err("overlayfs: statfs failed on '%s'\n", name); | |
512 | else | |
513 | ofs->namelen = max(ofs->namelen, statfs.f_namelen); | |
514 | ||
515 | return err; | |
516 | } | |
517 | ||
518 | static int ovl_lower_dir(const char *name, struct path *path, | |
519 | struct ovl_fs *ofs, int *stack_depth, bool *remote) | |
520 | { | |
521 | int err; | |
ab508822 | 522 | |
a78d9f0d | 523 | err = ovl_mount_dir_noesc(name, path); |
ab508822 MS |
524 | if (err) |
525 | goto out; | |
526 | ||
6b2d5fe4 MS |
527 | err = ovl_check_namelen(path, ofs, name); |
528 | if (err) | |
ab508822 | 529 | goto out_put; |
6b2d5fe4 | 530 | |
ab508822 MS |
531 | *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); |
532 | ||
7c03b5d4 MS |
533 | if (ovl_dentry_remote(path->dentry)) |
534 | *remote = true; | |
535 | ||
ab508822 MS |
536 | return 0; |
537 | ||
538 | out_put: | |
539 | path_put(path); | |
540 | out: | |
541 | return err; | |
542 | } | |
543 | ||
e9be9d5e MS |
544 | /* Workdir should not be subdir of upperdir and vice versa */ |
545 | static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir) | |
546 | { | |
547 | bool ok = false; | |
548 | ||
549 | if (workdir != upperdir) { | |
550 | ok = (lock_rename(workdir, upperdir) == NULL); | |
551 | unlock_rename(workdir, upperdir); | |
552 | } | |
553 | return ok; | |
554 | } | |
555 | ||
a78d9f0d MS |
556 | static unsigned int ovl_split_lowerdirs(char *str) |
557 | { | |
558 | unsigned int ctr = 1; | |
559 | char *s, *d; | |
560 | ||
561 | for (s = d = str;; s++, d++) { | |
562 | if (*s == '\\') { | |
563 | s++; | |
564 | } else if (*s == ':') { | |
565 | *d = '\0'; | |
566 | ctr++; | |
567 | continue; | |
568 | } | |
569 | *d = *s; | |
570 | if (!*s) | |
571 | break; | |
572 | } | |
573 | return ctr; | |
574 | } | |
575 | ||
0eb45fc3 AG |
576 | static int __maybe_unused |
577 | ovl_posix_acl_xattr_get(const struct xattr_handler *handler, | |
578 | struct dentry *dentry, struct inode *inode, | |
579 | const char *name, void *buffer, size_t size) | |
580 | { | |
581 | return ovl_xattr_get(dentry, handler->name, buffer, size); | |
582 | } | |
583 | ||
0c97be22 AG |
584 | static int __maybe_unused |
585 | ovl_posix_acl_xattr_set(const struct xattr_handler *handler, | |
586 | struct dentry *dentry, struct inode *inode, | |
587 | const char *name, const void *value, | |
588 | size_t size, int flags) | |
d837a49b MS |
589 | { |
590 | struct dentry *workdir = ovl_workdir(dentry); | |
591 | struct inode *realinode = ovl_inode_real(inode, NULL); | |
592 | struct posix_acl *acl = NULL; | |
593 | int err; | |
594 | ||
595 | /* Check that everything is OK before copy-up */ | |
596 | if (value) { | |
597 | acl = posix_acl_from_xattr(&init_user_ns, value, size); | |
598 | if (IS_ERR(acl)) | |
599 | return PTR_ERR(acl); | |
600 | } | |
601 | err = -EOPNOTSUPP; | |
602 | if (!IS_POSIXACL(d_inode(workdir))) | |
603 | goto out_acl_release; | |
604 | if (!realinode->i_op->set_acl) | |
605 | goto out_acl_release; | |
606 | if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) { | |
607 | err = acl ? -EACCES : 0; | |
608 | goto out_acl_release; | |
609 | } | |
610 | err = -EPERM; | |
611 | if (!inode_owner_or_capable(inode)) | |
612 | goto out_acl_release; | |
613 | ||
614 | posix_acl_release(acl); | |
615 | ||
fd3220d3 MS |
616 | /* |
617 | * Check if sgid bit needs to be cleared (actual setacl operation will | |
618 | * be done with mounter's capabilities and so that won't do it for us). | |
619 | */ | |
620 | if (unlikely(inode->i_mode & S_ISGID) && | |
621 | handler->flags == ACL_TYPE_ACCESS && | |
622 | !in_group_p(inode->i_gid) && | |
623 | !capable_wrt_inode_uidgid(inode, CAP_FSETID)) { | |
624 | struct iattr iattr = { .ia_valid = ATTR_KILL_SGID }; | |
625 | ||
626 | err = ovl_setattr(dentry, &iattr); | |
627 | if (err) | |
628 | return err; | |
629 | } | |
630 | ||
ce31513a MS |
631 | err = ovl_xattr_set(dentry, handler->name, value, size, flags); |
632 | if (!err) | |
633 | ovl_copyattr(ovl_inode_real(inode, NULL), inode); | |
634 | ||
635 | return err; | |
d837a49b MS |
636 | |
637 | out_acl_release: | |
638 | posix_acl_release(acl); | |
639 | return err; | |
640 | } | |
641 | ||
0eb45fc3 AG |
642 | static int ovl_own_xattr_get(const struct xattr_handler *handler, |
643 | struct dentry *dentry, struct inode *inode, | |
644 | const char *name, void *buffer, size_t size) | |
645 | { | |
48fab5d7 | 646 | return -EOPNOTSUPP; |
0eb45fc3 AG |
647 | } |
648 | ||
d837a49b MS |
649 | static int ovl_own_xattr_set(const struct xattr_handler *handler, |
650 | struct dentry *dentry, struct inode *inode, | |
651 | const char *name, const void *value, | |
652 | size_t size, int flags) | |
653 | { | |
48fab5d7 | 654 | return -EOPNOTSUPP; |
d837a49b MS |
655 | } |
656 | ||
0eb45fc3 AG |
657 | static int ovl_other_xattr_get(const struct xattr_handler *handler, |
658 | struct dentry *dentry, struct inode *inode, | |
659 | const char *name, void *buffer, size_t size) | |
660 | { | |
661 | return ovl_xattr_get(dentry, name, buffer, size); | |
662 | } | |
663 | ||
0e585ccc AG |
664 | static int ovl_other_xattr_set(const struct xattr_handler *handler, |
665 | struct dentry *dentry, struct inode *inode, | |
666 | const char *name, const void *value, | |
667 | size_t size, int flags) | |
668 | { | |
669 | return ovl_xattr_set(dentry, name, value, size, flags); | |
670 | } | |
671 | ||
0c97be22 AG |
672 | static const struct xattr_handler __maybe_unused |
673 | ovl_posix_acl_access_xattr_handler = { | |
d837a49b MS |
674 | .name = XATTR_NAME_POSIX_ACL_ACCESS, |
675 | .flags = ACL_TYPE_ACCESS, | |
0eb45fc3 | 676 | .get = ovl_posix_acl_xattr_get, |
d837a49b MS |
677 | .set = ovl_posix_acl_xattr_set, |
678 | }; | |
679 | ||
0c97be22 AG |
680 | static const struct xattr_handler __maybe_unused |
681 | ovl_posix_acl_default_xattr_handler = { | |
d837a49b MS |
682 | .name = XATTR_NAME_POSIX_ACL_DEFAULT, |
683 | .flags = ACL_TYPE_DEFAULT, | |
0eb45fc3 | 684 | .get = ovl_posix_acl_xattr_get, |
d837a49b MS |
685 | .set = ovl_posix_acl_xattr_set, |
686 | }; | |
687 | ||
688 | static const struct xattr_handler ovl_own_xattr_handler = { | |
689 | .prefix = OVL_XATTR_PREFIX, | |
0eb45fc3 | 690 | .get = ovl_own_xattr_get, |
d837a49b MS |
691 | .set = ovl_own_xattr_set, |
692 | }; | |
693 | ||
694 | static const struct xattr_handler ovl_other_xattr_handler = { | |
695 | .prefix = "", /* catch all */ | |
0eb45fc3 | 696 | .get = ovl_other_xattr_get, |
d837a49b MS |
697 | .set = ovl_other_xattr_set, |
698 | }; | |
699 | ||
700 | static const struct xattr_handler *ovl_xattr_handlers[] = { | |
0c97be22 | 701 | #ifdef CONFIG_FS_POSIX_ACL |
d837a49b MS |
702 | &ovl_posix_acl_access_xattr_handler, |
703 | &ovl_posix_acl_default_xattr_handler, | |
0c97be22 | 704 | #endif |
d837a49b MS |
705 | &ovl_own_xattr_handler, |
706 | &ovl_other_xattr_handler, | |
707 | NULL | |
708 | }; | |
709 | ||
e9be9d5e MS |
710 | static int ovl_fill_super(struct super_block *sb, void *data, int silent) |
711 | { | |
53a08cb9 MS |
712 | struct path upperpath = { NULL, NULL }; |
713 | struct path workpath = { NULL, NULL }; | |
e9be9d5e | 714 | struct dentry *root_dentry; |
39b681f8 | 715 | struct inode *realinode; |
e9be9d5e MS |
716 | struct ovl_entry *oe; |
717 | struct ovl_fs *ufs; | |
a78d9f0d MS |
718 | struct path *stack = NULL; |
719 | char *lowertmp; | |
720 | char *lower; | |
721 | unsigned int numlower; | |
722 | unsigned int stacklen = 0; | |
dd662667 | 723 | unsigned int i; |
7c03b5d4 | 724 | bool remote = false; |
51f8f3c4 | 725 | struct cred *cred; |
e9be9d5e MS |
726 | int err; |
727 | ||
f45827e8 EZ |
728 | err = -ENOMEM; |
729 | ufs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); | |
730 | if (!ufs) | |
e9be9d5e MS |
731 | goto out; |
732 | ||
39d3d60a | 733 | init_waitqueue_head(&ufs->copyup_wq); |
688ea0e5 | 734 | ufs->config.redirect_dir = ovl_redirect_dir_def; |
f45827e8 EZ |
735 | err = ovl_parse_opt((char *) data, &ufs->config); |
736 | if (err) | |
737 | goto out_free_config; | |
738 | ||
e9be9d5e | 739 | err = -EINVAL; |
53a08cb9 | 740 | if (!ufs->config.lowerdir) { |
07f2af7b KK |
741 | if (!silent) |
742 | pr_err("overlayfs: missing 'lowerdir'\n"); | |
e9be9d5e MS |
743 | goto out_free_config; |
744 | } | |
745 | ||
53a08cb9 | 746 | sb->s_stack_depth = 0; |
cf9a6784 | 747 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
53a08cb9 | 748 | if (ufs->config.upperdir) { |
53a08cb9 MS |
749 | if (!ufs->config.workdir) { |
750 | pr_err("overlayfs: missing 'workdir'\n"); | |
751 | goto out_free_config; | |
752 | } | |
e9be9d5e | 753 | |
53a08cb9 MS |
754 | err = ovl_mount_dir(ufs->config.upperdir, &upperpath); |
755 | if (err) | |
756 | goto out_free_config; | |
e9be9d5e | 757 | |
71cbad7e | 758 | /* Upper fs should not be r/o */ |
759 | if (upperpath.mnt->mnt_sb->s_flags & MS_RDONLY) { | |
760 | pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n"); | |
761 | err = -EINVAL; | |
762 | goto out_put_upperpath; | |
763 | } | |
764 | ||
6b2d5fe4 MS |
765 | err = ovl_check_namelen(&upperpath, ufs, ufs->config.upperdir); |
766 | if (err) | |
767 | goto out_put_upperpath; | |
768 | ||
53a08cb9 MS |
769 | err = ovl_mount_dir(ufs->config.workdir, &workpath); |
770 | if (err) | |
771 | goto out_put_upperpath; | |
772 | ||
2f83fd8c | 773 | err = -EINVAL; |
53a08cb9 MS |
774 | if (upperpath.mnt != workpath.mnt) { |
775 | pr_err("overlayfs: workdir and upperdir must reside under the same mount\n"); | |
776 | goto out_put_workpath; | |
777 | } | |
778 | if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) { | |
779 | pr_err("overlayfs: workdir and upperdir must be separate subtrees\n"); | |
780 | goto out_put_workpath; | |
781 | } | |
782 | sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth; | |
cc259639 | 783 | } |
a78d9f0d MS |
784 | err = -ENOMEM; |
785 | lowertmp = kstrdup(ufs->config.lowerdir, GFP_KERNEL); | |
786 | if (!lowertmp) | |
ab508822 | 787 | goto out_put_workpath; |
69c433ed | 788 | |
a78d9f0d MS |
789 | err = -EINVAL; |
790 | stacklen = ovl_split_lowerdirs(lowertmp); | |
6be4506e | 791 | if (stacklen > OVL_MAX_STACK) { |
fd36570a | 792 | pr_err("overlayfs: too many lower directories, limit is %d\n", |
6be4506e | 793 | OVL_MAX_STACK); |
a78d9f0d | 794 | goto out_free_lowertmp; |
6be4506e | 795 | } else if (!ufs->config.upperdir && stacklen == 1) { |
796 | pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n"); | |
797 | goto out_free_lowertmp; | |
798 | } | |
a78d9f0d | 799 | |
313684c4 | 800 | err = -ENOMEM; |
a78d9f0d MS |
801 | stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL); |
802 | if (!stack) | |
803 | goto out_free_lowertmp; | |
804 | ||
313684c4 | 805 | err = -EINVAL; |
a78d9f0d MS |
806 | lower = lowertmp; |
807 | for (numlower = 0; numlower < stacklen; numlower++) { | |
6b2d5fe4 MS |
808 | err = ovl_lower_dir(lower, &stack[numlower], ufs, |
809 | &sb->s_stack_depth, &remote); | |
a78d9f0d MS |
810 | if (err) |
811 | goto out_put_lowerpath; | |
812 | ||
813 | lower = strchr(lower, '\0') + 1; | |
814 | } | |
815 | ||
69c433ed | 816 | err = -EINVAL; |
ab508822 | 817 | sb->s_stack_depth++; |
69c433ed MS |
818 | if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { |
819 | pr_err("overlayfs: maximum fs stacking depth exceeded\n"); | |
3b7a9a24 | 820 | goto out_put_lowerpath; |
69c433ed MS |
821 | } |
822 | ||
53a08cb9 MS |
823 | if (ufs->config.upperdir) { |
824 | ufs->upper_mnt = clone_private_mount(&upperpath); | |
825 | err = PTR_ERR(ufs->upper_mnt); | |
826 | if (IS_ERR(ufs->upper_mnt)) { | |
827 | pr_err("overlayfs: failed to clone upperpath\n"); | |
828 | goto out_put_lowerpath; | |
829 | } | |
d719e8f2 MS |
830 | /* Don't inherit atime flags */ |
831 | ufs->upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); | |
832 | ||
833 | sb->s_time_gran = ufs->upper_mnt->mnt_sb->s_time_gran; | |
3b7a9a24 | 834 | |
53a08cb9 MS |
835 | ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry); |
836 | err = PTR_ERR(ufs->workdir); | |
837 | if (IS_ERR(ufs->workdir)) { | |
cc6f67bc MS |
838 | pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n", |
839 | ufs->config.workdir, OVL_WORKDIR_NAME, -err); | |
840 | sb->s_flags |= MS_RDONLY; | |
841 | ufs->workdir = NULL; | |
53a08cb9 | 842 | } |
45aebeaf VG |
843 | |
844 | /* | |
845 | * Upper should support d_type, else whiteouts are visible. | |
846 | * Given workdir and upper are on same fs, we can do | |
21765194 VG |
847 | * iterate_dir() on workdir. This check requires successful |
848 | * creation of workdir in previous step. | |
45aebeaf | 849 | */ |
21765194 | 850 | if (ufs->workdir) { |
e7f52429 AG |
851 | struct dentry *temp; |
852 | ||
21765194 VG |
853 | err = ovl_check_d_type_supported(&workpath); |
854 | if (err < 0) | |
855 | goto out_put_workdir; | |
45aebeaf | 856 | |
e7c0b599 VG |
857 | /* |
858 | * We allowed this configuration and don't want to | |
859 | * break users over kernel upgrade. So warn instead | |
860 | * of erroring out. | |
861 | */ | |
862 | if (!err) | |
863 | pr_warn("overlayfs: upper fs needs to support d_type.\n"); | |
e7f52429 AG |
864 | |
865 | /* Check if upper/work fs supports O_TMPFILE */ | |
866 | temp = ovl_do_tmpfile(ufs->workdir, S_IFREG | 0); | |
867 | ufs->tmpfile = !IS_ERR(temp); | |
868 | if (ufs->tmpfile) | |
869 | dput(temp); | |
870 | else | |
871 | pr_warn("overlayfs: upper fs does not support tmpfile.\n"); | |
45aebeaf | 872 | } |
e9be9d5e MS |
873 | } |
874 | ||
2f83fd8c | 875 | err = -ENOMEM; |
a78d9f0d | 876 | ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL); |
dd662667 | 877 | if (ufs->lower_mnt == NULL) |
3b7a9a24 | 878 | goto out_put_workdir; |
a78d9f0d MS |
879 | for (i = 0; i < numlower; i++) { |
880 | struct vfsmount *mnt = clone_private_mount(&stack[i]); | |
dd662667 | 881 | |
2f83fd8c | 882 | err = PTR_ERR(mnt); |
a78d9f0d MS |
883 | if (IS_ERR(mnt)) { |
884 | pr_err("overlayfs: failed to clone lowerpath\n"); | |
885 | goto out_put_lower_mnt; | |
886 | } | |
887 | /* | |
888 | * Make lower_mnt R/O. That way fchmod/fchown on lower file | |
889 | * will fail instead of modifying lower fs. | |
890 | */ | |
d719e8f2 | 891 | mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME; |
dd662667 | 892 | |
a78d9f0d MS |
893 | ufs->lower_mnt[ufs->numlower] = mnt; |
894 | ufs->numlower++; | |
895 | } | |
e9be9d5e | 896 | |
71cbad7e | 897 | /* If the upper fs is nonexistent, we mark overlayfs r/o too */ |
898 | if (!ufs->upper_mnt) | |
e9be9d5e MS |
899 | sb->s_flags |= MS_RDONLY; |
900 | ||
7c03b5d4 MS |
901 | if (remote) |
902 | sb->s_d_op = &ovl_reval_dentry_operations; | |
903 | else | |
904 | sb->s_d_op = &ovl_dentry_operations; | |
e9be9d5e | 905 | |
51f8f3c4 KK |
906 | ufs->creator_cred = cred = prepare_creds(); |
907 | if (!cred) | |
3fe6e52f AM |
908 | goto out_put_lower_mnt; |
909 | ||
51f8f3c4 KK |
910 | /* Never override disk quota limits or use reserved space */ |
911 | cap_lower(cred->cap_effective, CAP_SYS_RESOURCE); | |
912 | ||
e9be9d5e | 913 | err = -ENOMEM; |
a78d9f0d | 914 | oe = ovl_alloc_entry(numlower); |
3b7a9a24 | 915 | if (!oe) |
3fe6e52f | 916 | goto out_put_cred; |
e9be9d5e | 917 | |
655042cc VG |
918 | sb->s_magic = OVERLAYFS_SUPER_MAGIC; |
919 | sb->s_op = &ovl_super_operations; | |
920 | sb->s_xattr = ovl_xattr_handlers; | |
921 | sb->s_fs_info = ufs; | |
922 | sb->s_flags |= MS_POSIXACL | MS_NOREMOTELOCK; | |
923 | ||
ca4c8a3a | 924 | root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0)); |
e9be9d5e | 925 | if (!root_dentry) |
3b7a9a24 | 926 | goto out_free_oe; |
e9be9d5e MS |
927 | |
928 | mntput(upperpath.mnt); | |
a78d9f0d MS |
929 | for (i = 0; i < numlower; i++) |
930 | mntput(stack[i].mnt); | |
e9be9d5e | 931 | path_put(&workpath); |
a78d9f0d | 932 | kfree(lowertmp); |
e9be9d5e MS |
933 | |
934 | oe->__upperdentry = upperpath.dentry; | |
a78d9f0d MS |
935 | for (i = 0; i < numlower; i++) { |
936 | oe->lowerstack[i].dentry = stack[i].dentry; | |
937 | oe->lowerstack[i].mnt = ufs->lower_mnt[i]; | |
938 | } | |
0f95502a | 939 | kfree(stack); |
e9be9d5e MS |
940 | |
941 | root_dentry->d_fsdata = oe; | |
942 | ||
39b681f8 MS |
943 | realinode = d_inode(ovl_dentry_real(root_dentry)); |
944 | ovl_inode_init(d_inode(root_dentry), realinode, !!upperpath.dentry); | |
945 | ovl_copyattr(realinode, d_inode(root_dentry)); | |
ed06e069 | 946 | |
e9be9d5e | 947 | sb->s_root = root_dentry; |
e9be9d5e MS |
948 | |
949 | return 0; | |
950 | ||
3b7a9a24 MS |
951 | out_free_oe: |
952 | kfree(oe); | |
3fe6e52f AM |
953 | out_put_cred: |
954 | put_cred(ufs->creator_cred); | |
e9be9d5e | 955 | out_put_lower_mnt: |
dd662667 MS |
956 | for (i = 0; i < ufs->numlower; i++) |
957 | mntput(ufs->lower_mnt[i]); | |
958 | kfree(ufs->lower_mnt); | |
3b7a9a24 MS |
959 | out_put_workdir: |
960 | dput(ufs->workdir); | |
e9be9d5e | 961 | mntput(ufs->upper_mnt); |
e9be9d5e | 962 | out_put_lowerpath: |
a78d9f0d MS |
963 | for (i = 0; i < numlower; i++) |
964 | path_put(&stack[i]); | |
965 | kfree(stack); | |
966 | out_free_lowertmp: | |
967 | kfree(lowertmp); | |
3b7a9a24 MS |
968 | out_put_workpath: |
969 | path_put(&workpath); | |
e9be9d5e MS |
970 | out_put_upperpath: |
971 | path_put(&upperpath); | |
e9be9d5e | 972 | out_free_config: |
f45827e8 EZ |
973 | kfree(ufs->config.lowerdir); |
974 | kfree(ufs->config.upperdir); | |
975 | kfree(ufs->config.workdir); | |
976 | kfree(ufs); | |
e9be9d5e MS |
977 | out: |
978 | return err; | |
979 | } | |
980 | ||
981 | static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, | |
982 | const char *dev_name, void *raw_data) | |
983 | { | |
984 | return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); | |
985 | } | |
986 | ||
987 | static struct file_system_type ovl_fs_type = { | |
988 | .owner = THIS_MODULE, | |
ef94b186 | 989 | .name = "overlay", |
e9be9d5e MS |
990 | .mount = ovl_mount, |
991 | .kill_sb = kill_anon_super, | |
992 | }; | |
ef94b186 | 993 | MODULE_ALIAS_FS("overlay"); |
e9be9d5e MS |
994 | |
995 | static int __init ovl_init(void) | |
996 | { | |
997 | return register_filesystem(&ovl_fs_type); | |
998 | } | |
999 | ||
1000 | static void __exit ovl_exit(void) | |
1001 | { | |
1002 | unregister_filesystem(&ovl_fs_type); | |
1003 | } | |
1004 | ||
1005 | module_init(ovl_init); | |
1006 | module_exit(ovl_exit); |