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Commit | Line | Data |
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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 MS |
20 | #include "overlayfs.h" |
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 | ||
688ea0e5 MS |
31 | static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR); |
32 | module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644); | |
33 | MODULE_PARM_DESC(ovl_redirect_dir_def, | |
34 | "Default to on or off for the redirect_dir feature"); | |
e9be9d5e | 35 | |
438c84c2 MS |
36 | static bool ovl_redirect_always_follow = |
37 | IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW); | |
38 | module_param_named(redirect_always_follow, ovl_redirect_always_follow, | |
39 | bool, 0644); | |
40 | MODULE_PARM_DESC(ovl_redirect_always_follow, | |
41 | "Follow redirects even if redirect_dir feature is turned off"); | |
42 | ||
02bcd157 AG |
43 | static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX); |
44 | module_param_named(index, ovl_index_def, bool, 0644); | |
45 | MODULE_PARM_DESC(ovl_index_def, | |
46 | "Default to on or off for the inodes index feature"); | |
47 | ||
f168f109 AG |
48 | static bool ovl_nfs_export_def = IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT); |
49 | module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644); | |
50 | MODULE_PARM_DESC(ovl_nfs_export_def, | |
51 | "Default to on or off for the NFS export feature"); | |
52 | ||
4155c10a MS |
53 | static void ovl_entry_stack_free(struct ovl_entry *oe) |
54 | { | |
55 | unsigned int i; | |
56 | ||
57 | for (i = 0; i < oe->numlower; i++) | |
58 | dput(oe->lowerstack[i].dentry); | |
59 | } | |
60 | ||
e9be9d5e MS |
61 | static void ovl_dentry_release(struct dentry *dentry) |
62 | { | |
63 | struct ovl_entry *oe = dentry->d_fsdata; | |
64 | ||
65 | if (oe) { | |
4155c10a | 66 | ovl_entry_stack_free(oe); |
e9be9d5e MS |
67 | kfree_rcu(oe, rcu); |
68 | } | |
69 | } | |
70 | ||
b0990fbb AG |
71 | static int ovl_check_append_only(struct inode *inode, int flag) |
72 | { | |
73 | /* | |
74 | * This test was moot in vfs may_open() because overlay inode does | |
75 | * not have the S_APPEND flag, so re-check on real upper inode | |
76 | */ | |
77 | if (IS_APPEND(inode)) { | |
78 | if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) | |
79 | return -EPERM; | |
80 | if (flag & O_TRUNC) | |
81 | return -EPERM; | |
82 | } | |
83 | ||
84 | return 0; | |
85 | } | |
86 | ||
2d902671 MS |
87 | static struct dentry *ovl_d_real(struct dentry *dentry, |
88 | const struct inode *inode, | |
495e6429 | 89 | unsigned int open_flags, unsigned int flags) |
d101a125 MS |
90 | { |
91 | struct dentry *real; | |
b0990fbb | 92 | int err; |
d101a125 | 93 | |
cd91304e MS |
94 | if (flags & D_REAL_UPPER) |
95 | return ovl_dentry_upper(dentry); | |
96 | ||
ca4c8a3a | 97 | if (!d_is_reg(dentry)) { |
d101a125 MS |
98 | if (!inode || inode == d_inode(dentry)) |
99 | return dentry; | |
100 | goto bug; | |
101 | } | |
102 | ||
2d902671 | 103 | if (open_flags) { |
b0990fbb | 104 | err = ovl_open_maybe_copy_up(dentry, open_flags); |
2d902671 MS |
105 | if (err) |
106 | return ERR_PTR(err); | |
107 | } | |
108 | ||
d101a125 | 109 | real = ovl_dentry_upper(dentry); |
b0990fbb AG |
110 | if (real && (!inode || inode == d_inode(real))) { |
111 | if (!inode) { | |
112 | err = ovl_check_append_only(d_inode(real), open_flags); | |
113 | if (err) | |
114 | return ERR_PTR(err); | |
115 | } | |
d101a125 | 116 | return real; |
b0990fbb | 117 | } |
d101a125 MS |
118 | |
119 | real = ovl_dentry_lower(dentry); | |
120 | if (!real) | |
121 | goto bug; | |
122 | ||
c4fcfc16 | 123 | /* Handle recursion */ |
495e6429 | 124 | real = d_real(real, inode, open_flags, 0); |
c4fcfc16 | 125 | |
d101a125 MS |
126 | if (!inode || inode == d_inode(real)) |
127 | return real; | |
d101a125 | 128 | bug: |
656189d2 | 129 | WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry, |
d101a125 MS |
130 | inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0); |
131 | return dentry; | |
132 | } | |
133 | ||
7c03b5d4 MS |
134 | static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) |
135 | { | |
136 | struct ovl_entry *oe = dentry->d_fsdata; | |
137 | unsigned int i; | |
138 | int ret = 1; | |
139 | ||
140 | for (i = 0; i < oe->numlower; i++) { | |
141 | struct dentry *d = oe->lowerstack[i].dentry; | |
142 | ||
143 | if (d->d_flags & DCACHE_OP_REVALIDATE) { | |
144 | ret = d->d_op->d_revalidate(d, flags); | |
145 | if (ret < 0) | |
146 | return ret; | |
147 | if (!ret) { | |
148 | if (!(flags & LOOKUP_RCU)) | |
149 | d_invalidate(d); | |
150 | return -ESTALE; | |
151 | } | |
152 | } | |
153 | } | |
154 | return 1; | |
155 | } | |
156 | ||
157 | static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) | |
158 | { | |
159 | struct ovl_entry *oe = dentry->d_fsdata; | |
160 | unsigned int i; | |
161 | int ret = 1; | |
162 | ||
163 | for (i = 0; i < oe->numlower; i++) { | |
164 | struct dentry *d = oe->lowerstack[i].dentry; | |
165 | ||
166 | if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) { | |
167 | ret = d->d_op->d_weak_revalidate(d, flags); | |
168 | if (ret <= 0) | |
169 | break; | |
170 | } | |
171 | } | |
172 | return ret; | |
173 | } | |
174 | ||
e9be9d5e MS |
175 | static const struct dentry_operations ovl_dentry_operations = { |
176 | .d_release = ovl_dentry_release, | |
d101a125 | 177 | .d_real = ovl_d_real, |
e9be9d5e MS |
178 | }; |
179 | ||
7c03b5d4 MS |
180 | static const struct dentry_operations ovl_reval_dentry_operations = { |
181 | .d_release = ovl_dentry_release, | |
d101a125 | 182 | .d_real = ovl_d_real, |
7c03b5d4 MS |
183 | .d_revalidate = ovl_dentry_revalidate, |
184 | .d_weak_revalidate = ovl_dentry_weak_revalidate, | |
185 | }; | |
186 | ||
13cf199d AG |
187 | static struct kmem_cache *ovl_inode_cachep; |
188 | ||
189 | static struct inode *ovl_alloc_inode(struct super_block *sb) | |
190 | { | |
191 | struct ovl_inode *oi = kmem_cache_alloc(ovl_inode_cachep, GFP_KERNEL); | |
192 | ||
b3885bd6 HN |
193 | if (!oi) |
194 | return NULL; | |
195 | ||
04a01ac7 | 196 | oi->cache = NULL; |
cf31c463 | 197 | oi->redirect = NULL; |
04a01ac7 | 198 | oi->version = 0; |
13c72075 | 199 | oi->flags = 0; |
09d8b586 | 200 | oi->__upperdentry = NULL; |
25b7713a | 201 | oi->lower = NULL; |
a015dafc | 202 | mutex_init(&oi->lock); |
25b7713a | 203 | |
13cf199d AG |
204 | return &oi->vfs_inode; |
205 | } | |
206 | ||
207 | static void ovl_i_callback(struct rcu_head *head) | |
208 | { | |
209 | struct inode *inode = container_of(head, struct inode, i_rcu); | |
210 | ||
211 | kmem_cache_free(ovl_inode_cachep, OVL_I(inode)); | |
212 | } | |
213 | ||
214 | static void ovl_destroy_inode(struct inode *inode) | |
215 | { | |
09d8b586 MS |
216 | struct ovl_inode *oi = OVL_I(inode); |
217 | ||
218 | dput(oi->__upperdentry); | |
31747eda | 219 | iput(oi->lower); |
cf31c463 | 220 | kfree(oi->redirect); |
4edb83bb | 221 | ovl_dir_cache_free(inode); |
a015dafc | 222 | mutex_destroy(&oi->lock); |
09d8b586 | 223 | |
13cf199d AG |
224 | call_rcu(&inode->i_rcu, ovl_i_callback); |
225 | } | |
226 | ||
ad204488 | 227 | static void ovl_free_fs(struct ovl_fs *ofs) |
e9be9d5e | 228 | { |
dd662667 | 229 | unsigned i; |
e9be9d5e | 230 | |
ad204488 MS |
231 | dput(ofs->indexdir); |
232 | dput(ofs->workdir); | |
233 | if (ofs->workdir_locked) | |
234 | ovl_inuse_unlock(ofs->workbasedir); | |
235 | dput(ofs->workbasedir); | |
236 | if (ofs->upperdir_locked) | |
237 | ovl_inuse_unlock(ofs->upper_mnt->mnt_root); | |
238 | mntput(ofs->upper_mnt); | |
239 | for (i = 0; i < ofs->numlower; i++) { | |
240 | mntput(ofs->lower_layers[i].mnt); | |
241 | free_anon_bdev(ofs->lower_layers[i].pseudo_dev); | |
2a9c6d06 | 242 | } |
ad204488 MS |
243 | kfree(ofs->lower_layers); |
244 | ||
245 | kfree(ofs->config.lowerdir); | |
246 | kfree(ofs->config.upperdir); | |
247 | kfree(ofs->config.workdir); | |
438c84c2 | 248 | kfree(ofs->config.redirect_mode); |
ad204488 MS |
249 | if (ofs->creator_cred) |
250 | put_cred(ofs->creator_cred); | |
251 | kfree(ofs); | |
e9be9d5e MS |
252 | } |
253 | ||
a9075cdb MS |
254 | static void ovl_put_super(struct super_block *sb) |
255 | { | |
256 | struct ovl_fs *ofs = sb->s_fs_info; | |
257 | ||
258 | ovl_free_fs(ofs); | |
259 | } | |
260 | ||
e8d4bfe3 | 261 | /* Sync real dirty inodes in upper filesystem (if it exists) */ |
e593b2bf AG |
262 | static int ovl_sync_fs(struct super_block *sb, int wait) |
263 | { | |
ad204488 | 264 | struct ovl_fs *ofs = sb->s_fs_info; |
e593b2bf AG |
265 | struct super_block *upper_sb; |
266 | int ret; | |
267 | ||
ad204488 | 268 | if (!ofs->upper_mnt) |
e593b2bf | 269 | return 0; |
e8d4bfe3 CX |
270 | |
271 | /* | |
272 | * If this is a sync(2) call or an emergency sync, all the super blocks | |
273 | * will be iterated, including upper_sb, so no need to do anything. | |
274 | * | |
275 | * If this is a syncfs(2) call, then we do need to call | |
276 | * sync_filesystem() on upper_sb, but enough if we do it when being | |
277 | * called with wait == 1. | |
278 | */ | |
279 | if (!wait) | |
e593b2bf AG |
280 | return 0; |
281 | ||
e8d4bfe3 CX |
282 | upper_sb = ofs->upper_mnt->mnt_sb; |
283 | ||
e593b2bf | 284 | down_read(&upper_sb->s_umount); |
e8d4bfe3 | 285 | ret = sync_filesystem(upper_sb); |
e593b2bf | 286 | up_read(&upper_sb->s_umount); |
e8d4bfe3 | 287 | |
e593b2bf AG |
288 | return ret; |
289 | } | |
290 | ||
cc259639 AW |
291 | /** |
292 | * ovl_statfs | |
293 | * @sb: The overlayfs super block | |
294 | * @buf: The struct kstatfs to fill in with stats | |
295 | * | |
296 | * Get the filesystem statistics. As writes always target the upper layer | |
4ebc5818 | 297 | * filesystem pass the statfs to the upper filesystem (if it exists) |
cc259639 AW |
298 | */ |
299 | static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) | |
300 | { | |
301 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
302 | struct dentry *root_dentry = dentry->d_sb->s_root; | |
303 | struct path path; | |
304 | int err; | |
305 | ||
4ebc5818 | 306 | ovl_path_real(root_dentry, &path); |
cc259639 AW |
307 | |
308 | err = vfs_statfs(&path, buf); | |
309 | if (!err) { | |
6b2d5fe4 | 310 | buf->f_namelen = ofs->namelen; |
cc259639 AW |
311 | buf->f_type = OVERLAYFS_SUPER_MAGIC; |
312 | } | |
313 | ||
314 | return err; | |
315 | } | |
316 | ||
02bcd157 | 317 | /* Will this overlay be forced to mount/remount ro? */ |
ad204488 | 318 | static bool ovl_force_readonly(struct ovl_fs *ofs) |
02bcd157 | 319 | { |
ad204488 | 320 | return (!ofs->upper_mnt || !ofs->workdir); |
02bcd157 AG |
321 | } |
322 | ||
438c84c2 MS |
323 | static const char *ovl_redirect_mode_def(void) |
324 | { | |
325 | return ovl_redirect_dir_def ? "on" : "off"; | |
326 | } | |
327 | ||
f45827e8 EZ |
328 | /** |
329 | * ovl_show_options | |
330 | * | |
331 | * Prints the mount options for a given superblock. | |
332 | * Returns zero; does not fail. | |
333 | */ | |
334 | static int ovl_show_options(struct seq_file *m, struct dentry *dentry) | |
335 | { | |
336 | struct super_block *sb = dentry->d_sb; | |
ad204488 | 337 | struct ovl_fs *ofs = sb->s_fs_info; |
f45827e8 | 338 | |
ad204488 MS |
339 | seq_show_option(m, "lowerdir", ofs->config.lowerdir); |
340 | if (ofs->config.upperdir) { | |
341 | seq_show_option(m, "upperdir", ofs->config.upperdir); | |
342 | seq_show_option(m, "workdir", ofs->config.workdir); | |
53a08cb9 | 343 | } |
ad204488 | 344 | if (ofs->config.default_permissions) |
8d3095f4 | 345 | seq_puts(m, ",default_permissions"); |
438c84c2 MS |
346 | if (strcmp(ofs->config.redirect_mode, ovl_redirect_mode_def()) != 0) |
347 | seq_printf(m, ",redirect_dir=%s", ofs->config.redirect_mode); | |
ad204488 | 348 | if (ofs->config.index != ovl_index_def) |
438c84c2 | 349 | seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off"); |
f168f109 AG |
350 | if (ofs->config.nfs_export != ovl_nfs_export_def) |
351 | seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ? | |
352 | "on" : "off"); | |
f45827e8 EZ |
353 | return 0; |
354 | } | |
355 | ||
3cdf6fe9 SL |
356 | static int ovl_remount(struct super_block *sb, int *flags, char *data) |
357 | { | |
ad204488 | 358 | struct ovl_fs *ofs = sb->s_fs_info; |
3cdf6fe9 | 359 | |
1751e8a6 | 360 | if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs)) |
3cdf6fe9 SL |
361 | return -EROFS; |
362 | ||
363 | return 0; | |
364 | } | |
365 | ||
e9be9d5e | 366 | static const struct super_operations ovl_super_operations = { |
13cf199d AG |
367 | .alloc_inode = ovl_alloc_inode, |
368 | .destroy_inode = ovl_destroy_inode, | |
369 | .drop_inode = generic_delete_inode, | |
e9be9d5e | 370 | .put_super = ovl_put_super, |
e593b2bf | 371 | .sync_fs = ovl_sync_fs, |
cc259639 | 372 | .statfs = ovl_statfs, |
f45827e8 | 373 | .show_options = ovl_show_options, |
3cdf6fe9 | 374 | .remount_fs = ovl_remount, |
e9be9d5e MS |
375 | }; |
376 | ||
377 | enum { | |
378 | OPT_LOWERDIR, | |
379 | OPT_UPPERDIR, | |
380 | OPT_WORKDIR, | |
8d3095f4 | 381 | OPT_DEFAULT_PERMISSIONS, |
438c84c2 | 382 | OPT_REDIRECT_DIR, |
02bcd157 AG |
383 | OPT_INDEX_ON, |
384 | OPT_INDEX_OFF, | |
f168f109 AG |
385 | OPT_NFS_EXPORT_ON, |
386 | OPT_NFS_EXPORT_OFF, | |
e9be9d5e MS |
387 | OPT_ERR, |
388 | }; | |
389 | ||
390 | static const match_table_t ovl_tokens = { | |
391 | {OPT_LOWERDIR, "lowerdir=%s"}, | |
392 | {OPT_UPPERDIR, "upperdir=%s"}, | |
393 | {OPT_WORKDIR, "workdir=%s"}, | |
8d3095f4 | 394 | {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, |
438c84c2 | 395 | {OPT_REDIRECT_DIR, "redirect_dir=%s"}, |
02bcd157 AG |
396 | {OPT_INDEX_ON, "index=on"}, |
397 | {OPT_INDEX_OFF, "index=off"}, | |
f168f109 AG |
398 | {OPT_NFS_EXPORT_ON, "nfs_export=on"}, |
399 | {OPT_NFS_EXPORT_OFF, "nfs_export=off"}, | |
e9be9d5e MS |
400 | {OPT_ERR, NULL} |
401 | }; | |
402 | ||
91c77947 MS |
403 | static char *ovl_next_opt(char **s) |
404 | { | |
405 | char *sbegin = *s; | |
406 | char *p; | |
407 | ||
408 | if (sbegin == NULL) | |
409 | return NULL; | |
410 | ||
411 | for (p = sbegin; *p; p++) { | |
412 | if (*p == '\\') { | |
413 | p++; | |
414 | if (!*p) | |
415 | break; | |
416 | } else if (*p == ',') { | |
417 | *p = '\0'; | |
418 | *s = p + 1; | |
419 | return sbegin; | |
420 | } | |
421 | } | |
422 | *s = NULL; | |
423 | return sbegin; | |
424 | } | |
425 | ||
438c84c2 MS |
426 | static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode) |
427 | { | |
428 | if (strcmp(mode, "on") == 0) { | |
429 | config->redirect_dir = true; | |
430 | /* | |
431 | * Does not make sense to have redirect creation without | |
432 | * redirect following. | |
433 | */ | |
434 | config->redirect_follow = true; | |
435 | } else if (strcmp(mode, "follow") == 0) { | |
436 | config->redirect_follow = true; | |
437 | } else if (strcmp(mode, "off") == 0) { | |
438 | if (ovl_redirect_always_follow) | |
439 | config->redirect_follow = true; | |
440 | } else if (strcmp(mode, "nofollow") != 0) { | |
441 | pr_err("overlayfs: bad mount option \"redirect_dir=%s\"\n", | |
442 | mode); | |
443 | return -EINVAL; | |
444 | } | |
445 | ||
446 | return 0; | |
447 | } | |
448 | ||
e9be9d5e MS |
449 | static int ovl_parse_opt(char *opt, struct ovl_config *config) |
450 | { | |
451 | char *p; | |
452 | ||
438c84c2 MS |
453 | config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL); |
454 | if (!config->redirect_mode) | |
455 | return -ENOMEM; | |
456 | ||
91c77947 | 457 | while ((p = ovl_next_opt(&opt)) != NULL) { |
e9be9d5e MS |
458 | int token; |
459 | substring_t args[MAX_OPT_ARGS]; | |
460 | ||
461 | if (!*p) | |
462 | continue; | |
463 | ||
464 | token = match_token(p, ovl_tokens, args); | |
465 | switch (token) { | |
466 | case OPT_UPPERDIR: | |
467 | kfree(config->upperdir); | |
468 | config->upperdir = match_strdup(&args[0]); | |
469 | if (!config->upperdir) | |
470 | return -ENOMEM; | |
471 | break; | |
472 | ||
473 | case OPT_LOWERDIR: | |
474 | kfree(config->lowerdir); | |
475 | config->lowerdir = match_strdup(&args[0]); | |
476 | if (!config->lowerdir) | |
477 | return -ENOMEM; | |
478 | break; | |
479 | ||
480 | case OPT_WORKDIR: | |
481 | kfree(config->workdir); | |
482 | config->workdir = match_strdup(&args[0]); | |
483 | if (!config->workdir) | |
484 | return -ENOMEM; | |
485 | break; | |
486 | ||
8d3095f4 MS |
487 | case OPT_DEFAULT_PERMISSIONS: |
488 | config->default_permissions = true; | |
489 | break; | |
490 | ||
438c84c2 MS |
491 | case OPT_REDIRECT_DIR: |
492 | kfree(config->redirect_mode); | |
493 | config->redirect_mode = match_strdup(&args[0]); | |
494 | if (!config->redirect_mode) | |
495 | return -ENOMEM; | |
a6c60655 MS |
496 | break; |
497 | ||
02bcd157 AG |
498 | case OPT_INDEX_ON: |
499 | config->index = true; | |
500 | break; | |
501 | ||
502 | case OPT_INDEX_OFF: | |
503 | config->index = false; | |
504 | break; | |
505 | ||
f168f109 AG |
506 | case OPT_NFS_EXPORT_ON: |
507 | config->nfs_export = true; | |
508 | break; | |
509 | ||
510 | case OPT_NFS_EXPORT_OFF: | |
511 | config->nfs_export = false; | |
512 | break; | |
513 | ||
e9be9d5e | 514 | default: |
bead55ef | 515 | pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p); |
e9be9d5e MS |
516 | return -EINVAL; |
517 | } | |
518 | } | |
71cbad7e | 519 | |
520 | /* Workdir is useless in non-upper mount */ | |
521 | if (!config->upperdir && config->workdir) { | |
522 | pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n", | |
523 | config->workdir); | |
524 | kfree(config->workdir); | |
525 | config->workdir = NULL; | |
526 | } | |
527 | ||
438c84c2 | 528 | return ovl_parse_redirect_mode(config, config->redirect_mode); |
e9be9d5e MS |
529 | } |
530 | ||
531 | #define OVL_WORKDIR_NAME "work" | |
02bcd157 | 532 | #define OVL_INDEXDIR_NAME "index" |
e9be9d5e | 533 | |
ad204488 | 534 | static struct dentry *ovl_workdir_create(struct ovl_fs *ofs, |
6b8aa129 | 535 | const char *name, bool persist) |
e9be9d5e | 536 | { |
ad204488 MS |
537 | struct inode *dir = ofs->workbasedir->d_inode; |
538 | struct vfsmount *mnt = ofs->upper_mnt; | |
e9be9d5e MS |
539 | struct dentry *work; |
540 | int err; | |
541 | bool retried = false; | |
6b8aa129 | 542 | bool locked = false; |
e9be9d5e | 543 | |
5955102c | 544 | inode_lock_nested(dir, I_MUTEX_PARENT); |
6b8aa129 AG |
545 | locked = true; |
546 | ||
e9be9d5e | 547 | retry: |
ad204488 | 548 | work = lookup_one_len(name, ofs->workbasedir, strlen(name)); |
e9be9d5e MS |
549 | |
550 | if (!IS_ERR(work)) { | |
c11b9fdd MS |
551 | struct iattr attr = { |
552 | .ia_valid = ATTR_MODE, | |
32a3d848 | 553 | .ia_mode = S_IFDIR | 0, |
c11b9fdd | 554 | }; |
e9be9d5e MS |
555 | |
556 | if (work->d_inode) { | |
557 | err = -EEXIST; | |
558 | if (retried) | |
559 | goto out_dput; | |
560 | ||
6b8aa129 AG |
561 | if (persist) |
562 | goto out_unlock; | |
563 | ||
e9be9d5e | 564 | retried = true; |
eea2fb48 | 565 | ovl_workdir_cleanup(dir, mnt, work, 0); |
e9be9d5e MS |
566 | dput(work); |
567 | goto retry; | |
568 | } | |
569 | ||
32a3d848 AV |
570 | err = ovl_create_real(dir, work, |
571 | &(struct cattr){.mode = S_IFDIR | 0}, | |
572 | NULL, true); | |
e9be9d5e MS |
573 | if (err) |
574 | goto out_dput; | |
c11b9fdd | 575 | |
cb348edb MS |
576 | /* |
577 | * Try to remove POSIX ACL xattrs from workdir. We are good if: | |
578 | * | |
579 | * a) success (there was a POSIX ACL xattr and was removed) | |
580 | * b) -ENODATA (there was no POSIX ACL xattr) | |
581 | * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported) | |
582 | * | |
583 | * There are various other error values that could effectively | |
584 | * mean that the xattr doesn't exist (e.g. -ERANGE is returned | |
585 | * if the xattr name is too long), but the set of filesystems | |
586 | * allowed as upper are limited to "normal" ones, where checking | |
587 | * for the above two errors is sufficient. | |
588 | */ | |
c11b9fdd | 589 | err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT); |
e1ff3dd1 | 590 | if (err && err != -ENODATA && err != -EOPNOTSUPP) |
c11b9fdd MS |
591 | goto out_dput; |
592 | ||
593 | err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_ACCESS); | |
e1ff3dd1 | 594 | if (err && err != -ENODATA && err != -EOPNOTSUPP) |
c11b9fdd MS |
595 | goto out_dput; |
596 | ||
597 | /* Clear any inherited mode bits */ | |
598 | inode_lock(work->d_inode); | |
599 | err = notify_change(work, &attr, NULL); | |
600 | inode_unlock(work->d_inode); | |
601 | if (err) | |
602 | goto out_dput; | |
6b8aa129 AG |
603 | } else { |
604 | err = PTR_ERR(work); | |
605 | goto out_err; | |
e9be9d5e MS |
606 | } |
607 | out_unlock: | |
6b8aa129 AG |
608 | if (locked) |
609 | inode_unlock(dir); | |
e9be9d5e MS |
610 | |
611 | return work; | |
612 | ||
613 | out_dput: | |
614 | dput(work); | |
6b8aa129 AG |
615 | out_err: |
616 | pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n", | |
ad204488 | 617 | ofs->config.workdir, name, -err); |
6b8aa129 | 618 | work = NULL; |
e9be9d5e MS |
619 | goto out_unlock; |
620 | } | |
621 | ||
91c77947 MS |
622 | static void ovl_unescape(char *s) |
623 | { | |
624 | char *d = s; | |
625 | ||
626 | for (;; s++, d++) { | |
627 | if (*s == '\\') | |
628 | s++; | |
629 | *d = *s; | |
630 | if (!*s) | |
631 | break; | |
632 | } | |
633 | } | |
634 | ||
ab508822 MS |
635 | static int ovl_mount_dir_noesc(const char *name, struct path *path) |
636 | { | |
a78d9f0d | 637 | int err = -EINVAL; |
ab508822 | 638 | |
a78d9f0d MS |
639 | if (!*name) { |
640 | pr_err("overlayfs: empty lowerdir\n"); | |
641 | goto out; | |
642 | } | |
ab508822 MS |
643 | err = kern_path(name, LOOKUP_FOLLOW, path); |
644 | if (err) { | |
645 | pr_err("overlayfs: failed to resolve '%s': %i\n", name, err); | |
646 | goto out; | |
647 | } | |
648 | err = -EINVAL; | |
7c03b5d4 | 649 | if (ovl_dentry_weird(path->dentry)) { |
ab508822 MS |
650 | pr_err("overlayfs: filesystem on '%s' not supported\n", name); |
651 | goto out_put; | |
652 | } | |
2b8c30e9 | 653 | if (!d_is_dir(path->dentry)) { |
ab508822 MS |
654 | pr_err("overlayfs: '%s' not a directory\n", name); |
655 | goto out_put; | |
656 | } | |
657 | return 0; | |
658 | ||
659 | out_put: | |
8aafcb59 | 660 | path_put_init(path); |
ab508822 MS |
661 | out: |
662 | return err; | |
663 | } | |
664 | ||
665 | static int ovl_mount_dir(const char *name, struct path *path) | |
666 | { | |
667 | int err = -ENOMEM; | |
668 | char *tmp = kstrdup(name, GFP_KERNEL); | |
669 | ||
670 | if (tmp) { | |
671 | ovl_unescape(tmp); | |
672 | err = ovl_mount_dir_noesc(tmp, path); | |
7c03b5d4 MS |
673 | |
674 | if (!err) | |
675 | if (ovl_dentry_remote(path->dentry)) { | |
676 | pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n", | |
677 | tmp); | |
8aafcb59 | 678 | path_put_init(path); |
7c03b5d4 MS |
679 | err = -EINVAL; |
680 | } | |
ab508822 MS |
681 | kfree(tmp); |
682 | } | |
683 | return err; | |
684 | } | |
685 | ||
6b2d5fe4 MS |
686 | static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs, |
687 | const char *name) | |
ab508822 | 688 | { |
ab508822 | 689 | struct kstatfs statfs; |
6b2d5fe4 MS |
690 | int err = vfs_statfs(path, &statfs); |
691 | ||
692 | if (err) | |
693 | pr_err("overlayfs: statfs failed on '%s'\n", name); | |
694 | else | |
695 | ofs->namelen = max(ofs->namelen, statfs.f_namelen); | |
696 | ||
697 | return err; | |
698 | } | |
699 | ||
700 | static int ovl_lower_dir(const char *name, struct path *path, | |
701 | struct ovl_fs *ofs, int *stack_depth, bool *remote) | |
702 | { | |
703 | int err; | |
ab508822 | 704 | |
a78d9f0d | 705 | err = ovl_mount_dir_noesc(name, path); |
ab508822 MS |
706 | if (err) |
707 | goto out; | |
708 | ||
6b2d5fe4 MS |
709 | err = ovl_check_namelen(path, ofs, name); |
710 | if (err) | |
ab508822 | 711 | goto out_put; |
6b2d5fe4 | 712 | |
ab508822 MS |
713 | *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); |
714 | ||
7c03b5d4 MS |
715 | if (ovl_dentry_remote(path->dentry)) |
716 | *remote = true; | |
717 | ||
02bcd157 | 718 | /* |
f168f109 AG |
719 | * The inodes index feature and NFS export need to encode and decode |
720 | * file handles, so they require that all layers support them. | |
02bcd157 | 721 | */ |
f168f109 AG |
722 | if ((ofs->config.nfs_export || |
723 | (ofs->config.index && ofs->config.upperdir)) && | |
972d0093 | 724 | !ovl_can_decode_fh(path->dentry->d_sb)) { |
02bcd157 | 725 | ofs->config.index = false; |
f168f109 AG |
726 | ofs->config.nfs_export = false; |
727 | pr_warn("overlayfs: fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n", | |
728 | name); | |
02bcd157 AG |
729 | } |
730 | ||
ab508822 MS |
731 | return 0; |
732 | ||
733 | out_put: | |
8aafcb59 | 734 | path_put_init(path); |
ab508822 MS |
735 | out: |
736 | return err; | |
737 | } | |
738 | ||
e9be9d5e MS |
739 | /* Workdir should not be subdir of upperdir and vice versa */ |
740 | static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir) | |
741 | { | |
742 | bool ok = false; | |
743 | ||
744 | if (workdir != upperdir) { | |
745 | ok = (lock_rename(workdir, upperdir) == NULL); | |
746 | unlock_rename(workdir, upperdir); | |
747 | } | |
748 | return ok; | |
749 | } | |
750 | ||
a78d9f0d MS |
751 | static unsigned int ovl_split_lowerdirs(char *str) |
752 | { | |
753 | unsigned int ctr = 1; | |
754 | char *s, *d; | |
755 | ||
756 | for (s = d = str;; s++, d++) { | |
757 | if (*s == '\\') { | |
758 | s++; | |
759 | } else if (*s == ':') { | |
760 | *d = '\0'; | |
761 | ctr++; | |
762 | continue; | |
763 | } | |
764 | *d = *s; | |
765 | if (!*s) | |
766 | break; | |
767 | } | |
768 | return ctr; | |
769 | } | |
770 | ||
0eb45fc3 AG |
771 | static int __maybe_unused |
772 | ovl_posix_acl_xattr_get(const struct xattr_handler *handler, | |
773 | struct dentry *dentry, struct inode *inode, | |
774 | const char *name, void *buffer, size_t size) | |
775 | { | |
1d88f183 | 776 | return ovl_xattr_get(dentry, inode, handler->name, buffer, size); |
0eb45fc3 AG |
777 | } |
778 | ||
0c97be22 AG |
779 | static int __maybe_unused |
780 | ovl_posix_acl_xattr_set(const struct xattr_handler *handler, | |
781 | struct dentry *dentry, struct inode *inode, | |
782 | const char *name, const void *value, | |
783 | size_t size, int flags) | |
d837a49b MS |
784 | { |
785 | struct dentry *workdir = ovl_workdir(dentry); | |
09d8b586 | 786 | struct inode *realinode = ovl_inode_real(inode); |
d837a49b MS |
787 | struct posix_acl *acl = NULL; |
788 | int err; | |
789 | ||
790 | /* Check that everything is OK before copy-up */ | |
791 | if (value) { | |
792 | acl = posix_acl_from_xattr(&init_user_ns, value, size); | |
793 | if (IS_ERR(acl)) | |
794 | return PTR_ERR(acl); | |
795 | } | |
796 | err = -EOPNOTSUPP; | |
797 | if (!IS_POSIXACL(d_inode(workdir))) | |
798 | goto out_acl_release; | |
799 | if (!realinode->i_op->set_acl) | |
800 | goto out_acl_release; | |
801 | if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) { | |
802 | err = acl ? -EACCES : 0; | |
803 | goto out_acl_release; | |
804 | } | |
805 | err = -EPERM; | |
806 | if (!inode_owner_or_capable(inode)) | |
807 | goto out_acl_release; | |
808 | ||
809 | posix_acl_release(acl); | |
810 | ||
fd3220d3 MS |
811 | /* |
812 | * Check if sgid bit needs to be cleared (actual setacl operation will | |
813 | * be done with mounter's capabilities and so that won't do it for us). | |
814 | */ | |
815 | if (unlikely(inode->i_mode & S_ISGID) && | |
816 | handler->flags == ACL_TYPE_ACCESS && | |
817 | !in_group_p(inode->i_gid) && | |
818 | !capable_wrt_inode_uidgid(inode, CAP_FSETID)) { | |
819 | struct iattr iattr = { .ia_valid = ATTR_KILL_SGID }; | |
820 | ||
821 | err = ovl_setattr(dentry, &iattr); | |
822 | if (err) | |
823 | return err; | |
824 | } | |
825 | ||
1d88f183 | 826 | err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags); |
ce31513a | 827 | if (!err) |
09d8b586 | 828 | ovl_copyattr(ovl_inode_real(inode), inode); |
ce31513a MS |
829 | |
830 | return err; | |
d837a49b MS |
831 | |
832 | out_acl_release: | |
833 | posix_acl_release(acl); | |
834 | return err; | |
835 | } | |
836 | ||
0eb45fc3 AG |
837 | static int ovl_own_xattr_get(const struct xattr_handler *handler, |
838 | struct dentry *dentry, struct inode *inode, | |
839 | const char *name, void *buffer, size_t size) | |
840 | { | |
48fab5d7 | 841 | return -EOPNOTSUPP; |
0eb45fc3 AG |
842 | } |
843 | ||
d837a49b MS |
844 | static int ovl_own_xattr_set(const struct xattr_handler *handler, |
845 | struct dentry *dentry, struct inode *inode, | |
846 | const char *name, const void *value, | |
847 | size_t size, int flags) | |
848 | { | |
48fab5d7 | 849 | return -EOPNOTSUPP; |
d837a49b MS |
850 | } |
851 | ||
0eb45fc3 AG |
852 | static int ovl_other_xattr_get(const struct xattr_handler *handler, |
853 | struct dentry *dentry, struct inode *inode, | |
854 | const char *name, void *buffer, size_t size) | |
855 | { | |
1d88f183 | 856 | return ovl_xattr_get(dentry, inode, name, buffer, size); |
0eb45fc3 AG |
857 | } |
858 | ||
0e585ccc AG |
859 | static int ovl_other_xattr_set(const struct xattr_handler *handler, |
860 | struct dentry *dentry, struct inode *inode, | |
861 | const char *name, const void *value, | |
862 | size_t size, int flags) | |
863 | { | |
1d88f183 | 864 | return ovl_xattr_set(dentry, inode, name, value, size, flags); |
0e585ccc AG |
865 | } |
866 | ||
0c97be22 AG |
867 | static const struct xattr_handler __maybe_unused |
868 | ovl_posix_acl_access_xattr_handler = { | |
d837a49b MS |
869 | .name = XATTR_NAME_POSIX_ACL_ACCESS, |
870 | .flags = ACL_TYPE_ACCESS, | |
0eb45fc3 | 871 | .get = ovl_posix_acl_xattr_get, |
d837a49b MS |
872 | .set = ovl_posix_acl_xattr_set, |
873 | }; | |
874 | ||
0c97be22 AG |
875 | static const struct xattr_handler __maybe_unused |
876 | ovl_posix_acl_default_xattr_handler = { | |
d837a49b MS |
877 | .name = XATTR_NAME_POSIX_ACL_DEFAULT, |
878 | .flags = ACL_TYPE_DEFAULT, | |
0eb45fc3 | 879 | .get = ovl_posix_acl_xattr_get, |
d837a49b MS |
880 | .set = ovl_posix_acl_xattr_set, |
881 | }; | |
882 | ||
883 | static const struct xattr_handler ovl_own_xattr_handler = { | |
884 | .prefix = OVL_XATTR_PREFIX, | |
0eb45fc3 | 885 | .get = ovl_own_xattr_get, |
d837a49b MS |
886 | .set = ovl_own_xattr_set, |
887 | }; | |
888 | ||
889 | static const struct xattr_handler ovl_other_xattr_handler = { | |
890 | .prefix = "", /* catch all */ | |
0eb45fc3 | 891 | .get = ovl_other_xattr_get, |
d837a49b MS |
892 | .set = ovl_other_xattr_set, |
893 | }; | |
894 | ||
895 | static const struct xattr_handler *ovl_xattr_handlers[] = { | |
0c97be22 | 896 | #ifdef CONFIG_FS_POSIX_ACL |
d837a49b MS |
897 | &ovl_posix_acl_access_xattr_handler, |
898 | &ovl_posix_acl_default_xattr_handler, | |
0c97be22 | 899 | #endif |
d837a49b MS |
900 | &ovl_own_xattr_handler, |
901 | &ovl_other_xattr_handler, | |
902 | NULL | |
903 | }; | |
904 | ||
ad204488 | 905 | static int ovl_get_upper(struct ovl_fs *ofs, struct path *upperpath) |
6ee8acf0 | 906 | { |
5064975e | 907 | struct vfsmount *upper_mnt; |
6ee8acf0 MS |
908 | int err; |
909 | ||
ad204488 | 910 | err = ovl_mount_dir(ofs->config.upperdir, upperpath); |
6ee8acf0 MS |
911 | if (err) |
912 | goto out; | |
913 | ||
914 | /* Upper fs should not be r/o */ | |
915 | if (sb_rdonly(upperpath->mnt->mnt_sb)) { | |
916 | pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n"); | |
917 | err = -EINVAL; | |
918 | goto out; | |
919 | } | |
920 | ||
ad204488 | 921 | err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir); |
6ee8acf0 MS |
922 | if (err) |
923 | goto out; | |
924 | ||
925 | err = -EBUSY; | |
926 | if (ovl_inuse_trylock(upperpath->dentry)) { | |
ad204488 MS |
927 | ofs->upperdir_locked = true; |
928 | } else if (ofs->config.index) { | |
6ee8acf0 MS |
929 | pr_err("overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.\n"); |
930 | goto out; | |
931 | } else { | |
932 | pr_warn("overlayfs: upperdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n"); | |
933 | } | |
5064975e MS |
934 | |
935 | upper_mnt = clone_private_mount(upperpath); | |
936 | err = PTR_ERR(upper_mnt); | |
937 | if (IS_ERR(upper_mnt)) { | |
938 | pr_err("overlayfs: failed to clone upperpath\n"); | |
939 | goto out; | |
940 | } | |
941 | ||
942 | /* Don't inherit atime flags */ | |
943 | upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); | |
ad204488 | 944 | ofs->upper_mnt = upper_mnt; |
6ee8acf0 MS |
945 | err = 0; |
946 | out: | |
947 | return err; | |
948 | } | |
949 | ||
ad204488 | 950 | static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath) |
8ed61dc3 | 951 | { |
2ba9d57e | 952 | struct vfsmount *mnt = ofs->upper_mnt; |
8ed61dc3 MS |
953 | struct dentry *temp; |
954 | int err; | |
955 | ||
2ba9d57e AG |
956 | err = mnt_want_write(mnt); |
957 | if (err) | |
958 | return err; | |
959 | ||
ad204488 MS |
960 | ofs->workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false); |
961 | if (!ofs->workdir) | |
2ba9d57e | 962 | goto out; |
8ed61dc3 MS |
963 | |
964 | /* | |
965 | * Upper should support d_type, else whiteouts are visible. Given | |
966 | * workdir and upper are on same fs, we can do iterate_dir() on | |
967 | * workdir. This check requires successful creation of workdir in | |
968 | * previous step. | |
969 | */ | |
970 | err = ovl_check_d_type_supported(workpath); | |
971 | if (err < 0) | |
2ba9d57e | 972 | goto out; |
8ed61dc3 MS |
973 | |
974 | /* | |
975 | * We allowed this configuration and don't want to break users over | |
976 | * kernel upgrade. So warn instead of erroring out. | |
977 | */ | |
978 | if (!err) | |
979 | pr_warn("overlayfs: upper fs needs to support d_type.\n"); | |
980 | ||
981 | /* Check if upper/work fs supports O_TMPFILE */ | |
ad204488 MS |
982 | temp = ovl_do_tmpfile(ofs->workdir, S_IFREG | 0); |
983 | ofs->tmpfile = !IS_ERR(temp); | |
984 | if (ofs->tmpfile) | |
8ed61dc3 MS |
985 | dput(temp); |
986 | else | |
987 | pr_warn("overlayfs: upper fs does not support tmpfile.\n"); | |
988 | ||
989 | /* | |
990 | * Check if upper/work fs supports trusted.overlay.* xattr | |
991 | */ | |
ad204488 | 992 | err = ovl_do_setxattr(ofs->workdir, OVL_XATTR_OPAQUE, "0", 1, 0); |
8ed61dc3 | 993 | if (err) { |
ad204488 | 994 | ofs->noxattr = true; |
a683737b AG |
995 | ofs->config.index = false; |
996 | pr_warn("overlayfs: upper fs does not support xattr, falling back to index=off.\n"); | |
2ba9d57e | 997 | err = 0; |
8ed61dc3 | 998 | } else { |
ad204488 | 999 | vfs_removexattr(ofs->workdir, OVL_XATTR_OPAQUE); |
8ed61dc3 MS |
1000 | } |
1001 | ||
1002 | /* Check if upper/work fs supports file handles */ | |
ad204488 MS |
1003 | if (ofs->config.index && |
1004 | !ovl_can_decode_fh(ofs->workdir->d_sb)) { | |
1005 | ofs->config.index = false; | |
8ed61dc3 MS |
1006 | pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n"); |
1007 | } | |
1008 | ||
f168f109 AG |
1009 | /* NFS export of r/w mount depends on index */ |
1010 | if (ofs->config.nfs_export && !ofs->config.index) { | |
1011 | pr_warn("overlayfs: NFS export requires \"index=on\", falling back to nfs_export=off.\n"); | |
1012 | ofs->config.nfs_export = false; | |
1013 | } | |
1014 | ||
2ba9d57e AG |
1015 | out: |
1016 | mnt_drop_write(mnt); | |
1017 | return err; | |
8ed61dc3 MS |
1018 | } |
1019 | ||
ad204488 | 1020 | static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath) |
520d7c86 MS |
1021 | { |
1022 | int err; | |
bca44b52 | 1023 | struct path workpath = { }; |
520d7c86 | 1024 | |
ad204488 | 1025 | err = ovl_mount_dir(ofs->config.workdir, &workpath); |
520d7c86 MS |
1026 | if (err) |
1027 | goto out; | |
1028 | ||
1029 | err = -EINVAL; | |
bca44b52 | 1030 | if (upperpath->mnt != workpath.mnt) { |
520d7c86 MS |
1031 | pr_err("overlayfs: workdir and upperdir must reside under the same mount\n"); |
1032 | goto out; | |
1033 | } | |
bca44b52 | 1034 | if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) { |
520d7c86 MS |
1035 | pr_err("overlayfs: workdir and upperdir must be separate subtrees\n"); |
1036 | goto out; | |
1037 | } | |
1038 | ||
1039 | err = -EBUSY; | |
bca44b52 | 1040 | if (ovl_inuse_trylock(workpath.dentry)) { |
ad204488 MS |
1041 | ofs->workdir_locked = true; |
1042 | } else if (ofs->config.index) { | |
520d7c86 MS |
1043 | pr_err("overlayfs: workdir is in-use by another mount, mount with '-o index=off' to override exclusive workdir protection.\n"); |
1044 | goto out; | |
1045 | } else { | |
1046 | pr_warn("overlayfs: workdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n"); | |
1047 | } | |
1048 | ||
ad204488 MS |
1049 | ofs->workbasedir = dget(workpath.dentry); |
1050 | err = ovl_make_workdir(ofs, &workpath); | |
bca44b52 MS |
1051 | if (err) |
1052 | goto out; | |
1053 | ||
520d7c86 MS |
1054 | err = 0; |
1055 | out: | |
bca44b52 MS |
1056 | path_put(&workpath); |
1057 | ||
520d7c86 MS |
1058 | return err; |
1059 | } | |
1060 | ||
ad204488 | 1061 | static int ovl_get_indexdir(struct ovl_fs *ofs, struct ovl_entry *oe, |
95e6d417 | 1062 | struct path *upperpath) |
f7e3a7d9 | 1063 | { |
2ba9d57e | 1064 | struct vfsmount *mnt = ofs->upper_mnt; |
f7e3a7d9 MS |
1065 | int err; |
1066 | ||
2ba9d57e AG |
1067 | err = mnt_want_write(mnt); |
1068 | if (err) | |
1069 | return err; | |
1070 | ||
f7e3a7d9 | 1071 | /* Verify lower root is upper root origin */ |
d9768076 | 1072 | err = ovl_verify_origin(upperpath->dentry, oe->lowerstack[0].dentry, |
05122443 | 1073 | true); |
f7e3a7d9 MS |
1074 | if (err) { |
1075 | pr_err("overlayfs: failed to verify upper root origin\n"); | |
1076 | goto out; | |
1077 | } | |
1078 | ||
ad204488 MS |
1079 | ofs->indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true); |
1080 | if (ofs->indexdir) { | |
ad1d615c AG |
1081 | /* |
1082 | * Verify upper root is exclusively associated with index dir. | |
1083 | * Older kernels stored upper fh in "trusted.overlay.origin" | |
1084 | * xattr. If that xattr exists, verify that it is a match to | |
1085 | * upper dir file handle. In any case, verify or set xattr | |
1086 | * "trusted.overlay.upper" to indicate that index may have | |
1087 | * directory entries. | |
1088 | */ | |
1089 | if (ovl_check_origin_xattr(ofs->indexdir)) { | |
1090 | err = ovl_verify_set_fh(ofs->indexdir, OVL_XATTR_ORIGIN, | |
1091 | upperpath->dentry, true, false); | |
1092 | if (err) | |
1093 | pr_err("overlayfs: failed to verify index dir 'origin' xattr\n"); | |
1094 | } | |
1095 | err = ovl_verify_upper(ofs->indexdir, upperpath->dentry, true); | |
f7e3a7d9 | 1096 | if (err) |
ad1d615c | 1097 | pr_err("overlayfs: failed to verify index dir 'upper' xattr\n"); |
f7e3a7d9 MS |
1098 | |
1099 | /* Cleanup bad/stale/orphan index entries */ | |
1100 | if (!err) | |
1eff1a1d | 1101 | err = ovl_indexdir_cleanup(ofs); |
f7e3a7d9 | 1102 | } |
ad204488 | 1103 | if (err || !ofs->indexdir) |
f7e3a7d9 MS |
1104 | pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n"); |
1105 | ||
1106 | out: | |
2ba9d57e | 1107 | mnt_drop_write(mnt); |
f7e3a7d9 MS |
1108 | return err; |
1109 | } | |
1110 | ||
ad204488 | 1111 | static int ovl_get_lower_layers(struct ovl_fs *ofs, struct path *stack, |
520d7c86 MS |
1112 | unsigned int numlower) |
1113 | { | |
1114 | int err; | |
1115 | unsigned int i; | |
1116 | ||
1117 | err = -ENOMEM; | |
ad204488 | 1118 | ofs->lower_layers = kcalloc(numlower, sizeof(struct ovl_layer), |
520d7c86 | 1119 | GFP_KERNEL); |
ad204488 | 1120 | if (ofs->lower_layers == NULL) |
520d7c86 MS |
1121 | goto out; |
1122 | for (i = 0; i < numlower; i++) { | |
1123 | struct vfsmount *mnt; | |
1124 | dev_t dev; | |
1125 | ||
1126 | err = get_anon_bdev(&dev); | |
1127 | if (err) { | |
1128 | pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n"); | |
1129 | goto out; | |
1130 | } | |
1131 | ||
1132 | mnt = clone_private_mount(&stack[i]); | |
1133 | err = PTR_ERR(mnt); | |
1134 | if (IS_ERR(mnt)) { | |
1135 | pr_err("overlayfs: failed to clone lowerpath\n"); | |
1136 | free_anon_bdev(dev); | |
1137 | goto out; | |
1138 | } | |
1139 | /* | |
1140 | * Make lower layers R/O. That way fchmod/fchown on lower file | |
1141 | * will fail instead of modifying lower fs. | |
1142 | */ | |
1143 | mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME; | |
1144 | ||
ad204488 MS |
1145 | ofs->lower_layers[ofs->numlower].mnt = mnt; |
1146 | ofs->lower_layers[ofs->numlower].pseudo_dev = dev; | |
d583ed7d | 1147 | ofs->lower_layers[ofs->numlower].idx = i + 1; |
ad204488 | 1148 | ofs->numlower++; |
520d7c86 MS |
1149 | |
1150 | /* Check if all lower layers are on same sb */ | |
1151 | if (i == 0) | |
ad204488 MS |
1152 | ofs->same_sb = mnt->mnt_sb; |
1153 | else if (ofs->same_sb != mnt->mnt_sb) | |
1154 | ofs->same_sb = NULL; | |
520d7c86 MS |
1155 | } |
1156 | err = 0; | |
1157 | out: | |
1158 | return err; | |
1159 | } | |
1160 | ||
4155c10a | 1161 | static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb, |
ad204488 | 1162 | struct ovl_fs *ofs) |
53dbb0b4 MS |
1163 | { |
1164 | int err; | |
1165 | char *lowertmp, *lower; | |
4155c10a MS |
1166 | struct path *stack = NULL; |
1167 | unsigned int stacklen, numlower = 0, i; | |
53dbb0b4 | 1168 | bool remote = false; |
4155c10a | 1169 | struct ovl_entry *oe; |
53dbb0b4 MS |
1170 | |
1171 | err = -ENOMEM; | |
ad204488 | 1172 | lowertmp = kstrdup(ofs->config.lowerdir, GFP_KERNEL); |
53dbb0b4 | 1173 | if (!lowertmp) |
4155c10a | 1174 | goto out_err; |
53dbb0b4 MS |
1175 | |
1176 | err = -EINVAL; | |
1177 | stacklen = ovl_split_lowerdirs(lowertmp); | |
1178 | if (stacklen > OVL_MAX_STACK) { | |
1179 | pr_err("overlayfs: too many lower directories, limit is %d\n", | |
1180 | OVL_MAX_STACK); | |
4155c10a | 1181 | goto out_err; |
ad204488 | 1182 | } else if (!ofs->config.upperdir && stacklen == 1) { |
53dbb0b4 | 1183 | pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n"); |
4155c10a | 1184 | goto out_err; |
f168f109 AG |
1185 | } else if (!ofs->config.upperdir && ofs->config.nfs_export && |
1186 | ofs->config.redirect_follow) { | |
1187 | pr_warn("overlayfs: NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n"); | |
1188 | ofs->config.nfs_export = false; | |
53dbb0b4 MS |
1189 | } |
1190 | ||
1191 | err = -ENOMEM; | |
1192 | stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL); | |
1193 | if (!stack) | |
4155c10a | 1194 | goto out_err; |
53dbb0b4 MS |
1195 | |
1196 | err = -EINVAL; | |
1197 | lower = lowertmp; | |
1198 | for (numlower = 0; numlower < stacklen; numlower++) { | |
ad204488 | 1199 | err = ovl_lower_dir(lower, &stack[numlower], ofs, |
53dbb0b4 MS |
1200 | &sb->s_stack_depth, &remote); |
1201 | if (err) | |
4155c10a | 1202 | goto out_err; |
53dbb0b4 MS |
1203 | |
1204 | lower = strchr(lower, '\0') + 1; | |
1205 | } | |
1206 | ||
1207 | err = -EINVAL; | |
1208 | sb->s_stack_depth++; | |
1209 | if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { | |
1210 | pr_err("overlayfs: maximum fs stacking depth exceeded\n"); | |
4155c10a | 1211 | goto out_err; |
53dbb0b4 MS |
1212 | } |
1213 | ||
ad204488 | 1214 | err = ovl_get_lower_layers(ofs, stack, numlower); |
4155c10a MS |
1215 | if (err) |
1216 | goto out_err; | |
1217 | ||
1218 | err = -ENOMEM; | |
1219 | oe = ovl_alloc_entry(numlower); | |
1220 | if (!oe) | |
1221 | goto out_err; | |
1222 | ||
1223 | for (i = 0; i < numlower; i++) { | |
1224 | oe->lowerstack[i].dentry = dget(stack[i].dentry); | |
ad204488 | 1225 | oe->lowerstack[i].layer = &ofs->lower_layers[i]; |
4155c10a | 1226 | } |
53dbb0b4 MS |
1227 | |
1228 | if (remote) | |
1229 | sb->s_d_op = &ovl_reval_dentry_operations; | |
1230 | else | |
1231 | sb->s_d_op = &ovl_dentry_operations; | |
1232 | ||
53dbb0b4 | 1233 | out: |
53dbb0b4 MS |
1234 | for (i = 0; i < numlower; i++) |
1235 | path_put(&stack[i]); | |
1236 | kfree(stack); | |
4155c10a MS |
1237 | kfree(lowertmp); |
1238 | ||
1239 | return oe; | |
1240 | ||
1241 | out_err: | |
1242 | oe = ERR_PTR(err); | |
53dbb0b4 MS |
1243 | goto out; |
1244 | } | |
1245 | ||
e9be9d5e MS |
1246 | static int ovl_fill_super(struct super_block *sb, void *data, int silent) |
1247 | { | |
33006cdf | 1248 | struct path upperpath = { }; |
e9be9d5e | 1249 | struct dentry *root_dentry; |
4155c10a | 1250 | struct ovl_entry *oe; |
ad204488 | 1251 | struct ovl_fs *ofs; |
51f8f3c4 | 1252 | struct cred *cred; |
e9be9d5e MS |
1253 | int err; |
1254 | ||
f45827e8 | 1255 | err = -ENOMEM; |
ad204488 MS |
1256 | ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); |
1257 | if (!ofs) | |
e9be9d5e MS |
1258 | goto out; |
1259 | ||
ad204488 | 1260 | ofs->creator_cred = cred = prepare_creds(); |
c6fe6254 MS |
1261 | if (!cred) |
1262 | goto out_err; | |
1263 | ||
ad204488 | 1264 | ofs->config.index = ovl_index_def; |
f168f109 | 1265 | ofs->config.nfs_export = ovl_nfs_export_def; |
ad204488 | 1266 | err = ovl_parse_opt((char *) data, &ofs->config); |
f45827e8 | 1267 | if (err) |
a9075cdb | 1268 | goto out_err; |
f45827e8 | 1269 | |
e9be9d5e | 1270 | err = -EINVAL; |
ad204488 | 1271 | if (!ofs->config.lowerdir) { |
07f2af7b KK |
1272 | if (!silent) |
1273 | pr_err("overlayfs: missing 'lowerdir'\n"); | |
a9075cdb | 1274 | goto out_err; |
e9be9d5e MS |
1275 | } |
1276 | ||
53a08cb9 | 1277 | sb->s_stack_depth = 0; |
cf9a6784 | 1278 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
ad204488 MS |
1279 | if (ofs->config.upperdir) { |
1280 | if (!ofs->config.workdir) { | |
53a08cb9 | 1281 | pr_err("overlayfs: missing 'workdir'\n"); |
a9075cdb | 1282 | goto out_err; |
53a08cb9 | 1283 | } |
e9be9d5e | 1284 | |
ad204488 | 1285 | err = ovl_get_upper(ofs, &upperpath); |
53a08cb9 | 1286 | if (err) |
a9075cdb | 1287 | goto out_err; |
2cac0c00 | 1288 | |
ad204488 | 1289 | err = ovl_get_workdir(ofs, &upperpath); |
8ed61dc3 | 1290 | if (err) |
a9075cdb | 1291 | goto out_err; |
c6fe6254 | 1292 | |
ad204488 | 1293 | if (!ofs->workdir) |
1751e8a6 | 1294 | sb->s_flags |= SB_RDONLY; |
6e88256e | 1295 | |
ad204488 MS |
1296 | sb->s_stack_depth = ofs->upper_mnt->mnt_sb->s_stack_depth; |
1297 | sb->s_time_gran = ofs->upper_mnt->mnt_sb->s_time_gran; | |
c6fe6254 | 1298 | |
e9be9d5e | 1299 | } |
ad204488 | 1300 | oe = ovl_get_lowerstack(sb, ofs); |
4155c10a MS |
1301 | err = PTR_ERR(oe); |
1302 | if (IS_ERR(oe)) | |
a9075cdb | 1303 | goto out_err; |
e9be9d5e | 1304 | |
71cbad7e | 1305 | /* If the upper fs is nonexistent, we mark overlayfs r/o too */ |
ad204488 | 1306 | if (!ofs->upper_mnt) |
1751e8a6 | 1307 | sb->s_flags |= SB_RDONLY; |
ad204488 MS |
1308 | else if (ofs->upper_mnt->mnt_sb != ofs->same_sb) |
1309 | ofs->same_sb = NULL; | |
e9be9d5e | 1310 | |
ad204488 MS |
1311 | if (!(ovl_force_readonly(ofs)) && ofs->config.index) { |
1312 | err = ovl_get_indexdir(ofs, oe, &upperpath); | |
54fb347e | 1313 | if (err) |
4155c10a | 1314 | goto out_free_oe; |
6e88256e | 1315 | |
972d0093 AG |
1316 | /* Force r/o mount with no index dir */ |
1317 | if (!ofs->indexdir) { | |
1318 | dput(ofs->workdir); | |
1319 | ofs->workdir = NULL; | |
1751e8a6 | 1320 | sb->s_flags |= SB_RDONLY; |
972d0093 AG |
1321 | } |
1322 | ||
02bcd157 AG |
1323 | } |
1324 | ||
972d0093 | 1325 | /* Show index=off in /proc/mounts for forced r/o mount */ |
f168f109 | 1326 | if (!ofs->indexdir) { |
ad204488 | 1327 | ofs->config.index = false; |
f168f109 AG |
1328 | if (ofs->upper_mnt && ofs->config.nfs_export) { |
1329 | pr_warn("overlayfs: NFS export requires an index dir, falling back to nfs_export=off.\n"); | |
1330 | ofs->config.nfs_export = false; | |
1331 | } | |
1332 | } | |
02bcd157 | 1333 | |
51f8f3c4 KK |
1334 | /* Never override disk quota limits or use reserved space */ |
1335 | cap_lower(cred->cap_effective, CAP_SYS_RESOURCE); | |
1336 | ||
655042cc VG |
1337 | sb->s_magic = OVERLAYFS_SUPER_MAGIC; |
1338 | sb->s_op = &ovl_super_operations; | |
1339 | sb->s_xattr = ovl_xattr_handlers; | |
ad204488 | 1340 | sb->s_fs_info = ofs; |
1751e8a6 | 1341 | sb->s_flags |= SB_POSIXACL | SB_NOREMOTELOCK; |
655042cc | 1342 | |
c6fe6254 | 1343 | err = -ENOMEM; |
ca4c8a3a | 1344 | root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0)); |
e9be9d5e | 1345 | if (!root_dentry) |
4155c10a | 1346 | goto out_free_oe; |
e9be9d5e MS |
1347 | |
1348 | mntput(upperpath.mnt); | |
f3a15685 | 1349 | if (upperpath.dentry) { |
55acc661 | 1350 | oe->has_upper = true; |
13c72075 MS |
1351 | if (ovl_is_impuredir(upperpath.dentry)) |
1352 | ovl_set_flag(OVL_IMPURE, d_inode(root_dentry)); | |
f3a15685 | 1353 | } |
e9be9d5e MS |
1354 | |
1355 | root_dentry->d_fsdata = oe; | |
1356 | ||
b79e05aa AG |
1357 | /* Root is always merge -> can have whiteouts */ |
1358 | ovl_set_flag(OVL_WHITEOUTS, d_inode(root_dentry)); | |
09d8b586 MS |
1359 | ovl_inode_init(d_inode(root_dentry), upperpath.dentry, |
1360 | ovl_dentry_lower(root_dentry)); | |
ed06e069 | 1361 | |
e9be9d5e | 1362 | sb->s_root = root_dentry; |
e9be9d5e MS |
1363 | |
1364 | return 0; | |
1365 | ||
4155c10a MS |
1366 | out_free_oe: |
1367 | ovl_entry_stack_free(oe); | |
b9343632 | 1368 | kfree(oe); |
4155c10a | 1369 | out_err: |
e9be9d5e | 1370 | path_put(&upperpath); |
ad204488 | 1371 | ovl_free_fs(ofs); |
e9be9d5e MS |
1372 | out: |
1373 | return err; | |
1374 | } | |
1375 | ||
1376 | static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, | |
1377 | const char *dev_name, void *raw_data) | |
1378 | { | |
1379 | return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); | |
1380 | } | |
1381 | ||
1382 | static struct file_system_type ovl_fs_type = { | |
1383 | .owner = THIS_MODULE, | |
ef94b186 | 1384 | .name = "overlay", |
e9be9d5e MS |
1385 | .mount = ovl_mount, |
1386 | .kill_sb = kill_anon_super, | |
1387 | }; | |
ef94b186 | 1388 | MODULE_ALIAS_FS("overlay"); |
e9be9d5e | 1389 | |
13cf199d AG |
1390 | static void ovl_inode_init_once(void *foo) |
1391 | { | |
1392 | struct ovl_inode *oi = foo; | |
1393 | ||
1394 | inode_init_once(&oi->vfs_inode); | |
1395 | } | |
1396 | ||
e9be9d5e MS |
1397 | static int __init ovl_init(void) |
1398 | { | |
13cf199d AG |
1399 | int err; |
1400 | ||
1401 | ovl_inode_cachep = kmem_cache_create("ovl_inode", | |
1402 | sizeof(struct ovl_inode), 0, | |
1403 | (SLAB_RECLAIM_ACCOUNT| | |
1404 | SLAB_MEM_SPREAD|SLAB_ACCOUNT), | |
1405 | ovl_inode_init_once); | |
1406 | if (ovl_inode_cachep == NULL) | |
1407 | return -ENOMEM; | |
1408 | ||
1409 | err = register_filesystem(&ovl_fs_type); | |
1410 | if (err) | |
1411 | kmem_cache_destroy(ovl_inode_cachep); | |
1412 | ||
1413 | return err; | |
e9be9d5e MS |
1414 | } |
1415 | ||
1416 | static void __exit ovl_exit(void) | |
1417 | { | |
1418 | unregister_filesystem(&ovl_fs_type); | |
13cf199d AG |
1419 | |
1420 | /* | |
1421 | * Make sure all delayed rcu free inodes are flushed before we | |
1422 | * destroy cache. | |
1423 | */ | |
1424 | rcu_barrier(); | |
1425 | kmem_cache_destroy(ovl_inode_cachep); | |
1426 | ||
e9be9d5e MS |
1427 | } |
1428 | ||
1429 | module_init(ovl_init); | |
1430 | module_exit(ovl_exit); |