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1// SPDX-License-Identifier: GPL-2.0-only
2
3#include <linux/fs.h>
4#include <linux/module.h>
5#include <linux/namei.h>
6#include <linux/fs_context.h>
7#include <linux/fs_parser.h>
8#include <linux/posix_acl_xattr.h>
9#include <linux/seq_file.h>
10#include <linux/xattr.h>
11#include "overlayfs.h"
12#include "params.h"
13
14static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR);
15module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644);
16MODULE_PARM_DESC(redirect_dir,
17 "Default to on or off for the redirect_dir feature");
18
19static bool ovl_redirect_always_follow =
20 IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW);
21module_param_named(redirect_always_follow, ovl_redirect_always_follow,
22 bool, 0644);
23MODULE_PARM_DESC(redirect_always_follow,
24 "Follow redirects even if redirect_dir feature is turned off");
25
26static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO);
27module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644);
28MODULE_PARM_DESC(xino_auto,
29 "Auto enable xino feature");
30
31static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX);
32module_param_named(index, ovl_index_def, bool, 0644);
33MODULE_PARM_DESC(index,
34 "Default to on or off for the inodes index feature");
35
36static bool ovl_nfs_export_def = IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT);
37module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644);
38MODULE_PARM_DESC(nfs_export,
39 "Default to on or off for the NFS export feature");
40
41static bool ovl_metacopy_def = IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY);
42module_param_named(metacopy, ovl_metacopy_def, bool, 0644);
43MODULE_PARM_DESC(metacopy,
44 "Default to on or off for the metadata only copy up feature");
45
46enum ovl_opt {
47 Opt_lowerdir,
48 Opt_lowerdir_add,
49 Opt_datadir_add,
50 Opt_upperdir,
51 Opt_workdir,
52 Opt_default_permissions,
53 Opt_redirect_dir,
54 Opt_index,
55 Opt_uuid,
56 Opt_nfs_export,
57 Opt_userxattr,
58 Opt_xino,
59 Opt_metacopy,
60 Opt_verity,
61 Opt_volatile,
62};
63
64static const struct constant_table ovl_parameter_bool[] = {
65 { "on", true },
66 { "off", false },
67 {}
68};
69
70static const struct constant_table ovl_parameter_uuid[] = {
71 { "off", OVL_UUID_OFF },
72 { "null", OVL_UUID_NULL },
73 { "auto", OVL_UUID_AUTO },
74 { "on", OVL_UUID_ON },
75 {}
76};
77
78static const char *ovl_uuid_mode(struct ovl_config *config)
79{
80 return ovl_parameter_uuid[config->uuid].name;
81}
82
83static int ovl_uuid_def(void)
84{
85 return OVL_UUID_AUTO;
86}
87
88static const struct constant_table ovl_parameter_xino[] = {
89 { "off", OVL_XINO_OFF },
90 { "auto", OVL_XINO_AUTO },
91 { "on", OVL_XINO_ON },
92 {}
93};
94
95const char *ovl_xino_mode(struct ovl_config *config)
96{
97 return ovl_parameter_xino[config->xino].name;
98}
99
100static int ovl_xino_def(void)
101{
102 return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF;
103}
104
105const struct constant_table ovl_parameter_redirect_dir[] = {
106 { "off", OVL_REDIRECT_OFF },
107 { "follow", OVL_REDIRECT_FOLLOW },
108 { "nofollow", OVL_REDIRECT_NOFOLLOW },
109 { "on", OVL_REDIRECT_ON },
110 {}
111};
112
113static const char *ovl_redirect_mode(struct ovl_config *config)
114{
115 return ovl_parameter_redirect_dir[config->redirect_mode].name;
116}
117
118static int ovl_redirect_mode_def(void)
119{
120 return ovl_redirect_dir_def ? OVL_REDIRECT_ON :
121 ovl_redirect_always_follow ? OVL_REDIRECT_FOLLOW :
122 OVL_REDIRECT_NOFOLLOW;
123}
124
125static const struct constant_table ovl_parameter_verity[] = {
126 { "off", OVL_VERITY_OFF },
127 { "on", OVL_VERITY_ON },
128 { "require", OVL_VERITY_REQUIRE },
129 {}
130};
131
132static const char *ovl_verity_mode(struct ovl_config *config)
133{
134 return ovl_parameter_verity[config->verity_mode].name;
135}
136
137static int ovl_verity_mode_def(void)
138{
139 return OVL_VERITY_OFF;
140}
141
142const struct fs_parameter_spec ovl_parameter_spec[] = {
143 fsparam_string_empty("lowerdir", Opt_lowerdir),
144 fsparam_file_or_string("lowerdir+", Opt_lowerdir_add),
145 fsparam_file_or_string("datadir+", Opt_datadir_add),
146 fsparam_file_or_string("upperdir", Opt_upperdir),
147 fsparam_file_or_string("workdir", Opt_workdir),
148 fsparam_flag("default_permissions", Opt_default_permissions),
149 fsparam_enum("redirect_dir", Opt_redirect_dir, ovl_parameter_redirect_dir),
150 fsparam_enum("index", Opt_index, ovl_parameter_bool),
151 fsparam_enum("uuid", Opt_uuid, ovl_parameter_uuid),
152 fsparam_enum("nfs_export", Opt_nfs_export, ovl_parameter_bool),
153 fsparam_flag("userxattr", Opt_userxattr),
154 fsparam_enum("xino", Opt_xino, ovl_parameter_xino),
155 fsparam_enum("metacopy", Opt_metacopy, ovl_parameter_bool),
156 fsparam_enum("verity", Opt_verity, ovl_parameter_verity),
157 fsparam_flag("volatile", Opt_volatile),
158 {}
159};
160
161static char *ovl_next_opt(char **s)
162{
163 char *sbegin = *s;
164 char *p;
165
166 if (sbegin == NULL)
167 return NULL;
168
169 for (p = sbegin; *p; p++) {
170 if (*p == '\\') {
171 p++;
172 if (!*p)
173 break;
174 } else if (*p == ',') {
175 *p = '\0';
176 *s = p + 1;
177 return sbegin;
178 }
179 }
180 *s = NULL;
181 return sbegin;
182}
183
184static int ovl_parse_monolithic(struct fs_context *fc, void *data)
185{
186 return vfs_parse_monolithic_sep(fc, data, ovl_next_opt);
187}
188
189static ssize_t ovl_parse_param_split_lowerdirs(char *str)
190{
191 ssize_t nr_layers = 1, nr_colons = 0;
192 char *s, *d;
193
194 for (s = d = str;; s++, d++) {
195 if (*s == '\\') {
196 /* keep esc chars in split lowerdir */
197 *d++ = *s++;
198 } else if (*s == ':') {
199 bool next_colon = (*(s + 1) == ':');
200
201 nr_colons++;
202 if (nr_colons == 2 && next_colon) {
203 pr_err("only single ':' or double '::' sequences of unescaped colons in lowerdir mount option allowed.\n");
204 return -EINVAL;
205 }
206 /* count layers, not colons */
207 if (!next_colon)
208 nr_layers++;
209
210 *d = '\0';
211 continue;
212 }
213
214 *d = *s;
215 if (!*s) {
216 /* trailing colons */
217 if (nr_colons) {
218 pr_err("unescaped trailing colons in lowerdir mount option.\n");
219 return -EINVAL;
220 }
221 break;
222 }
223 nr_colons = 0;
224 }
225
226 return nr_layers;
227}
228
229static int ovl_mount_dir_noesc(const char *name, struct path *path)
230{
231 int err = -EINVAL;
232
233 if (!*name) {
234 pr_err("empty lowerdir\n");
235 goto out;
236 }
237 err = kern_path(name, LOOKUP_FOLLOW, path);
238 if (err) {
239 pr_err("failed to resolve '%s': %i\n", name, err);
240 goto out;
241 }
242 return 0;
243
244out:
245 return err;
246}
247
248static void ovl_unescape(char *s)
249{
250 char *d = s;
251
252 for (;; s++, d++) {
253 if (*s == '\\')
254 s++;
255 *d = *s;
256 if (!*s)
257 break;
258 }
259}
260
261static int ovl_mount_dir(const char *name, struct path *path)
262{
263 int err = -ENOMEM;
264 char *tmp = kstrdup(name, GFP_KERNEL);
265
266 if (tmp) {
267 ovl_unescape(tmp);
268 err = ovl_mount_dir_noesc(tmp, path);
269 kfree(tmp);
270 }
271 return err;
272}
273
274static int ovl_mount_dir_check(struct fs_context *fc, const struct path *path,
275 enum ovl_opt layer, const char *name, bool upper)
276{
277 struct ovl_fs_context *ctx = fc->fs_private;
278
279 if (!d_is_dir(path->dentry))
280 return invalfc(fc, "%s is not a directory", name);
281
282 /*
283 * Root dentries of case-insensitive capable filesystems might
284 * not have the dentry operations set, but still be incompatible
285 * with overlayfs. Check explicitly to prevent post-mount
286 * failures.
287 */
288 if (sb_has_encoding(path->mnt->mnt_sb))
289 return invalfc(fc, "case-insensitive capable filesystem on %s not supported", name);
290
291 if (ovl_dentry_weird(path->dentry))
292 return invalfc(fc, "filesystem on %s not supported", name);
293
294 /*
295 * Check whether upper path is read-only here to report failures
296 * early. Don't forget to recheck when the superblock is created
297 * as the mount attributes could change.
298 */
299 if (upper) {
300 if (path->dentry->d_flags & DCACHE_OP_REAL)
301 return invalfc(fc, "filesystem on %s not supported as upperdir", name);
302 if (__mnt_is_readonly(path->mnt))
303 return invalfc(fc, "filesystem on %s is read-only", name);
304 } else {
305 if (ctx->lowerdir_all && layer != Opt_lowerdir)
306 return invalfc(fc, "lowerdir+ and datadir+ cannot follow lowerdir");
307 if (ctx->nr_data && layer == Opt_lowerdir_add)
308 return invalfc(fc, "regular lower layers cannot follow data layers");
309 if (ctx->nr == OVL_MAX_STACK)
310 return invalfc(fc, "too many lower directories, limit is %d",
311 OVL_MAX_STACK);
312 }
313 return 0;
314}
315
316static int ovl_ctx_realloc_lower(struct fs_context *fc)
317{
318 struct ovl_fs_context *ctx = fc->fs_private;
319 struct ovl_fs_context_layer *l;
320 size_t nr;
321
322 if (ctx->nr < ctx->capacity)
323 return 0;
324
325 nr = min_t(size_t, max(4096 / sizeof(*l), ctx->capacity * 2),
326 OVL_MAX_STACK);
327 l = krealloc_array(ctx->lower, nr, sizeof(*l), GFP_KERNEL_ACCOUNT);
328 if (!l)
329 return -ENOMEM;
330
331 ctx->lower = l;
332 ctx->capacity = nr;
333 return 0;
334}
335
336static void ovl_add_layer(struct fs_context *fc, enum ovl_opt layer,
337 struct path *path, char **pname)
338{
339 struct ovl_fs *ofs = fc->s_fs_info;
340 struct ovl_config *config = &ofs->config;
341 struct ovl_fs_context *ctx = fc->fs_private;
342 struct ovl_fs_context_layer *l;
343
344 switch (layer) {
345 case Opt_workdir:
346 swap(config->workdir, *pname);
347 swap(ctx->work, *path);
348 break;
349 case Opt_upperdir:
350 swap(config->upperdir, *pname);
351 swap(ctx->upper, *path);
352 break;
353 case Opt_datadir_add:
354 ctx->nr_data++;
355 fallthrough;
356 case Opt_lowerdir:
357 fallthrough;
358 case Opt_lowerdir_add:
359 WARN_ON(ctx->nr >= ctx->capacity);
360 l = &ctx->lower[ctx->nr++];
361 memset(l, 0, sizeof(*l));
362 swap(l->name, *pname);
363 swap(l->path, *path);
364 break;
365 default:
366 WARN_ON(1);
367 }
368}
369
370static inline bool is_upper_layer(enum ovl_opt layer)
371{
372 return layer == Opt_upperdir || layer == Opt_workdir;
373}
374
375/* Handle non-file descriptor-based layer options that require path lookup. */
376static inline int ovl_kern_path(const char *layer_name, struct path *layer_path,
377 enum ovl_opt layer)
378{
379 int err;
380
381 switch (layer) {
382 case Opt_upperdir:
383 fallthrough;
384 case Opt_workdir:
385 fallthrough;
386 case Opt_lowerdir:
387 err = ovl_mount_dir(layer_name, layer_path);
388 break;
389 case Opt_lowerdir_add:
390 fallthrough;
391 case Opt_datadir_add:
392 err = ovl_mount_dir_noesc(layer_name, layer_path);
393 break;
394 default:
395 WARN_ON_ONCE(true);
396 err = -EINVAL;
397 }
398
399 return err;
400}
401
402static int ovl_do_parse_layer(struct fs_context *fc, const char *layer_name,
403 struct path *layer_path, enum ovl_opt layer)
404{
405 char *name __free(kfree) = kstrdup(layer_name, GFP_KERNEL);
406 bool upper;
407 int err = 0;
408
409 if (!name)
410 return -ENOMEM;
411
412 upper = is_upper_layer(layer);
413 err = ovl_mount_dir_check(fc, layer_path, layer, name, upper);
414 if (err)
415 return err;
416
417 if (!upper) {
418 err = ovl_ctx_realloc_lower(fc);
419 if (err)
420 return err;
421 }
422
423 /* Store the user provided path string in ctx to show in mountinfo */
424 ovl_add_layer(fc, layer, layer_path, &name);
425 return err;
426}
427
428static int ovl_parse_layer(struct fs_context *fc, struct fs_parameter *param,
429 enum ovl_opt layer)
430{
431 struct path layer_path __free(path_put) = {};
432 int err = 0;
433
434 switch (param->type) {
435 case fs_value_is_string:
436 err = ovl_kern_path(param->string, &layer_path, layer);
437 if (err)
438 return err;
439 err = ovl_do_parse_layer(fc, param->string, &layer_path, layer);
440 break;
441 case fs_value_is_file: {
442 char *buf __free(kfree);
443 char *layer_name;
444
445 buf = kmalloc(PATH_MAX, GFP_KERNEL_ACCOUNT);
446 if (!buf)
447 return -ENOMEM;
448
449 layer_path = param->file->f_path;
450 path_get(&layer_path);
451
452 layer_name = d_path(&layer_path, buf, PATH_MAX);
453 if (IS_ERR(layer_name))
454 return PTR_ERR(layer_name);
455
456 err = ovl_do_parse_layer(fc, layer_name, &layer_path, layer);
457 break;
458 }
459 default:
460 WARN_ON_ONCE(true);
461 err = -EINVAL;
462 }
463
464 return err;
465}
466
467static void ovl_reset_lowerdirs(struct ovl_fs_context *ctx)
468{
469 struct ovl_fs_context_layer *l = ctx->lower;
470
471 // Reset old user provided lowerdir string
472 kfree(ctx->lowerdir_all);
473 ctx->lowerdir_all = NULL;
474
475 for (size_t nr = 0; nr < ctx->nr; nr++, l++) {
476 path_put(&l->path);
477 kfree(l->name);
478 l->name = NULL;
479 }
480 ctx->nr = 0;
481 ctx->nr_data = 0;
482}
483
484/*
485 * Parse lowerdir= mount option:
486 *
487 * e.g.: lowerdir=/lower1:/lower2:/lower3::/data1::/data2
488 * Set "/lower1", "/lower2", and "/lower3" as lower layers and
489 * "/data1" and "/data2" as data lower layers. Any existing lower
490 * layers are replaced.
491 */
492static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
493{
494 int err;
495 struct ovl_fs_context *ctx = fc->fs_private;
496 char *dup = NULL, *iter;
497 ssize_t nr_lower, nr;
498 bool data_layer = false;
499
500 /*
501 * Ensure we're backwards compatible with mount(2)
502 * by allowing relative paths.
503 */
504
505 /* drop all existing lower layers */
506 ovl_reset_lowerdirs(ctx);
507
508 if (!*name)
509 return 0;
510
511 if (*name == ':') {
512 pr_err("cannot append lower layer\n");
513 return -EINVAL;
514 }
515
516 // Store user provided lowerdir string to show in mount options
517 ctx->lowerdir_all = kstrdup(name, GFP_KERNEL);
518 if (!ctx->lowerdir_all)
519 return -ENOMEM;
520
521 dup = kstrdup(name, GFP_KERNEL);
522 if (!dup)
523 return -ENOMEM;
524
525 err = -EINVAL;
526 nr_lower = ovl_parse_param_split_lowerdirs(dup);
527 if (nr_lower < 0)
528 goto out_err;
529
530 if (nr_lower > OVL_MAX_STACK) {
531 pr_err("too many lower directories, limit is %d\n", OVL_MAX_STACK);
532 goto out_err;
533 }
534
535 iter = dup;
536 for (nr = 0; nr < nr_lower; nr++) {
537 struct path path __free(path_put) = {};
538
539 err = ovl_kern_path(iter, &path, Opt_lowerdir);
540 if (err)
541 goto out_err;
542
543 err = ovl_do_parse_layer(fc, iter, &path, Opt_lowerdir);
544 if (err)
545 goto out_err;
546
547 if (data_layer)
548 ctx->nr_data++;
549
550 /* Calling strchr() again would overrun. */
551 if (ctx->nr == nr_lower)
552 break;
553
554 err = -EINVAL;
555 iter = strchr(iter, '\0') + 1;
556 if (*iter) {
557 /*
558 * This is a regular layer so we require that
559 * there are no data layers.
560 */
561 if (ctx->nr_data > 0) {
562 pr_err("regular lower layers cannot follow data lower layers\n");
563 goto out_err;
564 }
565
566 data_layer = false;
567 continue;
568 }
569
570 /* This is a data lower layer. */
571 data_layer = true;
572 iter++;
573 }
574 kfree(dup);
575 return 0;
576
577out_err:
578 kfree(dup);
579
580 /* Intentionally don't realloc to a smaller size. */
581 return err;
582}
583
584static int ovl_parse_param(struct fs_context *fc, struct fs_parameter *param)
585{
586 int err = 0;
587 struct fs_parse_result result;
588 struct ovl_fs *ofs = fc->s_fs_info;
589 struct ovl_config *config = &ofs->config;
590 struct ovl_fs_context *ctx = fc->fs_private;
591 int opt;
592
593 if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
594 /*
595 * On remount overlayfs has always ignored all mount
596 * options no matter if malformed or not so for
597 * backwards compatibility we do the same here.
598 */
599 if (fc->oldapi)
600 return 0;
601
602 /*
603 * Give us the freedom to allow changing mount options
604 * with the new mount api in the future. So instead of
605 * silently ignoring everything we report a proper
606 * error. This is only visible for users of the new
607 * mount api.
608 */
609 return invalfc(fc, "No changes allowed in reconfigure");
610 }
611
612 opt = fs_parse(fc, ovl_parameter_spec, param, &result);
613 if (opt < 0)
614 return opt;
615
616 switch (opt) {
617 case Opt_lowerdir:
618 err = ovl_parse_param_lowerdir(param->string, fc);
619 break;
620 case Opt_lowerdir_add:
621 case Opt_datadir_add:
622 case Opt_upperdir:
623 case Opt_workdir:
624 err = ovl_parse_layer(fc, param, opt);
625 break;
626 case Opt_default_permissions:
627 config->default_permissions = true;
628 break;
629 case Opt_redirect_dir:
630 config->redirect_mode = result.uint_32;
631 if (config->redirect_mode == OVL_REDIRECT_OFF) {
632 config->redirect_mode = ovl_redirect_always_follow ?
633 OVL_REDIRECT_FOLLOW :
634 OVL_REDIRECT_NOFOLLOW;
635 }
636 ctx->set.redirect = true;
637 break;
638 case Opt_index:
639 config->index = result.uint_32;
640 ctx->set.index = true;
641 break;
642 case Opt_uuid:
643 config->uuid = result.uint_32;
644 break;
645 case Opt_nfs_export:
646 config->nfs_export = result.uint_32;
647 ctx->set.nfs_export = true;
648 break;
649 case Opt_xino:
650 config->xino = result.uint_32;
651 break;
652 case Opt_metacopy:
653 config->metacopy = result.uint_32;
654 ctx->set.metacopy = true;
655 break;
656 case Opt_verity:
657 config->verity_mode = result.uint_32;
658 break;
659 case Opt_volatile:
660 config->ovl_volatile = true;
661 break;
662 case Opt_userxattr:
663 config->userxattr = true;
664 break;
665 default:
666 pr_err("unrecognized mount option \"%s\" or missing value\n",
667 param->key);
668 return -EINVAL;
669 }
670
671 return err;
672}
673
674static int ovl_get_tree(struct fs_context *fc)
675{
676 return get_tree_nodev(fc, ovl_fill_super);
677}
678
679static inline void ovl_fs_context_free(struct ovl_fs_context *ctx)
680{
681 ovl_reset_lowerdirs(ctx);
682 path_put(&ctx->upper);
683 path_put(&ctx->work);
684 kfree(ctx->lower);
685 kfree(ctx);
686}
687
688static void ovl_free(struct fs_context *fc)
689{
690 struct ovl_fs *ofs = fc->s_fs_info;
691 struct ovl_fs_context *ctx = fc->fs_private;
692
693 /*
694 * ofs is stored in the fs_context when it is initialized.
695 * ofs is transferred to the superblock on a successful mount,
696 * but if an error occurs before the transfer we have to free
697 * it here.
698 */
699 if (ofs)
700 ovl_free_fs(ofs);
701
702 if (ctx)
703 ovl_fs_context_free(ctx);
704}
705
706static int ovl_reconfigure(struct fs_context *fc)
707{
708 struct super_block *sb = fc->root->d_sb;
709 struct ovl_fs *ofs = OVL_FS(sb);
710 struct super_block *upper_sb;
711 int ret = 0;
712
713 if (!(fc->sb_flags & SB_RDONLY) && ovl_force_readonly(ofs))
714 return -EROFS;
715
716 if (fc->sb_flags & SB_RDONLY && !sb_rdonly(sb)) {
717 upper_sb = ovl_upper_mnt(ofs)->mnt_sb;
718 if (ovl_should_sync(ofs)) {
719 down_read(&upper_sb->s_umount);
720 ret = sync_filesystem(upper_sb);
721 up_read(&upper_sb->s_umount);
722 }
723 }
724
725 return ret;
726}
727
728static const struct fs_context_operations ovl_context_ops = {
729 .parse_monolithic = ovl_parse_monolithic,
730 .parse_param = ovl_parse_param,
731 .get_tree = ovl_get_tree,
732 .reconfigure = ovl_reconfigure,
733 .free = ovl_free,
734};
735
736/*
737 * This is called during fsopen() and will record the user namespace of
738 * the caller in fc->user_ns since we've raised FS_USERNS_MOUNT. We'll
739 * need it when we actually create the superblock to verify that the
740 * process creating the superblock is in the same user namespace as
741 * process that called fsopen().
742 */
743int ovl_init_fs_context(struct fs_context *fc)
744{
745 struct ovl_fs_context *ctx;
746 struct ovl_fs *ofs;
747
748 ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT);
749 if (!ctx)
750 return -ENOMEM;
751
752 /*
753 * By default we allocate for three lower layers. It's likely
754 * that it'll cover most users.
755 */
756 ctx->lower = kmalloc_array(3, sizeof(*ctx->lower), GFP_KERNEL_ACCOUNT);
757 if (!ctx->lower)
758 goto out_err;
759 ctx->capacity = 3;
760
761 ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
762 if (!ofs)
763 goto out_err;
764
765 ofs->config.redirect_mode = ovl_redirect_mode_def();
766 ofs->config.index = ovl_index_def;
767 ofs->config.uuid = ovl_uuid_def();
768 ofs->config.nfs_export = ovl_nfs_export_def;
769 ofs->config.xino = ovl_xino_def();
770 ofs->config.metacopy = ovl_metacopy_def;
771
772 fc->s_fs_info = ofs;
773 fc->fs_private = ctx;
774 fc->ops = &ovl_context_ops;
775 return 0;
776
777out_err:
778 ovl_fs_context_free(ctx);
779 return -ENOMEM;
780
781}
782
783void ovl_free_fs(struct ovl_fs *ofs)
784{
785 struct vfsmount **mounts;
786 unsigned i;
787
788 iput(ofs->workbasedir_trap);
789 iput(ofs->workdir_trap);
790 dput(ofs->whiteout);
791 dput(ofs->workdir);
792 if (ofs->workdir_locked)
793 ovl_inuse_unlock(ofs->workbasedir);
794 dput(ofs->workbasedir);
795 if (ofs->upperdir_locked)
796 ovl_inuse_unlock(ovl_upper_mnt(ofs)->mnt_root);
797
798 /* Reuse ofs->config.lowerdirs as a vfsmount array before freeing it */
799 mounts = (struct vfsmount **) ofs->config.lowerdirs;
800 for (i = 0; i < ofs->numlayer; i++) {
801 iput(ofs->layers[i].trap);
802 kfree(ofs->config.lowerdirs[i]);
803 mounts[i] = ofs->layers[i].mnt;
804 }
805 kern_unmount_array(mounts, ofs->numlayer);
806 kfree(ofs->layers);
807 for (i = 0; i < ofs->numfs; i++)
808 free_anon_bdev(ofs->fs[i].pseudo_dev);
809 kfree(ofs->fs);
810
811 kfree(ofs->config.lowerdirs);
812 kfree(ofs->config.upperdir);
813 kfree(ofs->config.workdir);
814 if (ofs->creator_cred)
815 put_cred(ofs->creator_cred);
816 kfree(ofs);
817}
818
819int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
820 struct ovl_config *config)
821{
822 struct ovl_opt_set set = ctx->set;
823
824 /* Workdir/index are useless in non-upper mount */
825 if (!config->upperdir) {
826 if (config->workdir) {
827 pr_info("option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
828 config->workdir);
829 kfree(config->workdir);
830 config->workdir = NULL;
831 }
832 if (config->index && set.index) {
833 pr_info("option \"index=on\" is useless in a non-upper mount, ignore\n");
834 set.index = false;
835 }
836 config->index = false;
837 }
838
839 if (!config->upperdir && config->ovl_volatile) {
840 pr_info("option \"volatile\" is meaningless in a non-upper mount, ignoring it.\n");
841 config->ovl_volatile = false;
842 }
843
844 if (!config->upperdir && config->uuid == OVL_UUID_ON) {
845 pr_info("option \"uuid=on\" requires an upper fs, falling back to uuid=null.\n");
846 config->uuid = OVL_UUID_NULL;
847 }
848
849 /* Resolve verity -> metacopy dependency */
850 if (config->verity_mode && !config->metacopy) {
851 /* Don't allow explicit specified conflicting combinations */
852 if (set.metacopy) {
853 pr_err("conflicting options: metacopy=off,verity=%s\n",
854 ovl_verity_mode(config));
855 return -EINVAL;
856 }
857 /* Otherwise automatically enable metacopy. */
858 config->metacopy = true;
859 }
860
861 /*
862 * This is to make the logic below simpler. It doesn't make any other
863 * difference, since redirect_dir=on is only used for upper.
864 */
865 if (!config->upperdir && config->redirect_mode == OVL_REDIRECT_FOLLOW)
866 config->redirect_mode = OVL_REDIRECT_ON;
867
868 /* Resolve verity -> metacopy -> redirect_dir dependency */
869 if (config->metacopy && config->redirect_mode != OVL_REDIRECT_ON) {
870 if (set.metacopy && set.redirect) {
871 pr_err("conflicting options: metacopy=on,redirect_dir=%s\n",
872 ovl_redirect_mode(config));
873 return -EINVAL;
874 }
875 if (config->verity_mode && set.redirect) {
876 pr_err("conflicting options: verity=%s,redirect_dir=%s\n",
877 ovl_verity_mode(config), ovl_redirect_mode(config));
878 return -EINVAL;
879 }
880 if (set.redirect) {
881 /*
882 * There was an explicit redirect_dir=... that resulted
883 * in this conflict.
884 */
885 pr_info("disabling metacopy due to redirect_dir=%s\n",
886 ovl_redirect_mode(config));
887 config->metacopy = false;
888 } else {
889 /* Automatically enable redirect otherwise. */
890 config->redirect_mode = OVL_REDIRECT_ON;
891 }
892 }
893
894 /* Resolve nfs_export -> index dependency */
895 if (config->nfs_export && !config->index) {
896 if (!config->upperdir &&
897 config->redirect_mode != OVL_REDIRECT_NOFOLLOW) {
898 pr_info("NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n");
899 config->nfs_export = false;
900 } else if (set.nfs_export && set.index) {
901 pr_err("conflicting options: nfs_export=on,index=off\n");
902 return -EINVAL;
903 } else if (set.index) {
904 /*
905 * There was an explicit index=off that resulted
906 * in this conflict.
907 */
908 pr_info("disabling nfs_export due to index=off\n");
909 config->nfs_export = false;
910 } else {
911 /* Automatically enable index otherwise. */
912 config->index = true;
913 }
914 }
915
916 /* Resolve nfs_export -> !metacopy && !verity dependency */
917 if (config->nfs_export && config->metacopy) {
918 if (set.nfs_export && set.metacopy) {
919 pr_err("conflicting options: nfs_export=on,metacopy=on\n");
920 return -EINVAL;
921 }
922 if (set.metacopy) {
923 /*
924 * There was an explicit metacopy=on that resulted
925 * in this conflict.
926 */
927 pr_info("disabling nfs_export due to metacopy=on\n");
928 config->nfs_export = false;
929 } else if (config->verity_mode) {
930 /*
931 * There was an explicit verity=.. that resulted
932 * in this conflict.
933 */
934 pr_info("disabling nfs_export due to verity=%s\n",
935 ovl_verity_mode(config));
936 config->nfs_export = false;
937 } else {
938 /*
939 * There was an explicit nfs_export=on that resulted
940 * in this conflict.
941 */
942 pr_info("disabling metacopy due to nfs_export=on\n");
943 config->metacopy = false;
944 }
945 }
946
947
948 /* Resolve userxattr -> !redirect && !metacopy && !verity dependency */
949 if (config->userxattr) {
950 if (set.redirect &&
951 config->redirect_mode != OVL_REDIRECT_NOFOLLOW) {
952 pr_err("conflicting options: userxattr,redirect_dir=%s\n",
953 ovl_redirect_mode(config));
954 return -EINVAL;
955 }
956 if (config->metacopy && set.metacopy) {
957 pr_err("conflicting options: userxattr,metacopy=on\n");
958 return -EINVAL;
959 }
960 if (config->verity_mode) {
961 pr_err("conflicting options: userxattr,verity=%s\n",
962 ovl_verity_mode(config));
963 return -EINVAL;
964 }
965 /*
966 * Silently disable default setting of redirect and metacopy.
967 * This shall be the default in the future as well: these
968 * options must be explicitly enabled if used together with
969 * userxattr.
970 */
971 config->redirect_mode = OVL_REDIRECT_NOFOLLOW;
972 config->metacopy = false;
973 }
974
975 /*
976 * Fail if we don't have trusted xattr capability and a feature was
977 * explicitly requested that requires them.
978 */
979 if (!config->userxattr && !capable(CAP_SYS_ADMIN)) {
980 if (set.redirect &&
981 config->redirect_mode != OVL_REDIRECT_NOFOLLOW) {
982 pr_err("redirect_dir requires permission to access trusted xattrs\n");
983 return -EPERM;
984 }
985 if (config->metacopy && set.metacopy) {
986 pr_err("metacopy requires permission to access trusted xattrs\n");
987 return -EPERM;
988 }
989 if (config->verity_mode) {
990 pr_err("verity requires permission to access trusted xattrs\n");
991 return -EPERM;
992 }
993 if (ctx->nr_data > 0) {
994 pr_err("lower data-only dirs require permission to access trusted xattrs\n");
995 return -EPERM;
996 }
997 /*
998 * Other xattr-dependent features should be disabled without
999 * great disturbance to the user in ovl_make_workdir().
1000 */
1001 }
1002
1003 if (ctx->nr_data > 0 && !config->metacopy) {
1004 pr_err("lower data-only dirs require metacopy support.\n");
1005 return -EINVAL;
1006 }
1007
1008 return 0;
1009}
1010
1011/**
1012 * ovl_show_options
1013 * @m: the seq_file handle
1014 * @dentry: The dentry to query
1015 *
1016 * Prints the mount options for a given superblock.
1017 * Returns zero; does not fail.
1018 */
1019int ovl_show_options(struct seq_file *m, struct dentry *dentry)
1020{
1021 struct super_block *sb = dentry->d_sb;
1022 struct ovl_fs *ofs = OVL_FS(sb);
1023 size_t nr, nr_merged_lower, nr_lower = 0;
1024 char **lowerdirs = ofs->config.lowerdirs;
1025
1026 /*
1027 * lowerdirs[0] holds the colon separated list that user provided
1028 * with lowerdir mount option.
1029 * lowerdirs[1..numlayer] hold the lowerdir paths that were added
1030 * using the lowerdir+ and datadir+ mount options.
1031 * For now, we do not allow mixing the legacy lowerdir mount option
1032 * with the new lowerdir+ and datadir+ mount options.
1033 */
1034 if (lowerdirs[0]) {
1035 seq_show_option(m, "lowerdir", lowerdirs[0]);
1036 } else {
1037 nr_lower = ofs->numlayer;
1038 nr_merged_lower = nr_lower - ofs->numdatalayer;
1039 }
1040 for (nr = 1; nr < nr_lower; nr++) {
1041 if (nr < nr_merged_lower)
1042 seq_show_option(m, "lowerdir+", lowerdirs[nr]);
1043 else
1044 seq_show_option(m, "datadir+", lowerdirs[nr]);
1045 }
1046 if (ofs->config.upperdir) {
1047 seq_show_option(m, "upperdir", ofs->config.upperdir);
1048 seq_show_option(m, "workdir", ofs->config.workdir);
1049 }
1050 if (ofs->config.default_permissions)
1051 seq_puts(m, ",default_permissions");
1052 if (ofs->config.redirect_mode != ovl_redirect_mode_def())
1053 seq_printf(m, ",redirect_dir=%s",
1054 ovl_redirect_mode(&ofs->config));
1055 if (ofs->config.index != ovl_index_def)
1056 seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off");
1057 if (ofs->config.uuid != ovl_uuid_def())
1058 seq_printf(m, ",uuid=%s", ovl_uuid_mode(&ofs->config));
1059 if (ofs->config.nfs_export != ovl_nfs_export_def)
1060 seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ?
1061 "on" : "off");
1062 if (ofs->config.xino != ovl_xino_def() && !ovl_same_fs(ofs))
1063 seq_printf(m, ",xino=%s", ovl_xino_mode(&ofs->config));
1064 if (ofs->config.metacopy != ovl_metacopy_def)
1065 seq_printf(m, ",metacopy=%s",
1066 ofs->config.metacopy ? "on" : "off");
1067 if (ofs->config.ovl_volatile)
1068 seq_puts(m, ",volatile");
1069 if (ofs->config.userxattr)
1070 seq_puts(m, ",userxattr");
1071 if (ofs->config.verity_mode != ovl_verity_mode_def())
1072 seq_printf(m, ",verity=%s",
1073 ovl_verity_mode(&ofs->config));
1074 return 0;
1075}