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