Commit | Line | Data |
---|---|---|
b4d0d230 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
9bc61ab1 DH |
2 | /* Provide a way to create a superblock configuration context within the kernel |
3 | * that allows a superblock to be set up prior to mounting. | |
4 | * | |
5 | * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved. | |
6 | * Written by David Howells (dhowells@redhat.com) | |
9bc61ab1 DH |
7 | */ |
8 | ||
9 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
007ec26c | 10 | #include <linux/module.h> |
9bc61ab1 | 11 | #include <linux/fs_context.h> |
3e1aeb00 | 12 | #include <linux/fs_parser.h> |
9bc61ab1 DH |
13 | #include <linux/fs.h> |
14 | #include <linux/mount.h> | |
15 | #include <linux/nsproxy.h> | |
16 | #include <linux/slab.h> | |
17 | #include <linux/magic.h> | |
18 | #include <linux/security.h> | |
19 | #include <linux/mnt_namespace.h> | |
20 | #include <linux/pid_namespace.h> | |
21 | #include <linux/user_namespace.h> | |
22 | #include <net/net_namespace.h> | |
007ec26c | 23 | #include <asm/sections.h> |
9bc61ab1 DH |
24 | #include "mount.h" |
25 | #include "internal.h" | |
26 | ||
3e1aeb00 DH |
27 | enum legacy_fs_param { |
28 | LEGACY_FS_UNSET_PARAMS, | |
29 | LEGACY_FS_MONOLITHIC_PARAMS, | |
30 | LEGACY_FS_INDIVIDUAL_PARAMS, | |
31 | }; | |
32 | ||
9bc61ab1 DH |
33 | struct legacy_fs_context { |
34 | char *legacy_data; /* Data page for legacy filesystems */ | |
35 | size_t data_size; | |
3e1aeb00 | 36 | enum legacy_fs_param param_type; |
9bc61ab1 DH |
37 | }; |
38 | ||
39 | static int legacy_init_fs_context(struct fs_context *fc); | |
40 | ||
3e1aeb00 DH |
41 | static const struct constant_table common_set_sb_flag[] = { |
42 | { "dirsync", SB_DIRSYNC }, | |
43 | { "lazytime", SB_LAZYTIME }, | |
44 | { "mand", SB_MANDLOCK }, | |
45 | { "posixacl", SB_POSIXACL }, | |
46 | { "ro", SB_RDONLY }, | |
47 | { "sync", SB_SYNCHRONOUS }, | |
48 | }; | |
49 | ||
50 | static const struct constant_table common_clear_sb_flag[] = { | |
51 | { "async", SB_SYNCHRONOUS }, | |
52 | { "nolazytime", SB_LAZYTIME }, | |
53 | { "nomand", SB_MANDLOCK }, | |
54 | { "rw", SB_RDONLY }, | |
55 | { "silent", SB_SILENT }, | |
56 | }; | |
57 | ||
58 | static const char *const forbidden_sb_flag[] = { | |
59 | "bind", | |
60 | "dev", | |
61 | "exec", | |
62 | "move", | |
63 | "noatime", | |
64 | "nodev", | |
65 | "nodiratime", | |
66 | "noexec", | |
67 | "norelatime", | |
68 | "nostrictatime", | |
69 | "nosuid", | |
70 | "private", | |
71 | "rec", | |
72 | "relatime", | |
73 | "remount", | |
74 | "shared", | |
75 | "slave", | |
76 | "strictatime", | |
77 | "suid", | |
78 | "unbindable", | |
79 | }; | |
80 | ||
81 | /* | |
82 | * Check for a common mount option that manipulates s_flags. | |
83 | */ | |
84 | static int vfs_parse_sb_flag(struct fs_context *fc, const char *key) | |
85 | { | |
86 | unsigned int token; | |
87 | unsigned int i; | |
88 | ||
89 | for (i = 0; i < ARRAY_SIZE(forbidden_sb_flag); i++) | |
90 | if (strcmp(key, forbidden_sb_flag[i]) == 0) | |
91 | return -EINVAL; | |
92 | ||
93 | token = lookup_constant(common_set_sb_flag, key, 0); | |
94 | if (token) { | |
95 | fc->sb_flags |= token; | |
96 | fc->sb_flags_mask |= token; | |
97 | return 0; | |
98 | } | |
99 | ||
100 | token = lookup_constant(common_clear_sb_flag, key, 0); | |
101 | if (token) { | |
102 | fc->sb_flags &= ~token; | |
103 | fc->sb_flags_mask |= token; | |
104 | return 0; | |
105 | } | |
106 | ||
107 | return -ENOPARAM; | |
108 | } | |
109 | ||
110 | /** | |
111 | * vfs_parse_fs_param - Add a single parameter to a superblock config | |
112 | * @fc: The filesystem context to modify | |
113 | * @param: The parameter | |
114 | * | |
115 | * A single mount option in string form is applied to the filesystem context | |
116 | * being set up. Certain standard options (for example "ro") are translated | |
117 | * into flag bits without going to the filesystem. The active security module | |
118 | * is allowed to observe and poach options. Any other options are passed over | |
119 | * to the filesystem to parse. | |
120 | * | |
121 | * This may be called multiple times for a context. | |
122 | * | |
123 | * Returns 0 on success and a negative error code on failure. In the event of | |
124 | * failure, supplementary error information may have been set. | |
125 | */ | |
126 | int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param) | |
127 | { | |
128 | int ret; | |
129 | ||
130 | if (!param->key) | |
131 | return invalf(fc, "Unnamed parameter\n"); | |
132 | ||
133 | ret = vfs_parse_sb_flag(fc, param->key); | |
134 | if (ret != -ENOPARAM) | |
135 | return ret; | |
136 | ||
137 | ret = security_fs_context_parse_param(fc, param); | |
138 | if (ret != -ENOPARAM) | |
139 | /* Param belongs to the LSM or is disallowed by the LSM; so | |
140 | * don't pass to the FS. | |
141 | */ | |
142 | return ret; | |
143 | ||
144 | if (fc->ops->parse_param) { | |
145 | ret = fc->ops->parse_param(fc, param); | |
146 | if (ret != -ENOPARAM) | |
147 | return ret; | |
148 | } | |
149 | ||
150 | /* If the filesystem doesn't take any arguments, give it the | |
151 | * default handling of source. | |
152 | */ | |
153 | if (strcmp(param->key, "source") == 0) { | |
154 | if (param->type != fs_value_is_string) | |
155 | return invalf(fc, "VFS: Non-string source"); | |
156 | if (fc->source) | |
157 | return invalf(fc, "VFS: Multiple sources"); | |
158 | fc->source = param->string; | |
159 | param->string = NULL; | |
160 | return 0; | |
161 | } | |
162 | ||
163 | return invalf(fc, "%s: Unknown parameter '%s'", | |
164 | fc->fs_type->name, param->key); | |
165 | } | |
166 | EXPORT_SYMBOL(vfs_parse_fs_param); | |
167 | ||
168 | /** | |
169 | * vfs_parse_fs_string - Convenience function to just parse a string. | |
170 | */ | |
171 | int vfs_parse_fs_string(struct fs_context *fc, const char *key, | |
172 | const char *value, size_t v_size) | |
173 | { | |
174 | int ret; | |
175 | ||
176 | struct fs_parameter param = { | |
177 | .key = key, | |
178 | .type = fs_value_is_string, | |
179 | .size = v_size, | |
180 | }; | |
181 | ||
182 | if (v_size > 0) { | |
183 | param.string = kmemdup_nul(value, v_size, GFP_KERNEL); | |
184 | if (!param.string) | |
185 | return -ENOMEM; | |
186 | } | |
187 | ||
188 | ret = vfs_parse_fs_param(fc, ¶m); | |
189 | kfree(param.string); | |
190 | return ret; | |
191 | } | |
192 | EXPORT_SYMBOL(vfs_parse_fs_string); | |
193 | ||
194 | /** | |
195 | * generic_parse_monolithic - Parse key[=val][,key[=val]]* mount data | |
196 | * @ctx: The superblock configuration to fill in. | |
197 | * @data: The data to parse | |
198 | * | |
199 | * Parse a blob of data that's in key[=val][,key[=val]]* form. This can be | |
200 | * called from the ->monolithic_mount_data() fs_context operation. | |
201 | * | |
202 | * Returns 0 on success or the error returned by the ->parse_option() fs_context | |
203 | * operation on failure. | |
204 | */ | |
205 | int generic_parse_monolithic(struct fs_context *fc, void *data) | |
206 | { | |
207 | char *options = data, *key; | |
208 | int ret = 0; | |
209 | ||
210 | if (!options) | |
211 | return 0; | |
212 | ||
213 | ret = security_sb_eat_lsm_opts(options, &fc->security); | |
214 | if (ret) | |
215 | return ret; | |
216 | ||
217 | while ((key = strsep(&options, ",")) != NULL) { | |
218 | if (*key) { | |
219 | size_t v_len = 0; | |
220 | char *value = strchr(key, '='); | |
221 | ||
222 | if (value) { | |
223 | if (value == key) | |
224 | continue; | |
225 | *value++ = 0; | |
226 | v_len = strlen(value); | |
227 | } | |
228 | ret = vfs_parse_fs_string(fc, key, value, v_len); | |
229 | if (ret < 0) | |
230 | break; | |
231 | } | |
232 | } | |
233 | ||
234 | return ret; | |
235 | } | |
236 | EXPORT_SYMBOL(generic_parse_monolithic); | |
237 | ||
9bc61ab1 DH |
238 | /** |
239 | * alloc_fs_context - Create a filesystem context. | |
240 | * @fs_type: The filesystem type. | |
241 | * @reference: The dentry from which this one derives (or NULL) | |
242 | * @sb_flags: Filesystem/superblock flags (SB_*) | |
243 | * @sb_flags_mask: Applicable members of @sb_flags | |
244 | * @purpose: The purpose that this configuration shall be used for. | |
245 | * | |
246 | * Open a filesystem and create a mount context. The mount context is | |
247 | * initialised with the supplied flags and, if a submount/automount from | |
248 | * another superblock (referred to by @reference) is supplied, may have | |
249 | * parameters such as namespaces copied across from that superblock. | |
250 | */ | |
251 | static struct fs_context *alloc_fs_context(struct file_system_type *fs_type, | |
252 | struct dentry *reference, | |
253 | unsigned int sb_flags, | |
254 | unsigned int sb_flags_mask, | |
255 | enum fs_context_purpose purpose) | |
256 | { | |
f3a09c92 | 257 | int (*init_fs_context)(struct fs_context *); |
9bc61ab1 DH |
258 | struct fs_context *fc; |
259 | int ret = -ENOMEM; | |
260 | ||
261 | fc = kzalloc(sizeof(struct fs_context), GFP_KERNEL); | |
262 | if (!fc) | |
263 | return ERR_PTR(-ENOMEM); | |
264 | ||
265 | fc->purpose = purpose; | |
266 | fc->sb_flags = sb_flags; | |
267 | fc->sb_flags_mask = sb_flags_mask; | |
268 | fc->fs_type = get_filesystem(fs_type); | |
269 | fc->cred = get_current_cred(); | |
270 | fc->net_ns = get_net(current->nsproxy->net_ns); | |
271 | ||
24dcb3d9 DH |
272 | mutex_init(&fc->uapi_mutex); |
273 | ||
9bc61ab1 DH |
274 | switch (purpose) { |
275 | case FS_CONTEXT_FOR_MOUNT: | |
276 | fc->user_ns = get_user_ns(fc->cred->user_ns); | |
277 | break; | |
e1a91586 AV |
278 | case FS_CONTEXT_FOR_SUBMOUNT: |
279 | fc->user_ns = get_user_ns(reference->d_sb->s_user_ns); | |
280 | break; | |
8d0347f6 | 281 | case FS_CONTEXT_FOR_RECONFIGURE: |
8d0347f6 | 282 | atomic_inc(&reference->d_sb->s_active); |
1dd9bc08 | 283 | fc->user_ns = get_user_ns(reference->d_sb->s_user_ns); |
8d0347f6 DH |
284 | fc->root = dget(reference); |
285 | break; | |
9bc61ab1 DH |
286 | } |
287 | ||
f3a09c92 AV |
288 | /* TODO: Make all filesystems support this unconditionally */ |
289 | init_fs_context = fc->fs_type->init_fs_context; | |
290 | if (!init_fs_context) | |
291 | init_fs_context = legacy_init_fs_context; | |
292 | ||
293 | ret = init_fs_context(fc); | |
9bc61ab1 DH |
294 | if (ret < 0) |
295 | goto err_fc; | |
296 | fc->need_free = true; | |
297 | return fc; | |
298 | ||
299 | err_fc: | |
300 | put_fs_context(fc); | |
301 | return ERR_PTR(ret); | |
302 | } | |
303 | ||
304 | struct fs_context *fs_context_for_mount(struct file_system_type *fs_type, | |
305 | unsigned int sb_flags) | |
306 | { | |
307 | return alloc_fs_context(fs_type, NULL, sb_flags, 0, | |
308 | FS_CONTEXT_FOR_MOUNT); | |
309 | } | |
310 | EXPORT_SYMBOL(fs_context_for_mount); | |
311 | ||
8d0347f6 DH |
312 | struct fs_context *fs_context_for_reconfigure(struct dentry *dentry, |
313 | unsigned int sb_flags, | |
314 | unsigned int sb_flags_mask) | |
315 | { | |
316 | return alloc_fs_context(dentry->d_sb->s_type, dentry, sb_flags, | |
317 | sb_flags_mask, FS_CONTEXT_FOR_RECONFIGURE); | |
318 | } | |
319 | EXPORT_SYMBOL(fs_context_for_reconfigure); | |
320 | ||
e1a91586 AV |
321 | struct fs_context *fs_context_for_submount(struct file_system_type *type, |
322 | struct dentry *reference) | |
323 | { | |
324 | return alloc_fs_context(type, reference, 0, 0, FS_CONTEXT_FOR_SUBMOUNT); | |
325 | } | |
326 | EXPORT_SYMBOL(fs_context_for_submount); | |
327 | ||
c9ce29ed AV |
328 | void fc_drop_locked(struct fs_context *fc) |
329 | { | |
330 | struct super_block *sb = fc->root->d_sb; | |
331 | dput(fc->root); | |
332 | fc->root = NULL; | |
333 | deactivate_locked_super(sb); | |
334 | } | |
335 | ||
9bc61ab1 | 336 | static void legacy_fs_context_free(struct fs_context *fc); |
8d0347f6 | 337 | |
0b52075e AV |
338 | /** |
339 | * vfs_dup_fc_config: Duplicate a filesystem context. | |
340 | * @src_fc: The context to copy. | |
341 | */ | |
342 | struct fs_context *vfs_dup_fs_context(struct fs_context *src_fc) | |
343 | { | |
344 | struct fs_context *fc; | |
345 | int ret; | |
346 | ||
347 | if (!src_fc->ops->dup) | |
348 | return ERR_PTR(-EOPNOTSUPP); | |
349 | ||
350 | fc = kmemdup(src_fc, sizeof(struct fs_context), GFP_KERNEL); | |
351 | if (!fc) | |
352 | return ERR_PTR(-ENOMEM); | |
353 | ||
24dcb3d9 DH |
354 | mutex_init(&fc->uapi_mutex); |
355 | ||
0b52075e AV |
356 | fc->fs_private = NULL; |
357 | fc->s_fs_info = NULL; | |
358 | fc->source = NULL; | |
359 | fc->security = NULL; | |
360 | get_filesystem(fc->fs_type); | |
361 | get_net(fc->net_ns); | |
362 | get_user_ns(fc->user_ns); | |
363 | get_cred(fc->cred); | |
007ec26c DH |
364 | if (fc->log) |
365 | refcount_inc(&fc->log->usage); | |
0b52075e AV |
366 | |
367 | /* Can't call put until we've called ->dup */ | |
368 | ret = fc->ops->dup(fc, src_fc); | |
369 | if (ret < 0) | |
370 | goto err_fc; | |
371 | ||
372 | ret = security_fs_context_dup(fc, src_fc); | |
373 | if (ret < 0) | |
374 | goto err_fc; | |
375 | return fc; | |
376 | ||
377 | err_fc: | |
378 | put_fs_context(fc); | |
379 | return ERR_PTR(ret); | |
380 | } | |
381 | EXPORT_SYMBOL(vfs_dup_fs_context); | |
382 | ||
e7582e16 DH |
383 | /** |
384 | * logfc - Log a message to a filesystem context | |
385 | * @fc: The filesystem context to log to. | |
386 | * @fmt: The format of the buffer. | |
387 | */ | |
388 | void logfc(struct fs_context *fc, const char *fmt, ...) | |
389 | { | |
007ec26c DH |
390 | static const char store_failure[] = "OOM: Can't store error string"; |
391 | struct fc_log *log = fc ? fc->log : NULL; | |
392 | const char *p; | |
e7582e16 | 393 | va_list va; |
007ec26c DH |
394 | char *q; |
395 | u8 freeable; | |
e7582e16 DH |
396 | |
397 | va_start(va, fmt); | |
007ec26c DH |
398 | if (!strchr(fmt, '%')) { |
399 | p = fmt; | |
400 | goto unformatted_string; | |
e7582e16 | 401 | } |
007ec26c DH |
402 | if (strcmp(fmt, "%s") == 0) { |
403 | p = va_arg(va, const char *); | |
404 | goto unformatted_string; | |
405 | } | |
406 | ||
407 | q = kvasprintf(GFP_KERNEL, fmt, va); | |
408 | copied_string: | |
409 | if (!q) | |
410 | goto store_failure; | |
411 | freeable = 1; | |
412 | goto store_string; | |
413 | ||
414 | unformatted_string: | |
415 | if ((unsigned long)p >= (unsigned long)__start_rodata && | |
416 | (unsigned long)p < (unsigned long)__end_rodata) | |
417 | goto const_string; | |
418 | if (log && within_module_core((unsigned long)p, log->owner)) | |
419 | goto const_string; | |
420 | q = kstrdup(p, GFP_KERNEL); | |
421 | goto copied_string; | |
422 | ||
423 | store_failure: | |
424 | p = store_failure; | |
425 | const_string: | |
426 | q = (char *)p; | |
427 | freeable = 0; | |
428 | store_string: | |
429 | if (!log) { | |
430 | switch (fmt[0]) { | |
431 | case 'w': | |
432 | printk(KERN_WARNING "%s\n", q + 2); | |
433 | break; | |
434 | case 'e': | |
435 | printk(KERN_ERR "%s\n", q + 2); | |
436 | break; | |
437 | default: | |
438 | printk(KERN_NOTICE "%s\n", q + 2); | |
439 | break; | |
440 | } | |
441 | if (freeable) | |
442 | kfree(q); | |
443 | } else { | |
444 | unsigned int logsize = ARRAY_SIZE(log->buffer); | |
445 | u8 index; | |
446 | ||
447 | index = log->head & (logsize - 1); | |
448 | BUILD_BUG_ON(sizeof(log->head) != sizeof(u8) || | |
449 | sizeof(log->tail) != sizeof(u8)); | |
450 | if ((u8)(log->head - log->tail) == logsize) { | |
451 | /* The buffer is full, discard the oldest message */ | |
452 | if (log->need_free & (1 << index)) | |
453 | kfree(log->buffer[index]); | |
454 | log->tail++; | |
455 | } | |
e7582e16 | 456 | |
007ec26c DH |
457 | log->buffer[index] = q; |
458 | log->need_free &= ~(1 << index); | |
459 | log->need_free |= freeable << index; | |
460 | log->head++; | |
461 | } | |
e7582e16 DH |
462 | va_end(va); |
463 | } | |
464 | EXPORT_SYMBOL(logfc); | |
007ec26c DH |
465 | |
466 | /* | |
467 | * Free a logging structure. | |
468 | */ | |
469 | static void put_fc_log(struct fs_context *fc) | |
470 | { | |
471 | struct fc_log *log = fc->log; | |
472 | int i; | |
473 | ||
474 | if (log) { | |
475 | if (refcount_dec_and_test(&log->usage)) { | |
476 | fc->log = NULL; | |
477 | for (i = 0; i <= 7; i++) | |
478 | if (log->need_free & (1 << i)) | |
479 | kfree(log->buffer[i]); | |
480 | kfree(log); | |
481 | } | |
482 | } | |
483 | } | |
e7582e16 | 484 | |
9bc61ab1 DH |
485 | /** |
486 | * put_fs_context - Dispose of a superblock configuration context. | |
487 | * @fc: The context to dispose of. | |
488 | */ | |
489 | void put_fs_context(struct fs_context *fc) | |
490 | { | |
491 | struct super_block *sb; | |
492 | ||
493 | if (fc->root) { | |
494 | sb = fc->root->d_sb; | |
495 | dput(fc->root); | |
496 | fc->root = NULL; | |
497 | deactivate_super(sb); | |
498 | } | |
499 | ||
f3a09c92 AV |
500 | if (fc->need_free && fc->ops && fc->ops->free) |
501 | fc->ops->free(fc); | |
9bc61ab1 DH |
502 | |
503 | security_free_mnt_opts(&fc->security); | |
8d0347f6 | 504 | put_net(fc->net_ns); |
9bc61ab1 DH |
505 | put_user_ns(fc->user_ns); |
506 | put_cred(fc->cred); | |
507 | kfree(fc->subtype); | |
007ec26c | 508 | put_fc_log(fc); |
9bc61ab1 DH |
509 | put_filesystem(fc->fs_type); |
510 | kfree(fc->source); | |
511 | kfree(fc); | |
512 | } | |
513 | EXPORT_SYMBOL(put_fs_context); | |
514 | ||
515 | /* | |
516 | * Free the config for a filesystem that doesn't support fs_context. | |
517 | */ | |
518 | static void legacy_fs_context_free(struct fs_context *fc) | |
519 | { | |
3e1aeb00 DH |
520 | struct legacy_fs_context *ctx = fc->fs_private; |
521 | ||
522 | if (ctx) { | |
523 | if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS) | |
524 | kfree(ctx->legacy_data); | |
525 | kfree(ctx); | |
526 | } | |
527 | } | |
528 | ||
0b52075e AV |
529 | /* |
530 | * Duplicate a legacy config. | |
531 | */ | |
532 | static int legacy_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc) | |
533 | { | |
534 | struct legacy_fs_context *ctx; | |
535 | struct legacy_fs_context *src_ctx = src_fc->fs_private; | |
536 | ||
537 | ctx = kmemdup(src_ctx, sizeof(*src_ctx), GFP_KERNEL); | |
538 | if (!ctx) | |
539 | return -ENOMEM; | |
540 | ||
541 | if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS) { | |
542 | ctx->legacy_data = kmemdup(src_ctx->legacy_data, | |
543 | src_ctx->data_size, GFP_KERNEL); | |
544 | if (!ctx->legacy_data) { | |
545 | kfree(ctx); | |
546 | return -ENOMEM; | |
547 | } | |
548 | } | |
549 | ||
550 | fc->fs_private = ctx; | |
551 | return 0; | |
552 | } | |
553 | ||
3e1aeb00 DH |
554 | /* |
555 | * Add a parameter to a legacy config. We build up a comma-separated list of | |
556 | * options. | |
557 | */ | |
558 | static int legacy_parse_param(struct fs_context *fc, struct fs_parameter *param) | |
559 | { | |
560 | struct legacy_fs_context *ctx = fc->fs_private; | |
561 | unsigned int size = ctx->data_size; | |
562 | size_t len = 0; | |
563 | ||
564 | if (strcmp(param->key, "source") == 0) { | |
565 | if (param->type != fs_value_is_string) | |
566 | return invalf(fc, "VFS: Legacy: Non-string source"); | |
567 | if (fc->source) | |
568 | return invalf(fc, "VFS: Legacy: Multiple sources"); | |
569 | fc->source = param->string; | |
570 | param->string = NULL; | |
571 | return 0; | |
572 | } | |
573 | ||
574 | if ((fc->fs_type->fs_flags & FS_HAS_SUBTYPE) && | |
575 | strcmp(param->key, "subtype") == 0) { | |
576 | if (param->type != fs_value_is_string) | |
577 | return invalf(fc, "VFS: Legacy: Non-string subtype"); | |
578 | if (fc->subtype) | |
579 | return invalf(fc, "VFS: Legacy: Multiple subtype"); | |
580 | fc->subtype = param->string; | |
581 | param->string = NULL; | |
582 | return 0; | |
583 | } | |
584 | ||
585 | if (ctx->param_type == LEGACY_FS_MONOLITHIC_PARAMS) | |
586 | return invalf(fc, "VFS: Legacy: Can't mix monolithic and individual options"); | |
587 | ||
588 | switch (param->type) { | |
589 | case fs_value_is_string: | |
590 | len = 1 + param->size; | |
591 | /* Fall through */ | |
592 | case fs_value_is_flag: | |
593 | len += strlen(param->key); | |
594 | break; | |
595 | default: | |
596 | return invalf(fc, "VFS: Legacy: Parameter type for '%s' not supported", | |
597 | param->key); | |
598 | } | |
599 | ||
600 | if (len > PAGE_SIZE - 2 - size) | |
601 | return invalf(fc, "VFS: Legacy: Cumulative options too large"); | |
602 | if (strchr(param->key, ',') || | |
603 | (param->type == fs_value_is_string && | |
604 | memchr(param->string, ',', param->size))) | |
605 | return invalf(fc, "VFS: Legacy: Option '%s' contained comma", | |
606 | param->key); | |
607 | if (!ctx->legacy_data) { | |
608 | ctx->legacy_data = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
609 | if (!ctx->legacy_data) | |
610 | return -ENOMEM; | |
611 | } | |
612 | ||
613 | ctx->legacy_data[size++] = ','; | |
614 | len = strlen(param->key); | |
615 | memcpy(ctx->legacy_data + size, param->key, len); | |
616 | size += len; | |
617 | if (param->type == fs_value_is_string) { | |
618 | ctx->legacy_data[size++] = '='; | |
619 | memcpy(ctx->legacy_data + size, param->string, param->size); | |
620 | size += param->size; | |
621 | } | |
622 | ctx->legacy_data[size] = '\0'; | |
623 | ctx->data_size = size; | |
624 | ctx->param_type = LEGACY_FS_INDIVIDUAL_PARAMS; | |
625 | return 0; | |
9bc61ab1 DH |
626 | } |
627 | ||
628 | /* | |
629 | * Add monolithic mount data. | |
630 | */ | |
631 | static int legacy_parse_monolithic(struct fs_context *fc, void *data) | |
632 | { | |
633 | struct legacy_fs_context *ctx = fc->fs_private; | |
3e1aeb00 DH |
634 | |
635 | if (ctx->param_type != LEGACY_FS_UNSET_PARAMS) { | |
636 | pr_warn("VFS: Can't mix monolithic and individual options\n"); | |
637 | return -EINVAL; | |
638 | } | |
639 | ||
9bc61ab1 | 640 | ctx->legacy_data = data; |
3e1aeb00 | 641 | ctx->param_type = LEGACY_FS_MONOLITHIC_PARAMS; |
9bc61ab1 DH |
642 | if (!ctx->legacy_data) |
643 | return 0; | |
3e1aeb00 | 644 | |
9bc61ab1 DH |
645 | if (fc->fs_type->fs_flags & FS_BINARY_MOUNTDATA) |
646 | return 0; | |
647 | return security_sb_eat_lsm_opts(ctx->legacy_data, &fc->security); | |
648 | } | |
649 | ||
650 | /* | |
651 | * Get a mountable root with the legacy mount command. | |
652 | */ | |
f3a09c92 | 653 | static int legacy_get_tree(struct fs_context *fc) |
9bc61ab1 DH |
654 | { |
655 | struct legacy_fs_context *ctx = fc->fs_private; | |
656 | struct super_block *sb; | |
657 | struct dentry *root; | |
658 | ||
659 | root = fc->fs_type->mount(fc->fs_type, fc->sb_flags, | |
660 | fc->source, ctx->legacy_data); | |
661 | if (IS_ERR(root)) | |
662 | return PTR_ERR(root); | |
663 | ||
664 | sb = root->d_sb; | |
665 | BUG_ON(!sb); | |
666 | ||
667 | fc->root = root; | |
668 | return 0; | |
669 | } | |
670 | ||
8d0347f6 DH |
671 | /* |
672 | * Handle remount. | |
673 | */ | |
f3a09c92 | 674 | static int legacy_reconfigure(struct fs_context *fc) |
8d0347f6 DH |
675 | { |
676 | struct legacy_fs_context *ctx = fc->fs_private; | |
677 | struct super_block *sb = fc->root->d_sb; | |
678 | ||
679 | if (!sb->s_op->remount_fs) | |
680 | return 0; | |
681 | ||
682 | return sb->s_op->remount_fs(sb, &fc->sb_flags, | |
683 | ctx ? ctx->legacy_data : NULL); | |
684 | } | |
685 | ||
f3a09c92 AV |
686 | const struct fs_context_operations legacy_fs_context_ops = { |
687 | .free = legacy_fs_context_free, | |
0b52075e | 688 | .dup = legacy_fs_context_dup, |
3e1aeb00 | 689 | .parse_param = legacy_parse_param, |
f3a09c92 AV |
690 | .parse_monolithic = legacy_parse_monolithic, |
691 | .get_tree = legacy_get_tree, | |
692 | .reconfigure = legacy_reconfigure, | |
693 | }; | |
694 | ||
9bc61ab1 DH |
695 | /* |
696 | * Initialise a legacy context for a filesystem that doesn't support | |
697 | * fs_context. | |
698 | */ | |
699 | static int legacy_init_fs_context(struct fs_context *fc) | |
700 | { | |
701 | fc->fs_private = kzalloc(sizeof(struct legacy_fs_context), GFP_KERNEL); | |
702 | if (!fc->fs_private) | |
703 | return -ENOMEM; | |
f3a09c92 | 704 | fc->ops = &legacy_fs_context_ops; |
9bc61ab1 DH |
705 | return 0; |
706 | } | |
707 | ||
708 | int parse_monolithic_mount_data(struct fs_context *fc, void *data) | |
709 | { | |
f3a09c92 | 710 | int (*monolithic_mount_data)(struct fs_context *, void *); |
3e1aeb00 | 711 | |
f3a09c92 | 712 | monolithic_mount_data = fc->ops->parse_monolithic; |
3e1aeb00 DH |
713 | if (!monolithic_mount_data) |
714 | monolithic_mount_data = generic_parse_monolithic; | |
715 | ||
f3a09c92 | 716 | return monolithic_mount_data(fc, data); |
9bc61ab1 | 717 | } |
ecdab150 DH |
718 | |
719 | /* | |
720 | * Clean up a context after performing an action on it and put it into a state | |
721 | * from where it can be used to reconfigure a superblock. | |
722 | * | |
723 | * Note that here we do only the parts that can't fail; the rest is in | |
724 | * finish_clean_context() below and in between those fs_context is marked | |
725 | * FS_CONTEXT_AWAITING_RECONF. The reason for splitup is that after | |
726 | * successful mount or remount we need to report success to userland. | |
727 | * Trying to do full reinit (for the sake of possible subsequent remount) | |
728 | * and failing to allocate memory would've put us into a nasty situation. | |
729 | * So here we only discard the old state and reinitialization is left | |
730 | * until we actually try to reconfigure. | |
731 | */ | |
732 | void vfs_clean_context(struct fs_context *fc) | |
733 | { | |
734 | if (fc->need_free && fc->ops && fc->ops->free) | |
735 | fc->ops->free(fc); | |
736 | fc->need_free = false; | |
737 | fc->fs_private = NULL; | |
738 | fc->s_fs_info = NULL; | |
739 | fc->sb_flags = 0; | |
740 | security_free_mnt_opts(&fc->security); | |
741 | kfree(fc->subtype); | |
742 | fc->subtype = NULL; | |
743 | kfree(fc->source); | |
744 | fc->source = NULL; | |
745 | ||
746 | fc->purpose = FS_CONTEXT_FOR_RECONFIGURE; | |
747 | fc->phase = FS_CONTEXT_AWAITING_RECONF; | |
748 | } | |
749 | ||
750 | int finish_clean_context(struct fs_context *fc) | |
751 | { | |
752 | int error; | |
753 | ||
754 | if (fc->phase != FS_CONTEXT_AWAITING_RECONF) | |
755 | return 0; | |
756 | ||
757 | if (fc->fs_type->init_fs_context) | |
758 | error = fc->fs_type->init_fs_context(fc); | |
759 | else | |
760 | error = legacy_init_fs_context(fc); | |
761 | if (unlikely(error)) { | |
762 | fc->phase = FS_CONTEXT_FAILED; | |
763 | return error; | |
764 | } | |
765 | fc->need_free = true; | |
766 | fc->phase = FS_CONTEXT_RECONF_PARAMS; | |
767 | return 0; | |
768 | } |