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