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 static int vfs_parse_sb_flag(struct fs_context *fc, const char *key) 62 { 63 unsigned int token; 64 65 token = lookup_constant(common_set_sb_flag, key, 0); 66 if (token) { 67 fc->sb_flags |= token; 68 fc->sb_flags_mask |= token; 69 return 0; 70 } 71 72 token = lookup_constant(common_clear_sb_flag, key, 0); 73 if (token) { 74 fc->sb_flags &= ~token; 75 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 int vfs_parse_fs_param_source(struct fs_context *fc, struct fs_parameter *param) 95 { 96 if (strcmp(param->key, "source") != 0) 97 return -ENOPARAM; 98 99 if (param->type != fs_value_is_string) 100 return invalf(fc, "Non-string source"); 101 102 if (fc->source) 103 return invalf(fc, "Multiple sources"); 104 105 fc->source = param->string; 106 param->string = NULL; 107 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 int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param) 128 { 129 int ret; 130 131 if (!param->key) 132 return invalf(fc, "Unnamed parameter\n"); 133 134 ret = vfs_parse_sb_flag(fc, param->key); 135 if (ret != -ENOPARAM) 136 return ret; 137 138 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 if (fc->ops->parse_param) { 146 ret = fc->ops->parse_param(fc, param); 147 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 ret = vfs_parse_fs_param_source(fc, param); 155 if (ret != -ENOPARAM) 156 return ret; 157 158 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_qstr - Convenience function to just parse a string. 165 * @fc: Filesystem context. 166 * @key: Parameter name. 167 * @value: Default value. 168 */ 169 int vfs_parse_fs_qstr(struct fs_context *fc, const char *key, 170 const struct qstr *value) 171 { 172 int ret; 173 174 struct fs_parameter param = { 175 .key = key, 176 .type = fs_value_is_flag, 177 .size = value ? value->len : 0, 178 }; 179 180 if (value) { 181 param.string = kmemdup_nul(value->name, value->len, GFP_KERNEL); 182 if (!param.string) 183 return -ENOMEM; 184 param.type = fs_value_is_string; 185 } 186 187 ret = vfs_parse_fs_param(fc, ¶m); 188 kfree(param.string); 189 return ret; 190 } 191 EXPORT_SYMBOL(vfs_parse_fs_qstr); 192 193 /** 194 * vfs_parse_monolithic_sep - Parse key[=val][,key[=val]]* mount data 195 * @fc: The superblock configuration to fill in. 196 * @data: The data to parse 197 * @sep: callback for separating next option 198 * 199 * Parse a blob of data that's in key[=val][,key[=val]]* form with a custom 200 * option separator callback. 201 * 202 * Returns 0 on success or the error returned by the ->parse_option() fs_context 203 * operation on failure. 204 */ 205 int vfs_parse_monolithic_sep(struct fs_context *fc, void *data, 206 char *(*sep)(char **)) 207 { 208 char *options = data, *key; 209 int ret = 0; 210 211 if (!options) 212 return 0; 213 214 ret = security_sb_eat_lsm_opts(options, &fc->security); 215 if (ret) 216 return ret; 217 218 while ((key = sep(&options)) != NULL) { 219 if (*key) { 220 char *value = strchr(key, '='); 221 222 if (value) { 223 if (unlikely(value == key)) 224 continue; 225 *value++ = 0; 226 } 227 ret = vfs_parse_fs_string(fc, key, value); 228 if (ret < 0) 229 break; 230 } 231 } 232 233 return ret; 234 } 235 EXPORT_SYMBOL(vfs_parse_monolithic_sep); 236 237 static char *vfs_parse_comma_sep(char **s) 238 { 239 return strsep(s, ","); 240 } 241 242 /** 243 * generic_parse_monolithic - Parse key[=val][,key[=val]]* mount data 244 * @fc: The superblock configuration to fill in. 245 * @data: The data to parse 246 * 247 * Parse a blob of data that's in key[=val][,key[=val]]* form. This can be 248 * called from the ->monolithic_mount_data() fs_context operation. 249 * 250 * Returns 0 on success or the error returned by the ->parse_option() fs_context 251 * operation on failure. 252 */ 253 int generic_parse_monolithic(struct fs_context *fc, void *data) 254 { 255 return vfs_parse_monolithic_sep(fc, data, vfs_parse_comma_sep); 256 } 257 EXPORT_SYMBOL(generic_parse_monolithic); 258 259 /** 260 * alloc_fs_context - Create a filesystem context. 261 * @fs_type: The filesystem type. 262 * @reference: The dentry from which this one derives (or NULL) 263 * @sb_flags: Filesystem/superblock flags (SB_*) 264 * @sb_flags_mask: Applicable members of @sb_flags 265 * @purpose: The purpose that this configuration shall be used for. 266 * 267 * Open a filesystem and create a mount context. The mount context is 268 * initialised with the supplied flags and, if a submount/automount from 269 * another superblock (referred to by @reference) is supplied, may have 270 * parameters such as namespaces copied across from that superblock. 271 */ 272 static struct fs_context *alloc_fs_context(struct file_system_type *fs_type, 273 struct dentry *reference, 274 unsigned int sb_flags, 275 unsigned int sb_flags_mask, 276 enum fs_context_purpose purpose) 277 { 278 int (*init_fs_context)(struct fs_context *); 279 struct fs_context *fc; 280 int ret = -ENOMEM; 281 282 fc = kzalloc(sizeof(struct fs_context), GFP_KERNEL_ACCOUNT); 283 if (!fc) 284 return ERR_PTR(-ENOMEM); 285 286 fc->purpose = purpose; 287 fc->sb_flags = sb_flags; 288 fc->sb_flags_mask = sb_flags_mask; 289 fc->fs_type = get_filesystem(fs_type); 290 fc->cred = get_current_cred(); 291 fc->net_ns = get_net(current->nsproxy->net_ns); 292 fc->log.prefix = fs_type->name; 293 294 mutex_init(&fc->uapi_mutex); 295 296 switch (purpose) { 297 case FS_CONTEXT_FOR_MOUNT: 298 fc->user_ns = get_user_ns(fc->cred->user_ns); 299 break; 300 case FS_CONTEXT_FOR_SUBMOUNT: 301 fc->user_ns = get_user_ns(reference->d_sb->s_user_ns); 302 break; 303 case FS_CONTEXT_FOR_RECONFIGURE: 304 atomic_inc(&reference->d_sb->s_active); 305 fc->user_ns = get_user_ns(reference->d_sb->s_user_ns); 306 fc->root = dget(reference); 307 break; 308 } 309 310 /* TODO: Make all filesystems support this unconditionally */ 311 init_fs_context = fc->fs_type->init_fs_context; 312 if (!init_fs_context) 313 init_fs_context = legacy_init_fs_context; 314 315 ret = init_fs_context(fc); 316 if (ret < 0) 317 goto err_fc; 318 fc->need_free = true; 319 return fc; 320 321 err_fc: 322 put_fs_context(fc); 323 return ERR_PTR(ret); 324 } 325 326 struct fs_context *fs_context_for_mount(struct file_system_type *fs_type, 327 unsigned int sb_flags) 328 { 329 return alloc_fs_context(fs_type, NULL, sb_flags, 0, 330 FS_CONTEXT_FOR_MOUNT); 331 } 332 EXPORT_SYMBOL(fs_context_for_mount); 333 334 struct fs_context *fs_context_for_reconfigure(struct dentry *dentry, 335 unsigned int sb_flags, 336 unsigned int sb_flags_mask) 337 { 338 return alloc_fs_context(dentry->d_sb->s_type, dentry, sb_flags, 339 sb_flags_mask, FS_CONTEXT_FOR_RECONFIGURE); 340 } 341 EXPORT_SYMBOL(fs_context_for_reconfigure); 342 343 /** 344 * fs_context_for_submount: allocate a new fs_context for a submount 345 * @type: file_system_type of the new context 346 * @reference: reference dentry from which to copy relevant info 347 * 348 * Allocate a new fs_context suitable for a submount. This also ensures that 349 * the fc->security object is inherited from @reference (if needed). 350 */ 351 struct fs_context *fs_context_for_submount(struct file_system_type *type, 352 struct dentry *reference) 353 { 354 struct fs_context *fc; 355 int ret; 356 357 fc = alloc_fs_context(type, reference, 0, 0, FS_CONTEXT_FOR_SUBMOUNT); 358 if (IS_ERR(fc)) 359 return fc; 360 361 ret = security_fs_context_submount(fc, reference->d_sb); 362 if (ret) { 363 put_fs_context(fc); 364 return ERR_PTR(ret); 365 } 366 367 return fc; 368 } 369 EXPORT_SYMBOL(fs_context_for_submount); 370 371 void fc_drop_locked(struct fs_context *fc) 372 { 373 struct super_block *sb = fc->root->d_sb; 374 dput(fc->root); 375 fc->root = NULL; 376 deactivate_locked_super(sb); 377 } 378 379 static void legacy_fs_context_free(struct fs_context *fc); 380 381 /** 382 * vfs_dup_fs_context - Duplicate a filesystem context. 383 * @src_fc: The context to copy. 384 */ 385 struct fs_context *vfs_dup_fs_context(struct fs_context *src_fc) 386 { 387 struct fs_context *fc; 388 int ret; 389 390 if (!src_fc->ops->dup) 391 return ERR_PTR(-EOPNOTSUPP); 392 393 fc = kmemdup(src_fc, sizeof(struct fs_context), GFP_KERNEL); 394 if (!fc) 395 return ERR_PTR(-ENOMEM); 396 397 mutex_init(&fc->uapi_mutex); 398 399 fc->fs_private = NULL; 400 fc->s_fs_info = NULL; 401 fc->source = NULL; 402 fc->security = NULL; 403 get_filesystem(fc->fs_type); 404 get_net(fc->net_ns); 405 get_user_ns(fc->user_ns); 406 get_cred(fc->cred); 407 if (fc->log.log) 408 refcount_inc(&fc->log.log->usage); 409 410 /* Can't call put until we've called ->dup */ 411 ret = fc->ops->dup(fc, src_fc); 412 if (ret < 0) 413 goto err_fc; 414 415 ret = security_fs_context_dup(fc, src_fc); 416 if (ret < 0) 417 goto err_fc; 418 return fc; 419 420 err_fc: 421 put_fs_context(fc); 422 return ERR_PTR(ret); 423 } 424 EXPORT_SYMBOL(vfs_dup_fs_context); 425 426 /** 427 * logfc - Log a message to a filesystem context 428 * @log: The filesystem context to log to, or NULL to use printk. 429 * @prefix: A string to prefix the output with, or NULL. 430 * @level: 'w' for a warning, 'e' for an error. Anything else is a notice. 431 * @fmt: The format of the buffer. 432 */ 433 void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...) 434 { 435 va_list va; 436 struct va_format vaf = {.fmt = fmt, .va = &va}; 437 438 va_start(va, fmt); 439 if (!log) { 440 switch (level) { 441 case 'w': 442 printk(KERN_WARNING "%s%s%pV\n", prefix ? prefix : "", 443 prefix ? ": " : "", &vaf); 444 break; 445 case 'e': 446 printk(KERN_ERR "%s%s%pV\n", prefix ? prefix : "", 447 prefix ? ": " : "", &vaf); 448 break; 449 case 'i': 450 printk(KERN_INFO "%s%s%pV\n", prefix ? prefix : "", 451 prefix ? ": " : "", &vaf); 452 break; 453 default: 454 printk(KERN_NOTICE "%s%s%pV\n", prefix ? prefix : "", 455 prefix ? ": " : "", &vaf); 456 break; 457 } 458 } else { 459 unsigned int logsize = ARRAY_SIZE(log->buffer); 460 u8 index; 461 char *q = kasprintf(GFP_KERNEL, "%c %s%s%pV\n", level, 462 prefix ? prefix : "", 463 prefix ? ": " : "", &vaf); 464 465 index = log->head & (logsize - 1); 466 BUILD_BUG_ON(sizeof(log->head) != sizeof(u8) || 467 sizeof(log->tail) != sizeof(u8)); 468 if ((u8)(log->head - log->tail) == logsize) { 469 /* The buffer is full, discard the oldest message */ 470 if (log->need_free & (1 << index)) 471 kfree(log->buffer[index]); 472 log->tail++; 473 } 474 475 log->buffer[index] = q ? q : "OOM: Can't store error string"; 476 if (q) 477 log->need_free |= 1 << index; 478 else 479 log->need_free &= ~(1 << index); 480 log->head++; 481 } 482 va_end(va); 483 } 484 EXPORT_SYMBOL(logfc); 485 486 /* 487 * Free a logging structure. 488 */ 489 static void put_fc_log(struct fs_context *fc) 490 { 491 struct fc_log *log = fc->log.log; 492 int i; 493 494 if (log) { 495 if (refcount_dec_and_test(&log->usage)) { 496 fc->log.log = NULL; 497 for (i = 0; i < ARRAY_SIZE(log->buffer) ; i++) 498 if (log->need_free & (1 << i)) 499 kfree(log->buffer[i]); 500 kfree(log); 501 } 502 } 503 } 504 505 /** 506 * put_fs_context - Dispose of a superblock configuration context. 507 * @fc: The context to dispose of. 508 */ 509 void put_fs_context(struct fs_context *fc) 510 { 511 struct super_block *sb; 512 513 if (fc->root) { 514 sb = fc->root->d_sb; 515 dput(fc->root); 516 fc->root = NULL; 517 deactivate_super(sb); 518 } 519 520 if (fc->need_free && fc->ops && fc->ops->free) 521 fc->ops->free(fc); 522 523 security_free_mnt_opts(&fc->security); 524 put_net(fc->net_ns); 525 put_user_ns(fc->user_ns); 526 put_cred(fc->cred); 527 put_fc_log(fc); 528 put_filesystem(fc->fs_type); 529 kfree(fc->source); 530 kfree(fc); 531 } 532 EXPORT_SYMBOL(put_fs_context); 533 534 /* 535 * Free the config for a filesystem that doesn't support fs_context. 536 */ 537 static void legacy_fs_context_free(struct fs_context *fc) 538 { 539 struct legacy_fs_context *ctx = fc->fs_private; 540 541 if (ctx) { 542 if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS) 543 kfree(ctx->legacy_data); 544 kfree(ctx); 545 } 546 } 547 548 /* 549 * Duplicate a legacy config. 550 */ 551 static int legacy_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc) 552 { 553 struct legacy_fs_context *ctx; 554 struct legacy_fs_context *src_ctx = src_fc->fs_private; 555 556 ctx = kmemdup(src_ctx, sizeof(*src_ctx), GFP_KERNEL); 557 if (!ctx) 558 return -ENOMEM; 559 560 if (ctx->param_type == LEGACY_FS_INDIVIDUAL_PARAMS) { 561 ctx->legacy_data = kmemdup(src_ctx->legacy_data, 562 src_ctx->data_size, GFP_KERNEL); 563 if (!ctx->legacy_data) { 564 kfree(ctx); 565 return -ENOMEM; 566 } 567 } 568 569 fc->fs_private = ctx; 570 return 0; 571 } 572 573 /* 574 * Add a parameter to a legacy config. We build up a comma-separated list of 575 * options. 576 */ 577 static int legacy_parse_param(struct fs_context *fc, struct fs_parameter *param) 578 { 579 struct legacy_fs_context *ctx = fc->fs_private; 580 unsigned int size = ctx->data_size; 581 size_t len = 0; 582 int ret; 583 584 ret = vfs_parse_fs_param_source(fc, param); 585 if (ret != -ENOPARAM) 586 return ret; 587 588 if (ctx->param_type == LEGACY_FS_MONOLITHIC_PARAMS) 589 return invalf(fc, "VFS: Legacy: Can't mix monolithic and individual options"); 590 591 switch (param->type) { 592 case fs_value_is_string: 593 len = 1 + param->size; 594 fallthrough; 595 case fs_value_is_flag: 596 len += strlen(param->key); 597 break; 598 default: 599 return invalf(fc, "VFS: Legacy: Parameter type for '%s' not supported", 600 param->key); 601 } 602 603 if (size + len + 2 > PAGE_SIZE) 604 return invalf(fc, "VFS: Legacy: Cumulative options too large"); 605 if (strchr(param->key, ',') || 606 (param->type == fs_value_is_string && 607 memchr(param->string, ',', param->size))) 608 return invalf(fc, "VFS: Legacy: Option '%s' contained comma", 609 param->key); 610 if (!ctx->legacy_data) { 611 ctx->legacy_data = kmalloc(PAGE_SIZE, GFP_KERNEL); 612 if (!ctx->legacy_data) 613 return -ENOMEM; 614 } 615 616 if (size) 617 ctx->legacy_data[size++] = ','; 618 len = strlen(param->key); 619 memcpy(ctx->legacy_data + size, param->key, len); 620 size += len; 621 if (param->type == fs_value_is_string) { 622 ctx->legacy_data[size++] = '='; 623 memcpy(ctx->legacy_data + size, param->string, param->size); 624 size += param->size; 625 } 626 ctx->legacy_data[size] = '\0'; 627 ctx->data_size = size; 628 ctx->param_type = LEGACY_FS_INDIVIDUAL_PARAMS; 629 return 0; 630 } 631 632 /* 633 * Add monolithic mount data. 634 */ 635 static int legacy_parse_monolithic(struct fs_context *fc, void *data) 636 { 637 struct legacy_fs_context *ctx = fc->fs_private; 638 639 if (ctx->param_type != LEGACY_FS_UNSET_PARAMS) { 640 pr_warn("VFS: Can't mix monolithic and individual options\n"); 641 return -EINVAL; 642 } 643 644 ctx->legacy_data = data; 645 ctx->param_type = LEGACY_FS_MONOLITHIC_PARAMS; 646 if (!ctx->legacy_data) 647 return 0; 648 649 if (fc->fs_type->fs_flags & FS_BINARY_MOUNTDATA) 650 return 0; 651 return security_sb_eat_lsm_opts(ctx->legacy_data, &fc->security); 652 } 653 654 /* 655 * Get a mountable root with the legacy mount command. 656 */ 657 static int legacy_get_tree(struct fs_context *fc) 658 { 659 struct legacy_fs_context *ctx = fc->fs_private; 660 struct super_block *sb; 661 struct dentry *root; 662 663 root = fc->fs_type->mount(fc->fs_type, fc->sb_flags, 664 fc->source, ctx->legacy_data); 665 if (IS_ERR(root)) 666 return PTR_ERR(root); 667 668 sb = root->d_sb; 669 BUG_ON(!sb); 670 671 fc->root = root; 672 return 0; 673 } 674 675 /* 676 * Handle remount. 677 */ 678 static int legacy_reconfigure(struct fs_context *fc) 679 { 680 struct legacy_fs_context *ctx = fc->fs_private; 681 struct super_block *sb = fc->root->d_sb; 682 683 if (!sb->s_op->remount_fs) 684 return 0; 685 686 return sb->s_op->remount_fs(sb, &fc->sb_flags, 687 ctx ? ctx->legacy_data : NULL); 688 } 689 690 const struct fs_context_operations legacy_fs_context_ops = { 691 .free = legacy_fs_context_free, 692 .dup = legacy_fs_context_dup, 693 .parse_param = legacy_parse_param, 694 .parse_monolithic = legacy_parse_monolithic, 695 .get_tree = legacy_get_tree, 696 .reconfigure = legacy_reconfigure, 697 }; 698 699 /* 700 * Initialise a legacy context for a filesystem that doesn't support 701 * fs_context. 702 */ 703 static int legacy_init_fs_context(struct fs_context *fc) 704 { 705 fc->fs_private = kzalloc(sizeof(struct legacy_fs_context), GFP_KERNEL_ACCOUNT); 706 if (!fc->fs_private) 707 return -ENOMEM; 708 fc->ops = &legacy_fs_context_ops; 709 return 0; 710 } 711 712 int parse_monolithic_mount_data(struct fs_context *fc, void *data) 713 { 714 int (*monolithic_mount_data)(struct fs_context *, void *); 715 716 monolithic_mount_data = fc->ops->parse_monolithic; 717 if (!monolithic_mount_data) 718 monolithic_mount_data = generic_parse_monolithic; 719 720 return monolithic_mount_data(fc, data); 721 } 722 723 /* 724 * Clean up a context after performing an action on it and put it into a state 725 * from where it can be used to reconfigure a superblock. 726 * 727 * Note that here we do only the parts that can't fail; the rest is in 728 * finish_clean_context() below and in between those fs_context is marked 729 * FS_CONTEXT_AWAITING_RECONF. The reason for splitup is that after 730 * successful mount or remount we need to report success to userland. 731 * Trying to do full reinit (for the sake of possible subsequent remount) 732 * and failing to allocate memory would've put us into a nasty situation. 733 * So here we only discard the old state and reinitialization is left 734 * until we actually try to reconfigure. 735 */ 736 void vfs_clean_context(struct fs_context *fc) 737 { 738 if (fc->need_free && fc->ops && fc->ops->free) 739 fc->ops->free(fc); 740 fc->need_free = false; 741 fc->fs_private = NULL; 742 fc->s_fs_info = NULL; 743 fc->sb_flags = 0; 744 security_free_mnt_opts(&fc->security); 745 kfree(fc->source); 746 fc->source = NULL; 747 fc->exclusive = false; 748 749 fc->purpose = FS_CONTEXT_FOR_RECONFIGURE; 750 fc->phase = FS_CONTEXT_AWAITING_RECONF; 751 } 752 753 int finish_clean_context(struct fs_context *fc) 754 { 755 int error; 756 757 if (fc->phase != FS_CONTEXT_AWAITING_RECONF) 758 return 0; 759 760 if (fc->fs_type->init_fs_context) 761 error = fc->fs_type->init_fs_context(fc); 762 else 763 error = legacy_init_fs_context(fc); 764 if (unlikely(error)) { 765 fc->phase = FS_CONTEXT_FAILED; 766 return error; 767 } 768 fc->need_free = true; 769 fc->phase = FS_CONTEXT_RECONF_PARAMS; 770 return 0; 771 } 772