fs/squashfs/super.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Squashfs - a compressed read only filesystem for Linux
   4  *
   5  * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
   6  * Phillip Lougher <phillip@squashfs.org.uk>
   7  *
   8  * super.c
   9  */
  10
  11 /*
  12  * This file implements code to read the superblock, read and initialise
  13  * in-memory structures at mount time, and all the VFS glue code to register
  14  * the filesystem.
  15  */
  16
  17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  18
  19 #include <linux/blkdev.h>
  20 #include <linux/fs.h>
  21 #include <linux/fs_context.h>
  22 #include <linux/fs_parser.h>
  23 #include <linux/vfs.h>
  24 #include <linux/slab.h>
  25 #include <linux/mutex.h>
  26 #include <linux/seq_file.h>
  27 #include <linux/pagemap.h>
  28 #include <linux/init.h>
  29 #include <linux/module.h>
  30 #include <linux/magic.h>
  31 #include <linux/xattr.h>
  32
  33 #include "squashfs_fs.h"
  34 #include "squashfs_fs_sb.h"
  35 #include "squashfs_fs_i.h"
  36 #include "squashfs.h"
  37 #include "decompressor.h"
  38 #include "xattr.h"
  39
  40 static struct file_system_type squashfs_fs_type;
  41 static const struct super_operations squashfs_super_ops;
  42
  43 enum Opt_errors {
  44         Opt_errors_continue,
  45         Opt_errors_panic,
  46 };
  47
  48 enum squashfs_param {
  49         Opt_errors,
  50 };
  51
  52 struct squashfs_mount_opts {
  53         enum Opt_errors errors;
  54 };
  55
  56 static const struct constant_table squashfs_param_errors[] = {
  57         {"continue",   Opt_errors_continue },
  58         {"panic",      Opt_errors_panic },
  59         {}
  60 };
  61
  62 static const struct fs_parameter_spec squashfs_fs_parameters[] = {
  63         fsparam_enum("errors", Opt_errors, squashfs_param_errors),
  64         {}
  65 };
  66
  67 static int squashfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
  68 {
  69         struct squashfs_mount_opts *opts = fc->fs_private;
  70         struct fs_parse_result result;
  71         int opt;
  72
  73         opt = fs_parse(fc, squashfs_fs_parameters, param, &result);
  74         if (opt < 0)
  75                 return opt;
  76
  77         switch (opt) {
  78         case Opt_errors:
  79                 opts->errors = result.uint_32;
  80                 break;
  81         default:
  82                 return -EINVAL;
  83         }
  84
  85         return 0;
  86 }
  87
  88 static const struct squashfs_decompressor *supported_squashfs_filesystem(
  89         struct fs_context *fc,
  90         short major, short minor, short id)
  91 {
  92         const struct squashfs_decompressor *decompressor;
  93
  94         if (major < SQUASHFS_MAJOR) {
  95                 errorf(fc, "Major/Minor mismatch, older Squashfs %d.%d "
  96                        "filesystems are unsupported", major, minor);
  97                 return NULL;
  98         } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
  99                 errorf(fc, "Major/Minor mismatch, trying to mount newer "
 100                        "%d.%d filesystem", major, minor);
 101                 errorf(fc, "Please update your kernel");
 102                 return NULL;
 103         }
 104
 105         decompressor = squashfs_lookup_decompressor(id);
 106         if (!decompressor->supported) {
 107                 errorf(fc, "Filesystem uses \"%s\" compression. This is not supported",
 108                        decompressor->name);
 109                 return NULL;
 110         }
 111
 112         return decompressor;
 113 }
 114
 115
 116 static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
 117 {
 118         struct squashfs_mount_opts *opts = fc->fs_private;
 119         struct squashfs_sb_info *msblk;
 120         struct squashfs_super_block *sblk = NULL;
 121         struct inode *root;
 122         long long root_inode;
 123         unsigned short flags;
 124         unsigned int fragments;
 125         u64 lookup_table_start, xattr_id_table_start, next_table;
 126         int err;
 127
 128         TRACE("Entered squashfs_fill_superblock\n");
 129
 130         sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL);
 131         if (sb->s_fs_info == NULL) {
 132                 ERROR("Failed to allocate squashfs_sb_info\n");
 133                 return -ENOMEM;
 134         }
 135         msblk = sb->s_fs_info;
 136
 137         msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
 138
 139         msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
 140         msblk->devblksize_log2 = ffz(~msblk->devblksize);
 141
 142         mutex_init(&msblk->meta_index_mutex);
 143
 144         /*
 145          * msblk->bytes_used is checked in squashfs_read_table to ensure reads
 146          * are not beyond filesystem end.  But as we're using
 147          * squashfs_read_table here to read the superblock (including the value
 148          * of bytes_used) we need to set it to an initial sensible dummy value
 149          */
 150         msblk->bytes_used = sizeof(*sblk);
 151         sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk));
 152
 153         if (IS_ERR(sblk)) {
 154                 errorf(fc, "unable to read squashfs_super_block");
 155                 err = PTR_ERR(sblk);
 156                 sblk = NULL;
 157                 goto failed_mount;
 158         }
 159
 160         err = -EINVAL;
 161
 162         /* Check it is a SQUASHFS superblock */
 163         sb->s_magic = le32_to_cpu(sblk->s_magic);
 164         if (sb->s_magic != SQUASHFS_MAGIC) {
 165                 if (!(fc->sb_flags & SB_SILENT))
 166                         errorf(fc, "Can't find a SQUASHFS superblock on %pg",
 167                                sb->s_bdev);
 168                 goto failed_mount;
 169         }
 170
 171         /* Check the MAJOR & MINOR versions and lookup compression type */
 172         msblk->decompressor = supported_squashfs_filesystem(
 173                         fc,
 174                         le16_to_cpu(sblk->s_major),
 175                         le16_to_cpu(sblk->s_minor),
 176                         le16_to_cpu(sblk->compression));
 177         if (msblk->decompressor == NULL)
 178                 goto failed_mount;
 179
 180         /* Check the filesystem does not extend beyond the end of the
 181            block device */
 182         msblk->bytes_used = le64_to_cpu(sblk->bytes_used);
 183         if (msblk->bytes_used < 0 ||
 184             msblk->bytes_used > bdev_nr_bytes(sb->s_bdev))
 185                 goto failed_mount;
 186
 187         /* Check block size for sanity */
 188         msblk->block_size = le32_to_cpu(sblk->block_size);
 189         if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE)
 190                 goto insanity;
 191
 192         /*
 193          * Check the system page size is not larger than the filesystem
 194          * block size (by default 128K).  This is currently not supported.
 195          */
 196         if (PAGE_SIZE > msblk->block_size) {
 197                 errorf(fc, "Page size > filesystem block size (%d).  This is "
 198                        "currently not supported!", msblk->block_size);
 199                 goto failed_mount;
 200         }
 201
 202         /* Check block log for sanity */
 203         msblk->block_log = le16_to_cpu(sblk->block_log);
 204         if (msblk->block_log > SQUASHFS_FILE_MAX_LOG)
 205                 goto failed_mount;
 206
 207         /* Check that block_size and block_log match */
 208         if (msblk->block_size != (1 << msblk->block_log))
 209                 goto insanity;
 210
 211         /* Check the root inode for sanity */
 212         root_inode = le64_to_cpu(sblk->root_inode);
 213         if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE)
 214                 goto insanity;
 215
 216         msblk->inode_table = le64_to_cpu(sblk->inode_table_start);
 217         msblk->directory_table = le64_to_cpu(sblk->directory_table_start);
 218         msblk->inodes = le32_to_cpu(sblk->inodes);
 219         msblk->fragments = le32_to_cpu(sblk->fragments);
 220         msblk->ids = le16_to_cpu(sblk->no_ids);
 221         flags = le16_to_cpu(sblk->flags);
 222
 223         TRACE("Found valid superblock on %pg\n", sb->s_bdev);
 224         TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags)
 225                                 ? "un" : "");
 226         TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags)
 227                                 ? "un" : "");
 228         TRACE("Filesystem size %lld bytes\n", msblk->bytes_used);
 229         TRACE("Block size %d\n", msblk->block_size);
 230         TRACE("Number of inodes %d\n", msblk->inodes);
 231         TRACE("Number of fragments %d\n", msblk->fragments);
 232         TRACE("Number of ids %d\n", msblk->ids);
 233         TRACE("sblk->inode_table_start %llx\n", msblk->inode_table);
 234         TRACE("sblk->directory_table_start %llx\n", msblk->directory_table);
 235         TRACE("sblk->fragment_table_start %llx\n",
 236                 (u64) le64_to_cpu(sblk->fragment_table_start));
 237         TRACE("sblk->id_table_start %llx\n",
 238                 (u64) le64_to_cpu(sblk->id_table_start));
 239
 240         sb->s_maxbytes = MAX_LFS_FILESIZE;
 241         sb->s_time_min = 0;
 242         sb->s_time_max = U32_MAX;
 243         sb->s_flags |= SB_RDONLY;
 244         sb->s_op = &squashfs_super_ops;
 245
 246         err = -ENOMEM;
 247
 248         msblk->block_cache = squashfs_cache_init("metadata",
 249                         SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
 250         if (msblk->block_cache == NULL)
 251                 goto failed_mount;
 252
 253         /* Allocate read_page block */
 254         msblk->read_page = squashfs_cache_init("data",
 255                 squashfs_max_decompressors(), msblk->block_size);
 256         if (msblk->read_page == NULL) {
 257                 errorf(fc, "Failed to allocate read_page block");
 258                 goto failed_mount;
 259         }
 260
 261         msblk->stream = squashfs_decompressor_setup(sb, flags);
 262         if (IS_ERR(msblk->stream)) {
 263                 err = PTR_ERR(msblk->stream);
 264                 msblk->stream = NULL;
 265                 goto insanity;
 266         }
 267
 268         /* Handle xattrs */
 269         sb->s_xattr = squashfs_xattr_handlers;
 270         xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start);
 271         if (xattr_id_table_start == SQUASHFS_INVALID_BLK) {
 272                 next_table = msblk->bytes_used;
 273                 goto allocate_id_index_table;
 274         }
 275
 276         /* Allocate and read xattr id lookup table */
 277         msblk->xattr_id_table = squashfs_read_xattr_id_table(sb,
 278                 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids);
 279         if (IS_ERR(msblk->xattr_id_table)) {
 280                 errorf(fc, "unable to read xattr id index table");
 281                 err = PTR_ERR(msblk->xattr_id_table);
 282                 msblk->xattr_id_table = NULL;
 283                 if (err != -ENOTSUPP)
 284                         goto failed_mount;
 285         }
 286         next_table = msblk->xattr_table;
 287
 288 allocate_id_index_table:
 289         /* Allocate and read id index table */
 290         msblk->id_table = squashfs_read_id_index_table(sb,
 291                 le64_to_cpu(sblk->id_table_start), next_table, msblk->ids);
 292         if (IS_ERR(msblk->id_table)) {
 293                 errorf(fc, "unable to read id index table");
 294                 err = PTR_ERR(msblk->id_table);
 295                 msblk->id_table = NULL;
 296                 goto failed_mount;
 297         }
 298         next_table = le64_to_cpu(msblk->id_table[0]);
 299
 300         /* Handle inode lookup table */
 301         lookup_table_start = le64_to_cpu(sblk->lookup_table_start);
 302         if (lookup_table_start == SQUASHFS_INVALID_BLK)
 303                 goto handle_fragments;
 304
 305         /* Allocate and read inode lookup table */
 306         msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb,
 307                 lookup_table_start, next_table, msblk->inodes);
 308         if (IS_ERR(msblk->inode_lookup_table)) {
 309                 errorf(fc, "unable to read inode lookup table");
 310                 err = PTR_ERR(msblk->inode_lookup_table);
 311                 msblk->inode_lookup_table = NULL;
 312                 goto failed_mount;
 313         }
 314         next_table = le64_to_cpu(msblk->inode_lookup_table[0]);
 315
 316         sb->s_export_op = &squashfs_export_ops;
 317
 318 handle_fragments:
 319         fragments = msblk->fragments;
 320         if (fragments == 0)
 321                 goto check_directory_table;
 322
 323         msblk->fragment_cache = squashfs_cache_init("fragment",
 324                 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size);
 325         if (msblk->fragment_cache == NULL) {
 326                 err = -ENOMEM;
 327                 goto failed_mount;
 328         }
 329
 330         /* Allocate and read fragment index table */
 331         msblk->fragment_index = squashfs_read_fragment_index_table(sb,
 332                 le64_to_cpu(sblk->fragment_table_start), next_table, fragments);
 333         if (IS_ERR(msblk->fragment_index)) {
 334                 errorf(fc, "unable to read fragment index table");
 335                 err = PTR_ERR(msblk->fragment_index);
 336                 msblk->fragment_index = NULL;
 337                 goto failed_mount;
 338         }
 339         next_table = le64_to_cpu(msblk->fragment_index[0]);
 340
 341 check_directory_table:
 342         /* Sanity check directory_table */
 343         if (msblk->directory_table > next_table) {
 344                 err = -EINVAL;
 345                 goto insanity;
 346         }
 347
 348         /* Sanity check inode_table */
 349         if (msblk->inode_table >= msblk->directory_table) {
 350                 err = -EINVAL;
 351                 goto insanity;
 352         }
 353
 354         /* allocate root */
 355         root = new_inode(sb);
 356         if (!root) {
 357                 err = -ENOMEM;
 358                 goto failed_mount;
 359         }
 360
 361         err = squashfs_read_inode(root, root_inode);
 362         if (err) {
 363                 make_bad_inode(root);
 364                 iput(root);
 365                 goto failed_mount;
 366         }
 367         insert_inode_hash(root);
 368
 369         sb->s_root = d_make_root(root);
 370         if (sb->s_root == NULL) {
 371                 ERROR("Root inode create failed\n");
 372                 err = -ENOMEM;
 373                 goto failed_mount;
 374         }
 375
 376         TRACE("Leaving squashfs_fill_super\n");
 377         kfree(sblk);
 378         return 0;
 379
 380 insanity:
 381         errorf(fc, "squashfs image failed sanity check");
 382 failed_mount:
 383         squashfs_cache_delete(msblk->block_cache);
 384         squashfs_cache_delete(msblk->fragment_cache);
 385         squashfs_cache_delete(msblk->read_page);
 386         squashfs_decompressor_destroy(msblk);
 387         kfree(msblk->inode_lookup_table);
 388         kfree(msblk->fragment_index);
 389         kfree(msblk->id_table);
 390         kfree(msblk->xattr_id_table);
 391         kfree(sb->s_fs_info);
 392         sb->s_fs_info = NULL;
 393         kfree(sblk);
 394         return err;
 395 }
 396
 397 static int squashfs_get_tree(struct fs_context *fc)
 398 {
 399         return get_tree_bdev(fc, squashfs_fill_super);
 400 }
 401
 402 static int squashfs_reconfigure(struct fs_context *fc)
 403 {
 404         struct super_block *sb = fc->root->d_sb;
 405         struct squashfs_sb_info *msblk = sb->s_fs_info;
 406         struct squashfs_mount_opts *opts = fc->fs_private;
 407
 408         sync_filesystem(fc->root->d_sb);
 409         fc->sb_flags |= SB_RDONLY;
 410
 411         msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
 412
 413         return 0;
 414 }
 415
 416 static void squashfs_free_fs_context(struct fs_context *fc)
 417 {
 418         kfree(fc->fs_private);
 419 }
 420
 421 static const struct fs_context_operations squashfs_context_ops = {
 422         .get_tree       = squashfs_get_tree,
 423         .free           = squashfs_free_fs_context,
 424         .parse_param    = squashfs_parse_param,
 425         .reconfigure    = squashfs_reconfigure,
 426 };
 427
 428 static int squashfs_show_options(struct seq_file *s, struct dentry *root)
 429 {
 430         struct super_block *sb = root->d_sb;
 431         struct squashfs_sb_info *msblk = sb->s_fs_info;
 432
 433         if (msblk->panic_on_errors)
 434                 seq_puts(s, ",errors=panic");
 435         else
 436                 seq_puts(s, ",errors=continue");
 437
 438         return 0;
 439 }
 440
 441 static int squashfs_init_fs_context(struct fs_context *fc)
 442 {
 443         struct squashfs_mount_opts *opts;
 444
 445         opts = kzalloc(sizeof(*opts), GFP_KERNEL);
 446         if (!opts)
 447                 return -ENOMEM;
 448
 449         fc->fs_private = opts;
 450         fc->ops = &squashfs_context_ops;
 451         return 0;
 452 }
 453
 454 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 455 {
 456         struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info;
 457         u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev);
 458
 459         TRACE("Entered squashfs_statfs\n");
 460
 461         buf->f_type = SQUASHFS_MAGIC;
 462         buf->f_bsize = msblk->block_size;
 463         buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1;
 464         buf->f_bfree = buf->f_bavail = 0;
 465         buf->f_files = msblk->inodes;
 466         buf->f_ffree = 0;
 467         buf->f_namelen = SQUASHFS_NAME_LEN;
 468         buf->f_fsid = u64_to_fsid(id);
 469
 470         return 0;
 471 }
 472
 473
 474 static void squashfs_put_super(struct super_block *sb)
 475 {
 476         if (sb->s_fs_info) {
 477                 struct squashfs_sb_info *sbi = sb->s_fs_info;
 478                 squashfs_cache_delete(sbi->block_cache);
 479                 squashfs_cache_delete(sbi->fragment_cache);
 480                 squashfs_cache_delete(sbi->read_page);
 481                 squashfs_decompressor_destroy(sbi);
 482                 kfree(sbi->id_table);
 483                 kfree(sbi->fragment_index);
 484                 kfree(sbi->meta_index);
 485                 kfree(sbi->inode_lookup_table);
 486                 kfree(sbi->xattr_id_table);
 487                 kfree(sb->s_fs_info);
 488                 sb->s_fs_info = NULL;
 489         }
 490 }
 491
 492 static struct kmem_cache *squashfs_inode_cachep;
 493
 494
 495 static void init_once(void *foo)
 496 {
 497         struct squashfs_inode_info *ei = foo;
 498
 499         inode_init_once(&ei->vfs_inode);
 500 }
 501
 502
 503 static int __init init_inodecache(void)
 504 {
 505         squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache",
 506                 sizeof(struct squashfs_inode_info), 0,
 507                 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
 508                 init_once);
 509
 510         return squashfs_inode_cachep ? 0 : -ENOMEM;
 511 }
 512
 513
 514 static void destroy_inodecache(void)
 515 {
 516         /*
 517          * Make sure all delayed rcu free inodes are flushed before we
 518          * destroy cache.
 519          */
 520         rcu_barrier();
 521         kmem_cache_destroy(squashfs_inode_cachep);
 522 }
 523
 524
 525 static int __init init_squashfs_fs(void)
 526 {
 527         int err = init_inodecache();
 528
 529         if (err)
 530                 return err;
 531
 532         err = register_filesystem(&squashfs_fs_type);
 533         if (err) {
 534                 destroy_inodecache();
 535                 return err;
 536         }
 537
 538         pr_info("version 4.0 (2009/01/31) Phillip Lougher\n");
 539
 540         return 0;
 541 }
 542
 543
 544 static void __exit exit_squashfs_fs(void)
 545 {
 546         unregister_filesystem(&squashfs_fs_type);
 547         destroy_inodecache();
 548 }
 549
 550
 551 static struct inode *squashfs_alloc_inode(struct super_block *sb)
 552 {
 553         struct squashfs_inode_info *ei =
 554                 alloc_inode_sb(sb, squashfs_inode_cachep, GFP_KERNEL);
 555
 556         return ei ? &ei->vfs_inode : NULL;
 557 }
 558
 559
 560 static void squashfs_free_inode(struct inode *inode)
 561 {
 562         kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode));
 563 }
 564
 565 static struct file_system_type squashfs_fs_type = {
 566         .owner = THIS_MODULE,
 567         .name = "squashfs",
 568         .init_fs_context = squashfs_init_fs_context,
 569         .parameters = squashfs_fs_parameters,
 570         .kill_sb = kill_block_super,
 571         .fs_flags = FS_REQUIRES_DEV
 572 };
 573 MODULE_ALIAS_FS("squashfs");
 574
 575 static const struct super_operations squashfs_super_ops = {
 576         .alloc_inode = squashfs_alloc_inode,
 577         .free_inode = squashfs_free_inode,
 578         .statfs = squashfs_statfs,
 579         .put_super = squashfs_put_super,
 580         .show_options = squashfs_show_options,
 581 };
 582
 583 module_init(init_squashfs_fs);
 584 module_exit(exit_squashfs_fs);
 585 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem");
 586 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>");
 587 MODULE_LICENSE("GPL");