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