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 #include <linux/backing-dev.h> 33 34 #include "squashfs_fs.h" 35 #include "squashfs_fs_sb.h" 36 #include "squashfs_fs_i.h" 37 #include "squashfs.h" 38 #include "decompressor.h" 39 #include "xattr.h" 40 41 static struct file_system_type squashfs_fs_type; 42 static const struct super_operations squashfs_super_ops; 43 44 enum Opt_errors { 45 Opt_errors_continue, 46 Opt_errors_panic, 47 }; 48 49 enum squashfs_param { 50 Opt_errors, 51 }; 52 53 struct squashfs_mount_opts { 54 enum Opt_errors errors; 55 }; 56 57 static const struct constant_table squashfs_param_errors[] = { 58 {"continue", Opt_errors_continue }, 59 {"panic", Opt_errors_panic }, 60 {} 61 }; 62 63 static const struct fs_parameter_spec squashfs_fs_parameters[] = { 64 fsparam_enum("errors", Opt_errors, squashfs_param_errors), 65 {} 66 }; 67 68 static int squashfs_parse_param(struct fs_context *fc, struct fs_parameter *param) 69 { 70 struct squashfs_mount_opts *opts = fc->fs_private; 71 struct fs_parse_result result; 72 int opt; 73 74 opt = fs_parse(fc, squashfs_fs_parameters, param, &result); 75 if (opt < 0) 76 return opt; 77 78 switch (opt) { 79 case Opt_errors: 80 opts->errors = result.uint_32; 81 break; 82 default: 83 return -EINVAL; 84 } 85 86 return 0; 87 } 88 89 static const struct squashfs_decompressor *supported_squashfs_filesystem( 90 struct fs_context *fc, 91 short major, short minor, short id) 92 { 93 const struct squashfs_decompressor *decompressor; 94 95 if (major < SQUASHFS_MAJOR) { 96 errorf(fc, "Major/Minor mismatch, older Squashfs %d.%d " 97 "filesystems are unsupported", major, minor); 98 return NULL; 99 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) { 100 errorf(fc, "Major/Minor mismatch, trying to mount newer " 101 "%d.%d filesystem", major, minor); 102 errorf(fc, "Please update your kernel"); 103 return NULL; 104 } 105 106 decompressor = squashfs_lookup_decompressor(id); 107 if (!decompressor->supported) { 108 errorf(fc, "Filesystem uses \"%s\" compression. This is not supported", 109 decompressor->name); 110 return NULL; 111 } 112 113 return decompressor; 114 } 115 116 static int squashfs_bdi_init(struct super_block *sb) 117 { 118 int err; 119 unsigned int major = MAJOR(sb->s_dev); 120 unsigned int minor = MINOR(sb->s_dev); 121 122 bdi_put(sb->s_bdi); 123 sb->s_bdi = &noop_backing_dev_info; 124 125 err = super_setup_bdi_name(sb, "squashfs_%u_%u", major, minor); 126 if (err) 127 return err; 128 129 sb->s_bdi->ra_pages = 0; 130 sb->s_bdi->io_pages = 0; 131 132 return 0; 133 } 134 135 static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc) 136 { 137 struct squashfs_mount_opts *opts = fc->fs_private; 138 struct squashfs_sb_info *msblk; 139 struct squashfs_super_block *sblk = NULL; 140 struct inode *root; 141 long long root_inode; 142 unsigned short flags; 143 unsigned int fragments; 144 u64 lookup_table_start, xattr_id_table_start, next_table; 145 int err; 146 147 TRACE("Entered squashfs_fill_superblock\n"); 148 149 /* 150 * squashfs provides 'backing_dev_info' in order to disable read-ahead. For 151 * squashfs, I/O is not deferred, it is done immediately in read_folio, 152 * which means the user would always have to wait their own I/O. So the effect 153 * of readahead is very weak for squashfs. squashfs_bdi_init will set 154 * sb->s_bdi->ra_pages and sb->s_bdi->io_pages to 0 and close readahead for 155 * squashfs. 156 */ 157 err = squashfs_bdi_init(sb); 158 if (err) { 159 errorf(fc, "squashfs init bdi failed"); 160 return err; 161 } 162 163 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL); 164 if (sb->s_fs_info == NULL) { 165 ERROR("Failed to allocate squashfs_sb_info\n"); 166 return -ENOMEM; 167 } 168 msblk = sb->s_fs_info; 169 170 msblk->panic_on_errors = (opts->errors == Opt_errors_panic); 171 172 msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE); 173 msblk->devblksize_log2 = ffz(~msblk->devblksize); 174 175 mutex_init(&msblk->meta_index_mutex); 176 177 /* 178 * msblk->bytes_used is checked in squashfs_read_table to ensure reads 179 * are not beyond filesystem end. But as we're using 180 * squashfs_read_table here to read the superblock (including the value 181 * of bytes_used) we need to set it to an initial sensible dummy value 182 */ 183 msblk->bytes_used = sizeof(*sblk); 184 sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk)); 185 186 if (IS_ERR(sblk)) { 187 errorf(fc, "unable to read squashfs_super_block"); 188 err = PTR_ERR(sblk); 189 sblk = NULL; 190 goto failed_mount; 191 } 192 193 err = -EINVAL; 194 195 /* Check it is a SQUASHFS superblock */ 196 sb->s_magic = le32_to_cpu(sblk->s_magic); 197 if (sb->s_magic != SQUASHFS_MAGIC) { 198 if (!(fc->sb_flags & SB_SILENT)) 199 errorf(fc, "Can't find a SQUASHFS superblock on %pg", 200 sb->s_bdev); 201 goto failed_mount; 202 } 203 204 /* Check the MAJOR & MINOR versions and lookup compression type */ 205 msblk->decompressor = supported_squashfs_filesystem( 206 fc, 207 le16_to_cpu(sblk->s_major), 208 le16_to_cpu(sblk->s_minor), 209 le16_to_cpu(sblk->compression)); 210 if (msblk->decompressor == NULL) 211 goto failed_mount; 212 213 /* Check the filesystem does not extend beyond the end of the 214 block device */ 215 msblk->bytes_used = le64_to_cpu(sblk->bytes_used); 216 if (msblk->bytes_used < 0 || 217 msblk->bytes_used > bdev_nr_bytes(sb->s_bdev)) 218 goto failed_mount; 219 220 /* Check block size for sanity */ 221 msblk->block_size = le32_to_cpu(sblk->block_size); 222 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE) 223 goto insanity; 224 225 /* 226 * Check the system page size is not larger than the filesystem 227 * block size (by default 128K). This is currently not supported. 228 */ 229 if (PAGE_SIZE > msblk->block_size) { 230 errorf(fc, "Page size > filesystem block size (%d). This is " 231 "currently not supported!", msblk->block_size); 232 goto failed_mount; 233 } 234 235 /* Check block log for sanity */ 236 msblk->block_log = le16_to_cpu(sblk->block_log); 237 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) 238 goto failed_mount; 239 240 /* Check that block_size and block_log match */ 241 if (msblk->block_size != (1 << msblk->block_log)) 242 goto insanity; 243 244 /* Check the root inode for sanity */ 245 root_inode = le64_to_cpu(sblk->root_inode); 246 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE) 247 goto insanity; 248 249 msblk->inode_table = le64_to_cpu(sblk->inode_table_start); 250 msblk->directory_table = le64_to_cpu(sblk->directory_table_start); 251 msblk->inodes = le32_to_cpu(sblk->inodes); 252 msblk->fragments = le32_to_cpu(sblk->fragments); 253 msblk->ids = le16_to_cpu(sblk->no_ids); 254 flags = le16_to_cpu(sblk->flags); 255 256 TRACE("Found valid superblock on %pg\n", sb->s_bdev); 257 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags) 258 ? "un" : ""); 259 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags) 260 ? "un" : ""); 261 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used); 262 TRACE("Block size %d\n", msblk->block_size); 263 TRACE("Number of inodes %d\n", msblk->inodes); 264 TRACE("Number of fragments %d\n", msblk->fragments); 265 TRACE("Number of ids %d\n", msblk->ids); 266 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table); 267 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table); 268 TRACE("sblk->fragment_table_start %llx\n", 269 (u64) le64_to_cpu(sblk->fragment_table_start)); 270 TRACE("sblk->id_table_start %llx\n", 271 (u64) le64_to_cpu(sblk->id_table_start)); 272 273 sb->s_maxbytes = MAX_LFS_FILESIZE; 274 sb->s_time_min = 0; 275 sb->s_time_max = U32_MAX; 276 sb->s_flags |= SB_RDONLY; 277 sb->s_op = &squashfs_super_ops; 278 279 err = -ENOMEM; 280 281 msblk->block_cache = squashfs_cache_init("metadata", 282 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE); 283 if (msblk->block_cache == NULL) 284 goto failed_mount; 285 286 /* Allocate read_page block */ 287 msblk->read_page = squashfs_cache_init("data", 288 squashfs_max_decompressors(), msblk->block_size); 289 if (msblk->read_page == NULL) { 290 errorf(fc, "Failed to allocate read_page block"); 291 goto failed_mount; 292 } 293 294 msblk->stream = squashfs_decompressor_setup(sb, flags); 295 if (IS_ERR(msblk->stream)) { 296 err = PTR_ERR(msblk->stream); 297 msblk->stream = NULL; 298 goto insanity; 299 } 300 301 /* Handle xattrs */ 302 sb->s_xattr = squashfs_xattr_handlers; 303 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start); 304 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) { 305 next_table = msblk->bytes_used; 306 goto allocate_id_index_table; 307 } 308 309 /* Allocate and read xattr id lookup table */ 310 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb, 311 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids); 312 if (IS_ERR(msblk->xattr_id_table)) { 313 errorf(fc, "unable to read xattr id index table"); 314 err = PTR_ERR(msblk->xattr_id_table); 315 msblk->xattr_id_table = NULL; 316 if (err != -ENOTSUPP) 317 goto failed_mount; 318 } 319 next_table = msblk->xattr_table; 320 321 allocate_id_index_table: 322 /* Allocate and read id index table */ 323 msblk->id_table = squashfs_read_id_index_table(sb, 324 le64_to_cpu(sblk->id_table_start), next_table, msblk->ids); 325 if (IS_ERR(msblk->id_table)) { 326 errorf(fc, "unable to read id index table"); 327 err = PTR_ERR(msblk->id_table); 328 msblk->id_table = NULL; 329 goto failed_mount; 330 } 331 next_table = le64_to_cpu(msblk->id_table[0]); 332 333 /* Handle inode lookup table */ 334 lookup_table_start = le64_to_cpu(sblk->lookup_table_start); 335 if (lookup_table_start == SQUASHFS_INVALID_BLK) 336 goto handle_fragments; 337 338 /* Allocate and read inode lookup table */ 339 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb, 340 lookup_table_start, next_table, msblk->inodes); 341 if (IS_ERR(msblk->inode_lookup_table)) { 342 errorf(fc, "unable to read inode lookup table"); 343 err = PTR_ERR(msblk->inode_lookup_table); 344 msblk->inode_lookup_table = NULL; 345 goto failed_mount; 346 } 347 next_table = le64_to_cpu(msblk->inode_lookup_table[0]); 348 349 sb->s_export_op = &squashfs_export_ops; 350 351 handle_fragments: 352 fragments = msblk->fragments; 353 if (fragments == 0) 354 goto check_directory_table; 355 356 msblk->fragment_cache = squashfs_cache_init("fragment", 357 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size); 358 if (msblk->fragment_cache == NULL) { 359 err = -ENOMEM; 360 goto failed_mount; 361 } 362 363 /* Allocate and read fragment index table */ 364 msblk->fragment_index = squashfs_read_fragment_index_table(sb, 365 le64_to_cpu(sblk->fragment_table_start), next_table, fragments); 366 if (IS_ERR(msblk->fragment_index)) { 367 errorf(fc, "unable to read fragment index table"); 368 err = PTR_ERR(msblk->fragment_index); 369 msblk->fragment_index = NULL; 370 goto failed_mount; 371 } 372 next_table = le64_to_cpu(msblk->fragment_index[0]); 373 374 check_directory_table: 375 /* Sanity check directory_table */ 376 if (msblk->directory_table > next_table) { 377 err = -EINVAL; 378 goto insanity; 379 } 380 381 /* Sanity check inode_table */ 382 if (msblk->inode_table >= msblk->directory_table) { 383 err = -EINVAL; 384 goto insanity; 385 } 386 387 /* allocate root */ 388 root = new_inode(sb); 389 if (!root) { 390 err = -ENOMEM; 391 goto failed_mount; 392 } 393 394 err = squashfs_read_inode(root, root_inode); 395 if (err) { 396 make_bad_inode(root); 397 iput(root); 398 goto failed_mount; 399 } 400 insert_inode_hash(root); 401 402 sb->s_root = d_make_root(root); 403 if (sb->s_root == NULL) { 404 ERROR("Root inode create failed\n"); 405 err = -ENOMEM; 406 goto failed_mount; 407 } 408 409 TRACE("Leaving squashfs_fill_super\n"); 410 kfree(sblk); 411 return 0; 412 413 insanity: 414 errorf(fc, "squashfs image failed sanity check"); 415 failed_mount: 416 squashfs_cache_delete(msblk->block_cache); 417 squashfs_cache_delete(msblk->fragment_cache); 418 squashfs_cache_delete(msblk->read_page); 419 squashfs_decompressor_destroy(msblk); 420 kfree(msblk->inode_lookup_table); 421 kfree(msblk->fragment_index); 422 kfree(msblk->id_table); 423 kfree(msblk->xattr_id_table); 424 kfree(sb->s_fs_info); 425 sb->s_fs_info = NULL; 426 kfree(sblk); 427 return err; 428 } 429 430 static int squashfs_get_tree(struct fs_context *fc) 431 { 432 return get_tree_bdev(fc, squashfs_fill_super); 433 } 434 435 static int squashfs_reconfigure(struct fs_context *fc) 436 { 437 struct super_block *sb = fc->root->d_sb; 438 struct squashfs_sb_info *msblk = sb->s_fs_info; 439 struct squashfs_mount_opts *opts = fc->fs_private; 440 441 sync_filesystem(fc->root->d_sb); 442 fc->sb_flags |= SB_RDONLY; 443 444 msblk->panic_on_errors = (opts->errors == Opt_errors_panic); 445 446 return 0; 447 } 448 449 static void squashfs_free_fs_context(struct fs_context *fc) 450 { 451 kfree(fc->fs_private); 452 } 453 454 static const struct fs_context_operations squashfs_context_ops = { 455 .get_tree = squashfs_get_tree, 456 .free = squashfs_free_fs_context, 457 .parse_param = squashfs_parse_param, 458 .reconfigure = squashfs_reconfigure, 459 }; 460 461 static int squashfs_show_options(struct seq_file *s, struct dentry *root) 462 { 463 struct super_block *sb = root->d_sb; 464 struct squashfs_sb_info *msblk = sb->s_fs_info; 465 466 if (msblk->panic_on_errors) 467 seq_puts(s, ",errors=panic"); 468 else 469 seq_puts(s, ",errors=continue"); 470 471 return 0; 472 } 473 474 static int squashfs_init_fs_context(struct fs_context *fc) 475 { 476 struct squashfs_mount_opts *opts; 477 478 opts = kzalloc(sizeof(*opts), GFP_KERNEL); 479 if (!opts) 480 return -ENOMEM; 481 482 fc->fs_private = opts; 483 fc->ops = &squashfs_context_ops; 484 return 0; 485 } 486 487 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) 488 { 489 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; 490 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev); 491 492 TRACE("Entered squashfs_statfs\n"); 493 494 buf->f_type = SQUASHFS_MAGIC; 495 buf->f_bsize = msblk->block_size; 496 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1; 497 buf->f_bfree = buf->f_bavail = 0; 498 buf->f_files = msblk->inodes; 499 buf->f_ffree = 0; 500 buf->f_namelen = SQUASHFS_NAME_LEN; 501 buf->f_fsid = u64_to_fsid(id); 502 503 return 0; 504 } 505 506 507 static void squashfs_put_super(struct super_block *sb) 508 { 509 if (sb->s_fs_info) { 510 struct squashfs_sb_info *sbi = sb->s_fs_info; 511 squashfs_cache_delete(sbi->block_cache); 512 squashfs_cache_delete(sbi->fragment_cache); 513 squashfs_cache_delete(sbi->read_page); 514 squashfs_decompressor_destroy(sbi); 515 kfree(sbi->id_table); 516 kfree(sbi->fragment_index); 517 kfree(sbi->meta_index); 518 kfree(sbi->inode_lookup_table); 519 kfree(sbi->xattr_id_table); 520 kfree(sb->s_fs_info); 521 sb->s_fs_info = NULL; 522 } 523 } 524 525 static struct kmem_cache *squashfs_inode_cachep; 526 527 528 static void init_once(void *foo) 529 { 530 struct squashfs_inode_info *ei = foo; 531 532 inode_init_once(&ei->vfs_inode); 533 } 534 535 536 static int __init init_inodecache(void) 537 { 538 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache", 539 sizeof(struct squashfs_inode_info), 0, 540 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT, 541 init_once); 542 543 return squashfs_inode_cachep ? 0 : -ENOMEM; 544 } 545 546 547 static void destroy_inodecache(void) 548 { 549 /* 550 * Make sure all delayed rcu free inodes are flushed before we 551 * destroy cache. 552 */ 553 rcu_barrier(); 554 kmem_cache_destroy(squashfs_inode_cachep); 555 } 556 557 558 static int __init init_squashfs_fs(void) 559 { 560 int err = init_inodecache(); 561 562 if (err) 563 return err; 564 565 err = register_filesystem(&squashfs_fs_type); 566 if (err) { 567 destroy_inodecache(); 568 return err; 569 } 570 571 pr_info("version 4.0 (2009/01/31) Phillip Lougher\n"); 572 573 return 0; 574 } 575 576 577 static void __exit exit_squashfs_fs(void) 578 { 579 unregister_filesystem(&squashfs_fs_type); 580 destroy_inodecache(); 581 } 582 583 584 static struct inode *squashfs_alloc_inode(struct super_block *sb) 585 { 586 struct squashfs_inode_info *ei = 587 alloc_inode_sb(sb, squashfs_inode_cachep, GFP_KERNEL); 588 589 return ei ? &ei->vfs_inode : NULL; 590 } 591 592 593 static void squashfs_free_inode(struct inode *inode) 594 { 595 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); 596 } 597 598 static struct file_system_type squashfs_fs_type = { 599 .owner = THIS_MODULE, 600 .name = "squashfs", 601 .init_fs_context = squashfs_init_fs_context, 602 .parameters = squashfs_fs_parameters, 603 .kill_sb = kill_block_super, 604 .fs_flags = FS_REQUIRES_DEV 605 }; 606 MODULE_ALIAS_FS("squashfs"); 607 608 static const struct super_operations squashfs_super_ops = { 609 .alloc_inode = squashfs_alloc_inode, 610 .free_inode = squashfs_free_inode, 611 .statfs = squashfs_statfs, 612 .put_super = squashfs_put_super, 613 .show_options = squashfs_show_options, 614 }; 615 616 module_init(init_squashfs_fs); 617 module_exit(exit_squashfs_fs); 618 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); 619 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>"); 620 MODULE_LICENSE("GPL"); 621