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"); 588