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"); 587