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