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/vfs.h> 21 #include <linux/slab.h> 22 #include <linux/mutex.h> 23 #include <linux/pagemap.h> 24 #include <linux/init.h> 25 #include <linux/module.h> 26 #include <linux/magic.h> 27 #include <linux/xattr.h> 28 29 #include "squashfs_fs.h" 30 #include "squashfs_fs_sb.h" 31 #include "squashfs_fs_i.h" 32 #include "squashfs.h" 33 #include "decompressor.h" 34 #include "xattr.h" 35 36 static struct file_system_type squashfs_fs_type; 37 static const struct super_operations squashfs_super_ops; 38 39 static const struct squashfs_decompressor *supported_squashfs_filesystem(short 40 major, short minor, short id) 41 { 42 const struct squashfs_decompressor *decompressor; 43 44 if (major < SQUASHFS_MAJOR) { 45 ERROR("Major/Minor mismatch, older Squashfs %d.%d " 46 "filesystems are unsupported\n", major, minor); 47 return NULL; 48 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) { 49 ERROR("Major/Minor mismatch, trying to mount newer " 50 "%d.%d filesystem\n", major, minor); 51 ERROR("Please update your kernel\n"); 52 return NULL; 53 } 54 55 decompressor = squashfs_lookup_decompressor(id); 56 if (!decompressor->supported) { 57 ERROR("Filesystem uses \"%s\" compression. This is not " 58 "supported\n", decompressor->name); 59 return NULL; 60 } 61 62 return decompressor; 63 } 64 65 66 static int squashfs_fill_super(struct super_block *sb, void *data, int silent) 67 { 68 struct squashfs_sb_info *msblk; 69 struct squashfs_super_block *sblk = NULL; 70 struct inode *root; 71 long long root_inode; 72 unsigned short flags; 73 unsigned int fragments; 74 u64 lookup_table_start, xattr_id_table_start, next_table; 75 int err; 76 77 TRACE("Entered squashfs_fill_superblock\n"); 78 79 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL); 80 if (sb->s_fs_info == NULL) { 81 ERROR("Failed to allocate squashfs_sb_info\n"); 82 return -ENOMEM; 83 } 84 msblk = sb->s_fs_info; 85 86 msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE); 87 msblk->devblksize_log2 = ffz(~msblk->devblksize); 88 89 mutex_init(&msblk->meta_index_mutex); 90 91 /* 92 * msblk->bytes_used is checked in squashfs_read_table to ensure reads 93 * are not beyond filesystem end. But as we're using 94 * squashfs_read_table here to read the superblock (including the value 95 * of bytes_used) we need to set it to an initial sensible dummy value 96 */ 97 msblk->bytes_used = sizeof(*sblk); 98 sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk)); 99 100 if (IS_ERR(sblk)) { 101 ERROR("unable to read squashfs_super_block\n"); 102 err = PTR_ERR(sblk); 103 sblk = NULL; 104 goto failed_mount; 105 } 106 107 err = -EINVAL; 108 109 /* Check it is a SQUASHFS superblock */ 110 sb->s_magic = le32_to_cpu(sblk->s_magic); 111 if (sb->s_magic != SQUASHFS_MAGIC) { 112 if (!silent) 113 ERROR("Can't find a SQUASHFS superblock on %pg\n", 114 sb->s_bdev); 115 goto failed_mount; 116 } 117 118 /* Check the MAJOR & MINOR versions and lookup compression type */ 119 msblk->decompressor = supported_squashfs_filesystem( 120 le16_to_cpu(sblk->s_major), 121 le16_to_cpu(sblk->s_minor), 122 le16_to_cpu(sblk->compression)); 123 if (msblk->decompressor == NULL) 124 goto failed_mount; 125 126 /* Check the filesystem does not extend beyond the end of the 127 block device */ 128 msblk->bytes_used = le64_to_cpu(sblk->bytes_used); 129 if (msblk->bytes_used < 0 || msblk->bytes_used > 130 i_size_read(sb->s_bdev->bd_inode)) 131 goto failed_mount; 132 133 /* Check block size for sanity */ 134 msblk->block_size = le32_to_cpu(sblk->block_size); 135 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE) 136 goto failed_mount; 137 138 /* 139 * Check the system page size is not larger than the filesystem 140 * block size (by default 128K). This is currently not supported. 141 */ 142 if (PAGE_SIZE > msblk->block_size) { 143 ERROR("Page size > filesystem block size (%d). This is " 144 "currently not supported!\n", msblk->block_size); 145 goto failed_mount; 146 } 147 148 /* Check block log for sanity */ 149 msblk->block_log = le16_to_cpu(sblk->block_log); 150 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) 151 goto failed_mount; 152 153 /* Check that block_size and block_log match */ 154 if (msblk->block_size != (1 << msblk->block_log)) 155 goto failed_mount; 156 157 /* Check the root inode for sanity */ 158 root_inode = le64_to_cpu(sblk->root_inode); 159 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE) 160 goto failed_mount; 161 162 msblk->inode_table = le64_to_cpu(sblk->inode_table_start); 163 msblk->directory_table = le64_to_cpu(sblk->directory_table_start); 164 msblk->inodes = le32_to_cpu(sblk->inodes); 165 msblk->fragments = le32_to_cpu(sblk->fragments); 166 flags = le16_to_cpu(sblk->flags); 167 168 TRACE("Found valid superblock on %pg\n", sb->s_bdev); 169 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags) 170 ? "un" : ""); 171 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags) 172 ? "un" : ""); 173 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used); 174 TRACE("Block size %d\n", msblk->block_size); 175 TRACE("Number of inodes %d\n", msblk->inodes); 176 TRACE("Number of fragments %d\n", msblk->fragments); 177 TRACE("Number of ids %d\n", le16_to_cpu(sblk->no_ids)); 178 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table); 179 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table); 180 TRACE("sblk->fragment_table_start %llx\n", 181 (u64) le64_to_cpu(sblk->fragment_table_start)); 182 TRACE("sblk->id_table_start %llx\n", 183 (u64) le64_to_cpu(sblk->id_table_start)); 184 185 sb->s_maxbytes = MAX_LFS_FILESIZE; 186 sb->s_flags |= SB_RDONLY; 187 sb->s_op = &squashfs_super_ops; 188 189 err = -ENOMEM; 190 191 msblk->block_cache = squashfs_cache_init("metadata", 192 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE); 193 if (msblk->block_cache == NULL) 194 goto failed_mount; 195 196 /* Allocate read_page block */ 197 msblk->read_page = squashfs_cache_init("data", 198 squashfs_max_decompressors(), msblk->block_size); 199 if (msblk->read_page == NULL) { 200 ERROR("Failed to allocate read_page block\n"); 201 goto failed_mount; 202 } 203 204 msblk->stream = squashfs_decompressor_setup(sb, flags); 205 if (IS_ERR(msblk->stream)) { 206 err = PTR_ERR(msblk->stream); 207 msblk->stream = NULL; 208 goto failed_mount; 209 } 210 211 /* Handle xattrs */ 212 sb->s_xattr = squashfs_xattr_handlers; 213 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start); 214 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) { 215 next_table = msblk->bytes_used; 216 goto allocate_id_index_table; 217 } 218 219 /* Allocate and read xattr id lookup table */ 220 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb, 221 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids); 222 if (IS_ERR(msblk->xattr_id_table)) { 223 ERROR("unable to read xattr id index table\n"); 224 err = PTR_ERR(msblk->xattr_id_table); 225 msblk->xattr_id_table = NULL; 226 if (err != -ENOTSUPP) 227 goto failed_mount; 228 } 229 next_table = msblk->xattr_table; 230 231 allocate_id_index_table: 232 /* Allocate and read id index table */ 233 msblk->id_table = squashfs_read_id_index_table(sb, 234 le64_to_cpu(sblk->id_table_start), next_table, 235 le16_to_cpu(sblk->no_ids)); 236 if (IS_ERR(msblk->id_table)) { 237 ERROR("unable to read id index table\n"); 238 err = PTR_ERR(msblk->id_table); 239 msblk->id_table = NULL; 240 goto failed_mount; 241 } 242 next_table = le64_to_cpu(msblk->id_table[0]); 243 244 /* Handle inode lookup table */ 245 lookup_table_start = le64_to_cpu(sblk->lookup_table_start); 246 if (lookup_table_start == SQUASHFS_INVALID_BLK) 247 goto handle_fragments; 248 249 /* Allocate and read inode lookup table */ 250 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb, 251 lookup_table_start, next_table, msblk->inodes); 252 if (IS_ERR(msblk->inode_lookup_table)) { 253 ERROR("unable to read inode lookup table\n"); 254 err = PTR_ERR(msblk->inode_lookup_table); 255 msblk->inode_lookup_table = NULL; 256 goto failed_mount; 257 } 258 next_table = le64_to_cpu(msblk->inode_lookup_table[0]); 259 260 sb->s_export_op = &squashfs_export_ops; 261 262 handle_fragments: 263 fragments = msblk->fragments; 264 if (fragments == 0) 265 goto check_directory_table; 266 267 msblk->fragment_cache = squashfs_cache_init("fragment", 268 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size); 269 if (msblk->fragment_cache == NULL) { 270 err = -ENOMEM; 271 goto failed_mount; 272 } 273 274 /* Allocate and read fragment index table */ 275 msblk->fragment_index = squashfs_read_fragment_index_table(sb, 276 le64_to_cpu(sblk->fragment_table_start), next_table, fragments); 277 if (IS_ERR(msblk->fragment_index)) { 278 ERROR("unable to read fragment index table\n"); 279 err = PTR_ERR(msblk->fragment_index); 280 msblk->fragment_index = NULL; 281 goto failed_mount; 282 } 283 next_table = le64_to_cpu(msblk->fragment_index[0]); 284 285 check_directory_table: 286 /* Sanity check directory_table */ 287 if (msblk->directory_table > next_table) { 288 err = -EINVAL; 289 goto failed_mount; 290 } 291 292 /* Sanity check inode_table */ 293 if (msblk->inode_table >= msblk->directory_table) { 294 err = -EINVAL; 295 goto failed_mount; 296 } 297 298 /* allocate root */ 299 root = new_inode(sb); 300 if (!root) { 301 err = -ENOMEM; 302 goto failed_mount; 303 } 304 305 err = squashfs_read_inode(root, root_inode); 306 if (err) { 307 make_bad_inode(root); 308 iput(root); 309 goto failed_mount; 310 } 311 insert_inode_hash(root); 312 313 sb->s_root = d_make_root(root); 314 if (sb->s_root == NULL) { 315 ERROR("Root inode create failed\n"); 316 err = -ENOMEM; 317 goto failed_mount; 318 } 319 320 TRACE("Leaving squashfs_fill_super\n"); 321 kfree(sblk); 322 return 0; 323 324 failed_mount: 325 squashfs_cache_delete(msblk->block_cache); 326 squashfs_cache_delete(msblk->fragment_cache); 327 squashfs_cache_delete(msblk->read_page); 328 squashfs_decompressor_destroy(msblk); 329 kfree(msblk->inode_lookup_table); 330 kfree(msblk->fragment_index); 331 kfree(msblk->id_table); 332 kfree(msblk->xattr_id_table); 333 kfree(sb->s_fs_info); 334 sb->s_fs_info = NULL; 335 kfree(sblk); 336 return err; 337 } 338 339 340 static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) 341 { 342 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; 343 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev); 344 345 TRACE("Entered squashfs_statfs\n"); 346 347 buf->f_type = SQUASHFS_MAGIC; 348 buf->f_bsize = msblk->block_size; 349 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1; 350 buf->f_bfree = buf->f_bavail = 0; 351 buf->f_files = msblk->inodes; 352 buf->f_ffree = 0; 353 buf->f_namelen = SQUASHFS_NAME_LEN; 354 buf->f_fsid.val[0] = (u32)id; 355 buf->f_fsid.val[1] = (u32)(id >> 32); 356 357 return 0; 358 } 359 360 361 static int squashfs_remount(struct super_block *sb, int *flags, char *data) 362 { 363 sync_filesystem(sb); 364 *flags |= SB_RDONLY; 365 return 0; 366 } 367 368 369 static void squashfs_put_super(struct super_block *sb) 370 { 371 if (sb->s_fs_info) { 372 struct squashfs_sb_info *sbi = sb->s_fs_info; 373 squashfs_cache_delete(sbi->block_cache); 374 squashfs_cache_delete(sbi->fragment_cache); 375 squashfs_cache_delete(sbi->read_page); 376 squashfs_decompressor_destroy(sbi); 377 kfree(sbi->id_table); 378 kfree(sbi->fragment_index); 379 kfree(sbi->meta_index); 380 kfree(sbi->inode_lookup_table); 381 kfree(sbi->xattr_id_table); 382 kfree(sb->s_fs_info); 383 sb->s_fs_info = NULL; 384 } 385 } 386 387 388 static struct dentry *squashfs_mount(struct file_system_type *fs_type, 389 int flags, const char *dev_name, void *data) 390 { 391 return mount_bdev(fs_type, flags, dev_name, data, squashfs_fill_super); 392 } 393 394 395 static struct kmem_cache *squashfs_inode_cachep; 396 397 398 static void init_once(void *foo) 399 { 400 struct squashfs_inode_info *ei = foo; 401 402 inode_init_once(&ei->vfs_inode); 403 } 404 405 406 static int __init init_inodecache(void) 407 { 408 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache", 409 sizeof(struct squashfs_inode_info), 0, 410 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT, 411 init_once); 412 413 return squashfs_inode_cachep ? 0 : -ENOMEM; 414 } 415 416 417 static void destroy_inodecache(void) 418 { 419 /* 420 * Make sure all delayed rcu free inodes are flushed before we 421 * destroy cache. 422 */ 423 rcu_barrier(); 424 kmem_cache_destroy(squashfs_inode_cachep); 425 } 426 427 428 static int __init init_squashfs_fs(void) 429 { 430 int err = init_inodecache(); 431 432 if (err) 433 return err; 434 435 err = register_filesystem(&squashfs_fs_type); 436 if (err) { 437 destroy_inodecache(); 438 return err; 439 } 440 441 pr_info("version 4.0 (2009/01/31) Phillip Lougher\n"); 442 443 return 0; 444 } 445 446 447 static void __exit exit_squashfs_fs(void) 448 { 449 unregister_filesystem(&squashfs_fs_type); 450 destroy_inodecache(); 451 } 452 453 454 static struct inode *squashfs_alloc_inode(struct super_block *sb) 455 { 456 struct squashfs_inode_info *ei = 457 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL); 458 459 return ei ? &ei->vfs_inode : NULL; 460 } 461 462 463 static void squashfs_free_inode(struct inode *inode) 464 { 465 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); 466 } 467 468 static struct file_system_type squashfs_fs_type = { 469 .owner = THIS_MODULE, 470 .name = "squashfs", 471 .mount = squashfs_mount, 472 .kill_sb = kill_block_super, 473 .fs_flags = FS_REQUIRES_DEV 474 }; 475 MODULE_ALIAS_FS("squashfs"); 476 477 static const struct super_operations squashfs_super_ops = { 478 .alloc_inode = squashfs_alloc_inode, 479 .free_inode = squashfs_free_inode, 480 .statfs = squashfs_statfs, 481 .put_super = squashfs_put_super, 482 .remount_fs = squashfs_remount 483 }; 484 485 module_init(init_squashfs_fs); 486 module_exit(exit_squashfs_fs); 487 MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); 488 MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>"); 489 MODULE_LICENSE("GPL"); 490