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#include <linux/backing-dev.h> 30 31#include "squashfs_fs.h" 32#include "squashfs_fs_sb.h" 33#include "squashfs_fs_i.h" 34#include "squashfs.h" 35#include "decompressor.h" 36#include "xattr.h" 37 38static struct file_system_type squashfs_fs_type; 39static const struct super_operations squashfs_super_ops; 40 41static const struct squashfs_decompressor *supported_squashfs_filesystem( 42 struct fs_context *fc, 43 short major, short minor, short id) 44{ 45 const struct squashfs_decompressor *decompressor; 46 47 if (major < SQUASHFS_MAJOR) { 48 errorf(fc, "Major/Minor mismatch, older Squashfs %d.%d " 49 "filesystems are unsupported", major, minor); 50 return NULL; 51 } else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) { 52 errorf(fc, "Major/Minor mismatch, trying to mount newer " 53 "%d.%d filesystem", major, minor); 54 errorf(fc, "Please update your kernel"); 55 return NULL; 56 } 57 58 decompressor = squashfs_lookup_decompressor(id); 59 if (!decompressor->supported) { 60 errorf(fc, "Filesystem uses \"%s\" compression. This is not supported", 61 decompressor->name); 62 return NULL; 63 } 64 65 return decompressor; 66} 67 68static int squashfs_bdi_init(struct super_block *sb) 69{ 70 int err; 71 unsigned int major = MAJOR(sb->s_dev); 72 unsigned int minor = MINOR(sb->s_dev); 73 74 bdi_put(sb->s_bdi); 75 sb->s_bdi = &noop_backing_dev_info; 76 77 err = super_setup_bdi_name(sb, "squashfs_%u_%u", major, minor); 78 if (err) 79 return err; 80 81 sb->s_bdi->ra_pages = 0; 82 sb->s_bdi->io_pages = 0; 83 84 return 0; 85} 86 87static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc) 88{ 89 struct squashfs_sb_info *msblk; 90 struct squashfs_super_block *sblk = NULL; 91 struct inode *root; 92 long long root_inode; 93 unsigned short flags; 94 unsigned int fragments; 95 u64 lookup_table_start, xattr_id_table_start, next_table; 96 int err; 97 98 TRACE("Entered squashfs_fill_superblock\n"); 99 100 /* 101 * squashfs provides 'backing_dev_info' in order to disable read-ahead. For 102 * squashfs, I/O is not deferred, it is done immediately in readpage, 103 * which means the user would have to wait not just for their own I/O 104 * but the read-ahead I/O as well i.e. completely pointless.squashfs_bdi_init 105 * will set sb->s_bdi->ra_pages and sb->s_bdi->io_pages to 0. 106 */ 107 err = squashfs_bdi_init(sb); 108 if (err) { 109 errorf(fc, "squashfs init bdi failed"); 110 return err; 111 } 112 113 sb->s_fs_info = kzalloc(sizeof(*msblk), GFP_KERNEL); 114 if (sb->s_fs_info == NULL) { 115 ERROR("Failed to allocate squashfs_sb_info\n"); 116 return -ENOMEM; 117 } 118 msblk = sb->s_fs_info; 119 120 msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE); 121 msblk->devblksize_log2 = ffz(~msblk->devblksize); 122 123 mutex_init(&msblk->meta_index_mutex); 124 125 /* 126 * msblk->bytes_used is checked in squashfs_read_table to ensure reads 127 * are not beyond filesystem end. But as we're using 128 * squashfs_read_table here to read the superblock (including the value 129 * of bytes_used) we need to set it to an initial sensible dummy value 130 */ 131 msblk->bytes_used = sizeof(*sblk); 132 sblk = squashfs_read_table(sb, SQUASHFS_START, sizeof(*sblk)); 133 134 if (IS_ERR(sblk)) { 135 errorf(fc, "unable to read squashfs_super_block"); 136 err = PTR_ERR(sblk); 137 sblk = NULL; 138 goto failed_mount; 139 } 140 141 err = -EINVAL; 142 143 /* Check it is a SQUASHFS superblock */ 144 sb->s_magic = le32_to_cpu(sblk->s_magic); 145 if (sb->s_magic != SQUASHFS_MAGIC) { 146 if (!(fc->sb_flags & SB_SILENT)) 147 errorf(fc, "Can't find a SQUASHFS superblock on %pg", 148 sb->s_bdev); 149 goto failed_mount; 150 } 151 152 /* Check the MAJOR & MINOR versions and lookup compression type */ 153 msblk->decompressor = supported_squashfs_filesystem( 154 fc, 155 le16_to_cpu(sblk->s_major), 156 le16_to_cpu(sblk->s_minor), 157 le16_to_cpu(sblk->compression)); 158 if (msblk->decompressor == NULL) 159 goto failed_mount; 160 161 /* Check the filesystem does not extend beyond the end of the 162 block device */ 163 msblk->bytes_used = le64_to_cpu(sblk->bytes_used); 164 if (msblk->bytes_used < 0 || msblk->bytes_used > 165 i_size_read(sb->s_bdev->bd_inode)) 166 goto failed_mount; 167 168 /* Check block size for sanity */ 169 msblk->block_size = le32_to_cpu(sblk->block_size); 170 if (msblk->block_size > SQUASHFS_FILE_MAX_SIZE) 171 goto insanity; 172 173 /* 174 * Check the system page size is not larger than the filesystem 175 * block size (by default 128K). This is currently not supported. 176 */ 177 if (PAGE_SIZE > msblk->block_size) { 178 errorf(fc, "Page size > filesystem block size (%d). This is " 179 "currently not supported!", msblk->block_size); 180 goto failed_mount; 181 } 182 183 /* Check block log for sanity */ 184 msblk->block_log = le16_to_cpu(sblk->block_log); 185 if (msblk->block_log > SQUASHFS_FILE_MAX_LOG) 186 goto failed_mount; 187 188 /* Check that block_size and block_log match */ 189 if (msblk->block_size != (1 << msblk->block_log)) 190 goto insanity; 191 192 /* Check the root inode for sanity */ 193 root_inode = le64_to_cpu(sblk->root_inode); 194 if (SQUASHFS_INODE_OFFSET(root_inode) > SQUASHFS_METADATA_SIZE) 195 goto insanity; 196 197 msblk->inode_table = le64_to_cpu(sblk->inode_table_start); 198 msblk->directory_table = le64_to_cpu(sblk->directory_table_start); 199 msblk->inodes = le32_to_cpu(sblk->inodes); 200 msblk->fragments = le32_to_cpu(sblk->fragments); 201 msblk->ids = le16_to_cpu(sblk->no_ids); 202 flags = le16_to_cpu(sblk->flags); 203 204 TRACE("Found valid superblock on %pg\n", sb->s_bdev); 205 TRACE("Inodes are %scompressed\n", SQUASHFS_UNCOMPRESSED_INODES(flags) 206 ? "un" : ""); 207 TRACE("Data is %scompressed\n", SQUASHFS_UNCOMPRESSED_DATA(flags) 208 ? "un" : ""); 209 TRACE("Filesystem size %lld bytes\n", msblk->bytes_used); 210 TRACE("Block size %d\n", msblk->block_size); 211 TRACE("Number of inodes %d\n", msblk->inodes); 212 TRACE("Number of fragments %d\n", msblk->fragments); 213 TRACE("Number of ids %d\n", msblk->ids); 214 TRACE("sblk->inode_table_start %llx\n", msblk->inode_table); 215 TRACE("sblk->directory_table_start %llx\n", msblk->directory_table); 216 TRACE("sblk->fragment_table_start %llx\n", 217 (u64) le64_to_cpu(sblk->fragment_table_start)); 218 TRACE("sblk->id_table_start %llx\n", 219 (u64) le64_to_cpu(sblk->id_table_start)); 220 221 sb->s_maxbytes = MAX_LFS_FILESIZE; 222 sb->s_time_min = 0; 223 sb->s_time_max = U32_MAX; 224 sb->s_flags |= SB_RDONLY; 225 sb->s_op = &squashfs_super_ops; 226 227 err = -ENOMEM; 228 229 msblk->block_cache = squashfs_cache_init("metadata", 230 SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE); 231 if (msblk->block_cache == NULL) 232 goto failed_mount; 233 234 /* Allocate read_page block */ 235 msblk->read_page = squashfs_cache_init("data", 236 squashfs_max_decompressors(), msblk->block_size); 237 if (msblk->read_page == NULL) { 238 errorf(fc, "Failed to allocate read_page block"); 239 goto failed_mount; 240 } 241 242 msblk->stream = squashfs_decompressor_setup(sb, flags); 243 if (IS_ERR(msblk->stream)) { 244 err = PTR_ERR(msblk->stream); 245 msblk->stream = NULL; 246 goto insanity; 247 } 248 249 /* Handle xattrs */ 250 sb->s_xattr = squashfs_xattr_handlers; 251 xattr_id_table_start = le64_to_cpu(sblk->xattr_id_table_start); 252 if (xattr_id_table_start == SQUASHFS_INVALID_BLK) { 253 next_table = msblk->bytes_used; 254 goto allocate_id_index_table; 255 } 256 257 /* Allocate and read xattr id lookup table */ 258 msblk->xattr_id_table = squashfs_read_xattr_id_table(sb, 259 xattr_id_table_start, &msblk->xattr_table, &msblk->xattr_ids); 260 if (IS_ERR(msblk->xattr_id_table)) { 261 errorf(fc, "unable to read xattr id index table"); 262 err = PTR_ERR(msblk->xattr_id_table); 263 msblk->xattr_id_table = NULL; 264 if (err != -ENOTSUPP) 265 goto failed_mount; 266 } 267 next_table = msblk->xattr_table; 268 269allocate_id_index_table: 270 /* Allocate and read id index table */ 271 msblk->id_table = squashfs_read_id_index_table(sb, 272 le64_to_cpu(sblk->id_table_start), next_table, msblk->ids); 273 if (IS_ERR(msblk->id_table)) { 274 errorf(fc, "unable to read id index table"); 275 err = PTR_ERR(msblk->id_table); 276 msblk->id_table = NULL; 277 goto failed_mount; 278 } 279 next_table = le64_to_cpu(msblk->id_table[0]); 280 281 /* Handle inode lookup table */ 282 lookup_table_start = le64_to_cpu(sblk->lookup_table_start); 283 if (lookup_table_start == SQUASHFS_INVALID_BLK) 284 goto handle_fragments; 285 286 /* Allocate and read inode lookup table */ 287 msblk->inode_lookup_table = squashfs_read_inode_lookup_table(sb, 288 lookup_table_start, next_table, msblk->inodes); 289 if (IS_ERR(msblk->inode_lookup_table)) { 290 errorf(fc, "unable to read inode lookup table"); 291 err = PTR_ERR(msblk->inode_lookup_table); 292 msblk->inode_lookup_table = NULL; 293 goto failed_mount; 294 } 295 next_table = le64_to_cpu(msblk->inode_lookup_table[0]); 296 297 sb->s_export_op = &squashfs_export_ops; 298 299handle_fragments: 300 fragments = msblk->fragments; 301 if (fragments == 0) 302 goto check_directory_table; 303 304 msblk->fragment_cache = squashfs_cache_init("fragment", 305 SQUASHFS_CACHED_FRAGMENTS, msblk->block_size); 306 if (msblk->fragment_cache == NULL) { 307 err = -ENOMEM; 308 goto failed_mount; 309 } 310 311 /* Allocate and read fragment index table */ 312 msblk->fragment_index = squashfs_read_fragment_index_table(sb, 313 le64_to_cpu(sblk->fragment_table_start), next_table, fragments); 314 if (IS_ERR(msblk->fragment_index)) { 315 errorf(fc, "unable to read fragment index table"); 316 err = PTR_ERR(msblk->fragment_index); 317 msblk->fragment_index = NULL; 318 goto failed_mount; 319 } 320 next_table = le64_to_cpu(msblk->fragment_index[0]); 321 322check_directory_table: 323 /* Sanity check directory_table */ 324 if (msblk->directory_table > next_table) { 325 err = -EINVAL; 326 goto insanity; 327 } 328 329 /* Sanity check inode_table */ 330 if (msblk->inode_table >= msblk->directory_table) { 331 err = -EINVAL; 332 goto insanity; 333 } 334 335 /* allocate root */ 336 root = new_inode(sb); 337 if (!root) { 338 err = -ENOMEM; 339 goto failed_mount; 340 } 341 342 err = squashfs_read_inode(root, root_inode); 343 if (err) { 344 make_bad_inode(root); 345 iput(root); 346 goto failed_mount; 347 } 348 insert_inode_hash(root); 349 350 sb->s_root = d_make_root(root); 351 if (sb->s_root == NULL) { 352 ERROR("Root inode create failed\n"); 353 err = -ENOMEM; 354 goto failed_mount; 355 } 356 357 TRACE("Leaving squashfs_fill_super\n"); 358 kfree(sblk); 359 return 0; 360 361insanity: 362 errorf(fc, "squashfs image failed sanity check"); 363failed_mount: 364 squashfs_cache_delete(msblk->block_cache); 365 squashfs_cache_delete(msblk->fragment_cache); 366 squashfs_cache_delete(msblk->read_page); 367 squashfs_decompressor_destroy(msblk); 368 kfree(msblk->inode_lookup_table); 369 kfree(msblk->fragment_index); 370 kfree(msblk->id_table); 371 kfree(msblk->xattr_id_table); 372 kfree(sb->s_fs_info); 373 sb->s_fs_info = NULL; 374 kfree(sblk); 375 return err; 376} 377 378static int squashfs_get_tree(struct fs_context *fc) 379{ 380 return get_tree_bdev(fc, squashfs_fill_super); 381} 382 383static int squashfs_reconfigure(struct fs_context *fc) 384{ 385 sync_filesystem(fc->root->d_sb); 386 fc->sb_flags |= SB_RDONLY; 387 return 0; 388} 389 390static const struct fs_context_operations squashfs_context_ops = { 391 .get_tree = squashfs_get_tree, 392 .reconfigure = squashfs_reconfigure, 393}; 394 395static int squashfs_init_fs_context(struct fs_context *fc) 396{ 397 fc->ops = &squashfs_context_ops; 398 return 0; 399} 400 401static int squashfs_statfs(struct dentry *dentry, struct kstatfs *buf) 402{ 403 struct squashfs_sb_info *msblk = dentry->d_sb->s_fs_info; 404 u64 id = huge_encode_dev(dentry->d_sb->s_bdev->bd_dev); 405 406 TRACE("Entered squashfs_statfs\n"); 407 408 buf->f_type = SQUASHFS_MAGIC; 409 buf->f_bsize = msblk->block_size; 410 buf->f_blocks = ((msblk->bytes_used - 1) >> msblk->block_log) + 1; 411 buf->f_bfree = buf->f_bavail = 0; 412 buf->f_files = msblk->inodes; 413 buf->f_ffree = 0; 414 buf->f_namelen = SQUASHFS_NAME_LEN; 415 buf->f_fsid = u64_to_fsid(id); 416 417 return 0; 418} 419 420 421static void squashfs_put_super(struct super_block *sb) 422{ 423 if (sb->s_fs_info) { 424 struct squashfs_sb_info *sbi = sb->s_fs_info; 425 squashfs_cache_delete(sbi->block_cache); 426 squashfs_cache_delete(sbi->fragment_cache); 427 squashfs_cache_delete(sbi->read_page); 428 squashfs_decompressor_destroy(sbi); 429 kfree(sbi->id_table); 430 kfree(sbi->fragment_index); 431 kfree(sbi->meta_index); 432 kfree(sbi->inode_lookup_table); 433 kfree(sbi->xattr_id_table); 434 kfree(sb->s_fs_info); 435 sb->s_fs_info = NULL; 436 } 437} 438 439static struct kmem_cache *squashfs_inode_cachep; 440 441 442static void init_once(void *foo) 443{ 444 struct squashfs_inode_info *ei = foo; 445 446 inode_init_once(&ei->vfs_inode); 447} 448 449 450static int __init init_inodecache(void) 451{ 452 squashfs_inode_cachep = kmem_cache_create("squashfs_inode_cache", 453 sizeof(struct squashfs_inode_info), 0, 454 SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT, 455 init_once); 456 457 return squashfs_inode_cachep ? 0 : -ENOMEM; 458} 459 460 461static void destroy_inodecache(void) 462{ 463 /* 464 * Make sure all delayed rcu free inodes are flushed before we 465 * destroy cache. 466 */ 467 rcu_barrier(); 468 kmem_cache_destroy(squashfs_inode_cachep); 469} 470 471 472static int __init init_squashfs_fs(void) 473{ 474 int err = init_inodecache(); 475 476 if (err) 477 return err; 478 479 err = register_filesystem(&squashfs_fs_type); 480 if (err) { 481 destroy_inodecache(); 482 return err; 483 } 484 485 pr_info("version 4.0 (2009/01/31) Phillip Lougher\n"); 486 487 return 0; 488} 489 490 491static void __exit exit_squashfs_fs(void) 492{ 493 unregister_filesystem(&squashfs_fs_type); 494 destroy_inodecache(); 495} 496 497 498static struct inode *squashfs_alloc_inode(struct super_block *sb) 499{ 500 struct squashfs_inode_info *ei = 501 kmem_cache_alloc(squashfs_inode_cachep, GFP_KERNEL); 502 503 return ei ? &ei->vfs_inode : NULL; 504} 505 506 507static void squashfs_free_inode(struct inode *inode) 508{ 509 kmem_cache_free(squashfs_inode_cachep, squashfs_i(inode)); 510} 511 512static struct file_system_type squashfs_fs_type = { 513 .owner = THIS_MODULE, 514 .name = "squashfs", 515 .init_fs_context = squashfs_init_fs_context, 516 .kill_sb = kill_block_super, 517 .fs_flags = FS_REQUIRES_DEV 518}; 519MODULE_ALIAS_FS("squashfs"); 520 521static const struct super_operations squashfs_super_ops = { 522 .alloc_inode = squashfs_alloc_inode, 523 .free_inode = squashfs_free_inode, 524 .statfs = squashfs_statfs, 525 .put_super = squashfs_put_super, 526}; 527 528module_init(init_squashfs_fs); 529module_exit(exit_squashfs_fs); 530MODULE_DESCRIPTION("squashfs 4.0, a compressed read-only filesystem"); 531MODULE_AUTHOR("Phillip Lougher <phillip@squashfs.org.uk>"); 532MODULE_LICENSE("GPL"); 533