fs/squashfs/super.c

   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");