1 /* Block- or MTD-based romfs 2 * 3 * Copyright © 2007 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells (dhowells@redhat.com) 5 * 6 * Derived from: ROMFS file system, Linux implementation 7 * 8 * Copyright © 1997-1999 Janos Farkas <chexum@shadow.banki.hu> 9 * 10 * Using parts of the minix filesystem 11 * Copyright © 1991, 1992 Linus Torvalds 12 * 13 * and parts of the affs filesystem additionally 14 * Copyright © 1993 Ray Burr 15 * Copyright © 1996 Hans-Joachim Widmaier 16 * 17 * Changes 18 * Changed for 2.1.19 modules 19 * Jan 1997 Initial release 20 * Jun 1997 2.1.43+ changes 21 * Proper page locking in readpage 22 * Changed to work with 2.1.45+ fs 23 * Jul 1997 Fixed follow_link 24 * 2.1.47 25 * lookup shouldn't return -ENOENT 26 * from Horst von Brand: 27 * fail on wrong checksum 28 * double unlock_super was possible 29 * correct namelen for statfs 30 * spotted by Bill Hawes: 31 * readlink shouldn't iput() 32 * Jun 1998 2.1.106 from Avery Pennarun: glibc scandir() 33 * exposed a problem in readdir 34 * 2.1.107 code-freeze spellchecker run 35 * Aug 1998 2.1.118+ VFS changes 36 * Sep 1998 2.1.122 another VFS change (follow_link) 37 * Apr 1999 2.2.7 no more EBADF checking in 38 * lookup/readdir, use ERR_PTR 39 * Jun 1999 2.3.6 d_alloc_root use changed 40 * 2.3.9 clean up usage of ENOENT/negative 41 * dentries in lookup 42 * clean up page flags setting 43 * (error, uptodate, locking) in 44 * in readpage 45 * use init_special_inode for 46 * fifos/sockets (and streamline) in 47 * read_inode, fix _ops table order 48 * Aug 1999 2.3.16 __initfunc() => __init change 49 * Oct 1999 2.3.24 page->owner hack obsoleted 50 * Nov 1999 2.3.27 2.3.25+ page->offset => index change 51 * 52 * 53 * This program is free software; you can redistribute it and/or 54 * modify it under the terms of the GNU General Public Licence 55 * as published by the Free Software Foundation; either version 56 * 2 of the Licence, or (at your option) any later version. 57 */ 58 59 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 60 61 #include <linux/module.h> 62 #include <linux/string.h> 63 #include <linux/fs.h> 64 #include <linux/time.h> 65 #include <linux/slab.h> 66 #include <linux/init.h> 67 #include <linux/blkdev.h> 68 #include <linux/parser.h> 69 #include <linux/mount.h> 70 #include <linux/namei.h> 71 #include <linux/statfs.h> 72 #include <linux/mtd/super.h> 73 #include <linux/ctype.h> 74 #include <linux/highmem.h> 75 #include <linux/pagemap.h> 76 #include <linux/uaccess.h> 77 #include <linux/major.h> 78 #include "internal.h" 79 80 static struct kmem_cache *romfs_inode_cachep; 81 82 static const umode_t romfs_modemap[8] = { 83 0, /* hard link */ 84 S_IFDIR | 0644, /* directory */ 85 S_IFREG | 0644, /* regular file */ 86 S_IFLNK | 0777, /* symlink */ 87 S_IFBLK | 0600, /* blockdev */ 88 S_IFCHR | 0600, /* chardev */ 89 S_IFSOCK | 0644, /* socket */ 90 S_IFIFO | 0644 /* FIFO */ 91 }; 92 93 static const unsigned char romfs_dtype_table[] = { 94 DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO 95 }; 96 97 static struct inode *romfs_iget(struct super_block *sb, unsigned long pos); 98 99 /* 100 * read a page worth of data from the image 101 */ 102 static int romfs_readpage(struct file *file, struct page *page) 103 { 104 struct inode *inode = page->mapping->host; 105 loff_t offset, size; 106 unsigned long fillsize, pos; 107 void *buf; 108 int ret; 109 110 buf = kmap(page); 111 if (!buf) 112 return -ENOMEM; 113 114 /* 32 bit warning -- but not for us :) */ 115 offset = page_offset(page); 116 size = i_size_read(inode); 117 fillsize = 0; 118 ret = 0; 119 if (offset < size) { 120 size -= offset; 121 fillsize = size > PAGE_SIZE ? PAGE_SIZE : size; 122 123 pos = ROMFS_I(inode)->i_dataoffset + offset; 124 125 ret = romfs_dev_read(inode->i_sb, pos, buf, fillsize); 126 if (ret < 0) { 127 SetPageError(page); 128 fillsize = 0; 129 ret = -EIO; 130 } 131 } 132 133 if (fillsize < PAGE_SIZE) 134 memset(buf + fillsize, 0, PAGE_SIZE - fillsize); 135 if (ret == 0) 136 SetPageUptodate(page); 137 138 flush_dcache_page(page); 139 kunmap(page); 140 unlock_page(page); 141 return ret; 142 } 143 144 static const struct address_space_operations romfs_aops = { 145 .readpage = romfs_readpage 146 }; 147 148 /* 149 * read the entries from a directory 150 */ 151 static int romfs_readdir(struct file *file, struct dir_context *ctx) 152 { 153 struct inode *i = file_inode(file); 154 struct romfs_inode ri; 155 unsigned long offset, maxoff; 156 int j, ino, nextfh; 157 char fsname[ROMFS_MAXFN]; /* XXX dynamic? */ 158 int ret; 159 160 maxoff = romfs_maxsize(i->i_sb); 161 162 offset = ctx->pos; 163 if (!offset) { 164 offset = i->i_ino & ROMFH_MASK; 165 ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE); 166 if (ret < 0) 167 goto out; 168 offset = be32_to_cpu(ri.spec) & ROMFH_MASK; 169 } 170 171 /* Not really failsafe, but we are read-only... */ 172 for (;;) { 173 if (!offset || offset >= maxoff) { 174 offset = maxoff; 175 ctx->pos = offset; 176 goto out; 177 } 178 ctx->pos = offset; 179 180 /* Fetch inode info */ 181 ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE); 182 if (ret < 0) 183 goto out; 184 185 j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE, 186 sizeof(fsname) - 1); 187 if (j < 0) 188 goto out; 189 190 ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j); 191 if (ret < 0) 192 goto out; 193 fsname[j] = '\0'; 194 195 ino = offset; 196 nextfh = be32_to_cpu(ri.next); 197 if ((nextfh & ROMFH_TYPE) == ROMFH_HRD) 198 ino = be32_to_cpu(ri.spec); 199 if (!dir_emit(ctx, fsname, j, ino, 200 romfs_dtype_table[nextfh & ROMFH_TYPE])) 201 goto out; 202 203 offset = nextfh & ROMFH_MASK; 204 } 205 out: 206 return 0; 207 } 208 209 /* 210 * look up an entry in a directory 211 */ 212 static struct dentry *romfs_lookup(struct inode *dir, struct dentry *dentry, 213 unsigned int flags) 214 { 215 unsigned long offset, maxoff; 216 struct inode *inode = NULL; 217 struct romfs_inode ri; 218 const char *name; /* got from dentry */ 219 int len, ret; 220 221 offset = dir->i_ino & ROMFH_MASK; 222 ret = romfs_dev_read(dir->i_sb, offset, &ri, ROMFH_SIZE); 223 if (ret < 0) 224 goto error; 225 226 /* search all the file entries in the list starting from the one 227 * pointed to by the directory's special data */ 228 maxoff = romfs_maxsize(dir->i_sb); 229 offset = be32_to_cpu(ri.spec) & ROMFH_MASK; 230 231 name = dentry->d_name.name; 232 len = dentry->d_name.len; 233 234 for (;;) { 235 if (!offset || offset >= maxoff) 236 break; 237 238 ret = romfs_dev_read(dir->i_sb, offset, &ri, sizeof(ri)); 239 if (ret < 0) 240 goto error; 241 242 /* try to match the first 16 bytes of name */ 243 ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name, 244 len); 245 if (ret < 0) 246 goto error; 247 if (ret == 1) { 248 /* Hard link handling */ 249 if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD) 250 offset = be32_to_cpu(ri.spec) & ROMFH_MASK; 251 inode = romfs_iget(dir->i_sb, offset); 252 break; 253 } 254 255 /* next entry */ 256 offset = be32_to_cpu(ri.next) & ROMFH_MASK; 257 } 258 259 return d_splice_alias(inode, dentry); 260 error: 261 return ERR_PTR(ret); 262 } 263 264 static const struct file_operations romfs_dir_operations = { 265 .read = generic_read_dir, 266 .iterate_shared = romfs_readdir, 267 .llseek = generic_file_llseek, 268 }; 269 270 static const struct inode_operations romfs_dir_inode_operations = { 271 .lookup = romfs_lookup, 272 }; 273 274 /* 275 * get a romfs inode based on its position in the image (which doubles as the 276 * inode number) 277 */ 278 static struct inode *romfs_iget(struct super_block *sb, unsigned long pos) 279 { 280 struct romfs_inode_info *inode; 281 struct romfs_inode ri; 282 struct inode *i; 283 unsigned long nlen; 284 unsigned nextfh; 285 int ret; 286 umode_t mode; 287 288 /* we might have to traverse a chain of "hard link" file entries to get 289 * to the actual file */ 290 for (;;) { 291 ret = romfs_dev_read(sb, pos, &ri, sizeof(ri)); 292 if (ret < 0) 293 goto error; 294 295 /* XXX: do romfs_checksum here too (with name) */ 296 297 nextfh = be32_to_cpu(ri.next); 298 if ((nextfh & ROMFH_TYPE) != ROMFH_HRD) 299 break; 300 301 pos = be32_to_cpu(ri.spec) & ROMFH_MASK; 302 } 303 304 /* determine the length of the filename */ 305 nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN); 306 if (IS_ERR_VALUE(nlen)) 307 goto eio; 308 309 /* get an inode for this image position */ 310 i = iget_locked(sb, pos); 311 if (!i) 312 return ERR_PTR(-ENOMEM); 313 314 if (!(i->i_state & I_NEW)) 315 return i; 316 317 /* precalculate the data offset */ 318 inode = ROMFS_I(i); 319 inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK; 320 inode->i_dataoffset = pos + inode->i_metasize; 321 322 set_nlink(i, 1); /* Hard to decide.. */ 323 i->i_size = be32_to_cpu(ri.size); 324 i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0; 325 i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0; 326 327 /* set up mode and ops */ 328 mode = romfs_modemap[nextfh & ROMFH_TYPE]; 329 330 switch (nextfh & ROMFH_TYPE) { 331 case ROMFH_DIR: 332 i->i_size = ROMFS_I(i)->i_metasize; 333 i->i_op = &romfs_dir_inode_operations; 334 i->i_fop = &romfs_dir_operations; 335 if (nextfh & ROMFH_EXEC) 336 mode |= S_IXUGO; 337 break; 338 case ROMFH_REG: 339 i->i_fop = &romfs_ro_fops; 340 i->i_data.a_ops = &romfs_aops; 341 if (nextfh & ROMFH_EXEC) 342 mode |= S_IXUGO; 343 break; 344 case ROMFH_SYM: 345 i->i_op = &page_symlink_inode_operations; 346 inode_nohighmem(i); 347 i->i_data.a_ops = &romfs_aops; 348 mode |= S_IRWXUGO; 349 break; 350 default: 351 /* depending on MBZ for sock/fifos */ 352 nextfh = be32_to_cpu(ri.spec); 353 init_special_inode(i, mode, MKDEV(nextfh >> 16, 354 nextfh & 0xffff)); 355 break; 356 } 357 358 i->i_mode = mode; 359 360 unlock_new_inode(i); 361 return i; 362 363 eio: 364 ret = -EIO; 365 error: 366 pr_err("read error for inode 0x%lx\n", pos); 367 return ERR_PTR(ret); 368 } 369 370 /* 371 * allocate a new inode 372 */ 373 static struct inode *romfs_alloc_inode(struct super_block *sb) 374 { 375 struct romfs_inode_info *inode; 376 377 inode = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL); 378 return inode ? &inode->vfs_inode : NULL; 379 } 380 381 /* 382 * return a spent inode to the slab cache 383 */ 384 static void romfs_free_inode(struct inode *inode) 385 { 386 kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode)); 387 } 388 389 /* 390 * get filesystem statistics 391 */ 392 static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf) 393 { 394 struct super_block *sb = dentry->d_sb; 395 u64 id = 0; 396 397 /* When calling huge_encode_dev(), 398 * use sb->s_bdev->bd_dev when, 399 * - CONFIG_ROMFS_ON_BLOCK defined 400 * use sb->s_dev when, 401 * - CONFIG_ROMFS_ON_BLOCK undefined and 402 * - CONFIG_ROMFS_ON_MTD defined 403 * leave id as 0 when, 404 * - CONFIG_ROMFS_ON_BLOCK undefined and 405 * - CONFIG_ROMFS_ON_MTD undefined 406 */ 407 if (sb->s_bdev) 408 id = huge_encode_dev(sb->s_bdev->bd_dev); 409 else if (sb->s_dev) 410 id = huge_encode_dev(sb->s_dev); 411 412 buf->f_type = ROMFS_MAGIC; 413 buf->f_namelen = ROMFS_MAXFN; 414 buf->f_bsize = ROMBSIZE; 415 buf->f_bfree = buf->f_bavail = buf->f_ffree; 416 buf->f_blocks = 417 (romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS; 418 buf->f_fsid.val[0] = (u32)id; 419 buf->f_fsid.val[1] = (u32)(id >> 32); 420 return 0; 421 } 422 423 /* 424 * remounting must involve read-only 425 */ 426 static int romfs_remount(struct super_block *sb, int *flags, char *data) 427 { 428 sync_filesystem(sb); 429 *flags |= SB_RDONLY; 430 return 0; 431 } 432 433 static const struct super_operations romfs_super_ops = { 434 .alloc_inode = romfs_alloc_inode, 435 .free_inode = romfs_free_inode, 436 .statfs = romfs_statfs, 437 .remount_fs = romfs_remount, 438 }; 439 440 /* 441 * checksum check on part of a romfs filesystem 442 */ 443 static __u32 romfs_checksum(const void *data, int size) 444 { 445 const __be32 *ptr = data; 446 __u32 sum; 447 448 sum = 0; 449 size >>= 2; 450 while (size > 0) { 451 sum += be32_to_cpu(*ptr++); 452 size--; 453 } 454 return sum; 455 } 456 457 /* 458 * fill in the superblock 459 */ 460 static int romfs_fill_super(struct super_block *sb, void *data, int silent) 461 { 462 struct romfs_super_block *rsb; 463 struct inode *root; 464 unsigned long pos, img_size; 465 const char *storage; 466 size_t len; 467 int ret; 468 469 #ifdef CONFIG_BLOCK 470 if (!sb->s_mtd) { 471 sb_set_blocksize(sb, ROMBSIZE); 472 } else { 473 sb->s_blocksize = ROMBSIZE; 474 sb->s_blocksize_bits = blksize_bits(ROMBSIZE); 475 } 476 #endif 477 478 sb->s_maxbytes = 0xFFFFFFFF; 479 sb->s_magic = ROMFS_MAGIC; 480 sb->s_flags |= SB_RDONLY | SB_NOATIME; 481 sb->s_op = &romfs_super_ops; 482 483 #ifdef CONFIG_ROMFS_ON_MTD 484 /* Use same dev ID from the underlying mtdblock device */ 485 if (sb->s_mtd) 486 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index); 487 #endif 488 /* read the image superblock and check it */ 489 rsb = kmalloc(512, GFP_KERNEL); 490 if (!rsb) 491 return -ENOMEM; 492 493 sb->s_fs_info = (void *) 512; 494 ret = romfs_dev_read(sb, 0, rsb, 512); 495 if (ret < 0) 496 goto error_rsb; 497 498 img_size = be32_to_cpu(rsb->size); 499 500 if (sb->s_mtd && img_size > sb->s_mtd->size) 501 goto error_rsb_inval; 502 503 sb->s_fs_info = (void *) img_size; 504 505 if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1 || 506 img_size < ROMFH_SIZE) { 507 if (!silent) 508 pr_warn("VFS: Can't find a romfs filesystem on dev %s.\n", 509 sb->s_id); 510 goto error_rsb_inval; 511 } 512 513 if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) { 514 pr_err("bad initial checksum on dev %s.\n", sb->s_id); 515 goto error_rsb_inval; 516 } 517 518 storage = sb->s_mtd ? "MTD" : "the block layer"; 519 520 len = strnlen(rsb->name, ROMFS_MAXFN); 521 if (!silent) 522 pr_notice("Mounting image '%*.*s' through %s\n", 523 (unsigned) len, (unsigned) len, rsb->name, storage); 524 525 kfree(rsb); 526 rsb = NULL; 527 528 /* find the root directory */ 529 pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK; 530 531 root = romfs_iget(sb, pos); 532 if (IS_ERR(root)) 533 return PTR_ERR(root); 534 535 sb->s_root = d_make_root(root); 536 if (!sb->s_root) 537 return -ENOMEM; 538 539 return 0; 540 541 error_rsb_inval: 542 ret = -EINVAL; 543 error_rsb: 544 kfree(rsb); 545 return ret; 546 } 547 548 /* 549 * get a superblock for mounting 550 */ 551 static struct dentry *romfs_mount(struct file_system_type *fs_type, 552 int flags, const char *dev_name, 553 void *data) 554 { 555 struct dentry *ret = ERR_PTR(-EINVAL); 556 557 #ifdef CONFIG_ROMFS_ON_MTD 558 ret = mount_mtd(fs_type, flags, dev_name, data, romfs_fill_super); 559 #endif 560 #ifdef CONFIG_ROMFS_ON_BLOCK 561 if (ret == ERR_PTR(-EINVAL)) 562 ret = mount_bdev(fs_type, flags, dev_name, data, 563 romfs_fill_super); 564 #endif 565 return ret; 566 } 567 568 /* 569 * destroy a romfs superblock in the appropriate manner 570 */ 571 static void romfs_kill_sb(struct super_block *sb) 572 { 573 #ifdef CONFIG_ROMFS_ON_MTD 574 if (sb->s_mtd) { 575 kill_mtd_super(sb); 576 return; 577 } 578 #endif 579 #ifdef CONFIG_ROMFS_ON_BLOCK 580 if (sb->s_bdev) { 581 kill_block_super(sb); 582 return; 583 } 584 #endif 585 } 586 587 static struct file_system_type romfs_fs_type = { 588 .owner = THIS_MODULE, 589 .name = "romfs", 590 .mount = romfs_mount, 591 .kill_sb = romfs_kill_sb, 592 .fs_flags = FS_REQUIRES_DEV, 593 }; 594 MODULE_ALIAS_FS("romfs"); 595 596 /* 597 * inode storage initialiser 598 */ 599 static void romfs_i_init_once(void *_inode) 600 { 601 struct romfs_inode_info *inode = _inode; 602 603 inode_init_once(&inode->vfs_inode); 604 } 605 606 /* 607 * romfs module initialisation 608 */ 609 static int __init init_romfs_fs(void) 610 { 611 int ret; 612 613 pr_info("ROMFS MTD (C) 2007 Red Hat, Inc.\n"); 614 615 romfs_inode_cachep = 616 kmem_cache_create("romfs_i", 617 sizeof(struct romfs_inode_info), 0, 618 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD | 619 SLAB_ACCOUNT, romfs_i_init_once); 620 621 if (!romfs_inode_cachep) { 622 pr_err("Failed to initialise inode cache\n"); 623 return -ENOMEM; 624 } 625 ret = register_filesystem(&romfs_fs_type); 626 if (ret) { 627 pr_err("Failed to register filesystem\n"); 628 goto error_register; 629 } 630 return 0; 631 632 error_register: 633 kmem_cache_destroy(romfs_inode_cachep); 634 return ret; 635 } 636 637 /* 638 * romfs module removal 639 */ 640 static void __exit exit_romfs_fs(void) 641 { 642 unregister_filesystem(&romfs_fs_type); 643 /* 644 * Make sure all delayed rcu free inodes are flushed before we 645 * destroy cache. 646 */ 647 rcu_barrier(); 648 kmem_cache_destroy(romfs_inode_cachep); 649 } 650 651 module_init(init_romfs_fs); 652 module_exit(exit_romfs_fs); 653 654 MODULE_DESCRIPTION("Direct-MTD Capable RomFS"); 655 MODULE_AUTHOR("Red Hat, Inc."); 656 MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */ 657