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 #include <linux/module.h> 60 #include <linux/string.h> 61 #include <linux/fs.h> 62 #include <linux/time.h> 63 #include <linux/slab.h> 64 #include <linux/init.h> 65 #include <linux/blkdev.h> 66 #include <linux/parser.h> 67 #include <linux/mount.h> 68 #include <linux/namei.h> 69 #include <linux/statfs.h> 70 #include <linux/mtd/super.h> 71 #include <linux/ctype.h> 72 #include <linux/highmem.h> 73 #include <linux/pagemap.h> 74 #include <linux/uaccess.h> 75 #include "internal.h" 76 77 static struct kmem_cache *romfs_inode_cachep; 78 79 static const umode_t romfs_modemap[8] = { 80 0, /* hard link */ 81 S_IFDIR | 0644, /* directory */ 82 S_IFREG | 0644, /* regular file */ 83 S_IFLNK | 0777, /* symlink */ 84 S_IFBLK | 0600, /* blockdev */ 85 S_IFCHR | 0600, /* chardev */ 86 S_IFSOCK | 0644, /* socket */ 87 S_IFIFO | 0644 /* FIFO */ 88 }; 89 90 static const unsigned char romfs_dtype_table[] = { 91 DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO 92 }; 93 94 static struct inode *romfs_iget(struct super_block *sb, unsigned long pos); 95 96 /* 97 * read a page worth of data from the image 98 */ 99 static int romfs_readpage(struct file *file, struct page *page) 100 { 101 struct inode *inode = page->mapping->host; 102 loff_t offset, size; 103 unsigned long fillsize, pos; 104 void *buf; 105 int ret; 106 107 buf = kmap(page); 108 if (!buf) 109 return -ENOMEM; 110 111 /* 32 bit warning -- but not for us :) */ 112 offset = page_offset(page); 113 size = i_size_read(inode); 114 fillsize = 0; 115 ret = 0; 116 if (offset < size) { 117 size -= offset; 118 fillsize = size > PAGE_SIZE ? PAGE_SIZE : size; 119 120 pos = ROMFS_I(inode)->i_dataoffset + offset; 121 122 ret = romfs_dev_read(inode->i_sb, pos, buf, fillsize); 123 if (ret < 0) { 124 SetPageError(page); 125 fillsize = 0; 126 ret = -EIO; 127 } 128 } 129 130 if (fillsize < PAGE_SIZE) 131 memset(buf + fillsize, 0, PAGE_SIZE - fillsize); 132 if (ret == 0) 133 SetPageUptodate(page); 134 135 flush_dcache_page(page); 136 kunmap(page); 137 unlock_page(page); 138 return ret; 139 } 140 141 static const struct address_space_operations romfs_aops = { 142 .readpage = romfs_readpage 143 }; 144 145 /* 146 * read the entries from a directory 147 */ 148 static int romfs_readdir(struct file *filp, void *dirent, filldir_t filldir) 149 { 150 struct inode *i = filp->f_dentry->d_inode; 151 struct romfs_inode ri; 152 unsigned long offset, maxoff; 153 int j, ino, nextfh; 154 int stored = 0; 155 char fsname[ROMFS_MAXFN]; /* XXX dynamic? */ 156 int ret; 157 158 maxoff = romfs_maxsize(i->i_sb); 159 160 offset = filp->f_pos; 161 if (!offset) { 162 offset = i->i_ino & ROMFH_MASK; 163 ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE); 164 if (ret < 0) 165 goto out; 166 offset = be32_to_cpu(ri.spec) & ROMFH_MASK; 167 } 168 169 /* Not really failsafe, but we are read-only... */ 170 for (;;) { 171 if (!offset || offset >= maxoff) { 172 offset = maxoff; 173 filp->f_pos = offset; 174 goto out; 175 } 176 filp->f_pos = offset; 177 178 /* Fetch inode info */ 179 ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE); 180 if (ret < 0) 181 goto out; 182 183 j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE, 184 sizeof(fsname) - 1); 185 if (j < 0) 186 goto out; 187 188 ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j); 189 if (ret < 0) 190 goto out; 191 fsname[j] = '\0'; 192 193 ino = offset; 194 nextfh = be32_to_cpu(ri.next); 195 if ((nextfh & ROMFH_TYPE) == ROMFH_HRD) 196 ino = be32_to_cpu(ri.spec); 197 if (filldir(dirent, fsname, j, offset, ino, 198 romfs_dtype_table[nextfh & ROMFH_TYPE]) < 0) 199 goto out; 200 201 stored++; 202 offset = nextfh & ROMFH_MASK; 203 } 204 205 out: 206 return stored; 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 struct nameidata *nd) 214 { 215 unsigned long offset, maxoff; 216 struct inode *inode; 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 goto out0; 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_strncmp(dir->i_sb, offset + ROMFH_SIZE, name, 244 len); 245 if (ret < 0) 246 goto error; 247 if (ret == 1) 248 break; 249 250 /* next entry */ 251 offset = be32_to_cpu(ri.next) & ROMFH_MASK; 252 } 253 254 /* Hard link handling */ 255 if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD) 256 offset = be32_to_cpu(ri.spec) & ROMFH_MASK; 257 258 inode = romfs_iget(dir->i_sb, offset); 259 if (IS_ERR(inode)) { 260 ret = PTR_ERR(inode); 261 goto error; 262 } 263 goto outi; 264 265 /* 266 * it's a bit funky, _lookup needs to return an error code 267 * (negative) or a NULL, both as a dentry. ENOENT should not 268 * be returned, instead we need to create a negative dentry by 269 * d_add(dentry, NULL); and return 0 as no error. 270 * (Although as I see, it only matters on writable file 271 * systems). 272 */ 273 out0: 274 inode = NULL; 275 outi: 276 d_add(dentry, inode); 277 ret = 0; 278 error: 279 return ERR_PTR(ret); 280 } 281 282 static const struct file_operations romfs_dir_operations = { 283 .read = generic_read_dir, 284 .readdir = romfs_readdir, 285 }; 286 287 static struct inode_operations romfs_dir_inode_operations = { 288 .lookup = romfs_lookup, 289 }; 290 291 /* 292 * get a romfs inode based on its position in the image (which doubles as the 293 * inode number) 294 */ 295 static struct inode *romfs_iget(struct super_block *sb, unsigned long pos) 296 { 297 struct romfs_inode_info *inode; 298 struct romfs_inode ri; 299 struct inode *i; 300 unsigned long nlen; 301 unsigned nextfh, ret; 302 umode_t mode; 303 304 /* we might have to traverse a chain of "hard link" file entries to get 305 * to the actual file */ 306 for (;;) { 307 ret = romfs_dev_read(sb, pos, &ri, sizeof(ri)); 308 if (ret < 0) 309 goto error; 310 311 /* XXX: do romfs_checksum here too (with name) */ 312 313 nextfh = be32_to_cpu(ri.next); 314 if ((nextfh & ROMFH_TYPE) != ROMFH_HRD) 315 break; 316 317 pos = be32_to_cpu(ri.spec) & ROMFH_MASK; 318 } 319 320 /* determine the length of the filename */ 321 nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN); 322 if (IS_ERR_VALUE(nlen)) 323 goto eio; 324 325 /* get an inode for this image position */ 326 i = iget_locked(sb, pos); 327 if (!i) 328 return ERR_PTR(-ENOMEM); 329 330 if (!(i->i_state & I_NEW)) 331 return i; 332 333 /* precalculate the data offset */ 334 inode = ROMFS_I(i); 335 inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK; 336 inode->i_dataoffset = pos + inode->i_metasize; 337 338 i->i_nlink = 1; /* Hard to decide.. */ 339 i->i_size = be32_to_cpu(ri.size); 340 i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0; 341 i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0; 342 343 /* set up mode and ops */ 344 mode = romfs_modemap[nextfh & ROMFH_TYPE]; 345 346 switch (nextfh & ROMFH_TYPE) { 347 case ROMFH_DIR: 348 i->i_size = ROMFS_I(i)->i_metasize; 349 i->i_op = &romfs_dir_inode_operations; 350 i->i_fop = &romfs_dir_operations; 351 if (nextfh & ROMFH_EXEC) 352 mode |= S_IXUGO; 353 break; 354 case ROMFH_REG: 355 i->i_fop = &romfs_ro_fops; 356 i->i_data.a_ops = &romfs_aops; 357 if (i->i_sb->s_mtd) 358 i->i_data.backing_dev_info = 359 i->i_sb->s_mtd->backing_dev_info; 360 if (nextfh & ROMFH_EXEC) 361 mode |= S_IXUGO; 362 break; 363 case ROMFH_SYM: 364 i->i_op = &page_symlink_inode_operations; 365 i->i_data.a_ops = &romfs_aops; 366 mode |= S_IRWXUGO; 367 break; 368 default: 369 /* depending on MBZ for sock/fifos */ 370 nextfh = be32_to_cpu(ri.spec); 371 init_special_inode(i, mode, MKDEV(nextfh >> 16, 372 nextfh & 0xffff)); 373 break; 374 } 375 376 i->i_mode = mode; 377 378 unlock_new_inode(i); 379 return i; 380 381 eio: 382 ret = -EIO; 383 error: 384 printk(KERN_ERR "ROMFS: read error for inode 0x%lx\n", pos); 385 return ERR_PTR(ret); 386 } 387 388 /* 389 * allocate a new inode 390 */ 391 static struct inode *romfs_alloc_inode(struct super_block *sb) 392 { 393 struct romfs_inode_info *inode; 394 inode = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL); 395 return inode ? &inode->vfs_inode : NULL; 396 } 397 398 /* 399 * return a spent inode to the slab cache 400 */ 401 static void romfs_destroy_inode(struct inode *inode) 402 { 403 kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode)); 404 } 405 406 /* 407 * get filesystem statistics 408 */ 409 static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf) 410 { 411 struct super_block *sb = dentry->d_sb; 412 u64 id = huge_encode_dev(sb->s_bdev->bd_dev); 413 414 buf->f_type = ROMFS_MAGIC; 415 buf->f_namelen = ROMFS_MAXFN; 416 buf->f_bsize = ROMBSIZE; 417 buf->f_bfree = buf->f_bavail = buf->f_ffree; 418 buf->f_blocks = 419 (romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS; 420 buf->f_fsid.val[0] = (u32)id; 421 buf->f_fsid.val[1] = (u32)(id >> 32); 422 return 0; 423 } 424 425 /* 426 * remounting must involve read-only 427 */ 428 static int romfs_remount(struct super_block *sb, int *flags, char *data) 429 { 430 *flags |= MS_RDONLY; 431 return 0; 432 } 433 434 static const struct super_operations romfs_super_ops = { 435 .alloc_inode = romfs_alloc_inode, 436 .destroy_inode = romfs_destroy_inode, 437 .statfs = romfs_statfs, 438 .remount_fs = romfs_remount, 439 }; 440 441 /* 442 * checksum check on part of a romfs filesystem 443 */ 444 static __u32 romfs_checksum(const void *data, int size) 445 { 446 const __be32 *ptr = data; 447 __u32 sum; 448 449 sum = 0; 450 size >>= 2; 451 while (size > 0) { 452 sum += be32_to_cpu(*ptr++); 453 size--; 454 } 455 return sum; 456 } 457 458 /* 459 * fill in the superblock 460 */ 461 static int romfs_fill_super(struct super_block *sb, void *data, int silent) 462 { 463 struct romfs_super_block *rsb; 464 struct inode *root; 465 unsigned long pos, img_size; 466 const char *storage; 467 size_t len; 468 int ret; 469 470 #ifdef CONFIG_BLOCK 471 if (!sb->s_mtd) { 472 sb_set_blocksize(sb, ROMBSIZE); 473 } else { 474 sb->s_blocksize = ROMBSIZE; 475 sb->s_blocksize_bits = blksize_bits(ROMBSIZE); 476 } 477 #endif 478 479 sb->s_maxbytes = 0xFFFFFFFF; 480 sb->s_magic = ROMFS_MAGIC; 481 sb->s_flags |= MS_RDONLY | MS_NOATIME; 482 sb->s_op = &romfs_super_ops; 483 484 /* read the image superblock and check it */ 485 rsb = kmalloc(512, GFP_KERNEL); 486 if (!rsb) 487 return -ENOMEM; 488 489 sb->s_fs_info = (void *) 512; 490 ret = romfs_dev_read(sb, 0, rsb, 512); 491 if (ret < 0) 492 goto error_rsb; 493 494 img_size = be32_to_cpu(rsb->size); 495 496 if (sb->s_mtd && img_size > sb->s_mtd->size) 497 goto error_rsb_inval; 498 499 sb->s_fs_info = (void *) img_size; 500 501 if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1 || 502 img_size < ROMFH_SIZE) { 503 if (!silent) 504 printk(KERN_WARNING "VFS:" 505 " Can't find a romfs filesystem on dev %s.\n", 506 sb->s_id); 507 goto error_rsb_inval; 508 } 509 510 if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) { 511 printk(KERN_ERR "ROMFS: bad initial checksum on dev %s.\n", 512 sb->s_id); 513 goto error_rsb_inval; 514 } 515 516 storage = sb->s_mtd ? "MTD" : "the block layer"; 517 518 len = strnlen(rsb->name, ROMFS_MAXFN); 519 if (!silent) 520 printk(KERN_NOTICE "ROMFS: Mounting image '%*.*s' through %s\n", 521 (unsigned) len, (unsigned) len, rsb->name, storage); 522 523 kfree(rsb); 524 rsb = NULL; 525 526 /* find the root directory */ 527 pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK; 528 529 root = romfs_iget(sb, pos); 530 if (!root) 531 goto error; 532 533 sb->s_root = d_alloc_root(root); 534 if (!sb->s_root) 535 goto error_i; 536 537 return 0; 538 539 error_i: 540 iput(root); 541 error: 542 return -EINVAL; 543 error_rsb_inval: 544 ret = -EINVAL; 545 error_rsb: 546 return ret; 547 } 548 549 /* 550 * get a superblock for mounting 551 */ 552 static int romfs_get_sb(struct file_system_type *fs_type, 553 int flags, const char *dev_name, 554 void *data, struct vfsmount *mnt) 555 { 556 int ret = -EINVAL; 557 558 #ifdef CONFIG_ROMFS_ON_MTD 559 ret = get_sb_mtd(fs_type, flags, dev_name, data, romfs_fill_super, 560 mnt); 561 #endif 562 #ifdef CONFIG_ROMFS_ON_BLOCK 563 if (ret == -EINVAL) 564 ret = get_sb_bdev(fs_type, flags, dev_name, data, 565 romfs_fill_super, mnt); 566 #endif 567 return ret; 568 } 569 570 /* 571 * destroy a romfs superblock in the appropriate manner 572 */ 573 static void romfs_kill_sb(struct super_block *sb) 574 { 575 #ifdef CONFIG_ROMFS_ON_MTD 576 if (sb->s_mtd) { 577 kill_mtd_super(sb); 578 return; 579 } 580 #endif 581 #ifdef CONFIG_ROMFS_ON_BLOCK 582 if (sb->s_bdev) { 583 kill_block_super(sb); 584 return; 585 } 586 #endif 587 } 588 589 static struct file_system_type romfs_fs_type = { 590 .owner = THIS_MODULE, 591 .name = "romfs", 592 .get_sb = romfs_get_sb, 593 .kill_sb = romfs_kill_sb, 594 .fs_flags = FS_REQUIRES_DEV, 595 }; 596 597 /* 598 * inode storage initialiser 599 */ 600 static void romfs_i_init_once(void *_inode) 601 { 602 struct romfs_inode_info *inode = _inode; 603 604 inode_init_once(&inode->vfs_inode); 605 } 606 607 /* 608 * romfs module initialisation 609 */ 610 static int __init init_romfs_fs(void) 611 { 612 int ret; 613 614 printk(KERN_INFO "ROMFS MTD (C) 2007 Red Hat, Inc.\n"); 615 616 romfs_inode_cachep = 617 kmem_cache_create("romfs_i", 618 sizeof(struct romfs_inode_info), 0, 619 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, 620 romfs_i_init_once); 621 622 if (!romfs_inode_cachep) { 623 printk(KERN_ERR 624 "ROMFS error: Failed to initialise inode cache\n"); 625 return -ENOMEM; 626 } 627 ret = register_filesystem(&romfs_fs_type); 628 if (ret) { 629 printk(KERN_ERR "ROMFS error: Failed to register filesystem\n"); 630 goto error_register; 631 } 632 return 0; 633 634 error_register: 635 kmem_cache_destroy(romfs_inode_cachep); 636 return ret; 637 } 638 639 /* 640 * romfs module removal 641 */ 642 static void __exit exit_romfs_fs(void) 643 { 644 unregister_filesystem(&romfs_fs_type); 645 kmem_cache_destroy(romfs_inode_cachep); 646 } 647 648 module_init(init_romfs_fs); 649 module_exit(exit_romfs_fs); 650 651 MODULE_DESCRIPTION("Direct-MTD Capable RomFS"); 652 MODULE_AUTHOR("Red Hat, Inc."); 653 MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */ 654