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_strcmp(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 const 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; 302 int ret; 303 umode_t mode; 304 305 /* we might have to traverse a chain of "hard link" file entries to get 306 * to the actual file */ 307 for (;;) { 308 ret = romfs_dev_read(sb, pos, &ri, sizeof(ri)); 309 if (ret < 0) 310 goto error; 311 312 /* XXX: do romfs_checksum here too (with name) */ 313 314 nextfh = be32_to_cpu(ri.next); 315 if ((nextfh & ROMFH_TYPE) != ROMFH_HRD) 316 break; 317 318 pos = be32_to_cpu(ri.spec) & ROMFH_MASK; 319 } 320 321 /* determine the length of the filename */ 322 nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN); 323 if (IS_ERR_VALUE(nlen)) 324 goto eio; 325 326 /* get an inode for this image position */ 327 i = iget_locked(sb, pos); 328 if (!i) 329 return ERR_PTR(-ENOMEM); 330 331 if (!(i->i_state & I_NEW)) 332 return i; 333 334 /* precalculate the data offset */ 335 inode = ROMFS_I(i); 336 inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK; 337 inode->i_dataoffset = pos + inode->i_metasize; 338 339 i->i_nlink = 1; /* Hard to decide.. */ 340 i->i_size = be32_to_cpu(ri.size); 341 i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0; 342 i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0; 343 344 /* set up mode and ops */ 345 mode = romfs_modemap[nextfh & ROMFH_TYPE]; 346 347 switch (nextfh & ROMFH_TYPE) { 348 case ROMFH_DIR: 349 i->i_size = ROMFS_I(i)->i_metasize; 350 i->i_op = &romfs_dir_inode_operations; 351 i->i_fop = &romfs_dir_operations; 352 if (nextfh & ROMFH_EXEC) 353 mode |= S_IXUGO; 354 break; 355 case ROMFH_REG: 356 i->i_fop = &romfs_ro_fops; 357 i->i_data.a_ops = &romfs_aops; 358 if (i->i_sb->s_mtd) 359 i->i_data.backing_dev_info = 360 i->i_sb->s_mtd->backing_dev_info; 361 if (nextfh & ROMFH_EXEC) 362 mode |= S_IXUGO; 363 break; 364 case ROMFH_SYM: 365 i->i_op = &page_symlink_inode_operations; 366 i->i_data.a_ops = &romfs_aops; 367 mode |= S_IRWXUGO; 368 break; 369 default: 370 /* depending on MBZ for sock/fifos */ 371 nextfh = be32_to_cpu(ri.spec); 372 init_special_inode(i, mode, MKDEV(nextfh >> 16, 373 nextfh & 0xffff)); 374 break; 375 } 376 377 i->i_mode = mode; 378 379 unlock_new_inode(i); 380 return i; 381 382 eio: 383 ret = -EIO; 384 error: 385 printk(KERN_ERR "ROMFS: read error for inode 0x%lx\n", pos); 386 return ERR_PTR(ret); 387 } 388 389 /* 390 * allocate a new inode 391 */ 392 static struct inode *romfs_alloc_inode(struct super_block *sb) 393 { 394 struct romfs_inode_info *inode; 395 inode = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL); 396 return inode ? &inode->vfs_inode : NULL; 397 } 398 399 /* 400 * return a spent inode to the slab cache 401 */ 402 static void romfs_destroy_inode(struct inode *inode) 403 { 404 kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode)); 405 } 406 407 /* 408 * get filesystem statistics 409 */ 410 static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf) 411 { 412 struct super_block *sb = dentry->d_sb; 413 u64 id = huge_encode_dev(sb->s_bdev->bd_dev); 414 415 buf->f_type = ROMFS_MAGIC; 416 buf->f_namelen = ROMFS_MAXFN; 417 buf->f_bsize = ROMBSIZE; 418 buf->f_bfree = buf->f_bavail = buf->f_ffree; 419 buf->f_blocks = 420 (romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS; 421 buf->f_fsid.val[0] = (u32)id; 422 buf->f_fsid.val[1] = (u32)(id >> 32); 423 return 0; 424 } 425 426 /* 427 * remounting must involve read-only 428 */ 429 static int romfs_remount(struct super_block *sb, int *flags, char *data) 430 { 431 *flags |= MS_RDONLY; 432 return 0; 433 } 434 435 static const struct super_operations romfs_super_ops = { 436 .alloc_inode = romfs_alloc_inode, 437 .destroy_inode = romfs_destroy_inode, 438 .statfs = romfs_statfs, 439 .remount_fs = romfs_remount, 440 }; 441 442 /* 443 * checksum check on part of a romfs filesystem 444 */ 445 static __u32 romfs_checksum(const void *data, int size) 446 { 447 const __be32 *ptr = data; 448 __u32 sum; 449 450 sum = 0; 451 size >>= 2; 452 while (size > 0) { 453 sum += be32_to_cpu(*ptr++); 454 size--; 455 } 456 return sum; 457 } 458 459 /* 460 * fill in the superblock 461 */ 462 static int romfs_fill_super(struct super_block *sb, void *data, int silent) 463 { 464 struct romfs_super_block *rsb; 465 struct inode *root; 466 unsigned long pos, img_size; 467 const char *storage; 468 size_t len; 469 int ret; 470 471 #ifdef CONFIG_BLOCK 472 if (!sb->s_mtd) { 473 sb_set_blocksize(sb, ROMBSIZE); 474 } else { 475 sb->s_blocksize = ROMBSIZE; 476 sb->s_blocksize_bits = blksize_bits(ROMBSIZE); 477 } 478 #endif 479 480 sb->s_maxbytes = 0xFFFFFFFF; 481 sb->s_magic = ROMFS_MAGIC; 482 sb->s_flags |= MS_RDONLY | MS_NOATIME; 483 sb->s_op = &romfs_super_ops; 484 485 /* read the image superblock and check it */ 486 rsb = kmalloc(512, GFP_KERNEL); 487 if (!rsb) 488 return -ENOMEM; 489 490 sb->s_fs_info = (void *) 512; 491 ret = romfs_dev_read(sb, 0, rsb, 512); 492 if (ret < 0) 493 goto error_rsb; 494 495 img_size = be32_to_cpu(rsb->size); 496 497 if (sb->s_mtd && img_size > sb->s_mtd->size) 498 goto error_rsb_inval; 499 500 sb->s_fs_info = (void *) img_size; 501 502 if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1 || 503 img_size < ROMFH_SIZE) { 504 if (!silent) 505 printk(KERN_WARNING "VFS:" 506 " Can't find a romfs filesystem on dev %s.\n", 507 sb->s_id); 508 goto error_rsb_inval; 509 } 510 511 if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) { 512 printk(KERN_ERR "ROMFS: bad initial checksum on dev %s.\n", 513 sb->s_id); 514 goto error_rsb_inval; 515 } 516 517 storage = sb->s_mtd ? "MTD" : "the block layer"; 518 519 len = strnlen(rsb->name, ROMFS_MAXFN); 520 if (!silent) 521 printk(KERN_NOTICE "ROMFS: Mounting image '%*.*s' through %s\n", 522 (unsigned) len, (unsigned) len, rsb->name, storage); 523 524 kfree(rsb); 525 rsb = NULL; 526 527 /* find the root directory */ 528 pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK; 529 530 root = romfs_iget(sb, pos); 531 if (IS_ERR(root)) 532 goto error; 533 534 sb->s_root = d_alloc_root(root); 535 if (!sb->s_root) 536 goto error_i; 537 538 return 0; 539 540 error_i: 541 iput(root); 542 error: 543 return -EINVAL; 544 error_rsb_inval: 545 ret = -EINVAL; 546 error_rsb: 547 kfree(rsb); 548 return ret; 549 } 550 551 /* 552 * get a superblock for mounting 553 */ 554 static int romfs_get_sb(struct file_system_type *fs_type, 555 int flags, const char *dev_name, 556 void *data, struct vfsmount *mnt) 557 { 558 int ret = -EINVAL; 559 560 #ifdef CONFIG_ROMFS_ON_MTD 561 ret = get_sb_mtd(fs_type, flags, dev_name, data, romfs_fill_super, 562 mnt); 563 #endif 564 #ifdef CONFIG_ROMFS_ON_BLOCK 565 if (ret == -EINVAL) 566 ret = get_sb_bdev(fs_type, flags, dev_name, data, 567 romfs_fill_super, mnt); 568 #endif 569 return ret; 570 } 571 572 /* 573 * destroy a romfs superblock in the appropriate manner 574 */ 575 static void romfs_kill_sb(struct super_block *sb) 576 { 577 #ifdef CONFIG_ROMFS_ON_MTD 578 if (sb->s_mtd) { 579 kill_mtd_super(sb); 580 return; 581 } 582 #endif 583 #ifdef CONFIG_ROMFS_ON_BLOCK 584 if (sb->s_bdev) { 585 kill_block_super(sb); 586 return; 587 } 588 #endif 589 } 590 591 static struct file_system_type romfs_fs_type = { 592 .owner = THIS_MODULE, 593 .name = "romfs", 594 .get_sb = romfs_get_sb, 595 .kill_sb = romfs_kill_sb, 596 .fs_flags = FS_REQUIRES_DEV, 597 }; 598 599 /* 600 * inode storage initialiser 601 */ 602 static void romfs_i_init_once(void *_inode) 603 { 604 struct romfs_inode_info *inode = _inode; 605 606 inode_init_once(&inode->vfs_inode); 607 } 608 609 /* 610 * romfs module initialisation 611 */ 612 static int __init init_romfs_fs(void) 613 { 614 int ret; 615 616 printk(KERN_INFO "ROMFS MTD (C) 2007 Red Hat, Inc.\n"); 617 618 romfs_inode_cachep = 619 kmem_cache_create("romfs_i", 620 sizeof(struct romfs_inode_info), 0, 621 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD, 622 romfs_i_init_once); 623 624 if (!romfs_inode_cachep) { 625 printk(KERN_ERR 626 "ROMFS error: Failed to initialise inode cache\n"); 627 return -ENOMEM; 628 } 629 ret = register_filesystem(&romfs_fs_type); 630 if (ret) { 631 printk(KERN_ERR "ROMFS error: Failed to register filesystem\n"); 632 goto error_register; 633 } 634 return 0; 635 636 error_register: 637 kmem_cache_destroy(romfs_inode_cachep); 638 return ret; 639 } 640 641 /* 642 * romfs module removal 643 */ 644 static void __exit exit_romfs_fs(void) 645 { 646 unregister_filesystem(&romfs_fs_type); 647 kmem_cache_destroy(romfs_inode_cachep); 648 } 649 650 module_init(init_romfs_fs); 651 module_exit(exit_romfs_fs); 652 653 MODULE_DESCRIPTION("Direct-MTD Capable RomFS"); 654 MODULE_AUTHOR("Red Hat, Inc."); 655 MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */ 656