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1/* Block- or MTD-based romfs2 *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 implementation7 *8 * Copyright © 1997-1999 Janos Farkas <chexum@shadow.banki.hu>9 *10 * Using parts of the minix filesystem11 * Copyright © 1991, 1992 Linus Torvalds12 *13 * and parts of the affs filesystem additionally14 * Copyright © 1993 Ray Burr15 * Copyright © 1996 Hans-Joachim Widmaier16 *17 * Changes18 * Changed for 2.1.19 modules19 * Jan 1997 Initial release20 * Jun 1997 2.1.43+ changes21 * Proper page locking in read_folio22 * Changed to work with 2.1.45+ fs23 * Jul 1997 Fixed follow_link24 * 2.1.4725 * lookup shouldn't return -ENOENT26 * from Horst von Brand:27 * fail on wrong checksum28 * double unlock_super was possible29 * correct namelen for statfs30 * 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 readdir34 * 2.1.107 code-freeze spellchecker run35 * Aug 1998 2.1.118+ VFS changes36 * Sep 1998 2.1.122 another VFS change (follow_link)37 * Apr 1999 2.2.7 no more EBADF checking in38 * lookup/readdir, use ERR_PTR39 * Jun 1999 2.3.6 d_alloc_root use changed40 * 2.3.9 clean up usage of ENOENT/negative41 * dentries in lookup42 * clean up page flags setting43 * (error, uptodate, locking) in44 * in read_folio45 * use init_special_inode for46 * fifos/sockets (and streamline) in47 * read_inode, fix _ops table order48 * Aug 1999 2.3.16 __initfunc() => __init change49 * Oct 1999 2.3.24 page->owner hack obsoleted50 * Nov 1999 2.3.27 2.3.25+ page->offset => index change51 *52 *53 * This program is free software; you can redistribute it and/or54 * modify it under the terms of the GNU General Public Licence55 * as published by the Free Software Foundation; either version56 * 2 of the Licence, or (at your option) any later version.57 */58 59#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt60 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/fs_context.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 80static struct kmem_cache *romfs_inode_cachep;81 82static 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 93static const unsigned char romfs_dtype_table[] = {94 DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO95};96 97static struct inode *romfs_iget(struct super_block *sb, unsigned long pos);98 99/*100 * read a page worth of data from the image101 */102static int romfs_read_folio(struct file *file, struct folio *folio)103{104 struct inode *inode = folio->mapping->host;105 loff_t offset, size;106 unsigned long fillsize, pos;107 void *buf;108 int ret;109 110 buf = kmap_local_folio(folio, 0);111 112 offset = folio_pos(folio);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 fillsize = 0;125 ret = -EIO;126 }127 }128 129 buf = folio_zero_tail(folio, fillsize, buf + fillsize);130 kunmap_local(buf);131 folio_end_read(folio, ret == 0);132 return ret;133}134 135static const struct address_space_operations romfs_aops = {136 .read_folio = romfs_read_folio137};138 139/*140 * read the entries from a directory141 */142static int romfs_readdir(struct file *file, struct dir_context *ctx)143{144 struct inode *i = file_inode(file);145 struct romfs_inode ri;146 unsigned long offset, maxoff;147 int j, ino, nextfh;148 char fsname[ROMFS_MAXFN]; /* XXX dynamic? */149 int ret;150 151 maxoff = romfs_maxsize(i->i_sb);152 153 offset = ctx->pos;154 if (!offset) {155 offset = i->i_ino & ROMFH_MASK;156 ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);157 if (ret < 0)158 goto out;159 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;160 }161 162 /* Not really failsafe, but we are read-only... */163 for (;;) {164 if (!offset || offset >= maxoff) {165 offset = maxoff;166 ctx->pos = offset;167 goto out;168 }169 ctx->pos = offset;170 171 /* Fetch inode info */172 ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);173 if (ret < 0)174 goto out;175 176 j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE,177 sizeof(fsname) - 1);178 if (j < 0)179 goto out;180 181 ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j);182 if (ret < 0)183 goto out;184 fsname[j] = '\0';185 186 ino = offset;187 nextfh = be32_to_cpu(ri.next);188 if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)189 ino = be32_to_cpu(ri.spec);190 if (!dir_emit(ctx, fsname, j, ino,191 romfs_dtype_table[nextfh & ROMFH_TYPE]))192 goto out;193 194 offset = nextfh & ROMFH_MASK;195 }196out:197 return 0;198}199 200/*201 * look up an entry in a directory202 */203static struct dentry *romfs_lookup(struct inode *dir, struct dentry *dentry,204 unsigned int flags)205{206 unsigned long offset, maxoff;207 struct inode *inode = NULL;208 struct romfs_inode ri;209 const char *name; /* got from dentry */210 int len, ret;211 212 offset = dir->i_ino & ROMFH_MASK;213 ret = romfs_dev_read(dir->i_sb, offset, &ri, ROMFH_SIZE);214 if (ret < 0)215 goto error;216 217 /* search all the file entries in the list starting from the one218 * pointed to by the directory's special data */219 maxoff = romfs_maxsize(dir->i_sb);220 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;221 222 name = dentry->d_name.name;223 len = dentry->d_name.len;224 225 for (;;) {226 if (!offset || offset >= maxoff)227 break;228 229 ret = romfs_dev_read(dir->i_sb, offset, &ri, sizeof(ri));230 if (ret < 0)231 goto error;232 233 /* try to match the first 16 bytes of name */234 ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name,235 len);236 if (ret < 0)237 goto error;238 if (ret == 1) {239 /* Hard link handling */240 if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)241 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;242 inode = romfs_iget(dir->i_sb, offset);243 break;244 }245 246 /* next entry */247 offset = be32_to_cpu(ri.next) & ROMFH_MASK;248 }249 250 return d_splice_alias(inode, dentry);251error:252 return ERR_PTR(ret);253}254 255static const struct file_operations romfs_dir_operations = {256 .read = generic_read_dir,257 .iterate_shared = romfs_readdir,258 .llseek = generic_file_llseek,259};260 261static const struct inode_operations romfs_dir_inode_operations = {262 .lookup = romfs_lookup,263};264 265/*266 * get a romfs inode based on its position in the image (which doubles as the267 * inode number)268 */269static struct inode *romfs_iget(struct super_block *sb, unsigned long pos)270{271 struct romfs_inode_info *inode;272 struct romfs_inode ri;273 struct inode *i;274 unsigned long nlen;275 unsigned nextfh;276 int ret;277 umode_t mode;278 279 /* we might have to traverse a chain of "hard link" file entries to get280 * to the actual file */281 for (;;) {282 ret = romfs_dev_read(sb, pos, &ri, sizeof(ri));283 if (ret < 0)284 goto error;285 286 /* XXX: do romfs_checksum here too (with name) */287 288 nextfh = be32_to_cpu(ri.next);289 if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)290 break;291 292 pos = be32_to_cpu(ri.spec) & ROMFH_MASK;293 }294 295 /* determine the length of the filename */296 nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN);297 if (IS_ERR_VALUE(nlen))298 goto eio;299 300 /* get an inode for this image position */301 i = iget_locked(sb, pos);302 if (!i)303 return ERR_PTR(-ENOMEM);304 305 if (!(i->i_state & I_NEW))306 return i;307 308 /* precalculate the data offset */309 inode = ROMFS_I(i);310 inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK;311 inode->i_dataoffset = pos + inode->i_metasize;312 313 set_nlink(i, 1); /* Hard to decide.. */314 i->i_size = be32_to_cpu(ri.size);315 inode_set_mtime_to_ts(i,316 inode_set_atime_to_ts(i, inode_set_ctime(i, 0, 0)));317 318 /* set up mode and ops */319 mode = romfs_modemap[nextfh & ROMFH_TYPE];320 321 switch (nextfh & ROMFH_TYPE) {322 case ROMFH_DIR:323 i->i_size = ROMFS_I(i)->i_metasize;324 i->i_op = &romfs_dir_inode_operations;325 i->i_fop = &romfs_dir_operations;326 if (nextfh & ROMFH_EXEC)327 mode |= S_IXUGO;328 break;329 case ROMFH_REG:330 i->i_fop = &romfs_ro_fops;331 i->i_data.a_ops = &romfs_aops;332 if (nextfh & ROMFH_EXEC)333 mode |= S_IXUGO;334 break;335 case ROMFH_SYM:336 i->i_op = &page_symlink_inode_operations;337 inode_nohighmem(i);338 i->i_data.a_ops = &romfs_aops;339 mode |= S_IRWXUGO;340 break;341 default:342 /* depending on MBZ for sock/fifos */343 nextfh = be32_to_cpu(ri.spec);344 init_special_inode(i, mode, MKDEV(nextfh >> 16,345 nextfh & 0xffff));346 break;347 }348 349 i->i_mode = mode;350 i->i_blocks = (i->i_size + 511) >> 9;351 352 unlock_new_inode(i);353 return i;354 355eio:356 ret = -EIO;357error:358 pr_err("read error for inode 0x%lx\n", pos);359 return ERR_PTR(ret);360}361 362/*363 * allocate a new inode364 */365static struct inode *romfs_alloc_inode(struct super_block *sb)366{367 struct romfs_inode_info *inode;368 369 inode = alloc_inode_sb(sb, romfs_inode_cachep, GFP_KERNEL);370 return inode ? &inode->vfs_inode : NULL;371}372 373/*374 * return a spent inode to the slab cache375 */376static void romfs_free_inode(struct inode *inode)377{378 kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));379}380 381/*382 * get filesystem statistics383 */384static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf)385{386 struct super_block *sb = dentry->d_sb;387 u64 id = 0;388 389 /* When calling huge_encode_dev(),390 * use sb->s_bdev->bd_dev when,391 * - CONFIG_ROMFS_ON_BLOCK defined392 * use sb->s_dev when,393 * - CONFIG_ROMFS_ON_BLOCK undefined and394 * - CONFIG_ROMFS_ON_MTD defined395 * leave id as 0 when,396 * - CONFIG_ROMFS_ON_BLOCK undefined and397 * - CONFIG_ROMFS_ON_MTD undefined398 */399 if (sb->s_bdev)400 id = huge_encode_dev(sb->s_bdev->bd_dev);401 else if (sb->s_dev)402 id = huge_encode_dev(sb->s_dev);403 404 buf->f_type = ROMFS_MAGIC;405 buf->f_namelen = ROMFS_MAXFN;406 buf->f_bsize = ROMBSIZE;407 buf->f_bfree = buf->f_bavail = buf->f_ffree;408 buf->f_blocks =409 (romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS;410 buf->f_fsid = u64_to_fsid(id);411 return 0;412}413 414/*415 * remounting must involve read-only416 */417static int romfs_reconfigure(struct fs_context *fc)418{419 sync_filesystem(fc->root->d_sb);420 fc->sb_flags |= SB_RDONLY;421 return 0;422}423 424static const struct super_operations romfs_super_ops = {425 .alloc_inode = romfs_alloc_inode,426 .free_inode = romfs_free_inode,427 .statfs = romfs_statfs,428};429 430/*431 * checksum check on part of a romfs filesystem432 */433static __u32 romfs_checksum(const void *data, int size)434{435 const __be32 *ptr = data;436 __u32 sum;437 438 sum = 0;439 size >>= 2;440 while (size > 0) {441 sum += be32_to_cpu(*ptr++);442 size--;443 }444 return sum;445}446 447/*448 * fill in the superblock449 */450static int romfs_fill_super(struct super_block *sb, struct fs_context *fc)451{452 struct romfs_super_block *rsb;453 struct inode *root;454 unsigned long pos, img_size;455 const char *storage;456 size_t len;457 int ret;458 459#ifdef CONFIG_BLOCK460 if (!sb->s_mtd) {461 sb_set_blocksize(sb, ROMBSIZE);462 } else {463 sb->s_blocksize = ROMBSIZE;464 sb->s_blocksize_bits = blksize_bits(ROMBSIZE);465 }466#endif467 468 sb->s_maxbytes = 0xFFFFFFFF;469 sb->s_magic = ROMFS_MAGIC;470 sb->s_flags |= SB_RDONLY | SB_NOATIME;471 sb->s_time_min = 0;472 sb->s_time_max = 0;473 sb->s_op = &romfs_super_ops;474 475#ifdef CONFIG_ROMFS_ON_MTD476 /* Use same dev ID from the underlying mtdblock device */477 if (sb->s_mtd)478 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index);479#endif480 /* read the image superblock and check it */481 rsb = kmalloc(512, GFP_KERNEL);482 if (!rsb)483 return -ENOMEM;484 485 sb->s_fs_info = (void *) 512;486 ret = romfs_dev_read(sb, 0, rsb, 512);487 if (ret < 0)488 goto error_rsb;489 490 img_size = be32_to_cpu(rsb->size);491 492 if (sb->s_mtd && img_size > sb->s_mtd->size)493 goto error_rsb_inval;494 495 sb->s_fs_info = (void *) img_size;496 497 if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1 ||498 img_size < ROMFH_SIZE) {499 if (!(fc->sb_flags & SB_SILENT))500 errorf(fc, "VFS: Can't find a romfs filesystem on dev %s.\n",501 sb->s_id);502 goto error_rsb_inval;503 }504 505 if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) {506 pr_err("bad initial checksum on dev %s.\n", sb->s_id);507 goto error_rsb_inval;508 }509 510 storage = sb->s_mtd ? "MTD" : "the block layer";511 512 len = strnlen(rsb->name, ROMFS_MAXFN);513 if (!(fc->sb_flags & SB_SILENT))514 pr_notice("Mounting image '%*.*s' through %s\n",515 (unsigned) len, (unsigned) len, rsb->name, storage);516 517 kfree(rsb);518 rsb = NULL;519 520 /* find the root directory */521 pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK;522 523 root = romfs_iget(sb, pos);524 if (IS_ERR(root))525 return PTR_ERR(root);526 527 sb->s_root = d_make_root(root);528 if (!sb->s_root)529 return -ENOMEM;530 531 return 0;532 533error_rsb_inval:534 ret = -EINVAL;535error_rsb:536 kfree(rsb);537 return ret;538}539 540/*541 * get a superblock for mounting542 */543static int romfs_get_tree(struct fs_context *fc)544{545 int ret = -EINVAL;546 547#ifdef CONFIG_ROMFS_ON_MTD548 ret = get_tree_mtd(fc, romfs_fill_super);549#endif550#ifdef CONFIG_ROMFS_ON_BLOCK551 if (ret == -EINVAL)552 ret = get_tree_bdev(fc, romfs_fill_super);553#endif554 return ret;555}556 557static const struct fs_context_operations romfs_context_ops = {558 .get_tree = romfs_get_tree,559 .reconfigure = romfs_reconfigure,560};561 562/*563 * Set up the filesystem mount context.564 */565static int romfs_init_fs_context(struct fs_context *fc)566{567 fc->ops = &romfs_context_ops;568 return 0;569}570 571/*572 * destroy a romfs superblock in the appropriate manner573 */574static void romfs_kill_sb(struct super_block *sb)575{576 generic_shutdown_super(sb);577 578#ifdef CONFIG_ROMFS_ON_MTD579 if (sb->s_mtd) {580 put_mtd_device(sb->s_mtd);581 sb->s_mtd = NULL;582 }583#endif584#ifdef CONFIG_ROMFS_ON_BLOCK585 if (sb->s_bdev) {586 sync_blockdev(sb->s_bdev);587 bdev_fput(sb->s_bdev_file);588 }589#endif590}591 592static struct file_system_type romfs_fs_type = {593 .owner = THIS_MODULE,594 .name = "romfs",595 .init_fs_context = romfs_init_fs_context,596 .kill_sb = romfs_kill_sb,597 .fs_flags = FS_REQUIRES_DEV,598};599MODULE_ALIAS_FS("romfs");600 601/*602 * inode storage initialiser603 */604static void romfs_i_init_once(void *_inode)605{606 struct romfs_inode_info *inode = _inode;607 608 inode_init_once(&inode->vfs_inode);609}610 611/*612 * romfs module initialisation613 */614static int __init init_romfs_fs(void)615{616 int ret;617 618 pr_info("ROMFS MTD (C) 2007 Red Hat, Inc.\n");619 620 romfs_inode_cachep =621 kmem_cache_create("romfs_i",622 sizeof(struct romfs_inode_info), 0,623 SLAB_RECLAIM_ACCOUNT | SLAB_ACCOUNT,624 romfs_i_init_once);625 626 if (!romfs_inode_cachep) {627 pr_err("Failed to initialise inode cache\n");628 return -ENOMEM;629 }630 ret = register_filesystem(&romfs_fs_type);631 if (ret) {632 pr_err("Failed to register filesystem\n");633 goto error_register;634 }635 return 0;636 637error_register:638 kmem_cache_destroy(romfs_inode_cachep);639 return ret;640}641 642/*643 * romfs module removal644 */645static void __exit exit_romfs_fs(void)646{647 unregister_filesystem(&romfs_fs_type);648 /*649 * Make sure all delayed rcu free inodes are flushed before we650 * destroy cache.651 */652 rcu_barrier();653 kmem_cache_destroy(romfs_inode_cachep);654}655 656module_init(init_romfs_fs);657module_exit(exit_romfs_fs);658 659MODULE_DESCRIPTION("Direct-MTD Capable RomFS");660MODULE_AUTHOR("Red Hat, Inc.");661MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */662