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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 read_folio
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 read_folio
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/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_FIFO
95};
96
97static struct inode *romfs_iget(struct super_block *sb, unsigned long pos);
98
99/*
100 * read a page worth of data from the image
101 */
102static int romfs_read_folio(struct file *file, struct folio *folio)
103{
104 struct page *page = &folio->page;
105 struct inode *inode = page->mapping->host;
106 loff_t offset, size;
107 unsigned long fillsize, pos;
108 void *buf;
109 int ret;
110
111 buf = kmap(page);
112 if (!buf)
113 return -ENOMEM;
114
115 /* 32 bit warning -- but not for us :) */
116 offset = page_offset(page);
117 size = i_size_read(inode);
118 fillsize = 0;
119 ret = 0;
120 if (offset < size) {
121 size -= offset;
122 fillsize = size > PAGE_SIZE ? PAGE_SIZE : size;
123
124 pos = ROMFS_I(inode)->i_dataoffset + offset;
125
126 ret = romfs_dev_read(inode->i_sb, pos, buf, fillsize);
127 if (ret < 0) {
128 SetPageError(page);
129 fillsize = 0;
130 ret = -EIO;
131 }
132 }
133
134 if (fillsize < PAGE_SIZE)
135 memset(buf + fillsize, 0, PAGE_SIZE - fillsize);
136 if (ret == 0)
137 SetPageUptodate(page);
138
139 flush_dcache_page(page);
140 kunmap(page);
141 unlock_page(page);
142 return ret;
143}
144
145static const struct address_space_operations romfs_aops = {
146 .read_folio = romfs_read_folio
147};
148
149/*
150 * read the entries from a directory
151 */
152static int romfs_readdir(struct file *file, struct dir_context *ctx)
153{
154 struct inode *i = file_inode(file);
155 struct romfs_inode ri;
156 unsigned long offset, maxoff;
157 int j, ino, nextfh;
158 char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
159 int ret;
160
161 maxoff = romfs_maxsize(i->i_sb);
162
163 offset = ctx->pos;
164 if (!offset) {
165 offset = i->i_ino & ROMFH_MASK;
166 ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
167 if (ret < 0)
168 goto out;
169 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
170 }
171
172 /* Not really failsafe, but we are read-only... */
173 for (;;) {
174 if (!offset || offset >= maxoff) {
175 offset = maxoff;
176 ctx->pos = offset;
177 goto out;
178 }
179 ctx->pos = offset;
180
181 /* Fetch inode info */
182 ret = romfs_dev_read(i->i_sb, offset, &ri, ROMFH_SIZE);
183 if (ret < 0)
184 goto out;
185
186 j = romfs_dev_strnlen(i->i_sb, offset + ROMFH_SIZE,
187 sizeof(fsname) - 1);
188 if (j < 0)
189 goto out;
190
191 ret = romfs_dev_read(i->i_sb, offset + ROMFH_SIZE, fsname, j);
192 if (ret < 0)
193 goto out;
194 fsname[j] = '\0';
195
196 ino = offset;
197 nextfh = be32_to_cpu(ri.next);
198 if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
199 ino = be32_to_cpu(ri.spec);
200 if (!dir_emit(ctx, fsname, j, ino,
201 romfs_dtype_table[nextfh & ROMFH_TYPE]))
202 goto out;
203
204 offset = nextfh & ROMFH_MASK;
205 }
206out:
207 return 0;
208}
209
210/*
211 * look up an entry in a directory
212 */
213static struct dentry *romfs_lookup(struct inode *dir, struct dentry *dentry,
214 unsigned int flags)
215{
216 unsigned long offset, maxoff;
217 struct inode *inode = NULL;
218 struct romfs_inode ri;
219 const char *name; /* got from dentry */
220 int len, ret;
221
222 offset = dir->i_ino & ROMFH_MASK;
223 ret = romfs_dev_read(dir->i_sb, offset, &ri, ROMFH_SIZE);
224 if (ret < 0)
225 goto error;
226
227 /* search all the file entries in the list starting from the one
228 * pointed to by the directory's special data */
229 maxoff = romfs_maxsize(dir->i_sb);
230 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
231
232 name = dentry->d_name.name;
233 len = dentry->d_name.len;
234
235 for (;;) {
236 if (!offset || offset >= maxoff)
237 break;
238
239 ret = romfs_dev_read(dir->i_sb, offset, &ri, sizeof(ri));
240 if (ret < 0)
241 goto error;
242
243 /* try to match the first 16 bytes of name */
244 ret = romfs_dev_strcmp(dir->i_sb, offset + ROMFH_SIZE, name,
245 len);
246 if (ret < 0)
247 goto error;
248 if (ret == 1) {
249 /* Hard link handling */
250 if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
251 offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
252 inode = romfs_iget(dir->i_sb, offset);
253 break;
254 }
255
256 /* next entry */
257 offset = be32_to_cpu(ri.next) & ROMFH_MASK;
258 }
259
260 return d_splice_alias(inode, dentry);
261error:
262 return ERR_PTR(ret);
263}
264
265static const struct file_operations romfs_dir_operations = {
266 .read = generic_read_dir,
267 .iterate_shared = romfs_readdir,
268 .llseek = generic_file_llseek,
269};
270
271static const struct inode_operations romfs_dir_inode_operations = {
272 .lookup = romfs_lookup,
273};
274
275/*
276 * get a romfs inode based on its position in the image (which doubles as the
277 * inode number)
278 */
279static struct inode *romfs_iget(struct super_block *sb, unsigned long pos)
280{
281 struct romfs_inode_info *inode;
282 struct romfs_inode ri;
283 struct inode *i;
284 unsigned long nlen;
285 unsigned nextfh;
286 int ret;
287 umode_t mode;
288
289 /* we might have to traverse a chain of "hard link" file entries to get
290 * to the actual file */
291 for (;;) {
292 ret = romfs_dev_read(sb, pos, &ri, sizeof(ri));
293 if (ret < 0)
294 goto error;
295
296 /* XXX: do romfs_checksum here too (with name) */
297
298 nextfh = be32_to_cpu(ri.next);
299 if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
300 break;
301
302 pos = be32_to_cpu(ri.spec) & ROMFH_MASK;
303 }
304
305 /* determine the length of the filename */
306 nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN);
307 if (IS_ERR_VALUE(nlen))
308 goto eio;
309
310 /* get an inode for this image position */
311 i = iget_locked(sb, pos);
312 if (!i)
313 return ERR_PTR(-ENOMEM);
314
315 if (!(i->i_state & I_NEW))
316 return i;
317
318 /* precalculate the data offset */
319 inode = ROMFS_I(i);
320 inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK;
321 inode->i_dataoffset = pos + inode->i_metasize;
322
323 set_nlink(i, 1); /* Hard to decide.. */
324 i->i_size = be32_to_cpu(ri.size);
325 inode_set_mtime_to_ts(i,
326 inode_set_atime_to_ts(i, inode_set_ctime(i, 0, 0)));
327
328 /* set up mode and ops */
329 mode = romfs_modemap[nextfh & ROMFH_TYPE];
330
331 switch (nextfh & ROMFH_TYPE) {
332 case ROMFH_DIR:
333 i->i_size = ROMFS_I(i)->i_metasize;
334 i->i_op = &romfs_dir_inode_operations;
335 i->i_fop = &romfs_dir_operations;
336 if (nextfh & ROMFH_EXEC)
337 mode |= S_IXUGO;
338 break;
339 case ROMFH_REG:
340 i->i_fop = &romfs_ro_fops;
341 i->i_data.a_ops = &romfs_aops;
342 if (nextfh & ROMFH_EXEC)
343 mode |= S_IXUGO;
344 break;
345 case ROMFH_SYM:
346 i->i_op = &page_symlink_inode_operations;
347 inode_nohighmem(i);
348 i->i_data.a_ops = &romfs_aops;
349 mode |= S_IRWXUGO;
350 break;
351 default:
352 /* depending on MBZ for sock/fifos */
353 nextfh = be32_to_cpu(ri.spec);
354 init_special_inode(i, mode, MKDEV(nextfh >> 16,
355 nextfh & 0xffff));
356 break;
357 }
358
359 i->i_mode = mode;
360 i->i_blocks = (i->i_size + 511) >> 9;
361
362 unlock_new_inode(i);
363 return i;
364
365eio:
366 ret = -EIO;
367error:
368 pr_err("read error for inode 0x%lx\n", pos);
369 return ERR_PTR(ret);
370}
371
372/*
373 * allocate a new inode
374 */
375static struct inode *romfs_alloc_inode(struct super_block *sb)
376{
377 struct romfs_inode_info *inode;
378
379 inode = alloc_inode_sb(sb, romfs_inode_cachep, GFP_KERNEL);
380 return inode ? &inode->vfs_inode : NULL;
381}
382
383/*
384 * return a spent inode to the slab cache
385 */
386static void romfs_free_inode(struct inode *inode)
387{
388 kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
389}
390
391/*
392 * get filesystem statistics
393 */
394static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf)
395{
396 struct super_block *sb = dentry->d_sb;
397 u64 id = 0;
398
399 /* When calling huge_encode_dev(),
400 * use sb->s_bdev->bd_dev when,
401 * - CONFIG_ROMFS_ON_BLOCK defined
402 * use sb->s_dev when,
403 * - CONFIG_ROMFS_ON_BLOCK undefined and
404 * - CONFIG_ROMFS_ON_MTD defined
405 * leave id as 0 when,
406 * - CONFIG_ROMFS_ON_BLOCK undefined and
407 * - CONFIG_ROMFS_ON_MTD undefined
408 */
409 if (sb->s_bdev)
410 id = huge_encode_dev(sb->s_bdev->bd_dev);
411 else if (sb->s_dev)
412 id = huge_encode_dev(sb->s_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 = u64_to_fsid(id);
421 return 0;
422}
423
424/*
425 * remounting must involve read-only
426 */
427static int romfs_reconfigure(struct fs_context *fc)
428{
429 sync_filesystem(fc->root->d_sb);
430 fc->sb_flags |= SB_RDONLY;
431 return 0;
432}
433
434static const struct super_operations romfs_super_ops = {
435 .alloc_inode = romfs_alloc_inode,
436 .free_inode = romfs_free_inode,
437 .statfs = romfs_statfs,
438};
439
440/*
441 * checksum check on part of a romfs filesystem
442 */
443static __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 */
460static int romfs_fill_super(struct super_block *sb, struct fs_context *fc)
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_time_min = 0;
482 sb->s_time_max = 0;
483 sb->s_op = &romfs_super_ops;
484
485#ifdef CONFIG_ROMFS_ON_MTD
486 /* Use same dev ID from the underlying mtdblock device */
487 if (sb->s_mtd)
488 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index);
489#endif
490 /* read the image superblock and check it */
491 rsb = kmalloc(512, GFP_KERNEL);
492 if (!rsb)
493 return -ENOMEM;
494
495 sb->s_fs_info = (void *) 512;
496 ret = romfs_dev_read(sb, 0, rsb, 512);
497 if (ret < 0)
498 goto error_rsb;
499
500 img_size = be32_to_cpu(rsb->size);
501
502 if (sb->s_mtd && img_size > sb->s_mtd->size)
503 goto error_rsb_inval;
504
505 sb->s_fs_info = (void *) img_size;
506
507 if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1 ||
508 img_size < ROMFH_SIZE) {
509 if (!(fc->sb_flags & SB_SILENT))
510 errorf(fc, "VFS: Can't find a romfs filesystem on dev %s.\n",
511 sb->s_id);
512 goto error_rsb_inval;
513 }
514
515 if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) {
516 pr_err("bad initial checksum on dev %s.\n", sb->s_id);
517 goto error_rsb_inval;
518 }
519
520 storage = sb->s_mtd ? "MTD" : "the block layer";
521
522 len = strnlen(rsb->name, ROMFS_MAXFN);
523 if (!(fc->sb_flags & SB_SILENT))
524 pr_notice("Mounting image '%*.*s' through %s\n",
525 (unsigned) len, (unsigned) len, rsb->name, storage);
526
527 kfree(rsb);
528 rsb = NULL;
529
530 /* find the root directory */
531 pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK;
532
533 root = romfs_iget(sb, pos);
534 if (IS_ERR(root))
535 return PTR_ERR(root);
536
537 sb->s_root = d_make_root(root);
538 if (!sb->s_root)
539 return -ENOMEM;
540
541 return 0;
542
543error_rsb_inval:
544 ret = -EINVAL;
545error_rsb:
546 kfree(rsb);
547 return ret;
548}
549
550/*
551 * get a superblock for mounting
552 */
553static int romfs_get_tree(struct fs_context *fc)
554{
555 int ret = -EINVAL;
556
557#ifdef CONFIG_ROMFS_ON_MTD
558 ret = get_tree_mtd(fc, romfs_fill_super);
559#endif
560#ifdef CONFIG_ROMFS_ON_BLOCK
561 if (ret == -EINVAL)
562 ret = get_tree_bdev(fc, romfs_fill_super);
563#endif
564 return ret;
565}
566
567static const struct fs_context_operations romfs_context_ops = {
568 .get_tree = romfs_get_tree,
569 .reconfigure = romfs_reconfigure,
570};
571
572/*
573 * Set up the filesystem mount context.
574 */
575static int romfs_init_fs_context(struct fs_context *fc)
576{
577 fc->ops = &romfs_context_ops;
578 return 0;
579}
580
581/*
582 * destroy a romfs superblock in the appropriate manner
583 */
584static void romfs_kill_sb(struct super_block *sb)
585{
586 generic_shutdown_super(sb);
587
588#ifdef CONFIG_ROMFS_ON_MTD
589 if (sb->s_mtd) {
590 put_mtd_device(sb->s_mtd);
591 sb->s_mtd = NULL;
592 }
593#endif
594#ifdef CONFIG_ROMFS_ON_BLOCK
595 if (sb->s_bdev) {
596 sync_blockdev(sb->s_bdev);
597 bdev_release(sb->s_bdev_handle);
598 }
599#endif
600}
601
602static struct file_system_type romfs_fs_type = {
603 .owner = THIS_MODULE,
604 .name = "romfs",
605 .init_fs_context = romfs_init_fs_context,
606 .kill_sb = romfs_kill_sb,
607 .fs_flags = FS_REQUIRES_DEV,
608};
609MODULE_ALIAS_FS("romfs");
610
611/*
612 * inode storage initialiser
613 */
614static void romfs_i_init_once(void *_inode)
615{
616 struct romfs_inode_info *inode = _inode;
617
618 inode_init_once(&inode->vfs_inode);
619}
620
621/*
622 * romfs module initialisation
623 */
624static int __init init_romfs_fs(void)
625{
626 int ret;
627
628 pr_info("ROMFS MTD (C) 2007 Red Hat, Inc.\n");
629
630 romfs_inode_cachep =
631 kmem_cache_create("romfs_i",
632 sizeof(struct romfs_inode_info), 0,
633 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD |
634 SLAB_ACCOUNT, romfs_i_init_once);
635
636 if (!romfs_inode_cachep) {
637 pr_err("Failed to initialise inode cache\n");
638 return -ENOMEM;
639 }
640 ret = register_filesystem(&romfs_fs_type);
641 if (ret) {
642 pr_err("Failed to register filesystem\n");
643 goto error_register;
644 }
645 return 0;
646
647error_register:
648 kmem_cache_destroy(romfs_inode_cachep);
649 return ret;
650}
651
652/*
653 * romfs module removal
654 */
655static void __exit exit_romfs_fs(void)
656{
657 unregister_filesystem(&romfs_fs_type);
658 /*
659 * Make sure all delayed rcu free inodes are flushed before we
660 * destroy cache.
661 */
662 rcu_barrier();
663 kmem_cache_destroy(romfs_inode_cachep);
664}
665
666module_init(init_romfs_fs);
667module_exit(exit_romfs_fs);
668
669MODULE_DESCRIPTION("Direct-MTD Capable RomFS");
670MODULE_AUTHOR("Red Hat, Inc.");
671MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */
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
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_FIFO
95};
96
97static struct inode *romfs_iget(struct super_block *sb, unsigned long pos);
98
99/*
100 * read a page worth of data from the image
101 */
102static 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
144static const struct address_space_operations romfs_aops = {
145 .readpage = romfs_readpage
146};
147
148/*
149 * read the entries from a directory
150 */
151static 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 }
205out:
206 return 0;
207}
208
209/*
210 * look up an entry in a directory
211 */
212static struct dentry *romfs_lookup(struct inode *dir, struct dentry *dentry,
213 unsigned int flags)
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 */
273out0:
274 inode = NULL;
275outi:
276 d_add(dentry, inode);
277 ret = 0;
278error:
279 return ERR_PTR(ret);
280}
281
282static const struct file_operations romfs_dir_operations = {
283 .read = generic_read_dir,
284 .iterate_shared = romfs_readdir,
285 .llseek = generic_file_llseek,
286};
287
288static const struct inode_operations romfs_dir_inode_operations = {
289 .lookup = romfs_lookup,
290};
291
292/*
293 * get a romfs inode based on its position in the image (which doubles as the
294 * inode number)
295 */
296static struct inode *romfs_iget(struct super_block *sb, unsigned long pos)
297{
298 struct romfs_inode_info *inode;
299 struct romfs_inode ri;
300 struct inode *i;
301 unsigned long nlen;
302 unsigned nextfh;
303 int ret;
304 umode_t mode;
305
306 /* we might have to traverse a chain of "hard link" file entries to get
307 * to the actual file */
308 for (;;) {
309 ret = romfs_dev_read(sb, pos, &ri, sizeof(ri));
310 if (ret < 0)
311 goto error;
312
313 /* XXX: do romfs_checksum here too (with name) */
314
315 nextfh = be32_to_cpu(ri.next);
316 if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
317 break;
318
319 pos = be32_to_cpu(ri.spec) & ROMFH_MASK;
320 }
321
322 /* determine the length of the filename */
323 nlen = romfs_dev_strnlen(sb, pos + ROMFH_SIZE, ROMFS_MAXFN);
324 if (IS_ERR_VALUE(nlen))
325 goto eio;
326
327 /* get an inode for this image position */
328 i = iget_locked(sb, pos);
329 if (!i)
330 return ERR_PTR(-ENOMEM);
331
332 if (!(i->i_state & I_NEW))
333 return i;
334
335 /* precalculate the data offset */
336 inode = ROMFS_I(i);
337 inode->i_metasize = (ROMFH_SIZE + nlen + 1 + ROMFH_PAD) & ROMFH_MASK;
338 inode->i_dataoffset = pos + inode->i_metasize;
339
340 set_nlink(i, 1); /* Hard to decide.. */
341 i->i_size = be32_to_cpu(ri.size);
342 i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0;
343 i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 0;
344
345 /* set up mode and ops */
346 mode = romfs_modemap[nextfh & ROMFH_TYPE];
347
348 switch (nextfh & ROMFH_TYPE) {
349 case ROMFH_DIR:
350 i->i_size = ROMFS_I(i)->i_metasize;
351 i->i_op = &romfs_dir_inode_operations;
352 i->i_fop = &romfs_dir_operations;
353 if (nextfh & ROMFH_EXEC)
354 mode |= S_IXUGO;
355 break;
356 case ROMFH_REG:
357 i->i_fop = &romfs_ro_fops;
358 i->i_data.a_ops = &romfs_aops;
359 if (nextfh & ROMFH_EXEC)
360 mode |= S_IXUGO;
361 break;
362 case ROMFH_SYM:
363 i->i_op = &page_symlink_inode_operations;
364 inode_nohighmem(i);
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
381eio:
382 ret = -EIO;
383error:
384 pr_err("read error for inode 0x%lx\n", pos);
385 return ERR_PTR(ret);
386}
387
388/*
389 * allocate a new inode
390 */
391static struct inode *romfs_alloc_inode(struct super_block *sb)
392{
393 struct romfs_inode_info *inode;
394
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 */
402static void romfs_i_callback(struct rcu_head *head)
403{
404 struct inode *inode = container_of(head, struct inode, i_rcu);
405
406 kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
407}
408
409static void romfs_destroy_inode(struct inode *inode)
410{
411 call_rcu(&inode->i_rcu, romfs_i_callback);
412}
413
414/*
415 * get filesystem statistics
416 */
417static int romfs_statfs(struct dentry *dentry, struct kstatfs *buf)
418{
419 struct super_block *sb = dentry->d_sb;
420 u64 id = 0;
421
422 /* When calling huge_encode_dev(),
423 * use sb->s_bdev->bd_dev when,
424 * - CONFIG_ROMFS_ON_BLOCK defined
425 * use sb->s_dev when,
426 * - CONFIG_ROMFS_ON_BLOCK undefined and
427 * - CONFIG_ROMFS_ON_MTD defined
428 * leave id as 0 when,
429 * - CONFIG_ROMFS_ON_BLOCK undefined and
430 * - CONFIG_ROMFS_ON_MTD undefined
431 */
432 if (sb->s_bdev)
433 id = huge_encode_dev(sb->s_bdev->bd_dev);
434 else if (sb->s_dev)
435 id = huge_encode_dev(sb->s_dev);
436
437 buf->f_type = ROMFS_MAGIC;
438 buf->f_namelen = ROMFS_MAXFN;
439 buf->f_bsize = ROMBSIZE;
440 buf->f_bfree = buf->f_bavail = buf->f_ffree;
441 buf->f_blocks =
442 (romfs_maxsize(dentry->d_sb) + ROMBSIZE - 1) >> ROMBSBITS;
443 buf->f_fsid.val[0] = (u32)id;
444 buf->f_fsid.val[1] = (u32)(id >> 32);
445 return 0;
446}
447
448/*
449 * remounting must involve read-only
450 */
451static int romfs_remount(struct super_block *sb, int *flags, char *data)
452{
453 sync_filesystem(sb);
454 *flags |= SB_RDONLY;
455 return 0;
456}
457
458static const struct super_operations romfs_super_ops = {
459 .alloc_inode = romfs_alloc_inode,
460 .destroy_inode = romfs_destroy_inode,
461 .statfs = romfs_statfs,
462 .remount_fs = romfs_remount,
463};
464
465/*
466 * checksum check on part of a romfs filesystem
467 */
468static __u32 romfs_checksum(const void *data, int size)
469{
470 const __be32 *ptr = data;
471 __u32 sum;
472
473 sum = 0;
474 size >>= 2;
475 while (size > 0) {
476 sum += be32_to_cpu(*ptr++);
477 size--;
478 }
479 return sum;
480}
481
482/*
483 * fill in the superblock
484 */
485static int romfs_fill_super(struct super_block *sb, void *data, int silent)
486{
487 struct romfs_super_block *rsb;
488 struct inode *root;
489 unsigned long pos, img_size;
490 const char *storage;
491 size_t len;
492 int ret;
493
494#ifdef CONFIG_BLOCK
495 if (!sb->s_mtd) {
496 sb_set_blocksize(sb, ROMBSIZE);
497 } else {
498 sb->s_blocksize = ROMBSIZE;
499 sb->s_blocksize_bits = blksize_bits(ROMBSIZE);
500 }
501#endif
502
503 sb->s_maxbytes = 0xFFFFFFFF;
504 sb->s_magic = ROMFS_MAGIC;
505 sb->s_flags |= SB_RDONLY | SB_NOATIME;
506 sb->s_op = &romfs_super_ops;
507
508#ifdef CONFIG_ROMFS_ON_MTD
509 /* Use same dev ID from the underlying mtdblock device */
510 if (sb->s_mtd)
511 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index);
512#endif
513 /* read the image superblock and check it */
514 rsb = kmalloc(512, GFP_KERNEL);
515 if (!rsb)
516 return -ENOMEM;
517
518 sb->s_fs_info = (void *) 512;
519 ret = romfs_dev_read(sb, 0, rsb, 512);
520 if (ret < 0)
521 goto error_rsb;
522
523 img_size = be32_to_cpu(rsb->size);
524
525 if (sb->s_mtd && img_size > sb->s_mtd->size)
526 goto error_rsb_inval;
527
528 sb->s_fs_info = (void *) img_size;
529
530 if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1 ||
531 img_size < ROMFH_SIZE) {
532 if (!silent)
533 pr_warn("VFS: Can't find a romfs filesystem on dev %s.\n",
534 sb->s_id);
535 goto error_rsb_inval;
536 }
537
538 if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) {
539 pr_err("bad initial checksum on dev %s.\n", sb->s_id);
540 goto error_rsb_inval;
541 }
542
543 storage = sb->s_mtd ? "MTD" : "the block layer";
544
545 len = strnlen(rsb->name, ROMFS_MAXFN);
546 if (!silent)
547 pr_notice("Mounting image '%*.*s' through %s\n",
548 (unsigned) len, (unsigned) len, rsb->name, storage);
549
550 kfree(rsb);
551 rsb = NULL;
552
553 /* find the root directory */
554 pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK;
555
556 root = romfs_iget(sb, pos);
557 if (IS_ERR(root))
558 return PTR_ERR(root);
559
560 sb->s_root = d_make_root(root);
561 if (!sb->s_root)
562 return -ENOMEM;
563
564 return 0;
565
566error_rsb_inval:
567 ret = -EINVAL;
568error_rsb:
569 kfree(rsb);
570 return ret;
571}
572
573/*
574 * get a superblock for mounting
575 */
576static struct dentry *romfs_mount(struct file_system_type *fs_type,
577 int flags, const char *dev_name,
578 void *data)
579{
580 struct dentry *ret = ERR_PTR(-EINVAL);
581
582#ifdef CONFIG_ROMFS_ON_MTD
583 ret = mount_mtd(fs_type, flags, dev_name, data, romfs_fill_super);
584#endif
585#ifdef CONFIG_ROMFS_ON_BLOCK
586 if (ret == ERR_PTR(-EINVAL))
587 ret = mount_bdev(fs_type, flags, dev_name, data,
588 romfs_fill_super);
589#endif
590 return ret;
591}
592
593/*
594 * destroy a romfs superblock in the appropriate manner
595 */
596static void romfs_kill_sb(struct super_block *sb)
597{
598#ifdef CONFIG_ROMFS_ON_MTD
599 if (sb->s_mtd) {
600 kill_mtd_super(sb);
601 return;
602 }
603#endif
604#ifdef CONFIG_ROMFS_ON_BLOCK
605 if (sb->s_bdev) {
606 kill_block_super(sb);
607 return;
608 }
609#endif
610}
611
612static struct file_system_type romfs_fs_type = {
613 .owner = THIS_MODULE,
614 .name = "romfs",
615 .mount = romfs_mount,
616 .kill_sb = romfs_kill_sb,
617 .fs_flags = FS_REQUIRES_DEV,
618};
619MODULE_ALIAS_FS("romfs");
620
621/*
622 * inode storage initialiser
623 */
624static void romfs_i_init_once(void *_inode)
625{
626 struct romfs_inode_info *inode = _inode;
627
628 inode_init_once(&inode->vfs_inode);
629}
630
631/*
632 * romfs module initialisation
633 */
634static int __init init_romfs_fs(void)
635{
636 int ret;
637
638 pr_info("ROMFS MTD (C) 2007 Red Hat, Inc.\n");
639
640 romfs_inode_cachep =
641 kmem_cache_create("romfs_i",
642 sizeof(struct romfs_inode_info), 0,
643 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD |
644 SLAB_ACCOUNT, romfs_i_init_once);
645
646 if (!romfs_inode_cachep) {
647 pr_err("Failed to initialise inode cache\n");
648 return -ENOMEM;
649 }
650 ret = register_filesystem(&romfs_fs_type);
651 if (ret) {
652 pr_err("Failed to register filesystem\n");
653 goto error_register;
654 }
655 return 0;
656
657error_register:
658 kmem_cache_destroy(romfs_inode_cachep);
659 return ret;
660}
661
662/*
663 * romfs module removal
664 */
665static void __exit exit_romfs_fs(void)
666{
667 unregister_filesystem(&romfs_fs_type);
668 /*
669 * Make sure all delayed rcu free inodes are flushed before we
670 * destroy cache.
671 */
672 rcu_barrier();
673 kmem_cache_destroy(romfs_inode_cachep);
674}
675
676module_init(init_romfs_fs);
677module_exit(exit_romfs_fs);
678
679MODULE_DESCRIPTION("Direct-MTD Capable RomFS");
680MODULE_AUTHOR("Red Hat, Inc.");
681MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */