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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/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_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 = 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);
260error:
261 return ERR_PTR(ret);
262}
263
264static const struct file_operations romfs_dir_operations = {
265 .read = generic_read_dir,
266 .iterate_shared = romfs_readdir,
267 .llseek = generic_file_llseek,
268};
269
270static 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 */
278static 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
363eio:
364 ret = -EIO;
365error:
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 */
373static 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 */
384static 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 */
392static 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 */
426static int romfs_reconfigure(struct fs_context *fc)
427{
428 sync_filesystem(fc->root->d_sb);
429 fc->sb_flags |= SB_RDONLY;
430 return 0;
431}
432
433static const struct super_operations romfs_super_ops = {
434 .alloc_inode = romfs_alloc_inode,
435 .free_inode = romfs_free_inode,
436 .statfs = romfs_statfs,
437};
438
439/*
440 * checksum check on part of a romfs filesystem
441 */
442static __u32 romfs_checksum(const void *data, int size)
443{
444 const __be32 *ptr = data;
445 __u32 sum;
446
447 sum = 0;
448 size >>= 2;
449 while (size > 0) {
450 sum += be32_to_cpu(*ptr++);
451 size--;
452 }
453 return sum;
454}
455
456/*
457 * fill in the superblock
458 */
459static int romfs_fill_super(struct super_block *sb, struct fs_context *fc)
460{
461 struct romfs_super_block *rsb;
462 struct inode *root;
463 unsigned long pos, img_size;
464 const char *storage;
465 size_t len;
466 int ret;
467
468#ifdef CONFIG_BLOCK
469 if (!sb->s_mtd) {
470 sb_set_blocksize(sb, ROMBSIZE);
471 } else {
472 sb->s_blocksize = ROMBSIZE;
473 sb->s_blocksize_bits = blksize_bits(ROMBSIZE);
474 }
475#endif
476
477 sb->s_maxbytes = 0xFFFFFFFF;
478 sb->s_magic = ROMFS_MAGIC;
479 sb->s_flags |= SB_RDONLY | SB_NOATIME;
480 sb->s_time_min = 0;
481 sb->s_time_max = 0;
482 sb->s_op = &romfs_super_ops;
483
484#ifdef CONFIG_ROMFS_ON_MTD
485 /* Use same dev ID from the underlying mtdblock device */
486 if (sb->s_mtd)
487 sb->s_dev = MKDEV(MTD_BLOCK_MAJOR, sb->s_mtd->index);
488#endif
489 /* read the image superblock and check it */
490 rsb = kmalloc(512, GFP_KERNEL);
491 if (!rsb)
492 return -ENOMEM;
493
494 sb->s_fs_info = (void *) 512;
495 ret = romfs_dev_read(sb, 0, rsb, 512);
496 if (ret < 0)
497 goto error_rsb;
498
499 img_size = be32_to_cpu(rsb->size);
500
501 if (sb->s_mtd && img_size > sb->s_mtd->size)
502 goto error_rsb_inval;
503
504 sb->s_fs_info = (void *) img_size;
505
506 if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1 ||
507 img_size < ROMFH_SIZE) {
508 if (!(fc->sb_flags & SB_SILENT))
509 errorf(fc, "VFS: Can't find a romfs filesystem on dev %s.\n",
510 sb->s_id);
511 goto error_rsb_inval;
512 }
513
514 if (romfs_checksum(rsb, min_t(size_t, img_size, 512))) {
515 pr_err("bad initial checksum on dev %s.\n", sb->s_id);
516 goto error_rsb_inval;
517 }
518
519 storage = sb->s_mtd ? "MTD" : "the block layer";
520
521 len = strnlen(rsb->name, ROMFS_MAXFN);
522 if (!(fc->sb_flags & SB_SILENT))
523 pr_notice("Mounting image '%*.*s' through %s\n",
524 (unsigned) len, (unsigned) len, rsb->name, storage);
525
526 kfree(rsb);
527 rsb = NULL;
528
529 /* find the root directory */
530 pos = (ROMFH_SIZE + len + 1 + ROMFH_PAD) & ROMFH_MASK;
531
532 root = romfs_iget(sb, pos);
533 if (IS_ERR(root))
534 return PTR_ERR(root);
535
536 sb->s_root = d_make_root(root);
537 if (!sb->s_root)
538 return -ENOMEM;
539
540 return 0;
541
542error_rsb_inval:
543 ret = -EINVAL;
544error_rsb:
545 kfree(rsb);
546 return ret;
547}
548
549/*
550 * get a superblock for mounting
551 */
552static int romfs_get_tree(struct fs_context *fc)
553{
554 int ret = -EINVAL;
555
556#ifdef CONFIG_ROMFS_ON_MTD
557 ret = get_tree_mtd(fc, romfs_fill_super);
558#endif
559#ifdef CONFIG_ROMFS_ON_BLOCK
560 if (ret == -EINVAL)
561 ret = get_tree_bdev(fc, romfs_fill_super);
562#endif
563 return ret;
564}
565
566static const struct fs_context_operations romfs_context_ops = {
567 .get_tree = romfs_get_tree,
568 .reconfigure = romfs_reconfigure,
569};
570
571/*
572 * Set up the filesystem mount context.
573 */
574static int romfs_init_fs_context(struct fs_context *fc)
575{
576 fc->ops = &romfs_context_ops;
577 return 0;
578}
579
580/*
581 * destroy a romfs superblock in the appropriate manner
582 */
583static void romfs_kill_sb(struct super_block *sb)
584{
585#ifdef CONFIG_ROMFS_ON_MTD
586 if (sb->s_mtd) {
587 kill_mtd_super(sb);
588 return;
589 }
590#endif
591#ifdef CONFIG_ROMFS_ON_BLOCK
592 if (sb->s_bdev) {
593 kill_block_super(sb);
594 return;
595 }
596#endif
597}
598
599static struct file_system_type romfs_fs_type = {
600 .owner = THIS_MODULE,
601 .name = "romfs",
602 .init_fs_context = romfs_init_fs_context,
603 .kill_sb = romfs_kill_sb,
604 .fs_flags = FS_REQUIRES_DEV,
605};
606MODULE_ALIAS_FS("romfs");
607
608/*
609 * inode storage initialiser
610 */
611static void romfs_i_init_once(void *_inode)
612{
613 struct romfs_inode_info *inode = _inode;
614
615 inode_init_once(&inode->vfs_inode);
616}
617
618/*
619 * romfs module initialisation
620 */
621static int __init init_romfs_fs(void)
622{
623 int ret;
624
625 pr_info("ROMFS MTD (C) 2007 Red Hat, Inc.\n");
626
627 romfs_inode_cachep =
628 kmem_cache_create("romfs_i",
629 sizeof(struct romfs_inode_info), 0,
630 SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD |
631 SLAB_ACCOUNT, romfs_i_init_once);
632
633 if (!romfs_inode_cachep) {
634 pr_err("Failed to initialise inode cache\n");
635 return -ENOMEM;
636 }
637 ret = register_filesystem(&romfs_fs_type);
638 if (ret) {
639 pr_err("Failed to register filesystem\n");
640 goto error_register;
641 }
642 return 0;
643
644error_register:
645 kmem_cache_destroy(romfs_inode_cachep);
646 return ret;
647}
648
649/*
650 * romfs module removal
651 */
652static void __exit exit_romfs_fs(void)
653{
654 unregister_filesystem(&romfs_fs_type);
655 /*
656 * Make sure all delayed rcu free inodes are flushed before we
657 * destroy cache.
658 */
659 rcu_barrier();
660 kmem_cache_destroy(romfs_inode_cachep);
661}
662
663module_init(init_romfs_fs);
664module_exit(exit_romfs_fs);
665
666MODULE_DESCRIPTION("Direct-MTD Capable RomFS");
667MODULE_AUTHOR("Red Hat, Inc.");
668MODULE_LICENSE("GPL"); /* Actually dual-licensed, but it doesn't matter for */