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1/*
2 * Compressed rom filesystem for Linux.
3 *
4 * Copyright (C) 1999 Linus Torvalds.
5 *
6 * This file is released under the GPL.
7 */
8
9/*
10 * These are the VFS interfaces to the compressed rom filesystem.
11 * The actual compression is based on zlib, see the other files.
12 */
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/module.h>
17#include <linux/fs.h>
18#include <linux/file.h>
19#include <linux/pagemap.h>
20#include <linux/pfn_t.h>
21#include <linux/ramfs.h>
22#include <linux/init.h>
23#include <linux/string.h>
24#include <linux/blkdev.h>
25#include <linux/mtd/mtd.h>
26#include <linux/mtd/super.h>
27#include <linux/fs_context.h>
28#include <linux/slab.h>
29#include <linux/vfs.h>
30#include <linux/mutex.h>
31#include <uapi/linux/cramfs_fs.h>
32#include <linux/uaccess.h>
33
34#include "internal.h"
35
36/*
37 * cramfs super-block data in memory
38 */
39struct cramfs_sb_info {
40 unsigned long magic;
41 unsigned long size;
42 unsigned long blocks;
43 unsigned long files;
44 unsigned long flags;
45 void *linear_virt_addr;
46 resource_size_t linear_phys_addr;
47 size_t mtd_point_size;
48};
49
50static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb)
51{
52 return sb->s_fs_info;
53}
54
55static const struct super_operations cramfs_ops;
56static const struct inode_operations cramfs_dir_inode_operations;
57static const struct file_operations cramfs_directory_operations;
58static const struct file_operations cramfs_physmem_fops;
59static const struct address_space_operations cramfs_aops;
60
61static DEFINE_MUTEX(read_mutex);
62
63
64/* These macros may change in future, to provide better st_ino semantics. */
65#define OFFSET(x) ((x)->i_ino)
66
67static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset)
68{
69 if (!cino->offset)
70 return offset + 1;
71 if (!cino->size)
72 return offset + 1;
73
74 /*
75 * The file mode test fixes buggy mkcramfs implementations where
76 * cramfs_inode->offset is set to a non zero value for entries
77 * which did not contain data, like devices node and fifos.
78 */
79 switch (cino->mode & S_IFMT) {
80 case S_IFREG:
81 case S_IFDIR:
82 case S_IFLNK:
83 return cino->offset << 2;
84 default:
85 break;
86 }
87 return offset + 1;
88}
89
90static struct inode *get_cramfs_inode(struct super_block *sb,
91 const struct cramfs_inode *cramfs_inode, unsigned int offset)
92{
93 struct inode *inode;
94 static struct timespec64 zerotime;
95
96 inode = iget_locked(sb, cramino(cramfs_inode, offset));
97 if (!inode)
98 return ERR_PTR(-ENOMEM);
99 if (!(inode->i_state & I_NEW))
100 return inode;
101
102 switch (cramfs_inode->mode & S_IFMT) {
103 case S_IFREG:
104 inode->i_fop = &generic_ro_fops;
105 inode->i_data.a_ops = &cramfs_aops;
106 if (IS_ENABLED(CONFIG_CRAMFS_MTD) &&
107 CRAMFS_SB(sb)->flags & CRAMFS_FLAG_EXT_BLOCK_POINTERS &&
108 CRAMFS_SB(sb)->linear_phys_addr)
109 inode->i_fop = &cramfs_physmem_fops;
110 break;
111 case S_IFDIR:
112 inode->i_op = &cramfs_dir_inode_operations;
113 inode->i_fop = &cramfs_directory_operations;
114 break;
115 case S_IFLNK:
116 inode->i_op = &page_symlink_inode_operations;
117 inode_nohighmem(inode);
118 inode->i_data.a_ops = &cramfs_aops;
119 break;
120 default:
121 init_special_inode(inode, cramfs_inode->mode,
122 old_decode_dev(cramfs_inode->size));
123 }
124
125 inode->i_mode = cramfs_inode->mode;
126 i_uid_write(inode, cramfs_inode->uid);
127 i_gid_write(inode, cramfs_inode->gid);
128
129 /* if the lower 2 bits are zero, the inode contains data */
130 if (!(inode->i_ino & 3)) {
131 inode->i_size = cramfs_inode->size;
132 inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
133 }
134
135 /* Struct copy intentional */
136 inode_set_mtime_to_ts(inode,
137 inode_set_atime_to_ts(inode, inode_set_ctime_to_ts(inode, zerotime)));
138 /* inode->i_nlink is left 1 - arguably wrong for directories,
139 but it's the best we can do without reading the directory
140 contents. 1 yields the right result in GNU find, even
141 without -noleaf option. */
142
143 unlock_new_inode(inode);
144
145 return inode;
146}
147
148/*
149 * We have our own block cache: don't fill up the buffer cache
150 * with the rom-image, because the way the filesystem is set
151 * up the accesses should be fairly regular and cached in the
152 * page cache and dentry tree anyway..
153 *
154 * This also acts as a way to guarantee contiguous areas of up to
155 * BLKS_PER_BUF*PAGE_SIZE, so that the caller doesn't need to
156 * worry about end-of-buffer issues even when decompressing a full
157 * page cache.
158 *
159 * Note: This is all optimized away at compile time when
160 * CONFIG_CRAMFS_BLOCKDEV=n.
161 */
162#define READ_BUFFERS (2)
163/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
164#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
165
166/*
167 * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
168 * data that takes up more space than the original and with unlucky
169 * alignment.
170 */
171#define BLKS_PER_BUF_SHIFT (2)
172#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
173#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_SIZE)
174
175static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
176static unsigned buffer_blocknr[READ_BUFFERS];
177static struct super_block *buffer_dev[READ_BUFFERS];
178static int next_buffer;
179
180/*
181 * Populate our block cache and return a pointer to it.
182 */
183static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
184 unsigned int len)
185{
186 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
187 struct file_ra_state ra = {};
188 struct page *pages[BLKS_PER_BUF];
189 unsigned i, blocknr, buffer;
190 unsigned long devsize;
191 char *data;
192
193 if (!len)
194 return NULL;
195 blocknr = offset >> PAGE_SHIFT;
196 offset &= PAGE_SIZE - 1;
197
198 /* Check if an existing buffer already has the data.. */
199 for (i = 0; i < READ_BUFFERS; i++) {
200 unsigned int blk_offset;
201
202 if (buffer_dev[i] != sb)
203 continue;
204 if (blocknr < buffer_blocknr[i])
205 continue;
206 blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT;
207 blk_offset += offset;
208 if (blk_offset > BUFFER_SIZE ||
209 blk_offset + len > BUFFER_SIZE)
210 continue;
211 return read_buffers[i] + blk_offset;
212 }
213
214 devsize = bdev_nr_bytes(sb->s_bdev) >> PAGE_SHIFT;
215
216 /* Ok, read in BLKS_PER_BUF pages completely first. */
217 file_ra_state_init(&ra, mapping);
218 page_cache_sync_readahead(mapping, &ra, NULL, blocknr, BLKS_PER_BUF);
219
220 for (i = 0; i < BLKS_PER_BUF; i++) {
221 struct page *page = NULL;
222
223 if (blocknr + i < devsize) {
224 page = read_mapping_page(mapping, blocknr + i, NULL);
225 /* synchronous error? */
226 if (IS_ERR(page))
227 page = NULL;
228 }
229 pages[i] = page;
230 }
231
232 buffer = next_buffer;
233 next_buffer = NEXT_BUFFER(buffer);
234 buffer_blocknr[buffer] = blocknr;
235 buffer_dev[buffer] = sb;
236
237 data = read_buffers[buffer];
238 for (i = 0; i < BLKS_PER_BUF; i++) {
239 struct page *page = pages[i];
240
241 if (page) {
242 memcpy_from_page(data, page, 0, PAGE_SIZE);
243 put_page(page);
244 } else
245 memset(data, 0, PAGE_SIZE);
246 data += PAGE_SIZE;
247 }
248 return read_buffers[buffer] + offset;
249}
250
251/*
252 * Return a pointer to the linearly addressed cramfs image in memory.
253 */
254static void *cramfs_direct_read(struct super_block *sb, unsigned int offset,
255 unsigned int len)
256{
257 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
258
259 if (!len)
260 return NULL;
261 if (len > sbi->size || offset > sbi->size - len)
262 return page_address(ZERO_PAGE(0));
263 return sbi->linear_virt_addr + offset;
264}
265
266/*
267 * Returns a pointer to a buffer containing at least LEN bytes of
268 * filesystem starting at byte offset OFFSET into the filesystem.
269 */
270static void *cramfs_read(struct super_block *sb, unsigned int offset,
271 unsigned int len)
272{
273 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
274
275 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sbi->linear_virt_addr)
276 return cramfs_direct_read(sb, offset, len);
277 else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
278 return cramfs_blkdev_read(sb, offset, len);
279 else
280 return NULL;
281}
282
283/*
284 * For a mapping to be possible, we need a range of uncompressed and
285 * contiguous blocks. Return the offset for the first block and number of
286 * valid blocks for which that is true, or zero otherwise.
287 */
288static u32 cramfs_get_block_range(struct inode *inode, u32 pgoff, u32 *pages)
289{
290 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
291 int i;
292 u32 *blockptrs, first_block_addr;
293
294 /*
295 * We can dereference memory directly here as this code may be
296 * reached only when there is a direct filesystem image mapping
297 * available in memory.
298 */
299 blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode) + pgoff * 4);
300 first_block_addr = blockptrs[0] & ~CRAMFS_BLK_FLAGS;
301 i = 0;
302 do {
303 u32 block_off = i * (PAGE_SIZE >> CRAMFS_BLK_DIRECT_PTR_SHIFT);
304 u32 expect = (first_block_addr + block_off) |
305 CRAMFS_BLK_FLAG_DIRECT_PTR |
306 CRAMFS_BLK_FLAG_UNCOMPRESSED;
307 if (blockptrs[i] != expect) {
308 pr_debug("range: block %d/%d got %#x expects %#x\n",
309 pgoff+i, pgoff + *pages - 1,
310 blockptrs[i], expect);
311 if (i == 0)
312 return 0;
313 break;
314 }
315 } while (++i < *pages);
316
317 *pages = i;
318 return first_block_addr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
319}
320
321#ifdef CONFIG_MMU
322
323/*
324 * Return true if the last page of a file in the filesystem image contains
325 * some other data that doesn't belong to that file. It is assumed that the
326 * last block is CRAMFS_BLK_FLAG_DIRECT_PTR | CRAMFS_BLK_FLAG_UNCOMPRESSED
327 * (verified by cramfs_get_block_range() and directly accessible in memory.
328 */
329static bool cramfs_last_page_is_shared(struct inode *inode)
330{
331 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
332 u32 partial, last_page, blockaddr, *blockptrs;
333 char *tail_data;
334
335 partial = offset_in_page(inode->i_size);
336 if (!partial)
337 return false;
338 last_page = inode->i_size >> PAGE_SHIFT;
339 blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode));
340 blockaddr = blockptrs[last_page] & ~CRAMFS_BLK_FLAGS;
341 blockaddr <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
342 tail_data = sbi->linear_virt_addr + blockaddr + partial;
343 return memchr_inv(tail_data, 0, PAGE_SIZE - partial) ? true : false;
344}
345
346static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
347{
348 struct inode *inode = file_inode(file);
349 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
350 unsigned int pages, max_pages, offset;
351 unsigned long address, pgoff = vma->vm_pgoff;
352 char *bailout_reason;
353 int ret;
354
355 ret = generic_file_readonly_mmap(file, vma);
356 if (ret)
357 return ret;
358
359 /*
360 * Now try to pre-populate ptes for this vma with a direct
361 * mapping avoiding memory allocation when possible.
362 */
363
364 /* Could COW work here? */
365 bailout_reason = "vma is writable";
366 if (vma->vm_flags & VM_WRITE)
367 goto bailout;
368
369 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
370 bailout_reason = "beyond file limit";
371 if (pgoff >= max_pages)
372 goto bailout;
373 pages = min(vma_pages(vma), max_pages - pgoff);
374
375 offset = cramfs_get_block_range(inode, pgoff, &pages);
376 bailout_reason = "unsuitable block layout";
377 if (!offset)
378 goto bailout;
379 address = sbi->linear_phys_addr + offset;
380 bailout_reason = "data is not page aligned";
381 if (!PAGE_ALIGNED(address))
382 goto bailout;
383
384 /* Don't map the last page if it contains some other data */
385 if (pgoff + pages == max_pages && cramfs_last_page_is_shared(inode)) {
386 pr_debug("mmap: %pD: last page is shared\n", file);
387 pages--;
388 }
389
390 if (!pages) {
391 bailout_reason = "no suitable block remaining";
392 goto bailout;
393 }
394
395 if (pages == vma_pages(vma)) {
396 /*
397 * The entire vma is mappable. remap_pfn_range() will
398 * make it distinguishable from a non-direct mapping
399 * in /proc/<pid>/maps by substituting the file offset
400 * with the actual physical address.
401 */
402 ret = remap_pfn_range(vma, vma->vm_start, address >> PAGE_SHIFT,
403 pages * PAGE_SIZE, vma->vm_page_prot);
404 } else {
405 /*
406 * Let's create a mixed map if we can't map it all.
407 * The normal paging machinery will take care of the
408 * unpopulated ptes via cramfs_read_folio().
409 */
410 int i;
411 vm_flags_set(vma, VM_MIXEDMAP);
412 for (i = 0; i < pages && !ret; i++) {
413 vm_fault_t vmf;
414 unsigned long off = i * PAGE_SIZE;
415 pfn_t pfn = phys_to_pfn_t(address + off, PFN_DEV);
416 vmf = vmf_insert_mixed(vma, vma->vm_start + off, pfn);
417 if (vmf & VM_FAULT_ERROR)
418 ret = vm_fault_to_errno(vmf, 0);
419 }
420 }
421
422 if (!ret)
423 pr_debug("mapped %pD[%lu] at 0x%08lx (%u/%lu pages) "
424 "to vma 0x%08lx, page_prot 0x%llx\n", file,
425 pgoff, address, pages, vma_pages(vma), vma->vm_start,
426 (unsigned long long)pgprot_val(vma->vm_page_prot));
427 return ret;
428
429bailout:
430 pr_debug("%pD[%lu]: direct mmap impossible: %s\n",
431 file, pgoff, bailout_reason);
432 /* Didn't manage any direct map, but normal paging is still possible */
433 return 0;
434}
435
436#else /* CONFIG_MMU */
437
438static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
439{
440 return is_nommu_shared_mapping(vma->vm_flags) ? 0 : -ENOSYS;
441}
442
443static unsigned long cramfs_physmem_get_unmapped_area(struct file *file,
444 unsigned long addr, unsigned long len,
445 unsigned long pgoff, unsigned long flags)
446{
447 struct inode *inode = file_inode(file);
448 struct super_block *sb = inode->i_sb;
449 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
450 unsigned int pages, block_pages, max_pages, offset;
451
452 pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
453 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
454 if (pgoff >= max_pages || pages > max_pages - pgoff)
455 return -EINVAL;
456 block_pages = pages;
457 offset = cramfs_get_block_range(inode, pgoff, &block_pages);
458 if (!offset || block_pages != pages)
459 return -ENOSYS;
460 addr = sbi->linear_phys_addr + offset;
461 pr_debug("get_unmapped for %pD ofs %#lx siz %lu at 0x%08lx\n",
462 file, pgoff*PAGE_SIZE, len, addr);
463 return addr;
464}
465
466static unsigned int cramfs_physmem_mmap_capabilities(struct file *file)
467{
468 return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT |
469 NOMMU_MAP_READ | NOMMU_MAP_EXEC;
470}
471
472#endif /* CONFIG_MMU */
473
474static const struct file_operations cramfs_physmem_fops = {
475 .llseek = generic_file_llseek,
476 .read_iter = generic_file_read_iter,
477 .splice_read = filemap_splice_read,
478 .mmap = cramfs_physmem_mmap,
479#ifndef CONFIG_MMU
480 .get_unmapped_area = cramfs_physmem_get_unmapped_area,
481 .mmap_capabilities = cramfs_physmem_mmap_capabilities,
482#endif
483};
484
485static void cramfs_kill_sb(struct super_block *sb)
486{
487 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
488
489 generic_shutdown_super(sb);
490
491 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sb->s_mtd) {
492 if (sbi && sbi->mtd_point_size)
493 mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size);
494 put_mtd_device(sb->s_mtd);
495 sb->s_mtd = NULL;
496 } else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) {
497 sync_blockdev(sb->s_bdev);
498 bdev_release(sb->s_bdev_handle);
499 }
500 kfree(sbi);
501}
502
503static int cramfs_reconfigure(struct fs_context *fc)
504{
505 sync_filesystem(fc->root->d_sb);
506 fc->sb_flags |= SB_RDONLY;
507 return 0;
508}
509
510static int cramfs_read_super(struct super_block *sb, struct fs_context *fc,
511 struct cramfs_super *super)
512{
513 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
514 unsigned long root_offset;
515 bool silent = fc->sb_flags & SB_SILENT;
516
517 /* We don't know the real size yet */
518 sbi->size = PAGE_SIZE;
519
520 /* Read the first block and get the superblock from it */
521 mutex_lock(&read_mutex);
522 memcpy(super, cramfs_read(sb, 0, sizeof(*super)), sizeof(*super));
523 mutex_unlock(&read_mutex);
524
525 /* Do sanity checks on the superblock */
526 if (super->magic != CRAMFS_MAGIC) {
527 /* check for wrong endianness */
528 if (super->magic == CRAMFS_MAGIC_WEND) {
529 if (!silent)
530 errorfc(fc, "wrong endianness");
531 return -EINVAL;
532 }
533
534 /* check at 512 byte offset */
535 mutex_lock(&read_mutex);
536 memcpy(super,
537 cramfs_read(sb, 512, sizeof(*super)),
538 sizeof(*super));
539 mutex_unlock(&read_mutex);
540 if (super->magic != CRAMFS_MAGIC) {
541 if (super->magic == CRAMFS_MAGIC_WEND && !silent)
542 errorfc(fc, "wrong endianness");
543 else if (!silent)
544 errorfc(fc, "wrong magic");
545 return -EINVAL;
546 }
547 }
548
549 /* get feature flags first */
550 if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) {
551 errorfc(fc, "unsupported filesystem features");
552 return -EINVAL;
553 }
554
555 /* Check that the root inode is in a sane state */
556 if (!S_ISDIR(super->root.mode)) {
557 errorfc(fc, "root is not a directory");
558 return -EINVAL;
559 }
560 /* correct strange, hard-coded permissions of mkcramfs */
561 super->root.mode |= 0555;
562
563 root_offset = super->root.offset << 2;
564 if (super->flags & CRAMFS_FLAG_FSID_VERSION_2) {
565 sbi->size = super->size;
566 sbi->blocks = super->fsid.blocks;
567 sbi->files = super->fsid.files;
568 } else {
569 sbi->size = 1<<28;
570 sbi->blocks = 0;
571 sbi->files = 0;
572 }
573 sbi->magic = super->magic;
574 sbi->flags = super->flags;
575 if (root_offset == 0)
576 infofc(fc, "empty filesystem");
577 else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
578 ((root_offset != sizeof(struct cramfs_super)) &&
579 (root_offset != 512 + sizeof(struct cramfs_super))))
580 {
581 errorfc(fc, "bad root offset %lu", root_offset);
582 return -EINVAL;
583 }
584
585 return 0;
586}
587
588static int cramfs_finalize_super(struct super_block *sb,
589 struct cramfs_inode *cramfs_root)
590{
591 struct inode *root;
592
593 /* Set it all up.. */
594 sb->s_flags |= SB_RDONLY;
595 sb->s_time_min = 0;
596 sb->s_time_max = 0;
597 sb->s_op = &cramfs_ops;
598 root = get_cramfs_inode(sb, cramfs_root, 0);
599 if (IS_ERR(root))
600 return PTR_ERR(root);
601 sb->s_root = d_make_root(root);
602 if (!sb->s_root)
603 return -ENOMEM;
604 return 0;
605}
606
607static int cramfs_blkdev_fill_super(struct super_block *sb, struct fs_context *fc)
608{
609 struct cramfs_sb_info *sbi;
610 struct cramfs_super super;
611 int i, err;
612
613 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
614 if (!sbi)
615 return -ENOMEM;
616 sb->s_fs_info = sbi;
617
618 /* Invalidate the read buffers on mount: think disk change.. */
619 for (i = 0; i < READ_BUFFERS; i++)
620 buffer_blocknr[i] = -1;
621
622 err = cramfs_read_super(sb, fc, &super);
623 if (err)
624 return err;
625 return cramfs_finalize_super(sb, &super.root);
626}
627
628static int cramfs_mtd_fill_super(struct super_block *sb, struct fs_context *fc)
629{
630 struct cramfs_sb_info *sbi;
631 struct cramfs_super super;
632 int err;
633
634 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
635 if (!sbi)
636 return -ENOMEM;
637 sb->s_fs_info = sbi;
638
639 /* Map only one page for now. Will remap it when fs size is known. */
640 err = mtd_point(sb->s_mtd, 0, PAGE_SIZE, &sbi->mtd_point_size,
641 &sbi->linear_virt_addr, &sbi->linear_phys_addr);
642 if (err || sbi->mtd_point_size != PAGE_SIZE) {
643 pr_err("unable to get direct memory access to mtd:%s\n",
644 sb->s_mtd->name);
645 return err ? : -ENODATA;
646 }
647
648 pr_info("checking physical address %pap for linear cramfs image\n",
649 &sbi->linear_phys_addr);
650 err = cramfs_read_super(sb, fc, &super);
651 if (err)
652 return err;
653
654 /* Remap the whole filesystem now */
655 pr_info("linear cramfs image on mtd:%s appears to be %lu KB in size\n",
656 sb->s_mtd->name, sbi->size/1024);
657 mtd_unpoint(sb->s_mtd, 0, PAGE_SIZE);
658 err = mtd_point(sb->s_mtd, 0, sbi->size, &sbi->mtd_point_size,
659 &sbi->linear_virt_addr, &sbi->linear_phys_addr);
660 if (err || sbi->mtd_point_size != sbi->size) {
661 pr_err("unable to get direct memory access to mtd:%s\n",
662 sb->s_mtd->name);
663 return err ? : -ENODATA;
664 }
665
666 return cramfs_finalize_super(sb, &super.root);
667}
668
669static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
670{
671 struct super_block *sb = dentry->d_sb;
672 u64 id = 0;
673
674 if (sb->s_bdev)
675 id = huge_encode_dev(sb->s_bdev->bd_dev);
676 else if (sb->s_dev)
677 id = huge_encode_dev(sb->s_dev);
678
679 buf->f_type = CRAMFS_MAGIC;
680 buf->f_bsize = PAGE_SIZE;
681 buf->f_blocks = CRAMFS_SB(sb)->blocks;
682 buf->f_bfree = 0;
683 buf->f_bavail = 0;
684 buf->f_files = CRAMFS_SB(sb)->files;
685 buf->f_ffree = 0;
686 buf->f_fsid = u64_to_fsid(id);
687 buf->f_namelen = CRAMFS_MAXPATHLEN;
688 return 0;
689}
690
691/*
692 * Read a cramfs directory entry.
693 */
694static int cramfs_readdir(struct file *file, struct dir_context *ctx)
695{
696 struct inode *inode = file_inode(file);
697 struct super_block *sb = inode->i_sb;
698 char *buf;
699 unsigned int offset;
700
701 /* Offset within the thing. */
702 if (ctx->pos >= inode->i_size)
703 return 0;
704 offset = ctx->pos;
705 /* Directory entries are always 4-byte aligned */
706 if (offset & 3)
707 return -EINVAL;
708
709 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
710 if (!buf)
711 return -ENOMEM;
712
713 while (offset < inode->i_size) {
714 struct cramfs_inode *de;
715 unsigned long nextoffset;
716 char *name;
717 ino_t ino;
718 umode_t mode;
719 int namelen;
720
721 mutex_lock(&read_mutex);
722 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
723 name = (char *)(de+1);
724
725 /*
726 * Namelengths on disk are shifted by two
727 * and the name padded out to 4-byte boundaries
728 * with zeroes.
729 */
730 namelen = de->namelen << 2;
731 memcpy(buf, name, namelen);
732 ino = cramino(de, OFFSET(inode) + offset);
733 mode = de->mode;
734 mutex_unlock(&read_mutex);
735 nextoffset = offset + sizeof(*de) + namelen;
736 for (;;) {
737 if (!namelen) {
738 kfree(buf);
739 return -EIO;
740 }
741 if (buf[namelen-1])
742 break;
743 namelen--;
744 }
745 if (!dir_emit(ctx, buf, namelen, ino, mode >> 12))
746 break;
747
748 ctx->pos = offset = nextoffset;
749 }
750 kfree(buf);
751 return 0;
752}
753
754/*
755 * Lookup and fill in the inode data..
756 */
757static struct dentry *cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
758{
759 unsigned int offset = 0;
760 struct inode *inode = NULL;
761 int sorted;
762
763 mutex_lock(&read_mutex);
764 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
765 while (offset < dir->i_size) {
766 struct cramfs_inode *de;
767 char *name;
768 int namelen, retval;
769 int dir_off = OFFSET(dir) + offset;
770
771 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
772 name = (char *)(de+1);
773
774 /* Try to take advantage of sorted directories */
775 if (sorted && (dentry->d_name.name[0] < name[0]))
776 break;
777
778 namelen = de->namelen << 2;
779 offset += sizeof(*de) + namelen;
780
781 /* Quick check that the name is roughly the right length */
782 if (((dentry->d_name.len + 3) & ~3) != namelen)
783 continue;
784
785 for (;;) {
786 if (!namelen) {
787 inode = ERR_PTR(-EIO);
788 goto out;
789 }
790 if (name[namelen-1])
791 break;
792 namelen--;
793 }
794 if (namelen != dentry->d_name.len)
795 continue;
796 retval = memcmp(dentry->d_name.name, name, namelen);
797 if (retval > 0)
798 continue;
799 if (!retval) {
800 inode = get_cramfs_inode(dir->i_sb, de, dir_off);
801 break;
802 }
803 /* else (retval < 0) */
804 if (sorted)
805 break;
806 }
807out:
808 mutex_unlock(&read_mutex);
809 return d_splice_alias(inode, dentry);
810}
811
812static int cramfs_read_folio(struct file *file, struct folio *folio)
813{
814 struct page *page = &folio->page;
815 struct inode *inode = page->mapping->host;
816 u32 maxblock;
817 int bytes_filled;
818 void *pgdata;
819
820 maxblock = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
821 bytes_filled = 0;
822 pgdata = kmap_local_page(page);
823
824 if (page->index < maxblock) {
825 struct super_block *sb = inode->i_sb;
826 u32 blkptr_offset = OFFSET(inode) + page->index * 4;
827 u32 block_ptr, block_start, block_len;
828 bool uncompressed, direct;
829
830 mutex_lock(&read_mutex);
831 block_ptr = *(u32 *) cramfs_read(sb, blkptr_offset, 4);
832 uncompressed = (block_ptr & CRAMFS_BLK_FLAG_UNCOMPRESSED);
833 direct = (block_ptr & CRAMFS_BLK_FLAG_DIRECT_PTR);
834 block_ptr &= ~CRAMFS_BLK_FLAGS;
835
836 if (direct) {
837 /*
838 * The block pointer is an absolute start pointer,
839 * shifted by 2 bits. The size is included in the
840 * first 2 bytes of the data block when compressed,
841 * or PAGE_SIZE otherwise.
842 */
843 block_start = block_ptr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
844 if (uncompressed) {
845 block_len = PAGE_SIZE;
846 /* if last block: cap to file length */
847 if (page->index == maxblock - 1)
848 block_len =
849 offset_in_page(inode->i_size);
850 } else {
851 block_len = *(u16 *)
852 cramfs_read(sb, block_start, 2);
853 block_start += 2;
854 }
855 } else {
856 /*
857 * The block pointer indicates one past the end of
858 * the current block (start of next block). If this
859 * is the first block then it starts where the block
860 * pointer table ends, otherwise its start comes
861 * from the previous block's pointer.
862 */
863 block_start = OFFSET(inode) + maxblock * 4;
864 if (page->index)
865 block_start = *(u32 *)
866 cramfs_read(sb, blkptr_offset - 4, 4);
867 /* Beware... previous ptr might be a direct ptr */
868 if (unlikely(block_start & CRAMFS_BLK_FLAG_DIRECT_PTR)) {
869 /* See comments on earlier code. */
870 u32 prev_start = block_start;
871 block_start = prev_start & ~CRAMFS_BLK_FLAGS;
872 block_start <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
873 if (prev_start & CRAMFS_BLK_FLAG_UNCOMPRESSED) {
874 block_start += PAGE_SIZE;
875 } else {
876 block_len = *(u16 *)
877 cramfs_read(sb, block_start, 2);
878 block_start += 2 + block_len;
879 }
880 }
881 block_start &= ~CRAMFS_BLK_FLAGS;
882 block_len = block_ptr - block_start;
883 }
884
885 if (block_len == 0)
886 ; /* hole */
887 else if (unlikely(block_len > 2*PAGE_SIZE ||
888 (uncompressed && block_len > PAGE_SIZE))) {
889 mutex_unlock(&read_mutex);
890 pr_err("bad data blocksize %u\n", block_len);
891 goto err;
892 } else if (uncompressed) {
893 memcpy(pgdata,
894 cramfs_read(sb, block_start, block_len),
895 block_len);
896 bytes_filled = block_len;
897 } else {
898 bytes_filled = cramfs_uncompress_block(pgdata,
899 PAGE_SIZE,
900 cramfs_read(sb, block_start, block_len),
901 block_len);
902 }
903 mutex_unlock(&read_mutex);
904 if (unlikely(bytes_filled < 0))
905 goto err;
906 }
907
908 memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled);
909 flush_dcache_page(page);
910 kunmap_local(pgdata);
911 SetPageUptodate(page);
912 unlock_page(page);
913 return 0;
914
915err:
916 kunmap_local(pgdata);
917 ClearPageUptodate(page);
918 SetPageError(page);
919 unlock_page(page);
920 return 0;
921}
922
923static const struct address_space_operations cramfs_aops = {
924 .read_folio = cramfs_read_folio
925};
926
927/*
928 * Our operations:
929 */
930
931/*
932 * A directory can only readdir
933 */
934static const struct file_operations cramfs_directory_operations = {
935 .llseek = generic_file_llseek,
936 .read = generic_read_dir,
937 .iterate_shared = cramfs_readdir,
938};
939
940static const struct inode_operations cramfs_dir_inode_operations = {
941 .lookup = cramfs_lookup,
942};
943
944static const struct super_operations cramfs_ops = {
945 .statfs = cramfs_statfs,
946};
947
948static int cramfs_get_tree(struct fs_context *fc)
949{
950 int ret = -ENOPROTOOPT;
951
952 if (IS_ENABLED(CONFIG_CRAMFS_MTD)) {
953 ret = get_tree_mtd(fc, cramfs_mtd_fill_super);
954 if (!ret)
955 return 0;
956 }
957 if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
958 ret = get_tree_bdev(fc, cramfs_blkdev_fill_super);
959 return ret;
960}
961
962static const struct fs_context_operations cramfs_context_ops = {
963 .get_tree = cramfs_get_tree,
964 .reconfigure = cramfs_reconfigure,
965};
966
967/*
968 * Set up the filesystem mount context.
969 */
970static int cramfs_init_fs_context(struct fs_context *fc)
971{
972 fc->ops = &cramfs_context_ops;
973 return 0;
974}
975
976static struct file_system_type cramfs_fs_type = {
977 .owner = THIS_MODULE,
978 .name = "cramfs",
979 .init_fs_context = cramfs_init_fs_context,
980 .kill_sb = cramfs_kill_sb,
981 .fs_flags = FS_REQUIRES_DEV,
982};
983MODULE_ALIAS_FS("cramfs");
984
985static int __init init_cramfs_fs(void)
986{
987 int rv;
988
989 rv = cramfs_uncompress_init();
990 if (rv < 0)
991 return rv;
992 rv = register_filesystem(&cramfs_fs_type);
993 if (rv < 0)
994 cramfs_uncompress_exit();
995 return rv;
996}
997
998static void __exit exit_cramfs_fs(void)
999{
1000 cramfs_uncompress_exit();
1001 unregister_filesystem(&cramfs_fs_type);
1002}
1003
1004module_init(init_cramfs_fs)
1005module_exit(exit_cramfs_fs)
1006MODULE_LICENSE("GPL");
1/*
2 * Compressed rom filesystem for Linux.
3 *
4 * Copyright (C) 1999 Linus Torvalds.
5 *
6 * This file is released under the GPL.
7 */
8
9/*
10 * These are the VFS interfaces to the compressed rom filesystem.
11 * The actual compression is based on zlib, see the other files.
12 */
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/module.h>
17#include <linux/fs.h>
18#include <linux/file.h>
19#include <linux/pagemap.h>
20#include <linux/pfn_t.h>
21#include <linux/ramfs.h>
22#include <linux/init.h>
23#include <linux/string.h>
24#include <linux/blkdev.h>
25#include <linux/mtd/mtd.h>
26#include <linux/mtd/super.h>
27#include <linux/fs_context.h>
28#include <linux/slab.h>
29#include <linux/vfs.h>
30#include <linux/mutex.h>
31#include <uapi/linux/cramfs_fs.h>
32#include <linux/uaccess.h>
33
34#include "internal.h"
35
36/*
37 * cramfs super-block data in memory
38 */
39struct cramfs_sb_info {
40 unsigned long magic;
41 unsigned long size;
42 unsigned long blocks;
43 unsigned long files;
44 unsigned long flags;
45 void *linear_virt_addr;
46 resource_size_t linear_phys_addr;
47 size_t mtd_point_size;
48};
49
50static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb)
51{
52 return sb->s_fs_info;
53}
54
55static const struct super_operations cramfs_ops;
56static const struct inode_operations cramfs_dir_inode_operations;
57static const struct file_operations cramfs_directory_operations;
58static const struct file_operations cramfs_physmem_fops;
59static const struct address_space_operations cramfs_aops;
60
61static DEFINE_MUTEX(read_mutex);
62
63
64/* These macros may change in future, to provide better st_ino semantics. */
65#define OFFSET(x) ((x)->i_ino)
66
67static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset)
68{
69 if (!cino->offset)
70 return offset + 1;
71 if (!cino->size)
72 return offset + 1;
73
74 /*
75 * The file mode test fixes buggy mkcramfs implementations where
76 * cramfs_inode->offset is set to a non zero value for entries
77 * which did not contain data, like devices node and fifos.
78 */
79 switch (cino->mode & S_IFMT) {
80 case S_IFREG:
81 case S_IFDIR:
82 case S_IFLNK:
83 return cino->offset << 2;
84 default:
85 break;
86 }
87 return offset + 1;
88}
89
90static struct inode *get_cramfs_inode(struct super_block *sb,
91 const struct cramfs_inode *cramfs_inode, unsigned int offset)
92{
93 struct inode *inode;
94 static struct timespec64 zerotime;
95
96 inode = iget_locked(sb, cramino(cramfs_inode, offset));
97 if (!inode)
98 return ERR_PTR(-ENOMEM);
99 if (!(inode->i_state & I_NEW))
100 return inode;
101
102 switch (cramfs_inode->mode & S_IFMT) {
103 case S_IFREG:
104 inode->i_fop = &generic_ro_fops;
105 inode->i_data.a_ops = &cramfs_aops;
106 if (IS_ENABLED(CONFIG_CRAMFS_MTD) &&
107 CRAMFS_SB(sb)->flags & CRAMFS_FLAG_EXT_BLOCK_POINTERS &&
108 CRAMFS_SB(sb)->linear_phys_addr)
109 inode->i_fop = &cramfs_physmem_fops;
110 break;
111 case S_IFDIR:
112 inode->i_op = &cramfs_dir_inode_operations;
113 inode->i_fop = &cramfs_directory_operations;
114 break;
115 case S_IFLNK:
116 inode->i_op = &page_symlink_inode_operations;
117 inode_nohighmem(inode);
118 inode->i_data.a_ops = &cramfs_aops;
119 break;
120 default:
121 init_special_inode(inode, cramfs_inode->mode,
122 old_decode_dev(cramfs_inode->size));
123 }
124
125 inode->i_mode = cramfs_inode->mode;
126 i_uid_write(inode, cramfs_inode->uid);
127 i_gid_write(inode, cramfs_inode->gid);
128
129 /* if the lower 2 bits are zero, the inode contains data */
130 if (!(inode->i_ino & 3)) {
131 inode->i_size = cramfs_inode->size;
132 inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;
133 }
134
135 /* Struct copy intentional */
136 inode->i_mtime = inode->i_atime = inode->i_ctime = zerotime;
137 /* inode->i_nlink is left 1 - arguably wrong for directories,
138 but it's the best we can do without reading the directory
139 contents. 1 yields the right result in GNU find, even
140 without -noleaf option. */
141
142 unlock_new_inode(inode);
143
144 return inode;
145}
146
147/*
148 * We have our own block cache: don't fill up the buffer cache
149 * with the rom-image, because the way the filesystem is set
150 * up the accesses should be fairly regular and cached in the
151 * page cache and dentry tree anyway..
152 *
153 * This also acts as a way to guarantee contiguous areas of up to
154 * BLKS_PER_BUF*PAGE_SIZE, so that the caller doesn't need to
155 * worry about end-of-buffer issues even when decompressing a full
156 * page cache.
157 *
158 * Note: This is all optimized away at compile time when
159 * CONFIG_CRAMFS_BLOCKDEV=n.
160 */
161#define READ_BUFFERS (2)
162/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */
163#define NEXT_BUFFER(_ix) ((_ix) ^ 1)
164
165/*
166 * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"
167 * data that takes up more space than the original and with unlucky
168 * alignment.
169 */
170#define BLKS_PER_BUF_SHIFT (2)
171#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)
172#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_SIZE)
173
174static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];
175static unsigned buffer_blocknr[READ_BUFFERS];
176static struct super_block *buffer_dev[READ_BUFFERS];
177static int next_buffer;
178
179/*
180 * Populate our block cache and return a pointer to it.
181 */
182static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
183 unsigned int len)
184{
185 struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
186 struct page *pages[BLKS_PER_BUF];
187 unsigned i, blocknr, buffer;
188 unsigned long devsize;
189 char *data;
190
191 if (!len)
192 return NULL;
193 blocknr = offset >> PAGE_SHIFT;
194 offset &= PAGE_SIZE - 1;
195
196 /* Check if an existing buffer already has the data.. */
197 for (i = 0; i < READ_BUFFERS; i++) {
198 unsigned int blk_offset;
199
200 if (buffer_dev[i] != sb)
201 continue;
202 if (blocknr < buffer_blocknr[i])
203 continue;
204 blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT;
205 blk_offset += offset;
206 if (blk_offset > BUFFER_SIZE ||
207 blk_offset + len > BUFFER_SIZE)
208 continue;
209 return read_buffers[i] + blk_offset;
210 }
211
212 devsize = mapping->host->i_size >> PAGE_SHIFT;
213
214 /* Ok, read in BLKS_PER_BUF pages completely first. */
215 for (i = 0; i < BLKS_PER_BUF; i++) {
216 struct page *page = NULL;
217
218 if (blocknr + i < devsize) {
219 page = read_mapping_page(mapping, blocknr + i, NULL);
220 /* synchronous error? */
221 if (IS_ERR(page))
222 page = NULL;
223 }
224 pages[i] = page;
225 }
226
227 for (i = 0; i < BLKS_PER_BUF; i++) {
228 struct page *page = pages[i];
229
230 if (page) {
231 wait_on_page_locked(page);
232 if (!PageUptodate(page)) {
233 /* asynchronous error */
234 put_page(page);
235 pages[i] = NULL;
236 }
237 }
238 }
239
240 buffer = next_buffer;
241 next_buffer = NEXT_BUFFER(buffer);
242 buffer_blocknr[buffer] = blocknr;
243 buffer_dev[buffer] = sb;
244
245 data = read_buffers[buffer];
246 for (i = 0; i < BLKS_PER_BUF; i++) {
247 struct page *page = pages[i];
248
249 if (page) {
250 memcpy(data, kmap(page), PAGE_SIZE);
251 kunmap(page);
252 put_page(page);
253 } else
254 memset(data, 0, PAGE_SIZE);
255 data += PAGE_SIZE;
256 }
257 return read_buffers[buffer] + offset;
258}
259
260/*
261 * Return a pointer to the linearly addressed cramfs image in memory.
262 */
263static void *cramfs_direct_read(struct super_block *sb, unsigned int offset,
264 unsigned int len)
265{
266 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
267
268 if (!len)
269 return NULL;
270 if (len > sbi->size || offset > sbi->size - len)
271 return page_address(ZERO_PAGE(0));
272 return sbi->linear_virt_addr + offset;
273}
274
275/*
276 * Returns a pointer to a buffer containing at least LEN bytes of
277 * filesystem starting at byte offset OFFSET into the filesystem.
278 */
279static void *cramfs_read(struct super_block *sb, unsigned int offset,
280 unsigned int len)
281{
282 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
283
284 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sbi->linear_virt_addr)
285 return cramfs_direct_read(sb, offset, len);
286 else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
287 return cramfs_blkdev_read(sb, offset, len);
288 else
289 return NULL;
290}
291
292/*
293 * For a mapping to be possible, we need a range of uncompressed and
294 * contiguous blocks. Return the offset for the first block and number of
295 * valid blocks for which that is true, or zero otherwise.
296 */
297static u32 cramfs_get_block_range(struct inode *inode, u32 pgoff, u32 *pages)
298{
299 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
300 int i;
301 u32 *blockptrs, first_block_addr;
302
303 /*
304 * We can dereference memory directly here as this code may be
305 * reached only when there is a direct filesystem image mapping
306 * available in memory.
307 */
308 blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode) + pgoff * 4);
309 first_block_addr = blockptrs[0] & ~CRAMFS_BLK_FLAGS;
310 i = 0;
311 do {
312 u32 block_off = i * (PAGE_SIZE >> CRAMFS_BLK_DIRECT_PTR_SHIFT);
313 u32 expect = (first_block_addr + block_off) |
314 CRAMFS_BLK_FLAG_DIRECT_PTR |
315 CRAMFS_BLK_FLAG_UNCOMPRESSED;
316 if (blockptrs[i] != expect) {
317 pr_debug("range: block %d/%d got %#x expects %#x\n",
318 pgoff+i, pgoff + *pages - 1,
319 blockptrs[i], expect);
320 if (i == 0)
321 return 0;
322 break;
323 }
324 } while (++i < *pages);
325
326 *pages = i;
327 return first_block_addr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
328}
329
330#ifdef CONFIG_MMU
331
332/*
333 * Return true if the last page of a file in the filesystem image contains
334 * some other data that doesn't belong to that file. It is assumed that the
335 * last block is CRAMFS_BLK_FLAG_DIRECT_PTR | CRAMFS_BLK_FLAG_UNCOMPRESSED
336 * (verified by cramfs_get_block_range() and directly accessible in memory.
337 */
338static bool cramfs_last_page_is_shared(struct inode *inode)
339{
340 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
341 u32 partial, last_page, blockaddr, *blockptrs;
342 char *tail_data;
343
344 partial = offset_in_page(inode->i_size);
345 if (!partial)
346 return false;
347 last_page = inode->i_size >> PAGE_SHIFT;
348 blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode));
349 blockaddr = blockptrs[last_page] & ~CRAMFS_BLK_FLAGS;
350 blockaddr <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
351 tail_data = sbi->linear_virt_addr + blockaddr + partial;
352 return memchr_inv(tail_data, 0, PAGE_SIZE - partial) ? true : false;
353}
354
355static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
356{
357 struct inode *inode = file_inode(file);
358 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
359 unsigned int pages, max_pages, offset;
360 unsigned long address, pgoff = vma->vm_pgoff;
361 char *bailout_reason;
362 int ret;
363
364 ret = generic_file_readonly_mmap(file, vma);
365 if (ret)
366 return ret;
367
368 /*
369 * Now try to pre-populate ptes for this vma with a direct
370 * mapping avoiding memory allocation when possible.
371 */
372
373 /* Could COW work here? */
374 bailout_reason = "vma is writable";
375 if (vma->vm_flags & VM_WRITE)
376 goto bailout;
377
378 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
379 bailout_reason = "beyond file limit";
380 if (pgoff >= max_pages)
381 goto bailout;
382 pages = min(vma_pages(vma), max_pages - pgoff);
383
384 offset = cramfs_get_block_range(inode, pgoff, &pages);
385 bailout_reason = "unsuitable block layout";
386 if (!offset)
387 goto bailout;
388 address = sbi->linear_phys_addr + offset;
389 bailout_reason = "data is not page aligned";
390 if (!PAGE_ALIGNED(address))
391 goto bailout;
392
393 /* Don't map the last page if it contains some other data */
394 if (pgoff + pages == max_pages && cramfs_last_page_is_shared(inode)) {
395 pr_debug("mmap: %s: last page is shared\n",
396 file_dentry(file)->d_name.name);
397 pages--;
398 }
399
400 if (!pages) {
401 bailout_reason = "no suitable block remaining";
402 goto bailout;
403 }
404
405 if (pages == vma_pages(vma)) {
406 /*
407 * The entire vma is mappable. remap_pfn_range() will
408 * make it distinguishable from a non-direct mapping
409 * in /proc/<pid>/maps by substituting the file offset
410 * with the actual physical address.
411 */
412 ret = remap_pfn_range(vma, vma->vm_start, address >> PAGE_SHIFT,
413 pages * PAGE_SIZE, vma->vm_page_prot);
414 } else {
415 /*
416 * Let's create a mixed map if we can't map it all.
417 * The normal paging machinery will take care of the
418 * unpopulated ptes via cramfs_readpage().
419 */
420 int i;
421 vma->vm_flags |= VM_MIXEDMAP;
422 for (i = 0; i < pages && !ret; i++) {
423 vm_fault_t vmf;
424 unsigned long off = i * PAGE_SIZE;
425 pfn_t pfn = phys_to_pfn_t(address + off, PFN_DEV);
426 vmf = vmf_insert_mixed(vma, vma->vm_start + off, pfn);
427 if (vmf & VM_FAULT_ERROR)
428 ret = vm_fault_to_errno(vmf, 0);
429 }
430 }
431
432 if (!ret)
433 pr_debug("mapped %s[%lu] at 0x%08lx (%u/%lu pages) "
434 "to vma 0x%08lx, page_prot 0x%llx\n",
435 file_dentry(file)->d_name.name, pgoff,
436 address, pages, vma_pages(vma), vma->vm_start,
437 (unsigned long long)pgprot_val(vma->vm_page_prot));
438 return ret;
439
440bailout:
441 pr_debug("%s[%lu]: direct mmap impossible: %s\n",
442 file_dentry(file)->d_name.name, pgoff, bailout_reason);
443 /* Didn't manage any direct map, but normal paging is still possible */
444 return 0;
445}
446
447#else /* CONFIG_MMU */
448
449static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
450{
451 return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS;
452}
453
454static unsigned long cramfs_physmem_get_unmapped_area(struct file *file,
455 unsigned long addr, unsigned long len,
456 unsigned long pgoff, unsigned long flags)
457{
458 struct inode *inode = file_inode(file);
459 struct super_block *sb = inode->i_sb;
460 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
461 unsigned int pages, block_pages, max_pages, offset;
462
463 pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
464 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
465 if (pgoff >= max_pages || pages > max_pages - pgoff)
466 return -EINVAL;
467 block_pages = pages;
468 offset = cramfs_get_block_range(inode, pgoff, &block_pages);
469 if (!offset || block_pages != pages)
470 return -ENOSYS;
471 addr = sbi->linear_phys_addr + offset;
472 pr_debug("get_unmapped for %s ofs %#lx siz %lu at 0x%08lx\n",
473 file_dentry(file)->d_name.name, pgoff*PAGE_SIZE, len, addr);
474 return addr;
475}
476
477static unsigned int cramfs_physmem_mmap_capabilities(struct file *file)
478{
479 return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT |
480 NOMMU_MAP_READ | NOMMU_MAP_EXEC;
481}
482
483#endif /* CONFIG_MMU */
484
485static const struct file_operations cramfs_physmem_fops = {
486 .llseek = generic_file_llseek,
487 .read_iter = generic_file_read_iter,
488 .splice_read = generic_file_splice_read,
489 .mmap = cramfs_physmem_mmap,
490#ifndef CONFIG_MMU
491 .get_unmapped_area = cramfs_physmem_get_unmapped_area,
492 .mmap_capabilities = cramfs_physmem_mmap_capabilities,
493#endif
494};
495
496static void cramfs_kill_sb(struct super_block *sb)
497{
498 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
499
500 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sb->s_mtd) {
501 if (sbi && sbi->mtd_point_size)
502 mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size);
503 kill_mtd_super(sb);
504 } else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) {
505 kill_block_super(sb);
506 }
507 kfree(sbi);
508}
509
510static int cramfs_reconfigure(struct fs_context *fc)
511{
512 sync_filesystem(fc->root->d_sb);
513 fc->sb_flags |= SB_RDONLY;
514 return 0;
515}
516
517static int cramfs_read_super(struct super_block *sb, struct fs_context *fc,
518 struct cramfs_super *super)
519{
520 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);
521 unsigned long root_offset;
522 bool silent = fc->sb_flags & SB_SILENT;
523
524 /* We don't know the real size yet */
525 sbi->size = PAGE_SIZE;
526
527 /* Read the first block and get the superblock from it */
528 mutex_lock(&read_mutex);
529 memcpy(super, cramfs_read(sb, 0, sizeof(*super)), sizeof(*super));
530 mutex_unlock(&read_mutex);
531
532 /* Do sanity checks on the superblock */
533 if (super->magic != CRAMFS_MAGIC) {
534 /* check for wrong endianness */
535 if (super->magic == CRAMFS_MAGIC_WEND) {
536 if (!silent)
537 errorf(fc, "cramfs: wrong endianness");
538 return -EINVAL;
539 }
540
541 /* check at 512 byte offset */
542 mutex_lock(&read_mutex);
543 memcpy(super,
544 cramfs_read(sb, 512, sizeof(*super)),
545 sizeof(*super));
546 mutex_unlock(&read_mutex);
547 if (super->magic != CRAMFS_MAGIC) {
548 if (super->magic == CRAMFS_MAGIC_WEND && !silent)
549 errorf(fc, "cramfs: wrong endianness");
550 else if (!silent)
551 errorf(fc, "cramfs: wrong magic");
552 return -EINVAL;
553 }
554 }
555
556 /* get feature flags first */
557 if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) {
558 errorf(fc, "cramfs: unsupported filesystem features");
559 return -EINVAL;
560 }
561
562 /* Check that the root inode is in a sane state */
563 if (!S_ISDIR(super->root.mode)) {
564 errorf(fc, "cramfs: root is not a directory");
565 return -EINVAL;
566 }
567 /* correct strange, hard-coded permissions of mkcramfs */
568 super->root.mode |= 0555;
569
570 root_offset = super->root.offset << 2;
571 if (super->flags & CRAMFS_FLAG_FSID_VERSION_2) {
572 sbi->size = super->size;
573 sbi->blocks = super->fsid.blocks;
574 sbi->files = super->fsid.files;
575 } else {
576 sbi->size = 1<<28;
577 sbi->blocks = 0;
578 sbi->files = 0;
579 }
580 sbi->magic = super->magic;
581 sbi->flags = super->flags;
582 if (root_offset == 0)
583 infof(fc, "cramfs: empty filesystem");
584 else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
585 ((root_offset != sizeof(struct cramfs_super)) &&
586 (root_offset != 512 + sizeof(struct cramfs_super))))
587 {
588 errorf(fc, "cramfs: bad root offset %lu", root_offset);
589 return -EINVAL;
590 }
591
592 return 0;
593}
594
595static int cramfs_finalize_super(struct super_block *sb,
596 struct cramfs_inode *cramfs_root)
597{
598 struct inode *root;
599
600 /* Set it all up.. */
601 sb->s_flags |= SB_RDONLY;
602 sb->s_time_min = 0;
603 sb->s_time_max = 0;
604 sb->s_op = &cramfs_ops;
605 root = get_cramfs_inode(sb, cramfs_root, 0);
606 if (IS_ERR(root))
607 return PTR_ERR(root);
608 sb->s_root = d_make_root(root);
609 if (!sb->s_root)
610 return -ENOMEM;
611 return 0;
612}
613
614static int cramfs_blkdev_fill_super(struct super_block *sb, struct fs_context *fc)
615{
616 struct cramfs_sb_info *sbi;
617 struct cramfs_super super;
618 int i, err;
619
620 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
621 if (!sbi)
622 return -ENOMEM;
623 sb->s_fs_info = sbi;
624
625 /* Invalidate the read buffers on mount: think disk change.. */
626 for (i = 0; i < READ_BUFFERS; i++)
627 buffer_blocknr[i] = -1;
628
629 err = cramfs_read_super(sb, fc, &super);
630 if (err)
631 return err;
632 return cramfs_finalize_super(sb, &super.root);
633}
634
635static int cramfs_mtd_fill_super(struct super_block *sb, struct fs_context *fc)
636{
637 struct cramfs_sb_info *sbi;
638 struct cramfs_super super;
639 int err;
640
641 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);
642 if (!sbi)
643 return -ENOMEM;
644 sb->s_fs_info = sbi;
645
646 /* Map only one page for now. Will remap it when fs size is known. */
647 err = mtd_point(sb->s_mtd, 0, PAGE_SIZE, &sbi->mtd_point_size,
648 &sbi->linear_virt_addr, &sbi->linear_phys_addr);
649 if (err || sbi->mtd_point_size != PAGE_SIZE) {
650 pr_err("unable to get direct memory access to mtd:%s\n",
651 sb->s_mtd->name);
652 return err ? : -ENODATA;
653 }
654
655 pr_info("checking physical address %pap for linear cramfs image\n",
656 &sbi->linear_phys_addr);
657 err = cramfs_read_super(sb, fc, &super);
658 if (err)
659 return err;
660
661 /* Remap the whole filesystem now */
662 pr_info("linear cramfs image on mtd:%s appears to be %lu KB in size\n",
663 sb->s_mtd->name, sbi->size/1024);
664 mtd_unpoint(sb->s_mtd, 0, PAGE_SIZE);
665 err = mtd_point(sb->s_mtd, 0, sbi->size, &sbi->mtd_point_size,
666 &sbi->linear_virt_addr, &sbi->linear_phys_addr);
667 if (err || sbi->mtd_point_size != sbi->size) {
668 pr_err("unable to get direct memory access to mtd:%s\n",
669 sb->s_mtd->name);
670 return err ? : -ENODATA;
671 }
672
673 return cramfs_finalize_super(sb, &super.root);
674}
675
676static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)
677{
678 struct super_block *sb = dentry->d_sb;
679 u64 id = 0;
680
681 if (sb->s_bdev)
682 id = huge_encode_dev(sb->s_bdev->bd_dev);
683 else if (sb->s_dev)
684 id = huge_encode_dev(sb->s_dev);
685
686 buf->f_type = CRAMFS_MAGIC;
687 buf->f_bsize = PAGE_SIZE;
688 buf->f_blocks = CRAMFS_SB(sb)->blocks;
689 buf->f_bfree = 0;
690 buf->f_bavail = 0;
691 buf->f_files = CRAMFS_SB(sb)->files;
692 buf->f_ffree = 0;
693 buf->f_fsid.val[0] = (u32)id;
694 buf->f_fsid.val[1] = (u32)(id >> 32);
695 buf->f_namelen = CRAMFS_MAXPATHLEN;
696 return 0;
697}
698
699/*
700 * Read a cramfs directory entry.
701 */
702static int cramfs_readdir(struct file *file, struct dir_context *ctx)
703{
704 struct inode *inode = file_inode(file);
705 struct super_block *sb = inode->i_sb;
706 char *buf;
707 unsigned int offset;
708
709 /* Offset within the thing. */
710 if (ctx->pos >= inode->i_size)
711 return 0;
712 offset = ctx->pos;
713 /* Directory entries are always 4-byte aligned */
714 if (offset & 3)
715 return -EINVAL;
716
717 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);
718 if (!buf)
719 return -ENOMEM;
720
721 while (offset < inode->i_size) {
722 struct cramfs_inode *de;
723 unsigned long nextoffset;
724 char *name;
725 ino_t ino;
726 umode_t mode;
727 int namelen;
728
729 mutex_lock(&read_mutex);
730 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);
731 name = (char *)(de+1);
732
733 /*
734 * Namelengths on disk are shifted by two
735 * and the name padded out to 4-byte boundaries
736 * with zeroes.
737 */
738 namelen = de->namelen << 2;
739 memcpy(buf, name, namelen);
740 ino = cramino(de, OFFSET(inode) + offset);
741 mode = de->mode;
742 mutex_unlock(&read_mutex);
743 nextoffset = offset + sizeof(*de) + namelen;
744 for (;;) {
745 if (!namelen) {
746 kfree(buf);
747 return -EIO;
748 }
749 if (buf[namelen-1])
750 break;
751 namelen--;
752 }
753 if (!dir_emit(ctx, buf, namelen, ino, mode >> 12))
754 break;
755
756 ctx->pos = offset = nextoffset;
757 }
758 kfree(buf);
759 return 0;
760}
761
762/*
763 * Lookup and fill in the inode data..
764 */
765static struct dentry *cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
766{
767 unsigned int offset = 0;
768 struct inode *inode = NULL;
769 int sorted;
770
771 mutex_lock(&read_mutex);
772 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;
773 while (offset < dir->i_size) {
774 struct cramfs_inode *de;
775 char *name;
776 int namelen, retval;
777 int dir_off = OFFSET(dir) + offset;
778
779 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);
780 name = (char *)(de+1);
781
782 /* Try to take advantage of sorted directories */
783 if (sorted && (dentry->d_name.name[0] < name[0]))
784 break;
785
786 namelen = de->namelen << 2;
787 offset += sizeof(*de) + namelen;
788
789 /* Quick check that the name is roughly the right length */
790 if (((dentry->d_name.len + 3) & ~3) != namelen)
791 continue;
792
793 for (;;) {
794 if (!namelen) {
795 inode = ERR_PTR(-EIO);
796 goto out;
797 }
798 if (name[namelen-1])
799 break;
800 namelen--;
801 }
802 if (namelen != dentry->d_name.len)
803 continue;
804 retval = memcmp(dentry->d_name.name, name, namelen);
805 if (retval > 0)
806 continue;
807 if (!retval) {
808 inode = get_cramfs_inode(dir->i_sb, de, dir_off);
809 break;
810 }
811 /* else (retval < 0) */
812 if (sorted)
813 break;
814 }
815out:
816 mutex_unlock(&read_mutex);
817 return d_splice_alias(inode, dentry);
818}
819
820static int cramfs_readpage(struct file *file, struct page *page)
821{
822 struct inode *inode = page->mapping->host;
823 u32 maxblock;
824 int bytes_filled;
825 void *pgdata;
826
827 maxblock = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
828 bytes_filled = 0;
829 pgdata = kmap(page);
830
831 if (page->index < maxblock) {
832 struct super_block *sb = inode->i_sb;
833 u32 blkptr_offset = OFFSET(inode) + page->index * 4;
834 u32 block_ptr, block_start, block_len;
835 bool uncompressed, direct;
836
837 mutex_lock(&read_mutex);
838 block_ptr = *(u32 *) cramfs_read(sb, blkptr_offset, 4);
839 uncompressed = (block_ptr & CRAMFS_BLK_FLAG_UNCOMPRESSED);
840 direct = (block_ptr & CRAMFS_BLK_FLAG_DIRECT_PTR);
841 block_ptr &= ~CRAMFS_BLK_FLAGS;
842
843 if (direct) {
844 /*
845 * The block pointer is an absolute start pointer,
846 * shifted by 2 bits. The size is included in the
847 * first 2 bytes of the data block when compressed,
848 * or PAGE_SIZE otherwise.
849 */
850 block_start = block_ptr << CRAMFS_BLK_DIRECT_PTR_SHIFT;
851 if (uncompressed) {
852 block_len = PAGE_SIZE;
853 /* if last block: cap to file length */
854 if (page->index == maxblock - 1)
855 block_len =
856 offset_in_page(inode->i_size);
857 } else {
858 block_len = *(u16 *)
859 cramfs_read(sb, block_start, 2);
860 block_start += 2;
861 }
862 } else {
863 /*
864 * The block pointer indicates one past the end of
865 * the current block (start of next block). If this
866 * is the first block then it starts where the block
867 * pointer table ends, otherwise its start comes
868 * from the previous block's pointer.
869 */
870 block_start = OFFSET(inode) + maxblock * 4;
871 if (page->index)
872 block_start = *(u32 *)
873 cramfs_read(sb, blkptr_offset - 4, 4);
874 /* Beware... previous ptr might be a direct ptr */
875 if (unlikely(block_start & CRAMFS_BLK_FLAG_DIRECT_PTR)) {
876 /* See comments on earlier code. */
877 u32 prev_start = block_start;
878 block_start = prev_start & ~CRAMFS_BLK_FLAGS;
879 block_start <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;
880 if (prev_start & CRAMFS_BLK_FLAG_UNCOMPRESSED) {
881 block_start += PAGE_SIZE;
882 } else {
883 block_len = *(u16 *)
884 cramfs_read(sb, block_start, 2);
885 block_start += 2 + block_len;
886 }
887 }
888 block_start &= ~CRAMFS_BLK_FLAGS;
889 block_len = block_ptr - block_start;
890 }
891
892 if (block_len == 0)
893 ; /* hole */
894 else if (unlikely(block_len > 2*PAGE_SIZE ||
895 (uncompressed && block_len > PAGE_SIZE))) {
896 mutex_unlock(&read_mutex);
897 pr_err("bad data blocksize %u\n", block_len);
898 goto err;
899 } else if (uncompressed) {
900 memcpy(pgdata,
901 cramfs_read(sb, block_start, block_len),
902 block_len);
903 bytes_filled = block_len;
904 } else {
905 bytes_filled = cramfs_uncompress_block(pgdata,
906 PAGE_SIZE,
907 cramfs_read(sb, block_start, block_len),
908 block_len);
909 }
910 mutex_unlock(&read_mutex);
911 if (unlikely(bytes_filled < 0))
912 goto err;
913 }
914
915 memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled);
916 flush_dcache_page(page);
917 kunmap(page);
918 SetPageUptodate(page);
919 unlock_page(page);
920 return 0;
921
922err:
923 kunmap(page);
924 ClearPageUptodate(page);
925 SetPageError(page);
926 unlock_page(page);
927 return 0;
928}
929
930static const struct address_space_operations cramfs_aops = {
931 .readpage = cramfs_readpage
932};
933
934/*
935 * Our operations:
936 */
937
938/*
939 * A directory can only readdir
940 */
941static const struct file_operations cramfs_directory_operations = {
942 .llseek = generic_file_llseek,
943 .read = generic_read_dir,
944 .iterate_shared = cramfs_readdir,
945};
946
947static const struct inode_operations cramfs_dir_inode_operations = {
948 .lookup = cramfs_lookup,
949};
950
951static const struct super_operations cramfs_ops = {
952 .statfs = cramfs_statfs,
953};
954
955static int cramfs_get_tree(struct fs_context *fc)
956{
957 int ret = -ENOPROTOOPT;
958
959 if (IS_ENABLED(CONFIG_CRAMFS_MTD)) {
960 ret = get_tree_mtd(fc, cramfs_mtd_fill_super);
961 if (!ret)
962 return 0;
963 }
964 if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))
965 ret = get_tree_bdev(fc, cramfs_blkdev_fill_super);
966 return ret;
967}
968
969static const struct fs_context_operations cramfs_context_ops = {
970 .get_tree = cramfs_get_tree,
971 .reconfigure = cramfs_reconfigure,
972};
973
974/*
975 * Set up the filesystem mount context.
976 */
977static int cramfs_init_fs_context(struct fs_context *fc)
978{
979 fc->ops = &cramfs_context_ops;
980 return 0;
981}
982
983static struct file_system_type cramfs_fs_type = {
984 .owner = THIS_MODULE,
985 .name = "cramfs",
986 .init_fs_context = cramfs_init_fs_context,
987 .kill_sb = cramfs_kill_sb,
988 .fs_flags = FS_REQUIRES_DEV,
989};
990MODULE_ALIAS_FS("cramfs");
991
992static int __init init_cramfs_fs(void)
993{
994 int rv;
995
996 rv = cramfs_uncompress_init();
997 if (rv < 0)
998 return rv;
999 rv = register_filesystem(&cramfs_fs_type);
1000 if (rv < 0)
1001 cramfs_uncompress_exit();
1002 return rv;
1003}
1004
1005static void __exit exit_cramfs_fs(void)
1006{
1007 cramfs_uncompress_exit();
1008 unregister_filesystem(&cramfs_fs_type);
1009}
1010
1011module_init(init_cramfs_fs)
1012module_exit(exit_cramfs_fs)
1013MODULE_LICENSE("GPL");