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