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 */ 39 struct 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 50 static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb) 51 { 52 return sb->s_fs_info; 53 } 54 55 static const struct super_operations cramfs_ops; 56 static const struct inode_operations cramfs_dir_inode_operations; 57 static const struct file_operations cramfs_directory_operations; 58 static const struct file_operations cramfs_physmem_fops; 59 static const struct address_space_operations cramfs_aops; 60 61 static 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 67 static 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 90 static 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) 173 174 static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE]; 175 static unsigned buffer_blocknr[READ_BUFFERS]; 176 static struct super_block *buffer_dev[READ_BUFFERS]; 177 static int next_buffer; 178 179 /* 180 * Populate our block cache and return a pointer to it. 181 */ 182 static 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 */ 263 static 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 */ 279 static 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 */ 297 static 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 */ 338 static 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 } 354 355 static 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; 439 440 bailout: 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 */ 448 449 static 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 } 453 454 static 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 } 476 477 static 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 */ 484 485 static 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 }; 495 496 static 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 } 509 510 static 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 } 516 517 static 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 } 594 595 static 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 } 613 614 static 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 } 634 635 static 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 } 675 676 static 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 */ 702 static 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 */ 765 static 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 } 815 out: 816 mutex_unlock(&read_mutex); 817 return d_splice_alias(inode, dentry); 818 } 819 820 static 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; 921 922 err: 923 kunmap(page); 924 ClearPageUptodate(page); 925 SetPageError(page); 926 unlock_page(page); 927 return 0; 928 } 929 930 static 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 */ 941 static const struct file_operations cramfs_directory_operations = { 942 .llseek = generic_file_llseek, 943 .read = generic_read_dir, 944 .iterate_shared = cramfs_readdir, 945 }; 946 947 static const struct inode_operations cramfs_dir_inode_operations = { 948 .lookup = cramfs_lookup, 949 }; 950 951 static const struct super_operations cramfs_ops = { 952 .statfs = cramfs_statfs, 953 }; 954 955 static 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 } 968 969 static 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 */ 977 static int cramfs_init_fs_context(struct fs_context *fc) 978 { 979 fc->ops = &cramfs_context_ops; 980 return 0; 981 } 982 983 static 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 }; 990 MODULE_ALIAS_FS("cramfs"); 991 992 static 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 1005 static void __exit exit_cramfs_fs(void) 1006 { 1007 cramfs_uncompress_exit(); 1008 unregister_filesystem(&cramfs_fs_type); 1009 } 1010 1011 module_init(init_cramfs_fs) 1012 module_exit(exit_cramfs_fs) 1013 MODULE_LICENSE("GPL"); 1014