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 file_ra_state ra; 187 struct page *pages[BLKS_PER_BUF]; 188 unsigned i, blocknr, buffer; 189 unsigned long devsize; 190 char *data; 191 192 if (!len) 193 return NULL; 194 blocknr = offset >> PAGE_SHIFT; 195 offset &= PAGE_SIZE - 1; 196 197 /* Check if an existing buffer already has the data.. */ 198 for (i = 0; i < READ_BUFFERS; i++) { 199 unsigned int blk_offset; 200 201 if (buffer_dev[i] != sb) 202 continue; 203 if (blocknr < buffer_blocknr[i]) 204 continue; 205 blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT; 206 blk_offset += offset; 207 if (blk_offset > BUFFER_SIZE || 208 blk_offset + len > BUFFER_SIZE) 209 continue; 210 return read_buffers[i] + blk_offset; 211 } 212 213 devsize = bdev_nr_bytes(sb->s_bdev) >> PAGE_SHIFT; 214 215 /* Ok, read in BLKS_PER_BUF pages completely first. */ 216 file_ra_state_init(&ra, mapping); 217 page_cache_sync_readahead(mapping, &ra, NULL, blocknr, BLKS_PER_BUF); 218 219 for (i = 0; i < BLKS_PER_BUF; i++) { 220 struct page *page = NULL; 221 222 if (blocknr + i < devsize) { 223 page = read_mapping_page(mapping, blocknr + i, NULL); 224 /* synchronous error? */ 225 if (IS_ERR(page)) 226 page = NULL; 227 } 228 pages[i] = page; 229 } 230 231 buffer = next_buffer; 232 next_buffer = NEXT_BUFFER(buffer); 233 buffer_blocknr[buffer] = blocknr; 234 buffer_dev[buffer] = sb; 235 236 data = read_buffers[buffer]; 237 for (i = 0; i < BLKS_PER_BUF; i++) { 238 struct page *page = pages[i]; 239 240 if (page) { 241 memcpy(data, kmap(page), PAGE_SIZE); 242 kunmap(page); 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 */ 254 static 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 */ 270 static 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 */ 288 static 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 */ 329 static 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 } 345 346 static 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 vma->vm_flags |= 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; 428 429 bailout: 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 */ 437 438 static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma) 439 { 440 return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS; 441 } 442 443 static 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 } 465 466 static 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 */ 473 474 static const struct file_operations cramfs_physmem_fops = { 475 .llseek = generic_file_llseek, 476 .read_iter = generic_file_read_iter, 477 .splice_read = generic_file_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 }; 484 485 static void cramfs_kill_sb(struct super_block *sb) 486 { 487 struct cramfs_sb_info *sbi = CRAMFS_SB(sb); 488 489 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sb->s_mtd) { 490 if (sbi && sbi->mtd_point_size) 491 mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size); 492 kill_mtd_super(sb); 493 } else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) { 494 kill_block_super(sb); 495 } 496 kfree(sbi); 497 } 498 499 static int cramfs_reconfigure(struct fs_context *fc) 500 { 501 sync_filesystem(fc->root->d_sb); 502 fc->sb_flags |= SB_RDONLY; 503 return 0; 504 } 505 506 static int cramfs_read_super(struct super_block *sb, struct fs_context *fc, 507 struct cramfs_super *super) 508 { 509 struct cramfs_sb_info *sbi = CRAMFS_SB(sb); 510 unsigned long root_offset; 511 bool silent = fc->sb_flags & SB_SILENT; 512 513 /* We don't know the real size yet */ 514 sbi->size = PAGE_SIZE; 515 516 /* Read the first block and get the superblock from it */ 517 mutex_lock(&read_mutex); 518 memcpy(super, cramfs_read(sb, 0, sizeof(*super)), sizeof(*super)); 519 mutex_unlock(&read_mutex); 520 521 /* Do sanity checks on the superblock */ 522 if (super->magic != CRAMFS_MAGIC) { 523 /* check for wrong endianness */ 524 if (super->magic == CRAMFS_MAGIC_WEND) { 525 if (!silent) 526 errorfc(fc, "wrong endianness"); 527 return -EINVAL; 528 } 529 530 /* check at 512 byte offset */ 531 mutex_lock(&read_mutex); 532 memcpy(super, 533 cramfs_read(sb, 512, sizeof(*super)), 534 sizeof(*super)); 535 mutex_unlock(&read_mutex); 536 if (super->magic != CRAMFS_MAGIC) { 537 if (super->magic == CRAMFS_MAGIC_WEND && !silent) 538 errorfc(fc, "wrong endianness"); 539 else if (!silent) 540 errorfc(fc, "wrong magic"); 541 return -EINVAL; 542 } 543 } 544 545 /* get feature flags first */ 546 if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) { 547 errorfc(fc, "unsupported filesystem features"); 548 return -EINVAL; 549 } 550 551 /* Check that the root inode is in a sane state */ 552 if (!S_ISDIR(super->root.mode)) { 553 errorfc(fc, "root is not a directory"); 554 return -EINVAL; 555 } 556 /* correct strange, hard-coded permissions of mkcramfs */ 557 super->root.mode |= 0555; 558 559 root_offset = super->root.offset << 2; 560 if (super->flags & CRAMFS_FLAG_FSID_VERSION_2) { 561 sbi->size = super->size; 562 sbi->blocks = super->fsid.blocks; 563 sbi->files = super->fsid.files; 564 } else { 565 sbi->size = 1<<28; 566 sbi->blocks = 0; 567 sbi->files = 0; 568 } 569 sbi->magic = super->magic; 570 sbi->flags = super->flags; 571 if (root_offset == 0) 572 infofc(fc, "empty filesystem"); 573 else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) && 574 ((root_offset != sizeof(struct cramfs_super)) && 575 (root_offset != 512 + sizeof(struct cramfs_super)))) 576 { 577 errorfc(fc, "bad root offset %lu", root_offset); 578 return -EINVAL; 579 } 580 581 return 0; 582 } 583 584 static int cramfs_finalize_super(struct super_block *sb, 585 struct cramfs_inode *cramfs_root) 586 { 587 struct inode *root; 588 589 /* Set it all up.. */ 590 sb->s_flags |= SB_RDONLY; 591 sb->s_time_min = 0; 592 sb->s_time_max = 0; 593 sb->s_op = &cramfs_ops; 594 root = get_cramfs_inode(sb, cramfs_root, 0); 595 if (IS_ERR(root)) 596 return PTR_ERR(root); 597 sb->s_root = d_make_root(root); 598 if (!sb->s_root) 599 return -ENOMEM; 600 return 0; 601 } 602 603 static int cramfs_blkdev_fill_super(struct super_block *sb, struct fs_context *fc) 604 { 605 struct cramfs_sb_info *sbi; 606 struct cramfs_super super; 607 int i, err; 608 609 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL); 610 if (!sbi) 611 return -ENOMEM; 612 sb->s_fs_info = sbi; 613 614 /* Invalidate the read buffers on mount: think disk change.. */ 615 for (i = 0; i < READ_BUFFERS; i++) 616 buffer_blocknr[i] = -1; 617 618 err = cramfs_read_super(sb, fc, &super); 619 if (err) 620 return err; 621 return cramfs_finalize_super(sb, &super.root); 622 } 623 624 static int cramfs_mtd_fill_super(struct super_block *sb, struct fs_context *fc) 625 { 626 struct cramfs_sb_info *sbi; 627 struct cramfs_super super; 628 int err; 629 630 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL); 631 if (!sbi) 632 return -ENOMEM; 633 sb->s_fs_info = sbi; 634 635 /* Map only one page for now. Will remap it when fs size is known. */ 636 err = mtd_point(sb->s_mtd, 0, PAGE_SIZE, &sbi->mtd_point_size, 637 &sbi->linear_virt_addr, &sbi->linear_phys_addr); 638 if (err || sbi->mtd_point_size != PAGE_SIZE) { 639 pr_err("unable to get direct memory access to mtd:%s\n", 640 sb->s_mtd->name); 641 return err ? : -ENODATA; 642 } 643 644 pr_info("checking physical address %pap for linear cramfs image\n", 645 &sbi->linear_phys_addr); 646 err = cramfs_read_super(sb, fc, &super); 647 if (err) 648 return err; 649 650 /* Remap the whole filesystem now */ 651 pr_info("linear cramfs image on mtd:%s appears to be %lu KB in size\n", 652 sb->s_mtd->name, sbi->size/1024); 653 mtd_unpoint(sb->s_mtd, 0, PAGE_SIZE); 654 err = mtd_point(sb->s_mtd, 0, sbi->size, &sbi->mtd_point_size, 655 &sbi->linear_virt_addr, &sbi->linear_phys_addr); 656 if (err || sbi->mtd_point_size != sbi->size) { 657 pr_err("unable to get direct memory access to mtd:%s\n", 658 sb->s_mtd->name); 659 return err ? : -ENODATA; 660 } 661 662 return cramfs_finalize_super(sb, &super.root); 663 } 664 665 static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf) 666 { 667 struct super_block *sb = dentry->d_sb; 668 u64 id = 0; 669 670 if (sb->s_bdev) 671 id = huge_encode_dev(sb->s_bdev->bd_dev); 672 else if (sb->s_dev) 673 id = huge_encode_dev(sb->s_dev); 674 675 buf->f_type = CRAMFS_MAGIC; 676 buf->f_bsize = PAGE_SIZE; 677 buf->f_blocks = CRAMFS_SB(sb)->blocks; 678 buf->f_bfree = 0; 679 buf->f_bavail = 0; 680 buf->f_files = CRAMFS_SB(sb)->files; 681 buf->f_ffree = 0; 682 buf->f_fsid = u64_to_fsid(id); 683 buf->f_namelen = CRAMFS_MAXPATHLEN; 684 return 0; 685 } 686 687 /* 688 * Read a cramfs directory entry. 689 */ 690 static int cramfs_readdir(struct file *file, struct dir_context *ctx) 691 { 692 struct inode *inode = file_inode(file); 693 struct super_block *sb = inode->i_sb; 694 char *buf; 695 unsigned int offset; 696 697 /* Offset within the thing. */ 698 if (ctx->pos >= inode->i_size) 699 return 0; 700 offset = ctx->pos; 701 /* Directory entries are always 4-byte aligned */ 702 if (offset & 3) 703 return -EINVAL; 704 705 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL); 706 if (!buf) 707 return -ENOMEM; 708 709 while (offset < inode->i_size) { 710 struct cramfs_inode *de; 711 unsigned long nextoffset; 712 char *name; 713 ino_t ino; 714 umode_t mode; 715 int namelen; 716 717 mutex_lock(&read_mutex); 718 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN); 719 name = (char *)(de+1); 720 721 /* 722 * Namelengths on disk are shifted by two 723 * and the name padded out to 4-byte boundaries 724 * with zeroes. 725 */ 726 namelen = de->namelen << 2; 727 memcpy(buf, name, namelen); 728 ino = cramino(de, OFFSET(inode) + offset); 729 mode = de->mode; 730 mutex_unlock(&read_mutex); 731 nextoffset = offset + sizeof(*de) + namelen; 732 for (;;) { 733 if (!namelen) { 734 kfree(buf); 735 return -EIO; 736 } 737 if (buf[namelen-1]) 738 break; 739 namelen--; 740 } 741 if (!dir_emit(ctx, buf, namelen, ino, mode >> 12)) 742 break; 743 744 ctx->pos = offset = nextoffset; 745 } 746 kfree(buf); 747 return 0; 748 } 749 750 /* 751 * Lookup and fill in the inode data.. 752 */ 753 static struct dentry *cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) 754 { 755 unsigned int offset = 0; 756 struct inode *inode = NULL; 757 int sorted; 758 759 mutex_lock(&read_mutex); 760 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS; 761 while (offset < dir->i_size) { 762 struct cramfs_inode *de; 763 char *name; 764 int namelen, retval; 765 int dir_off = OFFSET(dir) + offset; 766 767 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN); 768 name = (char *)(de+1); 769 770 /* Try to take advantage of sorted directories */ 771 if (sorted && (dentry->d_name.name[0] < name[0])) 772 break; 773 774 namelen = de->namelen << 2; 775 offset += sizeof(*de) + namelen; 776 777 /* Quick check that the name is roughly the right length */ 778 if (((dentry->d_name.len + 3) & ~3) != namelen) 779 continue; 780 781 for (;;) { 782 if (!namelen) { 783 inode = ERR_PTR(-EIO); 784 goto out; 785 } 786 if (name[namelen-1]) 787 break; 788 namelen--; 789 } 790 if (namelen != dentry->d_name.len) 791 continue; 792 retval = memcmp(dentry->d_name.name, name, namelen); 793 if (retval > 0) 794 continue; 795 if (!retval) { 796 inode = get_cramfs_inode(dir->i_sb, de, dir_off); 797 break; 798 } 799 /* else (retval < 0) */ 800 if (sorted) 801 break; 802 } 803 out: 804 mutex_unlock(&read_mutex); 805 return d_splice_alias(inode, dentry); 806 } 807 808 static int cramfs_read_folio(struct file *file, struct folio *folio) 809 { 810 struct page *page = &folio->page; 811 struct inode *inode = page->mapping->host; 812 u32 maxblock; 813 int bytes_filled; 814 void *pgdata; 815 816 maxblock = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT; 817 bytes_filled = 0; 818 pgdata = kmap(page); 819 820 if (page->index < maxblock) { 821 struct super_block *sb = inode->i_sb; 822 u32 blkptr_offset = OFFSET(inode) + page->index * 4; 823 u32 block_ptr, block_start, block_len; 824 bool uncompressed, direct; 825 826 mutex_lock(&read_mutex); 827 block_ptr = *(u32 *) cramfs_read(sb, blkptr_offset, 4); 828 uncompressed = (block_ptr & CRAMFS_BLK_FLAG_UNCOMPRESSED); 829 direct = (block_ptr & CRAMFS_BLK_FLAG_DIRECT_PTR); 830 block_ptr &= ~CRAMFS_BLK_FLAGS; 831 832 if (direct) { 833 /* 834 * The block pointer is an absolute start pointer, 835 * shifted by 2 bits. The size is included in the 836 * first 2 bytes of the data block when compressed, 837 * or PAGE_SIZE otherwise. 838 */ 839 block_start = block_ptr << CRAMFS_BLK_DIRECT_PTR_SHIFT; 840 if (uncompressed) { 841 block_len = PAGE_SIZE; 842 /* if last block: cap to file length */ 843 if (page->index == maxblock - 1) 844 block_len = 845 offset_in_page(inode->i_size); 846 } else { 847 block_len = *(u16 *) 848 cramfs_read(sb, block_start, 2); 849 block_start += 2; 850 } 851 } else { 852 /* 853 * The block pointer indicates one past the end of 854 * the current block (start of next block). If this 855 * is the first block then it starts where the block 856 * pointer table ends, otherwise its start comes 857 * from the previous block's pointer. 858 */ 859 block_start = OFFSET(inode) + maxblock * 4; 860 if (page->index) 861 block_start = *(u32 *) 862 cramfs_read(sb, blkptr_offset - 4, 4); 863 /* Beware... previous ptr might be a direct ptr */ 864 if (unlikely(block_start & CRAMFS_BLK_FLAG_DIRECT_PTR)) { 865 /* See comments on earlier code. */ 866 u32 prev_start = block_start; 867 block_start = prev_start & ~CRAMFS_BLK_FLAGS; 868 block_start <<= CRAMFS_BLK_DIRECT_PTR_SHIFT; 869 if (prev_start & CRAMFS_BLK_FLAG_UNCOMPRESSED) { 870 block_start += PAGE_SIZE; 871 } else { 872 block_len = *(u16 *) 873 cramfs_read(sb, block_start, 2); 874 block_start += 2 + block_len; 875 } 876 } 877 block_start &= ~CRAMFS_BLK_FLAGS; 878 block_len = block_ptr - block_start; 879 } 880 881 if (block_len == 0) 882 ; /* hole */ 883 else if (unlikely(block_len > 2*PAGE_SIZE || 884 (uncompressed && block_len > PAGE_SIZE))) { 885 mutex_unlock(&read_mutex); 886 pr_err("bad data blocksize %u\n", block_len); 887 goto err; 888 } else if (uncompressed) { 889 memcpy(pgdata, 890 cramfs_read(sb, block_start, block_len), 891 block_len); 892 bytes_filled = block_len; 893 } else { 894 bytes_filled = cramfs_uncompress_block(pgdata, 895 PAGE_SIZE, 896 cramfs_read(sb, block_start, block_len), 897 block_len); 898 } 899 mutex_unlock(&read_mutex); 900 if (unlikely(bytes_filled < 0)) 901 goto err; 902 } 903 904 memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled); 905 flush_dcache_page(page); 906 kunmap(page); 907 SetPageUptodate(page); 908 unlock_page(page); 909 return 0; 910 911 err: 912 kunmap(page); 913 ClearPageUptodate(page); 914 SetPageError(page); 915 unlock_page(page); 916 return 0; 917 } 918 919 static const struct address_space_operations cramfs_aops = { 920 .read_folio = cramfs_read_folio 921 }; 922 923 /* 924 * Our operations: 925 */ 926 927 /* 928 * A directory can only readdir 929 */ 930 static const struct file_operations cramfs_directory_operations = { 931 .llseek = generic_file_llseek, 932 .read = generic_read_dir, 933 .iterate_shared = cramfs_readdir, 934 }; 935 936 static const struct inode_operations cramfs_dir_inode_operations = { 937 .lookup = cramfs_lookup, 938 }; 939 940 static const struct super_operations cramfs_ops = { 941 .statfs = cramfs_statfs, 942 }; 943 944 static int cramfs_get_tree(struct fs_context *fc) 945 { 946 int ret = -ENOPROTOOPT; 947 948 if (IS_ENABLED(CONFIG_CRAMFS_MTD)) { 949 ret = get_tree_mtd(fc, cramfs_mtd_fill_super); 950 if (!ret) 951 return 0; 952 } 953 if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV)) 954 ret = get_tree_bdev(fc, cramfs_blkdev_fill_super); 955 return ret; 956 } 957 958 static const struct fs_context_operations cramfs_context_ops = { 959 .get_tree = cramfs_get_tree, 960 .reconfigure = cramfs_reconfigure, 961 }; 962 963 /* 964 * Set up the filesystem mount context. 965 */ 966 static int cramfs_init_fs_context(struct fs_context *fc) 967 { 968 fc->ops = &cramfs_context_ops; 969 return 0; 970 } 971 972 static struct file_system_type cramfs_fs_type = { 973 .owner = THIS_MODULE, 974 .name = "cramfs", 975 .init_fs_context = cramfs_init_fs_context, 976 .kill_sb = cramfs_kill_sb, 977 .fs_flags = FS_REQUIRES_DEV, 978 }; 979 MODULE_ALIAS_FS("cramfs"); 980 981 static int __init init_cramfs_fs(void) 982 { 983 int rv; 984 985 rv = cramfs_uncompress_init(); 986 if (rv < 0) 987 return rv; 988 rv = register_filesystem(&cramfs_fs_type); 989 if (rv < 0) 990 cramfs_uncompress_exit(); 991 return rv; 992 } 993 994 static void __exit exit_cramfs_fs(void) 995 { 996 cramfs_uncompress_exit(); 997 unregister_filesystem(&cramfs_fs_type); 998 } 999 1000 module_init(init_cramfs_fs) 1001 module_exit(exit_cramfs_fs) 1002 MODULE_LICENSE("GPL"); 1003