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 = bdev_nr_bytes(sb->s_bdev) >> 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: %pD: last page is shared\n", file); 396 pages--; 397 } 398 399 if (!pages) { 400 bailout_reason = "no suitable block remaining"; 401 goto bailout; 402 } 403 404 if (pages == vma_pages(vma)) { 405 /* 406 * The entire vma is mappable. remap_pfn_range() will 407 * make it distinguishable from a non-direct mapping 408 * in /proc/<pid>/maps by substituting the file offset 409 * with the actual physical address. 410 */ 411 ret = remap_pfn_range(vma, vma->vm_start, address >> PAGE_SHIFT, 412 pages * PAGE_SIZE, vma->vm_page_prot); 413 } else { 414 /* 415 * Let's create a mixed map if we can't map it all. 416 * The normal paging machinery will take care of the 417 * unpopulated ptes via cramfs_read_folio(). 418 */ 419 int i; 420 vma->vm_flags |= VM_MIXEDMAP; 421 for (i = 0; i < pages && !ret; i++) { 422 vm_fault_t vmf; 423 unsigned long off = i * PAGE_SIZE; 424 pfn_t pfn = phys_to_pfn_t(address + off, PFN_DEV); 425 vmf = vmf_insert_mixed(vma, vma->vm_start + off, pfn); 426 if (vmf & VM_FAULT_ERROR) 427 ret = vm_fault_to_errno(vmf, 0); 428 } 429 } 430 431 if (!ret) 432 pr_debug("mapped %pD[%lu] at 0x%08lx (%u/%lu pages) " 433 "to vma 0x%08lx, page_prot 0x%llx\n", file, 434 pgoff, address, pages, vma_pages(vma), vma->vm_start, 435 (unsigned long long)pgprot_val(vma->vm_page_prot)); 436 return ret; 437 438 bailout: 439 pr_debug("%pD[%lu]: direct mmap impossible: %s\n", 440 file, pgoff, bailout_reason); 441 /* Didn't manage any direct map, but normal paging is still possible */ 442 return 0; 443 } 444 445 #else /* CONFIG_MMU */ 446 447 static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma) 448 { 449 return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 0 : -ENOSYS; 450 } 451 452 static unsigned long cramfs_physmem_get_unmapped_area(struct file *file, 453 unsigned long addr, unsigned long len, 454 unsigned long pgoff, unsigned long flags) 455 { 456 struct inode *inode = file_inode(file); 457 struct super_block *sb = inode->i_sb; 458 struct cramfs_sb_info *sbi = CRAMFS_SB(sb); 459 unsigned int pages, block_pages, max_pages, offset; 460 461 pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; 462 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT; 463 if (pgoff >= max_pages || pages > max_pages - pgoff) 464 return -EINVAL; 465 block_pages = pages; 466 offset = cramfs_get_block_range(inode, pgoff, &block_pages); 467 if (!offset || block_pages != pages) 468 return -ENOSYS; 469 addr = sbi->linear_phys_addr + offset; 470 pr_debug("get_unmapped for %pD ofs %#lx siz %lu at 0x%08lx\n", 471 file, pgoff*PAGE_SIZE, len, addr); 472 return addr; 473 } 474 475 static unsigned int cramfs_physmem_mmap_capabilities(struct file *file) 476 { 477 return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT | 478 NOMMU_MAP_READ | NOMMU_MAP_EXEC; 479 } 480 481 #endif /* CONFIG_MMU */ 482 483 static const struct file_operations cramfs_physmem_fops = { 484 .llseek = generic_file_llseek, 485 .read_iter = generic_file_read_iter, 486 .splice_read = generic_file_splice_read, 487 .mmap = cramfs_physmem_mmap, 488 #ifndef CONFIG_MMU 489 .get_unmapped_area = cramfs_physmem_get_unmapped_area, 490 .mmap_capabilities = cramfs_physmem_mmap_capabilities, 491 #endif 492 }; 493 494 static void cramfs_kill_sb(struct super_block *sb) 495 { 496 struct cramfs_sb_info *sbi = CRAMFS_SB(sb); 497 498 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sb->s_mtd) { 499 if (sbi && sbi->mtd_point_size) 500 mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size); 501 kill_mtd_super(sb); 502 } else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) { 503 kill_block_super(sb); 504 } 505 kfree(sbi); 506 } 507 508 static int cramfs_reconfigure(struct fs_context *fc) 509 { 510 sync_filesystem(fc->root->d_sb); 511 fc->sb_flags |= SB_RDONLY; 512 return 0; 513 } 514 515 static int cramfs_read_super(struct super_block *sb, struct fs_context *fc, 516 struct cramfs_super *super) 517 { 518 struct cramfs_sb_info *sbi = CRAMFS_SB(sb); 519 unsigned long root_offset; 520 bool silent = fc->sb_flags & SB_SILENT; 521 522 /* We don't know the real size yet */ 523 sbi->size = PAGE_SIZE; 524 525 /* Read the first block and get the superblock from it */ 526 mutex_lock(&read_mutex); 527 memcpy(super, cramfs_read(sb, 0, sizeof(*super)), sizeof(*super)); 528 mutex_unlock(&read_mutex); 529 530 /* Do sanity checks on the superblock */ 531 if (super->magic != CRAMFS_MAGIC) { 532 /* check for wrong endianness */ 533 if (super->magic == CRAMFS_MAGIC_WEND) { 534 if (!silent) 535 errorfc(fc, "wrong endianness"); 536 return -EINVAL; 537 } 538 539 /* check at 512 byte offset */ 540 mutex_lock(&read_mutex); 541 memcpy(super, 542 cramfs_read(sb, 512, sizeof(*super)), 543 sizeof(*super)); 544 mutex_unlock(&read_mutex); 545 if (super->magic != CRAMFS_MAGIC) { 546 if (super->magic == CRAMFS_MAGIC_WEND && !silent) 547 errorfc(fc, "wrong endianness"); 548 else if (!silent) 549 errorfc(fc, "wrong magic"); 550 return -EINVAL; 551 } 552 } 553 554 /* get feature flags first */ 555 if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) { 556 errorfc(fc, "unsupported filesystem features"); 557 return -EINVAL; 558 } 559 560 /* Check that the root inode is in a sane state */ 561 if (!S_ISDIR(super->root.mode)) { 562 errorfc(fc, "root is not a directory"); 563 return -EINVAL; 564 } 565 /* correct strange, hard-coded permissions of mkcramfs */ 566 super->root.mode |= 0555; 567 568 root_offset = super->root.offset << 2; 569 if (super->flags & CRAMFS_FLAG_FSID_VERSION_2) { 570 sbi->size = super->size; 571 sbi->blocks = super->fsid.blocks; 572 sbi->files = super->fsid.files; 573 } else { 574 sbi->size = 1<<28; 575 sbi->blocks = 0; 576 sbi->files = 0; 577 } 578 sbi->magic = super->magic; 579 sbi->flags = super->flags; 580 if (root_offset == 0) 581 infofc(fc, "empty filesystem"); 582 else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) && 583 ((root_offset != sizeof(struct cramfs_super)) && 584 (root_offset != 512 + sizeof(struct cramfs_super)))) 585 { 586 errorfc(fc, "bad root offset %lu", root_offset); 587 return -EINVAL; 588 } 589 590 return 0; 591 } 592 593 static int cramfs_finalize_super(struct super_block *sb, 594 struct cramfs_inode *cramfs_root) 595 { 596 struct inode *root; 597 598 /* Set it all up.. */ 599 sb->s_flags |= SB_RDONLY; 600 sb->s_time_min = 0; 601 sb->s_time_max = 0; 602 sb->s_op = &cramfs_ops; 603 root = get_cramfs_inode(sb, cramfs_root, 0); 604 if (IS_ERR(root)) 605 return PTR_ERR(root); 606 sb->s_root = d_make_root(root); 607 if (!sb->s_root) 608 return -ENOMEM; 609 return 0; 610 } 611 612 static int cramfs_blkdev_fill_super(struct super_block *sb, struct fs_context *fc) 613 { 614 struct cramfs_sb_info *sbi; 615 struct cramfs_super super; 616 int i, err; 617 618 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL); 619 if (!sbi) 620 return -ENOMEM; 621 sb->s_fs_info = sbi; 622 623 /* Invalidate the read buffers on mount: think disk change.. */ 624 for (i = 0; i < READ_BUFFERS; i++) 625 buffer_blocknr[i] = -1; 626 627 err = cramfs_read_super(sb, fc, &super); 628 if (err) 629 return err; 630 return cramfs_finalize_super(sb, &super.root); 631 } 632 633 static int cramfs_mtd_fill_super(struct super_block *sb, struct fs_context *fc) 634 { 635 struct cramfs_sb_info *sbi; 636 struct cramfs_super super; 637 int err; 638 639 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL); 640 if (!sbi) 641 return -ENOMEM; 642 sb->s_fs_info = sbi; 643 644 /* Map only one page for now. Will remap it when fs size is known. */ 645 err = mtd_point(sb->s_mtd, 0, PAGE_SIZE, &sbi->mtd_point_size, 646 &sbi->linear_virt_addr, &sbi->linear_phys_addr); 647 if (err || sbi->mtd_point_size != PAGE_SIZE) { 648 pr_err("unable to get direct memory access to mtd:%s\n", 649 sb->s_mtd->name); 650 return err ? : -ENODATA; 651 } 652 653 pr_info("checking physical address %pap for linear cramfs image\n", 654 &sbi->linear_phys_addr); 655 err = cramfs_read_super(sb, fc, &super); 656 if (err) 657 return err; 658 659 /* Remap the whole filesystem now */ 660 pr_info("linear cramfs image on mtd:%s appears to be %lu KB in size\n", 661 sb->s_mtd->name, sbi->size/1024); 662 mtd_unpoint(sb->s_mtd, 0, PAGE_SIZE); 663 err = mtd_point(sb->s_mtd, 0, sbi->size, &sbi->mtd_point_size, 664 &sbi->linear_virt_addr, &sbi->linear_phys_addr); 665 if (err || sbi->mtd_point_size != sbi->size) { 666 pr_err("unable to get direct memory access to mtd:%s\n", 667 sb->s_mtd->name); 668 return err ? : -ENODATA; 669 } 670 671 return cramfs_finalize_super(sb, &super.root); 672 } 673 674 static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf) 675 { 676 struct super_block *sb = dentry->d_sb; 677 u64 id = 0; 678 679 if (sb->s_bdev) 680 id = huge_encode_dev(sb->s_bdev->bd_dev); 681 else if (sb->s_dev) 682 id = huge_encode_dev(sb->s_dev); 683 684 buf->f_type = CRAMFS_MAGIC; 685 buf->f_bsize = PAGE_SIZE; 686 buf->f_blocks = CRAMFS_SB(sb)->blocks; 687 buf->f_bfree = 0; 688 buf->f_bavail = 0; 689 buf->f_files = CRAMFS_SB(sb)->files; 690 buf->f_ffree = 0; 691 buf->f_fsid = u64_to_fsid(id); 692 buf->f_namelen = CRAMFS_MAXPATHLEN; 693 return 0; 694 } 695 696 /* 697 * Read a cramfs directory entry. 698 */ 699 static int cramfs_readdir(struct file *file, struct dir_context *ctx) 700 { 701 struct inode *inode = file_inode(file); 702 struct super_block *sb = inode->i_sb; 703 char *buf; 704 unsigned int offset; 705 706 /* Offset within the thing. */ 707 if (ctx->pos >= inode->i_size) 708 return 0; 709 offset = ctx->pos; 710 /* Directory entries are always 4-byte aligned */ 711 if (offset & 3) 712 return -EINVAL; 713 714 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL); 715 if (!buf) 716 return -ENOMEM; 717 718 while (offset < inode->i_size) { 719 struct cramfs_inode *de; 720 unsigned long nextoffset; 721 char *name; 722 ino_t ino; 723 umode_t mode; 724 int namelen; 725 726 mutex_lock(&read_mutex); 727 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN); 728 name = (char *)(de+1); 729 730 /* 731 * Namelengths on disk are shifted by two 732 * and the name padded out to 4-byte boundaries 733 * with zeroes. 734 */ 735 namelen = de->namelen << 2; 736 memcpy(buf, name, namelen); 737 ino = cramino(de, OFFSET(inode) + offset); 738 mode = de->mode; 739 mutex_unlock(&read_mutex); 740 nextoffset = offset + sizeof(*de) + namelen; 741 for (;;) { 742 if (!namelen) { 743 kfree(buf); 744 return -EIO; 745 } 746 if (buf[namelen-1]) 747 break; 748 namelen--; 749 } 750 if (!dir_emit(ctx, buf, namelen, ino, mode >> 12)) 751 break; 752 753 ctx->pos = offset = nextoffset; 754 } 755 kfree(buf); 756 return 0; 757 } 758 759 /* 760 * Lookup and fill in the inode data.. 761 */ 762 static struct dentry *cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) 763 { 764 unsigned int offset = 0; 765 struct inode *inode = NULL; 766 int sorted; 767 768 mutex_lock(&read_mutex); 769 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS; 770 while (offset < dir->i_size) { 771 struct cramfs_inode *de; 772 char *name; 773 int namelen, retval; 774 int dir_off = OFFSET(dir) + offset; 775 776 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN); 777 name = (char *)(de+1); 778 779 /* Try to take advantage of sorted directories */ 780 if (sorted && (dentry->d_name.name[0] < name[0])) 781 break; 782 783 namelen = de->namelen << 2; 784 offset += sizeof(*de) + namelen; 785 786 /* Quick check that the name is roughly the right length */ 787 if (((dentry->d_name.len + 3) & ~3) != namelen) 788 continue; 789 790 for (;;) { 791 if (!namelen) { 792 inode = ERR_PTR(-EIO); 793 goto out; 794 } 795 if (name[namelen-1]) 796 break; 797 namelen--; 798 } 799 if (namelen != dentry->d_name.len) 800 continue; 801 retval = memcmp(dentry->d_name.name, name, namelen); 802 if (retval > 0) 803 continue; 804 if (!retval) { 805 inode = get_cramfs_inode(dir->i_sb, de, dir_off); 806 break; 807 } 808 /* else (retval < 0) */ 809 if (sorted) 810 break; 811 } 812 out: 813 mutex_unlock(&read_mutex); 814 return d_splice_alias(inode, dentry); 815 } 816 817 static int cramfs_read_folio(struct file *file, struct folio *folio) 818 { 819 struct page *page = &folio->page; 820 struct inode *inode = page->mapping->host; 821 u32 maxblock; 822 int bytes_filled; 823 void *pgdata; 824 825 maxblock = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT; 826 bytes_filled = 0; 827 pgdata = kmap(page); 828 829 if (page->index < maxblock) { 830 struct super_block *sb = inode->i_sb; 831 u32 blkptr_offset = OFFSET(inode) + page->index * 4; 832 u32 block_ptr, block_start, block_len; 833 bool uncompressed, direct; 834 835 mutex_lock(&read_mutex); 836 block_ptr = *(u32 *) cramfs_read(sb, blkptr_offset, 4); 837 uncompressed = (block_ptr & CRAMFS_BLK_FLAG_UNCOMPRESSED); 838 direct = (block_ptr & CRAMFS_BLK_FLAG_DIRECT_PTR); 839 block_ptr &= ~CRAMFS_BLK_FLAGS; 840 841 if (direct) { 842 /* 843 * The block pointer is an absolute start pointer, 844 * shifted by 2 bits. The size is included in the 845 * first 2 bytes of the data block when compressed, 846 * or PAGE_SIZE otherwise. 847 */ 848 block_start = block_ptr << CRAMFS_BLK_DIRECT_PTR_SHIFT; 849 if (uncompressed) { 850 block_len = PAGE_SIZE; 851 /* if last block: cap to file length */ 852 if (page->index == maxblock - 1) 853 block_len = 854 offset_in_page(inode->i_size); 855 } else { 856 block_len = *(u16 *) 857 cramfs_read(sb, block_start, 2); 858 block_start += 2; 859 } 860 } else { 861 /* 862 * The block pointer indicates one past the end of 863 * the current block (start of next block). If this 864 * is the first block then it starts where the block 865 * pointer table ends, otherwise its start comes 866 * from the previous block's pointer. 867 */ 868 block_start = OFFSET(inode) + maxblock * 4; 869 if (page->index) 870 block_start = *(u32 *) 871 cramfs_read(sb, blkptr_offset - 4, 4); 872 /* Beware... previous ptr might be a direct ptr */ 873 if (unlikely(block_start & CRAMFS_BLK_FLAG_DIRECT_PTR)) { 874 /* See comments on earlier code. */ 875 u32 prev_start = block_start; 876 block_start = prev_start & ~CRAMFS_BLK_FLAGS; 877 block_start <<= CRAMFS_BLK_DIRECT_PTR_SHIFT; 878 if (prev_start & CRAMFS_BLK_FLAG_UNCOMPRESSED) { 879 block_start += PAGE_SIZE; 880 } else { 881 block_len = *(u16 *) 882 cramfs_read(sb, block_start, 2); 883 block_start += 2 + block_len; 884 } 885 } 886 block_start &= ~CRAMFS_BLK_FLAGS; 887 block_len = block_ptr - block_start; 888 } 889 890 if (block_len == 0) 891 ; /* hole */ 892 else if (unlikely(block_len > 2*PAGE_SIZE || 893 (uncompressed && block_len > PAGE_SIZE))) { 894 mutex_unlock(&read_mutex); 895 pr_err("bad data blocksize %u\n", block_len); 896 goto err; 897 } else if (uncompressed) { 898 memcpy(pgdata, 899 cramfs_read(sb, block_start, block_len), 900 block_len); 901 bytes_filled = block_len; 902 } else { 903 bytes_filled = cramfs_uncompress_block(pgdata, 904 PAGE_SIZE, 905 cramfs_read(sb, block_start, block_len), 906 block_len); 907 } 908 mutex_unlock(&read_mutex); 909 if (unlikely(bytes_filled < 0)) 910 goto err; 911 } 912 913 memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled); 914 flush_dcache_page(page); 915 kunmap(page); 916 SetPageUptodate(page); 917 unlock_page(page); 918 return 0; 919 920 err: 921 kunmap(page); 922 ClearPageUptodate(page); 923 SetPageError(page); 924 unlock_page(page); 925 return 0; 926 } 927 928 static const struct address_space_operations cramfs_aops = { 929 .read_folio = cramfs_read_folio 930 }; 931 932 /* 933 * Our operations: 934 */ 935 936 /* 937 * A directory can only readdir 938 */ 939 static const struct file_operations cramfs_directory_operations = { 940 .llseek = generic_file_llseek, 941 .read = generic_read_dir, 942 .iterate_shared = cramfs_readdir, 943 }; 944 945 static const struct inode_operations cramfs_dir_inode_operations = { 946 .lookup = cramfs_lookup, 947 }; 948 949 static const struct super_operations cramfs_ops = { 950 .statfs = cramfs_statfs, 951 }; 952 953 static int cramfs_get_tree(struct fs_context *fc) 954 { 955 int ret = -ENOPROTOOPT; 956 957 if (IS_ENABLED(CONFIG_CRAMFS_MTD)) { 958 ret = get_tree_mtd(fc, cramfs_mtd_fill_super); 959 if (!ret) 960 return 0; 961 } 962 if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV)) 963 ret = get_tree_bdev(fc, cramfs_blkdev_fill_super); 964 return ret; 965 } 966 967 static const struct fs_context_operations cramfs_context_ops = { 968 .get_tree = cramfs_get_tree, 969 .reconfigure = cramfs_reconfigure, 970 }; 971 972 /* 973 * Set up the filesystem mount context. 974 */ 975 static int cramfs_init_fs_context(struct fs_context *fc) 976 { 977 fc->ops = &cramfs_context_ops; 978 return 0; 979 } 980 981 static struct file_system_type cramfs_fs_type = { 982 .owner = THIS_MODULE, 983 .name = "cramfs", 984 .init_fs_context = cramfs_init_fs_context, 985 .kill_sb = cramfs_kill_sb, 986 .fs_flags = FS_REQUIRES_DEV, 987 }; 988 MODULE_ALIAS_FS("cramfs"); 989 990 static int __init init_cramfs_fs(void) 991 { 992 int rv; 993 994 rv = cramfs_uncompress_init(); 995 if (rv < 0) 996 return rv; 997 rv = register_filesystem(&cramfs_fs_type); 998 if (rv < 0) 999 cramfs_uncompress_exit(); 1000 return rv; 1001 } 1002 1003 static void __exit exit_cramfs_fs(void) 1004 { 1005 cramfs_uncompress_exit(); 1006 unregister_filesystem(&cramfs_fs_type); 1007 } 1008 1009 module_init(init_cramfs_fs) 1010 module_exit(exit_cramfs_fs) 1011 MODULE_LICENSE("GPL"); 1012