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1/*2 * Compressed rom filesystem for Linux.3 *4 * Copyright (C) 1999 Linus Torvalds.5 *6 * This file is released under the GPL.7 */8 9/*10 * These are the VFS interfaces to the compressed rom filesystem.11 * The actual compression is based on zlib, see the other files.12 */13 14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt15 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 memory38 */39struct cramfs_sb_info {40 unsigned long magic;41 unsigned long size;42 unsigned long blocks;43 unsigned long files;44 unsigned long flags;45 void *linear_virt_addr;46 resource_size_t linear_phys_addr;47 size_t mtd_point_size;48};49 50static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb)51{52 return sb->s_fs_info;53}54 55static const struct super_operations cramfs_ops;56static const struct inode_operations cramfs_dir_inode_operations;57static const struct file_operations cramfs_directory_operations;58static const struct file_operations cramfs_physmem_fops;59static const struct address_space_operations cramfs_aops;60 61static DEFINE_MUTEX(read_mutex);62 63 64/* These macros may change in future, to provide better st_ino semantics. */65#define OFFSET(x) ((x)->i_ino)66 67static unsigned long cramino(const struct cramfs_inode *cino, unsigned int offset)68{69 if (!cino->offset)70 return offset + 1;71 if (!cino->size)72 return offset + 1;73 74 /*75 * The file mode test fixes buggy mkcramfs implementations where76 * cramfs_inode->offset is set to a non zero value for entries77 * which did not contain data, like devices node and fifos.78 */79 switch (cino->mode & S_IFMT) {80 case S_IFREG:81 case S_IFDIR:82 case S_IFLNK:83 return cino->offset << 2;84 default:85 break;86 }87 return offset + 1;88}89 90static struct inode *get_cramfs_inode(struct super_block *sb,91 const struct cramfs_inode *cramfs_inode, unsigned int offset)92{93 struct inode *inode;94 static struct timespec64 zerotime;95 96 inode = iget_locked(sb, cramino(cramfs_inode, offset));97 if (!inode)98 return ERR_PTR(-ENOMEM);99 if (!(inode->i_state & I_NEW))100 return inode;101 102 switch (cramfs_inode->mode & S_IFMT) {103 case S_IFREG:104 inode->i_fop = &generic_ro_fops;105 inode->i_data.a_ops = &cramfs_aops;106 if (IS_ENABLED(CONFIG_CRAMFS_MTD) &&107 CRAMFS_SB(sb)->flags & CRAMFS_FLAG_EXT_BLOCK_POINTERS &&108 CRAMFS_SB(sb)->linear_phys_addr)109 inode->i_fop = &cramfs_physmem_fops;110 break;111 case S_IFDIR:112 inode->i_op = &cramfs_dir_inode_operations;113 inode->i_fop = &cramfs_directory_operations;114 break;115 case S_IFLNK:116 inode->i_op = &page_symlink_inode_operations;117 inode_nohighmem(inode);118 inode->i_data.a_ops = &cramfs_aops;119 break;120 default:121 init_special_inode(inode, cramfs_inode->mode,122 old_decode_dev(cramfs_inode->size));123 }124 125 inode->i_mode = cramfs_inode->mode;126 i_uid_write(inode, cramfs_inode->uid);127 i_gid_write(inode, cramfs_inode->gid);128 129 /* if the lower 2 bits are zero, the inode contains data */130 if (!(inode->i_ino & 3)) {131 inode->i_size = cramfs_inode->size;132 inode->i_blocks = (cramfs_inode->size - 1) / 512 + 1;133 }134 135 /* Struct copy intentional */136 inode_set_mtime_to_ts(inode,137 inode_set_atime_to_ts(inode, inode_set_ctime_to_ts(inode, zerotime)));138 /* inode->i_nlink is left 1 - arguably wrong for directories,139 but it's the best we can do without reading the directory140 contents. 1 yields the right result in GNU find, even141 without -noleaf option. */142 143 unlock_new_inode(inode);144 145 return inode;146}147 148/*149 * We have our own block cache: don't fill up the buffer cache150 * with the rom-image, because the way the filesystem is set151 * up the accesses should be fairly regular and cached in the152 * page cache and dentry tree anyway..153 *154 * This also acts as a way to guarantee contiguous areas of up to155 * BLKS_PER_BUF*PAGE_SIZE, so that the caller doesn't need to156 * worry about end-of-buffer issues even when decompressing a full157 * page cache.158 *159 * Note: This is all optimized away at compile time when160 * CONFIG_CRAMFS_BLOCKDEV=n.161 */162#define READ_BUFFERS (2)163/* NEXT_BUFFER(): Loop over [0..(READ_BUFFERS-1)]. */164#define NEXT_BUFFER(_ix) ((_ix) ^ 1)165 166/*167 * BLKS_PER_BUF_SHIFT should be at least 2 to allow for "compressed"168 * data that takes up more space than the original and with unlucky169 * alignment.170 */171#define BLKS_PER_BUF_SHIFT (2)172#define BLKS_PER_BUF (1 << BLKS_PER_BUF_SHIFT)173#define BUFFER_SIZE (BLKS_PER_BUF*PAGE_SIZE)174 175static unsigned char read_buffers[READ_BUFFERS][BUFFER_SIZE];176static unsigned buffer_blocknr[READ_BUFFERS];177static struct super_block *buffer_dev[READ_BUFFERS];178static int next_buffer;179 180/*181 * Populate our block cache and return a pointer to it.182 */183static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,184 unsigned int len)185{186 struct address_space *mapping = sb->s_bdev->bd_mapping;187 struct file_ra_state ra = {};188 struct page *pages[BLKS_PER_BUF];189 unsigned i, blocknr, buffer;190 unsigned long devsize;191 char *data;192 193 if (!len)194 return NULL;195 blocknr = offset >> PAGE_SHIFT;196 offset &= PAGE_SIZE - 1;197 198 /* Check if an existing buffer already has the data.. */199 for (i = 0; i < READ_BUFFERS; i++) {200 unsigned int blk_offset;201 202 if (buffer_dev[i] != sb)203 continue;204 if (blocknr < buffer_blocknr[i])205 continue;206 blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT;207 blk_offset += offset;208 if (blk_offset > BUFFER_SIZE ||209 blk_offset + len > BUFFER_SIZE)210 continue;211 return read_buffers[i] + blk_offset;212 }213 214 devsize = bdev_nr_bytes(sb->s_bdev) >> PAGE_SHIFT;215 216 /* Ok, read in BLKS_PER_BUF pages completely first. */217 file_ra_state_init(&ra, mapping);218 page_cache_sync_readahead(mapping, &ra, NULL, blocknr, BLKS_PER_BUF);219 220 for (i = 0; i < BLKS_PER_BUF; i++) {221 struct page *page = NULL;222 223 if (blocknr + i < devsize) {224 page = read_mapping_page(mapping, blocknr + i, NULL);225 /* synchronous error? */226 if (IS_ERR(page))227 page = NULL;228 }229 pages[i] = page;230 }231 232 buffer = next_buffer;233 next_buffer = NEXT_BUFFER(buffer);234 buffer_blocknr[buffer] = blocknr;235 buffer_dev[buffer] = sb;236 237 data = read_buffers[buffer];238 for (i = 0; i < BLKS_PER_BUF; i++) {239 struct page *page = pages[i];240 241 if (page) {242 memcpy_from_page(data, page, 0, PAGE_SIZE);243 put_page(page);244 } else245 memset(data, 0, PAGE_SIZE);246 data += PAGE_SIZE;247 }248 return read_buffers[buffer] + offset;249}250 251/*252 * Return a pointer to the linearly addressed cramfs image in memory.253 */254static void *cramfs_direct_read(struct super_block *sb, unsigned int offset,255 unsigned int len)256{257 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);258 259 if (!len)260 return NULL;261 if (len > sbi->size || offset > sbi->size - len)262 return page_address(ZERO_PAGE(0));263 return sbi->linear_virt_addr + offset;264}265 266/*267 * Returns a pointer to a buffer containing at least LEN bytes of268 * filesystem starting at byte offset OFFSET into the filesystem.269 */270static void *cramfs_read(struct super_block *sb, unsigned int offset,271 unsigned int len)272{273 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);274 275 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sbi->linear_virt_addr)276 return cramfs_direct_read(sb, offset, len);277 else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))278 return cramfs_blkdev_read(sb, offset, len);279 else280 return NULL;281}282 283/*284 * For a mapping to be possible, we need a range of uncompressed and285 * contiguous blocks. Return the offset for the first block and number of286 * valid blocks for which that is true, or zero otherwise.287 */288static u32 cramfs_get_block_range(struct inode *inode, u32 pgoff, u32 *pages)289{290 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);291 int i;292 u32 *blockptrs, first_block_addr;293 294 /*295 * We can dereference memory directly here as this code may be296 * reached only when there is a direct filesystem image mapping297 * 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_MMU322 323/*324 * Return true if the last page of a file in the filesystem image contains325 * some other data that doesn't belong to that file. It is assumed that the326 * last block is CRAMFS_BLK_FLAG_DIRECT_PTR | CRAMFS_BLK_FLAG_UNCOMPRESSED327 * (verified by cramfs_get_block_range() and directly accessible in memory.328 */329static bool cramfs_last_page_is_shared(struct inode *inode)330{331 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);332 u32 partial, last_page, blockaddr, *blockptrs;333 char *tail_data;334 335 partial = offset_in_page(inode->i_size);336 if (!partial)337 return false;338 last_page = inode->i_size >> PAGE_SHIFT;339 blockptrs = (u32 *)(sbi->linear_virt_addr + OFFSET(inode));340 blockaddr = blockptrs[last_page] & ~CRAMFS_BLK_FLAGS;341 blockaddr <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;342 tail_data = sbi->linear_virt_addr + blockaddr + partial;343 return memchr_inv(tail_data, 0, PAGE_SIZE - partial) ? true : false;344}345 346static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)347{348 struct inode *inode = file_inode(file);349 struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);350 unsigned int pages, max_pages, offset;351 unsigned long address, pgoff = vma->vm_pgoff;352 char *bailout_reason;353 int ret;354 355 ret = generic_file_readonly_mmap(file, vma);356 if (ret)357 return ret;358 359 /*360 * Now try to pre-populate ptes for this vma with a direct361 * 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() will398 * make it distinguishable from a non-direct mapping399 * in /proc/<pid>/maps by substituting the file offset400 * 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 the408 * unpopulated ptes via cramfs_read_folio().409 */410 int i;411 vm_flags_set(vma, VM_MIXEDMAP);412 for (i = 0; i < pages && !ret; i++) {413 vm_fault_t vmf;414 unsigned long off = i * PAGE_SIZE;415 pfn_t pfn = phys_to_pfn_t(address + off, PFN_DEV);416 vmf = vmf_insert_mixed(vma, vma->vm_start + off, pfn);417 if (vmf & VM_FAULT_ERROR)418 ret = vm_fault_to_errno(vmf, 0);419 }420 }421 422 if (!ret)423 pr_debug("mapped %pD[%lu] at 0x%08lx (%u/%lu pages) "424 "to vma 0x%08lx, page_prot 0x%llx\n", file,425 pgoff, address, pages, vma_pages(vma), vma->vm_start,426 (unsigned long long)pgprot_val(vma->vm_page_prot));427 return ret;428 429bailout:430 pr_debug("%pD[%lu]: direct mmap impossible: %s\n",431 file, pgoff, bailout_reason);432 /* Didn't manage any direct map, but normal paging is still possible */433 return 0;434}435 436#else /* CONFIG_MMU */437 438static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)439{440 return is_nommu_shared_mapping(vma->vm_flags) ? 0 : -ENOSYS;441}442 443static unsigned long cramfs_physmem_get_unmapped_area(struct file *file,444 unsigned long addr, unsigned long len,445 unsigned long pgoff, unsigned long flags)446{447 struct inode *inode = file_inode(file);448 struct super_block *sb = inode->i_sb;449 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);450 unsigned int pages, block_pages, max_pages, offset;451 452 pages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;453 max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;454 if (pgoff >= max_pages || pages > max_pages - pgoff)455 return -EINVAL;456 block_pages = pages;457 offset = cramfs_get_block_range(inode, pgoff, &block_pages);458 if (!offset || block_pages != pages)459 return -ENOSYS;460 addr = sbi->linear_phys_addr + offset;461 pr_debug("get_unmapped for %pD ofs %#lx siz %lu at 0x%08lx\n",462 file, pgoff*PAGE_SIZE, len, addr);463 return addr;464}465 466static unsigned int cramfs_physmem_mmap_capabilities(struct file *file)467{468 return NOMMU_MAP_COPY | NOMMU_MAP_DIRECT |469 NOMMU_MAP_READ | NOMMU_MAP_EXEC;470}471 472#endif /* CONFIG_MMU */473 474static const struct file_operations cramfs_physmem_fops = {475 .llseek = generic_file_llseek,476 .read_iter = generic_file_read_iter,477 .splice_read = filemap_splice_read,478 .mmap = cramfs_physmem_mmap,479#ifndef CONFIG_MMU480 .get_unmapped_area = cramfs_physmem_get_unmapped_area,481 .mmap_capabilities = cramfs_physmem_mmap_capabilities,482#endif483};484 485static void cramfs_kill_sb(struct super_block *sb)486{487 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);488 489 generic_shutdown_super(sb);490 491 if (IS_ENABLED(CONFIG_CRAMFS_MTD) && sb->s_mtd) {492 if (sbi && sbi->mtd_point_size)493 mtd_unpoint(sb->s_mtd, 0, sbi->mtd_point_size);494 put_mtd_device(sb->s_mtd);495 sb->s_mtd = NULL;496 } else if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV) && sb->s_bdev) {497 sync_blockdev(sb->s_bdev);498 bdev_fput(sb->s_bdev_file);499 }500 kfree(sbi);501}502 503static int cramfs_reconfigure(struct fs_context *fc)504{505 sync_filesystem(fc->root->d_sb);506 fc->sb_flags |= SB_RDONLY;507 return 0;508}509 510static int cramfs_read_super(struct super_block *sb, struct fs_context *fc,511 struct cramfs_super *super)512{513 struct cramfs_sb_info *sbi = CRAMFS_SB(sb);514 unsigned long root_offset;515 bool silent = fc->sb_flags & SB_SILENT;516 517 /* We don't know the real size yet */518 sbi->size = PAGE_SIZE;519 520 /* Read the first block and get the superblock from it */521 mutex_lock(&read_mutex);522 memcpy(super, cramfs_read(sb, 0, sizeof(*super)), sizeof(*super));523 mutex_unlock(&read_mutex);524 525 /* Do sanity checks on the superblock */526 if (super->magic != CRAMFS_MAGIC) {527 /* check for wrong endianness */528 if (super->magic == CRAMFS_MAGIC_WEND) {529 if (!silent)530 errorfc(fc, "wrong endianness");531 return -EINVAL;532 }533 534 /* check at 512 byte offset */535 mutex_lock(&read_mutex);536 memcpy(super,537 cramfs_read(sb, 512, sizeof(*super)),538 sizeof(*super));539 mutex_unlock(&read_mutex);540 if (super->magic != CRAMFS_MAGIC) {541 if (super->magic == CRAMFS_MAGIC_WEND && !silent)542 errorfc(fc, "wrong endianness");543 else if (!silent)544 errorfc(fc, "wrong magic");545 return -EINVAL;546 }547 }548 549 /* get feature flags first */550 if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) {551 errorfc(fc, "unsupported filesystem features");552 return -EINVAL;553 }554 555 /* Check that the root inode is in a sane state */556 if (!S_ISDIR(super->root.mode)) {557 errorfc(fc, "root is not a directory");558 return -EINVAL;559 }560 /* correct strange, hard-coded permissions of mkcramfs */561 super->root.mode |= 0555;562 563 root_offset = super->root.offset << 2;564 if (super->flags & CRAMFS_FLAG_FSID_VERSION_2) {565 sbi->size = super->size;566 sbi->blocks = super->fsid.blocks;567 sbi->files = super->fsid.files;568 } else {569 sbi->size = 1<<28;570 sbi->blocks = 0;571 sbi->files = 0;572 }573 sbi->magic = super->magic;574 sbi->flags = super->flags;575 if (root_offset == 0)576 infofc(fc, "empty filesystem");577 else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&578 ((root_offset != sizeof(struct cramfs_super)) &&579 (root_offset != 512 + sizeof(struct cramfs_super))))580 {581 errorfc(fc, "bad root offset %lu", root_offset);582 return -EINVAL;583 }584 585 return 0;586}587 588static int cramfs_finalize_super(struct super_block *sb,589 struct cramfs_inode *cramfs_root)590{591 struct inode *root;592 593 /* Set it all up.. */594 sb->s_flags |= SB_RDONLY;595 sb->s_time_min = 0;596 sb->s_time_max = 0;597 sb->s_op = &cramfs_ops;598 root = get_cramfs_inode(sb, cramfs_root, 0);599 if (IS_ERR(root))600 return PTR_ERR(root);601 sb->s_root = d_make_root(root);602 if (!sb->s_root)603 return -ENOMEM;604 return 0;605}606 607static int cramfs_blkdev_fill_super(struct super_block *sb, struct fs_context *fc)608{609 struct cramfs_sb_info *sbi;610 struct cramfs_super super;611 int i, err;612 613 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);614 if (!sbi)615 return -ENOMEM;616 sb->s_fs_info = sbi;617 618 /* Invalidate the read buffers on mount: think disk change.. */619 for (i = 0; i < READ_BUFFERS; i++)620 buffer_blocknr[i] = -1;621 622 err = cramfs_read_super(sb, fc, &super);623 if (err)624 return err;625 return cramfs_finalize_super(sb, &super.root);626}627 628static int cramfs_mtd_fill_super(struct super_block *sb, struct fs_context *fc)629{630 struct cramfs_sb_info *sbi;631 struct cramfs_super super;632 int err;633 634 sbi = kzalloc(sizeof(struct cramfs_sb_info), GFP_KERNEL);635 if (!sbi)636 return -ENOMEM;637 sb->s_fs_info = sbi;638 639 /* Map only one page for now. Will remap it when fs size is known. */640 err = mtd_point(sb->s_mtd, 0, PAGE_SIZE, &sbi->mtd_point_size,641 &sbi->linear_virt_addr, &sbi->linear_phys_addr);642 if (err || sbi->mtd_point_size != PAGE_SIZE) {643 pr_err("unable to get direct memory access to mtd:%s\n",644 sb->s_mtd->name);645 return err ? : -ENODATA;646 }647 648 pr_info("checking physical address %pap for linear cramfs image\n",649 &sbi->linear_phys_addr);650 err = cramfs_read_super(sb, fc, &super);651 if (err)652 return err;653 654 /* Remap the whole filesystem now */655 pr_info("linear cramfs image on mtd:%s appears to be %lu KB in size\n",656 sb->s_mtd->name, sbi->size/1024);657 mtd_unpoint(sb->s_mtd, 0, PAGE_SIZE);658 err = mtd_point(sb->s_mtd, 0, sbi->size, &sbi->mtd_point_size,659 &sbi->linear_virt_addr, &sbi->linear_phys_addr);660 if (err || sbi->mtd_point_size != sbi->size) {661 pr_err("unable to get direct memory access to mtd:%s\n",662 sb->s_mtd->name);663 return err ? : -ENODATA;664 }665 666 return cramfs_finalize_super(sb, &super.root);667}668 669static int cramfs_statfs(struct dentry *dentry, struct kstatfs *buf)670{671 struct super_block *sb = dentry->d_sb;672 u64 id = 0;673 674 if (sb->s_bdev)675 id = huge_encode_dev(sb->s_bdev->bd_dev);676 else if (sb->s_dev)677 id = huge_encode_dev(sb->s_dev);678 679 buf->f_type = CRAMFS_MAGIC;680 buf->f_bsize = PAGE_SIZE;681 buf->f_blocks = CRAMFS_SB(sb)->blocks;682 buf->f_bfree = 0;683 buf->f_bavail = 0;684 buf->f_files = CRAMFS_SB(sb)->files;685 buf->f_ffree = 0;686 buf->f_fsid = u64_to_fsid(id);687 buf->f_namelen = CRAMFS_MAXPATHLEN;688 return 0;689}690 691/*692 * Read a cramfs directory entry.693 */694static int cramfs_readdir(struct file *file, struct dir_context *ctx)695{696 struct inode *inode = file_inode(file);697 struct super_block *sb = inode->i_sb;698 char *buf;699 unsigned int offset;700 701 /* Offset within the thing. */702 if (ctx->pos >= inode->i_size)703 return 0;704 offset = ctx->pos;705 /* Directory entries are always 4-byte aligned */706 if (offset & 3)707 return -EINVAL;708 709 buf = kmalloc(CRAMFS_MAXPATHLEN, GFP_KERNEL);710 if (!buf)711 return -ENOMEM;712 713 while (offset < inode->i_size) {714 struct cramfs_inode *de;715 unsigned long nextoffset;716 char *name;717 ino_t ino;718 umode_t mode;719 int namelen;720 721 mutex_lock(&read_mutex);722 de = cramfs_read(sb, OFFSET(inode) + offset, sizeof(*de)+CRAMFS_MAXPATHLEN);723 name = (char *)(de+1);724 725 /*726 * Namelengths on disk are shifted by two727 * and the name padded out to 4-byte boundaries728 * with zeroes.729 */730 namelen = de->namelen << 2;731 memcpy(buf, name, namelen);732 ino = cramino(de, OFFSET(inode) + offset);733 mode = de->mode;734 mutex_unlock(&read_mutex);735 nextoffset = offset + sizeof(*de) + namelen;736 for (;;) {737 if (!namelen) {738 kfree(buf);739 return -EIO;740 }741 if (buf[namelen-1])742 break;743 namelen--;744 }745 if (!dir_emit(ctx, buf, namelen, ino, mode >> 12))746 break;747 748 ctx->pos = offset = nextoffset;749 }750 kfree(buf);751 return 0;752}753 754/*755 * Lookup and fill in the inode data..756 */757static struct dentry *cramfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)758{759 unsigned int offset = 0;760 struct inode *inode = NULL;761 int sorted;762 763 mutex_lock(&read_mutex);764 sorted = CRAMFS_SB(dir->i_sb)->flags & CRAMFS_FLAG_SORTED_DIRS;765 while (offset < dir->i_size) {766 struct cramfs_inode *de;767 char *name;768 int namelen, retval;769 int dir_off = OFFSET(dir) + offset;770 771 de = cramfs_read(dir->i_sb, dir_off, sizeof(*de)+CRAMFS_MAXPATHLEN);772 name = (char *)(de+1);773 774 /* Try to take advantage of sorted directories */775 if (sorted && (dentry->d_name.name[0] < name[0]))776 break;777 778 namelen = de->namelen << 2;779 offset += sizeof(*de) + namelen;780 781 /* Quick check that the name is roughly the right length */782 if (((dentry->d_name.len + 3) & ~3) != namelen)783 continue;784 785 for (;;) {786 if (!namelen) {787 inode = ERR_PTR(-EIO);788 goto out;789 }790 if (name[namelen-1])791 break;792 namelen--;793 }794 if (namelen != dentry->d_name.len)795 continue;796 retval = memcmp(dentry->d_name.name, name, namelen);797 if (retval > 0)798 continue;799 if (!retval) {800 inode = get_cramfs_inode(dir->i_sb, de, dir_off);801 break;802 }803 /* else (retval < 0) */804 if (sorted)805 break;806 }807out:808 mutex_unlock(&read_mutex);809 return d_splice_alias(inode, dentry);810}811 812static int cramfs_read_folio(struct file *file, struct folio *folio)813{814 struct inode *inode = folio->mapping->host;815 u32 maxblock;816 int bytes_filled;817 void *pgdata;818 bool success = false;819 820 maxblock = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;821 bytes_filled = 0;822 pgdata = kmap_local_folio(folio, 0);823 824 if (folio->index < maxblock) {825 struct super_block *sb = inode->i_sb;826 u32 blkptr_offset = OFFSET(inode) + folio->index * 4;827 u32 block_ptr, block_start, block_len;828 bool uncompressed, direct;829 830 mutex_lock(&read_mutex);831 block_ptr = *(u32 *) cramfs_read(sb, blkptr_offset, 4);832 uncompressed = (block_ptr & CRAMFS_BLK_FLAG_UNCOMPRESSED);833 direct = (block_ptr & CRAMFS_BLK_FLAG_DIRECT_PTR);834 block_ptr &= ~CRAMFS_BLK_FLAGS;835 836 if (direct) {837 /*838 * The block pointer is an absolute start pointer,839 * shifted by 2 bits. The size is included in the840 * first 2 bytes of the data block when compressed,841 * or PAGE_SIZE otherwise.842 */843 block_start = block_ptr << CRAMFS_BLK_DIRECT_PTR_SHIFT;844 if (uncompressed) {845 block_len = PAGE_SIZE;846 /* if last block: cap to file length */847 if (folio->index == maxblock - 1)848 block_len =849 offset_in_page(inode->i_size);850 } else {851 block_len = *(u16 *)852 cramfs_read(sb, block_start, 2);853 block_start += 2;854 }855 } else {856 /*857 * The block pointer indicates one past the end of858 * the current block (start of next block). If this859 * is the first block then it starts where the block860 * pointer table ends, otherwise its start comes861 * from the previous block's pointer.862 */863 block_start = OFFSET(inode) + maxblock * 4;864 if (folio->index)865 block_start = *(u32 *)866 cramfs_read(sb, blkptr_offset - 4, 4);867 /* Beware... previous ptr might be a direct ptr */868 if (unlikely(block_start & CRAMFS_BLK_FLAG_DIRECT_PTR)) {869 /* See comments on earlier code. */870 u32 prev_start = block_start;871 block_start = prev_start & ~CRAMFS_BLK_FLAGS;872 block_start <<= CRAMFS_BLK_DIRECT_PTR_SHIFT;873 if (prev_start & CRAMFS_BLK_FLAG_UNCOMPRESSED) {874 block_start += PAGE_SIZE;875 } else {876 block_len = *(u16 *)877 cramfs_read(sb, block_start, 2);878 block_start += 2 + block_len;879 }880 }881 block_start &= ~CRAMFS_BLK_FLAGS;882 block_len = block_ptr - block_start;883 }884 885 if (block_len == 0)886 ; /* hole */887 else if (unlikely(block_len > 2*PAGE_SIZE ||888 (uncompressed && block_len > PAGE_SIZE))) {889 mutex_unlock(&read_mutex);890 pr_err("bad data blocksize %u\n", block_len);891 goto err;892 } else if (uncompressed) {893 memcpy(pgdata,894 cramfs_read(sb, block_start, block_len),895 block_len);896 bytes_filled = block_len;897 } else {898 bytes_filled = cramfs_uncompress_block(pgdata,899 PAGE_SIZE,900 cramfs_read(sb, block_start, block_len),901 block_len);902 }903 mutex_unlock(&read_mutex);904 if (unlikely(bytes_filled < 0))905 goto err;906 }907 908 memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled);909 flush_dcache_folio(folio);910 911 success = true;912err:913 kunmap_local(pgdata);914 folio_end_read(folio, success);915 return 0;916}917 918static const struct address_space_operations cramfs_aops = {919 .read_folio = cramfs_read_folio920};921 922/*923 * Our operations:924 */925 926/*927 * A directory can only readdir928 */929static const struct file_operations cramfs_directory_operations = {930 .llseek = generic_file_llseek,931 .read = generic_read_dir,932 .iterate_shared = cramfs_readdir,933};934 935static const struct inode_operations cramfs_dir_inode_operations = {936 .lookup = cramfs_lookup,937};938 939static const struct super_operations cramfs_ops = {940 .statfs = cramfs_statfs,941};942 943static int cramfs_get_tree(struct fs_context *fc)944{945 int ret = -ENOPROTOOPT;946 947 if (IS_ENABLED(CONFIG_CRAMFS_MTD)) {948 ret = get_tree_mtd(fc, cramfs_mtd_fill_super);949 if (!ret)950 return 0;951 }952 if (IS_ENABLED(CONFIG_CRAMFS_BLOCKDEV))953 ret = get_tree_bdev(fc, cramfs_blkdev_fill_super);954 return ret;955}956 957static const struct fs_context_operations cramfs_context_ops = {958 .get_tree = cramfs_get_tree,959 .reconfigure = cramfs_reconfigure,960};961 962/*963 * Set up the filesystem mount context.964 */965static int cramfs_init_fs_context(struct fs_context *fc)966{967 fc->ops = &cramfs_context_ops;968 return 0;969}970 971static struct file_system_type cramfs_fs_type = {972 .owner = THIS_MODULE,973 .name = "cramfs",974 .init_fs_context = cramfs_init_fs_context,975 .kill_sb = cramfs_kill_sb,976 .fs_flags = FS_REQUIRES_DEV,977};978MODULE_ALIAS_FS("cramfs");979 980static int __init init_cramfs_fs(void)981{982 int rv;983 984 rv = cramfs_uncompress_init();985 if (rv < 0)986 return rv;987 rv = register_filesystem(&cramfs_fs_type);988 if (rv < 0)989 cramfs_uncompress_exit();990 return rv;991}992 993static void __exit exit_cramfs_fs(void)994{995 cramfs_uncompress_exit();996 unregister_filesystem(&cramfs_fs_type);997}998 999module_init(init_cramfs_fs)1000module_exit(exit_cramfs_fs)1001MODULE_DESCRIPTION("Compressed ROM file system support");1002MODULE_LICENSE("GPL");1003