// SPDX-License-Identifier: GPL-2.0 /* * linux/fs/ext2/dir.c * * Copyright (C) 1992, 1993, 1994, 1995 * Remy Card (card@masi.ibp.fr) * Laboratoire MASI - Institut Blaise Pascal * Universite Pierre et Marie Curie (Paris VI) * * from * * linux/fs/minix/dir.c * * Copyright (C) 1991, 1992 Linus Torvalds * * ext2 directory handling functions * * Big-endian to little-endian byte-swapping/bitmaps by * David S. Miller (davem@caip.rutgers.edu), 1995 * * All code that works with directory layout had been switched to pagecache * and moved here. AV */ #include "ext2.h" #include <linux/buffer_head.h> #include <linux/pagemap.h> #include <linux/swap.h> #include <linux/iversion.h> typedef struct ext2_dir_entry_2 ext2_dirent; /* * Tests against MAX_REC_LEN etc were put in place for 64k block * sizes; if that is not possible on this arch, we can skip * those tests and speed things up. */ static inline unsigned ext2_rec_len_from_disk(__le16 dlen) { unsigned len = le16_to_cpu(dlen); #if (PAGE_SIZE >= 65536) if (len == EXT2_MAX_REC_LEN) return 1 << 16; #endif return len; } static inline __le16 ext2_rec_len_to_disk(unsigned len) { #if (PAGE_SIZE >= 65536) if (len == (1 << 16)) return cpu_to_le16(EXT2_MAX_REC_LEN); else BUG_ON(len > (1 << 16)); #endif return cpu_to_le16(len); } /* * ext2 uses block-sized chunks. Arguably, sector-sized ones would be * more robust, but we have what we have */ static inline unsigned ext2_chunk_size(struct inode *inode) { return inode->i_sb->s_blocksize; } static inline void ext2_put_page(struct page *page) { kunmap(page); put_page(page); } /* * Return the offset into page `page_nr' of the last valid * byte in that page, plus one. */ static unsigned ext2_last_byte(struct inode *inode, unsigned long page_nr) { unsigned last_byte = inode->i_size; last_byte -= page_nr << PAGE_SHIFT; if (last_byte > PAGE_SIZE) last_byte = PAGE_SIZE; return last_byte; } static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len) { struct address_space *mapping = page->mapping; struct inode *dir = mapping->host; int err = 0; inode_inc_iversion(dir); block_write_end(NULL, mapping, pos, len, len, page, NULL); if (pos+len > dir->i_size) { i_size_write(dir, pos+len); mark_inode_dirty(dir); } if (IS_DIRSYNC(dir)) { err = write_one_page(page); if (!err) err = sync_inode_metadata(dir, 1); } else { unlock_page(page); } return err; } static bool ext2_check_page(struct page *page, int quiet) { struct inode *dir = page->mapping->host; struct super_block *sb = dir->i_sb; unsigned chunk_size = ext2_chunk_size(dir); char *kaddr = page_address(page); u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count); unsigned offs, rec_len; unsigned limit = PAGE_SIZE; ext2_dirent *p; char *error; if ((dir->i_size >> PAGE_SHIFT) == page->index) { limit = dir->i_size & ~PAGE_MASK; if (limit & (chunk_size - 1)) goto Ebadsize; if (!limit) goto out; } for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) { p = (ext2_dirent *)(kaddr + offs); rec_len = ext2_rec_len_from_disk(p->rec_len); if (unlikely(rec_len < EXT2_DIR_REC_LEN(1))) goto Eshort; if (unlikely(rec_len & 3)) goto Ealign; if (unlikely(rec_len < EXT2_DIR_REC_LEN(p->name_len))) goto Enamelen; if (unlikely(((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))) goto Espan; if (unlikely(le32_to_cpu(p->inode) > max_inumber)) goto Einumber; } if (offs != limit) goto Eend; out: SetPageChecked(page); return true; /* Too bad, we had an error */ Ebadsize: if (!quiet) ext2_error(sb, __func__, "size of directory #%lu is not a multiple " "of chunk size", dir->i_ino); goto fail; Eshort: error = "rec_len is smaller than minimal"; goto bad_entry; Ealign: error = "unaligned directory entry"; goto bad_entry; Enamelen: error = "rec_len is too small for name_len"; goto bad_entry; Espan: error = "directory entry across blocks"; goto bad_entry; Einumber: error = "inode out of bounds"; bad_entry: if (!quiet) ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - " "offset=%lu, inode=%lu, rec_len=%d, name_len=%d", dir->i_ino, error, (page->index<<PAGE_SHIFT)+offs, (unsigned long) le32_to_cpu(p->inode), rec_len, p->name_len); goto fail; Eend: if (!quiet) { p = (ext2_dirent *)(kaddr + offs); ext2_error(sb, "ext2_check_page", "entry in directory #%lu spans the page boundary" "offset=%lu, inode=%lu", dir->i_ino, (page->index<<PAGE_SHIFT)+offs, (unsigned long) le32_to_cpu(p->inode)); } fail: SetPageError(page); return false; } static struct page * ext2_get_page(struct inode *dir, unsigned long n, int quiet) { struct address_space *mapping = dir->i_mapping; struct page *page = read_mapping_page(mapping, n, NULL); if (!IS_ERR(page)) { kmap(page); if (unlikely(!PageChecked(page))) { if (PageError(page) || !ext2_check_page(page, quiet)) goto fail; } } return page; fail: ext2_put_page(page); return ERR_PTR(-EIO); } /* * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure. * * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller. */ static inline int ext2_match (int len, const char * const name, struct ext2_dir_entry_2 * de) { if (len != de->name_len) return 0; if (!de->inode) return 0; return !memcmp(name, de->name, len); } /* * p is at least 6 bytes before the end of page */ static inline ext2_dirent *ext2_next_entry(ext2_dirent *p) { return (ext2_dirent *)((char *)p + ext2_rec_len_from_disk(p->rec_len)); } static inline unsigned ext2_validate_entry(char *base, unsigned offset, unsigned mask) { ext2_dirent *de = (ext2_dirent*)(base + offset); ext2_dirent *p = (ext2_dirent*)(base + (offset&mask)); while ((char*)p < (char*)de) { if (p->rec_len == 0) break; p = ext2_next_entry(p); } return (char *)p - base; } static unsigned char ext2_filetype_table[EXT2_FT_MAX] = { [EXT2_FT_UNKNOWN] = DT_UNKNOWN, [EXT2_FT_REG_FILE] = DT_REG, [EXT2_FT_DIR] = DT_DIR, [EXT2_FT_CHRDEV] = DT_CHR, [EXT2_FT_BLKDEV] = DT_BLK, [EXT2_FT_FIFO] = DT_FIFO, [EXT2_FT_SOCK] = DT_SOCK, [EXT2_FT_SYMLINK] = DT_LNK, }; #define S_SHIFT 12 static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = { [S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE, [S_IFDIR >> S_SHIFT] = EXT2_FT_DIR, [S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV, [S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV, [S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO, [S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK, [S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK, }; static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode) { umode_t mode = inode->i_mode; if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE)) de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT]; else de->file_type = 0; } static int ext2_readdir(struct file *file, struct dir_context *ctx) { loff_t pos = ctx->pos; struct inode *inode = file_inode(file); struct super_block *sb = inode->i_sb; unsigned int offset = pos & ~PAGE_MASK; unsigned long n = pos >> PAGE_SHIFT; unsigned long npages = dir_pages(inode); unsigned chunk_mask = ~(ext2_chunk_size(inode)-1); unsigned char *types = NULL; bool need_revalidate = !inode_eq_iversion(inode, file->f_version); if (pos > inode->i_size - EXT2_DIR_REC_LEN(1)) return 0; if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE)) types = ext2_filetype_table; for ( ; n < npages; n++, offset = 0) { char *kaddr, *limit; ext2_dirent *de; struct page *page = ext2_get_page(inode, n, 0); if (IS_ERR(page)) { ext2_error(sb, __func__, "bad page in #%lu", inode->i_ino); ctx->pos += PAGE_SIZE - offset; return PTR_ERR(page); } kaddr = page_address(page); if (unlikely(need_revalidate)) { if (offset) { offset = ext2_validate_entry(kaddr, offset, chunk_mask); ctx->pos = (n<<PAGE_SHIFT) + offset; } file->f_version = inode_query_iversion(inode); need_revalidate = false; } de = (ext2_dirent *)(kaddr+offset); limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1); for ( ;(char*)de <= limit; de = ext2_next_entry(de)) { if (de->rec_len == 0) { ext2_error(sb, __func__, "zero-length directory entry"); ext2_put_page(page); return -EIO; } if (de->inode) { unsigned char d_type = DT_UNKNOWN; if (types && de->file_type < EXT2_FT_MAX) d_type = types[de->file_type]; if (!dir_emit(ctx, de->name, de->name_len, le32_to_cpu(de->inode), d_type)) { ext2_put_page(page); return 0; } } ctx->pos += ext2_rec_len_from_disk(de->rec_len); } ext2_put_page(page); } return 0; } /* * ext2_find_entry() * * finds an entry in the specified directory with the wanted name. It * returns the page in which the entry was found (as a parameter - res_page), * and the entry itself. Page is returned mapped and unlocked. * Entry is guaranteed to be valid. */ struct ext2_dir_entry_2 *ext2_find_entry (struct inode *dir, const struct qstr *child, struct page **res_page) { const char *name = child->name; int namelen = child->len; unsigned reclen = EXT2_DIR_REC_LEN(namelen); unsigned long start, n; unsigned long npages = dir_pages(dir); struct page *page = NULL; struct ext2_inode_info *ei = EXT2_I(dir); ext2_dirent * de; int dir_has_error = 0; if (npages == 0) goto out; /* OFFSET_CACHE */ *res_page = NULL; start = ei->i_dir_start_lookup; if (start >= npages) start = 0; n = start; do { char *kaddr; page = ext2_get_page(dir, n, dir_has_error); if (!IS_ERR(page)) { kaddr = page_address(page); de = (ext2_dirent *) kaddr; kaddr += ext2_last_byte(dir, n) - reclen; while ((char *) de <= kaddr) { if (de->rec_len == 0) { ext2_error(dir->i_sb, __func__, "zero-length directory entry"); ext2_put_page(page); goto out; } if (ext2_match (namelen, name, de)) goto found; de = ext2_next_entry(de); } ext2_put_page(page); } else dir_has_error = 1; if (++n >= npages) n = 0; /* next page is past the blocks we've got */ if (unlikely(n > (dir->i_blocks >> (PAGE_SHIFT - 9)))) { ext2_error(dir->i_sb, __func__, "dir %lu size %lld exceeds block count %llu", dir->i_ino, dir->i_size, (unsigned long long)dir->i_blocks); goto out; } } while (n != start); out: return NULL; found: *res_page = page; ei->i_dir_start_lookup = n; return de; } struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p) { struct page *page = ext2_get_page(dir, 0, 0); ext2_dirent *de = NULL; if (!IS_ERR(page)) { de = ext2_next_entry((ext2_dirent *) page_address(page)); *p = page; } return de; } ino_t ext2_inode_by_name(struct inode *dir, const struct qstr *child) { ino_t res = 0; struct ext2_dir_entry_2 *de; struct page *page; de = ext2_find_entry (dir, child, &page); if (de) { res = le32_to_cpu(de->inode); ext2_put_page(page); } return res; } static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len) { return __block_write_begin(page, pos, len, ext2_get_block); } /* Releases the page */ void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de, struct page *page, struct inode *inode, int update_times) { loff_t pos = page_offset(page) + (char *) de - (char *) page_address(page); unsigned len = ext2_rec_len_from_disk(de->rec_len); int err; lock_page(page); err = ext2_prepare_chunk(page, pos, len); BUG_ON(err); de->inode = cpu_to_le32(inode->i_ino); ext2_set_de_type(de, inode); err = ext2_commit_chunk(page, pos, len); ext2_put_page(page); if (update_times) dir->i_mtime = dir->i_ctime = current_time(dir); EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; mark_inode_dirty(dir); } /* * Parent is locked. */ int ext2_add_link (struct dentry *dentry, struct inode *inode) { struct inode *dir = d_inode(dentry->d_parent); const char *name = dentry->d_name.name; int namelen = dentry->d_name.len; unsigned chunk_size = ext2_chunk_size(dir); unsigned reclen = EXT2_DIR_REC_LEN(namelen); unsigned short rec_len, name_len; struct page *page = NULL; ext2_dirent * de; unsigned long npages = dir_pages(dir); unsigned long n; char *kaddr; loff_t pos; int err; /* * We take care of directory expansion in the same loop. * This code plays outside i_size, so it locks the page * to protect that region. */ for (n = 0; n <= npages; n++) { char *dir_end; page = ext2_get_page(dir, n, 0); err = PTR_ERR(page); if (IS_ERR(page)) goto out; lock_page(page); kaddr = page_address(page); dir_end = kaddr + ext2_last_byte(dir, n); de = (ext2_dirent *)kaddr; kaddr += PAGE_SIZE - reclen; while ((char *)de <= kaddr) { if ((char *)de == dir_end) { /* We hit i_size */ name_len = 0; rec_len = chunk_size; de->rec_len = ext2_rec_len_to_disk(chunk_size); de->inode = 0; goto got_it; } if (de->rec_len == 0) { ext2_error(dir->i_sb, __func__, "zero-length directory entry"); err = -EIO; goto out_unlock; } err = -EEXIST; if (ext2_match (namelen, name, de)) goto out_unlock; name_len = EXT2_DIR_REC_LEN(de->name_len); rec_len = ext2_rec_len_from_disk(de->rec_len); if (!de->inode && rec_len >= reclen) goto got_it; if (rec_len >= name_len + reclen) goto got_it; de = (ext2_dirent *) ((char *) de + rec_len); } unlock_page(page); ext2_put_page(page); } BUG(); return -EINVAL; got_it: pos = page_offset(page) + (char*)de - (char*)page_address(page); err = ext2_prepare_chunk(page, pos, rec_len); if (err) goto out_unlock; if (de->inode) { ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len); de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len); de->rec_len = ext2_rec_len_to_disk(name_len); de = de1; } de->name_len = namelen; memcpy(de->name, name, namelen); de->inode = cpu_to_le32(inode->i_ino); ext2_set_de_type (de, inode); err = ext2_commit_chunk(page, pos, rec_len); dir->i_mtime = dir->i_ctime = current_time(dir); EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL; mark_inode_dirty(dir); /* OFFSET_CACHE */ out_put: ext2_put_page(page); out: return err; out_unlock: unlock_page(page); goto out_put; } /* * ext2_delete_entry deletes a directory entry by merging it with the * previous entry. Page is up-to-date. Releases the page. */ int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page ) { struct inode *inode = page->mapping->host; char *kaddr = page_address(page); unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1); unsigned to = ((char *)dir - kaddr) + ext2_rec_len_from_disk(dir->rec_len); loff_t pos; ext2_dirent * pde = NULL; ext2_dirent * de = (ext2_dirent *) (kaddr + from); int err; while ((char*)de < (char*)dir) { if (de->rec_len == 0) { ext2_error(inode->i_sb, __func__, "zero-length directory entry"); err = -EIO; goto out; } pde = de; de = ext2_next_entry(de); } if (pde) from = (char*)pde - (char*)page_address(page); pos = page_offset(page) + from; lock_page(page); err = ext2_prepare_chunk(page, pos, to - from); BUG_ON(err); if (pde) pde->rec_len = ext2_rec_len_to_disk(to - from); dir->inode = 0; err = ext2_commit_chunk(page, pos, to - from); inode->i_ctime = inode->i_mtime = current_time(inode); EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL; mark_inode_dirty(inode); out: ext2_put_page(page); return err; } /* * Set the first fragment of directory. */ int ext2_make_empty(struct inode *inode, struct inode *parent) { struct page *page = grab_cache_page(inode->i_mapping, 0); unsigned chunk_size = ext2_chunk_size(inode); struct ext2_dir_entry_2 * de; int err; void *kaddr; if (!page) return -ENOMEM; err = ext2_prepare_chunk(page, 0, chunk_size); if (err) { unlock_page(page); goto fail; } kaddr = kmap_atomic(page); memset(kaddr, 0, chunk_size); de = (struct ext2_dir_entry_2 *)kaddr; de->name_len = 1; de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1)); memcpy (de->name, ".\0\0", 4); de->inode = cpu_to_le32(inode->i_ino); ext2_set_de_type (de, inode); de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1)); de->name_len = 2; de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1)); de->inode = cpu_to_le32(parent->i_ino); memcpy (de->name, "..\0", 4); ext2_set_de_type (de, inode); kunmap_atomic(kaddr); err = ext2_commit_chunk(page, 0, chunk_size); fail: put_page(page); return err; } /* * routine to check that the specified directory is empty (for rmdir) */ int ext2_empty_dir (struct inode * inode) { struct page *page = NULL; unsigned long i, npages = dir_pages(inode); int dir_has_error = 0; for (i = 0; i < npages; i++) { char *kaddr; ext2_dirent * de; page = ext2_get_page(inode, i, dir_has_error); if (IS_ERR(page)) { dir_has_error = 1; continue; } kaddr = page_address(page); de = (ext2_dirent *)kaddr; kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1); while ((char *)de <= kaddr) { if (de->rec_len == 0) { ext2_error(inode->i_sb, __func__, "zero-length directory entry"); printk("kaddr=%p, de=%p\n", kaddr, de); goto not_empty; } if (de->inode != 0) { /* check for . and .. */ if (de->name[0] != '.') goto not_empty; if (de->name_len > 2) goto not_empty; if (de->name_len < 2) { if (de->inode != cpu_to_le32(inode->i_ino)) goto not_empty; } else if (de->name[1] != '.') goto not_empty; } de = ext2_next_entry(de); } ext2_put_page(page); } return 1; not_empty: ext2_put_page(page); return 0; } const struct file_operations ext2_dir_operations = { .llseek = generic_file_llseek, .read = generic_read_dir, .iterate_shared = ext2_readdir, .unlocked_ioctl = ext2_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = ext2_compat_ioctl, #endif .fsync = ext2_fsync, };