1*68252eb5SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later
207972ddeSPhillip Lougher /*
307972ddeSPhillip Lougher * Squashfs - a compressed read only filesystem for Linux
407972ddeSPhillip Lougher *
507972ddeSPhillip Lougher * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
6d7f2ff67SPhillip Lougher * Phillip Lougher <phillip@squashfs.org.uk>
707972ddeSPhillip Lougher *
807972ddeSPhillip Lougher * dir.c
907972ddeSPhillip Lougher */
1007972ddeSPhillip Lougher
1107972ddeSPhillip Lougher /*
1207972ddeSPhillip Lougher * This file implements code to read directories from disk.
1307972ddeSPhillip Lougher *
1407972ddeSPhillip Lougher * See namei.c for a description of directory organisation on disk.
1507972ddeSPhillip Lougher */
1607972ddeSPhillip Lougher
1707972ddeSPhillip Lougher #include <linux/fs.h>
1807972ddeSPhillip Lougher #include <linux/vfs.h>
1907972ddeSPhillip Lougher #include <linux/slab.h>
2007972ddeSPhillip Lougher
2107972ddeSPhillip Lougher #include "squashfs_fs.h"
2207972ddeSPhillip Lougher #include "squashfs_fs_sb.h"
2307972ddeSPhillip Lougher #include "squashfs_fs_i.h"
2407972ddeSPhillip Lougher #include "squashfs.h"
2507972ddeSPhillip Lougher
2607972ddeSPhillip Lougher static const unsigned char squashfs_filetype_table[] = {
2707972ddeSPhillip Lougher DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_FIFO, DT_SOCK
2807972ddeSPhillip Lougher };
2907972ddeSPhillip Lougher
3007972ddeSPhillip Lougher /*
3107972ddeSPhillip Lougher * Lookup offset (f_pos) in the directory index, returning the
3207972ddeSPhillip Lougher * metadata block containing it.
3307972ddeSPhillip Lougher *
3407972ddeSPhillip Lougher * If we get an error reading the index then return the part of the index
3507972ddeSPhillip Lougher * (if any) we have managed to read - the index isn't essential, just
3607972ddeSPhillip Lougher * quicker.
3707972ddeSPhillip Lougher */
get_dir_index_using_offset(struct super_block * sb,u64 * next_block,int * next_offset,u64 index_start,int index_offset,int i_count,u64 f_pos)3807972ddeSPhillip Lougher static int get_dir_index_using_offset(struct super_block *sb,
3907972ddeSPhillip Lougher u64 *next_block, int *next_offset, u64 index_start, int index_offset,
4007972ddeSPhillip Lougher int i_count, u64 f_pos)
4107972ddeSPhillip Lougher {
4207972ddeSPhillip Lougher struct squashfs_sb_info *msblk = sb->s_fs_info;
4307972ddeSPhillip Lougher int err, i, index, length = 0;
44f960cae5SPhillip Lougher unsigned int size;
4507972ddeSPhillip Lougher struct squashfs_dir_index dir_index;
4607972ddeSPhillip Lougher
4707972ddeSPhillip Lougher TRACE("Entered get_dir_index_using_offset, i_count %d, f_pos %lld\n",
4807972ddeSPhillip Lougher i_count, f_pos);
4907972ddeSPhillip Lougher
5007972ddeSPhillip Lougher /*
5107972ddeSPhillip Lougher * Translate from external f_pos to the internal f_pos. This
5207972ddeSPhillip Lougher * is offset by 3 because we invent "." and ".." entries which are
5307972ddeSPhillip Lougher * not actually stored in the directory.
5407972ddeSPhillip Lougher */
552158d3fdSPhillip Lougher if (f_pos <= 3)
5607972ddeSPhillip Lougher return f_pos;
5707972ddeSPhillip Lougher f_pos -= 3;
5807972ddeSPhillip Lougher
5907972ddeSPhillip Lougher for (i = 0; i < i_count; i++) {
6007972ddeSPhillip Lougher err = squashfs_read_metadata(sb, &dir_index, &index_start,
6107972ddeSPhillip Lougher &index_offset, sizeof(dir_index));
6207972ddeSPhillip Lougher if (err < 0)
6307972ddeSPhillip Lougher break;
6407972ddeSPhillip Lougher
6507972ddeSPhillip Lougher index = le32_to_cpu(dir_index.index);
6607972ddeSPhillip Lougher if (index > f_pos)
6707972ddeSPhillip Lougher /*
6807972ddeSPhillip Lougher * Found the index we're looking for.
6907972ddeSPhillip Lougher */
7007972ddeSPhillip Lougher break;
7107972ddeSPhillip Lougher
72f960cae5SPhillip Lougher size = le32_to_cpu(dir_index.size) + 1;
73f960cae5SPhillip Lougher
74f960cae5SPhillip Lougher /* size should never be larger than SQUASHFS_NAME_LEN */
75f960cae5SPhillip Lougher if (size > SQUASHFS_NAME_LEN)
76f960cae5SPhillip Lougher break;
77f960cae5SPhillip Lougher
7807972ddeSPhillip Lougher err = squashfs_read_metadata(sb, NULL, &index_start,
79f960cae5SPhillip Lougher &index_offset, size);
8007972ddeSPhillip Lougher if (err < 0)
8107972ddeSPhillip Lougher break;
8207972ddeSPhillip Lougher
8307972ddeSPhillip Lougher length = index;
8407972ddeSPhillip Lougher *next_block = le32_to_cpu(dir_index.start_block) +
8507972ddeSPhillip Lougher msblk->directory_table;
8607972ddeSPhillip Lougher }
8707972ddeSPhillip Lougher
8807972ddeSPhillip Lougher *next_offset = (length + *next_offset) % SQUASHFS_METADATA_SIZE;
8907972ddeSPhillip Lougher
9007972ddeSPhillip Lougher /*
9107972ddeSPhillip Lougher * Translate back from internal f_pos to external f_pos.
9207972ddeSPhillip Lougher */
9307972ddeSPhillip Lougher return length + 3;
9407972ddeSPhillip Lougher }
9507972ddeSPhillip Lougher
9607972ddeSPhillip Lougher
squashfs_readdir(struct file * file,struct dir_context * ctx)975f6039ceSAl Viro static int squashfs_readdir(struct file *file, struct dir_context *ctx)
9807972ddeSPhillip Lougher {
99496ad9aaSAl Viro struct inode *inode = file_inode(file);
10007972ddeSPhillip Lougher struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
10107972ddeSPhillip Lougher u64 block = squashfs_i(inode)->start + msblk->directory_table;
1029e012423SPhillip Lougher int offset = squashfs_i(inode)->offset, length, err;
1039e012423SPhillip Lougher unsigned int inode_number, dir_count, size, type;
10407972ddeSPhillip Lougher struct squashfs_dir_header dirh;
10507972ddeSPhillip Lougher struct squashfs_dir_entry *dire;
10607972ddeSPhillip Lougher
10707972ddeSPhillip Lougher TRACE("Entered squashfs_readdir [%llx:%x]\n", block, offset);
10807972ddeSPhillip Lougher
10907972ddeSPhillip Lougher dire = kmalloc(sizeof(*dire) + SQUASHFS_NAME_LEN + 1, GFP_KERNEL);
11007972ddeSPhillip Lougher if (dire == NULL) {
11107972ddeSPhillip Lougher ERROR("Failed to allocate squashfs_dir_entry\n");
11207972ddeSPhillip Lougher goto finish;
11307972ddeSPhillip Lougher }
11407972ddeSPhillip Lougher
11507972ddeSPhillip Lougher /*
11607972ddeSPhillip Lougher * Return "." and ".." entries as the first two filenames in the
11707972ddeSPhillip Lougher * directory. To maximise compression these two entries are not
11807972ddeSPhillip Lougher * stored in the directory, and so we invent them here.
11907972ddeSPhillip Lougher *
12007972ddeSPhillip Lougher * It also means that the external f_pos is offset by 3 from the
12107972ddeSPhillip Lougher * on-disk directory f_pos.
12207972ddeSPhillip Lougher */
1235f6039ceSAl Viro while (ctx->pos < 3) {
12407972ddeSPhillip Lougher char *name;
12507972ddeSPhillip Lougher int i_ino;
12607972ddeSPhillip Lougher
1275f6039ceSAl Viro if (ctx->pos == 0) {
12807972ddeSPhillip Lougher name = ".";
12907972ddeSPhillip Lougher size = 1;
13007972ddeSPhillip Lougher i_ino = inode->i_ino;
13107972ddeSPhillip Lougher } else {
13207972ddeSPhillip Lougher name = "..";
13307972ddeSPhillip Lougher size = 2;
13407972ddeSPhillip Lougher i_ino = squashfs_i(inode)->parent;
13507972ddeSPhillip Lougher }
13607972ddeSPhillip Lougher
1375f6039ceSAl Viro if (!dir_emit(ctx, name, size, i_ino,
1385f6039ceSAl Viro squashfs_filetype_table[1]))
13907972ddeSPhillip Lougher goto finish;
14007972ddeSPhillip Lougher
1415f6039ceSAl Viro ctx->pos += size;
14207972ddeSPhillip Lougher }
14307972ddeSPhillip Lougher
14407972ddeSPhillip Lougher length = get_dir_index_using_offset(inode->i_sb, &block, &offset,
14507972ddeSPhillip Lougher squashfs_i(inode)->dir_idx_start,
14607972ddeSPhillip Lougher squashfs_i(inode)->dir_idx_offset,
14707972ddeSPhillip Lougher squashfs_i(inode)->dir_idx_cnt,
1485f6039ceSAl Viro ctx->pos);
14907972ddeSPhillip Lougher
15007972ddeSPhillip Lougher while (length < i_size_read(inode)) {
15107972ddeSPhillip Lougher /*
15207972ddeSPhillip Lougher * Read directory header
15307972ddeSPhillip Lougher */
15407972ddeSPhillip Lougher err = squashfs_read_metadata(inode->i_sb, &dirh, &block,
15507972ddeSPhillip Lougher &offset, sizeof(dirh));
15607972ddeSPhillip Lougher if (err < 0)
15707972ddeSPhillip Lougher goto failed_read;
15807972ddeSPhillip Lougher
15907972ddeSPhillip Lougher length += sizeof(dirh);
16007972ddeSPhillip Lougher
16107972ddeSPhillip Lougher dir_count = le32_to_cpu(dirh.count) + 1;
16244cff8a9SPhillip Lougher
1634826d83dSAjeet Yadav if (dir_count > SQUASHFS_DIR_COUNT)
16444cff8a9SPhillip Lougher goto failed_read;
16544cff8a9SPhillip Lougher
16607972ddeSPhillip Lougher while (dir_count--) {
16707972ddeSPhillip Lougher /*
16807972ddeSPhillip Lougher * Read directory entry.
16907972ddeSPhillip Lougher */
17007972ddeSPhillip Lougher err = squashfs_read_metadata(inode->i_sb, dire, &block,
17107972ddeSPhillip Lougher &offset, sizeof(*dire));
17207972ddeSPhillip Lougher if (err < 0)
17307972ddeSPhillip Lougher goto failed_read;
17407972ddeSPhillip Lougher
17507972ddeSPhillip Lougher size = le16_to_cpu(dire->size) + 1;
17607972ddeSPhillip Lougher
17744cff8a9SPhillip Lougher /* size should never be larger than SQUASHFS_NAME_LEN */
17844cff8a9SPhillip Lougher if (size > SQUASHFS_NAME_LEN)
17944cff8a9SPhillip Lougher goto failed_read;
18044cff8a9SPhillip Lougher
18107972ddeSPhillip Lougher err = squashfs_read_metadata(inode->i_sb, dire->name,
18207972ddeSPhillip Lougher &block, &offset, size);
18307972ddeSPhillip Lougher if (err < 0)
18407972ddeSPhillip Lougher goto failed_read;
18507972ddeSPhillip Lougher
18607972ddeSPhillip Lougher length += sizeof(*dire) + size;
18707972ddeSPhillip Lougher
1885f6039ceSAl Viro if (ctx->pos >= length)
18907972ddeSPhillip Lougher continue;
19007972ddeSPhillip Lougher
19107972ddeSPhillip Lougher dire->name[size] = '\0';
19207972ddeSPhillip Lougher inode_number = le32_to_cpu(dirh.inode_number) +
19307972ddeSPhillip Lougher ((short) le16_to_cpu(dire->inode_number));
19407972ddeSPhillip Lougher type = le16_to_cpu(dire->type);
19507972ddeSPhillip Lougher
1969e012423SPhillip Lougher if (type > SQUASHFS_MAX_DIR_TYPE)
1979e012423SPhillip Lougher goto failed_read;
1989e012423SPhillip Lougher
1995f6039ceSAl Viro if (!dir_emit(ctx, dire->name, size,
20007972ddeSPhillip Lougher inode_number,
2015f6039ceSAl Viro squashfs_filetype_table[type]))
20207972ddeSPhillip Lougher goto finish;
20307972ddeSPhillip Lougher
2045f6039ceSAl Viro ctx->pos = length;
20507972ddeSPhillip Lougher }
20607972ddeSPhillip Lougher }
20707972ddeSPhillip Lougher
20807972ddeSPhillip Lougher finish:
20907972ddeSPhillip Lougher kfree(dire);
21007972ddeSPhillip Lougher return 0;
21107972ddeSPhillip Lougher
21207972ddeSPhillip Lougher failed_read:
21307972ddeSPhillip Lougher ERROR("Unable to read directory block [%llx:%x]\n", block, offset);
21407972ddeSPhillip Lougher kfree(dire);
21507972ddeSPhillip Lougher return 0;
21607972ddeSPhillip Lougher }
21707972ddeSPhillip Lougher
21807972ddeSPhillip Lougher
21907972ddeSPhillip Lougher const struct file_operations squashfs_dir_ops = {
22007972ddeSPhillip Lougher .read = generic_read_dir,
221d375570fSAl Viro .iterate_shared = squashfs_readdir,
222d375570fSAl Viro .llseek = generic_file_llseek,
22307972ddeSPhillip Lougher };
224