1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Squashfs - a compressed read only filesystem for Linux
4 *
5 * Copyright (c) 2010
6 * Phillip Lougher <phillip@squashfs.org.uk>
7 *
8 * xattr_id.c
9 */
10
11/*
12 * This file implements code to map the 32-bit xattr id stored in the inode
13 * into the on disk location of the xattr data.
14 */
15
16#include <linux/fs.h>
17#include <linux/vfs.h>
18#include <linux/slab.h>
19
20#include "squashfs_fs.h"
21#include "squashfs_fs_sb.h"
22#include "squashfs.h"
23#include "xattr.h"
24
25/*
26 * Map xattr id using the xattr id look up table
27 */
28int squashfs_xattr_lookup(struct super_block *sb, unsigned int index,
29		int *count, unsigned int *size, unsigned long long *xattr)
30{
31	struct squashfs_sb_info *msblk = sb->s_fs_info;
32	int block = SQUASHFS_XATTR_BLOCK(index);
33	int offset = SQUASHFS_XATTR_BLOCK_OFFSET(index);
34	u64 start_block;
35	struct squashfs_xattr_id id;
36	int err;
37
38	if (index >= msblk->xattr_ids)
39		return -EINVAL;
40
41	start_block = le64_to_cpu(msblk->xattr_id_table[block]);
42
43	err = squashfs_read_metadata(sb, &id, &start_block, &offset,
44							sizeof(id));
45	if (err < 0)
46		return err;
47
48	*xattr = le64_to_cpu(id.xattr);
49	*size = le32_to_cpu(id.size);
50	*count = le32_to_cpu(id.count);
51	return 0;
52}
53
54
55/*
56 * Read uncompressed xattr id lookup table indexes from disk into memory
57 */
58__le64 *squashfs_read_xattr_id_table(struct super_block *sb, u64 table_start,
59		u64 *xattr_table_start, unsigned int *xattr_ids)
60{
61	struct squashfs_sb_info *msblk = sb->s_fs_info;
62	unsigned int len, indexes;
63	struct squashfs_xattr_id_table *id_table;
64	__le64 *table;
65	u64 start, end;
66	int n;
67
68	id_table = squashfs_read_table(sb, table_start, sizeof(*id_table));
69	if (IS_ERR(id_table))
70		return (__le64 *) id_table;
71
72	*xattr_table_start = le64_to_cpu(id_table->xattr_table_start);
73	*xattr_ids = le32_to_cpu(id_table->xattr_ids);
74	kfree(id_table);
75
76	/* Sanity check values */
77
78	/* there is always at least one xattr id */
79	if (*xattr_ids == 0)
80		return ERR_PTR(-EINVAL);
81
82	len = SQUASHFS_XATTR_BLOCK_BYTES(*xattr_ids);
83	indexes = SQUASHFS_XATTR_BLOCKS(*xattr_ids);
84
85	/*
86	 * The computed size of the index table (len bytes) should exactly
87	 * match the table start and end points
88	 */
89	start = table_start + sizeof(*id_table);
90	end = msblk->bytes_used;
91
92	if (len != (end - start))
93		return ERR_PTR(-EINVAL);
94
95	table = squashfs_read_table(sb, start, len);
96	if (IS_ERR(table))
97		return table;
98
99	/* table[0], table[1], ... table[indexes - 1] store the locations
100	 * of the compressed xattr id blocks.  Each entry should be less than
101	 * the next (i.e. table[0] < table[1]), and the difference between them
102	 * should be SQUASHFS_METADATA_SIZE or less.  table[indexes - 1]
103	 * should be less than table_start, and again the difference
104	 * shouls be SQUASHFS_METADATA_SIZE or less.
105	 *
106	 * Finally xattr_table_start should be less than table[0].
107	 */
108	for (n = 0; n < (indexes - 1); n++) {
109		start = le64_to_cpu(table[n]);
110		end = le64_to_cpu(table[n + 1]);
111
112		if (start >= end || (end - start) >
113				(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
114			kfree(table);
115			return ERR_PTR(-EINVAL);
116		}
117	}
118
119	start = le64_to_cpu(table[indexes - 1]);
120	if (start >= table_start || (table_start - start) >
121				(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
122		kfree(table);
123		return ERR_PTR(-EINVAL);
124	}
125
126	if (*xattr_table_start >= le64_to_cpu(table[0])) {
127		kfree(table);
128		return ERR_PTR(-EINVAL);
129	}
130
131	return table;
132}
133