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 */
28 int 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
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