Commit | Line | Data |
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68252eb5 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
8256c8f6 PL |
2 | /* |
3 | * Squashfs - a compressed read only filesystem for Linux | |
4 | * | |
5 | * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008 | |
d7f2ff67 | 6 | * Phillip Lougher <phillip@squashfs.org.uk> |
8256c8f6 | 7 | * |
8256c8f6 PL |
8 | * id.c |
9 | */ | |
10 | ||
11 | /* | |
12 | * This file implements code to handle uids and gids. | |
13 | * | |
14 | * For space efficiency regular files store uid and gid indexes, which are | |
15 | * converted to 32-bit uids/gids using an id look up table. This table is | |
16 | * stored compressed into metadata blocks. A second index table is used to | |
17 | * locate these. This second index table for speed of access (and because it | |
18 | * is small) is read at mount time and cached in memory. | |
19 | */ | |
20 | ||
21 | #include <linux/fs.h> | |
22 | #include <linux/vfs.h> | |
23 | #include <linux/slab.h> | |
8256c8f6 PL |
24 | |
25 | #include "squashfs_fs.h" | |
26 | #include "squashfs_fs_sb.h" | |
8256c8f6 PL |
27 | #include "squashfs.h" |
28 | ||
29 | /* | |
30 | * Map uid/gid index into real 32-bit uid/gid using the id look up table | |
31 | */ | |
32 | int squashfs_get_id(struct super_block *sb, unsigned int index, | |
33 | unsigned int *id) | |
34 | { | |
35 | struct squashfs_sb_info *msblk = sb->s_fs_info; | |
36 | int block = SQUASHFS_ID_BLOCK(index); | |
37 | int offset = SQUASHFS_ID_BLOCK_OFFSET(index); | |
f37aa4c7 | 38 | u64 start_block; |
8256c8f6 PL |
39 | __le32 disk_id; |
40 | int err; | |
41 | ||
f37aa4c7 PL |
42 | if (index >= msblk->ids) |
43 | return -EINVAL; | |
44 | ||
45 | start_block = le64_to_cpu(msblk->id_table[block]); | |
46 | ||
8256c8f6 PL |
47 | err = squashfs_read_metadata(sb, &disk_id, &start_block, &offset, |
48 | sizeof(disk_id)); | |
49 | if (err < 0) | |
50 | return err; | |
51 | ||
52 | *id = le32_to_cpu(disk_id); | |
53 | return 0; | |
54 | } | |
55 | ||
56 | ||
57 | /* | |
58 | * Read uncompressed id lookup table indexes from disk into memory | |
59 | */ | |
60 | __le64 *squashfs_read_id_index_table(struct super_block *sb, | |
37986f63 | 61 | u64 id_table_start, u64 next_table, unsigned short no_ids) |
8256c8f6 PL |
62 | { |
63 | unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids); | |
f37aa4c7 PL |
64 | unsigned int indexes = SQUASHFS_ID_BLOCKS(no_ids); |
65 | int n; | |
37986f63 | 66 | __le64 *table; |
f37aa4c7 | 67 | u64 start, end; |
8256c8f6 PL |
68 | |
69 | TRACE("In read_id_index_table, length %d\n", length); | |
70 | ||
37986f63 PL |
71 | /* Sanity check values */ |
72 | ||
73 | /* there should always be at least one id */ | |
74 | if (no_ids == 0) | |
75 | return ERR_PTR(-EINVAL); | |
76 | ||
77 | /* | |
f37aa4c7 PL |
78 | * The computed size of the index table (length bytes) should exactly |
79 | * match the table start and end points | |
37986f63 | 80 | */ |
f37aa4c7 | 81 | if (length != (next_table - id_table_start)) |
37986f63 PL |
82 | return ERR_PTR(-EINVAL); |
83 | ||
84 | table = squashfs_read_table(sb, id_table_start, length); | |
f37aa4c7 PL |
85 | if (IS_ERR(table)) |
86 | return table; | |
37986f63 PL |
87 | |
88 | /* | |
f37aa4c7 PL |
89 | * table[0], table[1], ... table[indexes - 1] store the locations |
90 | * of the compressed id blocks. Each entry should be less than | |
91 | * the next (i.e. table[0] < table[1]), and the difference between them | |
92 | * should be SQUASHFS_METADATA_SIZE or less. table[indexes - 1] | |
93 | * should be less than id_table_start, and again the difference | |
94 | * should be SQUASHFS_METADATA_SIZE or less | |
37986f63 | 95 | */ |
f37aa4c7 PL |
96 | for (n = 0; n < (indexes - 1); n++) { |
97 | start = le64_to_cpu(table[n]); | |
98 | end = le64_to_cpu(table[n + 1]); | |
99 | ||
8b44ca2b PL |
100 | if (start >= end || (end - start) > |
101 | (SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) { | |
f37aa4c7 PL |
102 | kfree(table); |
103 | return ERR_PTR(-EINVAL); | |
104 | } | |
105 | } | |
106 | ||
107 | start = le64_to_cpu(table[indexes - 1]); | |
8b44ca2b PL |
108 | if (start >= id_table_start || (id_table_start - start) > |
109 | (SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) { | |
37986f63 PL |
110 | kfree(table); |
111 | return ERR_PTR(-EINVAL); | |
112 | } | |
113 | ||
114 | return table; | |
8256c8f6 | 115 | } |