1 // SPDX-License-Identifier: GPL-2.0-or-later <<
2 /* 1 /*
3 * Squashfs - a compressed read only filesyste 2 * Squashfs - a compressed read only filesystem for Linux
4 * 3 *
5 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 4 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
6 * Phillip Lougher <phillip@squashfs.org.uk> 5 * Phillip Lougher <phillip@squashfs.org.uk>
>> 6 *
>> 7 * This program is free software; you can redistribute it and/or
>> 8 * modify it under the terms of the GNU General Public License
>> 9 * as published by the Free Software Foundation; either version 2,
>> 10 * or (at your option) any later version.
>> 11 *
>> 12 * This program is distributed in the hope that it will be useful,
>> 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> 15 * GNU General Public License for more details.
>> 16 *
>> 17 * You should have received a copy of the GNU General Public License
>> 18 * along with this program; if not, write to the Free Software
>> 19 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
7 * 20 *
8 * fragment.c 21 * fragment.c
9 */ 22 */
10 23
11 /* 24 /*
12 * This file implements code to handle compres 25 * This file implements code to handle compressed fragments (tail-end packed
13 * datablocks). 26 * datablocks).
14 * 27 *
15 * Regular files contain a fragment index whic 28 * Regular files contain a fragment index which is mapped to a fragment
16 * location on disk and compressed size using 29 * location on disk and compressed size using a fragment lookup table.
17 * Like everything in Squashfs this fragment l 30 * Like everything in Squashfs this fragment lookup table is itself stored
18 * compressed into metadata blocks. A second 31 * compressed into metadata blocks. A second index table is used to locate
19 * these. This second index table for speed o 32 * these. This second index table for speed of access (and because it
20 * is small) is read at mount time and cached 33 * is small) is read at mount time and cached in memory.
21 */ 34 */
22 35
23 #include <linux/fs.h> 36 #include <linux/fs.h>
24 #include <linux/vfs.h> 37 #include <linux/vfs.h>
25 #include <linux/slab.h> 38 #include <linux/slab.h>
26 39
27 #include "squashfs_fs.h" 40 #include "squashfs_fs.h"
28 #include "squashfs_fs_sb.h" 41 #include "squashfs_fs_sb.h"
29 #include "squashfs.h" 42 #include "squashfs.h"
30 43
31 /* 44 /*
32 * Look-up fragment using the fragment index t 45 * Look-up fragment using the fragment index table. Return the on disk
33 * location of the fragment and its compressed 46 * location of the fragment and its compressed size
34 */ 47 */
35 int squashfs_frag_lookup(struct super_block *s 48 int squashfs_frag_lookup(struct super_block *sb, unsigned int fragment,
36 u64 *fragment_ 49 u64 *fragment_block)
37 { 50 {
38 struct squashfs_sb_info *msblk = sb->s 51 struct squashfs_sb_info *msblk = sb->s_fs_info;
39 int block, offset, size; 52 int block, offset, size;
40 struct squashfs_fragment_entry fragmen 53 struct squashfs_fragment_entry fragment_entry;
41 u64 start_block; 54 u64 start_block;
42 55
43 if (fragment >= msblk->fragments) 56 if (fragment >= msblk->fragments)
44 return -EIO; 57 return -EIO;
45 block = SQUASHFS_FRAGMENT_INDEX(fragme 58 block = SQUASHFS_FRAGMENT_INDEX(fragment);
46 offset = SQUASHFS_FRAGMENT_INDEX_OFFSE 59 offset = SQUASHFS_FRAGMENT_INDEX_OFFSET(fragment);
47 60
48 start_block = le64_to_cpu(msblk->fragm 61 start_block = le64_to_cpu(msblk->fragment_index[block]);
49 62
50 size = squashfs_read_metadata(sb, &fra 63 size = squashfs_read_metadata(sb, &fragment_entry, &start_block,
51 &offse 64 &offset, sizeof(fragment_entry));
52 if (size < 0) 65 if (size < 0)
53 return size; 66 return size;
54 67
55 *fragment_block = le64_to_cpu(fragment 68 *fragment_block = le64_to_cpu(fragment_entry.start_block);
56 return squashfs_block_size(fragment_en 69 return squashfs_block_size(fragment_entry.size);
57 } 70 }
58 71
59 72
60 /* 73 /*
61 * Read the uncompressed fragment lookup table 74 * Read the uncompressed fragment lookup table indexes off disk into memory
62 */ 75 */
63 __le64 *squashfs_read_fragment_index_table(str 76 __le64 *squashfs_read_fragment_index_table(struct super_block *sb,
64 u64 fragment_table_start, u64 next_tab 77 u64 fragment_table_start, u64 next_table, unsigned int fragments)
65 { 78 {
66 unsigned int length = SQUASHFS_FRAGMEN 79 unsigned int length = SQUASHFS_FRAGMENT_INDEX_BYTES(fragments);
67 __le64 *table; 80 __le64 *table;
68 81
69 /* 82 /*
70 * Sanity check, length bytes should n 83 * Sanity check, length bytes should not extend into the next table -
71 * this check also traps instances whe 84 * this check also traps instances where fragment_table_start is
72 * incorrectly larger than the next ta 85 * incorrectly larger than the next table start
73 */ 86 */
74 if (fragment_table_start + length > ne 87 if (fragment_table_start + length > next_table)
75 return ERR_PTR(-EINVAL); 88 return ERR_PTR(-EINVAL);
76 89
77 table = squashfs_read_table(sb, fragme 90 table = squashfs_read_table(sb, fragment_table_start, length);
78 91
79 /* 92 /*
80 * table[0] points to the first fragme 93 * table[0] points to the first fragment table metadata block, this
81 * should be less than fragment_table_ 94 * should be less than fragment_table_start
82 */ 95 */
83 if (!IS_ERR(table) && le64_to_cpu(tabl 96 if (!IS_ERR(table) && le64_to_cpu(table[0]) >= fragment_table_start) {
84 kfree(table); 97 kfree(table);
85 return ERR_PTR(-EINVAL); 98 return ERR_PTR(-EINVAL);
86 } 99 }
87 100
88 return table; 101 return table;
89 } 102 }
90 103
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