1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Squashfs - a compressed read only filesystem for Linux
4 *
5 * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
6 * Phillip Lougher <phillip@squashfs.org.uk>
7 *
8 * decompressor.c
9 */
10
11 #include <linux/types.h>
12 #include <linux/mutex.h>
13 #include <linux/slab.h>
14 #include <linux/buffer_head.h>
15
16 #include "squashfs_fs.h"
17 #include "squashfs_fs_sb.h"
18 #include "decompressor.h"
19 #include "squashfs.h"
20 #include "page_actor.h"
21
22 /*
23 * This file (and decompressor.h) implements a decompressor framework for
24 * Squashfs, allowing multiple decompressors to be easily supported
25 */
26
27 static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
28 NULL, NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
29 };
30
31 #ifndef CONFIG_SQUASHFS_LZ4
32 static const struct squashfs_decompressor squashfs_lz4_comp_ops = {
33 NULL, NULL, NULL, NULL, LZ4_COMPRESSION, "lz4", 0
34 };
35 #endif
36
37 #ifndef CONFIG_SQUASHFS_LZO
38 static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
39 NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
40 };
41 #endif
42
43 #ifndef CONFIG_SQUASHFS_XZ
44 static const struct squashfs_decompressor squashfs_xz_comp_ops = {
45 NULL, NULL, NULL, NULL, XZ_COMPRESSION, "xz", 0
46 };
47 #endif
48
49 #ifndef CONFIG_SQUASHFS_ZLIB
50 static const struct squashfs_decompressor squashfs_zlib_comp_ops = {
51 NULL, NULL, NULL, NULL, ZLIB_COMPRESSION, "zlib", 0
52 };
53 #endif
54
55 #ifndef CONFIG_SQUASHFS_ZSTD
56 static const struct squashfs_decompressor squashfs_zstd_comp_ops = {
57 NULL, NULL, NULL, NULL, ZSTD_COMPRESSION, "zstd", 0
58 };
59 #endif
60
61 static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
62 NULL, NULL, NULL, NULL, 0, "unknown", 0
63 };
64
65 static const struct squashfs_decompressor *decompressor[] = {
66 &squashfs_zlib_comp_ops,
67 &squashfs_lz4_comp_ops,
68 &squashfs_lzo_comp_ops,
69 &squashfs_xz_comp_ops,
70 &squashfs_lzma_unsupported_comp_ops,
71 &squashfs_zstd_comp_ops,
72 &squashfs_unknown_comp_ops
73 };
74
75
squashfs_lookup_decompressor(int id)76 const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
77 {
78 int i;
79
80 for (i = 0; decompressor[i]->id; i++)
81 if (id == decompressor[i]->id)
82 break;
83
84 return decompressor[i];
85 }
86
87
get_comp_opts(struct super_block * sb,unsigned short flags)88 static void *get_comp_opts(struct super_block *sb, unsigned short flags)
89 {
90 struct squashfs_sb_info *msblk = sb->s_fs_info;
91 void *buffer = NULL, *comp_opts;
92 struct squashfs_page_actor *actor = NULL;
93 int length = 0;
94
95 /*
96 * Read decompressor specific options from file system if present
97 */
98 if (SQUASHFS_COMP_OPTS(flags)) {
99 buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
100 if (buffer == NULL) {
101 comp_opts = ERR_PTR(-ENOMEM);
102 goto out;
103 }
104
105 actor = squashfs_page_actor_init(&buffer, 1, 0);
106 if (actor == NULL) {
107 comp_opts = ERR_PTR(-ENOMEM);
108 goto out;
109 }
110
111 length = squashfs_read_data(sb,
112 sizeof(struct squashfs_super_block), 0, NULL, actor);
113
114 if (length < 0) {
115 comp_opts = ERR_PTR(length);
116 goto out;
117 }
118 }
119
120 comp_opts = squashfs_comp_opts(msblk, buffer, length);
121
122 out:
123 kfree(actor);
124 kfree(buffer);
125 return comp_opts;
126 }
127
128
squashfs_decompressor_setup(struct super_block * sb,unsigned short flags)129 void *squashfs_decompressor_setup(struct super_block *sb, unsigned short flags)
130 {
131 struct squashfs_sb_info *msblk = sb->s_fs_info;
132 void *stream, *comp_opts = get_comp_opts(sb, flags);
133
134 if (IS_ERR(comp_opts))
135 return comp_opts;
136
137 stream = squashfs_decompressor_create(msblk, comp_opts);
138 if (IS_ERR(stream))
139 kfree(comp_opts);
140
141 return stream;
142 }
143