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