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1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2013, 2014
4  * Phillip Lougher <phillip@squashfs.org.uk>
5  */
6 
7 #include <linux/bio.h>
8 #include <linux/mutex.h>
9 #include <linux/slab.h>
10 #include <linux/vmalloc.h>
11 #include <linux/lz4.h>
12 
13 #include "squashfs_fs.h"
14 #include "squashfs_fs_sb.h"
15 #include "squashfs.h"
16 #include "decompressor.h"
17 #include "page_actor.h"
18 
19 #define LZ4_LEGACY	1
20 
21 struct lz4_comp_opts {
22 	__le32 version;
23 	__le32 flags;
24 };
25 
26 struct squashfs_lz4 {
27 	void *input;
28 	void *output;
29 };
30 
31 
lz4_comp_opts(struct squashfs_sb_info * msblk,void * buff,int len)32 static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
33 	void *buff, int len)
34 {
35 	struct lz4_comp_opts *comp_opts = buff;
36 
37 	/* LZ4 compressed filesystems always have compression options */
38 	if (comp_opts == NULL || len < sizeof(*comp_opts))
39 		return ERR_PTR(-EIO);
40 
41 	if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
42 		/* LZ4 format currently used by the kernel is the 'legacy'
43 		 * format */
44 		ERROR("Unknown LZ4 version\n");
45 		return ERR_PTR(-EINVAL);
46 	}
47 
48 	return NULL;
49 }
50 
51 
lz4_init(struct squashfs_sb_info * msblk,void * buff)52 static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
53 {
54 	int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
55 	struct squashfs_lz4 *stream;
56 
57 	stream = kzalloc(sizeof(*stream), GFP_KERNEL);
58 	if (stream == NULL)
59 		goto failed;
60 	stream->input = vmalloc(block_size);
61 	if (stream->input == NULL)
62 		goto failed2;
63 	stream->output = vmalloc(block_size);
64 	if (stream->output == NULL)
65 		goto failed3;
66 
67 	return stream;
68 
69 failed3:
70 	vfree(stream->input);
71 failed2:
72 	kfree(stream);
73 failed:
74 	ERROR("Failed to initialise LZ4 decompressor\n");
75 	return ERR_PTR(-ENOMEM);
76 }
77 
78 
lz4_free(void * strm)79 static void lz4_free(void *strm)
80 {
81 	struct squashfs_lz4 *stream = strm;
82 
83 	if (stream) {
84 		vfree(stream->input);
85 		vfree(stream->output);
86 	}
87 	kfree(stream);
88 }
89 
90 
lz4_uncompress(struct squashfs_sb_info * msblk,void * strm,struct bio * bio,int offset,int length,struct squashfs_page_actor * output)91 static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
92 	struct bio *bio, int offset, int length,
93 	struct squashfs_page_actor *output)
94 {
95 	struct bvec_iter_all iter_all = {};
96 	struct bio_vec *bvec = bvec_init_iter_all(&iter_all);
97 	struct squashfs_lz4 *stream = strm;
98 	void *buff = stream->input, *data;
99 	int bytes = length, res;
100 
101 	while (bio_next_segment(bio, &iter_all)) {
102 		int avail = min(bytes, ((int)bvec->bv_len) - offset);
103 
104 		data = bvec_virt(bvec);
105 		memcpy(buff, data + offset, avail);
106 		buff += avail;
107 		bytes -= avail;
108 		offset = 0;
109 	}
110 
111 	res = LZ4_decompress_safe(stream->input, stream->output,
112 		length, output->length);
113 
114 	if (res < 0)
115 		return -EIO;
116 
117 	bytes = res;
118 	data = squashfs_first_page(output);
119 	buff = stream->output;
120 	while (data) {
121 		if (bytes <= PAGE_SIZE) {
122 			if (!IS_ERR(data))
123 				memcpy(data, buff, bytes);
124 			break;
125 		}
126 		if (!IS_ERR(data))
127 			memcpy(data, buff, PAGE_SIZE);
128 		buff += PAGE_SIZE;
129 		bytes -= PAGE_SIZE;
130 		data = squashfs_next_page(output);
131 	}
132 	squashfs_finish_page(output);
133 
134 	return res;
135 }
136 
137 const struct squashfs_decompressor squashfs_lz4_comp_ops = {
138 	.init = lz4_init,
139 	.comp_opts = lz4_comp_opts,
140 	.free = lz4_free,
141 	.decompress = lz4_uncompress,
142 	.id = LZ4_COMPRESSION,
143 	.name = "lz4",
144 	.alloc_buffer = 0,
145 	.supported = 1
146 };
147