projects/linux·blob v3.13 · refs

225 lines · 5.4 KiB

1/*
2 * Cryptographic API.
3 *
4 * Deflate algorithm (RFC 1951), implemented here primarily for use
5 * by IPCOMP (RFC 3173 & RFC 2394).
6 *
7 * Copyright (c) 2003 James Morris <[email protected]>
8 *
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the Free
11 * Software Foundation; either version 2 of the License, or (at your option)
12 * any later version.
13 *
14 * FIXME: deflate transforms will require up to a total of about 436k of kernel
15 * memory on i386 (390k for compression, the rest for decompression), as the
16 * current zlib kernel code uses a worst case pre-allocation system by default.
17 * This needs to be fixed so that the amount of memory required is properly
18 * related to the winbits and memlevel parameters.
19 *
20 * The default winbits of 11 should suit most packets, and it may be something
21 * to configure on a per-tfm basis in the future.
22 *
23 * Currently, compression history is not maintained between tfm calls, as
24 * it is not needed for IPCOMP and keeps the code simpler. It can be
25 * implemented if someone wants it.
26 */
27#include <linux/init.h>
28#include <linux/module.h>
29#include <linux/crypto.h>
30#include <linux/zlib.h>
31#include <linux/vmalloc.h>
32#include <linux/interrupt.h>
33#include <linux/mm.h>
34#include <linux/net.h>
35
36#define DEFLATE_DEF_LEVEL Z_DEFAULT_COMPRESSION
37#define DEFLATE_DEF_WINBITS 11
38#define DEFLATE_DEF_MEMLEVEL MAX_MEM_LEVEL
39
40struct deflate_ctx {
41 struct z_stream_s comp_stream;
42 struct z_stream_s decomp_stream;
43};
44
45static int deflate_comp_init(struct deflate_ctx *ctx)
46{
47 int ret = 0;
48 struct z_stream_s *stream = &ctx->comp_stream;
49
50 stream->workspace = vzalloc(zlib_deflate_workspacesize(
51 -DEFLATE_DEF_WINBITS, DEFLATE_DEF_MEMLEVEL));
52 if (!stream->workspace) {
53 ret = -ENOMEM;
54 goto out;
55 }
56 ret = zlib_deflateInit2(stream, DEFLATE_DEF_LEVEL, Z_DEFLATED,
57 -DEFLATE_DEF_WINBITS, DEFLATE_DEF_MEMLEVEL,
58 Z_DEFAULT_STRATEGY);
59 if (ret != Z_OK) {
60 ret = -EINVAL;
61 goto out_free;
62 }
63out:
64 return ret;
65out_free:
66 vfree(stream->workspace);
67 goto out;
68}
69
70static int deflate_decomp_init(struct deflate_ctx *ctx)
71{
72 int ret = 0;
73 struct z_stream_s *stream = &ctx->decomp_stream;
74
75 stream->workspace = vzalloc(zlib_inflate_workspacesize());
76 if (!stream->workspace) {
77 ret = -ENOMEM;
78 goto out;
79 }
80 ret = zlib_inflateInit2(stream, -DEFLATE_DEF_WINBITS);
81 if (ret != Z_OK) {
82 ret = -EINVAL;
83 goto out_free;
84 }
85out:
86 return ret;
87out_free:
88 vfree(stream->workspace);
89 goto out;
90}
91
92static void deflate_comp_exit(struct deflate_ctx *ctx)
93{
94 zlib_deflateEnd(&ctx->comp_stream);
95 vfree(ctx->comp_stream.workspace);
96}
97
98static void deflate_decomp_exit(struct deflate_ctx *ctx)
99{
100 zlib_inflateEnd(&ctx->decomp_stream);
101 vfree(ctx->decomp_stream.workspace);
102}
103
104static int deflate_init(struct crypto_tfm *tfm)
105{
106 struct deflate_ctx *ctx = crypto_tfm_ctx(tfm);
107 int ret;
108
109 ret = deflate_comp_init(ctx);
110 if (ret)
111 goto out;
112 ret = deflate_decomp_init(ctx);
113 if (ret)
114 deflate_comp_exit(ctx);
115out:
116 return ret;
117}
118
119static void deflate_exit(struct crypto_tfm *tfm)
120{
121 struct deflate_ctx *ctx = crypto_tfm_ctx(tfm);
122
123 deflate_comp_exit(ctx);
124 deflate_decomp_exit(ctx);
125}
126
127static int deflate_compress(struct crypto_tfm *tfm, const u8 *src,
128 unsigned int slen, u8 *dst, unsigned int *dlen)
129{
130 int ret = 0;
131 struct deflate_ctx *dctx = crypto_tfm_ctx(tfm);
132 struct z_stream_s *stream = &dctx->comp_stream;
133
134 ret = zlib_deflateReset(stream);
135 if (ret != Z_OK) {
136 ret = -EINVAL;
137 goto out;
138 }
139
140 stream->next_in = (u8 *)src;
141 stream->avail_in = slen;
142 stream->next_out = (u8 *)dst;
143 stream->avail_out = *dlen;
144
145 ret = zlib_deflate(stream, Z_FINISH);
146 if (ret != Z_STREAM_END) {
147 ret = -EINVAL;
148 goto out;
149 }
150 ret = 0;
151 *dlen = stream->total_out;
152out:
153 return ret;
154}
155
156static int deflate_decompress(struct crypto_tfm *tfm, const u8 *src,
157 unsigned int slen, u8 *dst, unsigned int *dlen)
158{
159
160 int ret = 0;
161 struct deflate_ctx *dctx = crypto_tfm_ctx(tfm);
162 struct z_stream_s *stream = &dctx->decomp_stream;
163
164 ret = zlib_inflateReset(stream);
165 if (ret != Z_OK) {
166 ret = -EINVAL;
167 goto out;
168 }
169
170 stream->next_in = (u8 *)src;
171 stream->avail_in = slen;
172 stream->next_out = (u8 *)dst;
173 stream->avail_out = *dlen;
174
175 ret = zlib_inflate(stream, Z_SYNC_FLUSH);
176 /*
177 * Work around a bug in zlib, which sometimes wants to taste an extra
178 * byte when being used in the (undocumented) raw deflate mode.
179 * (From USAGI).
180 */
181 if (ret == Z_OK && !stream->avail_in && stream->avail_out) {
182 u8 zerostuff = 0;
183 stream->next_in = &zerostuff;
184 stream->avail_in = 1;
185 ret = zlib_inflate(stream, Z_FINISH);
186 }
187 if (ret != Z_STREAM_END) {
188 ret = -EINVAL;
189 goto out;
190 }
191 ret = 0;
192 *dlen = stream->total_out;
193out:
194 return ret;
195}
196
197static struct crypto_alg alg = {
198 .cra_name = "deflate",
199 .cra_flags = CRYPTO_ALG_TYPE_COMPRESS,
200 .cra_ctxsize = sizeof(struct deflate_ctx),
201 .cra_module = THIS_MODULE,
202 .cra_init = deflate_init,
203 .cra_exit = deflate_exit,
204 .cra_u = { .compress = {
205 .coa_compress = deflate_compress,
206 .coa_decompress = deflate_decompress } }
207};
208
209static int __init deflate_mod_init(void)
210{
211 return crypto_register_alg(&alg);
212}
213
214static void __exit deflate_mod_fini(void)
215{
216 crypto_unregister_alg(&alg);
217}
218
219module_init(deflate_mod_init);
220module_exit(deflate_mod_fini);
221
222MODULE_LICENSE("GPL");
223MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP");
224MODULE_AUTHOR("James Morris <[email protected]>");
225