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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 <jmorris@intercode.com.au> |
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 | |
40 | struct deflate_ctx { |
41 | struct z_stream_s comp_stream; |
42 | struct z_stream_s decomp_stream; |
43 | }; |
44 | |
45 | static 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 | } |
63 | out: |
64 | return ret; |
65 | out_free: |
66 | vfree(stream->workspace); |
67 | goto out; |
68 | } |
69 | |
70 | static 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 | } |
85 | out: |
86 | return ret; |
87 | out_free: |
88 | vfree(stream->workspace); |
89 | goto out; |
90 | } |
91 | |
92 | static void deflate_comp_exit(struct deflate_ctx *ctx) |
93 | { |
94 | zlib_deflateEnd(&ctx->comp_stream); |
95 | vfree(ctx->comp_stream.workspace); |
96 | } |
97 | |
98 | static void deflate_decomp_exit(struct deflate_ctx *ctx) |
99 | { |
100 | zlib_inflateEnd(&ctx->decomp_stream); |
101 | vfree(ctx->decomp_stream.workspace); |
102 | } |
103 | |
104 | static 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); |
115 | out: |
116 | return ret; |
117 | } |
118 | |
119 | static 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 | |
127 | static 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; |
152 | out: |
153 | return ret; |
154 | } |
155 | |
156 | static 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; |
193 | out: |
194 | return ret; |
195 | } |
196 | |
197 | static 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 | |
209 | static int __init deflate_mod_init(void) |
210 | { |
211 | return crypto_register_alg(&alg); |
212 | } |
213 | |
214 | static void __exit deflate_mod_fini(void) |
215 | { |
216 | crypto_unregister_alg(&alg); |
217 | } |
218 | |
219 | module_init(deflate_mod_init); |
220 | module_exit(deflate_mod_fini); |
221 | |
222 | MODULE_LICENSE("GPL"); |
223 | MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP"); |
224 | MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); |
225 | |
226 |
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