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
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 <jmorris@intercode.com.au>");
225
226