Root/crypto/deflate.c

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

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