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#include <linux/slab.h>
36
37#define DEFLATE_DEF_LEVEL Z_DEFAULT_COMPRESSION
38#define DEFLATE_DEF_WINBITS 11
39#define DEFLATE_DEF_MEMLEVEL MAX_MEM_LEVEL
40
41struct deflate_ctx {
42    struct z_stream_s comp_stream;
43    struct z_stream_s decomp_stream;
44};
45
46static int deflate_comp_init(struct deflate_ctx *ctx)
47{
48    int ret = 0;
49    struct z_stream_s *stream = &ctx->comp_stream;
50
51    stream->workspace = vmalloc(zlib_deflate_workspacesize());
52    if (!stream->workspace) {
53        ret = -ENOMEM;
54        goto out;
55    }
56    memset(stream->workspace, 0, zlib_deflate_workspacesize());
57    ret = zlib_deflateInit2(stream, DEFLATE_DEF_LEVEL, Z_DEFLATED,
58                            -DEFLATE_DEF_WINBITS, DEFLATE_DEF_MEMLEVEL,
59                            Z_DEFAULT_STRATEGY);
60    if (ret != Z_OK) {
61        ret = -EINVAL;
62        goto out_free;
63    }
64out:
65    return ret;
66out_free:
67    vfree(stream->workspace);
68    goto out;
69}
70
71static int deflate_decomp_init(struct deflate_ctx *ctx)
72{
73    int ret = 0;
74    struct z_stream_s *stream = &ctx->decomp_stream;
75
76    stream->workspace = kzalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
77    if (!stream->workspace) {
78        ret = -ENOMEM;
79        goto out;
80    }
81    ret = zlib_inflateInit2(stream, -DEFLATE_DEF_WINBITS);
82    if (ret != Z_OK) {
83        ret = -EINVAL;
84        goto out_free;
85    }
86out:
87    return ret;
88out_free:
89    kfree(stream->workspace);
90    goto out;
91}
92
93static void deflate_comp_exit(struct deflate_ctx *ctx)
94{
95    zlib_deflateEnd(&ctx->comp_stream);
96    vfree(ctx->comp_stream.workspace);
97}
98
99static void deflate_decomp_exit(struct deflate_ctx *ctx)
100{
101    zlib_inflateEnd(&ctx->decomp_stream);
102    kfree(ctx->decomp_stream.workspace);
103}
104
105static int deflate_init(struct crypto_tfm *tfm)
106{
107    struct deflate_ctx *ctx = crypto_tfm_ctx(tfm);
108    int ret;
109
110    ret = deflate_comp_init(ctx);
111    if (ret)
112        goto out;
113    ret = deflate_decomp_init(ctx);
114    if (ret)
115        deflate_comp_exit(ctx);
116out:
117    return ret;
118}
119
120static void deflate_exit(struct crypto_tfm *tfm)
121{
122    struct deflate_ctx *ctx = crypto_tfm_ctx(tfm);
123
124    deflate_comp_exit(ctx);
125    deflate_decomp_exit(ctx);
126}
127
128static int deflate_compress(struct crypto_tfm *tfm, const u8 *src,
129                unsigned int slen, u8 *dst, unsigned int *dlen)
130{
131    int ret = 0;
132    struct deflate_ctx *dctx = crypto_tfm_ctx(tfm);
133    struct z_stream_s *stream = &dctx->comp_stream;
134
135    ret = zlib_deflateReset(stream);
136    if (ret != Z_OK) {
137        ret = -EINVAL;
138        goto out;
139    }
140
141    stream->next_in = (u8 *)src;
142    stream->avail_in = slen;
143    stream->next_out = (u8 *)dst;
144    stream->avail_out = *dlen;
145
146    ret = zlib_deflate(stream, Z_FINISH);
147    if (ret != Z_STREAM_END) {
148        ret = -EINVAL;
149        goto out;
150    }
151    ret = 0;
152    *dlen = stream->total_out;
153out:
154    return ret;
155}
156
157static int deflate_decompress(struct crypto_tfm *tfm, const u8 *src,
158                  unsigned int slen, u8 *dst, unsigned int *dlen)
159{
160
161    int ret = 0;
162    struct deflate_ctx *dctx = crypto_tfm_ctx(tfm);
163    struct z_stream_s *stream = &dctx->decomp_stream;
164
165    ret = zlib_inflateReset(stream);
166    if (ret != Z_OK) {
167        ret = -EINVAL;
168        goto out;
169    }
170
171    stream->next_in = (u8 *)src;
172    stream->avail_in = slen;
173    stream->next_out = (u8 *)dst;
174    stream->avail_out = *dlen;
175
176    ret = zlib_inflate(stream, Z_SYNC_FLUSH);
177    /*
178     * Work around a bug in zlib, which sometimes wants to taste an extra
179     * byte when being used in the (undocumented) raw deflate mode.
180     * (From USAGI).
181     */
182    if (ret == Z_OK && !stream->avail_in && stream->avail_out) {
183        u8 zerostuff = 0;
184        stream->next_in = &zerostuff;
185        stream->avail_in = 1;
186        ret = zlib_inflate(stream, Z_FINISH);
187    }
188    if (ret != Z_STREAM_END) {
189        ret = -EINVAL;
190        goto out;
191    }
192    ret = 0;
193    *dlen = stream->total_out;
194out:
195    return ret;
196}
197
198static struct crypto_alg alg = {
199    .cra_name = "deflate",
200    .cra_flags = CRYPTO_ALG_TYPE_COMPRESS,
201    .cra_ctxsize = sizeof(struct deflate_ctx),
202    .cra_module = THIS_MODULE,
203    .cra_list = LIST_HEAD_INIT(alg.cra_list),
204    .cra_init = deflate_init,
205    .cra_exit = deflate_exit,
206    .cra_u = { .compress = {
207    .coa_compress = deflate_compress,
208    .coa_decompress = deflate_decompress } }
209};
210
211static int __init deflate_mod_init(void)
212{
213    return crypto_register_alg(&alg);
214}
215
216static void __exit deflate_mod_fini(void)
217{
218    crypto_unregister_alg(&alg);
219}
220
221module_init(deflate_mod_init);
222module_exit(deflate_mod_fini);
223
224MODULE_LICENSE("GPL");
225MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP");
226MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
227
228

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