4 * Deflate algorithm (RFC 1951), implemented here primarily for use
5 * by IPCOMP (RFC 3173 & RFC 2394).
7 * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
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)
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.
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.
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.
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>
34 #include <linux/net.h>
35 #include <linux/slab.h>
37 #define DEFLATE_DEF_LEVEL Z_DEFAULT_COMPRESSION
38 #define DEFLATE_DEF_WINBITS 11
39 #define DEFLATE_DEF_MEMLEVEL MAX_MEM_LEVEL
42 struct z_stream_s comp_stream;
43 struct z_stream_s decomp_stream;
46 static int deflate_comp_init(struct deflate_ctx *ctx)
49 struct z_stream_s *stream = &ctx->comp_stream;
51 stream->workspace = vmalloc(zlib_deflate_workspacesize());
52 if (!stream->workspace ) {
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,
67 vfree(stream->workspace);
71 static int deflate_decomp_init(struct deflate_ctx *ctx)
74 struct z_stream_s *stream = &ctx->decomp_stream;
76 stream->workspace = kzalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
77 if (!stream->workspace ) {
81 ret = zlib_inflateInit2(stream, -DEFLATE_DEF_WINBITS);
89 kfree(stream->workspace);
93 static void deflate_comp_exit(struct deflate_ctx *ctx)
95 zlib_deflateEnd(&ctx->comp_stream);
96 vfree(ctx->comp_stream.workspace);
99 static void deflate_decomp_exit(struct deflate_ctx *ctx)
101 zlib_inflateEnd(&ctx->decomp_stream);
102 kfree(ctx->decomp_stream.workspace);
105 static int deflate_init(void *ctx)
109 ret = deflate_comp_init(ctx);
112 ret = deflate_decomp_init(ctx);
114 deflate_comp_exit(ctx);
119 static void deflate_exit(void *ctx)
121 deflate_comp_exit(ctx);
122 deflate_decomp_exit(ctx);
125 static int deflate_compress(void *ctx, const u8 *src, unsigned int slen,
126 u8 *dst, unsigned int *dlen)
129 struct deflate_ctx *dctx = ctx;
130 struct z_stream_s *stream = &dctx->comp_stream;
132 ret = zlib_deflateReset(stream);
138 stream->next_in = (u8 *)src;
139 stream->avail_in = slen;
140 stream->next_out = (u8 *)dst;
141 stream->avail_out = *dlen;
143 ret = zlib_deflate(stream, Z_FINISH);
144 if (ret != Z_STREAM_END) {
149 *dlen = stream->total_out;
154 static int deflate_decompress(void *ctx, const u8 *src, unsigned int slen,
155 u8 *dst, unsigned int *dlen)
159 struct deflate_ctx *dctx = ctx;
160 struct z_stream_s *stream = &dctx->decomp_stream;
162 ret = zlib_inflateReset(stream);
168 stream->next_in = (u8 *)src;
169 stream->avail_in = slen;
170 stream->next_out = (u8 *)dst;
171 stream->avail_out = *dlen;
173 ret = zlib_inflate(stream, Z_SYNC_FLUSH);
175 * Work around a bug in zlib, which sometimes wants to taste an extra
176 * byte when being used in the (undocumented) raw deflate mode.
179 if (ret == Z_OK && !stream->avail_in && stream->avail_out) {
181 stream->next_in = &zerostuff;
182 stream->avail_in = 1;
183 ret = zlib_inflate(stream, Z_FINISH);
185 if (ret != Z_STREAM_END) {
190 *dlen = stream->total_out;
195 static struct crypto_alg alg = {
196 .cra_name = "deflate",
197 .cra_flags = CRYPTO_ALG_TYPE_COMPRESS,
198 .cra_ctxsize = sizeof(struct deflate_ctx),
199 .cra_module = THIS_MODULE,
200 .cra_list = LIST_HEAD_INIT(alg.cra_list),
201 .cra_u = { .compress = {
202 .coa_init = deflate_init,
203 .coa_exit = deflate_exit,
204 .coa_compress = deflate_compress,
205 .coa_decompress = deflate_decompress } }
208 static int __init init(void)
210 return crypto_register_alg(&alg);
213 static void __exit fini(void)
215 crypto_unregister_alg(&alg);
221 MODULE_LICENSE("GPL");
222 MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP");
223 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");