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(struct crypto_tfm *tfm)
107 struct deflate_ctx *ctx = crypto_tfm_ctx(tfm);
110 ret = deflate_comp_init(ctx);
113 ret = deflate_decomp_init(ctx);
115 deflate_comp_exit(ctx);
120 static void deflate_exit(struct crypto_tfm *tfm)
122 struct deflate_ctx *ctx = crypto_tfm_ctx(tfm);
124 deflate_comp_exit(ctx);
125 deflate_decomp_exit(ctx);
128 static int deflate_compress(struct crypto_tfm *tfm, const u8 *src,
129 unsigned int slen, u8 *dst, unsigned int *dlen)
132 struct deflate_ctx *dctx = crypto_tfm_ctx(tfm);
133 struct z_stream_s *stream = &dctx->comp_stream;
135 ret = zlib_deflateReset(stream);
141 stream->next_in = (u8 *)src;
142 stream->avail_in = slen;
143 stream->next_out = (u8 *)dst;
144 stream->avail_out = *dlen;
146 ret = zlib_deflate(stream, Z_FINISH);
147 if (ret != Z_STREAM_END) {
152 *dlen = stream->total_out;
157 static int deflate_decompress(struct crypto_tfm *tfm, const u8 *src,
158 unsigned int slen, u8 *dst, unsigned int *dlen)
162 struct deflate_ctx *dctx = crypto_tfm_ctx(tfm);
163 struct z_stream_s *stream = &dctx->decomp_stream;
165 ret = zlib_inflateReset(stream);
171 stream->next_in = (u8 *)src;
172 stream->avail_in = slen;
173 stream->next_out = (u8 *)dst;
174 stream->avail_out = *dlen;
176 ret = zlib_inflate(stream, Z_SYNC_FLUSH);
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.
182 if (ret == Z_OK && !stream->avail_in && stream->avail_out) {
184 stream->next_in = &zerostuff;
185 stream->avail_in = 1;
186 ret = zlib_inflate(stream, Z_FINISH);
188 if (ret != Z_STREAM_END) {
193 *dlen = stream->total_out;
198 static 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 } }
211 static int __init init(void)
213 return crypto_register_alg(&alg);
216 static void __exit fini(void)
218 crypto_unregister_alg(&alg);
224 MODULE_LICENSE("GPL");
225 MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP");
226 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");