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
  40 struct deflate_ctx {
  41         struct z_stream_s comp_stream;
  42         struct z_stream_s decomp_stream;
  43 };
  44
  45 static 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         }
  63 out:
  64         return ret;
  65 out_free:
  66         vfree(stream->workspace);
  67         goto out;
  68 }
  69
  70 static 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         }
  85 out:
  86         return ret;
  87 out_free:
  88         vfree(stream->workspace);
  89         goto out;
  90 }
  91
  92 static void deflate_comp_exit(struct deflate_ctx *ctx)
  93 {
  94         zlib_deflateEnd(&ctx->comp_stream);
  95         vfree(ctx->comp_stream.workspace);
  96 }
  97
  98 static void deflate_decomp_exit(struct deflate_ctx *ctx)
  99 {
 100         zlib_inflateEnd(&ctx->decomp_stream);
 101         vfree(ctx->decomp_stream.workspace);
 102 }
 103
 104 static 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);
 115 out:
 116         return ret;
 117 }
 118
 119 static 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
 127 static 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;
 152 out:
 153         return ret;
 154 }
 155
 156 static 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;
 193 out:
 194         return ret;
 195 }
 196
 197 static 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
 209 static int __init deflate_mod_init(void)
 210 {
 211         return crypto_register_alg(&alg);
 212 }
 213
 214 static void __exit deflate_mod_fini(void)
 215 {
 216         crypto_unregister_alg(&alg);
 217 }
 218
 219 module_init(deflate_mod_init);
 220 module_exit(deflate_mod_fini);
 221
 222 MODULE_LICENSE("GPL");
 223 MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP");
 224 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
 225