linux/crypto/deflate.c
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   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 init(void)
 212{
 213        return crypto_register_alg(&alg);
 214}
 215
 216static void __exit fini(void)
 217{
 218        crypto_unregister_alg(&alg);
 219}
 220
 221module_init(init);
 222module_exit(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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