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
  36#define DEFLATE_DEF_LEVEL               Z_DEFAULT_COMPRESSION
  37#define DEFLATE_DEF_WINBITS             11
  38#define DEFLATE_DEF_MEMLEVEL            MAX_MEM_LEVEL
  39
  40struct deflate_ctx {
  41        struct z_stream_s comp_stream;
  42        struct z_stream_s decomp_stream;
  43};
  44
  45static 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        }
  63out:
  64        return ret;
  65out_free:
  66        vfree(stream->workspace);
  67        goto out;
  68}
  69
  70static 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        }
  85out:
  86        return ret;
  87out_free:
  88        vfree(stream->workspace);
  89        goto out;
  90}
  91
  92static void deflate_comp_exit(struct deflate_ctx *ctx)
  93{
  94        zlib_deflateEnd(&ctx->comp_stream);
  95        vfree(ctx->comp_stream.workspace);
  96}
  97
  98static void deflate_decomp_exit(struct deflate_ctx *ctx)
  99{
 100        zlib_inflateEnd(&ctx->decomp_stream);
 101        vfree(ctx->decomp_stream.workspace);
 102}
 103
 104static 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);
 115out:
 116        return ret;
 117}
 118
 119static 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
 127static 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;
 152out:
 153        return ret;
 154}
 155
 156static 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;
 193out:
 194        return ret;
 195}
 196
 197static 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_list               = LIST_HEAD_INIT(alg.cra_list),
 203        .cra_init               = deflate_init,
 204        .cra_exit               = deflate_exit,
 205        .cra_u                  = { .compress = {
 206        .coa_compress           = deflate_compress,
 207        .coa_decompress         = deflate_decompress } }
 208};
 209
 210static int __init deflate_mod_init(void)
 211{
 212        return crypto_register_alg(&alg);
 213}
 214
 215static void __exit deflate_mod_fini(void)
 216{
 217        crypto_unregister_alg(&alg);
 218}
 219
 220module_init(deflate_mod_init);
 221module_exit(deflate_mod_fini);
 222
 223MODULE_LICENSE("GPL");
 224MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP");
 225MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
 226
 227
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