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 #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
  41 struct deflate_ctx {
  42         struct z_stream_s comp_stream;
  43         struct z_stream_s decomp_stream;
  44 };
  45
  46 static 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         }
  64 out:
  65         return ret;
  66 out_free:
  67         vfree(stream->workspace);
  68         goto out;
  69 }
  70
  71 static 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 = kmalloc(zlib_inflate_workspacesize(), GFP_KERNEL);
  77         if (!stream->workspace ) {
  78                 ret = -ENOMEM;
  79                 goto out;
  80         }
  81         memset(stream->workspace, 0, zlib_inflate_workspacesize());
  82         ret = zlib_inflateInit2(stream, -DEFLATE_DEF_WINBITS);
  83         if (ret != Z_OK) {
  84                 ret = -EINVAL;
  85                 goto out_free;
  86         }
  87 out:
  88         return ret;
  89 out_free:
  90         kfree(stream->workspace);
  91         goto out;
  92 }
  93
  94 static void deflate_comp_exit(struct deflate_ctx *ctx)
  95 {
  96         zlib_deflateEnd(&ctx->comp_stream);
  97         vfree(ctx->comp_stream.workspace);
  98 }
  99
 100 static void deflate_decomp_exit(struct deflate_ctx *ctx)
 101 {
 102         zlib_inflateEnd(&ctx->decomp_stream);
 103         kfree(ctx->decomp_stream.workspace);
 104 }
 105
 106 static int deflate_init(void *ctx)
 107 {
 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);
 116 out:
 117         return ret;
 118 }
 119
 120 static void deflate_exit(void *ctx)
 121 {
 122         deflate_comp_exit(ctx);
 123         deflate_decomp_exit(ctx);
 124 }
 125
 126 static int deflate_compress(void *ctx, const u8 *src, unsigned int slen,
 127                             u8 *dst, unsigned int *dlen)
 128 {
 129         int ret = 0;
 130         struct deflate_ctx *dctx = ctx;
 131         struct z_stream_s *stream = &dctx->comp_stream;
 132
 133         ret = zlib_deflateReset(stream);
 134         if (ret != Z_OK) {
 135                 ret = -EINVAL;
 136                 goto out;
 137         }
 138
 139         stream->next_in = (u8 *)src;
 140         stream->avail_in = slen;
 141         stream->next_out = (u8 *)dst;
 142         stream->avail_out = *dlen;
 143
 144         ret = zlib_deflate(stream, Z_FINISH);
 145         if (ret != Z_STREAM_END) {
 146                 ret = -EINVAL;
 147                 goto out;
 148         }
 149         ret = 0;
 150         *dlen = stream->total_out;
 151 out:
 152         return ret;
 153 }
 154
 155 static int deflate_decompress(void *ctx, const u8 *src, unsigned int slen,
 156                               u8 *dst, unsigned int *dlen)
 157 {
 158
 159         int ret = 0;
 160         struct deflate_ctx *dctx = ctx;
 161         struct z_stream_s *stream = &dctx->decomp_stream;
 162
 163         ret = zlib_inflateReset(stream);
 164         if (ret != Z_OK) {
 165                 ret = -EINVAL;
 166                 goto out;
 167         }
 168
 169         stream->next_in = (u8 *)src;
 170         stream->avail_in = slen;
 171         stream->next_out = (u8 *)dst;
 172         stream->avail_out = *dlen;
 173
 174         ret = zlib_inflate(stream, Z_SYNC_FLUSH);
 175         /*
 176          * Work around a bug in zlib, which sometimes wants to taste an extra
 177          * byte when being used in the (undocumented) raw deflate mode.
 178          * (From USAGI).
 179          */
 180         if (ret == Z_OK && !stream->avail_in && stream->avail_out) {
 181                 u8 zerostuff = 0;
 182                 stream->next_in = &zerostuff;
 183                 stream->avail_in = 1;
 184                 ret = zlib_inflate(stream, Z_FINISH);
 185         }
 186         if (ret != Z_STREAM_END) {
 187                 ret = -EINVAL;
 188                 goto out;
 189         }
 190         ret = 0;
 191         *dlen = stream->total_out;
 192 out:
 193         return ret;
 194 }
 195
 196 static struct crypto_alg alg = {
 197         .cra_name               = "deflate",
 198         .cra_flags              = CRYPTO_ALG_TYPE_COMPRESS,
 199         .cra_ctxsize            = sizeof(struct deflate_ctx),
 200         .cra_module             = THIS_MODULE,
 201         .cra_list               = LIST_HEAD_INIT(alg.cra_list),
 202         .cra_u                  = { .compress = {
 203         .coa_init               = deflate_init,
 204         .coa_exit               = deflate_exit,
 205         .coa_compress           = deflate_compress,
 206         .coa_decompress         = deflate_decompress } }
 207 };
 208
 209 static int __init init(void)
 210 {
 211         return crypto_register_alg(&alg);
 212 }
 213
 214 static void __exit fini(void)
 215 {
 216         crypto_unregister_alg(&alg);
 217 }
 218
 219 module_init(init);
 220 module_exit(fini);
 221
 222 MODULE_LICENSE("GPL");
 223 MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP");
 224 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
 225