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