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         int comp_initialized;
  43         int decomp_initialized;
  44         struct z_stream_s comp_stream;
  45         struct z_stream_s decomp_stream;
  46 };
  47
  48 static inline int deflate_gfp(void)
  49 {
  50         return in_softirq() ? GFP_ATOMIC : GFP_KERNEL;
  51 }
  52
  53 static int deflate_init(void *ctx)
  54 {
  55         return 0;
  56 }
  57
  58 static void deflate_exit(void *ctx)
  59 {
  60         struct deflate_ctx *dctx = ctx;
  61
  62         if (dctx->comp_initialized)
  63                 vfree(dctx->comp_stream.workspace);
  64         if (dctx->decomp_initialized)
  65                 kfree(dctx->decomp_stream.workspace);
  66 }
  67
  68 /*
  69  * Lazy initialization to make interface simple without allocating
  70  * un-needed workspaces.  Thus can be called in softirq context.
  71  */
  72 static int deflate_comp_init(struct deflate_ctx *ctx)
  73 {
  74         int ret = 0;
  75         struct z_stream_s *stream = &ctx->comp_stream;
  76
  77         stream->workspace = __vmalloc(zlib_deflate_workspacesize(),
  78                                       deflate_gfp()|__GFP_HIGHMEM,
  79                                       PAGE_KERNEL);
  80         if (!stream->workspace ) {
  81                 ret = -ENOMEM;
  82                 goto out;
  83         }
  84         memset(stream->workspace, 0, zlib_deflate_workspacesize());
  85         ret = zlib_deflateInit2(stream, DEFLATE_DEF_LEVEL, Z_DEFLATED,
  86                                 -DEFLATE_DEF_WINBITS, DEFLATE_DEF_MEMLEVEL,
  87                                 Z_DEFAULT_STRATEGY);
  88         if (ret != Z_OK) {
  89                 ret = -EINVAL;
  90                 goto out_free;
  91         }
  92         ctx->comp_initialized = 1;
  93 out:
  94         return ret;
  95 out_free:
  96         vfree(stream->workspace);
  97         goto out;
  98 }
  99
 100 static int deflate_decomp_init(struct deflate_ctx *ctx)
 101 {
 102         int ret = 0;
 103         struct z_stream_s *stream = &ctx->decomp_stream;
 104
 105         stream->workspace = kmalloc(zlib_inflate_workspacesize(),
 106                                     deflate_gfp());
 107         if (!stream->workspace ) {
 108                 ret = -ENOMEM;
 109                 goto out;
 110         }
 111         memset(stream->workspace, 0, zlib_inflate_workspacesize());
 112         ret = zlib_inflateInit2(stream, -DEFLATE_DEF_WINBITS);
 113         if (ret != Z_OK) {
 114                 ret = -EINVAL;
 115                 goto out_free;
 116         }
 117         ctx->decomp_initialized = 1;
 118 out:
 119         return ret;
 120 out_free:
 121         kfree(stream->workspace);
 122         goto out;
 123 }
 124
 125 static int deflate_compress(void *ctx, const u8 *src, unsigned int slen,
 126                             u8 *dst, unsigned int *dlen)
 127 {
 128         int ret = 0;
 129         struct deflate_ctx *dctx = ctx;
 130         struct z_stream_s *stream = &dctx->comp_stream;
 131
 132         if (!dctx->comp_initialized) {
 133                 ret = deflate_comp_init(dctx);
 134                 if (ret)
 135                         goto out;
 136         }
 137
 138         ret = zlib_deflateReset(stream);
 139         if (ret != Z_OK) {
 140                 ret = -EINVAL;
 141                 goto out;
 142         }
 143
 144         stream->next_in = (u8 *)src;
 145         stream->avail_in = slen;
 146         stream->next_out = (u8 *)dst;
 147         stream->avail_out = *dlen;
 148
 149         ret = zlib_deflate(stream, Z_FINISH);
 150         if (ret != Z_STREAM_END) {
 151                 ret = -EINVAL;
 152                 goto out;
 153         }
 154         ret = 0;
 155         *dlen = stream->total_out;
 156 out:
 157         return ret;
 158 }
 159
 160 static int deflate_decompress(void *ctx, const u8 *src, unsigned int slen,
 161                               u8 *dst, unsigned int *dlen)
 162 {
 163
 164         int ret = 0;
 165         struct deflate_ctx *dctx = ctx;
 166         struct z_stream_s *stream = &dctx->decomp_stream;
 167
 168         if (!dctx->decomp_initialized) {
 169                 ret = deflate_decomp_init(dctx);
 170                 if (ret)
 171                         goto out;
 172         }
 173
 174         ret = zlib_inflateReset(stream);
 175         if (ret != Z_OK) {
 176                 ret = -EINVAL;
 177                 goto out;
 178         }
 179
 180         stream->next_in = (u8 *)src;
 181         stream->avail_in = slen;
 182         stream->next_out = (u8 *)dst;
 183         stream->avail_out = *dlen;
 184
 185         ret = zlib_inflate(stream, Z_SYNC_FLUSH);
 186         /*
 187          * Work around a bug in zlib, which sometimes wants to taste an extra
 188          * byte when being used in the (undocumented) raw deflate mode.
 189          * (From USAGI).
 190          */
 191         if (ret == Z_OK && !stream->avail_in && stream->avail_out) {
 192                 u8 zerostuff = 0;
 193                 stream->next_in = &zerostuff;
 194                 stream->avail_in = 1;
 195                 ret = zlib_inflate(stream, Z_FINISH);
 196         }
 197         if (ret != Z_STREAM_END) {
 198                 ret = -EINVAL;
 199                 goto out;
 200         }
 201         ret = 0;
 202         *dlen = stream->total_out;
 203 out:
 204         return ret;
 205 }
 206
 207 static struct crypto_alg alg = {
 208         .cra_name               = "deflate",
 209         .cra_flags              = CRYPTO_ALG_TYPE_COMPRESS,
 210         .cra_ctxsize            = sizeof(struct deflate_ctx),
 211         .cra_module             = THIS_MODULE,
 212         .cra_list               = LIST_HEAD_INIT(alg.cra_list),
 213         .cra_u                  = { .compress = {
 214         .coa_init               = deflate_init,
 215         .coa_exit               = deflate_exit,
 216         .coa_compress           = deflate_compress,
 217         .coa_decompress         = deflate_decompress } }
 218 };
 219
 220 static int __init init(void)
 221 {
 222         return crypto_register_alg(&alg);
 223 }
 224
 225 static void __exit fini(void)
 226 {
 227         crypto_unregister_alg(&alg);
 228 }
 229
 230 module_init(init);
 231 module_exit(fini);
 232
 233 MODULE_LICENSE("GPL");
 234 MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP");
 235 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
 236