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 = vzalloc(zlib_deflate_workspacesize()); 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 } 63 out: 64 return ret; 65 out_free: 66 vfree(stream->workspace); 67 goto out; 68 } 69 70 static 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 = kzalloc(zlib_inflate_workspacesize(), GFP_KERNEL); 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 } 85 out: 86 return ret; 87 out_free: 88 kfree(stream->workspace); 89 goto out; 90 } 91 92 static void deflate_comp_exit(struct deflate_ctx *ctx) 93 { 94 zlib_deflateEnd(&ctx->comp_stream); 95 vfree(ctx->comp_stream.workspace); 96 } 97 98 static void deflate_decomp_exit(struct deflate_ctx *ctx) 99 { 100 zlib_inflateEnd(&ctx->decomp_stream); 101 kfree(ctx->decomp_stream.workspace); 102 } 103 104 static 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); 115 out: 116 return ret; 117 } 118 119 static 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 } 126 127 static 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; 152 out: 153 return ret; 154 } 155 156 static 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; 193 out: 194 return ret; 195 } 196 197 static 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 }; 209 210 static int __init deflate_mod_init(void) 211 { 212 return crypto_register_alg(&alg); 213 } 214 215 static void __exit deflate_mod_fini(void) 216 { 217 crypto_unregister_alg(&alg); 218 } 219 220 module_init(deflate_mod_init); 221 module_exit(deflate_mod_fini); 222 223 MODULE_LICENSE("GPL"); 224 MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP"); 225 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 226 227