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 = kzalloc(zlib_inflate_workspacesize(), GFP_KERNEL); 77 if (!stream->workspace) { 78 ret = -ENOMEM; 79 goto out; 80 } 81 ret = zlib_inflateInit2(stream, -DEFLATE_DEF_WINBITS); 82 if (ret != Z_OK) { 83 ret = -EINVAL; 84 goto out_free; 85 } 86 out: 87 return ret; 88 out_free: 89 kfree(stream->workspace); 90 goto out; 91 } 92 93 static void deflate_comp_exit(struct deflate_ctx *ctx) 94 { 95 zlib_deflateEnd(&ctx->comp_stream); 96 vfree(ctx->comp_stream.workspace); 97 } 98 99 static void deflate_decomp_exit(struct deflate_ctx *ctx) 100 { 101 zlib_inflateEnd(&ctx->decomp_stream); 102 kfree(ctx->decomp_stream.workspace); 103 } 104 105 static int deflate_init(struct crypto_tfm *tfm) 106 { 107 struct deflate_ctx *ctx = crypto_tfm_ctx(tfm); 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(struct crypto_tfm *tfm) 121 { 122 struct deflate_ctx *ctx = crypto_tfm_ctx(tfm); 123 124 deflate_comp_exit(ctx); 125 deflate_decomp_exit(ctx); 126 } 127 128 static int deflate_compress(struct crypto_tfm *tfm, const u8 *src, 129 unsigned int slen, u8 *dst, unsigned int *dlen) 130 { 131 int ret = 0; 132 struct deflate_ctx *dctx = crypto_tfm_ctx(tfm); 133 struct z_stream_s *stream = &dctx->comp_stream; 134 135 ret = zlib_deflateReset(stream); 136 if (ret != Z_OK) { 137 ret = -EINVAL; 138 goto out; 139 } 140 141 stream->next_in = (u8 *)src; 142 stream->avail_in = slen; 143 stream->next_out = (u8 *)dst; 144 stream->avail_out = *dlen; 145 146 ret = zlib_deflate(stream, Z_FINISH); 147 if (ret != Z_STREAM_END) { 148 ret = -EINVAL; 149 goto out; 150 } 151 ret = 0; 152 *dlen = stream->total_out; 153 out: 154 return ret; 155 } 156 157 static int deflate_decompress(struct crypto_tfm *tfm, const u8 *src, 158 unsigned int slen, u8 *dst, unsigned int *dlen) 159 { 160 161 int ret = 0; 162 struct deflate_ctx *dctx = crypto_tfm_ctx(tfm); 163 struct z_stream_s *stream = &dctx->decomp_stream; 164 165 ret = zlib_inflateReset(stream); 166 if (ret != Z_OK) { 167 ret = -EINVAL; 168 goto out; 169 } 170 171 stream->next_in = (u8 *)src; 172 stream->avail_in = slen; 173 stream->next_out = (u8 *)dst; 174 stream->avail_out = *dlen; 175 176 ret = zlib_inflate(stream, Z_SYNC_FLUSH); 177 /* 178 * Work around a bug in zlib, which sometimes wants to taste an extra 179 * byte when being used in the (undocumented) raw deflate mode. 180 * (From USAGI). 181 */ 182 if (ret == Z_OK && !stream->avail_in && stream->avail_out) { 183 u8 zerostuff = 0; 184 stream->next_in = &zerostuff; 185 stream->avail_in = 1; 186 ret = zlib_inflate(stream, Z_FINISH); 187 } 188 if (ret != Z_STREAM_END) { 189 ret = -EINVAL; 190 goto out; 191 } 192 ret = 0; 193 *dlen = stream->total_out; 194 out: 195 return ret; 196 } 197 198 static struct crypto_alg alg = { 199 .cra_name = "deflate", 200 .cra_flags = CRYPTO_ALG_TYPE_COMPRESS, 201 .cra_ctxsize = sizeof(struct deflate_ctx), 202 .cra_module = THIS_MODULE, 203 .cra_list = LIST_HEAD_INIT(alg.cra_list), 204 .cra_init = deflate_init, 205 .cra_exit = deflate_exit, 206 .cra_u = { .compress = { 207 .coa_compress = deflate_compress, 208 .coa_decompress = deflate_decompress } } 209 }; 210 211 static int __init deflate_mod_init(void) 212 { 213 return crypto_register_alg(&alg); 214 } 215 216 static void __exit deflate_mod_fini(void) 217 { 218 crypto_unregister_alg(&alg); 219 } 220 221 module_init(deflate_mod_init); 222 module_exit(deflate_mod_fini); 223 224 MODULE_LICENSE("GPL"); 225 MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP"); 226 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 227 228