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(void *ctx) 106 { 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(void *ctx) 120 { 121 deflate_comp_exit(ctx); 122 deflate_decomp_exit(ctx); 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 ret = zlib_deflateReset(stream); 133 if (ret != Z_OK) { 134 ret = -EINVAL; 135 goto out; 136 } 137 138 stream->next_in = (u8 *)src; 139 stream->avail_in = slen; 140 stream->next_out = (u8 *)dst; 141 stream->avail_out = *dlen; 142 143 ret = zlib_deflate(stream, Z_FINISH); 144 if (ret != Z_STREAM_END) { 145 ret = -EINVAL; 146 goto out; 147 } 148 ret = 0; 149 *dlen = stream->total_out; 150 out: 151 return ret; 152 } 153 154 static int deflate_decompress(void *ctx, const u8 *src, unsigned int slen, 155 u8 *dst, unsigned int *dlen) 156 { 157 158 int ret = 0; 159 struct deflate_ctx *dctx = ctx; 160 struct z_stream_s *stream = &dctx->decomp_stream; 161 162 ret = zlib_inflateReset(stream); 163 if (ret != Z_OK) { 164 ret = -EINVAL; 165 goto out; 166 } 167 168 stream->next_in = (u8 *)src; 169 stream->avail_in = slen; 170 stream->next_out = (u8 *)dst; 171 stream->avail_out = *dlen; 172 173 ret = zlib_inflate(stream, Z_SYNC_FLUSH); 174 /* 175 * Work around a bug in zlib, which sometimes wants to taste an extra 176 * byte when being used in the (undocumented) raw deflate mode. 177 * (From USAGI). 178 */ 179 if (ret == Z_OK && !stream->avail_in && stream->avail_out) { 180 u8 zerostuff = 0; 181 stream->next_in = &zerostuff; 182 stream->avail_in = 1; 183 ret = zlib_inflate(stream, Z_FINISH); 184 } 185 if (ret != Z_STREAM_END) { 186 ret = -EINVAL; 187 goto out; 188 } 189 ret = 0; 190 *dlen = stream->total_out; 191 out: 192 return ret; 193 } 194 195 static struct crypto_alg alg = { 196 .cra_name = "deflate", 197 .cra_flags = CRYPTO_ALG_TYPE_COMPRESS, 198 .cra_ctxsize = sizeof(struct deflate_ctx), 199 .cra_module = THIS_MODULE, 200 .cra_list = LIST_HEAD_INIT(alg.cra_list), 201 .cra_u = { .compress = { 202 .coa_init = deflate_init, 203 .coa_exit = deflate_exit, 204 .coa_compress = deflate_compress, 205 .coa_decompress = deflate_decompress } } 206 }; 207 208 static int __init init(void) 209 { 210 return crypto_register_alg(&alg); 211 } 212 213 static void __exit fini(void) 214 { 215 crypto_unregister_alg(&alg); 216 } 217 218 module_init(init); 219 module_exit(fini); 220 221 MODULE_LICENSE("GPL"); 222 MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP"); 223 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 224 225