crypto/xcbc.c

   1 /*
   2  * Copyright (C)2006 USAGI/WIDE Project
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17  *
  18  * Author:
  19  *      Kazunori Miyazawa <miyazawa@linux-ipv6.org>
  20  */
  21
  22 #include <crypto/internal/hash.h>
  23 #include <linux/err.h>
  24 #include <linux/kernel.h>
  25
  26 static u_int32_t ks[12] = {0x01010101, 0x01010101, 0x01010101, 0x01010101,
  27                            0x02020202, 0x02020202, 0x02020202, 0x02020202,
  28                            0x03030303, 0x03030303, 0x03030303, 0x03030303};
  29
  30 /*
  31  * +------------------------
  32  * | <parent tfm>
  33  * +------------------------
  34  * | xcbc_tfm_ctx
  35  * +------------------------
  36  * | consts (block size * 2)
  37  * +------------------------
  38  */
  39 struct xcbc_tfm_ctx {
  40         struct crypto_cipher *child;
  41         u8 ctx[];
  42 };
  43
  44 /*
  45  * +------------------------
  46  * | <shash desc>
  47  * +------------------------
  48  * | xcbc_desc_ctx
  49  * +------------------------
  50  * | odds (block size)
  51  * +------------------------
  52  * | prev (block size)
  53  * +------------------------
  54  */
  55 struct xcbc_desc_ctx {
  56         unsigned int len;
  57         u8 ctx[];
  58 };
  59
  60 static int crypto_xcbc_digest_setkey(struct crypto_shash *parent,
  61                                      const u8 *inkey, unsigned int keylen)
  62 {
  63         unsigned long alignmask = crypto_shash_alignmask(parent);
  64         struct xcbc_tfm_ctx *ctx = crypto_shash_ctx(parent);
  65         int bs = crypto_shash_blocksize(parent);
  66         u8 *consts = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
  67         int err = 0;
  68         u8 key1[bs];
  69
  70         if ((err = crypto_cipher_setkey(ctx->child, inkey, keylen)))
  71                 return err;
  72
  73         crypto_cipher_encrypt_one(ctx->child, consts, (u8 *)ks + bs);
  74         crypto_cipher_encrypt_one(ctx->child, consts + bs, (u8 *)ks + bs * 2);
  75         crypto_cipher_encrypt_one(ctx->child, key1, (u8 *)ks);
  76
  77         return crypto_cipher_setkey(ctx->child, key1, bs);
  78
  79 }
  80
  81 static int crypto_xcbc_digest_init(struct shash_desc *pdesc)
  82 {
  83         unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
  84         struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
  85         int bs = crypto_shash_blocksize(pdesc->tfm);
  86         u8 *prev = PTR_ALIGN(&ctx->ctx[0], alignmask + 1) + bs;
  87
  88         ctx->len = 0;
  89         memset(prev, 0, bs);
  90
  91         return 0;
  92 }
  93
  94 static int crypto_xcbc_digest_update(struct shash_desc *pdesc, const u8 *p,
  95                                      unsigned int len)
  96 {
  97         struct crypto_shash *parent = pdesc->tfm;
  98         unsigned long alignmask = crypto_shash_alignmask(parent);
  99         struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
 100         struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
 101         struct crypto_cipher *tfm = tctx->child;
 102         int bs = crypto_shash_blocksize(parent);
 103         u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
 104         u8 *prev = odds + bs;
 105
 106         /* checking the data can fill the block */
 107         if ((ctx->len + len) <= bs) {
 108                 memcpy(odds + ctx->len, p, len);
 109                 ctx->len += len;
 110                 return 0;
 111         }
 112
 113         /* filling odds with new data and encrypting it */
 114         memcpy(odds + ctx->len, p, bs - ctx->len);
 115         len -= bs - ctx->len;
 116         p += bs - ctx->len;
 117
 118         crypto_xor(prev, odds, bs);
 119         crypto_cipher_encrypt_one(tfm, prev, prev);
 120
 121         /* clearing the length */
 122         ctx->len = 0;
 123
 124         /* encrypting the rest of data */
 125         while (len > bs) {
 126                 crypto_xor(prev, p, bs);
 127                 crypto_cipher_encrypt_one(tfm, prev, prev);
 128                 p += bs;
 129                 len -= bs;
 130         }
 131
 132         /* keeping the surplus of blocksize */
 133         if (len) {
 134                 memcpy(odds, p, len);
 135                 ctx->len = len;
 136         }
 137
 138         return 0;
 139 }
 140
 141 static int crypto_xcbc_digest_final(struct shash_desc *pdesc, u8 *out)
 142 {
 143         struct crypto_shash *parent = pdesc->tfm;
 144         unsigned long alignmask = crypto_shash_alignmask(parent);
 145         struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
 146         struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
 147         struct crypto_cipher *tfm = tctx->child;
 148         int bs = crypto_shash_blocksize(parent);
 149         u8 *consts = PTR_ALIGN(&tctx->ctx[0], alignmask + 1);
 150         u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
 151         u8 *prev = odds + bs;
 152         unsigned int offset = 0;
 153
 154         if (ctx->len != bs) {
 155                 unsigned int rlen;
 156                 u8 *p = odds + ctx->len;
 157
 158                 *p = 0x80;
 159                 p++;
 160
 161                 rlen = bs - ctx->len -1;
 162                 if (rlen)
 163                         memset(p, 0, rlen);
 164
 165                 offset += bs;
 166         }
 167
 168         crypto_xor(prev, odds, bs);
 169         crypto_xor(prev, consts + offset, bs);
 170
 171         crypto_cipher_encrypt_one(tfm, out, prev);
 172
 173         return 0;
 174 }
 175
 176 static int xcbc_init_tfm(struct crypto_tfm *tfm)
 177 {
 178         struct crypto_cipher *cipher;
 179         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 180         struct crypto_spawn *spawn = crypto_instance_ctx(inst);
 181         struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
 182
 183         cipher = crypto_spawn_cipher(spawn);
 184         if (IS_ERR(cipher))
 185                 return PTR_ERR(cipher);
 186
 187         ctx->child = cipher;
 188
 189         return 0;
 190 };
 191
 192 static void xcbc_exit_tfm(struct crypto_tfm *tfm)
 193 {
 194         struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
 195         crypto_free_cipher(ctx->child);
 196 }
 197
 198 static int xcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 199 {
 200         struct shash_instance *inst;
 201         struct crypto_alg *alg;
 202         unsigned long alignmask;
 203         int err;
 204
 205         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
 206         if (err)
 207                 return err;
 208
 209         alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
 210                                   CRYPTO_ALG_TYPE_MASK);
 211         if (IS_ERR(alg))
 212                 return PTR_ERR(alg);
 213
 214         switch(alg->cra_blocksize) {
 215         case 16:
 216                 break;
 217         default:
 218                 goto out_put_alg;
 219         }
 220
 221         inst = shash_alloc_instance("xcbc", alg);
 222         err = PTR_ERR(inst);
 223         if (IS_ERR(inst))
 224                 goto out_put_alg;
 225
 226         err = crypto_init_spawn(shash_instance_ctx(inst), alg,
 227                                 shash_crypto_instance(inst),
 228                                 CRYPTO_ALG_TYPE_MASK);
 229         if (err)
 230                 goto out_free_inst;
 231
 232         alignmask = alg->cra_alignmask | 3;
 233         inst->alg.base.cra_alignmask = alignmask;
 234         inst->alg.base.cra_priority = alg->cra_priority;
 235         inst->alg.base.cra_blocksize = alg->cra_blocksize;
 236
 237         inst->alg.digestsize = alg->cra_blocksize;
 238         inst->alg.descsize = ALIGN(sizeof(struct xcbc_desc_ctx),
 239                                    crypto_tfm_ctx_alignment()) +
 240                              (alignmask &
 241                               ~(crypto_tfm_ctx_alignment() - 1)) +
 242                              alg->cra_blocksize * 2;
 243
 244         inst->alg.base.cra_ctxsize = ALIGN(sizeof(struct xcbc_tfm_ctx),
 245                                            alignmask + 1) +
 246                                      alg->cra_blocksize * 2;
 247         inst->alg.base.cra_init = xcbc_init_tfm;
 248         inst->alg.base.cra_exit = xcbc_exit_tfm;
 249
 250         inst->alg.init = crypto_xcbc_digest_init;
 251         inst->alg.update = crypto_xcbc_digest_update;
 252         inst->alg.final = crypto_xcbc_digest_final;
 253         inst->alg.setkey = crypto_xcbc_digest_setkey;
 254
 255         err = shash_register_instance(tmpl, inst);
 256         if (err) {
 257 out_free_inst:
 258                 shash_free_instance(shash_crypto_instance(inst));
 259         }
 260
 261 out_put_alg:
 262         crypto_mod_put(alg);
 263         return err;
 264 }
 265
 266 static struct crypto_template crypto_xcbc_tmpl = {
 267         .name = "xcbc",
 268         .create = xcbc_create,
 269         .free = shash_free_instance,
 270         .module = THIS_MODULE,
 271 };
 272
 273 static int __init crypto_xcbc_module_init(void)
 274 {
 275         return crypto_register_template(&crypto_xcbc_tmpl);
 276 }
 277
 278 static void __exit crypto_xcbc_module_exit(void)
 279 {
 280         crypto_unregister_template(&crypto_xcbc_tmpl);
 281 }
 282
 283 module_init(crypto_xcbc_module_init);
 284 module_exit(crypto_xcbc_module_exit);
 285
 286 MODULE_LICENSE("GPL");
 287 MODULE_DESCRIPTION("XCBC keyed hash algorithm");