crypto/xcbc.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C)2006 USAGI/WIDE Project
   4  *
   5  * Author:
   6  *      Kazunori Miyazawa <miyazawa@linux-ipv6.org>
   7  */
   8
   9 #include <crypto/internal/hash.h>
  10 #include <linux/err.h>
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13
  14 static u_int32_t ks[12] = {0x01010101, 0x01010101, 0x01010101, 0x01010101,
  15                            0x02020202, 0x02020202, 0x02020202, 0x02020202,
  16                            0x03030303, 0x03030303, 0x03030303, 0x03030303};
  17
  18 /*
  19  * +------------------------
  20  * | <parent tfm>
  21  * +------------------------
  22  * | xcbc_tfm_ctx
  23  * +------------------------
  24  * | consts (block size * 2)
  25  * +------------------------
  26  */
  27 struct xcbc_tfm_ctx {
  28         struct crypto_cipher *child;
  29         u8 ctx[];
  30 };
  31
  32 /*
  33  * +------------------------
  34  * | <shash desc>
  35  * +------------------------
  36  * | xcbc_desc_ctx
  37  * +------------------------
  38  * | odds (block size)
  39  * +------------------------
  40  * | prev (block size)
  41  * +------------------------
  42  */
  43 struct xcbc_desc_ctx {
  44         unsigned int len;
  45         u8 ctx[];
  46 };
  47
  48 #define XCBC_BLOCKSIZE  16
  49
  50 static int crypto_xcbc_digest_setkey(struct crypto_shash *parent,
  51                                      const u8 *inkey, unsigned int keylen)
  52 {
  53         unsigned long alignmask = crypto_shash_alignmask(parent);
  54         struct xcbc_tfm_ctx *ctx = crypto_shash_ctx(parent);
  55         u8 *consts = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
  56         int err = 0;
  57         u8 key1[XCBC_BLOCKSIZE];
  58         int bs = sizeof(key1);
  59
  60         if ((err = crypto_cipher_setkey(ctx->child, inkey, keylen)))
  61                 return err;
  62
  63         crypto_cipher_encrypt_one(ctx->child, consts, (u8 *)ks + bs);
  64         crypto_cipher_encrypt_one(ctx->child, consts + bs, (u8 *)ks + bs * 2);
  65         crypto_cipher_encrypt_one(ctx->child, key1, (u8 *)ks);
  66
  67         return crypto_cipher_setkey(ctx->child, key1, bs);
  68
  69 }
  70
  71 static int crypto_xcbc_digest_init(struct shash_desc *pdesc)
  72 {
  73         unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
  74         struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
  75         int bs = crypto_shash_blocksize(pdesc->tfm);
  76         u8 *prev = PTR_ALIGN(&ctx->ctx[0], alignmask + 1) + bs;
  77
  78         ctx->len = 0;
  79         memset(prev, 0, bs);
  80
  81         return 0;
  82 }
  83
  84 static int crypto_xcbc_digest_update(struct shash_desc *pdesc, const u8 *p,
  85                                      unsigned int len)
  86 {
  87         struct crypto_shash *parent = pdesc->tfm;
  88         unsigned long alignmask = crypto_shash_alignmask(parent);
  89         struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
  90         struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
  91         struct crypto_cipher *tfm = tctx->child;
  92         int bs = crypto_shash_blocksize(parent);
  93         u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
  94         u8 *prev = odds + bs;
  95
  96         /* checking the data can fill the block */
  97         if ((ctx->len + len) <= bs) {
  98                 memcpy(odds + ctx->len, p, len);
  99                 ctx->len += len;
 100                 return 0;
 101         }
 102
 103         /* filling odds with new data and encrypting it */
 104         memcpy(odds + ctx->len, p, bs - ctx->len);
 105         len -= bs - ctx->len;
 106         p += bs - ctx->len;
 107
 108         crypto_xor(prev, odds, bs);
 109         crypto_cipher_encrypt_one(tfm, prev, prev);
 110
 111         /* clearing the length */
 112         ctx->len = 0;
 113
 114         /* encrypting the rest of data */
 115         while (len > bs) {
 116                 crypto_xor(prev, p, bs);
 117                 crypto_cipher_encrypt_one(tfm, prev, prev);
 118                 p += bs;
 119                 len -= bs;
 120         }
 121
 122         /* keeping the surplus of blocksize */
 123         if (len) {
 124                 memcpy(odds, p, len);
 125                 ctx->len = len;
 126         }
 127
 128         return 0;
 129 }
 130
 131 static int crypto_xcbc_digest_final(struct shash_desc *pdesc, u8 *out)
 132 {
 133         struct crypto_shash *parent = pdesc->tfm;
 134         unsigned long alignmask = crypto_shash_alignmask(parent);
 135         struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
 136         struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
 137         struct crypto_cipher *tfm = tctx->child;
 138         int bs = crypto_shash_blocksize(parent);
 139         u8 *consts = PTR_ALIGN(&tctx->ctx[0], alignmask + 1);
 140         u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
 141         u8 *prev = odds + bs;
 142         unsigned int offset = 0;
 143
 144         if (ctx->len != bs) {
 145                 unsigned int rlen;
 146                 u8 *p = odds + ctx->len;
 147
 148                 *p = 0x80;
 149                 p++;
 150
 151                 rlen = bs - ctx->len -1;
 152                 if (rlen)
 153                         memset(p, 0, rlen);
 154
 155                 offset += bs;
 156         }
 157
 158         crypto_xor(prev, odds, bs);
 159         crypto_xor(prev, consts + offset, bs);
 160
 161         crypto_cipher_encrypt_one(tfm, out, prev);
 162
 163         return 0;
 164 }
 165
 166 static int xcbc_init_tfm(struct crypto_tfm *tfm)
 167 {
 168         struct crypto_cipher *cipher;
 169         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 170         struct crypto_spawn *spawn = crypto_instance_ctx(inst);
 171         struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
 172
 173         cipher = crypto_spawn_cipher(spawn);
 174         if (IS_ERR(cipher))
 175                 return PTR_ERR(cipher);
 176
 177         ctx->child = cipher;
 178
 179         return 0;
 180 };
 181
 182 static void xcbc_exit_tfm(struct crypto_tfm *tfm)
 183 {
 184         struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
 185         crypto_free_cipher(ctx->child);
 186 }
 187
 188 static int xcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 189 {
 190         struct shash_instance *inst;
 191         struct crypto_alg *alg;
 192         unsigned long alignmask;
 193         int err;
 194
 195         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
 196         if (err)
 197                 return err;
 198
 199         alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
 200                                   CRYPTO_ALG_TYPE_MASK);
 201         if (IS_ERR(alg))
 202                 return PTR_ERR(alg);
 203
 204         switch(alg->cra_blocksize) {
 205         case XCBC_BLOCKSIZE:
 206                 break;
 207         default:
 208                 goto out_put_alg;
 209         }
 210
 211         inst = shash_alloc_instance("xcbc", alg);
 212         err = PTR_ERR(inst);
 213         if (IS_ERR(inst))
 214                 goto out_put_alg;
 215
 216         err = crypto_init_spawn(shash_instance_ctx(inst), alg,
 217                                 shash_crypto_instance(inst),
 218                                 CRYPTO_ALG_TYPE_MASK);
 219         if (err)
 220                 goto out_free_inst;
 221
 222         alignmask = alg->cra_alignmask | 3;
 223         inst->alg.base.cra_alignmask = alignmask;
 224         inst->alg.base.cra_priority = alg->cra_priority;
 225         inst->alg.base.cra_blocksize = alg->cra_blocksize;
 226
 227         inst->alg.digestsize = alg->cra_blocksize;
 228         inst->alg.descsize = ALIGN(sizeof(struct xcbc_desc_ctx),
 229                                    crypto_tfm_ctx_alignment()) +
 230                              (alignmask &
 231                               ~(crypto_tfm_ctx_alignment() - 1)) +
 232                              alg->cra_blocksize * 2;
 233
 234         inst->alg.base.cra_ctxsize = ALIGN(sizeof(struct xcbc_tfm_ctx),
 235                                            alignmask + 1) +
 236                                      alg->cra_blocksize * 2;
 237         inst->alg.base.cra_init = xcbc_init_tfm;
 238         inst->alg.base.cra_exit = xcbc_exit_tfm;
 239
 240         inst->alg.init = crypto_xcbc_digest_init;
 241         inst->alg.update = crypto_xcbc_digest_update;
 242         inst->alg.final = crypto_xcbc_digest_final;
 243         inst->alg.setkey = crypto_xcbc_digest_setkey;
 244
 245         err = shash_register_instance(tmpl, inst);
 246         if (err) {
 247 out_free_inst:
 248                 shash_free_instance(shash_crypto_instance(inst));
 249         }
 250
 251 out_put_alg:
 252         crypto_mod_put(alg);
 253         return err;
 254 }
 255
 256 static struct crypto_template crypto_xcbc_tmpl = {
 257         .name = "xcbc",
 258         .create = xcbc_create,
 259         .free = shash_free_instance,
 260         .module = THIS_MODULE,
 261 };
 262
 263 static int __init crypto_xcbc_module_init(void)
 264 {
 265         return crypto_register_template(&crypto_xcbc_tmpl);
 266 }
 267
 268 static void __exit crypto_xcbc_module_exit(void)
 269 {
 270         crypto_unregister_template(&crypto_xcbc_tmpl);
 271 }
 272
 273 subsys_initcall(crypto_xcbc_module_init);
 274 module_exit(crypto_xcbc_module_exit);
 275
 276 MODULE_LICENSE("GPL");
 277 MODULE_DESCRIPTION("XCBC keyed hash algorithm");
 278 MODULE_ALIAS_CRYPTO("xcbc");