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/cipher.h>
  10 #include <crypto/internal/hash.h>
  11 #include <linux/err.h>
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14
  15 static u_int32_t ks[12] = {0x01010101, 0x01010101, 0x01010101, 0x01010101,
  16                            0x02020202, 0x02020202, 0x02020202, 0x02020202,
  17                            0x03030303, 0x03030303, 0x03030303, 0x03030303};
  18
  19 /*
  20  * +------------------------
  21  * | <parent tfm>
  22  * +------------------------
  23  * | xcbc_tfm_ctx
  24  * +------------------------
  25  * | consts (block size * 2)
  26  * +------------------------
  27  */
  28 struct xcbc_tfm_ctx {
  29         struct crypto_cipher *child;
  30         u8 ctx[];
  31 };
  32
  33 /*
  34  * +------------------------
  35  * | <shash desc>
  36  * +------------------------
  37  * | xcbc_desc_ctx
  38  * +------------------------
  39  * | odds (block size)
  40  * +------------------------
  41  * | prev (block size)
  42  * +------------------------
  43  */
  44 struct xcbc_desc_ctx {
  45         unsigned int len;
  46         u8 ctx[];
  47 };
  48
  49 #define XCBC_BLOCKSIZE  16
  50
  51 static int crypto_xcbc_digest_setkey(struct crypto_shash *parent,
  52                                      const u8 *inkey, unsigned int keylen)
  53 {
  54         unsigned long alignmask = crypto_shash_alignmask(parent);
  55         struct xcbc_tfm_ctx *ctx = crypto_shash_ctx(parent);
  56         u8 *consts = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
  57         int err = 0;
  58         u8 key1[XCBC_BLOCKSIZE];
  59         int bs = sizeof(key1);
  60
  61         if ((err = crypto_cipher_setkey(ctx->child, inkey, keylen)))
  62                 return err;
  63
  64         crypto_cipher_encrypt_one(ctx->child, consts, (u8 *)ks + bs);
  65         crypto_cipher_encrypt_one(ctx->child, consts + bs, (u8 *)ks + bs * 2);
  66         crypto_cipher_encrypt_one(ctx->child, key1, (u8 *)ks);
  67
  68         return crypto_cipher_setkey(ctx->child, key1, bs);
  69
  70 }
  71
  72 static int crypto_xcbc_digest_init(struct shash_desc *pdesc)
  73 {
  74         unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
  75         struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
  76         int bs = crypto_shash_blocksize(pdesc->tfm);
  77         u8 *prev = PTR_ALIGN(&ctx->ctx[0], alignmask + 1) + bs;
  78
  79         ctx->len = 0;
  80         memset(prev, 0, bs);
  81
  82         return 0;
  83 }
  84
  85 static int crypto_xcbc_digest_update(struct shash_desc *pdesc, const u8 *p,
  86                                      unsigned int len)
  87 {
  88         struct crypto_shash *parent = pdesc->tfm;
  89         unsigned long alignmask = crypto_shash_alignmask(parent);
  90         struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
  91         struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
  92         struct crypto_cipher *tfm = tctx->child;
  93         int bs = crypto_shash_blocksize(parent);
  94         u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
  95         u8 *prev = odds + bs;
  96
  97         /* checking the data can fill the block */
  98         if ((ctx->len + len) <= bs) {
  99                 memcpy(odds + ctx->len, p, len);
 100                 ctx->len += len;
 101                 return 0;
 102         }
 103
 104         /* filling odds with new data and encrypting it */
 105         memcpy(odds + ctx->len, p, bs - ctx->len);
 106         len -= bs - ctx->len;
 107         p += bs - ctx->len;
 108
 109         crypto_xor(prev, odds, bs);
 110         crypto_cipher_encrypt_one(tfm, prev, prev);
 111
 112         /* clearing the length */
 113         ctx->len = 0;
 114
 115         /* encrypting the rest of data */
 116         while (len > bs) {
 117                 crypto_xor(prev, p, bs);
 118                 crypto_cipher_encrypt_one(tfm, prev, prev);
 119                 p += bs;
 120                 len -= bs;
 121         }
 122
 123         /* keeping the surplus of blocksize */
 124         if (len) {
 125                 memcpy(odds, p, len);
 126                 ctx->len = len;
 127         }
 128
 129         return 0;
 130 }
 131
 132 static int crypto_xcbc_digest_final(struct shash_desc *pdesc, u8 *out)
 133 {
 134         struct crypto_shash *parent = pdesc->tfm;
 135         unsigned long alignmask = crypto_shash_alignmask(parent);
 136         struct xcbc_tfm_ctx *tctx = crypto_shash_ctx(parent);
 137         struct xcbc_desc_ctx *ctx = shash_desc_ctx(pdesc);
 138         struct crypto_cipher *tfm = tctx->child;
 139         int bs = crypto_shash_blocksize(parent);
 140         u8 *consts = PTR_ALIGN(&tctx->ctx[0], alignmask + 1);
 141         u8 *odds = PTR_ALIGN(&ctx->ctx[0], alignmask + 1);
 142         u8 *prev = odds + bs;
 143         unsigned int offset = 0;
 144
 145         if (ctx->len != bs) {
 146                 unsigned int rlen;
 147                 u8 *p = odds + ctx->len;
 148
 149                 *p = 0x80;
 150                 p++;
 151
 152                 rlen = bs - ctx->len -1;
 153                 if (rlen)
 154                         memset(p, 0, rlen);
 155
 156                 offset += bs;
 157         }
 158
 159         crypto_xor(prev, odds, bs);
 160         crypto_xor(prev, consts + offset, bs);
 161
 162         crypto_cipher_encrypt_one(tfm, out, prev);
 163
 164         return 0;
 165 }
 166
 167 static int xcbc_init_tfm(struct crypto_tfm *tfm)
 168 {
 169         struct crypto_cipher *cipher;
 170         struct crypto_instance *inst = (void *)tfm->__crt_alg;
 171         struct crypto_cipher_spawn *spawn = crypto_instance_ctx(inst);
 172         struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
 173
 174         cipher = crypto_spawn_cipher(spawn);
 175         if (IS_ERR(cipher))
 176                 return PTR_ERR(cipher);
 177
 178         ctx->child = cipher;
 179
 180         return 0;
 181 };
 182
 183 static void xcbc_exit_tfm(struct crypto_tfm *tfm)
 184 {
 185         struct xcbc_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
 186         crypto_free_cipher(ctx->child);
 187 }
 188
 189 static int xcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
 190 {
 191         struct shash_instance *inst;
 192         struct crypto_cipher_spawn *spawn;
 193         struct crypto_alg *alg;
 194         unsigned long alignmask;
 195         u32 mask;
 196         int err;
 197
 198         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);
 199         if (err)
 200                 return err;
 201
 202         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 203         if (!inst)
 204                 return -ENOMEM;
 205         spawn = shash_instance_ctx(inst);
 206
 207         err = crypto_grab_cipher(spawn, shash_crypto_instance(inst),
 208                                  crypto_attr_alg_name(tb[1]), 0, mask);
 209         if (err)
 210                 goto err_free_inst;
 211         alg = crypto_spawn_cipher_alg(spawn);
 212
 213         err = -EINVAL;
 214         if (alg->cra_blocksize != XCBC_BLOCKSIZE)
 215                 goto err_free_inst;
 216
 217         err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
 218         if (err)
 219                 goto err_free_inst;
 220
 221         alignmask = alg->cra_alignmask | 3;
 222         inst->alg.base.cra_alignmask = alignmask;
 223         inst->alg.base.cra_priority = alg->cra_priority;
 224         inst->alg.base.cra_blocksize = alg->cra_blocksize;
 225
 226         inst->alg.digestsize = alg->cra_blocksize;
 227         inst->alg.descsize = ALIGN(sizeof(struct xcbc_desc_ctx),
 228                                    crypto_tfm_ctx_alignment()) +
 229                              (alignmask &
 230                               ~(crypto_tfm_ctx_alignment() - 1)) +
 231                              alg->cra_blocksize * 2;
 232
 233         inst->alg.base.cra_ctxsize = ALIGN(sizeof(struct xcbc_tfm_ctx),
 234                                            alignmask + 1) +
 235                                      alg->cra_blocksize * 2;
 236         inst->alg.base.cra_init = xcbc_init_tfm;
 237         inst->alg.base.cra_exit = xcbc_exit_tfm;
 238
 239         inst->alg.init = crypto_xcbc_digest_init;
 240         inst->alg.update = crypto_xcbc_digest_update;
 241         inst->alg.final = crypto_xcbc_digest_final;
 242         inst->alg.setkey = crypto_xcbc_digest_setkey;
 243
 244         inst->free = shash_free_singlespawn_instance;
 245
 246         err = shash_register_instance(tmpl, inst);
 247         if (err) {
 248 err_free_inst:
 249                 shash_free_singlespawn_instance(inst);
 250         }
 251         return err;
 252 }
 253
 254 static struct crypto_template crypto_xcbc_tmpl = {
 255         .name = "xcbc",
 256         .create = xcbc_create,
 257         .module = THIS_MODULE,
 258 };
 259
 260 static int __init crypto_xcbc_module_init(void)
 261 {
 262         return crypto_register_template(&crypto_xcbc_tmpl);
 263 }
 264
 265 static void __exit crypto_xcbc_module_exit(void)
 266 {
 267         crypto_unregister_template(&crypto_xcbc_tmpl);
 268 }
 269
 270 subsys_initcall(crypto_xcbc_module_init);
 271 module_exit(crypto_xcbc_module_exit);
 272
 273 MODULE_LICENSE("GPL");
 274 MODULE_DESCRIPTION("XCBC keyed hash algorithm");
 275 MODULE_ALIAS_CRYPTO("xcbc");
 276 MODULE_IMPORT_NS(CRYPTO_INTERNAL);