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_cipher_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_cipher_spawn *spawn;
 192         struct crypto_alg *alg;
 193         unsigned long alignmask;
 194         int err;
 195
 196         err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
 197         if (err)
 198                 return err;
 199
 200         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
 201         if (!inst)
 202                 return -ENOMEM;
 203         spawn = shash_instance_ctx(inst);
 204
 205         err = crypto_grab_cipher(spawn, shash_crypto_instance(inst),
 206                                  crypto_attr_alg_name(tb[1]), 0, 0);
 207         if (err)
 208                 goto err_free_inst;
 209         alg = crypto_spawn_cipher_alg(spawn);
 210
 211         err = -EINVAL;
 212         if (alg->cra_blocksize != XCBC_BLOCKSIZE)
 213                 goto err_free_inst;
 214
 215         err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
 216         if (err)
 217                 goto err_free_inst;
 218
 219         alignmask = alg->cra_alignmask | 3;
 220         inst->alg.base.cra_alignmask = alignmask;
 221         inst->alg.base.cra_priority = alg->cra_priority;
 222         inst->alg.base.cra_blocksize = alg->cra_blocksize;
 223
 224         inst->alg.digestsize = alg->cra_blocksize;
 225         inst->alg.descsize = ALIGN(sizeof(struct xcbc_desc_ctx),
 226                                    crypto_tfm_ctx_alignment()) +
 227                              (alignmask &
 228                               ~(crypto_tfm_ctx_alignment() - 1)) +
 229                              alg->cra_blocksize * 2;
 230
 231         inst->alg.base.cra_ctxsize = ALIGN(sizeof(struct xcbc_tfm_ctx),
 232                                            alignmask + 1) +
 233                                      alg->cra_blocksize * 2;
 234         inst->alg.base.cra_init = xcbc_init_tfm;
 235         inst->alg.base.cra_exit = xcbc_exit_tfm;
 236
 237         inst->alg.init = crypto_xcbc_digest_init;
 238         inst->alg.update = crypto_xcbc_digest_update;
 239         inst->alg.final = crypto_xcbc_digest_final;
 240         inst->alg.setkey = crypto_xcbc_digest_setkey;
 241
 242         inst->free = shash_free_singlespawn_instance;
 243
 244         err = shash_register_instance(tmpl, inst);
 245         if (err) {
 246 err_free_inst:
 247                 shash_free_singlespawn_instance(inst);
 248         }
 249         return err;
 250 }
 251
 252 static struct crypto_template crypto_xcbc_tmpl = {
 253         .name = "xcbc",
 254         .create = xcbc_create,
 255         .module = THIS_MODULE,
 256 };
 257
 258 static int __init crypto_xcbc_module_init(void)
 259 {
 260         return crypto_register_template(&crypto_xcbc_tmpl);
 261 }
 262
 263 static void __exit crypto_xcbc_module_exit(void)
 264 {
 265         crypto_unregister_template(&crypto_xcbc_tmpl);
 266 }
 267
 268 subsys_initcall(crypto_xcbc_module_init);
 269 module_exit(crypto_xcbc_module_exit);
 270
 271 MODULE_LICENSE("GPL");
 272 MODULE_DESCRIPTION("XCBC keyed hash algorithm");
 273 MODULE_ALIAS_CRYPTO("xcbc");