linux/crypto/xcbc.c
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   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
  15static 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 */
  28struct 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 */
  44struct xcbc_desc_ctx {
  45        unsigned int len;
  46        u8 ctx[];
  47};
  48
  49#define XCBC_BLOCKSIZE  16
  50
  51static 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
  72static 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
  85static 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
 132static 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
 167static 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
 183static 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
 189static 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) {
 248err_free_inst:
 249                shash_free_singlespawn_instance(inst);
 250        }
 251        return err;
 252}
 253
 254static struct crypto_template crypto_xcbc_tmpl = {
 255        .name = "xcbc",
 256        .create = xcbc_create,
 257        .module = THIS_MODULE,
 258};
 259
 260static int __init crypto_xcbc_module_init(void)
 261{
 262        return crypto_register_template(&crypto_xcbc_tmpl);
 263}
 264
 265static void __exit crypto_xcbc_module_exit(void)
 266{
 267        crypto_unregister_template(&crypto_xcbc_tmpl);
 268}
 269
 270subsys_initcall(crypto_xcbc_module_init);
 271module_exit(crypto_xcbc_module_exit);
 272
 273MODULE_LICENSE("GPL");
 274MODULE_DESCRIPTION("XCBC keyed hash algorithm");
 275MODULE_ALIAS_CRYPTO("xcbc");
 276MODULE_IMPORT_NS(CRYPTO_INTERNAL);
 277
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