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sha256_s390.c

/*
 * Cryptographic API.
 *
 * s390 implementation of the SHA256 Secure Hash Algorithm.
 *
 * s390 Version:
 *   Copyright IBM Corp. 2005,2007
 *   Author(s): Jan Glauber (jang@de.ibm.com)
 *
 * Derived from "crypto/sha256_generic.c"
 * and "arch/s390/crypto/sha1_s390.c"
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/crypto.h>
#include <crypto/sha.h>

#include "crypt_s390.h"

struct s390_sha256_ctx {
      u64 count;        /* message length */
      u32 state[8];
      u8 buf[2 * SHA256_BLOCK_SIZE];
};

static void sha256_init(struct crypto_tfm *tfm)
{
      struct s390_sha256_ctx *sctx = crypto_tfm_ctx(tfm);

      sctx->state[0] = SHA256_H0;
      sctx->state[1] = SHA256_H1;
      sctx->state[2] = SHA256_H2;
      sctx->state[3] = SHA256_H3;
      sctx->state[4] = SHA256_H4;
      sctx->state[5] = SHA256_H5;
      sctx->state[6] = SHA256_H6;
      sctx->state[7] = SHA256_H7;
      sctx->count = 0;
}

static void sha256_update(struct crypto_tfm *tfm, const u8 *data,
                    unsigned int len)
{
      struct s390_sha256_ctx *sctx = crypto_tfm_ctx(tfm);
      unsigned int index;
      int ret;

      /* how much is already in the buffer? */
      index = sctx->count & 0x3f;

      sctx->count += len;

      if ((index + len) < SHA256_BLOCK_SIZE)
            goto store;

      /* process one stored block */
      if (index) {
            memcpy(sctx->buf + index, data, SHA256_BLOCK_SIZE - index);
            ret = crypt_s390_kimd(KIMD_SHA_256, sctx->state, sctx->buf,
                              SHA256_BLOCK_SIZE);
            BUG_ON(ret != SHA256_BLOCK_SIZE);
            data += SHA256_BLOCK_SIZE - index;
            len -= SHA256_BLOCK_SIZE - index;
      }

      /* process as many blocks as possible */
      if (len >= SHA256_BLOCK_SIZE) {
            ret = crypt_s390_kimd(KIMD_SHA_256, sctx->state, data,
                              len & ~(SHA256_BLOCK_SIZE - 1));
            BUG_ON(ret != (len & ~(SHA256_BLOCK_SIZE - 1)));
            data += ret;
            len -= ret;
      }

store:
      /* anything left? */
      if (len)
            memcpy(sctx->buf + index , data, len);
}

/* Add padding and return the message digest */
static void sha256_final(struct crypto_tfm *tfm, u8 *out)
{
      struct s390_sha256_ctx *sctx = crypto_tfm_ctx(tfm);
      u64 bits;
      unsigned int index, end;
      int ret;

      /* must perform manual padding */
      index = sctx->count & 0x3f;
      end = (index < 56) ? SHA256_BLOCK_SIZE : (2 * SHA256_BLOCK_SIZE);

      /* start pad with 1 */
      sctx->buf[index] = 0x80;

      /* pad with zeros */
      index++;
      memset(sctx->buf + index, 0x00, end - index - 8);

      /* append message length */
      bits = sctx->count * 8;
      memcpy(sctx->buf + end - 8, &bits, sizeof(bits));

      ret = crypt_s390_kimd(KIMD_SHA_256, sctx->state, sctx->buf, end);
      BUG_ON(ret != end);

      /* copy digest to out */
      memcpy(out, sctx->state, SHA256_DIGEST_SIZE);

      /* wipe context */
      memset(sctx, 0, sizeof *sctx);
}

static struct crypto_alg alg = {
      .cra_name   =     "sha256",
      .cra_driver_name =      "sha256-s390",
      .cra_priority     =     CRYPT_S390_PRIORITY,
      .cra_flags  =     CRYPTO_ALG_TYPE_DIGEST,
      .cra_blocksize    =     SHA256_BLOCK_SIZE,
      .cra_ctxsize      =     sizeof(struct s390_sha256_ctx),
      .cra_module =     THIS_MODULE,
      .cra_list   =     LIST_HEAD_INIT(alg.cra_list),
      .cra_u            =     { .digest = {
      .dia_digestsize   =     SHA256_DIGEST_SIZE,
      .dia_init   =     sha256_init,
      .dia_update =     sha256_update,
      .dia_final  =     sha256_final } }
};

static int init(void)
{
      if (!crypt_s390_func_available(KIMD_SHA_256))
            return -EOPNOTSUPP;

      return crypto_register_alg(&alg);
}

static void __exit fini(void)
{
      crypto_unregister_alg(&alg);
}

module_init(init);
module_exit(fini);

MODULE_ALIAS("sha256");

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("SHA256 Secure Hash Algorithm");

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