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/*

 * 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");