// SPDX-License-Identifier: GPL-2.0
/*
 * Cryptographic API.
 *
 * s390 implementation of the GHASH algorithm for GCM (Galois/Counter Mode).
 *
 * Copyright IBM Corp. 2011
 * Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
 */

#include <asm/cpacf.h>
#include <crypto/ghash.h>
#include <crypto/internal/hash.h>
#include <linux/cpufeature.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>

struct s390_ghash_ctx {
        u8 key[GHASH_BLOCK_SIZE];
};

struct s390_ghash_desc_ctx {
        u8 icv[GHASH_BLOCK_SIZE];
        u8 key[GHASH_BLOCK_SIZE];
};

static int ghash_init(struct shash_desc *desc)
{
        struct s390_ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
        struct s390_ghash_desc_ctx *dctx = shash_desc_ctx(desc);

        memset(dctx, 0, sizeof(*dctx));
        memcpy(dctx->key, ctx->key, GHASH_BLOCK_SIZE);

        return 0;
}

static int ghash_setkey(struct crypto_shash *tfm,
                        const u8 *key, unsigned int keylen)
{
        struct s390_ghash_ctx *ctx = crypto_shash_ctx(tfm);

        if (keylen != GHASH_BLOCK_SIZE)
                return -EINVAL;

        memcpy(ctx->key, key, GHASH_BLOCK_SIZE);

        return 0;
}

static int ghash_update(struct shash_desc *desc,
                         const u8 *src, unsigned int srclen)
{
        struct s390_ghash_desc_ctx *dctx = shash_desc_ctx(desc);
        unsigned int n;

        n = srclen & ~(GHASH_BLOCK_SIZE - 1);
        cpacf_kimd(CPACF_KIMD_GHASH, dctx, src, n);
        return srclen - n;
}

static void ghash_flush(struct s390_ghash_desc_ctx *dctx, const u8 *src,
                        unsigned int len)
{
        if (len) {
                u8 buf[GHASH_BLOCK_SIZE] = {};

                memcpy(buf, src, len);
                cpacf_kimd(CPACF_KIMD_GHASH, dctx, buf, GHASH_BLOCK_SIZE);
                memzero_explicit(buf, sizeof(buf));
        }
}

static int ghash_finup(struct shash_desc *desc, const u8 *src,
                       unsigned int len, u8 *dst)
{
        struct s390_ghash_desc_ctx *dctx = shash_desc_ctx(desc);

        ghash_flush(dctx, src, len);
        memcpy(dst, dctx->icv, GHASH_BLOCK_SIZE);
        return 0;
}

static int ghash_export(struct shash_desc *desc, void *out)
{
        struct s390_ghash_desc_ctx *dctx = shash_desc_ctx(desc);

        memcpy(out, dctx->icv, GHASH_DIGEST_SIZE);
        return 0;
}

static int ghash_import(struct shash_desc *desc, const void *in)
{
        struct s390_ghash_ctx *ctx = crypto_shash_ctx(desc->tfm);
        struct s390_ghash_desc_ctx *dctx = shash_desc_ctx(desc);

        memcpy(dctx->icv, in, GHASH_DIGEST_SIZE);
        memcpy(dctx->key, ctx->key, GHASH_BLOCK_SIZE);
        return 0;
}

static struct shash_alg ghash_alg = {
        .digestsize     = GHASH_DIGEST_SIZE,
        .init           = ghash_init,
        .update         = ghash_update,
        .finup          = ghash_finup,
        .setkey         = ghash_setkey,
        .export         = ghash_export,
        .import         = ghash_import,
        .statesize      = sizeof(struct ghash_desc_ctx),
        .descsize       = sizeof(struct s390_ghash_desc_ctx),
        .base           = {
                .cra_name               = "ghash",
                .cra_driver_name        = "ghash-s390",
                .cra_priority           = 300,
                .cra_flags              = CRYPTO_AHASH_ALG_BLOCK_ONLY,
                .cra_blocksize          = GHASH_BLOCK_SIZE,
                .cra_ctxsize            = sizeof(struct s390_ghash_ctx),
                .cra_module             = THIS_MODULE,
        },
};

static int __init ghash_mod_init(void)
{
        if (!cpacf_query_func(CPACF_KIMD, CPACF_KIMD_GHASH))
                return -ENODEV;

        return crypto_register_shash(&ghash_alg);
}

static void __exit ghash_mod_exit(void)
{
        crypto_unregister_shash(&ghash_alg);
}

module_cpu_feature_match(S390_CPU_FEATURE_MSA, ghash_mod_init);
module_exit(ghash_mod_exit);

MODULE_ALIAS_CRYPTO("ghash");

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("GHASH hash function, s390 implementation");