/*

 * Copyright (C) 2011-2016 Free Software Foundation, Inc.

 * Copyright (C) 2015-2018 Red Hat, Inc.

 *

 * Author: Nikos Mavrogiannopoulos

 *

 * This file is part of GnuTLS.

 *

 * The GnuTLS is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public License

 * as published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this program.  If not, see <https://www.gnu.org/licenses/>

 *

 */

/*

 * The following code is an implementation of the AES-128-GCM cipher

 * using intel's AES instruction set.

 */

#include "errors.h"

#include "gnutls_int.h"

#include <gnutls/crypto.h>

#include "errors.h"

#include <aes-x86.h>

#include <x86-common.h>

#include <nettle/memxor.h>

#include <byteswap.h>

#define GCM_BLOCK_SIZE 16

/* GCM mode with PCLMUL and AVX optimization */

typedef struct {

	uint64_t hi, lo;

} u128;

/* This is the gcm128 structure used in openssl. It

 * is compatible with the included assembly code.

 */

struct gcm128_context {

	union {

		uint64_t u[2];

		uint32_t d[4];

		uint8_t c[16];

		size_t t[16 / sizeof(size_t)];

	} Yi, EKi, EK0, len, Xi, H;

	u128 Htable[16];

};

struct aes_gcm_ctx {

	AES_KEY expanded_key;

	struct gcm128_context gcm;

	unsigned finished;

	unsigned auth_finished;

};

void gcm_init_avx(u128 Htable[16], const uint64_t Xi[2]);

void gcm_ghash_avx(uint64_t Xi[2], const u128 Htable[16], const uint8_t *in, size_t len);

void gcm_gmult_avx(uint64_t Xi[2], const u128 Htable[16]);

static void aes_gcm_deinit(void *_ctx)

{

	struct aes_gcm_ctx *ctx = _ctx;

	zeroize_temp_key(ctx, sizeof(*ctx));

	gnutls_free(ctx);

}

static int

aes_gcm_cipher_init(gnutls_cipher_algorithm_t algorithm, void **_ctx,

		    int enc)

{

	/* we use key size to distinguish */

	if (algorithm != GNUTLS_CIPHER_AES_128_GCM &&

	    algorithm != GNUTLS_CIPHER_AES_192_GCM &&

	    algorithm != GNUTLS_CIPHER_AES_256_GCM)

		return GNUTLS_E_INVALID_REQUEST;

	*_ctx = gnutls_calloc(1, sizeof(struct aes_gcm_ctx));

	if (*_ctx == NULL) {

		gnutls_assert();

		return GNUTLS_E_MEMORY_ERROR;

	}

	return 0;

}

static int

aes_gcm_cipher_setkey(void *_ctx, const void *userkey, size_t keysize)

{

	struct aes_gcm_ctx *ctx = _ctx;

	int ret;

	CHECK_AES_KEYSIZE(keysize);

	ret =

	    aesni_set_encrypt_key(userkey, keysize * 8,

				  ALIGN16(&ctx->expanded_key));

	if (ret != 0)

		return gnutls_assert_val(GNUTLS_E_ENCRYPTION_FAILED);

	aesni_ecb_encrypt(ctx->gcm.H.c, ctx->gcm.H.c,

			  GCM_BLOCK_SIZE, ALIGN16(&ctx->expanded_key), 1);

	ctx->gcm.H.u[0] = bswap_64(ctx->gcm.H.u[0]);

	ctx->gcm.H.u[1] = bswap_64(ctx->gcm.H.u[1]);

	gcm_init_avx(ctx->gcm.Htable, ctx->gcm.H.u);

	return 0;

}

static int aes_gcm_setiv(void *_ctx, const void *iv, size_t iv_size)

{

	struct aes_gcm_ctx *ctx = _ctx;

	if (iv_size != GCM_BLOCK_SIZE - 4)

		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	memset(ctx->gcm.Xi.c, 0, sizeof(ctx->gcm.Xi.c));

	memset(ctx->gcm.len.c, 0, sizeof(ctx->gcm.len.c));

	memcpy(ctx->gcm.Yi.c, iv, GCM_BLOCK_SIZE - 4);

	ctx->gcm.Yi.c[GCM_BLOCK_SIZE - 4] = 0;

	ctx->gcm.Yi.c[GCM_BLOCK_SIZE - 3] = 0;

	ctx->gcm.Yi.c[GCM_BLOCK_SIZE - 2] = 0;

	ctx->gcm.Yi.c[GCM_BLOCK_SIZE - 1] = 1;

	aesni_ecb_encrypt(ctx->gcm.Yi.c, ctx->gcm.EK0.c,

			  GCM_BLOCK_SIZE, ALIGN16(&ctx->expanded_key), 1);

	ctx->gcm.Yi.c[GCM_BLOCK_SIZE - 1] = 2;

	ctx->finished = 0;

	ctx->auth_finished = 0;

	return 0;

}

static void

gcm_ghash(struct aes_gcm_ctx *ctx, const uint8_t * src, size_t src_size)

{

	size_t rest = src_size % GCM_BLOCK_SIZE;

	size_t aligned_size = src_size - rest;

	if (aligned_size > 0)

		gcm_ghash_avx(ctx->gcm.Xi.u, ctx->gcm.Htable, src,

				aligned_size);

	if (rest > 0) {

		memxor(ctx->gcm.Xi.c, src + aligned_size, rest);

		gcm_gmult_avx(ctx->gcm.Xi.u, ctx->gcm.Htable);

	}

}

static inline void

ctr_encrypt_last(struct aes_gcm_ctx *ctx, const uint8_t * src,

		 uint8_t * dst, size_t pos, size_t length)

{

	uint8_t tmp[GCM_BLOCK_SIZE];

	uint8_t out[GCM_BLOCK_SIZE];

	memcpy(tmp, &src[pos], length);

	aesni_ctr32_encrypt_blocks(tmp, out, 1,

				   ALIGN16(&ctx->expanded_key),

				   ctx->gcm.Yi.c);

	memcpy(&dst[pos], out, length);

}

static int

aes_gcm_encrypt(void *_ctx, const void *src, size_t src_size,

		void *dst, size_t length)

{

	struct aes_gcm_ctx *ctx = _ctx;

	int blocks = src_size / GCM_BLOCK_SIZE;

	int exp_blocks = blocks * GCM_BLOCK_SIZE;

	int rest = src_size - (exp_blocks);

	uint32_t counter;

	if (unlikely(ctx->finished))

		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	if (blocks > 0) {

		aesni_ctr32_encrypt_blocks(src, dst,

					   blocks,

					   ALIGN16(&ctx->expanded_key),

					   ctx->gcm.Yi.c);

		counter = _gnutls_read_uint32(ctx->gcm.Yi.c + 12);

		counter += blocks;

		_gnutls_write_uint32(counter, ctx->gcm.Yi.c + 12);

	}

	if (rest > 0) {	/* last incomplete block */

		ctr_encrypt_last(ctx, src, dst, exp_blocks, rest);

		ctx->finished = 1;

	}

	gcm_ghash(ctx, dst, src_size);

	ctx->gcm.len.u[1] += src_size;

	return 0;

}

static int

aes_gcm_decrypt(void *_ctx, const void *src, size_t src_size,

		void *dst, size_t dst_size)

{

	struct aes_gcm_ctx *ctx = _ctx;

	int blocks = src_size / GCM_BLOCK_SIZE;

	int exp_blocks = blocks * GCM_BLOCK_SIZE;

	int rest = src_size - (exp_blocks);

	uint32_t counter;

	if (unlikely(ctx->finished))

		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	gcm_ghash(ctx, src, src_size);

	ctx->gcm.len.u[1] += src_size;

	if (blocks > 0) {

		aesni_ctr32_encrypt_blocks(src, dst,

					   blocks,

					   ALIGN16(&ctx->expanded_key),

					   ctx->gcm.Yi.c);

		counter = _gnutls_read_uint32(ctx->gcm.Yi.c + 12);

		counter += blocks;

		_gnutls_write_uint32(counter, ctx->gcm.Yi.c + 12);

	}

	if (rest > 0) {	/* last incomplete block */

		ctr_encrypt_last(ctx, src, dst, exp_blocks, rest);

		ctx->finished = 1;

	}

	return 0;

}

static int aes_gcm_auth(void *_ctx, const void *src, size_t src_size)

{

	struct aes_gcm_ctx *ctx = _ctx;

	if (unlikely(ctx->auth_finished))

		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

	gcm_ghash(ctx, src, src_size);

	ctx->gcm.len.u[0] += src_size;

	if (src_size % GCM_BLOCK_SIZE != 0)

		ctx->auth_finished = 1;

	return 0;

}

static void aes_gcm_tag(void *_ctx, void *tag, size_t tagsize)

{

	struct aes_gcm_ctx *ctx = _ctx;

	uint8_t buffer[GCM_BLOCK_SIZE];

	uint64_t alen, clen;

	alen = ctx->gcm.len.u[0] * 8;

	clen = ctx->gcm.len.u[1] * 8;

	_gnutls_write_uint64(alen, buffer);

	_gnutls_write_uint64(clen, &buffer[8]);

	gcm_ghash_avx(ctx->gcm.Xi.u, ctx->gcm.Htable, buffer,

			GCM_BLOCK_SIZE);

	ctx->gcm.Xi.u[0] ^= ctx->gcm.EK0.u[0];

	ctx->gcm.Xi.u[1] ^= ctx->gcm.EK0.u[1];

	memcpy(tag, ctx->gcm.Xi.c, MIN(GCM_BLOCK_SIZE, tagsize));

}

#ifdef ASM_X86_64

/* requires AVX */

static int

aesni_gcm_aead_encrypt(void *_ctx,

			const void *nonce, size_t nonce_size,

			const void *auth, size_t auth_size,

			size_t tag_size,

			const void *plain, size_t plain_size,

		   	void *encr, size_t encr_size)

{

	struct aes_gcm_ctx *ctx = _ctx;

	size_t s = 0;

	if (encr_size < plain_size + tag_size)

		return gnutls_assert_val(GNUTLS_E_SHORT_MEMORY_BUFFER);

	aes_gcm_setiv(ctx, nonce, nonce_size);

	aes_gcm_auth(ctx, auth, auth_size);

	if (plain_size >= 96) {

		s = aesni_gcm_encrypt(plain, encr, plain_size, ALIGN16(&ctx->expanded_key),

			ctx->gcm.Yi.c, ctx->gcm.Xi.u);

		ctx->gcm.len.u[1] += s;

	}

	if ((plain_size-s) > 0)

		aes_gcm_encrypt(ctx, ((uint8_t*)plain)+s, plain_size-s, ((uint8_t*)encr)+s, encr_size-s);

	aes_gcm_tag(ctx, ((uint8_t*)encr) + plain_size, tag_size);

	return 0;

}

static int

aesni_gcm_aead_decrypt(void *_ctx,

			const void *nonce, size_t nonce_size,

			const void *auth, size_t auth_size,

			size_t tag_size,

		   	const void *encr, size_t encr_size,

			void *plain, size_t plain_size)

{

	struct aes_gcm_ctx *ctx = _ctx;

	uint8_t tag[MAX_HASH_SIZE];

	size_t s = 0;

	if (encr_size < tag_size)

		return gnutls_assert_val(GNUTLS_E_DECRYPTION_FAILED);

	aes_gcm_setiv(ctx, nonce, nonce_size);

	aes_gcm_auth(ctx, auth, auth_size);

	encr_size -= tag_size;

	if (encr_size >= 96) {

		s = aesni_gcm_decrypt(encr, plain, encr_size, ALIGN16(&ctx->expanded_key),

			ctx->gcm.Yi.c, ctx->gcm.Xi.u);

		ctx->gcm.len.u[1] += s;

	}

	if ((encr_size-s) > 0) {

		aes_gcm_decrypt(ctx, ((uint8_t*)encr)+s, encr_size-s, ((uint8_t*)plain)+s, plain_size-s);

	}

	aes_gcm_tag(ctx, tag, tag_size);

	if (gnutls_memcmp(((uint8_t*)encr)+encr_size, tag, tag_size) != 0)

		return gnutls_assert_val(GNUTLS_E_DECRYPTION_FAILED);

	return 0;

}

#else

# define aesni_gcm_aead_decrypt aes_gcm_aead_decrypt

# define aesni_gcm_aead_encrypt aes_gcm_aead_encrypt

# include "aes-gcm-aead.h"

#endif

const gnutls_crypto_cipher_st _gnutls_aes_gcm_pclmul_avx = {

	.init = aes_gcm_cipher_init,

	.setkey = aes_gcm_cipher_setkey,

	.setiv = aes_gcm_setiv,

	.aead_encrypt = aesni_gcm_aead_encrypt,

	.aead_decrypt = aesni_gcm_aead_decrypt,

	.encrypt = aes_gcm_encrypt,

	.decrypt = aes_gcm_decrypt,

	.deinit = aes_gcm_deinit,

	.tag = aes_gcm_tag,

	.auth = aes_gcm_auth,

};