path: root/crypto/aegis128-core.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * The AEGIS-128 Authenticated-Encryption Algorithm
 *
 * Copyright (c) 2017-2018 Ondrej Mosnacek <omosnacek@gmail.com>
 * Copyright (C) 2017-2018 Red Hat, Inc. All rights reserved.
 */

#include <crypto/algapi.h>
#include <crypto/internal/aead.h>
#include <crypto/internal/simd.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/jump_label.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/scatterlist.h>

#include <asm/simd.h>

#include "aegis.h"

#define AEGIS128_NONCE_SIZE 16
#define AEGIS128_STATE_BLOCKS 5
#define AEGIS128_KEY_SIZE 16
#define AEGIS128_MIN_AUTH_SIZE 8
#define AEGIS128_MAX_AUTH_SIZE 16

struct aegis_state {
	union aegis_block blocks[AEGIS128_STATE_BLOCKS];
};

struct aegis_ctx {
	union aegis_block key;
};

static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_simd);

static const union aegis_block crypto_aegis_const[2] = {
	{ .words64 = {
		cpu_to_le64(U64_C(0x0d08050302010100)),
		cpu_to_le64(U64_C(0x6279e99059372215)),
	} },
	{ .words64 = {
		cpu_to_le64(U64_C(0xf12fc26d55183ddb)),
		cpu_to_le64(U64_C(0xdd28b57342311120)),
	} },
};

static bool aegis128_do_simd(void)
{
#ifdef CONFIG_CRYPTO_AEGIS128_SIMD
	if (static_branch_likely(&have_simd))
		return crypto_simd_usable();
#endif
	return false;
}

bool crypto_aegis128_have_simd(void);
void crypto_aegis128_update_simd(struct aegis_state *state, const void *msg);
void crypto_aegis128_init_simd(struct aegis_state *state,
			       const union aegis_block *key,
			       const u8 *iv);
void crypto_aegis128_encrypt_chunk_simd(struct aegis_state *state, u8 *dst,
					const u8 *src, unsigned int size);
void crypto_aegis128_decrypt_chunk_simd(struct aegis_state *state, u8 *dst,
					const u8 *src, unsigned int size);
int crypto_aegis128_final_simd(struct aegis_state *state,
			       union aegis_block *tag_xor,
			       unsigned int assoclen,
			       unsigned int cryptlen,
			       unsigned int authsize);

static void crypto_aegis128_update(struct aegis_state *state)
{
	union aegis_block tmp;
	unsigned int i;

	tmp = state->blocks[AEGIS128_STATE_BLOCKS - 1];
	for (i = AEGIS128_STATE_BLOCKS - 1; i > 0; i--)
		crypto_aegis_aesenc(&state->blocks[i], &state->blocks[i - 1],
				    &state->blocks[i]);
	crypto_aegis_aesenc(&state->blocks[0], &tmp, &state->blocks[0]);
}

static void crypto_aegis128_update_a(struct aegis_state *state,
				     const union aegis_block *msg)
{
	if (aegis128_do_simd()) {
		crypto_aegis128_update_simd(state, msg);
		return;
	}

	crypto_aegis128_update(state);
	crypto_aegis_block_xor(&state->blocks[0], msg);
}

static void crypto_aegis128_update_u(struct aegis_state *state, const void *msg)
{
	if (aegis128_do_simd()) {
		crypto_aegis128_update_simd(state, msg);
		return;
	}

	crypto_aegis128_update(state);
	crypto_xor(state->blocks[0].bytes, msg, AEGIS_BLOCK_SIZE);
}

static void crypto_aegis128_init(struct aegis_state *state,
				 const union aegis_block *key,
				 const u8 *iv)
{
	union aegis_block key_iv;
	unsigned int i;

	key_iv = *key;
	crypto_xor(key_iv.bytes, iv, AEGIS_BLOCK_SIZE);

	state->blocks[0] = key_iv;
	state->blocks[1] = crypto_aegis_const[1];
	state->blocks[2] = crypto_aegis_const[0];
	state->blocks[3] = *key;
	state->blocks[4] = *key;

	crypto_aegis_block_xor(&state->blocks[3], &crypto_aegis_const[0]);
	crypto_aegis_block_xor(&state->blocks[4], &crypto_aegis_const[1]);

	for (i = 0; i < 5; i++) {
		crypto_aegis128_update_a(state, key);
		crypto_aegis128_update_a(state, &key_iv);
	}
}

static void crypto_aegis128_ad(struct aegis_state *state,
			       const u8 *src, unsigned int size)
{
	if (AEGIS_ALIGNED(src)) {
		const union aegis_block *src_blk =
				(const union aegis_block *)src;

		while (size >= AEGIS_BLOCK_SIZE) {
			crypto_aegis128_update_a(state, src_blk);

			size -= AEGIS_BLOCK_SIZE;
			src_blk++;
		}
	} else {
		while (size >= AEGIS_BLOCK_SIZE) {
			crypto_aegis128_update_u(state, src);

			size -= AEGIS_BLOCK_SIZE;
			src += AEGIS_BLOCK_SIZE;
		}
	}
}

static void crypto_aegis128_wipe_chunk(struct aegis_state *state, u8 *dst,
				       const u8 *src, unsigned int size)
{
	memzero_explicit(dst, size);
}

static void crypto_aegis128_encrypt_chunk(struct aegis_state *state, u8 *dst,
					  const u8 *src, unsigned int size)
{
	union aegis_block tmp;

	if (AEGIS_ALIGNED(src) && AEGIS_ALIGNED(dst)) {
		while (size >= AEGIS_BLOCK_SIZE) {
			union aegis_block *dst_blk =
					(union aegis_block *)dst;
			const union aegis_block *src_blk =
					(const union aegis_block *)src;

			tmp = state->blocks[2];
			crypto_aegis_block_and(&tmp, &state->blocks[3]);
			crypto_aegis_block_xor(&tmp, &state->blocks[4]);
			crypto_aegis_block_xor(&tmp, &state->blocks[1]);
			crypto_aegis_block_xor(&tmp, src_blk);

			crypto_aegis128_update_a(state, src_blk);

			*dst_blk = tmp;

			size -= AEGIS_BLOCK_SIZE;
			src += AEGIS_BLOCK_SIZE;
			dst += AEGIS_BLOCK_SIZE;
		}
	} else {
		while (size >= AEGIS_BLOCK_SIZE) {
			tmp = state->blocks[2];
			crypto_aegis_block_and(&tmp, &state->blocks[3]);
			crypto_aegis_block_xor(&tmp, &state->blocks[4]);
			crypto_aegis_block_xor(&tmp, &state->blocks[1]);
			crypto_xor(tmp.bytes, src, AEGIS_BLOCK_SIZE);

			crypto_aegis128_update_u(state, src);

			memcpy(dst, tmp.bytes, AEGIS_BLOCK_SIZE);

			size -= AEGIS_BLOCK_SIZE;
			src += AEGIS_BLOCK_SIZE;
			dst += AEGIS_BLOCK_SIZE;
		}
	}

	if (size > 0) {
		union aegis_block msg = {};
		memcpy(msg.bytes, src, size);

		tmp = state->blocks[2];
		crypto_aegis_block_and(&tmp, &state->blocks[3]);
		crypto_aegis_block_xor(&tmp, &state->blocks[4]);
		crypto_aegis_block_xor(&tmp, &state->blocks[1]);

		crypto_aegis128_update_a(state, &msg);

		crypto_aegis_block_xor(&msg, &tmp);

		memcpy(dst, msg.bytes, size);
	}
}

static void crypto_aegis128_decrypt_chunk(struct aegis_state *state, u8 *dst,
					  const u8 *src, unsigned int size)
{
	union aegis_block tmp;

	if (AEGIS_ALIGNED(src) && AEGIS_ALIGNED(dst)) {
		while (size >= AEGIS_BLOCK_SIZE) {
			union aegis_block *dst_blk =
					(union aegis_block *)dst;
			const union aegis_block *src_blk =
					(const union aegis_block *)src;

			tmp = state->blocks[2];
			crypto_aegis_block_and(&tmp, &state->blocks[3]);
			crypto_aegis_block_xor(&tmp, &state->blocks[4]);
			crypto_aegis_block_xor(&tmp, &state->blocks[1]);
			crypto_aegis_block_xor(&tmp, src_blk);

			crypto_aegis128_update_a(state, &tmp);

			*dst_blk = tmp;

			size -= AEGIS_BLOCK_SIZE;
			src += AEGIS_BLOCK_SIZE;
			dst += AEGIS_BLOCK_SIZE;
		}
	} else {
		while (size >= AEGIS_BLOCK_SIZE) {
			tmp = state->blocks[2];
			crypto_aegis_block_and(&tmp, &state->blocks[3]);
			crypto_aegis_block_xor(&tmp, &state->blocks[4]);
			crypto_aegis_block_xor(&tmp, &state->blocks[1]);
			crypto_xor(tmp.bytes, src, AEGIS_BLOCK_SIZE);

			crypto_aegis128_update_a(state, &tmp);

			memcpy(dst, tmp.bytes, AEGIS_BLOCK_SIZE);

			size -= AEGIS_BLOCK_SIZE;
			src += AEGIS_BLOCK_SIZE;
			dst += AEGIS_BLOCK_SIZE;
		}
	}

	if (size > 0) {
		union aegis_block msg = {};
		memcpy(msg.bytes, src, size);

		tmp = state->blocks[2];
		crypto_aegis_block_and(&tmp, &state->blocks[3]);
		crypto_aegis_block_xor(&tmp, &state->blocks[4]);
		crypto_aegis_block_xor(&tmp, &state->blocks[1]);
		crypto_aegis_block_xor(&msg, &tmp);

		memset(msg.bytes + size, 0, AEGIS_BLOCK_SIZE - size);

		crypto_aegis128_update_a(state, &msg);

		memcpy(dst, msg.bytes, size);
	}
}

static void crypto_aegis128_process_ad(struct aegis_state *state,
				       struct scatterlist *sg_src,
				       unsigned int assoclen)
{
	struct scatter_walk walk;
	union aegis_block buf;
	unsigned int pos = 0;

	scatterwalk_start(&walk, sg_src);
	while (assoclen != 0) {
		unsigned int size = scatterwalk_clamp(&walk, assoclen);
		unsigned int left = size;
		void *mapped = scatterwalk_map(&walk);
		const u8 *src = (const u8 *)mapped;

		if (pos + size >= AEGIS_BLOCK_SIZE) {
			if (pos > 0) {
				unsigned int fill = AEGIS_BLOCK_SIZE - pos;
				memcpy(buf.bytes + pos, src, fill);
				crypto_aegis128_update_a(state, &buf);
				pos = 0;
				left -= fill;
				src += fill;
			}

			crypto_aegis128_ad(state, src, left);
			src += left & ~(AEGIS_BLOCK_SIZE - 1);
			left &= AEGIS_BLOCK_SIZE - 1;
		}

		memcpy(buf.bytes + pos, src, left);

		pos += left;
		assoclen -= size;
		scatterwalk_unmap(mapped);
		scatterwalk_advance(&walk, size);
		scatterwalk_done(&walk, 0, assoclen);
	}

	if (pos > 0) {
		memset(buf.bytes + pos, 0, AEGIS_BLOCK_SIZE - pos);
		crypto_aegis128_update_a(state, &buf);
	}
}

static __always_inline
int crypto_aegis128_process_crypt(struct aegis_state *state,
				  struct skcipher_walk *walk,
				  void (*crypt)(struct aegis_state *state,
					        u8 *dst, const u8 *src,
					        unsigned int size))
{
	int err = 0;

	while (walk->nbytes) {
		unsigned int nbytes = walk->nbytes;

		if (nbytes < walk->total)
			nbytes = round_down(nbytes, walk->stride);

		crypt(state, walk->dst.virt.addr, walk->src.virt.addr, nbytes);

		err = skcipher_walk_done(walk, walk->nbytes - nbytes);
	}
	return err;
}

static void crypto_aegis128_final(struct aegis_state *state,
				  union aegis_block *tag_xor,
				  u64 assoclen, u64 cryptlen)
{
	u64 assocbits = assoclen * 8;
	u64 cryptbits = cryptlen * 8;

	union aegis_block tmp;
	unsigned int i;

	tmp.words64[0] = cpu_to_le64(assocbits);
	tmp.words64[1] = cpu_to_le64(cryptbits);

	crypto_aegis_block_xor(&tmp, &state->blocks[3]);

	for (i = 0; i < 7; i++)
		crypto_aegis128_update_a(state, &tmp);

	for (i = 0; i < AEGIS128_STATE_BLOCKS; i++)
		crypto_aegis_block_xor(tag_xor, &state->blocks[i]);
}

static int crypto_aegis128_setkey(struct crypto_aead *aead, const u8 *key,
				  unsigned int keylen)
{
	struct aegis_ctx *ctx = crypto_aead_ctx(aead);

	if (keylen != AEGIS128_KEY_SIZE)
		return -EINVAL;

	memcpy(ctx->key.bytes, key, AEGIS128_KEY_SIZE);
	return 0;
}

static int crypto_aegis128_setauthsize(struct crypto_aead *tfm,
				       unsigned int authsize)
{
	if (authsize > AEGIS128_MAX_AUTH_SIZE)
		return -EINVAL;
	if (authsize < AEGIS128_MIN_AUTH_SIZE)
		return -EINVAL;
	return 0;
}

static int crypto_aegis128_encrypt(struct aead_request *req)
{
	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
	union aegis_block tag = {};
	unsigned int authsize = crypto_aead_authsize(tfm);
	struct aegis_ctx *ctx = crypto_aead_ctx(tfm);
	unsigned int cryptlen = req->cryptlen;
	struct skcipher_walk walk;
	struct aegis_state state;

	skcipher_walk_aead_encrypt(&walk, req, false);
	if (aegis128_do_simd()) {
		crypto_aegis128_init_simd(&state, &ctx->key, req->iv);
		crypto_aegis128_process_ad(&state, req->src, req->assoclen);
		crypto_aegis128_process_crypt(&state, &walk,
					      crypto_aegis128_encrypt_chunk_simd);
		crypto_aegis128_final_simd(&state, &tag, req->assoclen,
					   cryptlen, 0);
	} else {
		crypto_aegis128_init(&state, &ctx->key, req->iv);
		crypto_aegis128_process_ad(&state, req->src, req->assoclen);
		crypto_aegis128_process_crypt(&state, &walk,
					      crypto_aegis128_encrypt_chunk);
		crypto_aegis128_final(&state, &tag, req->assoclen, cryptlen);
	}

	scatterwalk_map_and_copy(tag.bytes, req->dst, req->assoclen + cryptlen,
				 authsize, 1);
	return 0;
}

static int crypto_aegis128_decrypt(struct aead_request *req)
{
	static const u8 zeros[AEGIS128_MAX_AUTH_SIZE] = {};
	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
	union aegis_block tag;
	unsigned int authsize = crypto_aead_authsize(tfm);
	unsigned int cryptlen = req->cryptlen - authsize;
	struct aegis_ctx *ctx = crypto_aead_ctx(tfm);
	struct skcipher_walk walk;
	struct aegis_state state;

	scatterwalk_map_and_copy(tag.bytes, req->src, req->assoclen + cryptlen,
				 authsize, 0);

	skcipher_walk_aead_decrypt(&walk, req, false);
	if (aegis128_do_simd()) {
		crypto_aegis128_init_simd(&state, &ctx->key, req->iv);
		crypto_aegis128_process_ad(&state, req->src, req->assoclen);
		crypto_aegis128_process_crypt(&state, &walk,
					      crypto_aegis128_decrypt_chunk_simd);
		if (unlikely(crypto_aegis128_final_simd(&state, &tag,
							req->assoclen,
							cryptlen, authsize))) {
			skcipher_walk_aead_decrypt(&walk, req, false);
			crypto_aegis128_process_crypt(NULL, req, &walk,
						      crypto_aegis128_wipe_chunk);
			return -EBADMSG;
		}
		return 0;
	} else {
		crypto_aegis128_init(&state, &ctx->key, req->iv);
		crypto_aegis128_process_ad(&state, req->src, req->assoclen);
		crypto_aegis128_process_crypt(&state, &walk,
					      crypto_aegis128_decrypt_chunk);
		crypto_aegis128_final(&state, &tag, req->assoclen, cryptlen);
	}

	if (unlikely(crypto_memneq(tag.bytes, zeros, authsize))) {
		/*
		 * From Chapter 4. 'Security Analysis' of the AEGIS spec [0]
		 *
		 * "3. If verification fails, the decrypted plaintext and the
		 *     wrong authentication tag should not be given as output."
		 *
		 * [0] https://competitions.cr.yp.to/round3/aegisv11.pdf
		 */
		skcipher_walk_aead_decrypt(&walk, req, false);
		crypto_aegis128_process_crypt(NULL, &walk,
					      crypto_aegis128_wipe_chunk);
		memzero_explicit(&tag, sizeof(tag));
		return -EBADMSG;
	}
	return 0;
}

static struct aead_alg crypto_aegis128_alg = {
	.setkey = crypto_aegis128_setkey,
	.setauthsize = crypto_aegis128_setauthsize,
	.encrypt = crypto_aegis128_encrypt,
	.decrypt = crypto_aegis128_decrypt,

	.ivsize = AEGIS128_NONCE_SIZE,
	.maxauthsize = AEGIS128_MAX_AUTH_SIZE,
	.chunksize = AEGIS_BLOCK_SIZE,

	.base = {
		.cra_blocksize = 1,
		.cra_ctxsize = sizeof(struct aegis_ctx),
		.cra_alignmask = 0,

		.cra_priority = 100,

		.cra_name = "aegis128",
		.cra_driver_name = "aegis128-generic",

		.cra_module = THIS_MODULE,
	}
};

static int __init crypto_aegis128_module_init(void)
{
	if (IS_ENABLED(CONFIG_CRYPTO_AEGIS128_SIMD) &&
	    crypto_aegis128_have_simd())
		static_branch_enable(&have_simd);

	return crypto_register_aead(&crypto_aegis128_alg);
}

static void __exit crypto_aegis128_module_exit(void)
{
	crypto_unregister_aead(&crypto_aegis128_alg);
}

subsys_initcall(crypto_aegis128_module_init);
module_exit(crypto_aegis128_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Ondrej Mosnacek <omosnacek@gmail.com>");
MODULE_DESCRIPTION("AEGIS-128 AEAD algorithm");
MODULE_ALIAS_CRYPTO("aegis128");
MODULE_ALIAS_CRYPTO("aegis128-generic");