text: // 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);
  void crypto_aegis128_final_simd(struct aegis_state *state,
  				union aegis_block *tag_xor,
  				u64 assoclen, u64 cryptlen);
  
  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_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 aead_request *req,
  				  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, req, &walk,
  					      crypto_aegis128_encrypt_chunk_simd);
  		crypto_aegis128_final_simd(&state, &tag, req->assoclen,
  					   cryptlen);
  	} else {
  		crypto_aegis128_init(&state, &ctx->key, req->iv);
  		crypto_aegis128_process_ad(&state, req->src, req->assoclen);
  		crypto_aegis128_process_crypt(&state, req, &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, req, &walk,
  					      crypto_aegis128_decrypt_chunk_simd);
  		crypto_aegis128_final_simd(&state, &tag, req->assoclen,
  					   cryptlen);
  	} else {
  		crypto_aegis128_init(&state, &ctx->key, req->iv);
  		crypto_aegis128_process_ad(&state, req->src, req->assoclen);
  		crypto_aegis128_process_crypt(&state, req, &walk,
  					      crypto_aegis128_decrypt_chunk);
  		crypto_aegis128_final(&state, &tag, req->assoclen, cryptlen);
  	}
  
  	return crypto_memneq(tag.bytes, zeros, authsize) ? -EBADMSG : 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");
  