/*
   * ChaCha20-Poly1305 AEAD, RFC7539
   *
   * Copyright (C) 2015 Martin Willi
   *
   * 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 <crypto/internal/aead.h>
  #include <crypto/internal/hash.h>
  #include <crypto/internal/skcipher.h>
  #include <crypto/scatterwalk.h>

  #include <crypto/chacha20.h>

  #include <crypto/poly1305.h>

  #include <linux/err.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  
  #include "internal.h"

  #define CHACHAPOLY_IV_SIZE	12
  
  struct chachapoly_instance_ctx {
  	struct crypto_skcipher_spawn chacha;
  	struct crypto_ahash_spawn poly;
  	unsigned int saltlen;
  };
  
  struct chachapoly_ctx {

  	struct crypto_skcipher *chacha;

  	struct crypto_ahash *poly;
  	/* key bytes we use for the ChaCha20 IV */
  	unsigned int saltlen;
  	u8 salt[];
  };
  
  struct poly_req {
  	/* zero byte padding for AD/ciphertext, as needed */
  	u8 pad[POLY1305_BLOCK_SIZE];
  	/* tail data with AD/ciphertext lengths */
  	struct {
  		__le64 assoclen;
  		__le64 cryptlen;
  	} tail;
  	struct scatterlist src[1];
  	struct ahash_request req; /* must be last member */
  };
  
  struct chacha_req {

  	u8 iv[CHACHA20_IV_SIZE];
  	struct scatterlist src[1];

  	struct skcipher_request req; /* must be last member */

  };
  
  struct chachapoly_req_ctx {

  	struct scatterlist src[2];
  	struct scatterlist dst[2];

  	/* the key we generate for Poly1305 using Chacha20 */
  	u8 key[POLY1305_KEY_SIZE];

  	/* calculated Poly1305 tag */
  	u8 tag[POLY1305_DIGEST_SIZE];
  	/* length of data to en/decrypt, without ICV */
  	unsigned int cryptlen;

  	/* Actual AD, excluding IV */
  	unsigned int assoclen;

  	union {
  		struct poly_req poly;
  		struct chacha_req chacha;
  	} u;
  };
  
  static inline void async_done_continue(struct aead_request *req, int err,
  				       int (*cont)(struct aead_request *))
  {
  	if (!err)
  		err = cont(req);
  
  	if (err != -EINPROGRESS && err != -EBUSY)
  		aead_request_complete(req, err);
  }
  
  static void chacha_iv(u8 *iv, struct aead_request *req, u32 icb)
  {
  	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
  	__le32 leicb = cpu_to_le32(icb);
  
  	memcpy(iv, &leicb, sizeof(leicb));
  	memcpy(iv + sizeof(leicb), ctx->salt, ctx->saltlen);
  	memcpy(iv + sizeof(leicb) + ctx->saltlen, req->iv,
  	       CHACHA20_IV_SIZE - sizeof(leicb) - ctx->saltlen);
  }
  
  static int poly_verify_tag(struct aead_request *req)
  {
  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
  	u8 tag[sizeof(rctx->tag)];

  	scatterwalk_map_and_copy(tag, req->src,
  				 req->assoclen + rctx->cryptlen,
  				 sizeof(tag), 0);

  	if (crypto_memneq(tag, rctx->tag, sizeof(tag)))
  		return -EBADMSG;
  	return 0;
  }
  
  static int poly_copy_tag(struct aead_request *req)
  {
  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);

  	scatterwalk_map_and_copy(rctx->tag, req->dst,
  				 req->assoclen + rctx->cryptlen,

  				 sizeof(rctx->tag), 1);
  	return 0;
  }
  
  static void chacha_decrypt_done(struct crypto_async_request *areq, int err)
  {
  	async_done_continue(areq->data, err, poly_verify_tag);
  }
  
  static int chacha_decrypt(struct aead_request *req)
  {
  	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
  	struct chacha_req *creq = &rctx->u.chacha;

  	struct scatterlist *src, *dst;

  	int err;

  	if (rctx->cryptlen == 0)
  		goto skip;

  	chacha_iv(creq->iv, req, 1);

  	sg_init_table(rctx->src, 2);
  	src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen);
  	dst = src;
  
  	if (req->src != req->dst) {
  		sg_init_table(rctx->dst, 2);
  		dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);
  	}

  	skcipher_request_set_callback(&creq->req, aead_request_flags(req),
  				      chacha_decrypt_done, req);
  	skcipher_request_set_tfm(&creq->req, ctx->chacha);
  	skcipher_request_set_crypt(&creq->req, src, dst,
  				   rctx->cryptlen, creq->iv);
  	err = crypto_skcipher_decrypt(&creq->req);

  	if (err)
  		return err;

  skip:

  	return poly_verify_tag(req);
  }
  
  static int poly_tail_continue(struct aead_request *req)
  {
  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
  
  	if (rctx->cryptlen == req->cryptlen) /* encrypting */
  		return poly_copy_tag(req);
  
  	return chacha_decrypt(req);
  }
  
  static void poly_tail_done(struct crypto_async_request *areq, int err)
  {
  	async_done_continue(areq->data, err, poly_tail_continue);
  }
  
  static int poly_tail(struct aead_request *req)
  {

  	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
  	struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);

  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
  	struct poly_req *preq = &rctx->u.poly;
  	__le64 len;
  	int err;
  
  	sg_init_table(preq->src, 1);

  	len = cpu_to_le64(rctx->assoclen);

  	memcpy(&preq->tail.assoclen, &len, sizeof(len));
  	len = cpu_to_le64(rctx->cryptlen);
  	memcpy(&preq->tail.cryptlen, &len, sizeof(len));
  	sg_set_buf(preq->src, &preq->tail, sizeof(preq->tail));
  
  	ahash_request_set_callback(&preq->req, aead_request_flags(req),
  				   poly_tail_done, req);
  	ahash_request_set_tfm(&preq->req, ctx->poly);
  	ahash_request_set_crypt(&preq->req, preq->src,
  				rctx->tag, sizeof(preq->tail));
  
  	err = crypto_ahash_finup(&preq->req);
  	if (err)
  		return err;
  
  	return poly_tail_continue(req);
  }
  
  static void poly_cipherpad_done(struct crypto_async_request *areq, int err)
  {
  	async_done_continue(areq->data, err, poly_tail);
  }
  
  static int poly_cipherpad(struct aead_request *req)
  {
  	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
  	struct poly_req *preq = &rctx->u.poly;
  	unsigned int padlen, bs = POLY1305_BLOCK_SIZE;
  	int err;
  
  	padlen = (bs - (rctx->cryptlen % bs)) % bs;
  	memset(preq->pad, 0, sizeof(preq->pad));
  	sg_init_table(preq->src, 1);
  	sg_set_buf(preq->src, &preq->pad, padlen);
  
  	ahash_request_set_callback(&preq->req, aead_request_flags(req),
  				   poly_cipherpad_done, req);
  	ahash_request_set_tfm(&preq->req, ctx->poly);
  	ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen);
  
  	err = crypto_ahash_update(&preq->req);
  	if (err)
  		return err;
  
  	return poly_tail(req);
  }
  
  static void poly_cipher_done(struct crypto_async_request *areq, int err)
  {
  	async_done_continue(areq->data, err, poly_cipherpad);
  }
  
  static int poly_cipher(struct aead_request *req)
  {
  	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
  	struct poly_req *preq = &rctx->u.poly;
  	struct scatterlist *crypt = req->src;
  	int err;
  
  	if (rctx->cryptlen == req->cryptlen) /* encrypting */
  		crypt = req->dst;

  	sg_init_table(rctx->src, 2);
  	crypt = scatterwalk_ffwd(rctx->src, crypt, req->assoclen);

  	ahash_request_set_callback(&preq->req, aead_request_flags(req),
  				   poly_cipher_done, req);
  	ahash_request_set_tfm(&preq->req, ctx->poly);
  	ahash_request_set_crypt(&preq->req, crypt, NULL, rctx->cryptlen);
  
  	err = crypto_ahash_update(&preq->req);
  	if (err)
  		return err;
  
  	return poly_cipherpad(req);
  }
  
  static void poly_adpad_done(struct crypto_async_request *areq, int err)
  {
  	async_done_continue(areq->data, err, poly_cipher);
  }
  
  static int poly_adpad(struct aead_request *req)
  {
  	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
  	struct poly_req *preq = &rctx->u.poly;
  	unsigned int padlen, bs = POLY1305_BLOCK_SIZE;
  	int err;

  	padlen = (bs - (rctx->assoclen % bs)) % bs;

  	memset(preq->pad, 0, sizeof(preq->pad));
  	sg_init_table(preq->src, 1);
  	sg_set_buf(preq->src, preq->pad, padlen);
  
  	ahash_request_set_callback(&preq->req, aead_request_flags(req),
  				   poly_adpad_done, req);
  	ahash_request_set_tfm(&preq->req, ctx->poly);
  	ahash_request_set_crypt(&preq->req, preq->src, NULL, padlen);
  
  	err = crypto_ahash_update(&preq->req);
  	if (err)
  		return err;
  
  	return poly_cipher(req);
  }
  
  static void poly_ad_done(struct crypto_async_request *areq, int err)
  {
  	async_done_continue(areq->data, err, poly_adpad);
  }
  
  static int poly_ad(struct aead_request *req)
  {
  	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
  	struct poly_req *preq = &rctx->u.poly;
  	int err;
  
  	ahash_request_set_callback(&preq->req, aead_request_flags(req),
  				   poly_ad_done, req);
  	ahash_request_set_tfm(&preq->req, ctx->poly);

  	ahash_request_set_crypt(&preq->req, req->src, NULL, rctx->assoclen);

  
  	err = crypto_ahash_update(&preq->req);
  	if (err)
  		return err;
  
  	return poly_adpad(req);
  }

  static void poly_setkey_done(struct crypto_async_request *areq, int err)

  {
  	async_done_continue(areq->data, err, poly_ad);
  }

  static int poly_setkey(struct aead_request *req)

  {
  	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
  	struct poly_req *preq = &rctx->u.poly;
  	int err;

  	sg_init_table(preq->src, 1);
  	sg_set_buf(preq->src, rctx->key, sizeof(rctx->key));

  	ahash_request_set_callback(&preq->req, aead_request_flags(req),

  				   poly_setkey_done, req);

  	ahash_request_set_tfm(&preq->req, ctx->poly);

  	ahash_request_set_crypt(&preq->req, preq->src, NULL, sizeof(rctx->key));

  	err = crypto_ahash_update(&preq->req);

  	if (err)
  		return err;
  
  	return poly_ad(req);
  }

  static void poly_init_done(struct crypto_async_request *areq, int err)

  {

  	async_done_continue(areq->data, err, poly_setkey);
  }
  
  static int poly_init(struct aead_request *req)
  {
  	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));

  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);

  	struct poly_req *preq = &rctx->u.poly;

  	int err;

  	ahash_request_set_callback(&preq->req, aead_request_flags(req),
  				   poly_init_done, req);
  	ahash_request_set_tfm(&preq->req, ctx->poly);

  	err = crypto_ahash_init(&preq->req);

  	if (err)
  		return err;

  	return poly_setkey(req);

  }
  
  static void poly_genkey_done(struct crypto_async_request *areq, int err)
  {

  	async_done_continue(areq->data, err, poly_init);

  }
  
  static int poly_genkey(struct aead_request *req)
  {

  	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
  	struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);

  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
  	struct chacha_req *creq = &rctx->u.chacha;
  	int err;

  	rctx->assoclen = req->assoclen;
  
  	if (crypto_aead_ivsize(tfm) == 8) {
  		if (rctx->assoclen < 8)
  			return -EINVAL;
  		rctx->assoclen -= 8;
  	}

  	sg_init_table(creq->src, 1);

  	memset(rctx->key, 0, sizeof(rctx->key));
  	sg_set_buf(creq->src, rctx->key, sizeof(rctx->key));

  
  	chacha_iv(creq->iv, req, 0);

  	skcipher_request_set_callback(&creq->req, aead_request_flags(req),
  				      poly_genkey_done, req);
  	skcipher_request_set_tfm(&creq->req, ctx->chacha);
  	skcipher_request_set_crypt(&creq->req, creq->src, creq->src,
  				   POLY1305_KEY_SIZE, creq->iv);

  	err = crypto_skcipher_decrypt(&creq->req);

  	if (err)
  		return err;

  	return poly_init(req);

  }
  
  static void chacha_encrypt_done(struct crypto_async_request *areq, int err)
  {
  	async_done_continue(areq->data, err, poly_genkey);
  }
  
  static int chacha_encrypt(struct aead_request *req)
  {
  	struct chachapoly_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
  	struct chacha_req *creq = &rctx->u.chacha;

  	struct scatterlist *src, *dst;

  	int err;

  	if (req->cryptlen == 0)
  		goto skip;

  	chacha_iv(creq->iv, req, 1);

  	sg_init_table(rctx->src, 2);
  	src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen);
  	dst = src;
  
  	if (req->src != req->dst) {
  		sg_init_table(rctx->dst, 2);
  		dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);
  	}

  	skcipher_request_set_callback(&creq->req, aead_request_flags(req),
  				      chacha_encrypt_done, req);
  	skcipher_request_set_tfm(&creq->req, ctx->chacha);
  	skcipher_request_set_crypt(&creq->req, src, dst,
  				   req->cryptlen, creq->iv);
  	err = crypto_skcipher_encrypt(&creq->req);

  	if (err)
  		return err;

  skip:

  	return poly_genkey(req);
  }
  
  static int chachapoly_encrypt(struct aead_request *req)
  {
  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
  
  	rctx->cryptlen = req->cryptlen;
  
  	/* encrypt call chain:
  	 * - chacha_encrypt/done()

  	 * - poly_genkey/done()

  	 * - poly_init/done()

  	 * - poly_setkey/done()

  	 * - poly_ad/done()
  	 * - poly_adpad/done()
  	 * - poly_cipher/done()
  	 * - poly_cipherpad/done()
  	 * - poly_tail/done/continue()
  	 * - poly_copy_tag()
  	 */
  	return chacha_encrypt(req);
  }
  
  static int chachapoly_decrypt(struct aead_request *req)
  {
  	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);

  	rctx->cryptlen = req->cryptlen - POLY1305_DIGEST_SIZE;
  
  	/* decrypt call chain:

  	 * - poly_genkey/done()

  	 * - poly_init/done()

  	 * - poly_setkey/done()

  	 * - poly_ad/done()
  	 * - poly_adpad/done()
  	 * - poly_cipher/done()
  	 * - poly_cipherpad/done()
  	 * - poly_tail/done/continue()
  	 * - chacha_decrypt/done()
  	 * - poly_verify_tag()
  	 */
  	return poly_genkey(req);
  }
  
  static int chachapoly_setkey(struct crypto_aead *aead, const u8 *key,
  			     unsigned int keylen)
  {
  	struct chachapoly_ctx *ctx = crypto_aead_ctx(aead);
  	int err;
  
  	if (keylen != ctx->saltlen + CHACHA20_KEY_SIZE)
  		return -EINVAL;
  
  	keylen -= ctx->saltlen;
  	memcpy(ctx->salt, key + keylen, ctx->saltlen);

  	crypto_skcipher_clear_flags(ctx->chacha, CRYPTO_TFM_REQ_MASK);
  	crypto_skcipher_set_flags(ctx->chacha, crypto_aead_get_flags(aead) &
  					       CRYPTO_TFM_REQ_MASK);

  	err = crypto_skcipher_setkey(ctx->chacha, key, keylen);
  	crypto_aead_set_flags(aead, crypto_skcipher_get_flags(ctx->chacha) &
  				    CRYPTO_TFM_RES_MASK);

  	return err;
  }
  
  static int chachapoly_setauthsize(struct crypto_aead *tfm,
  				  unsigned int authsize)
  {
  	if (authsize != POLY1305_DIGEST_SIZE)
  		return -EINVAL;
  
  	return 0;
  }

  static int chachapoly_init(struct crypto_aead *tfm)

  {

  	struct aead_instance *inst = aead_alg_instance(tfm);
  	struct chachapoly_instance_ctx *ictx = aead_instance_ctx(inst);
  	struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);

  	struct crypto_skcipher *chacha;

  	struct crypto_ahash *poly;
  	unsigned long align;
  
  	poly = crypto_spawn_ahash(&ictx->poly);
  	if (IS_ERR(poly))
  		return PTR_ERR(poly);

  	chacha = crypto_spawn_skcipher(&ictx->chacha);

  	if (IS_ERR(chacha)) {
  		crypto_free_ahash(poly);
  		return PTR_ERR(chacha);
  	}
  
  	ctx->chacha = chacha;
  	ctx->poly = poly;
  	ctx->saltlen = ictx->saltlen;

  	align = crypto_aead_alignmask(tfm);

  	align &= ~(crypto_tfm_ctx_alignment() - 1);

  	crypto_aead_set_reqsize(
  		tfm,
  		align + offsetof(struct chachapoly_req_ctx, u) +
  		max(offsetof(struct chacha_req, req) +

  		    sizeof(struct skcipher_request) +
  		    crypto_skcipher_reqsize(chacha),

  		    offsetof(struct poly_req, req) +
  		    sizeof(struct ahash_request) +
  		    crypto_ahash_reqsize(poly)));

  
  	return 0;
  }

  static void chachapoly_exit(struct crypto_aead *tfm)

  {

  	struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);

  
  	crypto_free_ahash(ctx->poly);

  	crypto_free_skcipher(ctx->chacha);

  }

  static void chachapoly_free(struct aead_instance *inst)
  {
  	struct chachapoly_instance_ctx *ctx = aead_instance_ctx(inst);
  
  	crypto_drop_skcipher(&ctx->chacha);
  	crypto_drop_ahash(&ctx->poly);
  	kfree(inst);
  }
  
  static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb,
  			     const char *name, unsigned int ivsize)

  {
  	struct crypto_attr_type *algt;

  	struct aead_instance *inst;

  	struct skcipher_alg *chacha;

  	struct crypto_alg *poly;

  	struct hash_alg_common *poly_hash;

  	struct chachapoly_instance_ctx *ctx;
  	const char *chacha_name, *poly_name;
  	int err;
  
  	if (ivsize > CHACHAPOLY_IV_SIZE)

  		return -EINVAL;

  
  	algt = crypto_get_attr_type(tb);
  	if (IS_ERR(algt))

  		return PTR_ERR(algt);

  	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)

  		return -EINVAL;

  
  	chacha_name = crypto_attr_alg_name(tb[1]);
  	if (IS_ERR(chacha_name))

  		return PTR_ERR(chacha_name);

  	poly_name = crypto_attr_alg_name(tb[2]);
  	if (IS_ERR(poly_name))

  		return PTR_ERR(poly_name);

  
  	poly = crypto_find_alg(poly_name, &crypto_ahash_type,
  			       CRYPTO_ALG_TYPE_HASH,

  			       CRYPTO_ALG_TYPE_AHASH_MASK |
  			       crypto_requires_sync(algt->type,
  						    algt->mask));

  	if (IS_ERR(poly))

  		return PTR_ERR(poly);

  	poly_hash = __crypto_hash_alg_common(poly);
  
  	err = -EINVAL;
  	if (poly_hash->digestsize != POLY1305_DIGEST_SIZE)
  		goto out_put_poly;

  
  	err = -ENOMEM;
  	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
  	if (!inst)
  		goto out_put_poly;

  	ctx = aead_instance_ctx(inst);

  	ctx->saltlen = CHACHAPOLY_IV_SIZE - ivsize;

  	err = crypto_init_ahash_spawn(&ctx->poly, poly_hash,
  				      aead_crypto_instance(inst));

  	if (err)
  		goto err_free_inst;

  	crypto_set_skcipher_spawn(&ctx->chacha, aead_crypto_instance(inst));

  	err = crypto_grab_skcipher(&ctx->chacha, chacha_name, 0,
  				   crypto_requires_sync(algt->type,
  							algt->mask));

  	if (err)
  		goto err_drop_poly;

  	chacha = crypto_spawn_skcipher_alg(&ctx->chacha);

  
  	err = -EINVAL;
  	/* Need 16-byte IV size, including Initial Block Counter value */

  	if (crypto_skcipher_alg_ivsize(chacha) != CHACHA20_IV_SIZE)

  		goto out_drop_chacha;
  	/* Not a stream cipher? */

  	if (chacha->base.cra_blocksize != 1)

  		goto out_drop_chacha;
  
  	err = -ENAMETOOLONG;

  	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,

  		     "%s(%s,%s)", name, chacha_name,
  		     poly_name) >= CRYPTO_MAX_ALG_NAME)
  		goto out_drop_chacha;

  	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,

  		     "%s(%s,%s)", name, chacha->base.cra_driver_name,

  		     poly->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
  		goto out_drop_chacha;

  	inst->alg.base.cra_flags = (chacha->base.cra_flags | poly->cra_flags) &

  				   CRYPTO_ALG_ASYNC;

  	inst->alg.base.cra_priority = (chacha->base.cra_priority +

  				       poly->cra_priority) / 2;
  	inst->alg.base.cra_blocksize = 1;

  	inst->alg.base.cra_alignmask = chacha->base.cra_alignmask |

  				       poly->cra_alignmask;
  	inst->alg.base.cra_ctxsize = sizeof(struct chachapoly_ctx) +
  				     ctx->saltlen;
  	inst->alg.ivsize = ivsize;

  	inst->alg.chunksize = crypto_skcipher_alg_chunksize(chacha);

  	inst->alg.maxauthsize = POLY1305_DIGEST_SIZE;
  	inst->alg.init = chachapoly_init;
  	inst->alg.exit = chachapoly_exit;
  	inst->alg.encrypt = chachapoly_encrypt;
  	inst->alg.decrypt = chachapoly_decrypt;
  	inst->alg.setkey = chachapoly_setkey;
  	inst->alg.setauthsize = chachapoly_setauthsize;
  
  	inst->free = chachapoly_free;
  
  	err = aead_register_instance(tmpl, inst);
  	if (err)
  		goto out_drop_chacha;
  
  out_put_poly:

  	crypto_mod_put(poly);

  	return err;

  
  out_drop_chacha:
  	crypto_drop_skcipher(&ctx->chacha);
  err_drop_poly:
  	crypto_drop_ahash(&ctx->poly);
  err_free_inst:
  	kfree(inst);

  	goto out_put_poly;

  }

  static int rfc7539_create(struct crypto_template *tmpl, struct rtattr **tb)

  {

  	return chachapoly_create(tmpl, tb, "rfc7539", 12);

  }

  static int rfc7539esp_create(struct crypto_template *tmpl, struct rtattr **tb)

  {

  	return chachapoly_create(tmpl, tb, "rfc7539esp", 8);

  }
  
  static struct crypto_template rfc7539_tmpl = {
  	.name = "rfc7539",

  	.create = rfc7539_create,

  	.module = THIS_MODULE,
  };

  static struct crypto_template rfc7539esp_tmpl = {
  	.name = "rfc7539esp",

  	.create = rfc7539esp_create,

  	.module = THIS_MODULE,
  };

  static int __init chacha20poly1305_module_init(void)
  {

  	int err;
  
  	err = crypto_register_template(&rfc7539_tmpl);
  	if (err)
  		return err;
  
  	err = crypto_register_template(&rfc7539esp_tmpl);
  	if (err)
  		crypto_unregister_template(&rfc7539_tmpl);
  
  	return err;

  }
  
  static void __exit chacha20poly1305_module_exit(void)
  {

  	crypto_unregister_template(&rfc7539esp_tmpl);

  	crypto_unregister_template(&rfc7539_tmpl);
  }
  
  module_init(chacha20poly1305_module_init);
  module_exit(chacha20poly1305_module_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
  MODULE_DESCRIPTION("ChaCha20-Poly1305 AEAD");

  MODULE_ALIAS_CRYPTO("rfc7539");

  MODULE_ALIAS_CRYPTO("rfc7539esp");