crypto/chacha20poly1305.c - pub/scm/linux/kernel/git/krzk/linux-dt - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * ChaCha20-Poly1305 AEAD, RFC7539
  *
  * Copyright (C) 2015 Martin Willi
  */

 #include <crypto/internal/aead.h>
 #include <crypto/internal/hash.h>
 #include <crypto/internal/skcipher.h>
 #include <crypto/scatterwalk.h>
 #include <crypto/chacha.h>
 #include <crypto/poly1305.h>
 #include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/string.h>

 struct chachapoly_instance_ctx {
 	struct crypto_skcipher_spawn chacha;
 	unsigned int saltlen;
 };

 struct chachapoly_ctx {
 	struct crypto_skcipher *chacha;
 	/* key bytes we use for the ChaCha20 IV */
 	unsigned int saltlen;
 	u8 salt[] __counted_by(saltlen);
 };

 struct chacha_req {
 	u8 iv[CHACHA_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;
 	/* request flags, with MAY_SLEEP cleared if needed */
 	u32 flags;
 	union {
 		struct chacha_req chacha;
 	} u;
 };

 static inline void async_done_continue(struct aead_request *req, int err,
 				       int (*cont)(struct aead_request *))
 {
 	if (!err) {
 		struct chachapoly_req_ctx *rctx = aead_request_ctx(req);

 		rctx->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
 		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,
 	       CHACHA_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 void chacha_decrypt_done(void *data, int err)
 {
 	async_done_continue(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);

 	src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen);
 	dst = src;
 	if (req->src != req->dst)
 		dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);

 	skcipher_request_set_callback(&creq->req, rctx->flags,
 				      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_hash(struct aead_request *req)
 {
 	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
 	const void *zp = page_address(ZERO_PAGE(0));
 	struct scatterlist *sg = req->src;
 	struct poly1305_desc_ctx desc;
 	struct scatter_walk walk;
 	struct {
 		union {
 			struct {
 				__le64 assoclen;
 				__le64 cryptlen;
 			};
 			u8 u8[16];
 		};
 	} tail;
 	unsigned int padlen;
 	unsigned int total;

 	if (sg != req->dst)
 		memcpy_sglist(req->dst, sg, req->assoclen);

 	if (rctx->cryptlen == req->cryptlen) /* encrypting */
 		sg = req->dst;

 	poly1305_init(&desc, rctx->key);
 	scatterwalk_start(&walk, sg);

 	total = rctx->assoclen;
 	while (total) {
 		unsigned int n = scatterwalk_next(&walk, total);

 		poly1305_update(&desc, walk.addr, n);
 		scatterwalk_done_src(&walk, n);
 		total -= n;
 	}

 	padlen = -rctx->assoclen % POLY1305_BLOCK_SIZE;
 	poly1305_update(&desc, zp, padlen);

 	scatterwalk_skip(&walk, req->assoclen - rctx->assoclen);

 	total = rctx->cryptlen;
 	while (total) {
 		unsigned int n = scatterwalk_next(&walk, total);

 		poly1305_update(&desc, walk.addr, n);
 		scatterwalk_done_src(&walk, n);
 		total -= n;
 	}

 	padlen = -rctx->cryptlen % POLY1305_BLOCK_SIZE;
 	poly1305_update(&desc, zp, padlen);

 	tail.assoclen = cpu_to_le64(rctx->assoclen);
 	tail.cryptlen = cpu_to_le64(rctx->cryptlen);
 	poly1305_update(&desc, tail.u8, sizeof(tail));
 	memzero_explicit(&tail, sizeof(tail));
 	poly1305_final(&desc, rctx->tag);

 	if (rctx->cryptlen != req->cryptlen)
 		return chacha_decrypt(req);

 	memcpy_to_scatterwalk(&walk, rctx->tag, sizeof(rctx->tag));
 	return 0;
 }

 static void poly_genkey_done(void *data, int err)
 {
 	async_done_continue(data, err, poly_hash);
 }

 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;
 	}

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

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

 	skcipher_request_set_callback(&creq->req, rctx->flags,
 				      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_hash(req);
 }

 static void chacha_encrypt_done(void *data, int err)
 {
 	async_done_continue(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);

 	src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen);
 	dst = src;
 	if (req->src != req->dst)
 		dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);

 	skcipher_request_set_callback(&creq->req, rctx->flags,
 				      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;
 	rctx->flags = aead_request_flags(req);

 	/* encrypt call chain:
 	 * - chacha_encrypt/done()
 	 * - poly_genkey/done()
 	 * - poly_hash()
 	 */
 	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;
 	rctx->flags = aead_request_flags(req);

 	/* decrypt call chain:
 	 * - poly_genkey/done()
 	 * - poly_hash()
 	 * - 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);

 	if (keylen != ctx->saltlen + CHACHA_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);
 	return crypto_skcipher_setkey(ctx->chacha, key, keylen);
 }

 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;
 	unsigned long align;

 	chacha = crypto_spawn_skcipher(&ictx->chacha);
 	if (IS_ERR(chacha))
 		return PTR_ERR(chacha);

 	ctx->chacha = chacha;
 	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) +
 		offsetof(struct chacha_req, req) +
 		sizeof(struct skcipher_request) +
 		crypto_skcipher_reqsize(chacha));

 	return 0;
 }

 static void chachapoly_exit(struct crypto_aead *tfm)
 {
 	struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);

 	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);
 	kfree(inst);
 }

 static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb,
 			     const char *name, unsigned int ivsize)
 {
 	u32 mask;
 	struct aead_instance *inst;
 	struct chachapoly_instance_ctx *ctx;
 	struct skcipher_alg_common *chacha;
 	int err;

 	if (ivsize > CHACHAPOLY_IV_SIZE)
 		return -EINVAL;

 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
 	if (err)
 		return err;

 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 	if (!inst)
 		return -ENOMEM;
 	ctx = aead_instance_ctx(inst);
 	ctx->saltlen = CHACHAPOLY_IV_SIZE - ivsize;

 	err = crypto_grab_skcipher(&ctx->chacha, aead_crypto_instance(inst),
 				   crypto_attr_alg_name(tb[1]), 0, mask);
 	if (err)
 		goto err_free_inst;
 	chacha = crypto_spawn_skcipher_alg_common(&ctx->chacha);

 	err = -EINVAL;
 	if (strcmp(crypto_attr_alg_name(tb[2]), "poly1305") &&
 	    strcmp(crypto_attr_alg_name(tb[2]), "poly1305-generic"))
 		goto err_free_inst;
 	/* Need 16-byte IV size, including Initial Block Counter value */
 	if (chacha->ivsize != CHACHA_IV_SIZE)
 		goto err_free_inst;
 	/* Not a stream cipher? */
 	if (chacha->base.cra_blocksize != 1)
 		goto err_free_inst;

 	err = -ENAMETOOLONG;
 	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 		     "%s(%s,poly1305)", name,
 		     chacha->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
 		goto err_free_inst;
 	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 		     "%s(%s,poly1305-generic)", name,
 		     chacha->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
 		goto err_free_inst;

 	inst->alg.base.cra_priority = chacha->base.cra_priority;
 	inst->alg.base.cra_blocksize = 1;
 	inst->alg.base.cra_alignmask = chacha->base.cra_alignmask;
 	inst->alg.base.cra_ctxsize = sizeof(struct chachapoly_ctx) +
 				     ctx->saltlen;
 	inst->alg.ivsize = ivsize;
 	inst->alg.chunksize = chacha->chunksize;
 	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) {
 err_free_inst:
 		chachapoly_free(inst);
 	}
 	return err;
 }

 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_tmpls[] = {
 	{
 		.name = "rfc7539",
 		.create = rfc7539_create,
 		.module = THIS_MODULE,
 	}, {
 		.name = "rfc7539esp",
 		.create = rfc7539esp_create,
 		.module = THIS_MODULE,
 	},
 };

 static int __init chacha20poly1305_module_init(void)
 {
 	return crypto_register_templates(rfc7539_tmpls,
 					 ARRAY_SIZE(rfc7539_tmpls));
 }

 static void __exit chacha20poly1305_module_exit(void)
 {
 	crypto_unregister_templates(rfc7539_tmpls,
 				    ARRAY_SIZE(rfc7539_tmpls));
 }

 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");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* ChaCha20-Poly1305 AEAD, RFC7539
	*
	* Copyright (C) 2015 Martin Willi
	*/

	#include <crypto/internal/aead.h>
	#include <crypto/internal/hash.h>
	#include <crypto/internal/skcipher.h>
	#include <crypto/scatterwalk.h>
	#include <crypto/chacha.h>
	#include <crypto/poly1305.h>
	#include <linux/err.h>
	#include <linux/kernel.h>
	#include <linux/mm.h>
	#include <linux/module.h>
	#include <linux/string.h>

	struct chachapoly_instance_ctx {
	struct crypto_skcipher_spawn chacha;
	unsigned int saltlen;
	};

	struct chachapoly_ctx {
	struct crypto_skcipher *chacha;
	/* key bytes we use for the ChaCha20 IV */
	unsigned int saltlen;
	u8 salt[] __counted_by(saltlen);
	};

	struct chacha_req {
	u8 iv[CHACHA_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;
	/* request flags, with MAY_SLEEP cleared if needed */
	u32 flags;
	union {
	struct chacha_req chacha;
	} u;
	};

	static inline void async_done_continue(struct aead_request *req, int err,
	int (cont)(struct aead_request ))
	{
	if (!err) {
	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);

	rctx->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
	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,
	CHACHA_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 void chacha_decrypt_done(void *data, int err)
	{
	async_done_continue(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);

	src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen);
	dst = src;
	if (req->src != req->dst)
	dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);

	skcipher_request_set_callback(&creq->req, rctx->flags,
	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_hash(struct aead_request *req)
	{
	struct chachapoly_req_ctx *rctx = aead_request_ctx(req);
	const void *zp = page_address(ZERO_PAGE(0));
	struct scatterlist *sg = req->src;
	struct poly1305_desc_ctx desc;
	struct scatter_walk walk;
	struct {
	union {
	struct {
	__le64 assoclen;
	__le64 cryptlen;
	};
	u8 u8[16];
	};
	} tail;
	unsigned int padlen;
	unsigned int total;

	if (sg != req->dst)
	memcpy_sglist(req->dst, sg, req->assoclen);

	if (rctx->cryptlen == req->cryptlen) /* encrypting */
	sg = req->dst;

	poly1305_init(&desc, rctx->key);
	scatterwalk_start(&walk, sg);

	total = rctx->assoclen;
	while (total) {
	unsigned int n = scatterwalk_next(&walk, total);

	poly1305_update(&desc, walk.addr, n);
	scatterwalk_done_src(&walk, n);
	total -= n;
	}

	padlen = -rctx->assoclen % POLY1305_BLOCK_SIZE;
	poly1305_update(&desc, zp, padlen);

	scatterwalk_skip(&walk, req->assoclen - rctx->assoclen);

	total = rctx->cryptlen;
	while (total) {
	unsigned int n = scatterwalk_next(&walk, total);

	poly1305_update(&desc, walk.addr, n);
	scatterwalk_done_src(&walk, n);
	total -= n;
	}

	padlen = -rctx->cryptlen % POLY1305_BLOCK_SIZE;
	poly1305_update(&desc, zp, padlen);

	tail.assoclen = cpu_to_le64(rctx->assoclen);
	tail.cryptlen = cpu_to_le64(rctx->cryptlen);
	poly1305_update(&desc, tail.u8, sizeof(tail));
	memzero_explicit(&tail, sizeof(tail));
	poly1305_final(&desc, rctx->tag);

	if (rctx->cryptlen != req->cryptlen)
	return chacha_decrypt(req);

	memcpy_to_scatterwalk(&walk, rctx->tag, sizeof(rctx->tag));
	return 0;
	}

	static void poly_genkey_done(void *data, int err)
	{
	async_done_continue(data, err, poly_hash);
	}

	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;
	}

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

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

	skcipher_request_set_callback(&creq->req, rctx->flags,
	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_hash(req);
	}

	static void chacha_encrypt_done(void *data, int err)
	{
	async_done_continue(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);

	src = scatterwalk_ffwd(rctx->src, req->src, req->assoclen);
	dst = src;
	if (req->src != req->dst)
	dst = scatterwalk_ffwd(rctx->dst, req->dst, req->assoclen);

	skcipher_request_set_callback(&creq->req, rctx->flags,
	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;
	rctx->flags = aead_request_flags(req);

	/* encrypt call chain:
	* - chacha_encrypt/done()
	* - poly_genkey/done()
	* - poly_hash()
	*/
	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;
	rctx->flags = aead_request_flags(req);

	/* decrypt call chain:
	* - poly_genkey/done()
	* - poly_hash()
	* - 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);

	if (keylen != ctx->saltlen + CHACHA_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);
	return crypto_skcipher_setkey(ctx->chacha, key, keylen);
	}

	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;
	unsigned long align;

	chacha = crypto_spawn_skcipher(&ictx->chacha);
	if (IS_ERR(chacha))
	return PTR_ERR(chacha);

	ctx->chacha = chacha;
	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) +
	offsetof(struct chacha_req, req) +
	sizeof(struct skcipher_request) +
	crypto_skcipher_reqsize(chacha));

	return 0;
	}

	static void chachapoly_exit(struct crypto_aead *tfm)
	{
	struct chachapoly_ctx *ctx = crypto_aead_ctx(tfm);

	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);
	kfree(inst);
	}

	static int chachapoly_create(struct crypto_template tmpl, struct rtattr *tb,
	const char *name, unsigned int ivsize)
	{
	u32 mask;
	struct aead_instance *inst;
	struct chachapoly_instance_ctx *ctx;
	struct skcipher_alg_common *chacha;
	int err;

	if (ivsize > CHACHAPOLY_IV_SIZE)
	return -EINVAL;

	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
	if (err)
	return err;

	inst = kzalloc(sizeof(inst) + sizeof(ctx), GFP_KERNEL);
	if (!inst)
	return -ENOMEM;
	ctx = aead_instance_ctx(inst);
	ctx->saltlen = CHACHAPOLY_IV_SIZE - ivsize;

	err = crypto_grab_skcipher(&ctx->chacha, aead_crypto_instance(inst),
	crypto_attr_alg_name(tb[1]), 0, mask);
	if (err)
	goto err_free_inst;
	chacha = crypto_spawn_skcipher_alg_common(&ctx->chacha);

	err = -EINVAL;
	if (strcmp(crypto_attr_alg_name(tb[2]), "poly1305") &&
	strcmp(crypto_attr_alg_name(tb[2]), "poly1305-generic"))
	goto err_free_inst;
	/* Need 16-byte IV size, including Initial Block Counter value */
	if (chacha->ivsize != CHACHA_IV_SIZE)
	goto err_free_inst;
	/* Not a stream cipher? */
	if (chacha->base.cra_blocksize != 1)
	goto err_free_inst;

	err = -ENAMETOOLONG;
	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
	"%s(%s,poly1305)", name,
	chacha->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
	goto err_free_inst;
	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
	"%s(%s,poly1305-generic)", name,
	chacha->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
	goto err_free_inst;

	inst->alg.base.cra_priority = chacha->base.cra_priority;
	inst->alg.base.cra_blocksize = 1;
	inst->alg.base.cra_alignmask = chacha->base.cra_alignmask;
	inst->alg.base.cra_ctxsize = sizeof(struct chachapoly_ctx) +
	ctx->saltlen;
	inst->alg.ivsize = ivsize;
	inst->alg.chunksize = chacha->chunksize;
	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) {
	err_free_inst:
	chachapoly_free(inst);
	}
	return err;
	}

	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_tmpls[] = {
	{
	.name = "rfc7539",
	.create = rfc7539_create,
	.module = THIS_MODULE,
	}, {
	.name = "rfc7539esp",
	.create = rfc7539esp_create,
	.module = THIS_MODULE,
	},
	};

	static int __init chacha20poly1305_module_init(void)
	{
	return crypto_register_templates(rfc7539_tmpls,
	ARRAY_SIZE(rfc7539_tmpls));
	}

	static void __exit chacha20poly1305_module_exit(void)
	{
	crypto_unregister_templates(rfc7539_tmpls,
	ARRAY_SIZE(rfc7539_tmpls));
	}

	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");