/*
   * Authenc: Simple AEAD wrapper for IPsec
   *

   * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>

   *
   * 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/authenc.h>

  #include <crypto/null.h>

  #include <crypto/scatterwalk.h>

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

  #include <linux/rtnetlink.h>

  #include <linux/slab.h>
  #include <linux/spinlock.h>

  struct authenc_instance_ctx {

  	struct crypto_ahash_spawn auth;

  	struct crypto_skcipher_spawn enc;

  	unsigned int reqoff;

  };
  
  struct crypto_authenc_ctx {

  	struct crypto_ahash *auth;

  	struct crypto_skcipher *enc;
  	struct crypto_skcipher *null;

  };

  struct authenc_request_ctx {

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

  	char tail[];
  };

  static void authenc_request_complete(struct aead_request *req, int err)
  {
  	if (err != -EINPROGRESS)
  		aead_request_complete(req, err);
  }

  int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key,
  			       unsigned int keylen)

  {

  	struct rtattr *rta = (struct rtattr *)key;

  	struct crypto_authenc_key_param *param;

  	if (!RTA_OK(rta, keylen))

  		return -EINVAL;

  	if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)

  		return -EINVAL;

  	if (RTA_PAYLOAD(rta) < sizeof(*param))

  		return -EINVAL;

  
  	param = RTA_DATA(rta);

  	keys->enckeylen = be32_to_cpu(param->enckeylen);

  
  	key += RTA_ALIGN(rta->rta_len);
  	keylen -= RTA_ALIGN(rta->rta_len);

  	if (keylen < keys->enckeylen)
  		return -EINVAL;
  
  	keys->authkeylen = keylen - keys->enckeylen;
  	keys->authkey = key;
  	keys->enckey = key + keys->authkeylen;

  	return 0;
  }
  EXPORT_SYMBOL_GPL(crypto_authenc_extractkeys);
  
  static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
  				 unsigned int keylen)
  {
  	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  	struct crypto_ahash *auth = ctx->auth;

  	struct crypto_skcipher *enc = ctx->enc;

  	struct crypto_authenc_keys keys;
  	int err = -EINVAL;
  
  	if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
  		goto badkey;

  	crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  	crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc) &

  				    CRYPTO_TFM_REQ_MASK);

  	err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);

  	crypto_aead_set_flags(authenc, crypto_ahash_get_flags(auth) &

  				       CRYPTO_TFM_RES_MASK);
  
  	if (err)
  		goto out;

  	crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
  	crypto_skcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
  				       CRYPTO_TFM_REQ_MASK);
  	err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen);
  	crypto_aead_set_flags(authenc, crypto_skcipher_get_flags(enc) &

  				       CRYPTO_TFM_RES_MASK);
  
  out:

  	memzero_explicit(&keys, sizeof(keys));

  	return err;

  
  badkey:
  	crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
  	goto out;

  }

  static void authenc_geniv_ahash_done(struct crypto_async_request *areq, int err)
  {
  	struct aead_request *req = areq->data;
  	struct crypto_aead *authenc = crypto_aead_reqtfm(req);

  	struct aead_instance *inst = aead_alg_instance(authenc);
  	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);

  	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);

  	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);

  
  	if (err)
  		goto out;

  	scatterwalk_map_and_copy(ahreq->result, req->dst,
  				 req->assoclen + req->cryptlen,

  				 crypto_aead_authsize(authenc), 1);
  
  out:
  	aead_request_complete(req, err);
  }

  static int crypto_authenc_genicv(struct aead_request *req, unsigned int flags)

  {
  	struct crypto_aead *authenc = crypto_aead_reqtfm(req);

  	struct aead_instance *inst = aead_alg_instance(authenc);

  	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);

  	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);

  	struct crypto_ahash *auth = ctx->auth;
  	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);

  	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);

  	u8 *hash = areq_ctx->tail;
  	int err;

  	hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
  			   crypto_ahash_alignmask(auth) + 1);
  
  	ahash_request_set_tfm(ahreq, auth);

  	ahash_request_set_crypt(ahreq, req->dst, hash,
  				req->assoclen + req->cryptlen);
  	ahash_request_set_callback(ahreq, flags,
  				   authenc_geniv_ahash_done, req);

  
  	err = crypto_ahash_digest(ahreq);

  	if (err)

  		return err;

  	scatterwalk_map_and_copy(hash, req->dst, req->assoclen + req->cryptlen,

  				 crypto_aead_authsize(authenc), 1);

  	return 0;
  }
  
  static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
  					int err)
  {

  	struct aead_request *areq = req->data;

  	if (err)
  		goto out;

  	err = crypto_authenc_genicv(areq, 0);

  out:

  	authenc_request_complete(areq, err);

  }

  static int crypto_authenc_copy_assoc(struct aead_request *req)
  {
  	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
  	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);

  	SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);

  	skcipher_request_set_tfm(skreq, ctx->null);
  	skcipher_request_set_callback(skreq, aead_request_flags(req),
  				      NULL, NULL);
  	skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
  				   NULL);
  
  	return crypto_skcipher_encrypt(skreq);

  }

  static int crypto_authenc_encrypt(struct aead_request *req)
  {
  	struct crypto_aead *authenc = crypto_aead_reqtfm(req);

  	struct aead_instance *inst = aead_alg_instance(authenc);

  	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);

  	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);

  	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);

  	struct crypto_skcipher *enc = ctx->enc;

  	unsigned int cryptlen = req->cryptlen;

  	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
  						  ictx->reqoff);

  	struct scatterlist *src, *dst;

  	int err;

  	src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
  	dst = src;
  
  	if (req->src != req->dst) {
  		err = crypto_authenc_copy_assoc(req);
  		if (err)
  			return err;

  		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
  	}

  	skcipher_request_set_tfm(skreq, enc);
  	skcipher_request_set_callback(skreq, aead_request_flags(req),
  				      crypto_authenc_encrypt_done, req);
  	skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);

  	err = crypto_skcipher_encrypt(skreq);

  	if (err)
  		return err;

  	return crypto_authenc_genicv(req, aead_request_flags(req));

  }

  static int crypto_authenc_decrypt_tail(struct aead_request *req,
  				       unsigned int flags)

  {

  	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
  	struct aead_instance *inst = aead_alg_instance(authenc);
  	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
  	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
  	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);

  	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
  						  ictx->reqoff);

  	unsigned int authsize = crypto_aead_authsize(authenc);
  	u8 *ihash = ahreq->result + authsize;
  	struct scatterlist *src, *dst;

  	scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);

  	if (crypto_memneq(ihash, ahreq->result, authsize))
  		return -EBADMSG;

  	src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
  	dst = src;

  	if (req->src != req->dst)

  		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);

  	skcipher_request_set_tfm(skreq, ctx->enc);
  	skcipher_request_set_callback(skreq, aead_request_flags(req),
  				      req->base.complete, req->base.data);
  	skcipher_request_set_crypt(skreq, src, dst,
  				   req->cryptlen - authsize, req->iv);

  	return crypto_skcipher_decrypt(skreq);

  }

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

  {

  	struct aead_request *req = areq->data;

  	if (err)
  		goto out;

  	err = crypto_authenc_decrypt_tail(req, 0);

  out:
  	authenc_request_complete(req, err);

  }
  
  static int crypto_authenc_decrypt(struct aead_request *req)
  {
  	struct crypto_aead *authenc = crypto_aead_reqtfm(req);

  	unsigned int authsize = crypto_aead_authsize(authenc);

  	struct aead_instance *inst = aead_alg_instance(authenc);
  	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
  	struct crypto_ahash *auth = ctx->auth;
  	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
  	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
  	u8 *hash = areq_ctx->tail;

  	int err;

  	hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
  			   crypto_ahash_alignmask(auth) + 1);

  	ahash_request_set_tfm(ahreq, auth);
  	ahash_request_set_crypt(ahreq, req->src, hash,
  				req->assoclen + req->cryptlen - authsize);
  	ahash_request_set_callback(ahreq, aead_request_flags(req),
  				   authenc_verify_ahash_done, req);
  
  	err = crypto_ahash_digest(ahreq);

  	if (err)
  		return err;

  	return crypto_authenc_decrypt_tail(req, aead_request_flags(req));

  }

  static int crypto_authenc_init_tfm(struct crypto_aead *tfm)

  {

  	struct aead_instance *inst = aead_alg_instance(tfm);
  	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
  	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);

  	struct crypto_ahash *auth;

  	struct crypto_skcipher *enc;
  	struct crypto_skcipher *null;

  	int err;

  	auth = crypto_spawn_ahash(&ictx->auth);

  	if (IS_ERR(auth))
  		return PTR_ERR(auth);

  	enc = crypto_spawn_skcipher(&ictx->enc);

  	err = PTR_ERR(enc);
  	if (IS_ERR(enc))

  		goto err_free_ahash;

  	null = crypto_get_default_null_skcipher2();

  	err = PTR_ERR(null);
  	if (IS_ERR(null))
  		goto err_free_skcipher;

  	ctx->auth = auth;
  	ctx->enc = enc;

  	ctx->null = null;

  	crypto_aead_set_reqsize(
  		tfm,

  		sizeof(struct authenc_request_ctx) +

  		ictx->reqoff +

  		max_t(unsigned int,

  		      crypto_ahash_reqsize(auth) +
  		      sizeof(struct ahash_request),

  		      sizeof(struct skcipher_request) +
  		      crypto_skcipher_reqsize(enc)));

  
  	return 0;

  err_free_skcipher:

  	crypto_free_skcipher(enc);

  err_free_ahash:
  	crypto_free_ahash(auth);

  	return err;
  }

  static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)

  {

  	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);

  	crypto_free_ahash(ctx->auth);

  	crypto_free_skcipher(ctx->enc);
  	crypto_put_default_null_skcipher2();

  }

  static void crypto_authenc_free(struct aead_instance *inst)
  {
  	struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
  
  	crypto_drop_skcipher(&ctx->enc);
  	crypto_drop_ahash(&ctx->auth);
  	kfree(inst);
  }
  
  static int crypto_authenc_create(struct crypto_template *tmpl,
  				 struct rtattr **tb)

  {

  	struct crypto_attr_type *algt;

  	struct aead_instance *inst;

  	struct hash_alg_common *auth;
  	struct crypto_alg *auth_base;

  	struct skcipher_alg *enc;

  	struct authenc_instance_ctx *ctx;

  	const char *enc_name;

  	int err;

  	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;

  	auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,

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

  	if (IS_ERR(auth))

  		return PTR_ERR(auth);

  	auth_base = &auth->base;

  	enc_name = crypto_attr_alg_name(tb[2]);
  	err = PTR_ERR(enc_name);
  	if (IS_ERR(enc_name))

  		goto out_put_auth;

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

  		goto out_put_auth;

  	ctx = aead_instance_ctx(inst);

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

  	if (err)
  		goto err_free_inst;

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

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

  	if (err)
  		goto err_drop_auth;

  	enc = crypto_spawn_skcipher_alg(&ctx->enc);

  	ctx->reqoff = ALIGN(2 * auth->digestsize + auth_base->cra_alignmask,
  			    auth_base->cra_alignmask + 1);

  	err = -ENAMETOOLONG;

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

  		     "authenc(%s,%s)", auth_base->cra_name,
  		     enc->base.cra_name) >=

  	    CRYPTO_MAX_ALG_NAME)
  		goto err_drop_enc;

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

  		     "authenc(%s,%s)", auth_base->cra_driver_name,

  		     enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)

  		goto err_drop_enc;

  	inst->alg.base.cra_flags = (auth_base->cra_flags |
  				    enc->base.cra_flags) & CRYPTO_ALG_ASYNC;
  	inst->alg.base.cra_priority = enc->base.cra_priority * 10 +

  				      auth_base->cra_priority;

  	inst->alg.base.cra_blocksize = enc->base.cra_blocksize;

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

  				       enc->base.cra_alignmask;

  	inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);

  	inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
  	inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);

  	inst->alg.maxauthsize = auth->digestsize;

  	inst->alg.init = crypto_authenc_init_tfm;
  	inst->alg.exit = crypto_authenc_exit_tfm;

  	inst->alg.setkey = crypto_authenc_setkey;
  	inst->alg.encrypt = crypto_authenc_encrypt;
  	inst->alg.decrypt = crypto_authenc_decrypt;

  	inst->free = crypto_authenc_free;

  	err = aead_register_instance(tmpl, inst);
  	if (err)
  		goto err_drop_enc;

  
  out:

  	crypto_mod_put(auth_base);

  	return err;

  err_drop_enc:
  	crypto_drop_skcipher(&ctx->enc);

  err_drop_auth:

  	crypto_drop_ahash(&ctx->auth);

  err_free_inst:
  	kfree(inst);

  out_put_auth:

  	goto out;
  }

  static struct crypto_template crypto_authenc_tmpl = {
  	.name = "authenc",

  	.create = crypto_authenc_create,

  	.module = THIS_MODULE,
  };
  
  static int __init crypto_authenc_module_init(void)
  {
  	return crypto_register_template(&crypto_authenc_tmpl);
  }
  
  static void __exit crypto_authenc_module_exit(void)
  {
  	crypto_unregister_template(&crypto_authenc_tmpl);
  }
  
  module_init(crypto_authenc_module_init);
  module_exit(crypto_authenc_module_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");

  MODULE_ALIAS_CRYPTO("authenc");