/*
   * Authenc: Simple AEAD wrapper for IPsec
   *
   * Copyright (c) 2007 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/aead.h>

  #include <crypto/internal/skcipher.h>

  #include <crypto/authenc.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_spawn auth;

  	struct crypto_skcipher_spawn enc;

  };
  
  struct crypto_authenc_ctx {
  	spinlock_t auth_lock;
  	struct crypto_hash *auth;
  	struct crypto_ablkcipher *enc;
  };
  
  static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
  				 unsigned int keylen)
  {

  	unsigned int authkeylen;

  	unsigned int enckeylen;

  	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  	struct crypto_hash *auth = ctx->auth;
  	struct crypto_ablkcipher *enc = ctx->enc;

  	struct rtattr *rta = (void *)key;
  	struct crypto_authenc_key_param *param;

  	int err = -EINVAL;

  	if (!RTA_OK(rta, keylen))

  		goto badkey;
  	if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
  		goto badkey;
  	if (RTA_PAYLOAD(rta) < sizeof(*param))
  		goto badkey;
  
  	param = RTA_DATA(rta);
  	enckeylen = be32_to_cpu(param->enckeylen);
  
  	key += RTA_ALIGN(rta->rta_len);
  	keylen -= RTA_ALIGN(rta->rta_len);
  
  	if (keylen < enckeylen)
  		goto badkey;

  	authkeylen = keylen - enckeylen;
  
  	crypto_hash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
  	crypto_hash_set_flags(auth, crypto_aead_get_flags(authenc) &
  				    CRYPTO_TFM_REQ_MASK);
  	err = crypto_hash_setkey(auth, key, authkeylen);
  	crypto_aead_set_flags(authenc, crypto_hash_get_flags(auth) &
  				       CRYPTO_TFM_RES_MASK);
  
  	if (err)
  		goto out;
  
  	crypto_ablkcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
  	crypto_ablkcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
  					 CRYPTO_TFM_REQ_MASK);
  	err = crypto_ablkcipher_setkey(enc, key + authkeylen, enckeylen);
  	crypto_aead_set_flags(authenc, crypto_ablkcipher_get_flags(enc) &
  				       CRYPTO_TFM_RES_MASK);
  
  out:
  	return err;

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

  }

  static void authenc_chain(struct scatterlist *head, struct scatterlist *sg,
  			  int chain)
  {
  	if (chain) {
  		head->length += sg->length;
  		sg = scatterwalk_sg_next(sg);
  	}
  
  	if (sg)
  		scatterwalk_sg_chain(head, 2, sg);
  	else
  		sg_mark_end(head);
  }

  static u8 *crypto_authenc_hash(struct aead_request *req, unsigned int flags,
  			       struct scatterlist *cipher,
  			       unsigned int cryptlen)

  {
  	struct crypto_aead *authenc = crypto_aead_reqtfm(req);

  	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  	struct crypto_hash *auth = ctx->auth;
  	struct hash_desc desc = {
  		.tfm = auth,

  		.flags = aead_request_flags(req) & flags,

  	};
  	u8 *hash = aead_request_ctx(req);

  	int err;
  
  	hash = (u8 *)ALIGN((unsigned long)hash + crypto_hash_alignmask(auth), 
  			   crypto_hash_alignmask(auth) + 1);
  
  	spin_lock_bh(&ctx->auth_lock);
  	err = crypto_hash_init(&desc);
  	if (err)
  		goto auth_unlock;
  
  	err = crypto_hash_update(&desc, req->assoc, req->assoclen);
  	if (err)
  		goto auth_unlock;

  	err = crypto_hash_update(&desc, cipher, cryptlen);

  	if (err)
  		goto auth_unlock;
  
  	err = crypto_hash_final(&desc, hash);
  auth_unlock:
  	spin_unlock_bh(&ctx->auth_lock);
  
  	if (err)

  		return ERR_PTR(err);
  
  	return hash;
  }

  static int crypto_authenc_genicv(struct aead_request *req, u8 *iv,
  				 unsigned int flags)

  {
  	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
  	struct scatterlist *dst = req->dst;

  	struct scatterlist cipher[2];
  	struct page *dstp;
  	unsigned int ivsize = crypto_aead_ivsize(authenc);
  	unsigned int cryptlen;
  	u8 *vdst;

  	u8 *hash;

  	dstp = sg_page(dst);
  	vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + dst->offset;
  
  	sg_init_table(cipher, 2);
  	sg_set_buf(cipher, iv, ivsize);
  	authenc_chain(cipher, dst, vdst == iv + ivsize);
  
  	cryptlen = req->cryptlen + ivsize;
  	hash = crypto_authenc_hash(req, flags, cipher, cryptlen);

  	if (IS_ERR(hash))
  		return PTR_ERR(hash);

  	scatterwalk_map_and_copy(hash, cipher, cryptlen,

  				 crypto_aead_authsize(authenc), 1);

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

  	if (!err) {
  		struct aead_request *areq = req->data;
  		struct crypto_aead *authenc = crypto_aead_reqtfm(areq);
  		struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  		struct ablkcipher_request *abreq = aead_request_ctx(areq);
  		u8 *iv = (u8 *)(abreq + 1) +
  			 crypto_ablkcipher_reqsize(ctx->enc);
  
  		err = crypto_authenc_genicv(areq, iv, 0);
  	}

  
  	aead_request_complete(req->data, err);
  }
  
  static int crypto_authenc_encrypt(struct aead_request *req)
  {
  	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
  	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  	struct ablkcipher_request *abreq = aead_request_ctx(req);

  	struct crypto_ablkcipher *enc = ctx->enc;
  	struct scatterlist *dst = req->dst;
  	unsigned int cryptlen = req->cryptlen;
  	u8 *iv = (u8 *)(abreq + 1) + crypto_ablkcipher_reqsize(enc);

  	int err;

  	ablkcipher_request_set_tfm(abreq, enc);

  	ablkcipher_request_set_callback(abreq, aead_request_flags(req),
  					crypto_authenc_encrypt_done, req);

  	ablkcipher_request_set_crypt(abreq, req->src, dst, cryptlen, req->iv);
  
  	memcpy(iv, req->iv, crypto_aead_ivsize(authenc));

  
  	err = crypto_ablkcipher_encrypt(abreq);
  	if (err)
  		return err;

  	return crypto_authenc_genicv(req, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
  }
  
  static void crypto_authenc_givencrypt_done(struct crypto_async_request *req,
  					   int err)
  {
  	if (!err) {

  		struct aead_request *areq = req->data;
  		struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);

  		err = crypto_authenc_genicv(areq, greq->giv, 0);

  	}
  
  	aead_request_complete(req->data, err);
  }
  
  static int crypto_authenc_givencrypt(struct aead_givcrypt_request *req)
  {
  	struct crypto_aead *authenc = aead_givcrypt_reqtfm(req);
  	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  	struct aead_request *areq = &req->areq;
  	struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);
  	u8 *iv = req->giv;
  	int err;
  
  	skcipher_givcrypt_set_tfm(greq, ctx->enc);
  	skcipher_givcrypt_set_callback(greq, aead_request_flags(areq),
  				       crypto_authenc_givencrypt_done, areq);
  	skcipher_givcrypt_set_crypt(greq, areq->src, areq->dst, areq->cryptlen,
  				    areq->iv);
  	skcipher_givcrypt_set_giv(greq, iv, req->seq);
  
  	err = crypto_skcipher_givencrypt(greq);
  	if (err)
  		return err;
  
  	return crypto_authenc_genicv(areq, iv, CRYPTO_TFM_REQ_MAY_SLEEP);

  }

  static int crypto_authenc_verify(struct aead_request *req,

  				 struct scatterlist *cipher,

  				 unsigned int cryptlen)

  {
  	struct crypto_aead *authenc = crypto_aead_reqtfm(req);

  	u8 *ohash;

  	u8 *ihash;

  	unsigned int authsize;

  	ohash = crypto_authenc_hash(req, CRYPTO_TFM_REQ_MAY_SLEEP, cipher,

  				    cryptlen);
  	if (IS_ERR(ohash))
  		return PTR_ERR(ohash);

  	authsize = crypto_aead_authsize(authenc);

  	ihash = ohash + authsize;

  	scatterwalk_map_and_copy(ihash, cipher, cryptlen, authsize, 0);

  	return memcmp(ihash, ohash, authsize) ? -EBADMSG: 0;

  }

  static int crypto_authenc_iverify(struct aead_request *req, u8 *iv,
  				  unsigned int cryptlen)

  {

  	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
  	struct scatterlist *src = req->src;
  	struct scatterlist cipher[2];
  	struct page *srcp;
  	unsigned int ivsize = crypto_aead_ivsize(authenc);
  	u8 *vsrc;
  
  	srcp = sg_page(src);
  	vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + src->offset;
  
  	sg_init_table(cipher, 2);
  	sg_set_buf(cipher, iv, ivsize);
  	authenc_chain(cipher, src, vsrc == iv + ivsize);
  
  	return crypto_authenc_verify(req, cipher, cryptlen + ivsize);

  }
  
  static int crypto_authenc_decrypt(struct aead_request *req)
  {
  	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
  	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
  	struct ablkcipher_request *abreq = aead_request_ctx(req);

  	unsigned int cryptlen = req->cryptlen;
  	unsigned int authsize = crypto_aead_authsize(authenc);

  	u8 *iv = req->iv;

  	int err;

  	if (cryptlen < authsize)
  		return -EINVAL;
  	cryptlen -= authsize;

  	err = crypto_authenc_iverify(req, iv, cryptlen);

  	if (err)
  		return err;
  
  	ablkcipher_request_set_tfm(abreq, ctx->enc);
  	ablkcipher_request_set_callback(abreq, aead_request_flags(req),

  					req->base.complete, req->base.data);
  	ablkcipher_request_set_crypt(abreq, req->src, req->dst, cryptlen, iv);

  
  	return crypto_ablkcipher_decrypt(abreq);
  }
  
  static int crypto_authenc_init_tfm(struct crypto_tfm *tfm)
  {
  	struct crypto_instance *inst = (void *)tfm->__crt_alg;
  	struct authenc_instance_ctx *ictx = crypto_instance_ctx(inst);
  	struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
  	struct crypto_hash *auth;
  	struct crypto_ablkcipher *enc;

  	int err;
  
  	auth = crypto_spawn_hash(&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_hash;
  
  	ctx->auth = auth;
  	ctx->enc = enc;
  	tfm->crt_aead.reqsize = max_t(unsigned int,
  				      (crypto_hash_alignmask(auth) &
  				       ~(crypto_tfm_ctx_alignment() - 1)) +

  				      crypto_hash_digestsize(auth) * 2,

  				      sizeof(struct skcipher_givcrypt_request) +
  				      crypto_ablkcipher_reqsize(enc) +
  				      crypto_ablkcipher_ivsize(enc));

  
  	spin_lock_init(&ctx->auth_lock);
  
  	return 0;
  
  err_free_hash:
  	crypto_free_hash(auth);
  	return err;
  }
  
  static void crypto_authenc_exit_tfm(struct crypto_tfm *tfm)
  {
  	struct crypto_authenc_ctx *ctx = crypto_tfm_ctx(tfm);
  
  	crypto_free_hash(ctx->auth);
  	crypto_free_ablkcipher(ctx->enc);
  }
  
  static struct crypto_instance *crypto_authenc_alloc(struct rtattr **tb)
  {

  	struct crypto_attr_type *algt;

  	struct crypto_instance *inst;
  	struct crypto_alg *auth;
  	struct crypto_alg *enc;
  	struct authenc_instance_ctx *ctx;

  	const char *enc_name;

  	int err;

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

  		return ERR_PTR(err);

  	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
  		return ERR_PTR(-EINVAL);

  	auth = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
  			       CRYPTO_ALG_TYPE_HASH_MASK);
  	if (IS_ERR(auth))
  		return ERR_PTR(PTR_ERR(auth));

  	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 = crypto_instance_ctx(inst);

  
  	err = crypto_init_spawn(&ctx->auth, auth, inst, CRYPTO_ALG_TYPE_MASK);
  	if (err)
  		goto err_free_inst;

  	crypto_set_skcipher_spawn(&ctx->enc, 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_skcipher_spawn_alg(&ctx->enc);
  
  	err = -ENAMETOOLONG;
  	if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
  		     "authenc(%s,%s)", auth->cra_name, enc->cra_name) >=
  	    CRYPTO_MAX_ALG_NAME)
  		goto err_drop_enc;
  
  	if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
  		     "authenc(%s,%s)", auth->cra_driver_name,
  		     enc->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
  		goto err_drop_enc;
  
  	inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD;
  	inst->alg.cra_flags |= enc->cra_flags & CRYPTO_ALG_ASYNC;

  	inst->alg.cra_priority = enc->cra_priority * 10 + auth->cra_priority;
  	inst->alg.cra_blocksize = enc->cra_blocksize;

  	inst->alg.cra_alignmask = auth->cra_alignmask | enc->cra_alignmask;

  	inst->alg.cra_type = &crypto_aead_type;

  	inst->alg.cra_aead.ivsize = enc->cra_ablkcipher.ivsize;

  	inst->alg.cra_aead.maxauthsize = auth->cra_type == &crypto_hash_type ?
  					 auth->cra_hash.digestsize :
  					 auth->cra_digest.dia_digestsize;

  
  	inst->alg.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
  
  	inst->alg.cra_init = crypto_authenc_init_tfm;
  	inst->alg.cra_exit = crypto_authenc_exit_tfm;
  
  	inst->alg.cra_aead.setkey = crypto_authenc_setkey;
  	inst->alg.cra_aead.encrypt = crypto_authenc_encrypt;
  	inst->alg.cra_aead.decrypt = crypto_authenc_decrypt;

  	inst->alg.cra_aead.givencrypt = crypto_authenc_givencrypt;

  
  out:

  	crypto_mod_put(auth);
  	return inst;

  err_drop_enc:
  	crypto_drop_skcipher(&ctx->enc);

  err_drop_auth:
  	crypto_drop_spawn(&ctx->auth);
  err_free_inst:
  	kfree(inst);

  out_put_auth:

  	inst = ERR_PTR(err);
  	goto out;
  }
  
  static void crypto_authenc_free(struct crypto_instance *inst)
  {
  	struct authenc_instance_ctx *ctx = crypto_instance_ctx(inst);

  	crypto_drop_skcipher(&ctx->enc);

  	crypto_drop_spawn(&ctx->auth);
  	kfree(inst);
  }
  
  static struct crypto_template crypto_authenc_tmpl = {
  	.name = "authenc",
  	.alloc = crypto_authenc_alloc,
  	.free = crypto_authenc_free,
  	.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");