/*
 * authencesn.c - AEAD wrapper for IPsec with extended sequence numbers,
 *                 derived from authenc.c
 *
 * Copyright (C) 2010 secunet Security Networks AG
 * Copyright (C) 2010 Steffen Klassert <steffen.klassert@secunet.com>
 *
 * 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/hash.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_esn_instance_ctx {
	struct crypto_ahash_spawn auth;
	struct crypto_skcipher_spawn enc;
};

struct crypto_authenc_esn_ctx {
	unsigned int reqoff;
	struct crypto_ahash *auth;
	struct crypto_ablkcipher *enc;
};

struct authenc_esn_request_ctx {
	unsigned int cryptlen;
	unsigned int headlen;
	unsigned int trailen;
	struct scatterlist *sg;
	struct scatterlist hsg[2];
	struct scatterlist tsg[1];
	struct scatterlist cipher[2];
	crypto_completion_t complete;
	crypto_completion_t update_complete;
	crypto_completion_t update_complete2;
	char tail[];
};

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

static int crypto_authenc_esn_setkey(struct crypto_aead *authenc_esn, const u8 *key,
				     unsigned int keylen)
{
	unsigned int authkeylen;
	unsigned int enckeylen;
	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
	struct crypto_ahash *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_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
	crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc_esn) &
				     CRYPTO_TFM_REQ_MASK);
	err = crypto_ahash_setkey(auth, key, authkeylen);
	crypto_aead_set_flags(authenc_esn, crypto_ahash_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_esn) &
					 CRYPTO_TFM_REQ_MASK);
	err = crypto_ablkcipher_setkey(enc, key + authkeylen, enckeylen);
	crypto_aead_set_flags(authenc_esn, crypto_ablkcipher_get_flags(enc) &
					   CRYPTO_TFM_RES_MASK);

out:
	return err;

badkey:
	crypto_aead_set_flags(authenc_esn, CRYPTO_TFM_RES_BAD_KEY_LEN);
	goto out;
}

static void authenc_esn_geniv_ahash_update_done(struct crypto_async_request *areq,
						int err)
{
	struct aead_request *req = areq->data;
	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);

	if (err)
		goto out;

	ahash_request_set_crypt(ahreq, areq_ctx->sg, ahreq->result,
				areq_ctx->cryptlen);
	ahash_request_set_callback(ahreq, aead_request_flags(req) &
					  CRYPTO_TFM_REQ_MAY_SLEEP,
				   areq_ctx->update_complete2, req);

	err = crypto_ahash_update(ahreq);
	if (err)
		goto out;

	ahash_request_set_crypt(ahreq, areq_ctx->tsg, ahreq->result,
				areq_ctx->trailen);
	ahash_request_set_callback(ahreq, aead_request_flags(req) &
					  CRYPTO_TFM_REQ_MAY_SLEEP,
				   areq_ctx->complete, req);

	err = crypto_ahash_finup(ahreq);
	if (err)
		goto out;

	scatterwalk_map_and_copy(ahreq->result, areq_ctx->sg,
				 areq_ctx->cryptlen,
				 crypto_aead_authsize(authenc_esn), 1);

out:
	authenc_esn_request_complete(req, err);
}

static void authenc_esn_geniv_ahash_update_done2(struct crypto_async_request *areq,
						 int err)
{
	struct aead_request *req = areq->data;
	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);

	if (err)
		goto out;

	ahash_request_set_crypt(ahreq, areq_ctx->tsg, ahreq->result,
				areq_ctx->trailen);
	ahash_request_set_callback(ahreq, aead_request_flags(req) &
					  CRYPTO_TFM_REQ_MAY_SLEEP,
				   areq_ctx->complete, req);

	err = crypto_ahash_finup(ahreq);
	if (err)
		goto out;

	scatterwalk_map_and_copy(ahreq->result, areq_ctx->sg,
				 areq_ctx->cryptlen,
				 crypto_aead_authsize(authenc_esn), 1);

out:
	authenc_esn_request_complete(req, err);
}


static void authenc_esn_geniv_ahash_done(struct crypto_async_request *areq,
					 int err)
{
	struct aead_request *req = areq->data;
	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);

	if (err)
		goto out;

	scatterwalk_map_and_copy(ahreq->result, areq_ctx->sg,
				 areq_ctx->cryptlen,
				 crypto_aead_authsize(authenc_esn), 1);

out:
	aead_request_complete(req, err);
}


static void authenc_esn_verify_ahash_update_done(struct crypto_async_request *areq,
						 int err)
{
	u8 *ihash;
	unsigned int authsize;
	struct ablkcipher_request *abreq;
	struct aead_request *req = areq->data;
	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
	unsigned int cryptlen = req->cryptlen;

	if (err)
		goto out;

	ahash_request_set_crypt(ahreq, areq_ctx->sg, ahreq->result,
				areq_ctx->cryptlen);

	ahash_request_set_callback(ahreq,
				   aead_request_flags(req) &
				   CRYPTO_TFM_REQ_MAY_SLEEP,
				   areq_ctx->update_complete2, req);

	err = crypto_ahash_update(ahreq);
	if (err)
		goto out;

	ahash_request_set_crypt(ahreq, areq_ctx->tsg, ahreq->result,
				areq_ctx->trailen);
	ahash_request_set_callback(ahreq, aead_request_flags(req) &
					  CRYPTO_TFM_REQ_MAY_SLEEP,
				   areq_ctx->complete, req);

	err = crypto_ahash_finup(ahreq);
	if (err)
		goto out;

	authsize = crypto_aead_authsize(authenc_esn);
	cryptlen -= authsize;
	ihash = ahreq->result + authsize;
	scatterwalk_map_and_copy(ihash, areq_ctx->sg, areq_ctx->cryptlen,
				 authsize, 0);

	err = memcmp(ihash, ahreq->result, authsize) ? -EBADMSG : 0;
	if (err)
		goto out;

	abreq = aead_request_ctx(req);
	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, req->iv);

	err = crypto_ablkcipher_decrypt(abreq);

out:
	authenc_esn_request_complete(req, err);
}

static void authenc_esn_verify_ahash_update_done2(struct crypto_async_request *areq,
						  int err)
{
	u8 *ihash;
	unsigned int authsize;
	struct ablkcipher_request *abreq;
	struct aead_request *req = areq->data;
	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
	unsigned int cryptlen = req->cryptlen;

	if (err)
		goto out;

	ahash_request_set_crypt(ahreq, areq_ctx->tsg, ahreq->result,
				areq_ctx->trailen);
	ahash_request_set_callback(ahreq, aead_request_flags(req) &
					  CRYPTO_TFM_REQ_MAY_SLEEP,
				   areq_ctx->complete, req);

	err = crypto_ahash_finup(ahreq);
	if (err)
		goto out;

	authsize = crypto_aead_authsize(authenc_esn);
	cryptlen -= authsize;
	ihash = ahreq->result + authsize;
	scatterwalk_map_and_copy(ihash, areq_ctx->sg, areq_ctx->cryptlen,
				 authsize, 0);

	err = memcmp(ihash, ahreq->result, authsize) ? -EBADMSG : 0;
	if (err)
		goto out;

	abreq = aead_request_ctx(req);
	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, req->iv);

	err = crypto_ablkcipher_decrypt(abreq);

out:
	authenc_esn_request_complete(req, err);
}


static void authenc_esn_verify_ahash_done(struct crypto_async_request *areq,
					  int err)
{
	u8 *ihash;
	unsigned int authsize;
	struct ablkcipher_request *abreq;
	struct aead_request *req = areq->data;
	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
	unsigned int cryptlen = req->cryptlen;

	if (err)
		goto out;

	authsize = crypto_aead_authsize(authenc_esn);
	cryptlen -= authsize;
	ihash = ahreq->result + authsize;
	scatterwalk_map_and_copy(ihash, areq_ctx->sg, areq_ctx->cryptlen,
				 authsize, 0);

	err = memcmp(ihash, ahreq->result, authsize) ? -EBADMSG : 0;
	if (err)
		goto out;

	abreq = aead_request_ctx(req);
	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, req->iv);

	err = crypto_ablkcipher_decrypt(abreq);

out:
	authenc_esn_request_complete(req, err);
}

static u8 *crypto_authenc_esn_ahash(struct aead_request *req,
				    unsigned int flags)
{
	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
	struct crypto_ahash *auth = ctx->auth;
	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->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);

	err = crypto_ahash_init(ahreq);
	if (err)
		return ERR_PTR(err);

	ahash_request_set_crypt(ahreq, areq_ctx->hsg, hash, areq_ctx->headlen);
	ahash_request_set_callback(ahreq, aead_request_flags(req) & flags,
				   areq_ctx->update_complete, req);

	err = crypto_ahash_update(ahreq);
	if (err)
		return ERR_PTR(err);

	ahash_request_set_crypt(ahreq, areq_ctx->sg, hash, areq_ctx->cryptlen);
	ahash_request_set_callback(ahreq, aead_request_flags(req) & flags,
				   areq_ctx->update_complete2, req);

	err = crypto_ahash_update(ahreq);
	if (err)
		return ERR_PTR(err);

	ahash_request_set_crypt(ahreq, areq_ctx->tsg, hash,
				areq_ctx->trailen);
	ahash_request_set_callback(ahreq, aead_request_flags(req) & flags,
				   areq_ctx->complete, req);

	err = crypto_ahash_finup(ahreq);
	if (err)
		return ERR_PTR(err);

	return hash;
}

static int crypto_authenc_esn_genicv(struct aead_request *req, u8 *iv,
				     unsigned int flags)
{
	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
	struct scatterlist *dst = req->dst;
	struct scatterlist *assoc = req->assoc;
	struct scatterlist *cipher = areq_ctx->cipher;
	struct scatterlist *hsg = areq_ctx->hsg;
	struct scatterlist *tsg = areq_ctx->tsg;
	struct scatterlist *assoc1;
	struct scatterlist *assoc2;
	unsigned int ivsize = crypto_aead_ivsize(authenc_esn);
	unsigned int cryptlen = req->cryptlen;
	struct page *dstp;
	u8 *vdst;
	u8 *hash;

	dstp = sg_page(dst);
	vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + dst->offset;

	if (ivsize) {
		sg_init_table(cipher, 2);
		sg_set_buf(cipher, iv, ivsize);
		scatterwalk_crypto_chain(cipher, dst, vdst == iv + ivsize, 2);
		dst = cipher;
		cryptlen += ivsize;
	}

	if (sg_is_last(assoc))
		return -EINVAL;

	assoc1 = assoc + 1;
	if (sg_is_last(assoc1))
		return -EINVAL;

	assoc2 = assoc + 2;
	if (!sg_is_last(assoc2))
		return -EINVAL;

	sg_init_table(hsg, 2);
	sg_set_page(hsg, sg_page(assoc), assoc->length, assoc->offset);
	sg_set_page(hsg + 1, sg_page(assoc2), assoc2->length, assoc2->offset);

	sg_init_table(tsg, 1);
	sg_set_page(tsg, sg_page(assoc1), assoc1->length, assoc1->offset);

	areq_ctx->cryptlen = cryptlen;
	areq_ctx->headlen = assoc->length + assoc2->length;
	areq_ctx->trailen = assoc1->length;
	areq_ctx->sg = dst;

	areq_ctx->complete = authenc_esn_geniv_ahash_done;
	areq_ctx->update_complete = authenc_esn_geniv_ahash_update_done;
	areq_ctx->update_complete2 = authenc_esn_geniv_ahash_update_done2;

	hash = crypto_authenc_esn_ahash(req, flags);
	if (IS_ERR(hash))
		return PTR_ERR(hash);

	scatterwalk_map_and_copy(hash, dst, cryptlen,
				 crypto_aead_authsize(authenc_esn), 1);
	return 0;
}


static void crypto_authenc_esn_encrypt_done(struct crypto_async_request *req,
					    int err)
{
	struct aead_request *areq = req->data;

	if (!err) {
		struct crypto_aead *authenc_esn = crypto_aead_reqtfm(areq);
		struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
		struct ablkcipher_request *abreq = aead_request_ctx(areq);
		u8 *iv = (u8 *)(abreq + 1) +
			 crypto_ablkcipher_reqsize(ctx->enc);

		err = crypto_authenc_esn_genicv(areq, iv, 0);
	}

	authenc_esn_request_complete(areq, err);
}

static int crypto_authenc_esn_encrypt(struct aead_request *req)
{
	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
	struct crypto_ablkcipher *enc = ctx->enc;
	struct scatterlist *dst = req->dst;
	unsigned int cryptlen = req->cryptlen;
	struct ablkcipher_request *abreq = (void *)(areq_ctx->tail
						    + ctx->reqoff);
	u8 *iv = (u8 *)abreq - crypto_ablkcipher_ivsize(enc);
	int err;

	ablkcipher_request_set_tfm(abreq, enc);
	ablkcipher_request_set_callback(abreq, aead_request_flags(req),
					crypto_authenc_esn_encrypt_done, req);
	ablkcipher_request_set_crypt(abreq, req->src, dst, cryptlen, req->iv);

	memcpy(iv, req->iv, crypto_aead_ivsize(authenc_esn));

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

	return crypto_authenc_esn_genicv(req, iv, CRYPTO_TFM_REQ_MAY_SLEEP);
}

static void crypto_authenc_esn_givencrypt_done(struct crypto_async_request *req,
					       int err)
{
	struct aead_request *areq = req->data;

	if (!err) {
		struct skcipher_givcrypt_request *greq = aead_request_ctx(areq);

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

	authenc_esn_request_complete(areq, err);
}

static int crypto_authenc_esn_givencrypt(struct aead_givcrypt_request *req)
{
	struct crypto_aead *authenc_esn = aead_givcrypt_reqtfm(req);