/*

 * Copyright (C)2002 USAGI/WIDE Project

 *

 * 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.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 * Authors

 *

 *	Mitsuru KANDA @USAGI       : IPv6 Support

 * 	Kazunori MIYAZAWA @USAGI   :

 * 	Kunihiro Ishiguro <kunihiro@ipinfusion.com>

 *

 * 	This file is derived from net/ipv4/esp.c

 */

#include <crypto/aead.h>

#include <crypto/authenc.h>

#include <linux/err.h>

#include <linux/module.h>

#include <net/ip.h>

#include <net/xfrm.h>

#include <net/esp.h>

#include <linux/scatterlist.h>

#include <linux/kernel.h>

#include <linux/pfkeyv2.h>

#include <linux/random.h>

#include <linux/slab.h>

#include <linux/spinlock.h>

#include <net/icmp.h>

#include <net/ipv6.h>

#include <net/protocol.h>

#include <linux/icmpv6.h>

struct esp_skb_cb {

	struct xfrm_skb_cb xfrm;

	void *tmp;

};

#define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0]))

/*

 * Allocate an AEAD request structure with extra space for SG and IV.

 *

 * For alignment considerations the IV is placed at the front, followed

 * by the request and finally the SG list.

 *

 * TODO: Use spare space in skb for this where possible.

 */

static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags)

{

	unsigned int len;

	len = crypto_aead_ivsize(aead);

	if (len) {

		len += crypto_aead_alignmask(aead) &

		       ~(crypto_tfm_ctx_alignment() - 1);

		len = ALIGN(len, crypto_tfm_ctx_alignment());

	}

	len += sizeof(struct aead_givcrypt_request) + crypto_aead_reqsize(aead);

	len = ALIGN(len, __alignof__(struct scatterlist));

	len += sizeof(struct scatterlist) * nfrags;

	return kmalloc(len, GFP_ATOMIC);

}

static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp)

{

	return crypto_aead_ivsize(aead) ?

	       PTR_ALIGN((u8 *)tmp, crypto_aead_alignmask(aead) + 1) : tmp;

}

static inline struct aead_givcrypt_request *esp_tmp_givreq(

	struct crypto_aead *aead, u8 *iv)

{

	struct aead_givcrypt_request *req;

	req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),

				crypto_tfm_ctx_alignment());

	aead_givcrypt_set_tfm(req, aead);

	return req;

}

static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv)

{

	struct aead_request *req;

	req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),

				crypto_tfm_ctx_alignment());

	aead_request_set_tfm(req, aead);

	return req;

}

static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,

					     struct aead_request *req)

{

	return (void *)ALIGN((unsigned long)(req + 1) +

			     crypto_aead_reqsize(aead),

			     __alignof__(struct scatterlist));

}

static inline struct scatterlist *esp_givreq_sg(

	struct crypto_aead *aead, struct aead_givcrypt_request *req)

{

	return (void *)ALIGN((unsigned long)(req + 1) +

			     crypto_aead_reqsize(aead),

			     __alignof__(struct scatterlist));

}

static void esp_output_done(struct crypto_async_request *base, int err)

{

	struct sk_buff *skb = base->data;

	kfree(ESP_SKB_CB(skb)->tmp);

	xfrm_output_resume(skb, err);

}

static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)

{

	int err;

	struct ip_esp_hdr *esph;

	struct crypto_aead *aead;

	struct aead_givcrypt_request *req;

	struct scatterlist *sg;

	struct scatterlist *asg;

	struct sk_buff *trailer;

	void *tmp;

	int blksize;

	int clen;

	int alen;

	int nfrags;

	u8 *iv;

	u8 *tail;

	struct esp_data *esp = x->data;

	/* skb is pure payload to encrypt */

	err = -ENOMEM;

	/* Round to block size */

	clen = skb->len;

	aead = esp->aead;

	alen = crypto_aead_authsize(aead);

	blksize = ALIGN(crypto_aead_blocksize(aead), 4);

	clen = ALIGN(clen + 2, blksize);

	if (esp->padlen)

		clen = ALIGN(clen, esp->padlen);

	if ((err = skb_cow_data(skb, clen - skb->len + alen, &trailer)) < 0)

		goto error;

	nfrags = err;

	tmp = esp_alloc_tmp(aead, nfrags + 1);

	if (!tmp)

		goto error;

	iv = esp_tmp_iv(aead, tmp);

	req = esp_tmp_givreq(aead, iv);

	asg = esp_givreq_sg(aead, req);

	sg = asg + 1;

	/* Fill padding... */

	tail = skb_tail_pointer(trailer);

	do {

		int i;

		for (i=0; i<clen-skb->len - 2; i++)

			tail[i] = i + 1;

	} while (0);

	tail[clen-skb->len - 2] = (clen - skb->len) - 2;

	tail[clen - skb->len - 1] = *skb_mac_header(skb);

	pskb_put(skb, trailer, clen - skb->len + alen);

	skb_push(skb, -skb_network_offset(skb));

	esph = ip_esp_hdr(skb);

	*skb_mac_header(skb) = IPPROTO_ESP;

	esph->spi = x->id.spi;

	esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output);

	sg_init_table(sg, nfrags);

	skb_to_sgvec(skb, sg,

		     esph->enc_data + crypto_aead_ivsize(aead) - skb->data,

		     clen + alen);

	sg_init_one(asg, esph, sizeof(*esph));

	aead_givcrypt_set_callback(req, 0, esp_output_done, skb);

	aead_givcrypt_set_crypt(req, sg, sg, clen, iv);

	aead_givcrypt_set_assoc(req, asg, sizeof(*esph));

	aead_givcrypt_set_giv(req, esph->enc_data,

			      XFRM_SKB_CB(skb)->seq.output);

	ESP_SKB_CB(skb)->tmp = tmp;

	err = crypto_aead_givencrypt(req);

	if (err == -EINPROGRESS)

		goto error;

	if (err == -EBUSY)

		err = NET_XMIT_DROP;

	kfree(tmp);

error:

	return err;

}

static int esp_input_done2(struct sk_buff *skb, int err)

{

	struct xfrm_state *x = xfrm_input_state(skb);

	struct esp_data *esp = x->data;

	struct crypto_aead *aead = esp->aead;

	int alen = crypto_aead_authsize(aead);

	int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);

	int elen = skb->len - hlen;

	int hdr_len = skb_network_header_len(skb);

	int padlen;

	u8 nexthdr[2];

	kfree(ESP_SKB_CB(skb)->tmp);

	if (unlikely(err))

		goto out;

	if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2))

		BUG();

	err = -EINVAL;

	padlen = nexthdr[0];

	if (padlen + 2 + alen >= elen) {

		LIMIT_NETDEBUG(KERN_WARNING "ipsec esp packet is garbage "

			       "padlen=%d, elen=%d\n", padlen + 2, elen - alen);

		goto out;

	}

	/* ... check padding bits here. Silly. :-) */

	pskb_trim(skb, skb->len - alen - padlen - 2);

	__skb_pull(skb, hlen);

	skb_set_transport_header(skb, -hdr_len);

	err = nexthdr[1];

	/* RFC4303: Drop dummy packets without any error */

	if (err == IPPROTO_NONE)

		err = -EINVAL;

out:

	return err;

}

static void esp_input_done(struct crypto_async_request *base, int err)

{

	struct sk_buff *skb = base->data;

	xfrm_input_resume(skb, esp_input_done2(skb, err));

}

static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)

{

	struct ip_esp_hdr *esph;

	struct esp_data *esp = x->data;

	struct crypto_aead *aead = esp->aead;

	struct aead_request *req;

	struct sk_buff *trailer;

	int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead);

	int nfrags;

	int ret = 0;

	void *tmp;

	u8 *iv;

	struct scatterlist *sg;

	struct scatterlist *asg;

	if (!pskb_may_pull(skb, sizeof(*esph) + crypto_aead_ivsize(aead))) {

		ret = -EINVAL;

		goto out;

	}

	if (elen <= 0) {

		ret = -EINVAL;

		goto out;

	}

	if ((nfrags = skb_cow_data(skb, 0, &trailer)) < 0) {

		ret = -EINVAL;

		goto out;

	}

	ret = -ENOMEM;

	tmp = esp_alloc_tmp(aead, nfrags + 1);

	if (!tmp)

		goto out;

	ESP_SKB_CB(skb)->tmp = tmp;

	iv = esp_tmp_iv(aead, tmp);

	req = esp_tmp_req(aead, iv);

	asg = esp_req_sg(aead, req);

	sg = asg + 1;

	skb->ip_summed = CHECKSUM_NONE;

	esph = (struct ip_esp_hdr *)skb->data;

	/* Get ivec. This can be wrong, check against another impls. */

	iv = esph->enc_data;

	sg_init_table(sg, nfrags);

	skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen);

	sg_init_one(asg, esph, sizeof(*esph));

	aead_request_set_callback(req, 0, esp_input_done, skb);

	aead_request_set_crypt(req, sg, sg, elen, iv);

	aead_request_set_assoc(req, asg, sizeof(*esph));

	ret = crypto_aead_decrypt(req);

	if (ret == -EINPROGRESS)

		goto out;

	ret = esp_input_done2(skb, ret);

out:

	return ret;

}

static u32 esp6_get_mtu(struct xfrm_state *x, int mtu)

{

	struct esp_data *esp = x->data;

	u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4);

	u32 align = max_t(u32, blksize, esp->padlen);

	u32 rem;

	mtu -= x->props.header_len + crypto_aead_authsize(esp->aead);

	rem = mtu & (align - 1);

	mtu &= ~(align - 1);

	if (x->props.mode != XFRM_MODE_TUNNEL) {

		u32 padsize = ((blksize - 1) & 7) + 1;

		mtu -= blksize - padsize;

		mtu += min_t(u32, blksize - padsize, rem);

	}

	return mtu - 2;

}

static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,

		     int type, int code, int offset, __be32 info)

{

	struct ipv6hdr *iph = (struct ipv6hdr*)skb->data;

	struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data + offset);

	struct xfrm_state *x;

	if (type != ICMPV6_DEST_UNREACH &&

	    type != ICMPV6_PKT_TOOBIG)

		return;

	if (!x)

		return;

	xfrm_state_put(x);

}

static void esp6_destroy(struct xfrm_state *x)

{

	struct esp_data *esp = x->data;

	if (!esp)

		return;

	crypto_free_aead(esp->aead);

	kfree(esp);

}

static int esp_init_aead(struct xfrm_state *x)

{

	struct esp_data *esp = x->data;

	struct crypto_aead *aead;

	int err;

	aead = crypto_alloc_aead(x->aead->alg_name, 0, 0);

	err = PTR_ERR(aead);

	if (IS_ERR(aead))

		goto error;

	esp->aead = aead;

	err = crypto_aead_setkey(aead, x->aead->alg_key,

				 (x->aead->alg_key_len + 7) / 8);

	if (err)

		goto error;

	err = crypto_aead_setauthsize(aead, x->aead->alg_icv_len / 8);

	if (err)

		goto error;

error:

	return err;

}

static int esp_init_authenc(struct xfrm_state *x)

{

	struct esp_data *esp = x->data;

	struct crypto_aead *aead;

	struct crypto_authenc_key_param *param;

	struct rtattr *rta;

	char *key;

	char *p;

	char authenc_name[CRYPTO_MAX_ALG_NAME];

	unsigned int keylen;

	int err;

	err = -EINVAL;

	if (x->ealg == NULL)

		goto error;

	err = -ENAMETOOLONG;

	if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, "authenc(%s,%s)",

		     x->aalg ? x->aalg->alg_name : "digest_null",

		     x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)

		goto error;

	aead = crypto_alloc_aead(authenc_name, 0, 0);

	err = PTR_ERR(aead);

	if (IS_ERR(aead))

		goto error;

	esp->aead = aead;

	keylen = (x->aalg ? (x->aalg->alg_key_len + 7) / 8 : 0) +

		 (x->ealg->alg_key_len + 7) / 8 + RTA_SPACE(sizeof(*param));

	err = -ENOMEM;

	key = kmalloc(keylen, GFP_KERNEL);

	if (!key)

		goto error;

	p = key;

	rta = (void *)p;

	rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM;

	rta->rta_len = RTA_LENGTH(sizeof(*param));

	param = RTA_DATA(rta);

	p += RTA_SPACE(sizeof(*param));

	if (x->aalg) {

		struct xfrm_algo_desc *aalg_desc;

		memcpy(p, x->aalg->alg_key, (x->aalg->alg_key_len + 7) / 8);

		p += (x->aalg->alg_key_len + 7) / 8;

		aalg_desc = xfrm_aalg_get_byname(x->aalg->alg_name, 0);

		BUG_ON(!aalg_desc);

		err = -EINVAL;

		if (aalg_desc->uinfo.auth.icv_fullbits/8 !=

		    crypto_aead_authsize(aead)) {

			NETDEBUG(KERN_INFO "ESP: %s digestsize %u != %hu\n",

				 x->aalg->alg_name,

				 crypto_aead_authsize(aead),

				 aalg_desc->uinfo.auth.icv_fullbits/8);

			goto free_key;

		}

		err = crypto_aead_setauthsize(

			aead, aalg_desc->uinfo.auth.icv_truncbits / 8);

		if (err)

			goto free_key;

	}

	param->enckeylen = cpu_to_be32((x->ealg->alg_key_len + 7) / 8);

	memcpy(p, x->ealg->alg_key, (x->ealg->alg_key_len + 7) / 8);

	err = crypto_aead_setkey(aead, key, keylen);

free_key:

	kfree(key);

error:

	return err;

}

static int esp6_init_state(struct xfrm_state *x)

{

	struct esp_data *esp;

	struct crypto_aead *aead;

	u32 align;

	int err;

	if (x->encap)

		return -EINVAL;

	esp = kzalloc(sizeof(*esp), GFP_KERNEL);

	if (esp == NULL)

		return -ENOMEM;

	x->data = esp;

	if (x->aead)

		err = esp_init_aead(x);

	else

		err = esp_init_authenc(x);

	if (err)

		goto error;

	aead = esp->aead;

	esp->padlen = 0;

	x->props.header_len = sizeof(struct ip_esp_hdr) +

			      crypto_aead_ivsize(aead);

	switch (x->props.mode) {

	case XFRM_MODE_BEET:

		if (x->sel.family != AF_INET6)

			x->props.header_len += IPV4_BEET_PHMAXLEN +

				               (sizeof(struct ipv6hdr) - sizeof(struct iphdr));

		break;