/*
   * 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]))

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

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

   * For alignment considerations the upper 32 bits of the sequence number are
   * placed at the front, if present. Followed by the IV, 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, int seqihlen)

  {
  	unsigned int len;

  	len = seqihlen;
  
  	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 __be32 *esp_tmp_seqhi(void *tmp)
  {
  	return PTR_ALIGN((__be32 *)tmp, __alignof__(__be32));
  }
  
  static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp, int seqhilen)

  {
  	return crypto_aead_ivsize(aead) ?

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

  }
  
  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 plen;
  	int tfclen;

  	int nfrags;

  	int assoclen;
  	int sglists;
  	int seqhilen;

  	u8 *iv;

  	u8 *tail;

  	__be32 *seqhi;

  	struct esp_data *esp = x->data;

  	/* skb is pure payload to encrypt */

  	err = -ENOMEM;

  	aead = esp->aead;
  	alen = crypto_aead_authsize(aead);

  	tfclen = 0;
  	if (x->tfcpad) {
  		struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb);
  		u32 padto;
  
  		padto = min(x->tfcpad, esp6_get_mtu(x, dst->child_mtu_cached));
  		if (skb->len < padto)
  			tfclen = padto - skb->len;
  	}

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

  	clen = ALIGN(skb->len + 2 + tfclen, blksize);

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

  	plen = clen - skb->len - tfclen;

  	err = skb_cow_data(skb, tfclen + plen + alen, &trailer);
  	if (err < 0)

  		goto error;

  	nfrags = err;

  	assoclen = sizeof(*esph);
  	sglists = 1;
  	seqhilen = 0;
  
  	if (x->props.flags & XFRM_STATE_ESN) {
  		sglists += 2;
  		seqhilen += sizeof(__be32);
  		assoclen += seqhilen;
  	}
  
  	tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen);

  	if (!tmp)
  		goto error;

  	seqhi = esp_tmp_seqhi(tmp);
  	iv = esp_tmp_iv(aead, tmp, seqhilen);

  	req = esp_tmp_givreq(aead, iv);
  	asg = esp_givreq_sg(aead, req);

  	sg = asg + sglists;

  
  	/* Fill padding... */

  	tail = skb_tail_pointer(trailer);

  	if (tfclen) {
  		memset(tail, 0, tfclen);
  		tail += tfclen;
  	}

  	do {
  		int i;

  		for (i = 0; i < plen - 2; i++)

  			tail[i] = i + 1;

  	} while (0);

  	tail[plen - 2] = plen - 2;
  	tail[plen - 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.low);

  	sg_init_table(sg, nfrags);
  	skb_to_sgvec(skb, sg,
  		     esph->enc_data + crypto_aead_ivsize(aead) - skb->data,
  		     clen + alen);

  
  	if ((x->props.flags & XFRM_STATE_ESN)) {
  		sg_init_table(asg, 3);
  		sg_set_buf(asg, &esph->spi, sizeof(__be32));
  		*seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
  		sg_set_buf(asg + 1, seqhi, seqhilen);
  		sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32));
  	} else
  		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, assoclen);

  	aead_givcrypt_set_giv(req, esph->enc_data,

  			      XFRM_SKB_CB(skb)->seq.output.low);

  	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
  ", 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 assoclen;
  	int sglists;
  	int seqhilen;

  	int ret = 0;

  	void *tmp;

  	__be32 *seqhi;

  	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;

  
  	assoclen = sizeof(*esph);
  	sglists = 1;
  	seqhilen = 0;
  
  	if (x->props.flags & XFRM_STATE_ESN) {
  		sglists += 2;
  		seqhilen += sizeof(__be32);
  		assoclen += seqhilen;
  	}
  
  	tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen);

  	if (!tmp)
  		goto out;

  	ESP_SKB_CB(skb)->tmp = tmp;

  	seqhi = esp_tmp_seqhi(tmp);
  	iv = esp_tmp_iv(aead, tmp, seqhilen);

  	req = esp_tmp_req(aead, iv);
  	asg = esp_req_sg(aead, req);

  	sg = asg + sglists;

  	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);

  
  	if ((x->props.flags & XFRM_STATE_ESN)) {
  		sg_init_table(asg, 3);
  		sg_set_buf(asg, &esph->spi, sizeof(__be32));
  		*seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
  		sg_set_buf(asg + 1, seqhi, seqhilen);
  		sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32));
  	} else
  		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, assoclen);

  	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,

  		     u8 type, u8 code, int offset, __be32 info)

  {

  	struct net *net = dev_net(skb->dev);

  	const struct ipv6hdr *iph = (const 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;

  	x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
  			      esph->spi, IPPROTO_ESP, AF_INET6);

  	if (!x)
  		return;

  	printk(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%pI6
  ",

  			ntohl(esph->spi), &iph->daddr);

  	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 ((x->props.flags & XFRM_STATE_ESN)) {
  		if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
  			     "authencesn(%s,%s)",
  			     x->aalg ? x->aalg->alg_name : "digest_null",
  			     x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
  			goto error;
  	} else {
  		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
  ",
  				 x->aalg->alg_name,

  				 crypto_aead_authsize(aead),

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

  			goto free_key;

  		}

  		err = crypto_aead_setauthsize(

  			aead, x->aalg->alg_trunc_len / 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;

  	case XFRM_MODE_TRANSPORT:
  		break;
  	case XFRM_MODE_TUNNEL:

  		x->props.header_len += sizeof(struct ipv6hdr);

  		break;

  	default:
  		goto error;
  	}

  
  	align = ALIGN(crypto_aead_blocksize(aead), 4);
  	if (esp->padlen)
  		align = max_t(u32, align, esp->padlen);
  	x->props.trailer_len = align + 1 + crypto_aead_authsize(esp->aead);

  
  error:

  	return err;

  }

  static const struct xfrm_type esp6_type =

  {
  	.description	= "ESP6",
  	.owner	     	= THIS_MODULE,
  	.proto	     	= IPPROTO_ESP,

  	.flags		= XFRM_TYPE_REPLAY_PROT,

  	.init_state	= esp6_init_state,
  	.destructor	= esp6_destroy,

  	.get_mtu	= esp6_get_mtu,

  	.input		= esp6_input,

  	.output		= esp6_output,
  	.hdr_offset	= xfrm6_find_1stfragopt,

  };

  static const struct inet6_protocol esp6_protocol = {

  	.handler 	=	xfrm6_rcv,
  	.err_handler	=	esp6_err,
  	.flags		=	INET6_PROTO_NOPOLICY,
  };
  
  static int __init esp6_init(void)
  {
  	if (xfrm_register_type(&esp6_type, AF_INET6) < 0) {
  		printk(KERN_INFO "ipv6 esp init: can't add xfrm type
  ");
  		return -EAGAIN;
  	}
  	if (inet6_add_protocol(&esp6_protocol, IPPROTO_ESP) < 0) {
  		printk(KERN_INFO "ipv6 esp init: can't add protocol
  ");
  		xfrm_unregister_type(&esp6_type, AF_INET6);
  		return -EAGAIN;
  	}
  
  	return 0;
  }
  
  static void __exit esp6_fini(void)
  {
  	if (inet6_del_protocol(&esp6_protocol, IPPROTO_ESP) < 0)
  		printk(KERN_INFO "ipv6 esp close: can't remove protocol
  ");
  	if (xfrm_unregister_type(&esp6_type, AF_INET6) < 0)
  		printk(KERN_INFO "ipv6 esp close: can't remove xfrm type
  ");
  }
  
  module_init(esp6_init);
  module_exit(esp6_fini);
  
  MODULE_LICENSE("GPL");

  MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ESP);