ipcomp6.c 5.5 KB
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/*
 * IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173
 *
 * Copyright (C)2003 USAGI/WIDE Project
 *
 * Author	Mitsuru KANDA  <mk@linux-ipv6.org>
 *
 * 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.
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 *
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 * 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.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with this program; if not, see <http://www.gnu.org/licenses/>.
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 */
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/*
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 * [Memo]
 *
 * Outbound:
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 *  The compression of IP datagram MUST be done before AH/ESP processing,
 *  fragmentation, and the addition of Hop-by-Hop/Routing header.
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 *
 * Inbound:
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 *  The decompression of IP datagram MUST be done after the reassembly,
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 *  AH/ESP processing.
 */
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#define pr_fmt(fmt) "IPv6: " fmt

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#include <linux/module.h>
#include <net/ip.h>
#include <net/xfrm.h>
#include <net/ipcomp.h>
#include <linux/crypto.h>
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#include <linux/err.h>
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#include <linux/pfkeyv2.h>
#include <linux/random.h>
#include <linux/percpu.h>
#include <linux/smp.h>
#include <linux/list.h>
#include <linux/vmalloc.h>
#include <linux/rtnetlink.h>
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#include <net/ip6_route.h>
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#include <net/icmp.h>
#include <net/ipv6.h>
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#include <net/protocol.h>
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#include <linux/ipv6.h>
#include <linux/icmpv6.h>
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#include <linux/mutex.h>
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static int ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
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				u8 type, u8 code, int offset, __be32 info)
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{
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	struct net *net = dev_net(skb->dev);
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	__be32 spi;
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	const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data;
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	struct ip_comp_hdr *ipcomph =
		(struct ip_comp_hdr *)(skb->data + offset);
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	struct xfrm_state *x;

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	if (type != ICMPV6_PKT_TOOBIG &&
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	    type != NDISC_REDIRECT)
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		return 0;
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	spi = htonl(ntohs(ipcomph->cpi));
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	x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
			      spi, IPPROTO_COMP, AF_INET6);
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	if (!x)
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		return 0;
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	if (type == NDISC_REDIRECT)
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		ip6_redirect(skb, net, skb->dev->ifindex, 0,
			     sock_net_uid(net, NULL));
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	else
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		ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
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	xfrm_state_put(x);
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	return 0;
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}

static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
{
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	struct net *net = xs_net(x);
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	struct xfrm_state *t = NULL;

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	t = xfrm_state_alloc(net);
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	if (!t)
		goto out;

	t->id.proto = IPPROTO_IPV6;
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	t->id.spi = xfrm6_tunnel_alloc_spi(net, (xfrm_address_t *)&x->props.saddr);
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	if (!t->id.spi)
		goto error;

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	memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
	memcpy(&t->sel, &x->sel, sizeof(t->sel));
	t->props.family = AF_INET6;
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	t->props.mode = x->props.mode;
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	memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
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	memcpy(&t->mark, &x->mark, sizeof(t->mark));
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	if (xfrm_init_state(t))
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		goto error;

	atomic_set(&t->tunnel_users, 1);

out:
	return t;

error:
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	t->km.state = XFRM_STATE_DEAD;
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	xfrm_state_put(t);
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	t = NULL;
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	goto out;
}

static int ipcomp6_tunnel_attach(struct xfrm_state *x)
{
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	struct net *net = xs_net(x);
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	int err = 0;
	struct xfrm_state *t = NULL;
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	__be32 spi;
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	u32 mark = x->mark.m & x->mark.v;
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	spi = xfrm6_tunnel_spi_lookup(net, (xfrm_address_t *)&x->props.saddr);
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	if (spi)
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		t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr,
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					      spi, IPPROTO_IPV6, AF_INET6);
	if (!t) {
		t = ipcomp6_tunnel_create(x);
		if (!t) {
			err = -EINVAL;
			goto out;
		}
		xfrm_state_insert(t);
		xfrm_state_hold(t);
	}
	x->tunnel = t;
	atomic_inc(&t->tunnel_users);

out:
	return err;
}

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static int ipcomp6_init_state(struct xfrm_state *x)
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{
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	int err = -EINVAL;
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	x->props.header_len = 0;
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	switch (x->props.mode) {
	case XFRM_MODE_TRANSPORT:
		break;
	case XFRM_MODE_TUNNEL:
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		x->props.header_len += sizeof(struct ipv6hdr);
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		break;
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	default:
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		goto out;
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	}
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	err = ipcomp_init_state(x);
	if (err)
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		goto out;

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	if (x->props.mode == XFRM_MODE_TUNNEL) {
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		err = ipcomp6_tunnel_attach(x);
		if (err)
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			goto out;
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	}

	err = 0;
out:
	return err;
}

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static int ipcomp6_rcv_cb(struct sk_buff *skb, int err)
{
	return 0;
}

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static const struct xfrm_type ipcomp6_type = {
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	.description	= "IPCOMP6",
	.owner		= THIS_MODULE,
	.proto		= IPPROTO_COMP,
	.init_state	= ipcomp6_init_state,
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	.destructor	= ipcomp_destroy,
	.input		= ipcomp_input,
	.output		= ipcomp_output,
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	.hdr_offset	= xfrm6_find_1stfragopt,
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};

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static struct xfrm6_protocol ipcomp6_protocol = {
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	.handler	= xfrm6_rcv,
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	.cb_handler	= ipcomp6_rcv_cb,
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	.err_handler	= ipcomp6_err,
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	.priority	= 0,
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};

static int __init ipcomp6_init(void)
{
	if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
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		pr_info("%s: can't add xfrm type\n", __func__);
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		return -EAGAIN;
	}
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	if (xfrm6_protocol_register(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
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		pr_info("%s: can't add protocol\n", __func__);
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		xfrm_unregister_type(&ipcomp6_type, AF_INET6);
		return -EAGAIN;
	}
	return 0;
}

static void __exit ipcomp6_fini(void)
{
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	if (xfrm6_protocol_deregister(&ipcomp6_protocol, IPPROTO_COMP) < 0)
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		pr_info("%s: can't remove protocol\n", __func__);
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	if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
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		pr_info("%s: can't remove xfrm type\n", __func__);
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}

module_init(ipcomp6_init);
module_exit(ipcomp6_fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");

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MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);