1/*
2 * IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173
3 *
4 * Copyright (C)2003 USAGI/WIDE Project
5 *
6 * Author	Mitsuru KANDA  <mk@linux-ipv6.org>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, see <http://www.gnu.org/licenses/>.
20 */
21/*
22 * [Memo]
23 *
24 * Outbound:
25 *  The compression of IP datagram MUST be done before AH/ESP processing,
26 *  fragmentation, and the addition of Hop-by-Hop/Routing header.
27 *
28 * Inbound:
29 *  The decompression of IP datagram MUST be done after the reassembly,
30 *  AH/ESP processing.
31 */
32
33#define pr_fmt(fmt) "IPv6: " fmt
34
35#include <linux/module.h>
36#include <net/ip.h>
37#include <net/xfrm.h>
38#include <net/ipcomp.h>
39#include <linux/crypto.h>
40#include <linux/err.h>
41#include <linux/pfkeyv2.h>
42#include <linux/random.h>
43#include <linux/percpu.h>
44#include <linux/smp.h>
45#include <linux/list.h>
46#include <linux/vmalloc.h>
47#include <linux/rtnetlink.h>
48#include <net/ip6_route.h>
49#include <net/icmp.h>
50#include <net/ipv6.h>
51#include <net/protocol.h>
52#include <linux/ipv6.h>
53#include <linux/icmpv6.h>
54#include <linux/mutex.h>
55
56static int ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
57				u8 type, u8 code, int offset, __be32 info)
58{
59	struct net *net = dev_net(skb->dev);
60	__be32 spi;
61	const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data;
62	struct ip_comp_hdr *ipcomph =
63		(struct ip_comp_hdr *)(skb->data + offset);
64	struct xfrm_state *x;
65
66	if (type != ICMPV6_PKT_TOOBIG &&
67	    type != NDISC_REDIRECT)
68		return 0;
69
70	spi = htonl(ntohs(ipcomph->cpi));
71	x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
72			      spi, IPPROTO_COMP, AF_INET6);
73	if (!x)
74		return 0;
75
76	if (type == NDISC_REDIRECT)
77		ip6_redirect(skb, net, skb->dev->ifindex, 0);
78	else
79		ip6_update_pmtu(skb, net, info, 0, 0);
80	xfrm_state_put(x);
81
82	return 0;
83}
84
85static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
86{
87	struct net *net = xs_net(x);
88	struct xfrm_state *t = NULL;
89
90	t = xfrm_state_alloc(net);
91	if (!t)
92		goto out;
93
94	t->id.proto = IPPROTO_IPV6;
95	t->id.spi = xfrm6_tunnel_alloc_spi(net, (xfrm_address_t *)&x->props.saddr);
96	if (!t->id.spi)
97		goto error;
98
99	memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
100	memcpy(&t->sel, &x->sel, sizeof(t->sel));
101	t->props.family = AF_INET6;
102	t->props.mode = x->props.mode;
103	memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
104	memcpy(&t->mark, &x->mark, sizeof(t->mark));
105
106	if (xfrm_init_state(t))
107		goto error;
108
109	atomic_set(&t->tunnel_users, 1);
110
111out:
112	return t;
113
114error:
115	t->km.state = XFRM_STATE_DEAD;
116	xfrm_state_put(t);
117	t = NULL;
118	goto out;
119}
120
121static int ipcomp6_tunnel_attach(struct xfrm_state *x)
122{
123	struct net *net = xs_net(x);
124	int err = 0;
125	struct xfrm_state *t = NULL;
126	__be32 spi;
127	u32 mark = x->mark.m & x->mark.v;
128
129	spi = xfrm6_tunnel_spi_lookup(net, (xfrm_address_t *)&x->props.saddr);
130	if (spi)
131		t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr,
132					      spi, IPPROTO_IPV6, AF_INET6);
133	if (!t) {
134		t = ipcomp6_tunnel_create(x);
135		if (!t) {
136			err = -EINVAL;
137			goto out;
138		}
139		xfrm_state_insert(t);
140		xfrm_state_hold(t);
141	}
142	x->tunnel = t;
143	atomic_inc(&t->tunnel_users);
144
145out:
146	return err;
147}
148
149static int ipcomp6_init_state(struct xfrm_state *x)
150{
151	int err = -EINVAL;
152
153	x->props.header_len = 0;
154	switch (x->props.mode) {
155	case XFRM_MODE_TRANSPORT:
156		break;
157	case XFRM_MODE_TUNNEL:
158		x->props.header_len += sizeof(struct ipv6hdr);
159		break;
160	default:
161		goto out;
162	}
163
164	err = ipcomp_init_state(x);
165	if (err)
166		goto out;
167
168	if (x->props.mode == XFRM_MODE_TUNNEL) {
169		err = ipcomp6_tunnel_attach(x);
170		if (err)
171			goto out;
172	}
173
174	err = 0;
175out:
176	return err;
177}
178
179static int ipcomp6_rcv_cb(struct sk_buff *skb, int err)
180{
181	return 0;
182}
183
184static const struct xfrm_type ipcomp6_type = {
185	.description	= "IPCOMP6",
186	.owner		= THIS_MODULE,
187	.proto		= IPPROTO_COMP,
188	.init_state	= ipcomp6_init_state,
189	.destructor	= ipcomp_destroy,
190	.input		= ipcomp_input,
191	.output		= ipcomp_output,
192	.hdr_offset	= xfrm6_find_1stfragopt,
193};
194
195static struct xfrm6_protocol ipcomp6_protocol = {
196	.handler	= xfrm6_rcv,
197	.cb_handler	= ipcomp6_rcv_cb,
198	.err_handler	= ipcomp6_err,
199	.priority	= 0,
200};
201
202static int __init ipcomp6_init(void)
203{
204	if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
205		pr_info("%s: can't add xfrm type\n", __func__);
206		return -EAGAIN;
207	}
208	if (xfrm6_protocol_register(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
209		pr_info("%s: can't add protocol\n", __func__);
210		xfrm_unregister_type(&ipcomp6_type, AF_INET6);
211		return -EAGAIN;
212	}
213	return 0;
214}
215
216static void __exit ipcomp6_fini(void)
217{
218	if (xfrm6_protocol_deregister(&ipcomp6_protocol, IPPROTO_COMP) < 0)
219		pr_info("%s: can't remove protocol\n", __func__);
220	if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
221		pr_info("%s: can't remove xfrm type\n", __func__);
222}
223
224module_init(ipcomp6_init);
225module_exit(ipcomp6_fini);
226MODULE_LICENSE("GPL");
227MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
228MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
229
230MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);
231