1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173
4 *
5 * Copyright (C)2003 USAGI/WIDE Project
6 *
7 * Author	Mitsuru KANDA  <mk@linux-ipv6.org>
8 */
9/*
10 * [Memo]
11 *
12 * Outbound:
13 *  The compression of IP datagram MUST be done before AH/ESP processing,
14 *  fragmentation, and the addition of Hop-by-Hop/Routing header.
15 *
16 * Inbound:
17 *  The decompression of IP datagram MUST be done after the reassembly,
18 *  AH/ESP processing.
19 */
20
21#define pr_fmt(fmt) "IPv6: " fmt
22
23#include <linux/module.h>
24#include <net/ip.h>
25#include <net/xfrm.h>
26#include <net/ipcomp.h>
27#include <linux/crypto.h>
28#include <linux/err.h>
29#include <linux/pfkeyv2.h>
30#include <linux/random.h>
31#include <linux/percpu.h>
32#include <linux/smp.h>
33#include <linux/list.h>
34#include <linux/vmalloc.h>
35#include <linux/rtnetlink.h>
36#include <net/ip6_route.h>
37#include <net/icmp.h>
38#include <net/ipv6.h>
39#include <net/protocol.h>
40#include <linux/ipv6.h>
41#include <linux/icmpv6.h>
42#include <linux/mutex.h>
43
44static int ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
45				u8 type, u8 code, int offset, __be32 info)
46{
47	struct net *net = dev_net(skb->dev);
48	__be32 spi;
49	const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data;
50	struct ip_comp_hdr *ipcomph =
51		(struct ip_comp_hdr *)(skb->data + offset);
52	struct xfrm_state *x;
53
54	if (type != ICMPV6_PKT_TOOBIG &&
55	    type != NDISC_REDIRECT)
56		return 0;
57
58	spi = htonl(ntohs(ipcomph->cpi));
59	x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
60			      spi, IPPROTO_COMP, AF_INET6);
61	if (!x)
62		return 0;
63
64	if (type == NDISC_REDIRECT)
65		ip6_redirect(skb, net, skb->dev->ifindex, 0,
66			     sock_net_uid(net, NULL));
67	else
68		ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
69	xfrm_state_put(x);
70
71	return 0;
72}
73
74static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
75{
76	struct net *net = xs_net(x);
77	struct xfrm_state *t = NULL;
78
79	t = xfrm_state_alloc(net);
80	if (!t)
81		goto out;
82
83	t->id.proto = IPPROTO_IPV6;
84	t->id.spi = xfrm6_tunnel_alloc_spi(net, (xfrm_address_t *)&x->props.saddr);
85	if (!t->id.spi)
86		goto error;
87
88	memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
89	memcpy(&t->sel, &x->sel, sizeof(t->sel));
90	t->props.family = AF_INET6;
91	t->props.mode = x->props.mode;
92	memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
93	memcpy(&t->mark, &x->mark, sizeof(t->mark));
94	t->if_id = x->if_id;
95
96	if (xfrm_init_state(t))
97		goto error;
98
99	atomic_set(&t->tunnel_users, 1);
100
101out:
102	return t;
103
104error:
105	t->km.state = XFRM_STATE_DEAD;
106	xfrm_state_put(t);
107	t = NULL;
108	goto out;
109}
110
111static int ipcomp6_tunnel_attach(struct xfrm_state *x)
112{
113	struct net *net = xs_net(x);
114	int err = 0;
115	struct xfrm_state *t = NULL;
116	__be32 spi;
117	u32 mark = x->mark.m & x->mark.v;
118
119	spi = xfrm6_tunnel_spi_lookup(net, (xfrm_address_t *)&x->props.saddr);
120	if (spi)
121		t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr,
122					      spi, IPPROTO_IPV6, AF_INET6);
123	if (!t) {
124		t = ipcomp6_tunnel_create(x);
125		if (!t) {
126			err = -EINVAL;
127			goto out;
128		}
129		xfrm_state_insert(t);
130		xfrm_state_hold(t);
131	}
132	x->tunnel = t;
133	atomic_inc(&t->tunnel_users);
134
135out:
136	return err;
137}
138
139static int ipcomp6_init_state(struct xfrm_state *x,
140			      struct netlink_ext_ack *extack)
141{
142	int err = -EINVAL;
143
144	x->props.header_len = 0;
145	switch (x->props.mode) {
146	case XFRM_MODE_TRANSPORT:
147		break;
148	case XFRM_MODE_TUNNEL:
149		x->props.header_len += sizeof(struct ipv6hdr);
150		break;
151	default:
152		NL_SET_ERR_MSG(extack, "Unsupported XFRM mode for IPcomp");
153		goto out;
154	}
155
156	err = ipcomp_init_state(x, extack);
157	if (err)
158		goto out;
159
160	if (x->props.mode == XFRM_MODE_TUNNEL) {
161		err = ipcomp6_tunnel_attach(x);
162		if (err) {
163			NL_SET_ERR_MSG(extack, "Kernel error: failed to initialize the associated state");
164			goto out;
165		}
166	}
167
168	err = 0;
169out:
170	return err;
171}
172
173static int ipcomp6_rcv_cb(struct sk_buff *skb, int err)
174{
175	return 0;
176}
177
178static const struct xfrm_type ipcomp6_type = {
179	.owner		= THIS_MODULE,
180	.proto		= IPPROTO_COMP,
181	.init_state	= ipcomp6_init_state,
182	.destructor	= ipcomp_destroy,
183	.input		= ipcomp_input,
184	.output		= ipcomp_output,
185};
186
187static struct xfrm6_protocol ipcomp6_protocol = {
188	.handler	= xfrm6_rcv,
189	.input_handler	= xfrm_input,
190	.cb_handler	= ipcomp6_rcv_cb,
191	.err_handler	= ipcomp6_err,
192	.priority	= 0,
193};
194
195static int __init ipcomp6_init(void)
196{
197	if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
198		pr_info("%s: can't add xfrm type\n", __func__);
199		return -EAGAIN;
200	}
201	if (xfrm6_protocol_register(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
202		pr_info("%s: can't add protocol\n", __func__);
203		xfrm_unregister_type(&ipcomp6_type, AF_INET6);
204		return -EAGAIN;
205	}
206	return 0;
207}
208
209static void __exit ipcomp6_fini(void)
210{
211	if (xfrm6_protocol_deregister(&ipcomp6_protocol, IPPROTO_COMP) < 0)
212		pr_info("%s: can't remove protocol\n", __func__);
213	xfrm_unregister_type(&ipcomp6_type, AF_INET6);
214}
215
216module_init(ipcomp6_init);
217module_exit(ipcomp6_fini);
218MODULE_LICENSE("GPL");
219MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
220MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
221
222MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);
223