/net/ipv6/ipcomp6.c

  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
 95	if (xfrm_init_state(t))
 96		goto error;
 97
 98	atomic_set(&t->tunnel_users, 1);
 99
100out:
101	return t;
102
103error:
104	t->km.state = XFRM_STATE_DEAD;
105	xfrm_state_put(t);
106	t = NULL;
107	goto out;
108}
109
110static int ipcomp6_tunnel_attach(struct xfrm_state *x)
111{
112	struct net *net = xs_net(x);
113	int err = 0;
114	struct xfrm_state *t = NULL;
115	__be32 spi;
116	u32 mark = x->mark.m & x->mark.v;
117
118	spi = xfrm6_tunnel_spi_lookup(net, (xfrm_address_t *)&x->props.saddr);
119	if (spi)
120		t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr,
121					      spi, IPPROTO_IPV6, AF_INET6);
122	if (!t) {
123		t = ipcomp6_tunnel_create(x);
124		if (!t) {
125			err = -EINVAL;
126			goto out;
127		}
128		xfrm_state_insert(t);
129		xfrm_state_hold(t);
130	}
131	x->tunnel = t;
132	atomic_inc(&t->tunnel_users);
133
134out:
135	return err;
136}
137
138static int ipcomp6_init_state(struct xfrm_state *x)
139{
140	int err = -EINVAL;
141
142	x->props.header_len = 0;
143	switch (x->props.mode) {
144	case XFRM_MODE_TRANSPORT:
145		break;
146	case XFRM_MODE_TUNNEL:
147		x->props.header_len += sizeof(struct ipv6hdr);
148		break;
149	default:
150		goto out;
151	}
152
153	err = ipcomp_init_state(x);
154	if (err)
155		goto out;
156
157	if (x->props.mode == XFRM_MODE_TUNNEL) {
158		err = ipcomp6_tunnel_attach(x);
159		if (err)
160			goto out;
161	}
162
163	err = 0;
164out:
165	return err;
166}
167
168static int ipcomp6_rcv_cb(struct sk_buff *skb, int err)
169{
170	return 0;
171}
172
173static const struct xfrm_type ipcomp6_type = {
174	.description	= "IPCOMP6",
175	.owner		= THIS_MODULE,
176	.proto		= IPPROTO_COMP,
177	.init_state	= ipcomp6_init_state,
178	.destructor	= ipcomp_destroy,
179	.input		= ipcomp_input,
180	.output		= ipcomp_output,
181	.hdr_offset	= xfrm6_find_1stfragopt,
182};
183
184static struct xfrm6_protocol ipcomp6_protocol = {
185	.handler	= xfrm6_rcv,
186	.cb_handler	= ipcomp6_rcv_cb,
187	.err_handler	= ipcomp6_err,
188	.priority	= 0,
189};
190
191static int __init ipcomp6_init(void)
192{
193	if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
194		pr_info("%s: can't add xfrm type\n", __func__);
195		return -EAGAIN;
196	}
197	if (xfrm6_protocol_register(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
198		pr_info("%s: can't add protocol\n", __func__);
199		xfrm_unregister_type(&ipcomp6_type, AF_INET6);
200		return -EAGAIN;
201	}
202	return 0;
203}
204
205static void __exit ipcomp6_fini(void)
206{
207	if (xfrm6_protocol_deregister(&ipcomp6_protocol, IPPROTO_COMP) < 0)
208		pr_info("%s: can't remove protocol\n", __func__);
209	xfrm_unregister_type(&ipcomp6_type, AF_INET6);
210}
211
212module_init(ipcomp6_init);
213module_exit(ipcomp6_fini);
214MODULE_LICENSE("GPL");
215MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
216MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
217
218MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);