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 lock_class_key xfrm_state_lock_key;
 75static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
 76{
 77	struct net *net = xs_net(x);
 78	struct xfrm_state *t = NULL;
 79
 80	t = xfrm_state_alloc(net);
 81	if (!t)
 82		goto out;
 83	lockdep_set_class(&t->lock, &xfrm_state_lock_key);
 84
 85	t->id.proto = IPPROTO_IPV6;
 86	t->id.spi = xfrm6_tunnel_alloc_spi(net, (xfrm_address_t *)&x->props.saddr);
 87	if (!t->id.spi)
 88		goto error;
 89
 90	memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
 91	memcpy(&t->sel, &x->sel, sizeof(t->sel));
 92	t->props.family = AF_INET6;
 93	t->props.mode = x->props.mode;
 94	memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
 95	memcpy(&t->mark, &x->mark, sizeof(t->mark));
 96	t->if_id = x->if_id;
 97
 98	if (xfrm_init_state(t))
 99		goto error;
100
101	atomic_set(&t->tunnel_users, 1);
102
103out:
104	return t;
105
106error:
107	t->km.state = XFRM_STATE_DEAD;
108	xfrm_state_put(t);
109	t = NULL;
110	goto out;
111}
112
113static int ipcomp6_tunnel_attach(struct xfrm_state *x)
114{
115	struct net *net = xs_net(x);
116	int err = 0;
117	struct xfrm_state *t = NULL;
118	__be32 spi;
119	u32 mark = x->mark.m & x->mark.v;
120
121	spi = xfrm6_tunnel_spi_lookup(net, (xfrm_address_t *)&x->props.saddr);
122	if (spi)
123		t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr,
124					      spi, IPPROTO_IPV6, AF_INET6);
125	if (!t) {
126		t = ipcomp6_tunnel_create(x);
127		if (!t) {
128			err = -EINVAL;
129			goto out;
130		}
131		xfrm_state_insert(t);
132		xfrm_state_hold(t);
133	}
134	x->tunnel = t;
135	atomic_inc(&t->tunnel_users);
136
137out:
138	return err;
139}
140
141static int ipcomp6_init_state(struct xfrm_state *x,
142			      struct netlink_ext_ack *extack)
143{
144	int err = -EINVAL;
145
146	x->props.header_len = 0;
147	switch (x->props.mode) {
148	case XFRM_MODE_TRANSPORT:
149		break;
150	case XFRM_MODE_TUNNEL:
151		x->props.header_len += sizeof(struct ipv6hdr);
152		break;
153	default:
154		NL_SET_ERR_MSG(extack, "Unsupported XFRM mode for IPcomp");
155		goto out;
156	}
157
158	err = ipcomp_init_state(x, extack);
159	if (err)
160		goto out;
161
162	if (x->props.mode == XFRM_MODE_TUNNEL) {
163		err = ipcomp6_tunnel_attach(x);
164		if (err) {
165			NL_SET_ERR_MSG(extack, "Kernel error: failed to initialize the associated state");
166			goto out;
167		}
168	}
169
170	err = 0;
171out:
172	return err;
173}
174
175static int ipcomp6_rcv_cb(struct sk_buff *skb, int err)
176{
177	return 0;
178}
179
180static const struct xfrm_type ipcomp6_type = {
181	.owner		= THIS_MODULE,
182	.proto		= IPPROTO_COMP,
183	.init_state	= ipcomp6_init_state,
184	.destructor	= ipcomp_destroy,
185	.input		= ipcomp_input,
186	.output		= ipcomp_output,
187};
188
189static struct xfrm6_protocol ipcomp6_protocol = {
190	.handler	= xfrm6_rcv,
191	.input_handler	= xfrm_input,
192	.cb_handler	= ipcomp6_rcv_cb,
193	.err_handler	= ipcomp6_err,
194	.priority	= 0,
195};
196
197static int __init ipcomp6_init(void)
198{
199	if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
200		pr_info("%s: can't add xfrm type\n", __func__);
201		return -EAGAIN;
202	}
203	if (xfrm6_protocol_register(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
204		pr_info("%s: can't add protocol\n", __func__);
205		xfrm_unregister_type(&ipcomp6_type, AF_INET6);
206		return -EAGAIN;
207	}
208	return 0;
209}
210
211static void __exit ipcomp6_fini(void)
212{
213	if (xfrm6_protocol_deregister(&ipcomp6_protocol, IPPROTO_COMP) < 0)
214		pr_info("%s: can't remove protocol\n", __func__);
215	xfrm_unregister_type(&ipcomp6_type, AF_INET6);
216}
217
218module_init(ipcomp6_init);
219module_exit(ipcomp6_fini);
220MODULE_LICENSE("GPL");
221MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
222MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
223
224MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);