1// SPDX-License-Identifier: GPL-2.0-only
2/* xfrm4_tunnel.c: Generic IP tunnel transformer.
3 *
4 * Copyright (C) 2003 David S. Miller (davem@redhat.com)
5 */
6
7#define pr_fmt(fmt) "IPsec: " fmt
8
9#include <linux/skbuff.h>
10#include <linux/module.h>
11#include <net/xfrm.h>
12#include <net/protocol.h>
13
14static int ipip_output(struct xfrm_state *x, struct sk_buff *skb)
15{
16	skb_push(skb, -skb_network_offset(skb));
17	return 0;
18}
19
20static int ipip_xfrm_rcv(struct xfrm_state *x, struct sk_buff *skb)
21{
22	return ip_hdr(skb)->protocol;
23}
24
25static int ipip_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
26{
27	if (x->props.mode != XFRM_MODE_TUNNEL) {
28		NL_SET_ERR_MSG(extack, "IPv4 tunnel can only be used with tunnel mode");
29		return -EINVAL;
30	}
31
32	if (x->encap) {
33		NL_SET_ERR_MSG(extack, "IPv4 tunnel is not compatible with encapsulation");
34		return -EINVAL;
35	}
36
37	x->props.header_len = sizeof(struct iphdr);
38
39	return 0;
40}
41
42static void ipip_destroy(struct xfrm_state *x)
43{
44}
45
46static const struct xfrm_type ipip_type = {
47	.owner		= THIS_MODULE,
48	.proto	     	= IPPROTO_IPIP,
49	.init_state	= ipip_init_state,
50	.destructor	= ipip_destroy,
51	.input		= ipip_xfrm_rcv,
52	.output		= ipip_output
53};
54
55static int xfrm_tunnel_rcv(struct sk_buff *skb)
56{
57	return xfrm4_rcv_spi(skb, IPPROTO_IPIP, ip_hdr(skb)->saddr);
58}
59
60static int xfrm_tunnel_err(struct sk_buff *skb, u32 info)
61{
62	return -ENOENT;
63}
64
65static struct xfrm_tunnel xfrm_tunnel_handler __read_mostly = {
66	.handler	=	xfrm_tunnel_rcv,
67	.err_handler	=	xfrm_tunnel_err,
68	.priority	=	4,
69};
70
71#if IS_ENABLED(CONFIG_IPV6)
72static struct xfrm_tunnel xfrm64_tunnel_handler __read_mostly = {
73	.handler	=	xfrm_tunnel_rcv,
74	.err_handler	=	xfrm_tunnel_err,
75	.priority	=	3,
76};
77#endif
78
79static int __init ipip_init(void)
80{
81	if (xfrm_register_type(&ipip_type, AF_INET) < 0) {
82		pr_info("%s: can't add xfrm type\n", __func__);
83		return -EAGAIN;
84	}
85
86	if (xfrm4_tunnel_register(&xfrm_tunnel_handler, AF_INET)) {
87		pr_info("%s: can't add xfrm handler for AF_INET\n", __func__);
88		xfrm_unregister_type(&ipip_type, AF_INET);
89		return -EAGAIN;
90	}
91#if IS_ENABLED(CONFIG_IPV6)
92	if (xfrm4_tunnel_register(&xfrm64_tunnel_handler, AF_INET6)) {
93		pr_info("%s: can't add xfrm handler for AF_INET6\n", __func__);
94		xfrm4_tunnel_deregister(&xfrm_tunnel_handler, AF_INET);
95		xfrm_unregister_type(&ipip_type, AF_INET);
96		return -EAGAIN;
97	}
98#endif
99	return 0;
100}
101
102static void __exit ipip_fini(void)
103{
104#if IS_ENABLED(CONFIG_IPV6)
105	if (xfrm4_tunnel_deregister(&xfrm64_tunnel_handler, AF_INET6))
106		pr_info("%s: can't remove xfrm handler for AF_INET6\n",
107			__func__);
108#endif
109	if (xfrm4_tunnel_deregister(&xfrm_tunnel_handler, AF_INET))
110		pr_info("%s: can't remove xfrm handler for AF_INET\n",
111			__func__);
112	xfrm_unregister_type(&ipip_type, AF_INET);
113}
114
115module_init(ipip_init);
116module_exit(ipip_fini);
117MODULE_DESCRIPTION("IPv4 XFRM tunnel driver");
118MODULE_LICENSE("GPL");
119MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_IPIP);
120