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, len: -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, spi: 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(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(handler: &xfrm_tunnel_handler, AF_INET)) {
87 pr_info("%s: can't add xfrm handler for AF_INET\n", __func__);
88 xfrm_unregister_type(type: &ipip_type, AF_INET);
89 return -EAGAIN;
90 }
91#if IS_ENABLED(CONFIG_IPV6)
92 if (xfrm4_tunnel_register(handler: &xfrm64_tunnel_handler, AF_INET6)) {
93 pr_info("%s: can't add xfrm handler for AF_INET6\n", __func__);
94 xfrm4_tunnel_deregister(handler: &xfrm_tunnel_handler, AF_INET);
95 xfrm_unregister_type(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(handler: &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(handler: &xfrm_tunnel_handler, AF_INET))
110 pr_info("%s: can't remove xfrm handler for AF_INET\n",
111 __func__);
112 xfrm_unregister_type(type: &ipip_type, AF_INET);
113}
114
115module_init(ipip_init);
116module_exit(ipip_fini);
117MODULE_LICENSE("GPL");
118MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_IPIP);
119

source code of linux/net/ipv4/xfrm4_tunnel.c