1 /*
2 * xfrm6_mode_tunnel.c - Tunnel mode encapsulation for IPv6.
3 *
4 * Copyright (C) 2002 USAGI/WIDE Project
5 * Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
6 */
7
8 #include <linux/init.h>
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/skbuff.h>
12 #include <linux/stringify.h>
13 #include <net/dsfield.h>
14 #include <net/dst.h>
15 #include <net/inet_ecn.h>
16 #include <net/ipv6.h>
17 #include <net/xfrm.h>
18
ipip6_ecn_decapsulate(struct sk_buff * skb)19 static inline void ipip6_ecn_decapsulate(struct sk_buff *skb)
20 {
21 struct ipv6hdr *outer_iph = ipv6_hdr(skb);
22 struct ipv6hdr *inner_iph = ipipv6_hdr(skb);
23
24 if (INET_ECN_is_ce(ipv6_get_dsfield(outer_iph)))
25 IP6_ECN_set_ce(inner_iph);
26 }
27
28 /* Add encapsulation header.
29 *
30 * The top IP header will be constructed per RFC 2401.
31 */
xfrm6_mode_tunnel_output(struct xfrm_state * x,struct sk_buff * skb)32 static int xfrm6_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
33 {
34 struct dst_entry *dst = skb->dst;
35 struct ipv6hdr *top_iph;
36 int dsfield;
37
38 skb_set_network_header(skb, -x->props.header_len);
39 skb->mac_header = skb->network_header +
40 offsetof(struct ipv6hdr, nexthdr);
41 skb->transport_header = skb->network_header + sizeof(*top_iph);
42 top_iph = ipv6_hdr(skb);
43
44 top_iph->version = 6;
45
46 memcpy(top_iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
47 sizeof(top_iph->flow_lbl));
48 top_iph->nexthdr = xfrm_af2proto(skb->dst->ops->family);
49
50 dsfield = XFRM_MODE_SKB_CB(skb)->tos;
51 dsfield = INET_ECN_encapsulate(dsfield, dsfield);
52 if (x->props.flags & XFRM_STATE_NOECN)
53 dsfield &= ~INET_ECN_MASK;
54 ipv6_change_dsfield(top_iph, 0, dsfield);
55 top_iph->hop_limit = dst_metric(dst->child, RTAX_HOPLIMIT);
56 ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
57 ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
58 return 0;
59 }
60
xfrm6_mode_tunnel_input(struct xfrm_state * x,struct sk_buff * skb)61 static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
62 {
63 int err = -EINVAL;
64 const unsigned char *old_mac;
65
66 if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPV6)
67 goto out;
68 if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
69 goto out;
70
71 if (skb_cloned(skb) &&
72 (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
73 goto out;
74
75 if (x->props.flags & XFRM_STATE_DECAP_DSCP)
76 ipv6_copy_dscp(ipv6_get_dsfield(ipv6_hdr(skb)),
77 ipipv6_hdr(skb));
78 if (!(x->props.flags & XFRM_STATE_NOECN))
79 ipip6_ecn_decapsulate(skb);
80
81 old_mac = skb_mac_header(skb);
82 skb_set_mac_header(skb, -skb->mac_len);
83 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
84 skb_reset_network_header(skb);
85 err = 0;
86
87 out:
88 return err;
89 }
90
91 static struct xfrm_mode xfrm6_tunnel_mode = {
92 .input2 = xfrm6_mode_tunnel_input,
93 .input = xfrm_prepare_input,
94 .output2 = xfrm6_mode_tunnel_output,
95 .output = xfrm6_prepare_output,
96 .owner = THIS_MODULE,
97 .encap = XFRM_MODE_TUNNEL,
98 .flags = XFRM_MODE_FLAG_TUNNEL,
99 };
100
xfrm6_mode_tunnel_init(void)101 static int __init xfrm6_mode_tunnel_init(void)
102 {
103 return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
104 }
105
xfrm6_mode_tunnel_exit(void)106 static void __exit xfrm6_mode_tunnel_exit(void)
107 {
108 int err;
109
110 err = xfrm_unregister_mode(&xfrm6_tunnel_mode, AF_INET6);
111 BUG_ON(err);
112 }
113
114 module_init(xfrm6_mode_tunnel_init);
115 module_exit(xfrm6_mode_tunnel_exit);
116 MODULE_LICENSE("GPL");
117 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);
118