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/gfp.h>
9 #include <linux/init.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/skbuff.h>
13 #include <linux/stringify.h>
14 #include <net/dsfield.h>
15 #include <net/dst.h>
16 #include <net/inet_ecn.h>
17 #include <net/ip6_route.h>
18 #include <net/ipv6.h>
19 #include <net/xfrm.h>
20
ipip6_ecn_decapsulate(struct sk_buff * skb)21 static inline void ipip6_ecn_decapsulate(struct sk_buff *skb)
22 {
23 const struct ipv6hdr *outer_iph = ipv6_hdr(skb);
24 struct ipv6hdr *inner_iph = ipipv6_hdr(skb);
25
26 if (INET_ECN_is_ce(ipv6_get_dsfield(outer_iph)))
27 IP6_ECN_set_ce(inner_iph);
28 }
29
30 /* Add encapsulation header.
31 *
32 * The top IP header will be constructed per RFC 2401.
33 */
xfrm6_mode_tunnel_output(struct xfrm_state * x,struct sk_buff * skb)34 static int xfrm6_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
35 {
36 struct dst_entry *dst = skb_dst(skb);
37 struct ipv6hdr *top_iph;
38 int dsfield;
39
40 skb_set_network_header(skb, -x->props.header_len);
41 skb->mac_header = skb->network_header +
42 offsetof(struct ipv6hdr, nexthdr);
43 skb->transport_header = skb->network_header + sizeof(*top_iph);
44 top_iph = ipv6_hdr(skb);
45
46 top_iph->version = 6;
47
48 memcpy(top_iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
49 sizeof(top_iph->flow_lbl));
50 top_iph->nexthdr = xfrm_af2proto(skb_dst(skb)->ops->family);
51
52 if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
53 dsfield = 0;
54 else
55 dsfield = XFRM_MODE_SKB_CB(skb)->tos;
56 dsfield = INET_ECN_encapsulate(dsfield, XFRM_MODE_SKB_CB(skb)->tos);
57 if (x->props.flags & XFRM_STATE_NOECN)
58 dsfield &= ~INET_ECN_MASK;
59 ipv6_change_dsfield(top_iph, 0, dsfield);
60 top_iph->hop_limit = ip6_dst_hoplimit(dst->child);
61 top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
62 top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
63 return 0;
64 }
65
xfrm6_mode_tunnel_input(struct xfrm_state * x,struct sk_buff * skb)66 static int xfrm6_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
67 {
68 int err = -EINVAL;
69
70 if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPV6)
71 goto out;
72 if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
73 goto out;
74
75 err = skb_unclone(skb, GFP_ATOMIC);
76 if (err)
77 goto out;
78
79 if (x->props.flags & XFRM_STATE_DECAP_DSCP)
80 ipv6_copy_dscp(ipv6_get_dsfield(ipv6_hdr(skb)),
81 ipipv6_hdr(skb));
82 if (!(x->props.flags & XFRM_STATE_NOECN))
83 ipip6_ecn_decapsulate(skb);
84
85 skb_reset_network_header(skb);
86 skb_mac_header_rebuild(skb);
87
88 err = 0;
89
90 out:
91 return err;
92 }
93
94 static struct xfrm_mode xfrm6_tunnel_mode = {
95 .input2 = xfrm6_mode_tunnel_input,
96 .input = xfrm_prepare_input,
97 .output2 = xfrm6_mode_tunnel_output,
98 .output = xfrm6_prepare_output,
99 .owner = THIS_MODULE,
100 .encap = XFRM_MODE_TUNNEL,
101 .flags = XFRM_MODE_FLAG_TUNNEL,
102 };
103
xfrm6_mode_tunnel_init(void)104 static int __init xfrm6_mode_tunnel_init(void)
105 {
106 return xfrm_register_mode(&xfrm6_tunnel_mode, AF_INET6);
107 }
108
xfrm6_mode_tunnel_exit(void)109 static void __exit xfrm6_mode_tunnel_exit(void)
110 {
111 int err;
112
113 err = xfrm_unregister_mode(&xfrm6_tunnel_mode, AF_INET6);
114 BUG_ON(err);
115 }
116
117 module_init(xfrm6_mode_tunnel_init);
118 module_exit(xfrm6_mode_tunnel_exit);
119 MODULE_LICENSE("GPL");
120 MODULE_ALIAS_XFRM_MODE(AF_INET6, XFRM_MODE_TUNNEL);
121