2 * xfrm4_mode_tunnel.c - Tunnel mode encapsulation for IPv4.
4 * Copyright (c) 2004-2006 Herbert Xu <herbert@gondor.apana.org.au>
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>
14 #include <net/inet_ecn.h>
18 static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
20 struct iphdr *inner_iph = ipip_hdr(skb);
22 if (INET_ECN_is_ce(XFRM_MODE_SKB_CB(skb)->tos))
23 IP_ECN_set_ce(inner_iph);
26 /* Add encapsulation header.
28 * The top IP header will be constructed per RFC 2401.
30 static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
32 struct dst_entry *dst = skb_dst(skb);
33 struct iphdr *top_iph;
36 skb_set_network_header(skb, -x->props.header_len);
37 skb->mac_header = skb->network_header +
38 offsetof(struct iphdr, protocol);
39 skb->transport_header = skb->network_header + sizeof(*top_iph);
40 top_iph = ip_hdr(skb);
45 top_iph->protocol = xfrm_af2proto(skb_dst(skb)->ops->family);
48 top_iph->tos = INET_ECN_encapsulate(XFRM_MODE_SKB_CB(skb)->tos,
49 XFRM_MODE_SKB_CB(skb)->tos);
51 flags = x->props.flags;
52 if (flags & XFRM_STATE_NOECN)
53 IP_ECN_clear(top_iph);
55 top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
56 0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));
57 ip_select_ident(top_iph, dst->child, NULL);
59 top_iph->ttl = dst_metric_hoplimit(dst->child);
61 top_iph->saddr = x->props.saddr.a4;
62 top_iph->daddr = x->id.daddr.a4;
67 static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
69 const unsigned char *old_mac;
72 if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPIP)
75 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
78 if (skb_cloned(skb) &&
79 (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
82 if (x->props.flags & XFRM_STATE_DECAP_DSCP)
83 ipv4_copy_dscp(XFRM_MODE_SKB_CB(skb)->tos, ipip_hdr(skb));
84 if (!(x->props.flags & XFRM_STATE_NOECN))
85 ipip_ecn_decapsulate(skb);
87 old_mac = skb_mac_header(skb);
88 skb_set_mac_header(skb, -skb->mac_len);
89 memmove(skb_mac_header(skb), old_mac, skb->mac_len);
90 skb_reset_network_header(skb);
97 static struct xfrm_mode xfrm4_tunnel_mode = {
98 .input2 = xfrm4_mode_tunnel_input,
99 .input = xfrm_prepare_input,
100 .output2 = xfrm4_mode_tunnel_output,
101 .output = xfrm4_prepare_output,
102 .owner = THIS_MODULE,
103 .encap = XFRM_MODE_TUNNEL,
104 .flags = XFRM_MODE_FLAG_TUNNEL,
107 static int __init xfrm4_mode_tunnel_init(void)
109 return xfrm_register_mode(&xfrm4_tunnel_mode, AF_INET);
112 static void __exit xfrm4_mode_tunnel_exit(void)
116 err = xfrm_unregister_mode(&xfrm4_tunnel_mode, AF_INET);
120 module_init(xfrm4_mode_tunnel_init);
121 module_exit(xfrm4_mode_tunnel_exit);
122 MODULE_LICENSE("GPL");
123 MODULE_ALIAS_XFRM_MODE(AF_INET, XFRM_MODE_TUNNEL);