2 * xfrm4_output.c - Common IPsec encapsulation code for IPv4.
3 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
11 #include <linux/skbuff.h>
12 #include <linux/spinlock.h>
13 #include <net/inet_ecn.h>
18 /* Add encapsulation header.
20 * In transport mode, the IP header will be moved forward to make space
21 * for the encapsulation header.
23 * In tunnel mode, the top IP header will be constructed per RFC 2401.
24 * The following fields in it shall be filled in by x->type->output:
28 * On exit, skb->h will be set to the start of the payload to be processed
29 * by x->type->output and skb->nh will be set to the top IP header.
31 static void xfrm4_encap(struct sk_buff *skb)
33 struct dst_entry *dst = skb->dst;
34 struct xfrm_state *x = dst->xfrm;
35 struct iphdr *iph, *top_iph;
40 skb->nh.raw = skb_push(skb, x->props.header_len);
41 top_iph = skb->nh.iph;
44 skb->h.raw += iph->ihl*4;
45 memmove(top_iph, iph, iph->ihl*4);
53 top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
54 if (x->props.flags & XFRM_STATE_NOECN)
55 IP_ECN_clear(top_iph);
57 top_iph->frag_off = iph->frag_off & htons(IP_DF);
58 if (!top_iph->frag_off)
59 __ip_select_ident(top_iph, dst, 0);
62 top_iph->ttl = iph->ttl;
64 top_iph->saddr = x->props.saddr.a4;
65 top_iph->daddr = x->id.daddr.a4;
66 top_iph->protocol = IPPROTO_IPIP;
68 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
71 static int xfrm4_tunnel_check_size(struct sk_buff *skb)
74 struct dst_entry *dst;
75 struct iphdr *iph = skb->nh.iph;
77 if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
80 IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
82 if (!(iph->frag_off & htons(IP_DF)))
86 mtu = dst_pmtu(dst) - dst->header_len - dst->trailer_len;
88 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
95 int xfrm4_output(struct sk_buff **pskb)
97 struct sk_buff *skb = *pskb;
98 struct dst_entry *dst = skb->dst;
99 struct xfrm_state *x = dst->xfrm;
102 if (skb->ip_summed == CHECKSUM_HW) {
103 err = skb_checksum_help(pskb, 0);
109 spin_lock_bh(&x->lock);
110 err = xfrm_state_check(x, skb);
115 err = xfrm4_tunnel_check_size(skb);
122 err = x->type->output(pskb);
127 x->curlft.bytes += skb->len;
130 spin_unlock_bh(&x->lock);
132 if (!(skb->dst = dst_pop(dst))) {
136 err = NET_XMIT_BYPASS;
141 spin_unlock_bh(&x->lock);