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>
17 /* Add encapsulation header.
19 * In transport mode, the IP header will be moved forward to make space
20 * for the encapsulation header.
22 * In tunnel mode, the top IP header will be constructed per RFC 2401.
23 * The following fields in it shall be filled in by x->type->output:
27 * On exit, skb->h will be set to the start of the payload to be processed
28 * by x->type->output and skb->nh will be set to the top IP header.
30 static void xfrm4_encap(struct sk_buff *skb)
32 struct dst_entry *dst = skb->dst;
33 struct xfrm_state *x = dst->xfrm;
34 struct iphdr *iph, *top_iph;
39 skb->nh.raw = skb_push(skb, x->props.header_len);
40 top_iph = skb->nh.iph;
43 skb->h.raw += iph->ihl*4;
44 memmove(top_iph, iph, iph->ihl*4);
52 top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
53 if (x->props.flags & XFRM_STATE_NOECN)
54 IP_ECN_clear(top_iph);
56 top_iph->frag_off = iph->frag_off & htons(IP_DF);
57 if (!top_iph->frag_off)
58 __ip_select_ident(top_iph, dst, 0);
61 top_iph->ttl = iph->ttl;
63 top_iph->saddr = x->props.saddr.a4;
64 top_iph->daddr = x->id.daddr.a4;
65 top_iph->protocol = IPPROTO_IPIP;
67 memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
70 int xfrm4_output(struct sk_buff **pskb)
72 struct sk_buff *skb = *pskb;
73 struct dst_entry *dst = skb->dst;
74 struct xfrm_state *x = dst->xfrm;
77 if (skb->ip_summed == CHECKSUM_HW) {
78 err = skb_checksum_help(pskb, 0);
84 spin_lock_bh(&x->lock);
85 err = xfrm_state_check(x, skb);
90 err = xfrm4_tunnel_check_size(skb);
97 err = x->type->output(pskb);
102 x->curlft.bytes += skb->len;
105 spin_unlock_bh(&x->lock);
107 if (!(skb->dst = dst_pop(dst))) {
111 err = NET_XMIT_BYPASS;
116 spin_unlock_bh(&x->lock);