net/ipv4/xfrm4_output.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * xfrm4_output.c - Common IPsec encapsulation code for IPv4.
   4  * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
   5  */
   6
   7 #include <linux/if_ether.h>
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/skbuff.h>
  11 #include <linux/netfilter_ipv4.h>
  12 #include <net/dst.h>
  13 #include <net/ip.h>
  14 #include <net/xfrm.h>
  15 #include <net/icmp.h>
  16
  17 static int __xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
  18 {
  19 #ifdef CONFIG_NETFILTER
  20         struct xfrm_state *x = skb_dst(skb)->xfrm;
  21
  22         if (!x) {
  23                 IPCB(skb)->flags |= IPSKB_REROUTED;
  24                 return dst_output(net, sk, skb);
  25         }
  26 #endif
  27
  28         return xfrm_output(sk, skb);
  29 }
  30
  31 int xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
  32 {
  33         return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
  34                             net, sk, skb, skb->dev, skb_dst(skb)->dev,
  35                             __xfrm4_output,
  36                             !(IPCB(skb)->flags & IPSKB_REROUTED));
  37 }
  38
  39 void xfrm4_local_error(struct sk_buff *skb, u32 mtu)
  40 {
  41         struct iphdr *hdr;
  42
  43         hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb);
  44         ip_local_error(skb->sk, EMSGSIZE, hdr->daddr,
  45                        inet_sk(skb->sk)->inet_dport, mtu);
  46 }