1 /* 2 * xfrm4_output.c - Common IPsec encapsulation code for IPv4. 3 * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au> 4 * 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. 9 */ 10 11 #include <linux/if_ether.h> 12 #include <linux/kernel.h> 13 #include <linux/module.h> 14 #include <linux/skbuff.h> 15 #include <linux/netfilter_ipv4.h> 16 #include <net/dst.h> 17 #include <net/ip.h> 18 #include <net/xfrm.h> 19 #include <net/icmp.h> 20 21 static int xfrm4_tunnel_check_size(struct sk_buff *skb) 22 { 23 int mtu, ret = 0; 24 25 if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE) 26 goto out; 27 28 if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->ignore_df) 29 goto out; 30 31 mtu = dst_mtu(skb_dst(skb)); 32 if ((!skb_is_gso(skb) && skb->len > mtu) || 33 (skb_is_gso(skb) && 34 !skb_gso_validate_network_len(skb, ip_skb_dst_mtu(skb->sk, skb)))) { 35 skb->protocol = htons(ETH_P_IP); 36 37 if (skb->sk) 38 xfrm_local_error(skb, mtu); 39 else 40 icmp_send(skb, ICMP_DEST_UNREACH, 41 ICMP_FRAG_NEEDED, htonl(mtu)); 42 ret = -EMSGSIZE; 43 } 44 out: 45 return ret; 46 } 47 48 int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb) 49 { 50 int err; 51 52 err = xfrm4_tunnel_check_size(skb); 53 if (err) 54 return err; 55 56 XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol; 57 58 return xfrm4_extract_header(skb); 59 } 60 61 int xfrm4_output_finish(struct sock *sk, struct sk_buff *skb) 62 { 63 memset(IPCB(skb), 0, sizeof(*IPCB(skb))); 64 65 #ifdef CONFIG_NETFILTER 66 IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED; 67 #endif 68 69 return xfrm_output(sk, skb); 70 } 71 72 static int __xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb) 73 { 74 struct xfrm_state *x = skb_dst(skb)->xfrm; 75 76 #ifdef CONFIG_NETFILTER 77 if (!x) { 78 IPCB(skb)->flags |= IPSKB_REROUTED; 79 return dst_output(net, sk, skb); 80 } 81 #endif 82 83 return x->outer_mode->afinfo->output_finish(sk, skb); 84 } 85 86 int xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb) 87 { 88 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, 89 net, sk, skb, NULL, skb_dst(skb)->dev, 90 __xfrm4_output, 91 !(IPCB(skb)->flags & IPSKB_REROUTED)); 92 } 93 94 void xfrm4_local_error(struct sk_buff *skb, u32 mtu) 95 { 96 struct iphdr *hdr; 97 98 hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb); 99 ip_local_error(skb->sk, EMSGSIZE, hdr->daddr, 100 inet_sk(skb->sk)->inet_dport, mtu); 101 } 102