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_prepare_output(struct xfrm_state *x, struct sk_buff *skb) 62 { 63 int err; 64 65 err = xfrm_inner_extract_output(x, skb); 66 if (err) 67 return err; 68 69 IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE; 70 skb->protocol = htons(ETH_P_IP); 71 72 return x->outer_mode->output2(x, skb); 73 } 74 EXPORT_SYMBOL(xfrm4_prepare_output); 75 76 int xfrm4_output_finish(struct sock *sk, struct sk_buff *skb) 77 { 78 memset(IPCB(skb), 0, sizeof(*IPCB(skb))); 79 80 #ifdef CONFIG_NETFILTER 81 IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED; 82 #endif 83 84 return xfrm_output(sk, skb); 85 } 86 87 static int __xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb) 88 { 89 struct xfrm_state *x = skb_dst(skb)->xfrm; 90 91 #ifdef CONFIG_NETFILTER 92 if (!x) { 93 IPCB(skb)->flags |= IPSKB_REROUTED; 94 return dst_output(net, sk, skb); 95 } 96 #endif 97 98 return x->outer_mode->afinfo->output_finish(sk, skb); 99 } 100 101 int xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb) 102 { 103 return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, 104 net, sk, skb, NULL, skb_dst(skb)->dev, 105 __xfrm4_output, 106 !(IPCB(skb)->flags & IPSKB_REROUTED)); 107 } 108 109 void xfrm4_local_error(struct sk_buff *skb, u32 mtu) 110 { 111 struct iphdr *hdr; 112 113 hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb); 114 ip_local_error(skb->sk, EMSGSIZE, hdr->daddr, 115 inet_sk(skb->sk)->inet_dport, mtu); 116 } 117