/* * xfrm4_output.c - Common IPsec encapsulation code for IPv4. * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/if_ether.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/skbuff.h> #include <linux/netfilter_ipv4.h> #include <net/dst.h> #include <net/ip.h> #include <net/xfrm.h> #include <net/icmp.h> static int xfrm4_tunnel_check_size(struct sk_buff *skb) { int mtu, ret = 0; struct dst_entry *dst; if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE) goto out; if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df) goto out; dst = skb_dst(skb); mtu = dst_mtu(dst); if (skb->len > mtu) { if (skb->sk) ip_local_error(skb->sk, EMSGSIZE, ip_hdr(skb)->daddr, inet_sk(skb->sk)->inet_dport, mtu); else icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); ret = -EMSGSIZE; } out: return ret; } int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb) { int err; err = xfrm4_tunnel_check_size(skb); if (err) return err; XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol; return xfrm4_extract_header(skb); } int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb) { int err; err = xfrm_inner_extract_output(x, skb); if (err) return err; memset(IPCB(skb), 0, sizeof(*IPCB(skb))); IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED; skb->protocol = htons(ETH_P_IP); return x->outer_mode->output2(x, skb); } EXPORT_SYMBOL(xfrm4_prepare_output); int xfrm4_output_finish(struct sk_buff *skb) { #ifdef CONFIG_NETFILTER if (!skb_dst(skb)->xfrm) { IPCB(skb)->flags |= IPSKB_REROUTED; return dst_output(skb); } IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED; #endif skb->protocol = htons(ETH_P_IP); return xfrm_output(skb); } int xfrm4_output(struct sk_buff *skb) { struct dst_entry *dst = skb_dst(skb); struct xfrm_state *x = dst->xfrm; return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, NULL, dst->dev, x->outer_mode->afinfo->output_finish, !(IPCB(skb)->flags & IPSKB_REROUTED)); }