11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * xfrm4_output.c - Common IPsec encapsulation code for IPv4. 31da177e4SLinus Torvalds * Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au> 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * This program is free software; you can redistribute it and/or 61da177e4SLinus Torvalds * modify it under the terms of the GNU General Public License 71da177e4SLinus Torvalds * as published by the Free Software Foundation; either version 81da177e4SLinus Torvalds * 2 of the License, or (at your option) any later version. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 1109b8f7a9SHerbert Xu #include <linux/if_ether.h> 1209b8f7a9SHerbert Xu #include <linux/kernel.h> 1336cf9acfSHerbert Xu #include <linux/module.h> 141da177e4SLinus Torvalds #include <linux/skbuff.h> 1516a6677fSPatrick McHardy #include <linux/netfilter_ipv4.h> 1636cf9acfSHerbert Xu #include <net/dst.h> 171da177e4SLinus Torvalds #include <net/ip.h> 181da177e4SLinus Torvalds #include <net/xfrm.h> 191da177e4SLinus Torvalds #include <net/icmp.h> 201da177e4SLinus Torvalds 211da177e4SLinus Torvalds static int xfrm4_tunnel_check_size(struct sk_buff *skb) 221da177e4SLinus Torvalds { 231da177e4SLinus Torvalds int mtu, ret = 0; 241da177e4SLinus Torvalds struct dst_entry *dst; 251da177e4SLinus Torvalds 261da177e4SLinus Torvalds if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE) 271da177e4SLinus Torvalds goto out; 281da177e4SLinus Torvalds 29eddc9ec5SArnaldo Carvalho de Melo if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df) 301da177e4SLinus Torvalds goto out; 311da177e4SLinus Torvalds 32adf30907SEric Dumazet dst = skb_dst(skb); 331da177e4SLinus Torvalds mtu = dst_mtu(dst); 341da177e4SLinus Torvalds if (skb->len > mtu) { 35b00897b8SSteffen Klassert if (skb->sk) 36b00897b8SSteffen Klassert ip_local_error(skb->sk, EMSGSIZE, ip_hdr(skb)->daddr, 37b00897b8SSteffen Klassert inet_sk(skb->sk)->inet_dport, mtu); 38b00897b8SSteffen Klassert else 39b00897b8SSteffen Klassert icmp_send(skb, ICMP_DEST_UNREACH, 40b00897b8SSteffen Klassert ICMP_FRAG_NEEDED, htonl(mtu)); 411da177e4SLinus Torvalds ret = -EMSGSIZE; 421da177e4SLinus Torvalds } 431da177e4SLinus Torvalds out: 441da177e4SLinus Torvalds return ret; 451da177e4SLinus Torvalds } 461da177e4SLinus Torvalds 4736cf9acfSHerbert Xu int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb) 481da177e4SLinus Torvalds { 491da177e4SLinus Torvalds int err; 501da177e4SLinus Torvalds 511da177e4SLinus Torvalds err = xfrm4_tunnel_check_size(skb); 521da177e4SLinus Torvalds if (err) 5336cf9acfSHerbert Xu return err; 5436cf9acfSHerbert Xu 5560d5fcfbSHerbert Xu XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol; 5660d5fcfbSHerbert Xu 5736cf9acfSHerbert Xu return xfrm4_extract_header(skb); 581da177e4SLinus Torvalds } 591da177e4SLinus Torvalds 6036cf9acfSHerbert Xu int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb) 6136cf9acfSHerbert Xu { 6236cf9acfSHerbert Xu int err; 6336cf9acfSHerbert Xu 64df9dcb45SKazunori MIYAZAWA err = xfrm_inner_extract_output(x, skb); 6536cf9acfSHerbert Xu if (err) 6636cf9acfSHerbert Xu return err; 6736cf9acfSHerbert Xu 6836cf9acfSHerbert Xu memset(IPCB(skb), 0, sizeof(*IPCB(skb))); 69862b82c6SHerbert Xu IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED; 7036cf9acfSHerbert Xu 7136cf9acfSHerbert Xu skb->protocol = htons(ETH_P_IP); 7236cf9acfSHerbert Xu 7336cf9acfSHerbert Xu return x->outer_mode->output2(x, skb); 7436cf9acfSHerbert Xu } 7536cf9acfSHerbert Xu EXPORT_SYMBOL(xfrm4_prepare_output); 7636cf9acfSHerbert Xu 7743a4dea4SSteffen Klassert int xfrm4_output_finish(struct sk_buff *skb) 7809b8f7a9SHerbert Xu { 7909b8f7a9SHerbert Xu #ifdef CONFIG_NETFILTER 80adf30907SEric Dumazet if (!skb_dst(skb)->xfrm) { 8109b8f7a9SHerbert Xu IPCB(skb)->flags |= IPSKB_REROUTED; 8209b8f7a9SHerbert Xu return dst_output(skb); 8309b8f7a9SHerbert Xu } 84862b82c6SHerbert Xu 85862b82c6SHerbert Xu IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED; 8609b8f7a9SHerbert Xu #endif 8709b8f7a9SHerbert Xu 8809b8f7a9SHerbert Xu skb->protocol = htons(ETH_P_IP); 89862b82c6SHerbert Xu return xfrm_output(skb); 9009b8f7a9SHerbert Xu } 9109b8f7a9SHerbert Xu 9216a6677fSPatrick McHardy int xfrm4_output(struct sk_buff *skb) 9316a6677fSPatrick McHardy { 9443a4dea4SSteffen Klassert struct dst_entry *dst = skb_dst(skb); 9543a4dea4SSteffen Klassert struct xfrm_state *x = dst->xfrm; 9643a4dea4SSteffen Klassert 979bbc768aSJan Engelhardt return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb, 9843a4dea4SSteffen Klassert NULL, dst->dev, 9943a4dea4SSteffen Klassert x->outer_mode->afinfo->output_finish, 10048d5cad8SPatrick McHardy !(IPCB(skb)->flags & IPSKB_REROUTED)); 10116a6677fSPatrick McHardy } 102