| 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 | struct dst_entry *dst; |
| 25 | |
| 26 | if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE) |
| 27 | goto out; |
| 28 | |
| 29 | if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df) |
| 30 | goto out; |
| 31 | |
| 32 | dst = skb->dst; |
| 33 | mtu = dst_mtu(dst); |
| 34 | if (skb->len > mtu) { |
| 35 | icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); |
| 36 | ret = -EMSGSIZE; |
| 37 | } |
| 38 | out: |
| 39 | return ret; |
| 40 | } |
| 41 | |
| 42 | int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb) |
| 43 | { |
| 44 | int err; |
| 45 | |
| 46 | err = xfrm4_tunnel_check_size(skb); |
| 47 | if (err) |
| 48 | return err; |
| 49 | |
| 50 | XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol; |
| 51 | |
| 52 | return xfrm4_extract_header(skb); |
| 53 | } |
| 54 | |
| 55 | int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb) |
| 56 | { |
| 57 | int err; |
| 58 | |
| 59 | err = xfrm_inner_extract_output(x, skb); |
| 60 | if (err) |
| 61 | return err; |
| 62 | |
| 63 | memset(IPCB(skb), 0, sizeof(*IPCB(skb))); |
| 64 | IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED; |
| 65 | |
| 66 | skb->protocol = htons(ETH_P_IP); |
| 67 | |
| 68 | return x->outer_mode->output2(x, skb); |
| 69 | } |
| 70 | EXPORT_SYMBOL(xfrm4_prepare_output); |
| 71 | |
| 72 | static int xfrm4_output_finish(struct sk_buff *skb) |
| 73 | { |
| 74 | #ifdef CONFIG_NETFILTER |
| 75 | if (!skb->dst->xfrm) { |
| 76 | IPCB(skb)->flags |= IPSKB_REROUTED; |
| 77 | return dst_output(skb); |
| 78 | } |
| 79 | |
| 80 | IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED; |
| 81 | #endif |
| 82 | |
| 83 | skb->protocol = htons(ETH_P_IP); |
| 84 | return xfrm_output(skb); |
| 85 | } |
| 86 | |
| 87 | int xfrm4_output(struct sk_buff *skb) |
| 88 | { |
| 89 | return NF_HOOK_COND(PF_INET, NF_INET_POST_ROUTING, skb, |
| 90 | NULL, skb->dst->dev, xfrm4_output_finish, |
| 91 | !(IPCB(skb)->flags & IPSKB_REROUTED)); |
| 92 | } |