152 lines
3.5 KiB
C
152 lines
3.5 KiB
C
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/*
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* xfrm4_output.c - Common IPsec encapsulation code for IPv4.
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* Copyright (c) 2004 Herbert Xu <herbert@gondor.apana.org.au>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/if_ether.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/netfilter_ipv4.h>
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#include <net/dst.h>
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#include <net/ip.h>
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#include <net/xfrm.h>
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#include <net/icmp.h>
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static int xfrm4_tunnel_check_size(struct sk_buff *skb)
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{
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int mtu, ret = 0;
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if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
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goto out;
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if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->ignore_df)
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goto out;
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mtu = dst_mtu(skb_dst(skb));
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if ((!skb_is_gso(skb) && skb->len > mtu) ||
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(skb_is_gso(skb) &&
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!skb_gso_validate_network_len(skb, ip_skb_dst_mtu(skb->sk, skb)))) {
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skb->protocol = htons(ETH_P_IP);
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if (skb->sk)
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xfrm_local_error(skb, mtu);
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else
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icmp_send(skb, ICMP_DEST_UNREACH,
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ICMP_FRAG_NEEDED, htonl(mtu));
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ret = -EMSGSIZE;
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}
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out:
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return ret;
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}
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int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
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{
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int err;
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err = xfrm4_tunnel_check_size(skb);
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if (err)
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return err;
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XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;
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return xfrm4_extract_header(skb);
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}
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int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
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{
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int err;
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err = xfrm_inner_extract_output(x, skb);
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if (err)
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return err;
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IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
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skb->protocol = htons(ETH_P_IP);
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return x->outer_mode->output2(x, skb);
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}
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EXPORT_SYMBOL(xfrm4_prepare_output);
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int xfrm4_output_finish(struct sock *sk, struct sk_buff *skb)
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{
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memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
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IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
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return xfrm_output(sk, skb);
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}
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static int __xfrm4_output_finish(struct net *net, struct sock *sk,
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struct sk_buff *skb)
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{
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struct xfrm_state *x = skb_dst(skb)->xfrm;
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return x->outer_mode->afinfo->output_finish(sk, skb);
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}
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static inline int ip4_skb_dst_mtu(struct sk_buff *skb)
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{
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struct inet_sock *np = skb->sk && !dev_recursion_level() ?
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inet_sk(skb->sk) : NULL;
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return (np && np->pmtudisc >= IP_PMTUDISC_PROBE) ?
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skb_dst(skb)->dev->mtu : dst_mtu(skb_dst(skb));
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}
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static int __xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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struct xfrm_state *x = skb_dst(skb)->xfrm;
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int mtu;
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bool toobig;
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#ifdef CONFIG_NETFILTER
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if (!x) {
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IPCB(skb)->flags |= IPSKB_REROUTED;
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return dst_output(net, sk, skb);
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}
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#endif
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if (x->props.mode != XFRM_MODE_TUNNEL)
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goto skip_frag;
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if (skb->protocol == htons(ETH_P_IP))
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mtu = ip4_skb_dst_mtu(skb);
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else
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goto skip_frag;
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toobig = skb->len > mtu && !skb_is_gso(skb);
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if (!skb->ignore_df && toobig && skb->sk) {
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xfrm_local_error(skb, mtu);
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return -EMSGSIZE;
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}
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if (toobig || dst_allfrag(skb_dst(skb)))
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return ip_fragment(net, sk, skb, mtu, __xfrm4_output_finish);
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skip_frag:
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return x->outer_mode->afinfo->output_finish(sk, skb);
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}
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int xfrm4_output(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING,
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net, sk, skb, NULL, skb_dst(skb)->dev,
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__xfrm4_output,
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!(IPCB(skb)->flags & IPSKB_REROUTED));
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}
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void xfrm4_local_error(struct sk_buff *skb, u32 mtu)
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{
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struct iphdr *hdr;
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hdr = skb->encapsulation ? inner_ip_hdr(skb) : ip_hdr(skb);
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ip_local_error(skb->sk, EMSGSIZE, hdr->daddr,
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inet_sk(skb->sk)->inet_dport, mtu);
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}
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