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628e341f31
In xfrm4 and xfrm6 we need to take care about sockets of the other address family. This could happen because a 6in4 or 4in6 tunnel could get protected by ipsec. Because we don't want to have a run-time dependency on ipv6 when only using ipv4 xfrm we have to embed a pointer to the correct local_error function in xfrm_state_afinet and look it up when returning an error depending on the socket address family. Thanks to vi0ss for the great bug report: <https://bugzilla.kernel.org/show_bug.cgi?id=58691> v2: a) fix two more unsafe interpretations of skb->sk as ipv6 socket (xfrm6_local_dontfrag and __xfrm6_output) v3: a) add an EXPORT_SYMBOL_GPL(xfrm_local_error) to fix a link error when building ipv6 as a module (thanks to Steffen Klassert) Reported-by: <vi0oss@gmail.com> Cc: Steffen Klassert <steffen.klassert@secunet.com> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
110 lines
2.5 KiB
C
110 lines
2.5 KiB
C
/*
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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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struct dst_entry *dst;
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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->local_df)
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goto out;
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dst = skb_dst(skb);
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mtu = dst_mtu(dst);
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if (skb->len > mtu) {
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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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memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
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IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED;
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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 sk_buff *skb)
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{
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#ifdef CONFIG_NETFILTER
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if (!skb_dst(skb)->xfrm) {
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IPCB(skb)->flags |= IPSKB_REROUTED;
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return dst_output(skb);
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}
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IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
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#endif
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skb->protocol = htons(ETH_P_IP);
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return xfrm_output(skb);
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}
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int xfrm4_output(struct sk_buff *skb)
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{
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struct dst_entry *dst = skb_dst(skb);
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struct xfrm_state *x = dst->xfrm;
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return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, skb,
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NULL, dst->dev,
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x->outer_mode->afinfo->output_finish,
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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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