Commit 5a25cf1e authored by Hannes Frederic Sowa's avatar Hannes Frederic Sowa Committed by Steffen Klassert
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xfrm: revert ipv4 mtu determination to dst_mtu 



In commit 0ea9d5e3 ("xfrm: introduce
helper for safe determination of mtu") I switched the determination of
ipv4 mtus from dst_mtu to ip_skb_dst_mtu. This was an error because in
case of IP_PMTUDISC_PROBE we fall back to the interface mtu, which is
never correct for ipv4 ipsec.

This patch partly reverts 0ea9d5e3
("xfrm: introduce helper for safe determination of mtu").

Cc: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
parent 844d4874

include/net/xfrm.h

+0 −12
Original line number Diff line number Diff line
@@ -20,7 +20,6 @@ 
#include <net/route.h>

#include <net/ipv6.h>

#include <net/ip6_fib.h>

#include <net/ip6_route.h>

#include <net/flow.h>



#include <linux/interrupt.h>
@@ -1724,15 +1723,4 @@ static inline int xfrm_mark_put(struct sk_buff *skb, const struct xfrm_mark *m) 
	return ret;

}



static inline int xfrm_skb_dst_mtu(struct sk_buff *skb)

{

	struct sock *sk = skb->sk;



	if (sk && skb->protocol == htons(ETH_P_IPV6))

		return ip6_skb_dst_mtu(skb);

	else if (sk && skb->protocol == htons(ETH_P_IP))

		return ip_skb_dst_mtu(skb);

	return dst_mtu(skb_dst(skb));

}



#endif	/* _NET_XFRM_H */

net/ipv4/xfrm4_output.c

+1 −1
Original line number Diff line number Diff line
@@ -28,7 +28,7 @@ static int xfrm4_tunnel_check_size(struct sk_buff *skb) 
	if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->local_df)

		goto out;



	mtu = xfrm_skb_dst_mtu(skb);

	mtu = dst_mtu(skb_dst(skb));

	if (skb->len > mtu) {

		if (skb->sk)

			xfrm_local_error(skb, mtu);

net/ipv6/xfrm6_output.c

+5 −3
Original line number Diff line number Diff line
@@ -140,10 +140,12 @@ static int __xfrm6_output(struct sk_buff *skb) 
{

	struct dst_entry *dst = skb_dst(skb);

	struct xfrm_state *x = dst->xfrm;

	int mtu = xfrm_skb_dst_mtu(skb);

	int mtu;



	if (mtu < IPV6_MIN_MTU)

		mtu = IPV6_MIN_MTU;

	if (skb->protocol == htons(ETH_P_IPV6))

		mtu = ip6_skb_dst_mtu(skb);

	else

		mtu = dst_mtu(skb_dst(skb));



	if (skb->len > mtu && xfrm6_local_dontfrag(skb)) {

		xfrm6_local_rxpmtu(skb, mtu);

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