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Commit 93efac3f authored by Herbert Xu's avatar Herbert Xu Committed by Steffen Klassert
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ipv6: Fix IPsec pre-encap fragmentation check 



The IPv6 IPsec pre-encap path performs fragmentation for tunnel-mode
packets.  That is, we perform fragmentation pre-encap rather than
post-encap.

A check was added later to ensure that proper MTU information is
passed back for locally generated traffic.  Unfortunately this
check was performed on all IPsec packets, including transport-mode
packets.

What's more, the check failed to take GSO into account.

The end result is that transport-mode GSO packets get dropped at
the check.

This patch fixes it by moving the tunnel mode check forward as well
as adding the GSO check.

Fixes: dd767856 ("xfrm6: Don't call icmpv6_send on local error")
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarSteffen Klassert <steffen.klassert@secunet.com>
parent 724a7636

net/ipv6/xfrm6_output.c

+11 −6
Original line number Diff line number Diff line
@@ -136,6 +136,7 @@ static int __xfrm6_output(struct sock *sk, struct sk_buff *skb) 
	struct dst_entry *dst = skb_dst(skb);

	struct xfrm_state *x = dst->xfrm;

	int mtu;

	bool toobig;



#ifdef CONFIG_NETFILTER

	if (!x) {
@@ -144,25 +145,29 @@ static int __xfrm6_output(struct sock *sk, struct sk_buff *skb) 
	}

#endif



	if (x->props.mode != XFRM_MODE_TUNNEL)

		goto skip_frag;



	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)) {

	toobig = skb->len > mtu && !skb_is_gso(skb);



	if (toobig && xfrm6_local_dontfrag(skb)) {

		xfrm6_local_rxpmtu(skb, mtu);

		return -EMSGSIZE;

	} else if (!skb->ignore_df && skb->len > mtu && skb->sk) {

	} else if (!skb->ignore_df && toobig && skb->sk) {

		xfrm_local_error(skb, mtu);

		return -EMSGSIZE;

	}



	if (x->props.mode == XFRM_MODE_TUNNEL &&

	    ((skb->len > mtu && !skb_is_gso(skb)) ||

		dst_allfrag(skb_dst(skb)))) {

	if (toobig || dst_allfrag(skb_dst(skb)))

		return ip6_fragment(sk, skb,

				    x->outer_mode->afinfo->output_finish);

	}



skip_frag:

	return x->outer_mode->afinfo->output_finish(sk, skb);

}