Commit 8c76e77f authored Dec 30, 2018 by Willem de Bruijn Committed by David S. Miller Jan 01, 2019

tap: call skb_probe_transport_header after setting skb->dev



The BPF flow dissector expects either skb->sk or skb->dev set on
all skbs. Delay flow dissection until after skb->dev is set.

This requires calling from within an rcu read-side critical section.
That is fine, see also the call from tun_xdp_one.

Fixes: d0e13a14 ("flow_dissector: lookup netns by skb->sk if skb->dev is NULL")
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent aff6db45

drivers/net/tap.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -1177,8 +1177,6 @@ static int tap_get_user_xdp(struct tap_queue q, struct xdp_buff xdp)
		goto err_kfree;
		}

		skb_probe_transport_header(skb, ETH_HLEN);

		/* Move network header to the right position for VLAN tagged packets */
		if ((skb->protocol == htons(ETH_P_8021Q) \|\|
		skb->protocol == htons(ETH_P_8021AD)) &&
		@@ -1189,6 +1187,7 @@ static int tap_get_user_xdp(struct tap_queue q, struct xdp_buff xdp)
		tap = rcu_dereference(q->tap);
		if (tap) {
		skb->dev = tap->dev;
		skb_probe_transport_header(skb, ETH_HLEN);
		dev_queue_xmit(skb);
		} else {
		kfree_skb(skb);

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