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tap: call skb_probe_transport_header after setting skb->dev

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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: d0e13a1488ad ("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>
This commit is contained in:
Willem de Bruijn 2018-12-30 17:21:05 -05:00 committed by David S. Miller
parent aff6db4545
commit 8c76e77f90
1 changed files with 1 additions and 2 deletions
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3
drivers/net/tap.c
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@ -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);