Commit 1f59533f authored Sep 03, 2014 by Jesper Dangaard Brouer Committed by David S. Miller Sep 03, 2014

qdisc: validate frames going through the direct_xmit path



In commit 50cbe9ab ("net: Validate xmit SKBs right when we
pull them out of the qdisc") the validation code was moved out of
dev_hard_start_xmit and into dequeue_skb.

However this overlooked the fact that we do not always enqueue
the skb onto a qdisc. First situation is if qdisc have flag
TCQ_F_CAN_BYPASS and qdisc is empty.  Second situation is if
there is no qdisc on the device, which is a common case for
software devices.

Originally spotted and inital patch by Alexander Duyck.
As a result Alex was seeing issues trying to connect to a
vhost_net interface after commit 50cbe9ab was applied.

Added a call to validate_xmit_skb() in __dev_xmit_skb(), in the
code path for qdiscs with TCQ_F_CAN_BYPASS flag, and in
__dev_queue_xmit() when no qdisc.

Also handle the error situation where dev_hard_start_xmit() could
return a skb list, and does not return dev_xmit_complete(rc) and
falls through to the kfree_skb(), in that situation it should
call kfree_skb_list().

Fixes:  50cbe9ab ("net: Validate xmit SKBs right when we pull them out of the qdisc")
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 3f3c7eec

net/core/dev.c

+8 −2

Original line number	Diff line number	Diff line
		@@ -2739,7 +2739,8 @@ static inline int __dev_xmit_skb(struct sk_buff skb, struct Qdisc q,

		qdisc_bstats_update(q, skb);

		if (sch_direct_xmit(skb, q, dev, txq, root_lock)) {
		skb = validate_xmit_skb(skb, dev);
		if (skb && sch_direct_xmit(skb, q, dev, txq, root_lock)) {
		if (unlikely(contended)) {
		spin_unlock(&q->busylock);
		contended = false;
		@@ -2879,6 +2880,10 @@ static int __dev_queue_xmit(struct sk_buff skb, void accel_priv)
		if (__this_cpu_read(xmit_recursion) > RECURSION_LIMIT)
		goto recursion_alert;

		skb = validate_xmit_skb(skb, dev);
		if (!skb)
		goto drop;

		HARD_TX_LOCK(dev, txq, cpu);

		if (!netif_xmit_stopped(txq)) {
		@@ -2904,10 +2909,11 @@ static int __dev_queue_xmit(struct sk_buff skb, void accel_priv)
		}

		rc = -ENETDOWN;
		drop:
		rcu_read_unlock_bh();

		atomic_long_inc(&dev->tx_dropped);
		kfree_skb(skb);
		kfree_skb_list(skb);
		return rc;
		out:
		rcu_read_unlock_bh();