net: more accurate network taps in transmit path (b40863c6) · Commits · 戴 / test

dev_queue_xmit_nit() should be called right before ndo_start_xmit() calls or we might give wrong packet contents to taps users : Packet checksum can be changed, or packet can be linearized or segmented, and segments partially sent for the later case. Also a memory allocation can fail and packet never really hit the driver entry point. Reported-by:

Jamie Gloudon <jamie.gloudon@gmail.com> Signed-off-by:

Eric Dumazet <edumazet@google.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/core/dev.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -2213,9 +2213,6 @@ int dev_hard_start_xmit(struct sk_buff skb, struct net_device dev,
		if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
		skb_dst_drop(skb);

		if (!list_empty(&ptype_all))
		dev_queue_xmit_nit(skb, dev);

		features = netif_skb_features(skb);

		if (vlan_tx_tag_present(skb) &&
		@@ -2250,6 +2247,9 @@ int dev_hard_start_xmit(struct sk_buff skb, struct net_device dev,
		}
		}

		if (!list_empty(&ptype_all))
		dev_queue_xmit_nit(skb, dev);

		skb_len = skb->len;
		rc = ops->ndo_start_xmit(skb, dev);
		trace_net_dev_xmit(skb, rc, dev, skb_len);
		@@ -2272,6 +2272,9 @@ gso:
		if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
		skb_dst_drop(nskb);

		if (!list_empty(&ptype_all))
		dev_queue_xmit_nit(nskb, dev);

		skb_len = nskb->len;
		rc = ops->ndo_start_xmit(nskb, dev);
		trace_net_dev_xmit(nskb, rc, dev, skb_len);

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