Commit 596d087e authored Sep 16, 2020 by Xie He Committed by Greg Kroah-Hartman Oct 07, 2020

drivers/net/wan/lapbether: Make skb->protocol consistent with the header



[ Upstream commit 83f9a9c8c1edc222846dc1bde6e3479703e8e5a3 ]

This driver is a virtual driver stacked on top of Ethernet interfaces.

When this driver transmits data on the Ethernet device, the skb->protocol
setting is inconsistent with the Ethernet header prepended to the skb.

This causes a user listening on the Ethernet interface with an AF_PACKET
socket, to see different sll_protocol values for incoming and outgoing
frames, because incoming frames would have this value set by parsing the
Ethernet header.

This patch changes the skb->protocol value for outgoing Ethernet frames,
making it consistent with the Ethernet header prepended. This makes a
user listening on the Ethernet device with an AF_PACKET socket, to see
the same sll_protocol value for incoming and outgoing frames.

Cc: Martin Schiller <ms@dev.tdt.de>
Signed-off-by: Xie He <xie.he.0141@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent c2df194a

drivers/net/wan/lapbether.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -201,8 +201,6 @@ static void lapbeth_data_transmit(struct net_device ndev, struct sk_buff skb)
		struct net_device *dev;
		int size = skb->len;

		skb->protocol = htons(ETH_P_X25);

		ptr = skb_push(skb, 2);

		*ptr++ = size % 256;
		@@ -213,6 +211,8 @@ static void lapbeth_data_transmit(struct net_device ndev, struct sk_buff skb)

		skb->dev = dev = lapbeth->ethdev;

		skb->protocol = htons(ETH_P_DEC);

		skb_reset_network_header(skb);

		dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);