netdev - [PATCH v2 net] stmmac: strip vlan tag on reception only for 8021q tagged frames

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Message-ID: <35b608aa-0e74-c375-b5e8-35ddc07e0f59@gmail.com>
Date:   Fri, 11 May 2018 10:31:40 +0300
From:   Elad Nachman <eladv6@...il.com>
To:     Toshiaki Makita <makita.toshiaki@....ntt.co.jp>,
        davem@...emloft.net, netdev@...r.kernel.org
Cc:     eladv6@...il.com
Subject: [PATCH v2 net] stmmac: strip vlan tag on reception only for 8021q
 tagged frames

stmmac reception handler calls stmmac_rx_vlan() to strip the vlan before calling napi_gro_receive().

The function assumes VLAN tagged frames are always tagged with 802.1Q protocol,
and assigns ETH_P_8021Q to the skb by hard-coding the parameter on call to __vlan_hwaccel_put_tag() without checking the actual VLAN tag.

This causes packets not to be passed to the VLAN slave if it was created with 802.1AD protocol
(ip link add link eth0 eth0.100 type vlan proto 802.1ad id 100).

This fix only strips the VLAN tag for 802.1Q tagged protocols. 802.1AD frames will be handled later by skb_vlan_untag() .

Signed-off-by: Elad Nachman <eladn@...at.com>

---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index b65e2d1..b230ab5 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3293,17 +3293,21 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 
 static void stmmac_rx_vlan(struct net_device *dev, struct sk_buff *skb)
 {
-	struct ethhdr *ehdr;
+	struct vlan_ethhdr *veth;
 	u16 vlanid;
+	__be16 vlan_proto;
 
 	if ((dev->features & NETIF_F_HW_VLAN_CTAG_RX) ==
 	    NETIF_F_HW_VLAN_CTAG_RX &&
 	    !__vlan_get_tag(skb, &vlanid)) {
-		/* pop the vlan tag */
-		ehdr = (struct ethhdr *)skb->data;
-		memmove(skb->data + VLAN_HLEN, ehdr, ETH_ALEN * 2);
-		skb_pull(skb, VLAN_HLEN);
-		__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), vlanid);
+		veth = (struct vlan_ethhdr *)skb->data;
+		vlan_proto = veth->h_vlan_proto;
+		if (likely(vlan_proto == htons(ETH_P_8021Q))) {
+			/* pop the vlan tag */
+			memmove(skb->data + VLAN_HLEN, veth, ETH_ALEN * 2);
+			skb_pull(skb, VLAN_HLEN);
+			__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), vlanid);
+		}
 	}
 }
 
-- 
2.7.4