net: dsa: lantiq: Allow special tags only on CPU port

Allow the special tag in ingress only on the CPU port and not on all
ports. A packet with a special tag could circumvent the hardware
forwarding and should only be allowed on the CPU port where Linux
controls the port.

Fixes: 14fceff4 ("net: dsa: Add Lantiq / Intel DSA driver for vrx200)"
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/lantiq_gswip.c

@@ -461,8 +461,6 @@ static int gswip_port_enable(struct dsa_switch *ds, int port,
 			 GSWIP_FDMA_PCTRLp(port));
 	gswip_switch_mask(priv, 0, GSWIP_SDMA_PCTRL_EN,
 			  GSWIP_SDMA_PCTRLp(port));
-	gswip_switch_mask(priv, 0, GSWIP_PCE_PCTRL_0_INGRESS,
-			  GSWIP_PCE_PCTRL_0p(port));
 
 	if (!dsa_is_cpu_port(ds, port)) {
 		u32 macconf = GSWIP_MDIO_PHY_LINK_AUTO |
@@ -578,6 +576,10 @@ static int gswip_setup(struct dsa_switch *ds)
 	gswip_switch_mask(priv, 0, GSWIP_FDMA_PCTRL_STEN,
 			  GSWIP_FDMA_PCTRLp(cpu_port));
 
+	/* accept special tag in ingress direction */
+	gswip_switch_mask(priv, 0, GSWIP_PCE_PCTRL_0_INGRESS,
+			  GSWIP_PCE_PCTRL_0p(cpu_port));
+
 	gswip_switch_mask(priv, 0, GSWIP_MAC_CTRL_2_MLEN,
 			  GSWIP_MAC_CTRL_2p(cpu_port));
 	gswip_switch_w(priv, VLAN_ETH_FRAME_LEN + 8, GSWIP_MAC_FLEN);