net: mscc: ocelot: refine the ocelot_ace_is_problematic_mac_etype function

The commit mentioned below was a bit too harsh, and while it restricted
the invalid key combinations which are known to not work, such as:

tc filter add dev swp0 ingress proto ip \
      flower src_ip 192.0.2.1 action drop
tc filter add dev swp0 ingress proto all \
      flower src_mac 00:11:22:33:44:55 action drop

it also restricted some which still should work, such as:

tc filter add dev swp0 ingress proto ip \
      flower src_ip 192.0.2.1 action drop
tc filter add dev swp0 ingress proto 0x22f0 \
      flower src_mac 00:11:22:33:44:55 action drop

What actually does not match "sanely" is a MAC_ETYPE rule on frames
having an EtherType of ARP, IPv4, IPv6, in addition to SNAP and OAM
frames (which the ocelot tc-flower implementation does not parse yet, so
the function might need to be revisited again in the future).

So just make the function recognize the problematic MAC_ETYPE rules by
EtherType - thus the VCAP IS2 can be forced to match even on those
packets.

This patch makes it possible for IP rules to live on a port together
with MAC_ETYPE rules that are non-all, non-arp, non-ip and non-ipv6.

Fixes: d4d0cb741d7b ("net: mscc: ocelot: deal with problematic MAC_ETYPE VCAP IS2 rules")
Reported-by: NAllan W. Nielsen <allan.nielsen@microchip.com>
Signed-off-by: NVladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/mscc/ocelot_ace.c

@@ -739,14 +739,24 @@ static void ocelot_match_all_as_mac_etype(struct ocelot *ocelot, int port,
 
 static bool ocelot_ace_is_problematic_mac_etype(struct ocelot_ace_rule *ace)
 {
+	u16 proto, mask;
+
 	if (ace->type != OCELOT_ACE_TYPE_ETYPE)
 		return false;
-	if (ether_addr_to_u64(ace->frame.etype.dmac.value) &
-	    ether_addr_to_u64(ace->frame.etype.dmac.mask))
+
+	proto = ntohs(*(u16 *)ace->frame.etype.etype.value);
+	mask = ntohs(*(u16 *)ace->frame.etype.etype.mask);
+
+	/* ETH_P_ALL match, so all protocols below are included */
+	if (mask == 0)
 		return true;
-	if (ether_addr_to_u64(ace->frame.etype.smac.value) &
-	    ether_addr_to_u64(ace->frame.etype.smac.mask))
+	if (proto == ETH_P_ARP)
 		return true;
+	if (proto == ETH_P_IP)
+		return true;
+	if (proto == ETH_P_IPV6)
+		return true;
+
 	return false;
 }