cfg80211: add MPLS and 802.21 classification

MPLS labels may contain traffic control information, which should be
evaluated and used by the wireless subsystem if present.

Also check for IEEE 802.21 which is always network control traffic.
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Mathias Kretschmer <mathias.kretschmer@fokus.fraunhofer.de>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/wireless/util.c

@@ -11,6 +11,7 @@
 #include <net/ip.h>
 #include <net/dsfield.h>
 #include <linux/if_vlan.h>
+#include <linux/mpls.h>
 #include "core.h"
 #include "rdev-ops.h"
 
@@ -717,6 +718,21 @@ unsigned int cfg80211_classify8021d(struct sk_buff *skb,
 	case htons(ETH_P_IPV6):
 		dscp = ipv6_get_dsfield(ipv6_hdr(skb)) & 0xfc;
 		break;
+	case htons(ETH_P_MPLS_UC):
+	case htons(ETH_P_MPLS_MC): {
+		struct mpls_label mpls_tmp, *mpls;
+
+		mpls = skb_header_pointer(skb, sizeof(struct ethhdr),
+					  sizeof(*mpls), &mpls_tmp);
+		if (!mpls)
+			return 0;
+
+		return (ntohl(mpls->entry) & MPLS_LS_TC_MASK)
+			>> MPLS_LS_TC_SHIFT;
+	}
+	case htons(ETH_P_80221):
+		/* 802.21 is always network control traffic */
+		return 7;
 	default:
 		return 0;
 	}