pkt_sched: ingress socket filter by mark

Allow bpf to set a filter to drop packets that dont
match a specific mark

Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/filter.h

@@ -123,7 +123,8 @@ struct sock_fprog	/* Required for SO_ATTACH_FILTER. */
 #define SKF_AD_IFINDEX 	8
 #define SKF_AD_NLATTR	12
 #define SKF_AD_NLATTR_NEST	16
-#define SKF_AD_MAX	20
+#define SKF_AD_MARK 	20
+#define SKF_AD_MAX	24
 #define SKF_NET_OFF   (-0x100000)
 #define SKF_LL_OFF    (-0x200000)
 

net/core/filter.c

@@ -303,6 +303,9 @@ load_b:
 		case SKF_AD_IFINDEX:
 			A = skb->dev->ifindex;
 			continue;
+		case SKF_AD_MARK:
+			A = skb->mark;
+			continue;
 		case SKF_AD_NLATTR: {
 			struct nlattr *nla;