flow_dissector: Add control/reporting of encapsulation

Add an input flag to flow dissector on rather dissection should stop
when encapsulation is detected (IP/IP or GRE). Also, add a key_control
flag that indicates encapsulation was encountered during the
dissection.
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/flow_dissector.h

@@ -14,6 +14,7 @@ struct flow_dissector_key_control {
 	u16	addr_type;
 	u32	is_fragment:1;
 	u32	first_frag:1;
+	u32	encapsulation:1;
 };
 
 /**
@@ -127,6 +128,7 @@ enum flow_dissector_key_id {
 #define FLOW_DISSECTOR_F_PARSE_1ST_FRAG		BIT(0)
 #define FLOW_DISSECTOR_F_STOP_AT_L3		BIT(1)
 #define FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL	BIT(2)
+#define FLOW_DISSECTOR_F_STOP_AT_ENCAP		BIT(3)
 
 struct flow_dissector_key {
 	enum flow_dissector_key_id key_id;

net/core/flow_dissector.c

@@ -397,6 +397,11 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
 			proto = eth->h_proto;
 			nhoff += sizeof(*eth);
 		}
+
+		key_control->encapsulation = 1;
+		if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP)
+			goto out_good;
+
 		goto again;
 	}
 	case NEXTHDR_HOP:
@@ -444,9 +449,19 @@ bool __skb_flow_dissect(const struct sk_buff *skb,
 	}
 	case IPPROTO_IPIP:
 		proto = htons(ETH_P_IP);
+
+		key_control->encapsulation = 1;
+		if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP)
+			goto out_good;
+
 		goto ip;
 	case IPPROTO_IPV6:
 		proto = htons(ETH_P_IPV6);
+
+		key_control->encapsulation = 1;
+		if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP)
+			goto out_good;
+
 		goto ipv6;
 	case IPPROTO_MPLS:
 		proto = htons(ETH_P_MPLS_UC);