flow_dissector: Add flag to stop parsing at L3

Add an input flag to flow dissector on rather dissection should be
stopped when an L3 packet is encountered. This would be useful if a
caller just wanted to get IP addresses of the outermost header (e.g.
to do an L3 hash).

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 3410227..bb81e3b 100644 (file)
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -125,6 +125,7 @@ enum flow_dissector_key_id {
 };
 
 #define FLOW_DISSECTOR_F_PARSE_1ST_FRAG                BIT(0)
+#define FLOW_DISSECTOR_F_STOP_AT_L3            BIT(1)
 
 struct flow_dissector_key {
        enum flow_dissector_key_id key_id;

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 907de2f..94fd841 100644 (file)
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -200,6 +200,9 @@ ip:
                        }
                }
 
+               if (flags & FLOW_DISSECTOR_F_STOP_AT_L3)
+                       goto out_good;
+
                break;
        }
        case htons(ETH_P_IPV6): {
@@ -238,6 +241,9 @@ ipv6:
                        }
                }
 
+               if (flags & FLOW_DISSECTOR_F_STOP_AT_L3)
+                       goto out_good;
+
                break;
        }
        case htons(ETH_P_8021AD):