flow_dissector: Add number of vlan tags dissector

Our customers in the fiber telecom world have network configurations
where they would like to control their traffic according to the number
of tags appearing in the packet.

For example, TR247 GPON conformance test suite specification mostly
talks about untagged, single, double tagged packets and gives lax
guidelines on the vlan protocol vs. number of vlan tags.

This is different from the common IT networks where 802.1Q and 802.1ad
protocols are usually describe single and double tagged packet. GPON
configurations that we work with have arbitrary mix the above protocols
and number of vlan tags in the packet.

The goal is to make the following TC commands possible:

tc filter add dev eth1 ingress flower \
  num_of_vlans 1 vlan_prio 5 action drop

From our logs, we have redirect rules such that:

tc filter add dev $GPON ingress flower num_of_vlans $N \
     action mirred egress redirect dev $DEV

where N can range from 0 to 3 and $DEV is the function of $N.

Also there are rules setting skb mark based on the number of vlans:

tc filter add dev $GPON ingress flower num_of_vlans $N vlan_prio \
    $P action skbedit mark $M

This new dissector allows extracting the number of vlan tags existing in
the packet.

Signed-off-by: Boris Sukholitko <boris.sukholitko@broadcom.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 9f65f1bfbd24646c4d9a37db85360126d038fc42..a4c6057c70972a81f880be521beedbad5bf1905f 100644 (file)
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -253,6 +253,14 @@ struct flow_dissector_key_hash {
        u32 hash;
 };
 
+/**
+ * struct flow_dissector_key_num_of_vlans:
+ * @num_of_vlans: num_of_vlans value
+ */
+struct flow_dissector_key_num_of_vlans {
+       u8 num_of_vlans;
+};
+
 enum flow_dissector_key_id {
        FLOW_DISSECTOR_KEY_CONTROL, /* struct flow_dissector_key_control */
        FLOW_DISSECTOR_KEY_BASIC, /* struct flow_dissector_key_basic */
@@ -282,6 +290,7 @@ enum flow_dissector_key_id {
        FLOW_DISSECTOR_KEY_META, /* struct flow_dissector_key_meta */
        FLOW_DISSECTOR_KEY_CT, /* struct flow_dissector_key_ct */
        FLOW_DISSECTOR_KEY_HASH, /* struct flow_dissector_key_hash */
+       FLOW_DISSECTOR_KEY_NUM_OF_VLANS, /* struct flow_dissector_key_num_of_vlans */
 
        FLOW_DISSECTOR_KEY_MAX,
 };

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 6f7ec72016dcd5e0caa90ea631d06317e667d8d7..6aee04f75e3e4128839e064291dccdcaa311e15c 100644 (file)
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -1035,6 +1035,16 @@ bool __skb_flow_dissect(const struct net *net,
                memcpy(key_eth_addrs, eth, sizeof(*key_eth_addrs));
        }
 
+       if (dissector_uses_key(flow_dissector,
+                              FLOW_DISSECTOR_KEY_NUM_OF_VLANS)) {
+               struct flow_dissector_key_num_of_vlans *key_num_of_vlans;
+
+               key_num_of_vlans = skb_flow_dissector_target(flow_dissector,
+                                                            FLOW_DISSECTOR_KEY_NUM_OF_VLANS,
+                                                            target_container);
+               key_num_of_vlans->num_of_vlans = 0;
+       }
+
 proto_again:
        fdret = FLOW_DISSECT_RET_CONTINUE;
 
@@ -1158,6 +1168,16 @@ proto_again:
                        nhoff += sizeof(*vlan);
                }
 
+               if (dissector_uses_key(flow_dissector,
+                                      FLOW_DISSECTOR_KEY_NUM_OF_VLANS)) {
+                       struct flow_dissector_key_num_of_vlans *key_nvs;
+
+                       key_nvs = skb_flow_dissector_target(flow_dissector,
+                                                           FLOW_DISSECTOR_KEY_NUM_OF_VLANS,
+                                                           target_container);
+                       key_nvs->num_of_vlans++;
+               }
+
                if (dissector_vlan == FLOW_DISSECTOR_KEY_MAX) {
                        dissector_vlan = FLOW_DISSECTOR_KEY_VLAN;
                } else if (dissector_vlan == FLOW_DISSECTOR_KEY_VLAN) {