[PATCH net] net: ethtool: Allow matching on vlan CFI bit

[Maxime Chevallier]

Using ethtool, users can specify a classification action matching on the
full vlan tag, which includes the CFI bit.

However, when converting the ethool_flow_spec to a flow_rule, we use
dissector keys to represent the matching patterns.

Since the vlan dissector key doesn't include the CFI bit, this
information was silently discarded when translating the ethtool
flow spec in to a flow_rule.

This commit adds the CFI bit into the vlan dissector key, and allows
propagating the information to the driver when parsing the ethtool flow
spec.

Fixes: eca4205f9ec3 ("ethtool: add ethtool_rx_flow_spec to flow_rule structure translator")
Reported-by: MichaÅ MirosÅaw <mirq-linux@xxxxxxxxxxxx>
Signed-off-by: Maxime Chevallier <maxime.chevallier@xxxxxxxxxxx>
---
Hi all,

Although this prevents information to be silently discarded when parsing
an ethtool_flow_spec, this information doesn't seem to be used by any
driver that converts an ethtool_flow_spec to a flow_rule, hence I'm not
sure this is suitable for -net.

Thanks,

Maxime

 include/net/flow_dissector.h | 1 +
 net/core/ethtool.c           | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index 7c5a8d9a8d2a..9d2e395c6568 100644
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -46,6 +46,7 @@ struct flow_dissector_key_tags {
 
 struct flow_dissector_key_vlan {
 	u16	vlan_id:12,
+		vlan_cfi:1,
 		vlan_priority:3;
 	__be16	vlan_tpid;
 };
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index d08b1e19ce9c..43df34c1ebe1 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -3020,6 +3020,11 @@ ethtool_rx_flow_rule_create(const struct ethtool_rx_flow_spec_input *input)
 			match->mask.vlan.vlan_id =
 				ntohs(ext_m_spec->vlan_tci) & 0x0fff;
 
+			match->key.vlan.vlan_cfi =
+				!!(ntohs(ext_h_spec->vlan_tci) & 0x1000);
+			match->mask.vlan.vlan_cfi =
+				!!(ntohs(ext_m_spec->vlan_tci) & 0x1000);
+
 			match->key.vlan.vlan_priority =
 				(ntohs(ext_h_spec->vlan_tci) & 0xe000) >> 13;
 			match->mask.vlan.vlan_priority =
-- 
2.20.1