bnxt_en: flower: validate control flags

This driver currently doesn't support any control flags.

Use flow_rule_match_has_control_flags() to check for control flags,
such as can be set through `tc flower ... ip_flags frag`.

In case any control flags are masked, flow_rule_match_has_control_flags()
sets a NL extended error message, and we return -EOPNOTSUPP.

Only compile-tested.
Signed-off-by: Asbjørn Sloth Tønnesen <ast@fiberby.net>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Tested-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Link: https://lore.kernel.org/r/20240422152626.175569-1-ast@fiberby.netSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/broadcom/bnxt/bnxt_tc.c

@@ -370,6 +370,7 @@ static int bnxt_tc_parse_flow(struct bnxt *bp,
 			      struct bnxt_tc_flow *flow)
 {
 	struct flow_rule *rule = flow_cls_offload_flow_rule(tc_flow_cmd);
+	struct netlink_ext_ack *extack = tc_flow_cmd->common.extack;
 	struct flow_dissector *dissector = rule->match.dissector;
 
 	/* KEY_CONTROL and KEY_BASIC are needed for forming a meaningful key */
@@ -380,6 +381,9 @@ static int bnxt_tc_parse_flow(struct bnxt *bp,
 		return -EOPNOTSUPP;
 	}
 
+	if (flow_rule_match_has_control_flags(rule, extack))
+		return -EOPNOTSUPP;
+
 	if (flow_rule_match_key(rule, FLOW_DISSECTOR_KEY_BASIC)) {
 		struct flow_match_basic match;