On Fri, Feb 14, 2025 at 05:00:30PM +0800, Qiang Zhang wrote:

Hi, all.

recently met an issue: tc-flower not worked when configured dst_port and src_port range in one rule.

detailed like this: $ tc qdisc add dev ens38 ingress $ tc filter add dev ens38 ingress protocol ip flower ip_proto udp \ dst_port 5000 src_port 2000-3000 action drop

I try to find the root cause in kernel source code:

1. FLOW_DISSECTOR_KEY_PORTS and FLOW_DISSECTOR_KEY_PORTS_RANGE flag of

mask->dissector were set in fl_classify from flow_dissector.c. 2. then skb_flow_dissect -> __skb_flow_dissect -> __skb_flow_dissect_ports. 3. FLOW_DISSECTOR_KEY_PORTS handled and FLOW_DISSECTOR_KEY_PORTS_RANGE not handled in __skb_flow_dissect_ports, so tp_range.tp.src was 0 here expected the actual skb source port.

By the way, __skb_flow_bpf_to_target function may has the same issue.

Please help confirm and fix it, thank you.

Thanks for your analysis and report!

I think you are right, please try the following patch. I tested it by myself and I am working on a selftest to cover this case.

---

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index 5db41bf2ed93..c33af3ef0b79 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -853,23 +853,30 @@ __skb_flow_dissect_ports(const struct sk_buff *skb, void *target_container, const void *data, int nhoff, u8 ip_proto, int hlen) { - enum flow_dissector_key_id dissector_ports = FLOW_DISSECTOR_KEY_MAX; - struct flow_dissector_key_ports *key_ports; + struct flow_dissector_key_ports_range *key_ports_range = NULL; + struct flow_dissector_key_ports *key_ports = NULL; + __be32 ports;

if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_PORTS)) - dissector_ports = FLOW_DISSECTOR_KEY_PORTS; - else if (dissector_uses_key(flow_dissector, - FLOW_DISSECTOR_KEY_PORTS_RANGE)) - dissector_ports = FLOW_DISSECTOR_KEY_PORTS_RANGE; + key_ports = skb_flow_dissector_target(flow_dissector, + FLOW_DISSECTOR_KEY_PORTS, + target_container);

- if (dissector_ports == FLOW_DISSECTOR_KEY_MAX) + if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_PORTS_RANGE)) + key_ports_range = skb_flow_dissector_target(flow_dissector, + FLOW_DISSECTOR_KEY_PORTS_RANGE, + target_container); + + if (!key_ports && !key_ports_range) return;

- key_ports = skb_flow_dissector_target(flow_dissector, - dissector_ports, - target_container); - key_ports->ports = __skb_flow_get_ports(skb, nhoff, ip_proto, - data, hlen); + ports = __skb_flow_get_ports(skb, nhoff, ip_proto, data, hlen); + + if (key_ports) + key_ports->ports = ports; + + if (key_ports_range) + key_ports_range->tp.ports = ports; }

static void