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
