netdev - Re: [RESEND]tc-flower not worked when configured dst_port and src

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Message-ID: <Z7NoJHQ7hLiTXuA1@pop-os.localdomain>
Date: Mon, 17 Feb 2025 08:47:32 -0800
From: Cong Wang <xiyou.wangcong@...il.com>
To: Qiang Zhang <dtzq01@...il.com>
Cc: Jamal Hadi Salim <jhs@...atatu.com>, Jiri Pirko <jiri@...nulli.us>,
	stable@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
	regressions@...ts.linux.dev
Subject: Re: [RESEND]tc-flower not worked when configured dst_port and
 src_port range in one rule.

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