Re: [Patch net 1/4] flow_dissector: Fix handling of mixed port and port-range keys

[Ido Schimmel <idosch@idosch.org>]

On Mon, Feb 17, 2025 at 08:32:07PM -0800, Cong Wang wrote:
> This patch fixes a bug in TC flower filter where rules combining a
> specific destination port with a source port range weren't working
> correctly.
> 
> The specific case was when users tried to configure rules like:
> 
> tc filter add dev ens38 ingress protocol ip flower ip_proto udp \
> dst_port 5000 src_port 2000-3000 action drop
> 
> The root cause was in the flow dissector code. While both
> FLOW_DISSECTOR_KEY_PORTS and FLOW_DISSECTOR_KEY_PORTS_RANGE flags
> were being set correctly in the classifier, the __skb_flow_dissect_ports()
> function was only populating one of them: whichever came first in
> the enum check. This meant that when the code needed both a specific
> port and a port range, one of them would be left as 0, causing the
> filter to not match packets as expected.
> 
> Fix it by removing the either/or logic and instead checking and
> populating both key types independently when they're in use.
> 
> Fixes: 8ffb055beae5 ("cls_flower: Fix the behavior using port ranges with hw-offload")
> Reported-by: Qiang Zhang <dtzq01@gmail.com>
> Closes: https://lore.kernel.org/netdev/CAPx+-5uvFxkhkz4=j_Xuwkezjn9U6kzKTD5jz4tZ9msSJ0fOJA@mail.gmail.com/
> Cc: Yoshiki Komachi <komachi.yoshiki@gmail.com>
> Cc: Jamal Hadi Salim <jhs@mojatatu.com>
> Cc: Jiri Pirko <jiri@resnulli.us>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>