[Devel] [PATCH 3/3] selftests: forwarding: fix pedit tests failure with br_netfilter enabled

[Konstantin Khorenko]

   Problem: Missed function

   In pedit_dsfield.sh, the function do_test_ip_dscp_ecn() creates its own tc filter directly without 
going through
   do_test_pedit_dsfield():

    tools/testing/selftests/net/forwarding/pedit_dsfield.sh lines 230-232

       tc filter add $locus handle 101 pref 1              \
          flower action pedit ex munge ip dsfield set 124 retain 0xfc  \
             action pedit ex munge ip dsfield set 1 retain 0x03

   This function also modifies the IP header (dsfield), but the checksum recalculation was not added 
here. This will
   still fail with br_netfilter enabled.

   Required fix

   The line should be:

       tc filter add $locus handle 101 pref 1              \
          flower action pedit ex munge ip dsfield set 124 retain 0xfc  \
             action pedit ex munge ip dsfield set 1 retain 0x03    \
             pipe action csum ip

--
Best regards,

Konstantin Khorenko,
Virtuozzo Linux Kernel Team

On 2/1/26 00:19, Aleksei Oladko wrote:
> The tests use the tc pedit action to modify the IPv4 source address
> ("pedit ex munge ip src set"), but the IP header checksum is not
> recalculated after the modification. As a result, the modified packet
> fails sanity checks in br_netfilter after bridging and is dropped,
> which causes the test to fail.
> 
> Fix this by adding an explicit checksum recalculation using the
> "csum ip" action, so the the modified packet contains a valid IPv4
> checksum.
> 
> https://virtuozzo.atlassian.net/browse/VSTOR-123249
> 
> Signed-off-by: Aleksei Oladko <aleksey.oladko at virtuozzo.com>
> ---
>   tools/testing/selftests/net/forwarding/pedit_dsfield.sh | 2 +-
>   tools/testing/selftests/net/forwarding/pedit_ip.sh      | 2 +-
>   2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/net/forwarding/pedit_dsfield.sh b/tools/testing/selftests/net/forwarding/pedit_dsfield.sh
> index af008fbf2725..7cfdff525707 100755
> --- a/tools/testing/selftests/net/forwarding/pedit_dsfield.sh
> +++ b/tools/testing/selftests/net/forwarding/pedit_dsfield.sh
> @@ -156,7 +156,7 @@ do_test_pedit_dsfield()
>   	local daddr=$1; shift
>   
>   	tc filter add $pedit_locus handle 101 pref 1 \
> -	   flower action pedit ex munge $pedit_action
> +	   flower action pedit ex munge $pedit_action pipe action csum ip
>   	tc filter add dev $h2 ingress handle 101 pref 1 prot $match_prot \
>   	   flower skip_hw $match_flower action pass
>   
> diff --git a/tools/testing/selftests/net/forwarding/pedit_ip.sh b/tools/testing/selftests/net/forwarding/pedit_ip.sh
> index d14efb2d23b2..a53ee3b1ef67 100755
> --- a/tools/testing/selftests/net/forwarding/pedit_ip.sh
> +++ b/tools/testing/selftests/net/forwarding/pedit_ip.sh
> @@ -122,7 +122,7 @@ do_test_pedit_ip()
>   	local mz_flags=$1; shift
>   
>   	tc filter add $pedit_locus handle 101 pref 1 \
> -	   flower action pedit ex munge $pedit_action
> +	   flower action pedit ex munge $pedit_action pipe action csum ip
>   	tc filter add dev $h2 ingress handle 101 pref 1 prot $match_prot \
>   	   flower skip_hw $match_flower action pass
>