Re: [PATCH net-next 4/4] selftests/net: Add netkit container ping test

[Bobby Eshleman <bobbyeshleman@gmail.com>]

On Tue, Feb 10, 2026 at 12:04:19PM -0800, David Wei wrote:
> Add a basic ping test using NetDrvContEnv that sets up a netkit pair,
> with one end in a netns. Use LOCAL_PREFIX_V6 and nk_forward BPF program
> to ping from a remote host to the netkit in netns.
> 
> Signed-off-by: David Wei <dw@davidwei.uk>
> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
> ---
>  .../testing/selftests/drivers/net/hw/Makefile |  1 +
>  tools/testing/selftests/drivers/net/hw/config |  3 +++
>  .../selftests/drivers/net/hw/nk_netns.py      | 23 +++++++++++++++++++
>  3 files changed, 27 insertions(+)
>  create mode 100755 tools/testing/selftests/drivers/net/hw/nk_netns.py
> 
> diff --git a/tools/testing/selftests/drivers/net/hw/Makefile b/tools/testing/selftests/drivers/net/hw/Makefile
> index a64140333a46..91df028abfc0 100644
> --- a/tools/testing/selftests/drivers/net/hw/Makefile
> +++ b/tools/testing/selftests/drivers/net/hw/Makefile
> @@ -32,6 +32,7 @@ TEST_PROGS = \
>  	irq.py \
>  	loopback.sh \
>  	nic_timestamp.py \
> +	nk_netns.py \
>  	pp_alloc_fail.py \
>  	rss_api.py \
>  	rss_ctx.py \
> diff --git a/tools/testing/selftests/drivers/net/hw/config b/tools/testing/selftests/drivers/net/hw/config
> index 2307aa001be1..b6524040418e 100644
> --- a/tools/testing/selftests/drivers/net/hw/config
> +++ b/tools/testing/selftests/drivers/net/hw/config
> @@ -1,3 +1,4 @@
> +CONFIG_BPF_SYSCALL=y
>  CONFIG_FAIL_FUNCTION=y
>  CONFIG_FAULT_INJECTION=y
>  CONFIG_FAULT_INJECTION_DEBUG_FS=y
> @@ -5,6 +6,8 @@ CONFIG_FUNCTION_ERROR_INJECTION=y
>  CONFIG_IO_URING=y
>  CONFIG_IPV6=y
>  CONFIG_IPV6_GRE=y
> +CONFIG_NETKIT=y
> +CONFIG_NET_CLS_BPF=y
>  CONFIG_NET_IPGRE=y
>  CONFIG_NET_IPGRE_DEMUX=y
>  CONFIG_UDMABUF=y

I did find CONFIG_NET_SCH_INGRESS=y being needed for the qdisc too,
sorry for missing that last rev.

> diff --git a/tools/testing/selftests/drivers/net/hw/nk_netns.py b/tools/testing/selftests/drivers/net/hw/nk_netns.py
> new file mode 100755
> index 000000000000..afa8638195d8
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/net/hw/nk_netns.py
> @@ -0,0 +1,23 @@
> +#!/usr/bin/env python3
> +# SPDX-License-Identifier: GPL-2.0
> +
> +from lib.py import ksft_run, ksft_exit
> +from lib.py import NetDrvContEnv
> +from lib.py import cmd
> +
> +
> +def test_ping(cfg) -> None:
> +    cfg.require_ipver("6")
> +
> +    cmd(f"ping -c 1 -W5 {cfg.nk_guest_ipv6}", host=cfg.remote)
> +    cmd(f"ping -c 1 -W5 {cfg.remote_addr_v['6']}", ns=cfg.netns)
> +
> +
> +def main() -> None:
> +    with NetDrvContEnv(__file__) as cfg:
> +        ksft_run([test_ping], args=(cfg,))
> +    ksft_exit()
> +
> +
> +if __name__ == "__main__":
> +    main()
> -- 
> 2.47.3
> 

I had some issues getting this to work until I enabled IPv6 forwarding.
I wasn't able to tell if this was only required because of my particular
REMOTE_TYPE=netns setup, or if it is something that is required by this
test specifically? 

I'm also running this directly, but maybe this is done prior in
kselftest?

Best,
Bobby