Re: [PATCH net v2 2/2] selftests: drv-net: psp: test ipv6 tcp socket with extension headers

["Daniel Zahka" <daniel.zahka@gmail.com>]

On Thu Oct 22, 2026 at 6:30 PM EDT, Todd Freed wrote:
> send on a psp tcp socket in three phases, checking the device's
> tx-packets and what the peer received after each
>
> 1/ no socket options - the data is sent and counted.
>
> 2/ an extension header set on the socket - with destination or
>    hop-by-hop options, the data is sent, counted, and received by the
>    peer. with a routing header, the packets are dropped, tx-packets is
>    unchanged, nothing reaches the peer, and the data stays queued.
>
> 3/ option removed - any queued data, then new data, is sent, counted,
>    and received.
>
> phases 2 and 3 run three times: with a destination options header
> (IPV6_DSTOPTS) and with a hop-by-hop options header (IPV6_HOPOPTS), each
> holding one padn option, and with a segment routing header
> (IPV6_RTHDR) whose only segment is the peer.
>
> in phase 2, a software filter on the peer also counts udp packets from
> the socket's address to the peer's. the psp packets reach the peer as
> decrypted tcp packets, as expected. malformed or unencrypted packets
> show up as udp, and the test asserts there are none. if the peer can't
> take the filter, the test is skipped.
>
> tx-packets is read after it has quiesced, because some devices refresh
> counters periodically (mlx5 takes about a second).
>
> without the fix in the preceding patch:
>
> - with netdevsim, the peer receives none of the data of phase 2, and the
>   test fails on that.
> - with mlx5 (connectx-7), the packets go out unencrypted and aren't
>   counted in tx-packets. the test fails on the udp packets which reach
>   the peer. capturing on the peer,
>
>     tcpdump -i <dev> -nn -A 'ip6 and src host <sender> and not tcp'
>
>   shows them as udp, with the test's payload readable
>
> Signed-off-by: Todd Freed <toddfreed@meta.com>
> ---
>  tools/testing/selftests/drivers/net/config |   1 +
>  tools/testing/selftests/drivers/net/psp.py | 138 ++++++++++++++++++++-
>  2 files changed, 137 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/drivers/net/config b/tools/testing/selftests/drivers/net/config
> index 4838adf27fa1..409f9a96a102 100644
> --- a/tools/testing/selftests/drivers/net/config
> +++ b/tools/testing/selftests/drivers/net/config
> @@ -4,6 +4,7 @@ CONFIG_DEBUG_INFO_BTF_MODULES=n
>  CONFIG_INET_PSP=y
>  CONFIG_IPV6=y
>  CONFIG_MACSEC=m
> +CONFIG_NET_ACT_GACT=m
>  CONFIG_NET_ACT_SKBEDIT=m
>  CONFIG_NET_CLS_ACT=y
>  CONFIG_NET_CLS_BPF=y
> diff --git a/tools/testing/selftests/drivers/net/psp.py b/tools/testing/selftests/drivers/net/psp.py
> index a5b1e14f120f..47e8cb19f376 100755
> --- a/tools/testing/selftests/drivers/net/psp.py
> +++ b/tools/testing/selftests/drivers/net/psp.py
> @@ -16,12 +16,12 @@ from lib.py import ksft_run, ksft_exit, ksft_pr
>  from lib.py import ksft_true, ksft_eq, ksft_ne, ksft_gt, ksft_raises
>  from lib.py import ksft_not_none
>  from lib.py import ksft_variants, KsftNamedVariant
> -from lib.py import KsftSkipEx, KsftFailEx
> +from lib.py import KsftSkipEx, KsftFailEx, CmdExitFailure
>  from lib.py import NetDrvEpEnv, NetDrvContEnv
>  from lib.py import Netlink, NlError, PSPFamily, RtnlFamily
>  from lib.py import NetNSEnter
>  from lib.py import bkg, rand_port, wait_port_listen
> -from lib.py import ip
> +from lib.py import ip, tc
>  
>  TCP_ULP = 31
>  
> @@ -120,6 +120,57 @@ def _check_data_outq(s, exp_len, force_wait=False):
>  def _get_stat(cfg, key):
>      return cfg.pspnl.get_stats({'dev-id': cfg.psp_dev_id})[key]
>  
> +
> +def _get_quiesced_stat(cfg, key, timeout=10):
> +    """
> +    Like _get_stat(), but wait till the value stops changing. Note
> +    that some devices refresh flow counters periodically, e.g. once
> +    per second with mlx5.
> +    """
> +    val = _get_stat(cfg, key)
> +    end = time.monotonic() + timeout
> +    while True:
> +        time.sleep(1.5)
> +        new = _get_stat(cfg, key)
> +        if new == val:
> +            return val
> +        val = new
> +        if time.monotonic() >= end:
> +            ksft_pr(f"{key} still changing after {timeout}s: {val}")
> +            return val
> +
> +
> +def _remote_udp_from(cfg, src, dst):
> +    """
> +    Count what reaches the remote from @src to @dst as UDP, with a software
> +    filter on its ingress (offloaded filter counters are refreshed
> +    periodically). Returns a function reading the count, or None if the
> +    filter can't be installed.
> +    """
> +    flt = (f"dev {cfg.remote_ifname} ingress protocol ipv6 pref 1 "
> +           f"handle 0x5053 flower")
> +    try:
> +        qdiscs = tc(f"qdisc show dev {cfg.remote_ifname}", json=True,
> +                    host=cfg.remote)
> +        if not any(q['kind'] == 'clsact' for q in qdiscs):
> +            tc(f"qdisc add dev {cfg.remote_ifname} clsact", host=cfg.remote)
> +            defer(tc, f"qdisc del dev {cfg.remote_ifname} clsact",
> +                  host=cfg.remote)
> +        tc(f"filter add {flt} skip_hw src_ip {src} dst_ip {dst} "
> +           f"ip_proto udp action drop", host=cfg.remote)
> +    except CmdExitFailure as e:
> +        ksft_pr(f"Can't count UDP on the remote: {e}")
> +        return None
> +    defer(tc, f"filter del {flt}", host=cfg.remote)
> +
> +    def count():
> +        filters = tc(f"-s filter get {flt}", json=True, host=cfg.remote)
> +        for f in filters:
> +            for act in f.get("options", {}).get("actions", []):
> +                return act["stats"]["packets"]
> +        raise KsftFailEx("no action on the remote filter")
> +    return count
> +
>  #
>  # Test case boiler plate
>  #
> @@ -624,6 +675,89 @@ def removal_device_bi(cfg):
>          _close_conn(cfg, s)
>  
>  
> +def data_send_ipv6_exthdr(cfg):
> +    """ Test PSP on IPv6 packets with extension headers """
> +    cfg.require_ipver("6")
> +    _init_psp_dev(cfg)
> +
> +    s = _make_psp_conn(cfg, 0, "6")
> +    try:
> +        # In happy path, PSP traffic arrives at the remote decrypted as TCP
> +        remote_udp = _remote_udp_from(cfg, s.getsockname()[0],
> +                                      s.getpeername()[0])
> +        if not remote_udp:
> +            raise KsftSkipEx("can't count UDP on the remote")
> +
> +        rx_assoc = cfg.pspnl.rx_assoc({"version": 0,
> +                                       "dev-id": cfg.psp_dev_id,
> +                                       "sock-fd": s.fileno()})
> +        tx = _spi_xchg(s, rx_assoc['rx-key'])
> +        cfg.pspnl.tx_assoc({"dev-id": cfg.psp_dev_id,
> +                            "version": 0,
> +                            "tx-key": tx,
> +                            "sock-fd": s.fileno()})
> +        _check_data_outq(s, 0)
> +
> +        def wait_outq_empty():
> +            for _ in range(100):
> +                if _get_outq(s) == 0:
> +                    break
> +                time.sleep(0.5)
> +            _check_data_outq(s, 0)
> +
> +        # 1. No options: sent and counted
> +        tx_pkts = _get_quiesced_stat(cfg, 'tx-packets')
> +        total = _send_careful(cfg, s, 20)
> +        wait_outq_empty()
> +        ksft_gt(_get_quiesced_stat(cfg, 'tx-packets'), tx_pkts)
> +        _check_data_rx(cfg, total)
> +
> +        # An extension header with one PadN option, as destination options
> +        # and as hop-by-hop options, and a segment routing header with the
> +        # peer as its only segment
> +        padn = bytes([0, 0, 1, 4, 0, 0, 0, 0])
> +        srh = bytes([0, 2, 4, 0, 0, 0, 0, 0]) + \
> +            socket.inet_pton(socket.AF_INET6, s.getpeername()[0])
> +        for name, opt, val, sent in (
> +                ("IPV6_DSTOPTS", socket.IPV6_DSTOPTS, padn, True),
> +                ("IPV6_HOPOPTS", socket.IPV6_HOPOPTS, padn, True),
> +                ("IPV6_RTHDR", socket.IPV6_RTHDR, srh, False)):

Maybe parameterizing the test over these options would be better than
the for loop. Then one failure in the chain wouldn't make the whole test
fail, and features like filtering by test case would work.

> +            # 2. With the option. Destination and hop-by-hop options: sent
> +            # encrypted, with UDP + PSP after the extension header, counted,
> +            # and received. Routing header: dropped, not counted, and the
> +            # data stays queued. Nothing reaches the peer as plain UDP.
> +            s.setsockopt(socket.IPPROTO_IPV6, opt, val)
> +            tx_pkts = _get_quiesced_stat(cfg, 'tx-packets')
> +            udp = remote_udp()
> +            queued = _send_careful(cfg, s, 20)
> +            if sent:
> +                total += queued
> +                wait_outq_empty()
> +                ksft_gt(_get_quiesced_stat(cfg, 'tx-packets'), tx_pkts,
> +                        comment=name)
> +            else:
> +                _check_data_outq(s, queued, force_wait=True)
> +                ksft_eq(_get_quiesced_stat(cfg, 'tx-packets'), tx_pkts,
> +                        comment=name)
> +            ksft_eq(remote_udp(), udp, comment=f"{name}: UDP at the remote")
> +            _check_data_rx(cfg, total)
> +            if not sent:
> +                total += queued
> +
> +            # 3. Option removed: any queued data, then new data, sent and
> +            # counted
> +            tx_pkts = _get_quiesced_stat(cfg, 'tx-packets')
> +            s.setsockopt(socket.IPPROTO_IPV6, opt, b'')
> +            wait_outq_empty()
> +            total += _send_careful(cfg, s, 20)
> +            wait_outq_empty()
> +            ksft_gt(_get_quiesced_stat(cfg, 'tx-packets'), tx_pkts,
> +                    comment=name)
> +            _check_data_rx(cfg, total)
> +    finally:
> +        _close_psp_conn(cfg, s)
> +
> +
>  def _get_psp_ver_ip_variants():
>      for ver in range(4):
>          for ipv in ("4", "6"):