[PATCH net v3 4/4] selftests: drv-net: psp: test ipv6 tcp socket with extension headers

[Todd Freed <toddfreed@meta.com>]

send on a psp tcp socket in three phases, and after each, check that the
data was sent, counted in the device's tx-packets, and received by the
peer. phases:

 1/ no socket options.

 2/ an extension header set on the socket.

 3/ option removed.

the test has a variant for each supported extension header type. for
the routing header, the test enables seg6_enabled on the peer, which
otherwise drops packets with a segment routing header.

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 fixes in the preceding patches:

- with netdevsim, the peer receives none of the data of phase 2. it
  stays in the send queue, and the test fails after waiting for it to
  drain.
- 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 | 137 ++++++++++++++++++++-
 2 files changed, 135 insertions(+), 3 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..2a56a7bf5d24 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 cmd, 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 +675,85 @@ def removal_device_bi(cfg):
         _close_conn(cfg, s)
 
 
+def _ipv6_exthdr_variants():
+    padn = bytes([0, 0, 1, 4, 0, 0, 0, 0])  # one PadN option
+
+    def srh(peer):
+        """ segment routing header, with @peer as its only segment """
+        return (bytes([0, 2, 4, 0, 0, 0, 0, 0]) +
+                socket.inet_pton(socket.AF_INET6, peer))
+
+    yield KsftNamedVariant("dstopts", socket.IPV6_DSTOPTS, lambda peer: padn)
+    yield KsftNamedVariant("hopopts", socket.IPV6_HOPOPTS, lambda peer: padn)
+    yield KsftNamedVariant("rthdr", socket.IPV6_RTHDR, srh)
+
+
+def _remote_seg6_enable(cfg):
+    """ Make the remote accept segment routing headers """
+    for conf in ("all", cfg.remote_ifname):
+        # slashes, so that sysctl doesn't split a dotted ifname
+        key = f"net/ipv6/conf/{conf}/seg6_enabled"
+        old = cmd(f"sysctl -n {key}", host=cfg.remote).stdout.strip()
+        cmd(f"sysctl -qw {key}=1", host=cfg.remote)
+        defer(cmd, f"sysctl -qw {key}={old}", host=cfg.remote)
+
+
+@ksft_variants(_ipv6_exthdr_variants())
+def data_send_ipv6_exthdr(cfg, opt, val):
+    """ Test PSP on IPv6 packets with an extension header """
+    cfg.require_ipver("6")
+    _init_psp_dev(cfg)
+    if opt == socket.IPV6_RTHDR:
+        _remote_seg6_enable(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)
+
+        total = 0
+
+        def send(phase):
+            """ Sent encrypted, counted, and received. Nothing reaches the
+            peer as plain UDP.
+            """
+            nonlocal total
+            tx_pkts = _get_quiesced_stat(cfg, 'tx-packets')
+            udp = remote_udp()
+            total += _send_careful(cfg, s, 20)
+            for _ in range(100):
+                if _get_outq(s) == 0:
+                    break
+                time.sleep(0.5)
+            _check_data_outq(s, 0)
+            ksft_gt(_get_quiesced_stat(cfg, 'tx-packets'), tx_pkts,
+                    comment=phase)
+            ksft_eq(remote_udp(), udp, comment=f"{phase}: UDP at the remote")
+            _check_data_rx(cfg, total)
+
+        send("no option")
+        # UDP + PSP go after the extension header
+        s.setsockopt(socket.IPPROTO_IPV6, opt, val(s.getpeername()[0]))
+        send("with the option")
+        s.setsockopt(socket.IPPROTO_IPV6, opt, b'')
+        send("option removed")
+    finally:
+        _close_psp_conn(cfg, s)
+
+
 def _get_psp_ver_ip_variants():
     for ver in range(4):
         for ipv in ("4", "6"):
@@ -1019,7 +1149,8 @@ def main() -> None:
                                                           cfg.comm_port),
                                                          timeout=1)
 
-                cases = [data_basic_send, data_mss_adjust]
+                cases = [data_basic_send, data_mss_adjust,
+                         data_send_ipv6_exthdr]
 
                 if has_cont:
                     cases += [
-- 
2.53.0-Meta