[PATCH net-next v7 5/5] selftests: net: test AF_PACKET multicast dumps

[Yuyang Huang <sigefriedhyy@gmail.com>]

Dump the link-layer multicast addresses of a dummy device and verify
that ifa_index restricts the dump to that device, that the all-hosts
address joined on link up is listed without IFA_F_GLOBAL, that an
address added with SIOCADDMULTI is listed with IFA_F_GLOBAL and
IFA_MC_USERS, and that IFA_TARGET_NETNSID dumps another netns.

Signed-off-by: Yuyang Huang <sigefriedhyy@gmail.com>
Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
---
 tools/testing/selftests/net/rtnetlink.py | 73 +++++++++++++++++++++++-
 1 file changed, 71 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/rtnetlink.py b/tools/testing/selftests/net/rtnetlink.py
index dc8c77db4897..5534ade056a5 100755
--- a/tools/testing/selftests/net/rtnetlink.py
+++ b/tools/testing/selftests/net/rtnetlink.py
@@ -5,13 +5,18 @@ import socket
 import struct
 import time
 from lib.py import bkg, ip, ksft_exit, ksft_run, ksft_eq, ksft_ge, ksft_true, KsftSkipEx
-from lib.py import ksft_not_in, ksft_not_none
+from lib.py import ksft_in, ksft_not_in, ksft_not_none
 from lib.py import CmdExitFailure, NetNS, NetNSEnter, RtnlAddrFamily, RtnlRouteFamily
 from lib.py import defer
 
 IPV4_ALL_HOSTS_MULTICAST = b'\xe0\x00\x00\x01'
 IPV4_TEST_MULTICAST = b'\xef\x01\x01\x01'
 IPV6_TEST_MULTICAST = bytes.fromhex('ff020000000000000000000000000123')
+ETH_ALL_HOSTS_MULTICAST = bytes.fromhex('01005e000001')
+ETH_TEST_MULTICAST_STR = '01:00:5e:01:01:01'
+ETH_TEST_MULTICAST = bytes.fromhex(ETH_TEST_MULTICAST_STR.replace(':', ''))
+ETH_PEER_MULTICAST_STR = '01:00:5e:02:02:02'
+ETH_PEER_MULTICAST = bytes.fromhex(ETH_PEER_MULTICAST_STR.replace(':', ''))
 
 
 def _users_for(rtnl: RtnlAddrFamily, family: int, grp: bytes, ifindex: int):
@@ -105,6 +110,69 @@ def dump_mcaddr6_check() -> None:
                 s2.close()
 
 
+def dump_mcaddr_l2_check() -> None:
+    """
+    Verify link-layer multicast addresses in an AF_PACKET RTM_GETMULTICAST
+    dump: the ifa-index filter, mc-users, the global flag and
+    target-netnsid.
+    """
+
+    with NetNS() as ns, NetNSEnter(str(ns)):
+        for ifname in ("dummy1", "dummy2"):
+            ip(f"link add name {ifname} type dummy")
+            ip(f"link set {ifname} up")
+        dev_idx = socket.if_nametoindex("dummy1")
+        ip(f"maddr add {ETH_TEST_MULTICAST_STR} dev dummy1")
+
+        rtnl = RtnlAddrFamily()
+        defer(rtnl.close)
+        addresses = rtnl.getmulticast(
+            {"ifa-family": socket.AF_PACKET, "ifa-index": dev_idx},
+            dump=True)
+
+        # dummy2 has entries as well, only dummy1 may be listed
+        ksft_eq({addr['ifa-index'] for addr in addresses}, {dev_idx},
+                "AF_PACKET multicast dump ignored ifa-index filter")
+
+        entries = {addr['multicast']: addr for addr in addresses}
+
+        # Bringing an Ethernet device up joins 224.0.0.1, which maps
+        # to 01:00:5e:00:00:01 in the device multicast list.
+        all_hosts = entries.get(ETH_ALL_HOSTS_MULTICAST)
+        ksft_not_none(all_hosts,
+                      "dummy1 does not have the all-hosts link-layer address")
+        if all_hosts is not None:
+            ksft_not_in('global', all_hosts['flags'],
+                        "protocol entry is global")
+
+        static = entries.get(ETH_TEST_MULTICAST)
+        ksft_not_none(static, "dummy1 does not have the SIOCADDMULTI address")
+        if static is not None:
+            ksft_eq(static['mc-users'], 1,
+                    "unexpected mc-users for the SIOCADDMULTI address")
+            ksft_in('global', static['flags'],
+                    "SIOCADDMULTI entry is not global")
+
+        # target-netnsid dumps another netns, ifa-index is relative to it
+        with NetNS() as peer:
+            ip(f"netns set {peer} 5")
+            ip("link add name dummy3 type dummy", ns=peer)
+            ip("link set dummy3 up", ns=peer)
+            ip(f"maddr add {ETH_PEER_MULTICAST_STR} dev dummy3", ns=peer)
+            peer_idx = ip("link show dummy3", json=True, ns=peer)[0]['ifindex']
+
+            addresses = rtnl.getmulticast(
+                {"ifa-family": socket.AF_PACKET, "target-netnsid": 5,
+                 "ifa-index": peer_idx}, dump=True)
+            ksft_eq({(addr['ifa-index'], addr['target-netnsid'])
+                     for addr in addresses}, {(peer_idx, 5)},
+                    "target-netnsid did not dump the peer netns")
+            # dummy1 in this netns can have the same ifindex as dummy3
+            ksft_in(ETH_PEER_MULTICAST,
+                    {addr['multicast'] for addr in addresses},
+                    "target-netnsid did not dump the peer device")
+
+
 def ipv4_devconf_notify() -> None:
     """
     Configure an interface and set ipv4-devconf values through netlink
@@ -424,7 +492,8 @@ def ipv6_verify_inter_scope_addr_order() -> None:
 
 
 def main() -> None:
-    ksft_run([dump_mcaddr_check, dump_mcaddr6_check, ipv4_devconf_notify,
+    ksft_run([dump_mcaddr_check, dump_mcaddr6_check, dump_mcaddr_l2_check,
+              ipv4_devconf_notify,
               ipv6_route_del_reason_expired,
               ipv6_route_del_reason_ra_withdrawn,
               ipv6_route_del_reason_absent,
-- 
2.43.0