get_interfaces: don't exclude bridge and bond members

The change that introduced this issue was handling interfaces that are
bonded in the kernel, in a way that doesn't present as "a bond" to
userspace in the normal way.  Both members of this "bond" will share a
MAC address, so we filter one of them out to avoid incorrect MAC address
collision warnings.

Unfortunately, the matching condition was too broad, so that change also
affected normal bonds and bridges.  This change specifically excludes
bonds and bridges from that determination, to address that regression.

LP: #1846535

2 files changed, 73 insertions, 10 deletions

diff --git a/cloudinit/net/__init__.py b/cloudinit/net/__init__.py
index 5de5c6de..307da780 100644
--- a/cloudinit/net/__init__.py
+++ b/cloudinit/net/__init__.py
@@ -109,8 +109,22 @@ def is_bond(devname):
     return os.path.exists(sys_dev_path(devname, "bonding"))
 
 
-def has_master(devname):
-    return os.path.exists(sys_dev_path(devname, path="master"))
+def get_master(devname):
+    """Return the master path for devname, or None if no master"""
+    path = sys_dev_path(devname, path="master")
+    if os.path.exists(path):
+        return path
+    return None
+
+
+def master_is_bridge_or_bond(devname):
+    """Return a bool indicating if devname's master is a bridge or bond"""
+    master_path = get_master(devname)
+    if master_path is None:
+        return False
+    bonding_path = os.path.join(master_path, "bonding")
+    bridge_path = os.path.join(master_path, "bridge")
+    return (os.path.exists(bonding_path) or os.path.exists(bridge_path))
 
 
 def is_netfailover(devname, driver=None):
@@ -158,7 +172,7 @@ def is_netfail_master(devname, driver=None):
 
         Return True if all of the above is True.
     """
-    if has_master(devname):
+    if get_master(devname) is not None:
         return False
 
     if driver is None:
@@ -215,7 +229,7 @@ def is_netfail_standby(devname, driver=None):
 
         Return True if all of the above is True.
     """
-    if not has_master(devname):
+    if get_master(devname) is None:
         return False
 
     if driver is None:
@@ -790,7 +804,7 @@ def get_interfaces():
             continue
         if is_bond(name):
             continue
-        if has_master(name):
+        if get_master(name) is not None and not master_is_bridge_or_bond(name):
             continue
         if is_netfailover(name):
             continue
diff --git a/cloudinit/net/tests/test_init.py b/cloudinit/net/tests/test_init.py
index 999db986..6db93e26 100644
--- a/cloudinit/net/tests/test_init.py
+++ b/cloudinit/net/tests/test_init.py
@@ -157,11 +157,40 @@ class TestReadSysNet(CiTestCase):
         ensure_file(os.path.join(self.sysdir, 'eth0', 'bonding'))
         self.assertTrue(net.is_bond('eth0'))
 
-    def test_has_master(self):
-        """has_master is True when /sys/net/devname/master exists."""
-        self.assertFalse(net.has_master('enP1s1'))
-        ensure_file(os.path.join(self.sysdir, 'enP1s1', 'master'))
-        self.assertTrue(net.has_master('enP1s1'))
+    def test_get_master(self):
+        """get_master returns the path when /sys/net/devname/master exists."""
+        self.assertIsNone(net.get_master('enP1s1'))
+        master_path = os.path.join(self.sysdir, 'enP1s1', 'master')
+        ensure_file(master_path)
+        self.assertEqual(master_path, net.get_master('enP1s1'))
+
+    def test_master_is_bridge_or_bond(self):
+        bridge_mac = 'aa:bb:cc:aa:bb:cc'
+        bond_mac = 'cc:bb:aa:cc:bb:aa'
+
+        # No master => False
+        write_file(os.path.join(self.sysdir, 'eth1', 'address'), bridge_mac)
+        write_file(os.path.join(self.sysdir, 'eth2', 'address'), bond_mac)
+
+        self.assertFalse(net.master_is_bridge_or_bond('eth1'))
+        self.assertFalse(net.master_is_bridge_or_bond('eth2'))
+
+        # masters without bridge/bonding => False
+        write_file(os.path.join(self.sysdir, 'br0', 'address'), bridge_mac)
+        write_file(os.path.join(self.sysdir, 'bond0', 'address'), bond_mac)
+
+        os.symlink('../br0', os.path.join(self.sysdir, 'eth1', 'master'))
+        os.symlink('../bond0', os.path.join(self.sysdir, 'eth2', 'master'))
+
+        self.assertFalse(net.master_is_bridge_or_bond('eth1'))
+        self.assertFalse(net.master_is_bridge_or_bond('eth2'))
+
+        # masters with bridge/bonding => True
+        write_file(os.path.join(self.sysdir, 'br0', 'bridge'), '')
+        write_file(os.path.join(self.sysdir, 'bond0', 'bonding'), '')
+
+        self.assertTrue(net.master_is_bridge_or_bond('eth1'))
+        self.assertTrue(net.master_is_bridge_or_bond('eth2'))
 
     def test_is_vlan(self):
         """is_vlan is True when /sys/net/devname/uevent has DEVTYPE=vlan."""
@@ -461,6 +490,26 @@ class TestGetInterfaceMAC(CiTestCase):
         expected = [('ens3', mac, None, None)]
         self.assertEqual(expected, net.get_interfaces())
 
+    def test_get_interfaces_does_not_skip_phys_members_of_bridges_and_bonds(
+        self
+    ):
+        bridge_mac = 'aa:bb:cc:aa:bb:cc'
+        bond_mac = 'cc:bb:aa:cc:bb:aa'
+        write_file(os.path.join(self.sysdir, 'br0', 'address'), bridge_mac)
+        write_file(os.path.join(self.sysdir, 'br0', 'bridge'), '')
+
+        write_file(os.path.join(self.sysdir, 'bond0', 'address'), bond_mac)
+        write_file(os.path.join(self.sysdir, 'bond0', 'bonding'), '')
+
+        write_file(os.path.join(self.sysdir, 'eth1', 'address'), bridge_mac)
+        os.symlink('../br0', os.path.join(self.sysdir, 'eth1', 'master'))
+
+        write_file(os.path.join(self.sysdir, 'eth2', 'address'), bond_mac)
+        os.symlink('../bond0', os.path.join(self.sysdir, 'eth2', 'master'))
+
+        interface_names = [interface[0] for interface in net.get_interfaces()]
+        self.assertEqual(['eth1', 'eth2'], sorted(interface_names))
+
 
 class TestInterfaceHasOwnMAC(CiTestCase):