test-network: add test for sysctl watch

Add a NetworkdSysctlTest class which ensures that networkd correctly
complains when a sysctl file it's handling has been changed externally.

diff --git a/test/test-network/systemd-networkd-tests.py b/test/test-network/systemd-networkd-tests.py
index a596537ffaeafb9a0c14360a2ec309d88a0aa411..687fda7b3d8450ff8475f169c8550f3b792e94b8 100755 (executable)
--- a/test/test-network/systemd-networkd-tests.py
+++ b/test/test-network/systemd-networkd-tests.py
@@ -8034,6 +8034,38 @@ class NetworkdMTUTests(unittest.TestCase, Utilities):
         copy_network_unit('12-dummy.netdev', '12-dummy-mtu.link', '12-dummy.network.d/ipv6-mtu-1550.conf')
         self.check_mtu('1600', '1550', reset=False)
 
+class NetworkdSysctlTest(unittest.TestCase, Utilities):
+
+    def setUp(self):
+        setup_common()
+
+    def tearDown(self):
+        tear_down_common()
+
+    @unittest.skipUnless(compare_kernel_version("6.12"), reason="On kernels <= 6.12, bpf_current_task_under_cgroup() isn't available for program types BPF_PROG_TYPE_CGROUP_SYSCTL")
+    def check_sysctl_watch(self):
+        copy_network_unit('12-dummy.network', '12-dummy.netdev', '12-dummy.link')
+        start_networkd()
+
+        self.wait_online('dummy98:routable')
+
+        # Change managed sysctls
+        call('sysctl -w net.ipv6.conf.dummy98.accept_ra=1')
+        call('sysctl -w net.ipv6.conf.dummy98.mtu=1360')
+        call('sysctl -w net.ipv4.conf.dummy98.promote_secondaries=0')
+        call('sysctl -w net.ipv6.conf.dummy98.proxy_ndp=1')
+
+        # And unmanaged ones
+        call('sysctl -w net.ipv6.conf.dummy98.hop_limit=4')
+        call('sysctl -w net.ipv6.conf.dummy98.max_addresses=10')
+
+        log=read_networkd_log()
+        self.assertRegex(log, r"Foreign process 'sysctl\[\d+\]' changed sysctl '/proc/sys/net/ipv6/conf/dummy98/accept_ra' from '0' to '1', conflicting with our setting to '0'")
+        self.assertRegex(log, r"Foreign process 'sysctl\[\d+\]' changed sysctl '/proc/sys/net/ipv6/conf/dummy98/mtu' from '1550' to '1360', conflicting with our setting to '1550'")
+        self.assertRegex(log, r"Foreign process 'sysctl\[\d+\]' changed sysctl '/proc/sys/net/ipv4/conf/dummy98/promote_secondaries' from '1' to '0', conflicting with our setting to '1'")
+        self.assertRegex(log, r"Foreign process 'sysctl\[\d+\]' changed sysctl '/proc/sys/net/ipv6/conf/dummy98/proxy_ndp' from '0' to '1', conflicting with our setting to '0'")
+        self.assertNotIn("changed sysctl '/proc/sys/net/ipv6/conf/dummy98/hop_limit'", log)
+        self.assertNotIn("changed sysctl '/proc/sys/net/ipv6/conf/dummy98/max_addresses'", log)
 
 if __name__ == '__main__':
     parser = argparse.ArgumentParser()