selftests: bonding: add tests for ether type changes

Add new network selftests for the bonding device which exercise the ether
type changing call paths. They also test for the recent syzbot bug[1] which
causes a warning and results in wrong device flags (IFF_SLAVE missing).
The test adds three bond devices and a nlmon device, enslaves one of the
bond devices to the other and then uses the nlmon device for successful
and unsuccesful enslaves both of which change the bond ether type. Thus
we can test for both MASTER and SLAVE flags at the same time.

If the flags are properly restored we get:
TEST: Change ether type of an enslaved bond device with unsuccessful enslave   [ OK ]
TEST: Change ether type of an enslaved bond device with successful enslave   [ OK ]

[1] https://syzkaller.appspot.com/bug?id=391c7b1f6522182899efba27d891f1743e8eb3ef

Signed-off-by: Nikolay Aleksandrov <[email protected]>
Reviewed-by: Michal Kubiak <[email protected]>
Acked-by: Jonathan Toppins <[email protected]>
Acked-by: Jay Vosburgh <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

tools/testing/selftests/drivers/net/bonding/Makefile

@@ -8,7 +8,8 @@ TEST_PROGS := \
 	dev_addr_lists.sh \
 	mode-1-recovery-updelay.sh \
 	mode-2-recovery-updelay.sh \
-	option_prio.sh
+	option_prio.sh \
+	bond-eth-type-change.sh
 
 TEST_FILES := \
 	lag_lib.sh \

tools/testing/selftests/drivers/net/bonding/bond-eth-type-change.sh

@@ -0,0 +1,85 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Test bond device ether type changing
+#
+
+ALL_TESTS="
+	bond_test_unsuccessful_enslave_type_change
+	bond_test_successful_enslave_type_change
+"
+REQUIRE_MZ=no
+NUM_NETIFS=0
+lib_dir=$(dirname "$0")
+source "$lib_dir"/net_forwarding_lib.sh
+
+bond_check_flags()
+{
+	local bonddev=$1
+
+	ip -d l sh dev "$bonddev" | grep -q "MASTER"
+	check_err $? "MASTER flag is missing from the bond device"
+
+	ip -d l sh dev "$bonddev" | grep -q "SLAVE"
+	check_err $? "SLAVE flag is missing from the bond device"
+}
+
+# test enslaved bond dev type change from ARPHRD_ETHER and back
+# this allows us to test both MASTER and SLAVE flags at once
+bond_test_enslave_type_change()
+{
+	local test_success=$1
+	local devbond0="test-bond0"
+	local devbond1="test-bond1"
+	local devbond2="test-bond2"
+	local nonethdev="test-noneth0"
+
+	# create a non-ARPHRD_ETHER device for testing (e.g. nlmon type)
+	ip link add name "$nonethdev" type nlmon
+	check_err $? "could not create a non-ARPHRD_ETHER device (nlmon)"
+	ip link add name "$devbond0" type bond
+	if [ $test_success -eq 1 ]; then
+		# we need devbond0 in active-backup mode to successfully enslave nonethdev
+		ip link set dev "$devbond0" type bond mode active-backup
+		check_err $? "could not change bond mode to active-backup"
+	fi
+	ip link add name "$devbond1" type bond
+	ip link add name "$devbond2" type bond
+	ip link set dev "$devbond0" master "$devbond1"
+	check_err $? "could not enslave $devbond0 to $devbond1"
+	# change bond type to non-ARPHRD_ETHER
+	ip link set dev "$nonethdev" master "$devbond0" 1>/dev/null 2>/dev/null
+	ip link set dev "$nonethdev" nomaster 1>/dev/null 2>/dev/null
+	# restore ARPHRD_ETHER type by enslaving such device
+	ip link set dev "$devbond2" master "$devbond0"
+	check_err $? "could not enslave $devbond2 to $devbond0"
+	ip link set dev "$devbond1" nomaster
+
+	bond_check_flags "$devbond0"
+
+	# clean up
+	ip link del dev "$devbond0"
+	ip link del dev "$devbond1"
+	ip link del dev "$devbond2"
+	ip link del dev "$nonethdev"
+}
+
+bond_test_unsuccessful_enslave_type_change()
+{
+	RET=0
+
+	bond_test_enslave_type_change 0
+	log_test "Change ether type of an enslaved bond device with unsuccessful enslave"
+}
+
+bond_test_successful_enslave_type_change()
+{
+	RET=0
+
+	bond_test_enslave_type_change 1
+	log_test "Change ether type of an enslaved bond device with successful enslave"
+}
+
+tests_run
+
+exit "$EXIT_STATUS"