selftests/bonding: add a test for bonding lladdr target

This is a regression test for commit 592335a4164c ("bonding: accept
unsolicited NA message") and commit b7f14132bf58 ("bonding: use unspecified
address if no available link local address"). When the bond interface
up and no available link local address, unspecified address(::) is used to
send the NS message. The unsolicited NA message should also be accepted
for validation.

Signed-off-by: Hangbin Liu <[e-mail]>
Acked-by: Jonathan Toppins <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

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

···
 # Makefile for net selftests
 
 TEST_PROGS := bond-break-lacpdu-tx.sh
+TEST_PROGS += bond-lladdr-target.sh
 
 include ../../../lib.mk

tools/testing/selftests/drivers/net/bonding/bond-lladdr-target.sh

···
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# Regression Test:
+#   Verify bond interface could up when set IPv6 link local address target.
+#
+#  +----------------+
+#  |      br0       |
+#  |       |        |    sw
+#  | veth0   veth1  |
+#  +---+-------+----+
+#      |       |
+#  +---+-------+----+
+#  | veth0   veth1  |
+#  |       |        |    host
+#  |     bond0      |
+#  +----------------+
+#
+# We use veths instead of physical interfaces
+sw="sw-$(mktemp -u XXXXXX)"
+host="ns-$(mktemp -u XXXXXX)"
+
+cleanup()
+{
+	ip netns del $sw
+	ip netns del $host
+}
+
+trap cleanup 0 1 2
+
+ip netns add $sw
+ip netns add $host
+
+ip -n $host link add veth0 type veth peer name veth0 netns $sw
+ip -n $host link add veth1 type veth peer name veth1 netns $sw
+
+ip -n $sw link add br0 type bridge
+ip -n $sw link set br0 up
+sw_lladdr=$(ip -n $sw addr show br0 | awk '/fe80/{print $2}' | cut -d'/' -f1)
+# sleep some time to make sure bridge lladdr pass DAD
+sleep 2
+
+ip -n $host link add bond0 type bond mode 1 ns_ip6_target ${sw_lladdr} \
+	arp_validate 3 arp_interval 1000
+# add a lladdr for bond to make sure there is a route to target
+ip -n $host addr add fe80::beef/64 dev bond0
+ip -n $host link set bond0 up
+ip -n $host link set veth0 master bond0
+ip -n $host link set veth1 master bond0
+
+ip -n $sw link set veth0 master br0
+ip -n $sw link set veth1 master br0
+ip -n $sw link set veth0 up
+ip -n $sw link set veth1 up
+
+sleep 5
+
+rc=0
+if ip -n $host link show bond0 | grep -q LOWER_UP; then
+	echo "PASS"
+else
+	echo "FAIL"
+	rc=1
+fi
+exit $rc