1 files changed, 47 insertions, 0 deletions
diff --git a/tools/testing/selftests/net/broadcast_pmtu.sh b/tools/testing/selftests/net/broadcast_pmtu.sh
new file mode 100755
index 000000000000..726eb5d25839
--- /dev/null
+++ b/tools/testing/selftests/net/broadcast_pmtu.sh
@@ -0,0 +1,47 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Ensures broadcast route MTU is respected
+
+CLIENT_NS=$(mktemp -u client-XXXXXXXX)
+CLIENT_IP4="192.168.0.1/24"
+CLIENT_BROADCAST_ADDRESS="192.168.0.255"
+
+SERVER_NS=$(mktemp -u server-XXXXXXXX)
+SERVER_IP4="192.168.0.2/24"
+
+setup() {
+	ip netns add "${CLIENT_NS}"
+	ip netns add "${SERVER_NS}"
+
+	ip -net "${SERVER_NS}" link add link1 type veth peer name link0 netns "${CLIENT_NS}"
+
+	ip -net "${CLIENT_NS}" link set link0 up
+	ip -net "${CLIENT_NS}" link set link0 mtu 9000
+	ip -net "${CLIENT_NS}" addr add "${CLIENT_IP4}" dev link0
+
+	ip -net "${SERVER_NS}" link set link1 up
+	ip -net "${SERVER_NS}" link set link1 mtu 1500
+	ip -net "${SERVER_NS}" addr add "${SERVER_IP4}" dev link1
+
+	read -r -a CLIENT_BROADCAST_ENTRY <<< "$(ip -net "${CLIENT_NS}" route show table local type broadcast)"
+	ip -net "${CLIENT_NS}" route del "${CLIENT_BROADCAST_ENTRY[@]}"
+	ip -net "${CLIENT_NS}" route add "${CLIENT_BROADCAST_ENTRY[@]}" mtu 1500
+
+	ip net exec "${SERVER_NS}" sysctl -wq net.ipv4.icmp_echo_ignore_broadcasts=0
+}
+
+cleanup() {
+	ip -net "${SERVER_NS}" link del link1
+	ip netns del "${CLIENT_NS}"
+	ip netns del "${SERVER_NS}"
+}
+
+trap cleanup EXIT
+
+setup &&
+	echo "Testing for broadcast route MTU" &&
+	ip net exec "${CLIENT_NS}" ping -f -M want -q -c 1 -s 8000 -w 1 -b "${CLIENT_BROADCAST_ADDRESS}" > /dev/null 2>&1
+
+exit $?
+