selftests/net: add ip_defrag selftest

This test creates a raw IPv4 socket, fragments a largish UDP
datagram and sends the fragments out of order.

Then repeats in a loop with different message and fragment lengths.

Then does the same with overlapping fragments (with overlapping
fragments the expectation is that the recv times out).

Tested:

root@<host># time ./ip_defrag.sh
ipv4 defrag
PASS
ipv4 defrag with overlaps
PASS

real    1m7.679s
user    0m0.628s
sys     0m2.242s

A similar test for IPv6 is to follow.

Signed-off-by: Peter Oskolkov <posk@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 28 insertions, 0 deletions

diff --git a/tools/testing/selftests/net/ip_defrag.sh b/tools/testing/selftests/net/ip_defrag.sh
new file mode 100755
index 000000000000..78743adcca9e
--- /dev/null
+++ b/tools/testing/selftests/net/ip_defrag.sh
@@ -0,0 +1,28 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# Run a couple of IP defragmentation tests.
+
+set +x
+set -e
+
+echo "ipv4 defrag"
+
+run_v4() {
+sysctl -w net.ipv4.ipfrag_high_thresh=9000000 &> /dev/null
+sysctl -w net.ipv4.ipfrag_low_thresh=7000000 &> /dev/null
+./ip_defrag -4
+}
+export -f run_v4
+
+./in_netns.sh "run_v4"
+
+echo "ipv4 defrag with overlaps"
+run_v4o() {
+sysctl -w net.ipv4.ipfrag_high_thresh=9000000 &> /dev/null
+sysctl -w net.ipv4.ipfrag_low_thresh=7000000 &> /dev/null
+./ip_defrag -4o
+}
+export -f run_v4o
+
+./in_netns.sh "run_v4o"