netdev - [PATCH net-next 2/4] selftests: fcnal: Test SO

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Message-ID: <ac92940c6d2c17c7c8d476428cfa94c4ffa6bd8b.1683626501.git.gnault@redhat.com>
Date: Tue, 9 May 2023 14:02:37 +0200
From: Guillaume Nault <gnault@...hat.com>
To: David Miller <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>, Eric Dumazet <edumazet@...gle.com>
Cc: netdev@...r.kernel.org, David Ahern <dsahern@...nel.org>
Subject: [PATCH net-next 2/4] selftests: fcnal: Test SO_DONTROUTE on TCP
 sockets.

Use nettest -G to test the kernel behaviour with TCP sockets having the
SO_DONTROUTE option. Sending packets to a neighbour (on link) host,
should work. When the host is behind a router, sending should fail.

Client and server sockets are tested independently, so that we can
cover different TCP kernel paths.

SO_DONTROUTE also affects the syncookies path. So ipv4_tcp_dontroute()
is made to work with or without syncookies, to cover both paths.

Signed-off-by: Guillaume Nault <gnault@...hat.com>
---
 tools/testing/selftests/net/fcnal-test.sh | 70 +++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/tools/testing/selftests/net/fcnal-test.sh b/tools/testing/selftests/net/fcnal-test.sh
index 21ca91473c09..1f8939fbb021 100755
--- a/tools/testing/selftests/net/fcnal-test.sh
+++ b/tools/testing/selftests/net/fcnal-test.sh
@@ -1098,6 +1098,73 @@ test_ipv4_md5_vrf__global_server__bind_ifindex0()
 	set_sysctl net.ipv4.tcp_l3mdev_accept="$old_tcp_l3mdev_accept"
 }
 
+ipv4_tcp_dontroute()
+{
+	local syncookies=$1
+	local nsa_syncookies
+	local nsb_syncookies
+	local a
+
+	#
+	# Link local connection tests (SO_DONTROUTE).
+	# Connections should succeed only when the remote IP address is
+	# on link (doesn't need to be routed through a gateway).
+	#
+
+	nsa_syncookies=$(ip netns exec "${NSA}" sysctl -n net.ipv4.tcp_syncookies)
+	nsb_syncookies=$(ip netns exec "${NSB}" sysctl -n net.ipv4.tcp_syncookies)
+	ip netns exec "${NSA}" sysctl -wq net.ipv4.tcp_syncookies=${syncookies}
+	ip netns exec "${NSB}" sysctl -wq net.ipv4.tcp_syncookies=${syncookies}
+
+	# Test with eth1 address (on link).
+
+	a=${NSB_IP}
+	log_start
+	run_cmd_nsb nettest -s &
+	sleep 1
+	run_cmd nettest -r ${a} -G
+	log_test_addr ${a} $? 0 "SO_DONTROUTE client, syncookies=${syncookies}"
+
+	a=${NSB_IP}
+	log_start
+	# Ensure previous nettest server exited, so that it won't respond (we
+	# really want to test the -G option on the server).
+	wait
+	run_cmd_nsb nettest -s -G &
+	sleep 1
+	run_cmd nettest -r ${a}
+	log_test_addr ${a} $? 0 "SO_DONTROUTE server, syncookies=${syncookies}"
+
+	# Test with loopback address (routed).
+	#
+	# The client would use the eth1 address as source IP by default.
+	# Therefore, we need to use the -c option here, to force the use of the
+	# routed (loopback) address as source IP (so that the server will try
+	# to respond to a routed address and not a link local one).
+
+	a=${NSB_LO_IP}
+	log_start
+	show_hint "Should fail 'Network is unreachable' since server is not on link"
+	run_cmd_nsb nettest -s &
+	sleep 1
+	run_cmd nettest -c ${NSA_LO_IP} -r ${a} -G
+	log_test_addr ${a} $? 1 "SO_DONTROUTE client, syncookies=${syncookies}"
+
+	a=${NSB_LO_IP}
+	log_start
+	show_hint "Should timeout since server cannot respond (client is not on link)"
+	# Ensure previous nettest server exited, so that it won't respond (we
+	# really want to test the -G option on the server).
+	wait
+	run_cmd_nsb nettest -s -G &
+	sleep 1
+	run_cmd nettest -c ${NSA_LO_IP} -r ${a}
+	log_test_addr ${a} $? 2 "SO_DONTROUTE server, syncookies=${syncookies}"
+
+	ip netns exec "${NSB}" sysctl -wq net.ipv4.tcp_syncookies=${nsb_syncookies}
+	ip netns exec "${NSA}" sysctl -wq net.ipv4.tcp_syncookies=${nsa_syncookies}
+}
+
 ipv4_tcp_novrf()
 {
 	local a
@@ -1217,6 +1284,9 @@ ipv4_tcp_novrf()
 	log_test_addr ${a} $? 1 "No server, device client, local conn"
 
 	ipv4_tcp_md5_novrf
+
+	ipv4_tcp_dontroute 0
+	ipv4_tcp_dontroute 2
 }
 
 ipv4_tcp_vrf()
-- 
2.30.2