Added the test cases for MP_FAIL, use 'tc' commands to trigger the
checksum failures.

Suggested-by: Davide Caratti <dcaratti@redhat.com>
Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
---
 v10:
 - enable check_invert
 - use ip mptcp wrappers
---
 tools/testing/selftests/net/mptcp/config      |   5 +
 .../testing/selftests/net/mptcp/mptcp_join.sh | 112 ++++++++++++++++--
 2 files changed, 108 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/config b/tools/testing/selftests/net/mptcp/config
index d36b7da5082a..26955abe49f0 100644
--- a/tools/testing/selftests/net/mptcp/config
+++ b/tools/testing/selftests/net/mptcp/config
@@ -19,3 +19,8 @@ CONFIG_IP_ADVANCED_ROUTER=y
 CONFIG_IP_MULTIPLE_TABLES=y
 CONFIG_IP_NF_TARGET_REJECT=m
 CONFIG_IPV6_MULTIPLE_TABLES=y
+CONFIG_NET_ACT_CSUM=m
+CONFIG_NET_ACT_PEDIT=m
+CONFIG_NET_CLS_ACT=y
+CONFIG_NET_CLS_FLOWER=m
+CONFIG_NET_SCH_INGRESS=m
diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 76c45c845d3b..32e17c9e2e2c 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -17,6 +17,8 @@ capture=0
 checksum=0
 ip_mptcp=0
 check_invert=0
+validate_checksum=0
+nr_fail=0
 do_all_tests=1
 
 TEST_COUNT=0
@@ -61,6 +63,7 @@ init()
 	done
 
 	check_invert=0
+	validate_checksum=$checksum
 
 	#  ns1              ns2
 	# ns1eth1    ns2eth1
@@ -166,6 +169,46 @@ reset_with_allow_join_id0()
 	ip netns exec $ns2 sysctl -q net.mptcp.allow_join_initial_addr_port=$ns2_enable
 }
 
+# Modify TCP payload without corrupting the TCP packet
+#
+# This rule inverts a 32-bit word at byte offset 148 for all TCP ACK
+# packets carrying enough data.
+# Once it is done, the TCP Checksum field is updated so the packet
+# is still considered as valid at the TCP level.
+# But because the MPTCP checksum, covering the TCP options and data,
+# has not been updated, we will detect the modification and emit an
+# MP_FAIL: what we want to validate here.
+#
+# Please note that this rule will produce this pr_info() message for
+# each TCP ACK packets not carrying enough data:
+#
+#     tc action pedit offset 162 out of bounds
+#
+# But this should be limited to a very few numbers of packets as we
+# restrict this rule to outgoing TCP traffic with only the ACK flag
+# + except the 3rd ACK, only packets carrying data should be seen in
+# this direction.
+reset_with_fail()
+{
+	reset
+
+	ip netns exec $ns1 sysctl -q net.mptcp.checksum_enabled=1
+	ip netns exec $ns2 sysctl -q net.mptcp.checksum_enabled=1
+
+	check_invert=1
+	validate_checksum=1
+	nr_fail=0
+	i="$1"
+
+	tc -n $ns2 qdisc add dev ns2eth$i clsact
+	tc -n $ns2 filter add dev ns2eth$i egress \
+		protocol ip prio 1000 \
+		flower ip_proto tcp tcp_flags 0x10/0xff \
+		action pedit munge offset 148 u32 invert \
+		pipe csum tcp \
+		index 100
+}
+
 ip -Version > /dev/null 2>&1
 if [ $? -ne 0 ];then
 	echo "SKIP: Could not run test without ip tool"
@@ -184,6 +227,12 @@ if [ $? -ne 0 ];then
 	exit $ksft_skip
 fi
 
+jq -V > /dev/null 2>&1
+if [ $? -ne 0 ];then
+	echo "SKIP: Could not run all tests without jq tool"
+	exit $ksft_skip
+fi
+
 print_file_err()
 {
 	ls -l "$1" 1>&2
@@ -244,6 +293,21 @@ link_failure()
 	done
 }
 
+get_nr_fail()
+{
+	i="$1"
+
+	local action=$(tc -n $ns2 -j -s action show action pedit index 100)
+	local packets=$(echo $action | jq '.[1].actions[0].stats.packets')
+	local overlimits=$(echo $action | jq '.[1].actions[0].stats.overlimits')
+
+	let pkt=$packets-$overlimits
+	if [ $pkt -gt 0 ]; then
+		nr_fail=1
+	fi
+	tc -n $ns2 qdisc del dev ns2eth$i clsact
+}
+
 # $1: IP address
 is_v6()
 {
@@ -739,6 +803,8 @@ dump_stats()
 chk_csum_nr()
 {
 	local msg=${1:-""}
+	local csum_ns1=${2:-0}
+	local csum_ns2=${3:-0}
 	local count
 	local dump_stats
 
@@ -750,8 +816,8 @@ chk_csum_nr()
 	printf " %-36s %s" "$msg" "sum"
 	count=`ip netns exec $ns1 nstat -as | grep MPTcpExtDataCsumErr | awk '{print $2}'`
 	[ -z "$count" ] && count=0
-	if [ "$count" != 0 ]; then
-		echo "[fail] got $count data checksum error[s] expected 0"
+	if [ "$count" != $csum_ns1 ]; then
+		echo "[fail] got $count data checksum error[s] expected $csum_ns1"
 		ret=1
 		dump_stats=1
 	else
@@ -760,8 +826,8 @@ chk_csum_nr()
 	echo -n " - csum  "
 	count=`ip netns exec $ns2 nstat -as | grep MPTcpExtDataCsumErr | awk '{print $2}'`
 	[ -z "$count" ] && count=0
-	if [ "$count" != 0 ]; then
-		echo "[fail] got $count data checksum error[s] expected 0"
+	if [ "$count" != $csum_ns2 ]; then
+		echo "[fail] got $count data checksum error[s] expected $csum_ns2"
 		ret=1
 		dump_stats=1
 	else
@@ -840,6 +906,8 @@ chk_join_nr()
 	local syn_nr=$2
 	local syn_ack_nr=$3
 	local ack_nr=$4
+	local fail_nr=${5:-0}
+	local infi_nr=${6:-0}
 	local count
 	local dump_stats
 
@@ -876,10 +944,10 @@ chk_join_nr()
 		echo "[ ok ]"
 	fi
 	[ "${dump_stats}" = 1 ] && dump_stats
-	if [ $checksum -eq 1 ]; then
-		chk_csum_nr
-		chk_fail_nr 0 0
-		chk_infi_nr 0 0
+	if [ $validate_checksum -eq 1 ]; then
+		chk_csum_nr "" $fail_nr
+		chk_fail_nr $fail_nr $fail_nr
+		chk_infi_nr $infi_nr $infi_nr
 	fi
 }
 
@@ -2183,6 +2251,27 @@ userspace_tests()
 	chk_rm_nr 0 0
 }
 
+fail_tests()
+{
+	# multiple subflows
+	reset_with_fail 2
+	pm_nl_set_limits $ns1 0 2
+	pm_nl_set_limits $ns2 0 2
+	pm_nl_add_endpoint $ns2 10.0.2.2 dev ns2eth2 flags subflow
+	pm_nl_add_endpoint $ns2 10.0.3.2 dev ns2eth3 flags subflow
+	run_tests $ns1 $ns2 10.0.1.1 2
+	get_nr_fail 2
+	chk_join_nr "$nr_fail MP_FAIL, multiple subflows" 2 2 2 $nr_fail
+
+	# single subflow
+	reset_with_fail 1
+	pm_nl_set_limits $ns1 0 2
+	pm_nl_set_limits $ns2 0 2
+	run_tests $ns1 $ns2 10.0.1.1 1
+	get_nr_fail 1
+	chk_join_nr "$nr_fail MP_FAIL, single subflow" 0 0 0 $nr_fail $nr_fail
+}
+
 all_tests()
 {
 	subflows_tests
@@ -2201,6 +2290,7 @@ all_tests()
 	deny_join_id0_tests
 	fullmesh_tests
 	userspace_tests
+	fail_tests
 }
 
 usage()
@@ -2222,6 +2312,7 @@ usage()
 	echo "  -d deny_join_id0_tests"
 	echo "  -m fullmesh_tests"
 	echo "  -u userspace_tests"
+	echo "  -F fail_tests"
 	echo "  -c capture pcap files"
 	echo "  -C enable data checksum"
 	echo "  -i use ip mptcp"
@@ -2261,7 +2352,7 @@ if [ $do_all_tests -eq 1 ]; then
 	exit $ret
 fi
 
-while getopts 'fesltra64bpkdmuchCSi' opt; do
+while getopts 'fesltra64bpkdmuchCSFi' opt; do
 	case $opt in
 		f)
 			subflows_tests
@@ -2311,6 +2402,9 @@ while getopts 'fesltra64bpkdmuchCSi' opt; do
 		u)
 			userspace_tests
 			;;
+		F)
+			fail_tests
+			;;
 		c)
 			;;
 		C)
-- 
2.31.1