[PATCH RESEND mptcp-next v7 7/7] selftests: mptcp: add the MP_FAIL testcases

[Geliang Tang <geliang.tang@suse.com>]

Added the test cases for MP_FAIL, the multiple subflows test for the
MP_RST case and the single subflow one for the infinite mapping case.
The former used the test_linkfail value to make 1024KB test files,
and the latter 128KB.

Added a new function reset_with_fail(), in it use 'iptables' and 'tc
action pedit' rules to produce the bit flips to trigger the checksum
failures. Added a new function pedit_action_pkts() to get the numbers
of the packets edited by the tc pedit actions.

Added a new global variable validate_checksum to enable checksums for
the MP_FAIL tests without passing the '-C' argument.

Also added the needed kernel configures in the config file.

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>
---
 tools/testing/selftests/net/mptcp/config      |  8 ++
 .../testing/selftests/net/mptcp/mptcp_join.sh | 86 ++++++++++++++++++-
 2 files changed, 92 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/config b/tools/testing/selftests/net/mptcp/config
index d36b7da5082a..38021a0dd527 100644
--- a/tools/testing/selftests/net/mptcp/config
+++ b/tools/testing/selftests/net/mptcp/config
@@ -12,6 +12,9 @@ CONFIG_NF_TABLES=m
 CONFIG_NFT_COMPAT=m
 CONFIG_NETFILTER_XTABLES=m
 CONFIG_NETFILTER_XT_MATCH_BPF=m
+CONFIG_NETFILTER_XT_MATCH_LENGTH=m
+CONFIG_NETFILTER_XT_MATCH_STATISTIC=m
+CONFIG_NETFILTER_XT_TARGET_MARK=m
 CONFIG_NF_TABLES_INET=y
 CONFIG_NFT_TPROXY=m
 CONFIG_NFT_SOCKET=m
@@ -19,3 +22,8 @@ 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_FW=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 21add441c08a..bfe2349794fc 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -17,6 +17,7 @@ capture=0
 checksum=0
 ip_mptcp=0
 check_invert=0
+validate_checksum=0
 do_all_tests=1
 
 TEST_COUNT=0
@@ -62,6 +63,7 @@ init()
 	done
 
 	check_invert=0
+	validate_checksum=$checksum
 
 	#  ns1              ns2
 	# ns1eth1    ns2eth1
@@ -167,6 +169,58 @@ 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 8-bit word at byte offset 148 for the 2nd 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.
+# Because the MPTCP checksum, covering the TCP options and data, has not been
+# updated, the modification will be detected and an MP_FAIL will be emitted:
+# what we want to validate here without corrupting "random" MPTCP options.
+#
+# To avoid having tc producing this pr_info() message for each TCP ACK packets
+# not carrying enough data:
+#
+#     tc action pedit offset 162 out of bounds
+#
+# Netfilter is used to mark packets with enough data.
+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
+	local i="$1"
+	local ip="${2:-4}"
+	local tables
+
+	tables="iptables"
+	if [ $ip -eq 6 ]; then
+		tables="ip6tables"
+	fi
+
+	ip netns exec $ns2 $tables \
+		-t mangle \
+		-A OUTPUT \
+		-o ns2eth$i \
+		-p tcp \
+		-m length --length 150:9999 \
+		-m statistic --mode nth --packet 1 --every 99999 \
+		-j MARK --set-mark 42 || exit 1
+
+	tc -n $ns2 qdisc add dev ns2eth$i clsact || exit 1
+	tc -n $ns2 filter add dev ns2eth$i egress \
+		protocol ip prio 1000 \
+		handle 42 fw \
+		action pedit munge offset 148 u8 invert \
+		pipe csum tcp \
+		index 100 || exit 1
+}
+
 ip -Version > /dev/null 2>&1
 if [ $? -ne 0 ];then
 	echo "SKIP: Could not run test without ip tool"
@@ -920,7 +974,7 @@ chk_join_nr()
 		echo "[ ok ]"
 	fi
 	[ "${dump_stats}" = 1 ] && dump_stats
-	if [ $checksum -eq 1 ]; then
+	if [ $validate_checksum -eq 1 ]; then
 		chk_csum_nr "" $fail_nr
 		chk_fail_nr $fail_nr $fail_nr
 		chk_rst_nr $rst_nr $rst_nr
@@ -2239,6 +2293,29 @@ userspace_tests()
 	chk_rm_nr 0 0
 }
 
+pedit_action_pkts()
+{
+	tc -n $ns2 -j -s action show action pedit index 100 | \
+		sed 's/.*"packets":\([0-9]\+\),.*/\1/'
+}
+
+fail_tests()
+{
+	# multiple subflows
+	reset_with_fail 2
+	tc -n $ns2 qdisc add dev ns2eth1 root netem rate 20mbit delay 1
+	pm_nl_set_limits $ns1 0 1
+	pm_nl_set_limits $ns2 0 1
+	pm_nl_add_endpoint $ns2 10.0.2.2 dev ns2eth2 flags subflow
+	run_tests $ns1 $ns2 10.0.1.1 1024
+	chk_join_nr "MP_FAIL MP_RST: $(pedit_action_pkts) corrupted pkts" 1 1 1 1 1
+
+	# single subflow
+	reset_with_fail 1
+	run_tests $ns1 $ns2 10.0.1.1 128
+	chk_join_nr "Infinite map: $(pedit_action_pkts) corrupted pkts" 0 0 0 1 0 1
+}
+
 all_tests()
 {
 	subflows_tests
@@ -2257,6 +2334,7 @@ all_tests()
 	deny_join_id0_tests
 	fullmesh_tests
 	userspace_tests
+	fail_tests
 }
 
 usage()
@@ -2278,6 +2356,7 @@ 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"
@@ -2317,7 +2396,7 @@ 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
@@ -2367,6 +2446,9 @@ while getopts 'fesltra64bpkdmuchCSi' opt; do
 		u)
 			userspace_tests
 			;;
+		F)
+			fail_tests
+			;;
 		c)
 			;;
 		C)
-- 
2.34.1