selftests/net: use tc rule to filter the na packet

Test arp_ndisc_untracked_subnets use tcpdump to filter the unsolicited
and untracked na messages. It set -e before calling tcpdump. But if
tcpdump filters 0 packet, it will return none zero, and cause the script
to exit.

Instead of using slow tcpdump to capture packets, let's using tc rule
to filter out the na message.

At the same time, fix function setup_v6 which only needs one parameter.
Move all the related helpers from forwarding lib.sh to net lib.sh.

Fixes: 0ea7b0a4 ("selftests: net: arp_ndisc_untracked_subnets: test for arp_accept and accept_untracked_na")
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240517010327.2631319-1-liuhangbin@gmail.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

tools/testing/selftests/net/arp_ndisc_untracked_subnets.sh

@@ -73,25 +73,19 @@ setup_v6() {
 	# namespaces. veth0 is veth-router, veth1 is veth-host.
 	# first, set up the inteface's link to the namespace
 	# then, set the interface "up"
-	ip -6 -netns ${ROUTER_NS_V6} link add name ${ROUTER_INTF} \
-		type veth peer name ${HOST_INTF}
-
-	ip -6 -netns ${ROUTER_NS_V6} link set dev ${ROUTER_INTF} up
-	ip -6 -netns ${ROUTER_NS_V6} link set dev ${HOST_INTF} netns \
-		${HOST_NS_V6}
+	ip -n ${ROUTER_NS_V6} link add name ${ROUTER_INTF} \
+		type veth peer name ${HOST_INTF} netns ${HOST_NS_V6}
 
-	ip -6 -netns ${HOST_NS_V6} link set dev ${HOST_INTF} up
-	ip -6 -netns ${ROUTER_NS_V6} addr add \
-		${ROUTER_ADDR_V6}/${PREFIX_WIDTH_V6} dev ${ROUTER_INTF} nodad
+	# Add tc rule to filter out host na message
+	tc -n ${ROUTER_NS_V6} qdisc add dev ${ROUTER_INTF} clsact
+	tc -n ${ROUTER_NS_V6} filter add dev ${ROUTER_INTF} \
+		ingress protocol ipv6 pref 1 handle 101 \
+		flower src_ip ${HOST_ADDR_V6} ip_proto icmpv6 type 136 skip_hw action pass
 
 	HOST_CONF=net.ipv6.conf.${HOST_INTF}
 	ip netns exec ${HOST_NS_V6} sysctl -qw ${HOST_CONF}.ndisc_notify=1
 	ip netns exec ${HOST_NS_V6} sysctl -qw ${HOST_CONF}.disable_ipv6=0
-	ip -6 -netns ${HOST_NS_V6} addr add ${HOST_ADDR_V6}/${PREFIX_WIDTH_V6} \
-		dev ${HOST_INTF}
-
 	ROUTER_CONF=net.ipv6.conf.${ROUTER_INTF}
-
 	ip netns exec ${ROUTER_NS_V6} sysctl -w \
 		${ROUTER_CONF}.forwarding=1 >/dev/null 2>&1
 	ip netns exec ${ROUTER_NS_V6} sysctl -w \
@@ -99,6 +93,13 @@ setup_v6() {
 	ip netns exec ${ROUTER_NS_V6} sysctl -w \
 		${ROUTER_CONF}.accept_untracked_na=${accept_untracked_na} \
 		>/dev/null 2>&1
+
+	ip -n ${ROUTER_NS_V6} link set dev ${ROUTER_INTF} up
+	ip -n ${HOST_NS_V6} link set dev ${HOST_INTF} up
+	ip -n ${ROUTER_NS_V6} addr add ${ROUTER_ADDR_V6}/${PREFIX_WIDTH_V6} \
+		dev ${ROUTER_INTF} nodad
+	ip -n ${HOST_NS_V6} addr add ${HOST_ADDR_V6}/${PREFIX_WIDTH_V6} \
+		dev ${HOST_INTF}
 	set +e
 }
 
@@ -162,26 +163,6 @@ arp_test_gratuitous_combinations() {
 	arp_test_gratuitous 2 1
 }
 
-cleanup_tcpdump() {
-	set -e
-	[[ ! -z  ${tcpdump_stdout} ]] && rm -f ${tcpdump_stdout}
-	[[ ! -z  ${tcpdump_stderr} ]] && rm -f ${tcpdump_stderr}
-	tcpdump_stdout=
-	tcpdump_stderr=
-	set +e
-}
-
-start_tcpdump() {
-	set -e
-	tcpdump_stdout=`mktemp`
-	tcpdump_stderr=`mktemp`
-	ip netns exec ${ROUTER_NS_V6} timeout 15s \
-		tcpdump --immediate-mode -tpni ${ROUTER_INTF} -c 1 \
-		"icmp6 && icmp6[0] == 136 && src ${HOST_ADDR_V6}" \
-		> ${tcpdump_stdout} 2> /dev/null
-	set +e
-}
-
 verify_ndisc() {
 	local accept_untracked_na=$1
 	local same_subnet=$2
@@ -222,8 +203,9 @@ ndisc_test_untracked_advertisements() {
 			HOST_ADDR_V6=2001:db8:abcd:0012::3
 		fi
 	fi
-	setup_v6 $1 $2
-	start_tcpdump
+	setup_v6 $1
+	slowwait_for_counter 15 1 \
+		tc_rule_handle_stats_get "dev ${ROUTER_INTF} ingress" 101 ".packets" "-n ${ROUTER_NS_V6}"
 
 	if verify_ndisc $1 $2; then
 		printf "    TEST: %-60s  [ OK ]\n" "${test_msg[*]}"
@@ -231,7 +213,6 @@ ndisc_test_untracked_advertisements() {
 		printf "    TEST: %-60s  [FAIL]\n" "${test_msg[*]}"
 	fi
 
-	cleanup_tcpdump
 	cleanup_v6
 	set +e
 }

tools/testing/selftests/net/forwarding/lib.sh

@@ -129,14 +129,6 @@ fi
 
 source "$net_forwarding_dir/../lib.sh"
 
-# timeout in seconds
-slowwait()
-{
-	local timeout_sec=$1; shift
-
-	loopy_wait "sleep 0.1" "$((timeout_sec * 1000))" "$@"
-}
-
 ##############################################################################
 # Sanity checks
 
@@ -678,33 +670,6 @@ wait_for_trap()
 	"$@" | grep -q trap
 }
 
-until_counter_is()
-{
-	local expr=$1; shift
-	local current=$("$@")
-
-	echo $((current))
-	((current $expr))
-}
-
-busywait_for_counter()
-{
-	local timeout=$1; shift
-	local delta=$1; shift
-
-	local base=$("$@")
-	busywait "$timeout" until_counter_is ">= $((base + delta))" "$@"
-}
-
-slowwait_for_counter()
-{
-	local timeout=$1; shift
-	local delta=$1; shift
-
-	local base=$("$@")
-	slowwait "$timeout" until_counter_is ">= $((base + delta))" "$@"
-}
-
 setup_wait_dev()
 {
 	local dev=$1; shift
@@ -1023,29 +988,6 @@ link_stats_rx_errors_get()
 	link_stats_get $1 rx errors
 }
 
-tc_rule_stats_get()
-{
-	local dev=$1; shift
-	local pref=$1; shift
-	local dir=$1; shift
-	local selector=${1:-.packets}; shift
-
-	tc -j -s filter show dev $dev ${dir:-ingress} pref $pref \
-	    | jq ".[1].options.actions[].stats$selector"
-}
-
-tc_rule_handle_stats_get()
-{
-	local id=$1; shift
-	local handle=$1; shift
-	local selector=${1:-.packets}; shift
-	local netns=${1:-""}; shift
-
-	tc $netns -j -s filter show $id \
-	    | jq ".[] | select(.options.handle == $handle) | \
-		  .options.actions[0].stats$selector"
-}
-
 ethtool_stats_get()
 {
 	local dev=$1; shift

tools/testing/selftests/net/lib.sh

@@ -91,6 +91,41 @@ busywait()
 	loopy_wait : "$timeout_ms" "$@"
 }
 
+# timeout in seconds
+slowwait()
+{
+	local timeout_sec=$1; shift
+
+	loopy_wait "sleep 0.1" "$((timeout_sec * 1000))" "$@"
+}
+
+until_counter_is()
+{
+	local expr=$1; shift
+	local current=$("$@")
+
+	echo $((current))
+	((current $expr))
+}
+
+busywait_for_counter()
+{
+	local timeout=$1; shift
+	local delta=$1; shift
+
+	local base=$("$@")
+	busywait "$timeout" until_counter_is ">= $((base + delta))" "$@"
+}
+
+slowwait_for_counter()
+{
+	local timeout=$1; shift
+	local delta=$1; shift
+
+	local base=$("$@")
+	slowwait "$timeout" until_counter_is ">= $((base + delta))" "$@"
+}
+
 cleanup_ns()
 {
 	local ns=""
@@ -150,3 +185,26 @@ setup_ns()
 	done
 	NS_LIST="$NS_LIST $ns_list"
 }
+
+tc_rule_stats_get()
+{
+	local dev=$1; shift
+	local pref=$1; shift
+	local dir=$1; shift
+	local selector=${1:-.packets}; shift
+
+	tc -j -s filter show dev $dev ${dir:-ingress} pref $pref \
+	    | jq ".[1].options.actions[].stats$selector"
+}
+
+tc_rule_handle_stats_get()
+{
+	local id=$1; shift
+	local handle=$1; shift
+	local selector=${1:-.packets}; shift
+	local netns=${1:-""}; shift
+
+	tc $netns -j -s filter show $id \
+	    | jq ".[] | select(.options.handle == $handle) | \
+		  .options.actions[0].stats$selector"
+}