selftests: netfilter: add test for br_netfilter+conntrack+queue combination

Trigger cloned skbs leaving softirq protection.
This triggers splat without the preceeding change
("netfilter: nf_queue: drop packets with cloned unconfirmed
 conntracks"):

WARNING: at net/netfilter/nf_conntrack_core.c:1198 __nf_conntrack_confirm..

because local delivery and forwarding will race for confirmation.

Based on a reproducer script from Yi Chen.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

tools/testing/selftests/net/netfilter/Makefile

@@ -7,6 +7,7 @@ MNL_CFLAGS := $(shell $(HOSTPKG_CONFIG) --cflags libmnl 2>/dev/null)
 MNL_LDLIBS := $(shell $(HOSTPKG_CONFIG) --libs libmnl 2>/dev/null || echo -lmnl)
 
 TEST_PROGS := br_netfilter.sh bridge_brouter.sh
+TEST_PROGS += br_netfilter_queue.sh
 TEST_PROGS += conntrack_icmp_related.sh
 TEST_PROGS += conntrack_ipip_mtu.sh
 TEST_PROGS += conntrack_tcp_unreplied.sh

tools/testing/selftests/net/netfilter/br_netfilter_queue.sh

+#!/bin/bash
+
+source lib.sh
+
+checktool "nft --version" "run test without nft tool"
+
+cleanup() {
+	cleanup_all_ns
+}
+
+setup_ns c1 c2 c3 sender
+
+trap cleanup EXIT
+
+nf_queue_wait()
+{
+	grep -q "^ *$1 " "/proc/self/net/netfilter/nfnetlink_queue"
+}
+
+port_add() {
+	ns="$1"
+	dev="$2"
+	a="$3"
+
+	ip link add name "$dev" type veth peer name "$dev" netns "$ns"
+
+	ip -net "$ns" addr add 192.168.1."$a"/24 dev "$dev"
+	ip -net "$ns" link set "$dev" up
+
+	ip link set "$dev" master br0
+	ip link set "$dev" up
+}
+
+[ "${1}" != "run" ] && { unshare -n "${0}" run; exit $?; }
+
+ip link add br0 type bridge
+ip addr add 192.168.1.254/24 dev br0
+
+port_add "$c1" "c1" 1
+port_add "$c2" "c2" 2
+port_add "$c3" "c3" 3
+port_add "$sender" "sender" 253
+
+ip link set br0 up
+
+modprobe -q br_netfilter
+
+sysctl net.bridge.bridge-nf-call-iptables=1 || exit 1
+
+ip netns exec "$sender" ping -I sender -c1 192.168.1.1 || exit 1
+ip netns exec "$sender" ping -I sender -c1 192.168.1.2 || exit 2
+ip netns exec "$sender" ping -I sender -c1 192.168.1.3 || exit 3
+
+nft -f /dev/stdin <<EOF
+table ip filter {
+	chain forward {
+		type filter hook forward priority 0; policy accept;
+		ct state new counter
+		ip protocol icmp counter queue num 0 bypass
+	}
+}
+EOF
+./nf_queue -t 5 > /dev/null &
+
+busywait 5000 nf_queue_wait
+
+for i in $(seq 1 5); do conntrack -F > /dev/null 2> /dev/null; sleep 0.1 ; done &
+ip netns exec "$sender" ping -I sender -f -c 50 -b 192.168.1.255
+
+read t < /proc/sys/kernel/tainted
+if [ "$t" -eq 0 ];then
+	echo PASS: kernel not tainted
+else
+	echo ERROR: kernel is tainted
+	exit 1
+fi
+
+exit 0