netdev - [PATCH nf-next 18/19] selftests: netfilter: nft_queue.sh: add test for disappearing listener

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Date: Thu, 27 Jun 2024 13:27:12 +0200
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net,
	netdev@...r.kernel.org,
	kuba@...nel.org,
	pabeni@...hat.com,
	edumazet@...gle.com,
	fw@...len.de
Subject: [PATCH nf-next 18/19] selftests: netfilter: nft_queue.sh: add test for disappearing listener

From: Florian Westphal <fw@...len.de>

If userspace program exits while the queue its subscribed to has packets
those need to be discarded.

commit dc21c6cc3d69 ("netfilter: nfnetlink_queue: acquire rcu_read_lock()
in instance_destroy_rcu()") fixed a (harmless) rcu splat that could be
triggered in this case.

Add a test case to cover this.

Signed-off-by: Florian Westphal <fw@...len.de>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
 .../selftests/net/netfilter/nft_queue.sh      | 37 +++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/tools/testing/selftests/net/netfilter/nft_queue.sh b/tools/testing/selftests/net/netfilter/nft_queue.sh
index 288b3cc55ed7..7e210d75e738 100755
--- a/tools/testing/selftests/net/netfilter/nft_queue.sh
+++ b/tools/testing/selftests/net/netfilter/nft_queue.sh
@@ -449,6 +449,42 @@ EOF
 	wait "$rpid" && echo "PASS: sctp and nfqueue in output chain with GSO"
 }
 
+test_queue_removal()
+{
+	read tainted_then < /proc/sys/kernel/tainted
+
+	ip netns exec "$ns1" nft -f - <<EOF
+flush ruleset
+table ip filter {
+	chain output {
+		type filter hook output priority 0; policy accept;
+		ip protocol icmp queue num 0
+	}
+}
+EOF
+	ip netns exec "$ns1" ./nf_queue -q 0 -d 30000 -t "$timeout" &
+	local nfqpid=$!
+
+	busywait "$BUSYWAIT_TIMEOUT" nf_queue_wait "$ns1" 0
+
+	ip netns exec "$ns1" ping -w 2 -f -c 10 127.0.0.1 -q >/dev/null
+	kill $nfqpid
+
+	ip netns exec "$ns1" nft flush ruleset
+
+	if [ "$tainted_then" -ne 0 ];then
+		return
+	fi
+
+	read tainted_now < /proc/sys/kernel/tainted
+	if [ "$tainted_now" -eq 0 ];then
+		echo "PASS: queue program exiting while packets queued"
+	else
+		echo "TAINT: queue program exiting while packets queued"
+		ret=1
+	fi
+}
+
 ip netns exec "$nsrouter" sysctl net.ipv6.conf.all.forwarding=1 > /dev/null
 ip netns exec "$nsrouter" sysctl net.ipv4.conf.veth0.forwarding=1 > /dev/null
 ip netns exec "$nsrouter" sysctl net.ipv4.conf.veth1.forwarding=1 > /dev/null
@@ -489,5 +525,6 @@ test_tcp_localhost_requeue
 test_icmp_vrf
 test_sctp_forward
 test_sctp_output
+test_queue_removal
 
 exit $ret
-- 
2.30.2