From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f45.google.com (mail-ej1-f45.google.com [209.85.218.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6CE8939A7F6 for ; Wed, 1 Jul 2026 23:11:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.45 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782947465; cv=none; b=bvQHQh7Y0pHlu20S1sb+hhIxlIgbk6sMB+PVzoR3GdcRR7gQdGWqPmJ6CZ6Lon28y/9h4thZhPHW2rrCliXcHhiwtMeqVGB+RxTe/CTOs1m73fk8TwDLu5noTJkQEt02fjhT5gmTdP7hMXg1DgbiK88+866j0k9bxyhVR7HZ7c0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782947465; c=relaxed/simple; bh=aXRM6rleMtmqAGpHOgyjB5R1SPGt0HQzOmTZSePQYyk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uxoJU4rCozjmiFkkCwvz/o+z6+cGmqjKnt5fsi8NyklbqtSH+gIO/r7L4s99ctlzrHmE46KNTMo5KjT0fvDc0tziCIynsHK28IWYUJaIXz72lUjaAq1oYJtDHRyCsBxk9+JTwEwiSBxvNsrSqf4UQe4+bcGaaO+yI129HfYTO1M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=Dtw9qJwM; arc=none smtp.client-ip=209.85.218.45 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Dtw9qJwM" Received: by mail-ej1-f45.google.com with SMTP id a640c23a62f3a-c126b8118afso178893666b.2 for ; Wed, 01 Jul 2026 16:11:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1782947463; x=1783552263; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=2Vd217j9BX8Lq/p1KnSze+ojMBVOwOcfGoPl0hFkSxs=; b=Dtw9qJwM77WF3+YZvu9pq1f46h+8kdE0rrD8is4mFTaMzSzFaO6SHfe2XKAAfQau+u UPidPhXCkwfr96GcRvbK6sHAHo3Vx5QX0rH4KnbpNcMmxBhLJpW8wUlJOgkcaM5Uxvl/ OGE+V1wc3V3oB4Ns6nPHKWtq986rFYEPl5Y9VQNISt9gpvjGU4RlM2MORP5Dgl1SIi7/ r6kpaLwfo2QI7np/9bgN/D6ZBnftc2Cn4ozcEaQ2tDofkvqHS8UQSk5weRtqhXRNzsN6 c2BCu5pYqNMgf14rQAhvS7m/makxy4/cslB7VSKPbA3Nw6NrZDC0G6whoUdsdI6E54kl /CFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1782947463; x=1783552263; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=2Vd217j9BX8Lq/p1KnSze+ojMBVOwOcfGoPl0hFkSxs=; b=mmvRBpuxVhbB8SP5JuAFVSsDN4qjSXeZ0XzuOGxoigDiDCspgnS/hYt5mQtlz1Jyjm iZQd5dCgwarpPtQ2rTJucs5Q6o89ots7uscHO+Bq6dMyPinRblBQs1dJsmi29WXzHRjf YrsW/Dr18XQ0emkfZ0EJ7DvV7ZGEOXaU2ijR+xOVmhI5g7z/nN5zd6eQ1AjHmNbuDwa2 JZCL4yxXnV6D6tdCrGoLTsY8c5TPb45OqbJAdBBjgKOb2WNOejNrhiLnJsSpPNVvvZQ3 Qk+VZIMjWoQfQyc+JXwyFU9gPJeA90XZaXbWVKzMTkJHu6p6Mld9MSho2eYkOMUOsxVq RkMA== X-Gm-Message-State: AOJu0Yxsat8UpQYFVaclsPL7fmdTWv3FqdgaKAKjFhYqcfQrBxjIPXjH jfXTDFC8FFo96TZNIOYiyPz5vRJCgl55lOnSrqfeScHRR9NU8j8jO5Ask7/ZVhov1mQ= X-Gm-Gg: AfdE7clNbyNGCq+linajrj9fqtSBB/EldbnGD9IJJUnZMKGjcHGvd5hQkJkxm8zBpAd 5QEZ0yowzYDKWUL51vuoFVrS7NRs/m0vwQ6ll4ZxG3le0tX7gB8bKNuNRb3b/qPAH8mwQQANp0I oGPLETtJlZN+OoPGKHqQNMzxbLolmts5r+9NgXivUG1GSvJSUhKg6pij5QRasjS0BVW+VLPhFbJ D4Yq5kfJI+a36k81/6OFm3gUPKOchXqOATqu/YeqKlWDCrAWQO3+hRDbgZo0sRUrRBJZWR9tgZd x/5sN6qtva9fsVjcG1iVXjRq1B6/q3+sgiJ5PbPLf60CIkMCyecYj8BWSWe/LWGfFrCIV3oHYkC qFyy+1Imd6aji/qEsteuIgGqq5KuRBRf6uWvc1QEv79Zs68c+wDXwhdg/fHfH93i8O4viUxHHSS lfm4Q/ufO7fIxoyZW769i83sj17BlBLoNUj/YJADAjdbWw2s3JYJCbR9ksBQHPzEtwrh/VOrHfS 5dWkg== X-Received: by 2002:a17:906:515:b0:c12:acd3:bde9 with SMTP id a640c23a62f3a-c12ae7e94demr109519266b.45.1782947462673; Wed, 01 Jul 2026 16:11:02 -0700 (PDT) Received: from dau-home-pc.megasoftware.org ([95.164.115.35]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c12b629a1d4sm30663466b.39.2026.07.01.16.10.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Jul 2026 16:11:02 -0700 (PDT) From: Anton Danilov To: netdev@vger.kernel.org Cc: Willem de Bruijn , "David S . Miller" , David Ahern , Eric Dumazet , Kuniyuki Iwashima , Jakub Kicinski , Paolo Abeni , Simon Horman , Shuah Khan , linux-kselftest@vger.kernel.org Subject: [PATCH net-next v4 2/2] selftests: net: add FOU multicast encapsulation resubmit test Date: Thu, 2 Jul 2026 02:10:37 +0300 Message-ID: X-Mailer: git-send-email 2.47.3 In-Reply-To: References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add a selftest to verify that FOU-encapsulated packets addressed to a multicast destination are correctly resubmitted to the inner protocol handler (GRE) via the UDP multicast delivery path. The test creates two network namespaces connected by a veth pair with a FOU/GRETAP tunnel using a multicast remote address (239.0.0.1). Ping is sent through the tunnel and received packets are counted on the receiver's tunnel interface. A static neighbor entry is configured on the sender because ARP replies from the receiver cannot traverse the unidirectional multicast tunnel back to the sender. The early demux optimization (net.ipv4.ip_early_demux) is disabled on the receiver to force packets through __udp4_lib_mcast_deliver(), which is the code path being tested. Signed-off-by: Anton Danilov Assisted-by: Claude:claude-opus-4-6 --- tools/testing/selftests/net/Makefile | 1 + .../testing/selftests/net/fou_mcast_encap.sh | 112 ++++++++++++++++++ 2 files changed, 113 insertions(+) create mode 100755 tools/testing/selftests/net/fou_mcast_encap.sh diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile index 708d960ae07d..7e9ae937cffa 100644 --- a/tools/testing/selftests/net/Makefile +++ b/tools/testing/selftests/net/Makefile @@ -39,6 +39,7 @@ TEST_PROGS := \ fib_rule_tests.sh \ fib_tests.sh \ fin_ack_lat.sh \ + fou_mcast_encap.sh \ fq_band_pktlimit.sh \ gre_gso.sh \ gre_ipv6_lladdr.sh \ diff --git a/tools/testing/selftests/net/fou_mcast_encap.sh b/tools/testing/selftests/net/fou_mcast_encap.sh new file mode 100755 index 000000000000..8db9633f4c28 --- /dev/null +++ b/tools/testing/selftests/net/fou_mcast_encap.sh @@ -0,0 +1,112 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# Test that UDP encapsulation (FOU) correctly handles packet resubmit +# when packets are delivered via the multicast UDP delivery path. +# +# When a FOU-encapsulated packet arrives with a multicast destination IP, +# __udp4_lib_mcast_deliver() must resubmit it to the inner protocol +# handler (e.g., GRE) rather than consuming it. This test verifies that +# by creating a FOU/GRETAP tunnel with a multicast remote address and +# sending ping through it. +# +# The early demux optimization can mask this issue by routing packets via +# the unicast path (udp_unicast_rcv_skb), so we disable it to force +# packets through __udp4_lib_mcast_deliver(). + +source lib.sh + +NSENDER="" +NRECV="" + +cleanup() { + cleanup_all_ns +} + +trap cleanup EXIT + +setup() { + setup_ns NSENDER NRECV + + ip link add veth_s type veth peer name veth_r + ip link set veth_s netns "$NSENDER" + ip link set veth_r netns "$NRECV" + + ip -n "$NSENDER" addr add 10.0.0.1/24 dev veth_s + ip -n "$NSENDER" link set veth_s up + + ip -n "$NRECV" addr add 10.0.0.2/24 dev veth_r + ip -n "$NRECV" link set veth_r up + + # Disable early demux to force multicast delivery path + ip netns exec "$NRECV" sysctl -wq net.ipv4.ip_early_demux=0 + + # Join multicast group on receiver + ip -n "$NRECV" addr add 239.0.0.1/32 dev veth_r autojoin + + # Multicast routes + ip -n "$NRECV" route add 239.0.0.0/8 dev veth_r + ip -n "$NSENDER" route add 239.0.0.0/8 dev veth_s + + # Sender: GRETAP with FOU encap (no FOU listener needed on TX side) + ip -n "$NSENDER" link add eoudp0 type gretap \ + remote 239.0.0.1 local 10.0.0.1 \ + encap fou encap-sport 4797 encap-dport 4797 \ + key 239.0.0.1 + ip -n "$NSENDER" link set eoudp0 up + ip -n "$NSENDER" addr add 192.168.99.1/24 dev eoudp0 + + # Receiver: FOU listener + GRETAP + ip netns exec "$NRECV" ip fou add port 4797 ipproto 47 + ip -n "$NRECV" link add eoudp0 type gretap \ + remote 239.0.0.1 local 10.0.0.2 \ + encap fou encap-sport 4797 encap-dport 4797 \ + key 239.0.0.1 + ip -n "$NRECV" link set eoudp0 up + ip -n "$NRECV" addr add 192.168.99.2/24 dev eoudp0 + + # Static neigh entry on sender: ARP replies cannot traverse the + # multicast tunnel back, so pre-populate the neighbor cache. + local recv_mac + recv_mac=$(ip -n "$NRECV" link show eoudp0 | awk '/ether/{print $2}') + ip -n "$NSENDER" neigh add 192.168.99.2 lladdr "$recv_mac" dev eoudp0 +} + +get_rx_packets() { + ip -n "$NRECV" -s link show eoudp0 | awk '/RX:/{getline; print $2}' +} + +test_fou_mcast_encap() { + local count=100 + local rx_before + local rx_after + local rx_delta + + # Warmup: let any initial broadcast/ARP traffic settle + ip netns exec "$NSENDER" ping -c 1 -W 1 192.168.99.2 >/dev/null 2>&1 + sleep 1 + + rx_before=$(get_rx_packets) + ip netns exec "$NSENDER" ping -c $count -W 1 192.168.99.2 >/dev/null 2>&1 + sleep 1 + rx_after=$(get_rx_packets) + + rx_delta=$((rx_after - rx_before)) + + if [ "$rx_delta" -ge "$count" ]; then + echo "PASS: received $rx_delta/$count packets via multicast FOU/GRETAP" + return "$ksft_pass" + elif [ "$rx_delta" -gt 0 ]; then + echo "FAIL: only $rx_delta/$count packets received (partial delivery)" + return "$ksft_fail" + else + echo "FAIL: 0/$count packets received (multicast encap resubmit broken)" + return "$ksft_fail" + fi +} + +echo "TEST: FOU/GRETAP multicast encapsulation resubmit" + +setup +test_fou_mcast_encap +exit $? -- 2.47.3