From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A89744C4F69 for ; Mon, 28 Sep 2026 14:43:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790606591; cv=none; b=Q43ZY4RMcNz1dtbGlMLLrs2wsPSQag7udF91KfH2g3hypWnUYYA/7wi5MAp2Jpv4qAlAGkWTCKDleRoV0Zo20wXp2dHVO0aciJCyD78D1+DLvFEA9nrD3fHesdmWd9iylixduOV0bnscdUxcAvvXX4vdYe/71mBX8zbVyUTgeRY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790606591; c=relaxed/simple; bh=OSfRzVDUvBeAN7hm0ECX9M2AaR/sma3/1Fm9X0pEYxw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eNybHypV/imxJ/pP3GMVJCZ3cgT73CtB3MgLTA6omqAUs6frLMspRvK5TsRMbC+k6R0OCiHiLeKpKsQ8wE18B/7HRQHS0Sbr34cklY67lZFar7dpd6mZg92ZGi62E5q/IvhoKnm3L1C2IodpBHbXxGx5FgE4lzEjCkS3XDq+iJI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PksIICp+; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="PksIICp+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E94001F00898; Mon, 28 Sep 2026 14:43:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790606583; bh=WNDL+BHhx1E7tAaK0LTR3OnIXWP1n0O7e/XtPSm/qhs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=PksIICp+2yQr+cCNwWJTITYDVijfwvtfsjMZe6FP8PChm6SCEJkn02hqSpU5b4Xmr BRgatUereSYKOBA1GQ78O+zuIbvabMPiqDE0dkSXOT2nKfXEIpt5GRA0BNo2HnnaJE 6Zzj9ipGGl/XiGWaWL4fs3obRigg8oR+uBWKeIY2aNtHNPIW6tCEoHRcls9CLKgki4 2OGAd6n6RSU1mIvYa1TukicYzDQdMP9fQY4AcripJ/euylzVDgcq66Tnt3ByfoPUfD puiWBn8z71lE8Etl7oCF92A2TiyCqTHtcF3U+37vHMh9xnFM7/iLr95yAeFx0D4ECD 8da/+1PElELfw== From: Eric Dumazet To: "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Willem de Bruijn , "Michael S . Tsirkin" , netdev@vger.kernel.org, edumazet@kernel.org Subject: [PATCH v2 net 2/2] selftests: net: tun: add test for VLAN-tagged GSO without NEEDS_CSUM Date: Mon, 28 Sep 2026 14:42:53 +0000 Message-ID: <20260928144254.3361044-3-edumazet@kernel.org> X-Mailer: git-send-email 2.56.0.rc1.315.gc6ed9934b7-goog In-Reply-To: <20260928144254.3361044-1-edumazet@kernel.org> References: <20260928144254.3361044-1-edumazet@kernel.org> 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 in tun.c verifying that a VLAN-tagged (802.1Q) TCPv4 GSO packet without VIRTIO_NET_HDR_F_NEEDS_CSUM (both flags = 0 and flags = VIRTIO_NET_HDR_F_DATA_VALID) is accepted when written to a TAP device (/dev/net/tun with IFF_TAP | IFF_NO_PI | IFF_VNET_HDR). Also verify that mismatched GSO types (e.g. VIRTIO_NET_HDR_GSO_TCPV6 on a VLAN-tagged IPv4 packet) and truncated headers without NEEDS_CSUM are rejected with -EINVAL. Based on a reproducer by Michael S. Tsirkin . Assisted-by: LLM Signed-off-by: Eric Dumazet --- tools/testing/selftests/net/tun.c | 107 ++++++++++++++++++++++++++++++ 1 file changed, 107 insertions(+) diff --git a/tools/testing/selftests/net/tun.c b/tools/testing/selftests/net/tun.c index abe488bac50bb3b05df5c446836c1c3dfa9ea604..c6afafb7b957360e2873640e60a7d580c6564a66 100644 --- a/tools/testing/selftests/net/tun.c +++ b/tools/testing/selftests/net/tun.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include @@ -542,6 +543,112 @@ TEST_F(tun, reattach_close_delete) EXPECT_EQ(tun_delete(self->ifname), 0); } +FIXTURE(tun_vnet_gso) +{ + char ifname[IFNAMSIZ]; + int fd; +}; + +FIXTURE_SETUP(tun_vnet_gso) +{ + int flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR; + + memset(self->ifname, 0, sizeof(self->ifname)); + self->fd = tun_open(self->ifname, flags, 0, 0, NULL); + ASSERT_GE(self->fd, 0); +} + +FIXTURE_TEARDOWN(tun_vnet_gso) +{ + if (self->fd >= 0) + close(self->fd); +} + +static int build_vlan_tcpv4_gso_packet(uint8_t *buf, int payload_len) +{ + uint16_t vlan_tag[2] = { htons(100), htons(ETH_P_IP) }; + uint8_t *cur = buf + sizeof(struct virtio_net_hdr); + struct virtio_net_hdr vh = { 0 }; + struct tcphdr tcph = { 0 }; + uint32_t sum; + + cur += build_eth(cur, ETH_P_8021Q, param_hwaddr_outer_src, + param_hwaddr_outer_dst); + + /* 802.1Q tag: VID=100, inner protocol=ETH_P_IP */ + memcpy(cur, vlan_tag, sizeof(vlan_tag)); + cur += sizeof(vlan_tag); + + cur += build_ipv4_header(cur, IPPROTO_TCP, + sizeof(tcph) + payload_len, + ¶m_ipaddr4_outer_src, + ¶m_ipaddr4_outer_dst); + + tcph.source = htons(12345); + tcph.dest = htons(80); + tcph.seq = htonl(1); + tcph.doff = sizeof(tcph) / 4; + tcph.ack = 1; + tcph.window = htons(65535); + memcpy(cur, &tcph, sizeof(tcph)); + memset(cur + sizeof(tcph), PKT_DATA, payload_len); + + sum = add_csum((const uint8_t *)¶m_ipaddr4_outer_src, + sizeof(param_ipaddr4_outer_src)); + sum += add_csum((const uint8_t *)¶m_ipaddr4_outer_dst, + sizeof(param_ipaddr4_outer_dst)); + sum += htons(IPPROTO_TCP) + htons(sizeof(tcph) + payload_len); + sum += add_csum(cur, sizeof(tcph) + payload_len); + tcph.check = finish_ip_csum(sum); + memcpy(cur, &tcph, sizeof(tcph)); + cur += sizeof(tcph) + payload_len; + + vh.gso_type = VIRTIO_NET_HDR_GSO_TCPV4; + vh.gso_size = 1400; + vh.hdr_len = (cur - buf) - sizeof(vh) - payload_len; + memcpy(buf, &vh, sizeof(vh)); + + return cur - buf; +} + +TEST_F(tun_vnet_gso, vlan_tcpv4_gso_no_csum) +{ + struct virtio_net_hdr vh; + uint8_t pkt[4096] = { 0 }; + int len, ret; + + len = build_vlan_tcpv4_gso_packet(pkt, 2800); + memcpy(&vh, pkt, sizeof(vh)); + + /* Valid VLAN-tagged TCPv4 GSO with flags = 0 (no NEEDS_CSUM) */ + vh.flags = 0; + memcpy(pkt, &vh, sizeof(vh)); + ret = write(self->fd, pkt, len); + ASSERT_EQ(ret, len); + + /* Valid VLAN-tagged TCPv4 GSO with flags = DATA_VALID */ + vh.flags = VIRTIO_NET_HDR_F_DATA_VALID; + memcpy(pkt, &vh, sizeof(vh)); + ret = write(self->fd, pkt, len); + ASSERT_EQ(ret, len); + + /* Mismatched GSO type (TCPV6 on VLAN-tagged IPv4 packet) */ + vh.flags = 0; + vh.gso_type = VIRTIO_NET_HDR_GSO_TCPV6; + memcpy(pkt, &vh, sizeof(vh)); + ret = write(self->fd, pkt, len); + ASSERT_EQ(ret, -1); + ASSERT_EQ(errno, EINVAL); + + /* Truncated TCP header without NEEDS_CSUM */ + vh.gso_type = VIRTIO_NET_HDR_GSO_TCPV4; + vh.hdr_len = ETH_HLEN + 4 + sizeof(struct iphdr); + memcpy(pkt, &vh, sizeof(vh)); + ret = write(self->fd, pkt, sizeof(vh) + vh.hdr_len); + ASSERT_EQ(ret, -1); + ASSERT_EQ(errno, EINVAL); +} + FIXTURE(tun_vnet_udptnl) { char ifname[IFNAMSIZ]; -- 2.56.0.rc1.315.gc6ed9934b7-goog