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([82.77.81.131]) by smtp.gmail.com with ESMTPSA id t16-20020a1709060c5000b007c14ae38a80sm7987721ejf.122.2022.12.22.00.36.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Dec 2022 00:36:02 -0800 (PST) From: Tudor Ambarus To: stable@vger.kernel.org Cc: willemdebruijn.kernel@gmail.com, mst@redhat.com, jasowang@redhat.com, edumazet@google.com, virtualization@lists.linux-foundation.org, davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, netdev@vger.kernel.org, willemb@google.com, syzkaller@googlegroups.com, liuhangbin@gmail.com, linux-kernel@vger.kernel.org, joneslee@google.com, syzbot+3d91b8dbbcf515400e92@syzkaller.appspotmail.com, Tudor Ambarus Subject: [PATCH 1/2] net/af_packet: add VLAN support for AF_PACKET SOCK_RAW GSO Date: Thu, 22 Dec 2022 10:35:44 +0200 Message-Id: <20221222083545.1972489-2-tudor.ambarus@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20221222083545.1972489-1-tudor.ambarus@linaro.org> References: <20221222083545.1972489-1-tudor.ambarus@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Hangbin Liu [ Upstream commit dfed913e8b55a0c2c4906f1242fd38fd9a116e49 ] Before the blammed commit, the kernel drops GSO VLAN tagged packet if it's created with socket(AF_PACKET, SOCK_RAW, 0) plus virtio_net_hdr. The reason is AF_PACKET doesn't adjust the skb network header if there is a VLAN tag. Then after virtio_net_hdr_set_proto() called, the skb->protocol will be set to ETH_P_IP/IPv6. And in later inet/ipv6_gso_segment() the skb is dropped as network header position is invalid. The blammed commit introduces a kernel BUG in __skb_gso_segment for AF_PACKET SOCK_RAW GSO VLAN tagged packets. What happens is that virtio_net_hdr_set_proto() exists early as skb->protocol is already set to ETH_P_ALL. Then in packet_parse_headers() skb->protocol is set to ETH_P_8021AD, but neither the network header position is adjusted, nor the mac header is pulled. Thus when we get to validate the xmit skb and enter skb_mac_gso_segment(), skb->mac_len has value 14, but vlan_depth gets updated to 18 after skb_network_protocol() is called. This causes the BUG_ON from __skb_pull(skb, vlan_depth) to be hit, as the mac header has not been pulled yet. Let's handle VLAN packets by adjusting network header position in packet_parse_headers(). The adjustment is safe and does not affect the later xmit as tap device also did that. The mac header pull is handled in a following commit: commit e9d3f80935b6 ("net/af_packet: make sure to pull mac header") In packet_snd(), packet_parse_headers() need to be moved before calling virtio_net_hdr_set_proto(), so we can set correct skb->protocol and network header first. There is no need to update tpacket_snd() as it calls packet_parse_headers() in tpacket_fill_skb(), which is already before calling virtio_net_hdr_* functions. skb->no_fcs setting is also moved upper to make all skb settings together and keep consistency with function packet_sendmsg_spkt(). Cc: stable@vger.kernel.org # 5.4+ Fixes: 1ed1d5921139 ("net: skip virtio_net_hdr_set_proto if protocol alread= y set") Reported-by: syzbot+3d91b8dbbcf515400e92@syzkaller.appspotmail.com Signed-off-by: Hangbin Liu Acked-by: Willem de Bruijn Acked-by: Michael S. Tsirkin Link: https://lore.kernel.org/r/20220425014502.985464-1-liuhangbin@gmail.com Signed-off-by: Paolo Abeni Tested-by: Tudor Ambarus [ta: Update commit description, add Cc, Fixes, Reported-by and Tested-by.] Signed-off-by: Tudor Ambarus --- net/packet/af_packet.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index ceca0d6c41b5..f25fa75fe651 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1888,12 +1888,20 @@ static int packet_rcv_spkt(struct sk_buff *skb, str= uct net_device *dev, =20 static void packet_parse_headers(struct sk_buff *skb, struct socket *sock) { + int depth; + if ((!skb->protocol || skb->protocol =3D=3D htons(ETH_P_ALL)) && sock->type =3D=3D SOCK_RAW) { skb_reset_mac_header(skb); skb->protocol =3D dev_parse_header_protocol(skb); } =20 + /* Move network header to the right position for VLAN tagged packets */ + if (likely(skb->dev->type =3D=3D ARPHRD_ETHER) && + eth_type_vlan(skb->protocol) && + __vlan_get_protocol(skb, skb->protocol, &depth) !=3D 0) + skb_set_network_header(skb, depth); + skb_probe_transport_header(skb); } =20 @@ -3008,6 +3016,11 @@ static int packet_snd(struct socket *sock, struct ms= ghdr *msg, size_t len) skb->mark =3D sockc.mark; skb->tstamp =3D sockc.transmit_time; =20 + if (unlikely(extra_len =3D=3D 4)) + skb->no_fcs =3D 1; + + packet_parse_headers(skb, sock); + if (has_vnet_hdr) { err =3D virtio_net_hdr_to_skb(skb, &vnet_hdr, vio_le()); if (err) @@ -3016,11 +3029,6 @@ static int packet_snd(struct socket *sock, struct ms= ghdr *msg, size_t len) virtio_net_hdr_set_proto(skb, &vnet_hdr); } =20 - packet_parse_headers(skb, sock); - - if (unlikely(extra_len =3D=3D 4)) - skb->no_fcs =3D 1; - err =3D po->xmit(skb); if (unlikely(err !=3D 0)) { if (err > 0) --=20 2.34.1