From: Antoine Tenart <atenart@kernel.org>
To: davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com,
edumazet@google.com
Cc: Antoine Tenart <atenart@kernel.org>,
steffen.klassert@secunet.com, netdev@vger.kernel.org
Subject: [PATCH net 4/4] udp: prevent local UDP tunnel packets from being GROed
Date: Fri, 15 Mar 2024 16:17:20 +0100 [thread overview]
Message-ID: <20240315151722.119628-5-atenart@kernel.org> (raw)
In-Reply-To: <20240315151722.119628-1-atenart@kernel.org>
GRO has a fundamental issue with UDP tunnel packets as it can't detect
those in a foolproof way and GRO could happen before they reach the
tunnel endpoint. Previous commits have fixed issues when UDP tunnel
packets come from a remote host, but if those packets are issued locally
they could run into checksum issues.
If the inner packet has a partial checksum the information will be lost
in the GRO logic, either in udp4/6_gro_complete or in
udp_gro_complete_segment and packets will have an invalid checksum when
leaving the host.
Prevent local UDP tunnel packets from ever being GROed at the outer UDP
level.
Due to skb->encapsulation being wrongly used in some drivers this is
actually only preventing UDP tunnel packets with a partial checksum to
be GROed (see iptunnel_handle_offloads) but those were also the packets
triggering issues so in practice this should be sufficient.
Fixes: 9fd1ff5d2ac7 ("udp: Support UDP fraglist GRO/GSO.")
Fixes: 36707061d6ba ("udp: allow forwarding of plain (non-fraglisted) UDP GRO packets")
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
---
net/ipv4/udp_offload.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 3263ebcaa3f4..4ea72bd4f6d7 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -559,6 +559,12 @@ struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
*/
NAPI_GRO_CB(skb)->is_flist = 0;
if (!sk || !udp_sk(sk)->gro_receive) {
+ /* If the packet was locally encapsulated in a UDP tunnel that
+ * wasn't detected above, do not GRO.
+ */
+ if (skb->encapsulation)
+ goto out;
+
if (skb->dev->features & NETIF_F_GRO_FRAGLIST)
NAPI_GRO_CB(skb)->is_flist = sk ? !udp_test_bit(GRO_ENABLED, sk) : 1;
--
2.44.0
next prev parent reply other threads:[~2024-03-15 15:17 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-15 15:17 [PATCH net 0/4] gro: various fixes related to UDP tunnels Antoine Tenart
2024-03-15 15:17 ` [PATCH net 1/4] udp: do not accept non-tunnel GSO skbs landing in a tunnel Antoine Tenart
2024-03-15 21:21 ` kernel test robot
2024-03-18 10:03 ` Antoine Tenart
2024-03-15 21:43 ` kernel test robot
2024-03-16 14:05 ` Willem de Bruijn
2024-03-15 15:17 ` [PATCH net 2/4] gro: fix ownership transfer Antoine Tenart
2024-03-16 15:25 ` Willem de Bruijn
2024-03-18 9:09 ` Antoine Tenart
2024-03-15 15:17 ` [PATCH net 3/4] udp: do not transition UDP fraglist to unnecessary checksum Antoine Tenart
2024-03-15 15:17 ` Antoine Tenart [this message]
2024-03-16 15:43 ` [PATCH net 4/4] udp: prevent local UDP tunnel packets from being GROed Willem de Bruijn
2024-03-18 8:43 ` Antoine Tenart
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