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UPSTREAM: udp: skip L4 aggregation for UDP tunnel packets

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If NETIF_F_GRO_FRAGLIST or NETIF_F_GRO_UDP_FWD are enabled, and there
are UDP tunnels available in the system, udp_gro_receive() could end-up
doing L4 aggregation (either SKB_GSO_UDP_L4 or SKB_GSO_FRAGLIST) at
the outer UDP tunnel level for packets effectively carrying and UDP
tunnel header.

That could cause inner protocol corruption. If e.g. the relevant
packets carry a vxlan header, different vxlan ids will be ignored/
aggregated to the same GSO packet. Inner headers will be ignored, too,
so that e.g. TCP over vxlan push packets will be held in the GRO
engine till the next flush, etc.

Just skip the SKB_GSO_UDP_L4 and SKB_GSO_FRAGLIST code path if the
current packet could land in a UDP tunnel, and let udp_gro_receive()
do GRO via udp_sk(sk)->gro_receive.

The check implemented in this patch is broader than what is strictly
needed, as the existing UDP tunnel could be e.g. configured on top of
a different device: we could end-up skipping GRO at-all for some packets.

Anyhow, that is a very thin corner case and covering it will add quite
a bit of complexity.

v1 -> v2:
 - hopefully clarify the commit message

Fixes: 9fd1ff5d2ac7 ("udp: Support UDP fraglist GRO/GSO.")
Fixes: 36707061d6ba ("udp: allow forwarding of plain (non-fraglisted) UDP GRO packets")
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 18f25dc399901426dff61e676ba603ff52c666f7)
Bug: 187129171
Signed-off-by: Connor O'Brien <connoro@google.com>
Change-Id: If48b1d56009edac9710a100889696d75965eb764
This commit is contained in:
Paolo Abeni 2021-03-30 12:28:50 +02:00 committed by Connor O'Brien
parent 13ab504be3
commit 01228292a6
1 changed files with 10 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
net/ipv4/udp_offload.c
View File

@ -512,20 +512,23 @@ struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
unsigned int off = skb_gro_offset(skb);
int flush = 1;
/* we can do L4 aggregation only if the packet can't land in a tunnel
* otherwise we could corrupt the inner stream
*/
NAPI_GRO_CB(skb)->is_flist = 0;
if (skb->dev->features & NETIF_F_GRO_FRAGLIST)
NAPI_GRO_CB(skb)->is_flist = sk ? !udp_sk(sk)->gro_enabled: 1;
if (!sk || !udp_sk(sk)->gro_receive) {
if (skb->dev->features & NETIF_F_GRO_FRAGLIST)
NAPI_GRO_CB(skb)->is_flist = sk ? !udp_sk(sk)->gro_enabled : 1;
if ((sk && udp_sk(sk)->gro_enabled) || NAPI_GRO_CB(skb)->is_flist) {
pp = call_gro_receive(udp_gro_receive_segment, head, skb);
if ((sk && udp_sk(sk)->gro_enabled) || NAPI_GRO_CB(skb)->is_flist)
pp = call_gro_receive(udp_gro_receive_segment, head, skb);
return pp;
}
if (!sk || NAPI_GRO_CB(skb)->encap_mark ||
if (NAPI_GRO_CB(skb)->encap_mark ||
(uh->check && skb->ip_summed != CHECKSUM_PARTIAL &&
NAPI_GRO_CB(skb)->csum_cnt == 0 &&
!NAPI_GRO_CB(skb)->csum_valid) ||
!udp_sk(sk)->gro_receive)
!NAPI_GRO_CB(skb)->csum_valid))
goto out;
/* mark that this skb passed once through the tunnel gro layer */