sst-linux/net/openvswitch
Guillaume Nault b88786ea2c tunnels: Accept PACKET_HOST in skb_tunnel_check_pmtu().
[ Upstream commit 8930424777e43257f5bf6f0f0f53defd0d30415c ]

Because skb_tunnel_check_pmtu() doesn't handle PACKET_HOST packets,
commit 30a92c9e3d6b ("openvswitch: Set the skbuff pkt_type for proper
pmtud support.") forced skb->pkt_type to PACKET_OUTGOING for
openvswitch packets that are sent using the OVS_ACTION_ATTR_OUTPUT
action. This allowed such packets to invoke the
iptunnel_pmtud_check_icmp() or iptunnel_pmtud_check_icmpv6() helpers
and thus trigger PMTU update on the input device.

However, this also broke other parts of PMTU discovery. Since these
packets don't have the PACKET_HOST type anymore, they won't trigger the
sending of ICMP Fragmentation Needed or Packet Too Big messages to
remote hosts when oversized (see the skb_in->pkt_type condition in
__icmp_send() for example).

These two skb->pkt_type checks are therefore incompatible as one
requires skb->pkt_type to be PACKET_HOST, while the other requires it
to be anything but PACKET_HOST.

It makes sense to not trigger ICMP messages for non-PACKET_HOST packets
as these messages should be generated only for incoming l2-unicast
packets. However there doesn't seem to be any reason for
skb_tunnel_check_pmtu() to ignore PACKET_HOST packets.

Allow both cases to work by allowing skb_tunnel_check_pmtu() to work on
PACKET_HOST packets and not overriding skb->pkt_type in openvswitch
anymore.

Fixes: 30a92c9e3d6b ("openvswitch: Set the skbuff pkt_type for proper pmtud support.")
Fixes: 4cb47a8644 ("tunnels: PMTU discovery support for directly bridged IP packets")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Tested-by: Aaron Conole <aconole@redhat.com>
Link: https://patch.msgid.link/eac941652b86fddf8909df9b3bf0d97bc9444793.1743208264.git.gnault@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-04-10 14:33:40 +02:00
..
actions.c tunnels: Accept PACKET_HOST in skb_tunnel_check_pmtu(). 2025-04-10 14:33:40 +02:00
conntrack.c
conntrack.h
datapath.c
datapath.h
dp_notify.c
flow_netlink.c net: openvswitch: remove misbehaving actions length check 2025-03-28 21:58:50 +01:00
flow_netlink.h
flow_table.c
flow_table.h
flow.c
flow.h
Kconfig
Makefile
meter.c
meter.h
openvswitch_trace.c
openvswitch_trace.h
vport-geneve.c
vport-gre.c
vport-internal_dev.c
vport-internal_dev.h
vport-netdev.c
vport-netdev.h
vport-vxlan.c
vport.c
vport.h