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* [RFC PATCH 0/4] Introduce per-peer MTU setting
@ 2021-12-28 23:45 leon
  2021-12-28 23:45 ` [RFC PATCH 1/4] netdevice: add ndo_lookup_mtu for dynamically determining MTU leon
                   ` (4 more replies)
  0 siblings, 5 replies; 7+ messages in thread
From: leon @ 2021-12-28 23:45 UTC (permalink / raw)
  To: wireguard; +Cc: Leon Schuermann

From: Leon Schuermann <>

This patch series is an attempt to integrate a per-peer MTU setting
into WireGuard. With matching changes to the wireguard-tools,
individual MTU values can be set and retrieved for each registered

While Linux supports setting an MTU metric for specific FIB route
entries [which I've only found out after implementing this :)], and
thus allows to lower the MTU for individual peers, this appears to
disable regular path MTU discovery (PMTUD) entirely on the
route. While regular PMTUD does not work over the tunnel link, it
should still be usable on the rest of the route.

Furthermore, with the goal of eventually introducing an in-band
per-peer PMTUD mechanism, keeping an internal per-peer MTU value does
not require modifying the FIB and thus potentially interfere with

In an effort to solve this issues, this patch series introduces a
rather generic framework for implementing these kinds of dynamic MTU
policies. By providing a hook in the netdevice implementation to
decide on the applicable MTU, very flexible designs can be built. I
suppose that these changes are rather controversial, or at least
require some more discussion. I'm sending this patchset to the
WireGuard development list in hopes to get some initial feedback on
the idea and implementation and would like to eventually submit the
non-WireGuard changes directly to the netdev ML.

The patches are currently based on v5.10, as that happens to be
what I was developing on. I'll gladly rebase to the latest
revision / wireguard-devel if requested.



Leon Schuermann (4):
  netdevice: add ndo_lookup_mtu for dynamically determining MTU
  net/ipv4: respect MTU determined by `ndo_lookup_mtu`
  net/ipv6: respect MTU determined by `ndo_lookup_mtu`
  net/wireguard: add per-peer MTU setting

 drivers/net/wireguard/allowedips.c |  2 +-
 drivers/net/wireguard/allowedips.h |  2 +-
 drivers/net/wireguard/device.c     | 20 ++++++++++++++++--
 drivers/net/wireguard/netlink.c    |  8 +++++++
 drivers/net/wireguard/peer.c       |  1 +
 drivers/net/wireguard/peer.h       |  1 +
 drivers/net/wireguard/queueing.h   |  2 +-
 include/linux/netdevice.h          | 12 +++++++++++
 include/net/ip.h                   | 34 ++++++++++++++++++++++--------
 include/net/ip6_route.h            | 14 ++++++++++--
 include/uapi/linux/wireguard.h     |  5 +++++
 net/ipv4/ip_forward.c              |  2 +-
 net/netfilter/nf_flow_table_core.c |  2 +-
 13 files changed, 87 insertions(+), 18 deletions(-)

base-commit: 2c85ebc57b3e1817b6ce1a6b703928e113a90442

^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2022-01-07 22:13 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-12-28 23:45 [RFC PATCH 0/4] Introduce per-peer MTU setting leon
2021-12-28 23:45 ` [RFC PATCH 1/4] netdevice: add ndo_lookup_mtu for dynamically determining MTU leon
2021-12-28 23:45 ` [RFC PATCH 2/4] net/ipv4: respect MTU determined by `ndo_lookup_mtu` leon
2021-12-28 23:45 ` [RFC PATCH 3/4] net/ipv6: " leon
2021-12-28 23:45 ` [RFC PATCH 4/4] net/wireguard: add per-peer MTU setting leon
2022-01-04 21:34 ` [RFC PATCH 0/4] Introduce " Toke Høiland-Jørgensen
2022-01-07 22:13   ` Leon Schuermann

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