netdev - [PATCH net-next 0/3] Single MSS length in UDP GSO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20260125121649.778086-1-gal@nvidia.com>
Date: Sun, 25 Jan 2026 14:16:46 +0200
From: Gal Pressman <gal@...dia.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Andrew Lunn <andrew+netdev@...n.ch>,
	<netdev@...r.kernel.org>
CC: Igor Russkikh <irusskikh@...vell.com>, Boris Pismenny <borisp@...dia.com>,
	Saeed Mahameed <saeedm@...dia.com>, Leon Romanovsky <leon@...nel.org>, "Tariq
 Toukan" <tariqt@...dia.com>, Mark Bloch <mbloch@...dia.com>, David Ahern
	<dsahern@...nel.org>, Simon Horman <horms@...nel.org>, Alexander Duyck
	<alexanderduyck@...com>, <linux-rdma@...r.kernel.org>, Gal Pressman
	<gal@...dia.com>
Subject: [PATCH net-next 0/3] Single MSS length in UDP GSO_PARTIAL

This series addresses an inconsistency in how UDP GSO_PARTIAL handles
the UDP header length field.

Currently, when GSO_PARTIAL segmentation is used, the UDP header length
contains the large MSS size, requiring drivers to manually adjust it
before transmitting. This is inconsistent with how tunnel GSO_PARTIAL
handles outer headers in UDP tunnels, where the length is set to the
single segment size.

This was originally suggested by Alexander Duyck back in 2018:
https://lore.kernel.org/netdev/CAKgT0UcdnUWgr3KQ=RnLKigokkiUuYefmL-ePpDvJOBNpKScFA@mail.gmail.com/

The first patch fixes the core UDP offload code to set the UDP length
field to the single segment size (gso_size + UDP header) instead of the
large MSS size. This provides hardware with a proper template length
value for final segmentation.

The subsequent patches remove the now redundant UDP header length
adjustments from the mlx5e and aquantia drivers, as the core code now
handles this correctly.
I couldn't find any other drivers that support UDP GSO_PARTIAL; idpf
supports UDP segmentation, but it does not use GSO_PARTIAL.

Gal Pressman (3):
  udp: gso: Use single MSS length in UDP header for GSO_PARTIAL
  net/mlx5e: Remove redundant UDP length adjustment with GSO_PARTIAL
  net: aquantia: Remove redundant UDP length adjustment with GSO_PARTIAL

 drivers/net/ethernet/aquantia/atlantic/aq_nic.c |  3 ---
 .../mellanox/mlx5/core/en_accel/en_accel.h      | 17 -----------------
 net/ipv4/udp_offload.c                          |  6 ++++--
 3 files changed, 4 insertions(+), 22 deletions(-)

-- 
2.40.1