8b58bd6c64
This NodeCapability works around the UDP GSO bugs introduced by torvalds/linux@b10b446 (v7.0-rc1). These bugs were later fixed by torvalds/linux@78effd8 and torvalds/linux@5f17ae0 (v7.1-rc5). These Linux kernel bugs cause mangled UDP headers and UDP checksums, resulting in high levels of packet loss. The aforementioned bugs have already made their way downstream into various distros, e.g. Ubuntu 26.04 LTS. Impacted users are now dealing with poor UDP performance in tailscaled, and in any other software that makes use of UDP GSO. Not all users of the affected kernels are impacted as the relevant kernel code path sits between kernel and netdev driver, and behaviors vary by driver/device capability. We cannot detect impact at runtime, as this would require gathering all netdevs, and performing loopback tests. This is invasive and in many cases impossible. So, we are left to choose between disabling UDP GSO for all users on affected kernels, whether they experience real impact or not, or try and work around the bugs. Disabling UDP GSO for a user that is not impacted can cut max throughput in half, and consume more CPU cycles. This commit attempts to workaround the bugs by avoiding UDP GSO when batches are small, and injecting a 1-byte sentinel tail payload when they are large. This tail payload is smaller than "GSO size", which sidesteps the primary trigger of all fragments in a batch being equal in length. The end result is slightly increased payload and packet overhead, but functional UDP GSO for all Linux 7.0-7.1.4 users, regardless of netdev/driver. Updates #19777 Signed-off-by: Jordan Whited <jordan@tailscale.com>
Tailscale
Private WireGuard® networks made easy
Overview
This repository contains the majority of Tailscale's open source code.
Notably, it includes the tailscaled daemon and
the tailscale CLI tool. The tailscaled daemon runs on Linux, Windows,
macOS, and to varying degrees
on FreeBSD and OpenBSD. The Tailscale iOS and Android apps use this repo's
code, but this repo doesn't contain the mobile GUI code.
Other Tailscale repos of note:
- the Android app is at https://github.com/tailscale/tailscale-android
- the Synology package is at https://github.com/tailscale/tailscale-synology
- the QNAP package is at https://github.com/tailscale/tailscale-qpkg
- the Chocolatey packaging is at https://github.com/tailscale/tailscale-chocolatey
For background on which parts of Tailscale are open source and why, see https://tailscale.com/opensource/.
Using
We serve packages for a variety of distros and platforms at https://pkgs.tailscale.com.
Other clients
The macOS, iOS, and Windows clients use the code in this repository but additionally include small GUI wrappers. The GUI wrappers on non-open source platforms are themselves not open source.
Building
We always require the latest Go release, currently Go 1.26. (While we build releases with our Go fork, its use is not required.)
go install tailscale.com/cmd/tailscale{,d}
If you're packaging Tailscale for distribution, use build_dist.sh
instead, to burn commit IDs and version info into the binaries:
./build_dist.sh tailscale.com/cmd/tailscale
./build_dist.sh tailscale.com/cmd/tailscaled
If your distro has conventions that preclude the use of
build_dist.sh, please do the equivalent of what it does in your
distro's way, so that bug reports contain useful version information.
Bugs
Please file any issues about this code or the hosted service on the issue tracker.
Contributing
PRs welcome! But please file bugs. Commit messages should reference bugs.
We require Developer Certificate of
Origin
Signed-off-by lines in commits.
See commit-messages.md (or skim git log) for our commit message style.
About Us
Tailscale is primarily developed by the people at https://github.com/orgs/tailscale/people. For other contributors, see:
- https://github.com/tailscale/tailscale/graphs/contributors
- https://github.com/tailscale/tailscale-android/graphs/contributors
Legal
WireGuard is a registered trademark of Jason A. Donenfeld.