Brad Fitzpatrick
2fc4be0f76
The forwarder's upstream UDP socket is unconnected, so any host that could send a datagram to its ephemeral port reached the single ReadFromUDPAddrPort call that decided the query: a datagram with the right 16-bit transaction ID was returned to the client as the resolver's answer no matter what address it came from, and a datagram with the wrong ID failed the query outright, handing it to the TCP fallback (or to nothing at all, with TCP retries disabled). sendUDP now keeps reading until a datagram arrives that could be a reply to the query it sent: one from the resolver's address and port carrying the transaction ID of the request. Other datagrams are dropped and counted, so neither a spoofed reply nor a single stray datagram can answer or end the query. This is the same source check the kernel applies to a connected socket; the socket stays unconnected because its ListenPacket path is what binds the query to a link (IP_BOUND_IF on macOS, ForwardLinkSelector elsewhere). The read loop still ends when the query context expires and closeOnCtxDone closes the conn, as before. On Windows an oversized datagram is reported as a truncation error without a source address, so there the transaction ID remains the only check, as before. Thanks to Ben Carman for the report! Updates tailscale/corp#48187 Reported-by: Ben Carman Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com> Change-Id: Ibabbec5c82739b66caa6fb943faa376c39adbf64
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 1.27. (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.