Andrew Dunham 33714211c8 net/dns: use os.Root to prevent path traversal in darwin resolver
The darwinConfigurator writes split DNS resolver files to
/etc/resolver/$SUFFIX using os.WriteFile with string concatenation.
A crafted MatchDomain value containing path traversal sequences
(e.g. "../evil") could write files outside the resolver directory.

Use os.OpenRoot to confine all file operations in SetDNS and
removeResolverFiles to the resolver directory. os.Root rejects any
path component that escapes the root, returning an error instead of
following the traversal.

Also parametrize the resolver directory path on the struct to enable
testing with t.TempDir(), and add tests.

As far as I can tell, this would require a malicious controlplane to
exploit, but still worth fixing.

Updates tailscale/corp#39751

Signed-off-by: Andrew Dunham <andrew@tailscale.com>
2026-04-28 11:08:22 -04:00
2026-04-27 18:38:06 -07:00
2026-03-27 08:41:33 +00:00
2026-01-27 16:15:17 -08:00

Tailscale

https://tailscale.com

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:

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:

WireGuard is a registered trademark of Jason A. Donenfeld.

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