James Tucker f7c1b8e526 hostinfo,ssh/tailssh: don't leak systemd service env to child processes
tailscaled runs under a Type=notify unit, so NOTIFY_SOCKET is in its
environment. The desktop probe ran loginctl with that environment
inherited. loginctl sends sd_notify(3) messages on exit and error, and
lives in the daemon's cgroup, so systemd took each message as coming
from the tailscaled unit and rejected it:

  tailscaled.service: Got notification message from PID 1234, but
  reception only permitted for main PID 1000

One failing exec sends two messages, ERRNO=... and EXIT_STATUS=... That
is the pair of rejected lines seen at each SSH session on Debian-family
hosts. The per-connection ssh-monitor child also received the daemon's
full environment.

Helpers exec'd by tailscaled now get the daemon's environment without
the systemd service-instance variables: NOTIFY_SOCKET, WATCHDOG_PID,
WATCHDOG_USEC, LISTEN_FDS, LISTEN_PID, LISTEN_FDNAMES, INVOCATION_ID,
JOURNAL_STREAM. The scrub covers the loginctl and getenforce probes,
the direct-exec fallback probe, and the ssh-monitor spawn.

Session children still never receive the daemon's environment. The
monitor still gives children running as the connection's user no daemon
variables. The daemon's own environment is unchanged.

Updates tailscale/corp#50380

Change-Id: Ic686726473e851e2855e75eea11d7b3f75440311
Signed-off-by: James Tucker <james@tailscale.com>
2026-10-28 15:17:19 -07:00
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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 1.27. (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:

WireGuard is a registered trademark of Jason A. Donenfeld.

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