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21413392cf
Tested three macOS Tailscale daemons: - App Store (Network Extension) - Standalone (macsys) - tailscaled And two types of local IPC each: - IPN - HTTP And two CLI modes: - sandboxed (running the GUI binary as the CLI; normal way) - open source CLI hitting GUI (with #4525) Bonus: simplifies the code. Fixes tailscale/corp#4559 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
157 lines
5.1 KiB
Go
157 lines
5.1 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build !windows && !js
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// +build !windows,!js
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package safesocket
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import (
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"errors"
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"fmt"
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"io"
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"log"
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"net"
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"os"
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"os/exec"
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"path/filepath"
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"runtime"
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"strconv"
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)
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// TODO(apenwarr): handle magic cookie auth
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func connect(s *ConnectionStrategy) (net.Conn, error) {
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if runtime.GOOS == "js" {
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return nil, errors.New("safesocket.Connect not yet implemented on js/wasm")
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}
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if runtime.GOOS == "darwin" && s.fallback && s.path == "" && s.port == 0 {
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return connectMacOSAppSandbox()
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}
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pipe, err := net.Dial("unix", s.path)
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if err != nil {
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if runtime.GOOS == "darwin" && s.fallback {
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extConn, extErr := connectMacOSAppSandbox()
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if extErr != nil {
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return nil, fmt.Errorf("safesocket: failed to connect to %v: %v; failed to connect to Tailscale IPNExtension: %v", s.path, err, extErr)
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}
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return extConn, nil
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}
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return nil, err
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}
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return pipe, nil
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}
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// TODO(apenwarr): handle magic cookie auth
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func listen(path string, port uint16) (ln net.Listener, _ uint16, err error) {
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// Unix sockets hang around in the filesystem even after nobody
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// is listening on them. (Which is really unfortunate but long-
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// entrenched semantics.) Try connecting first; if it works, then
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// the socket is still live, so let's not replace it. If it doesn't
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// work, then replace it.
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//
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// Note that there's a race condition between these two steps. A
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// "proper" daemon usually uses a dance involving pidfiles to first
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// ensure that no other instances of itself are running, but that's
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// beyond the scope of our simple socket library.
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c, err := net.Dial("unix", path)
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if err == nil {
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c.Close()
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if tailscaledRunningUnderLaunchd() {
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return nil, 0, fmt.Errorf("%v: address already in use; tailscaled already running under launchd (to stop, run: $ sudo launchctl stop com.tailscale.tailscaled)", path)
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}
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return nil, 0, fmt.Errorf("%v: address already in use", path)
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}
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_ = os.Remove(path)
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perm := socketPermissionsForOS()
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sockDir := filepath.Dir(path)
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if _, err := os.Stat(sockDir); os.IsNotExist(err) {
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os.MkdirAll(sockDir, 0755) // best effort
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// If we're on a platform where we want the socket
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// world-readable, open up the permissions on the
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// just-created directory too, in case a umask ate
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// it. This primarily affects running tailscaled by
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// hand as root in a shell, as there is no umask when
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// running under systemd.
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if perm == 0666 {
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if fi, err := os.Stat(sockDir); err == nil && fi.Mode()&0077 == 0 {
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if err := os.Chmod(sockDir, 0755); err != nil {
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log.Print(err)
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}
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}
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}
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}
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pipe, err := net.Listen("unix", path)
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if err != nil {
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return nil, 0, err
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}
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os.Chmod(path, perm)
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return pipe, 0, err
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}
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func tailscaledRunningUnderLaunchd() bool {
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if runtime.GOOS != "darwin" {
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return false
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}
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plist, err := exec.Command("launchctl", "list", "com.tailscale.tailscaled").Output()
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_ = plist // parse it? https://github.com/DHowett/go-plist if we need something.
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running := err == nil
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return running
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}
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// socketPermissionsForOS returns the permissions to use for the
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// tailscaled.sock.
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func socketPermissionsForOS() os.FileMode {
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if PlatformUsesPeerCreds() {
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return 0666
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}
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// Otherwise, root only.
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return 0600
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}
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// connectMacOSAppSandbox connects to the Tailscale Network Extension (macOS App
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// Store build) or App Extension (macsys standalone build), where the CLI itself
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// is either running within the macOS App Sandbox or built separately (e.g.
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// homebrew or go install). This little dance to connect a regular user binary
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// to the sandboxed network extension is:
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//
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// * the sandboxed IPNExtension picks a random localhost:0 TCP port
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// to listen on
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// * it also picks a random hex string that acts as an auth token
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// * the CLI looks on disk for that TCP port + auth token (see localTCPPortAndTokenDarwin)
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// * we send it upon TCP connect to prove to the Tailscale daemon that
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// we're a suitably privileged user to have access the files on disk
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// which the Network/App Extension wrote.
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func connectMacOSAppSandbox() (net.Conn, error) {
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port, token, err := LocalTCPPortAndToken()
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if err != nil {
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return nil, fmt.Errorf("failed to find local Tailscale daemon: %w", err)
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}
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return connectMacTCP(port, token)
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}
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// connectMacTCP creates an authenticated net.Conn to the local macOS Tailscale
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// daemon for used by the "IPN" JSON message bus protocol (Tailscale's original
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// local non-HTTP IPC protocol).
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func connectMacTCP(port int, token string) (net.Conn, error) {
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c, err := net.Dial("tcp", "localhost:"+strconv.Itoa(port))
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if err != nil {
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return nil, fmt.Errorf("error dialing IPNExtension: %w", err)
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}
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if _, err := io.WriteString(c, token+"\n"); err != nil {
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return nil, fmt.Errorf("error writing auth token: %w", err)
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}
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buf := make([]byte, 5)
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const authOK = "#IPN\n"
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if _, err := io.ReadFull(c, buf); err != nil {
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return nil, fmt.Errorf("error reading from IPNExtension post-auth: %w", err)
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}
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if string(buf) != authOK {
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return nil, fmt.Errorf("invalid response reading from IPNExtension post-auth")
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}
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return c, nil
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}
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