1 files changed, 24 insertions, 3 deletions
diff --git a/nixos/modules/services/networking/tailscale.nix b/nixos/modules/services/networking/tailscale.nix
index 1f64113950a..0133874d0e0 100644
--- a/nixos/modules/services/networking/tailscale.nix
+++ b/nixos/modules/services/networking/tailscale.nix
@@ -2,9 +2,13 @@
 
 with lib;
 
-let cfg = config.services.tailscale;
+let
+  cfg = config.services.tailscale;
+  firewallOn = config.networking.firewall.enable;
+  rpfMode = config.networking.firewall.checkReversePath;
+  rpfIsStrict = rpfMode == true || rpfMode == "strict";
 in {
-  meta.maintainers = with maintainers; [ danderson mbaillie ];
+  meta.maintainers = with maintainers; [ danderson mbaillie twitchyliquid64 ];
 
   options.services.tailscale = {
     enable = mkEnableOption "Tailscale client daemon";
@@ -36,17 +40,34 @@ in {
   };
 
   config = mkIf cfg.enable {
+    warnings = optional (firewallOn && rpfIsStrict) "Strict reverse path filtering breaks Tailscale exit node use and some subnet routing setups. Consider setting `networking.firewall.checkReversePath` = 'loose'";
     environment.systemPackages = [ cfg.package ]; # for the CLI
     systemd.packages = [ cfg.package ];
     systemd.services.tailscaled = {
       wantedBy = [ "multi-user.target" ];
-      path = [ pkgs.openresolv pkgs.procps ];
+      path = [
+        pkgs.openresolv # for configuring DNS in some configs
+        pkgs.procps     # for collecting running services (opt-in feature)
+        pkgs.glibc      # for `getent` to look up user shells
+      ];
       serviceConfig.Environment = [
         "PORT=${toString cfg.port}"
         ''"FLAGS=--tun ${lib.escapeShellArg cfg.interfaceName}"''
       ] ++ (lib.optionals (cfg.permitCertUid != null) [
         "TS_PERMIT_CERT_UID=${cfg.permitCertUid}"
       ]);
+      # Restart tailscaled with a single `systemctl restart` at the
+      # end of activation, rather than a `stop` followed by a later
+      # `start`. Activation over Tailscale can hang for tens of
+      # seconds in the stop+start setup, if the activation script has
+      # a significant delay between the stop and start phases
+      # (e.g. script blocked on another unit with a slow shutdown).
+      #
+      # Tailscale is aware of the correctness tradeoff involved, and
+      # already makes its upstream systemd unit robust against unit
+      # version mismatches on restart for compatibility with other
+      # linux distros.
+      stopIfChanged = false;
     };
   };
 }