Merge pull request #173109 from Mic92/upterm

nixos/upterm: additional hardening

nixos/modules/services/networking/uptermd.nix

@@ -85,6 +85,7 @@ in
         AmbientCapabilities = mkIf (cfg.port < 1024) [ "CAP_NET_BIND_SERVICE" ];
         CapabilityBoundingSet = mkIf (cfg.port < 1024) [ "CAP_NET_BIND_SERVICE" ];
         PrivateUsers = cfg.port >= 1024;
+        DynamicUser = true;
         LockPersonality = true;
         MemoryDenyWriteExecute = true;
         PrivateDevices = true;
@@ -95,7 +96,9 @@ in
         ProtectKernelLogs = true;
         ProtectKernelModules = true;
         ProtectKernelTunables = true;
-        RestrictAddressFamilies = [ "AF_INET" "AF_INET6" ];
+        ProtectProc = "invisible";
+        # AF_UNIX is for ssh-keygen, which relies on nscd to resolve the uid to a user
+        RestrictAddressFamilies = [ "AF_INET" "AF_INET6" "AF_UNIX" ];
         RestrictNamespaces = true;
         RestrictRealtime = true;
         SystemCallArchitectures = "native";

nixos/tests/uptermd.nix

@@ -30,11 +30,14 @@ in
     server.wait_for_unit("uptermd.service")
     server.wait_for_unit("network-online.target")
 
+    # wait for upterm port to be reachable
+    client1.wait_until_succeeds("nc -z -v server 1337")
+
     # Add SSH hostkeys from the server to both clients
     # uptermd needs an '@cert-authority entry so we need to modify the known_hosts file
-    client1.execute("sleep 3; mkdir -p ~/.ssh && ssh -o StrictHostKeyChecking=no -p 1337 server ls")
+    client1.execute("mkdir -p ~/.ssh && ssh -o StrictHostKeyChecking=no -p 1337 server ls")
     client1.execute("echo @cert-authority $(cat ~/.ssh/known_hosts) > ~/.ssh/known_hosts")
-    client2.execute("sleep 3; mkdir -p ~/.ssh && ssh -o StrictHostKeyChecking=no -p 1337 server ls")
+    client2.execute("mkdir -p ~/.ssh && ssh -o StrictHostKeyChecking=no -p 1337 server ls")
     client2.execute("echo @cert-authority $(cat ~/.ssh/known_hosts) > ~/.ssh/known_hosts")
 
     client1.wait_for_unit("multi-user.target")