From 765695eaa2861f9b5e8b3efab02a0646d0381787 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@tailscale.com>
Date: Fri, 29 May 2020 22:40:26 -0700
Subject: [PATCH] net/netns: also don't err on tailscaled -fake as a regular
 user

That's one of my dev workflows.
---
 net/netns/netns_linux.go | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/net/netns/netns_linux.go b/net/netns/netns_linux.go
index e2b738884..30c6775b6 100644
--- a/net/netns/netns_linux.go
+++ b/net/netns/netns_linux.go
@@ -38,11 +38,22 @@ func control(network, address string, c syscall.RawConn) error {
 	err := c.Control(func(fd uintptr) {
 		controlErr = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_MARK, tailscaleBypassMark)
 	})
-	// Before returning some fatal error, see if we're just a regular user
-	// running cmd/tailscale (presumably netcheck) and ignore the error if so.
+	// Before returning some fatal error, skip it in some cases.
 	if (err != nil || controlErr != nil) && os.Getuid() != 0 {
-		if v, _ := os.Executable(); filepath.Base(v) == "tailscale" {
-			return nil
+		v, _ := os.Executable()
+		switch filepath.Base(v) {
+		case "tailscale":
+			for _, arg := range os.Args {
+				if arg == "netcheck" {
+					return nil
+				}
+			}
+		case "tailscaled":
+			for _, arg := range os.Args {
+				if arg == "-fake" || arg == "--fake" {
+					return nil
+				}
+			}
 		}
 	}
 	if err != nil {