Allow 'runsc do' to run without root

'--rootless' flag lets a non-root user execute 'runsc do'.
The drawback is that the sandbox and gofer processes will
run as root inside a user namespace that is mapped to the
caller's user, intead of nobody. And network is defaulted
to '--network=host' inside the root network namespace. On
the bright side, it's very convenient for testing:

runsc --rootless do ls
runsc --rootless do curl www.google.com

PiperOrigin-RevId: 252840970

1 files changed, 12 insertions, 10 deletions

diff --git a/runsc/cmd/boot.go b/runsc/cmd/boot.go
index 3a547d4aa..e0a950e9c 100644
--- a/runsc/cmd/boot.go
+++ b/runsc/cmd/boot.go
@@ -130,6 +130,8 @@ func (b *Boot) Execute(_ context.Context, f *flag.FlagSet, args ...interface{})
 	// Ensure that if there is a panic, all goroutine stacks are printed.
 	debug.SetTraceback("all")
 
+	conf := args[0].(*boot.Config)
+
 	if b.setUpRoot {
 		if err := setUpChroot(b.pidns); err != nil {
 			Fatalf("error setting up chroot: %v", err)
@@ -143,14 +145,16 @@ func (b *Boot) Execute(_ context.Context, f *flag.FlagSet, args ...interface{})
 					args = append(args, arg)
 				}
 			}
-			// Note that we've already read the spec from the spec FD, and
-			// we will read it again after the exec call. This works
-			// because the ReadSpecFromFile function seeks to the beginning
-			// of the file before reading.
-			if err := callSelfAsNobody(args); err != nil {
-				Fatalf("%v", err)
+			if !conf.Rootless {
+				// Note that we've already read the spec from the spec FD, and
+				// we will read it again after the exec call. This works
+				// because the ReadSpecFromFile function seeks to the beginning
+				// of the file before reading.
+				if err := callSelfAsNobody(args); err != nil {
+					Fatalf("%v", err)
+				}
+				panic("callSelfAsNobody must never return success")
 			}
-			panic("callSelfAsNobody must never return success")
 		}
 	}
 
@@ -163,9 +167,6 @@ func (b *Boot) Execute(_ context.Context, f *flag.FlagSet, args ...interface{})
 	}
 	specutils.LogSpec(spec)
 
-	conf := args[0].(*boot.Config)
-	waitStatus := args[1].(*syscall.WaitStatus)
-
 	if b.applyCaps {
 		caps := spec.Process.Capabilities
 		if caps == nil {
@@ -251,6 +252,7 @@ func (b *Boot) Execute(_ context.Context, f *flag.FlagSet, args ...interface{})
 
 	ws := l.WaitExit()
 	log.Infof("application exiting with %+v", ws)
+	waitStatus := args[1].(*syscall.WaitStatus)
 	*waitStatus = syscall.WaitStatus(ws.Status())
 	l.Destroy()
 	return subcommands.ExitSuccess