Merge pull request #280 from crosbymichael/stdio-perms

Fix STDIO permissions when container user not root

libcontainer/init_linux.go

@@ -187,7 +187,17 @@ func setupUser(config *initConfig) error {
 			return err
 		}
 	}
-
+	// change the permissions on the STDIO of the current process so that when the user
+	// is changed for the container, it's STDIO of the process matches the user.
+	for _, fd := range []uintptr{
+		os.Stdin.Fd(),
+		os.Stderr.Fd(),
+		os.Stdout.Fd(),
+	} {
+		if err := syscall.Fchown(int(fd), execUser.Uid, execUser.Gid); err != nil {
+			return err
+		}
+	}
 	suppGroups := append(execUser.Sgids, addGroups...)
 	if err := syscall.Setgroups(suppGroups); err != nil {
 		return err

libcontainer/integration/exec_test.go

@@ -994,3 +994,23 @@ func TestHook(t *testing.T) {
 		t.Fatalf("expected file to not exist, got %s", fi.Name())
 	}
 }
+
+func TestSTDIOPermissions(t *testing.T) {
+	if testing.Short() {
+		return
+	}
+
+	rootfs, err := newRootfs()
+	ok(t, err)
+	defer remove(rootfs)
+	config := newTemplateConfig(rootfs)
+	buffers, exitCode, err := runContainer(config, "", "sh", "-c", "echo hi > /dev/stderr")
+	ok(t, err)
+	if exitCode != 0 {
+		t.Fatalf("exit code not 0. code %d stderr %q", exitCode, buffers.Stderr)
+	}
+
+	if actual := strings.Trim(buffers.Stderr.String(), "\n"); actual != "hi" {
+		t.Fatalf("stderr should equal be equal %q %q", actual, "hi")
+	}
+}