From 04da969aa8b85ade0d226d111129e66b0e4e852c Mon Sep 17 00:00:00 2001
From: Tonis Tiigi <tonistiigi@gmail.com>
Date: Thu, 10 Mar 2016 22:23:38 -0800
Subject: [PATCH] Clear groups after entering userns

Clears supplementary groups that have effect on the
mount permissions before joining the user specified
groups happens.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>
---
 libcontainer/nsenter/nsexec.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libcontainer/nsenter/nsexec.c b/libcontainer/nsenter/nsexec.c
index a52b7dc37..ee51c4753 100644
--- a/libcontainer/nsenter/nsexec.c
+++ b/libcontainer/nsenter/nsexec.c
@@ -16,6 +16,7 @@
 #include <sys/types.h>
 #include <sys/prctl.h>
 #include <unistd.h>
+#include <grp.h>
 
 #include <bits/sockaddr.h>
 #include <linux/types.h>
@@ -383,6 +384,11 @@ static void process_nl_attributes(int pipenum, char *data, int data_size)
 			pr_perror("setgid failed");
 			exit(1);
 		}
+    
+		if (setgroups(0, NULL) == -1) {
+			pr_perror("setgroups failed");
+			exit(1);
+		}
 
 		if (consolefd != -1) {
 			if (ioctl(consolefd, TIOCSCTTY, 0) == -1) {