From 1cc2f74ce5603432ba9d5ea9d39cdf3d9eb3fbfe Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Wed, 13 Mar 2013 11:51:49 -0700
Subject: [PATCH] --- yaml --- r: 361207 b: refs/heads/master c:
 e66eded8309ebf679d3d3c1f5820d1f2ca332c71 h: refs/heads/master i:   361205:
 0cd15911d5b39e50d6673ca1216e3fc001c0e217   361203:
 c833f19932f4f2f2dac35b124c9b6eea4868e78b   361199:
 75d726f29174b33ee7dd42fc0a9aa2f7a8655406 v: v3

---
 [refs]                        | 2 +-
 trunk/kernel/fork.c           | 5 ++++-
 trunk/kernel/user_namespace.c | 4 ++++
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index c4706496b451..aae13e22c280 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 6c23cbbd5056b155401b0a2b5567d530e6c750c4
+refs/heads/master: e66eded8309ebf679d3d3c1f5820d1f2ca332c71
diff --git a/trunk/kernel/fork.c b/trunk/kernel/fork.c
index 8d932b1c9056..1766d324d5e3 100644
--- a/trunk/kernel/fork.c
+++ b/trunk/kernel/fork.c
@@ -1141,6 +1141,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 	if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
 		return ERR_PTR(-EINVAL);
 
+	if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
+		return ERR_PTR(-EINVAL);
+
 	/*
 	 * Thread groups must share signals as well, and detached threads
 	 * can only be started up within the thread group.
@@ -1807,7 +1810,7 @@ SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
 	 * If unsharing a user namespace must also unshare the thread.
 	 */
 	if (unshare_flags & CLONE_NEWUSER)
-		unshare_flags |= CLONE_THREAD;
+		unshare_flags |= CLONE_THREAD | CLONE_FS;
 	/*
 	 * If unsharing a pid namespace must also unshare the thread.
 	 */
diff --git a/trunk/kernel/user_namespace.c b/trunk/kernel/user_namespace.c
index 8b650837083e..b14f4d342043 100644
--- a/trunk/kernel/user_namespace.c
+++ b/trunk/kernel/user_namespace.c
@@ -21,6 +21,7 @@
 #include <linux/uaccess.h>
 #include <linux/ctype.h>
 #include <linux/projid.h>
+#include <linux/fs_struct.h>
 
 static struct kmem_cache *user_ns_cachep __read_mostly;
 
@@ -837,6 +838,9 @@ static int userns_install(struct nsproxy *nsproxy, void *ns)
 	if (atomic_read(&current->mm->mm_users) > 1)
 		return -EINVAL;
 
+	if (current->fs->users != 1)
+		return -EINVAL;
+
 	if (!ns_capable(user_ns, CAP_SYS_ADMIN))
 		return -EPERM;