From 132c94e31b8bca8ea921f9f96a57d684fa4ae0a9 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Fri, 22 Mar 2013 04:08:05 -0700
Subject: vfs: Carefully propogate mounts across user namespaces
As a matter of policy MNT_READONLY should not be changable if the
original mounter had more privileges than creator of the mount
namespace.
Add the flag CL_UNPRIVILEGED to note when we are copying a mount from
a mount namespace that requires more privileges to a mount namespace
that requires fewer privileges.
When the CL_UNPRIVILEGED flag is set cause clone_mnt to set MNT_NO_REMOUNT
if any of the mnt flags that should never be changed are set.
This protects both mount propagation and the initial creation of a less
privileged mount namespace.
Cc: stable@vger.kernel.org
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/pnode.h | 1 +
1 file changed, 1 insertion(+)
(limited to 'fs/pnode.h')
diff --git a/fs/pnode.h b/fs/pnode.h
index 19b853a3445c..a0493d5ebfbf 100644
--- a/fs/pnode.h
+++ b/fs/pnode.h
@@ -23,6 +23,7 @@
#define CL_MAKE_SHARED 0x08
#define CL_PRIVATE 0x10
#define CL_SHARED_TO_SLAVE 0x20
+#define CL_UNPRIVILEGED 0x40
static inline void set_mnt_shared(struct mount *mnt)
{
--
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