linux/fs/pnode.h
Eric W. Biederman 132c94e31b 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>
2013-03-27 07:50:05 -07:00

49 lines
1.5 KiB
C

/*
* linux/fs/pnode.h
*
* (C) Copyright IBM Corporation 2005.
* Released under GPL v2.
*
*/
#ifndef _LINUX_PNODE_H
#define _LINUX_PNODE_H
#include <linux/list.h>
#include "mount.h"
#define IS_MNT_SHARED(m) ((m)->mnt.mnt_flags & MNT_SHARED)
#define IS_MNT_SLAVE(m) ((m)->mnt_master)
#define IS_MNT_NEW(m) (!(m)->mnt_ns)
#define CLEAR_MNT_SHARED(m) ((m)->mnt.mnt_flags &= ~MNT_SHARED)
#define IS_MNT_UNBINDABLE(m) ((m)->mnt.mnt_flags & MNT_UNBINDABLE)
#define CL_EXPIRE 0x01
#define CL_SLAVE 0x02
#define CL_COPY_ALL 0x04
#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)
{
mnt->mnt.mnt_flags &= ~MNT_SHARED_MASK;
mnt->mnt.mnt_flags |= MNT_SHARED;
}
void change_mnt_propagation(struct mount *, int);
int propagate_mnt(struct mount *, struct dentry *, struct mount *,
struct list_head *);
int propagate_umount(struct list_head *);
int propagate_mount_busy(struct mount *, int);
void mnt_release_group_id(struct mount *);
int get_dominating_id(struct mount *mnt, const struct path *root);
unsigned int mnt_get_count(struct mount *mnt);
void mnt_set_mountpoint(struct mount *, struct dentry *,
struct mount *);
void release_mounts(struct list_head *);
void umount_tree(struct mount *, int, struct list_head *);
struct mount *copy_tree(struct mount *, struct dentry *, int);
bool is_path_reachable(struct mount *, struct dentry *,
const struct path *root);
#endif /* _LINUX_PNODE_H */