kernel_optimize_test/include/linux/mount.h
Linus Torvalds 8f502d5b9e Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull usernamespace mount fixes from Eric Biederman:
 "Way back in October Andrey Vagin reported that umount(MNT_DETACH)
  could be used to defeat MNT_LOCKED.  As I worked to fix this I
  discovered that combined with mount propagation and an appropriate
  selection of shared subtrees a reference to a directory on an
  unmounted filesystem is not necessary.

  That MNT_DETACH is allowed in user namespace in a form that can break
  MNT_LOCKED comes from my early misunderstanding what MNT_DETACH does.

  To avoid breaking existing userspace the conflict between MNT_DETACH
  and MNT_LOCKED is fixed by leaving mounts that are locked to their
  parents in the mount hash table until the last reference goes away.

  While investigating this issue I also found an issue with
  __detach_mounts.  The code was unnecessarily and incorrectly
  triggering mount propagation.  Resulting in too many mounts going away
  when a directory is deleted, and too many cpu cycles are burned while
  doing that.

  Looking some more I realized that __detach_mounts by only keeping
  mounts connected that were MNT_LOCKED it had the potential to still
  leak information so I tweaked the code to keep everything locked
  together that possibly could be.

  This code was almost ready last cycle but Al invented fs_pin which
  slightly simplifies this code but required rewrites and retesting, and
  I have not been in top form for a while so it took me a while to get
  all of that done.  Similiarly this pull request is late because I have
  been feeling absolutely miserable all week.

  The issue of being able to escape a bind mount has not yet been
  addressed, as the fixes are not yet mature"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  mnt: Update detach_mounts to leave mounts connected
  mnt: Fix the error check in __detach_mounts
  mnt: Honor MNT_LOCKED when detaching mounts
  fs_pin: Allow for the possibility that m_list or s_list go unused.
  mnt: Factor umount_mnt from umount_tree
  mnt: Factor out unhash_mnt from detach_mnt and umount_tree
  mnt: Fail collect_mounts when applied to unmounted mounts
  mnt: Don't propagate unmounts to locked mounts
  mnt: On an unmount propagate clearing of MNT_LOCKED
  mnt: Delay removal from the mount hash.
  mnt: Add MNT_UMOUNT flag
  mnt: In umount_tree reuse mnt_list instead of mnt_hash
  mnt: Don't propagate umounts in __detach_mounts
  mnt: Improve the umount_tree flags
  mnt: Use hlist_move_list in namespace_unlock
2015-04-18 11:20:31 -04:00

99 lines
3.0 KiB
C

/*
*
* Definitions for mount interface. This describes the in the kernel build
* linkedlist with mounted filesystems.
*
* Author: Marco van Wieringen <mvw@planets.elm.net>
*
*/
#ifndef _LINUX_MOUNT_H
#define _LINUX_MOUNT_H
#include <linux/types.h>
#include <linux/list.h>
#include <linux/nodemask.h>
#include <linux/spinlock.h>
#include <linux/seqlock.h>
#include <linux/atomic.h>
struct super_block;
struct vfsmount;
struct dentry;
struct mnt_namespace;
#define MNT_NOSUID 0x01
#define MNT_NODEV 0x02
#define MNT_NOEXEC 0x04
#define MNT_NOATIME 0x08
#define MNT_NODIRATIME 0x10
#define MNT_RELATIME 0x20
#define MNT_READONLY 0x40 /* does the user want this to be r/o? */
#define MNT_SHRINKABLE 0x100
#define MNT_WRITE_HOLD 0x200
#define MNT_SHARED 0x1000 /* if the vfsmount is a shared mount */
#define MNT_UNBINDABLE 0x2000 /* if the vfsmount is a unbindable mount */
/*
* MNT_SHARED_MASK is the set of flags that should be cleared when a
* mount becomes shared. Currently, this is only the flag that says a
* mount cannot be bind mounted, since this is how we create a mount
* that shares events with another mount. If you add a new MNT_*
* flag, consider how it interacts with shared mounts.
*/
#define MNT_SHARED_MASK (MNT_UNBINDABLE)
#define MNT_USER_SETTABLE_MASK (MNT_NOSUID | MNT_NODEV | MNT_NOEXEC \
| MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME \
| MNT_READONLY)
#define MNT_ATIME_MASK (MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME )
#define MNT_INTERNAL_FLAGS (MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL | \
MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED)
#define MNT_INTERNAL 0x4000
#define MNT_LOCK_ATIME 0x040000
#define MNT_LOCK_NOEXEC 0x080000
#define MNT_LOCK_NOSUID 0x100000
#define MNT_LOCK_NODEV 0x200000
#define MNT_LOCK_READONLY 0x400000
#define MNT_LOCKED 0x800000
#define MNT_DOOMED 0x1000000
#define MNT_SYNC_UMOUNT 0x2000000
#define MNT_MARKED 0x4000000
#define MNT_UMOUNT 0x8000000
struct vfsmount {
struct dentry *mnt_root; /* root of the mounted tree */
struct super_block *mnt_sb; /* pointer to superblock */
int mnt_flags;
};
struct file; /* forward dec */
struct path;
extern int mnt_want_write(struct vfsmount *mnt);
extern int mnt_want_write_file(struct file *file);
extern int mnt_clone_write(struct vfsmount *mnt);
extern void mnt_drop_write(struct vfsmount *mnt);
extern void mnt_drop_write_file(struct file *file);
extern void mntput(struct vfsmount *mnt);
extern struct vfsmount *mntget(struct vfsmount *mnt);
extern struct vfsmount *mnt_clone_internal(struct path *path);
extern int __mnt_is_readonly(struct vfsmount *mnt);
struct path;
extern struct vfsmount *clone_private_mount(struct path *path);
struct file_system_type;
extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
int flags, const char *name,
void *data);
extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
extern void mark_mounts_for_expiry(struct list_head *mounts);
extern dev_t name_to_dev_t(const char *name);
#endif /* _LINUX_MOUNT_H */