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Commit 1de4f2ef authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 

Pull namespace fixes from Eric Biederman:
 "I believe all of these are simple obviously correct bug fixes. These
  fall into two groups:

   - Fixing the implementation of MNT_LOCKED which prevents lesser
     privileged users from seeing unders mounts created by more
     privileged users.

   - Fixing the extended uid and group mapping in user namespaces.

  As well as ensuring the code looks correct I have spot tested these
  changes as well and in my testing the fixes are working"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  mount: Prevent MNT_DETACH from disconnecting locked mounts
  mount: Don't allow copying MNT_UNBINDABLE|MNT_LOCKED mounts
  mount: Retest MNT_LOCKED in do_umount
  userns: also map extents in the reverse map to kernel IDs
parents a1aa42f1 9c8e0a1b

fs/namespace.c

+17 −5
Original line number Diff line number Diff line
@@ -1540,8 +1540,13 @@ static int do_umount(struct mount *mnt, int flags) 


	namespace_lock();

	lock_mount_hash();

	event++;



	/* Recheck MNT_LOCKED with the locks held */

	retval = -EINVAL;

	if (mnt->mnt.mnt_flags & MNT_LOCKED)

		goto out;



	event++;

	if (flags & MNT_DETACH) {

		if (!list_empty(&mnt->mnt_list))

			umount_tree(mnt, UMOUNT_PROPAGATE);
@@ -1555,6 +1560,7 @@ static int do_umount(struct mount *mnt, int flags) 
			retval = 0;

		}

	}

out:

	unlock_mount_hash();

	namespace_unlock();

	return retval;
@@ -1645,7 +1651,7 @@ int ksys_umount(char __user *name, int flags) 
		goto dput_and_out;

	if (!check_mnt(mnt))

		goto dput_and_out;

	if (mnt->mnt.mnt_flags & MNT_LOCKED)

	if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */

		goto dput_and_out;

	retval = -EPERM;

	if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN))
@@ -1728,9 +1734,15 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, 
		for (s = r; s; s = next_mnt(s, r)) {

			if (!(flag & CL_COPY_UNBINDABLE) &&

			    IS_MNT_UNBINDABLE(s)) {

				if (s->mnt.mnt_flags & MNT_LOCKED) {

					/* Both unbindable and locked. */

					q = ERR_PTR(-EPERM);

					goto out;

				} else {

					s = skip_mnt_tree(s);

					continue;

				}

			}

			if (!(flag & CL_COPY_MNT_NS_FILE) &&

			    is_mnt_ns_file(s->mnt.mnt_root)) {

				s = skip_mnt_tree(s);
@@ -1782,7 +1794,7 @@ void drop_collected_mounts(struct vfsmount *mnt) 
{

	namespace_lock();

	lock_mount_hash();

	umount_tree(real_mount(mnt), UMOUNT_SYNC);

	umount_tree(real_mount(mnt), 0);

	unlock_mount_hash();

	namespace_unlock();

}

kernel/user_namespace.c

+8 −4
Original line number Diff line number Diff line
@@ -974,10 +974,6 @@ static ssize_t map_write(struct file *file, const char __user *buf, 
	if (!new_idmap_permitted(file, ns, cap_setid, &new_map))

		goto out;



	ret = sort_idmaps(&new_map);

	if (ret < 0)

		goto out;



	ret = -EPERM;

	/* Map the lower ids from the parent user namespace to the

	 * kernel global id space.
@@ -1004,6 +1000,14 @@ static ssize_t map_write(struct file *file, const char __user *buf, 
		e->lower_first = lower_first;

	}



	/*

	 * If we want to use binary search for lookup, this clones the extent

	 * array and sorts both copies.

	 */

	ret = sort_idmaps(&new_map);

	if (ret < 0)

		goto out;



	/* Install the map */

	if (new_map.nr_extents <= UID_GID_MAP_MAX_BASE_EXTENTS) {

		memcpy(map->extent, new_map.extent,