Commit message: 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>
CVE: CVE-2013-1957
CWE: CWE-264
Vulnerability description: The clone_mnt function in fs/namespace.c in the Linux kernel before 3.8.6 does not properly restrict changes to the MNT_READONLY flag, which allows local users to bypass an intended read-only property of a filesystem by leveraging a separate mount namespace.

Project: linux
File: namespace.c

SYSCALL_DEFINE1(oldumount, char __user *, name)
{
	return sys_umount(name, 0);
}

Project: linux
File: namespace.c

SYSCALL_DEFINE2(umount, char __user *, name, int, flags)
{
	struct path path;
	struct mount *mnt;
	int retval;
	int lookup_flags = 0;

	if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))
		return -EINVAL;

	if (!may_mount())
		return -EPERM;

	if (!(flags & UMOUNT_NOFOLLOW))
		lookup_flags |= LOOKUP_FOLLOW;

	retval = user_path_at(AT_FDCWD, name, lookup_flags, &path);
	if (retval)
		goto out;
	mnt = real_mount(path.mnt);
	retval = -EINVAL;
	if (path.dentry != path.mnt->mnt_root)
		goto dput_and_out;
	if (!check_mnt(mnt))
		goto dput_and_out;

	retval = do_umount(mnt, flags);
dput_and_out:
	/* we mustn't call path_put() as that would clear mnt_expiry_mark */
	dput(path.dentry);
	mntput_no_expire(mnt);
out:
	return retval;
}

Project: linux
File: namespace.c

SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
		const char __user *, put_old)
{
	struct path new, old, parent_path, root_parent, root;
	struct mount *new_mnt, *root_mnt;
	int error;

	if (!may_mount())
		return -EPERM;

	error = user_path_dir(new_root, &new);
	if (error)
		goto out0;

	error = user_path_dir(put_old, &old);
	if (error)
		goto out1;

	error = security_sb_pivotroot(&old, &new);
	if (error)
		goto out2;

	get_fs_root(current->fs, &root);
	error = lock_mount(&old);
	if (error)
		goto out3;

	error = -EINVAL;
	new_mnt = real_mount(new.mnt);
	root_mnt = real_mount(root.mnt);
	if (IS_MNT_SHARED(real_mount(old.mnt)) ||
		IS_MNT_SHARED(new_mnt->mnt_parent) ||
		IS_MNT_SHARED(root_mnt->mnt_parent))
		goto out4;
	if (!check_mnt(root_mnt) || !check_mnt(new_mnt))
		goto out4;
	error = -ENOENT;
	if (d_unlinked(new.dentry))
		goto out4;
	if (d_unlinked(old.dentry))
		goto out4;
	error = -EBUSY;
	if (new.mnt == root.mnt ||
	    old.mnt == root.mnt)
		goto out4; /* loop, on the same file system  */
	error = -EINVAL;
	if (root.mnt->mnt_root != root.dentry)
		goto out4; /* not a mountpoint */
	if (!mnt_has_parent(root_mnt))
		goto out4; /* not attached */
	if (new.mnt->mnt_root != new.dentry)
		goto out4; /* not a mountpoint */
	if (!mnt_has_parent(new_mnt))
		goto out4; /* not attached */
	/* make sure we can reach put_old from new_root */
	if (!is_path_reachable(real_mount(old.mnt), old.dentry, &new))
		goto out4;
	br_write_lock(&vfsmount_lock);
	detach_mnt(new_mnt, &parent_path);
	detach_mnt(root_mnt, &root_parent);
	/* mount old root on put_old */
	attach_mnt(root_mnt, &old);
	/* mount new_root on / */
	attach_mnt(new_mnt, &root_parent);
	touch_mnt_namespace(current->nsproxy->mnt_ns);
	br_write_unlock(&vfsmount_lock);
	chroot_fs_refs(&root, &new);
	error = 0;
out4:
	unlock_mount(&old);
	if (!error) {
		path_put(&root_parent);
		path_put(&parent_path);
	}
out3:
	path_put(&root);
out2:
	path_put(&old);
out1:
	path_put(&new);
out0:
	return error;
}

Project: linux
File: namespace.c

SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name,
		char __user *, type, unsigned long, flags, void __user *, data)
{
	int ret;
	char *kernel_type;
	struct filename *kernel_dir;
	char *kernel_dev;
	unsigned long data_page;

	ret = copy_mount_string(type, &kernel_type);
	if (ret < 0)
		goto out_type;

	kernel_dir = getname(dir_name);
	if (IS_ERR(kernel_dir)) {
		ret = PTR_ERR(kernel_dir);
		goto out_dir;
	}

	ret = copy_mount_string(dev_name, &kernel_dev);
	if (ret < 0)
		goto out_dev;

	ret = copy_mount_options(data, &data_page);
	if (ret < 0)
		goto out_data;

	ret = do_mount(kernel_dev, kernel_dir->name, kernel_type, flags,
		(void *) data_page);

	free_page(data_page);
out_data:
	kfree(kernel_dev);
out_dev:
	putname(kernel_dir);
out_dir:
	kfree(kernel_type);
out_type:
	return ret;
}

Project: linux
File: namespace.c

void __mnt_drop_write(struct vfsmount *mnt)
{
	preempt_disable();
	mnt_dec_writers(real_mount(mnt));
	preempt_enable();
}

Project: linux
File: namespace.c

void __mnt_drop_write_file(struct file *file)
{
	__mnt_drop_write(file->f_path.mnt);
}

Project: linux
File: namespace.c

int __mnt_is_readonly(struct vfsmount *mnt)
{
	if (mnt->mnt_flags & MNT_READONLY)
		return 1;
	if (mnt->mnt_sb->s_flags & MS_RDONLY)
		return 1;
	return 0;
}

Project: linux
File: namespace.c

static void __mnt_unmake_readonly(struct mount *mnt)
{
	br_write_lock(&vfsmount_lock);
	mnt->mnt.mnt_flags &= ~MNT_READONLY;
	br_write_unlock(&vfsmount_lock);
}

Project: linux
File: namespace.c

int __mnt_want_write(struct vfsmount *m)
{
	struct mount *mnt = real_mount(m);
	int ret = 0;

	preempt_disable();
	mnt_inc_writers(mnt);
	/*
	 * The store to mnt_inc_writers must be visible before we pass
	 * MNT_WRITE_HOLD loop below, so that the slowpath can see our
	 * incremented count after it has set MNT_WRITE_HOLD.
	 */
	smp_mb();
	while (ACCESS_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD)
		cpu_relax();
	/*
	 * After the slowpath clears MNT_WRITE_HOLD, mnt_is_readonly will
	 * be set to match its requirements. So we must not load that until
	 * MNT_WRITE_HOLD is cleared.
	 */
	smp_rmb();
	if (mnt_is_readonly(m)) {
		mnt_dec_writers(mnt);
		ret = -EROFS;
	}
	preempt_enable();

	return ret;
}

Project: linux
File: namespace.c

int __mnt_want_write_file(struct file *file)
{
	struct inode *inode = file_inode(file);

	if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode))
		return __mnt_want_write(file->f_path.mnt);
	else
		return mnt_clone_write(file->f_path.mnt);
}

Project: linux
File: namespace.c

static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns)
{
	struct mnt_namespace *new_ns;
	int ret;

	new_ns = kmalloc(sizeof(struct mnt_namespace), GFP_KERNEL);
	if (!new_ns)
		return ERR_PTR(-ENOMEM);
	ret = proc_alloc_inum(&new_ns->proc_inum);
	if (ret) {
		kfree(new_ns);
		return ERR_PTR(ret);
	}
	new_ns->seq = atomic64_add_return(1, &mnt_ns_seq);
	atomic_set(&new_ns->count, 1);
	new_ns->root = NULL;
	INIT_LIST_HEAD(&new_ns->list);
	init_waitqueue_head(&new_ns->poll);
	new_ns->event = 0;
	new_ns->user_ns = get_user_ns(user_ns);
	return new_ns;
}

Project: linux
File: namespace.c

static struct mount *alloc_vfsmnt(const char *name)
{
	struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
	if (mnt) {
		int err;

		err = mnt_alloc_id(mnt);
		if (err)
			goto out_free_cache;

		if (name) {
			mnt->mnt_devname = kstrdup(name, GFP_KERNEL);
			if (!mnt->mnt_devname)
				goto out_free_id;
		}

#ifdef CONFIG_SMP
		mnt->mnt_pcp = alloc_percpu(struct mnt_pcp);
		if (!mnt->mnt_pcp)
			goto out_free_devname;

		this_cpu_add(mnt->mnt_pcp->mnt_count, 1);
#else
		mnt->mnt_count = 1;
		mnt->mnt_writers = 0;
#endif

		INIT_LIST_HEAD(&mnt->mnt_hash);
		INIT_LIST_HEAD(&mnt->mnt_child);
		INIT_LIST_HEAD(&mnt->mnt_mounts);
		INIT_LIST_HEAD(&mnt->mnt_list);
		INIT_LIST_HEAD(&mnt->mnt_expire);
		INIT_LIST_HEAD(&mnt->mnt_share);
		INIT_LIST_HEAD(&mnt->mnt_slave_list);
		INIT_LIST_HEAD(&mnt->mnt_slave);
#ifdef CONFIG_FSNOTIFY
		INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks);
#endif
	}
	return mnt;

#ifdef CONFIG_SMP
out_free_devname:
	kfree(mnt->mnt_devname);
#endif
out_free_id:
	mnt_free_id(mnt);
out_free_cache:
	kmem_cache_free(mnt_cache, mnt);
	return NULL;
}

Project: linux
File: namespace.c

static void attach_mnt(struct mount *mnt, struct path *path)
{
	mnt_set_mountpoint(real_mount(path->mnt), path->dentry, mnt);
	list_add_tail(&mnt->mnt_hash, mount_hashtable +
			hash(path->mnt, path->dentry));
	list_add_tail(&mnt->mnt_child, &real_mount(path->mnt)->mnt_mounts);
}

Project: linux
File: namespace.c

static int attach_recursive_mnt(struct mount *source_mnt,
			struct path *path, struct path *parent_path)
{
	LIST_HEAD(tree_list);
	struct mount *dest_mnt = real_mount(path->mnt);
	struct dentry *dest_dentry = path->dentry;
	struct mount *child, *p;
	int err;

	if (IS_MNT_SHARED(dest_mnt)) {
		err = invent_group_ids(source_mnt, true);
		if (err)
			goto out;
	}
	err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list);
	if (err)
		goto out_cleanup_ids;

	br_write_lock(&vfsmount_lock);

	if (IS_MNT_SHARED(dest_mnt)) {
		for (p = source_mnt; p; p = next_mnt(p, source_mnt))
			set_mnt_shared(p);
	}
	if (parent_path) {
		detach_mnt(source_mnt, parent_path);
		attach_mnt(source_mnt, path);
		touch_mnt_namespace(source_mnt->mnt_ns);
	} else {
		mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
		commit_tree(source_mnt);
	}

	list_for_each_entry_safe(child, p, &tree_list, mnt_hash) {
		list_del_init(&child->mnt_hash);
		commit_tree(child);
	}
	br_write_unlock(&vfsmount_lock);

	return 0;

 out_cleanup_ids:
	if (IS_MNT_SHARED(dest_mnt))
		cleanup_group_ids(source_mnt, NULL);
 out:
	return err;
}

Project: linux
File: namespace.c

static inline int check_mnt(struct mount *mnt)
{
	return mnt->mnt_ns == current->nsproxy->mnt_ns;
}

Project: linux
File: namespace.c

static void cleanup_group_ids(struct mount *mnt, struct mount *end)
{
	struct mount *p;

	for (p = mnt; p != end; p = next_mnt(p, mnt)) {
		if (p->mnt_group_id && !IS_MNT_SHARED(p))
			mnt_release_group_id(p);
	}
}

Project: linux
File: namespace.c

struct vfsmount *collect_mounts(struct path *path)
{
	struct mount *tree;
	down_write(&namespace_sem);
	tree = copy_tree(real_mount(path->mnt), path->dentry,
			 CL_COPY_ALL | CL_PRIVATE);
	up_write(&namespace_sem);
	if (IS_ERR(tree))
		return NULL;
	return &tree->mnt;
}

Project: linux
File: namespace.c

static void commit_tree(struct mount *mnt)
{
	struct mount *parent = mnt->mnt_parent;
	struct mount *m;
	LIST_HEAD(head);
	struct mnt_namespace *n = parent->mnt_ns;

	BUG_ON(parent == mnt);

	list_add_tail(&head, &mnt->mnt_list);
	list_for_each_entry(m, &head, mnt_list)
		m->mnt_ns = n;

	list_splice(&head, n->list.prev);

	list_add_tail(&mnt->mnt_hash, mount_hashtable +
				hash(&parent->mnt, mnt->mnt_mountpoint));
	list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
	touch_mnt_namespace(n);
}

Project: linux
File: namespace.c

struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
		struct user_namespace *user_ns, struct fs_struct *new_fs)
{
	struct mnt_namespace *new_ns;

	BUG_ON(!ns);
	get_mnt_ns(ns);

	if (!(flags & CLONE_NEWNS))
		return ns;

	new_ns = dup_mnt_ns(ns, user_ns, new_fs);

	put_mnt_ns(ns);
	return new_ns;
}

Project: linux
File: namespace.c

int copy_mount_options(const void __user * data, unsigned long *where)
{
	int i;
	unsigned long page;
	unsigned long size;

	*where = 0;
	if (!data)
		return 0;

	if (!(page = __get_free_page(GFP_KERNEL)))
		return -ENOMEM;

	/* We only care that *some* data at the address the user
	 * gave us is valid.  Just in case, we'll zero
	 * the remainder of the page.
	 */
	/* copy_from_user cannot cross TASK_SIZE ! */
	size = TASK_SIZE - (unsigned long)data;
	if (size > PAGE_SIZE)
		size = PAGE_SIZE;

	i = size - exact_copy_from_user((void *)page, data, size);
	if (!i) {
		free_page(page);
		return -EFAULT;
	}
	if (i != PAGE_SIZE)
		memset((char *)page + i, 0, PAGE_SIZE - i);
	*where = page;
	return 0;
}

Project: linux
File: namespace.c

int copy_mount_string(const void __user *data, char **where)
{
	char *tmp;

	if (!data) {
		*where = NULL;
		return 0;
	}

	tmp = strndup_user(data, PAGE_SIZE);
	if (IS_ERR(tmp))
		return PTR_ERR(tmp);

	*where = tmp;
	return 0;
}

Project: linux
File: namespace.c

struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,
					int flag)
{
	struct mount *res, *p, *q, *r;
	struct path path;

	if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
		return ERR_PTR(-EINVAL);

	res = q = clone_mnt(mnt, dentry, flag);
	if (IS_ERR(q))
		return q;

	q->mnt_mountpoint = mnt->mnt_mountpoint;

	p = mnt;
	list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) {
		struct mount *s;
		if (!is_subdir(r->mnt_mountpoint, dentry))
			continue;

		for (s = r; s; s = next_mnt(s, r)) {
			if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(s)) {
				s = skip_mnt_tree(s);
				continue;
			}
			while (p != s->mnt_parent) {
				p = p->mnt_parent;
				q = q->mnt_parent;
			}
			p = s;
			path.mnt = &q->mnt;
			path.dentry = p->mnt_mountpoint;
			q = clone_mnt(p, p->mnt.mnt_root, flag);
			if (IS_ERR(q))
				goto out;
			br_write_lock(&vfsmount_lock);
			list_add_tail(&q->mnt_list, &res->mnt_list);
			attach_mnt(q, &path);
			br_write_unlock(&vfsmount_lock);
		}
	}
	return res;
out:
	if (res) {
		LIST_HEAD(umount_list);
		br_write_lock(&vfsmount_lock);
		umount_tree(res, 0, &umount_list);
		br_write_unlock(&vfsmount_lock);
		release_mounts(&umount_list);
	}
	return q;
}

Project: linux
File: namespace.c

static struct mnt_namespace *create_mnt_ns(struct vfsmount *m)
{
	struct mnt_namespace *new_ns = alloc_mnt_ns(&init_user_ns);
	if (!IS_ERR(new_ns)) {
		struct mount *mnt = real_mount(m);
		mnt->mnt_ns = new_ns;
		new_ns->root = mnt;
		list_add(&new_ns->list, &mnt->mnt_list);
	} else {
		mntput(m);
	}
	return new_ns;
}

Project: linux
File: namespace.c

bool current_chrooted(void)
{
	/* Does the current process have a non-standard root */
	struct path ns_root;
	struct path fs_root;
	bool chrooted;

	/* Find the namespace root */
	ns_root.mnt = &current->nsproxy->mnt_ns->root->mnt;
	ns_root.dentry = ns_root.mnt->mnt_root;
	path_get(&ns_root);
	while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root))
		;

	get_fs_root(current->fs, &fs_root);

	chrooted = !path_equal(&fs_root, &ns_root);

	path_put(&fs_root);
	path_put(&ns_root);

	return chrooted;
}

Project: linux
File: namespace.c

static void dentry_reset_mounted(struct dentry *dentry)
{
	unsigned u;

	for (u = 0; u < HASH_SIZE; u++) {
		struct mount *p;

		list_for_each_entry(p, &mount_hashtable[u], mnt_hash) {
			if (p->mnt_mountpoint == dentry)
				return;
		}
	}
	spin_lock(&dentry->d_lock);
	dentry->d_flags &= ~DCACHE_MOUNTED;
	spin_unlock(&dentry->d_lock);
}

Project: linux
File: namespace.c

static void detach_mnt(struct mount *mnt, struct path *old_path)
{
	old_path->dentry = mnt->mnt_mountpoint;
	old_path->mnt = &mnt->mnt_parent->mnt;
	mnt->mnt_parent = mnt;
	mnt->mnt_mountpoint = mnt->mnt.mnt_root;
	list_del_init(&mnt->mnt_child);
	list_del_init(&mnt->mnt_hash);
	dentry_reset_mounted(old_path->dentry);
}

Project: linux
File: namespace.c

static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags)
{
	int err;

	mnt_flags &= ~(MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL);

	err = lock_mount(path);
	if (err)
		return err;

	err = -EINVAL;
	if (unlikely(!check_mnt(real_mount(path->mnt)))) {
		/* that's acceptable only for automounts done in private ns */
		if (!(mnt_flags & MNT_SHRINKABLE))
			goto unlock;
		/* ... and for those we'd better have mountpoint still alive */
		if (!real_mount(path->mnt)->mnt_ns)
			goto unlock;
	}

	/* Refuse the same filesystem on the same mount point */
	err = -EBUSY;
	if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb &&
	    path->mnt->mnt_root == path->dentry)
		goto unlock;

	err = -EINVAL;
	if (S_ISLNK(newmnt->mnt.mnt_root->d_inode->i_mode))
		goto unlock;

	newmnt->mnt.mnt_flags = mnt_flags;
	err = graft_tree(newmnt, path);

unlock:
	unlock_mount(path);
	return err;
}

Project: linux
File: namespace.c

static int do_change_type(struct path *path, int flag)
{
	struct mount *m;
	struct mount *mnt = real_mount(path->mnt);
	int recurse = flag & MS_REC;
	int type;
	int err = 0;

	if (path->dentry != path->mnt->mnt_root)
		return -EINVAL;

	type = flags_to_propagation_type(flag);
	if (!type)
		return -EINVAL;

	down_write(&namespace_sem);
	if (type == MS_SHARED) {
		err = invent_group_ids(mnt, recurse);
		if (err)
			goto out_unlock;
	}

	br_write_lock(&vfsmount_lock);
	for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL))
		change_mnt_propagation(m, type);
	br_write_unlock(&vfsmount_lock);

 out_unlock:
	up_write(&namespace_sem);
	return err;
}

Project: linux
File: namespace.c

static int do_loopback(struct path *path, const char *old_name,
				int recurse)
{
	LIST_HEAD(umount_list);
	struct path old_path;
	struct mount *mnt = NULL, *old;
	int err;
	if (!old_name || !*old_name)
		return -EINVAL;
	err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path);
	if (err)
		return err;

	err = -EINVAL;
	if (mnt_ns_loop(&old_path))
		goto out; 

	err = lock_mount(path);
	if (err)
		goto out;

	old = real_mount(old_path.mnt);

	err = -EINVAL;
	if (IS_MNT_UNBINDABLE(old))
		goto out2;

	if (!check_mnt(real_mount(path->mnt)) || !check_mnt(old))
		goto out2;

	if (recurse)
		mnt = copy_tree(old, old_path.dentry, 0);
	else
		mnt = clone_mnt(old, old_path.dentry, 0);

	if (IS_ERR(mnt)) {
		err = PTR_ERR(mnt);
		goto out;
	}

	err = graft_tree(mnt, path);
	if (err) {
		br_write_lock(&vfsmount_lock);
		umount_tree(mnt, 0, &umount_list);
		br_write_unlock(&vfsmount_lock);
	}
out2:
	unlock_mount(path);
	release_mounts(&umount_list);
out:
	path_put(&old_path);
	return err;
}

Project: linux
File: namespace.c

long do_mount(const char *dev_name, const char *dir_name,
		const char *type_page, unsigned long flags, void *data_page)
{
	struct path path;
	int retval = 0;
	int mnt_flags = 0;

	/* Discard magic */
	if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
		flags &= ~MS_MGC_MSK;

	/* Basic sanity checks */

	if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE))
		return -EINVAL;

	if (data_page)
		((char *)data_page)[PAGE_SIZE - 1] = 0;

	/* ... and get the mountpoint */
	retval = kern_path(dir_name, LOOKUP_FOLLOW, &path);
	if (retval)
		return retval;

	retval = security_sb_mount(dev_name, &path,
				   type_page, flags, data_page);
	if (retval)
		goto dput_out;

	if (!may_mount())
		return -EPERM;

	/* Default to relatime unless overriden */
	if (!(flags & MS_NOATIME))
		mnt_flags |= MNT_RELATIME;

	/* Separate the per-mountpoint flags */
	if (flags & MS_NOSUID)
		mnt_flags |= MNT_NOSUID;
	if (flags & MS_NODEV)
		mnt_flags |= MNT_NODEV;
	if (flags & MS_NOEXEC)
		mnt_flags |= MNT_NOEXEC;
	if (flags & MS_NOATIME)
		mnt_flags |= MNT_NOATIME;
	if (flags & MS_NODIRATIME)
		mnt_flags |= MNT_NODIRATIME;
	if (flags & MS_STRICTATIME)
		mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME);
	if (flags & MS_RDONLY)
		mnt_flags |= MNT_READONLY;

	flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN |
		   MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT |
		   MS_STRICTATIME);

	if (flags & MS_REMOUNT)
		retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags,
				    data_page);
	else if (flags & MS_BIND)
		retval = do_loopback(&path, dev_name, flags & MS_REC);
	else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
		retval = do_change_type(&path, flags);
	else if (flags & MS_MOVE)
		retval = do_move_mount(&path, dev_name);
	else
		retval = do_new_mount(&path, type_page, flags, mnt_flags,
				      dev_name, data_page);
dput_out:
	path_put(&path);
	return retval;
}

Project: linux
File: namespace.c

static int do_remount(struct path *path, int flags, int mnt_flags,
		      void *data)
{
	int err;
	struct super_block *sb = path->mnt->mnt_sb;
	struct mount *mnt = real_mount(path->mnt);

	if (!check_mnt(mnt))
		return -EINVAL;

	if (path->dentry != path->mnt->mnt_root)
		return -EINVAL;

	err = security_sb_remount(sb, data);
	if (err)
		return err;

	down_write(&sb->s_umount);
	if (flags & MS_BIND)
		err = change_mount_flags(path->mnt, flags);
	else if (!capable(CAP_SYS_ADMIN))
		err = -EPERM;
	else
		err = do_remount_sb(sb, flags, data, 0);
	if (!err) {
		br_write_lock(&vfsmount_lock);
		mnt_flags |= mnt->mnt.mnt_flags & MNT_PROPAGATION_MASK;
		mnt->mnt.mnt_flags = mnt_flags;
		br_write_unlock(&vfsmount_lock);
	}
	up_write(&sb->s_umount);
	if (!err) {
		br_write_lock(&vfsmount_lock);
		touch_mnt_namespace(mnt->mnt_ns);
		br_write_unlock(&vfsmount_lock);
	}
	return err;
}

Project: linux
File: namespace.c

static int do_umount(struct mount *mnt, int flags)
{
	struct super_block *sb = mnt->mnt.mnt_sb;
	int retval;
	LIST_HEAD(umount_list);

	retval = security_sb_umount(&mnt->mnt, flags);
	if (retval)
		return retval;

	/*
	 * Allow userspace to request a mountpoint be expired rather than
	 * unmounting unconditionally. Unmount only happens if:
	 *  (1) the mark is already set (the mark is cleared by mntput())
	 *  (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount]
	 */
	if (flags & MNT_EXPIRE) {
		if (&mnt->mnt == current->fs->root.mnt ||
		    flags & (MNT_FORCE | MNT_DETACH))
			return -EINVAL;

		/*
		 * probably don't strictly need the lock here if we examined
		 * all race cases, but it's a slowpath.
		 */
		br_write_lock(&vfsmount_lock);
		if (mnt_get_count(mnt) != 2) {
			br_write_unlock(&vfsmount_lock);
			return -EBUSY;
		}
		br_write_unlock(&vfsmount_lock);

		if (!xchg(&mnt->mnt_expiry_mark, 1))
			return -EAGAIN;
	}

	/*
	 * If we may have to abort operations to get out of this
	 * mount, and they will themselves hold resources we must
	 * allow the fs to do things. In the Unix tradition of
	 * 'Gee thats tricky lets do it in userspace' the umount_begin
	 * might fail to complete on the first run through as other tasks
	 * must return, and the like. Thats for the mount program to worry
	 * about for the moment.
	 */

	if (flags & MNT_FORCE && sb->s_op->umount_begin) {
		sb->s_op->umount_begin(sb);
	}

	/*
	 * No sense to grab the lock for this test, but test itself looks
	 * somewhat bogus. Suggestions for better replacement?
	 * Ho-hum... In principle, we might treat that as umount + switch
	 * to rootfs. GC would eventually take care of the old vfsmount.
	 * Actually it makes sense, especially if rootfs would contain a
	 * /reboot - static binary that would close all descriptors and
	 * call reboot(9). Then init(8) could umount root and exec /reboot.
	 */
	if (&mnt->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) {
		/*
		 * Special case for "unmounting" root ...
		 * we just try to remount it readonly.
		 */
		down_write(&sb->s_umount);
		if (!(sb->s_flags & MS_RDONLY))
			retval = do_remount_sb(sb, MS_RDONLY, NULL, 0);
		up_write(&sb->s_umount);
		return retval;
	}

	down_write(&namespace_sem);
	br_write_lock(&vfsmount_lock);
	event++;

	if (!(flags & MNT_DETACH))
		shrink_submounts(mnt, &umount_list);

	retval = -EBUSY;
	if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) {
		if (!list_empty(&mnt->mnt_list))
			umount_tree(mnt, 1, &umount_list);
		retval = 0;
	}
	br_write_unlock(&vfsmount_lock);
	up_write(&namespace_sem);
	release_mounts(&umount_list);
	return retval;
}

Project: linux
File: namespace.c

void drop_collected_mounts(struct vfsmount *mnt)
{
	LIST_HEAD(umount_list);
	down_write(&namespace_sem);
	br_write_lock(&vfsmount_lock);
	umount_tree(real_mount(mnt), 0, &umount_list);
	br_write_unlock(&vfsmount_lock);
	up_write(&namespace_sem);
	release_mounts(&umount_list);
}

Project: linux
File: namespace.c

static long exact_copy_from_user(void *to, const void __user * from,
				 unsigned long n)
{
	char *t = to;
	const char __user *f = from;
	char c;

	if (!access_ok(VERIFY_READ, from, n))
		return n;

	while (n) {
		if (__get_user(c, f)) {
			memset(t, 0, n);
			break;
		}
		*t++ = c;
		f++;
		n--;
	}
	return n;
}

Project: linux
File: namespace.c

int finish_automount(struct vfsmount *m, struct path *path)
{
	struct mount *mnt = real_mount(m);
	int err;
	/* The new mount record should have at least 2 refs to prevent it being
	 * expired before we get a chance to add it
	 */
	BUG_ON(mnt_get_count(mnt) < 2);

	if (m->mnt_sb == path->mnt->mnt_sb &&
	    m->mnt_root == path->dentry) {
		err = -ELOOP;
		goto fail;
	}

	err = do_add_mount(mnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE);
	if (!err)
		return 0;
fail:
	/* remove m from any expiration list it may be on */
	if (!list_empty(&mnt->mnt_expire)) {
		down_write(&namespace_sem);
		br_write_lock(&vfsmount_lock);
		list_del_init(&mnt->mnt_expire);
		br_write_unlock(&vfsmount_lock);
		up_write(&namespace_sem);
	}
	mntput(m);
	mntput(m);
	return err;
}

Project: linux
File: namespace.c

static int flags_to_propagation_type(int flags)
{
	int type = flags & ~(MS_REC | MS_SILENT);

	/* Fail if any non-propagation flags are set */
	if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
		return 0;
	/* Only one propagation flag should be set */
	if (!is_power_of_2(type))
		return 0;
	return type;
}

Project: linux
File: namespace.c

static void free_mnt_ns(struct mnt_namespace *ns)
{
	proc_free_inum(ns->proc_inum);
	put_user_ns(ns->user_ns);
	kfree(ns);
}

Project: linux
File: namespace.c

static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
{
	int err;
	const char *subtype = strchr(fstype, '.');
	if (subtype) {
		subtype++;
		err = -EINVAL;
		if (!subtype[0])
			goto err;
	} else
		subtype = "";

	mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
	err = -ENOMEM;
	if (!mnt->mnt_sb->s_subtype)
		goto err;
	return mnt;

 err:
	mntput(mnt);
	return ERR_PTR(err);
}

Project: linux
File: namespace.c

int generic_show_options(struct seq_file *m, struct dentry *root)
{
	const char *options;

	rcu_read_lock();
	options = rcu_dereference(root->d_sb->s_options);

	if (options != NULL && options[0]) {
		seq_putc(m, ',');
		mangle(m, options);
	}
	rcu_read_unlock();

	return 0;
}

Project: linux
File: namespace.c

static int graft_tree(struct mount *mnt, struct path *path)
{
	if (mnt->mnt.mnt_sb->s_flags & MS_NOUSER)
		return -EINVAL;

	if (S_ISDIR(path->dentry->d_inode->i_mode) !=
	      S_ISDIR(mnt->mnt.mnt_root->d_inode->i_mode))
		return -ENOTDIR;

	if (d_unlinked(path->dentry))
		return -ENOENT;

	return attach_recursive_mnt(mnt, path, NULL);
}

Project: linux
File: namespace.c

static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry)
{
	unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES);
	tmp += ((unsigned long)dentry / L1_CACHE_BYTES);
	tmp = tmp + (tmp >> HASH_SHIFT);
	return tmp & (HASH_SIZE - 1);
}

Project: linux
File: namespace.c

static void __init init_mount_tree(void)
{
	struct vfsmount *mnt;
	struct mnt_namespace *ns;
	struct path root;
	struct file_system_type *type;

	type = get_fs_type("rootfs");
	if (!type)
		panic("Can't find rootfs type");
	mnt = vfs_kern_mount(type, 0, "rootfs", NULL);
	put_filesystem(type);
	if (IS_ERR(mnt))
		panic("Can't create rootfs");

	ns = create_mnt_ns(mnt);
	if (IS_ERR(ns))
		panic("Can't allocate initial namespace");

	init_task.nsproxy->mnt_ns = ns;
	get_mnt_ns(ns);

	root.mnt = mnt;
	root.dentry = mnt->mnt_root;

	set_fs_pwd(current->fs, &root);
	set_fs_root(current->fs, &root);
}

Project: linux
File: namespace.c

static int invent_group_ids(struct mount *mnt, bool recurse)
{
	struct mount *p;

	for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) {
		if (!p->mnt_group_id && !IS_MNT_SHARED(p)) {
			int err = mnt_alloc_group_id(p);
			if (err) {
				cleanup_group_ids(mnt, p);
				return err;
			}
		}
	}

	return 0;
}

Project: linux
File: namespace.c

bool is_path_reachable(struct mount *mnt, struct dentry *dentry,
			 const struct path *root)
{
	while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) {
		dentry = mnt->mnt_mountpoint;
		mnt = mnt->mnt_parent;
	}
	return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry);
}

Project: linux
File: namespace.c

struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
{
	struct vfsmount *mnt;
	mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, data);
	if (!IS_ERR(mnt)) {
		/*
		 * it is a longterm mount, don't release mnt until
		 * we unmount before file sys is unregistered
		*/
		real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL;
	}
	return mnt;
}

Project: linux
File: namespace.c

void kern_unmount(struct vfsmount *mnt)
{
	/* release long term mount so mount point can be released */
	if (!IS_ERR_OR_NULL(mnt)) {
		br_write_lock(&vfsmount_lock);
		real_mount(mnt)->mnt_ns = NULL;
		br_write_unlock(&vfsmount_lock);
		mntput(mnt);
	}
}

Project: linux
File: namespace.c

static int lock_mount(struct path *path)
{
	struct vfsmount *mnt;
retry:
	mutex_lock(&path->dentry->d_inode->i_mutex);
	if (unlikely(cant_mount(path->dentry))) {
		mutex_unlock(&path->dentry->d_inode->i_mutex);
		return -ENOENT;
	}
	down_write(&namespace_sem);
	mnt = lookup_mnt(path);
	if (likely(!mnt))
		return 0;
	up_write(&namespace_sem);
	mutex_unlock(&path->dentry->d_inode->i_mutex);
	path_put(path);
	path->mnt = mnt;
	path->dentry = dget(mnt->mnt_root);
	goto retry;
}

Project: linux
File: namespace.c

struct vfsmount *lookup_mnt(struct path *path)
{
	struct mount *child_mnt;

	br_read_lock(&vfsmount_lock);
	child_mnt = __lookup_mnt(path->mnt, path->dentry, 1);
	if (child_mnt) {
		mnt_add_count(child_mnt, 1);
		br_read_unlock(&vfsmount_lock);
		return &child_mnt->mnt;
	} else {
		br_read_unlock(&vfsmount_lock);
		return NULL;
	}
}

Project: linux
File: namespace.c

static void *m_next(struct seq_file *m, void *v, loff_t *pos)
{
	struct proc_mounts *p = proc_mounts(m);

	return seq_list_next(v, &p->ns->list, pos);
}

Project: linux
File: namespace.c

static int m_show(struct seq_file *m, void *v)
{
	struct proc_mounts *p = proc_mounts(m);
	struct mount *r = list_entry(v, struct mount, mnt_list);
	return p->show(m, &r->mnt);
}

Project: linux
File: namespace.c

static void *m_start(struct seq_file *m, loff_t *pos)
{
	struct proc_mounts *p = proc_mounts(m);

	down_read(&namespace_sem);
	return seq_list_start(&p->ns->list, *pos);
}

Project: linux
File: namespace.c

static void m_stop(struct seq_file *m, void *v)
{
	up_read(&namespace_sem);
}

Project: linux
File: namespace.c

static inline void mangle(struct seq_file *m, const char *s)
{
	seq_escape(m, s, " \t\n\\");
}

Project: linux
File: namespace.c

void mark_mounts_for_expiry(struct list_head *mounts)
{
	struct mount *mnt, *next;
	LIST_HEAD(graveyard);
	LIST_HEAD(umounts);

	if (list_empty(mounts))
		return;

	down_write(&namespace_sem);
	br_write_lock(&vfsmount_lock);

	/* extract from the expiration list every vfsmount that matches the
	 * following criteria:
	 * - only referenced by its parent vfsmount
	 * - still marked for expiry (marked on the last call here; marks are
	 *   cleared by mntput())
	 */
	list_for_each_entry_safe(mnt, next, mounts, mnt_expire) {
		if (!xchg(&mnt->mnt_expiry_mark, 1) ||
			propagate_mount_busy(mnt, 1))
			continue;
		list_move(&mnt->mnt_expire, &graveyard);
	}
	while (!list_empty(&graveyard)) {
		mnt = list_first_entry(&graveyard, struct mount, mnt_expire);
		touch_mnt_namespace(mnt->mnt_ns);
		umount_tree(mnt, 1, &umounts);
	}
	br_write_unlock(&vfsmount_lock);
	up_write(&namespace_sem);

	release_mounts(&umounts);
}

Project: linux
File: namespace.c

static inline bool may_mount(void)
{
	return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN);
}

Project: linux
File: namespace.c

int may_umount(struct vfsmount *mnt)
{
	int ret = 1;
	down_read(&namespace_sem);
	br_write_lock(&vfsmount_lock);
	if (propagate_mount_busy(real_mount(mnt), 2))
		ret = 0;
	br_write_unlock(&vfsmount_lock);
	up_read(&namespace_sem);
	return ret;
}

Project: linux
File: namespace.c

static inline void mnt_add_count(struct mount *mnt, int n)
{
#ifdef CONFIG_SMP
	this_cpu_add(mnt->mnt_pcp->mnt_count, n);
#else
	preempt_disable();
	mnt->mnt_count += n;
	preempt_enable();
#endif
}

Project: linux
File: namespace.c

static int mnt_alloc_group_id(struct mount *mnt)
{
	int res;

	if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL))
		return -ENOMEM;

	res = ida_get_new_above(&mnt_group_ida,
				mnt_group_start,
				&mnt->mnt_group_id);
	if (!res)
		mnt_group_start = mnt->mnt_group_id + 1;

	return res;
}

Project: linux
File: namespace.c

static int mnt_alloc_id(struct mount *mnt)
{
	int res;

retry:
	ida_pre_get(&mnt_id_ida, GFP_KERNEL);
	spin_lock(&mnt_id_lock);
	res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id);
	if (!res)
		mnt_id_start = mnt->mnt_id + 1;
	spin_unlock(&mnt_id_lock);
	if (res == -EAGAIN)
		goto retry;

	return res;
}

Project: linux
File: namespace.c

int mnt_clone_write(struct vfsmount *mnt)
{
	/* superblock may be r/o */
	if (__mnt_is_readonly(mnt))
		return -EROFS;
	preempt_disable();
	mnt_inc_writers(real_mount(mnt));
	preempt_enable();
	return 0;
}

Project: linux
File: namespace.c

static inline void mnt_dec_writers(struct mount *mnt)
{
#ifdef CONFIG_SMP
	this_cpu_dec(mnt->mnt_pcp->mnt_writers);
#else
	mnt->mnt_writers--;
#endif
}

Project: linux
File: namespace.c

void mnt_drop_write(struct vfsmount *mnt)
{
	__mnt_drop_write(mnt);
	sb_end_write(mnt->mnt_sb);
}

Project: linux
File: namespace.c

void mnt_drop_write_file(struct file *file)
{
	mnt_drop_write(file->f_path.mnt);
}

Project: linux
File: namespace.c

static void mnt_free_id(struct mount *mnt)
{
	int id = mnt->mnt_id;
	spin_lock(&mnt_id_lock);
	ida_remove(&mnt_id_ida, id);
	if (mnt_id_start > id)
		mnt_id_start = id;
	spin_unlock(&mnt_id_lock);
}

Project: linux
File: namespace.c

static unsigned int mnt_get_writers(struct mount *mnt)
{
#ifdef CONFIG_SMP
	unsigned int count = 0;
	int cpu;

	for_each_possible_cpu(cpu) {
		count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers;
	}

	return count;
#else
	return mnt->mnt_writers;
#endif
}

Project: linux
File: namespace.c

static inline void mnt_inc_writers(struct mount *mnt)
{
#ifdef CONFIG_SMP
	this_cpu_inc(mnt->mnt_pcp->mnt_writers);
#else
	mnt->mnt_writers++;
#endif
}

Project: linux
File: namespace.c

void __init mnt_init(void)
{
	unsigned u;
	int err;

	init_rwsem(&namespace_sem);

	mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount),
			0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);

	mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC);

	if (!mount_hashtable)
		panic("Failed to allocate mount hash table\n");

	printk(KERN_INFO "Mount-cache hash table entries: %lu\n", HASH_SIZE);

	for (u = 0; u < HASH_SIZE; u++)
		INIT_LIST_HEAD(&mount_hashtable[u]);

	br_lock_init(&vfsmount_lock);

	err = sysfs_init();
	if (err)
		printk(KERN_WARNING "%s: sysfs_init error: %d\n",
			__func__, err);
	fs_kobj = kobject_create_and_add("fs", NULL);
	if (!fs_kobj)
		printk(KERN_WARNING "%s: kobj create error\n", __func__);
	init_rootfs();
	init_mount_tree();
}

Project: linux
File: namespace.c

static int mnt_is_readonly(struct vfsmount *mnt)
{
	if (mnt->mnt_sb->s_readonly_remount)
		return 1;
	/* Order wrt setting s_flags/s_readonly_remount in do_remount() */
	smp_rmb();
	return __mnt_is_readonly(mnt);
}

Project: linux
File: namespace.c

static int mnt_make_readonly(struct mount *mnt)
{
	int ret = 0;

	br_write_lock(&vfsmount_lock);
	mnt->mnt.mnt_flags |= MNT_WRITE_HOLD;
	/*
	 * After storing MNT_WRITE_HOLD, we'll read the counters. This store
	 * should be visible before we do.
	 */
	smp_mb();

	/*
	 * With writers on hold, if this value is zero, then there are
	 * definitely no active writers (although held writers may subsequently
	 * increment the count, they'll have to wait, and decrement it after
	 * seeing MNT_READONLY).
	 *
	 * It is OK to have counter incremented on one CPU and decremented on
	 * another: the sum will add up correctly. The danger would be when we
	 * sum up each counter, if we read a counter before it is incremented,
	 * but then read another CPU's count which it has been subsequently
	 * decremented from -- we would see more decrements than we should.
	 * MNT_WRITE_HOLD protects against this scenario, because
	 * mnt_want_write first increments count, then smp_mb, then spins on
	 * MNT_WRITE_HOLD, so it can't be decremented by another CPU while
	 * we're counting up here.
	 */
	if (mnt_get_writers(mnt) > 0)
		ret = -EBUSY;
	else
		mnt->mnt.mnt_flags |= MNT_READONLY;
	/*
	 * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers
	 * that become unheld will see MNT_READONLY.
	 */
	smp_wmb();
	mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD;
	br_write_unlock(&vfsmount_lock);
	return ret;
}

Project: linux
File: namespace.c

static bool mnt_ns_loop(struct path *path)
{
	/* Could bind mounting the mount namespace inode cause a
	 * mount namespace loop?
	 */
	struct inode *inode = path->dentry->d_inode;
	struct proc_inode *ei;
	struct mnt_namespace *mnt_ns;

	if (!proc_ns_inode(inode))
		return false;

	ei = PROC_I(inode);
	if (ei->ns_ops != &mntns_operations)
		return false;

	mnt_ns = ei->ns;
	return current->nsproxy->mnt_ns->seq >= mnt_ns->seq;
}

Project: linux
File: namespace.c

void mnt_pin(struct vfsmount *mnt)
{
	br_write_lock(&vfsmount_lock);
	real_mount(mnt)->mnt_pinned++;
	br_write_unlock(&vfsmount_lock);
}

Project: linux
File: namespace.c

void mnt_release_group_id(struct mount *mnt)
{
	int id = mnt->mnt_group_id;
	ida_remove(&mnt_group_ida, id);
	if (mnt_group_start > id)
		mnt_group_start = id;
	mnt->mnt_group_id = 0;
}

Project: linux
File: namespace.c

void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list)
{
	down_write(&namespace_sem);
	br_write_lock(&vfsmount_lock);

	list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list);

	br_write_unlock(&vfsmount_lock);
	up_write(&namespace_sem);
}

Project: linux
File: namespace.c

void mnt_unpin(struct vfsmount *m)
{
	struct mount *mnt = real_mount(m);
	br_write_lock(&vfsmount_lock);
	if (mnt->mnt_pinned) {
		mnt_add_count(mnt, 1);
		mnt->mnt_pinned--;
	}
	br_write_unlock(&vfsmount_lock);
}

Project: linux
File: namespace.c

int mnt_want_write(struct vfsmount *m)
{
	int ret;

	sb_start_write(m->mnt_sb);
	ret = __mnt_want_write(m);
	if (ret)
		sb_end_write(m->mnt_sb);
	return ret;
}

Project: linux
File: namespace.c

int mnt_want_write_file(struct file *file)
{
	int ret;

	sb_start_write(file->f_path.mnt->mnt_sb);
	ret = __mnt_want_write_file(file);
	if (ret)
		sb_end_write(file->f_path.mnt->mnt_sb);
	return ret;
}

Project: linux
File: namespace.c

struct vfsmount *mntget(struct vfsmount *mnt)
{
	if (mnt)
		mnt_add_count(real_mount(mnt), 1);
	return mnt;
}

Project: linux
File: namespace.c

static void *mntns_get(struct task_struct *task)
{
	struct mnt_namespace *ns = NULL;
	struct nsproxy *nsproxy;

	rcu_read_lock();
	nsproxy = task_nsproxy(task);
	if (nsproxy) {
		ns = nsproxy->mnt_ns;
		get_mnt_ns(ns);
	}
	rcu_read_unlock();

	return ns;
}

Project: linux
File: namespace.c

static int mntns_install(struct nsproxy *nsproxy, void *ns)
{
	struct fs_struct *fs = current->fs;
	struct mnt_namespace *mnt_ns = ns;
	struct path root;

	if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) ||
	    !nsown_capable(CAP_SYS_CHROOT) ||
	    !nsown_capable(CAP_SYS_ADMIN))
		return -EPERM;

	if (fs->users != 1)
		return -EINVAL;

	get_mnt_ns(mnt_ns);
	put_mnt_ns(nsproxy->mnt_ns);
	nsproxy->mnt_ns = mnt_ns;

	/* Find the root */
	root.mnt    = &mnt_ns->root->mnt;
	root.dentry = mnt_ns->root->mnt.mnt_root;
	path_get(&root);
	while(d_mountpoint(root.dentry) && follow_down_one(&root))
		;

	/* Update the pwd and root */
	set_fs_pwd(fs, &root);
	set_fs_root(fs, &root);

	path_put(&root);
	return 0;
}

Project: linux
File: namespace.c

static unsigned int mntns_inum(void *ns)
{
	struct mnt_namespace *mnt_ns = ns;
	return mnt_ns->proc_inum;
}

Project: linux
File: namespace.c

static void mntns_put(void *ns)
{
	put_mnt_ns(ns);
}

Project: linux
File: namespace.c

void mntput(struct vfsmount *mnt)
{
	if (mnt) {
		struct mount *m = real_mount(mnt);
		/* avoid cacheline pingpong, hope gcc doesn't get "smart" */
		if (unlikely(m->mnt_expiry_mark))
			m->mnt_expiry_mark = 0;
		mntput_no_expire(m);
	}
}

Project: linux
File: namespace.c

static void mntput_no_expire(struct mount *mnt)
{
put_again:
#ifdef CONFIG_SMP
	br_read_lock(&vfsmount_lock);
	if (likely(mnt->mnt_ns)) {
		/* shouldn't be the last one */
		mnt_add_count(mnt, -1);
		br_read_unlock(&vfsmount_lock);
		return;
	}
	br_read_unlock(&vfsmount_lock);

	br_write_lock(&vfsmount_lock);
	mnt_add_count(mnt, -1);
	if (mnt_get_count(mnt)) {
		br_write_unlock(&vfsmount_lock);
		return;
	}
#else
	mnt_add_count(mnt, -1);
	if (likely(mnt_get_count(mnt)))
		return;
	br_write_lock(&vfsmount_lock);
#endif
	if (unlikely(mnt->mnt_pinned)) {
		mnt_add_count(mnt, mnt->mnt_pinned + 1);
		mnt->mnt_pinned = 0;
		br_write_unlock(&vfsmount_lock);
		acct_auto_close_mnt(&mnt->mnt);
		goto put_again;
	}

	list_del(&mnt->mnt_instance);
	br_write_unlock(&vfsmount_lock);
	mntfree(mnt);
}

Project: linux
File: namespace.c

struct dentry *mount_subtree(struct vfsmount *mnt, const char *name)
{
	struct mnt_namespace *ns;
	struct super_block *s;
	struct path path;
	int err;

	ns = create_mnt_ns(mnt);
	if (IS_ERR(ns))
		return ERR_CAST(ns);

	err = vfs_path_lookup(mnt->mnt_root, mnt,
			name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);

	put_mnt_ns(ns);

	if (err)
		return ERR_PTR(err);

	/* trade a vfsmount reference for active sb one */
	s = path.mnt->mnt_sb;
	atomic_inc(&s->s_active);
	mntput(path.mnt);
	/* lock the sucker */
	down_write(&s->s_umount);
	/* ... and return the root of (sub)tree on it */
	return path.dentry;
}

Project: linux
File: namespace.c

static struct mount *next_mnt(struct mount *p, struct mount *root)
{
	struct list_head *next = p->mnt_mounts.next;
	if (next == &p->mnt_mounts) {
		while (1) {
			if (p == root)
				return NULL;
			next = p->mnt_child.next;
			if (next != &p->mnt_parent->mnt_mounts)
				break;
			p = p->mnt_parent;
		}
	}
	return list_entry(next, struct mount, mnt_child);
}

Project: linux
File: namespace.c

bool our_mnt(struct vfsmount *mnt)
{
	return check_mnt(real_mount(mnt));
}

Project: linux
File: namespace.c

int path_is_under(struct path *path1, struct path *path2)
{
	int res;
	br_read_lock(&vfsmount_lock);
	res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2);
	br_read_unlock(&vfsmount_lock);
	return res;
}

Project: linux
File: namespace.c

void put_mnt_ns(struct mnt_namespace *ns)
{
	LIST_HEAD(umount_list);

	if (!atomic_dec_and_test(&ns->count))
		return;
	down_write(&namespace_sem);
	br_write_lock(&vfsmount_lock);
	umount_tree(ns->root, 0, &umount_list);
	br_write_unlock(&vfsmount_lock);
	up_write(&namespace_sem);
	release_mounts(&umount_list);
	free_mnt_ns(ns);
}

Project: linux
File: namespace.c

void release_mounts(struct list_head *head)
{
	struct mount *mnt;
	while (!list_empty(head)) {
		mnt = list_first_entry(head, struct mount, mnt_hash);
		list_del_init(&mnt->mnt_hash);
		if (mnt_has_parent(mnt)) {
			struct dentry *dentry;
			struct mount *m;

			br_write_lock(&vfsmount_lock);
			dentry = mnt->mnt_mountpoint;
			m = mnt->mnt_parent;
			mnt->mnt_mountpoint = mnt->mnt.mnt_root;
			mnt->mnt_parent = mnt;
			m->mnt_ghosts--;
			br_write_unlock(&vfsmount_lock);
			dput(dentry);
			mntput(&m->mnt);
		}
		mntput(&mnt->mnt);
	}
}

Project: linux
File: namespace.c

void replace_mount_options(struct super_block *sb, char *options)
{
	char *old = sb->s_options;
	rcu_assign_pointer(sb->s_options, options);
	if (old) {
		synchronize_rcu();
		kfree(old);
	}
}

Project: linux
File: namespace.c

void save_mount_options(struct super_block *sb, char *options)
{
	BUG_ON(sb->s_options);
	rcu_assign_pointer(sb->s_options, kstrdup(options, GFP_KERNEL));
}

Project: linux
File: namespace.c

int sb_prepare_remount_readonly(struct super_block *sb)
{
	struct mount *mnt;
	int err = 0;

	/* Racy optimization.  Recheck the counter under MNT_WRITE_HOLD */
	if (atomic_long_read(&sb->s_remove_count))
		return -EBUSY;

	br_write_lock(&vfsmount_lock);
	list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) {
		if (!(mnt->mnt.mnt_flags & MNT_READONLY)) {
			mnt->mnt.mnt_flags |= MNT_WRITE_HOLD;
			smp_mb();
			if (mnt_get_writers(mnt) > 0) {
				err = -EBUSY;
				break;
			}
		}
	}
	if (!err && atomic_long_read(&sb->s_remove_count))
		err = -EBUSY;

	if (!err) {
		sb->s_readonly_remount = 1;
		smp_wmb();
	}
	list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) {
		if (mnt->mnt.mnt_flags & MNT_WRITE_HOLD)
			mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD;
	}
	br_write_unlock(&vfsmount_lock);

	return err;
}

Project: linux
File: namespace.c

static int select_submounts(struct mount *parent, struct list_head *graveyard)
{
	struct mount *this_parent = parent;
	struct list_head *next;
	int found = 0;

repeat:
	next = this_parent->mnt_mounts.next;
resume:
	while (next != &this_parent->mnt_mounts) {
		struct list_head *tmp = next;
		struct mount *mnt = list_entry(tmp, struct mount, mnt_child);

		next = tmp->next;
		if (!(mnt->mnt.mnt_flags & MNT_SHRINKABLE))
			continue;
		/*
		 * Descend a level if the d_mounts list is non-empty.
		 */
		if (!list_empty(&mnt->mnt_mounts)) {
			this_parent = mnt;
			goto repeat;
		}

		if (!propagate_mount_busy(mnt, 1)) {
			list_move_tail(&mnt->mnt_expire, graveyard);
			found++;
		}
	}
	/*
	 * All done at this level ... ascend and resume the search
	 */
	if (this_parent != parent) {
		next = this_parent->mnt_child.next;
		this_parent = this_parent->mnt_parent;
		goto resume;
	}
	return found;
}

Project: linux
File: namespace.c

static void shrink_submounts(struct mount *mnt, struct list_head *umounts)
{
	LIST_HEAD(graveyard);
	struct mount *m;

	/* extract submounts of 'mountpoint' from the expiration list */
	while (select_submounts(mnt, &graveyard)) {
		while (!list_empty(&graveyard)) {
			m = list_first_entry(&graveyard, struct mount,
						mnt_expire);
			touch_mnt_namespace(m->mnt_ns);
			umount_tree(m, 1, umounts);
		}
	}
}

Project: linux
File: namespace.c

static struct mount *skip_mnt_tree(struct mount *p)
{
	struct list_head *prev = p->mnt_mounts.prev;
	while (prev != &p->mnt_mounts) {
		p = list_entry(prev, struct mount, mnt_child);
		prev = p->mnt_mounts.prev;
	}
	return p;
}

Project: linux
File: namespace.c

static void touch_mnt_namespace(struct mnt_namespace *ns)
{
	if (ns) {
		ns->event = ++event;
		wake_up_interruptible(&ns->poll);
	}
}

Project: linux
File: namespace.c

static inline int tree_contains_unbindable(struct mount *mnt)
{
	struct mount *p;
	for (p = mnt; p; p = next_mnt(p, mnt)) {
		if (IS_MNT_UNBINDABLE(p))
			return 1;
	}
	return 0;
}

Project: linux
File: namespace.c

void umount_tree(struct mount *mnt, int propagate, struct list_head *kill)
{
	LIST_HEAD(tmp_list);
	struct mount *p;

	for (p = mnt; p; p = next_mnt(p, mnt))
		list_move(&p->mnt_hash, &tmp_list);

	if (propagate)
		propagate_umount(&tmp_list);

	list_for_each_entry(p, &tmp_list, mnt_hash) {
		list_del_init(&p->mnt_expire);
		list_del_init(&p->mnt_list);
		__touch_mnt_namespace(p->mnt_ns);
		p->mnt_ns = NULL;
		list_del_init(&p->mnt_child);
		if (mnt_has_parent(p)) {
			p->mnt_parent->mnt_ghosts++;
			dentry_reset_mounted(p->mnt_mountpoint);
		}
		change_mnt_propagation(p, MS_PRIVATE);
	}
	list_splice(&tmp_list, kill);
}

Project: linux
File: namespace.c

static void unlock_mount(struct path *path)
{
	up_write(&namespace_sem);
	mutex_unlock(&path->dentry->d_inode->i_mutex);
}

Project: linux
File: namespace.c

vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
{
	struct mount *mnt;
	struct dentry *root;

	if (!type)
		return ERR_PTR(-ENODEV);

	mnt = alloc_vfsmnt(name);
	if (!mnt)
		return ERR_PTR(-ENOMEM);

	if (flags & MS_KERNMOUNT)
		mnt->mnt.mnt_flags = MNT_INTERNAL;

	root = mount_fs(type, flags, name, data);
	if (IS_ERR(root)) {
		free_vfsmnt(mnt);
		return ERR_CAST(root);
	}

	mnt->mnt.mnt_root = root;
	mnt->mnt.mnt_sb = root->d_sb;
	mnt->mnt_mountpoint = mnt->mnt.mnt_root;
	mnt->mnt_parent = mnt;
	br_write_lock(&vfsmount_lock);
	list_add_tail(&mnt->mnt_instance, &root->d_sb->s_mounts);
	br_write_unlock(&vfsmount_lock);
	return &mnt->mnt;
}

Project: linux
File: pnode.c

static void __propagate_umount(struct mount *mnt)
{
	struct mount *parent = mnt->mnt_parent;
	struct mount *m;

	BUG_ON(parent == mnt);

	for (m = propagation_next(parent, parent); m;
			m = propagation_next(m, parent)) {

		struct mount *child = __lookup_mnt(&m->mnt,
					mnt->mnt_mountpoint, 0);
		/*
		 * umount the child only if the child has no
		 * other children
		 */
		if (child && list_empty(&child->mnt_mounts))
			list_move_tail(&child->mnt_hash, &mnt->mnt_hash);
	}
}

Project: linux
File: pnode.c

void change_mnt_propagation(struct mount *mnt, int type)
{
	if (type == MS_SHARED) {
		set_mnt_shared(mnt);
		return;
	}
	do_make_slave(mnt);
	if (type != MS_SLAVE) {
		list_del_init(&mnt->mnt_slave);
		mnt->mnt_master = NULL;
		if (type == MS_UNBINDABLE)
			mnt->mnt.mnt_flags |= MNT_UNBINDABLE;
		else
			mnt->mnt.mnt_flags &= ~MNT_UNBINDABLE;
	}
}

Project: linux
File: pnode.c

static int do_make_slave(struct mount *mnt)
{
	struct mount *peer_mnt = mnt, *master = mnt->mnt_master;
	struct mount *slave_mnt;

	/*
	 * slave 'mnt' to a peer mount that has the
	 * same root dentry. If none is available then
	 * slave it to anything that is available.
	 */
	while ((peer_mnt = next_peer(peer_mnt)) != mnt &&
	       peer_mnt->mnt.mnt_root != mnt->mnt.mnt_root) ;

	if (peer_mnt == mnt) {
		peer_mnt = next_peer(mnt);
		if (peer_mnt == mnt)
			peer_mnt = NULL;
	}
	if (IS_MNT_SHARED(mnt) && list_empty(&mnt->mnt_share))
		mnt_release_group_id(mnt);

	list_del_init(&mnt->mnt_share);
	mnt->mnt_group_id = 0;

	if (peer_mnt)
		master = peer_mnt;

	if (master) {
		list_for_each_entry(slave_mnt, &mnt->mnt_slave_list, mnt_slave)
			slave_mnt->mnt_master = master;
		list_move(&mnt->mnt_slave, &master->mnt_slave_list);
		list_splice(&mnt->mnt_slave_list, master->mnt_slave_list.prev);
		INIT_LIST_HEAD(&mnt->mnt_slave_list);
	} else {
		struct list_head *p = &mnt->mnt_slave_list;
		while (!list_empty(p)) {
                        slave_mnt = list_first_entry(p,
					struct mount, mnt_slave);
			list_del_init(&slave_mnt->mnt_slave);
			slave_mnt->mnt_master = NULL;
		}
	}
	mnt->mnt_master = master;
	CLEAR_MNT_SHARED(mnt);
	return 0;
}

Project: linux
File: pnode.c

static inline struct mount *first_slave(struct mount *p)
{
	return list_entry(p->mnt_slave_list.next, struct mount, mnt_slave);
}

Project: linux
File: pnode.c

int get_dominating_id(struct mount *mnt, const struct path *root)
{
	struct mount *m;

	for (m = mnt->mnt_master; m != NULL; m = m->mnt_master) {
		struct mount *d = get_peer_under_root(m, mnt->mnt_ns, root);
		if (d)
			return d->mnt_group_id;
	}

	return 0;
}

Project: linux
File: pnode.c

static struct mount *get_peer_under_root(struct mount *mnt,
					 struct mnt_namespace *ns,
					 const struct path *root)
{
	struct mount *m = mnt;

	do {
		/* Check the namespace first for optimization */
		if (m->mnt_ns == ns && is_path_reachable(m, m->mnt.mnt_root, root))
			return m;

		m = next_peer(m);
	} while (m != mnt);

	return NULL;
}

Project: linux
File: pnode.c

static struct mount *get_source(struct mount *dest,
				struct mount *last_dest,
				struct mount *last_src,
				int *type)
{
	struct mount *p_last_src = NULL;
	struct mount *p_last_dest = NULL;

	while (last_dest != dest->mnt_master) {
		p_last_dest = last_dest;
		p_last_src = last_src;
		last_dest = last_dest->mnt_master;
		last_src = last_src->mnt_master;
	}

	if (p_last_dest) {
		do {
			p_last_dest = next_peer(p_last_dest);
		} while (IS_MNT_NEW(p_last_dest));
		/* is that a peer of the earlier? */
		if (dest == p_last_dest) {
			*type = CL_MAKE_SHARED;
			return p_last_src;
		}
	}
	/* slave of the earlier, then */
	*type = CL_SLAVE;
	/* beginning of peer group among the slaves? */
	if (IS_MNT_SHARED(dest))
		*type |= CL_MAKE_SHARED;
	return last_src;
}

Project: linux
File: pnode.c

static inline struct mount *next_peer(struct mount *p)
{
	return list_entry(p->mnt_share.next, struct mount, mnt_share);
}

Project: linux
File: pnode.c

static inline struct mount *next_slave(struct mount *p)
{
	return list_entry(p->mnt_slave.next, struct mount, mnt_slave);
}

Project: linux
File: pnode.c

int propagate_mount_busy(struct mount *mnt, int refcnt)
{
	struct mount *m, *child;
	struct mount *parent = mnt->mnt_parent;
	int ret = 0;

	if (mnt == parent)
		return do_refcount_check(mnt, refcnt);

	/*
	 * quickly check if the current mount can be unmounted.
	 * If not, we don't have to go checking for all other
	 * mounts
	 */
	if (!list_empty(&mnt->mnt_mounts) || do_refcount_check(mnt, refcnt))
		return 1;

	for (m = propagation_next(parent, parent); m;
	     		m = propagation_next(m, parent)) {
		child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint, 0);
		if (child && list_empty(&child->mnt_mounts) &&
		    (ret = do_refcount_check(child, 1)))
			break;
	}
	return ret;
}

Project: linux
File: pnode.c

int propagate_umount(struct list_head *list)
{
	struct mount *mnt;

	list_for_each_entry(mnt, list, mnt_hash)
		__propagate_umount(mnt);
	return 0;
}

Project: linux
File: pnode.c

static struct mount *propagation_next(struct mount *m,
					 struct mount *origin)
{
	/* are there any slaves of this mount? */
	if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list))
		return first_slave(m);

	while (1) {
		struct mount *master = m->mnt_master;

		if (master == origin->mnt_master) {
			struct mount *next = next_peer(m);
			return (next == origin) ? NULL : next;
		} else if (m->mnt_slave.next != &master->mnt_slave_list)
			return next_slave(m);

		/* back at master */
		m = master;
	}
}