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Commit 99421c1c 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:
 "This tree contains 4 fixes.

  The first is a fix for a race that can causes oopses under the right
  circumstances, and that someone just recently encountered.

  Past that are several small trivial correct fixes. A real issue that
  was blocking development of an out of tree driver, but does not appear
  to have caused any actual problems for in-tree code. A potential
  deadlock that was reported by lockdep. And a deadlock people have
  experienced and took the time to track down caused by a cleanup that
  removed the code to drop a reference count"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  sysctl: Drop reference added by grab_header in proc_sys_readdir
  pid: fix lockdep deadlock warning due to ucount_lock
  libfs: Modify mount_pseudo_xattr to be clear it is not a userspace mount
  mnt: Protect the mountpoint hashtable with mount_lock
parents c9281627 93362fa4

fs/dcache.c

+5 −2
Original line number Diff line number Diff line
@@ -1336,9 +1336,12 @@ int d_set_mounted(struct dentry *dentry) 
	}

	spin_lock(&dentry->d_lock);

	if (!d_unlinked(dentry)) {

		ret = -EBUSY;

		if (!d_mountpoint(dentry)) {

			dentry->d_flags |= DCACHE_MOUNTED;

			ret = 0;

		}

	}

 	spin_unlock(&dentry->d_lock);

out:

	write_sequnlock(&rename_lock);

fs/libfs.c

+2 −1
Original line number Diff line number Diff line
@@ -245,7 +245,8 @@ struct dentry *mount_pseudo_xattr(struct file_system_type *fs_type, char *name, 
	struct inode *root;

	struct qstr d_name = QSTR_INIT(name, strlen(name));



	s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL);

	s = sget_userns(fs_type, NULL, set_anon_super, MS_KERNMOUNT|MS_NOUSER,

			&init_user_ns, NULL);

	if (IS_ERR(s))

		return ERR_CAST(s);

fs/namespace.c

+45 −19
Original line number Diff line number Diff line
@@ -742,26 +742,50 @@ static struct mountpoint *lookup_mountpoint(struct dentry *dentry) 
	return NULL;

}



static struct mountpoint *new_mountpoint(struct dentry *dentry)

static struct mountpoint *get_mountpoint(struct dentry *dentry)

{

	struct hlist_head *chain = mp_hash(dentry);

	struct mountpoint *mp;

	struct mountpoint *mp, *new = NULL;

	int ret;



	mp = kmalloc(sizeof(struct mountpoint), GFP_KERNEL);

	if (!mp)

	if (d_mountpoint(dentry)) {

mountpoint:

		read_seqlock_excl(&mount_lock);

		mp = lookup_mountpoint(dentry);

		read_sequnlock_excl(&mount_lock);

		if (mp)

			goto done;

	}



	if (!new)

		new = kmalloc(sizeof(struct mountpoint), GFP_KERNEL);

	if (!new)

		return ERR_PTR(-ENOMEM);





	/* Exactly one processes may set d_mounted */

	ret = d_set_mounted(dentry);

	if (ret) {

		kfree(mp);

		return ERR_PTR(ret);

	}



	mp->m_dentry = dentry;

	mp->m_count = 1;

	hlist_add_head(&mp->m_hash, chain);

	INIT_HLIST_HEAD(&mp->m_list);

	/* Someone else set d_mounted? */

	if (ret == -EBUSY)

		goto mountpoint;



	/* The dentry is not available as a mountpoint? */

	mp = ERR_PTR(ret);

	if (ret)

		goto done;



	/* Add the new mountpoint to the hash table */

	read_seqlock_excl(&mount_lock);

	new->m_dentry = dentry;

	new->m_count = 1;

	hlist_add_head(&new->m_hash, mp_hash(dentry));

	INIT_HLIST_HEAD(&new->m_list);

	read_sequnlock_excl(&mount_lock);



	mp = new;

	new = NULL;

done:

	kfree(new);

	return mp;

}
@@ -1595,11 +1619,11 @@ void __detach_mounts(struct dentry *dentry) 
	struct mount *mnt;



	namespace_lock();

	lock_mount_hash();

	mp = lookup_mountpoint(dentry);

	if (IS_ERR_OR_NULL(mp))

		goto out_unlock;



	lock_mount_hash();

	event++;

	while (!hlist_empty(&mp->m_list)) {

		mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list);
@@ -1609,9 +1633,9 @@ void __detach_mounts(struct dentry *dentry) 
		}

		else umount_tree(mnt, UMOUNT_CONNECTED);

	}

	unlock_mount_hash();

	put_mountpoint(mp);

out_unlock:

	unlock_mount_hash();

	namespace_unlock();

}
@@ -2038,9 +2062,7 @@ static struct mountpoint *lock_mount(struct path *path) 
	namespace_lock();

	mnt = lookup_mnt(path);

	if (likely(!mnt)) {

		struct mountpoint *mp = lookup_mountpoint(dentry);

		if (!mp)

			mp = new_mountpoint(dentry);

		struct mountpoint *mp = get_mountpoint(dentry);

		if (IS_ERR(mp)) {

			namespace_unlock();

			inode_unlock(dentry->d_inode);
@@ -2059,7 +2081,11 @@ static struct mountpoint *lock_mount(struct path *path) 
static void unlock_mount(struct mountpoint *where)

{

	struct dentry *dentry = where->m_dentry;



	read_seqlock_excl(&mount_lock);

	put_mountpoint(where);

	read_sequnlock_excl(&mount_lock);



	namespace_unlock();

	inode_unlock(dentry->d_inode);

}
@@ -3135,9 +3161,9 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, 
	touch_mnt_namespace(current->nsproxy->mnt_ns);

	/* A moved mount should not expire automatically */

	list_del_init(&new_mnt->mnt_expire);

	put_mountpoint(root_mp);

	unlock_mount_hash();

	chroot_fs_refs(&root, &new);

	put_mountpoint(root_mp);

	error = 0;

out4:

	unlock_mount(old_mp);

fs/proc/proc_sysctl.c

+2 −1
Original line number Diff line number Diff line
@@ -709,7 +709,7 @@ static int proc_sys_readdir(struct file *file, struct dir_context *ctx) 
	ctl_dir = container_of(head, struct ctl_dir, header);



	if (!dir_emit_dots(file, ctx))

		return 0;

		goto out;



	pos = 2;
@@ -719,6 +719,7 @@ static int proc_sys_readdir(struct file *file, struct dir_context *ctx) 
			break;

		}

	}

out:

	sysctl_head_finish(head);

	return 0;

}

kernel/pid_namespace.c

+6 −4
Original line number Diff line number Diff line
@@ -151,8 +151,12 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns 


static void delayed_free_pidns(struct rcu_head *p)

{

	kmem_cache_free(pid_ns_cachep,

			container_of(p, struct pid_namespace, rcu));

	struct pid_namespace *ns = container_of(p, struct pid_namespace, rcu);



	dec_pid_namespaces(ns->ucounts);

	put_user_ns(ns->user_ns);



	kmem_cache_free(pid_ns_cachep, ns);

}



static void destroy_pid_namespace(struct pid_namespace *ns)
@@ -162,8 +166,6 @@ static void destroy_pid_namespace(struct pid_namespace *ns) 
	ns_free_inum(&ns->ns);

	for (i = 0; i < PIDMAP_ENTRIES; i++)

		kfree(ns->pidmap[i].page);

	dec_pid_namespaces(ns->ucounts);

	put_user_ns(ns->user_ns);

	call_rcu(&ns->rcu, delayed_free_pidns);

}