Commit 56c1731b authored by Al Viro's avatar Al Viro Committed by David S. Miller
Browse files

unix_bind_bsd(): move done_path_create() call after dealing with ->bindlock 



Final preparations for doing unlink on failure past the successful
mknod.  We can't hold ->bindlock over ->mknod() or ->unlink(), since
either might do sb_start_write() (e.g. on overlayfs).  However, we
can do it while holding filesystem and VFS locks - doing
	kern_path_create()
	vfs_mknod()
	grab ->bindlock
	if u->addr had been set
		drop ->bindlock
		done_path_create
		return -EINVAL
	else
		assign the address to socket
		drop ->bindlock
		done_path_create
		return 0
would be deadlock-free.  Here we massage unix_bind_bsd() to that
form.  We are still doing equivalent transformations.

Next commit will *not* be an equivalent transformation - it will
add a call of vfs_unlink() before done_path_create() in "alread bound"
case.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 71e6be6f

net/unix/af_unix.c

+11 −15
Original line number Diff line number Diff line
@@ -989,8 +989,8 @@ static int unix_bind_bsd(struct sock *sk, struct unix_address *addr) 
	struct unix_sock *u = unix_sk(sk);

	umode_t mode = S_IFSOCK |

	       (SOCK_INODE(sk->sk_socket)->i_mode & ~current_umask());

	struct path parent, path;

	struct user_namespace *ns; // barf...

	struct path parent;

	struct dentry *dentry;

	unsigned int hash;

	int err;
@@ -1008,36 +1008,32 @@ static int unix_bind_bsd(struct sock *sk, struct unix_address *addr) 
	 * All right, let's create it.

	 */

	err = security_path_mknod(&parent, dentry, mode, 0);

	if (!err) {

	if (!err)

		err = vfs_mknod(ns, d_inode(parent.dentry), dentry, mode, 0);

		if (!err) {

			path.mnt = mntget(parent.mnt);

			path.dentry = dget(dentry);

		}

	}

	if (err) {

		done_path_create(&parent, dentry);

	if (err)

		return err;



	}

	err = mutex_lock_interruptible(&u->bindlock);

	if (err) {

		path_put(&path);

		done_path_create(&parent, dentry);

		return err;

	}



	if (u->addr) {

		mutex_unlock(&u->bindlock);

		path_put(&path);

		done_path_create(&parent, dentry);

		return -EINVAL;

	}



	addr->hash = UNIX_HASH_SIZE;

	hash = d_backing_inode(path.dentry)->i_ino & (UNIX_HASH_SIZE - 1);

	hash = d_backing_inode(dentry)->i_ino & (UNIX_HASH_SIZE - 1);

	spin_lock(&unix_table_lock);

	u->path = path;

	u->path.mnt = mntget(parent.mnt);

	u->path.dentry = dget(dentry);

	__unix_set_addr(sk, addr, hash);

	spin_unlock(&unix_table_lock);

	mutex_unlock(&u->bindlock);

	done_path_create(&parent, dentry);

	return 0;

}