xfs: lift cursor copy in/out into xfs_ioc_attr_list

Lift the common code to copy the cursor from and to user space into
xfs_ioc_attr_list.  Note that this means we copy in twice now as
the cursor is in the middle of the conaining structure, but we never
touch the memory for the original copy.  Doing so keeps the cursor
handling isolated in the common helper.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Chandan Rajendra <chandanrlinux@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

1 files changed, 15 insertions, 21 deletions

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 34f59697f8dd..2a7d05992584 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -355,9 +355,10 @@ xfs_ioc_attr_list(
 	void __user			*ubuf,
 	int				bufsize,
 	int				flags,
-	struct attrlist_cursor_kern	*cursor)
+	struct xfs_attrlist_cursor __user *ucursor)
 {
 	struct xfs_attr_list_context	context;
+	struct attrlist_cursor_kern	cursor;
 	struct xfs_attrlist		*alist;
 	void				*buffer;
 	int				error;
@@ -377,10 +378,12 @@ xfs_ioc_attr_list(
 	/*
 	 * Validate the cursor.
 	 */
-	if (cursor->pad1 || cursor->pad2)
+	if (copy_from_user(&cursor, ucursor, sizeof(cursor)))
+		return -EFAULT;
+	if (cursor.pad1 || cursor.pad2)
 		return -EINVAL;
-	if ((cursor->initted == 0) &&
-	    (cursor->hashval || cursor->blkno || cursor->offset))
+	if ((cursor.initted == 0) &&
+	    (cursor.hashval || cursor.blkno || cursor.offset))
 		return -EINVAL;
 
 	buffer = kmem_zalloc_large(bufsize, 0);
@@ -392,7 +395,7 @@ xfs_ioc_attr_list(
 	 */
 	memset(&context, 0, sizeof(context));
 	context.dp = dp;
-	context.cursor = cursor;
+	context.cursor = &cursor;
 	context.resynch = 1;
 	context.flags = flags;
 	context.buffer = buffer;
@@ -409,7 +412,8 @@ xfs_ioc_attr_list(
 	if (error)
 		goto out_free;
 
-	if (copy_to_user(ubuf, buffer, bufsize))
+	if (copy_to_user(ubuf, buffer, bufsize) ||
+	    copy_to_user(ucursor, &cursor, sizeof(cursor)))
 		error = -EFAULT;
 out_free:
 	kmem_free(buffer);
@@ -419,33 +423,23 @@ out_free:
 STATIC int
 xfs_attrlist_by_handle(
 	struct file		*parfilp,
-	void			__user *arg)
+	struct xfs_fsop_attrlist_handlereq __user *p)
 {
-	int			error = -ENOMEM;
-	attrlist_cursor_kern_t	*cursor;
-	struct xfs_fsop_attrlist_handlereq __user	*p = arg;
-	xfs_fsop_attrlist_handlereq_t al_hreq;
+	struct xfs_fsop_attrlist_handlereq al_hreq;
 	struct dentry		*dentry;
+	int			error = -ENOMEM;
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
-	if (copy_from_user(&al_hreq, arg, sizeof(xfs_fsop_attrlist_handlereq_t)))
+	if (copy_from_user(&al_hreq, p, sizeof(al_hreq)))
 		return -EFAULT;
 
 	dentry = xfs_handlereq_to_dentry(parfilp, &al_hreq.hreq);
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
 
-	cursor = (attrlist_cursor_kern_t *)&al_hreq.pos;
 	error = xfs_ioc_attr_list(XFS_I(d_inode(dentry)), al_hreq.buffer,
-				  al_hreq.buflen, al_hreq.flags, cursor);
-	if (error)
-		goto out_dput;
-
-	if (copy_to_user(&p->pos, cursor, sizeof(attrlist_cursor_kern_t)))
-		error = -EFAULT;
-
-out_dput:
+				  al_hreq.buflen, al_hreq.flags, &p->pos);
 	dput(dentry);
 	return error;
 }