ima: fix fallback to use new_sync_read()

3.16 commit aad4f8bb42af06371aa0e85bf0cd9d52c0494985
'switch simple generic_file_aio_read() users to ->read_iter()'
replaced ->aio_read with ->read_iter in most of the file systems
and introduced new_sync_read() as a replacement for do_sync_read().

Most of file systems set '->read' and ima_kernel_read is not affected.
When ->read is not set, this patch adopts fallback call changes from the
vfs_read.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org>  3.16+

security/integrity/ima/ima_crypto.c

@@ -80,19 +80,19 @@ static int ima_kernel_read(struct file *file, loff_t offset,
 {
 	mm_segment_t old_fs;
 	char __user *buf = addr;
-	ssize_t ret;
+	ssize_t ret = -EINVAL;
 
 	if (!(file->f_mode & FMODE_READ))
 		return -EBADF;
-	if (!file->f_op->read && !file->f_op->aio_read)
-		return -EINVAL;
 
 	old_fs = get_fs();
 	set_fs(get_ds());
 	if (file->f_op->read)
 		ret = file->f_op->read(file, buf, count, &offset);
-	else
+	else if (file->f_op->aio_read)
 		ret = do_sync_read(file, buf, count, &offset);
+	else if (file->f_op->read_iter)
+		ret = new_sync_read(file, buf, count, &offset);
 	set_fs(old_fs);
 	return ret;
 }