Oracle Linux can be freely downloaded and distributed. Oracle provides both ISO images of the installation media as well as individual RPM packages (incl. errata and updates) via the Oracle Linux Yum Server. Oracle Linux Vagrant Boxes are available here
The primary and official resource for getting Oracle Linux (and Oracle VM Server) ISO images is the Oracle Software Delivery Cloud (formerly known as E-Delivery).
Oracle Linux is also listed on DistroWatch and LQ ISO.
Additionally, the ISO images are available for direct download from the following mirror sites:
(Note that these mirrors are not run or managed by Oracle and this list is provided as a convenience only).