Open Berkeley sites support the campus Berkeley Brand standards. The Berkeley wordmark, site name font, and Cal favicon (the icon displayed in the browser's tab bar) are part of the Berkeley Brand. See our documentation on Berkeley Brand theme options for information on how to configure the display of your site's header and footer. Also we encourage you to reach out to the Brand team at https://brand.berkeley.edu/contact/ to see if they can consult with you or your team on understanding campus branding guidelines.
Although the Berkeley Brand does not allow custom logos in the header, you have the option to place your own logo in the footer, or on your home page or landing page for a particular section. You can create a reusable widget that would allow you to place the same logo image on multiple pages.