Section 24 and 80c

Tax benefits on Joint home loans are available to all the joint holders. However, ownership is a prerequisite to avail any tax benefit. So there are two things

1. You must be co-owner in the property and 
2. You must be co-borrower for the loan

In your case, since your son is co-applicant of the loan but he is not the co-owner of the property, therefore he is devoid of tax benefit on the home loan. So, it is you (father, in your case) only who can claim the tax benefit.

Thanks