Blocks should provide more granular permissions

Currently the block module provides only one permission - 'administer blocks'. The custom_block module does not provide any permissions at all.

Sor right now a user with this permission can CRUD any blocks he wishes to.

I think having more granular permission system for blocks in place is desired.

It doesn't have to go into such extent as node module does but the user should be at least restricted to add new or delete an existing block(instance). Or re/move a block to/from a region, edit block he didn't authored and such.