I don't think that the Linux permission system can distinguish between local and remote accounts.
However, since each of your devices has its own account when accessing the Samba server, you could use ACLs to remove write permissions from a directory:
Code:
setfacl -m USER:r-x DIRECTORY
I suppose Samba also allows you to set permissions on shares, but I would have to research the mechanism. Giving control to Samba is the cleaner solution in my opinion.