[Coco] Telnet to your CoCo.. and invite 6 of your friends

Joel Ewy jcewy at swbell.net
Tue Dec 1 16:31:09 EST 2009

Willard Goosey wrote:
> ...
>> Would it be hard to write a routine that would intercept such a call
>> and disable it, or disable it in some other way?
> Probably the easiest way is to grab the NitrOS-9 source and replace
> F$SETID with a stub that always fails.  Or expand the system call a
> little by making it check the current user number, and only allow user
> 0 to succeed.
> I'm not deep enough into OS-9 kernel hacking to know what would happen
> if there were multiple modules trying to provide the same system call.
> That might or might not be handled gracefully.

In theory, you can add new system calls by adding os9p[x] modules, and 
there are versions of os9p3 out there.  So your question is a good one:  
what if os9p3 implemented the F$SETID call?  Could that simply override 
the one in os9p2?  That would be interesting.


>> I would think that for a server there is no real
>> need to switch user IDs. 
> Security systems start getting complicated really quickly...
> Willard

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