Path: utzoo!attcan!uunet!bywater!scifi!njs
From: njs@scifi.UUCP (Nicholas J. Simicich)
Newsgroups: comp.sys.ibm.pc.rt
Subject: Re: Priorities and AIX 2.2.1
Message-ID: <928@scifi.UUCP>
Date: 19 Nov 89 21:12:43 GMT
References: <3485@nmtsun.nmt.edu>
Reply-To: njs@scifi.UUCP (Nicholas J. Simicich)
Organization: Nick Simicich, Peekskill, NY
Lines: 43

In article <3485@nmtsun.nmt.edu> peter@hydrovax.nmt.edu (Peter A. Blemel) writes:

 >   Many hours and faxes into the search, IBM tells me that the program
 >runs ON the VRM at an elevated priority. I checked, and sure enough -- the
 >program starts niced and then drops to prio 10. I have looked, and nothing
 >is setuid root (I have looked for any and all 'tps*' and 'leaf*' execs), the
 >owner (leafadm) is now in its own group, and I run it from an unpriveleged
 >account. It still can change its nice value.
 >
 >   I was under the impression that only a priv'd account could change the
 >nice value of an executing program. If this is correct, then how can
 >Interleaf change its priority from a vanilla account? Is this an indication
 >of some unknown security hole (how is it getting authorization to elevate
 >its priority)?

What is actually happening is that Interleaf is running as a monitor
mode program, I believe (I've never run Interleaf, but I've seen it
run from a distance of more than five feet).  (Monitor Mode is a
special mode which allows a running program to take over a monitor
completely and use the adapter directly without stepping on other
programs (X Windows, for example) which are also using the adapter
directly.)  AIX/RT believes that the program that is using the adapter
at the console should get good, smooth, consistent performance, and so
automatically nices it as it goes into Monitor Mode.  I think that
this is why, for example, that the X server runs at nice value 0.

X is a well behaved program, and probably should be run at nice 0.  It
seems that Interleaf is not.  (This behavior makes it difficult or
impossible to debug a monitor mode program which is in a loop.)

Thus, Interleaf is not changing its own nice value, that is being done
for it by AIX.  Any user that can go into monitor mode can get niced
in the same way.

If you think that this behavior is a bug, then call support.  You
might be able to get Interleaf to reset its nice value whenever it is
cranked, but I don't know.

If Interleaf runs under X, then geting that version might work for you
as well, as the program would no longer be in monitor mode.

-- 
Nick Simicich --- uunet!bywater!scifi!njs --- njs@ibm.com (Internet)