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From: mouse@lightning.mcrcim.mcgill.EDU (der Mouse)
Newsgroups: comp.windows.x
Subject: Re:  Xterm cannot write log files
Message-ID: <9104100652.AA06486@lightning.McRCIM.McGill.EDU>
Date: 10 Apr 91 06:52:38 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 34

> There's a really frustrating bug with Xterm, and I was wondering if
> anyone knew a way around it.

> For some reason, xterm is setuid root.  I don't know what good this
> does,

It's so that xterm can write /etc/utmp and change the owner of the
pseudo-tty it allocates.

> but it can prevent xterms from writing to log-files on NFS partitions
> (because NFS prevents root from writing across filesystems).

Or rather, a common (mis)feature in NFS implementations prevents it.
There is nothing about NFS per se that has anything to do with UID=0
accesses.

> This normally has no effect, but it can prevent the xterm from
> writing log files.

Under what circumstances?  I just did a test, and xterm was capable of
creating and writing a logfile under circumstances which prevented root
from creating files.  (UID 103, directory owned by UID 103 and mode
755, root could not create files there (with touch) but xterm -l did.)

> Is there any pressing reason for xterm to be suid root ?

Not unless you want utmp entries for your xterm windows.  (Unless you
make utmp world-writeable, which opens up other, fairly serious,
security holes, but that may be acceptable in trusting environments.)

					der Mouse

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			new: mouse@larry.mcrcim.mcgill.edu