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From: klier@cs.tu-berlin.de (Jan Klier)
Newsgroups: comp.os.386bsd.development
Subject: SIGKILL and kill
Date: 17 Apr 1993 05:14:02 GMT
Organization: Technical University of Berlin, Germany
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Message-ID: <1qo3mq$d4b@news.cs.tu-berlin.de>
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Summary: suggestion: restricting SIGKILL to root in the kill program
Keywords: SIGNALS SECURITY
Hi 386bsd community,
I don't know if this is the right place to post such things, so if no please
appologize.
From my experience as administrator and user of Unix systems I have a
suggestion for a little change which could increase the system security
for the user themselves.
I experienced that many users often use the command 'kill -9 pid' to kill
a process instead of the simple version 'kill pid'. But if the SIGKILL signal
is used to terminate a process the user will get rid of, the process itself
has no chance to catch that and cleanup it's own data structure, flushing
some buffers, updating databases etc.
Most often the TERM signal will do the same job, users just don't know about
the difference between KILL and TERM and risk (unconciously) loosing data.
My idea is now (and I post it here because it could be tested experimentally
in 386bsd) to modify the kill-programm in order to restrict the SIGKILL signal
to the superuser.
This will force users to use the safe TERM-signal when the terminate processes
and still leaves the door open for really hung situation where a SIGKILL is
necessary.
Any comments?
jan
--
*******************************************************************************
Jan Klier Berlin, Germany
e-mail: klier.cs.tu-berlin.de cis : 100022,1700
| jklier.ipk.fhg.de | 100022.1700@compuserve.com