Messages in this thread |  | | | From | "Henning P. Schmiedehausen" <> | | Subject | [2.4] ptrace bugfix breaks strace and keeps processes in STOPPED state (was: Re: How to fix the ptrace flaw without rebooting) | | Date | Sat, 5 Apr 2003 08:35:20 +0000 (UTC) |
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Alan Cox <alan@lxorguk.ukuu.org.uk> writes:
>On Gwe, 2003-04-04 at 12:18, Chuck Ebbert wrote: >> Erik Hensema wrote: >> >> >> > A better fix in a running system is to simply disable dynamic module >> > loading: echo /no/such/file > /proc/sys/kernel/modprobe >> >> >> You mean like this? >> >> # echo 'x'>/proc/sys/kernel/modprobe >> bash: /proc/sys/kernel/modprobe: No such file or directory
>Thats not a sufficient fix except for people blindly running the >example exploit
Speaking of the exploit fix: Since I run a kernel which has it installed, I can no longer strace processes which do run as root but have a gid sbit set, e.g.
# ls -la /tmp/bash -rwxr-sr-x 1 root smmsp 541096 Apr 5 10:21 /tmp/bash # id uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel) # /tmp/bash bash-2.05a# echo $$ 2625
(in another shell)
# strace -f -p 2625 trace: ptrace(PTRACE_SYSCALL, ...): Operation not permitted detach: ptrace(PTRACE_DETACH, ...): Operation not permitted
but the shell with the pid of 2625 is now "dead" until one sends it a SIGCONT:
# kill -CONT 2625
(other shell now works again)
% uname -an Linux henning-pc 2.4.18-27.7.x #1 Fri Mar 14 06:44:53 EST 2003 i686 unknown
I'm running the most current strace (4.4.94) because of the STOP/CONT problems before (RH bugzilla #64303, #75709) but this is new after installing the exploit fix.
(I found this BTW trying to trace sendmail that's why I have that test case with setgid to smmsp).
Regards Henning
-- Dipl.-Inf. (Univ.) Henning P. Schmiedehausen INTERMETA GmbH hps@intermeta.de +49 9131 50 654 0 http://www.intermeta.de/
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