Setuid script not working

druidmatrix has asked for the wisdom of the Perl Monks concerning the following question:

Hello Monks,

I have a simple setuid script:

#!/usr/bin/perl -T
#
use POSIX qw(setuid setgid);
if ($<) {
        $( = $) = 0;
        $< = $> = 0;
        print "Could not setuid ".$<." \n" if ($<);
        POSIX::setuid(0) if ($<);
        print "Posix could not setuid either ".$<." \n" if ($<);
}
[download]

I have the sticky bit set and the file is owned by root:

-rwsrwx--- 1 root csit 237 2010-04-30 01:16 setuid.pl
[download]

The output to the above is:

Could not setuid 500
Posix could not setuid either 500
[download]

My perl version is v5.10.1 and this is running on Fedora 10. I have also set selinux enforcing to "permissive".

TIA.

Comment on Setuid script not working Select or Download Code

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Re: Setuid script not working by afoken (Chancellor) on Apr 30, 2010 at 05:57 UTC
Why did you omit any error checking? perlvar clearly states: Since changes to `$<` require a system call, check `$!` after a change attempt to detect any possible errors, similar statements exist for `$>`, `$(`, and `$)`. Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply] [d/l] [select]
Re^2: Setuid script not working by druidmatrix (Acolyte) on Apr 30, 2010 at 06:06 UTC
Thank you for your response. I looked for $! and sure enough it is populated, but does not explain why it failed. `$< = $> = 0; print "Could not setuid ".$<." error: $! \n" if ($<); POSIX::setuid(0) if ($<); print "Posix could not setuid either ".$<." error: $! \n" if ( +$<);` [download] It now produces: `Could not setuid 500 error: Operation not permitted Posix could not setuid either 500 error: Operation not permitted` [download]	[reply] [d/l] [select]
Re^3: Setuid script not working by Anonymous Monk on Apr 30, 2010 at 07:03 UTC
but does not explain why it failed. Yes it does, Operation not permitted. Oh you want to know why it isn't permitted? You'll have to rule out each possibility (or use strace, OS usually doesn't provide backtrace)	[reply]
Re^4: Setuid script not working by afoken (Chancellor) on Apr 30, 2010 at 07:51 UTC
Re^4: Setuid script not working by ikegami (Patriarch) on Apr 30, 2010 at 21:12 UTC
Re^4: Setuid script not working by druidmatrix (Acolyte) on Apr 30, 2010 at 07:53 UTC
Re^5: Setuid script not working by Anonymous Monk on Apr 30, 2010 at 08:44 UTC
Re^4: Setuid script not working by druidmatrix (Acolyte) on Apr 30, 2010 at 08:50 UTC
Re: Setuid script not working by MidLifeXis (Monsignor) on Apr 30, 2010 at 13:32 UTC
I have the sticky bit set and the file is owned by root: Just as a terminology clarification, this is the setuid bit, not the sticky bit. The sticky bit has a very different meaning from setuid bit or setgid bit. It also behaves differently based on if the target is a file or a directory. The documentation and behavior of what the sticky bit does is typically not well understood among even experienced system administrators (my own experience), partly due to poor, incomplete, or inconsistent documentation of the bit and infrequent use. --MidLifeXis	[reply]
Re^2: Setuid script not working by druidmatrix (Acolyte) on Apr 30, 2010 at 18:49 UTC
Good point. I stand corrected. Thank you.	[reply]
Re: Setuid script not working by Khen1950fx (Canon) on Apr 30, 2010 at 05:41 UTC
My guess is that you might need to download and install the perl-suidperl rpm for Fedora 10.	[reply]
Re^2: Setuid script not working by druidmatrix (Acolyte) on Apr 30, 2010 at 06:11 UTC
This would not be possible since since the perl install is a custom build, and not from an RPM. Are you saying that there is a switch to turn on setuid scripts for the Configure script (and by default it is off)? In that case would you please elaborate, since I didn't find that?	[reply]
Re^3: Setuid script not working by Anonymous Monk on Apr 30, 2010 at 07:00 UTC
`$ perl "-V:.?suid.?" d_dosuid='undef'; d_setresuid='undef'; d_suidsafe='undef';` [download] http://perl5.git.perl.org/perl.git?a=search&h=HEAD&st=grep&s=suid	[reply] [d/l]
Re^4: Setuid script not working by druidmatrix (Acolyte) on Apr 30, 2010 at 07:48 UTC
Re^5: Setuid script not working by Anonymous Monk on Apr 30, 2010 at 08:38 UTC
Some notes below your chosen depth have not been shown here


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