Re: setuid vs. setgid (was Re: Anonymous Qmail Denial of Service)

From: Kragen Sitaker (kragenat_private)
Date: Sat Jan 09 1999 - 17:19:43 PST

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    On Fri, 8 Jan 1999, Thamer Al-Herbish wrote:
    > > Maybe getuid() is the "best" you can do, maybe not.  A lot of the OS's
    > > these days have some sort of audit id which is sometimes less flexible
    > > than uid's when it comes to change.
    >
    > To be extra pedantic use getlogin() to double check. getlogin cannot
    > lie unless you are root and did a setlogin().
    
    This is a joke, I assume.
    
    >From the Linux man page for getlogin():
    
    BUGS
           Unfortunately, it is often rather easy to fool getlogin().
           Sometimes it does not work at all,  because  some  program
           messed  up the utmp file.
    
    This is the traditional getlogin() behavior, IIRC.
    
    You might be correct if you are on a system where utmp is not
    world-writable and all the programs that modify it are properly
    secure.
    
    --
    <kragenat_private>       Kragen Sitaker     <http://www.pobox.com/~kragen/>
    A good conversation and even lengthy and heated conversations are probably
    some of the most important pointful things I can think of.  They are the
    antithesis of pointlessness!  -- Matt O'Connor <matthew@anti-earth.org>
    



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