You don't need to run memcached as root to do that, you need to *start* it
as root.
If you look just under the setrlimit(RLIMIT_NOFILE code you see that the
privilege dropping happens.
So you fire up memcached *from* root, specifying -u memcached pand it will
do its root-y things and then drop privileges to that user already.
On Tue, 20 Jul 2010, Loganaden Velvindron wrote:
> It's useful when you need to run memcached as root (-u root).
>
>
> if (setrlimit(RLIMIT_NOFILE, &rlim) != 0) {
> fprintf(stderr, "failed to set rlimit for open files. Try running
> a$
> exit(EX_OSERR);
> }
>
> for upping rlimit.
>
> Once it's done setting rlimit, root privileges are no longer needed.
>
> Additionally, it chroots the process to /var/empty. If the attacker somehow
> succeeds in finding an exploit, he cannot execute commands like /bin/sh, since
> he's jailed inside the /var/empty.
>
>
> //Logan
> C-x-C-c
> On Tue, Jul 20, 2010 at 2:38 AM, dormando <[email protected]> wrote:
>
> > Greetings,
> >
> > We are a small company who are increasingly relying on
> > memcached for our big projects. We are very pleased with
> > its performance.
> >
> > I've put this patch that
> >
> > 1) chroots to /var/empty
> > 2) change from root to a simple user.
> >
> > It effectively jails the process once it no longer needs root
> > privilege and allows an attacker very little room to play.
> >
> > The patch has been working fine on our gentoo server for
> > quite some time.
> >
> > Feedback is most welcomed, and we are more than willing to
> > improve the patch to fit your standards.
>
> I'm a little confused; there is already a method for memcached to drop
> user privileges, by specifying the -u option? What's the purpose of this
> that the other function doesn't do?
>
>
>
>
> --
> `` Real men run current !''
>
>
>
>
>
>
>
