Re: CVE Request -- vsftpd -- Do not create network namespace per connection

[Jan Lieskovsky <jlieskov () redhat com>]

Hello Greg,

  you earlier mentioned this has been already fixed in newer kernels:

> This should already be fixed in the kernel, it looks like it's just
> older kernels that has the issue, if the distro enabled that specific
> option, so there's really nothing that needs to be done here, or a CVE
> assigned that I can tell, right?
>
> thanks,
>
> greg k-h

So the solution you describe above would be just disabling the net_ns
or some other fix? If the latter holds, could you point us to the 
relevant commit?

Thank you && Regards, Jan.
--
Jan iankko Lieskovsky / Red Hat Security Response Team

On 07/29/2011 10:37 AM, Eugene Teo wrote:
> On 06/07/2011 02:28 AM, Josh Bressers wrote:
> > ----- Original Message -----
> > > Hello, Josh, Steve, vendors,
> > >
> > > It was found that vsftpd, Very Secure FTP daemon, when the network
> > > namespace (CONFIG_NET_NS) support was activated in the kernel, used to
> > > create a new network namespace per connection. A remote attacker could
> > > use this flaw to cause a memory pressure and denial of the vsftpd
> > > service.
> > >
> > > References:
> > > [1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=629373
> > > [2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095
> > > [3] https://bugzilla.redhat.com/show_bug.cgi?id=711134
> > >
> > > This one being a bit tricky one -- from my understanding of the issue,
> > > vsftpd doesn't necessarily have a security flaw on its side. It's
> > > kernel issue / bug, which allows this to be used for vsftpd DoS:
> > > [4]
> > > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095/comments/31
> > > [5]
> > > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095/comments/32
> > >
> > > Short-term solution would be probably to address this on the vsftpd
> > > side, the long-term one then being to get this fixed in kernel.
> > >
> > > Though not sure, how it would be wrt to CVE identifier(s) assignment.
> >
> > I'm going to assign CVE-2011-2189 for the kernel. There are numerous
> > vendors shipping this bug.
> >
> > I'll leave it up to MITRE if they think vsftpd should get an ID. I don't
> > think it should myself, but they understand these corner cases better than
> > I.
>
> Kees, how are you guys fixing this? Disable net_ns and fix vsftpd? I
> wonder how other distros approach this. Any suggestions?
>
> Thanks, Eugene