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Re: CVE Request -- vsftpd -- Do not create network namespace per connection
From: Jan Lieskovsky <jlieskov () redhat com>
Date: Fri, 29 Jul 2011 11:31:43 +0200


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


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