On 06/16/2010 01:11 PM, Stefan Berger wrote:
On 06/16/2010 02:54 PM, Jamie Strandboge wrote:
Hi,
I noticed today that ebiptablesWriteToTempFile() creates a temporary file in /tmp that is later executed. It uses mkstemp() and therefore is safe from symlinks attacks, however, there is not really any reason that I can see why it is using /tmp instead of somewhere like /var/lib/libvirt. If libvirtd is confined under a MAC which allows execution of /tmp/virtd* and a vulnerability is found in libvirtd, the /tmp path leaves an opportunity for a local non-root attacker to write a script in /tmp and then subvert libvirt to execute that script.
I don't mind the move of the temporary file, but I'd like to understand how would someone subvert libvirt to run an arbitrary script?
I'm with Stefan - the whole point of mkstemp is that the created file has 0600 permissions, and /tmp is restricted-deletion, so no other user can either overwrite the file contents or unlink it and replace it with an alternate file. Then again, gnulib documents that glibc 2.0.7 or older would create a file with group/other permissions if the umask wasn't set prior to the mkstemp() call, and gnulib's mkstemp() does not work around this issue; but that's a rather old version of glibc to be worrying about. -- Eric Blake eblake@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org