Date: Wed, 12 Sep 2012 12:42:17 -0500 From: Raphael Geissert <geissert@...ian.org> To: Tomas Hoger <thoger@...hat.com>, oss-security@...ts.openwall.com Subject: Re: CVE request: opencryptoki insecure lock files handling On Sunday 09 September 2012 07:29:23 Tomas Hoger wrote: > On Fri, 7 Sep 2012 11:26:34 -0500 Raphael Geissert wrote: > > > There were following problems that I'm aware of: > > > > > > - /tmp/.pkapi_xpk - This was normally created by pcksslotd (running > > > as root). Symlink attack on this did not allow corrupting / > > > truncating files, but allowed creating new empty files at arbitrary > > > locations. > > > > > > - /tmp/.pkcs11spinloc - I believe this is created by opencryptoki > > > clients. In addition to the above, there's a chmod to make this > > > file world writable. This may get created by non-root user, but > > > chmod may still run later with root privileges later. > > > > > > Those files do not seem to get removed as part of the normal > > > operation, so replacing them with symlinks if they already exist is > > > limited by /tmp stickiness. Attacker does not need to be pkcs11 > > > group member. > > > > Correct, and to make it clear: /tmp/.pkcs11spinloc *is* chmod'ed by > > pcksslotd to make it world-writable. > > When do pkcsslotd does that, and which version? It does not happen on > its start or stop, or when client as pkcsconf queries for some data. I apparently confused it with another set of CreateXProcLock and XProcUnLock's. pkcsslotd indeed doesn't seem to chmod spinloc. Regarding /tmp/.pkapi_xpk, it is created by pkcsslotd with S_IRWXU|S_IRWXG| S_IRWXO (but not chmoded). Upstream's init script seems to set a umask of 077, but at least Debian's doesn't :-/ > If pkcs11 group member can make pkcsslotd chmod lock file, pkcs11 group > membership need to be assumed root equivalent without any additional > condition. Agreed. Cheers, -- Raphael Geissert - Debian Developer www.debian.org - get.debian.net
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