On Mon, Feb 23, 2015 at 08:33:58AM -0800, Andy Lutomirski wrote: > On Mon, Feb 23, 2015 at 8:16 AM, Serge Hallyn <serge.hallyn@xxxxxxxxxx> wrote: > > Quoting Christoph Lameter (cl@xxxxxxxxx): > >> Ok 4.0-rc1 is out and this patch has been sitting here for a couple of > >> weeks without comment after an intensive discussion about the RFCs. > >> > >> Since there were no objections: Is there any chance to get this into -next > >> somehow? > > > > Andrew Morgan and Andy Lutomirski appear to have a similar concern > > but competing ideas on how to address them. We need them to agree > > on an approach. > > > > The core concern for amorgan is that an unprivileged user not be > > able to cause a privileged program to run in a way that it fails to > > drop privilege before running unprivileged-user-provided code. > > > > Andy Lutomirski's concern is simply that code which is currently > > doing the right thing to drop privilege not be run in a way that > > it thinks it is dropping privilege, but in fact is not. > > > > I share both concerns. > > > (Please correct me where I've mis-spoken or misunderstood) > > > > Since your desire is precisely for a mode where dropping privilege > > works as usual, but exec then re-gains some or all of that privilege, > > we need to either agree on a way to enter that mode that ordinary > > use caes can't be tricked into using, or find a way for legacy > > users to be tpiped off as to what's going on (without having to be > > re-written) > > Is there really a need to drop privilege and then regain it or is it > sufficient to keep the privilege permitted (and perhaps ambient, too) > and just to have execve not drop it for you? I assume the latter. Well right, any perceived security benefit of the temporary drop would seem to be easily debunked (just run shell for exec /bin/sh to get around it) So this is more of a desire, I suspect, for regular programs which drop privilege to still be usable in this environment. I think this may be a decent place for a compromise. Attempts to drop privilege when ambient caps are set return EPERM. -serge -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
