On Tue, Jan 03, 2017 at 02:47:02PM -0700, Jason Gunthorpe wrote: > On Tue, Jan 03, 2017 at 08:36:10AM -0800, James Bottomley wrote: > > > > I'm not sure about this. Why you couldn't have a very thin daemon > > > that prepares the file descriptor and sends it through UDS socket to > > > a client. > > > > So I'm a bit soured on daemons from the trousers experience: tcsd > > crashed regularly and when it did it took all the TPM connections down > > irrecoverably. I'm not saying we can't write a stateless daemon to fix > > most of the trousers issues, but I think it's valuable first to ask the > > question, "can we manage without a daemon at all?" I actually think > > the answer is "yes", so I'm interested in seeing how far that line of > > research gets us. > > There is clearly no need for a daemon to be involved when working on > simple tasks like key load and key sign/enc/dec actions, adding such a > thing only increases the complexity. > > If we discover a reason to have a daemon down the road then it should > work in some way where the user space can call out to the daemon over > a different path than the kernel. (eg dbus or something) > > > Do you have a link to the presentation? The Plumbers etherpad doesn't > > contain it. I've been trying to work out whether a properly set up TPM > > actually does need any protections at all. As far as I can tell, once > > you've set all the hierarchy authorities and the lockout one, you're > > pretty well protected. > > I think we should also consider TPM 1.2 support in all of this, it is > still a very popular peice of hardware and it is equally able to > support a RM.
I'm not against considering TPM 1.2 support but getting both in the same patch set would be too much. > > So, in general, I'd prefer to see the unprivileged char dev hard > prevented by the kernel from doing certain things: > > - Wipe the TPM > - Manipulate the SRK, nvram, tpm flags, change passwords etc > - Read back the EK > - Write to PCRs > - etc. I rather have an ioctl where you can supply a list of CCs that you want to allow a client to do. /Jarkko > Even if TPM 2 has a stronger password based model, I still think the > kernel should hard prevent those sorts of actions even if the user > knows the TPM password. > > Realistically people in less senstive environments will want to use > the well known TPM passwords and still have reasonable safety in their > unprivileged accounts. > > Jason
