On Wed, Jan 04, 2017 at 10:57:51AM -0800, James Bottomley wrote: > > You are doing all this work to get the user space side in shape, I'd > > like to see matching kernel support. To me that means out-of-the-box > > a user can just use your plugins, the plugins will access /dev/tmps > > and everything will work fine for RSA key storage. > > Actually, not necessarily; you're not considering the setup issue: > right at the moment users get delivered TPMs mostly in the cleared
I have no problem with users being instructed to do 'sudo tpm2-provision' or having that happen via GUI using the usual privilege escalation techniques. > state (thankfully they no longer have to clear via bios). So the first > thing a new user has to do is set all the authorizations and create an > SRK equivalent primary object at 0x81000001. I think in the interests > of best practice we want to make that as easy as possible; saying they > have to do this as root and use a different device is problematic. The device names should never be exposed to the user. The user should specify a chip number (default to 0) and the tools should select the correct available device to do what the user is asking. First try /dev/tpms and elevate filter, then try /dev/tpmX, then fail. > You can say they don't have to use a different device because the > filter can be lifted for root, but then how do I lock down root apps > for this untrusted root setup secure boot has going on? Presumably the same way you lock down /dev/tpm0 today? selinux I guess? > I suppose we could use TPMA_PERMANENT for this. The first three bits > indicate whether the authorizations are set, so if they're all clear, > we can assume an unowned TPM and lift the filter? A sort of trust on > first use model. I feel tpm provisioning is something that should only be done by the system owner, and that means root in unix parlance. I don't want random end-users provisioning the TPM in my server, for instance. Jason
