[libvirt] [PATCH v9 06/17] qemu: Extend QEMU with external TPM support

[Stefan Berger]

On 06/06/2018 09:08 PM, bushuanshuan wrote:
>
> ...
>
> > +static int
>
> > +qemuExtTPMStartEmulator(virQEMUDriverPtr driver,
>
> > +                        virDomainDefPtr def,
>
> > +                        qemuDomainLogContextPtr logCtxt)
>
> > +{
>
> ...
>
> > +    if (!(cmd = qemuTPMEmulatorBuildCommand(tpm, def->name, def->uuid,
>
> > + driver->privileged,
>
> > +    cfg->swtpm_user,
>
> > + cfg->swtpm_group)))
>
> > +        goto cleanup;
>
> > +
>
> > +    if (qemuExtDeviceLogCommand(logCtxt, cmd, "TPM Emulator") < 0)
>
> > +        goto cleanup;
>
> > +
>
> > +   virCommandSetErrorBuffer(cmd, &errbuf);
>
> > +
>
> > +    if (virCommandRun(cmd, &exitstatus) < 0 || exitstatus != 0) {
>
> > +       virReportError(VIR_ERR_INTERNAL_ERROR,
>
> > +                       _("Could not start 'swtpm'. exitstatus: %d, "
>
> > +                         "error: %s"), exitstatus, errbuf);
>
> > +        goto cleanup;
>
> > +    }
>
> Now that the sensitive data in NVRAM need to be protected,  it might 
> be a feasible way that swtpm uses the 'key' to encrypt it when VM 
> shutdown.
>
> I wonder why don't use the key when swtpm process is launched here.
>

Adding support for vTPM state encryption can be added later on, but then 
only be used for newly created vTPMs (those that are not encyrpted 
remain not encrypted).

> Of course, we should avoid to let the key exposed in system log when 
> we design the encryption scheme.
>
> Another question is: where we can store the key securely. Maybe 
> physical TPM can help this.
>
> What do you think about this question?
>

libvirt supports 'secrets' and they could be encrypted by a TPM. So far 
I think they are primarily protected through file access control bits.

     Stefan

> ...
>
> Thanks,
>
> Shuanshuan Bu
>

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