Re: [Ksummit-discuss] [TrouSerS-tech] TPM MiniSummit @ LinuxCon Europe

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

On 09/23/2014 12:42 PM, Andy Lutomirski wrote:
> On Sep 22, 2014 2:07 AM, "Peter Huewe" <PeterHuewe@gmx.de> wrote:
>> Hi,
>>
>> I would like to 'invite' all interested parties in a short TPM minisummit where we can discuss the following hot topics of the TPM subsystem over a beer or two:
>>   - State of the TPM Subsystem
>>   - De-/Initialization Mess
>>   - Devm'ification
>>   - Testing
>>   - TPM 2.0 Support
>>   - Dependencies / interaction with other subsystems (e.g. keyring / IMA)
>>   - Status of old 1.1b TPM drivers, deprecation plans
>>   - ...
>>
> I am unlikely to be there, but I have a feature request / food for thought:
>
> Using a mandatory userspace daemon (e.g. trousers) for TPM access
> sucks.  Might it be possible to teach the kernel to handle context
> save and restore and let multiple processes open the device at once?
> Then a daemon wouldn't be necessary.

Why add the complexity of swapping of authenticated sessions and keys 
into the kernel if you can handle this in userspace? You need a library 
that is aware of the number of key slots and slots for sessions in the 
TPM and swaps them in at out when applications need them. Trousers is 
such a library that was designed to cope with the limitations of the 
device and make its functionality available to all applications that 
want to access it.

    Stefan

>
> There would still be a need for some policy (e.g. who can clear the
> SRK), but that should be manageable.  Maybe there should be two device
> nodes.  /dev/tpm_unpriv would be fully virtualized for access by
> multiple processes, but it would only allow use of the key hierarchy
> and read access to PCRs.  /dev/tpm_priv would allow NV access, PCR
> writes, SRK clears, etc.
>
> --Andy
>
>> Please register your interest by filling out this doodle
>>   http://doodle.com/q9ezcrivhqrktw6u
>>
>> I'm not sure if I can get any funding for the summit... but maybe I can arrange something.
>>
>>
>> Also I'm trying to bring along some TPM samples from my employer if possible.
>>
>>
>> Thanks
>> Peter
>>
>> p.s.: experienced kernel developers welcome :)
>> _______________________________________________
>> Ksummit-discuss mailing list
>> Ksummit-discuss@lists.linuxfoundation.org
>> https://lists.linuxfoundation.org/mailman/listinfo/ksummit-discuss
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