On 10/04/2013 01:08 PM, Jason Gunthorpe wrote: > On Mon, Sep 30, 2013 at 05:09:51PM -0500, Joel Schopp wrote: > >>> So far, nobody I have talked to has offered any strong opinions on >>> what locality should be used or how it should be set. I think finding >>> a developer of trousers may be the most useful to talk about how the >>> ioctl portion of this would need to be set up - if someone is actually >>> needed. >> I am a TrouSerS developer and am ccing Richard, another TrouSerS >> developer, and ccing the trousers-tech list. It would be good if you >> could elaborate on the question and context for those not following the >> entire thread, myself included. > Two questions: > > Is userspace interested in using the TPM Locality feature, and if so > is there any thoughts on what the interface should be?
In terms of interface it should probably be an ioctl so that whoever holds the fd to /dev/tpm0 gets to choose the locality. Locality allows the resetting of certain PCRs. See section 3.7 in http://www.trustedcomputinggroup.org/files/static_page_files/8E45D739-1A4B-B294-D06274E7047730FD/TCG_PCClientTPMInterfaceSpecification_TIS__1-3_27_03212013.pdf Locality 4 can only be used by the hardware (section 2.2). Locality has an influence on the following TPM commands: TSC_ResetEstablishmentBit, Seal, Sealx, CreateWrapKey, UnSeal, GetPubKey, CMK_CreateKey, SHA1CompleteExtend, CertifyKey, Extend, PCR_Reset, NV_ReadValue, NV_WriteValue, and others. Some of the commands allow operations to succeed if a previously selected locality is also currently the chosen one. (If you have control over choosing the locality, at least that part won't prevent you from succeeding..) http://www.trustedcomputinggroup.org/files/static_page_files/72C33D71-1A4B-B294-D02C7DF86630BE7C/TPM%20Main-Part%203%20Commands_v1.2_rev116_01032011.pdf The worst would probably be if an application was to reset a PCR while another one is using that PCR or just for malicious purposes. Not providing support for choosing locality would mean that applications could still use PCRs 16 and 23 for their own purposes and can compete for their exclusive usage while being able to reset only those two. Are there use case for resetting PCRs from user space? If not I'd not support choice for locality from user space. Stefan > > Is the kernel interested in using the TPM Locality feature? What for? > > Jason > > ------------------------------------------------------------------------------ > October Webinars: Code for Performance > Free Intel webinars can help you accelerate application performance. > Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from > the latest Intel processors and coprocessors. See abstracts and register > > http://pubads.g.doubleclick.net/gampad/clk?id=60134791&iu=/4140/ostg.clktrk > _______________________________________________ > tpmdd-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/tpmdd-devel > ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60134791&iu=/4140/ostg.clktrk _______________________________________________ TrouSerS-tech mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/trousers-tech
