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[tpmdd-devel] Fwd: [TrouSerS-users] tpm self test returns error 0xa?
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From: Kent Y. <shp...@gm...> - 2012-05-21 21:19:27
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Sending this over to the tpmdd list... Kent ---------- Forwarded message ---------- From: Luigi Semenzato <sem...@go...> Date: Mon, May 21, 2012 at 3:18 PM Subject: [TrouSerS-users] tpm self test returns error 0xa? To: tro...@li... Greetings, the new version of tpm_tis.c in Linux 3.4 is calling TPM_ContinueSelfTest in the probe function. I have a few questions. 1. why do we do this? Typically the self test is started in the firmware. Are we hitting cases in which the self test hasn't completed by the time the kernel has loaded and has reached the TPM driver? 2. the semantics of ContinueSelfTest are annoyingly vague. If the self test is not running, will ContinueSelfTest start it? Perhaps only if the self test hasn't been run since power on? Because otherwise it seems that running it another time might unnecessarily delay boot. 2. a comment in tpm_do_selftest mentions that some TPMs may return error 0xa (10) BAD_ORDINAL. In fact, that's what I am seeing on an Infineon TPM at boot. But... why? The TPM specification does not list error 0xa among those that can be returned by ContinueSelfTest. It almost seems that there could be an error in building the request packet, but the code seems equivalent to that before the change. I am almost thinking that we may need some additional kernel configuration settings to deal with various kinds of TPMs, not to mention board-level differences. For instance, some Chromebooks keep the TPM turned on during suspend-to-RAM (S3 state for x86), so the kernel doesn't need to save the state at suspend, and it would be better if it didn't. Thanks! Luigi ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ TrouSerS-users mailing list Tro...@li... https://lists.sourceforge.net/lists/listinfo/trousers-users -- IBM LTC Security |
