Support BIOS SINIT modules #1470
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pcr-calc currently uses an ACM file to read out the SINIT capabilities to determine its calculations. Add an option to just directly provide the SINIT capabilities. This is useful for the case of a BIOS provided ACM when a file is unavailable. Otherwise pcr-calc will be unable to run and you cannot forward seal. Signed-off-by: Jason Andryuk <[email protected]>
You can have a machine do a measured launch from a BIOS-provided ACM when you don't have an SINIT ACM file. In that case, you cannot forward seal because ml-functions fails when it cannot find a file. Add a fallback mode for when a file cannot be found to parse the SINIT capabilities out of the txt-stat output. It's not pretty, but it may do the trick. Then you can use the new -C option to pcr-calc for the forward seal. Signed-off-by: Jason Andryuk <[email protected]>
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Unfortunately this is not ideal, but until a method is crafted to allow dom0 either access (direct memory) or details (expand tboot hypercall), this is probably the best way in the short term. |
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Intel doesn't really post SINIT modules anymore. Also, with Converged BootGuard and TXT (CBnT), the BIOS-provided ACM doesn't double duty for both BootGuard and TXT. It's something like there can be only a single BIOS ACM. Since it has to be there for BootGuard, it also does TXT.
Since there may not be an SINIT ACM on on disk to match against, we can't rely on it to parse the ACM caps. Instead (kinda ugly) grep it out of txt-stat output. It's logged there by tboot and we just need a single 32bit value.
pcr-calc is updated to accept ACM caps on the command line.