coreboot.git - my copy of coreboot

Age	Commit message (Collapse)	Author
2020-12-09	cbfs: Allow mcache to be found after the first lookup	Julius Werner
	This patch addresses the same problem as CB:48429, but hopefully this time correctly. Since the mcache is not guaranteed to be available on the first CBFS lookup for some special cases, we can no longer treat it as a one-time fire-and-forget initialization. Instead, we test cbd->mcache_size to check if the mcache has been initialized yet, and keep trying on every lookup if we don't find it the first time. Since the mcache is a hard requirement for TOCTOU safety, also make it more clear in Kconfig that configurations known to do CBFS accesses before CBMEM init are incompatbile with that, and make sure we die() rather than do something unsafe if there's a case that Kconfig didn't catch. Signed-off-by: Julius Werner <jwerner@chromium.org> Change-Id: I4e01e9a9905f7dcba14eaf05168495201ed5de60 Reviewed-on: https://review.coreboot.org/c/coreboot/+/48482 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Arthur Heymans <arthur@aheymans.xyz> Reviewed-by: Christian Walter <christian.walter@9elements.com> Reviewed-by: Angel Pons <th3fanbus@gmail.com>
2020-12-03	cbfs: Add verification for RO CBFS metadata hash	Julius Werner
	This patch adds the first stage of the new CONFIG_CBFS_VERIFICATION feature. It's not useful to end-users in this stage so it cannot be selected in menuconfig (and should not be used other than for development) yet. With this patch coreboot can verify the metadata hash of the RO CBFS when it starts booting, but it does not verify individual files yet. Likewise, verifying RW CBFSes with vboot is not yet supported. Verification is bootstrapped from a "metadata hash anchor" structure that is embedded in the bootblock code and marked by a unique magic number. This anchor contains both the CBFS metadata hash and a separate hash for the FMAP which is required to find the primary CBFS. Both are verified on first use in the bootblock (and halt the system on failure). The CONFIG_TOCTOU_SAFETY option is also added for illustrative purposes to show some paths that need to be different when full protection against TOCTOU (time-of-check vs. time-of-use) attacks is desired. For normal verification it is sufficient to check the FMAP and the CBFS metadata hash only once in the bootblock -- for TOCTOU verification we do the same, but we need to be extra careful that we do not re-read the FMAP or any CBFS metadata in later stages. This is mostly achieved by depending on the CBFS metadata cache and FMAP cache features, but we allow for one edge case in case the RW CBFS metadata cache overflows (which may happen during an RW update and could otherwise no longer be fixed because mcache size is defined by RO code). This code is added to demonstrate design intent but won't really matter until RW CBFS verification can be supported. Signed-off-by: Julius Werner <jwerner@chromium.org> Change-Id: I8930434de55eb938b042fdada9aa90218c0b5a34 Reviewed-on: https://review.coreboot.org/c/coreboot/+/41120 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Patrick Georgi <pgeorgi@google.com>