coreboot-kgpe-d16/src/security/vboot/vboot_loader.c

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/* SPDX-License-Identifier: GPL-2.0-only */
#include <boot_device.h>
#include <cbfs.h>
#include <cbmem.h>
#include <commonlib/bsd/cbfs_private.h>
#include <console/console.h>
#include <ec/google/chromeec/ec.h>
#include <rmodule.h>
#include <security/vboot/misc.h>
#include <security/vboot/symbols.h>
#include <security/vboot/vboot_common.h>
vboot: Disallow separate verstage after romstage, try to clarify logic No board has ever tried to combine CONFIG_SEPARATE_VERSTAGE with CONFIG_VBOOT_STARTS_IN_ROMSTAGE. There are probably many reasons why this wouldn't work (e.g. x86 CAR migration logic currently always assumes verstage code to run pre-migration). It would also not really make sense: the reason we use separate verstages is to decrease bootblock size (mitigating the boot speed cost of slow boot ROM SPI drivers) and to allow the SRAM-saving RETURN_FROM_VERSTAGE trick, neither of which would apply to the after-romstage case. It is better to just forbid that case explicitly and give programmers more guarantees about what the verstage is (e.g. now the assumption that it runs pre-RAM is always valid). Since Kconfig dependencies aren't always guaranteed in the face of 'select' statements, also add some explicit compile-time assertions to the vboot code. We can simplify some of the loader logic which now no longer needs to provide for the forbidden case. In addition, also try to make some of the loader logic more readable by writing it in a more functional style that allows us to put more assertions about which cases should be unreachable in there, which will hopefully make it more robust and fail-fast with future changes (e.g. addition of new stages). Change-Id: Iaf60040af4eff711d9b80ee0e5950ce05958b3aa Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/18983 Reviewed-by: Aaron Durbin <adurbin@chromium.org> Tested-by: build bot (Jenkins)
2017-03-18 00:54:48 +01:00
/* Ensure vboot configuration is valid: */
_Static_assert(CONFIG(VBOOT_STARTS_IN_BOOTBLOCK) +
CONFIG(VBOOT_STARTS_BEFORE_BOOTBLOCK) +
CONFIG(VBOOT_STARTS_IN_ROMSTAGE) == 1,
"vboot must start in bootblock, PSP or romstage (but only one!)");
_Static_assert(!CONFIG(VBOOT_SEPARATE_VERSTAGE) || CONFIG(VBOOT_STARTS_IN_BOOTBLOCK) ||
CONFIG(VBOOT_STARTS_BEFORE_BOOTBLOCK),
"stand-alone verstage must start in or before bootblock ");
_Static_assert(!CONFIG(VBOOT_RETURN_FROM_VERSTAGE) ||
CONFIG(VBOOT_SEPARATE_VERSTAGE),
vboot: Disallow separate verstage after romstage, try to clarify logic No board has ever tried to combine CONFIG_SEPARATE_VERSTAGE with CONFIG_VBOOT_STARTS_IN_ROMSTAGE. There are probably many reasons why this wouldn't work (e.g. x86 CAR migration logic currently always assumes verstage code to run pre-migration). It would also not really make sense: the reason we use separate verstages is to decrease bootblock size (mitigating the boot speed cost of slow boot ROM SPI drivers) and to allow the SRAM-saving RETURN_FROM_VERSTAGE trick, neither of which would apply to the after-romstage case. It is better to just forbid that case explicitly and give programmers more guarantees about what the verstage is (e.g. now the assumption that it runs pre-RAM is always valid). Since Kconfig dependencies aren't always guaranteed in the face of 'select' statements, also add some explicit compile-time assertions to the vboot code. We can simplify some of the loader logic which now no longer needs to provide for the forbidden case. In addition, also try to make some of the loader logic more readable by writing it in a more functional style that allows us to put more assertions about which cases should be unreachable in there, which will hopefully make it more robust and fail-fast with future changes (e.g. addition of new stages). Change-Id: Iaf60040af4eff711d9b80ee0e5950ce05958b3aa Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://review.coreboot.org/18983 Reviewed-by: Aaron Durbin <adurbin@chromium.org> Tested-by: build bot (Jenkins)
2017-03-18 00:54:48 +01:00
"return from verstage only makes sense for separate verstages");
int vboot_executed;
cbfs: Add verification for RO CBFS metadata hash 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>
2020-05-07 02:06:35 +02:00
static void after_verstage(void)
{
cbfs: Add verification for RO CBFS metadata hash 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>
2020-05-07 02:06:35 +02:00
vboot_executed = 1; /* Mark verstage execution complete. */
const struct cbfs_boot_device *cbd = vboot_get_cbfs_boot_device();
cbfs: Add verification for RO CBFS metadata hash 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>
2020-05-07 02:06:35 +02:00
if (!cbd) /* Can't initialize RW CBFS in recovery mode. */
return;
cbfs: Add verification for RO CBFS metadata hash 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>
2020-05-07 02:06:35 +02:00
cb_err_t err = cbfs_init_boot_device(cbd, NULL); /* TODO: RW hash */
if (err && err != CB_CBFS_CACHE_FULL) /* TODO: -> recovery? */
die("RW CBFS initialization failure: %d", err);
}
void vboot_run_logic(void)
{
if (verification_should_run()) {
/* Note: this path is not used for VBOOT_RETURN_FROM_VERSTAGE */
verstage_main();
cbfs: Add verification for RO CBFS metadata hash 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>
2020-05-07 02:06:35 +02:00
after_verstage();
} else if (verstage_should_load()) {
struct prog verstage =
PROG_INIT(PROG_VERSTAGE,
CONFIG_CBFS_PREFIX "/verstage");
printk(BIOS_DEBUG, "VBOOT: Loading verstage.\n");
if (cbfs_prog_stage_load(&verstage))
die("failed to load verstage");
/* verify and select a slot */
prog_run(&verstage);
/* This is not actually possible to hit this condition at
* runtime, but this provides a hint to the compiler for dead
* code elimination below. */
if (!CONFIG(VBOOT_RETURN_FROM_VERSTAGE))
return;
cbfs: Add verification for RO CBFS metadata hash 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>
2020-05-07 02:06:35 +02:00
after_verstage();
}
}
const struct cbfs_boot_device *vboot_get_cbfs_boot_device(void)
{
/* Don't honor vboot results until the vboot logic has run. */
if (!vboot_logic_executed())
return NULL;
static struct cbfs_boot_device cbd;
if (region_device_sz(&cbd.rdev))
return &cbd;
struct vb2_context *ctx = vboot_get_context();
if (ctx->flags & VB2_CONTEXT_RECOVERY_MODE)
return NULL;
boot_device_init();
if (vboot_locate_firmware(ctx, &cbd.rdev))
return NULL;
cbfs_boot_device_find_mcache(&cbd, CBMEM_ID_CBFS_RW_MCACHE);
return &cbd;
}