From f046fff8bc4c4d8f8a478022e76e40b818f692df Mon Sep 17 00:00:00 2001 From: Ilias Apalodimas Date: Fri, 19 Nov 2021 13:47:45 +0200 Subject: efi/libstub: measure loaded initrd info into the TPM In an effort to ensure the initrd observed and used by the OS is the same one that was meant to be loaded, which is difficult to guarantee otherwise, let's measure the initrd if the EFI stub and specifically the newly introduced LOAD_FILE2 protocol was used. Modify the initrd loading sequence so that the contents of the initrd are measured into PCR9. Note that the patch is currently using EV_EVENT_TAG to create the eventlog entry instead of EV_IPL. According to the TCP PC Client specification this is used for PCRs defined for OS and application usage. Co-developed-by: Ard Biesheuvel Signed-off-by: Ard Biesheuvel Signed-off-by: Ilias Apalodimas Link: https://lore.kernel.org/r/20211119114745.1560453-5-ilias.apalodimas@linaro.org [ardb: add braces to initializer of tagged_event_data] Link: https://github.com/ClangBuiltLinux/linux/issues/1547 Signed-off-by: Ard Biesheuvel --- drivers/firmware/efi/libstub/efi-stub-helper.c | 72 +++++++++++++++++++++----- 1 file changed, 58 insertions(+), 14 deletions(-) (limited to 'drivers/firmware/efi') diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c index 01677181453d..3d972061c1b0 100644 --- a/drivers/firmware/efi/libstub/efi-stub-helper.c +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c @@ -625,6 +625,47 @@ efi_status_t efi_load_initrd_cmdline(efi_loaded_image_t *image, load_addr, load_size); } +static const struct { + efi_tcg2_event_t event_data; + efi_tcg2_tagged_event_t tagged_event; + u8 tagged_event_data[]; +} initrd_tcg2_event = { + { + sizeof(initrd_tcg2_event) + sizeof("Linux initrd"), + { + sizeof(initrd_tcg2_event.event_data.event_header), + EFI_TCG2_EVENT_HEADER_VERSION, + 9, + EV_EVENT_TAG, + }, + }, + { + INITRD_EVENT_TAG_ID, + sizeof("Linux initrd"), + }, + { "Linux initrd" }, +}; + +static void efi_measure_initrd(unsigned long load_addr, unsigned long load_size) +{ + efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID; + efi_tcg2_protocol_t *tcg2 = NULL; + efi_status_t status; + + efi_bs_call(locate_protocol, &tcg2_guid, NULL, (void **)&tcg2); + if (tcg2) { + status = efi_call_proto(tcg2, hash_log_extend_event, + 0, load_addr, load_size, + &initrd_tcg2_event.event_data); + if (status != EFI_SUCCESS) + efi_warn("Failed to measure initrd data: 0x%lx\n", + status); + else + efi_info("Measured initrd data into PCR %d\n", + initrd_tcg2_event.event_data.event_header.pcr_index); + } +} + /** * efi_load_initrd() - Load initial RAM disk * @image: EFI loaded image protocol @@ -645,22 +686,25 @@ efi_status_t efi_load_initrd(efi_loaded_image_t *image, if (efi_noinitrd) { *load_addr = *load_size = 0; - return EFI_SUCCESS; + status = EFI_SUCCESS; + } else { + status = efi_load_initrd_dev_path(load_addr, load_size, hard_limit); + if (status == EFI_SUCCESS) { + efi_info("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n"); + if (*load_size > 0) + efi_measure_initrd(*load_addr, *load_size); + } else if (status == EFI_NOT_FOUND) { + status = efi_load_initrd_cmdline(image, load_addr, load_size, + soft_limit, hard_limit); + if (status == EFI_SUCCESS && *load_size > 0) + efi_info("Loaded initrd from command line option\n"); + } + if (status != EFI_SUCCESS) { + efi_err("Failed to load initrd: 0x%lx\n", status); + *load_addr = *load_size = 0; + } } - status = efi_load_initrd_dev_path(load_addr, load_size, hard_limit); - if (status == EFI_SUCCESS) { - efi_info("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n"); - } else if (status == EFI_NOT_FOUND) { - status = efi_load_initrd_cmdline(image, load_addr, load_size, - soft_limit, hard_limit); - if (status == EFI_SUCCESS && *load_size > 0) - efi_info("Loaded initrd from command line option\n"); - } - if (status != EFI_SUCCESS) { - efi_err("Failed to load initrd: 0x%lx\n", status); - *load_addr = *load_size = 0; - } return status; } -- cgit v1.2.3-59-g8ed1b