From 566331696329c2f9ca0fe2a55a5dd029ac43d2d2 Mon Sep 17 00:00:00 2001 From: Ilias Apalodimas Date: Fri, 16 Sep 2022 11:14:34 +0300 Subject: [PATCH] efi/libstub: refactor the initrd measuring functions Currently, from the efi-stub, we are only measuring the loaded initrd, using the TCG2 measured boot protocols. A following patch is introducing measurements of additional components, such as the kernel command line. On top of that, we will shortly have to support other types of measured boot that don't expose the TCG2 protocols. So let's prepare for that, by rejigging the efi_measure_initrd() routine into something that we should be able to reuse for measuring other assets, and which can be extended later to support other measured boot protocols. Co-developed-by: Ilias Apalodimas Signed-off-by: Ilias Apalodimas Signed-off-by: Ard Biesheuvel --- .../firmware/efi/libstub/efi-stub-helper.c | 120 +++++++++++------- 1 file changed, 77 insertions(+), 43 deletions(-) diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c index aa6e73c0de2d..e0bb2025930b 100644 --- a/drivers/firmware/efi/libstub/efi-stub-helper.c +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c @@ -334,6 +334,79 @@ void efi_apply_loadoptions_quirk(const void **load_options, u32 *load_options_si *load_options_size = load_option_unpacked.optional_data_size; } +enum efistub_event { + EFISTUB_EVT_INITRD, + EFISTUB_EVT_COUNT, +}; + +#define STR_WITH_SIZE(s) sizeof(s), s + +static const struct { + u32 pcr_index; + u32 event_id; + u32 event_data_len; + u8 event_data[52]; +} events[] = { + [EFISTUB_EVT_INITRD] = { + 9, + INITRD_EVENT_TAG_ID, + STR_WITH_SIZE("Linux initrd") + }, +}; + +static efi_status_t efi_measure_tagged_event(unsigned long load_addr, + unsigned long load_size, + enum efistub_event event) +{ + 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) { + struct efi_measured_event { + efi_tcg2_event_t event_data; + efi_tcg2_tagged_event_t tagged_event; + u8 tagged_event_data[]; + } *evt; + int size = sizeof(*evt) + events[event].event_data_len; + + status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size, + (void **)&evt); + if (status != EFI_SUCCESS) + goto fail; + + evt->event_data = (struct efi_tcg2_event){ + .event_size = size, + .event_header.header_size = sizeof(evt->event_data.event_header), + .event_header.header_version = EFI_TCG2_EVENT_HEADER_VERSION, + .event_header.pcr_index = events[event].pcr_index, + .event_header.event_type = EV_EVENT_TAG, + }; + + evt->tagged_event = (struct efi_tcg2_tagged_event){ + .tagged_event_id = events[event].event_id, + .tagged_event_data_size = events[event].event_data_len, + }; + + memcpy(evt->tagged_event_data, events[event].event_data, + events[event].event_data_len); + + status = efi_call_proto(tcg2, hash_log_extend_event, 0, + load_addr, load_size, &evt->event_data); + efi_bs_call(free_pool, evt); + + if (status != EFI_SUCCESS) + goto fail; + return EFI_SUCCESS; + } + + return EFI_UNSUPPORTED; +fail: + efi_warn("Failed to measure data for event %d: 0x%lx\n", event, status); + return status; +} + /* * Convert the unicode UEFI command line to ASCII to pass to kernel. * Size of memory allocated return in *cmd_line_len. @@ -607,47 +680,6 @@ efi_status_t efi_load_initrd_cmdline(efi_loaded_image_t *image, &initrd->base, &initrd->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 @@ -671,8 +703,10 @@ efi_status_t efi_load_initrd(efi_loaded_image_t *image, status = efi_load_initrd_dev_path(&initrd, hard_limit); if (status == EFI_SUCCESS) { efi_info("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n"); - if (initrd.size > 0) - efi_measure_initrd(initrd.base, initrd.size); + if (initrd.size > 0 && + efi_measure_tagged_event(initrd.base, initrd.size, + EFISTUB_EVT_INITRD) == EFI_SUCCESS) + efi_info("Measured initrd data into PCR 9\n"); } else if (status == EFI_NOT_FOUND) { status = efi_load_initrd_cmdline(image, &initrd, soft_limit, hard_limit);