feat: extract standalone Event Log library
Extract the Event Log driver from TF-A into its own `libevlog` project.
Add a CMake-based build to support initialization, measurement,
recording, and dumping of TCG event logs across projects
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
Change-Id: I44dce25b3d67db94e5e0774174967433c2a5a377
diff --git a/src/event_log.c b/src/event_log.c
new file mode 100644
index 0000000..d59346b
--- /dev/null
+++ b/src/event_log.c
@@ -0,0 +1,315 @@
+/*
+ * Copyright (c) 2020-2025, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <string.h>
+
+#include "event_log.h"
+
+/* Running Event Log Pointer */
+static uint8_t *log_ptr;
+
+/* Pointer to the first byte past end of the Event Log buffer */
+static uintptr_t log_end;
+
+/* Hash function for event log operations set by user. */
+static const struct event_log_hash_info *crypto_hash_info;
+
+/* TCG_EfiSpecIdEvent */
+static const id_event_headers_t id_event_header = {
+ .header = { .pcr_index = PCR_0,
+ .event_type = EV_NO_ACTION,
+ .digest = { 0 },
+ .event_size =
+ (uint32_t)(sizeof(id_event_struct_t) +
+ (sizeof(id_event_algorithm_size_t) *
+ HASH_ALG_COUNT)) },
+
+ .struct_header = { .signature = TCG_ID_EVENT_SIGNATURE_03,
+ .platform_class = PLATFORM_CLASS_CLIENT,
+ .spec_version_minor = TCG_SPEC_VERSION_MINOR_TPM2,
+ .spec_version_major = TCG_SPEC_VERSION_MAJOR_TPM2,
+ .spec_errata = TCG_SPEC_ERRATA_TPM2,
+ .uintn_size = (uint8_t)(sizeof(unsigned int) /
+ sizeof(uint32_t)),
+ .number_of_algorithms = HASH_ALG_COUNT }
+};
+
+static const event2_header_t locality_event_header = {
+ /*
+ * All EV_NO_ACTION events SHALL set
+ * TCG_PCR_EVENT2.pcrIndex = 0, unless otherwise specified
+ */
+ .pcr_index = PCR_0,
+
+ /*
+ * All EV_NO_ACTION events SHALL set
+ * TCG_PCR_EVENT2.eventType = 03h
+ */
+ .event_type = EV_NO_ACTION,
+
+ /*
+ * All EV_NO_ACTION events SHALL set TCG_PCR_EVENT2.digests to all
+ * 0x00's for each allocated Hash algorithm
+ */
+ .digests = { .count = HASH_ALG_COUNT }
+};
+
+/* Message digest algorithm */
+enum crypto_md_algo {
+ CRYPTO_MD_SHA256,
+ CRYPTO_MD_SHA384,
+ CRYPTO_MD_SHA512,
+};
+
+int event_log_record(const uint8_t *hash, uint32_t event_type,
+ const event_log_metadata_t *metadata_ptr)
+{
+ void *ptr = log_ptr;
+ uint32_t name_len = 0U;
+
+ /* event_log_buf_init() must have been called prior to this. */
+ if (hash == NULL || metadata_ptr == NULL || log_ptr == NULL) {
+ return -EINVAL;
+ }
+
+ if (metadata_ptr->name != NULL) {
+ name_len = (uint32_t)strlen(metadata_ptr->name) + 1U;
+ }
+
+ /* Check for space in Event Log buffer */
+ if (((uintptr_t)ptr + (uint32_t)EVENT2_HDR_SIZE + name_len) > log_end) {
+ return -ENOMEM;
+ }
+
+ /*
+ * As per TCG specifications, firmware components that are measured
+ * into PCR[0] must be logged in the event log using the event type
+ * EV_POST_CODE.
+ */
+ /* TCG_PCR_EVENT2.PCRIndex */
+ ((event2_header_t *)ptr)->pcr_index = metadata_ptr->pcr;
+
+ /* TCG_PCR_EVENT2.EventType */
+ ((event2_header_t *)ptr)->event_type = event_type;
+
+ /* TCG_PCR_EVENT2.Digests.Count */
+ ptr = (uint8_t *)ptr + offsetof(event2_header_t, digests);
+ ((tpml_digest_values *)ptr)->count = HASH_ALG_COUNT;
+
+ /* TCG_PCR_EVENT2.Digests[] */
+ ptr = (uint8_t *)((uintptr_t)ptr +
+ offsetof(tpml_digest_values, digests));
+
+ /* TCG_PCR_EVENT2.Digests[].AlgorithmId */
+ ((tpmt_ha *)ptr)->algorithm_id = TPM_ALG_ID;
+
+ /* TCG_PCR_EVENT2.Digests[].Digest[] */
+ ptr = (uint8_t *)((uintptr_t)ptr + offsetof(tpmt_ha, digest));
+
+ /* Copy digest */
+ (void)memcpy(ptr, (const void *)hash, TCG_DIGEST_SIZE);
+
+ /* TCG_PCR_EVENT2.EventSize */
+ ptr = (uint8_t *)((uintptr_t)ptr + TCG_DIGEST_SIZE);
+ ((event2_data_t *)ptr)->event_size = name_len;
+
+ /* Copy event data to TCG_PCR_EVENT2.Event */
+ if (metadata_ptr->name != NULL) {
+ (void)memcpy((void *)(((event2_data_t *)ptr)->event),
+ (const void *)metadata_ptr->name, name_len);
+ }
+
+ /* End of event data */
+ log_ptr = (uint8_t *)((uintptr_t)ptr + offsetof(event2_data_t, event) +
+ name_len);
+
+ return 0;
+}
+
+int event_log_init(uint8_t *start, uint8_t *finish)
+{
+ if ((start == NULL || finish == NULL) || start > finish) {
+ return -EINVAL;
+ }
+
+ log_ptr = start;
+ log_end = (uintptr_t)finish;
+
+ return 0;
+}
+
+int event_log_write_specid_event(void)
+{
+ void *ptr;
+
+ /* event_log_buf_init() must have been called prior to this. */
+ if (log_ptr == NULL) {
+ return -EFAULT;
+ }
+
+ if (((uintptr_t)log_ptr + ID_EVENT_SIZE) > log_end) {
+ return -ENOMEM;
+ }
+
+ ptr = log_ptr;
+
+ /*
+ * Add Specification ID Event first
+ *
+ * Copy TCG_EfiSpecIDEventStruct structure header
+ */
+ (void)memcpy(ptr, (const void *)&id_event_header,
+ sizeof(id_event_header));
+ ptr = (uint8_t *)((uintptr_t)ptr + sizeof(id_event_header));
+
+ /* TCG_EfiSpecIdEventAlgorithmSize structure */
+ ((id_event_algorithm_size_t *)ptr)->algorithm_id = TPM_ALG_ID;
+ ((id_event_algorithm_size_t *)ptr)->digest_size = TCG_DIGEST_SIZE;
+ ptr = (uint8_t *)((uintptr_t)ptr + sizeof(id_event_algorithm_size_t));
+
+ /*
+ * TCG_EfiSpecIDEventStruct.vendorInfoSize
+ * No vendor data
+ */
+ ((id_event_struct_data_t *)ptr)->vendor_info_size = 0;
+ log_ptr = (uint8_t *)((uintptr_t)ptr +
+ offsetof(id_event_struct_data_t, vendor_info));
+
+ return 0;
+}
+
+int event_log_write_header(void)
+{
+ const char locality_signature[] = TCG_STARTUP_LOCALITY_SIGNATURE;
+ void *ptr;
+ int rc;
+
+ rc = event_log_write_specid_event();
+ if (rc < 0) {
+ return rc;
+ }
+
+ if (((uintptr_t)log_ptr + LOC_EVENT_SIZE) > log_end) {
+ return -ENOMEM;
+ }
+
+ ptr = log_ptr;
+
+ /*
+ * The Startup Locality event should be placed in the log before
+ * any event which extends PCR[0].
+ *
+ * Ref. TCG PC Client Platform Firmware Profile 9.4.5.3
+ */
+
+ /* Copy Startup Locality Event Header */
+ (void)memcpy(ptr, (const void *)&locality_event_header,
+ sizeof(locality_event_header));
+ ptr = (uint8_t *)((uintptr_t)ptr + sizeof(locality_event_header));
+
+ /* TCG_PCR_EVENT2.Digests[].AlgorithmId */
+ ((tpmt_ha *)ptr)->algorithm_id = TPM_ALG_ID;
+
+ /* TCG_PCR_EVENT2.Digests[].Digest[] */
+ (void)memset(&((tpmt_ha *)ptr)->digest, 0, TCG_DIGEST_SIZE);
+ ptr = (uint8_t *)((uintptr_t)ptr + offsetof(tpmt_ha, digest) +
+ TCG_DIGEST_SIZE);
+
+ /* TCG_PCR_EVENT2.EventSize */
+ ((event2_data_t *)ptr)->event_size =
+ (uint32_t)sizeof(startup_locality_event_t);
+ ptr = (uint8_t *)((uintptr_t)ptr + offsetof(event2_data_t, event));
+
+ /* TCG_EfiStartupLocalityEvent.Signature */
+ (void)memcpy(ptr, (const void *)locality_signature,
+ sizeof(TCG_STARTUP_LOCALITY_SIGNATURE));
+
+ /*
+ * TCG_EfiStartupLocalityEvent.StartupLocality = 0:
+ * the platform's boot firmware
+ */
+ ((startup_locality_event_t *)ptr)->startup_locality = 0U;
+ log_ptr =
+ (uint8_t *)((uintptr_t)ptr + sizeof(startup_locality_event_t));
+
+ return 0;
+}
+
+int event_log_measure(uintptr_t data_base, uint32_t data_size,
+ unsigned char *hash_data)
+{
+ if (crypto_hash_info == NULL) {
+ return -EINVAL;
+ }
+
+ return crypto_hash_info->func(crypto_hash_info->ids[0],
+ (void *)data_base, data_size, hash_data);
+}
+
+int event_log_init_and_reg(uint8_t *start, uint8_t *finish,
+ const struct event_log_hash_info *hash_info)
+{
+ int rc = event_log_init(start, finish);
+ if (rc < 0) {
+ return rc;
+ }
+
+ if (crypto_hash_info != NULL) {
+ return -EEXIST;
+ }
+
+ if (hash_info == NULL || hash_info->func == NULL ||
+ hash_info->count < 0 || hash_info->count > HASH_ALG_COUNT) {
+ return -EINVAL;
+ }
+
+ crypto_hash_info = hash_info;
+ return 0;
+}
+
+int event_log_measure_and_record(uintptr_t data_base, uint32_t data_size,
+ uint32_t data_id,
+ const event_log_metadata_t *metadata_ptr)
+{
+ unsigned char hash_data[MAX_DIGEST_SIZE];
+ int rc;
+
+ if (metadata_ptr == NULL) {
+ return -EINVAL;
+ }
+
+ /* Get the metadata associated with this image. */
+ while (metadata_ptr->id != data_id) {
+ if (metadata_ptr->id == EVLOG_INVALID_ID) {
+ return -EINVAL;
+ }
+
+ metadata_ptr++;
+ }
+
+ /* Measure the payload with algorithm selected by EventLog driver */
+ rc = event_log_measure(data_base, data_size, hash_data);
+ if (rc != 0) {
+ return rc;
+ }
+
+ rc = event_log_record(hash_data, EV_POST_CODE, metadata_ptr);
+ if (rc != 0) {
+ return rc;
+ }
+
+ return 0;
+}
+
+size_t event_log_get_cur_size(uint8_t *_start)
+{
+ assert(_start != NULL);
+ assert(log_ptr >= _start);
+
+ return (size_t)((uintptr_t)log_ptr - (uintptr_t)_start);
+}