tpm: Support boot measurements

Add TPM2 functions to support boot measurement. This includes
starting up the TPM, initializing/appending the event log, and
measuring the U-Boot version. Much of the code was used in the
EFI subsystem, so remove it there and use the common functions.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
For the API moving around from EFI -> u-boot core
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
For EFI testing
Tested-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

1 files changed, 814 insertions, 0 deletions

diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
index 9ab5b46df17..bd0fb078dc3 100644
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -1,16 +1,705 @@
 // SPDX-License-Identifier: GPL-2.0+
 /*
+ * Copyright (c) 2023 Linaro Limited
  * Copyright (c) 2018 Bootlin
  * Author: Miquel Raynal <miquel.raynal@bootlin.com>
  */
 
 #include <common.h>
 #include <dm.h>
+#include <dm/of_access.h>
+#include <tpm_api.h>
 #include <tpm-common.h>
 #include <tpm-v2.h>
+#include <u-boot/sha1.h>
+#include <u-boot/sha256.h>
+#include <u-boot/sha512.h>
+#include <version_string.h>
+#include <asm/io.h>
 #include <linux/bitops.h>
+#include <linux/unaligned/be_byteshift.h>
+#include <linux/unaligned/generic.h>
+#include <linux/unaligned/le_byteshift.h>
+
 #include "tpm-utils.h"
 
+const enum tpm2_algorithms tpm2_supported_algorithms[4] = {
+	TPM2_ALG_SHA1,
+	TPM2_ALG_SHA256,
+	TPM2_ALG_SHA384,
+	TPM2_ALG_SHA512,
+};
+
+int tcg2_get_active_pcr_banks(struct udevice *dev, u32 *active_pcr_banks)
+{
+	u32 supported = 0;
+	u32 pcr_banks = 0;
+	u32 active = 0;
+	int rc;
+
+	rc = tpm2_get_pcr_info(dev, &supported, &active, &pcr_banks);
+	if (rc)
+		return rc;
+
+	*active_pcr_banks = active;
+
+	return 0;
+}
+
+u32 tcg2_event_get_size(struct tpml_digest_values *digest_list)
+{
+	u32 len;
+	size_t i;
+
+	len = offsetof(struct tcg_pcr_event2, digests);
+	len += offsetof(struct tpml_digest_values, digests);
+	for (i = 0; i < digest_list->count; ++i) {
+		u16 l = tpm2_algorithm_to_len(digest_list->digests[i].hash_alg);
+
+		if (!l)
+			continue;
+
+		len += l + offsetof(struct tpmt_ha, digest);
+	}
+	len += sizeof(u32);
+
+	return len;
+}
+
+int tcg2_create_digest(struct udevice *dev, const u8 *input, u32 length,
+		       struct tpml_digest_values *digest_list)
+{
+	u8 final[sizeof(union tpmu_ha)];
+	sha256_context ctx_256;
+	sha512_context ctx_512;
+	sha1_context ctx;
+	u32 active;
+	size_t i;
+	u32 len;
+	int rc;
+
+	rc = tcg2_get_active_pcr_banks(dev, &active);
+	if (rc)
+		return rc;
+
+	digest_list->count = 0;
+	for (i = 0; i < ARRAY_SIZE(tpm2_supported_algorithms); ++i) {
+		u32 mask =
+			tpm2_algorithm_to_mask(tpm2_supported_algorithms[i]);
+
+		if (!(active & mask))
+			continue;
+
+		switch (tpm2_supported_algorithms[i]) {
+		case TPM2_ALG_SHA1:
+			sha1_starts(&ctx);
+			sha1_update(&ctx, input, length);
+			sha1_finish(&ctx, final);
+			len = TPM2_SHA1_DIGEST_SIZE;
+			break;
+		case TPM2_ALG_SHA256:
+			sha256_starts(&ctx_256);
+			sha256_update(&ctx_256, input, length);
+			sha256_finish(&ctx_256, final);
+			len = TPM2_SHA256_DIGEST_SIZE;
+			break;
+		case TPM2_ALG_SHA384:
+			sha384_starts(&ctx_512);
+			sha384_update(&ctx_512, input, length);
+			sha384_finish(&ctx_512, final);
+			len = TPM2_SHA384_DIGEST_SIZE;
+			break;
+		case TPM2_ALG_SHA512:
+			sha512_starts(&ctx_512);
+			sha512_update(&ctx_512, input, length);
+			sha512_finish(&ctx_512, final);
+			len = TPM2_SHA512_DIGEST_SIZE;
+			break;
+		default:
+			printf("%s: unsupported algorithm %x\n", __func__,
+			       tpm2_supported_algorithms[i]);
+			continue;
+		}
+
+		digest_list->digests[digest_list->count].hash_alg =
+			tpm2_supported_algorithms[i];
+		memcpy(&digest_list->digests[digest_list->count].digest, final,
+		       len);
+		digest_list->count++;
+	}
+
+	return 0;
+}
+
+void tcg2_log_append(u32 pcr_index, u32 event_type,
+		     struct tpml_digest_values *digest_list, u32 size,
+		     const u8 *event, u8 *log)
+{
+	size_t len;
+	size_t pos;
+	u32 i;
+
+	pos = offsetof(struct tcg_pcr_event2, pcr_index);
+	put_unaligned_le32(pcr_index, log);
+	pos = offsetof(struct tcg_pcr_event2, event_type);
+	put_unaligned_le32(event_type, log + pos);
+	pos = offsetof(struct tcg_pcr_event2, digests) +
+		offsetof(struct tpml_digest_values, count);
+	put_unaligned_le32(digest_list->count, log + pos);
+
+	pos = offsetof(struct tcg_pcr_event2, digests) +
+		offsetof(struct tpml_digest_values, digests);
+	for (i = 0; i < digest_list->count; ++i) {
+		u16 hash_alg = digest_list->digests[i].hash_alg;
+
+		len = tpm2_algorithm_to_len(hash_alg);
+		if (!len)
+			continue;
+
+		pos += offsetof(struct tpmt_ha, hash_alg);
+		put_unaligned_le16(hash_alg, log + pos);
+		pos += offsetof(struct tpmt_ha, digest);
+		memcpy(log + pos, (u8 *)&digest_list->digests[i].digest, len);
+		pos += len;
+	}
+
+	put_unaligned_le32(size, log + pos);
+	pos += sizeof(u32);
+	memcpy(log + pos, event, size);
+}
+
+static int tcg2_log_append_check(struct tcg2_event_log *elog, u32 pcr_index,
+				 u32 event_type,
+				 struct tpml_digest_values *digest_list,
+				 u32 size, const u8 *event)
+{
+	u32 event_size;
+	u8 *log;
+
+	event_size = size + tcg2_event_get_size(digest_list);
+	if (elog->log_position + event_size > elog->log_size) {
+		printf("%s: log too large: %u + %u > %u\n", __func__,
+		       elog->log_position, event_size, elog->log_size);
+		return -ENOBUFS;
+	}
+
+	log = elog->log + elog->log_position;
+	elog->log_position += event_size;
+
+	tcg2_log_append(pcr_index, event_type, digest_list, size, event, log);
+
+	return 0;
+}
+
+static int tcg2_log_init(struct udevice *dev, struct tcg2_event_log *elog)
+{
+	struct tcg_efi_spec_id_event *ev;
+	struct tcg_pcr_event *log;
+	u32 event_size;
+	u32 count = 0;
+	u32 log_size;
+	u32 active;
+	u32 mask;
+	size_t i;
+	u16 len;
+	int rc;
+
+	rc = tcg2_get_active_pcr_banks(dev, &active);
+	if (rc)
+		return rc;
+
+	event_size = offsetof(struct tcg_efi_spec_id_event, digest_sizes);
+	for (i = 0; i < ARRAY_SIZE(tpm2_supported_algorithms); ++i) {
+		mask = tpm2_algorithm_to_mask(tpm2_supported_algorithms[i]);
+
+		if (!(active & mask))
+			continue;
+
+		switch (tpm2_supported_algorithms[i]) {
+		case TPM2_ALG_SHA1:
+		case TPM2_ALG_SHA256:
+		case TPM2_ALG_SHA384:
+		case TPM2_ALG_SHA512:
+			count++;
+			break;
+		default:
+			continue;
+		}
+	}
+
+	event_size += 1 +
+		(sizeof(struct tcg_efi_spec_id_event_algorithm_size) * count);
+	log_size = offsetof(struct tcg_pcr_event, event) + event_size;
+
+	if (log_size > elog->log_size) {
+		printf("%s: log too large: %u > %u\n", __func__, log_size,
+		       elog->log_size);
+		return -ENOBUFS;
+	}
+
+	log = (struct tcg_pcr_event *)elog->log;
+	put_unaligned_le32(0, &log->pcr_index);
+	put_unaligned_le32(EV_NO_ACTION, &log->event_type);
+	memset(&log->digest, 0, sizeof(log->digest));
+	put_unaligned_le32(event_size, &log->event_size);
+
+	ev = (struct tcg_efi_spec_id_event *)log->event;
+	strlcpy((char *)ev->signature, TCG_EFI_SPEC_ID_EVENT_SIGNATURE_03,
+		sizeof(ev->signature));
+	put_unaligned_le32(0, &ev->platform_class);
+	ev->spec_version_minor = TCG_EFI_SPEC_ID_EVENT_SPEC_VERSION_MINOR_TPM2;
+	ev->spec_version_major = TCG_EFI_SPEC_ID_EVENT_SPEC_VERSION_MAJOR_TPM2;
+	ev->spec_errata = TCG_EFI_SPEC_ID_EVENT_SPEC_VERSION_ERRATA_TPM2;
+	ev->uintn_size = sizeof(size_t) / sizeof(u32);
+	put_unaligned_le32(count, &ev->number_of_algorithms);
+
+	count = 0;
+	for (i = 0; i < ARRAY_SIZE(tpm2_supported_algorithms); ++i) {
+		mask = tpm2_algorithm_to_mask(tpm2_supported_algorithms[i]);
+
+		if (!(active & mask))
+			continue;
+
+		len = tpm2_algorithm_to_len(tpm2_supported_algorithms[i]);
+		if (!len)
+			continue;
+
+		put_unaligned_le16(tpm2_supported_algorithms[i],
+				   &ev->digest_sizes[count].algorithm_id);
+		put_unaligned_le16(len, &ev->digest_sizes[count].digest_size);
+		count++;
+	}
+
+	*((u8 *)ev + (event_size - 1)) = 0;
+	elog->log_position = log_size;
+
+	return 0;
+}
+
+static int tcg2_replay_eventlog(struct tcg2_event_log *elog,
+				struct udevice *dev,
+				struct tpml_digest_values *digest_list,
+				u32 log_position)
+{
+	const u32 offset = offsetof(struct tcg_pcr_event2, digests) +
+		offsetof(struct tpml_digest_values, digests);
+	u32 event_size;
+	u32 count;
+	u16 algo;
+	u32 pcr;
+	u32 pos;
+	u16 len;
+	u8 *log;
+	int rc;
+	u32 i;
+
+	while (log_position + offset < elog->log_size) {
+		log = elog->log + log_position;
+
+		pos = offsetof(struct tcg_pcr_event2, pcr_index);
+		pcr = get_unaligned_le32(log + pos);
+		pos = offsetof(struct tcg_pcr_event2, event_type);
+		if (!get_unaligned_le32(log + pos))
+			return 0;
+
+		pos = offsetof(struct tcg_pcr_event2, digests) +
+			offsetof(struct tpml_digest_values, count);
+		count = get_unaligned_le32(log + pos);
+		if (count > ARRAY_SIZE(tpm2_supported_algorithms) ||
+		    (digest_list->count && digest_list->count != count))
+			return 0;
+
+		pos = offsetof(struct tcg_pcr_event2, digests) +
+			offsetof(struct tpml_digest_values, digests);
+		for (i = 0; i < count; ++i) {
+			pos += offsetof(struct tpmt_ha, hash_alg);
+			if (log_position + pos + sizeof(u16) >= elog->log_size)
+				return 0;
+
+			algo = get_unaligned_le16(log + pos);
+			pos += offsetof(struct tpmt_ha, digest);
+			switch (algo) {
+			case TPM2_ALG_SHA1:
+			case TPM2_ALG_SHA256:
+			case TPM2_ALG_SHA384:
+			case TPM2_ALG_SHA512:
+				len = tpm2_algorithm_to_len(algo);
+				break;
+			default:
+				return 0;
+			}
+
+			if (digest_list->count) {
+				if (algo != digest_list->digests[i].hash_alg ||
+				    log_position + pos + len >= elog->log_size)
+					return 0;
+
+				memcpy(digest_list->digests[i].digest.sha512,
+				       log + pos, len);
+			}
+
+			pos += len;
+		}
+
+		if (log_position + pos + sizeof(u32) >= elog->log_size)
+			return 0;
+
+		event_size = get_unaligned_le32(log + pos);
+		pos += event_size + sizeof(u32);
+		if (log_position + pos > elog->log_size)
+			return 0;
+
+		if (digest_list->count) {
+			rc = tcg2_pcr_extend(dev, pcr, digest_list);
+			if (rc)
+				return rc;
+		}
+
+		log_position += pos;
+	}
+
+	elog->log_position = log_position;
+	elog->found = true;
+	return 0;
+}
+
+static int tcg2_log_parse(struct udevice *dev, struct tcg2_event_log *elog)
+{
+	struct tpml_digest_values digest_list;
+	struct tcg_efi_spec_id_event *event;
+	struct tcg_pcr_event *log;
+	u32 log_active;
+	u32 calc_size;
+	u32 active;
+	u32 count;
+	u32 evsz;
+	u32 mask;
+	u16 algo;
+	u16 len;
+	int rc;
+	u32 i;
+	u16 j;
+
+	if (elog->log_size <= offsetof(struct tcg_pcr_event, event))
+		return 0;
+
+	log = (struct tcg_pcr_event *)elog->log;
+	if (get_unaligned_le32(&log->pcr_index) != 0 ||
+	    get_unaligned_le32(&log->event_type) != EV_NO_ACTION)
+		return 0;
+
+	for (i = 0; i < sizeof(log->digest); i++) {
+		if (log->digest[i])
+			return 0;
+	}
+
+	evsz = get_unaligned_le32(&log->event_size);
+	if (evsz < offsetof(struct tcg_efi_spec_id_event, digest_sizes) ||
+	    evsz + offsetof(struct tcg_pcr_event, event) > elog->log_size)
+		return 0;
+
+	event = (struct tcg_efi_spec_id_event *)log->event;
+	if (memcmp(event->signature, TCG_EFI_SPEC_ID_EVENT_SIGNATURE_03,
+		   sizeof(TCG_EFI_SPEC_ID_EVENT_SIGNATURE_03)))
+		return 0;
+
+	if (event->spec_version_minor != TCG_EFI_SPEC_ID_EVENT_SPEC_VERSION_MINOR_TPM2 ||
+	    event->spec_version_major != TCG_EFI_SPEC_ID_EVENT_SPEC_VERSION_MAJOR_TPM2)
+		return 0;
+
+	count = get_unaligned_le32(&event->number_of_algorithms);
+	if (count > ARRAY_SIZE(tpm2_supported_algorithms))
+		return 0;
+
+	calc_size = offsetof(struct tcg_efi_spec_id_event, digest_sizes) +
+		(sizeof(struct tcg_efi_spec_id_event_algorithm_size) * count) +
+		1;
+	if (evsz != calc_size)
+		return 0;
+
+	rc = tcg2_get_active_pcr_banks(dev, &active);
+	if (rc)
+		return rc;
+
+	digest_list.count = 0;
+	log_active = 0;
+
+	for (i = 0; i < count; ++i) {
+		algo = get_unaligned_le16(&event->digest_sizes[i].algorithm_id);
+		mask = tpm2_algorithm_to_mask(algo);
+
+		if (!(active & mask))
+			return 0;
+
+		switch (algo) {
+		case TPM2_ALG_SHA1:
+		case TPM2_ALG_SHA256:
+		case TPM2_ALG_SHA384:
+		case TPM2_ALG_SHA512:
+			len = get_unaligned_le16(&event->digest_sizes[i].digest_size);
+			if (tpm2_algorithm_to_len(algo) != len)
+				return 0;
+			digest_list.digests[digest_list.count++].hash_alg = algo;
+			break;
+		default:
+			return 0;
+		}
+
+		log_active |= mask;
+	}
+
+	/* Ensure the previous firmware extended all the PCRs. */
+	if (log_active != active)
+		return 0;
+
+	/* Read PCR0 to check if previous firmware extended the PCRs or not. */
+	rc = tcg2_pcr_read(dev, 0, &digest_list);
+	if (rc)
+		return rc;
+
+	for (i = 0; i < digest_list.count; ++i) {
+		len = tpm2_algorithm_to_len(digest_list.digests[i].hash_alg);
+		for (j = 0; j < len; ++j) {
+			if (digest_list.digests[i].digest.sha512[j])
+				break;
+		}
+
+		/* PCR is non-zero; it has been extended, so skip extending. */
+		if (j != len) {
+			digest_list.count = 0;
+			break;
+		}
+	}
+
+	return tcg2_replay_eventlog(elog, dev, &digest_list,
+				    offsetof(struct tcg_pcr_event, event) +
+				    evsz);
+}
+
+int tcg2_pcr_extend(struct udevice *dev, u32 pcr_index,
+		    struct tpml_digest_values *digest_list)
+{
+	u32 rc;
+	u32 i;
+
+	for (i = 0; i < digest_list->count; i++) {
+		u32 alg = digest_list->digests[i].hash_alg;
+
+		rc = tpm2_pcr_extend(dev, pcr_index, alg,
+				     (u8 *)&digest_list->digests[i].digest,
+				     tpm2_algorithm_to_len(alg));
+		if (rc) {
+			printf("%s: error pcr:%u alg:%08x\n", __func__,
+			       pcr_index, alg);
+			return rc;
+		}
+	}
+
+	return 0;
+}
+
+int tcg2_pcr_read(struct udevice *dev, u32 pcr_index,
+		  struct tpml_digest_values *digest_list)
+{
+	struct tpm_chip_priv *priv;
+	u32 rc;
+	u32 i;
+
+	priv = dev_get_uclass_priv(dev);
+	if (!priv)
+		return -ENODEV;
+
+	for (i = 0; i < digest_list->count; i++) {
+		u32 alg = digest_list->digests[i].hash_alg;
+		u8 *digest = (u8 *)&digest_list->digests[i].digest;
+
+		rc = tpm2_pcr_read(dev, pcr_index, priv->pcr_select_min, alg,
+				   digest, tpm2_algorithm_to_len(alg), NULL);
+		if (rc) {
+			printf("%s: error pcr:%u alg:%08x\n", __func__,
+			       pcr_index, alg);
+			return rc;
+		}
+	}
+
+	return 0;
+}
+
+int tcg2_measure_data(struct udevice *dev, struct tcg2_event_log *elog,
+		      u32 pcr_index, u32 size, const u8 *data, u32 event_type,
+		      u32 event_size, const u8 *event)
+{
+	struct tpml_digest_values digest_list;
+	int rc;
+
+	if (data)
+		rc = tcg2_create_digest(dev, data, size, &digest_list);
+	else
+		rc = tcg2_create_digest(dev, event, event_size, &digest_list);
+	if (rc)
+		return rc;
+
+	rc = tcg2_pcr_extend(dev, pcr_index, &digest_list);
+	if (rc)
+		return rc;
+
+	return tcg2_log_append_check(elog, pcr_index, event_type, &digest_list,
+				     event_size, event);
+}
+
+int tcg2_log_prepare_buffer(struct udevice *dev, struct tcg2_event_log *elog,
+			    bool ignore_existing_log)
+{
+	struct tcg2_event_log log;
+	int rc;
+
+	elog->log_position = 0;
+	elog->found = false;
+
+	rc = tcg2_platform_get_log(dev, (void **)&log.log, &log.log_size);
+	if (!rc) {
+		log.log_position = 0;
+		log.found = false;
+
+		if (!ignore_existing_log) {
+			rc = tcg2_log_parse(dev, &log);
+			if (rc)
+				return rc;
+		}
+
+		if (elog->log_size) {
+			if (log.found) {
+				if (elog->log_size < log.log_position)
+					return -ENOSPC;
+
+				/*
+				 * Copy the discovered log into the user buffer
+				 * if there's enough space.
+				 */
+				memcpy(elog->log, log.log, log.log_position);
+			}
+
+			unmap_physmem(log.log, MAP_NOCACHE);
+		} else {
+			elog->log = log.log;
+			elog->log_size = log.log_size;
+		}
+
+		elog->log_position = log.log_position;
+		elog->found = log.found;
+	}
+
+	/*
+	 * Initialize the log buffer if no log was discovered and the buffer is
+	 * valid. User's can pass in their own buffer as a fallback if no
+	 * memory region is found.
+	 */
+	if (!elog->found && elog->log_size)
+		rc = tcg2_log_init(dev, elog);
+
+	return rc;
+}
+
+int tcg2_measurement_init(struct udevice **dev, struct tcg2_event_log *elog,
+			  bool ignore_existing_log)
+{
+	int rc;
+
+	rc = tcg2_platform_get_tpm2(dev);
+	if (rc)
+		return rc;
+
+	rc = tpm_auto_start(*dev);
+	if (rc)
+		return rc;
+
+	rc = tcg2_log_prepare_buffer(*dev, elog, ignore_existing_log);
+	if (rc) {
+		tcg2_measurement_term(*dev, elog, true);
+		return rc;
+	}
+
+	rc = tcg2_measure_event(*dev, elog, 0, EV_S_CRTM_VERSION,
+				strlen(version_string) + 1,
+				(u8 *)version_string);
+	if (rc) {
+		tcg2_measurement_term(*dev, elog, true);
+		return rc;
+	}
+
+	return 0;
+}
+
+void tcg2_measurement_term(struct udevice *dev, struct tcg2_event_log *elog,
+			   bool error)
+{
+	u32 event = error ? 0x1 : 0xffffffff;
+	int i;
+
+	for (i = 0; i < 8; ++i)
+		tcg2_measure_event(dev, elog, i, EV_SEPARATOR, sizeof(event),
+				   (const u8 *)&event);
+
+	if (elog->log)
+		unmap_physmem(elog->log, MAP_NOCACHE);
+}
+
+__weak int tcg2_platform_get_log(struct udevice *dev, void **addr, u32 *size)
+{
+	const __be32 *addr_prop;
+	const __be32 *size_prop;
+	int asize;
+	int ssize;
+
+	*addr = NULL;
+	*size = 0;
+
+	addr_prop = dev_read_prop(dev, "tpm_event_log_addr", &asize);
+	if (!addr_prop)
+		addr_prop = dev_read_prop(dev, "linux,sml-base", &asize);
+
+	size_prop = dev_read_prop(dev, "tpm_event_log_size", &ssize);
+	if (!size_prop)
+		size_prop = dev_read_prop(dev, "linux,sml-size", &ssize);
+
+	if (addr_prop && size_prop) {
+		u64 a = of_read_number(addr_prop, asize / sizeof(__be32));
+		u64 s = of_read_number(size_prop, ssize / sizeof(__be32));
+
+		*addr = map_physmem(a, s, MAP_NOCACHE);
+		*size = (u32)s;
+	} else {
+		struct ofnode_phandle_args args;
+		phys_addr_t a;
+		fdt_size_t s;
+
+		if (dev_read_phandle_with_args(dev, "memory-region", NULL, 0,
+					       0, &args))
+			return -ENODEV;
+
+		a = ofnode_get_addr_size(args.node, "reg", &s);
+		if (a == FDT_ADDR_T_NONE)
+			return -ENOMEM;
+
+		*addr = map_physmem(a, s, MAP_NOCACHE);
+		*size = (u32)s;
+	}
+
+	return 0;
+}
+
+__weak int tcg2_platform_get_tpm2(struct udevice **dev)
+{
+	for_each_tpm_device(*dev) {
+		if (tpm_get_version(*dev) == TPM_V2)
+			return 0;
+	}
+
+	return -ENODEV;
+}
+
+__weak void tcg2_platform_startup_error(struct udevice *dev, int rc) {}
+
 u32 tpm2_startup(struct udevice *dev, enum tpm2_startup_types mode)
 {
 	const u8 command_v2[12] = {
@@ -359,6 +1048,131 @@ u32 tpm2_get_capability(struct udevice *dev, u32 capability, u32 property,
 	return 0;
 }
 
+static int tpm2_get_num_pcr(struct udevice *dev, u32 *num_pcr)
+{
+	u8 response[(sizeof(struct tpms_capability_data) -
+		offsetof(struct tpms_capability_data, data))];
+	u32 properties_offset =
+		offsetof(struct tpml_tagged_tpm_property, tpm_property) +
+		offsetof(struct tpms_tagged_property, value);
+	u32 ret;
+
+	memset(response, 0, sizeof(response));
+	ret = tpm2_get_capability(dev, TPM2_CAP_TPM_PROPERTIES,
+				  TPM2_PT_PCR_COUNT, response, 1);
+	if (ret)
+		return ret;
+
+	*num_pcr = get_unaligned_be32(response + properties_offset);
+	if (*num_pcr > TPM2_MAX_PCRS) {
+		printf("%s: too many pcrs: %u\n", __func__, *num_pcr);
+		return -E2BIG;
+	}
+
+	return 0;
+}
+
+static bool tpm2_is_active_pcr(struct tpms_pcr_selection *selection)
+{
+	int i;
+
+	/*
+	 * check the pcr_select. If at least one of the PCRs supports the
+	 * algorithm add it on the active ones
+	 */
+	for (i = 0; i < selection->size_of_select; i++) {
+		if (selection->pcr_select[i])
+			return true;
+	}
+
+	return false;
+}
+
+int tpm2_get_pcr_info(struct udevice *dev, u32 *supported_pcr, u32 *active_pcr,
+		      u32 *pcr_banks)
+{
+	u8 response[(sizeof(struct tpms_capability_data) -
+		offsetof(struct tpms_capability_data, data))];
+	struct tpml_pcr_selection pcrs;
+	u32 num_pcr;
+	size_t i;
+	u32 ret;
+
+	*supported_pcr = 0;
+	*active_pcr = 0;
+	*pcr_banks = 0;
+	memset(response, 0, sizeof(response));
+	ret = tpm2_get_capability(dev, TPM2_CAP_PCRS, 0, response, 1);
+	if (ret)
+		return ret;
+
+	pcrs.count = get_unaligned_be32(response);
+	/*
+	 * We only support 5 algorithms for now so check against that
+	 * instead of TPM2_NUM_PCR_BANKS
+	 */
+	if (pcrs.count > ARRAY_SIZE(tpm2_supported_algorithms) ||
+	    pcrs.count < 1) {
+		printf("%s: too many pcrs: %u\n", __func__, pcrs.count);
+		return -EMSGSIZE;
+	}
+
+	ret = tpm2_get_num_pcr(dev, &num_pcr);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < pcrs.count; i++) {
+		/*
+		 * Definition of TPMS_PCR_SELECTION Structure
+		 * hash: u16
+		 * size_of_select: u8
+		 * pcr_select: u8 array
+		 *
+		 * The offsets depend on the number of the device PCRs
+		 * so we have to calculate them based on that
+		 */
+		u32 hash_offset = offsetof(struct tpml_pcr_selection, selection) +
+			i * offsetof(struct tpms_pcr_selection, pcr_select) +
+			i * ((num_pcr + 7) / 8);
+		u32 size_select_offset =
+			hash_offset + offsetof(struct tpms_pcr_selection,
+					       size_of_select);
+		u32 pcr_select_offset =
+			hash_offset + offsetof(struct tpms_pcr_selection,
+					       pcr_select);
+
+		pcrs.selection[i].hash =
+			get_unaligned_be16(response + hash_offset);
+		pcrs.selection[i].size_of_select =
+			__get_unaligned_be(response + size_select_offset);
+		if (pcrs.selection[i].size_of_select > TPM2_PCR_SELECT_MAX) {
+			printf("%s: pcrs selection too large: %u\n", __func__,
+			       pcrs.selection[i].size_of_select);
+			return -ENOBUFS;
+		}
+		/* copy the array of pcr_select */
+		memcpy(pcrs.selection[i].pcr_select, response + pcr_select_offset,
+		       pcrs.selection[i].size_of_select);
+	}
+
+	for (i = 0; i < pcrs.count; i++) {
+		u32 hash_mask = tpm2_algorithm_to_mask(pcrs.selection[i].hash);
+
+		if (hash_mask) {
+			*supported_pcr |= hash_mask;
+			if (tpm2_is_active_pcr(&pcrs.selection[i]))
+				*active_pcr |= hash_mask;
+		} else {
+			printf("%s: unknown algorithm %x\n", __func__,
+			       pcrs.selection[i].hash);
+		}
+	}
+
+	*pcr_banks = pcrs.count;
+
+	return 0;
+}
+
 u32 tpm2_dam_reset(struct udevice *dev, const char *pw, const ssize_t pw_sz)
 {
 	u8 command_v2[COMMAND_BUFFER_SIZE] = {