Merge tag 'tpm-master-28012025' of https://source.denx.de/u-boot/custodians/u-boot-tpm

CI: https://source.denx.de/u-boot/custodians/u-boot-tpm/-/pipelines/24375

We have use cases where a previous stage boot loader doesn't have any
TPM drivers. Instead of extending the hardware PCRs it produces an
EventLog that U-Boot later replays on the hardware.

The only real example we have is TF-A, which produces the EventLog using
hashing algorithms created at compile time. This creates a problem to the
TPM since measurements need to extend all active PCR banks. Up to now
we were exiting refusing the extend measurements.

TPMs can be instructed to change their active PCR banks, as long as the
device resets immediately after a reconfiguration. This PR is adding
that functionality. U-Boot can now scan the currently active TPM PCR
banks, the ones it was compiled to support and the ones present in an
EventLog. It the reconfigures the TPM on the fly with the correct algorithms.

1 files changed, 254 insertions, 5 deletions

diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
index bc750b7ca19..9ca7933c094 100644
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -44,12 +44,134 @@ static int tpm2_update_active_banks(struct udevice *dev)
 	return 0;
 }
 
-u32 tpm2_startup(struct udevice *dev, enum tpm2_startup_types mode)
+static void tpm2_print_selected_algorithm_name(u32 selected)
 {
+	size_t i;
+	const char *str;
+
+	for (i = 0; i < ARRAY_SIZE(hash_algo_list); i++) {
+		const struct digest_info *algo = &hash_algo_list[i];
+
+		if (!(selected & algo->hash_mask))
+			continue;
+
+		str = tpm2_algorithm_name(algo->hash_alg);
+		if (str)
+			log_info("%s\n", str);
+	}
+}
+
+int tpm2_scan_masks(struct udevice *dev, u32 log_active, u32 *mask)
+{
+	struct tpml_pcr_selection pcrs;
+	u32 active = 0;
+	u32 supported = 0;
+	int rc, i;
+
+	*mask = 0;
+
+	rc = tpm2_get_pcr_info(dev, &pcrs);
+	if (rc)
+		return rc;
+
+	for (i = 0; i < pcrs.count; i++) {
+		struct tpms_pcr_selection *sel = &pcrs.selection[i];
+		size_t j;
+		u32 hash_mask = 0;
+
+		for (j = 0; j < ARRAY_SIZE(hash_algo_list); j++) {
+			if (hash_algo_list[j].hash_alg == sel->hash)
+				hash_mask = hash_algo_list[j].hash_mask;
+		}
+
+		if (tpm2_algorithm_supported(sel->hash))
+			supported |= hash_mask;
+
+		if (tpm2_is_active_bank(sel))
+			active |= hash_mask;
+	}
+
+	/* All eventlog algorithm(s) must be supported */
+	if (log_active & ~supported) {
+		log_err("EventLog contains U-Boot unsupported algorithm(s)\n");
+		tpm2_print_selected_algorithm_name(log_active & ~supported);
+		rc = -1;
+	}
+	if (log_active && active & ~log_active) {
+		log_warning("TPM active algorithm(s) not exist in eventlog\n");
+		tpm2_print_selected_algorithm_name(active & ~log_active);
+		*mask = log_active;
+	}
+
+	/* Any active algorithm(s) which are not supported must be removed */
+	if (active & ~supported) {
+		log_warning("TPM active algorithm(s) unsupported by u-boot\n");
+		tpm2_print_selected_algorithm_name(active & ~supported);
+		if (*mask)
+			*mask = active & supported & *mask;
+		else
+			*mask = active & supported;
+	}
+
+	return rc;
+}
+
+static int tpm2_pcr_allocate(struct udevice *dev, u32 algo_mask)
+{
+	struct tpml_pcr_selection pcr = { 0 };
+	u32 pcr_len = 0;
+	int rc;
+
+	rc = tpm2_get_pcr_info(dev, &pcr);
+	if (rc)
+		return rc;
+
+	rc = tpm2_pcr_config_algo(dev, algo_mask, &pcr, &pcr_len);
+	if (rc)
+		return rc;
+
+	/* Assume no password */
+	rc = tpm2_send_pcr_allocate(dev, NULL, 0, &pcr, pcr_len);
+	if (rc)
+		return rc;
+
+	/* Send TPM2_Shutdown, assume mode = TPM2_SU_CLEAR */
+	return tpm2_startup(dev, false, TPM2_SU_CLEAR);
+}
+
+int tpm2_activate_banks(struct udevice *dev, u32 log_active)
+{
+	u32 algo_mask = 0;
+	int rc;
+
+	rc = tpm2_scan_masks(dev, log_active, &algo_mask);
+	if (rc)
+		return rc;
+
+	if (algo_mask) {
+		if (!IS_ENABLED(CONFIG_TPM_PCR_ALLOCATE))
+			return -1;
+
+		rc = tpm2_pcr_allocate(dev, algo_mask);
+		if (rc)
+			return rc;
+
+		log_info("PCR allocate done, shutdown TPM and reboot\n");
+		do_reset(NULL, 0, 0, NULL);
+		log_err("reset does not work!\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+u32 tpm2_startup(struct udevice *dev, bool bon, enum tpm2_startup_types mode)
+{
+	int op = bon ? TPM2_CC_STARTUP : TPM2_CC_SHUTDOWN;
 	const u8 command_v2[12] = {
 		tpm_u16(TPM2_ST_NO_SESSIONS),
 		tpm_u32(12),
-		tpm_u32(TPM2_CC_STARTUP),
+		tpm_u32(op),
 		tpm_u16(mode),
 	};
 	int ret;
@@ -59,7 +181,7 @@ u32 tpm2_startup(struct udevice *dev, enum tpm2_startup_types mode)
 	 * but will return RC_INITIALIZE otherwise.
 	 */
 	ret = tpm_sendrecv_command(dev, command_v2, NULL, NULL);
-	if (ret && ret != TPM2_RC_INITIALIZE)
+	if ((ret && ret != TPM2_RC_INITIALIZE) || !bon)
 		return ret;
 
 	return tpm2_update_active_banks(dev);
@@ -84,7 +206,7 @@ u32 tpm2_auto_start(struct udevice *dev)
 	rc = tpm2_self_test(dev, TPMI_YES);
 
 	if (rc == TPM2_RC_INITIALIZE) {
-		rc = tpm2_startup(dev, TPM2_SU_CLEAR);
+		rc = tpm2_startup(dev, true, TPM2_SU_CLEAR);
 		if (rc)
 			return rc;
 
@@ -222,7 +344,10 @@ u32 tpm2_pcr_extend(struct udevice *dev, u32 index, u32 algorithm,
 
 	if (!tpm2_check_active_banks(dev)) {
 		log_err("Cannot extend PCRs if all the TPM enabled algorithms are not supported\n");
-		return -EINVAL;
+
+		ret = tpm2_pcr_allocate(dev, 0);
+		if (ret)
+			return -EINVAL;
 	}
 	/*
 	 * Fill the command structure starting from the first buffer:
@@ -399,6 +524,130 @@ u32 tpm2_get_capability(struct udevice *dev, u32 capability, u32 property,
 	return 0;
 }
 
+u32 tpm2_pcr_config_algo(struct udevice *dev, u32 algo_mask,
+			 struct tpml_pcr_selection *pcr, u32 *pcr_len)
+{
+	int i;
+
+	if (pcr->count > TPM2_NUM_PCR_BANKS)
+		return TPM_LIB_ERROR;
+
+	*pcr_len = sizeof(pcr->count);
+
+	for (i = 0; i < pcr->count; i++) {
+		struct tpms_pcr_selection *sel = &pcr->selection[i];
+		u8 pad = 0;
+		int j;
+
+		if (sel->size_of_select > TPM2_PCR_SELECT_MAX)
+			return TPM_LIB_ERROR;
+
+		/*
+		 * Found the algorithm (bank) that matches, and enable all PCR
+		 * bits.
+		 * TODO: only select the bits needed
+		 */
+		for (j = 0; j < ARRAY_SIZE(hash_algo_list); j++) {
+			if (hash_algo_list[j].hash_alg != sel->hash)
+				continue;
+
+			if (algo_mask & hash_algo_list[j].hash_mask)
+				pad = 0xff;
+		}
+
+		for (j = 0; j < sel->size_of_select; j++)
+			sel->pcr_select[j] = pad;
+
+		log_info("set bank[%d] %s %s\n", i,
+			 tpm2_algorithm_name(sel->hash),
+			 tpm2_is_active_bank(sel) ? "on" : "off");
+
+		*pcr_len += sizeof(sel->hash) + sizeof(sel->size_of_select) +
+			    sel->size_of_select;
+	}
+
+	return 0;
+}
+
+u32 tpm2_send_pcr_allocate(struct udevice *dev, const char *pw,
+			   const ssize_t pw_sz, struct tpml_pcr_selection *pcr,
+			   u32 pcr_len)
+{
+	/* Length of the message header, up to start of password */
+	uint offset = 27;
+	u8 command_v2[COMMAND_BUFFER_SIZE] = {
+		tpm_u16(TPM2_ST_SESSIONS),   /* TAG */
+		tpm_u32(offset + pw_sz + pcr_len), /* Length */
+		tpm_u32(TPM2_CC_PCR_ALLOCATE),  /* Command code */
+
+		/* handles 4 bytes */
+		tpm_u32(TPM2_RH_PLATFORM),	/* Primary platform seed */
+
+		/* AUTH_SESSION */
+		tpm_u32(9 + pw_sz),		/* Authorization size */
+		tpm_u32(TPM2_RS_PW),		/* Session handle */
+		tpm_u16(0),			/* Size of <nonce> */
+						/* <nonce> (if any) */
+		0,				/* Attributes: Cont/Excl/Rst */
+		tpm_u16(pw_sz),			/* Size of <hmac/password> */
+		/* STRING(pw)			   <hmac/password> (if any) */
+
+		/* TPML_PCR_SELECTION */
+	};
+	u8 response[COMMAND_BUFFER_SIZE];
+	size_t response_len = COMMAND_BUFFER_SIZE;
+	u32 i;
+	int ret;
+
+	/*
+	 * Fill the command structure starting from the first buffer:
+	 * the password (if any)
+	 */
+	if (pack_byte_string(command_v2, sizeof(command_v2), "s", offset, pw,
+			     pw_sz))
+		return TPM_LIB_ERROR;
+
+	offset += pw_sz;
+
+	/* Pack the count field */
+	if (pack_byte_string(command_v2, sizeof(command_v2), "d", offset, pcr->count))
+		return TPM_LIB_ERROR;
+
+	offset += sizeof(pcr->count);
+
+	/* Pack each tpms_pcr_selection */
+	for (i = 0; i < pcr->count; i++) {
+		struct tpms_pcr_selection *sel = &pcr->selection[i];
+
+		/* Pack hash (16-bit) */
+		if (pack_byte_string(command_v2, sizeof(command_v2), "w", offset,
+				     sel->hash))
+			return TPM_LIB_ERROR;
+
+		offset += sizeof(sel->hash);
+
+		/* Pack size_of_select (8-bit) */
+		if (pack_byte_string(command_v2, sizeof(command_v2), "b", offset,
+				     sel->size_of_select))
+			return TPM_LIB_ERROR;
+
+		offset += sizeof(sel->size_of_select);
+
+		/* Pack pcr_select array */
+		if (pack_byte_string(command_v2, sizeof(command_v2), "s", offset,
+				     sel->pcr_select, sel->size_of_select))
+			return TPM_LIB_ERROR;
+
+		offset += sel->size_of_select;
+	}
+
+	ret = tpm_sendrecv_command(dev, command_v2, response, &response_len);
+	if (!ret)
+		tpm_init(dev);
+
+	return ret;
+}
+
 static int tpm2_get_num_pcr(struct udevice *dev, u32 *num_pcr)
 {
 	u8 response[(sizeof(struct tpms_capability_data) -