tpm: Require a digest source when extending the PCR

This feature is used for measured boot, so we can add a log entry to the
TCPA with some information about where the digest comes from. It is not
currently supported in the TPM drivers, but add it to the API so that
code which expects it can signal its request.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

5 files changed, 18 insertions, 10 deletions

diff --git a/cmd/tpm-v1.c b/cmd/tpm-v1.c
index bf238a9f2e3..0efb079b0a9 100644
--- a/cmd/tpm-v1.c
+++ b/cmd/tpm-v1.c
@@ -131,7 +131,8 @@ static int do_tpm_extend(struct cmd_tbl *cmdtp, int flag, int argc,
 		return CMD_RET_FAILURE;
 	}
 
-	rc = tpm_pcr_extend(dev, index, in_digest, out_digest);
+	rc = tpm_pcr_extend(dev, index, in_digest, sizeof(in_digest),
+			    out_digest, "cmd");
 	if (!rc) {
 		puts("PCR value after execution of the command:\n");
 		print_byte_string(out_digest, sizeof(out_digest));
diff --git a/cmd/tpm_test.c b/cmd/tpm_test.c
index a3ccb12f53a..b35eae81dc3 100644
--- a/cmd/tpm_test.c
+++ b/cmd/tpm_test.c
@@ -91,7 +91,8 @@ static int test_early_extend(struct udevice *dev)
 	tpm_init(dev);
 	TPM_CHECK(tpm_startup(dev, TPM_ST_CLEAR));
 	TPM_CHECK(tpm_continue_self_test(dev));
-	TPM_CHECK(tpm_pcr_extend(dev, 1, value_in, value_out));
+	TPM_CHECK(tpm_pcr_extend(dev, 1, value_in, sizeof(value_in), value_out,
+				 "test"));
 	printf("done\n");
 	return 0;
 }
@@ -438,7 +439,7 @@ static int test_timing(struct udevice *dev)
 		   100);
 	TTPM_CHECK(tpm_nv_read_value(dev, INDEX0, (uint8_t *)&x, sizeof(x)),
 		   100);
-	TTPM_CHECK(tpm_pcr_extend(dev, 0, in, out), 200);
+	TTPM_CHECK(tpm_pcr_extend(dev, 0, in, sizeof(in), out, "test"), 200);
 	TTPM_CHECK(tpm_set_global_lock(dev), 50);
 	TTPM_CHECK(tpm_tsc_physical_presence(dev, PHYS_PRESENCE), 100);
 	printf("done\n");
diff --git a/include/tpm_api.h b/include/tpm_api.h
index 11aa14eb793..8979d9d6df7 100644
--- a/include/tpm_api.h
+++ b/include/tpm_api.h
@@ -81,14 +81,16 @@ u32 tpm_nv_write_value(struct udevice *dev, u32 index, const void *data,
  *
  * @param dev		TPM device
  * @param index		index of the PCR
- * @param in_digest	160-bit value representing the event to be
+ * @param in_digest	160/256-bit value representing the event to be
  *			recorded
- * @param out_digest	160-bit PCR value after execution of the
+ * @param size		size of digest in bytes
+ * @param out_digest	160/256-bit PCR value after execution of the
  *			command
+ * @param name		digest source, used for log output
  * Return: return code of the operation
  */
 u32 tpm_pcr_extend(struct udevice *dev, u32 index, const void *in_digest,
-		   void *out_digest);
+		   uint size, void *out_digest, const char *name);
 
 /**
  * Issue a TPM_PCRRead command.
diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
index 1bf627853af..6058f2e1e4f 100644
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -157,6 +157,8 @@ u32 tpm2_pcr_extend(struct udevice *dev, u32 index, u32 algorithm,
 	};
 	int ret;
 
+	if (!digest)
+		return -EINVAL;
 	/*
 	 * Fill the command structure starting from the first buffer:
 	 *     - the digest
diff --git a/lib/tpm_api.c b/lib/tpm_api.c
index 032f383ca04..7e8df8795ef 100644
--- a/lib/tpm_api.c
+++ b/lib/tpm_api.c
@@ -140,15 +140,17 @@ u32 tpm_write_lock(struct udevice *dev, u32 index)
 }
 
 u32 tpm_pcr_extend(struct udevice *dev, u32 index, const void *in_digest,
-		   void *out_digest)
+		   uint size, void *out_digest, const char *name)
 {
-	if (tpm_is_v1(dev))
+	if (tpm_is_v1(dev)) {
 		return tpm1_extend(dev, index, in_digest, out_digest);
-	else if (tpm_is_v2(dev))
+	} else if (tpm_is_v2(dev)) {
 		return tpm2_pcr_extend(dev, index, TPM2_ALG_SHA256, in_digest,
 				       TPM2_DIGEST_LEN);
-	else
+		/* @name is ignored as we do not support the TPM log here */
+	} else {
 		return -ENOSYS;
+	}
 }
 
 u32 tpm_pcr_read(struct udevice *dev, u32 index, void *data, size_t count)