[PATCH 05/11] tpm: add flag in hash_algo_list and API to check if algorithm is supported

[Raymond Mao]

Add a bool var into hash_algo_list to indicate whether the algorithm
is supported or not and move the IS_ENABLED to only cover this var.
So that we can have the name, hash, mask and size no matter the
digest kconfigs are enabled or not.

In before, tpm2_algorithm_to_len() and tcg2_algorithm_to_mask() are used to
identify an unsupported algorithm when they return 0.
It is not the case now when hash_algo_list always provides algorithm size
and mask, thus a new API is introduced to check if an algorithm is
supported by U-Boot.

Suggested-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
---
 include/tpm-v2.h | 37 +++++++++++++++++++++++++++++--------
 lib/tpm-v2.c     | 14 +++++++++++++-
 lib/tpm_tcg2.c   | 17 +++++++++--------
 3 files changed, 51 insertions(+), 17 deletions(-)

diff --git a/include/tpm-v2.h b/include/tpm-v2.h
index 87b2c614ad..c49eadda26 100644
--- a/include/tpm-v2.h
+++ b/include/tpm-v2.h
@@ -268,6 +268,7 @@ struct digest_info {
 	u16 hash_alg;
 	u32 hash_mask;
 	u16 hash_len;
+	bool supported;
 };
 
 /* Algorithm Registry */
@@ -278,38 +279,50 @@ struct digest_info {
 #define TCG2_BOOT_HASH_ALG_SM3_256 0x00000010
 
 static const struct digest_info hash_algo_list[] = {
-#if IS_ENABLED(CONFIG_SHA1)
 	{
 		"sha1",
 		TPM2_ALG_SHA1,
 		TCG2_BOOT_HASH_ALG_SHA1,
 		TPM2_SHA1_DIGEST_SIZE,
-	},
+#if IS_ENABLED(CONFIG_SHA1)
+		true,
+#else
+		false,
 #endif
-#if IS_ENABLED(CONFIG_SHA256)
+	},
 	{
 		"sha256",
 		TPM2_ALG_SHA256,
 		TCG2_BOOT_HASH_ALG_SHA256,
 		TPM2_SHA256_DIGEST_SIZE,
-	},
+#if IS_ENABLED(CONFIG_SHA256)
+		true,
+#else
+		false,
 #endif
-#if IS_ENABLED(CONFIG_SHA384)
+	},
 	{
 		"sha384",
 		TPM2_ALG_SHA384,
 		TCG2_BOOT_HASH_ALG_SHA384,
 		TPM2_SHA384_DIGEST_SIZE,
-	},
+#if IS_ENABLED(CONFIG_SHA384)
+		true,
+#else
+		false,
 #endif
-#if IS_ENABLED(CONFIG_SHA512)
+	},
 	{
 		"sha512",
 		TPM2_ALG_SHA512,
 		TCG2_BOOT_HASH_ALG_SHA512,
 		TPM2_SHA512_DIGEST_SIZE,
-	},
+#if IS_ENABLED(CONFIG_SHA512)
+		true,
+#else
+		false,
 #endif
+	},
 };
 
 /* NV index attributes */
@@ -704,6 +717,14 @@ enum tpm2_algorithms tpm2_name_to_algorithm(const char *name);
  */
 const char *tpm2_algorithm_name(enum tpm2_algorithms);
 
+/**
+ * tpm2_algorithm_supported() -  Check if the algorithm supported by U-Boot
+ *
+ * @algorithm_id: algorithm defined in enum tpm2_algorithms
+ * Return: true if supported, otherwise false
+ */
+bool tpm2_algorithm_supported(enum tpm2_algorithms algo);
+
 /**
  * tpm2_algorithm_to_len() - Return an algorithm length for supported algorithm id
  *
diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
index 0edb0aa90c..96c164f2a5 100644
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -884,6 +884,18 @@ const char *tpm2_algorithm_name(enum tpm2_algorithms algo)
 	return "";
 }
 
+bool tpm2_algorithm_supported(enum tpm2_algorithms algo)
+{
+	size_t i;
+
+	for (i = 0; i < ARRAY_SIZE(hash_algo_list); ++i) {
+		if (hash_algo_list[i].hash_alg == algo)
+			return hash_algo_list[i].supported;
+	}
+
+	return false;
+}
+
 u16 tpm2_algorithm_to_len(enum tpm2_algorithms algo)
 {
 	size_t i;
@@ -908,7 +920,7 @@ bool tpm2_check_active_banks(struct udevice *dev)
 
 	for (i = 0; i < pcrs.count; i++) {
 		if (tpm2_is_active_bank(&pcrs.selection[i]) &&
-		    !tpm2_algorithm_to_len(pcrs.selection[i].hash))
+		    !tpm2_algorithm_supported(pcrs.selection[i].hash))
 			return false;
 	}
 
diff --git a/lib/tpm_tcg2.c b/lib/tpm_tcg2.c
index 16f41cbfd1..4682f7664f 100644
--- a/lib/tpm_tcg2.c
+++ b/lib/tpm_tcg2.c
@@ -37,16 +37,17 @@ int tcg2_get_pcr_info(struct udevice *dev, u32 *supported_bank, u32 *active_bank
 		return ret;
 
 	for (i = 0; i < pcrs.count; i++) {
-		u32 hash_mask = tcg2_algorithm_to_mask(pcrs.selection[i].hash);
+		struct tpms_pcr_selection *sel = &pcrs.selection[i];
+		u32 hash_mask = tcg2_algorithm_to_mask(sel->hash);
 
-		if (hash_mask) {
+		if (tpm2_algorithm_supported(sel->hash))
 			*supported_bank |= hash_mask;
-			if (tpm2_is_active_bank(&pcrs.selection[i]))
-				*active_bank |= hash_mask;
-		} else {
-			printf("%s: unknown algorithm %x\n", __func__,
-			       pcrs.selection[i].hash);
-		}
+		else
+			log_warning("%s: unknown algorithm %x\n", __func__,
+				    sel->hash);
+
+		if (tpm2_is_active_bank(sel))
+			*active_bank |= hash_mask;
 	}
 
 	*bank_num = pcrs.count;
-- 
2.25.1