tpm: Rename TPM2_OA_TMPL to TPM2_OA_NULL_KEY and make it local

Rename and document TPM2_OA_TMPL, as originally requested in the patch
set review, but left unaddressed without any appropriate reasoning. The
new name is TPM2_OA_NULL_KEY, has a documentation and is local only to
tpm2-sessions.c.

Link: https://lore.kernel.org/linux-integrity/ddbeb8111f48a8ddb0b8fca248dff6cc9d7079b2.camel@HansenPartnership.com/
Link: https://lore.kernel.org/linux-integrity/CZCKTWU6ZCC9.2UTEQPEVICYHL@suppilovahvero/Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

drivers/char/tpm/tpm2-sessions.c

@@ -80,6 +80,9 @@
 /* maximum number of names the TPM must remember for authorization */
 #define AUTH_MAX_NAMES	3
 
+#define AES_KEY_BYTES	AES_KEYSIZE_128
+#define AES_KEY_BITS	(AES_KEY_BYTES*8)
+
 static int tpm2_create_primary(struct tpm_chip *chip, u32 hierarchy,
 			       u32 *handle, u8 *name);
 
@@ -954,6 +957,20 @@ int tpm2_start_auth_session(struct tpm_chip *chip)
 }
 EXPORT_SYMBOL(tpm2_start_auth_session);
 
+/*
+ * A mask containing the object attributes for the kernel held null primary key
+ * used in HMAC encryption. For more information on specific attributes look up
+ * to "8.3 TPMA_OBJECT (Object Attributes)".
+ */
+#define TPM2_OA_NULL_KEY ( \
+	TPM2_OA_NO_DA | \
+	TPM2_OA_FIXED_TPM | \
+	TPM2_OA_FIXED_PARENT | \
+	TPM2_OA_SENSITIVE_DATA_ORIGIN |	\
+	TPM2_OA_USER_WITH_AUTH | \
+	TPM2_OA_DECRYPT | \
+	TPM2_OA_RESTRICTED)
+
 /**
  * tpm2_parse_create_primary() - parse the data returned from TPM_CC_CREATE_PRIMARY
  *
@@ -1018,7 +1035,7 @@ static int tpm2_parse_create_primary(struct tpm_chip *chip, struct tpm_buf *buf,
 	val = tpm_buf_read_u32(buf, &offset_t);
 
 	/* object properties */
-	if (val != TPM2_OA_TMPL)
+	if (val != TPM2_OA_NULL_KEY)
 		return -EINVAL;
 
 	/* auth policy (empty) */
@@ -1178,7 +1195,7 @@ static int tpm2_create_primary(struct tpm_chip *chip, u32 hierarchy,
 	tpm_buf_append_u16(&template, TPM_ALG_SHA256);
 
 	/* object properties */
-	tpm_buf_append_u32(&template, TPM2_OA_TMPL);
+	tpm_buf_append_u32(&template, TPM2_OA_NULL_KEY);
 
 	/* sauth policy (empty) */
 	tpm_buf_append_u16(&template, 0);

include/linux/tpm.h

@@ -394,21 +394,6 @@ enum tpm2_object_attributes {
 	TPM2_OA_SIGN			= BIT(18),
 };
 
-/*
- * definitions for the canonical template.  These are mandated
- * by the TCG key template documents
- */
-
-#define AES_KEY_BYTES	AES_KEYSIZE_128
-#define AES_KEY_BITS	(AES_KEY_BYTES*8)
-#define TPM2_OA_TMPL	(TPM2_OA_NO_DA |			\
-			 TPM2_OA_FIXED_TPM |			\
-			 TPM2_OA_FIXED_PARENT |			\
-			 TPM2_OA_SENSITIVE_DATA_ORIGIN |	\
-			 TPM2_OA_USER_WITH_AUTH |		\
-			 TPM2_OA_DECRYPT |			\
-			 TPM2_OA_RESTRICTED)
-
 enum tpm2_session_attributes {
 	TPM2_SA_CONTINUE_SESSION	= BIT(0),
 	TPM2_SA_AUDIT_EXCLUSIVE		= BIT(1),