1 files changed, 20 insertions, 8 deletions

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 5294442505cb..0f1dc35e7078 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -328,7 +328,7 @@ unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip,
 }
 EXPORT_SYMBOL_GPL(tpm_calc_ordinal_duration);
 
-static bool tpm_validate_command(struct tpm_chip *chip,
+static int tpm_validate_command(struct tpm_chip *chip,
 				 struct tpm_space *space,
 				 const u8 *cmd,
 				 size_t len)
@@ -340,10 +340,10 @@ static bool tpm_validate_command(struct tpm_chip *chip,
 	unsigned int nr_handles;
 
 	if (len < TPM_HEADER_SIZE)
-		return false;
+		return -EINVAL;
 
 	if (!space)
-		return true;
+		return 0;
 
 	if (chip->flags & TPM_CHIP_FLAG_TPM2 && chip->nr_commands) {
 		cc = be32_to_cpu(header->ordinal);
@@ -352,7 +352,7 @@ static bool tpm_validate_command(struct tpm_chip *chip,
 		if (i < 0) {
 			dev_dbg(&chip->dev, "0x%04X is an invalid command\n",
 				cc);
-			return false;
+			return -EOPNOTSUPP;
 		}
 
 		attrs = chip->cc_attrs_tbl[i];
@@ -362,11 +362,11 @@ static bool tpm_validate_command(struct tpm_chip *chip,
 			goto err_len;
 	}
 
-	return true;
+	return 0;
 err_len:
 	dev_dbg(&chip->dev,
 		"%s: insufficient command length %zu", __func__, len);
-	return false;
+	return -EINVAL;
 }
 
 /**
@@ -391,8 +391,20 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
 	unsigned long stop;
 	bool need_locality;
 
-	if (!tpm_validate_command(chip, space, buf, bufsiz))
-		return -EINVAL;
+	rc = tpm_validate_command(chip, space, buf, bufsiz);
+	if (rc == -EINVAL)
+		return rc;
+	/*
+	 * If the command is not implemented by the TPM, synthesize a
+	 * response with a TPM2_RC_COMMAND_CODE return for user-space.
+	 */
+	if (rc == -EOPNOTSUPP) {
+		header->length = cpu_to_be32(sizeof(*header));
+		header->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
+		header->return_code = cpu_to_be32(TPM2_RC_COMMAND_CODE |
+						  TSS2_RESMGR_TPM_RC_LAYER);
+		return bufsiz;
+	}
 
 	if (bufsiz > TPM_BUFSIZE)
 		bufsiz = TPM_BUFSIZE;