linux-kernel - [PATCH] tpm: Use -EPERM as fallback error code in tpm_ret_to

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Message-Id: <20250922072332.2649135-1-jarkko@kernel.org>
Date: Mon, 22 Sep 2025 10:23:32 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: linux-integrity@...r.kernel.org
Cc: Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>,
	stable@...r.kernel.org,
	Peter Huewe <peterhuewe@....de>,
	Jarkko Sakkinen <jarkko@...nel.org>,
	Jason Gunthorpe <jgg@...pe.ca>,
	David Howells <dhowells@...hat.com>,
	Paul Moore <paul@...l-moore.com>,
	James Morris <jmorris@...ei.org>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	Mimi Zohar <zohar@...ux.ibm.com>,
	Stefano Garzarella <sgarzare@...hat.com>,
	linux-kernel@...r.kernel.org (open list),
	keyrings@...r.kernel.org (open list:KEYS/KEYRINGS),
	linux-security-module@...r.kernel.org (open list:SECURITY SUBSYSTEM)
Subject: [PATCH] tpm: Use -EPERM as fallback error code in tpm_ret_to_err

From: Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>

Using -EFAULT here was not the best idea for tpm_ret_to_err as the fallback
error code as it is no concise with trusted keys.

Change the fallback as -EPERM, process TPM_RC_HASH also in tpm_ret_to_err,
and by these changes make the helper applicable for trusted keys.

Cc: stable@...r.kernel.org # v6.15+
Fixes: 539fbab37881 ("tpm: Mask TPM RC in tpm2_start_auth_session()")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>
---
 include/linux/tpm.h                       |  9 +++++---
 security/keys/trusted-keys/trusted_tpm2.c | 26 ++++++-----------------
 2 files changed, 13 insertions(+), 22 deletions(-)

diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index dc0338a783f3..667d290789ca 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -449,13 +449,16 @@ static inline ssize_t tpm_ret_to_err(ssize_t ret)
 	if (ret < 0)
 		return ret;
 
-	switch (tpm2_rc_value(ret)) {
-	case TPM2_RC_SUCCESS:
+	if (!ret)
 		return 0;
+
+	switch (tpm2_rc_value(ret)) {
 	case TPM2_RC_SESSION_MEMORY:
 		return -ENOMEM;
+	case TPM2_RC_HASH:
+		return -EINVAL;
 	default:
-		return -EFAULT;
+		return -EPERM;
 	}
 }
 
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index 024be262702f..e165b117bbca 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -348,25 +348,19 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	}
 
 	blob_len = tpm2_key_encode(payload, options, &buf.data[offset], blob_len);
+	if (blob_len < 0)
+		rc = blob_len;
 
 out:
 	tpm_buf_destroy(&sized);
 	tpm_buf_destroy(&buf);
 
-	if (rc > 0) {
-		if (tpm2_rc_value(rc) == TPM2_RC_HASH)
-			rc = -EINVAL;
-		else
-			rc = -EPERM;
-	}
-	if (blob_len < 0)
-		rc = blob_len;
-	else
+	if (!rc)
 		payload->blob_len = blob_len;
 
 out_put:
 	tpm_put_ops(chip);
-	return rc;
+	return tpm_ret_to_err(rc);
 }
 
 /**
@@ -468,10 +462,7 @@ static int tpm2_load_cmd(struct tpm_chip *chip,
 		kfree(blob);
 	tpm_buf_destroy(&buf);
 
-	if (rc > 0)
-		rc = -EPERM;
-
-	return rc;
+	return tpm_ret_to_err(rc);
 }
 
 /**
@@ -534,8 +525,6 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 	tpm_buf_fill_hmac_session(chip, &buf);
 	rc = tpm_transmit_cmd(chip, &buf, 6, "unsealing");
 	rc = tpm_buf_check_hmac_response(chip, &buf, rc);
-	if (rc > 0)
-		rc = -EPERM;
 
 	if (!rc) {
 		data_len = be16_to_cpup(
@@ -568,7 +557,7 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip,
 
 out:
 	tpm_buf_destroy(&buf);
-	return rc;
+	return tpm_ret_to_err(rc);
 }
 
 /**
@@ -600,6 +589,5 @@ int tpm2_unseal_trusted(struct tpm_chip *chip,
 
 out:
 	tpm_put_ops(chip);
-
-	return rc;
+	return tpm_ret_to_err(rc);
 }
-- 
2.39.5