tpm: Mask TPM RC in tpm2_start_auth_session()

tpm2_start_auth_session() does not mask TPM RC correctly from the callers:

[   28.766528] tpm tpm0: A TPM error (2307) occurred start auth session

Process TPM RCs inside tpm2_start_auth_session(), and map them to POSIX
error codes.

Cc: stable@vger.kernel.org # v6.10+
Fixes: 699e3efd6c64 ("tpm: Add HMAC session start and end functions")
Reported-by: Herbert Xu <herbert@gondor.apana.org.au>
Closes: https://lore.kernel.org/linux-integrity/Z_NgdRHuTKP6JK--@gondor.apana.org.au/
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

1 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 6c3125300c00..9ac9768cc8f7 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -257,6 +257,7 @@ enum tpm2_return_codes {
 	TPM2_RC_TESTING		= 0x090A, /* RC_WARN */
 	TPM2_RC_REFERENCE_H0	= 0x0910,
 	TPM2_RC_RETRY		= 0x0922,
+	TPM2_RC_SESSION_MEMORY	= 0x0903,
 };
 
 enum tpm2_command_codes {
@@ -437,6 +438,24 @@ static inline u32 tpm2_rc_value(u32 rc)
 	return (rc & BIT(7)) ? rc & 0xbf : rc;
 }
 
+/*
+ * Convert a return value from tpm_transmit_cmd() to POSIX error code.
+ */
+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:
+		return 0;
+	case TPM2_RC_SESSION_MEMORY:
+		return -ENOMEM;
+	default:
+		return -EFAULT;
+	}
+}
+
 #if defined(CONFIG_TCG_TPM) || defined(CONFIG_TCG_TPM_MODULE)
 
 extern int tpm_is_tpm2(struct tpm_chip *chip);