Commit 539fbab3 authored by Jarkko Sakkinen's avatar Jarkko Sakkinen
Browse files

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: 699e3efd ("tpm: Add HMAC session start and end functions")
Reported-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Closes: https://lore.kernel.org/linux-integrity/Z_NgdRHuTKP6JK--@gondor.apana.org.au/


Reviewed-by: default avatarStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
parent 74a63255

drivers/char/tpm/tpm2-sessions.c

+6 −14
Original line number Diff line number Diff line
@@ -40,11 +40,6 @@ 
 *

 * These are the usage functions:

 *

 * tpm2_start_auth_session() which allocates the opaque auth structure

 *	and gets a session from the TPM.  This must be called before

 *	any of the following functions.  The session is protected by a

 *	session_key which is derived from a random salt value

 *	encrypted to the NULL seed.

 * tpm2_end_auth_session() kills the session and frees the resources.

 *	Under normal operation this function is done by

 *	tpm_buf_check_hmac_response(), so this is only to be used on
@@ -963,16 +958,13 @@ static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key) 
}



/**

 * tpm2_start_auth_session() - create a HMAC authentication session with the TPM

 * @chip: the TPM chip structure to create the session with

 * tpm2_start_auth_session() - Create an a HMAC authentication session

 * @chip:	A TPM chip

 *

 * This function loads the NULL seed from its saved context and starts

 * an authentication session on the null seed, fills in the

 * @chip->auth structure to contain all the session details necessary

 * for performing the HMAC, encrypt and decrypt operations and

 * returns.  The NULL seed is flushed before this function returns.

 * Loads the ephemeral key (null seed), and starts an HMAC authenticated

 * session. The null seed is flushed before the return.

 *

 * Return: zero on success or actual error encountered.

 * Returns zero on success, or a POSIX error code.

 */

int tpm2_start_auth_session(struct tpm_chip *chip)

{
@@ -1024,7 +1016,7 @@ int tpm2_start_auth_session(struct tpm_chip *chip) 
	/* hash algorithm for session */

	tpm_buf_append_u16(&buf, TPM_ALG_SHA256);



	rc = tpm_transmit_cmd(chip, &buf, 0, "start auth session");

	rc = tpm_ret_to_err(tpm_transmit_cmd(chip, &buf, 0, "StartAuthSession"));

	tpm2_flush_context(chip, null_key);



	if (rc == TPM2_RC_SUCCESS)

include/linux/tpm.h

+19 −0
Original line number Diff line number Diff line
@@ -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);