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tpm: Mask TPM RC in tpm2_start_auth_session()

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commit 539fbab378 upstream.

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: 699e3efd6c ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jarkko Sakkinen
2025-04-07 15:28:05 +03:00
committed by Greg Kroah-Hartman
parent cac03fecbc
commit ec5d9a750e
2 changed files with 25 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
drivers/char/tpm/tpm2-sessions.c
View File

@@ -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 @@ err:
}
/**
* 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)

19
include/linux/tpm.h
View File

@@ -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);