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... Signed-off-by: Jarkko Sakkinen jarkko@kernel.org --- v2: - Investigate TPM rc only after destroying tpm_buf. --- drivers/char/tpm/tpm2-sessions.c | 29 +++++++++++++++-------------- include/linux/tpm.h | 1 + 2 files changed, 16 insertions(+), 14 deletions(-)
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c index 3f89635ba5e8..da382b86dc41 100644 --- a/drivers/char/tpm/tpm2-sessions.c +++ b/drivers/char/tpm/tpm2-sessions.c @@ -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_transmit_cmd(chip, &buf, 0, "StartAuthSession"); tpm2_flush_context(chip, null_key);
if (rc == TPM2_RC_SUCCESS) @@ -1032,6 +1024,15 @@ int tpm2_start_auth_session(struct tpm_chip *chip)
tpm_buf_destroy(&buf);
+ switch (rc) { + case TPM2_RC_SESSION_MEMORY: + rc = -ENOMEM; + goto out; + default: + rc = -EFAULT; + goto out; + } + if (rc == TPM2_RC_SUCCESS) { chip->auth = auth; return 0; diff --git a/include/linux/tpm.h b/include/linux/tpm.h index 6c3125300c00..c1d3d60b416f 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 {