On 10/21/24 1:39 AM, Jarkko Sakkinen wrote:

Instead of flushing and reloading the auth session for every single transaction, keep the session open unless /dev/tpm0 is used. In practice this means applying TPM2_SA_CONTINUE_SESSION to the session attributes. Flush the session always when /dev/tpm0 is written.

Reported-by: Pengyu Ma mapengyu@gmail.com Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219229 Cc: stable@vger.kernel.org # v6.10+ Fixes: 7ca110f2679b ("tpm: Address !chip->auth in tpm_buf_append_hmac_session*()") Tested-by: Pengyu Ma mapengyu@gmail.com Signed-off-by: Jarkko Sakkinen jarkko@kernel.org

---

v5:

• No changes.

v4:

• Changed as bug.

v3:

• Refined the commit message.
• Removed the conditional for applying TPM2_SA_CONTINUE_SESSION only when /dev/tpm0 is open. It is not required as the auth session is flushed, not saved.

v2:

• A new patch.

---

drivers/char/tpm/tpm-chip.c | 1 + drivers/char/tpm/tpm-dev-common.c | 1 + drivers/char/tpm/tpm-interface.c | 1 + drivers/char/tpm/tpm2-sessions.c | 3 +++ 4 files changed, 6 insertions(+)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index 0ea00e32f575..7a6bb30d1f32 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -680,6 +680,7 @@ void tpm_chip_unregister(struct tpm_chip *chip) rc = tpm_try_get_ops(chip); if (!rc) { if (chip->flags & TPM_CHIP_FLAG_TPM2) {

• 	tpm2_end_auth_session(chip);
  

That could also go into the inline. Looks good otherwise.

	tpm2_flush_context(chip, chip->null_key);
	chip->null_key = 0;
}

diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c index 4eaa8e05c291..a3ed7a99a394 100644 --- a/drivers/char/tpm/tpm-dev-common.c +++ b/drivers/char/tpm/tpm-dev-common.c @@ -29,6 +29,7 @@ static ssize_t tpm_dev_transmit(struct tpm_chip *chip, struct tpm_space *space, #ifdef CONFIG_TCG_TPM2_HMAC if (chip->flags & TPM_CHIP_FLAG_TPM2) {

• tpm2_end_auth_session(chip);
  

  tpm2_flush_context(chip, chip->null_key); chip->null_key = 0; }

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c index bfa47d48b0f2..2363018fa8fb 100644 --- a/drivers/char/tpm/tpm-interface.c +++ b/drivers/char/tpm/tpm-interface.c @@ -381,6 +381,7 @@ int tpm_pm_suspend(struct device *dev) if (!rc) { if (chip->flags & TPM_CHIP_FLAG_TPM2) { #ifdef CONFIG_TCG_TPM2_HMAC

• 	tpm2_end_auth_session(chip);
  tpm2_flush_context(chip, chip->null_key);
  chip->null_key = 0;
  

  #endif

diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c index 6e52785de9fd..a7079c7ec6d1 100644 --- a/drivers/char/tpm/tpm2-sessions.c +++ b/drivers/char/tpm/tpm2-sessions.c @@ -333,6 +333,9 @@ void tpm_buf_append_hmac_session(struct tpm_chip *chip, struct tpm_buf *buf, } #ifdef CONFIG_TCG_TPM2_HMAC

• /* The first write to /dev/tpm{rm0} will flush the session. */
• attributes |= TPM2_SA_CONTINUE_SESSION;
• /*
  • The Architecture Guide requires us to strip trailing zeros
  • before computing the HMAC