| Message ID | 20241028055007.1708971-3-jarkko@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Lazy flush for the auth session | expand |
Dear Jarkko, Thank you for your patch. Am 28.10.24 um 06:50 schrieb Jarkko Sakkinen: > Do not continue on tpm2_create_primary() failure in tpm2_load_null(). Could you please elaborate, why this is done, that means the motivation for your change? > Cc: stable@vger.kernel.org # v6.10+ > Fixes: eb24c9788cd9 ("tpm: disable the TPM if NULL name changes") > Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> > Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> Kind regards, Paul
On Mon Oct 28, 2024 at 8:13 AM EET, Paul Menzel wrote: > Dear Jarkko, > > > Thank you for your patch. > > Am 28.10.24 um 06:50 schrieb Jarkko Sakkinen: > > Do not continue on tpm2_create_primary() failure in tpm2_load_null(). > > Could you please elaborate, why this is done, that means the motivation > for your change? Which part of "not properly handling a return value" I should explain? BR, Jarkko
Dear Jarkko, Am 28.10.24 um 13:10 schrieb Jarkko Sakkinen: > On Mon Oct 28, 2024 at 8:13 AM EET, Paul Menzel wrote: >> Am 28.10.24 um 06:50 schrieb Jarkko Sakkinen: >>> Do not continue on tpm2_create_primary() failure in tpm2_load_null(). >> >> Could you please elaborate, why this is done, that means the motivation >> for your change? > > Which part of "not properly handling a return value" I should explain? Sorry, where is your quote from? Anyway, maybe explaining why a successful call to tpm2_create_primary() is needed to continue would at least help me. Kind regards, Paul
On Mon Oct 28, 2024 at 2:38 PM EET, Paul Menzel wrote: > Dear Jarkko, > > > Am 28.10.24 um 13:10 schrieb Jarkko Sakkinen: > > On Mon Oct 28, 2024 at 8:13 AM EET, Paul Menzel wrote: > > >> Am 28.10.24 um 06:50 schrieb Jarkko Sakkinen: > >>> Do not continue on tpm2_create_primary() failure in tpm2_load_null(). > >> > >> Could you please elaborate, why this is done, that means the motivation > >> for your change? > > > > Which part of "not properly handling a return value" I should explain? > > Sorry, where is your quote from? > > Anyway, maybe explaining why a successful call to tpm2_create_primary() > is needed to continue would at least help me. It's not a void function. BR, Jarkko
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c index a0306126e86c..950a3e48293b 100644 --- a/drivers/char/tpm/tpm2-sessions.c +++ b/drivers/char/tpm/tpm2-sessions.c @@ -915,33 +915,37 @@ static int tpm2_parse_start_auth_session(struct tpm2_auth *auth, static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key) { - int rc; unsigned int offset = 0; /* dummy offset for null seed context */ u8 name[SHA256_DIGEST_SIZE + 2]; + u32 tmp_null_key; + int rc; rc = tpm2_load_context(chip, chip->null_key_context, &offset, - null_key); - if (rc != -EINVAL) - return rc; + &tmp_null_key); + if (rc != -EINVAL) { + if (!rc) + *null_key = tmp_null_key; + goto err; + } - /* an integrity failure may mean the TPM has been reset */ - dev_err(&chip->dev, "NULL key integrity failure!\n"); - /* check the null name against what we know */ - tpm2_create_primary(chip, TPM2_RH_NULL, NULL, name); - if (memcmp(name, chip->null_key_name, sizeof(name)) == 0) - /* name unchanged, assume transient integrity failure */ - return rc; - /* - * Fatal TPM failure: the NULL seed has actually changed, so - * the TPM must have been illegally reset. All in-kernel TPM - * operations will fail because the NULL primary can't be - * loaded to salt the sessions, but disable the TPM anyway so - * userspace programmes can't be compromised by it. - */ - dev_err(&chip->dev, "NULL name has changed, disabling TPM due to interference\n"); + /* Try to re-create null key, given the integrity failure: */ + rc = tpm2_create_primary(chip, TPM2_RH_NULL, &tmp_null_key, name); + if (rc) + goto err; + + /* Return null key if the name has not been changed: */ + if (!memcmp(name, chip->null_key_name, sizeof(name))) { + *null_key = tmp_null_key; + return 0; + } + + /* Deduce from the name change TPM interference: */ + dev_err(&chip->dev, "null key integrity check failed\n"); + tpm2_flush_context(chip, tmp_null_key); chip->flags |= TPM_CHIP_FLAG_DISABLE; - return rc; +err: + return rc ? -ENODEV : 0; } /**
Do not continue on tpm2_create_primary() failure in tpm2_load_null(). Cc: stable@vger.kernel.org # v6.10+ Fixes: eb24c9788cd9 ("tpm: disable the TPM if NULL name changes") Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> --- v8: - Fix stray character in a log message. v7: - No changes. v6: - Address Stefan's remark: https://lore.kernel.org/linux-integrity/def4ec2d-584b-405f-9d5e-99267013c3c0@linux.ibm.com/ v5: - Fix the TPM error code leak from tpm2_load_context(). v4: - No changes. v3: - Update log messages. Previously the log message incorrectly stated on load failure that integrity check had been failed, even tho the check is done *after* the load operation. v2: - Refined the commit message. - Reverted tpm2_create_primary() changes. They are not required if tmp_null_key is used as the parameter. --- drivers/char/tpm/tpm2-sessions.c | 44 +++++++++++++++++--------------- 1 file changed, 24 insertions(+), 20 deletions(-)