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tpm: Rollback tpm2_load_null()

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Do not continue on tpm2_create_primary() failure in tpm2_load_null().

Cc: stable@vger.kernel.org # v6.10+
Fixes: eb24c9788c ("tpm: disable the TPM if NULL name changes")
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
This commit is contained in:
Jarkko Sakkinen 2024-10-28 07:50:00 +02:00
parent d658d59471
commit cc7d859434
1 changed files with 24 additions and 20 deletions
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44
drivers/char/tpm/tpm2-sessions.c
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@ -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) static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key)
{ {
int rc;
unsigned int offset = 0; /* dummy offset for null seed context */ unsigned int offset = 0; /* dummy offset for null seed context */
u8 name[SHA256_DIGEST_SIZE + 2]; u8 name[SHA256_DIGEST_SIZE + 2];
u32 tmp_null_key;
int rc;
rc = tpm2_load_context(chip, chip->null_key_context, &offset, rc = tpm2_load_context(chip, chip->null_key_context, &offset,
null_key); &tmp_null_key);
if (rc != -EINVAL) if (rc != -EINVAL) {
return rc; if (!rc)
*null_key = tmp_null_key;
goto err;
}
/* an integrity failure may mean the TPM has been reset */ /* Try to re-create null key, given the integrity failure: */
dev_err(&chip->dev, "NULL key integrity failure!\n"); rc = tpm2_create_primary(chip, TPM2_RH_NULL, &tmp_null_key, name);
/* check the null name against what we know */ if (rc)
tpm2_create_primary(chip, TPM2_RH_NULL, NULL, name); goto err;
if (memcmp(name, chip->null_key_name, sizeof(name)) == 0)
/* name unchanged, assume transient integrity failure */ /* Return null key if the name has not been changed: */
return rc; if (!memcmp(name, chip->null_key_name, sizeof(name))) {
/* *null_key = tmp_null_key;
* Fatal TPM failure: the NULL seed has actually changed, so return 0;
* 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 /* Deduce from the name change TPM interference: */
* userspace programmes can't be compromised by it. dev_err(&chip->dev, "null key integrity check failed\n");
*/ tpm2_flush_context(chip, tmp_null_key);
dev_err(&chip->dev, "NULL name has changed, disabling TPM due to interference\n");
chip->flags |= TPM_CHIP_FLAG_DISABLE; chip->flags |= TPM_CHIP_FLAG_DISABLE;
return rc; err:
return rc ? -ENODEV : 0;
} }
/** /**