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author | Roberto Sassu <roberto.sassu@huawei.com> | 2019-08-05 19:44:27 +0300 |
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committer | Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> | 2019-08-13 19:59:23 +0300 |
commit | 2d6c25215ab26bb009de3575faab7b685f138e92 (patch) | |
tree | c741ea6dc1f2b7040be70696eb10e3717aabdd3d /security/keys/trusted.c | |
parent | d45331b00ddb179e291766617259261c112db872 (diff) | |
download | linux-2d6c25215ab26bb009de3575faab7b685f138e92.tar.xz |
KEYS: trusted: allow module init if TPM is inactive or deactivated
Commit c78719203fc6 ("KEYS: trusted: allow trusted.ko to initialize w/o a
TPM") allows the trusted module to be loaded even if a TPM is not found, to
avoid module dependency problems.
However, trusted module initialization can still fail if the TPM is
inactive or deactivated. tpm_get_random() returns an error.
This patch removes the call to tpm_get_random() and instead extends the PCR
specified by the user with zeros. The security of this alternative is
equivalent to the previous one, as either option prevents with a PCR update
unsealing and misuse of sealed data by a user space process.
Even if a PCR is extended with zeros, instead of random data, it is still
computationally infeasible to find a value as input for a new PCR extend
operation, to obtain again the PCR value that would allow unsealing.
Cc: stable@vger.kernel.org
Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip structure...")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Tyler Hicks <tyhicks@canonical.com>
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Diffstat (limited to 'security/keys/trusted.c')
-rw-r--r-- | security/keys/trusted.c | 13 |
1 files changed, 0 insertions, 13 deletions
diff --git a/security/keys/trusted.c b/security/keys/trusted.c index 9a94672e7adc..ade699131065 100644 --- a/security/keys/trusted.c +++ b/security/keys/trusted.c @@ -1228,24 +1228,11 @@ hashalg_fail: static int __init init_digests(void) { - u8 digest[TPM_MAX_DIGEST_SIZE]; - int ret; - int i; - - ret = tpm_get_random(chip, digest, TPM_MAX_DIGEST_SIZE); - if (ret < 0) - return ret; - if (ret < TPM_MAX_DIGEST_SIZE) - return -EFAULT; - digests = kcalloc(chip->nr_allocated_banks, sizeof(*digests), GFP_KERNEL); if (!digests) return -ENOMEM; - for (i = 0; i < chip->nr_allocated_banks; i++) - memcpy(digests[i].digest, digest, TPM_MAX_DIGEST_SIZE); - return 0; } |