[ck] [PATCH 14/17] KEYS: trusted: allow module init if TPM is inactive or deactivated

From: Roberto Sassu &lt;roberto.sassu(a)huawei.com&gt; commit 2d6c25215ab26bb009de3575faab7b685f138e92 upstream. 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(a)vger.kernel.org Fixes: 240730437deb ("KEYS: trusted: explicitly use tpm_chip structure...") Signed-off-by: Roberto Sassu &lt;roberto.sassu(a)huawei.com&gt; Reviewed-by: Tyler Hicks &lt;tyhicks(a)canonical.com&gt; Suggested-by: Mimi Zohar &lt;zohar(a)linux.ibm.com&gt; Reviewed-by: Jarkko Sakkinen &lt;jarkko.sakkinen(a)linux.intel.com&gt; Signed-off-by: Jarkko Sakkinen &lt;jarkko.sakkinen(a)linux.intel.com&gt; Signed-off-by: mayuanchen &lt;mayuanchen(a)hygon.cn&gt; Change-Id: I6090f4610d9fe239074b742b36a4a28d95ff972a --- security/keys/trusted.c | 13 ------------- 1 file changed, 13 deletions(-) diff --git a/security/keys/trusted.c b/security/keys/trusted.c index fb934887b2d2..4b43ff25bdc4 100644 --- a/security/keys/trusted.c +++ b/security/keys/trusted.c @@ -1216,24 +1216,11 @@ static int __init trusted_shash_alloc(void) 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; } -- 2.17.1