Re: [Linux-ima-devel] [PATCH v2 4/5] keys, trusted: modify arguments of tpm_pcr_extend()

Roberto Sassu
2017-05-30T07:36:38Z

On 5/30/2017 5:35 AM, Mimi Zohar wrote:
> On Fri, 2017-05-05 at 16:21 +0200, Roberto Sassu wrote:
>> pcrlock() has been modified to pass the correct arguments
>> to tpm_pcr_extend(): the pointer of a tpm2_digest structure containing
>> a random value generated by tpm_get_random() and the size of the array (1).
>
> If the number of arguments is wrong, that means the patch that
> introduced the change is not bi-sect safe. (This comment is
> applicable to patch 5/5 too.)

Jarkko (the TPM driver maintainer) asked me to not introduce
a new function to pass multiple digests, but to modify
the parameters of tpm_pcr_extend().

Roberto

>
> Mimi
>
>> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
>> ---
>> security/keys/trusted.c | 6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/security/keys/trusted.c b/security/keys/trusted.c
>> index 2ae31c5..3eb89e6 100644
>> --- a/security/keys/trusted.c
>> +++ b/security/keys/trusted.c
>> @@ -377,15 +377,15 @@ static int trusted_tpm_send(const u32 chip_num, unsigned char *cmd,
>> */
>> static int pcrlock(const int pcrnum)
>> {
>> - unsigned char hash[SHA1_DIGEST_SIZE];
>> + struct tpm2_digest digestarg = {.alg_id = TPM2_ALG_SHA1};
>> int ret;
>>
>> if (!capable(CAP_SYS_ADMIN))
>> return -EPERM;
>> - ret = tpm_get_random(TPM_ANY_NUM, hash, SHA1_DIGEST_SIZE);
>> + ret = tpm_get_random(TPM_ANY_NUM, digestarg.digest, SHA1_DIGEST_SIZE);
>> if (ret != SHA1_DIGEST_SIZE)
>> return ret;
>> - return tpm_pcr_extend(TPM_ANY_NUM, pcrnum, hash) ? -EINVAL : 0;
>> + return tpm_pcr_extend(TPM_ANY_NUM, pcrnum, 1, &digestarg) ? -EINVAL : 0;
>> }
>>
>> /*
>