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

[Roberto Sassu]

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@xxxxxxxxxx>
> > ---
> >  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;
> >  }
> >
> >  /*