Re: [PATCH v2 1/3] keys, trusted: select the hash algorithm

Jarkko Sakkinen
2015-11-03T07:39:33Z

On Mon, Nov 02, 2015 at 07:16:49AM -0500, Mimi Zohar wrote:
> On Fri, 2015-10-30 at 13:35 +0200, Jarkko Sakkinen wrote:
>
> > @@ -787,6 +791,20 @@ static int getoptions(char *c, struct trusted_key_payload *pay,
> > return -EINVAL;
> > opt->pcrlock = lock;
> > break;
> > + case Opt_hash:
> > + for (i = 0; i < HASH_ALGO__LAST; i++) {
> > + if (!strcmp(args[0].from, hash_algo_name[i])) {
> > + opt->hash = i;
> > + break;
> > + }
> > + }
> > + res = tpm_is_tpm2(TPM_ANY_NUM);
>
> While looking at this, I wanted to verify that chips are still added to
> the tail of the tpm_chip_list. Unfortunately, commit "afb5abc tpm:
> two-phase chip management functions" reverted David Howell's commit
> "770ab65 TPM: Add new TPMs to the tail of the list to prevent
> inadvertent change of dev".
>
> > + if (res < 0)
> > + return res;
> > + if (i == HASH_ALGO__LAST ||
> > + (!res && i != HASH_ALGO_SHA1))
> > + return -EINVAL;
> > + break;
>
> If the first TPM registered is a TPM 1.2, then changing the default TPM
> 2.0 hash algorithm will fail.

Now that we are going fix this issue in 4.3 and 4.4 do you find this
patch otherwise acceptable?

PS. In other options that we don't support in TPM2 I'm planning to
submit a fix that they will return -EINVAL (like pcrinfo).

> Mimi

/Jarkko