Re: [PATCH v7 2/3] ima-evm-utils: Allow manual setting keyid from a cert file

[Vitaly Chikunov <vt@altlinux.org>]

Mimi,

On Mon, Jul 05, 2021 at 03:59:02PM -0400, Mimi Zohar wrote:
> On Thu, 2021-07-01 at 04:13 +0300, Vitaly Chikunov wrote:
> 
> > @@ -2805,6 +2811,14 @@ int main(int argc, char *argv[])
> >  			}
> >  			imaevm_params.keyid = keyid;
> >  			break;
> > +		case 145:
> > +			keyid = imaevm_read_keyid(optarg);
> > +			if (keyid == 0) {
> 
> The function comment indicates zero is returned on error, which is
> normally true, but -1 is returned to indicate reading the cert failed. 

Ah, bug.

Thanks!

> 
> > +				log_err("Error reading keyid.\n");
> > +				exit(1);
> > +			}
> > +			imaevm_params.keyid = keyid;
> 
> As a result, imaevm_params.keyid is set to -1, which the "--keyid="
> case would detect, but isn't detected here.
> 
> > +			break;
> >  		case '?':
> >  			exit(1);
> >  			break;
> > diff --git a/src/imaevm.h b/src/imaevm.h
> > index fe244f1..491f136 100644
> > --- a/src/imaevm.h
> > +++ b/src/imaevm.h
> > 
> > +/**
> 
> kernel doc?  :)
> 
> > + * imaevm_read_keyid() - Read 32-bit keyid from the cert file
> > + * @certfile:	File with certificate in PEM or DER form.
> > + *
> > + * Try to read keyid from Subject Key Identifier (SKID) of x509 certificate.
> > + * Autodetect if cert is in PEM (tried first) or DER encoding.
> > + *
> > + * Return: 0 on error, logged error message;
> > + *         32-bit keyid in host order.
> 
> As mentioned above, -1 could be returned.
> 
> > + */
> > +uint32_t imaevm_read_keyid(const char *certfile)
> > +{
> > +	uint32_t keyid_be = 0;
> > +	X509 *x;
> > +
> > +	/* true: to load in DER form too. */
> > +	if (!(x = read_cert(certfile, true)))
> > +		return -1;
> > +	extract_keyid(&keyid_be, x, certfile);
> > +	/* On error keyid_be will not be set, returning 0. */
> 
> Ok
> 
> thanks,
> 
> Mimi
> 
> > +	X509_free(x);
> > +	return ntohl(keyid_be);
> > +}
> > +
> >  static EVP_PKEY *read_priv_pkey(const char *keyfile, const char *keypass)
> >  {
> >  	FILE *fp;