Re: [PATCH 4/9] vtpmmgr: Allow specifying srk_handle for TPM2

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>]

Jason Andryuk, le mar. 04 mai 2021 08:48:37 -0400, a ecrit:
> Bypass taking ownership of the TPM2 if an srk_handle is specified.
> 
> This srk_handle must be usable with Null auth for the time being.
> 
> Signed-off-by: Jason Andryuk <jandryuk@xxxxxxxxx>
> ---
>  docs/man/xen-vtpmmgr.7.pod |  7 +++++++
>  stubdom/vtpmmgr/init.c     | 11 ++++++++++-
>  2 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/docs/man/xen-vtpmmgr.7.pod b/docs/man/xen-vtpmmgr.7.pod
> index 875dcce508..3286954568 100644
> --- a/docs/man/xen-vtpmmgr.7.pod
> +++ b/docs/man/xen-vtpmmgr.7.pod
> @@ -92,6 +92,13 @@ Valid arguments:
>  
>  =over 4
>  
> +=item srk_handle=<HANDLE>

Is this actually srk_handle= or srk_handle: ?

The code tests for the latter. The problem seems to "exist" also for
owner_auth: and srk_auth: but both = and : work actually because strncmp
is told not to check for = and :

We'd better clean this up to avoid confusions.

Samuel

> +
> +Specify a srk_handle for TPM 2.0.  TPM 2.0 uses a key hierarchy, and
> +this allow specifying the parent handle for vtpmmgr to create its own
> +key under.  Using this option bypasses vtpmmgr trying to take ownership
> +of the TPM.
> +
>  =item owner_auth=<AUTHSPEC>
>  
>  =item srk_auth=<AUTHSPEC>
> diff --git a/stubdom/vtpmmgr/init.c b/stubdom/vtpmmgr/init.c
> index 1506735051..c01d03e9f4 100644
> --- a/stubdom/vtpmmgr/init.c
> +++ b/stubdom/vtpmmgr/init.c
> @@ -302,6 +302,11 @@ int parse_cmdline_opts(int argc, char** argv, struct 
> Opts* opts)
>              goto err_invalid;
>           }
>        }
> +      else if(!strncmp(argv[i], "srk_handle:", 11)) {
> +         if(sscanf(argv[i] + 11, "%x", &vtpm_globals.srk_handle) != 1) {
> +            goto err_invalid;
> +         }
> +      }
>        else if(!strncmp(argv[i], "tpmdriver=", 10)) {
>           if(!strcmp(argv[i] + 10, "tpm_tis")) {
>              opts->tpmdriver = TPMDRV_TPM_TIS;
> @@ -586,7 +591,11 @@ TPM_RESULT vtpmmgr2_create(void)
>  {
>      TPM_RESULT status = TPM_SUCCESS;
>  
> -    TPMTRYRETURN(tpm2_take_ownership());
> +    if ( vtpm_globals.srk_handle == 0 ) {
> +        TPMTRYRETURN(tpm2_take_ownership());
> +    } else {
> +        tpm2_AuthArea_ctor(NULL, 0, &vtpm_globals.srk_auth_area);
> +    }
>  
>     /* create SK */
>      TPM2_Create_Params_out out;
> -- 
> 2.30.2
>