On Sun Aug 4, 2024 at 4:42 PM EEST, James Bottomley wrote:
> The design of the intel-tss shim is to hide the difference between the
> internal and the external handles by doing the internal to external
> transform on entry. Unfortunately, the NULL handle (TPM_RH_NULL,
> 40000007) has two possible internal representations depending on
> whether it's used to indicate no session or the null hierarcy.
>
> There is a bug in the intel-tss in that it uses the wrong internal
> NULL handle to try to create the NULL seed primary (and thus fails).
> Now that we're going to be using the NULL primary to salt sessions,
> the Intel TSS shim needs fixing to cope with thi correctly.
>
> The fix is to do the correct transform to the internal hierarchy
> representation on NULL hierarchy creation and to do the session handle
> conversion everywhere else. Additionally remove the intel_handle()
> code which was supposed to do this: it's unused because 0 is never
> passed in as a handle number.
>
> Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
>
> ---
> v2: reword commit message
>
> ---
> src/include/intel-tss.h | 18 +++++-------------
> 1 file changed, 5 insertions(+), 13 deletions(-)
>
> diff --git a/src/include/intel-tss.h b/src/include/intel-tss.h
> index 1870b4e..5b8db20 100644
> --- a/src/include/intel-tss.h
> +++ b/src/include/intel-tss.h
> @@ -251,14 +251,6 @@ intel_sess_helper(TSS_CONTEXT *tssContext,
> TPM_HANDLE auth, TPMA_SESSION flags)
> TPMA_SESSION_CONTINUESESSION |
> flags);
> }
>
> -static inline TPM_HANDLE
> -intel_handle(TPM_HANDLE h)
> -{
> - if (h == 0)
> - return ESYS_TR_NONE;
> - return h;
> -}
> -
> static inline void
> TSS_Delete(TSS_CONTEXT *tssContext)
> {
> @@ -937,8 +929,10 @@ tpm2_CreatePrimary(TSS_CONTEXT *tssContext,
> TPM_HANDLE primaryHandle,
> TPM2B_PUBLIC *opub;
> TPM_RC rc;
>
> - /* FIXME will generate wrong value for NULL hierarchy */
> - primaryHandle = intel_handle(primaryHandle);
> +
> + /* TPM_RH_NULL is mapped to ESYS_TR_NONE, which won't work
> here */
> + if (primaryHandle == TPM_RH_NULL)
> + primaryHandle = INT_TPM_RH_NULL;
>
> outsideInfo.size = 0;
> creationPcr.count = 0;
> @@ -993,9 +987,7 @@ tpm2_StartAuthSession(TSS_CONTEXT *tssContext,
> TPM_HANDLE tpmKey,
> TPM_HANDLE *sessionHandle,
> const char *bindPassword)
> {
> - bind = intel_handle(bind);
> - tpmKey = intel_handle(tpmKey);
> - if (bind != ESYS_TR_NONE)
> + if (bind != TPM_RH_NULL)
> intel_auth_helper(tssContext, bind, bindPassword);
Not blaming the patch but just have hard time coping this.
The most basic question is probably this: what is the application for
INT_TPM_RH_NULL?
Let's imagine that we have a flow chart describing Intel shim as a state
machine. I decide to shoot it with these three stimulus:
1. INT_TPM_RH_NULL
2. TPM_RH_NULL
3. A valid handle
What happens in each case to its state?
>
> return Esys_StartAuthSession(tssContext, tpmKey, bind,
> ESYS_TR_NONE,
BR, Jarkko
