TPM module: lack of internal kernel interface

TPM module: lack of internal kernel interface

[David Kyle]

I'm currently working on implementing a trusted computing system using
the linux TPM driver, similar to enforcer
(http://enforcer.sourceforge.net).  As my project involves kernel
modifications that are highly unlikely to be of use within the
mainstream kernel, I am attempting to confine my kernel-level work to
a linux security module, so that my system will hopefully not be
affected too heavily by newer kernel versions.

Hovever, I have run into difficulty since the TPM driver included in
the kernel doesn't include a internal interface for TPM access from
within the kernel itself.  There is only a userspace character device
interface.  Is there in fact an internal TPM interface I'm not seeing?
 If not, is there a particular reason why there isn't (and shouldn't
be) one?

It seems to me that it would be important to have such an interface
for any trusted computing system.  Enforcer uses it's own tpm kernel
driver, which I'd definately like to avoid doing with my project.

If I were to extend the existing TPM driver with an internal kernel
interface, would it likely be included in the mainstream kernel?

Thanks,
David Kyle

Re: TPM module: lack of internal kernel interface

[Kylene Hall]

David-

I wouldn't have a problem with this.  In fact all that should be 
necessary is to export the tpm_transmit function and maybe a way to get 
the tpm_chip struct for the particular tpm you want since the driver is 
setup to handle multiple tpms.  We have played around with only 
exporting functions that were necessary (such as tpm_extend for work we 
have done but if there is a usecase for that it should work.

Thanks,
Kylie

David Kyle wrote:
> I'm currently working on implementing a trusted computing system using
> the linux TPM driver, similar to enforcer
> (http://enforcer.sourceforge.net).  As my project involves kernel
> modifications that are highly unlikely to be of use within the
> mainstream kernel, I am attempting to confine my kernel-level work to
> a linux security module, so that my system will hopefully not be
> affected too heavily by newer kernel versions.
> 
> Hovever, I have run into difficulty since the TPM driver included in
> the kernel doesn't include a internal interface for TPM access from
> within the kernel itself.  There is only a userspace character device
> interface.  Is there in fact an internal TPM interface I'm not seeing?
> If not, is there a particular reason why there isn't (and shouldn't
> be) one?
> 
> It seems to me that it would be important to have such an interface
> for any trusted computing system.  Enforcer uses it's own tpm kernel
> driver, which I'd definately like to avoid doing with my project.
> 
> If I were to extend the existing TPM driver with an internal kernel
> interface, would it likely be included in the mainstream kernel?
> 
> Thanks,
> David Kyle
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/