[PATCH] efi_loader: add EFI_TCG2_PROTOCOL.SubmitCommand

[Masahisa Kojima]

On Fri, 29 Oct 2021 at 18:43, Masahisa Kojima
<masahisa.kojima at linaro.org> wrote:
>
> On Fri, 29 Oct 2021 at 15:26, Ilias Apalodimas
> <ilias.apalodimas at linaro.org> wrote:
> >
> >
> > On Fri, Oct 22, 2021 at 08:20:55PM +0900, Masahisa Kojima wrote:
> > > This commit adds the EFI_TCG2_PROTOCOL.SubmitCommand
> > > required in the TCG PC Client PFP spec.
> > > SubmitCommand enables to send the raw command to the TPM device.
> > >
> > > To implement this api, tpm2_submit_command() is added
> > > into tpm-v2.c.
> > >
> > > Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
> > > ---
> > >  include/tpm-v2.h          | 15 +++++++++++++++
> > >  lib/efi_loader/efi_tcg2.c | 37 +++++++++++++++++++++++++++++++------
> > >  lib/tpm-v2.c              |  6 ++++++
> > >  3 files changed, 52 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/include/tpm-v2.h b/include/tpm-v2.h
> > > index e6b68769f3..6b04a637ca 100644
> > > --- a/include/tpm-v2.h
> > > +++ b/include/tpm-v2.h
> > > @@ -642,4 +642,19 @@ u32 tpm2_write_lock(struct udevice *dev, u32 index);
> > >   */
> > >  u32 tpm2_disable_platform_hierarchy(struct udevice *dev);
> > >
> > > +/**
> > > + * submit user specified data to the TPM and get response
> > > + *
> > > + * @dev              TPM device
> > > + * @sendbuf: Buffer of the data to send
> > > + * @send_size:       Size of the data to send
> > > + * @recvbuf: Buffer to save the response to
> > > + * @recv_size:       Pointer to the size of the response buffer
> > > + *
> > > + * Returns 0 on success (and places the number of response bytes at
> > > + * recv_size) or -ve on failure.
> > > + */
> > > +u32 tpm2_submit_command(struct udevice *dev, const u8 *sendbuf,
> > > +                     size_t send_size, u8 *recvbuf, size_t *recv_size);
> > > +
> > >  #endif /* __TPM_V2_H */
> > > diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c
> > > index da02e281e7..a0728b555e 100644
> > > --- a/lib/efi_loader/efi_tcg2.c
> > > +++ b/lib/efi_loader/efi_tcg2.c
> > > @@ -1033,13 +1033,38 @@ out:
> > >   * Return:   status code
> > >   */
> > >  static efi_status_t EFIAPI
> > > -efi_tcg2_submit_command(__maybe_unused struct efi_tcg2_protocol *this,
> > > -                     u32 __maybe_unused input_param_block_size,
> > > -                     u8 __maybe_unused *input_param_block,
> > > -                     u32 __maybe_unused output_param_block_size,
> > > -                     u8 __maybe_unused *output_param_block)
> > > +efi_tcg2_submit_command(struct efi_tcg2_protocol *this,
> > > +                     u32 input_param_block_size,
> > > +                     u8 *input_param_block,
> > > +                     u32 output_param_block_size,
> > > +                     u8 *output_param_block)
> > >  {
> > > -     return EFI_UNSUPPORTED;
> > > +     struct udevice *dev;
> > > +     efi_status_t ret;
> > > +     u32 rc;
> > > +     size_t resp_buf_size = output_param_block_size;
> > > +
> > > +     EFI_ENTRY("%p, %u, %p, %u, %p", this, input_param_block_size,
> > > +               input_param_block, output_param_block_size, output_param_block);
> > > +
> > > +     if (!this || !input_param_block || !input_param_block_size) {
> > > +             ret = EFI_INVALID_PARAMETER;
> > > +             goto out;
> > > +     }
> > > +
> > > +     ret = platform_get_tpm2_device(&dev);
> > > +     if (ret != EFI_SUCCESS)
> > > +             goto out;
> > > +
> > > +     rc = tpm2_submit_command(dev, input_param_block, input_param_block_size,
> > > +                              output_param_block, &resp_buf_size);
> >
> > Shouldn't you check resp_buf_size against output_param_block_size here and
> > return EFI_BUFFER_TOO_SMALL if the output_param_block_size is smaller?
>
> It should be checked, thank you.

tpm_sendrecv_command() does not fill *recv_size with the received size
if the *recv_size is smaller than the actual received size, it just
return -ENOSPC.

So instead of checking resp_buf_size, check return code and
if rc is -ENOSPC then return EFI_BUFFER_TOO_SMALL.

Thanks,
Masahisa Kojima

>
> >
> > > +     if (rc) {
> > > +             ret = EFI_DEVICE_ERROR;
> > > +             goto out;
> > > +     }
> > > +
> > > +out:
> > > +     return EFI_EXIT(ret);
> > >  }
> > >
> > >  /**
> > > diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
> > > index 235f8c20d4..ee08948ec1 100644
> > > --- a/lib/tpm-v2.c
> > > +++ b/lib/tpm-v2.c
> > > @@ -659,3 +659,9 @@ u32 tpm2_disable_platform_hierarchy(struct udevice *dev)
> > >
> > >       return 0;
> > >  }
> > > +
> > > +u32 tpm2_submit_command(struct udevice *dev, const u8 *sendbuf,
> > > +                     size_t send_size, u8 *recvbuf, size_t *recv_size)
> >
> > Why do we keep send_size in the arg list? tpm_sendrecv_command is exported
> > anyway, so we can just use that?
>
> Yes, send_size is not used, should be removed.
>
> tpm_sendrecv_command() is exported, but declared in lib/tpm-utils.h,
> it means this function can only be called under u-boot/lib, can not be
> called from ./lib/efi_loader/*.
> Also the tpm stack seems to be designed having following layers.
>  tpm-v1/2.c -> tpm-common.c -> device-dependent driver
>
> Thanks,
> Masahisa Kojima
>
> >
> > > +{
> > > +     return tpm_sendrecv_command(dev, sendbuf, recvbuf, recv_size);
> > > +}
> > > --
> > > 2.17.1
> > >
> >
> > Thanks!
> > /Ilias