On Thu, Feb 16, 2023 at 03:14:03PM -0500, James Bottomley wrote:
> Introducing encryption sessions changes where the return parameters
> are located in the buffer because if a return session is present
> they're 4 bytes beyond the header with those 4 bytes showing the
> parameter length. If there is no return session, then they're in the
> usual place immediately after the header. The tpm_buf_parameters()
> encapsulates this calculation and should be used everywhere
> &buf.data[TPM_HEADER_SIZE] is used now
>
> Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/char/tpm/tpm-buf.c | 10 ++++++++++
> include/linux/tpm.h | 2 ++
> 2 files changed, 12 insertions(+)
>
> diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
> index b76158f9bcd0..2518b675e866 100644
> --- a/drivers/char/tpm/tpm-buf.c
> +++ b/drivers/char/tpm/tpm-buf.c
> @@ -183,3 +183,13 @@ u32 tpm_get_inc_u32(const u8 **ptr)
> return val;
> }
> EXPORT_SYMBOL_GPL(tpm_get_inc_u32);
> +
> +u8 *tpm_buf_parameters(struct tpm_buf *buf)
kdoc
> +{
> + int offset = TPM_HEADER_SIZE;
> +
> + if (tpm_buf_tag(buf) == TPM2_ST_SESSIONS)
> + offset += 4;
> +
> + return &buf->data[offset];
> +}
> diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> index f7cff1d114b0..fa8d1f932c0f 100644
> --- a/include/linux/tpm.h
> +++ b/include/linux/tpm.h
> @@ -339,6 +339,8 @@ u8 tpm_get_inc_u8(const u8 **ptr);
> u16 tpm_get_inc_u16(const u8 **ptr);
> u32 tpm_get_inc_u32(const u8 **ptr);
>
> +u8 *tpm_buf_parameters(struct tpm_buf *buf);
> +
> /*
> * Check if TPM device is in the firmware upgrade mode.
> */
> --
> 2.35.3
>
BR, Jarkko
