Re: [PATCH 1/1] tpm: fixed the nv_define_space command in TPMv2

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

Hi Michel

On Thu, Feb 13, 2025 at 12:43:34PM +0000, Michel Alex wrote:
> Added 2 HMAC bytes to the command message

Please cc the TPM maintainers, otherwise I might miss this patch.

What the patch does is obvious, can you add a better explanation of
- what it fixes / what was broken?
- pointers to spec that define the hmac size and placement?

Thanks
/Ilias
>
> Signed-off-by: Alex Michel <alex.michel@wiedemann-group.com>
> ---
>  lib/tpm-v2.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
> index 9ca7933c094..4a082af78af 100644
> --- a/lib/tpm-v2.c
> +++ b/lib/tpm-v2.c
> @@ -264,7 +264,7 @@ u32 tpm2_nv_define_space(struct udevice *dev, u32 space_index,
>  	 * chunks below.
>  	 */
>  	const int platform_len = sizeof(u32);
> -	const int session_hdr_len = 13;
> +	const int session_hdr_len = 15;
>  	const int message_len = 14;
>  	uint offset = TPM2_HDR_LEN + platform_len + session_hdr_len +
>  		message_len;
> @@ -277,11 +277,12 @@ u32 tpm2_nv_define_space(struct udevice *dev, u32 space_index,
>  		/* handles 4 bytes */
>  		tpm_u32(TPM2_RH_PLATFORM),	/* Primary platform seed */
>
> -		/* session header 13 bytes */
> +		/* session header 15 bytes */
>  		tpm_u32(9),			/* Header size */
>  		tpm_u32(TPM2_RS_PW),		/* Password authorisation */
>  		tpm_u16(0),			/* nonce_size */
>  		0,				/* session_attrs */
> +		tpm_u16(0),			/* HMAC size */
>  		tpm_u16(0),			/* auth_size */
>
>  		/* message 14 bytes + policy */
> --
> 2.43.0
>