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

[Ilias Apalodimas]

Hi Alex,

++ CC Niek who originally authored this

On Thu, 20 Feb 2025 at 10:27, Ilias Apalodimas
<ilias.apalodimas at linaro.org> wrote:
>
> Hi Michel,
>
> On Thu, 20 Feb 2025 at 09:14, Michel Alex
> <Alex.Michel at wiedemann-group.com> wrote:
> >
> > Hi Ilias,
> >
> > I don't know where to find the spec for the tpm v2 nv_define command. I was just wondering
> > why this command does not work in u-boot. Then I found a patch, that has never been
> > applied to the master, see https://lists.denx.de/pipermail/u-boot/2023-December/542089.html,
>
> Yes, that patch was useful but unfortunately, it didn't apply to
> -master cleanly and I haven't seen an updated revision since.
> I'll have a look at the tpm specs and figure out why this change is
> working and let you know. You can then send a v2 with a commit message
> that explains why
>
> Thanks
> /Ilias
>
> > where the nv_define's message buf was "fixed". I tried this change and the nv_define command
> > is working now.
> >
> > Alex
> >
> > > -----Original Message-----
> > > From: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> > > Sent: Tuesday, February 18, 2025 8:38 AM
> > > To: Michel Alex <Alex.Michel at wiedemann-group.com>
> > > Cc: u-boot at lists.denx.de
> > > Subject: Re: [PATCH 1/1] tpm: fixed the nv_define_space command in TPMv2
> > >
> > > Vorsicht: Es handelt sich um eine externe E-Mail vom Absender Ilias
> > > Apalodimas <ilias.apalodimas at linaro.org>. Bitte klicken Sie nicht auf Links oder
> > > Anhänge, solange Sie nicht von der Echtheit der Nachricht überzeugt sind.
> > >
> > > 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 at 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 */

So looking at this again, and the spec -- we are using a password auth
just above. So the HMAC shouldn't be needed. Any chance this is the
TPM2B_AUTH filed we add and it somehow fixes your issue?

Cheers
/Ilias
> > > >             tpm_u16(0),                     /* auth_size */
> > > >
> > > >             /* message 14 bytes + policy */
> > > > --
> > > > 2.43.0
> > > >