Hi Ilias,
On Tue, 7 Jun 2022 at 02:42, Ilias Apalodimas
<ilias.apalodi...@linaro.org> wrote:
>
> On Mon, Feb 28, 2022 at 05:11:19PM -0700, Simon Glass wrote:
> > This feature is used for measured boot. It is not currently supported in
> > the TPM drivers, but add it to the API so that code which expects it can
> > signal its request.
> >
> > Signed-off-by: Simon Glass <s...@chromium.org>
> > ---
> >
> > cmd/tpm-v1.c | 3 ++-
> > cmd/tpm_test.c | 5 +++--
> > include/tpm_api.h | 8 +++++---
> > lib/tpm-v2.c | 2 ++
> > lib/tpm_api.c | 14 ++++++++++----
> > 5 files changed, 22 insertions(+), 10 deletions(-)
(long pause as I forgot about this and only just discovered it was not applied)
> >
> > diff --git a/cmd/tpm-v1.c b/cmd/tpm-v1.c
> > index bf238a9f2e..0869b70775 100644
> > --- a/cmd/tpm-v1.c
> > +++ b/cmd/tpm-v1.c
> > @@ -131,7 +131,8 @@ static int do_tpm_extend(struct cmd_tbl *cmdtp, int
> > flag, int argc,
> > return CMD_RET_FAILURE;
> > }
> >
> > - rc = tpm_pcr_extend(dev, index, in_digest, out_digest);
> > + rc = tpm_pcr_extend(dev, index, in_digest, sizeof(in_digest),
> > + out_digest, "test");
>
> Where is the output value of an extended PCR needed in measured boot?
> IMHO this out_digest seems pointless. I'd be happier if we just completely
> removed it and make the v2 variant look like v1 more.
It is used by the tpm command to display the digest value.
>
> > if (!rc) {
> > puts("PCR value after execution of the command:\n");
> > print_byte_string(out_digest, sizeof(out_digest));
> > diff --git a/cmd/tpm_test.c b/cmd/tpm_test.c
> > index a3ccb12f53..b35eae81dc 100644
> > --- a/cmd/tpm_test.c
> > +++ b/cmd/tpm_test.c
> > @@ -91,7 +91,8 @@ static int test_early_extend(struct udevice *dev)
> > tpm_init(dev);
> > TPM_CHECK(tpm_startup(dev, TPM_ST_CLEAR));
> > TPM_CHECK(tpm_continue_self_test(dev));
> > - TPM_CHECK(tpm_pcr_extend(dev, 1, value_in, value_out));
> > + TPM_CHECK(tpm_pcr_extend(dev, 1, value_in, sizeof(value_in),
> > value_out,
> > + "test"));
> > printf("done\n");
> > return 0;
> > }
> > @@ -438,7 +439,7 @@ static int test_timing(struct udevice *dev)
> > 100);
> > TTPM_CHECK(tpm_nv_read_value(dev, INDEX0, (uint8_t *)&x, sizeof(x)),
> > 100);
> > - TTPM_CHECK(tpm_pcr_extend(dev, 0, in, out), 200);
> > + TTPM_CHECK(tpm_pcr_extend(dev, 0, in, sizeof(in), out, "test"), 200);
> > TTPM_CHECK(tpm_set_global_lock(dev), 50);
> > TTPM_CHECK(tpm_tsc_physical_presence(dev, PHYS_PRESENCE), 100);
> > printf("done\n");
> > diff --git a/include/tpm_api.h b/include/tpm_api.h
> > index 11aa14eb79..3c8e48bc25 100644
> > --- a/include/tpm_api.h
> > +++ b/include/tpm_api.h
> > @@ -81,14 +81,16 @@ u32 tpm_nv_write_value(struct udevice *dev, u32 index,
> > const void *data,
> > *
> > * @param dev TPM device
> > * @param index index of the PCR
> > - * @param in_digest 160-bit value representing the event to be
> > + * @param in_digest 160/256-bit value representing the event to be
> > * recorded
> > - * @param out_digest 160-bit PCR value after execution of the
> > + * @param size size of digest in bytes
> > + * @param out_digest 160/256-bit PCR value after execution of the
> > * command
> > + * @param name additional info about where the digest comes
> > from
> > * Return: return code of the operation
> > */
> > u32 tpm_pcr_extend(struct udevice *dev, u32 index, const void *in_digest,
> > - void *out_digest);
> > + uint size, void *out_digest, const char *name);
> >
> > /**
> > * Issue a TPM_PCRRead command.
> > diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
> > index 1bf627853a..6058f2e1e4 100644
> > --- a/lib/tpm-v2.c
> > +++ b/lib/tpm-v2.c
> > @@ -157,6 +157,8 @@ u32 tpm2_pcr_extend(struct udevice *dev, u32 index, u32
> > algorithm,
> > };
> > int ret;
> >
> > + if (!digest)
> > + return -EINVAL;
> > /*
> > * Fill the command structure starting from the first buffer:
> > * - the digest
> > diff --git a/lib/tpm_api.c b/lib/tpm_api.c
> > index 4ac4612c81..a8d3731d3a 100644
> > --- a/lib/tpm_api.c
> > +++ b/lib/tpm_api.c
> > @@ -140,15 +140,21 @@ u32 tpm_write_lock(struct udevice *dev, u32 index)
> > }
> >
> > u32 tpm_pcr_extend(struct udevice *dev, u32 index, const void *in_digest,
> > - void *out_digest)
> > + uint size, void *out_digest, const char *name)
> > {
> > - if (tpm_is_v1(dev))
> > + if (tpm_is_v1(dev)) {
> > + if (size != PCR_DIGEST_LENGTH || !out_digest)
> > + return -EINVAL;
> > return tpm1_extend(dev, index, in_digest, out_digest);
> > - else if (tpm_is_v2(dev))
> > + } else if (tpm_is_v2(dev)) {
> > + if (size != TPM2_SHA256_DIGEST_SIZE)
> > + return -EINVAL;
>
> Why are we limiting this? This is supposed to be dictated by the PCR bank
> configuration of each hardware
OK I can drop this. Normally we use SHA256 for TPMv2 and I'm not sure
we suppose anything else. But we don't have to....
>
> > return tpm2_pcr_extend(dev, index, TPM2_ALG_SHA256, in_digest,
> > TPM2_DIGEST_LEN);
> > - else
> > + /* @name is ignored as we do not support measured boot */
> > + } else {
> > return -ENOSYS;
> > + }
> > }
> >
> > u32 tpm_pcr_read(struct udevice *dev, u32 index, void *data, size_t count)
> > --
> > 2.35.1.574.g5d30c73bfb-goog
Regards,
Simon
