[PATCH v2] tpm: Allow committing non-volatile data
Ilias Apalodimas
ilias.apalodimas at linaro.org
Tue Feb 21 14:58:38 CET 2023
Hi Simon,
On Mon, Feb 20, 2023 at 09:31:24AM -0700, Simon Glass wrote:
> Add an option to tell the TPM to commit non-volatile data immediately it
> is changed, rather than waiting until later. This is needed in some
> situations, since if the device reboots it may not write the data.
>
> Add definitions for the rest of the Cr50 commands while we are here.
This defines a function that's unused. IIRC you said U-Boot doesn't use it,
but some code that run for that laptop does right?
In any case the function declaration doesn't belong to the TPMv2 library.
I think we are better off adding it to the cr50 driver itself. I also
assume you compile u-boot in a 'special' way so the linker doesn't get rid
of the emitted code? Does t hat mean we can define it as __unused as well?
Thanks
/Ilias
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
> I am resending this as I think it got lost.
>
> Changes in v2:
> - Rebase to master
>
> include/tpm-v2.h | 14 ++++++++++++++
> lib/tpm-v2.c | 20 ++++++++++++++++++++
> 2 files changed, 34 insertions(+)
>
> diff --git a/include/tpm-v2.h b/include/tpm-v2.h
> index 8e90a616220..0a03994740d 100644
> --- a/include/tpm-v2.h
> +++ b/include/tpm-v2.h
> @@ -712,4 +712,18 @@ u32 tpm2_submit_command(struct udevice *dev, const u8 *sendbuf,
> */
> u32 tpm2_cr50_report_state(struct udevice *dev, u8 *recvbuf, size_t *recv_size);
>
> +/*
> + * tpm2_cr50_enable_nvcommits() - Tell Cr50 to commit NV data immediately
> + *
> + * For Chromium OS verified boot, we may reboot or reset at different times,
> + * possibly leaving non-volatile data unwritten by the TPM.
> + *
> + * This vendor command is used to indicate that non-volatile data should be
> + * written to its store immediately.
> + *
> + * @dev TPM device
> + * Return: result of the operation
> + */
> +u32 tpm2_cr50_enable_nvcommits(struct udevice *dev);
> +
> #endif /* __TPM_V2_H */
> diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
> index bdf019b0f93..5fcd3649b74 100644
> --- a/lib/tpm-v2.c
> +++ b/lib/tpm-v2.c
> @@ -699,3 +699,23 @@ u32 tpm2_cr50_report_state(struct udevice *dev, u8 *recvbuf, size_t *recv_size)
>
> return 0;
> }
> +
> +u32 tpm2_cr50_enable_nvcommits(struct udevice *dev)
> +{
> + u8 command_v2[COMMAND_BUFFER_SIZE] = {
> + /* header 10 bytes */
> + tpm_u16(TPM2_ST_NO_SESSIONS), /* TAG */
> + tpm_u32(10 + 2), /* Length */
> + tpm_u32(TPM2_CR50_VENDOR_COMMAND), /* Command code */
> +
> + tpm_u16(TPM2_CR50_SUB_CMD_NVMEM_ENABLE_COMMITS),
> + };
> + int ret;
> +
> + ret = tpm_sendrecv_command(dev, command_v2, NULL, NULL);
> + log_debug("ret=%s, %x\n", dev->name, ret);
> + if (ret)
> + return ret;
> +
> + return 0;
> +}
> --
> 2.39.2.637.g21b0678d19-goog
>
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