On Sat, Jan 23, 2021 at 10:26:07AM -0700, Simon Glass wrote:
> With TPM2 we don't actually lock the TPM once verified boot is finished.
> Instead we disable the platform hierarchy which serves the same purpose.
> Add an implementation of this so we can safely boot into the kernel.
>
> Signed-off-by: Simon Glass <s...@chromium.org>
> ---
>
> (no changes since v2)
>
> Changes in v2:
> - Add definition of TPM2_RC_NV_DEFINED return code
>
> include/tpm-v2.h | 13 +++++++++++++
> lib/tpm-v2.c | 35 +++++++++++++++++++++++++++++++++++
> 2 files changed, 48 insertions(+)
>
> diff --git a/include/tpm-v2.h b/include/tpm-v2.h
> index 1ca1e7e2011..e18c8b1ccca 100644
> --- a/include/tpm-v2.h
> +++ b/include/tpm-v2.h
> @@ -235,6 +235,7 @@ enum tpm2_handles {
> enum tpm2_command_codes {
> TPM2_CC_STARTUP = 0x0144,
> TPM2_CC_SELF_TEST = 0x0143,
> + TPM2_CC_HIER_CONTROL = 0x0121,
> TPM2_CC_CLEAR = 0x0126,
> TPM2_CC_CLEARCONTROL = 0x0127,
> TPM2_CC_HIERCHANGEAUTH = 0x0129,
> @@ -272,6 +273,7 @@ enum tpm2_return_codes {
> TPM2_RC_COMMAND_CODE = TPM2_RC_VER1 + 0x0043,
> TPM2_RC_AUTHSIZE = TPM2_RC_VER1 + 0x0044,
> TPM2_RC_AUTH_CONTEXT = TPM2_RC_VER1 + 0x0045,
> + TPM2_RC_NV_DEFINED = TPM2_RC_VER1 + 0x004c,
> TPM2_RC_NEEDS_TEST = TPM2_RC_VER1 + 0x0053,
> TPM2_RC_WARN = 0x0900,
> TPM2_RC_TESTING = TPM2_RC_WARN + 0x000A,
> @@ -582,4 +584,15 @@ u32 tpm2_get_random(struct udevice *dev, void *data, u32
> count);
> */
> u32 tpm2_write_lock(struct udevice *dev, u32 index);
>
> +/**
> + * Disable access to any platform data
> + *
> + * This can be called to close off access to the firmware data in the data,
> + * before calling the kernel.
> + *
> + * @dev TPM device
> + * @return code of the operation
> + */
> +u32 tpm2_disable_platform_hierarchy(struct udevice *dev);
> +
> #endif /* __TPM_V2_H */
> diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
> index 35f3917aeb5..1b32661979d 100644
> --- a/lib/tpm-v2.c
> +++ b/lib/tpm-v2.c
> @@ -625,3 +625,38 @@ u32 tpm2_write_lock(struct udevice *dev, u32 index)
>
> return tpm_sendrecv_command(dev, command_v2, NULL, NULL);
> }
> +
> +u32 tpm2_disable_platform_hierarchy(struct udevice *dev)
> +{
> + struct tpm_chip_priv *priv = dev_get_uclass_priv(dev);
> + u8 command_v2[COMMAND_BUFFER_SIZE] = {
> + /* header 10 bytes */
> + tpm_u16(TPM2_ST_SESSIONS), /* TAG */
> + tpm_u32(10 + 4 + 13 + 5), /* Length */
> + tpm_u32(TPM2_CC_HIER_CONTROL), /* Command code */
> +
> + /* 4 bytes */
> + tpm_u32(TPM2_RH_PLATFORM), /* Primary platform seed */
> +
> + /* session header 9 bytes */
> + tpm_u32(9), /* Header size */
> + tpm_u32(TPM2_RS_PW), /* Password authorisation */
> + tpm_u16(0), /* nonce_size */
> + 0, /* session_attrs */
> + tpm_u16(0), /* auth_size */
> +
> + /* payload 5 bytes */
> + tpm_u32(TPM2_RH_PLATFORM), /* Hierarchy to disable */
> + 0, /* 0=disable */
> + };
> + int ret;
> +
> + ret = tpm_sendrecv_command(dev, command_v2, NULL, NULL);
> + log_info("ret=%s, %x\n", dev->name, ret);
> + if (ret)
> + return ret;
> +
> + priv->plat_hier_disabled = true;
> +
> + return 0;
> +}
> --
> 2.30.0.280.ga3ce27912f-goog
>
Acked-by: Ilias Apalodimas <ilias.apalodi...@linaro.org>
