> On 8 Jul 2025, at 2:01 PM, Gary Lin via Grub-devel <[email protected]> wrote:
>
> The TPM2_PCR_Event command is introduced to tss2 to allow the user to
> extend a specific PCR. The related data structure and unmarshal function
> are also introduced.
>
> However, simply invoking TPM2_PCR_Event does not automatically record
> the event into the TPM event log. The TPM event log is primarily
> maintained by the system firmware (e.g., BIOS/UEFI). Therefore, for most
> standard use cases, the recommended method for extending PCRs and
> ensuring proper event logging is to utilize the system firmware
> functions.
>
> There are specific scenarios where direct use of TPM2_PCR_Event becomes
> necessary. For instance, in environments lacking system firmware support
> for PCR extension, such as the grub-emu, TPM2_PCR_Event serves as the
> only available method to extend PCRs.
>
> Signed-off-by: Gary Lin <[email protected]>
> ---
> grub-core/lib/tss2/tpm2_cmd.c | 51 +++++++++++++++++++++++++++++++
> grub-core/lib/tss2/tpm2_cmd.h | 7 +++++
> grub-core/lib/tss2/tss2_mu.c | 18 +++++++++++
> grub-core/lib/tss2/tss2_mu.h | 4 +++
> grub-core/lib/tss2/tss2_structs.h | 7 +++++
> grub-core/lib/tss2/tss2_types.h | 1 +
> 6 files changed, 88 insertions(+)
>
> diff --git a/grub-core/lib/tss2/tpm2_cmd.c b/grub-core/lib/tss2/tpm2_cmd.c
> index 6d25db1ab..37ca78aee 100644
> --- a/grub-core/lib/tss2/tpm2_cmd.c
> +++ b/grub-core/lib/tss2/tpm2_cmd.c
> @@ -575,6 +575,57 @@ grub_tpm2_flushcontext (const TPMI_DH_CONTEXT_t handle)
> return TPM_RC_SUCCESS;
> }
>
> +extern TPM_RC_t
Do you think the extern keyword is required for function definition as well?
> +grub_tpm2_pcr_event (const TPMI_DH_PCR_t pcrHandle,
> + const TPMS_AUTH_COMMAND_t *authCommand,
> + const TPM2B_EVENT_t *eventData,
> + TPML_DIGEST_VALUES_t *digests,
> + TPMS_AUTH_RESPONSE_t *authResponse)
> +{
> + TPM_RC_t rc;
> + struct grub_tpm2_buffer in;
> + struct grub_tpm2_buffer out;
> + TPML_DIGEST_VALUES_t digestsTmp;
> + TPMS_AUTH_RESPONSE_t authResponseTmp;
> + TPM_RC_t responseCode;
> + grub_uint32_t parameterSize;
> +
> + if (eventData == NULL)
> + return TPM_RC_VALUE;
> + if (authCommand == NULL)
> + return TPM_RC_VALUE;
> +
> + if (digests == NULL)
> + digests = &digestsTmp;
> + if (authResponse == NULL)
> + authResponse = &authResponseTmp;
> +
> + /* Marshal */
> + grub_tpm2_buffer_init (&in);
> + grub_tpm2_buffer_pack_u32 (&in, pcrHandle);
> + grub_Tss2_MU_TPMS_AUTH_COMMAND_Marshal (&in, authCommand);
> + grub_Tss2_MU_TPM2B_Marshal (&in, eventData->size, eventData->buffer);
> + if (in.error != 0)
It would be better to use true/false for boolean.
if (in.error == true)
> + return TPM_RC_FAILURE;
> +
> + /* Submit */
> + grub_tpm2_buffer_init (&out);
> + rc = tpm2_submit_command (TPM_ST_SESSIONS, TPM_CC_PCR_Event,
> &responseCode, &in, &out);
> + if (rc != TPM_RC_SUCCESS)
> + return rc;
> + if (responseCode != TPM_RC_SUCCESS)
> + return responseCode;
> +
> + /* Unmarshal */
> + grub_tpm2_buffer_unpack_u32 (&out, ¶meterSize);
> + grub_Tss2_MU_TPML_DIGEST_VALUE_Unmarshal (&out, digests);
> + grub_Tss2_MU_TPMS_AUTH_RESPONSE_Unmarshal (&out, authResponse);
> + if (out.error != 0)
It would be better to use true/false for boolean.
if (out.error == true)
> + return TPM_RC_FAILURE;
> +
> + return TPM_RC_SUCCESS;
> +}
> +
> TPM_RC_t
> grub_tpm2_pcr_read (const TPMS_AUTH_COMMAND_t *authCommand,
> const TPML_PCR_SELECTION_t *pcrSelectionIn,
> diff --git a/grub-core/lib/tss2/tpm2_cmd.h b/grub-core/lib/tss2/tpm2_cmd.h
> index 90b42efec..d7ad962ab 100644
> --- a/grub-core/lib/tss2/tpm2_cmd.h
> +++ b/grub-core/lib/tss2/tpm2_cmd.h
> @@ -89,6 +89,13 @@ grub_tpm2_unseal (const TPMI_DH_OBJECT_t item_handle,
> extern TPM_RC_t
> grub_tpm2_flushcontext (const TPMI_DH_CONTEXT_t handle);
>
> +extern TPM_RC_t
> +grub_tpm2_pcr_event (const TPMI_DH_PCR_t pcrHandle,
> + const TPMS_AUTH_COMMAND_t *authCommand,
> + const TPM2B_EVENT_t *eventData,
> + TPML_DIGEST_VALUES_t *digests,
> + TPMS_AUTH_RESPONSE_t *authResponse);
> +
> extern TPM_RC_t
> grub_tpm2_pcr_read (const TPMS_AUTH_COMMAND_t *authCommand,
> const TPML_PCR_SELECTION_t *pcrSelectionIn,
> diff --git a/grub-core/lib/tss2/tss2_mu.c b/grub-core/lib/tss2/tss2_mu.c
> index 816e5b37f..675a0009a 100644
> --- a/grub-core/lib/tss2/tss2_mu.c
> +++ b/grub-core/lib/tss2/tss2_mu.c
> @@ -1118,6 +1118,24 @@ grub_Tss2_MU_TPML_DIGEST_Unmarshal (grub_tpm2_buffer_t
> buffer,
> grub_Tss2_MU_TPM2B_DIGEST_Unmarshal (buffer, &digest->digests[i]);
> }
>
> +void
> +grub_Tss2_MU_TPML_DIGEST_VALUE_Unmarshal (grub_tpm2_buffer_t buffer,
> + TPML_DIGEST_VALUES_t *digests)
> +{
> + grub_uint32_t i;
> +
> + grub_tpm2_buffer_unpack_u32 (buffer, &digests->count);
> +
> + if (digests->count > TPM_NUM_PCR_BANKS)
> + {
> + buffer->error = 1;
It would be better to use true/false for boolean.
buffer->error = true;
Thanks,
Sudhakar
> + return;
> + }
> +
> + for (i = 0; i < digests->count; i++)
> + grub_Tss2_MU_TPMT_HA_Unmarshal (buffer, &digests->digests[i]);
> +}
> +
> void
> grub_Tss2_MU_TPMS_SIGNATURE_RSA_Unmarshal (grub_tpm2_buffer_t buffer,
> TPMS_SIGNATURE_RSA_t *rsa)
> diff --git a/grub-core/lib/tss2/tss2_mu.h b/grub-core/lib/tss2/tss2_mu.h
> index 6440de57c..76eebc994 100644
> --- a/grub-core/lib/tss2/tss2_mu.h
> +++ b/grub-core/lib/tss2/tss2_mu.h
> @@ -380,6 +380,10 @@ extern void
> grub_Tss2_MU_TPML_DIGEST_Unmarshal (grub_tpm2_buffer_t buffer,
> TPML_DIGEST_t *digest);
>
> +extern void
> +grub_Tss2_MU_TPML_DIGEST_VALUE_Unmarshal (grub_tpm2_buffer_t buffer,
> + TPML_DIGEST_VALUES_t *digests);
> +
> extern void
> grub_Tss2_MU_TPMS_SIGNATURE_RSA_Unmarshal (grub_tpm2_buffer_t buffer,
> TPMS_SIGNATURE_RSA_t *p);
> diff --git a/grub-core/lib/tss2/tss2_structs.h
> b/grub-core/lib/tss2/tss2_structs.h
> index 2eefba87c..0ac09f50f 100644
> --- a/grub-core/lib/tss2/tss2_structs.h
> +++ b/grub-core/lib/tss2/tss2_structs.h
> @@ -144,6 +144,13 @@ typedef struct TPML_DIGEST TPML_DIGEST_t;
> /* TPM2B_NONCE Type */
> typedef TPM2B_DIGEST_t TPM2B_NONCE_t;
>
> +/* TPM2B_EVENT Structure */
> +struct TPM2B_EVENT {
> + grub_uint16_t size;
> + grub_uint8_t buffer[1024];
> +};
> +typedef struct TPM2B_EVENT TPM2B_EVENT_t;
> +
> /* TPMA_SESSION Structure */
> struct TPMA_SESSION
> {
> diff --git a/grub-core/lib/tss2/tss2_types.h b/grub-core/lib/tss2/tss2_types.h
> index bddde7191..52d304b90 100644
> --- a/grub-core/lib/tss2/tss2_types.h
> +++ b/grub-core/lib/tss2/tss2_types.h
> @@ -343,6 +343,7 @@ typedef grub_uint32_t TPM_CC_t;
> #define TPM_CC_NV_Write ((TPM_CC_t) 0x00000137)
> #define TPM_CC_NV_UndefineSpace ((TPM_CC_t) 0x00000122)
> #define TPM_CC_GetCapability ((TPM_CC_t) 0x0000017a)
> +#define TPM_CC_PCR_Event ((TPM_CC_t) 0x0000013c)
> #define TPM_CC_PCR_Read ((TPM_CC_t) 0x0000017e)
> #define TPM_CC_Load ((TPM_CC_t) 0x00000157)
> #define TPM_CC_LoadExternal ((TPM_CC_t) 0x00000167)
> --
> 2.43.0
>
>
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