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tpm.c
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tpm.c
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// SPDX-License-Identifier: BSD-2-Clause-Patent
#include "shim.h"
typedef struct {
CHAR16 *VariableName;
EFI_GUID *VendorGuid;
VOID *Data;
UINTN Size;
} VARIABLE_RECORD;
UINTN measuredcount = 0;
VARIABLE_RECORD *measureddata = NULL;
static BOOLEAN tpm_present(efi_tpm_protocol_t *tpm)
{
EFI_STATUS efi_status;
TCG_EFI_BOOT_SERVICE_CAPABILITY caps;
UINT32 flags;
EFI_PHYSICAL_ADDRESS eventlog, lastevent;
caps.Size = (UINT8)sizeof(caps);
efi_status = tpm->status_check(tpm, &caps, &flags,
&eventlog, &lastevent);
if (EFI_ERROR(efi_status) ||
caps.TPMDeactivatedFlag || !caps.TPMPresentFlag)
return FALSE;
return TRUE;
}
static EFI_STATUS tpm2_get_caps(efi_tpm2_protocol_t *tpm,
EFI_TCG2_BOOT_SERVICE_CAPABILITY *caps,
BOOLEAN *old_caps)
{
EFI_STATUS efi_status;
caps->Size = (UINT8)sizeof(*caps);
efi_status = tpm->get_capability(tpm, caps);
if (EFI_ERROR(efi_status))
return efi_status;
if (caps->StructureVersion.Major == 1 &&
caps->StructureVersion.Minor == 0)
*old_caps = TRUE;
else
*old_caps = FALSE;
return EFI_SUCCESS;
}
static BOOLEAN tpm2_present(EFI_TCG2_BOOT_SERVICE_CAPABILITY *caps,
BOOLEAN old_caps)
{
TREE_BOOT_SERVICE_CAPABILITY *caps_1_0;
if (old_caps) {
caps_1_0 = (TREE_BOOT_SERVICE_CAPABILITY *)caps;
if (caps_1_0->TrEEPresentFlag)
return TRUE;
}
if (caps->TPMPresentFlag)
return TRUE;
return FALSE;
}
static EFI_STATUS tpm_locate_protocol(efi_tpm_protocol_t **tpm,
efi_tpm2_protocol_t **tpm2,
BOOLEAN *old_caps_p,
EFI_TCG2_BOOT_SERVICE_CAPABILITY *capsp)
{
EFI_STATUS efi_status;
*tpm = NULL;
*tpm2 = NULL;
efi_status = LibLocateProtocol(&EFI_TPM2_GUID, (VOID **)tpm2);
/* TPM 2.0 */
if (!EFI_ERROR(efi_status)) {
BOOLEAN old_caps;
EFI_TCG2_BOOT_SERVICE_CAPABILITY caps;
efi_status = tpm2_get_caps(*tpm2, &caps, &old_caps);
if (EFI_ERROR(efi_status))
return efi_status;
if (tpm2_present(&caps, old_caps)) {
if (old_caps_p)
*old_caps_p = old_caps;
if (capsp)
memcpy(capsp, &caps, sizeof(caps));
return EFI_SUCCESS;
}
} else {
efi_status = LibLocateProtocol(&EFI_TPM_GUID, (VOID **)tpm);
if (EFI_ERROR(efi_status))
return efi_status;
if (tpm_present(*tpm))
return EFI_SUCCESS;
}
return EFI_NOT_FOUND;
}
static EFI_STATUS tpm_log_event_raw(EFI_PHYSICAL_ADDRESS buf, UINTN size,
UINT8 pcr, const CHAR8 *log, UINTN logsize,
UINT32 type, CHAR8 *hash)
{
EFI_STATUS efi_status;
efi_tpm_protocol_t *tpm;
efi_tpm2_protocol_t *tpm2;
BOOLEAN old_caps;
EFI_TCG2_BOOT_SERVICE_CAPABILITY caps;
efi_status = tpm_locate_protocol(&tpm, &tpm2, &old_caps, &caps);
if (EFI_ERROR(efi_status)) {
#ifdef REQUIRE_TPM
perror(L"TPM logging failed: %r\n", efi_status);
return efi_status;
#else
if (efi_status != EFI_NOT_FOUND) {
perror(L"TPM logging failed: %r\n", efi_status);
return efi_status;
}
#endif
} else if (tpm2) {
EFI_TCG2_EVENT *event;
UINTN event_size = sizeof(*event) - sizeof(event->Event) +
logsize;
event = AllocatePool(event_size);
if (!event) {
perror(L"Unable to allocate event structure\n");
return EFI_OUT_OF_RESOURCES;
}
event->Header.HeaderSize = sizeof(EFI_TCG2_EVENT_HEADER);
event->Header.HeaderVersion = 1;
event->Header.PCRIndex = pcr;
event->Header.EventType = type;
event->Size = event_size;
CopyMem(event->Event, (VOID *)log, logsize);
if (hash) {
/* TPM 2 systems will generate the appropriate hash
themselves if we pass PE_COFF_IMAGE. In case that
fails we fall back to measuring without it.
*/
efi_status = tpm2->hash_log_extend_event(tpm2,
PE_COFF_IMAGE, buf, (UINT64) size, event);
}
if (!hash || EFI_ERROR(efi_status)) {
efi_status = tpm2->hash_log_extend_event(tpm2,
0, buf, (UINT64) size, event);
}
FreePool(event);
return efi_status;
} else if (tpm) {
TCG_PCR_EVENT *event;
UINT32 eventnum = 0;
EFI_PHYSICAL_ADDRESS lastevent;
efi_status = LibLocateProtocol(&EFI_TPM_GUID, (VOID **)&tpm);
if (EFI_ERROR(efi_status))
return EFI_SUCCESS;
if (!tpm_present(tpm))
return EFI_SUCCESS;
event = AllocatePool(sizeof(*event) + logsize);
if (!event) {
perror(L"Unable to allocate event structure\n");
return EFI_OUT_OF_RESOURCES;
}
event->PCRIndex = pcr;
event->EventType = type;
event->EventSize = logsize;
CopyMem(event->Event, (VOID *)log, logsize);
if (hash) {
/* TPM 1.2 devices require us to pass the Authenticode
hash rather than allowing the firmware to attempt
to calculate it */
CopyMem(event->digest, hash, sizeof(event->digest));
efi_status = tpm->log_extend_event(tpm, 0, 0,
TPM_ALG_SHA, event, &eventnum, &lastevent);
} else {
efi_status = tpm->log_extend_event(tpm, buf,
(UINT64)size, TPM_ALG_SHA, event, &eventnum,
&lastevent);
}
FreePool(event);
return efi_status;
}
return EFI_SUCCESS;
}
EFI_STATUS tpm_log_event(EFI_PHYSICAL_ADDRESS buf, UINTN size, UINT8 pcr,
const CHAR8 *description)
{
return tpm_log_event_raw(buf, size, pcr, description,
strlen(description) + 1, EV_IPL, NULL);
}
EFI_STATUS tpm_log_pe(EFI_PHYSICAL_ADDRESS buf, UINTN size,
EFI_PHYSICAL_ADDRESS addr, EFI_DEVICE_PATH *path,
UINT8 *sha1hash, UINT8 pcr)
{
EFI_IMAGE_LOAD_EVENT *ImageLoad = NULL;
EFI_STATUS efi_status;
UINTN path_size = 0;
if (path)
path_size = DevicePathSize(path);
ImageLoad = AllocateZeroPool(sizeof(*ImageLoad) + path_size);
if (!ImageLoad) {
perror(L"Unable to allocate image load event structure\n");
return EFI_OUT_OF_RESOURCES;
}
ImageLoad->ImageLocationInMemory = buf;
ImageLoad->ImageLengthInMemory = size;
ImageLoad->ImageLinkTimeAddress = addr;
if (path_size > 0) {
CopyMem(ImageLoad->DevicePath, path, path_size);
ImageLoad->LengthOfDevicePath = path_size;
}
efi_status = tpm_log_event_raw(buf, size, pcr, (CHAR8 *)ImageLoad,
sizeof(*ImageLoad) + path_size,
EV_EFI_BOOT_SERVICES_APPLICATION,
(CHAR8 *)sha1hash);
FreePool(ImageLoad);
return efi_status;
}
typedef struct {
EFI_GUID VariableName;
UINT64 UnicodeNameLength;
UINT64 VariableDataLength;
CHAR16 UnicodeName[1];
INT8 VariableData[1];
} __attribute__ ((packed)) EFI_VARIABLE_DATA_TREE;
static BOOLEAN tpm_data_measured(CHAR16 *VarName, EFI_GUID VendorGuid, UINTN VarSize, VOID *VarData)
{
UINTN i;
for (i=0; i<measuredcount; i++) {
if ((StrCmp (VarName, measureddata[i].VariableName) == 0) &&
(CompareGuid (&VendorGuid, measureddata[i].VendorGuid) == 0) &&
(VarSize == measureddata[i].Size) &&
(CompareMem (VarData, measureddata[i].Data, VarSize) == 0)) {
return TRUE;
}
}
return FALSE;
}
static EFI_STATUS tpm_record_data_measurement(CHAR16 *VarName, EFI_GUID VendorGuid, UINTN VarSize, VOID *VarData)
{
if (measureddata == NULL) {
measureddata = AllocatePool(sizeof(*measureddata));
} else {
measureddata = ReallocatePool(measureddata, measuredcount * sizeof(*measureddata),
(measuredcount + 1) * sizeof(*measureddata));
}
if (measureddata == NULL)
return EFI_OUT_OF_RESOURCES;
measureddata[measuredcount].VariableName = AllocatePool(StrSize(VarName));
measureddata[measuredcount].VendorGuid = AllocatePool(sizeof(EFI_GUID));
measureddata[measuredcount].Data = AllocatePool(VarSize);
if (measureddata[measuredcount].VariableName == NULL ||
measureddata[measuredcount].VendorGuid == NULL ||
measureddata[measuredcount].Data == NULL) {
return EFI_OUT_OF_RESOURCES;
}
StrCpy(measureddata[measuredcount].VariableName, VarName);
CopyMem(measureddata[measuredcount].VendorGuid, &VendorGuid, sizeof(EFI_GUID));
CopyMem(measureddata[measuredcount].Data, VarData, VarSize);
measureddata[measuredcount].Size = VarSize;
measuredcount++;
return EFI_SUCCESS;
}
EFI_STATUS tpm_measure_variable(CHAR16 *VarName, EFI_GUID VendorGuid, UINTN VarSize, VOID *VarData)
{
EFI_STATUS efi_status;
UINTN VarNameLength;
EFI_VARIABLE_DATA_TREE *VarLog;
UINT32 VarLogSize;
/* Don't measure something that we've already measured */
if (tpm_data_measured(VarName, VendorGuid, VarSize, VarData))
return EFI_SUCCESS;
VarNameLength = StrLen (VarName);
VarLogSize = (UINT32)(sizeof (*VarLog) +
VarNameLength * sizeof (*VarName) +
VarSize -
sizeof (VarLog->UnicodeName) -
sizeof (VarLog->VariableData));
VarLog = (EFI_VARIABLE_DATA_TREE *) AllocateZeroPool (VarLogSize);
if (VarLog == NULL) {
return EFI_OUT_OF_RESOURCES;
}
CopyMem (&VarLog->VariableName, &VendorGuid,
sizeof(VarLog->VariableName));
VarLog->UnicodeNameLength = VarNameLength;
VarLog->VariableDataLength = VarSize;
CopyMem (VarLog->UnicodeName, VarName,
VarNameLength * sizeof (*VarName));
CopyMem ((CHAR16 *)VarLog->UnicodeName + VarNameLength, VarData,
VarSize);
efi_status = tpm_log_event_raw((EFI_PHYSICAL_ADDRESS)(intptr_t)VarLog,
VarLogSize, 7, (CHAR8 *)VarLog, VarLogSize,
EV_EFI_VARIABLE_AUTHORITY, NULL);
FreePool(VarLog);
if (EFI_ERROR(efi_status))
return efi_status;
return tpm_record_data_measurement(VarName, VendorGuid, VarSize,
VarData);
}
EFI_STATUS
fallback_should_prefer_reset(void)
{
EFI_STATUS efi_status;
efi_tpm_protocol_t *tpm;
efi_tpm2_protocol_t *tpm2;
efi_status = tpm_locate_protocol(&tpm, &tpm2, NULL, NULL);
if (EFI_ERROR(efi_status))
return EFI_NOT_FOUND;
return EFI_SUCCESS;
}
#ifdef SHIM_UNIT_TEST
static void DESTRUCTOR
tpm_clean_up_measurements(void)
{
for (UINTN i = 0; i < measuredcount; i++) {
VARIABLE_RECORD *vr = &measureddata[i];
if (vr->VariableName)
FreePool(vr->VariableName);
if (vr->VendorGuid)
FreePool(vr->VendorGuid);
if (vr->Data)
FreePool(vr->Data);
}
if (measureddata)
FreePool(measureddata);
measuredcount = 0;
measureddata = NULL;
}
#endif