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audk/SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c

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/** @file
Implement image verification services for secure boot service in UEFI2.3.1.
Copyright (c) 2009 - 2011, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
#include "DxeImageVerificationLib.h"
EFI_IMAGE_OPTIONAL_HEADER_PTR_UNION mNtHeader;
UINTN mImageSize;
UINT32 mPeCoffHeaderOffset;
UINT8 mImageDigest[MAX_DIGEST_SIZE];
UINTN mImageDigestSize;
EFI_IMAGE_DATA_DIRECTORY *mSecDataDir = NULL;
UINT8 *mImageBase = NULL;
EFI_GUID mCertType;
//
// Notify string for authorization UI.
//
CHAR16 mNotifyString1[MAX_NOTIFY_STRING_LEN] = L"Image verification pass but not found in authorized database!";
CHAR16 mNotifyString2[MAX_NOTIFY_STRING_LEN] = L"Launch this image anyway? (Yes/Defer/No)";
//
// Public Exponent of RSA Key.
//
CONST UINT8 mRsaE[] = { 0x01, 0x00, 0x01 };
//
// OID ASN.1 Value for Hash Algorithms
//
UINT8 mHashOidValue[] = {
0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x02, 0x05, // OBJ_md5
0x2B, 0x0E, 0x03, 0x02, 0x1A, // OBJ_sha1
0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04, // OBJ_sha224
0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, // OBJ_sha256
0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02, // OBJ_sha384
0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, // OBJ_sha512
};
HASH_TABLE mHash[] = {
{ L"SHA1", 20, &mHashOidValue[8], 5, Sha1GetContextSize, Sha1Init, Sha1Update, Sha1Final },
{ L"SHA224", 28, &mHashOidValue[13], 9, NULL, NULL, NULL, NULL },
{ L"SHA256", 32, &mHashOidValue[22], 9, Sha256GetContextSize,Sha256Init, Sha256Update, Sha256Final},
{ L"SHA384", 48, &mHashOidValue[31], 9, NULL, NULL, NULL, NULL },
{ L"SHA512", 64, &mHashOidValue[40], 9, NULL, NULL, NULL, NULL }
};
/**
Get the image type.
@param[in] File This is a pointer to the device path of the file that is
being dispatched.
@return UINT32 Image Type
**/
UINT32
GetImageType (
IN CONST EFI_DEVICE_PATH_PROTOCOL *File
)
{
EFI_STATUS Status;
EFI_HANDLE DeviceHandle;
EFI_DEVICE_PATH_PROTOCOL *TempDevicePath;
EFI_BLOCK_IO_PROTOCOL *BlockIo;
//
// First check to see if File is from a Firmware Volume
//
DeviceHandle = NULL;
TempDevicePath = (EFI_DEVICE_PATH_PROTOCOL *) File;
Status = gBS->LocateDevicePath (
&gEfiFirmwareVolume2ProtocolGuid,
&TempDevicePath,
&DeviceHandle
);
if (!EFI_ERROR (Status)) {
Status = gBS->OpenProtocol (
DeviceHandle,
&gEfiFirmwareVolume2ProtocolGuid,
NULL,
NULL,
NULL,
EFI_OPEN_PROTOCOL_TEST_PROTOCOL
);
if (!EFI_ERROR (Status)) {
return IMAGE_FROM_FV;
}
}
//
// Next check to see if File is from a Block I/O device
//
DeviceHandle = NULL;
TempDevicePath = (EFI_DEVICE_PATH_PROTOCOL *) File;
Status = gBS->LocateDevicePath (
&gEfiBlockIoProtocolGuid,
&TempDevicePath,
&DeviceHandle
);
if (!EFI_ERROR (Status)) {
BlockIo = NULL;
Status = gBS->OpenProtocol (
DeviceHandle,
&gEfiBlockIoProtocolGuid,
(VOID **) &BlockIo,
NULL,
NULL,
EFI_OPEN_PROTOCOL_GET_PROTOCOL
);
if (!EFI_ERROR (Status) && BlockIo != NULL) {
if (BlockIo->Media != NULL) {
if (BlockIo->Media->RemovableMedia) {
//
// Block I/O is present and specifies the media is removable
//
return IMAGE_FROM_REMOVABLE_MEDIA;
} else {
//
// Block I/O is present and specifies the media is not removable
//
return IMAGE_FROM_FIXED_MEDIA;
}
}
}
}
//
// File is not in a Firmware Volume or on a Block I/O device, so check to see if
// the device path supports the Simple File System Protocol.
//
DeviceHandle = NULL;
TempDevicePath = (EFI_DEVICE_PATH_PROTOCOL *) File;
Status = gBS->LocateDevicePath (
&gEfiSimpleFileSystemProtocolGuid,
&TempDevicePath,
&DeviceHandle
);
if (!EFI_ERROR (Status)) {
//
// Simple File System is present without Block I/O, so assume media is fixed.
//
return IMAGE_FROM_FIXED_MEDIA;
}
//
// File is not from an FV, Block I/O or Simple File System, so the only options
// left are a PCI Option ROM and a Load File Protocol such as a PXE Boot from a NIC.
//
TempDevicePath = (EFI_DEVICE_PATH_PROTOCOL *) File;
while (!IsDevicePathEndType (TempDevicePath)) {
switch (DevicePathType (TempDevicePath)) {
case MEDIA_DEVICE_PATH:
if (DevicePathSubType (TempDevicePath) == MEDIA_RELATIVE_OFFSET_RANGE_DP) {
return IMAGE_FROM_OPTION_ROM;
}
break;
case MESSAGING_DEVICE_PATH:
if (DevicePathSubType(TempDevicePath) == MSG_MAC_ADDR_DP) {
return IMAGE_FROM_REMOVABLE_MEDIA;
}
break;
default:
break;
}
TempDevicePath = NextDevicePathNode (TempDevicePath);
}
return IMAGE_UNKNOWN;
}
/**
Caculate hash of Pe/Coff image based on the authenticode image hashing in
PE/COFF Specification 8.0 Appendix A
@param[in] HashAlg Hash algorithm type.
@retval TRUE Successfully hash image.
@retval FALSE Fail in hash image.
**/
BOOLEAN
HashPeImage (
IN UINT32 HashAlg
)
{
BOOLEAN Status;
UINT16 Magic;
EFI_IMAGE_SECTION_HEADER *Section;
VOID *HashCtx;
UINTN CtxSize;
UINT8 *HashBase;
UINTN HashSize;
UINTN SumOfBytesHashed;
EFI_IMAGE_SECTION_HEADER *SectionHeader;
UINTN Index;
UINTN Pos;
UINTN SumOfSectionBytes;
EFI_IMAGE_SECTION_HEADER *SectionCache;
HashCtx = NULL;
SectionHeader = NULL;
Status = FALSE;
if ((HashAlg != HASHALG_SHA1) && (HashAlg != HASHALG_SHA256)) {
return FALSE;
}
//
// Initialize context of hash.
//
ZeroMem (mImageDigest, MAX_DIGEST_SIZE);
if (HashAlg == HASHALG_SHA1) {
mImageDigestSize = SHA1_DIGEST_SIZE;
mCertType = gEfiCertSha1Guid;
} else if (HashAlg == HASHALG_SHA256) {
mImageDigestSize = SHA256_DIGEST_SIZE;
mCertType = gEfiCertSha256Guid;
} else {
return FALSE;
}
CtxSize = mHash[HashAlg].GetContextSize();
HashCtx = AllocatePool (CtxSize);
if (HashCtx == NULL) {
return FALSE;
}
// 1. Load the image header into memory.
// 2. Initialize a SHA hash context.
Status = mHash[HashAlg].HashInit(HashCtx);
if (!Status) {
goto Done;
}
//
// Measuring PE/COFF Image Header;
// But CheckSum field and SECURITY data directory (certificate) are excluded
//
Magic = mNtHeader.Pe32->OptionalHeader.Magic;
//
// 3. Calculate the distance from the base of the image header to the image checksum address.
// 4. Hash the image header from its base to beginning of the image checksum.
//
HashBase = mImageBase;
if (Magic == EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
//
// Use PE32 offset.
//
HashSize = (UINTN) ((UINT8 *) (&mNtHeader.Pe32->OptionalHeader.CheckSum) - HashBase);
} else if (Magic == EFI_IMAGE_NT_OPTIONAL_HDR64_MAGIC) {
//
// Use PE32+ offset.
//
HashSize = (UINTN) ((UINT8 *) (&mNtHeader.Pe32Plus->OptionalHeader.CheckSum) - HashBase);
} else {
//
// Invalid header magic number.
//
Status = FALSE;
goto Done;
}
Status = mHash[HashAlg].HashUpdate(HashCtx, HashBase, HashSize);
if (!Status) {
goto Done;
}
//
// 5. Skip over the image checksum (it occupies a single ULONG).
// 6. Get the address of the beginning of the Cert Directory.
// 7. Hash everything from the end of the checksum to the start of the Cert Directory.
//
if (Magic == EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
//
// Use PE32 offset.
//
HashBase = (UINT8 *) &mNtHeader.Pe32->OptionalHeader.CheckSum + sizeof (UINT32);
HashSize = (UINTN) ((UINT8 *) (&mNtHeader.Pe32->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY]) - HashBase);
} else {
//
// Use PE32+ offset.
//
HashBase = (UINT8 *) &mNtHeader.Pe32Plus->OptionalHeader.CheckSum + sizeof (UINT32);
HashSize = (UINTN) ((UINT8 *) (&mNtHeader.Pe32Plus->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY]) - HashBase);
}
Status = mHash[HashAlg].HashUpdate(HashCtx, HashBase, HashSize);
if (!Status) {
goto Done;
}
//
// 8. Skip over the Cert Directory. (It is sizeof(IMAGE_DATA_DIRECTORY) bytes.)
// 9. Hash everything from the end of the Cert Directory to the end of image header.
//
if (Magic == EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
//
// Use PE32 offset
//
HashBase = (UINT8 *) &mNtHeader.Pe32->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY + 1];
HashSize = mNtHeader.Pe32->OptionalHeader.SizeOfHeaders - (UINTN) ((UINT8 *) (&mNtHeader.Pe32->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY + 1]) - mImageBase);
} else {
//
// Use PE32+ offset.
//
HashBase = (UINT8 *) &mNtHeader.Pe32Plus->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY + 1];
HashSize = mNtHeader.Pe32Plus->OptionalHeader.SizeOfHeaders - (UINTN) ((UINT8 *) (&mNtHeader.Pe32Plus->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY + 1]) - mImageBase);
}
Status = mHash[HashAlg].HashUpdate(HashCtx, HashBase, HashSize);
if (!Status) {
goto Done;
}
//
// 10. Set the SUM_OF_BYTES_HASHED to the size of the header.
//
if (Magic == EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
//
// Use PE32 offset.
//
SumOfBytesHashed = mNtHeader.Pe32->OptionalHeader.SizeOfHeaders;
} else {
//
// Use PE32+ offset
//
SumOfBytesHashed = mNtHeader.Pe32Plus->OptionalHeader.SizeOfHeaders;
}
Section = (EFI_IMAGE_SECTION_HEADER *) (
mImageBase +
mPeCoffHeaderOffset +
sizeof (UINT32) +
sizeof (EFI_IMAGE_FILE_HEADER) +
mNtHeader.Pe32->FileHeader.SizeOfOptionalHeader
);
SectionCache = Section;
for (Index = 0, SumOfSectionBytes = 0; Index < mNtHeader.Pe32->FileHeader.NumberOfSections; Index++, SectionCache++) {
SumOfSectionBytes += SectionCache->SizeOfRawData;
}
//
// Sanity check for file corruption. Sections raw data size should be smaller
// than Image Size.
//
if (SumOfSectionBytes >= mImageSize) {
Status = FALSE;
goto Done;
}
//
// 11. Build a temporary table of pointers to all the IMAGE_SECTION_HEADER
// structures in the image. The 'NumberOfSections' field of the image
// header indicates how big the table should be. Do not include any
// IMAGE_SECTION_HEADERs in the table whose 'SizeOfRawData' field is zero.
//
SectionHeader = (EFI_IMAGE_SECTION_HEADER *) AllocateZeroPool (sizeof (EFI_IMAGE_SECTION_HEADER) * mNtHeader.Pe32->FileHeader.NumberOfSections);
if (SectionHeader == NULL) {
Status = FALSE;
goto Done;
}
//
// 12. Using the 'PointerToRawData' in the referenced section headers as
// a key, arrange the elements in the table in ascending order. In other
// words, sort the section headers according to the disk-file offset of
// the section.
//
for (Index = 0; Index < mNtHeader.Pe32->FileHeader.NumberOfSections; Index++) {
Pos = Index;
while ((Pos > 0) && (Section->PointerToRawData < SectionHeader[Pos - 1].PointerToRawData)) {
CopyMem (&SectionHeader[Pos], &SectionHeader[Pos - 1], sizeof (EFI_IMAGE_SECTION_HEADER));
Pos--;
}
CopyMem (&SectionHeader[Pos], Section, sizeof (EFI_IMAGE_SECTION_HEADER));
Section += 1;
}
//
// 13. Walk through the sorted table, bring the corresponding section
// into memory, and hash the entire section (using the 'SizeOfRawData'
// field in the section header to determine the amount of data to hash).
// 14. Add the section's 'SizeOfRawData' to SUM_OF_BYTES_HASHED .
// 15. Repeat steps 13 and 14 for all the sections in the sorted table.
//
for (Index = 0; Index < mNtHeader.Pe32->FileHeader.NumberOfSections; Index++) {
Section = &SectionHeader[Index];
if (Section->SizeOfRawData == 0) {
continue;
}
HashBase = mImageBase + Section->PointerToRawData;
HashSize = (UINTN) Section->SizeOfRawData;
Status = mHash[HashAlg].HashUpdate(HashCtx, HashBase, HashSize);
if (!Status) {
goto Done;
}
SumOfBytesHashed += HashSize;
}
//
// 16. If the file size is greater than SUM_OF_BYTES_HASHED, there is extra
// data in the file that needs to be added to the hash. This data begins
// at file offset SUM_OF_BYTES_HASHED and its length is:
// FileSize - (CertDirectory->Size)
//
if (mImageSize > SumOfBytesHashed) {
HashBase = mImageBase + SumOfBytesHashed;
if (Magic == EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
//
// Use PE32 offset.
//
HashSize = (UINTN)(
mImageSize -
mNtHeader.Pe32->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY].Size -
SumOfBytesHashed);
} else {
//
// Use PE32+ offset.
//
HashSize = (UINTN)(
mImageSize -
mNtHeader.Pe32Plus->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY].Size -
SumOfBytesHashed);
}
Status = mHash[HashAlg].HashUpdate(HashCtx, HashBase, HashSize);
if (!Status) {
goto Done;
}
}
Status = mHash[HashAlg].HashFinal(HashCtx, mImageDigest);
Done:
if (HashCtx != NULL) {
FreePool (HashCtx);
}
if (SectionHeader != NULL) {
FreePool (SectionHeader);
}
return Status;
}
/**
Recognize the Hash algorithm in PE/COFF Authenticode and caculate hash of
Pe/Coff image based on the authenticode image hashing in PE/COFF Specification
8.0 Appendix A
@retval EFI_UNSUPPORTED Hash algorithm is not supported.
@retval EFI_SUCCESS Hash successfully.
**/
EFI_STATUS
HashPeImageByType (
VOID
)
{
UINT8 Index;
WIN_CERTIFICATE_EFI_PKCS *PkcsCertData;
PkcsCertData = (WIN_CERTIFICATE_EFI_PKCS *) (mImageBase + mSecDataDir->VirtualAddress);
for (Index = 0; Index < HASHALG_MAX; Index++) {
//
// Check the Hash algorithm in PE/COFF Authenticode.
// According to PKCS#7 Definition:
// SignedData ::= SEQUENCE {
// version Version,
// digestAlgorithms DigestAlgorithmIdentifiers,
// contentInfo ContentInfo,
// .... }
// The DigestAlgorithmIdentifiers can be used to determine the hash algorithm in PE/COFF hashing
// This field has the fixed offset (+32) in final Authenticode ASN.1 data.
//
if (CompareMem (PkcsCertData->CertData + 32, mHash[Index].OidValue, mHash[Index].OidLength) == 0) {
break;
}
}
if (Index == HASHALG_MAX) {
return EFI_UNSUPPORTED;
}
//
// HASH PE Image based on Hash algorithm in PE/COFF Authenticode.
//
if (!HashPeImage(Index)) {
return EFI_UNSUPPORTED;
}
return EFI_SUCCESS;
}
/**
Returns the size of a given image execution info table in bytes.
This function returns the size, in bytes, of the image execution info table specified by
ImageExeInfoTable. If ImageExeInfoTable is NULL, then 0 is returned.
@param ImageExeInfoTable A pointer to a image execution info table structure.
@retval 0 If ImageExeInfoTable is NULL.
@retval Others The size of a image execution info table in bytes.
**/
UINTN
GetImageExeInfoTableSize (
EFI_IMAGE_EXECUTION_INFO_TABLE *ImageExeInfoTable
)
{
UINTN Index;
EFI_IMAGE_EXECUTION_INFO *ImageExeInfoItem;
UINTN TotalSize;
if (ImageExeInfoTable == NULL) {
return 0;
}
ImageExeInfoItem = (EFI_IMAGE_EXECUTION_INFO *) ((UINT8 *) ImageExeInfoTable + sizeof (EFI_IMAGE_EXECUTION_INFO_TABLE));
TotalSize = sizeof (EFI_IMAGE_EXECUTION_INFO_TABLE);
for (Index = 0; Index < ImageExeInfoTable->NumberOfImages; Index++) {
TotalSize += ReadUnaligned32 ((UINT32 *) &ImageExeInfoItem->InfoSize);
ImageExeInfoItem = (EFI_IMAGE_EXECUTION_INFO *) ((UINT8 *) ImageExeInfoItem + ReadUnaligned32 ((UINT32 *) &ImageExeInfoItem->InfoSize));
}
return TotalSize;
}
/**
Create an Image Execution Information Table entry and add it to system configuration table.
@param[in] Action Describes the action taken by the firmware regarding this image.
@param[in] Name Input a null-terminated, user-friendly name.
@param[in] DevicePath Input device path pointer.
@param[in] Signature Input signature info in EFI_SIGNATURE_LIST data structure.
@param[in] SignatureSize Size of signature.
**/
VOID
AddImageExeInfo (
IN EFI_IMAGE_EXECUTION_ACTION Action,
IN CHAR16 *Name OPTIONAL,
IN CONST EFI_DEVICE_PATH_PROTOCOL *DevicePath,
IN EFI_SIGNATURE_LIST *Signature OPTIONAL,
IN UINTN SignatureSize
)
{
EFI_IMAGE_EXECUTION_INFO_TABLE *ImageExeInfoTable;
EFI_IMAGE_EXECUTION_INFO_TABLE *NewImageExeInfoTable;
EFI_IMAGE_EXECUTION_INFO *ImageExeInfoEntry;
UINTN ImageExeInfoTableSize;
UINTN NewImageExeInfoEntrySize;
UINTN NameStringLen;
UINTN DevicePathSize;
ImageExeInfoTable = NULL;
NewImageExeInfoTable = NULL;
ImageExeInfoEntry = NULL;
NameStringLen = 0;
if (DevicePath == NULL) {
return ;
}
if (Name != NULL) {
NameStringLen = StrSize (Name);
}
ImageExeInfoTable = NULL;
EfiGetSystemConfigurationTable (&gEfiImageSecurityDatabaseGuid, (VOID **) &ImageExeInfoTable);
if (ImageExeInfoTable != NULL) {
//
// The table has been found!
// We must enlarge the table to accmodate the new exe info entry.
//
ImageExeInfoTableSize = GetImageExeInfoTableSize (ImageExeInfoTable);
} else {
//
// Not Found!
// We should create a new table to append to the configuration table.
//
ImageExeInfoTableSize = sizeof (EFI_IMAGE_EXECUTION_INFO_TABLE);
}
DevicePathSize = GetDevicePathSize (DevicePath);
NewImageExeInfoEntrySize = sizeof (EFI_IMAGE_EXECUTION_INFO) + NameStringLen + DevicePathSize + SignatureSize;
NewImageExeInfoTable = (EFI_IMAGE_EXECUTION_INFO_TABLE *) AllocateRuntimePool (ImageExeInfoTableSize + NewImageExeInfoEntrySize);
if (NewImageExeInfoTable == NULL) {
return ;
}
if (ImageExeInfoTable != NULL) {
CopyMem (NewImageExeInfoTable, ImageExeInfoTable, ImageExeInfoTableSize);
} else {
NewImageExeInfoTable->NumberOfImages = 0;
}
NewImageExeInfoTable->NumberOfImages++;
ImageExeInfoEntry = (EFI_IMAGE_EXECUTION_INFO *) ((UINT8 *) NewImageExeInfoTable + ImageExeInfoTableSize);
//
// Update new item's infomation.
//
WriteUnaligned32 ((UINT32 *) &ImageExeInfoEntry->Action, Action);
WriteUnaligned32 ((UINT32 *) &ImageExeInfoEntry->InfoSize, (UINT32) NewImageExeInfoEntrySize);
if (Name != NULL) {
CopyMem ((UINT8 *) &ImageExeInfoEntry->InfoSize + sizeof (UINT32), Name, NameStringLen);
}
CopyMem (
(UINT8 *) &ImageExeInfoEntry->InfoSize + sizeof (UINT32) + NameStringLen,
DevicePath,
DevicePathSize
);
if (Signature != NULL) {
CopyMem (
(UINT8 *) &ImageExeInfoEntry->InfoSize + sizeof (UINT32) + NameStringLen + DevicePathSize,
Signature,
SignatureSize
);
}
//
// Update/replace the image execution table.
//
gBS->InstallConfigurationTable (&gEfiImageSecurityDatabaseGuid, (VOID *) NewImageExeInfoTable);
//
// Free Old table data!
//
if (ImageExeInfoTable != NULL) {
FreePool (ImageExeInfoTable);
}
}
/**
Discover if the UEFI image is authorized by user's policy setting.
@param[in] Policy Specify platform's policy setting.
@retval EFI_ACCESS_DENIED Image is not allowed to run.
@retval EFI_SECURITY_VIOLATION Image is deferred.
@retval EFI_SUCCESS Image is authorized to run.
**/
EFI_STATUS
ImageAuthorization (
IN UINT32 Policy
)
{
EFI_STATUS Status;
EFI_INPUT_KEY Key;
Status = EFI_ACCESS_DENIED;
switch (Policy) {
case QUERY_USER_ON_SECURITY_VIOLATION:
do {
CreatePopUp (EFI_LIGHTGRAY | EFI_BACKGROUND_BLUE, &Key, mNotifyString1, mNotifyString2, NULL);
if (Key.UnicodeChar == L'Y' || Key.UnicodeChar == L'y') {
Status = EFI_SUCCESS;
break;
} else if (Key.UnicodeChar == L'N' || Key.UnicodeChar == L'n') {
Status = EFI_ACCESS_DENIED;
break;
} else if (Key.UnicodeChar == L'D' || Key.UnicodeChar == L'd') {
Status = EFI_SECURITY_VIOLATION;
break;
}
} while (TRUE);
break;
case ALLOW_EXECUTE_ON_SECURITY_VIOLATION:
Status = EFI_SUCCESS;
break;
case DEFER_EXECUTE_ON_SECURITY_VIOLATION:
Status = EFI_SECURITY_VIOLATION;
break;
case DENY_EXECUTE_ON_SECURITY_VIOLATION:
Status = EFI_ACCESS_DENIED;
break;
}
return Status;
}
/**
Check whether signature is in specified database.
@param[in] VariableName Name of database variable that is searched in.
@param[in] Signature Pointer to signature that is searched for.
@param[in] CertType Pointer to hash algrithom.
@param[in] SignatureSize Size of Signature.
@return TRUE Found the signature in the variable database.
@return FALSE Not found the signature in the variable database.
**/
BOOLEAN
IsSignatureFoundInDatabase (
IN CHAR16 *VariableName,
IN UINT8 *Signature,
IN EFI_GUID *CertType,
IN UINTN SignatureSize
)
{
EFI_STATUS Status;
EFI_SIGNATURE_LIST *CertList;
EFI_SIGNATURE_DATA *Cert;
UINTN DataSize;
UINT8 *Data;
UINTN Index;
UINTN CertCount;
BOOLEAN IsFound;
//
// Read signature database variable.
//
IsFound = FALSE;
Data = NULL;
DataSize = 0;
Status = gRT->GetVariable (VariableName, &gEfiImageSecurityDatabaseGuid, NULL, &DataSize, NULL);
if (Status != EFI_BUFFER_TOO_SMALL) {
return FALSE;
}
Data = (UINT8 *) AllocateZeroPool (DataSize);
if (Data == NULL) {
return FALSE;
}
Status = gRT->GetVariable (VariableName, &gEfiImageSecurityDatabaseGuid, NULL, &DataSize, Data);
if (EFI_ERROR (Status)) {
goto Done;
}
//
// Enumerate all signature data in SigDB to check if executable's signature exists.
//
CertList = (EFI_SIGNATURE_LIST *) Data;
while ((DataSize > 0) && (DataSize >= CertList->SignatureListSize)) {
CertCount = (CertList->SignatureListSize - CertList->SignatureHeaderSize) / CertList->SignatureSize;
Cert = (EFI_SIGNATURE_DATA *) ((UINT8 *) CertList + sizeof (EFI_SIGNATURE_LIST) + CertList->SignatureHeaderSize);
if ((CertList->SignatureSize == sizeof(EFI_SIGNATURE_DATA) - 1 + SignatureSize) && (CompareGuid(&CertList->SignatureType, CertType))) {
for (Index = 0; Index < CertCount; Index++) {
if (CompareMem (Cert->SignatureData, Signature, SignatureSize) == 0) {
//
// Find the signature in database.
//
IsFound = TRUE;
break;
}
Cert = (EFI_SIGNATURE_DATA *) ((UINT8 *) Cert + CertList->SignatureSize);
}
if (IsFound) {
break;
}
}
DataSize -= CertList->SignatureListSize;
CertList = (EFI_SIGNATURE_LIST *) ((UINT8 *) CertList + CertList->SignatureListSize);
}
Done:
if (Data != NULL) {
FreePool (Data);
}
return IsFound;
}
/**
Verify PKCS#7 SignedData using certificate found in Variable which formatted
as EFI_SIGNATURE_LIST. The Variable may be PK, KEK, DB or DBX.
@param VariableName Name of Variable to search for Certificate.
@param VendorGuid Variable vendor GUID.
@retval TRUE Image pass verification.
@retval FALSE Image fail verification.
**/
BOOLEAN
IsPkcsSignedDataVerifiedBySignatureList (
IN CHAR16 *VariableName,
IN EFI_GUID *VendorGuid
)
{
EFI_STATUS Status;
BOOLEAN VerifyStatus;
WIN_CERTIFICATE_EFI_PKCS *PkcsCertData;
EFI_SIGNATURE_LIST *CertList;
EFI_SIGNATURE_DATA *Cert;
UINTN DataSize;
UINT8 *Data;
UINT8 *RootCert;
UINTN RootCertSize;
UINTN Index;
UINTN CertCount;
Data = NULL;
CertList = NULL;
Cert = NULL;
RootCert = NULL;
RootCertSize = 0;
VerifyStatus = FALSE;
PkcsCertData = (WIN_CERTIFICATE_EFI_PKCS *) (mImageBase + mSecDataDir->VirtualAddress);
DataSize = 0;
Status = gRT->GetVariable (VariableName, VendorGuid, NULL, &DataSize, NULL);
if (Status == EFI_BUFFER_TOO_SMALL) {
Data = (UINT8 *) AllocateZeroPool (DataSize);
if (Data == NULL) {
return VerifyStatus;
}
Status = gRT->GetVariable (VariableName, VendorGuid, NULL, &DataSize, (VOID *) Data);
if (EFI_ERROR (Status)) {
goto Done;
}
//
// Find X509 certificate in Signature List to verify the signature in pkcs7 signed data.
//
CertList = (EFI_SIGNATURE_LIST *) Data;
while ((DataSize > 0) && (DataSize >= CertList->SignatureListSize)) {
if (CompareGuid (&CertList->SignatureType, &gEfiCertX509Guid)) {
Cert = (EFI_SIGNATURE_DATA *) ((UINT8 *) CertList + sizeof (EFI_SIGNATURE_LIST) + CertList->SignatureHeaderSize);
CertCount = (CertList->SignatureListSize - sizeof (EFI_SIGNATURE_LIST) - CertList->SignatureHeaderSize) / CertList->SignatureSize;
for (Index = 0; Index < CertCount; Index++) {
//
// Iterate each Signature Data Node within this CertList for verify.
//
RootCert = Cert->SignatureData;
RootCertSize = CertList->SignatureSize;
//
// Call AuthenticodeVerify library to Verify Authenticode struct.
//
VerifyStatus = AuthenticodeVerify (
PkcsCertData->CertData,
mSecDataDir->Size - sizeof(PkcsCertData->Hdr),
RootCert,
RootCertSize,
mImageDigest,
mImageDigestSize
);
if (VerifyStatus) {
goto Done;
}
Cert = (EFI_SIGNATURE_DATA *) ((UINT8 *) Cert + CertList->SignatureSize);
}
}
DataSize -= CertList->SignatureListSize;
CertList = (EFI_SIGNATURE_LIST *) ((UINT8 *) CertList + CertList->SignatureListSize);
}
}
Done:
if (Data != NULL) {
FreePool (Data);
}
return VerifyStatus;
}
/**
Verify certificate in WIN_CERT_TYPE_PKCS_SIGNED_DATA format.
@retval EFI_SUCCESS Image pass verification.
@retval EFI_SECURITY_VIOLATION Image fail verification.
**/
EFI_STATUS
VerifyCertPkcsSignedData (
VOID
)
{
//
// 1: Find certificate from DBX forbidden database for revoked certificate.
//
if (IsPkcsSignedDataVerifiedBySignatureList (EFI_IMAGE_SECURITY_DATABASE1, &gEfiImageSecurityDatabaseGuid)) {
//
// DBX is forbidden database, if Authenticode verification pass with
// one of the certificate in DBX, this image should be rejected.
//
return EFI_SECURITY_VIOLATION;
}
//
// 2: Find certificate from KEK database and try to verify authenticode struct.
//
if (IsPkcsSignedDataVerifiedBySignatureList (EFI_KEY_EXCHANGE_KEY_NAME, &gEfiGlobalVariableGuid)) {
return EFI_SUCCESS;
}
//
// 3: Find certificate from DB database and try to verify authenticode struct.
//
if (IsPkcsSignedDataVerifiedBySignatureList (EFI_IMAGE_SECURITY_DATABASE, &gEfiImageSecurityDatabaseGuid)) {
return EFI_SUCCESS;
} else {
return EFI_SECURITY_VIOLATION;
}
}
/**
Verify certificate in WIN_CERTIFICATE_UEFI_GUID format.
@retval EFI_SUCCESS Image pass verification.
@retval EFI_SECURITY_VIOLATION Image fail verification.
@retval other error value
**/
EFI_STATUS
VerifyCertUefiGuid (
VOID
)
{
BOOLEAN Status;
WIN_CERTIFICATE_UEFI_GUID *EfiCert;
EFI_SIGNATURE_LIST *KekList;
EFI_SIGNATURE_DATA *KekItem;
EFI_CERT_BLOCK_RSA_2048_SHA256 *CertBlock;
VOID *Rsa;
UINTN KekCount;
UINTN Index;
UINTN KekDataSize;
BOOLEAN IsFound;
EFI_STATUS Result;
EfiCert = NULL;
KekList = NULL;
KekItem = NULL;
CertBlock = NULL;
Rsa = NULL;
Status = FALSE;
IsFound = FALSE;
KekDataSize = 0;
EfiCert = (WIN_CERTIFICATE_UEFI_GUID *) (mImageBase + mSecDataDir->VirtualAddress);
CertBlock = (EFI_CERT_BLOCK_RSA_2048_SHA256 *) EfiCert->CertData;
if (!CompareGuid (&EfiCert->CertType, &gEfiCertTypeRsa2048Sha256Guid)) {
//
// Invalid Certificate Data Type.
//
return EFI_SECURITY_VIOLATION;
}
//
// Get KEK database variable data size
//
Result = gRT->GetVariable (EFI_KEY_EXCHANGE_KEY_NAME, &gEfiGlobalVariableGuid, NULL, &KekDataSize, NULL);
if (Result != EFI_BUFFER_TOO_SMALL) {
return EFI_SECURITY_VIOLATION;
}
//
// Get KEK database variable.
//
KekList = GetEfiGlobalVariable (EFI_KEY_EXCHANGE_KEY_NAME);
if (KekList == NULL) {
return EFI_SECURITY_VIOLATION;
}
//
// Enumerate all Kek items in this list to verify the variable certificate data.
// If anyone is authenticated successfully, it means the variable is correct!
//
while ((KekDataSize > 0) && (KekDataSize >= KekList->SignatureListSize)) {
if (CompareGuid (&KekList->SignatureType, &gEfiCertRsa2048Guid)) {
KekItem = (EFI_SIGNATURE_DATA *) ((UINT8 *) KekList + sizeof (EFI_SIGNATURE_LIST) + KekList->SignatureHeaderSize);
KekCount = (KekList->SignatureListSize - sizeof (EFI_SIGNATURE_LIST) - KekList->SignatureHeaderSize) / KekList->SignatureSize;
for (Index = 0; Index < KekCount; Index++) {
if (CompareMem (KekItem->SignatureData, CertBlock->PublicKey, EFI_CERT_TYPE_RSA2048_SIZE) == 0) {
IsFound = TRUE;
break;
}
KekItem = (EFI_SIGNATURE_DATA *) ((UINT8 *) KekItem + KekList->SignatureSize);
}
}
KekDataSize -= KekList->SignatureListSize;
KekList = (EFI_SIGNATURE_LIST *) ((UINT8 *) KekList + KekList->SignatureListSize);
}
if (!IsFound) {
//
// Signed key is not a trust one.
//
goto Done;
}
//
// Now, we found the corresponding security policy.
// Verify the data payload.
//
Rsa = RsaNew ();
if (Rsa == NULL) {
Status = FALSE;
goto Done;
}
//
// Set RSA Key Components.
// NOTE: Only N and E are needed to be set as RSA public key for signature verification.
//
Status = RsaSetKey (Rsa, RsaKeyN, CertBlock->PublicKey, EFI_CERT_TYPE_RSA2048_SIZE);
if (!Status) {
goto Done;
}
Status = RsaSetKey (Rsa, RsaKeyE, mRsaE, sizeof (mRsaE));
if (!Status) {
goto Done;
}
//
// Verify the signature.
//
Status = RsaPkcs1Verify (
Rsa,
mImageDigest,
mImageDigestSize,
CertBlock->Signature,
EFI_CERT_TYPE_RSA2048_SHA256_SIZE
);
Done:
if (KekList != NULL) {
FreePool (KekList);
}
if (Rsa != NULL ) {
RsaFree (Rsa);
}
if (Status) {
return EFI_SUCCESS;
} else {
return EFI_SECURITY_VIOLATION;
}
}
/**
Provide verification service for signed images, which include both signature validation
and platform policy control. For signature types, both UEFI WIN_CERTIFICATE_UEFI_GUID and
MSFT Authenticode type signatures are supported.
In this implementation, only verify external executables when in USER MODE.
Executables from FV is bypass, so pass in AuthenticationStatus is ignored.
The image verification process is:
Is the Image signed?
If yes,
Does the image verify against a certificate (root or intermediate) in the allowed db?
Run it
Image verification fail
Is the Image's Hash not in forbidden database and the Image's Hash in allowed db?
Run it
If no,
Is the Image's Hash in the forbidden database (DBX)?
if yes,
Error out
Is the Image's Hash in the allowed database (DB)?
If yes,
Run it
If no,
Error out
@param[in] AuthenticationStatus
This is the authentication status returned from the security
measurement services for the input file.
@param[in] File This is a pointer to the device path of the file that is
being dispatched. This will optionally be used for logging.
@param[in] FileBuffer File buffer matches the input file device path.
@param[in] FileSize Size of File buffer matches the input file device path.
@retval EFI_SUCCESS The file specified by File did authenticate, and the
platform policy dictates that the DXE Core may use File.
@retval EFI_INVALID_PARAMETER Input argument is incorrect.
@retval EFI_OUT_RESOURCE Fail to allocate memory.
@retval EFI_SECURITY_VIOLATION The file specified by File did not authenticate, and
the platform policy dictates that File should be placed
in the untrusted state. A file may be promoted from
the untrusted to the trusted state at a future time
with a call to the Trust() DXE Service.
@retval EFI_ACCESS_DENIED The file specified by File did not authenticate, and
the platform policy dictates that File should not be
used for any purpose.
**/
EFI_STATUS
EFIAPI
DxeImageVerificationHandler (
IN UINT32 AuthenticationStatus,
IN CONST EFI_DEVICE_PATH_PROTOCOL *File,
IN VOID *FileBuffer,
IN UINTN FileSize
)
{
EFI_STATUS Status;
UINT16 Magic;
EFI_IMAGE_DOS_HEADER *DosHdr;
EFI_STATUS VerifyStatus;
UINT8 *SetupMode;
EFI_SIGNATURE_LIST *SignatureList;
UINTN SignatureListSize;
EFI_SIGNATURE_DATA *Signature;
EFI_IMAGE_EXECUTION_ACTION Action;
WIN_CERTIFICATE *WinCertificate;
UINT32 Policy;
UINT8 *SecureBootEnable;
if (File == NULL) {
return EFI_INVALID_PARAMETER;
}
SignatureList = NULL;
SignatureListSize = 0;
WinCertificate = NULL;
Action = EFI_IMAGE_EXECUTION_AUTH_UNTESTED;
Status = EFI_ACCESS_DENIED;
//
// Check the image type and get policy setting.
//
switch (GetImageType (File)) {
case IMAGE_FROM_FV:
Policy = ALWAYS_EXECUTE;
break;
case IMAGE_FROM_OPTION_ROM:
Policy = PcdGet32 (PcdOptionRomImageVerificationPolicy);
break;
case IMAGE_FROM_REMOVABLE_MEDIA:
Policy = PcdGet32 (PcdRemovableMediaImageVerificationPolicy);
break;
case IMAGE_FROM_FIXED_MEDIA:
Policy = PcdGet32 (PcdFixedMediaImageVerificationPolicy);
break;
default:
Policy = DENY_EXECUTE_ON_SECURITY_VIOLATION;
break;
}
//
// If policy is always/never execute, return directly.
//
if (Policy == ALWAYS_EXECUTE) {
return EFI_SUCCESS;
} else if (Policy == NEVER_EXECUTE) {
return EFI_ACCESS_DENIED;
}
SecureBootEnable = GetVariable (EFI_SECURE_BOOT_ENABLE_NAME, &gEfiSecureBootEnableDisableGuid);
//
// Skip verification if SecureBootEnable variable doesn't exist.
//
if (SecureBootEnable == NULL) {
return EFI_SUCCESS;
}
//
// Skip verification if SecureBootEnable is disabled.
//
if (*SecureBootEnable == SECURE_BOOT_DISABLE) {
FreePool (SecureBootEnable);
return EFI_SUCCESS;
}
SetupMode = GetEfiGlobalVariable (EFI_SETUP_MODE_NAME);
//
// SetupMode doesn't exist means no AuthVar driver is dispatched,
// skip verification.
//
if (SetupMode == NULL) {
return EFI_SUCCESS;
}
//
// If platform is in SETUP MODE, skip verification.
//
if (*SetupMode == SETUP_MODE) {
FreePool (SetupMode);
return EFI_SUCCESS;
}
//
// Read the Dos header.
//
if (FileBuffer == NULL) {
FreePool (SetupMode);
return EFI_INVALID_PARAMETER;
}
mImageBase = (UINT8 *) FileBuffer;
mImageSize = FileSize;
DosHdr = (EFI_IMAGE_DOS_HEADER *) mImageBase;
if (DosHdr->e_magic == EFI_IMAGE_DOS_SIGNATURE) {
//
// DOS image header is present,
// so read the PE header after the DOS image header.
//
mPeCoffHeaderOffset = DosHdr->e_lfanew;
} else {
mPeCoffHeaderOffset = 0;
}
//
// Check PE/COFF image.
//
mNtHeader.Pe32 = (EFI_IMAGE_NT_HEADERS32 *) (mImageBase + mPeCoffHeaderOffset);
if (mNtHeader.Pe32->Signature != EFI_IMAGE_NT_SIGNATURE) {
//
// It is not a valid Pe/Coff file.
//
return EFI_ACCESS_DENIED;
}
Magic = mNtHeader.Pe32->OptionalHeader.Magic;
if (Magic == EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
//
// Use PE32 offset.
//
mSecDataDir = (EFI_IMAGE_DATA_DIRECTORY *) &mNtHeader.Pe32->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY];
} else if (Magic == EFI_IMAGE_NT_OPTIONAL_HDR64_MAGIC) {
//
// Use PE32+ offset.
//
mSecDataDir = (EFI_IMAGE_DATA_DIRECTORY *) &mNtHeader.Pe32Plus->OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY];
} else {
//
// Invalid header magic number.
//
Status = EFI_INVALID_PARAMETER;
goto Done;
}
if (mSecDataDir->VirtualAddress >= mImageSize) {
//
// Sanity check to see if this file is corrupted.
//
Status = EFI_INVALID_PARAMETER;
goto Done;
}
if (mSecDataDir->Size == 0) {
//
// This image is not signed.
//
if (!HashPeImage (HASHALG_SHA256)) {
goto Done;
}
if (IsSignatureFoundInDatabase (EFI_IMAGE_SECURITY_DATABASE1, mImageDigest, &mCertType, mImageDigestSize)) {
//
// Image Hash is in forbidden database (DBX).
//
Action = EFI_IMAGE_EXECUTION_AUTH_UNTESTED;
Status = EFI_ACCESS_DENIED;
goto Done;
}
if (IsSignatureFoundInDatabase (EFI_IMAGE_SECURITY_DATABASE, mImageDigest, &mCertType, mImageDigestSize)) {
//
// Image Hash is in allowed database (DB).
//
return EFI_SUCCESS;
}
//
// Image Hash is not found in both forbidden and allowed database.
//
Action = EFI_IMAGE_EXECUTION_AUTH_UNTESTED;
Status = EFI_ACCESS_DENIED;
goto Done;
}
//
// Verify signature of executables.
//
WinCertificate = (WIN_CERTIFICATE *) (mImageBase + mSecDataDir->VirtualAddress);
switch (WinCertificate->wCertificateType) {
case WIN_CERT_TYPE_EFI_GUID:
//
// Verify UEFI GUID type.
//
if (!HashPeImage (HASHALG_SHA256)) {
goto Done;
}
VerifyStatus = VerifyCertUefiGuid ();
break;
case WIN_CERT_TYPE_PKCS_SIGNED_DATA:
//
// Verify Pkcs signed data type.
//
Status = HashPeImageByType();
if (EFI_ERROR (Status)) {
goto Done;
}
VerifyStatus = VerifyCertPkcsSignedData ();
//
// For image verification against enrolled certificate(root or intermediate),
// no need to check image's hash in the allowed database.
//
if (!EFI_ERROR (VerifyStatus)) {
if (!IsSignatureFoundInDatabase (EFI_IMAGE_SECURITY_DATABASE1, mImageDigest, &mCertType, mImageDigestSize)) {
return EFI_SUCCESS;
}
}
break;
default:
Status = EFI_ACCESS_DENIED;
goto Done;
}
//
// Get image hash value as executable's signature.
//
SignatureListSize = sizeof (EFI_SIGNATURE_LIST) + sizeof (EFI_SIGNATURE_DATA) - 1 + mImageDigestSize;
SignatureList = (EFI_SIGNATURE_LIST *) AllocateZeroPool (SignatureListSize);
if (SignatureList == NULL) {
Status = EFI_OUT_OF_RESOURCES;
goto Done;
}
SignatureList->SignatureHeaderSize = 0;
SignatureList->SignatureListSize = (UINT32) SignatureListSize;
SignatureList->SignatureSize = (UINT32) mImageDigestSize;
CopyMem (&SignatureList->SignatureType, &mCertType, sizeof (EFI_GUID));
Signature = (EFI_SIGNATURE_DATA *) ((UINT8 *) SignatureList + sizeof (EFI_SIGNATURE_LIST));
CopyMem (Signature->SignatureData, mImageDigest, mImageDigestSize);
//
// Signature database check after verification.
//
if (EFI_ERROR (VerifyStatus)) {
//
// Verification failure.
//
if (!IsSignatureFoundInDatabase (EFI_IMAGE_SECURITY_DATABASE1, mImageDigest, &mCertType, mImageDigestSize) &&
IsSignatureFoundInDatabase (EFI_IMAGE_SECURITY_DATABASE, mImageDigest, &mCertType, mImageDigestSize)) {
//
// Verification fail, Image Hash is not in forbidden database (DBX),
// and Image Hash is in allowed database (DB).
//
Status = EFI_SUCCESS;
} else {
Action = EFI_IMAGE_EXECUTION_AUTH_SIG_FAILED;
Status = EFI_ACCESS_DENIED;
}
} else if (IsSignatureFoundInDatabase (EFI_IMAGE_SECURITY_DATABASE1, Signature->SignatureData, &mCertType, mImageDigestSize)) {
//
// Executable signature verification passes, but is found in forbidden signature database.
//
Action = EFI_IMAGE_EXECUTION_AUTH_SIG_FOUND;
Status = EFI_ACCESS_DENIED;
} else if (IsSignatureFoundInDatabase (EFI_IMAGE_SECURITY_DATABASE, Signature->SignatureData, &mCertType, mImageDigestSize)) {
//
// Executable signature is found in authorized signature database.
//
Status = EFI_SUCCESS;
} else {
//
// Executable signature verification passes, but cannot be found in authorized signature database.
// Get platform policy to determine the action.
//
Action = EFI_IMAGE_EXECUTION_AUTH_SIG_PASSED;
Status = ImageAuthorization (Policy);
}
Done:
if (Status != EFI_SUCCESS) {
//
// Policy decides to defer or reject the image; add its information in image executable information table.
//
AddImageExeInfo (Action, NULL, File, SignatureList, SignatureListSize);
}
if (SignatureList != NULL) {
FreePool (SignatureList);
}
FreePool (SetupMode);
return Status;
}
/**
When VariableWriteArchProtocol install, create "SecureBoot" variable.
@param[in] Event Event whose notification function is being invoked.
@param[in] Context Pointer to the notification function's context.
**/
VOID
EFIAPI
VariableWriteCallBack (
IN EFI_EVENT Event,
IN VOID *Context
)
{
UINT8 SecureBootMode;
UINT8 *SecureBootModePtr;
EFI_STATUS Status;
VOID *ProtocolPointer;
Status = gBS->LocateProtocol (&gEfiVariableWriteArchProtocolGuid, NULL, &ProtocolPointer);
if (EFI_ERROR (Status)) {
return;
}
//
// Check whether "SecureBoot" variable exists.
// If this library is built-in, it means firmware has capability to perform
// driver signing verification.
//
SecureBootModePtr = GetEfiGlobalVariable (EFI_SECURE_BOOT_MODE_NAME);
if (SecureBootModePtr == NULL) {
SecureBootMode = SECURE_BOOT_MODE_DISABLE;
//
// Authenticated variable driver will update "SecureBoot" depending on SetupMode variable.
//
gRT->SetVariable (
EFI_SECURE_BOOT_MODE_NAME,
&gEfiGlobalVariableGuid,
EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,
sizeof (UINT8),
&SecureBootMode
);
} else {
FreePool (SecureBootModePtr);
}
}
/**
Register security measurement handler.
@param ImageHandle ImageHandle of the loaded driver.
@param SystemTable Pointer to the EFI System Table.
@retval EFI_SUCCESS The handlers were registered successfully.
**/
EFI_STATUS
EFIAPI
DxeImageVerificationLibConstructor (
IN EFI_HANDLE ImageHandle,
IN EFI_SYSTEM_TABLE *SystemTable
)
{
VOID *Registration;
//
// Register callback function upon VariableWriteArchProtocol.
//
EfiCreateProtocolNotifyEvent (
&gEfiVariableWriteArchProtocolGuid,
TPL_CALLBACK,
VariableWriteCallBack,
NULL,
&Registration
);
return RegisterSecurityHandler (
DxeImageVerificationHandler,
EFI_AUTH_OPERATION_VERIFY_IMAGE | EFI_AUTH_OPERATION_IMAGE_REQUIRED
);
}
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