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shim.c
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/*
* shim - trivial UEFI first-stage bootloader
*
* Copyright 2012 Red Hat, Inc <[email protected]>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Significant portions of this code are derived from Tianocore
* (http://tianocore.sf.net) and are Copyright 2009-2012 Intel
* Corporation.
*/
#include <efi.h>
#include <efilib.h>
#include <Library/BaseCryptLib.h>
#include <openssl/rsa.h>
#include <openssl/bio.h>
#include <openssl/x509.h>
#include <openssl/evp.h>
#include <openssl/err.h>
#include "PeImage.h"
#include "shim.h"
#include "netboot.h"
#include "shim_cert.h"
#include "replacements.h"
#include "ucs2.h"
#include "guid.h"
#include "variables.h"
#include "efiauthenticated.h"
#include "security_policy.h"
#include "console.h"
#include "version.h"
#define FALLBACK L"\\fallback.efi"
#define MOK_MANAGER L"\\MokManager.efi"
static EFI_SYSTEM_TABLE *systab;
static EFI_STATUS (EFIAPI *entry_point) (EFI_HANDLE image_handle, EFI_SYSTEM_TABLE *system_table);
static CHAR16 *second_stage;
static void *load_options;
static UINT32 load_options_size;
EFI_GUID SHIM_LOCK_GUID = { 0x605dab50, 0xe046, 0x4300, {0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 0x23} };
typedef BOOLEAN EFIAPI (*verify_func)(
IN CONST UINT8 *AuthData,
IN UINTN DataSize,
IN CONST UINT8 *TrustedCert,
IN UINTN CertSize,
IN CONST UINT8 *ImageHash,
IN UINTN HashSize
);
/*
* The vendor certificate used for validating the second stage loader
*/
extern struct {
UINT32 vendor_cert_size;
UINT32 vendor_dbx_size;
UINT32 vendor_cert_offset;
UINT32 vendor_dbx_offset;
} cert_table;
UINT32 vendor_cert_size;
UINT32 vendor_dbx_size;
UINT8 *vendor_cert;
UINT8 *vendor_dbx;
/*
* indicator of how an image has been verified
*/
verification_method_t verification_method;
int loader_is_participating;
#define EFI_IMAGE_SECURITY_DATABASE_GUID { 0xd719b2cb, 0x3d3a, 0x4596, { 0xa3, 0xbc, 0xda, 0xd0, 0x0e, 0x67, 0x65, 0x6f }}
UINT8 insecure_mode;
UINT8 ignore_db;
typedef enum {
DATA_FOUND,
DATA_NOT_FOUND,
VAR_NOT_FOUND
} CHECK_STATUS;
typedef struct {
UINT32 MokSize;
UINT8 *Mok;
} MokListNode;
/*
* Perform basic bounds checking of the intra-image pointers
*/
static void *ImageAddress (void *image, int size, unsigned int address)
{
if (address > size)
return NULL;
return image + address;
}
/*
* Perform the actual relocation
*/
static EFI_STATUS relocate_coff (PE_COFF_LOADER_IMAGE_CONTEXT *context,
void *data)
{
EFI_IMAGE_BASE_RELOCATION *RelocBase, *RelocBaseEnd;
UINT64 Adjust;
UINT16 *Reloc, *RelocEnd;
char *Fixup, *FixupBase, *FixupData = NULL;
UINT16 *Fixup16;
UINT32 *Fixup32;
UINT64 *Fixup64;
int size = context->ImageSize;
void *ImageEnd = (char *)data + size;
#if __LP64__
context->PEHdr->Pe32Plus.OptionalHeader.ImageBase = (UINT64)data;
#else
context->PEHdr->Pe32.OptionalHeader.ImageBase = (UINT32)data;
#endif
if (context->NumberOfRvaAndSizes <= EFI_IMAGE_DIRECTORY_ENTRY_BASERELOC) {
Print(L"Image has no relocation entry\n");
return EFI_UNSUPPORTED;
}
RelocBase = ImageAddress(data, size, context->RelocDir->VirtualAddress);
RelocBaseEnd = ImageAddress(data, size, context->RelocDir->VirtualAddress + context->RelocDir->Size - 1);
if (!RelocBase || !RelocBaseEnd) {
Print(L"Reloc table overflows binary\n");
return EFI_UNSUPPORTED;
}
Adjust = (UINTN)data - context->ImageAddress;
if (Adjust == 0)
return EFI_SUCCESS;
while (RelocBase < RelocBaseEnd) {
Reloc = (UINT16 *) ((char *) RelocBase + sizeof (EFI_IMAGE_BASE_RELOCATION));
if ((RelocBase->SizeOfBlock == 0) || (RelocBase->SizeOfBlock > context->RelocDir->Size)) {
Print(L"Reloc block size is invalid\n");
return EFI_UNSUPPORTED;
}
RelocEnd = (UINT16 *) ((char *) RelocBase + RelocBase->SizeOfBlock);
if ((void *)RelocEnd < data || (void *)RelocEnd > ImageEnd) {
Print(L"Reloc entry overflows binary\n");
return EFI_UNSUPPORTED;
}
FixupBase = ImageAddress(data, size, RelocBase->VirtualAddress);
if (!FixupBase) {
Print(L"Invalid fixupbase\n");
return EFI_UNSUPPORTED;
}
while (Reloc < RelocEnd) {
Fixup = FixupBase + (*Reloc & 0xFFF);
switch ((*Reloc) >> 12) {
case EFI_IMAGE_REL_BASED_ABSOLUTE:
break;
case EFI_IMAGE_REL_BASED_HIGH:
Fixup16 = (UINT16 *) Fixup;
*Fixup16 = (UINT16) (*Fixup16 + ((UINT16) ((UINT32) Adjust >> 16)));
if (FixupData != NULL) {
*(UINT16 *) FixupData = *Fixup16;
FixupData = FixupData + sizeof (UINT16);
}
break;
case EFI_IMAGE_REL_BASED_LOW:
Fixup16 = (UINT16 *) Fixup;
*Fixup16 = (UINT16) (*Fixup16 + (UINT16) Adjust);
if (FixupData != NULL) {
*(UINT16 *) FixupData = *Fixup16;
FixupData = FixupData + sizeof (UINT16);
}
break;
case EFI_IMAGE_REL_BASED_HIGHLOW:
Fixup32 = (UINT32 *) Fixup;
*Fixup32 = *Fixup32 + (UINT32) Adjust;
if (FixupData != NULL) {
FixupData = ALIGN_POINTER (FixupData, sizeof (UINT32));
*(UINT32 *)FixupData = *Fixup32;
FixupData = FixupData + sizeof (UINT32);
}
break;
case EFI_IMAGE_REL_BASED_DIR64:
Fixup64 = (UINT64 *) Fixup;
*Fixup64 = *Fixup64 + (UINT64) Adjust;
if (FixupData != NULL) {
FixupData = ALIGN_POINTER (FixupData, sizeof(UINT64));
*(UINT64 *)(FixupData) = *Fixup64;
FixupData = FixupData + sizeof(UINT64);
}
break;
default:
Print(L"Unknown relocation\n");
return EFI_UNSUPPORTED;
}
Reloc += 1;
}
RelocBase = (EFI_IMAGE_BASE_RELOCATION *) RelocEnd;
}
return EFI_SUCCESS;
}
static CHECK_STATUS internal_check_db_cert_in_ram(EFI_SIGNATURE_LIST *CertList,
UINTN dbsize,
CONST UINT8 *sigdata,
UINTN sigsize,
UINT8 *hash,
verify_func vfunc)
{
EFI_SIGNATURE_DATA *Cert;
UINTN CertCount, Index;
BOOLEAN IsFound = FALSE;
EFI_GUID CertType = X509_GUID;
while ((dbsize > 0) && (dbsize >= CertList->SignatureListSize)) {
if (CompareGuid (&CertList->SignatureType, &CertType) == 0) {
CertCount = (CertList->SignatureListSize - sizeof (EFI_SIGNATURE_LIST) - CertList->SignatureHeaderSize) / CertList->SignatureSize;
Cert = (EFI_SIGNATURE_DATA *) ((UINT8 *) CertList + sizeof (EFI_SIGNATURE_LIST) + CertList->SignatureHeaderSize);
for (Index = 0; Index < CertCount; Index++) {
IsFound = vfunc(sigdata, sigsize,
Cert->SignatureData,
CertList->SignatureSize,
hash, SHA256_DIGEST_SIZE);
if (IsFound)
break;
Cert = (EFI_SIGNATURE_DATA *) ((UINT8 *) Cert + CertList->SignatureSize);
}
}
if (IsFound)
break;
dbsize -= CertList->SignatureListSize;
CertList = (EFI_SIGNATURE_LIST *) ((UINT8 *) CertList + CertList->SignatureListSize);
}
if (IsFound)
return DATA_FOUND;
return DATA_NOT_FOUND;
}
static CHECK_STATUS check_db_cert_in_ram(EFI_SIGNATURE_LIST *CertList,
UINTN dbsize,
WIN_CERTIFICATE_EFI_PKCS *data,
UINT8 *hash)
{
return internal_check_db_cert_in_ram(CertList, dbsize, data->CertData,
data->Hdr.dwLength - sizeof(data->Hdr),
hash, AuthenticodeVerify);
}
static CHECK_STATUS internal_check_db_cert(CHAR16 *dbname, EFI_GUID guid,
CONST UINT8 *sigdata, UINTN sigsize,
UINT8 *hash, verify_func vfunc)
{
CHECK_STATUS rc;
EFI_STATUS efi_status;
EFI_SIGNATURE_LIST *CertList;
UINTN dbsize = 0;
UINT8 *db;
efi_status = get_variable(dbname, &db, &dbsize, guid);
if (efi_status != EFI_SUCCESS)
return VAR_NOT_FOUND;
CertList = (EFI_SIGNATURE_LIST *)db;
rc = internal_check_db_cert_in_ram(CertList, dbsize, sigdata, sigsize,
hash, vfunc);
FreePool(db);
return rc;
}
static CHECK_STATUS check_db_cert(CHAR16 *dbname, EFI_GUID guid,
WIN_CERTIFICATE_EFI_PKCS *data, UINT8 *hash)
{
return internal_check_db_cert(dbname, guid, data->CertData,
data->Hdr.dwLength - sizeof(data->Hdr),
hash, AuthenticodeVerify);
}
/*
* Check a hash against an EFI_SIGNATURE_LIST in a buffer
*/
static CHECK_STATUS check_db_hash_in_ram(EFI_SIGNATURE_LIST *CertList,
UINTN dbsize, UINT8 *data,
int SignatureSize, EFI_GUID CertType)
{
EFI_SIGNATURE_DATA *Cert;
UINTN CertCount, Index;
BOOLEAN IsFound = FALSE;
while ((dbsize > 0) && (dbsize >= CertList->SignatureListSize)) {
CertCount = (CertList->SignatureListSize -sizeof (EFI_SIGNATURE_LIST) - CertList->SignatureHeaderSize) / CertList->SignatureSize;
Cert = (EFI_SIGNATURE_DATA *) ((UINT8 *) CertList + sizeof (EFI_SIGNATURE_LIST) + CertList->SignatureHeaderSize);
if (CompareGuid(&CertList->SignatureType, &CertType) == 0) {
for (Index = 0; Index < CertCount; Index++) {
if (CompareMem (Cert->SignatureData, data, SignatureSize) == 0) {
//
// Find the signature in database.
//
IsFound = TRUE;
break;
}
Cert = (EFI_SIGNATURE_DATA *) ((UINT8 *) Cert + CertList->SignatureSize);
}
if (IsFound) {
break;
}
}
dbsize -= CertList->SignatureListSize;
CertList = (EFI_SIGNATURE_LIST *) ((UINT8 *) CertList + CertList->SignatureListSize);
}
if (IsFound)
return DATA_FOUND;
return DATA_NOT_FOUND;
}
/*
* Check a hash against an EFI_SIGNATURE_LIST in a UEFI variable
*/
static CHECK_STATUS check_db_hash(CHAR16 *dbname, EFI_GUID guid, UINT8 *data,
int SignatureSize, EFI_GUID CertType)
{
EFI_STATUS efi_status;
EFI_SIGNATURE_LIST *CertList;
UINTN dbsize = 0;
UINT8 *db;
efi_status = get_variable(dbname, &db, &dbsize, guid);
if (efi_status != EFI_SUCCESS) {
return VAR_NOT_FOUND;
}
CertList = (EFI_SIGNATURE_LIST *)db;
CHECK_STATUS rc = check_db_hash_in_ram(CertList, dbsize, data,
SignatureSize, CertType);
FreePool(db);
return rc;
}
/*
* Check whether the binary signature or hash are present in dbx or the
* built-in blacklist
*/
static EFI_STATUS check_blacklist (WIN_CERTIFICATE_EFI_PKCS *cert,
UINT8 *sha256hash, UINT8 *sha1hash)
{
EFI_GUID secure_var = EFI_IMAGE_SECURITY_DATABASE_GUID;
EFI_SIGNATURE_LIST *dbx = (EFI_SIGNATURE_LIST *)vendor_dbx;
if (check_db_hash_in_ram(dbx, vendor_dbx_size, sha256hash,
SHA256_DIGEST_SIZE, EFI_CERT_SHA256_GUID) ==
DATA_FOUND)
return EFI_ACCESS_DENIED;
if (check_db_hash_in_ram(dbx, vendor_dbx_size, sha1hash,
SHA1_DIGEST_SIZE, EFI_CERT_SHA1_GUID) ==
DATA_FOUND)
return EFI_ACCESS_DENIED;
if (cert && check_db_cert_in_ram(dbx, vendor_dbx_size, cert,
sha256hash) == DATA_FOUND)
return EFI_ACCESS_DENIED;
if (check_db_hash(L"dbx", secure_var, sha256hash, SHA256_DIGEST_SIZE,
EFI_CERT_SHA256_GUID) == DATA_FOUND)
return EFI_ACCESS_DENIED;
if (check_db_hash(L"dbx", secure_var, sha1hash, SHA1_DIGEST_SIZE,
EFI_CERT_SHA1_GUID) == DATA_FOUND)
return EFI_ACCESS_DENIED;
if (cert && check_db_cert(L"dbx", secure_var, cert, sha256hash) ==
DATA_FOUND)
return EFI_ACCESS_DENIED;
return EFI_SUCCESS;
}
static void update_verification_method(verification_method_t method)
{
if (verification_method == VERIFIED_BY_NOTHING)
verification_method = method;
}
/*
* Check whether the binary signature or hash are present in db or MokList
*/
static EFI_STATUS check_whitelist (WIN_CERTIFICATE_EFI_PKCS *cert,
UINT8 *sha256hash, UINT8 *sha1hash)
{
EFI_GUID secure_var = EFI_IMAGE_SECURITY_DATABASE_GUID;
EFI_GUID shim_var = SHIM_LOCK_GUID;
if (!ignore_db) {
if (check_db_hash(L"db", secure_var, sha256hash, SHA256_DIGEST_SIZE,
EFI_CERT_SHA256_GUID) == DATA_FOUND) {
update_verification_method(VERIFIED_BY_HASH);
return EFI_SUCCESS;
}
if (check_db_hash(L"db", secure_var, sha1hash, SHA1_DIGEST_SIZE,
EFI_CERT_SHA1_GUID) == DATA_FOUND) {
verification_method = VERIFIED_BY_HASH;
update_verification_method(VERIFIED_BY_HASH);
return EFI_SUCCESS;
}
if (cert && check_db_cert(L"db", secure_var, cert, sha256hash)
== DATA_FOUND) {
verification_method = VERIFIED_BY_CERT;
update_verification_method(VERIFIED_BY_CERT);
return EFI_SUCCESS;
}
}
if (check_db_hash(L"MokList", shim_var, sha256hash, SHA256_DIGEST_SIZE,
EFI_CERT_SHA256_GUID) == DATA_FOUND) {
verification_method = VERIFIED_BY_HASH;
update_verification_method(VERIFIED_BY_HASH);
return EFI_SUCCESS;
}
if (cert && check_db_cert(L"MokList", shim_var, cert, sha256hash) ==
DATA_FOUND) {
verification_method = VERIFIED_BY_CERT;
update_verification_method(VERIFIED_BY_CERT);
return EFI_SUCCESS;
}
update_verification_method(VERIFIED_BY_NOTHING);
return EFI_ACCESS_DENIED;
}
/*
* Check whether we're in Secure Boot and user mode
*/
static BOOLEAN secure_mode (void)
{
EFI_STATUS status;
EFI_GUID global_var = EFI_GLOBAL_VARIABLE;
UINTN len;
UINT8 *Data;
UINT8 sb, setupmode;
if (insecure_mode)
return FALSE;
status = get_variable(L"SecureBoot", &Data, &len, global_var);
if (status != EFI_SUCCESS) {
if (verbose)
console_notify(L"Secure boot not enabled\n");
return FALSE;
}
sb = *Data;
FreePool(Data);
if (sb != 1) {
if (verbose)
console_notify(L"Secure boot not enabled\n");
return FALSE;
}
status = get_variable(L"SetupMode", &Data, &len, global_var);
if (status != EFI_SUCCESS)
return TRUE;
setupmode = *Data;
FreePool(Data);
if (setupmode == 1) {
if (verbose)
console_notify(L"Platform is in setup mode\n");
return FALSE;
}
return TRUE;
}
/*
* Calculate the SHA1 and SHA256 hashes of a binary
*/
static EFI_STATUS generate_hash (char *data, int datasize,
PE_COFF_LOADER_IMAGE_CONTEXT *context,
UINT8 *sha256hash, UINT8 *sha1hash)
{
unsigned int sha256ctxsize, sha1ctxsize;
unsigned int size = datasize;
void *sha256ctx = NULL, *sha1ctx = NULL;
char *hashbase;
unsigned int hashsize;
unsigned int SumOfBytesHashed, SumOfSectionBytes;
unsigned int index, pos;
EFI_IMAGE_SECTION_HEADER *Section;
EFI_IMAGE_SECTION_HEADER *SectionHeader = NULL;
EFI_IMAGE_SECTION_HEADER *SectionCache;
EFI_STATUS status = EFI_SUCCESS;
sha256ctxsize = Sha256GetContextSize();
sha256ctx = AllocatePool(sha256ctxsize);
sha1ctxsize = Sha1GetContextSize();
sha1ctx = AllocatePool(sha1ctxsize);
if (!sha256ctx || !sha1ctx) {
Print(L"Unable to allocate memory for hash context\n");
return EFI_OUT_OF_RESOURCES;
}
if (!Sha256Init(sha256ctx) || !Sha1Init(sha1ctx)) {
Print(L"Unable to initialise hash\n");
status = EFI_OUT_OF_RESOURCES;
goto done;
}
/* Hash start to checksum */
hashbase = data;
hashsize = (char *)&context->PEHdr->Pe32.OptionalHeader.CheckSum -
hashbase;
if (!(Sha256Update(sha256ctx, hashbase, hashsize)) ||
!(Sha1Update(sha1ctx, hashbase, hashsize))) {
Print(L"Unable to generate hash\n");
status = EFI_OUT_OF_RESOURCES;
goto done;
}
/* Hash post-checksum to start of certificate table */
hashbase = (char *)&context->PEHdr->Pe32.OptionalHeader.CheckSum +
sizeof (int);
hashsize = (char *)context->SecDir - hashbase;
if (!(Sha256Update(sha256ctx, hashbase, hashsize)) ||
!(Sha1Update(sha1ctx, hashbase, hashsize))) {
Print(L"Unable to generate hash\n");
status = EFI_OUT_OF_RESOURCES;
goto done;
}
/* Hash end of certificate table to end of image header */
#if __LP64__
hashbase = (char *) &context->PEHdr->Pe32Plus.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY + 1];
hashsize = context->PEHdr->Pe32Plus.OptionalHeader.SizeOfHeaders -
(int) ((char *) (&context->PEHdr->Pe32Plus.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY + 1]) - data);
#else
hashbase = (char *) &context->PEHdr->Pe32.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY + 1];
hashsize = context->PEHdr->Pe32.OptionalHeader.SizeOfHeaders -
(int) ((char *) (&context->PEHdr->Pe32.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY + 1]) - data);
#endif
if (!(Sha256Update(sha256ctx, hashbase, hashsize)) ||
!(Sha1Update(sha1ctx, hashbase, hashsize))) {
Print(L"Unable to generate hash\n");
status = EFI_OUT_OF_RESOURCES;
goto done;
}
/* Sort sections */
#if __LP64__
SumOfBytesHashed = context->PEHdr->Pe32Plus.OptionalHeader.SizeOfHeaders;
#else
SumOfBytesHashed = context->PEHdr->Pe32.OptionalHeader.SizeOfHeaders;
#endif
Section = (EFI_IMAGE_SECTION_HEADER *) (
(char *)context->PEHdr + sizeof (UINT32) +
sizeof (EFI_IMAGE_FILE_HEADER) +
context->PEHdr->Pe32.FileHeader.SizeOfOptionalHeader
);
SectionCache = Section;
for (index = 0, SumOfSectionBytes = 0; index < context->PEHdr->Pe32.FileHeader.NumberOfSections; index++, SectionCache++) {
SumOfSectionBytes += SectionCache->SizeOfRawData;
}
if (SumOfSectionBytes >= datasize) {
Print(L"Malformed binary: %x %x\n", SumOfSectionBytes, size);
status = EFI_INVALID_PARAMETER;
goto done;
}
SectionHeader = (EFI_IMAGE_SECTION_HEADER *) AllocateZeroPool (sizeof (EFI_IMAGE_SECTION_HEADER) * context->PEHdr->Pe32.FileHeader.NumberOfSections);
if (SectionHeader == NULL) {
Print(L"Unable to allocate section header\n");
status = EFI_OUT_OF_RESOURCES;
goto done;
}
/* Sort the section headers */
for (index = 0; index < context->PEHdr->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;
}
/* Hash the sections */
for (index = 0; index < context->PEHdr->Pe32.FileHeader.NumberOfSections; index++) {
Section = &SectionHeader[index];
if (Section->SizeOfRawData == 0) {
continue;
}
hashbase = ImageAddress(data, size, Section->PointerToRawData);
hashsize = (unsigned int) Section->SizeOfRawData;
if (!hashbase) {
Print(L"Malformed section header\n");
status = EFI_INVALID_PARAMETER;
goto done;
}
if (!(Sha256Update(sha256ctx, hashbase, hashsize)) ||
!(Sha1Update(sha1ctx, hashbase, hashsize))) {
Print(L"Unable to generate hash\n");
status = EFI_OUT_OF_RESOURCES;
goto done;
}
SumOfBytesHashed += Section->SizeOfRawData;
}
/* Hash all remaining data */
if (size > SumOfBytesHashed) {
hashbase = data + SumOfBytesHashed;
hashsize = (unsigned int)(
size -
#if __LP64__
context->PEHdr->Pe32Plus.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY].Size -
#else
context->PEHdr->Pe32.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY].Size -
#endif
SumOfBytesHashed);
if (!(Sha256Update(sha256ctx, hashbase, hashsize)) ||
!(Sha1Update(sha1ctx, hashbase, hashsize))) {
Print(L"Unable to generate hash\n");
status = EFI_OUT_OF_RESOURCES;
goto done;
}
}
if (!(Sha256Final(sha256ctx, sha256hash)) ||
!(Sha1Final(sha1ctx, sha1hash))) {
Print(L"Unable to finalise hash\n");
status = EFI_OUT_OF_RESOURCES;
goto done;
}
done:
if (SectionHeader)
FreePool(SectionHeader);
if (sha1ctx)
FreePool(sha1ctx);
if (sha256ctx)
FreePool(sha256ctx);
return status;
}
/*
* Ensure that the MOK database hasn't been set or modified from an OS
*/
static EFI_STATUS verify_mok (void) {
EFI_GUID shim_lock_guid = SHIM_LOCK_GUID;
EFI_STATUS status = EFI_SUCCESS;
UINT8 *MokListData = NULL;
UINTN MokListDataSize = 0;
UINT32 attributes;
status = get_variable_attr(L"MokList", &MokListData, &MokListDataSize,
shim_lock_guid, &attributes);
if (!EFI_ERROR(status) && attributes & EFI_VARIABLE_RUNTIME_ACCESS) {
Print(L"MokList is compromised!\nErase all keys in MokList!\n");
if (LibDeleteVariable(L"MokList", &shim_lock_guid) != EFI_SUCCESS) {
Print(L"Failed to erase MokList\n");
return EFI_ACCESS_DENIED;
}
}
if (MokListData)
FreePool(MokListData);
return EFI_SUCCESS;
}
static VOID pr_error_openssl(void)
{
unsigned long code;
while ( (code = ERR_get_error()) )
/* Sadly, can't print out the friendly error string because
* all the BIO snprintf() functions are stubbed out due to the
* lack of most 8-bit string functions in gnu-efi. Look up the
* codes using 'openssl errstr' in a shell */
Print(L"openssl error code %08X\n", code);
}
static EVP_PKEY *get_pkey(CONST UINT8 *cert, UINTN certsize)
{
BIO *bio;
X509 *x509 = NULL;
EVP_PKEY *pkey = NULL;
/* BIO is the OpenSSL input/output abstraction. Instantiate
* one using a memory buffer containing the certificate */
bio = BIO_new_mem_buf((void *)cert, certsize);
if (!bio) {
return NULL;
}
/* Obtain an x509 structure from the DER cert data */
x509 = d2i_X509_bio(bio, NULL);
if (!x509) {
goto done;
}
/* And finally get the public key out of the certificate */
pkey = X509_get_pubkey(x509);
if (!pkey) {
goto done;
}
if (EVP_PKEY_RSA != EVP_PKEY_type(pkey->type)) {
EVP_PKEY_free(pkey);
pkey = NULL;
}
done:
if (bio != NULL)
BIO_free(bio);
if (x509 != NULL)
X509_free(x509);
return pkey;
}
static BOOLEAN EFIAPI openssl_verify(
IN CONST UINT8 *sig, IN UINTN sigsize,
IN CONST UINT8 *cert, IN UINTN certsize,
IN CONST UINT8 *hash, IN UINTN hashsize)
{
EVP_PKEY *pkey;
UINTN ret;
if (!sig || !cert || !hash)
return FALSE;
pkey = get_pkey(cert, certsize);
if (!pkey) {
Print(L"Unable to extract public key from certificate\n");
return FALSE;
}
ret = RSA_verify(NID_sha256, hash, hashsize, (unsigned char *)sig,
sigsize, EVP_PKEY_get1_RSA(pkey));
EVP_PKEY_free(pkey);
return (ret == 1) ? TRUE : FALSE;
}
static CHECK_STATUS check_db_blob_cert_in_ram(EFI_SIGNATURE_LIST *CertList,
UINTN dbsize,
UINT8 *data,
UINTN datasize,
UINT8 *hash)
{
return internal_check_db_cert_in_ram(CertList, dbsize, data,
datasize, hash, openssl_verify);
}
static CHECK_STATUS check_db_blob_cert(
CHAR16 *dbname, EFI_GUID guid,
UINT8 *data, UINTN datasize,
UINT8 *hash)
{
return internal_check_db_cert(dbname, guid, data, datasize,
hash, openssl_verify);
}
/*
* Check whether the binary signature or hash are present in dbx or the
* built-in blacklist
*/
static EFI_STATUS blob_check_blacklist (
IN UINT8 *sig,
IN UINTN sigsize,
UINT8 *sha256hash)
{
EFI_GUID secure_var = EFI_IMAGE_SECURITY_DATABASE_GUID;
EFI_SIGNATURE_LIST *dbx = (EFI_SIGNATURE_LIST *)vendor_dbx;
if (check_db_hash_in_ram(dbx, vendor_dbx_size, sha256hash,
SHA256_DIGEST_SIZE, EFI_CERT_SHA256_GUID) ==
DATA_FOUND)
return EFI_ACCESS_DENIED;
if (check_db_blob_cert_in_ram(dbx, vendor_dbx_size, sig, sigsize,
sha256hash) == DATA_FOUND)
return EFI_ACCESS_DENIED;
if (check_db_hash(L"dbx", secure_var, sha256hash, SHA256_DIGEST_SIZE,
EFI_CERT_SHA256_GUID) == DATA_FOUND)
return EFI_ACCESS_DENIED;
if (check_db_blob_cert(L"dbx", secure_var, sig, sigsize, sha256hash) == DATA_FOUND)
return EFI_ACCESS_DENIED;
return EFI_SUCCESS;
}
/*
* Check whether the binary signature or hash are present in db or MokList
*/
static EFI_STATUS blob_check_whitelist (
IN UINT8 *sig,
IN UINTN sigsize,
UINT8 *sha256hash)
{
EFI_GUID secure_var = EFI_IMAGE_SECURITY_DATABASE_GUID;
EFI_GUID shim_var = SHIM_LOCK_GUID;
if (!ignore_db) {
if (check_db_hash(L"db", secure_var, sha256hash,
SHA256_DIGEST_SIZE,
EFI_CERT_SHA256_GUID) == DATA_FOUND) {
update_verification_method(VERIFIED_BY_HASH);
return EFI_SUCCESS;
}
if (check_db_blob_cert(L"db", secure_var, sig, sigsize,
sha256hash) == DATA_FOUND) {
update_verification_method(VERIFIED_BY_CERT);
return EFI_SUCCESS;
}
}
if (check_db_hash(L"MokList", shim_var, sha256hash, SHA256_DIGEST_SIZE,
EFI_CERT_SHA256_GUID) == DATA_FOUND)
return EFI_SUCCESS;
if (check_db_blob_cert(L"MokList", shim_var, sig, sigsize, sha256hash) == DATA_FOUND)
return EFI_SUCCESS;
return EFI_ACCESS_DENIED;
}
static EFI_STATUS verify_generic_blob (VOID *data, UINTN datasize,
VOID *sig, UINTN sigsize)
{
SHA256_CTX sha_ctx;
UINT8 digest[SHA256_DIGEST_LENGTH];
loader_is_participating = 1;
if (1 != SHA256_Init(&sha_ctx))
return EFI_INVALID_PARAMETER;
if (1 != SHA256_Update(&sha_ctx, data, datasize))
return EFI_INVALID_PARAMETER;
if (1 != SHA256_Final(digest, &sha_ctx))
return EFI_INVALID_PARAMETER;
if (EFI_ERROR(verify_mok())) {
Print(L"MokList is compromised and could not be erased");
return EFI_ACCESS_DENIED;
}
if (EFI_ERROR(blob_check_blacklist(sig, sigsize, digest))) {
Print(L"Binary is blacklisted\n");
return EFI_ACCESS_DENIED;
}
if (EFI_SUCCESS == blob_check_whitelist(sig, sigsize, digest))
return EFI_SUCCESS;
if (openssl_verify(sig, sigsize, shim_cert, sizeof(shim_cert),
digest, SHA256_DIGEST_LENGTH))
return EFI_SUCCESS;
if (openssl_verify(sig, sigsize, vendor_cert, vendor_cert_size,
digest, SHA256_DIGEST_LENGTH))
return EFI_SUCCESS;
pr_error_openssl();
Print(L"Invalid signature\n");
return EFI_ACCESS_DENIED;
}
/*
* Check that the signature is valid and matches the binary
*/
static EFI_STATUS verify_buffer (char *data, int datasize,
PE_COFF_LOADER_IMAGE_CONTEXT *context)
{
UINT8 sha256hash[SHA256_DIGEST_SIZE];
UINT8 sha1hash[SHA1_DIGEST_SIZE];
EFI_STATUS status = EFI_ACCESS_DENIED;
WIN_CERTIFICATE_EFI_PKCS *cert = NULL;
unsigned int size = datasize;
if (context->SecDir->Size != 0) {
cert = ImageAddress (data, size,
context->SecDir->VirtualAddress);
if (!cert) {
Print(L"Certificate located outside the image\n");
return EFI_INVALID_PARAMETER;
}
if (cert->Hdr.wCertificateType !=
WIN_CERT_TYPE_PKCS_SIGNED_DATA) {
Print(L"Unsupported certificate type %x\n",
cert->Hdr.wCertificateType);
return EFI_UNSUPPORTED;
}
}
status = generate_hash(data, datasize, context, sha256hash, sha1hash);
if (status != EFI_SUCCESS)
return status;
/*
* Check that the MOK database hasn't been modified
*/
status = verify_mok();
if (status != EFI_SUCCESS)
return status;
/*
* Ensure that the binary isn't blacklisted
*/
status = check_blacklist(cert, sha256hash, sha1hash);
if (status != EFI_SUCCESS) {
Print(L"Binary is blacklisted\n");
return status;
}