proxmox-mirrors/efi-boot-shim
1
0
Fork 0
mirror of https://git.proxmox.com/git/efi-boot-shim synced 2025-05-29 22:48:18 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity
62f0afa2ec
efi-boot-shim/shim.c
Mathieu Trudel-Lapierre 62f0afa2ec Import upstream version 0.9+1474479173.6c180c6
2016-09-21 20:29:42 -04:00

2741 lines
72 KiB
C
Raw Blame History

/*
* shim - trivial UEFI first-stage bootloader
*
* Copyright 2012 Red Hat, Inc <mjg@redhat.com>
*
* 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 "PeImage.h"
#include "shim.h"
#include "netboot.h"
#include "httpboot.h"
#include "shim_cert.h"
#include "replacements.h"
#include "tpm.h"
#include "ucs2.h"
#include "guid.h"
#include "variables.h"
#include "efiauthenticated.h"
#include "security_policy.h"
#include "console.h"
#include "version.h"
#include <stdarg.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>
#define FALLBACK L"\\fb" EFI_ARCH L".efi"
#define MOK_MANAGER L"\\mm" EFI_ARCH L".efi"
#define OID_EKU_MODSIGN "1.3.6.1.4.1.2312.16.1.2"
static EFI_SYSTEM_TABLE *systab;
static EFI_HANDLE image_handle;
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;
static UINT8 in_protocol;
#define perror(fmt, ...) ({ \
UINTN __perror_ret = 0; \
if (!in_protocol) \
__perror_ret = Print((fmt), ##__VA_ARGS__); \
__perror_ret; \
})
EFI_GUID SHIM_LOCK_GUID = { 0x605dab50, 0xe046, 0x4300, {0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 0x23} };
/*
* 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 user_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, unsigned int size, unsigned int address)
{
if (address > size)
return NULL;
return image + address;
}
/* here's a chart:
* i686 x86_64 aarch64
* 64-on-64: nyet yes yes
* 64-on-32: nyet yes nyet
* 32-on-32: yes yes no
*/
static int
allow_64_bit(void)
{
#if defined(__x86_64__) || defined(__aarch64__)
return 1;
#elif defined(__i386__) || defined(__i686__)
/* Right now blindly assuming the kernel will correctly detect this
* and /halt the system/ if you're not really on a 64-bit cpu */
if (in_protocol)
return 1;
return 0;
#else /* assuming everything else is 32-bit... */
return 0;
#endif
}
static int
allow_32_bit(void)
{
#if defined(__x86_64__)
#if defined(ALLOW_32BIT_KERNEL_ON_X64)
if (in_protocol)
return 1;
return 0;
#else
return 0;
#endif
#elif defined(__i386__) || defined(__i686__)
return 1;
#elif defined(__arch64__)
return 0;
#else /* assuming everything else is 32-bit... */
return 1;
#endif
}
static int
image_is_64_bit(EFI_IMAGE_OPTIONAL_HEADER_UNION *PEHdr)
{
/* .Magic is the same offset in all cases */
if (PEHdr->Pe32Plus.OptionalHeader.Magic
== EFI_IMAGE_NT_OPTIONAL_HDR64_MAGIC)
return 1;
return 0;
}
static const UINT16 machine_type =
#if defined(__x86_64__)
IMAGE_FILE_MACHINE_X64;
#elif defined(__aarch64__)
IMAGE_FILE_MACHINE_ARM64;
#elif defined(__arm__)
IMAGE_FILE_MACHINE_ARMTHUMB_MIXED;
#elif defined(__i386__) || defined(__i486__) || defined(__i686__)
IMAGE_FILE_MACHINE_I386;
#elif defined(__ia64__)
IMAGE_FILE_MACHINE_IA64;
#else
#error this architecture is not supported by shim
#endif
static int
image_is_loadable(EFI_IMAGE_OPTIONAL_HEADER_UNION *PEHdr)
{
/* If the machine type doesn't match the binary, bail, unless
* we're in an allowed 64-on-32 scenario */
if (PEHdr->Pe32.FileHeader.Machine != machine_type) {
if (!(machine_type == IMAGE_FILE_MACHINE_I386 &&
PEHdr->Pe32.FileHeader.Machine == IMAGE_FILE_MACHINE_X64 &&
allow_64_bit())) {
return 0;
}
}
/* If it's not a header type we recognize at all, bail */
switch (PEHdr->Pe32Plus.OptionalHeader.Magic) {
case EFI_IMAGE_NT_OPTIONAL_HDR64_MAGIC:
case EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC:
break;
default:
return 0;
}
/* and now just check for general 64-vs-32 compatibility */
if (image_is_64_bit(PEHdr)) {
if (allow_64_bit())
return 1;
} else {
if (allow_32_bit())
return 1;
}
return 0;
}
/*
* Perform the actual relocation
*/
static EFI_STATUS relocate_coff (PE_COFF_LOADER_IMAGE_CONTEXT *context,
EFI_IMAGE_SECTION_HEADER *Section,
void *orig, 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 *)orig + size;
int n = 0;
if (image_is_64_bit(context->PEHdr))
context->PEHdr->Pe32Plus.OptionalHeader.ImageBase = (UINT64)(unsigned long)data;
else
context->PEHdr->Pe32.OptionalHeader.ImageBase = (UINT32)(unsigned long)data;
/* Alright, so here's how this works:
*
* context->RelocDir gives us two things:
* - the VA the table of base relocation blocks are (maybe) to be
* mapped at (RelocDir->VirtualAddress)
* - the virtual size (RelocDir->Size)
*
* The .reloc section (Section here) gives us some other things:
* - the name! kind of. (Section->Name)
* - the virtual size (Section->VirtualSize), which should be the same
* as RelocDir->Size
* - the virtual address (Section->VirtualAddress)
* - the file section size (Section->SizeOfRawData), which is
* a multiple of OptHdr->FileAlignment. Only useful for image
* validation, not really useful for iteration bounds.
* - the file address (Section->PointerToRawData)
* - a bunch of stuff we don't use that's 0 in our binaries usually
* - Flags (Section->Characteristics)
*
* and then the thing that's actually at the file address is an array
* of EFI_IMAGE_BASE_RELOCATION structs with some values packed behind
* them. The SizeOfBlock field of this structure includes the
* structure itself, and adding it to that structure's address will
* yield the next entry in the array.
*/
RelocBase = ImageAddress(orig, size, Section->PointerToRawData);
/* RelocBaseEnd here is the address of the first entry /past/ the
* table. */
RelocBaseEnd = ImageAddress(orig, size, Section->PointerToRawData +
Section->Misc.VirtualSize);
if (!RelocBase && !RelocBaseEnd)
return EFI_SUCCESS;
if (!RelocBase || !RelocBaseEnd) {
perror(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)) {
perror(L"Reloc %d block size %d is invalid\n", n, RelocBase->SizeOfBlock);
return EFI_UNSUPPORTED;
}
RelocEnd = (UINT16 *) ((char *) RelocBase + RelocBase->SizeOfBlock);
if ((void *)RelocEnd < orig || (void *)RelocEnd > ImageEnd) {
perror(L"Reloc %d entry overflows binary\n", n);
return EFI_UNSUPPORTED;
}
FixupBase = ImageAddress(data, size, RelocBase->VirtualAddress);
if (!FixupBase) {
perror(L"Reloc %d Invalid fixupbase\n", 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:
perror(L"Reloc %d Unknown relocation\n", n);
return EFI_UNSUPPORTED;
}
Reloc += 1;
}
RelocBase = (EFI_IMAGE_BASE_RELOCATION *) RelocEnd;
n++;
}
return EFI_SUCCESS;
}
static BOOLEAN verify_x509(UINT8 *Cert, UINTN CertSize)
{
UINTN length;
if (!Cert || CertSize < 4)
return FALSE;
/*
* A DER encoding x509 certificate starts with SEQUENCE(0x30),
* the number of length bytes, and the number of value bytes.
* The size of a x509 certificate is usually between 127 bytes
* and 64KB. For convenience, assume the number of value bytes
* is 2, i.e. the second byte is 0x82.
*/
if (Cert[0] != 0x30 || Cert[1] != 0x82)
return FALSE;
length = Cert[2]<<8 | Cert[3];
if (length != (CertSize - 4))
return FALSE;
return TRUE;
}
static BOOLEAN verify_eku(UINT8 *Cert, UINTN CertSize)
{
X509 *x509;
CONST UINT8 *Temp = Cert;
EXTENDED_KEY_USAGE *eku;
ASN1_OBJECT *module_signing;
module_signing = OBJ_nid2obj(OBJ_create(OID_EKU_MODSIGN, NULL, NULL));
x509 = d2i_X509 (NULL, &Temp, (long) CertSize);
if (x509 != NULL) {
eku = X509_get_ext_d2i(x509, NID_ext_key_usage, NULL, NULL);
if (eku) {
int i = 0;
for (i = 0; i < sk_ASN1_OBJECT_num(eku); i++) {
ASN1_OBJECT *key_usage = sk_ASN1_OBJECT_value(eku, i);
if (OBJ_cmp(module_signing, key_usage) == 0)
return FALSE;
}
EXTENDED_KEY_USAGE_free(eku);
}
X509_free(x509);
}
OBJ_cleanup();
return TRUE;
}
static CHECK_STATUS check_db_cert_in_ram(EFI_SIGNATURE_LIST *CertList,
UINTN dbsize,
WIN_CERTIFICATE_EFI_PKCS *data,
UINT8 *hash)
{
EFI_SIGNATURE_DATA *Cert;
UINTN CertSize;
BOOLEAN IsFound = FALSE;
EFI_GUID CertType = X509_GUID;
while ((dbsize > 0) && (dbsize >= CertList->SignatureListSize)) {
if (CompareGuid (&CertList->SignatureType, &CertType) == 0) {
Cert = (EFI_SIGNATURE_DATA *) ((UINT8 *) CertList + sizeof (EFI_SIGNATURE_LIST) + CertList->SignatureHeaderSize);
CertSize = CertList->SignatureSize - sizeof(EFI_GUID);
if (verify_x509(Cert->SignatureData, CertSize)) {
if (verify_eku(Cert->SignatureData, CertSize)) {
IsFound = AuthenticodeVerify (data->CertData,
data->Hdr.dwLength - sizeof(data->Hdr),
Cert->SignatureData,
CertSize,
hash, SHA256_DIGEST_SIZE);
if (IsFound)
return DATA_FOUND;
}
} else if (verbose) {
console_notify(L"Not a DER encoding x.509 Certificate");
}
}
dbsize -= CertList->SignatureListSize;
CertList = (EFI_SIGNATURE_LIST *) ((UINT8 *) CertList + CertList->SignatureListSize);
}
return DATA_NOT_FOUND;
}
static CHECK_STATUS check_db_cert(CHAR16 *dbname, EFI_GUID guid,
WIN_CERTIFICATE_EFI_PKCS *data, UINT8 *hash)
{
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 = check_db_cert_in_ram(CertList, dbsize, data, hash);
FreePool(db);
return rc;
}
/*
* 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_GUID shim_var = SHIM_LOCK_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;
if (check_db_hash(L"MokListX", shim_var, sha256hash, SHA256_DIGEST_SIZE,
EFI_CERT_SHA256_GUID) == DATA_FOUND) {
return EFI_ACCESS_DENIED;
}
if (cert && check_db_cert(L"MokListX", shim_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)
{
static int first = 1;
if (user_insecure_mode)
return FALSE;
if (variable_is_secureboot() != 1) {
if (verbose && !in_protocol && first)
console_notify(L"Secure boot not enabled");
first = 0;
return FALSE;
}
/* If we /do/ have "SecureBoot", but /don't/ have "SetupMode",
* then the implementation is bad, but we assume that secure boot is
* enabled according to the status of "SecureBoot". If we have both
* of them, then "SetupMode" may tell us additional data, and we need
* to consider it.
*/
if (variable_is_setupmode(0) == 1) {
if (verbose && !in_protocol && first)
console_notify(L"Platform is in setup mode");
first = 0;
return FALSE;
}
first = 0;
return TRUE;
}
#define check_size_line(data, datasize_in, hashbase, hashsize, l) ({ \
if ((unsigned long)hashbase > \
(unsigned long)data + datasize_in) { \
perror(L"shim.c:%d Invalid hash base 0x%016x\n", l, \
hashbase); \
goto done; \
} \
if ((unsigned long)hashbase + hashsize > \
(unsigned long)data + datasize_in) { \
perror(L"shim.c:%d Invalid hash size 0x%016x\n", l, \
hashsize); \
goto done; \
} \
})
#define check_size(d,ds,h,hs) check_size_line(d,ds,h,hs,__LINE__)
/*
* Calculate the SHA1 and SHA256 hashes of a binary
*/
static EFI_STATUS generate_hash (char *data, unsigned int datasize_in,
PE_COFF_LOADER_IMAGE_CONTEXT *context,
UINT8 *sha256hash, UINT8 *sha1hash)
{
unsigned int sha256ctxsize, sha1ctxsize;
unsigned int size = datasize_in;
void *sha256ctx = NULL, *sha1ctx = NULL;
char *hashbase;
unsigned int hashsize;
unsigned int SumOfBytesHashed, SumOfSectionBytes;
unsigned int index, pos;
unsigned int datasize;
EFI_IMAGE_SECTION_HEADER *Section;
EFI_IMAGE_SECTION_HEADER *SectionHeader = NULL;
EFI_STATUS status = EFI_SUCCESS;
EFI_IMAGE_DOS_HEADER *DosHdr = (void *)data;
unsigned int PEHdr_offset = 0;
if (datasize_in < 0) {
perror(L"Invalid data size\n");
return EFI_INVALID_PARAMETER;
}
size = datasize = (unsigned int)datasize_in;
if (datasize <= sizeof (*DosHdr) ||
DosHdr->e_magic != EFI_IMAGE_DOS_SIGNATURE) {
perror(L"Invalid signature\n");
return EFI_INVALID_PARAMETER;
}
PEHdr_offset = DosHdr->e_lfanew;
sha256ctxsize = Sha256GetContextSize();
sha256ctx = AllocatePool(sha256ctxsize);
sha1ctxsize = Sha1GetContextSize();
sha1ctx = AllocatePool(sha1ctxsize);
if (!sha256ctx || !sha1ctx) {
perror(L"Unable to allocate memory for hash context\n");
return EFI_OUT_OF_RESOURCES;
}
if (!Sha256Init(sha256ctx) || !Sha1Init(sha1ctx)) {
perror(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;
check_size(data, datasize_in, hashbase, hashsize);
if (!(Sha256Update(sha256ctx, hashbase, hashsize)) ||
!(Sha1Update(sha1ctx, hashbase, hashsize))) {
perror(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;
check_size(data, datasize_in, hashbase, hashsize);
if (!(Sha256Update(sha256ctx, hashbase, hashsize)) ||
!(Sha1Update(sha1ctx, hashbase, hashsize))) {
perror(L"Unable to generate hash\n");
status = EFI_OUT_OF_RESOURCES;
goto done;
}
/* Hash end of certificate table to end of image header */
EFI_IMAGE_DATA_DIRECTORY *dd = context->SecDir + 1;
hashbase = (char *)dd;
hashsize = context->SizeOfHeaders - (unsigned long)((char *)dd - data);
if (hashsize > datasize_in) {
perror(L"Data Directory size %d is invalid\n", hashsize);
status = EFI_INVALID_PARAMETER;
goto done;
}
check_size(data, datasize_in, hashbase, hashsize);
if (!(Sha256Update(sha256ctx, hashbase, hashsize)) ||
!(Sha1Update(sha1ctx, hashbase, hashsize))) {
perror(L"Unable to generate hash\n");
status = EFI_OUT_OF_RESOURCES;
goto done;
}
/* Sort sections */
SumOfBytesHashed = context->SizeOfHeaders;
/* Validate section locations and sizes */
for (index = 0, SumOfSectionBytes = 0; index < context->PEHdr->Pe32.FileHeader.NumberOfSections; index++) {
EFI_IMAGE_SECTION_HEADER *SectionPtr;
/* Validate SectionPtr is within image */
SectionPtr = ImageAddress(data, datasize,
PEHdr_offset +
sizeof (UINT32) +
sizeof (EFI_IMAGE_FILE_HEADER) +
context->PEHdr->Pe32.FileHeader.SizeOfOptionalHeader +
(index * sizeof(*SectionPtr)));
if (!SectionPtr) {
perror(L"Malformed section %d\n", index);
status = EFI_INVALID_PARAMETER;
goto done;
}
/* Validate section size is within image. */
if (SectionPtr->SizeOfRawData >
datasize - SumOfBytesHashed - SumOfSectionBytes) {
perror(L"Malformed section %d size\n", index);
status = EFI_INVALID_PARAMETER;
goto done;
}
SumOfSectionBytes += SectionPtr->SizeOfRawData;
}
SectionHeader = (EFI_IMAGE_SECTION_HEADER *) AllocateZeroPool (sizeof (EFI_IMAGE_SECTION_HEADER) * context->PEHdr->Pe32.FileHeader.NumberOfSections);
if (SectionHeader == NULL) {
perror(L"Unable to allocate section header\n");
status = EFI_OUT_OF_RESOURCES;
goto done;
}
/* Already validated above */
Section = ImageAddress(data, datasize,
PEHdr_offset +
sizeof (UINT32) +
sizeof (EFI_IMAGE_FILE_HEADER) +
context->PEHdr->Pe32.FileHeader.SizeOfOptionalHeader);
/* 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);
if (!hashbase) {
perror(L"Malformed section header\n");
status = EFI_INVALID_PARAMETER;
goto done;
}
/* Verify hashsize within image. */
if (Section->SizeOfRawData >
datasize - Section->PointerToRawData) {
perror(L"Malformed section raw size %d\n", index);
status = EFI_INVALID_PARAMETER;
goto done;
}
hashsize = (unsigned int) Section->SizeOfRawData;
check_size(data, datasize_in, hashbase, hashsize);
if (!(Sha256Update(sha256ctx, hashbase, hashsize)) ||
!(Sha1Update(sha1ctx, hashbase, hashsize))) {
perror(L"Unable to generate hash\n");
status = EFI_OUT_OF_RESOURCES;
goto done;
}
SumOfBytesHashed += Section->SizeOfRawData;
}
/* Hash all remaining data */
if (datasize > SumOfBytesHashed) {
hashbase = data + SumOfBytesHashed;
hashsize = datasize - context->SecDir->Size - SumOfBytesHashed;
check_size(data, datasize_in, hashbase, hashsize);
if (!(Sha256Update(sha256ctx, hashbase, hashsize)) ||
!(Sha1Update(sha1ctx, hashbase, hashsize))) {
perror(L"Unable to generate hash\n");
status = EFI_OUT_OF_RESOURCES;
goto done;
}
}
if (!(Sha256Final(sha256ctx, sha256hash)) ||
!(Sha1Final(sha1ctx, sha1hash))) {
perror(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) {
perror(L"MokList is compromised!\nErase all keys in MokList!\n");
if (LibDeleteVariable(L"MokList", &shim_lock_guid) != EFI_SUCCESS) {
perror(L"Failed to erase MokList\n");
return EFI_ACCESS_DENIED;
}
}
if (MokListData)
FreePool(MokListData);
return EFI_SUCCESS;
}
/*
* 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) {
if (context->SecDir->Size >= size) {
perror(L"Certificate Database size is too large\n");
return EFI_INVALID_PARAMETER;
}
cert = ImageAddress (data, size,
context->SecDir->VirtualAddress);
if (!cert) {
perror(L"Certificate located outside the image\n");
return EFI_INVALID_PARAMETER;
}
if (cert->Hdr.dwLength > context->SecDir->Size) {
perror(L"Certificate list size is inconsistent with PE headers");
return EFI_INVALID_PARAMETER;
}
if (cert->Hdr.wCertificateType !=
WIN_CERT_TYPE_PKCS_SIGNED_DATA) {
perror(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) {
perror(L"Binary is blacklisted\n");
return status;
}
/*
* Check whether the binary is whitelisted in any of the firmware
* databases
*/
status = check_whitelist(cert, sha256hash, sha1hash);
if (status == EFI_SUCCESS)
return status;
if (cert) {
/*
* Check against the shim build key
*/
if (sizeof(shim_cert) &&
AuthenticodeVerify(cert->CertData,
cert->Hdr.dwLength - sizeof(cert->Hdr),
shim_cert, sizeof(shim_cert), sha256hash,
SHA256_DIGEST_SIZE)) {
status = EFI_SUCCESS;
return status;
}
/*
* And finally, check against shim's built-in key
*/
if (vendor_cert_size &&
AuthenticodeVerify(cert->CertData,
cert->Hdr.dwLength - sizeof(cert->Hdr),
vendor_cert, vendor_cert_size,
sha256hash, SHA256_DIGEST_SIZE)) {
status = EFI_SUCCESS;
return status;
}
}
status = EFI_ACCESS_DENIED;
return status;
}
/*
* Read the binary header and grab appropriate information from it
*/
static EFI_STATUS read_header(void *data, unsigned int datasize,
PE_COFF_LOADER_IMAGE_CONTEXT *context)
{
EFI_IMAGE_DOS_HEADER *DosHdr = data;
EFI_IMAGE_OPTIONAL_HEADER_UNION *PEHdr = data;
unsigned long HeaderWithoutDataDir, SectionHeaderOffset, OptHeaderSize;
unsigned long FileAlignment = 0;
if (datasize < sizeof (PEHdr->Pe32)) {
perror(L"Invalid image\n");
return EFI_UNSUPPORTED;
}
if (DosHdr->e_magic == EFI_IMAGE_DOS_SIGNATURE)
PEHdr = (EFI_IMAGE_OPTIONAL_HEADER_UNION *)((char *)data + DosHdr->e_lfanew);
if (!image_is_loadable(PEHdr)) {
perror(L"Platform does not support this image\n");
return EFI_UNSUPPORTED;
}
if (image_is_64_bit(PEHdr)) {
context->NumberOfRvaAndSizes = PEHdr->Pe32Plus.OptionalHeader.NumberOfRvaAndSizes;
context->SizeOfHeaders = PEHdr->Pe32Plus.OptionalHeader.SizeOfHeaders;
context->ImageSize = PEHdr->Pe32Plus.OptionalHeader.SizeOfImage;
context->SectionAlignment = PEHdr->Pe32Plus.OptionalHeader.SectionAlignment;
FileAlignment = PEHdr->Pe32Plus.OptionalHeader.FileAlignment;
OptHeaderSize = sizeof(EFI_IMAGE_OPTIONAL_HEADER64);
} else {
context->NumberOfRvaAndSizes = PEHdr->Pe32.OptionalHeader.NumberOfRvaAndSizes;
context->SizeOfHeaders = PEHdr->Pe32.OptionalHeader.SizeOfHeaders;
context->ImageSize = (UINT64)PEHdr->Pe32.OptionalHeader.SizeOfImage;
context->SectionAlignment = PEHdr->Pe32.OptionalHeader.SectionAlignment;
FileAlignment = PEHdr->Pe32.OptionalHeader.FileAlignment;
OptHeaderSize = sizeof(EFI_IMAGE_OPTIONAL_HEADER32);
}
if (FileAlignment % 2 != 0) {
perror(L"File Alignment is invalid (%d)\n", FileAlignment);
return EFI_UNSUPPORTED;
}
if (FileAlignment == 0)
FileAlignment = 0x200;
if (context->SectionAlignment == 0)
context->SectionAlignment = PAGE_SIZE;
if (context->SectionAlignment < FileAlignment)
context->SectionAlignment = FileAlignment;
context->NumberOfSections = PEHdr->Pe32.FileHeader.NumberOfSections;
if (EFI_IMAGE_NUMBER_OF_DIRECTORY_ENTRIES < context->NumberOfRvaAndSizes) {
perror(L"Image header too small\n");
return EFI_UNSUPPORTED;
}
HeaderWithoutDataDir = OptHeaderSize
- sizeof (EFI_IMAGE_DATA_DIRECTORY) * EFI_IMAGE_NUMBER_OF_DIRECTORY_ENTRIES;
if (((UINT32)PEHdr->Pe32.FileHeader.SizeOfOptionalHeader - HeaderWithoutDataDir) !=
context->NumberOfRvaAndSizes * sizeof (EFI_IMAGE_DATA_DIRECTORY)) {
perror(L"Image header overflows data directory\n");
return EFI_UNSUPPORTED;
}
SectionHeaderOffset = DosHdr->e_lfanew
+ sizeof (UINT32)
+ sizeof (EFI_IMAGE_FILE_HEADER)
+ PEHdr->Pe32.FileHeader.SizeOfOptionalHeader;
if (((UINT32)context->ImageSize - SectionHeaderOffset) / EFI_IMAGE_SIZEOF_SECTION_HEADER
<= context->NumberOfSections) {
perror(L"Image sections overflow image size\n");
return EFI_UNSUPPORTED;
}
if ((context->SizeOfHeaders - SectionHeaderOffset) / EFI_IMAGE_SIZEOF_SECTION_HEADER
< (UINT32)context->NumberOfSections) {
perror(L"Image sections overflow section headers\n");
return EFI_UNSUPPORTED;
}
if ((((UINT8 *)PEHdr - (UINT8 *)data) + sizeof(EFI_IMAGE_OPTIONAL_HEADER_UNION)) > datasize) {
perror(L"Invalid image\n");
return EFI_UNSUPPORTED;
}
if (PEHdr->Te.Signature != EFI_IMAGE_NT_SIGNATURE) {
perror(L"Unsupported image type\n");
return EFI_UNSUPPORTED;
}
if (PEHdr->Pe32.FileHeader.Characteristics & EFI_IMAGE_FILE_RELOCS_STRIPPED) {
perror(L"Unsupported image - Relocations have been stripped\n");
return EFI_UNSUPPORTED;
}
context->PEHdr = PEHdr;
if (image_is_64_bit(PEHdr)) {
context->ImageAddress = PEHdr->Pe32Plus.OptionalHeader.ImageBase;
context->EntryPoint = PEHdr->Pe32Plus.OptionalHeader.AddressOfEntryPoint;
context->RelocDir = &PEHdr->Pe32Plus.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_BASERELOC];
context->SecDir = &PEHdr->Pe32Plus.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY];
} else {
context->ImageAddress = PEHdr->Pe32.OptionalHeader.ImageBase;
context->EntryPoint = PEHdr->Pe32.OptionalHeader.AddressOfEntryPoint;
context->RelocDir = &PEHdr->Pe32.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_BASERELOC];
context->SecDir = &PEHdr->Pe32.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_SECURITY];
}
context->FirstSection = (EFI_IMAGE_SECTION_HEADER *)((char *)PEHdr + PEHdr->Pe32.FileHeader.SizeOfOptionalHeader + sizeof(UINT32) + sizeof(EFI_IMAGE_FILE_HEADER));
if (context->ImageSize < context->SizeOfHeaders) {
perror(L"Invalid image\n");
return EFI_UNSUPPORTED;
}
if ((unsigned long)((UINT8 *)context->SecDir - (UINT8 *)data) >
(datasize - sizeof(EFI_IMAGE_DATA_DIRECTORY))) {
perror(L"Invalid image\n");
return EFI_UNSUPPORTED;
}
if (context->SecDir->VirtualAddress >= datasize) {
perror(L"Malformed security header\n");
return EFI_INVALID_PARAMETER;
}
return EFI_SUCCESS;
}
/*
* Once the image has been loaded it needs to be validated and relocated
*/
static EFI_STATUS handle_image (void *data, unsigned int datasize,
EFI_LOADED_IMAGE *li)
{
EFI_STATUS efi_status;
char *buffer;
int i;
EFI_IMAGE_SECTION_HEADER *Section;
char *base, *end;
PE_COFF_LOADER_IMAGE_CONTEXT context;
unsigned int alignment;
int found_entry_point = 0;
/*
* The binary header contains relevant context and section pointers
*/
efi_status = read_header(data, datasize, &context);
if (efi_status != EFI_SUCCESS) {
perror(L"Failed to read header: %r\n", efi_status);
return efi_status;
}
/*
* We only need to verify the binary if we're in secure mode
*/
if (secure_mode ()) {
efi_status = verify_buffer(data, datasize, &context);
if (EFI_ERROR(efi_status)) {
console_error(L"Verification failed", efi_status);
return efi_status;
} else {
if (verbose)
console_notify(L"Verification succeeded");
}
}
/* The spec says, uselessly, of SectionAlignment:
* =====
* The alignment (in bytes) of sections when they are loaded into
* memory. It must be greater than or equal to FileAlignment. The
* default is the page size for the architecture.
* =====
* Which doesn't tell you whose responsibility it is to enforce the
* "default", or when. It implies that the value in the field must
* be > FileAlignment (also poorly defined), but it appears visual
* studio will happily write 512 for FileAlignment (its default) and
* 0 for SectionAlignment, intending to imply PAGE_SIZE.
*
* We only support one page size, so if it's zero, nerf it to 4096.
*/
alignment = context.SectionAlignment;
if (!alignment)
alignment = 4096;
buffer = AllocatePool(context.ImageSize + context.SectionAlignment);
buffer = ALIGN_POINTER(buffer, alignment);
if (!buffer) {
perror(L"Failed to allocate image buffer\n");
return EFI_OUT_OF_RESOURCES;
}
CopyMem(buffer, data, context.SizeOfHeaders);
entry_point = ImageAddress(buffer, context.ImageSize, context.EntryPoint);
if (!entry_point) {
perror(L"Entry point is invalid\n");
FreePool(buffer);
return EFI_UNSUPPORTED;
}
char *RelocBase, *RelocBaseEnd;
/*
* These are relative virtual addresses, so we have to check them
* against the image size, not the data size.
*/
RelocBase = ImageAddress(buffer, context.ImageSize,
context.RelocDir->VirtualAddress);
/*
* RelocBaseEnd here is the address of the last byte of the table
*/
RelocBaseEnd = ImageAddress(buffer, context.ImageSize,
context.RelocDir->VirtualAddress +
context.RelocDir->Size - 1);
EFI_IMAGE_SECTION_HEADER *RelocSection = NULL;
/*
* Copy the executable's sections to their desired offsets
*/
Section = context.FirstSection;
for (i = 0; i < context.NumberOfSections; i++, Section++) {
base = ImageAddress (buffer, context.ImageSize,
Section->VirtualAddress);
end = ImageAddress (buffer, context.ImageSize,
Section->VirtualAddress
+ Section->Misc.VirtualSize - 1);
if (end < base) {
perror(L"Section %d has negative size\n", i);
FreePool(buffer);
return EFI_UNSUPPORTED;
}
if (Section->VirtualAddress <= context.EntryPoint &&
(Section->VirtualAddress + Section->SizeOfRawData - 1)
> context.EntryPoint)
found_entry_point++;
/* We do want to process .reloc, but it's often marked
* discardable, so we don't want to memcpy it. */
if (CompareMem(Section->Name, ".reloc\0\0", 8) == 0) {
if (RelocSection) {
perror(L"Image has multiple relocation sections\n");
return EFI_UNSUPPORTED;
}
/* If it has nonzero sizes, and our bounds check
* made sense, and the VA and size match RelocDir's
* versions, then we believe in this section table. */
if (Section->SizeOfRawData &&
Section->Misc.VirtualSize &&
base && end &&
RelocBase == base &&
RelocBaseEnd == end) {
RelocSection = Section;
}
}
if (Section->Characteristics & EFI_IMAGE_SCN_MEM_DISCARDABLE) {
continue;
}
if (!base) {
perror(L"Section %d has invalid base address\n", i);
return EFI_UNSUPPORTED;
}
if (!end) {
perror(L"Section %d has zero size\n", i);
return EFI_UNSUPPORTED;
}
if (!(Section->Characteristics & EFI_IMAGE_SCN_CNT_UNINITIALIZED_DATA) &&
(Section->VirtualAddress < context.SizeOfHeaders ||
Section->PointerToRawData < context.SizeOfHeaders)) {
perror(L"Section %d is inside image headers\n", i);
return EFI_UNSUPPORTED;
}
if (Section->Characteristics & EFI_IMAGE_SCN_CNT_UNINITIALIZED_DATA) {
ZeroMem(base, Section->Misc.VirtualSize);
} else {
if (Section->PointerToRawData < context.SizeOfHeaders) {
perror(L"Section %d is inside image headers\n", i);
return EFI_UNSUPPORTED;
}
if (Section->SizeOfRawData > 0)
CopyMem(base, data + Section->PointerToRawData,
Section->SizeOfRawData);
if (Section->SizeOfRawData < Section->Misc.VirtualSize)
ZeroMem(base + Section->SizeOfRawData,
Section->Misc.VirtualSize - Section->SizeOfRawData);
}
}
if (context.NumberOfRvaAndSizes <= EFI_IMAGE_DIRECTORY_ENTRY_BASERELOC) {
perror(L"Image has no relocation entry\n");
FreePool(buffer);
return EFI_UNSUPPORTED;
}
if (context.RelocDir->Size && RelocSection) {
/*
* Run the relocation fixups
*/
efi_status = relocate_coff(&context, RelocSection, data,
buffer);
if (efi_status != EFI_SUCCESS) {
perror(L"Relocation failed: %r\n", efi_status);
FreePool(buffer);
return efi_status;
}
}
/*
* grub needs to know its location and size in memory, so fix up
* the loaded image protocol values
*/
li->ImageBase = buffer;
li->ImageSize = context.ImageSize;
/* Pass the load options to the second stage loader */
li->LoadOptions = load_options;
li->LoadOptionsSize = load_options_size;
if (!found_entry_point) {
perror(L"Entry point is not within sections\n");
return EFI_UNSUPPORTED;
}
if (found_entry_point > 1) {
perror(L"%d sections contain entry point\n");
return EFI_UNSUPPORTED;
}
return EFI_SUCCESS;
}
static int
should_use_fallback(EFI_HANDLE image_handle)
{
EFI_GUID loaded_image_protocol = LOADED_IMAGE_PROTOCOL;
EFI_LOADED_IMAGE *li;
unsigned int pathlen = 0;
CHAR16 *bootpath = NULL;
EFI_FILE_IO_INTERFACE *fio = NULL;
EFI_FILE *vh = NULL;
EFI_FILE *fh = NULL;
EFI_STATUS rc;
int ret = 0;
rc = uefi_call_wrapper(BS->HandleProtocol, 3, image_handle,
&loaded_image_protocol, (void **)&li);
if (EFI_ERROR(rc)) {
perror(L"Could not get image for bootx64.efi: %r\n", rc);
return 0;
}
bootpath = DevicePathToStr(li->FilePath);
/* Check the beginning of the string and the end, to avoid
* caring about which arch this is. */
/* I really don't know why, but sometimes bootpath gives us
* L"\\EFI\\BOOT\\/BOOTX64.EFI". So just handle that here...
*/
if (StrnCaseCmp(bootpath, L"\\EFI\\BOOT\\BOOT", 14) &&
StrnCaseCmp(bootpath, L"\\EFI\\BOOT\\/BOOT", 15) &&
StrnCaseCmp(bootpath, L"EFI\\BOOT\\BOOT", 13) &&
StrnCaseCmp(bootpath, L"EFI\\BOOT\\/BOOT", 14))
goto error;
pathlen = StrLen(bootpath);
if (pathlen < 5 || StrCaseCmp(bootpath + pathlen - 4, L".EFI"))
goto error;
rc = uefi_call_wrapper(BS->HandleProtocol, 3, li->DeviceHandle,
&FileSystemProtocol, (void **)&fio);
if (EFI_ERROR(rc)) {
perror(L"Could not get fio for li->DeviceHandle: %r\n", rc);
goto error;
}
rc = uefi_call_wrapper(fio->OpenVolume, 2, fio, &vh);
if (EFI_ERROR(rc)) {
perror(L"Could not open fio volume: %r\n", rc);
goto error;
}
rc = uefi_call_wrapper(vh->Open, 5, vh, &fh, L"\\EFI\\BOOT" FALLBACK,
EFI_FILE_MODE_READ, 0);
if (EFI_ERROR(rc)) {
/* Do not print the error here - this is an acceptable case
* for removable media, where we genuinely don't want
* fallback.efi to exist.
* Print(L"Could not open \"\\EFI\\BOOT%s\": %d\n", FALLBACK,
* rc);
*/
goto error;
}
ret = 1;
error:
if (fh)
uefi_call_wrapper(fh->Close, 1, fh);
if (vh)
uefi_call_wrapper(vh->Close, 1, vh);
if (bootpath)
FreePool(bootpath);
return ret;
}
/*
* Generate the path of an executable given shim's path and the name
* of the executable
*/
static EFI_STATUS generate_path(EFI_LOADED_IMAGE *li, CHAR16 *ImagePath,
CHAR16 **PathName)
{
EFI_DEVICE_PATH *devpath;
unsigned int i;
int j, last = -1;
unsigned int pathlen = 0;
EFI_STATUS efi_status = EFI_SUCCESS;
CHAR16 *bootpath;
/*
* Suuuuper lazy technique here, but check and see if this is a full
* path to something on the ESP. Backwards compatibility demands
* that we don't just use \\, becuase we (not particularly brightly)
* used to require that the relative file path started with that.
*
* If it is a full path, don't try to merge it with the directory
* from our Loaded Image handle.
*/
if (StrSize(ImagePath) > 5 && StrnCmp(ImagePath, L"\\EFI\\", 5) == 0) {
*PathName = StrDuplicate(ImagePath);
if (!*PathName) {
perror(L"Failed to allocate path buffer\n");
return EFI_OUT_OF_RESOURCES;
}
return EFI_SUCCESS;
}
devpath = li->FilePath;
bootpath = DevicePathToStr(devpath);
pathlen = StrLen(bootpath);
/*
* DevicePathToStr() concatenates two nodes with '/'.
* Convert '/' to '\\'.
*/
for (i = 0; i < pathlen; i++) {
if (bootpath[i] == '/')
bootpath[i] = '\\';
}
for (i=pathlen; i>0; i--) {
if (bootpath[i] == '\\' && bootpath[i-1] == '\\')
bootpath[i] = '/';
else if (last == -1 && bootpath[i] == '\\')
last = i;
}
if (last == -1 && bootpath[0] == '\\')
last = 0;
bootpath[last+1] = '\0';
if (last > 0) {
for (i = 0, j = 0; bootpath[i] != '\0'; i++) {
if (bootpath[i] != '/') {
bootpath[j] = bootpath[i];
j++;
}
}
bootpath[j] = '\0';
}
while (*ImagePath == '\\')
ImagePath++;
*PathName = AllocatePool(StrSize(bootpath) + StrSize(ImagePath));
if (!*PathName) {
perror(L"Failed to allocate path buffer\n");
efi_status = EFI_OUT_OF_RESOURCES;
goto error;
}
*PathName[0] = '\0';
if (StrnCaseCmp(bootpath, ImagePath, StrLen(bootpath)))
StrCat(*PathName, bootpath);
StrCat(*PathName, ImagePath);
error:
FreePool(bootpath);
return efi_status;
}
/*
* Open the second stage bootloader and read it into a buffer
*/
static EFI_STATUS load_image (EFI_LOADED_IMAGE *li, void **data,
int *datasize, CHAR16 *PathName)
{
EFI_GUID simple_file_system_protocol = SIMPLE_FILE_SYSTEM_PROTOCOL;
EFI_GUID file_info_id = EFI_FILE_INFO_ID;
EFI_STATUS efi_status;
EFI_HANDLE device;
EFI_FILE_INFO *fileinfo = NULL;
EFI_FILE_IO_INTERFACE *drive;
EFI_FILE *root, *grub;
UINTN buffersize = sizeof(EFI_FILE_INFO);
device = li->DeviceHandle;
/*
* Open the device
*/
efi_status = uefi_call_wrapper(BS->HandleProtocol, 3, device,
&simple_file_system_protocol,
(void **)&drive);
if (efi_status != EFI_SUCCESS) {
perror(L"Failed to find fs: %r\n", efi_status);
goto error;
}
efi_status = uefi_call_wrapper(drive->OpenVolume, 2, drive, &root);
if (efi_status != EFI_SUCCESS) {
perror(L"Failed to open fs: %r\n", efi_status);
goto error;
}
/*
* And then open the file
*/
efi_status = uefi_call_wrapper(root->Open, 5, root, &grub, PathName,
EFI_FILE_MODE_READ, 0);
if (efi_status != EFI_SUCCESS) {
perror(L"Failed to open %s - %r\n", PathName, efi_status);
goto error;
}
fileinfo = AllocatePool(buffersize);
if (!fileinfo) {
perror(L"Unable to allocate file info buffer\n");
efi_status = EFI_OUT_OF_RESOURCES;
goto error;
}
/*
* Find out how big the file is in order to allocate the storage
* buffer
*/
efi_status = uefi_call_wrapper(grub->GetInfo, 4, grub, &file_info_id,
&buffersize, fileinfo);
if (efi_status == EFI_BUFFER_TOO_SMALL) {
FreePool(fileinfo);
fileinfo = AllocatePool(buffersize);
if (!fileinfo) {
perror(L"Unable to allocate file info buffer\n");
efi_status = EFI_OUT_OF_RESOURCES;
goto error;
}
efi_status = uefi_call_wrapper(grub->GetInfo, 4, grub,
&file_info_id, &buffersize,
fileinfo);
}
if (efi_status != EFI_SUCCESS) {
perror(L"Unable to get file info: %r\n", efi_status);
goto error;
}
buffersize = fileinfo->FileSize;
*data = AllocatePool(buffersize);
if (!*data) {
perror(L"Unable to allocate file buffer\n");
efi_status = EFI_OUT_OF_RESOURCES;
goto error;
}
/*
* Perform the actual read
*/
efi_status = uefi_call_wrapper(grub->Read, 3, grub, &buffersize,
*data);
if (efi_status == EFI_BUFFER_TOO_SMALL) {
FreePool(*data);
*data = AllocatePool(buffersize);
efi_status = uefi_call_wrapper(grub->Read, 3, grub,
&buffersize, *data);
}
if (efi_status != EFI_SUCCESS) {
perror(L"Unexpected return from initial read: %r, buffersize %x\n", efi_status, buffersize);
goto error;
}
*datasize = buffersize;
FreePool(fileinfo);
return EFI_SUCCESS;
error:
if (*data) {
FreePool(*data);
*data = NULL;
}
if (fileinfo)
FreePool(fileinfo);
return efi_status;
}
/*
* Protocol entry point. If secure boot is enabled, verify that the provided
* buffer is signed with a trusted key.
*/
EFI_STATUS shim_verify (void *buffer, UINT32 size)
{
EFI_STATUS status = EFI_SUCCESS;
PE_COFF_LOADER_IMAGE_CONTEXT context;
loader_is_participating = 1;
in_protocol = 1;
if (!secure_mode())
goto done;
status = read_header(buffer, size, &context);
if (status != EFI_SUCCESS)
goto done;
status = verify_buffer(buffer, size, &context);
done:
in_protocol = 0;
return status;
}
static EFI_STATUS shim_hash (char *data, int datasize,
PE_COFF_LOADER_IMAGE_CONTEXT *context,
UINT8 *sha256hash, UINT8 *sha1hash)
{
EFI_STATUS status;
in_protocol = 1;
status = generate_hash(data, datasize, context, sha256hash, sha1hash);
in_protocol = 0;
return status;
}
static EFI_STATUS shim_read_header(void *data, unsigned int datasize,
PE_COFF_LOADER_IMAGE_CONTEXT *context)
{
EFI_STATUS status;
in_protocol = 1;
status = read_header(data, datasize, context);
in_protocol = 0;
return status;
}
/*
* Load and run an EFI executable
*/
EFI_STATUS start_image(EFI_HANDLE image_handle, CHAR16 *ImagePath)
{
EFI_GUID loaded_image_protocol = LOADED_IMAGE_PROTOCOL;
EFI_STATUS efi_status;
EFI_LOADED_IMAGE *li, li_bak;
CHAR16 *PathName = NULL;
void *sourcebuffer = NULL;
UINT64 sourcesize = 0;
void *data = NULL;
int datasize;
/*
* We need to refer to the loaded image protocol on the running
* binary in order to find our path
*/
efi_status = uefi_call_wrapper(BS->HandleProtocol, 3, image_handle,
&loaded_image_protocol, (void **)&li);
if (efi_status != EFI_SUCCESS) {
perror(L"Unable to init protocol\n");
return efi_status;
}
/*
* Build a new path from the existing one plus the executable name
*/
efi_status = generate_path(li, ImagePath, &PathName);
if (efi_status != EFI_SUCCESS) {
perror(L"Unable to generate path %s: %r\n", ImagePath, efi_status);
goto done;
}
if (findNetboot(li->DeviceHandle)) {
efi_status = parseNetbootinfo(image_handle);
if (efi_status != EFI_SUCCESS) {
perror(L"Netboot parsing failed: %r\n", efi_status);
return EFI_PROTOCOL_ERROR;
}
efi_status = FetchNetbootimage(image_handle, &sourcebuffer,
&sourcesize);
if (efi_status != EFI_SUCCESS) {
perror(L"Unable to fetch TFTP image: %r\n", efi_status);
return efi_status;
}
data = sourcebuffer;
datasize = sourcesize;
#if defined(ENABLE_HTTPBOOT)
} else if (find_httpboot(li->DeviceHandle)) {
efi_status = httpboot_fetch_buffer (image_handle, &sourcebuffer,
&sourcesize);
if (efi_status != EFI_SUCCESS) {
perror(L"Unable to fetch HTTP image: %r\n", efi_status);
return efi_status;
}
data = sourcebuffer;
datasize = sourcesize;
#endif
} else {
/*
* Read the new executable off disk
*/
efi_status = load_image(li, &data, &datasize, PathName);
if (efi_status != EFI_SUCCESS) {
perror(L"Failed to load image %s: %r\n", PathName, efi_status);
goto done;
}
}
/* Measure the binary into the TPM */
tpm_log_event((EFI_PHYSICAL_ADDRESS)data, datasize, 9,
(CHAR8 *)"Second stage bootloader");
/*
* We need to modify the loaded image protocol entry before running
* the new binary, so back it up
*/
CopyMem(&li_bak, li, sizeof(li_bak));
/*
* Verify and, if appropriate, relocate and execute the executable
*/
efi_status = handle_image(data, datasize, li);
if (efi_status != EFI_SUCCESS) {
perror(L"Failed to load image: %r\n", efi_status);
CopyMem(li, &li_bak, sizeof(li_bak));
goto done;
}
loader_is_participating = 0;
/*
* The binary is trusted and relocated. Run it
*/
efi_status = uefi_call_wrapper(entry_point, 2, image_handle, systab);
/*
* Restore our original loaded image values
*/
CopyMem(li, &li_bak, sizeof(li_bak));
done:
if (PathName)
FreePool(PathName);
if (data)
FreePool(data);
return efi_status;
}
/*
* Load and run grub. If that fails because grub isn't trusted, load and
* run MokManager.
*/
EFI_STATUS init_grub(EFI_HANDLE image_handle)
{
EFI_STATUS efi_status;
int use_fb = should_use_fallback(image_handle);
efi_status = start_image(image_handle, use_fb ? FALLBACK :second_stage);
if (efi_status == EFI_SECURITY_VIOLATION) {
efi_status = start_image(image_handle, MOK_MANAGER);
if (efi_status != EFI_SUCCESS) {
Print(L"start_image() returned %r\n", efi_status);
uefi_call_wrapper(BS->Stall, 1, 2000000);
return efi_status;
}
efi_status = start_image(image_handle,
use_fb ? FALLBACK : second_stage);
}
if (efi_status != EFI_SUCCESS) {
Print(L"start_image() returned %r\n", efi_status);
uefi_call_wrapper(BS->Stall, 1, 2000000);
}
return efi_status;
}
/*
* Measure some of the MOK variables into the TPM
*/
EFI_STATUS measure_mok()
{
EFI_GUID shim_lock_guid = SHIM_LOCK_GUID;
EFI_STATUS efi_status;
UINT8 *Data = NULL;
UINTN DataSize = 0;
efi_status = get_variable(L"MokList", &Data, &DataSize, shim_lock_guid);
if (efi_status != EFI_SUCCESS)
return efi_status;
efi_status = tpm_log_event((EFI_PHYSICAL_ADDRESS)Data, DataSize, 14,
(CHAR8 *)"MokList");
FreePool(Data);
if (efi_status != EFI_SUCCESS)
return efi_status;
efi_status = get_variable(L"MokSBState", &Data, &DataSize,
shim_lock_guid);
if (efi_status != EFI_SUCCESS)
return efi_status;
efi_status = tpm_log_event((EFI_PHYSICAL_ADDRESS)Data, DataSize, 14,
(CHAR8 *)"MokSBState");
FreePool(Data);
return efi_status;
}
/*
* Copy the boot-services only MokList variable to the runtime-accessible
* MokListRT variable. It's not marked NV, so the OS can't modify it.
*/
EFI_STATUS mirror_mok_list()
{
EFI_GUID shim_lock_guid = SHIM_LOCK_GUID;
EFI_STATUS efi_status;
UINT8 *Data = NULL;
UINTN DataSize = 0;
void *FullData = NULL;
UINTN FullDataSize = 0;
EFI_SIGNATURE_LIST *CertList = NULL;
EFI_SIGNATURE_DATA *CertData = NULL;
uint8_t *p = NULL;
efi_status = get_variable(L"MokList", &Data, &DataSize, shim_lock_guid);
if (efi_status != EFI_SUCCESS)
DataSize = 0;
if (vendor_cert_size) {
FullDataSize = DataSize
+ sizeof (*CertList)
+ sizeof (EFI_GUID)
+ vendor_cert_size
;
FullData = AllocatePool(FullDataSize);
if (!FullData) {
perror(L"Failed to allocate space for MokListRT\n");
return EFI_OUT_OF_RESOURCES;
}
p = FullData;
if (efi_status == EFI_SUCCESS && DataSize > 0) {
CopyMem(p, Data, DataSize);
p += DataSize;
}
CertList = (EFI_SIGNATURE_LIST *)p;
p += sizeof (*CertList);
CertData = (EFI_SIGNATURE_DATA *)p;
p += sizeof (EFI_GUID);
CertList->SignatureType = EFI_CERT_X509_GUID;
CertList->SignatureListSize = vendor_cert_size
+ sizeof (*CertList)
+ sizeof (*CertData)
-1;
CertList->SignatureHeaderSize = 0;
CertList->SignatureSize = vendor_cert_size + sizeof (EFI_GUID);
CertData->SignatureOwner = SHIM_LOCK_GUID;
CopyMem(p, vendor_cert, vendor_cert_size);
} else {
FullDataSize = DataSize;
FullData = Data;
}
efi_status = uefi_call_wrapper(RT->SetVariable, 5, L"MokListRT",
&shim_lock_guid,
EFI_VARIABLE_BOOTSERVICE_ACCESS
| EFI_VARIABLE_RUNTIME_ACCESS,
FullDataSize, FullData);
if (efi_status != EFI_SUCCESS) {
perror(L"Failed to set MokListRT: %r\n", efi_status);
}
return efi_status;
}
/*
* Copy the boot-services only MokListX variable to the runtime-accessible
* MokListXRT variable. It's not marked NV, so the OS can't modify it.
*/
EFI_STATUS mirror_mok_list_x()
{
EFI_GUID shim_lock_guid = SHIM_LOCK_GUID;
EFI_STATUS efi_status;
UINT8 *Data = NULL;
UINTN DataSize = 0;
efi_status = get_variable(L"MokListX", &Data, &DataSize, shim_lock_guid);
if (efi_status != EFI_SUCCESS)
return efi_status;
efi_status = uefi_call_wrapper(RT->SetVariable, 5, L"MokListXRT",
&shim_lock_guid,
EFI_VARIABLE_BOOTSERVICE_ACCESS
| EFI_VARIABLE_RUNTIME_ACCESS,
DataSize, Data);
if (efi_status != EFI_SUCCESS) {
console_error(L"Failed to set MokListRT", efi_status);
}
return efi_status;
}
/*
* Copy the boot-services only MokSBState variable to the runtime-accessible
* MokSBStateRT variable. It's not marked NV, so the OS can't modify it.
*/
EFI_STATUS mirror_mok_sb_state()
{
EFI_GUID shim_lock_guid = SHIM_LOCK_GUID;
EFI_STATUS efi_status;
UINT8 *Data = NULL;
UINTN DataSize = 0;
efi_status = get_variable(L"MokSBState", &Data, &DataSize, shim_lock_guid);
if (efi_status != EFI_SUCCESS)
return efi_status;
efi_status = uefi_call_wrapper(RT->SetVariable, 5, L"MokSBStateRT",
&shim_lock_guid,
EFI_VARIABLE_BOOTSERVICE_ACCESS
| EFI_VARIABLE_RUNTIME_ACCESS,
DataSize, Data);
if (efi_status != EFI_SUCCESS) {
console_error(L"Failed to set MokSBStateRT", efi_status);
}
return efi_status;
}
/*
* Check if a variable exists
*/
static BOOLEAN check_var(CHAR16 *varname)
{
EFI_STATUS efi_status;
EFI_GUID shim_lock_guid = SHIM_LOCK_GUID;
UINTN size = sizeof(UINT32);
UINT32 MokVar;
UINT32 attributes;
efi_status = uefi_call_wrapper(RT->GetVariable, 5, varname,
&shim_lock_guid, &attributes,
&size, (void *)&MokVar);
if (efi_status == EFI_SUCCESS || efi_status == EFI_BUFFER_TOO_SMALL)
return TRUE;
return FALSE;
}
/*
* If the OS has set any of these variables we need to drop into MOK and
* handle them appropriately
*/
EFI_STATUS check_mok_request(EFI_HANDLE image_handle)
{
EFI_STATUS efi_status;
if (check_var(L"MokNew") || check_var(L"MokSB") ||
check_var(L"MokPW") || check_var(L"MokAuth") ||
check_var(L"MokDel") || check_var(L"MokDB") ||
check_var(L"MokXNew") || check_var(L"MokXDel") ||
check_var(L"MokXAuth")) {
efi_status = start_image(image_handle, MOK_MANAGER);
if (efi_status != EFI_SUCCESS) {
perror(L"Failed to start MokManager: %r\n", efi_status);
return efi_status;
}
}
return EFI_SUCCESS;
}
/*
* Verify that MokSBState is valid, and if appropriate set insecure mode
*/
static EFI_STATUS check_mok_sb (void)
{
EFI_GUID shim_lock_guid = SHIM_LOCK_GUID;
EFI_STATUS status = EFI_SUCCESS;
UINT8 MokSBState;
UINTN MokSBStateSize = sizeof(MokSBState);
UINT32 attributes;
user_insecure_mode = 0;
ignore_db = 0;
status = uefi_call_wrapper(RT->GetVariable, 5, L"MokSBState", &shim_lock_guid,
&attributes, &MokSBStateSize, &MokSBState);
if (status != EFI_SUCCESS)
return EFI_ACCESS_DENIED;
/*
* Delete and ignore the variable if it's been set from or could be
* modified by the OS
*/
if (attributes & EFI_VARIABLE_RUNTIME_ACCESS) {
perror(L"MokSBState is compromised! Clearing it\n");
if (LibDeleteVariable(L"MokSBState", &shim_lock_guid) != EFI_SUCCESS) {
perror(L"Failed to erase MokSBState\n");
}
status = EFI_ACCESS_DENIED;
} else {
if (MokSBState == 1) {
user_insecure_mode = 1;
}
}
return status;
}
/*
* Verify that MokDBState is valid, and if appropriate set ignore db mode
*/
static EFI_STATUS check_mok_db (void)
{
EFI_GUID shim_lock_guid = SHIM_LOCK_GUID;
EFI_STATUS status = EFI_SUCCESS;
UINT8 MokDBState;
UINTN MokDBStateSize = sizeof(MokDBState);
UINT32 attributes;
status = uefi_call_wrapper(RT->GetVariable, 5, L"MokDBState", &shim_lock_guid,
&attributes, &MokDBStateSize, &MokDBState);
if (status != EFI_SUCCESS)
return EFI_ACCESS_DENIED;
ignore_db = 0;
/*
* Delete and ignore the variable if it's been set from or could be
* modified by the OS
*/
if (attributes & EFI_VARIABLE_RUNTIME_ACCESS) {
perror(L"MokDBState is compromised! Clearing it\n");
if (LibDeleteVariable(L"MokDBState", &shim_lock_guid) != EFI_SUCCESS) {
perror(L"Failed to erase MokDBState\n");
}
status = EFI_ACCESS_DENIED;
} else {
if (MokDBState == 1) {
ignore_db = 1;
}
}
return status;
}
static EFI_STATUS mok_ignore_db()
{
EFI_GUID shim_lock_guid = SHIM_LOCK_GUID;
EFI_STATUS efi_status = EFI_SUCCESS;
UINT8 Data = 1;
UINTN DataSize = sizeof(UINT8);
check_mok_db();
if (ignore_db) {
efi_status = uefi_call_wrapper(RT->SetVariable, 5, L"MokIgnoreDB",
&shim_lock_guid,
EFI_VARIABLE_BOOTSERVICE_ACCESS
| EFI_VARIABLE_RUNTIME_ACCESS,
DataSize, (void *)&Data);
if (efi_status != EFI_SUCCESS) {
perror(L"Failed to set MokIgnoreDB: %r\n", efi_status);
}
}
return efi_status;
}
EFI_GUID bds_guid = { 0x8108ac4e, 0x9f11, 0x4d59, { 0x85, 0x0e, 0xe2, 0x1a, 0x52, 0x2c, 0x59, 0xb2 } };
static inline EFI_STATUS
get_load_option_optional_data(UINT8 *data, UINTN data_size,
UINT8 **od, UINTN *ods)
{
/*
* If it's not at least Attributes + FilePathListLength +
* Description=L"" + 0x7fff0400 (EndEntrireDevicePath), it can't
* be valid.
*/
if (data_size < (sizeof(UINT32) + sizeof(UINT16) + 2 + 4))
return EFI_INVALID_PARAMETER;
UINT8 *cur = data + sizeof(UINT32);
UINT16 fplistlen = *(UINT16 *)cur;
/*
* If there's not enough space for the file path list and the
* smallest possible description (L""), it's not valid.
*/
if (fplistlen > data_size - (sizeof(UINT32) + 2 + 4))
return EFI_INVALID_PARAMETER;
cur += sizeof(UINT16);
UINTN limit = data_size - (cur - data) - fplistlen;
UINTN i;
for (i = 0; i < limit ; i++) {
/* If the description isn't valid UCS2-LE, it's not valid. */
if (i % 2 != 0) {
if (cur[i] != 0)
return EFI_INVALID_PARAMETER;
} else if (cur[i] == 0) {
/* we've found the end */
i++;
if (i >= limit || cur[i] != 0)
return EFI_INVALID_PARAMETER;
break;
}
}
i++;
if (i > limit)
return EFI_INVALID_PARAMETER;
/*
* If i is limit, we know the rest of this is the FilePathList and
* there's no optional data. So just bail now.
*/
if (i == limit) {
*od = NULL;
*ods = 0;
return EFI_SUCCESS;
}
cur += i;
limit -= i;
limit += fplistlen;
i = 0;
while (limit - i >= 4) {
struct {
UINT8 type;
UINT8 subtype;
UINT16 len;
} dp = {
.type = cur[i],
.subtype = cur[i+1],
/*
* it's a little endian UINT16, but we're not
* guaranteed alignment is sane, so we can't just
* typecast it directly.
*/
.len = (cur[i+3] << 8) | cur[i+2],
};
/*
* We haven't found an EndEntire, so this has to be a valid
* EFI_DEVICE_PATH in order for the data to be valid. That
* means it has to fit, and it can't be smaller than 4 bytes.
*/
if (dp.len < 4 || dp.len > limit)
return EFI_INVALID_PARAMETER;
/*
* see if this is an EndEntire node...
*/
if (dp.type == 0x7f && dp.subtype == 0xff) {
/*
* if we've found the EndEntire node, it must be 4
* bytes
*/
if (dp.len != 4)
return EFI_INVALID_PARAMETER;
i += dp.len;
break;
}
/*
* It's just some random DP node; skip it.
*/
i += dp.len;
}
if (i != fplistlen)
return EFI_INVALID_PARAMETER;
/*
* if there's any space left, it's "optional data"
*/
*od = cur + i;
*ods = limit - i;
return EFI_SUCCESS;
}
/*
* Check the load options to specify the second stage loader
*/
EFI_STATUS set_second_stage (EFI_HANDLE image_handle)
{
EFI_STATUS status;
EFI_LOADED_IMAGE *li;
CHAR16 *start = NULL;
int remaining_size = 0;
CHAR16 *loader_str = NULL;
UINTN loader_len = 0;
unsigned int i;
second_stage = DEFAULT_LOADER;
load_options = NULL;
load_options_size = 0;
status = uefi_call_wrapper(BS->HandleProtocol, 3, image_handle,
&LoadedImageProtocol, (void **) &li);
if (status != EFI_SUCCESS) {
perror (L"Failed to get load options: %r\n", status);
return status;
}
/* So, load options are a giant pain in the ass. If we're invoked
* from the EFI shell, we get something like this:
00000000 5c 00 45 00 36 00 49 00 5c 00 66 00 65 00 64 00 |\.E.F.I.\.f.e.d.|
00000010 6f 00 72 00 61 00 5c 00 73 00 68 00 69 00 6d 00 |o.r.a.\.s.h.i.m.|
00000020 78 00 36 00 34 00 2e 00 64 00 66 00 69 00 20 00 |x.6.4...e.f.i. .|
00000030 5c 00 45 00 46 00 49 00 5c 00 66 00 65 00 64 00 |\.E.F.I.\.f.e.d.|
00000040 6f 00 72 00 61 00 5c 00 66 00 77 00 75 00 70 00 |o.r.a.\.f.w.u.p.|
00000050 64 00 61 00 74 00 65 00 2e 00 65 00 66 00 20 00 |d.a.t.e.e.f.i. .|
00000060 00 00 66 00 73 00 30 00 3a 00 5c 00 00 00 |..f.s.0.:.\...|
*
* which is just some paths rammed together separated by a UCS-2 NUL.
* But if we're invoked from BDS, we get something more like:
*
00000000 01 00 00 00 62 00 4c 00 69 00 6e 00 75 00 78 00 |....b.L.i.n.u.x.|
00000010 20 00 46 00 69 00 72 00 6d 00 77 00 61 00 72 00 | .F.i.r.m.w.a.r.|
00000020 65 00 20 00 55 00 70 00 64 00 61 00 74 00 65 00 |e. .U.p.d.a.t.e.|
00000030 72 00 00 00 40 01 2a 00 01 00 00 00 00 08 00 00 |r.....*.........|
00000040 00 00 00 00 00 40 06 00 00 00 00 00 1a 9e 55 bf |.....@........U.|
00000050 04 57 f2 4f b4 4a ed 26 4a 40 6a 94 02 02 04 04 |.W.O.:.&J@j.....|
00000060 34 00 5c 00 45 00 46 00 49 00 5c 00 66 00 65 00 |4.\.E.F.I.f.e.d.|
00000070 64 00 6f 00 72 00 61 00 5c 00 73 00 68 00 69 00 |o.r.a.\.s.h.i.m.|
00000080 6d 00 78 00 36 00 34 00 2e 00 65 00 66 00 69 00 |x.6.4...e.f.i...|
00000090 00 00 7f ff 40 00 20 00 5c 00 66 00 77 00 75 00 |...... .\.f.w.u.|
000000a0 70 00 78 00 36 00 34 00 2e 00 65 00 66 00 69 00 |p.x.6.4...e.f.i.|
000000b0 00 00 |..|
*
* which is clearly an EFI_LOAD_OPTION filled in halfway reasonably.
* In short, the UEFI shell is still a useless piece of junk.
*
* But then on some versions of BDS, we get:
00000000 5c 00 66 00 77 00 75 00 70 00 78 00 36 00 34 00 |\.f.w.u.p.x.6.4.|
00000010 2e 00 65 00 66 00 69 00 00 00 |..e.f.i...|
0000001a
* which as you can see is one perfectly normal UCS2-EL string
* containing the load option from the Boot#### variable.
*
* We also sometimes find a guid or partial guid at the end, because
* BDS will add that, but we ignore that here.
*/
/*
* In either case, we've got to have at least a UCS2 NUL...
*/
if (li->LoadOptionsSize < 2)
return EFI_BAD_BUFFER_SIZE;
/*
* Some awesome versions of BDS will add entries for Linux. On top
* of that, some versions of BDS will "tag" any Boot#### entries they
* create by putting a GUID at the very end of the optional data in
* the EFI_LOAD_OPTIONS, thus screwing things up for everybody who
* tries to actually *use* the optional data for anything. Why they
* did this instead of adding a flag to the spec to /say/ it's
* created by BDS, I do not know. For shame.
*
* Anyway, just nerf that out from the start. It's always just
* garbage at the end.
*/
if (li->LoadOptionsSize > 16) {
if (CompareGuid((EFI_GUID *)(li->LoadOptions
+ (li->LoadOptionsSize - 16)),
&bds_guid) == 0)
li->LoadOptionsSize -= 16;
}
/*
* Check and see if this is just a list of strings. If it's an
* EFI_LOAD_OPTION, it'll be 0, since we know EndEntire device path
* won't pass muster as UCS2-LE.
*
* If there are 3 strings, we're launched from the shell most likely,
* But we actually only care about the second one.
*/
UINTN strings = count_ucs2_strings(li->LoadOptions,
li->LoadOptionsSize);
/*
* If it's not string data, try it as an EFI_LOAD_OPTION.
*/
if (strings == 0) {
/*
* We at least didn't find /enough/ strings. See if it works
* as an EFI_LOAD_OPTION.
*/
status = get_load_option_optional_data(li->LoadOptions,
li->LoadOptionsSize,
(UINT8 **)&start,
&loader_len);
if (status != EFI_SUCCESS)
return EFI_SUCCESS;
remaining_size = 0;
} else if (strings >= 2) {
/*
* UEFI shell copies the whole line of the command into
* LoadOptions. We ignore the string before the first L' ',
* i.e. the name of this program.
* Counting by two bytes is safe, because we know the size is
* compatible with a UCS2-LE string.
*/
UINT8 *cur = li->LoadOptions;
for (i = 0; i < li->LoadOptionsSize - 2; i += 2) {
CHAR16 c = (cur[i+1] << 8) | cur[i];
if (c == L' ') {
start = (CHAR16 *)&cur[i+2];
remaining_size = li->LoadOptionsSize - i - 2;
break;
}
}
if (!start || remaining_size <= 0 || start[0] == L'\0')
return EFI_SUCCESS;
for (i = 0; start[i] != '\0'; i++) {
if (start[i] == L' ')
start[i] = L'\0';
if (start[i] == L'\0') {
loader_len = 2 * i + 2;
break;
}
}
if (loader_len)
remaining_size -= loader_len;
} else {
/* only find one string */
start = li->LoadOptions;
loader_len = li->LoadOptionsSize;
}
/*
* Just to be sure all that math is right...
*/
if (loader_len % 2 != 0)
return EFI_INVALID_PARAMETER;
strings = count_ucs2_strings((UINT8 *)start, loader_len);
if (strings < 1)
return EFI_SUCCESS;
/*
* Set up the name of the alternative loader and the LoadOptions for
* the loader
*/
if (loader_len > 0) {
loader_str = AllocatePool(loader_len);
if (!loader_str) {
perror(L"Failed to allocate loader string\n");
return EFI_OUT_OF_RESOURCES;
}
for (i = 0; i < loader_len / 2; i++)
loader_str[i] = start[i];
loader_str[loader_len/2-1] = L'\0';
second_stage = loader_str;
load_options = remaining_size ? start + loader_len : NULL;
load_options_size = remaining_size;
}
return EFI_SUCCESS;
}
static SHIM_LOCK shim_lock_interface;
static EFI_HANDLE shim_lock_handle;
EFI_STATUS
install_shim_protocols(void)
{
EFI_GUID shim_lock_guid = SHIM_LOCK_GUID;
EFI_STATUS efi_status;
if (!secure_mode())
return EFI_SUCCESS;
/*
* Install the protocol
*/
efi_status = uefi_call_wrapper(BS->InstallProtocolInterface, 4,
&shim_lock_handle, &shim_lock_guid,
EFI_NATIVE_INTERFACE, &shim_lock_interface);
if (EFI_ERROR(efi_status)) {
console_error(L"Could not install security protocol",
efi_status);
return efi_status;
}
#if defined(OVERRIDE_SECURITY_POLICY)
/*
* Install the security protocol hook
*/
security_policy_install(shim_verify);
#endif
return EFI_SUCCESS;
}
void
uninstall_shim_protocols(void)
{
EFI_GUID shim_lock_guid = SHIM_LOCK_GUID;
if (!secure_mode())
return;
#if defined(OVERRIDE_SECURITY_POLICY)
/*
* Clean up the security protocol hook
*/
security_policy_uninstall();
#endif
/*
* If we're back here then clean everything up before exiting
*/
uefi_call_wrapper(BS->UninstallProtocolInterface, 3, shim_lock_handle,
&shim_lock_guid, &shim_lock_interface);
}
EFI_STATUS
shim_init(void)
{
EFI_STATUS status = EFI_SUCCESS;
setup_console(1);
setup_verbosity();
dprinta(shim_version);
/* Set the second stage loader */
set_second_stage (image_handle);
if (secure_mode()) {
if (vendor_cert_size || vendor_dbx_size) {
/*
* If shim includes its own certificates then ensure
* that anything it boots has performed some
* validation of the next image.
*/
hook_system_services(systab);
loader_is_participating = 0;
}
hook_exit(systab);
status = install_shim_protocols();
}
return status;
}
void
shim_fini(void)
{
if (secure_mode()) {
/*
* Remove our protocols
*/
uninstall_shim_protocols();
/*
* Remove our hooks from system services.
*/
unhook_system_services();
unhook_exit();
}
/*
* Free the space allocated for the alternative 2nd stage loader
*/
if (load_options_size > 0 && second_stage)
FreePool(second_stage);
setup_console(0);
}
extern EFI_STATUS
efi_main(EFI_HANDLE passed_image_handle, EFI_SYSTEM_TABLE *passed_systab);
static void
__attribute__((__optimize__("0")))
debug_hook(void)
{
EFI_GUID guid = SHIM_LOCK_GUID;
UINT8 *data = NULL;
UINTN dataSize = 0;
EFI_STATUS efi_status;
volatile register UINTN x = 0;
extern char _text, _data;
if (x)
return;
efi_status = get_variable(L"SHIM_DEBUG", &data, &dataSize, guid);
if (EFI_ERROR(efi_status)) {
return;
}
Print(L"add-symbol-file "DEBUGDIR
L"shim" EFI_ARCH L".efi.debug 0x%08x -s .data 0x%08x\n", &_text,
&_data);
Print(L"Pausing for debugger attachment.\n");
Print(L"To disable this, remove the EFI variable SHIM_DEBUG-%g .\n",
&guid);
x = 1;
while (x++) {
/* Make this so it can't /totally/ DoS us. */
#if defined(__x86_64__) || defined(__i386__) || defined(__i686__)
if (x > 4294967294ULL)
break;
__asm__ __volatile__("pause");
#elif defined(__aarch64__)
if (x > 1000)
break;
__asm__ __volatile__("wfi");
#else
if (x > 12000)
break;
uefi_call_wrapper(BS->Stall, 1, 5000);
#endif
}
x = 1;
}
EFI_STATUS
efi_main (EFI_HANDLE passed_image_handle, EFI_SYSTEM_TABLE *passed_systab)
{
EFI_STATUS efi_status;
verification_method = VERIFIED_BY_NOTHING;
vendor_cert_size = cert_table.vendor_cert_size;
vendor_dbx_size = cert_table.vendor_dbx_size;
vendor_cert = (UINT8 *)&cert_table + cert_table.vendor_cert_offset;
vendor_dbx = (UINT8 *)&cert_table + cert_table.vendor_dbx_offset;
/*
* Set up the shim lock protocol so that grub and MokManager can
* call back in and use shim functions
*/
shim_lock_interface.Verify = shim_verify;
shim_lock_interface.Hash = shim_hash;
shim_lock_interface.Context = shim_read_header;
systab = passed_systab;
image_handle = passed_image_handle;
/*
* Ensure that gnu-efi functions are available
*/
InitializeLib(image_handle, systab);
/*
* if SHIM_DEBUG is set, wait for a debugger to attach.
*/
debug_hook();
/*
* Measure the MOK variables
*/
efi_status = measure_mok();
if (efi_status != EFI_SUCCESS && efi_status != EFI_NOT_FOUND) {
Print(L"Something has gone seriously wrong: %r\n", efi_status);
Print(L"Shim was unable to measure state into the TPM\n");
systab->BootServices->Stall(5000000);
systab->RuntimeServices->ResetSystem(EfiResetShutdown,
EFI_SECURITY_VIOLATION,
0, NULL);
}
/*
* Check whether the user has configured the system to run in
* insecure mode
*/
check_mok_sb();
efi_status = shim_init();
if (EFI_ERROR(efi_status)) {
Print(L"Something has gone seriously wrong: %r\n", efi_status);
Print(L"shim cannot continue, sorry.\n");
uefi_call_wrapper(BS->Stall, 1, 5000000);
uefi_call_wrapper(systab->RuntimeServices->ResetSystem, 4,
EfiResetShutdown, EFI_SECURITY_VIOLATION,
0, NULL);
}
/*
* Tell the user that we're in insecure mode if necessary
*/
if (user_insecure_mode) {
Print(L"Booting in insecure mode\n");
uefi_call_wrapper(BS->Stall, 1, 2000000);
}
/*
* Enter MokManager if necessary
*/
efi_status = check_mok_request(image_handle);
/*
* Copy the MOK list to a runtime variable so the kernel can
* make use of it
*/
efi_status = mirror_mok_list();
efi_status = mirror_mok_list_x();
/*
* Copy the MOK SB State to a runtime variable so the kernel can
* make use of it
*/
efi_status = mirror_mok_sb_state();
/*
* Create the runtime MokIgnoreDB variable so the kernel can
* make use of it
*/
efi_status = mok_ignore_db();
/*
* Hand over control to the second stage bootloader
*/
efi_status = init_grub(image_handle);
shim_fini();
return efi_status;
}
Reference in New Issue View Git Blame Copy Permalink