EnrollDefaultKeys.c

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#include <Guid/AuthenticatedVariableFormat.h>    // gEfiCustomModeEnableGuid
#include <Guid/GlobalVariable.h>                 // EFI_SETUP_MODE_NAME
#include <Guid/ImageAuthentication.h>            // EFI_IMAGE_SECURITY_DATABASE
#include <Guid/MicrosoftVendor.h>                // gMicrosoftVendorGuid
#include <Guid/OvmfPkKek1AppPrefix.h>            // gOvmfPkKek1AppPrefixGuid
#include <IndustryStandard/SmBios.h>             // SMBIOS_HANDLE_PI_RESERVED
#include <Library/BaseLib.h>                     // GUID_STRING_LENGTH
#include <Library/BaseMemoryLib.h>               // CopyGuid()
#include <Library/DebugLib.h>                    // ASSERT()
#include <Library/MemoryAllocationLib.h>         // FreePool()
#include <Library/PrintLib.h>                    // AsciiSPrint()
#include <Library/ShellCEntryLib.h>              // ShellAppMain()
#include <Library/UefiBootServicesTableLib.h>    // gBS
#include <Library/UefiLib.h>                     // AsciiPrint()
#include <Library/UefiRuntimeServicesTableLib.h> // gRT
#include <Protocol/Smbios.h>                     // EFI_SMBIOS_PROTOCOL
 
#include "EnrollDefaultKeys.h"
 
STATIC
EFI_STATUS
GetPkKek1 (
  OUT UINT8  **PkKek1,
  OUT UINTN  *SizeOfPkKek1
  )
{
  CONST CHAR8              *Base64Cert;
  CHAR8                    OvmfPkKek1AppPrefix[GUID_STRING_LENGTH + 1 + 1];
  EFI_STATUS               Status;
  EFI_SMBIOS_PROTOCOL      *Smbios;
  EFI_SMBIOS_HANDLE        Handle;
  EFI_SMBIOS_TYPE          Type;
  EFI_SMBIOS_TABLE_HEADER  *Header;
  SMBIOS_TABLE_TYPE11      *OemStringsTable;
  UINTN                    Base64CertLen;
  UINTN                    DecodedCertSize;
  UINT8                    *DecodedCert;
 
  Base64Cert = NULL;
 
  //
  // Format the application prefix, for OEM String matching.
  //
  AsciiSPrint (
    OvmfPkKek1AppPrefix,
    sizeof OvmfPkKek1AppPrefix,
    "%g:",
    &gOvmfPkKek1AppPrefixGuid
    );
 
  //
  // Scan all "OEM Strings" tables.
  //
  Status = gBS->LocateProtocol (
                  &gEfiSmbiosProtocolGuid,
                  NULL,
                  (VOID **)&Smbios
                  );
  if (EFI_ERROR (Status)) {
    AsciiPrint ("error: failed to locate EFI_SMBIOS_PROTOCOL: %r\n", Status);
    return Status;
  }
 
  Handle = SMBIOS_HANDLE_PI_RESERVED;
  Type   = SMBIOS_TYPE_OEM_STRINGS;
  for (Status = Smbios->GetNext (Smbios, &Handle, &Type, &Header, NULL);
       !EFI_ERROR (Status);
       Status = Smbios->GetNext (Smbios, &Handle, &Type, &Header, NULL))
  {
    CONST CHAR8  *OemString;
    UINTN        Idx;
 
    if (Header->Length < sizeof *OemStringsTable) {
      //
      // Malformed table header, skip to next.
      //
      continue;
    }
 
    OemStringsTable = (SMBIOS_TABLE_TYPE11 *)Header;
 
    //
    // Scan all strings in the unformatted area of the current "OEM Strings"
    // table.
    //
    OemString = (CONST CHAR8 *)(OemStringsTable + 1);
    for (Idx = 0; Idx < OemStringsTable->StringCount; ++Idx) {
      CHAR8  CandidatePrefix[sizeof OvmfPkKek1AppPrefix];
 
      //
      // NUL-terminate the candidate prefix for case-insensitive comparison.
      //
      AsciiStrnCpyS (
        CandidatePrefix,
        sizeof CandidatePrefix,
        OemString,
        GUID_STRING_LENGTH + 1
        );
      if (AsciiStriCmp (OvmfPkKek1AppPrefix, CandidatePrefix) == 0) {
        //
        // The current string matches the prefix.
        //
        Base64Cert = OemString + GUID_STRING_LENGTH + 1;
        break;
      }
 
      OemString += AsciiStrSize (OemString);
    }
 
    if (Idx < OemStringsTable->StringCount) {
      //
      // The current table has a matching string.
      //
      break;
    }
  }
 
  if (EFI_ERROR (Status)) {
    //
    // No table with a matching string has been found.
    //
    AsciiPrint (
      "error: OEM String with app prefix %g not found: %r\n",
      &gOvmfPkKek1AppPrefixGuid,
      Status
      );
    return EFI_NOT_FOUND;
  }
 
  ASSERT (Base64Cert != NULL);
  Base64CertLen = AsciiStrLen (Base64Cert);
 
  //
  // Verify the base64 encoding, and determine the decoded size.
  //
  DecodedCertSize = 0;
  Status          = Base64Decode (Base64Cert, Base64CertLen, NULL, &DecodedCertSize);
  switch (Status) {
    case EFI_BUFFER_TOO_SMALL:
      ASSERT (DecodedCertSize > 0);
      break;
    case EFI_SUCCESS:
      AsciiPrint (
        "error: empty certificate after app prefix %g\n",
        &gOvmfPkKek1AppPrefixGuid
        );
      return EFI_PROTOCOL_ERROR;
    default:
      AsciiPrint (
        "error: invalid base64 string after app prefix %g\n",
        &gOvmfPkKek1AppPrefixGuid
        );
      return EFI_PROTOCOL_ERROR;
  }
 
  //
  // Allocate the output buffer.
  //
  DecodedCert = AllocatePool (DecodedCertSize);
  if (DecodedCert == NULL) {
    AsciiPrint ("error: failed to allocate memory\n");
    return EFI_OUT_OF_RESOURCES;
  }
 
  //
  // Decoding will succeed at this point.
  //
  Status = Base64Decode (
             Base64Cert,
             Base64CertLen,
             DecodedCert,
             &DecodedCertSize
             );
  ASSERT_EFI_ERROR (Status);
 
  *PkKek1       = DecodedCert;
  *SizeOfPkKek1 = DecodedCertSize;
  return EFI_SUCCESS;
}
 
STATIC
EFI_STATUS
EFIAPI
EnrollListOfCerts (
  IN CHAR16    *VariableName,
  IN EFI_GUID  *VendorGuid,
  IN EFI_GUID  *CertType,
  ...
  )
{
  UINTN             DataSize;
  SINGLE_HEADER     *SingleHeader;
  REPEATING_HEADER  *RepeatingHeader;
  VA_LIST           Marker;
  CONST UINT8       *Cert;
  EFI_STATUS        Status;
  UINT8             *Data;
  UINT8             *Position;
 
  Status = EFI_SUCCESS;
 
  //
  // compute total size first, for UINT32 range check, and allocation
  //
  DataSize = sizeof *SingleHeader;
  VA_START (Marker, CertType);
  for (Cert = VA_ARG (Marker, CONST UINT8 *);
       Cert != NULL;
       Cert = VA_ARG (Marker, CONST UINT8 *))
  {
    UINTN  CertSize;
 
    CertSize = VA_ARG (Marker, UINTN);
    (VOID)VA_ARG (Marker, CONST EFI_GUID *);
 
    if ((CertSize == 0) ||
        (CertSize > MAX_UINT32 - sizeof *RepeatingHeader) ||
        (DataSize > MAX_UINT32 - sizeof *RepeatingHeader - CertSize))
    {
      Status = EFI_INVALID_PARAMETER;
      break;
    }
 
    DataSize += sizeof *RepeatingHeader + CertSize;
  }
 
  VA_END (Marker);
 
  if (DataSize == sizeof *SingleHeader) {
    Status = EFI_INVALID_PARAMETER;
  }
 
  if (EFI_ERROR (Status)) {
    goto Out;
  }
 
  Data = AllocatePool (DataSize);
  if (Data == NULL) {
    Status = EFI_OUT_OF_RESOURCES;
    goto Out;
  }
 
  Position = Data;
 
  SingleHeader = (SINGLE_HEADER *)Position;
  Status       = gRT->GetTime (&SingleHeader->TimeStamp, NULL);
  if (EFI_ERROR (Status)) {
    goto FreeData;
  }
 
  SingleHeader->TimeStamp.Pad1       = 0;
  SingleHeader->TimeStamp.Nanosecond = 0;
  SingleHeader->TimeStamp.TimeZone   = 0;
  SingleHeader->TimeStamp.Daylight   = 0;
  SingleHeader->TimeStamp.Pad2       = 0;
 #if 0
  SingleHeader->dwLength = DataSize - sizeof SingleHeader->TimeStamp;
 #else
  //
  // This looks like a bug in edk2. According to the UEFI specification,
  // dwLength is "The length of the entire certificate, including the length of
  // the header, in bytes". That shouldn't stop right after CertType -- it
  // should include everything below it.
  //
  SingleHeader->dwLength = sizeof *SingleHeader
                           - sizeof SingleHeader->TimeStamp;
 #endif
  SingleHeader->wRevision        = 0x0200;
  SingleHeader->wCertificateType = WIN_CERT_TYPE_EFI_GUID;
  CopyGuid (&SingleHeader->CertType, &gEfiCertPkcs7Guid);
  Position += sizeof *SingleHeader;
 
  VA_START (Marker, CertType);
  for (Cert = VA_ARG (Marker, CONST UINT8 *);
       Cert != NULL;
       Cert = VA_ARG (Marker, CONST UINT8 *))
  {
    UINTN           CertSize;
    CONST EFI_GUID  *OwnerGuid;
 
    CertSize  = VA_ARG (Marker, UINTN);
    OwnerGuid = VA_ARG (Marker, CONST EFI_GUID *);
 
    RepeatingHeader = (REPEATING_HEADER *)Position;
    CopyGuid (&RepeatingHeader->SignatureType, CertType);
    RepeatingHeader->SignatureListSize =
      (UINT32)(sizeof *RepeatingHeader + CertSize);
    RepeatingHeader->SignatureHeaderSize = 0;
    RepeatingHeader->SignatureSize       =
      (UINT32)(sizeof RepeatingHeader->SignatureOwner + CertSize);
    CopyGuid (&RepeatingHeader->SignatureOwner, OwnerGuid);
    Position += sizeof *RepeatingHeader;
 
    CopyMem (Position, Cert, CertSize);
    Position += CertSize;
  }
 
  VA_END (Marker);
 
  ASSERT (Data + DataSize == Position);
 
  Status = gRT->SetVariable (
                  VariableName,
                  VendorGuid,
                  (EFI_VARIABLE_NON_VOLATILE |
                   EFI_VARIABLE_BOOTSERVICE_ACCESS |
                   EFI_VARIABLE_RUNTIME_ACCESS |
                   EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS),
                  DataSize,
                  Data
                  );
 
FreeData:
  FreePool (Data);
 
Out:
  if (EFI_ERROR (Status)) {
    AsciiPrint (
      "error: %a(\"%s\", %g): %r\n",
      __func__,
      VariableName,
      VendorGuid,
      Status
      );
  }
 
  return Status;
}
 
STATIC
EFI_STATUS
GetExact (
  IN CHAR16    *VariableName,
  IN EFI_GUID  *VendorGuid,
  OUT VOID     *Data,
  IN UINTN     DataSize,
  IN BOOLEAN   AllowMissing
  )
{
  UINTN       Size;
  EFI_STATUS  Status;
 
  Size   = DataSize;
  Status = gRT->GetVariable (VariableName, VendorGuid, NULL, &Size, Data);
  if (EFI_ERROR (Status)) {
    if ((Status == EFI_NOT_FOUND) && AllowMissing) {
      ZeroMem (Data, DataSize);
      return EFI_SUCCESS;
    }
 
    AsciiPrint (
      "error: GetVariable(\"%s\", %g): %r\n",
      VariableName,
      VendorGuid,
      Status
      );
    return Status;
  }
 
  if (Size != DataSize) {
    AsciiPrint (
      "error: GetVariable(\"%s\", %g): expected size 0x%Lx, "
      "got 0x%Lx\n",
      VariableName,
      VendorGuid,
      (UINT64)DataSize,
      (UINT64)Size
      );
    return EFI_PROTOCOL_ERROR;
  }
 
  return EFI_SUCCESS;
}
 
STATIC
EFI_STATUS
GetSettings (
  OUT SETTINGS  *Settings
  )
{
  EFI_STATUS  Status;
 
  Status = GetExact (
             EFI_SETUP_MODE_NAME,
             &gEfiGlobalVariableGuid,
             &Settings->SetupMode,
             sizeof Settings->SetupMode,
             FALSE
             );
  if (EFI_ERROR (Status)) {
    return Status;
  }
 
  Status = GetExact (
             EFI_SECURE_BOOT_MODE_NAME,
             &gEfiGlobalVariableGuid,
             &Settings->SecureBoot,
             sizeof Settings->SecureBoot,
             FALSE
             );
  if (EFI_ERROR (Status)) {
    return Status;
  }
 
  Status = GetExact (
             EFI_SECURE_BOOT_ENABLE_NAME,
             &gEfiSecureBootEnableDisableGuid,
             &Settings->SecureBootEnable,
             sizeof Settings->SecureBootEnable,
             TRUE
             );
  if (EFI_ERROR (Status)) {
    return Status;
  }
 
  Status = GetExact (
             EFI_CUSTOM_MODE_NAME,
             &gEfiCustomModeEnableGuid,
             &Settings->CustomMode,
             sizeof Settings->CustomMode,
             FALSE
             );
  if (EFI_ERROR (Status)) {
    return Status;
  }
 
  Status = GetExact (
             EFI_VENDOR_KEYS_VARIABLE_NAME,
             &gEfiGlobalVariableGuid,
             &Settings->VendorKeys,
             sizeof Settings->VendorKeys,
             FALSE
             );
  return Status;
}
 
STATIC
VOID
PrintSettings (
  IN CONST SETTINGS  *Settings
  )
{
  AsciiPrint (
    "info: SetupMode=%d SecureBoot=%d SecureBootEnable=%d "
    "CustomMode=%d VendorKeys=%d\n",
    Settings->SetupMode,
    Settings->SecureBoot,
    Settings->SecureBootEnable,
    Settings->CustomMode,
    Settings->VendorKeys
    );
}
 
INTN
EFIAPI
ShellAppMain (
  IN UINTN   Argc,
  IN CHAR16  **Argv
  )
{
  INTN        RetVal;
  EFI_STATUS  Status;
  SETTINGS    Settings;
  UINT8       *PkKek1;
  UINTN       SizeOfPkKek1;
  BOOLEAN     NoDefault;
 
  if ((Argc == 2) && (StrCmp (Argv[1], L"--no-default") == 0)) {
    NoDefault = TRUE;
  } else {
    NoDefault = FALSE;
  }
 
  //
  // Prepare for failure.
  //
  RetVal = 1;
 
  //
  // If we're not in Setup Mode, we can't do anything.
  //
  Status = GetSettings (&Settings);
  if (EFI_ERROR (Status)) {
    return RetVal;
  }
 
  PrintSettings (&Settings);
 
  if (Settings.SetupMode != 1) {
    AsciiPrint ("error: already in User Mode\n");
    return RetVal;
  }
 
  //
  // Set PkKek1 and SizeOfPkKek1 to suppress incorrect compiler/analyzer
  // warnings.
  //
  PkKek1       = NULL;
  SizeOfPkKek1 = 0;
 
  //
  // Fetch the X509 certificate (to be used as Platform Key and first Key
  // Exchange Key) from SMBIOS.
  //
  Status = GetPkKek1 (&PkKek1, &SizeOfPkKek1);
  if (EFI_ERROR (Status)) {
    return RetVal;
  }
 
  //
  // Enter Custom Mode so we can enroll PK, KEK, db, and dbx without signature
  // checks on those variable writes.
  //
  if (Settings.CustomMode != CUSTOM_SECURE_BOOT_MODE) {
    Settings.CustomMode = CUSTOM_SECURE_BOOT_MODE;
    Status              = gRT->SetVariable (
                                 EFI_CUSTOM_MODE_NAME,
                                 &gEfiCustomModeEnableGuid,
                                 (EFI_VARIABLE_NON_VOLATILE |
                                  EFI_VARIABLE_BOOTSERVICE_ACCESS),
                                 sizeof Settings.CustomMode,
                                 &Settings.CustomMode
                                 );
    if (EFI_ERROR (Status)) {
      AsciiPrint (
        "error: SetVariable(\"%s\", %g): %r\n",
        EFI_CUSTOM_MODE_NAME,
        &gEfiCustomModeEnableGuid,
        Status
        );
      goto FreePkKek1;
    }
  }
 
  //
  // Enroll db.
  //
  if (NoDefault) {
    Status = EnrollListOfCerts (
               EFI_IMAGE_SECURITY_DATABASE,
               &gEfiImageSecurityDatabaseGuid,
               &gEfiCertX509Guid,
               PkKek1,
               SizeOfPkKek1,
               &gEfiCallerIdGuid,
               NULL
               );
  } else {
    Status = EnrollListOfCerts (
               EFI_IMAGE_SECURITY_DATABASE,
               &gEfiImageSecurityDatabaseGuid,
               &gEfiCertX509Guid,
               mMicrosoftPca,
               mSizeOfMicrosoftPca,
               &gMicrosoftVendorGuid,
               mMicrosoftUefiCa,
               mSizeOfMicrosoftUefiCa,
               &gMicrosoftVendorGuid,
               NULL
               );
  }
 
  if (EFI_ERROR (Status)) {
    goto FreePkKek1;
  }
 
  //
  // Enroll dbx.
  //
  Status = EnrollListOfCerts (
             EFI_IMAGE_SECURITY_DATABASE1,
             &gEfiImageSecurityDatabaseGuid,
             &gEfiCertSha256Guid,
             mSha256OfDevNull,
             mSizeOfSha256OfDevNull,
             &gEfiCallerIdGuid,
             NULL
             );
  if (EFI_ERROR (Status)) {
    goto FreePkKek1;
  }
 
  //
  // Enroll KEK.
  //
  if (NoDefault) {
    Status = EnrollListOfCerts (
               EFI_KEY_EXCHANGE_KEY_NAME,
               &gEfiGlobalVariableGuid,
               &gEfiCertX509Guid,
               PkKek1,
               SizeOfPkKek1,
               &gEfiCallerIdGuid,
               NULL
               );
  } else {
    Status = EnrollListOfCerts (
               EFI_KEY_EXCHANGE_KEY_NAME,
               &gEfiGlobalVariableGuid,
               &gEfiCertX509Guid,
               PkKek1,
               SizeOfPkKek1,
               &gEfiCallerIdGuid,
               mMicrosoftKek,
               mSizeOfMicrosoftKek,
               &gMicrosoftVendorGuid,
               NULL
               );
  }
 
  if (EFI_ERROR (Status)) {
    goto FreePkKek1;
  }
 
  //
  // Enroll PK, leaving Setup Mode (entering User Mode) at once.
  //
  Status = EnrollListOfCerts (
             EFI_PLATFORM_KEY_NAME,
             &gEfiGlobalVariableGuid,
             &gEfiCertX509Guid,
             PkKek1,
             SizeOfPkKek1,
             &gEfiGlobalVariableGuid,
             NULL
             );
  if (EFI_ERROR (Status)) {
    goto FreePkKek1;
  }
 
  //
  // Leave Custom Mode, so that updates to PK, KEK, db, and dbx require valid
  // signatures.
  //
  Settings.CustomMode = STANDARD_SECURE_BOOT_MODE;
  Status              = gRT->SetVariable (
                               EFI_CUSTOM_MODE_NAME,
                               &gEfiCustomModeEnableGuid,
                               EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS,
                               sizeof Settings.CustomMode,
                               &Settings.CustomMode
                               );
  if (EFI_ERROR (Status)) {
    AsciiPrint (
      "error: SetVariable(\"%s\", %g): %r\n",
      EFI_CUSTOM_MODE_NAME,
      &gEfiCustomModeEnableGuid,
      Status
      );
    goto FreePkKek1;
  }
 
  //
  // Final sanity check:
  //
  //                                 [SetupMode]
  //                        (read-only, standardized by UEFI)
  //                                /                \_
  //                               0               1, default
  //                              /                    \_
  //                      PK enrolled                   no PK enrolled yet,
  //              (this is called "User Mode")          PK enrollment possible
  //                             |
  //                             |
  //                     [SecureBootEnable]
  //         (read-write, edk2-specific, boot service only)
  //                /                           \_
  //               0                         1, default
  //              /                               \_
  //       [SecureBoot]=0                     [SecureBoot]=1
  // (read-only, standardized by UEFI)  (read-only, standardized by UEFI)
  //     images are not verified         images are verified, platform is
  //                                      operating in Secure Boot mode
  //                                                 |
  //                                                 |
  //                                           [CustomMode]
  //                          (read-write, edk2-specific, boot service only)
  //                                /                           \_
  //                          0, default                         1
  //                              /                               \_
  //                      PK, KEK, db, dbx                PK, KEK, db, dbx
  //                    updates are verified          updates are not verified
  //
  Status = GetSettings (&Settings);
  if (EFI_ERROR (Status)) {
    goto FreePkKek1;
  }
 
  PrintSettings (&Settings);
 
  if ((Settings.SetupMode != 0) || (Settings.SecureBoot != 1) ||
      (Settings.SecureBootEnable != 1) || (Settings.CustomMode != 0) ||
      (Settings.VendorKeys != 0))
  {
    AsciiPrint ("error: unexpected\n");
    goto FreePkKek1;
  }
 
  AsciiPrint ("info: success\n");
  RetVal = 0;
 
FreePkKek1:
  FreePool (PkKek1);
 
  return RetVal;
}