code.delx.au - refind/blob - mok/mok.c

   1 /* mok/mok.c
   2  *
   3  * Based mostly on shim.c by Matthew J. Garrett/Red Hat (see below
   4  * copyright notice).
   5  *
   6  * Code to perform Secure Boot verification of boot loader programs
   7  * using the Shim program and its Machine Owner Keys (MOKs), to
   8  * supplement standard Secure Boot checks performed by the firmware.
   9  *
  10  */
  11
  12 /*
  13  * shim - trivial UEFI first-stage bootloader
  14  *
  15  * Copyright 2012 Red Hat, Inc <mjg@redhat.com>
  16  *
  17  * Redistribution and use in source and binary forms, with or without
  18  * modification, are permitted provided that the following conditions
  19  * are met:
  20  *
  21  * Redistributions of source code must retain the above copyright
  22  * notice, this list of conditions and the following disclaimer.
  23  *
  24  * Redistributions in binary form must reproduce the above copyright
  25  * notice, this list of conditions and the following disclaimer in the
  26  * documentation and/or other materials provided with the
  27  * distribution.
  28  *
  29  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  30  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  31  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  32  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  33  * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
  34  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  35  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  36  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  37  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  38  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  39  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  40  * OF THE POSSIBILITY OF SUCH DAMAGE.
  41  *
  42  * Significant portions of this code are derived from Tianocore
  43  * (http://tianocore.sf.net) and are Copyright 2009-2012 Intel
  44  * Corporation.
  45  */
  46
  47 #include "global.h"
  48 #include "mok.h"
  49 #include "../include/refit_call_wrapper.h"
  50 #include "../refind/lib.h"
  51 #include "../refind/screen.h"
  52
  53
  54 /*
  55  * Check whether we're in Secure Boot and user mode
  56  */
  57 BOOLEAN secure_mode (VOID)
  58 {
  59    EFI_STATUS status;
  60    EFI_GUID global_var = EFI_GLOBAL_VARIABLE;
  61    UINTN charsize = sizeof(char);
  62    UINT8 *sb = NULL, *setupmode = NULL;
  63
  64    status = EfivarGetRaw(&global_var, L"SecureBoot", (CHAR8 **) &sb, &charsize);
  65    /* FIXME - more paranoia here? */
  66    if (status != EFI_SUCCESS || charsize != sizeof(CHAR8) || *sb != 1) {
  67       return FALSE;
  68    }
  69
  70    status = EfivarGetRaw(&global_var, L"SetupMode", (CHAR8 **) &setupmode, &charsize);
  71    if (status == EFI_SUCCESS && charsize == sizeof(CHAR8) && *setupmode == 1) {
  72       return FALSE;
  73    }
  74
  75    return TRUE;
  76 } // secure_mode()
  77
  78 // Returns TRUE if the shim program is available to verify binaries,
  79 // FALSE if not
  80 BOOLEAN ShimLoaded(void) {
  81    SHIM_LOCK   *shim_lock;
  82    EFI_GUID    ShimLockGuid = SHIM_LOCK_GUID;
  83
  84    return (refit_call3_wrapper(BS->LocateProtocol, &ShimLockGuid, NULL, (VOID**) &shim_lock) == EFI_SUCCESS);
  85 } // ShimLoaded()
  86
  87 // The following is based on the grub_linuxefi_secure_validate() function in Fedora's
  88 // version of GRUB 2.
  89 // Returns TRUE if the specified data is validated by Shim's MOK, FALSE otherwise
  90 BOOLEAN ShimValidate (VOID *data, UINT32 size)
  91 {
  92    SHIM_LOCK   *shim_lock;
  93    EFI_GUID    ShimLockGuid = SHIM_LOCK_GUID;
  94
  95    if ((data != NULL) && (refit_call3_wrapper(BS->LocateProtocol, &ShimLockGuid, NULL, (VOID**) &shim_lock) == EFI_SUCCESS)) {
  96       if (!shim_lock)
  97          return FALSE;
  98
  99       if (shim_lock->shim_verify(data, size) == EFI_SUCCESS)
 100          return TRUE;
 101    }
 102
 103    return FALSE;
 104 } // BOOLEAN ShimValidate()