X-Git-Url: https://code.delx.au/refind/blobdiff_plain/c5d1646e66976fff2184375187bb96db366afcbc..7e22a0b1a85d3403ed76ece8339a07ef59174ed3:/mok/mok.c

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+/* mok/mok.c
+ *
+ * Based mostly on shim.c by Matthew J. Garrett/Red Hat (see below
+ * copyright notice).
+ *
+ * Code to perform Secure Boot verification of boot loader programs
+ * using the Shim program and its Machine Owner Keys (MOKs), to
+ * supplement standard Secure Boot checks performed by the firmware.
+ *
+ */
+
+/*
+ * 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 "global.h"
+#include "mok.h"
+#include "../include/refit_call_wrapper.h"
+
+static EFI_STATUS get_variable (CHAR16 *name, EFI_GUID guid, UINT32 *attributes, UINTN *size, VOID **buffer)
+{
+   EFI_STATUS efi_status;
+   char allocate = !(*size);
+
+   efi_status = uefi_call_wrapper(RT->GetVariable, 5, name, &guid, attributes, size, buffer);
+
+   if (efi_status != EFI_BUFFER_TOO_SMALL || !allocate) {
+      return efi_status;
+   }
+
+   *buffer = AllocatePool(*size);
+
+   if (!*buffer) {
+      Print(L"Unable to allocate variable buffer\n");
+      return EFI_OUT_OF_RESOURCES;
+   }
+
+   efi_status = uefi_call_wrapper(RT->GetVariable, 5, name, &guid, attributes, size, *buffer);
+
+   return efi_status;
+} // get_variable()
+
+/*
+ * Check whether we're in Secure Boot and user mode
+ */
+BOOLEAN secure_mode (VOID)
+{
+   EFI_STATUS status;
+   EFI_GUID global_var = EFI_GLOBAL_VARIABLE;
+   UINTN charsize = sizeof(char);
+   UINT8 sb, setupmode;
+   UINT32 attributes;
+
+   status = get_variable(L"SecureBoot", global_var, &attributes, &charsize, (VOID *)&sb);
+
+   /* FIXME - more paranoia here? */
+   if (status != EFI_SUCCESS || sb != 1) {
+      return FALSE;
+   }
+
+   status = get_variable(L"SetupMode", global_var, &attributes, &charsize, (VOID *)&setupmode);
+
+   if (status == EFI_SUCCESS && setupmode == 1) {
+      return FALSE;
+   }
+
+   return TRUE;
+} // secure_mode()
+
+// Returns TRUE if the shim program is available to verify binaries,
+// FALSE if not
+BOOLEAN ShimLoaded(void) {
+   SHIM_LOCK   *shim_lock;
+   EFI_GUID    ShimLockGuid = SHIM_LOCK_GUID;
+
+   return (refit_call3_wrapper(BS->LocateProtocol, &ShimLockGuid, NULL, (VOID**) &shim_lock) == EFI_SUCCESS);
+} // ShimLoaded()
+
+// The following is based on the grub_linuxefi_secure_validate() function in Fedora's
+// version of GRUB 2.
+// Returns TRUE if the specified data is validated by Shim's MOK, FALSE otherwise
+BOOLEAN ShimValidate (VOID *data, UINT32 size)
+{
+   SHIM_LOCK   *shim_lock;
+   EFI_GUID    ShimLockGuid = SHIM_LOCK_GUID;
+
+   if (refit_call3_wrapper(BS->LocateProtocol, &ShimLockGuid, NULL, (VOID**) &shim_lock) == EFI_SUCCESS) {
+      if (!shim_lock)
+         return FALSE;
+
+      if (shim_lock->shim_verify(data, size) == EFI_SUCCESS)
+         return TRUE;
+   }
+
+   return FALSE;
+} // BOOLEAN ShimValidate()