VBoot Reference: Add version checking to for preventing rollbacks.

src/platform/vboot_reference/utils/rollback_index.c

+/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Functions for querying, manipulating and locking rollback indices
+ * stored in the TPM NVRAM.
+ */
+
+#include "rollback_index.h"
+
+#include <stdint.h>
+#include <tss/tcs.h>
+
+#include "tlcl.h"
+
+uint16_t g_firmware_key_version = 0;
+uint16_t g_firmware_version = 0;
+uint16_t g_kernel_key_version = 0;
+uint16_t g_kernel_version = 0;
+
+static void InitializeSpaces(void) {
+  uint16_t zero = 0;
+  uint32_t perm = TPM_NV_PER_WRITE_STCLEAR | TPM_NV_PER_PPWRITE;
+
+  printf("Initializing spaces\n");
+  TlclSetNvLocked();  /* useful only the first time */
+
+  TlclDefineSpace(FIRMWARE_KEY_VERSION_NV_INDEX, perm, sizeof(uint16_t));
+  TlclWrite(FIRMWARE_KEY_VERSION_NV_INDEX, (uint8_t*) &zero, sizeof(uint16_t));
+
+  TlclDefineSpace(FIRMWARE_VERSION_NV_INDEX, perm, sizeof(uint16_t));
+  TlclWrite(FIRMWARE_VERSION_NV_INDEX, (uint8_t*) &zero, sizeof(uint16_t));
+
+  TlclDefineSpace(KERNEL_KEY_VERSION_NV_INDEX, perm, sizeof(uint16_t));
+  TlclWrite(KERNEL_KEY_VERSION_NV_INDEX, (uint8_t*) &zero, sizeof(uint16_t));
+
+  TlclDefineSpace(KERNEL_VERSION_NV_INDEX, perm, sizeof(uint16_t));
+  TlclWrite(KERNEL_VERSION_NV_INDEX, (uint8_t*) &zero, sizeof(uint16_t));
+}
+
+static void EnterRecovery(void) {
+  /* Temporary recovery stub. Currently just initalizes spaces. */
+  InitializeSpaces();
+}
+
+static int GetTPMRollbackIndices(void) {
+  /* We just perform the reads, making sure they succeed. A failure means that
+   * the rollback index locations are some how messed up and we must jump to
+   * recovery */
+  if (TPM_SUCCESS != TlclRead(FIRMWARE_KEY_VERSION_NV_INDEX,
+                              (uint8_t*) &g_firmware_key_version,
+                              sizeof(g_firmware_key_version)) ||
+      TPM_SUCCESS != TlclRead(FIRMWARE_KEY_VERSION_NV_INDEX,
+                              (uint8_t*) &g_firmware_key_version,
+                              sizeof(g_firmware_key_version)) ||
+      TPM_SUCCESS != TlclRead(FIRMWARE_KEY_VERSION_NV_INDEX,
+                               (uint8_t*) &g_firmware_key_version,
+                               sizeof(g_firmware_key_version))  ||
+      TPM_SUCCESS != TlclRead(FIRMWARE_KEY_VERSION_NV_INDEX,
+                              (uint8_t*) &g_firmware_key_version,
+                              sizeof(g_firmware_key_version)))
+    return 0;
+  return 1;
+}
+
+
+void SetupTPM(void) {
+  TlclLibinit();
+  TlclStartup();
+  /* TODO(gauravsh): The call to self test  should probably be deferred.
+   * As per semenzato@chromium.org -
+   * TlclStartup should be called before the firmware initializes the memory
+   * controller, so the selftest can run in parallel with that. Here we should
+   * just call TlclSelftestFull to make sure the self test has
+   * completed---unless we want to rely on the NVRAM operations being available
+   * before the selftest completes. */
+  TlclSelftestfull();
+  TlclAssertPhysicalPresence();
+  if (!GetTPMRollbackIndices()) {
+    fprintf(stderr, "Ho Ho Ho! We must jump to recovery.");
+    EnterRecovery();
+  }
+}
+
+
+uint16_t GetStoredVersion(int type) {
+  switch (type) {
+    case FIRMWARE_KEY_VERSION:
+      return g_firmware_key_version;
+      break;
+    case FIRMWARE_VERSION:
+      return g_firmware_version;
+      break;
+    case KERNEL_KEY_VERSION:
+      return g_kernel_key_version;
+      break;
+    case KERNEL_VERSION:
+      return g_kernel_version;
+      break;
+  }
+  return 0;
+}
+
+int WriteStoredVersion(int type, uint16_t version) {
+  switch (type) {
+    case FIRMWARE_KEY_VERSION:
+      return (TPM_SUCCESS == TlclWrite(FIRMWARE_KEY_VERSION_NV_INDEX,
+                                       (uint8_t*) &version,
+                                       sizeof(uint16_t)));
+      break;
+    case FIRMWARE_VERSION:
+      return (TPM_SUCCESS == TlclWrite(FIRMWARE_VERSION_NV_INDEX,
+                                       (uint8_t*) &version,
+                                       sizeof(uint16_t)));
+      break;
+    case KERNEL_KEY_VERSION:
+      return (TPM_SUCCESS == TlclWrite(KERNEL_KEY_VERSION_NV_INDEX,
+                                       (uint8_t*) &version,
+                                       sizeof(uint16_t)));
+      break;
+    case KERNEL_VERSION:
+      return (TPM_SUCCESS == TlclWrite(KERNEL_VERSION_NV_INDEX,
+                                       (uint8_t*) &version,
+                                       sizeof(uint16_t)));
+      break;
+  }
+  return 0;
+}
+
+void LockStoredVersion(int type) {
+  /* TODO(gauravsh): Add error checking here to make sure TlclWriteLock
+   * did not fail. We must jump to recovery in that case.
+   */
+  switch (type) {
+    case FIRMWARE_KEY_VERSION:
+      TlclWriteLock(FIRMWARE_KEY_VERSION_NV_INDEX);
+      break;
+    case FIRMWARE_VERSION:
+      TlclWriteLock(FIRMWARE_VERSION_NV_INDEX);
+      break;
+    case KERNEL_KEY_VERSION:
+      TlclWriteLock(KERNEL_KEY_VERSION_NV_INDEX);
+      break;
+    case KERNEL_VERSION:
+      TlclWriteLock(KERNEL_VERSION_NV_INDEX);
+      break;
+  }
+}