cros: Replace "TPM" with "secure module" for machines without TPM.

chromeos/tpm/tpm_token_info_getter.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chromeos/tpm/tpm_token_info_getter.h"
 
 #include <stdint.h>
 
 #include "base/bind.h"
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
 #include "base/location.h"
 #include "base/task_runner.h"
 #include "chromeos/cryptohome/cryptohome_parameters.h"
 #include "chromeos/dbus/cryptohome_client.h"
 
 namespace {
 
 const int64_t kInitialRequestDelayMs = 100;
 const int64_t kMaxRequestDelayMs = 300000;  // 5 minutes
 
+// If either of these two files exist, then we are not using TPM.
+constexpr char kNoTPMIndicatorFile1[] =

[apronin, 2017/05/02 16:43:38]

I'd go with 'NoTPMIndicator' -> 'Cr50UsedIndicator'. Or, ->
'TPMNotUsedIndicator'

[sammiequon, 2017/05/02 17:27:23]

Done.

+    "/opt/google/cr50/firmware/cr50.bin.prod";
+constexpr char kNoTPMIndicatorFile2[] = "/etc/init/cr50-update.conf";
+
 // Calculates the delay before running next attempt to initiatialize the TPM
 // token, if |last_delay| was the last or initial delay.
 base::TimeDelta GetNextRequestDelayMs(base::TimeDelta last_delay) {
   // This implements an exponential backoff, as we don't know in which order of
   // magnitude the TPM token changes it's state.
   base::TimeDelta next_delay = last_delay * 2;
 
   // Cap the delay to prevent an overflow. This threshold is arbitrarily chosen.
   const base::TimeDelta max_delay =
       base::TimeDelta::FromMilliseconds(kMaxRequestDelayMs);
@@ skipping 24 matching lines @@
 }
 
 // static
 std::unique_ptr<TPMTokenInfoGetter> TPMTokenInfoGetter::CreateForSystemToken(
     CryptohomeClient* cryptohome_client,
     const scoped_refptr<base::TaskRunner>& delayed_task_runner) {
   return std::unique_ptr<TPMTokenInfoGetter>(new TPMTokenInfoGetter(
       TYPE_SYSTEM, EmptyAccountId(), cryptohome_client, delayed_task_runner));
 }
 
+bool TPMTokenInfoGetter::DoesTPMExist() {

[apronin, 2017/05/02 16:43:38]

Does what is supposed to do for the purposes of the patch. But I'd rename and
revert the logic just to minimize potential confusion in the future. In theory,
several chips, including a TPM and an H1 with Cr50 can exist on the same system.
It counts not what exists, but what is used. So, I'd do something like:

bool TPMTokenInfoGetter::IsCr50Used() {
   return base::PathExists(base::FilePath(kCr50UsedIndicatorFile1)) ||
          base::PathExists(base::FilePath(kCr50UsedIndicatorFile2));
}

Or, at least switch from 'DoesExist' to 'IsUsed', though that may confuse future
readers: are we talking about a security module (which, even in cr50 case, in
everyday life may be referred to as tpm for brevity) not being used and going
with software-based approach, or are we talking about using h1+cr50 instead of a
tpm:

bool TPMTokenInfoGetter::IsTPMUsed() {
   return !base::PathExists(base::FilePath(kCr50UsedIndicatorFile1)) &&
          !base::PathExists(base::FilePath(kCr50UsedIndicatorFile2));
}

[sammiequon, 2017/05/02 17:27:23]

Done.

+  return !base::PathExists(base::FilePath(kNoTPMIndicatorFile1)) &&
+         !base::PathExists(base::FilePath(kNoTPMIndicatorFile2));
+}
+
 TPMTokenInfoGetter::~TPMTokenInfoGetter() {}
 
 void TPMTokenInfoGetter::Start(const TPMTokenInfoCallback& callback) {
   CHECK(state_ == STATE_INITIAL);
   CHECK(!callback.is_null());
 
   callback_ = callback;
 
   state_ = STATE_STARTED;
   Continue();
@@ skipping 80 matching lines @@
   TPMTokenInfo token_info;
   token_info.tpm_is_enabled = true;
   token_info.token_name = token_name;
   token_info.user_pin = user_pin;
   token_info.token_slot_id = token_slot_id;
 
   callback_.Run(token_info);
 }
 
 }  // namespace chromeos