cros: Added a new function to quick unlock api for checking unfinished pins.

chrome/browser/chromeos/extensions/quick_unlock_private/quick_unlock_private_api.cc

 // Copyright 2016 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 "chrome/browser/chromeos/extensions/quick_unlock_private/quick_unlock_private_api.h"
 
 #include "chrome/browser/chromeos/login/quick_unlock/pin_storage.h"
 #include "chrome/browser/chromeos/login/quick_unlock/pin_storage_factory.h"
 #include "chrome/browser/chromeos/profiles/profile_helper.h"
+#include "chrome/common/pref_names.h"
 #include "chromeos/login/auth/extended_authenticator.h"
 #include "chromeos/login/auth/user_context.h"
+#include "components/prefs/pref_service.h"
 #include "extensions/browser/event_router.h"
 
 namespace extensions {
 
 namespace quick_unlock_private = api::quick_unlock_private;
 namespace SetModes = quick_unlock_private::SetModes;
 namespace GetActiveModes = quick_unlock_private::GetActiveModes;
+namespace IsCredentialUsable = quick_unlock_private::IsCredentialUsable;
 namespace GetAvailableModes = quick_unlock_private::GetAvailableModes;
 namespace OnActiveModesChanged = quick_unlock_private::OnActiveModesChanged;
+using CredentialRequirementFailure =
+    quick_unlock_private::CredentialRequirementFailure;
+using CredentialRequirement = quick_unlock_private::CredentialRequirement;
 using QuickUnlockMode = quick_unlock_private::QuickUnlockMode;
 using QuickUnlockModeList = std::vector<QuickUnlockMode>;
 
 namespace {
 
 const char kModesAndCredentialsLengthMismatch[] =
     "|modes| and |credentials| must have the same number of elements";
 const char kMultipleModesNotSupported[] =
     "At most one quick unlock mode can be active.";
 
@@ skipping 18 matching lines @@
   // This is a slow comparison algorithm, but the number of entries in |a| and
   // |b| will always be very low (0-3 items) so it doesn't matter.
   for (size_t i = 0; i < a.size(); ++i) {
     if (std::find(b.begin(), b.end(), a[i]) == b.end())
       return false;
   }
 
   return true;
 }
 
+// Check if a given |pin| is valid given the policies in the |profile|. If
+// |result| is a valid pointer, the failures are added to |result|. Pass a
+// nullptr for |result| if all we want to do is check the validity of |pin|.

[jdufault, 2016/10/04 22:57:27]

nit: 'a nullptr' => 'null'

null is preferred inside of comments.

[sammiequon, 2016/10/05 19:48:11]

Done.

+bool IsPinLengthValid(const std::string& pin,
+                      Profile* profile,
+                      CredentialRequirement* result) {
+  bool is_valid = true;
+  PrefService* pref_service = profile->GetPrefs();
+  int minimum_length = pref_service->GetInteger(prefs::kPinUnlockMinimumLength);

[jdufault, 2016/10/04 22:57:27]

Name these min_length, max_length?

[sammiequon, 2016/10/05 19:48:11]

Done.

+  int maximum_length = pref_service->GetInteger(prefs::kPinUnlockMaximumLength);
+  if (result) {
+    result->min_length = base::MakeUnique<int>(minimum_length);
+    result->max_length = base::MakeUnique<int>(maximum_length);
+  }
+
+  // Check if the pin is shorter than the minimum specified length.
+  if (int{pin.size()} < minimum_length) {
+    is_valid = false;
+    if (result) {
+      result->failures.push_back(CredentialRequirementFailure::
+                                     CREDENTIAL_REQUIREMENT_FAILURE_TOO_SHORT);
+    }
+  }
+
+  // If the maximum specified length is shorter or equal to the minimum
+  // specified length, there is no maximum length. Otherwise check if the pin is
+  // longer than the maximum specified length.

[jdufault, 2016/10/04 22:57:27]

I think if the maximum length is shorter than the minimum, we should set the
maximum to the minimum. For example,

min: 4, max: 1 => pin of exactly 4 digits

For the unlimited case, we could hard code that to 0.

It seems that with the current logic we cannot set policy to require a PIN of
exactly 4 digits.

[sammiequon, 2016/10/05 19:48:11]

Done.

+  if (maximum_length > minimum_length && int{pin.size()} > maximum_length) {
+    is_valid = true;
+    if (result) {
+      result->failures.push_back(CredentialRequirementFailure::
+                                     CREDENTIAL_REQUIREMENT_FAILURE_TOO_LONG);
+    }
+  }
+
+  return is_valid;
+}
+
+// Check if a given |pin| is valid given the policies in the |profile|. If
+// |result| is a valid pointer, the failures are added to |result|. Pass a
+// nullptr for |result| if all we want to do is check the validity of |pin|.

[jdufault, 2016/10/04 22:57:27]

nullptr => null (see above comment)

[sammiequon, 2016/10/05 19:48:11]

Done.

+bool IsPinDifficultEnough(const std::string& pin,

[jdufault, 2016/10/04 22:57:28]

If result->allow_easy_pins is eliminated, this function can be simplified by
returning the set of failures.

  std::vector<CredentialRequirementFailure> CheckPinDifficulty(
      const std::string& pin, Profile* profile);

I think applying a similar logic to IsPinLengthValid would make it more readable
as well.

  std::vector<CredentialRequirementFailure> CheckPinLength(
      const std::string& pin, Profile* profile,
      int* out_min_length, int* out_max_length) {
    // ...
    if (out_min_length)
      *out_min_length = min_length;
    // ...
  }

This would eliminate all of the if (result) blocks which make the functions
painful to read and complicate the logic.

[sammiequon, 2016/10/05 19:48:11]

Done.

+                          Profile* profile,
+                          CredentialRequirement* result) {
+  PrefService* pref_service = profile->GetPrefs();
+  bool allow_easy = pref_service->GetBoolean(prefs::kPinUnlockAllowEasyPins);
+  if (result)
+    result->allow_easy_pins = base::MakeUnique<bool>(allow_easy);
+
+  // If the pin length is two or less, there is no need to check for same
+  // character and increasing pin.
+  const int pin_check_easy_threshold = 2;

[jdufault, 2016/10/04 22:57:27]

Move this constant the top of the file and fix the naming style.

[sammiequon, 2016/10/05 19:48:11]

Done.

+  if (int{pin.size()} <= pin_check_easy_threshold)
+    return allow_easy;

[jdufault, 2016/10/04 22:57:28]

Shouldn't this always return true?

[sammiequon, 2016/10/05 19:48:11]

Done.

+
+  // Check for same digits, increasing pin simutaneously.
+  bool is_same = true;
+  bool is_increasing = true;
+  bool first = true;
+  char last_char;
+  for (const char& c : pin) {

[jdufault, 2016/10/04 22:57:28]

I'd remove the const&, the pointer is bigger than the actual value.

I'd switch this to a normal for loop since there are quite a few lines dedicated
to tracking the previous value.

for (size_t i = 1; i < pin.length(); ++i) {
  const char previous = pin[i - 1];
  const char current = pin[i];

  is_same = is_same && (current == previous);
  is_increasing = is_increasing && (current == previous + 1);
}

[sammiequon, 2016/10/05 19:48:11]

Done.

+    if (first) {
+      first = false;
+      last_char = c;
+      continue;
+    }
+    is_same = is_same && (c == last_char);
+    is_increasing = is_increasing && (c == last_char + 1);
+    last_char = c;
+  }
+
+  // Pin is considered weak if either of these is met.
+  if ((is_same || is_increasing) && result) {
+    result->failures.push_back(
+        CredentialRequirementFailure::CREDENTIAL_REQUIREMENT_FAILURE_TOO_WEAK);
+  }
+
+  return is_same || is_increasing;
+}
+
 }  // namespace
 
 // quickUnlockPrivate.getAvailableModes
 
 QuickUnlockPrivateGetAvailableModesFunction::
     QuickUnlockPrivateGetAvailableModesFunction()
     : chrome_details_(this) {}
 
 QuickUnlockPrivateGetAvailableModesFunction::
     ~QuickUnlockPrivateGetAvailableModesFunction() {}
@@ skipping 17 matching lines @@
 QuickUnlockPrivateGetActiveModesFunction::
     ~QuickUnlockPrivateGetActiveModesFunction() {}
 
 ExtensionFunction::ResponseAction
 QuickUnlockPrivateGetActiveModesFunction::Run() {
   const QuickUnlockModeList modes =
       ComputeActiveModes(chrome_details_.GetProfile());
   return RespondNow(ArgumentList(GetActiveModes::Results::Create(modes)));
 }
 
+// quickUnlockPrivate.isCredentialUsable
+
+QuickUnlockPrivateIsCredentialUsableFunction::
+    QuickUnlockPrivateIsCredentialUsableFunction()
+    : chrome_details_(this) {}
+
+QuickUnlockPrivateIsCredentialUsableFunction::
+    ~QuickUnlockPrivateIsCredentialUsableFunction() {}
+
+ExtensionFunction::ResponseAction
+QuickUnlockPrivateIsCredentialUsableFunction::Run() {
+  params_ = IsCredentialUsable::Params::Create(*args_);
+  EXTENSION_FUNCTION_VALIDATE(params_.get());
+
+  auto result = base::MakeUnique<CredentialRequirement>();
+
+  // Only handles pins for now.
+  if (params_->mode != QuickUnlockMode::QUICK_UNLOCK_MODE_PIN) {
+    return RespondNow(
+        ArgumentList(IsCredentialUsable::Results::Create(*result)));
+  }
+
+  std::string tried_password = params_->credential;
+
+  Profile* profile = chrome_details_.GetProfile();
+  IsPinLengthValid(tried_password, profile, result.get());
+  IsPinDifficultEnough(tried_password, profile, result.get());
+
+  return RespondNow(ArgumentList(IsCredentialUsable::Results::Create(*result)));
+}
+
 // quickUnlockPrivate.setModes
 
 QuickUnlockPrivateSetModesFunction::QuickUnlockPrivateSetModesFunction()
     : chrome_details_(this) {}
 
 QuickUnlockPrivateSetModesFunction::~QuickUnlockPrivateSetModesFunction() {}
 
 void QuickUnlockPrivateSetModesFunction::SetAuthenticatorAllocatorForTesting(
     const QuickUnlockPrivateSetModesFunction::AuthenticatorAllocator&
         allocator) {
@@ skipping 14 matching lines @@
 
   if (params_->modes.size() > 1)
     return RespondNow(Error(kMultipleModesNotSupported));
 
   // Verify every credential is numeric.
   for (const std::string& credential : params_->credentials) {
     if (!std::all_of(credential.begin(), credential.end(), ::isdigit))
       return RespondNow(ArgumentList(SetModes::Results::Create(false)));
   }
 
+  // Verify every credential is valid based on policies.
+  for (size_t j = 0; j < params_->modes.size(); ++j) {
+    if (params_->modes[j] == QuickUnlockMode::QUICK_UNLOCK_MODE_PIN &&
+        !IsPinLengthValid(params_->credentials[j], chrome_details_.GetProfile(),
+                          nullptr) &&
+        !IsPinDifficultEnough(params_->credentials[j],
+                              chrome_details_.GetProfile(), nullptr)) {
+      return RespondNow(ArgumentList(SetModes::Results::Create(false)));
+    }
+  }
+
   user_manager::User* user = chromeos::ProfileHelper::Get()->GetUserByProfile(
       chrome_details_.GetProfile());
   chromeos::UserContext user_context(user->GetAccountId());
   user_context.SetKey(chromeos::Key(params_->account_password));
 
   // Lazily allocate the authenticator. We do this here, instead of in the ctor,
   // so that tests can install a fake.
   if (authenticator_allocator_.is_null())
     extended_authenticator_ = chromeos::ExtendedAuthenticator::Create(this);
   else
@@ skipping 83 matching lines @@
   }
 
   std::unique_ptr<base::ListValue> args = OnActiveModesChanged::Create(modes);
   std::unique_ptr<Event> event(
       new Event(events::QUICK_UNLOCK_PRIVATE_ON_ACTIVE_MODES_CHANGED,
                 OnActiveModesChanged::kEventName, std::move(args)));
   EventRouter::Get(browser_context())->BroadcastEvent(std::move(event));
 }
 
 }  // namespace extensions