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.";
+// Pins greater in length than |kPinCheckWeakThreshold| will be checked for
+// weakness.
+const int kPinCheckWeakThreshold = 2;
 
 // Returns the active set of quick unlock modes.
 QuickUnlockModeList ComputeActiveModes(Profile* profile) {
   QuickUnlockModeList modes;
 
   chromeos::PinStorage* pin_storage =
       chromeos::PinStorageFactory::GetForProfile(profile);
   if (pin_storage && pin_storage->IsPinSet())
     modes.push_back(quick_unlock_private::QUICK_UNLOCK_MODE_PIN);
 
   return modes;
 }
 
 // Returns true if |a| and |b| contain the same elements. The elements do not
 // need to be in the same order.
 bool AreModesEqual(const QuickUnlockModeList& a, const QuickUnlockModeList& b) {
   if (a.size() != b.size())
     return false;
 
   // 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
+// null for |result| if all we want to do is check the validity of |pin|.

[jdufault, 2016/10/05 21:47:38]

Update comment

[sammiequon, 2016/10/14 20:58:53]

Done.

+std::vector<CredentialRequirementFailure> IsPinLengthValid(
+    const std::string& pin,
+    Profile* profile,
+    int* out_min_length,
+    int* out_max_length) {
+  std::vector<CredentialRequirementFailure> failures;
+  PrefService* pref_service = profile->GetPrefs();
+  int min_length = pref_service->GetInteger(prefs::kPinUnlockMinimumLength);
+  int max_length = pref_service->GetInteger(prefs::kPinUnlockMaximumLength);
+  if (out_min_length)
+    *out_min_length = min_length;
+  if (out_max_length)
+    *out_max_length = max_length;
+
+  // Check if the pin is shorter than the minimum specified length.
+  if (int{pin.size()} < min_length) {

[jdufault, 2016/10/05 21:47:37]

Compilation fails without this cast? What if you do

  if (min_length >= pin.size())
    // ...

[sammiequon, 2016/10/14 20:58:53]

Yeah it doesn't compile without the cast both ways.

+    failures.push_back(
+        CredentialRequirementFailure::CREDENTIAL_REQUIREMENT_FAILURE_TOO_SHORT);
+  }
+
+  // If the maximum lenght is nonzero and shorter than the minimum length, the

[jdufault, 2016/10/05 21:47:38]

lenght -> length

[sammiequon, 2016/10/14 20:58:53]

Done.

+  // maximum length is the minimum length.
+  if (max_length > 0 && max_length < min_length)

[jdufault, 2016/10/05 21:47:38]

This check should happen before assigning out_* params.

It should probably be != 0 instead of > 0 as well.

[sammiequon, 2016/10/14 20:58:53]

Done.

+    max_length = min_length;
+
+  // If the maximum specified length is zero, there is no maximum length.
+  // Otherwise check if the pin is longer than the maximum specified length.
+  if (max_length > 0 && int{pin.size()} > max_length) {
+    failures.push_back(
+        CredentialRequirementFailure::CREDENTIAL_REQUIREMENT_FAILURE_TOO_LONG);
+  }
+
+  return failures;
+}
+
+// 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

[jdufault, 2016/10/05 21:47:38]

Update comment

[sammiequon, 2016/10/14 20:58:53]

Done.

+// null for |result| if all we want to do is check the validity of |pin|.
+std::vector<CredentialRequirementFailure> IsPinDifficultEnough(
+    const std::string& pin,
+    Profile* profile,
+    bool* out_allow_weak_pin) {
+  std::vector<CredentialRequirementFailure> failures;
+  PrefService* pref_service = profile->GetPrefs();
+  bool allow_weak = pref_service->GetBoolean(prefs::kPinUnlockAllowWeakPins);
+  if (out_allow_weak_pin)
+    *out_allow_weak_pin = allow_weak;
+
+  // If the pin length is |kPinCheckWeakThreshold| or less, there is no need to
+  // check for same character and increasing pin.
+  if (int{pin.size()} <= kPinCheckWeakThreshold)
+    return failures;
+
+  // Check for same digits, increasing pin simutaneously.
+  bool is_same = true;
+  bool is_increasing = true;
+  bool is_decreasing = true;
+  for (int i = 1; i < int{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);
+    is_decreasing = is_decreasing && (current == previous - 1);
+  }
+
+  // Pin is considered weak if either of these is met.
+  if ((is_same || is_increasing || is_decreasing)) {
+    failures.push_back(
+        CredentialRequirementFailure::CREDENTIAL_REQUIREMENT_FAILURE_TOO_WEAK);
+  }
+
+  return failures;
+}
+
 }  // 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>();
+  result->min_length = base::MakeUnique<int>();
+  result->max_length = base::MakeUnique<int>();
+  result->allow_weak_pins = base::MakeUnique<bool>();
+
+  // 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;
+  if (!std::all_of(tried_password.begin(), tried_password.end(), ::isdigit))
+    return RespondNow(
+        ArgumentList(IsCredentialUsable::Results::Create(*result)));
+
+  Profile* profile = chrome_details_.GetProfile();
+  auto length_failures =
+      IsPinLengthValid(tried_password, profile, result->min_length.get(),
+                       result->max_length.get());
+  auto weak_failures = IsPinDifficultEnough(tried_password, profile,
+                                            result->allow_weak_pins.get());
+  result->failures.insert(result->failures.end(), length_failures.begin(),
+                          length_failures.end());
+  result->failures.insert(result->failures.end(), weak_failures.begin(),
+                          weak_failures.end());
+
+  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, nullptr)
+             .empty() &&
+        !IsPinDifficultEnough(params_->credentials[j],
+                              chrome_details_.GetProfile(), nullptr)
+             .empty()) {
+      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