Added a timeout for platform verification key generation.

chrome/browser/chromeos/attestation/platform_verification_flow.h

 // Copyright 2013 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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_ATTESTATION_PLATFORM_VERIFICATION_FLOW_H_
 #define CHROME_BROWSER_CHROMEOS_ATTESTATION_PLATFORM_VERIFICATION_FLOW_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
+#include "base/time/time.h"
+#include "base/timer/timer.h"
 #include "url/gurl.h"
 
 class PrefService;
 
 namespace content {
 class WebContents;
 }
 
 namespace cryptohome {
 class AsyncMethodCaller;
 }
 
 namespace user_prefs {
 class PrefRegistrySyncable;
 }
 
 namespace chromeos {
 
 class CryptohomeClient;
 class UserManager;
 class User;
 
 namespace attestation {
 
 class AttestationFlow;
 
 // This class allows platform verification for the content protection use case.
 // All methods must only be called on the UI thread.  Example:
-//   PlatformVerificationFlow verifier;
+//   scoped_refptr<PlatformVerificationFlow> verifier =
+//       new PlatformVerificationFlow();
 //   PlatformVerificationFlow::Callback callback = base::Bind(&MyCallback);
-//   verifier.ChallengePlatformKey(my_web_contents, "my_id", "some_challenge",
-//                                 callback);
-class PlatformVerificationFlow {
+//   verifier->ChallengePlatformKey(my_web_contents, "my_id", "some_challenge",
+//                                  callback);
+//
+// This class is RefCountedThreadSafe because it may need to outlive its caller.
+// The attestation flow that needs to happen to establish a certified platform
+// key may take minutes on some hardware.  This class will timeout after a much
+// shorter time so the caller can proceed without platform verification but it
+// is important that the pending operation be allowed to finish.  If the
+// attestation flow is aborted at any stage, it will need to start over.  If we
+// use weak pointers, the attestation flow will stop when the next callback is
+// run.  So we need the instance to stay alive until the platform key is fully
+// certified so the next time ChallegePlatformKey() is invoked it will be quick.
+class PlatformVerificationFlow
+    : public base::RefCountedThreadSafe<PlatformVerificationFlow> {
  public:
   enum Result {
     SUCCESS,                // The operation succeeded.
     INTERNAL_ERROR,         // The operation failed unexpectedly.
     PLATFORM_NOT_VERIFIED,  // The platform cannot be verified.  For example:
                             // - It is not a Chrome device.
                             // - It is not running a verified OS image.
     USER_REJECTED,          // The user explicitly rejected the operation.
     POLICY_REJECTED,        // The operation is not allowed by policy/settings.
+    TIMEOUT,                // The operation timed out.
   };
 
   enum ConsentType {
     CONSENT_TYPE_NONE,         // No consent necessary.
     CONSENT_TYPE_ATTESTATION,  // Consent to use attestation.
     CONSENT_TYPE_ALWAYS,       // Consent because 'Always Ask' was requested.
   };
 
   enum ConsentResponse {
     CONSENT_RESPONSE_NONE,
@@ skipping 38 matching lines @@
   PlatformVerificationFlow();
 
   // An alternate constructor which specifies dependent objects explicitly.
   // This is useful in testing.  The caller retains ownership of all pointers.
   PlatformVerificationFlow(AttestationFlow* attestation_flow,
                            cryptohome::AsyncMethodCaller* async_caller,
                            CryptohomeClient* cryptohome_client,
                            UserManager* user_manager,
                            Delegate* delegate);
 
-  virtual ~PlatformVerificationFlow();
-
   // Invokes an asynchronous operation to challenge a platform key.  Any user
   // interaction will be associated with |web_contents|.  The |service_id| is an
   // arbitrary value but it should uniquely identify the origin of the request
   // and should not be determined by that origin; its purpose is to prevent
   // collusion between multiple services.  The |challenge| is also an arbitrary
   // value but it should be time sensitive or associated to some kind of session
   // because its purpose is to prevent certificate replay.  The |callback| will
   // be called when the operation completes.  The duration of the operation can
   // vary depending on system state, hardware capabilities, and interaction with
   // the user.
   void ChallengePlatformKey(content::WebContents* web_contents,
                             const std::string& service_id,
                             const std::string& challenge,
                             const ChallengeCallback& callback);
 
   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* prefs);
 
   void set_testing_prefs(PrefService* testing_prefs) {
     testing_prefs_ = testing_prefs;
   }
 
   void set_testing_url(const GURL& testing_url) {
     testing_url_ = testing_url;
   }
 
+  void set_timeout_delay(const base::TimeDelta& timeout_delay) {
+    timeout_delay_ = timeout_delay;
+  }
+
  private:
+  // Holds the arguments of a ChallengePlatformKey call.  This is convenient for
+  // use with base::Bind so we don't get too many arguments.
+  struct ChallengeContext {
+    content::WebContents* web_contents;
+    std::string service_id;
+    std::string challenge;
+    ChallengeCallback callback;
+  };
+
+  friend class base::RefCountedThreadSafe<PlatformVerificationFlow>;
+  ~PlatformVerificationFlow();
+
   // Checks whether we need to prompt the user for consent before proceeding and
-  // invokes the consent UI if so.  All parameters are the same as in
-  // ChallengePlatformKey except for the additional |attestation_enrolled| which
-  // specifies whether attestation has been enrolled for this device.
-  void CheckConsent(content::WebContents* web_contents,
-                    const std::string& service_id,
-                    const std::string& challenge,
-                    const ChallengeCallback& callback,
+  // invokes the consent UI if so.  The arguments to ChallengePlatformKey are
+  // in |context| and |attestation_enrolled| specifies whether attestation has
+  // been enrolled for this device.
+  void CheckConsent(const ChallengeContext& context,
                     bool attestation_enrolled);
 
-  // A callback called when the user has given their consent response.  All
-  // parameters are the same as in ChallengePlatformKey except for the
-  // additional |consent_type| and |consent_response| which indicate the consent
-  // type and user response, respectively.  If the response indicates that the
-  // operation should proceed, this method invokes a certificate request.
-  void OnConsentResponse(content::WebContents* web_contents,
-                         const std::string& service_id,
-                         const std::string& challenge,
-                         const ChallengeCallback& callback,
+  // A callback called when the user has given their consent response.  The
+  // arguments to ChallengePlatformKey are in |context|.  |consent_type| and
+  // |consent_response| indicate the consent type and user response,
+  // respectively.  If the response indicates that the operation should proceed,
+  // this method invokes a certificate request.
+  void OnConsentResponse(const ChallengeContext& context,
                          ConsentType consent_type,
                          ConsentResponse consent_response);
 
   // A callback called when an attestation certificate request operation
-  // completes.  |service_id|, |challenge|, and |callback| are the same as in
-  // ChallengePlatformKey.  |user_id| identifies the user for which the
-  // certificate was requested.  |operation_success| is true iff the certificate
-  // request operation succeeded.  |certificate| holds the certificate for the
-  // platform key on success.  If the certificate request was successful, this
-  // method invokes a request to sign the challenge.
-  void OnCertificateReady(const std::string& user_id,
-                          const std::string& service_id,
-                          const std::string& challenge,
-                          const ChallengeCallback& callback,
+  // completes.  The arguments to ChallengePlatformKey are in |context|.
+  // |user_id| identifies the user for which the certificate was requested.
+  // |operation_success| is true iff the certificate request operation
+  // succeeded.  |certificate| holds the certificate for the platform key on
+  // success.  If the certificate request was successful, this method invokes a
+  // request to sign the challenge.  If the operation timed out prior to this
+  // method being called, this method does nothing - notably, the callback is
+  // not invoked.
+  void OnCertificateReady(const ChallengeContext& context,
+                          const std::string& user_id,
+                          scoped_ptr<base::Timer> timer,
                           bool operation_success,
                           const std::string& certificate);
 
+  // A callback run after a constant delay to handle timeouts for lengthy
+  // certificate requests.  |context.callback| will be invoked with a TIMEOUT
+  // result.
+  void OnCertificateTimeout(const ChallengeContext& context);
+
   // A callback called when a challenge signing request has completed.  The
   // |certificate| is the platform certificate for the key which signed the
-  // |challenge|.  |callback| is the same as in ChallengePlatformKey.
+  // |challenge|.  The arguments to ChallengePlatformKey are in |context|.
   // |operation_success| is true iff the challenge signing operation was
   // successful.  If it was successful, |response_data| holds the challenge
-  // response and the method will invoke |callback|.
-  void OnChallengeReady(const std::string& certificate,
-                        const std::string& challenge,
-                        const ChallengeCallback& callback,
+  // response and the method will invoke |context.callback|.
+  void OnChallengeReady(const ChallengeContext& context,
+                        const std::string& certificate,
                         bool operation_success,
                         const std::string& response_data);
 
   // Gets prefs associated with the given |web_contents|.  If prefs have been
   // set explicitly using set_testing_prefs(), then these are always returned.
   // If no prefs are associated with |web_contents| then NULL is returned.
   PrefService* GetPrefs(content::WebContents* web_contents);
 
   // Gets the URL associated with the given |web_contents|.  If a URL as been
   // set explicitly using set_testing_url(), then this value is always returned.
@@ skipping 38 matching lines @@
 
   AttestationFlow* attestation_flow_;
   scoped_ptr<AttestationFlow> default_attestation_flow_;
   cryptohome::AsyncMethodCaller* async_caller_;
   CryptohomeClient* cryptohome_client_;
   UserManager* user_manager_;
   Delegate* delegate_;
   scoped_ptr<Delegate> default_delegate_;
   PrefService* testing_prefs_;
   GURL testing_url_;
-
-  // Note: This should remain the last member so it'll be destroyed and
-  // invalidate the weak pointers before any other members are destroyed.
-  base::WeakPtrFactory<PlatformVerificationFlow> weak_factory_;
+  base::TimeDelta timeout_delay_;
 
   DISALLOW_COPY_AND_ASSIGN(PlatformVerificationFlow);
 };
 
 }  // namespace attestation
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_ATTESTATION_PLATFORM_VERIFICATION_FLOW_H_