Beginning of support for extension content verification

extensions/browser/content_verifier.h

+// 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.
+
+#ifndef EXTENSIONS_BROWSER_CONTENT_VERIFIER_H_
+#define EXTENSIONS_BROWSER_CONTENT_VERIFIER_H_
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/observer_list_threadsafe.h"
+#include "extensions/browser/content_verifier_filter.h"
+#include "extensions/browser/content_verify_job.h"
+
+namespace base {
+class FilePath;
+}
+
+namespace content {
+class BrowserContext;
+}
+
+namespace extensions {
+
+// Interface for clients of ContentVerifier.
+class ContentVerifierObserver {
+ public:
+  // Called when the content verifier detects that a read of a file inside
+  // an extension did not match its expected hash.
+  virtual void ContentVerifyFailed(const std::string& extension_id) = 0;
+};
+
+// Used for managing overall content verification - both fetching content
+// hashes as needed, and supplying job objects to verify file contents as they
+// are read.
+class ContentVerifier : public base::RefCountedThreadSafe<ContentVerifier> {
+ public:
+  ContentVerifier(content::BrowserContext* context,
+                  const ContentVerifierFilter& filter);
+  void Start();
+  void Shutdown();
+
+  // Call this before reading a file within an extension. The caller owns the
+  // returned job.
+  ContentVerifyJob* CreateJobFor(const std::string& extension_id,
+                                 const base::FilePath& extension_root,
+                                 const base::FilePath& relative_path);
+
+  // Called (typically by a verification job) to indicate that verification
+  // failed while reading some file in |extension_id|.
+  void VerifyFailed(const std::string& extension_id,
+                    ContentVerifyJob::FailureReason reason);
+
+  // Observers will be called back on the same thread that they call
+  // AddObserver on.
+  void AddObserver(ContentVerifierObserver* observer);
+  void RemoveObserver(ContentVerifierObserver* observer);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ContentVerifier);
+
+  friend class base::RefCountedThreadSafe<ContentVerifier>;
+  virtual ~ContentVerifier();
+
+  // Attempts to fetch content hashes for |extension_id|.
+  void RequestFetch(const std::string& extension_id);
+
+  // Note that it is important for these to appear in increasing "severity"
+  // order, because we use this to let command line flags increase, but not
+  // decrease, the mode you're running in compared to the experiment group.
+  enum Mode {
+    // Do not try to fetch content hashes if they are missing, and do not
+    // enforce them if they are present.
+    NONE = 0,
+
+    // If content hashes are missing, try to fetch them, but do not enforce.
+    BOOTSTRAP,
+
+    // If hashes are present, enforce them. If they are missing, try to fetch
+    // them.
+    ENFORCE,
+
+    // Treat the absence of hashes the same as a verification failure.
+    ENFORCE_STRICT
+  };
+
+  static Mode GetMode();
+
+  // The mode we're running in - set once at creation.
+  const Mode mode_;
+
+  // The filter we use to decide whether to return a ContentVerifyJob.
+  ContentVerifierFilter filter_;
+
+  // The associated BrowserContext.
+  content::BrowserContext* context_;
+
+  // The set of objects interested in verification failures.
+  scoped_refptr<ObserverListThreadSafe<ContentVerifierObserver> > observers_;
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_CONTENT_VERIFIER_H_