Add the first part of Chrome-side support for NaCl validation caching.

This code injects a validation caching implementation into sel_ldr that hashes
all of the data it is given and then queries against a stub database.  The stub
database returns whatever value is specified in the NACL_VALIDATION_RESULT env
var for all validation requests.  This code is inactive in Chrome unless
NACL_VALIDATION_CACHE=1 is set in the environment.

BUG= http://code.google.com/p/nativeclient/issues/detail?id=2515
TEST= unit_tests --gtest_filter=NaClValidationQueryTest*

Review URL: https://chromiumcodereview.appspot.com/9553009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@127304 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 93 insertions, 0 deletions

diff --git a/chrome/nacl/nacl_validation_query.h b/chrome/nacl/nacl_validation_query.h
new file mode 100644
index 0000000..1a21bb4
--- /dev/null
+++ b/chrome/nacl/nacl_validation_query.h
@@ -0,0 +1,93 @@
+// Copyright (c) 2012 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_NACL_NACL_VALIDATION_QUERY_H_
+#define CHROME_NACL_NACL_VALIDATION_QUERY_H_
+#pragma once
+
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/string_piece.h"
+#include "crypto/hmac.h"
+
+struct NaClValidationCache;
+class NaClValidationDB;
+class NaClValidationQuery;
+
+class NaClValidationQueryContext {
+ public:
+  NaClValidationQueryContext(NaClValidationDB* db,
+                             const std::string& profile_key,
+                             const std::string& nacl_version);
+
+  NaClValidationQuery* CreateQuery();
+
+ private:
+  NaClValidationDB* db_;
+
+  // A key used by HMAC that is specific to this installation of Chrome.
+  std::string profile_key_;
+
+  // Bytes indicating the "version" of the validator being used.  This is used
+  // to implicitly invalidate the cache - changing the version will change the
+  // hashes that are produced.
+  std::string nacl_version_;
+};
+
+class NaClValidationQuery {
+ public:
+  // SHA256 digest size.
+  static const int kDigestLength = 32;
+
+  NaClValidationQuery(NaClValidationDB* db, const std::string& profile_key);
+
+  void AddData(const char* data, size_t length);
+  void AddData(const unsigned char* data, size_t length);
+  void AddData(const base::StringPiece& data);
+
+  int QueryKnownToValidate();
+
+  void SetKnownToValidate();
+
+  NaClValidationQueryContext* context_;
+
+ private:
+  enum QueryState {
+    READY,
+    GET_CALLED,
+    SET_CALLED
+  };
+
+  // The HMAC interface currently does not support incremental signing.  To work
+  // around this, each piece of data is signed and the signature is added to a
+  // buffer.  If there is not enough space in the buffer to accommodate new
+  // data, the buffer contents are signed and the new signature replaces the
+  // contents of the buffer.  CompressBuffer performs this operation.  In
+  // affect, a hash tree is constructed to emulate incremental signing.
+  void CompressBuffer();
+
+  // Track the state of the query to detect suspicious method calls.
+  QueryState state_;
+
+  crypto::HMAC hasher_;
+  NaClValidationDB* db_;
+
+  // The size of buffer_ is a somewhat arbitrary choice.  It needs to be at
+  // at least kDigestLength * 2, but it can be arbitrarily large.  In practice
+  // there are 4 calls to AddData (version, architechture, cpu features, and
+  // code), so 4 times digest length means the buffer will not need to be
+  // compressed as an intermediate step in the expected use cases.
+  char buffer_[kDigestLength * 4];
+  int buffer_length_;
+
+  DISALLOW_COPY_AND_ASSIGN(NaClValidationQuery);
+};
+
+// Create a validation cache interface for use by sel_ldr.
+struct NaClValidationCache* CreateValidationCache(
+    NaClValidationDB* db, const std::string& profile_key,
+    const std::string& nacl_version);
+
+#endif  // CHROME_NACL_NACL_VALIDATION_QUERY_H_