[3p-Conflicts] Now ignore wanted modules in IsBlacklisted()

We explicitly allow all modules seemingly signed by the signer
of the process's main exe to load into the process.

Bug: 819793
Change-Id: I3636b8251cb82cd1d4a5f69f3899ea4516b1b00a
Reviewed-on: https://chromium-review.googlesource.com/952074
Commit-Queue: Patrick Monette <pmonette@chromium.org>
Reviewed-by: Greg Thompson <grt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543091}

chrome/browser/conflicts/module_list_filter_win.cc

@@ -6,10 +6,12 @@
 
 #include <string>
 
+#include "base/base_paths.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/i18n/case_conversion.h"
 #include "base/logging.h"
+#include "base/path_service.h"
 #include "base/sha1.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
@@ -61,10 +63,15 @@ ModuleListFilter::~ModuleListFilter() = default;
 bool ModuleListFilter::Initialize(const base::FilePath& module_list_path) {
   DCHECK(!initialized_);
 
+  base::FilePath exe_path;
   std::string contents;
-  initialized_ = base::ReadFileToString(module_list_path, &contents) &&
+  initialized_ = base::PathService::Get(base::FILE_EXE, &exe_path) &&
+                 base::ReadFileToString(module_list_path, &contents) &&
                  module_list_.ParseFromString(contents);
 
+  if (initialized_)
+    GetCertificateInfo(exe_path, &exe_certificate_info_);
+
   return initialized_;
 }
 
@@ -93,6 +100,15 @@ ModuleListFilter::IsBlacklisted(const ModuleInfoKey& module_key,
                                 const ModuleInfoData& module_data) const {
   DCHECK(initialized_);
 
+  // Ignore modules whose signing cert's Subject field matches the one in the
+  // current executable. No attempt is made to check the validity of module
+  // signatures or of signing certs.
+  if (exe_certificate_info_.type != CertificateType::NO_CERTIFICATE &&
+      exe_certificate_info_.subject ==
+          module_data.inspection_result->certificate_info.subject) {
+    return nullptr;
+  }
+
   // Precompute the hash of the basename and of the code id.
   const std::string module_basename_hash =
       base::SHA1HashString(base::UTF16ToUTF8(

chrome/browser/conflicts/module_list_filter_win.h

@@ -8,6 +8,7 @@
 #include <memory>
 
 #include "base/macros.h"
+#include "chrome/browser/conflicts/module_info_util_win.h"
 #include "chrome/browser/conflicts/proto/module_list.pb.h"
 
 struct ModuleInfoKey;
@@ -49,6 +50,9 @@ class ModuleListFilter {
       const ModuleInfoData& module_data) const;
 
  private:
+  // The certificate info of the current executable.
+  CertificateInfo exe_certificate_info_;
+
   chrome::conflicts::ModuleList module_list_;
 
   // Indicates if Initalize() has been succesfully called.