Make chrome_elf use thunks instead of function pointers.

chrome_elf/thunk_getter.cc

Index: chrome_elf/thunk_getter.cc
diff --git a/chrome_elf/thunk_getter.cc b/chrome_elf/thunk_getter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..d127e83b0f53d09b007248cd43fce1c7bff28817
--- /dev/null
+++ b/chrome_elf/thunk_getter.cc
@@ -0,0 +1,143 @@
+// 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.
+
+#include <stdint.h>
+#include <windows.h>
+
+#include "base/basictypes.h"
+#include "sandbox/win/src/interception_internal.h"
+#include "sandbox/win/src/internal_types.h"
+#include "sandbox/win/src/sandbox_utils.h"
+#include "sandbox/win/src/service_resolver.h"
+
+namespace {
+enum Version {
+  VERSION_PRE_XP_SP2 = 0,  // Not supported.
+  VERSION_XP_SP2,
+  VERSION_SERVER_2003,  // Also includes XP Pro x64 and Server 2003 R2.
+  VERSION_VISTA,        // Also includes Windows Server 2008.
+  VERSION_WIN7,         // Also includes Windows Server 2008 R2.
+  VERSION_WIN8,         // Also includes Windows Server 2012.
+  VERSION_WIN8_1,
+  VERSION_WIN_LAST,  // Indicates error condition.
+};
+
+// Whether a process is running under WOW64 (the wrapper that allows 32-bit
+// processes to run on 64-bit versions of Windows).  This will return
+// WOW64_DISABLED for both "32-bit Chrome on 32-bit Windows" and "64-bit
+// Chrome on 64-bit Windows".  WOW64_UNKNOWN means "an error occurred", e.g.
+// the process does not have sufficient access rights to determine this.
+enum WOW64Status { WOW64_DISABLED, WOW64_ENABLED, WOW64_UNKNOWN, };
+
+WOW64Status GetWOW64StatusForCurrentProcess() {
+  typedef BOOL(WINAPI * IsWow64ProcessFunc)(HANDLE, PBOOL);
+  IsWow64ProcessFunc is_wow64_process = reinterpret_cast<IsWow64ProcessFunc>(
+      GetProcAddress(GetModuleHandle(L"kernel32.dll"), "IsWow64Process"));
+  if (!is_wow64_process)
+    return WOW64_DISABLED;
+  BOOL is_wow64 = FALSE;
+  if (!is_wow64_process(GetCurrentProcess(), &is_wow64))
+    return WOW64_UNKNOWN;
+  return is_wow64 ? WOW64_ENABLED : WOW64_DISABLED;
+}
+
+class OSInfo {
+ public:
+  struct VersionNumber {
+    int major;
+    int minor;
+    int build;
+  };
+
+  struct ServicePack {
+    int major;
+    int minor;
+  };
+
+  OSInfo() {
+    OSVERSIONINFOEX version_info = {sizeof(version_info)};
+    GetVersionEx(reinterpret_cast<OSVERSIONINFO*>(&version_info));
+    version_number_.major = version_info.dwMajorVersion;
+    version_number_.minor = version_info.dwMinorVersion;
+    version_number_.build = version_info.dwBuildNumber;
+    if ((version_number_.major == 5) && (version_number_.minor > 0)) {
+      // Treat XP Pro x64, Home Server, and Server 2003 R2 as Server 2003.
+      version_ =
+          (version_number_.minor == 1) ? VERSION_XP_SP2 : VERSION_SERVER_2003;
+      if (version_ == VERSION_XP_SP2 && version_info.wServicePackMajor < 2)
+        version_ = VERSION_PRE_XP_SP2;
+    } else if (version_number_.major == 6) {
+      switch (version_number_.minor) {
+        case 0:
+          // Treat Windows Server 2008 the same as Windows Vista.
+          version_ = VERSION_VISTA;
+          break;
+        case 1:
+          // Treat Windows Server 2008 R2 the same as Windows 7.
+          version_ = VERSION_WIN7;
+          break;
+        case 2:
+          // Treat Windows Server 2012 the same as Windows 8.
+          version_ = VERSION_WIN8;
+          break;
+        default:
+          version_ = VERSION_WIN8_1;
+          break;
+      }
+    } else if (version_number_.major > 6) {
+      version_ = VERSION_WIN_LAST;
+    } else {
+      version_ = VERSION_PRE_XP_SP2;
+    }
+
+    service_pack_.major = version_info.wServicePackMajor;
+    service_pack_.minor = version_info.wServicePackMinor;
+  }
+
+  Version version() const { return version_; }
+  VersionNumber version_number() const { return version_number_; }
+  ServicePack service_pack() const { return service_pack_; }
+
+ private:
+  Version version_;
+  VersionNumber version_number_;
+  ServicePack service_pack_;
+
+  DISALLOW_COPY_AND_ASSIGN(OSInfo);
+};
+
+}  // namespace
+
+sandbox::ServiceResolverThunk* GetThunk(bool relaxed) {
+  // Create a thunk via the appropriate ServiceResolver instance.
+  sandbox::ServiceResolverThunk* thunk = NULL;
+
+  // No thunks for unsupported OS versions.
+  OSInfo os_info;
+  if (os_info.version() <= VERSION_PRE_XP_SP2)
+    return thunk;
+
+  // Pseudo-handle, no need to close.
+  HANDLE current_process = ::GetCurrentProcess();
+
+#if defined(_WIN64)
+  // Because Windows 8 and 8.1 have different stubs in 64-bit,

[robertshield, 2014/03/04 01:47:07]

Rereading this comment, I don't like the sentence structure (very possible that
I wrote it :-)).

Can we delete the part on line 125?

[Cait (Slow), 2014/03/04 15:43:56]

Done.

+  // ServiceResolverThunk can handle all the formats in 64-bit (instead only
+  // handling 1 like it does in 32-bit versions).
+  thunk = new sandbox::ServiceResolverThunk(current_process, relaxed);
+#else
+  if (GetWOW64StatusForCurrentProcess() == WOW64_ENABLED) {
+    if (os_info.version() >= VERSION_WIN8)
+      thunk = new sandbox::Wow64W8ResolverThunk(current_process, relaxed);
+    else
+      thunk = new sandbox::Wow64ResolverThunk(current_process, relaxed);
+  } else if (os_info.version() >= VERSION_WIN8) {
+    thunk = new sandbox::Win8ResolverThunk(current_process, relaxed);
+  } else {
+    thunk = new sandbox::ServiceResolverThunk(current_process, relaxed);
+  }
+#endif
+
+  return thunk;
+}