Add SBX_CHROME_API_RQ to nacl_helper env whitelist

components/nacl/zygote/nacl_fork_delegate_linux.cc

 // 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.
 
 #include "components/nacl/zygote/nacl_fork_delegate_linux.h"
 
 #include <signal.h>
 #include <stdlib.h>
 #include <sys/resource.h>
 #include <sys/socket.h>
@@ skipping 39 matching lines @@
 // NACL_ENV_PASSTHROUGH="PATH,CWD" would pass both $PATH and $CWD to the child
 // process.
 const char kNaClEnvPassthrough[] = "NACL_ENV_PASSTHROUGH";
 char kNaClEnvPassthroughDelimiter = ',';
 
 // The following environment variables are always passed through if they exist
 // in the parent process.
 const char kNaClExeStderr[] = "NACL_EXE_STDERR";
 const char kNaClExeStdout[] = "NACL_EXE_STDOUT";
 const char kNaClVerbosity[] = "NACLVERBOSITY";
+const char kSbxChromeApiRq[] = "SBX_CHROME_API_RQ";

[jln (very slow on Chromium), 2014/06/18 23:14:38]

Could you include sandbox/linux/suid/sandbox.h instead and use
kSandboxEnvironmentApiRequest?

Another possibility would be to add some GetSandboxAPIEnvironmentVariables() API
to the SetuidSandboxClient class that could add variables to a vector<string>
(and would add only this one) and simply call this from
AddPassthroughEnvToOptions.

[elijahtaylor1, 2014/06/18 23:48:18]

I did the first suggestion because the second seemed like overkill to me.

 
 #if defined(ARCH_CPU_X86)
 bool NonZeroSegmentBaseIsSlow() {
   base::CPU cpuid;
   // Using a non-zero segment base is known to be very slow on Intel
   // Atom CPUs.  See "Segmentation-based Memory Protection Mechanism
   // on Intel Atom Microarchitecture: Coding Optimizations" (Leonardo
   // Potenza, Intel).
   //
   // The following list of CPU model numbers is taken from:
@@ skipping 353 matching lines @@
   scoped_ptr<base::Environment> env(base::Environment::Create());
   std::string pass_through_string;
   std::vector<std::string> pass_through_vars;
   if (env->GetVar(kNaClEnvPassthrough, &pass_through_string)) {
     base::SplitString(
         pass_through_string, kNaClEnvPassthroughDelimiter, &pass_through_vars);
   }
   pass_through_vars.push_back(kNaClExeStderr);
   pass_through_vars.push_back(kNaClExeStdout);
   pass_through_vars.push_back(kNaClVerbosity);
+  pass_through_vars.push_back(kSbxChromeApiRq);
   for (size_t i = 0; i < pass_through_vars.size(); ++i) {
     std::string temp;
     if (env->GetVar(pass_through_vars[i].c_str(), &temp))
       options->environ[pass_through_vars[i]] = temp;
   }
 }
 
 }  // namespace nacl