linux: warn if we're not running with the SUID sandbox

content/browser/zygote_host_linux.cc

 // Copyright (c) 2011 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 "content/browser/zygote_host_linux.h"
 
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ skipping 100 matching lines @@
     switches::kEnableSeccompSandbox,
     switches::kNaClLinuxHelper,
   };
   cmd_line.CopySwitchesFrom(browser_command_line, kForwardSwitches,
                             arraysize(kForwardSwitches));
 
   content::GetContentClient()->browser()->AppendExtraCommandLineSwitches(
       &cmd_line, -1);
 
   sandbox_binary_ = sandbox_cmd.c_str();
-  struct stat st;
 
-  if (!sandbox_cmd.empty() && stat(sandbox_binary_.c_str(), &st) == 0) {
-    if (access(sandbox_binary_.c_str(), X_OK) == 0 &&
+  if (!sandbox_cmd.empty()) {
+    struct stat st;
+    if (stat(sandbox_binary_.c_str(), &st) == 0 &&
+        access(sandbox_binary_.c_str(), X_OK) == 0 &&
         (st.st_uid == 0) &&
         (st.st_mode & S_ISUID) &&
         (st.st_mode & S_IXOTH)) {
       using_suid_sandbox_ = true;
       cmd_line.PrependWrapper(sandbox_binary_);
 
       SaveSUIDUnsafeEnvironmentVariables();
     } else {
       LOG(FATAL) << "The SUID sandbox helper binary was found, but is not "

[Lei Zhang, 2011/08/09 09:09:45]

This message isn't quite right with this CL. If |sandbox_binary_| is
non-existent, the stat() fails and we end up here.

                     "configured correctly. Rather than run without sandboxing "
                     "I'm aborting now. You need to make sure that "
                  << sandbox_binary_ << " is mode 4755 and owned by root.";
     }
+  } else {
+    LOG(WARNING) << "Running without the SUID sandbox! See "
+        "http://code.google.com/p/chromium/wiki/LinuxSUIDSandboxDevelopment "
+        "for more information on developing with the sandbox on.";
   }
 
   // Start up the sandbox host process and get the file descriptor for the
   // renderers to talk to it.
   const int sfd = RenderSandboxHostLinux::GetInstance()->GetRendererSocket();
   fds_to_map.push_back(std::make_pair(sfd, 5));
 
   int dummy_fd = -1;
   if (using_suid_sandbox_) {
     dummy_fd = socket(PF_UNIX, SOCK_DGRAM, 0);
@@ skipping 217 matching lines @@
       !read_pickle.ReadInt(&iter, &tmp_exit_code)) {
     LOG(WARNING) << "Error parsing GetTerminationStatus response from zygote.";
     return base::TERMINATION_STATUS_NORMAL_TERMINATION;
   }
 
   if (exit_code)
     *exit_code = tmp_exit_code;
 
   return static_cast<base::TerminationStatus>(status);
 }