Linux: Adjust /proc/pid/oom_adj to sacrifice plugin and renderer processes to...

chrome/browser/zygote_host_linux.cc

 // Copyright (c) 2009 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 "chrome/browser/zygote_host_linux.h"
 
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ skipping 31 matching lines @@
       setenv(saved_envvar, value, 1 /* overwrite */);
     else
       unsetenv(saved_envvar);
 
     free(saved_envvar);
   }
 }
 
 ZygoteHost::ZygoteHost()
     : pid_(-1),
-      init_(false) {
+      init_(false),
+      using_suid_sandbox_(false) {
 }
 
 ZygoteHost::~ZygoteHost() {
   if (init_)
     close(control_fd_);
 }
 
 void ZygoteHost::Init(const std::string& sandbox_cmd) {
   DCHECK(!init_);
   init_ = true;
@@ skipping 30 matching lines @@
   if (browser_command_line.HasSwitch(switches::kEnableLogging)) {
     // Append with value to support --enable-logging=stderr.
     cmd_line.AppendSwitchWithValue(switches::kEnableLogging,
                                    browser_command_line.GetSwitchValueASCII(
                                        switches::kEnableLogging));
   }
   if (browser_command_line.HasSwitch(switches::kEnableSeccompSandbox)) {
     cmd_line.AppendSwitch(switches::kEnableSeccompSandbox);
   }
 
-  const char* sandbox_binary = sandbox_cmd.c_str();
+  sandbox_binary_ = sandbox_cmd.c_str();
   struct stat st;
 
-  bool using_suid_sandbox = false;
-  if (!sandbox_cmd.empty() && stat(sandbox_binary, &st) == 0) {
-    if (access(sandbox_binary, X_OK) == 0 &&
+  if (!sandbox_cmd.empty() && stat(sandbox_binary_.c_str(), &st) == 0) {
+    if (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(ASCIIToWide(sandbox_binary));
+      using_suid_sandbox_ = true;
+      cmd_line.PrependWrapper(ASCIIToWide(sandbox_binary_.c_str()));
 
       SaveSUIDUnsafeEnvironmentVariables();
     } else {
       LOG(FATAL) << "The SUID sandbox helper binary was found, but is not "
                     "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.";
+                 << sandbox_binary_ << " is mode 4755 and owned by root.";
     }
   }
 
   // Start up the sandbox host process and get the file descriptor for the
   // renderers to talk to it.
   const int sfd = Singleton<RenderSandboxHostLinux>()->GetRendererSocket();
   fds_to_map.push_back(std::make_pair(sfd, 5));
 
   int dummy_fd = -1;
-  if (using_suid_sandbox) {
+  if (using_suid_sandbox_) {
     dummy_fd = socket(PF_UNIX, SOCK_DGRAM, 0);
     CHECK(dummy_fd >= 0);
     fds_to_map.push_back(std::make_pair(dummy_fd, 7));
   }
 
   base::ProcessHandle process;
   base::LaunchApp(cmd_line.argv(), fds_to_map, false, &process);
   CHECK(process != -1) << "Failed to launch zygote process";
 
-  if (using_suid_sandbox) {
+  if (using_suid_sandbox_) {
     // In the SUID sandbox, the real zygote is forked from the sandbox.
     // We need to look for it.
     // But first, wait for the zygote to tell us it's running.
     // The sending code is in chrome/browser/zygote_main_linux.cc.
     std::vector<int> fds_vec;
     const int kExpectedLength = sizeof(kZygoteMagic);
     char buf[kExpectedLength];
     const ssize_t len = base::RecvMsg(fds[0], buf, sizeof(buf), &fds_vec);
     CHECK(len == kExpectedLength) << "Incorrect zygote magic length";
     CHECK(0 == strcmp(buf, kZygoteMagic)) << "Incorrect zygote magic";
 
     std::string inode_output;
     ino_t inode = 0;
     // Figure out the inode for |dummy_fd|, close |dummy_fd| on our end,
     // and find the zygote process holding |dummy_fd|.
     if (base::FileDescriptorGetInode(&inode, dummy_fd)) {
       close(dummy_fd);
       std::vector<std::string> get_inode_cmdline;
-      get_inode_cmdline.push_back(sandbox_binary);
+      get_inode_cmdline.push_back(sandbox_binary_);
       get_inode_cmdline.push_back(base::kFindInodeSwitch);
       get_inode_cmdline.push_back(Int64ToString(inode));
       CommandLine get_inode_cmd(get_inode_cmdline);
       if (base::GetAppOutput(get_inode_cmd, &inode_output)) {
         StringToInt(inode_output, &pid_);
       }
     }
     CHECK(pid_ > 0) << "Did not find zygote process";
 
     if (process != pid_) {
@@ skipping 30 matching lines @@
     fds.push_back(i->second);
   }
 
   if (!base::SendMsg(control_fd_, pickle.data(), pickle.size(), fds))
     return base::kNullProcessHandle;
 
   pid_t pid;
   if (HANDLE_EINTR(read(control_fd_, &pid, sizeof(pid))) != sizeof(pid))
     return base::kNullProcessHandle;
 
+  const int kRendererScore = 5;
+  if (using_suid_sandbox_) {
+    base::ProcessHandle sandbox_helper_process;
+    base::file_handle_mapping_vector dummy_map;
+    std::vector<std::string> adj_oom_score_cmdline;
+
+    adj_oom_score_cmdline.push_back(sandbox_binary_);
+    adj_oom_score_cmdline.push_back(base::kAdjustOOMScoreSwitch);
+    adj_oom_score_cmdline.push_back(Int64ToString(pid));
+    adj_oom_score_cmdline.push_back(IntToString(kRendererScore));
+    CommandLine adj_oom_score_cmd(adj_oom_score_cmdline);
+    if (base::LaunchApp(adj_oom_score_cmdline, dummy_map, false,
+                        &sandbox_helper_process)) {
+      ProcessWatcher::EnsureProcessGetsReaped(sandbox_helper_process);
+    }
+  } else {
+    base::AdjustOOMScore(pid, kRendererScore);
+  }
+
   return pid;
 }
 
 void ZygoteHost::EnsureProcessTerminated(pid_t process) {
   DCHECK(init_);
   Pickle pickle;
 
   pickle.WriteInt(kCmdReap);
   pickle.WriteInt(process);
 
@@ skipping 28 matching lines @@
       !read_pickle.ReadBool(&iter, &tmp_child_exited)) {
     LOG(WARNING) << "Error parsing DidProcessCrash response from zygote.";
     return false;
   }
 
   if (child_exited)
     *child_exited = tmp_child_exited;
 
   return did_crash;
 }