content/zygote/zygote_linux.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_ZYGOTE_ZYGOTE_LINUX_H_
   6 #define CONTENT_ZYGOTE_ZYGOTE_LINUX_H_
   7
   8 #include <stddef.h>
   9
  10 #include <string>
  11
  12 #include "base/containers/small_map.h"
  13 #include "base/files/scoped_file.h"
  14 #include "base/memory/scoped_vector.h"
  15 #include "base/posix/global_descriptors.h"
  16 #include "base/process/kill.h"
  17 #include "base/process/process.h"
  18
  19 namespace base {
  20 class Pickle;
  21 class PickleIterator;
  22 }
  23
  24 namespace content {
  25
  26 class ZygoteForkDelegate;
  27
  28 // This is the object which implements the zygote. The ZygoteMain function,
  29 // which is called from ChromeMain, simply constructs one of these objects and
  30 // runs it.
  31 class Zygote {
  32  public:
  33   Zygote(int sandbox_flags, ScopedVector<ZygoteForkDelegate> helpers,
  34          const std::vector<base::ProcessHandle>& extra_children,
  35          const std::vector<int>& extra_fds);
  36   ~Zygote();
  37
  38   bool ProcessRequests();
  39
  40  private:
  41   struct ZygoteProcessInfo {
  42     // Pid from inside the Zygote's PID namespace.
  43     base::ProcessHandle internal_pid;
  44     // Keeps track of which fork delegate helper the process was started from.
  45     ZygoteForkDelegate* started_from_helper;
  46   };
  47   typedef base::SmallMap< std::map<base::ProcessHandle, ZygoteProcessInfo> >
  48       ZygoteProcessMap;
  49
  50   // Retrieve a ZygoteProcessInfo from the process_info_map_.
  51   // Returns true and write to process_info if |pid| can be found, return
  52   // false otherwise.
  53   bool GetProcessInfo(base::ProcessHandle pid,
  54                       ZygoteProcessInfo* process_info);
  55
  56   // Returns true if the SUID sandbox is active.
  57   bool UsingSUIDSandbox() const;
  58   // Returns true if the NS sandbox is active.
  59   bool UsingNSSandbox() const;
  60
  61   // ---------------------------------------------------------------------------
  62   // Requests from the browser...
  63
  64   // Read and process a request from the browser. Returns true if we are in a
  65   // new process and thus need to unwind back into ChromeMain.
  66   bool HandleRequestFromBrowser(int fd);
  67
  68   void HandleReapRequest(int fd, base::PickleIterator iter);
  69
  70   // Get the termination status of |real_pid|. |real_pid| is the PID as it
  71   // appears outside of the sandbox.
  72   // Return true if it managed to get the termination status and return the
  73   // status in |status| and the exit code in |exit_code|.
  74   bool GetTerminationStatus(base::ProcessHandle real_pid, bool known_dead,
  75                             base::TerminationStatus* status,
  76                             int* exit_code);
  77
  78   void HandleGetTerminationStatus(int fd,
  79                                   base::PickleIterator iter);
  80
  81   // This is equivalent to fork(), except that, when using the SUID sandbox, it
  82   // returns the real PID of the child process as it appears outside the
  83   // sandbox, rather than returning the PID inside the sandbox.  The child's
  84   // real PID is determined by having it call content::SendZygoteChildPing(int)
  85   // using the |pid_oracle| descriptor.
  86   // Finally, when using a ZygoteForkDelegate helper, |uma_name|, |uma_sample|,
  87   // and |uma_boundary_value| may be set if the helper wants to make a UMA
  88   // report via UMA_HISTOGRAM_ENUMERATION.
  89   int ForkWithRealPid(const std::string& process_type,
  90                       const base::GlobalDescriptors::Mapping& fd_mapping,
  91                       const std::string& channel_id,
  92                       base::ScopedFD pid_oracle,
  93                       std::string* uma_name,
  94                       int* uma_sample,
  95                       int* uma_boundary_value);
  96
  97   // Unpacks process type and arguments from |iter| and forks a new process.
  98   // Returns -1 on error, otherwise returns twice, returning 0 to the child
  99   // process and the child process ID to the parent process, like fork().
 100   base::ProcessId ReadArgsAndFork(base::PickleIterator iter,
 101                                   ScopedVector<base::ScopedFD> fds,
 102                                   std::string* uma_name,
 103                                   int* uma_sample,
 104                                   int* uma_boundary_value);
 105
 106   // Handle a 'fork' request from the browser: this means that the browser
 107   // wishes to start a new renderer. Returns true if we are in a new process,
 108   // otherwise writes the child_pid back to the browser via |fd|. Writes a
 109   // child_pid of -1 on error.
 110   bool HandleForkRequest(int fd,
 111                          base::PickleIterator iter,
 112                          ScopedVector<base::ScopedFD> fds);
 113
 114   bool HandleGetSandboxStatus(int fd,
 115                               base::PickleIterator iter);
 116
 117   // The Zygote needs to keep some information about each process. Most
 118   // notably what the PID of the process is inside the PID namespace of
 119   // the Zygote and whether or not a process was started by the
 120   // ZygoteForkDelegate helper.
 121   ZygoteProcessMap process_info_map_;
 122
 123   const int sandbox_flags_;
 124   ScopedVector<ZygoteForkDelegate> helpers_;
 125
 126   // Count of how many fork delegates for which we've invoked InitialUMA().
 127   size_t initial_uma_index_;
 128
 129   // This vector contains the PIDs of any child processes which have been
 130   // created prior to the construction of the Zygote object, and must be reaped
 131   // before the Zygote exits. The Zygote will perform a blocking wait on these
 132   // children, so they must be guaranteed to be exiting by the time the Zygote
 133   // exits.
 134   std::vector<base::ProcessHandle> extra_children_;
 135
 136   // This vector contains the FDs that must be closed before reaping the extra
 137   // children.
 138   std::vector<int> extra_fds_;
 139 };
 140
 141 }  // namespace content
 142
 143 #endif  // CONTENT_ZYGOTE_ZYGOTE_LINUX_H_