sandbox/linux/syscall_broker/broker_common.h

   1 // Copyright 2014 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 SANDBOX_LINUX_SYSCALL_BROKER_BROKER_COMMON_H_
   6 #define SANDBOX_LINUX_SYSCALL_BROKER_BROKER_COMMON_H_
   7
   8 #include <fcntl.h>
   9 #include <stddef.h>
  10
  11 namespace sandbox {
  12
  13 namespace syscall_broker {
  14
  15 const size_t kMaxMessageLength = 4096;
  16
  17 // Some flags are local to the current process and cannot be sent over a Unix
  18 // socket. They need special treatment from the client.
  19 // O_CLOEXEC is tricky because in theory another thread could call execve()
  20 // before special treatment is made on the client, so a client needs to call
  21 // recvmsg(2) with MSG_CMSG_CLOEXEC.
  22 // To make things worse, there are two CLOEXEC related flags, FD_CLOEXEC (see
  23 // F_GETFD in fcntl(2)) and O_CLOEXEC (see F_GETFL in fcntl(2)). O_CLOEXEC
  24 // doesn't affect the semantics on execve(), it's merely a note that the
  25 // descriptor was originally opened with O_CLOEXEC as a flag. And it is sent
  26 // over unix sockets just fine, so a receiver that would (incorrectly) look at
  27 // O_CLOEXEC instead of FD_CLOEXEC may be tricked in thinking that the file
  28 // descriptor will or won't be closed on execve().
  29 const int kCurrentProcessOpenFlagsMask = O_CLOEXEC;
  30
  31 enum IPCCommand {
  32   COMMAND_INVALID = 0,
  33   COMMAND_OPEN,
  34   COMMAND_ACCESS,
  35 };
  36
  37 }  // namespace syscall_broker
  38
  39 }  // namespace sandbox
  40
  41 #endif  // SANDBOX_LINUX_SYSCALL_BROKER_BROKER_COMMON_H_