sandbox/linux/services/proc_util.cc

   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 #include "sandbox/linux/services/proc_util.h"
   6
   7 #include <dirent.h>
   8 #include <errno.h>
   9 #include <fcntl.h>
  10 #include <string.h>
  11 #include <sys/stat.h>
  12 #include <sys/types.h>
  13
  14 #include "base/logging.h"
  15 #include "base/memory/scoped_ptr.h"
  16 #include "base/posix/eintr_wrapper.h"
  17 #include "base/strings/string_number_conversions.h"
  18
  19 namespace sandbox {
  20 namespace {
  21
  22 struct DIRCloser {
  23   void operator()(DIR* d) const {
  24     DCHECK(d);
  25     PCHECK(0 == closedir(d));
  26   }
  27 };
  28
  29 typedef scoped_ptr<DIR, DIRCloser> ScopedDIR;
  30
  31 base::ScopedFD OpenDirectory(const char* path) {
  32   DCHECK(path);
  33   base::ScopedFD directory_fd(
  34       HANDLE_EINTR(open(path, O_RDONLY | O_DIRECTORY | O_CLOEXEC)));
  35   PCHECK(directory_fd.is_valid());
  36   return directory_fd.Pass();
  37 }
  38
  39 }  // namespace
  40
  41 int ProcUtil::CountOpenFds(int proc_fd) {
  42   DCHECK_LE(0, proc_fd);
  43   int proc_self_fd = HANDLE_EINTR(
  44       openat(proc_fd, "self/fd/", O_DIRECTORY | O_RDONLY | O_CLOEXEC));
  45   PCHECK(0 <= proc_self_fd);
  46
  47   // Ownership of proc_self_fd is transferred here, it must not be closed
  48   // or modified afterwards except via dir.
  49   ScopedDIR dir(fdopendir(proc_self_fd));
  50   CHECK(dir);
  51
  52   int count = 0;
  53   struct dirent e;
  54   struct dirent* de;
  55   while (!readdir_r(dir.get(), &e, &de) && de) {
  56     if (strcmp(e.d_name, ".") == 0 || strcmp(e.d_name, "..") == 0) {
  57       continue;
  58     }
  59
  60     int fd_num;
  61     CHECK(base::StringToInt(e.d_name, &fd_num));
  62     if (fd_num == proc_fd || fd_num == proc_self_fd) {
  63       continue;
  64     }
  65
  66     ++count;
  67   }
  68   return count;
  69 }
  70
  71 bool ProcUtil::HasOpenDirectory(int proc_fd) {
  72   DCHECK_LE(0, proc_fd);
  73   int proc_self_fd =
  74       openat(proc_fd, "self/fd/", O_DIRECTORY | O_RDONLY | O_CLOEXEC);
  75
  76   PCHECK(0 <= proc_self_fd);
  77
  78   // Ownership of proc_self_fd is transferred here, it must not be closed
  79   // or modified afterwards except via dir.
  80   ScopedDIR dir(fdopendir(proc_self_fd));
  81   CHECK(dir);
  82
  83   struct dirent e;
  84   struct dirent* de;
  85   while (!readdir_r(dir.get(), &e, &de) && de) {
  86     if (strcmp(e.d_name, ".") == 0 || strcmp(e.d_name, "..") == 0) {
  87       continue;
  88     }
  89
  90     int fd_num;
  91     CHECK(base::StringToInt(e.d_name, &fd_num));
  92     if (fd_num == proc_fd || fd_num == proc_self_fd) {
  93       continue;
  94     }
  95
  96     struct stat s;
  97     // It's OK to use proc_self_fd here, fstatat won't modify it.
  98     CHECK(fstatat(proc_self_fd, e.d_name, &s, 0) == 0);
  99     if (S_ISDIR(s.st_mode)) {
 100       return true;
 101     }
 102   }
 103
 104   // No open unmanaged directories found.
 105   return false;
 106 }
 107
 108 bool ProcUtil::HasOpenDirectory() {
 109   base::ScopedFD proc_fd(
 110       HANDLE_EINTR(open("/proc/", O_DIRECTORY | O_RDONLY | O_CLOEXEC)));
 111   return HasOpenDirectory(proc_fd.get());
 112 }
 113
 114 // static
 115 base::ScopedFD ProcUtil::OpenProc() {
 116   return OpenDirectory("/proc/");
 117 }
 118
 119 }  // namespace sandbox