File: process_util_linux.cc

package info (click to toggle)
icedove 1:52.3.0-4~deb8u2
  • links: PTS, VCS
  • area: main
  • in suites: jessie
  • size: 1,705,608 kB
  • sloc: cpp: 5,079,451; ansic: 2,051,639; python: 458,782; java: 241,615; xml: 192,378; asm: 178,649; sh: 81,867; makefile: 24,692; perl: 16,874; objc: 4,389; yacc: 1,816; ada: 1,697; lex: 1,257; pascal: 1,251; cs: 879; exp: 499; php: 436; lisp: 258; awk: 152; sed: 51; ruby: 47; csh: 27
file content (274 lines) | stat: -rw-r--r-- 7,234 bytes parent folder | download | duplicates (5)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
// Copyright (c) 2008 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 "base/process_util.h"

#include <ctype.h>
#include <fcntl.h>
#include <memory>
#include <unistd.h>
#include <string>
#include <sys/types.h>
#include <sys/wait.h>

#include "base/eintr_wrapper.h"
#include "base/file_util.h"
#include "base/logging.h"
#include "base/string_util.h"
#include "nsLiteralString.h"
#include "mozilla/UniquePtr.h"

#include "prenv.h"
#include "prmem.h"

#ifdef MOZ_WIDGET_GONK
/*
 * AID_APP is the first application UID used by Android. We're using
 * it as our unprivilegied UID.  This ensure the UID used is not
 * shared with any other processes than our own childs.
 */
# include <private/android_filesystem_config.h>
# define CHILD_UNPRIVILEGED_UID AID_APP
# define CHILD_UNPRIVILEGED_GID AID_APP
#else
/*
 * On platforms that are not gonk based, we fall back to an arbitrary
 * UID. This is generally the UID for user `nobody', albeit it is not
 * always the case.
 */
# define CHILD_UNPRIVILEGED_UID 65534
# define CHILD_UNPRIVILEGED_GID 65534
#endif

namespace {

enum ParsingState {
  KEY_NAME,
  KEY_VALUE
};

static mozilla::EnvironmentLog gProcessLog("MOZ_PROCESS_LOG");

}  // namespace

namespace base {

class EnvironmentEnvp
{
public:
  EnvironmentEnvp()
    : mEnvp(PR_DuplicateEnvironment()) {}

  explicit EnvironmentEnvp(const environment_map &em)
  {
    mEnvp = (char **)PR_Malloc(sizeof(char *) * (em.size() + 1));
    if (!mEnvp) {
      return;
    }
    char **e = mEnvp;
    for (environment_map::const_iterator it = em.begin();
         it != em.end(); ++it, ++e) {
      std::string str = it->first;
      str += "=";
      str += it->second;
      size_t len = str.length() + 1;
      *e = static_cast<char*>(PR_Malloc(len));
      memcpy(*e, str.c_str(), len);
    }
    *e = NULL;
  }

  ~EnvironmentEnvp()
  {
    if (!mEnvp) {
      return;
    }
    for (char **e = mEnvp; *e; ++e) {
      PR_Free(*e);
    }
    PR_Free(mEnvp);
  }

  char * const *AsEnvp() { return mEnvp; }

  void ToMap(environment_map &em)
  {
    if (!mEnvp) {
      return;
    }
    em.clear();
    for (char **e = mEnvp; *e; ++e) {
      const char *eq;
      if ((eq = strchr(*e, '=')) != NULL) {
        std::string varname(*e, eq - *e);
        em[varname.c_str()] = &eq[1];
      }
    }
  }

private:
  char **mEnvp;
};

class Environment : public environment_map
{
public:
  Environment()
  {
    EnvironmentEnvp envp;
    envp.ToMap(*this);
  }

  char * const *AsEnvp() {
    mEnvp.reset(new EnvironmentEnvp(*this));
    return mEnvp->AsEnvp();
  }

  void Merge(const environment_map &em)
  {
    for (const_iterator it = em.begin(); it != em.end(); ++it) {
      (*this)[it->first] = it->second;
    }
  }
private:
  std::auto_ptr<EnvironmentEnvp> mEnvp;
};

bool LaunchApp(const std::vector<std::string>& argv,
               const file_handle_mapping_vector& fds_to_remap,
               bool wait, ProcessHandle* process_handle) {
  return LaunchApp(argv, fds_to_remap, environment_map(),
                   wait, process_handle);
}

bool LaunchApp(const std::vector<std::string>& argv,
               const file_handle_mapping_vector& fds_to_remap,
               const environment_map& env_vars_to_set,
               bool wait, ProcessHandle* process_handle,
               ProcessArchitecture arch) {
  return LaunchApp(argv, fds_to_remap, env_vars_to_set,
                   PRIVILEGES_INHERIT,
                   wait, process_handle);
}

bool LaunchApp(const std::vector<std::string>& argv,
               const file_handle_mapping_vector& fds_to_remap,
               const environment_map& env_vars_to_set,
               ChildPrivileges privs,
               bool wait, ProcessHandle* process_handle,
               ProcessArchitecture arch) {
  mozilla::UniquePtr<char*[]> argv_cstr(new char*[argv.size() + 1]);
  // Illegal to allocate memory after fork and before execvp
  InjectiveMultimap fd_shuffle1, fd_shuffle2;
  fd_shuffle1.reserve(fds_to_remap.size());
  fd_shuffle2.reserve(fds_to_remap.size());

  Environment env;
  env.Merge(env_vars_to_set);
  char * const *envp = env.AsEnvp();
  if (!envp) {
    DLOG(ERROR) << "FAILED to duplicate environment for: " << argv_cstr[0];
    return false;
  }

  pid_t pid = fork();
  if (pid < 0)
    return false;

  if (pid == 0) {
    for (file_handle_mapping_vector::const_iterator
        it = fds_to_remap.begin(); it != fds_to_remap.end(); ++it) {
      fd_shuffle1.push_back(InjectionArc(it->first, it->second, false));
      fd_shuffle2.push_back(InjectionArc(it->first, it->second, false));
    }

    if (!ShuffleFileDescriptors(&fd_shuffle1))
      _exit(127);

    CloseSuperfluousFds(fd_shuffle2);

    for (size_t i = 0; i < argv.size(); i++)
      argv_cstr[i] = const_cast<char*>(argv[i].c_str());
    argv_cstr[argv.size()] = NULL;

    SetCurrentProcessPrivileges(privs);

    execve(argv_cstr[0], argv_cstr.get(), envp);
    // if we get here, we're in serious trouble and should complain loudly
    // NOTE: This is async signal unsafe; it could deadlock instead.  (But
    // only on debug builds; otherwise it's a signal-safe no-op.)
    DLOG(ERROR) << "FAILED TO exec() CHILD PROCESS, path: " << argv_cstr[0];
    _exit(127);
  } else {
    gProcessLog.print("==> process %d launched child process %d\n",
                      GetCurrentProcId(), pid);
    if (wait)
      HANDLE_EINTR(waitpid(pid, 0, 0));

    if (process_handle)
      *process_handle = pid;
  }

  return true;
}

bool LaunchApp(const CommandLine& cl,
               bool wait, bool start_hidden,
               ProcessHandle* process_handle) {
  file_handle_mapping_vector no_files;
  return LaunchApp(cl.argv(), no_files, wait, process_handle);
}

void SetCurrentProcessPrivileges(ChildPrivileges privs) {
  if (privs == PRIVILEGES_INHERIT) {
    return;
  }

  gid_t gid = CHILD_UNPRIVILEGED_GID;
  uid_t uid = CHILD_UNPRIVILEGED_UID;
#ifdef MOZ_WIDGET_GONK
  {
    static bool checked_pix_max, pix_max_ok;
    if (!checked_pix_max) {
      checked_pix_max = true;
      int fd = open("/proc/sys/kernel/pid_max", O_CLOEXEC | O_RDONLY);
      if (fd < 0) {
        DLOG(ERROR) << "Failed to open pid_max";
        _exit(127);
      }
      char buf[PATH_MAX];
      ssize_t len = read(fd, buf, sizeof(buf) - 1);
      close(fd);
      if (len < 0) {
        DLOG(ERROR) << "Failed to read pid_max";
        _exit(127);
      }
      buf[len] = '\0';
      int pid_max = atoi(buf);
      pix_max_ok =
        (pid_max + CHILD_UNPRIVILEGED_UID > CHILD_UNPRIVILEGED_UID);
    }
    if (!pix_max_ok) {
      DLOG(ERROR) << "Can't safely get unique uid/gid";
      _exit(127);
    }
    gid += getpid();
    uid += getpid();
  }
#endif
  if (setgid(gid) != 0) {
    DLOG(ERROR) << "FAILED TO setgid() CHILD PROCESS";
    _exit(127);
  }
  if (setuid(uid) != 0) {
    DLOG(ERROR) << "FAILED TO setuid() CHILD PROCESS";
    _exit(127);
  }
  if (chdir("/") != 0)
    gProcessLog.print("==> could not chdir()\n");
}

}  // namespace base