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 {
operator ()sandbox::__anone8e144360111::DIRCloser23 void operator()(DIR* d) const {
24 DCHECK(d);
25 PCHECK(0 == closedir(d));
26 }
27 };
28
29 typedef scoped_ptr<DIR, DIRCloser> ScopedDIR;
30
OpenDirectory(const char * path)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;
37 }
38
39 } // namespace
40
CountOpenFds(int proc_fd)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
HasOpenDirectory(int proc_fd)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
HasOpenDirectory()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
OpenProc()115 base::ScopedFD ProcUtil::OpenProc() {
116 return OpenDirectory("/proc/");
117 }
118
119 } // namespace sandbox
120