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
|
/* Copyright (C) 2012-2013 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
/* Test that secure_getenv works by invoking the test as a SGID
program with a group ID from the supplementary group list. This
test can fail spuriously if the user is not a member of a suitable
supplementary group. */
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
static char MAGIC_ARGUMENT[] = "run-actual-test";
#define MAGIC_STATUS 19
static const char *test_dir;
/* Return a GID which is not our current GID, but is present in the
supplementary group list. */
static gid_t
choose_gid (void)
{
const int count = 64;
gid_t groups[count];
int ret = getgroups (count, groups);
if (ret < 0)
{
printf ("getgroups: %m\n");
exit (1);
}
gid_t current = getgid ();
for (int i = 0; i < ret; ++i)
{
if (groups[i] != current)
return groups[i];
}
return 0;
}
/* Copies the executable into a restricted directory, so that we can
safely make it SGID with the TARGET group ID. Then runs the
executable. */
static int
run_executable_sgid (gid_t target)
{
char *dirname = 0;
char *execname = 0;
int infd = -1;
int outfd = -1;
int ret = -1;
if (asprintf (&dirname, "%s/secure-getenv.%jd",
test_dir, (intmax_t) getpid ()) < 0)
{
printf ("asprintf: %m\n");
goto err;
}
if (mkdir (dirname, 0700) < 0)
{
printf ("mkdir: %m\n");
goto err;
}
if (asprintf (&execname, "%s/bin", dirname) < 0)
{
printf ("asprintf: %m\n");
goto err;
}
infd = open ("/proc/self/exe", O_RDONLY);
if (infd < 0)
{
printf ("open (/proc/self/exe): %m\n");
goto err;
}
outfd = open (execname, O_WRONLY | O_CREAT | O_EXCL, 0700);
if (outfd < 0)
{
printf ("open (%s): %m\n", execname);
goto err;
}
char buf[4096];
for (;;)
{
ssize_t rdcount = read (infd, buf, sizeof (buf));
if (rdcount < 0)
{
printf ("read: %m\n");
goto err;
}
if (rdcount == 0)
break;
char *p = buf;
char *end = buf + rdcount;
while (p != end)
{
ssize_t wrcount = write (outfd, buf, end - p);
if (wrcount == 0)
errno = ENOSPC;
if (wrcount <= 0)
{
printf ("write: %m\n");
goto err;
}
p += wrcount;
}
}
if (fchown (outfd, getuid (), target) < 0)
{
printf ("fchown (%s): %m\n", execname);
goto err;
}
if (fchmod (outfd, 02750) < 0)
{
printf ("fchmod (%s): %m\n", execname);
goto err;
}
if (close (outfd) < 0)
{
printf ("close (outfd): %m\n");
goto err;
}
if (close (infd) < 0)
{
printf ("close (infd): %m\n");
goto err;
}
int kid = fork ();
if (kid < 0)
{
printf ("fork: %m\n");
goto err;
}
if (kid == 0)
{
/* Child process. */
char *args[] = { execname, MAGIC_ARGUMENT, NULL };
execve (execname, args, environ);
printf ("execve (%s): %m\n", execname);
_exit (1);
}
int status;
if (waitpid (kid, &status, 0) < 0)
{
printf ("waitpid: %m\n");
goto err;
}
if (!WIFEXITED (status) || WEXITSTATUS (status) != MAGIC_STATUS)
{
printf ("Unexpected exit status %d from child process\n",
status);
goto err;
}
ret = 0;
err:
if (outfd >= 0)
close (outfd);
if (infd >= 0)
close (infd);
if (execname)
{
unlink (execname);
free (execname);
}
if (dirname)
{
rmdir (dirname);
free (dirname);
}
return ret;
}
static int
do_test (void)
{
if (getenv ("PATH") == NULL)
{
printf ("PATH not set\n");
exit (1);
}
if (secure_getenv ("PATH") == NULL)
{
printf ("PATH not set according to secure_getenv\n");
exit (1);
}
if (strcmp (getenv ("PATH"), secure_getenv ("PATH")) != 0)
{
printf ("PATH mismatch (%s, %s)\n",
getenv ("PATH"), secure_getenv ("PATH"));
exit (1);
}
gid_t target = choose_gid ();
if (target == 0)
{
fprintf (stderr,
"Could not find a suitable GID for user %jd, skipping test\n",
(intmax_t) getuid ());
exit (0);
}
return run_executable_sgid (target);
}
static void
alternative_main (int argc, char **argv)
{
if (argc == 2 && strcmp (argv[1], MAGIC_ARGUMENT) == 0)
{
if (getgid () == getegid ())
{
/* This can happen if the file system is mounted nosuid. */
fprintf (stderr, "SGID failed: GID and EGID match (%jd)\n",
(intmax_t) getgid ());
exit (MAGIC_STATUS);
}
if (getenv ("PATH") == NULL)
{
printf ("PATH variable not present\n");
exit (3);
}
if (secure_getenv ("PATH") != NULL)
{
printf ("PATH variable not filtered out\n");
exit (4);
}
exit (MAGIC_STATUS);
}
}
#define PREPARE(argc, argv) alternative_main(argc, argv)
#define TEST_FUNCTION do_test ()
#include "../test-skeleton.c"
|
