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
|
/* Capture output from a subprocess.
Copyright (C) 2017-2022 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
<https://www.gnu.org/licenses/>. */
#include <support/subprocess.h>
#include <support/capture_subprocess.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <support/check.h>
#include <support/xunistd.h>
#include <support/xsocket.h>
#include <support/xspawn.h>
#include <support/support.h>
#include <support/test-driver.h>
static void
transfer (const char *what, struct pollfd *pfd, struct xmemstream *stream)
{
if (pfd->revents != 0)
{
char buf[1024];
ssize_t ret = TEMP_FAILURE_RETRY (read (pfd->fd, buf, sizeof (buf)));
if (ret < 0)
{
support_record_failure ();
printf ("error: reading from subprocess %s: %m\n", what);
pfd->events = 0;
pfd->revents = 0;
}
else if (ret == 0)
{
/* EOF reached. Stop listening. */
pfd->events = 0;
pfd->revents = 0;
}
else
/* Store the data just read. */
TEST_VERIFY (fwrite (buf, ret, 1, stream->out) == 1);
}
}
static void
support_capture_poll (struct support_capture_subprocess *result,
struct support_subprocess *proc)
{
struct pollfd fds[2] =
{
{ .fd = proc->stdout_pipe[0], .events = POLLIN },
{ .fd = proc->stderr_pipe[0], .events = POLLIN },
};
do
{
xpoll (fds, 2, -1);
transfer ("stdout", &fds[0], &result->out);
transfer ("stderr", &fds[1], &result->err);
}
while (fds[0].events != 0 || fds[1].events != 0);
xfclose_memstream (&result->out);
xfclose_memstream (&result->err);
result->status = support_process_wait (proc);
}
struct support_capture_subprocess
support_capture_subprocess (void (*callback) (void *), void *closure)
{
struct support_capture_subprocess result;
xopen_memstream (&result.out);
xopen_memstream (&result.err);
struct support_subprocess proc = support_subprocess (callback, closure);
support_capture_poll (&result, &proc);
return result;
}
struct support_capture_subprocess
support_capture_subprogram (const char *file, char *const argv[])
{
struct support_capture_subprocess result;
xopen_memstream (&result.out);
xopen_memstream (&result.err);
struct support_subprocess proc = support_subprogram (file, argv);
support_capture_poll (&result, &proc);
return result;
}
/* 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
copy_and_spawn_sgid (char *child_id, gid_t gid)
{
char *dirname = xasprintf ("%s/tst-tunables-setuid.%jd",
test_dir, (intmax_t) getpid ());
char *execname = xasprintf ("%s/bin", dirname);
int infd = -1;
int outfd = -1;
int ret = 1, status = 1;
TEST_VERIFY (mkdir (dirname, 0700) == 0);
if (support_record_failure_is_failed ())
goto err;
infd = open ("/proc/self/exe", O_RDONLY);
if (infd < 0)
FAIL_UNSUPPORTED ("unsupported: Cannot read binary from procfs\n");
outfd = open (execname, O_WRONLY | O_CREAT | O_EXCL, 0700);
TEST_VERIFY (outfd >= 0);
if (support_record_failure_is_failed ())
goto err;
char buf[4096];
for (;;)
{
ssize_t rdcount = read (infd, buf, sizeof (buf));
TEST_VERIFY (rdcount >= 0);
if (support_record_failure_is_failed ())
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;
TEST_VERIFY (wrcount > 0);
if (support_record_failure_is_failed ())
goto err;
p += wrcount;
}
}
TEST_VERIFY (fchown (outfd, getuid (), gid) == 0);
if (support_record_failure_is_failed ())
goto err;
TEST_VERIFY (fchmod (outfd, 02750) == 0);
if (support_record_failure_is_failed ())
goto err;
TEST_VERIFY (close (outfd) == 0);
if (support_record_failure_is_failed ())
goto err;
TEST_VERIFY (close (infd) == 0);
if (support_record_failure_is_failed ())
goto err;
/* We have the binary, now spawn the subprocess. Avoid using
support_subprogram because we only want the program exit status, not the
contents. */
ret = 0;
infd = outfd = -1;
char * const args[] = {execname, child_id, NULL};
status = support_subprogram_wait (args[0], args);
err:
if (outfd >= 0)
close (outfd);
if (infd >= 0)
close (infd);
if (execname != NULL)
{
unlink (execname);
free (execname);
}
if (dirname != NULL)
{
rmdir (dirname);
free (dirname);
}
if (ret != 0)
FAIL_EXIT1("Failed to make sgid executable for test\n");
return status;
}
int
support_capture_subprogram_self_sgid (char *child_id)
{
gid_t target = 0;
const int count = 64;
gid_t groups[count];
/* Get a GID which is not our current GID, but is present in the
supplementary group list. */
int ret = getgroups (count, groups);
if (ret < 0)
FAIL_UNSUPPORTED("Could not get group list for user %jd\n",
(intmax_t) getuid ());
gid_t current = getgid ();
for (int i = 0; i < ret; ++i)
{
if (groups[i] != current)
{
target = groups[i];
break;
}
}
if (target == 0)
FAIL_UNSUPPORTED("Could not find a suitable GID for user %jd\n",
(intmax_t) getuid ());
return copy_and_spawn_sgid (child_id, target);
}
void
support_capture_subprocess_free (struct support_capture_subprocess *p)
{
free (p->out.buffer);
free (p->err.buffer);
}
|
