1/*
2 * Copyright �� 2019 Alexey Dobriyan <adobriyan@gmail.com>
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 */
16/*
17 * Test that setns(CLONE_NEWNET) points to new /proc/net content even
18 * if old one is in dcache.
19 *
20 * FIXME /proc/net/unix is under CONFIG_UNIX which can be disabled.
21 */
22#undef NDEBUG
23#include <assert.h>
24#include <errno.h>
25#include <sched.h>
26#include <signal.h>
27#include <stdio.h>
28#include <stdlib.h>
29#include <string.h>
30#include <unistd.h>
31#include <sys/types.h>
32#include <sys/stat.h>
33#include <fcntl.h>
34#include <sys/socket.h>
35
36static pid_t pid = -1;
37
38static void f(void)
39{
40	if (pid > 0) {
41		kill(pid, SIGTERM);
42	}
43}
44
45int main(void)
46{
47	int fd[2];
48	char _ = 0;
49	int nsfd;
50
51	atexit(f);
52
53	/* Check for priviledges and syscall availability straight away. */
54	if (unshare(CLONE_NEWNET) == -1) {
55		if (errno == ENOSYS || errno == EPERM) {
56			return 4;
57		}
58		return 1;
59	}
60	/* Distinguisher between two otherwise empty net namespaces. */
61	if (socket(AF_UNIX, SOCK_STREAM, 0) == -1) {
62		return 1;
63	}
64
65	if (pipe(fd) == -1) {
66		return 1;
67	}
68
69	pid = fork();
70	if (pid == -1) {
71		return 1;
72	}
73
74	if (pid == 0) {
75		if (unshare(CLONE_NEWNET) == -1) {
76			return 1;
77		}
78
79		if (write(fd[1], &_, 1) != 1) {
80			return 1;
81		}
82
83		pause();
84
85		return 0;
86	}
87
88	if (read(fd[0], &_, 1) != 1) {
89		return 1;
90	}
91
92	{
93		char buf[64];
94		snprintf(buf, sizeof(buf), "/proc/%u/ns/net", pid);
95		nsfd = open(buf, O_RDONLY);
96		if (nsfd == -1) {
97			return 1;
98		}
99	}
100
101	/* Reliably pin dentry into dcache. */
102	(void)open("/proc/net/unix", O_RDONLY);
103
104	if (setns(nsfd, CLONE_NEWNET) == -1) {
105		return 1;
106	}
107
108	kill(pid, SIGTERM);
109	pid = 0;
110
111	{
112		char buf[4096];
113		ssize_t rv;
114		int fd;
115
116		fd = open("/proc/net/unix", O_RDONLY);
117		if (fd == -1) {
118			return 1;
119		}
120
121#define S "Num       RefCount Protocol Flags    Type St Inode Path\n"
122		rv = read(fd, buf, sizeof(buf));
123
124		assert(rv == strlen(S));
125		assert(memcmp(buf, S, strlen(S)) == 0);
126	}
127
128	return 0;
129}
130