1 // SPDX-License-Identifier: GPL-2.0
2 #define _GNU_SOURCE
3 #include <sched.h>
4 #include <unistd.h>
5 #include <stdio.h>
6 #include <errno.h>
7 #include <string.h>
8 #include <stdlib.h>
9 #include <stdint.h>
10 #include <sys/types.h>
11 #include <sys/socket.h>
12 
13 #ifndef SO_NETNS_COOKIE
14 #define SO_NETNS_COOKIE 71
15 #endif
16 
17 #define pr_err(fmt, ...) \
18 	({ \
19 		fprintf(stderr, "%s:%d:" fmt ": %m\n", \
20 			__func__, __LINE__, ##__VA_ARGS__); \
21 		1; \
22 	})
23 
main(int argc,char * argvp[])24 int main(int argc, char *argvp[])
25 {
26 	uint64_t cookie1, cookie2;
27 	socklen_t vallen;
28 	int sock1, sock2;
29 
30 	sock1 = socket(AF_INET, SOCK_STREAM, 0);
31 	if (sock1 < 0)
32 		return pr_err("Unable to create TCP socket");
33 
34 	vallen = sizeof(cookie1);
35 	if (getsockopt(sock1, SOL_SOCKET, SO_NETNS_COOKIE, &cookie1, &vallen) != 0)
36 		return pr_err("getsockopt(SOL_SOCKET, SO_NETNS_COOKIE)");
37 
38 	if (!cookie1)
39 		return pr_err("SO_NETNS_COOKIE returned zero cookie");
40 
41 	if (unshare(CLONE_NEWNET))
42 		return pr_err("unshare");
43 
44 	sock2 = socket(AF_INET, SOCK_STREAM, 0);
45 	if (sock2 < 0)
46 		return pr_err("Unable to create TCP socket");
47 
48 	vallen = sizeof(cookie2);
49 	if (getsockopt(sock2, SOL_SOCKET, SO_NETNS_COOKIE, &cookie2, &vallen) != 0)
50 		return pr_err("getsockopt(SOL_SOCKET, SO_NETNS_COOKIE)");
51 
52 	if (!cookie2)
53 		return pr_err("SO_NETNS_COOKIE returned zero cookie");
54 
55 	if (cookie1 == cookie2)
56 		return pr_err("SO_NETNS_COOKIE returned identical cookies for distinct ns");
57 
58 	close(sock1);
59 	close(sock2);
60 	return 0;
61 }
62