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
36 static pid_t pid = -1;
37
38 static void f(void)
39 {
40 if (pid > 0) {
41 kill(pid, SIGTERM);
42 }
43 }
44
45 int 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 }