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_NEWIPC) points to new /proc/sysvipc content even
18 * if old one is in dcache.
19 */
20#undef NDEBUG
21#include <assert.h>
22#include <errno.h>
23#include <stdio.h>
24#include <sched.h>
25#include <signal.h>
26#include <stdlib.h>
27#include <string.h>
28#include <unistd.h>
29#include <sys/types.h>
30#include <sys/stat.h>
31#include <fcntl.h>
32#include <sys/ipc.h>
33#include <sys/shm.h>
34
35static pid_t pid = -1;
36
37static void f(void)
38{
39	if (pid > 0) {
40		kill(pid, SIGTERM);
41	}
42}
43
44int main(void)
45{
46	int fd[2];
47	char _ = 0;
48	int nsfd;
49
50	atexit(f);
51
52	/* Check for priviledges and syscall availability straight away. */
53	if (unshare(CLONE_NEWIPC) == -1) {
54		if (errno == ENOSYS || errno == EPERM) {
55			return 4;
56		}
57		return 1;
58	}
59	/* Distinguisher between two otherwise empty IPC namespaces. */
60	if (shmget(IPC_PRIVATE, 1, IPC_CREAT) == -1) {
61		return 1;
62	}
63
64	if (pipe(fd) == -1) {
65		return 1;
66	}
67
68	pid = fork();
69	if (pid == -1) {
70		return 1;
71	}
72
73	if (pid == 0) {
74		if (unshare(CLONE_NEWIPC) == -1) {
75			return 1;
76		}
77
78		if (write(fd[1], &_, 1) != 1) {
79			return 1;
80		}
81
82		pause();
83
84		return 0;
85	}
86
87	if (read(fd[0], &_, 1) != 1) {
88		return 1;
89	}
90
91	{
92		char buf[64];
93		snprintf(buf, sizeof(buf), "/proc/%u/ns/ipc", pid);
94		nsfd = open(buf, O_RDONLY);
95		if (nsfd == -1) {
96			return 1;
97		}
98	}
99
100	/* Reliably pin dentry into dcache. */
101	(void)open("/proc/sysvipc/shm", O_RDONLY);
102
103	if (setns(nsfd, CLONE_NEWIPC) == -1) {
104		return 1;
105	}
106
107	kill(pid, SIGTERM);
108	pid = 0;
109
110	{
111		char buf[4096];
112		ssize_t rv;
113		int fd;
114
115		fd = open("/proc/sysvipc/shm", O_RDONLY);
116		if (fd == -1) {
117			return 1;
118		}
119
120#define S32 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n"
121#define S64 "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n"
122		rv = read(fd, buf, sizeof(buf));
123		if (rv == strlen(S32)) {
124			assert(memcmp(buf, S32, strlen(S32)) == 0);
125		} else if (rv == strlen(S64)) {
126			assert(memcmp(buf, S64, strlen(S64)) == 0);
127		} else {
128			assert(0);
129		}
130	}
131
132	return 0;
133}
134