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