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 }