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}