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