selftests/nsfs/pidns.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #define _GNU_SOURCE
0003 #include <sched.h>
0004 #include <unistd.h>
0005 #include <stdio.h>
0006 #include <stdlib.h>
0007 #include <signal.h>
0008 #include <errno.h>
0009 #include <sys/types.h>
0010 #include <sys/stat.h>
0011 #include <fcntl.h>
0012 #include <sys/ioctl.h>
0013 #include <sys/prctl.h>
0014 #include <sys/wait.h>
0015
0016 #define pr_err(fmt, ...) \
0017         ({ \
0018             fprintf(stderr, "%s:%d:" fmt ": %m\n", \
0019                 __func__, __LINE__, ##__VA_ARGS__); \
0020             1; \
0021         })
0022
0023 #define NSIO    0xb7
0024 #define NS_GET_USERNS   _IO(NSIO, 0x1)
0025 #define NS_GET_PARENT   _IO(NSIO, 0x2)
0026
0027 #define __stack_aligned__   __attribute__((aligned(16)))
0028 struct cr_clone_arg {
0029     char stack[128] __stack_aligned__;
0030     char stack_ptr[];
0031 };
0032
0033 static int child(void *args)
0034 {
0035     prctl(PR_SET_PDEATHSIG, SIGKILL);
0036     while (1)
0037         sleep(1);
0038     exit(0);
0039 }
0040
0041 int main(int argc, char *argv[])
0042 {
0043     char *ns_strs[] = {"pid", "user"};
0044     char path[] = "/proc/0123456789/ns/pid";
0045     struct cr_clone_arg ca;
0046     struct stat st1, st2;
0047     int ns, pns, i;
0048     pid_t pid;
0049
0050     pid = clone(child, ca.stack_ptr, CLONE_NEWUSER | CLONE_NEWPID | SIGCHLD, NULL);
0051     if (pid < 0)
0052         return pr_err("clone");
0053
0054     for (i = 0; i < 2; i++) {
0055         snprintf(path, sizeof(path), "/proc/%d/ns/%s", pid, ns_strs[i]);
0056         ns = open(path, O_RDONLY);
0057         if (ns < 0)
0058             return pr_err("Unable to open %s", path);
0059
0060         pns = ioctl(ns, NS_GET_PARENT);
0061         if (pns < 0)
0062             return pr_err("Unable to get a parent pidns");
0063
0064         snprintf(path, sizeof(path), "/proc/self/ns/%s", ns_strs[i]);
0065         if (stat(path, &st2))
0066             return pr_err("Unable to stat %s", path);
0067         if (fstat(pns, &st1))
0068             return pr_err("Unable to stat the parent pidns");
0069         if (st1.st_ino != st2.st_ino)
0070             return pr_err("NS_GET_PARENT returned a wrong namespace");
0071
0072         if (ioctl(pns, NS_GET_PARENT) >= 0 || errno != EPERM)
0073             return pr_err("Don't get EPERM");
0074     }
0075
0076     kill(pid, SIGKILL);
0077     wait(NULL);
0078     return 0;
0079 }