root/tools/testing/selftests/nsfs/pidns.c

DEFINITIONS

1. child
2. main

   1 // SPDX-License-Identifier: GPL-2.0
   2 #define _GNU_SOURCE
   3 #include <sched.h>
   4 #include <unistd.h>
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <signal.h>
   8 #include <errno.h>
   9 #include <sys/types.h>
  10 #include <sys/stat.h>
  11 #include <fcntl.h>
  12 #include <sys/ioctl.h>
  13 #include <sys/prctl.h>
  14 #include <sys/wait.h>
  15 
  16 #define pr_err(fmt, ...) \
  17                 ({ \
  18                         fprintf(stderr, "%s:%d:" fmt ": %m\n", \
  19                                 __func__, __LINE__, ##__VA_ARGS__); \
  20                         1; \
  21                 })
  22 
  23 #define NSIO    0xb7
  24 #define NS_GET_USERNS   _IO(NSIO, 0x1)
  25 #define NS_GET_PARENT   _IO(NSIO, 0x2)
  26 
  27 #define __stack_aligned__       __attribute__((aligned(16)))
  28 struct cr_clone_arg {
  29         char stack[128] __stack_aligned__;
  30         char stack_ptr[0];
  31 };
  32 
  33 static int child(void *args)
  34 {
  35         prctl(PR_SET_PDEATHSIG, SIGKILL);
  36         while (1)
  37                 sleep(1);
  38         exit(0);
  39 }
  40 
  41 int main(int argc, char *argv[])
  42 {
  43         char *ns_strs[] = {"pid", "user"};
  44         char path[] = "/proc/0123456789/ns/pid";
  45         struct cr_clone_arg ca;
  46         struct stat st1, st2;
  47         int ns, pns, i;
  48         pid_t pid;
  49 
  50         pid = clone(child, ca.stack_ptr, CLONE_NEWUSER | CLONE_NEWPID | SIGCHLD, NULL);
  51         if (pid < 0)
  52                 return pr_err("clone");
  53 
  54         for (i = 0; i < 2; i++) {
  55                 snprintf(path, sizeof(path), "/proc/%d/ns/%s", pid, ns_strs[i]);
  56                 ns = open(path, O_RDONLY);
  57                 if (ns < 0)
  58                         return pr_err("Unable to open %s", path);
  59 
  60                 pns = ioctl(ns, NS_GET_PARENT);
  61                 if (pns < 0)
  62                         return pr_err("Unable to get a parent pidns");
  63 
  64                 snprintf(path, sizeof(path), "/proc/self/ns/%s", ns_strs[i]);
  65                 if (stat(path, &st2))
  66                         return pr_err("Unable to stat %s", path);
  67                 if (fstat(pns, &st1))
  68                         return pr_err("Unable to stat the parent pidns");
  69                 if (st1.st_ino != st2.st_ino)
  70                         return pr_err("NS_GET_PARENT returned a wrong namespace");
  71 
  72                 if (ioctl(pns, NS_GET_PARENT) >= 0 || errno != EPERM)
  73                         return pr_err("Don't get EPERM");
  74         }
  75 
  76         kill(pid, SIGKILL);
  77         wait(NULL);
  78         return 0;
  79 }