linux/tools/testing/selftests/nsfs/pidns.c
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   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)))
  28struct cr_clone_arg {
  29        char stack[128] __stack_aligned__;
  30        char stack_ptr[0];
  31};
  32
  33static int child(void *args)
  34{
  35        prctl(PR_SET_PDEATHSIG, SIGKILL);
  36        while (1)
  37                sleep(1);
  38        exit(0);
  39}
  40
  41int 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}
  80