93 lines
2.0 KiB
C
93 lines
2.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#define _GNU_SOURCE
|
|
#include <sched.h>
|
|
#include <unistd.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <signal.h>
|
|
#include <errno.h>
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <fcntl.h>
|
|
#include <sys/ioctl.h>
|
|
#include <sys/prctl.h>
|
|
#include <sys/wait.h>
|
|
|
|
#define NSIO 0xb7
|
|
#define NS_GET_USERNS _IO(NSIO, 0x1)
|
|
|
|
#define pr_err(fmt, ...) \
|
|
({ \
|
|
fprintf(stderr, "%s:%d:" fmt ": %m\n", \
|
|
__func__, __LINE__, ##__VA_ARGS__); \
|
|
1; \
|
|
})
|
|
|
|
int main(int argc, char *argvp[])
|
|
{
|
|
int pfd[2], ns, uns, init_uns;
|
|
struct stat st1, st2;
|
|
char path[128];
|
|
pid_t pid;
|
|
char c;
|
|
|
|
if (pipe(pfd))
|
|
return 1;
|
|
|
|
pid = fork();
|
|
if (pid < 0)
|
|
return pr_err("fork");
|
|
if (pid == 0) {
|
|
prctl(PR_SET_PDEATHSIG, SIGKILL);
|
|
if (unshare(CLONE_NEWUTS | CLONE_NEWUSER))
|
|
return pr_err("unshare");
|
|
close(pfd[0]);
|
|
close(pfd[1]);
|
|
while (1)
|
|
sleep(1);
|
|
return 0;
|
|
}
|
|
close(pfd[1]);
|
|
if (read(pfd[0], &c, 1) != 0)
|
|
return pr_err("Unable to read from pipe");
|
|
close(pfd[0]);
|
|
|
|
snprintf(path, sizeof(path), "/proc/%d/ns/uts", pid);
|
|
ns = open(path, O_RDONLY);
|
|
if (ns < 0)
|
|
return pr_err("Unable to open %s", path);
|
|
|
|
uns = ioctl(ns, NS_GET_USERNS);
|
|
if (uns < 0)
|
|
return pr_err("Unable to get an owning user namespace");
|
|
|
|
if (fstat(uns, &st1))
|
|
return pr_err("fstat");
|
|
|
|
snprintf(path, sizeof(path), "/proc/%d/ns/user", pid);
|
|
if (stat(path, &st2))
|
|
return pr_err("stat");
|
|
|
|
if (st1.st_ino != st2.st_ino)
|
|
return pr_err("NS_GET_USERNS returned a wrong namespace");
|
|
|
|
init_uns = ioctl(uns, NS_GET_USERNS);
|
|
if (uns < 0)
|
|
return pr_err("Unable to get an owning user namespace");
|
|
|
|
if (ioctl(init_uns, NS_GET_USERNS) >= 0 || errno != EPERM)
|
|
return pr_err("Don't get EPERM");
|
|
|
|
if (unshare(CLONE_NEWUSER))
|
|
return pr_err("unshare");
|
|
|
|
if (ioctl(ns, NS_GET_USERNS) >= 0 || errno != EPERM)
|
|
return pr_err("Don't get EPERM");
|
|
if (ioctl(init_uns, NS_GET_USERNS) >= 0 || errno != EPERM)
|
|
return pr_err("Don't get EPERM");
|
|
|
|
kill(pid, SIGKILL);
|
|
wait(NULL);
|
|
return 0;
|
|
}
|