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# please run: mkdir /tmp/img ; docker export $(docker create centos) | tar -C /tmp/img/ -xvf - | |
# before this script | |
import os | |
import ctypes | |
from multiprocessing import Process | |
CLONE_NEWUSER = 0x10000000 | |
CLONE_NEWPID = 0x20000000 | |
CLONE_NEWNET = 0x40000000 | |
CLONE_NEWNS = 0x00020000 | |
MS_PRIVATE = 0x40000 | |
MS_REC = 0x4000 | |
MS_NODEV = 0x4 | |
MS_NOEXEC = 0x8 | |
MS_NOSUID = 0x2 | |
MS_SLAVE = 0x80000 | |
MS_BIND = 4096 | |
libc = ctypes.CDLL(None) | |
get_errno_loc = libc.__errno_location | |
get_errno_loc.restype = ctypes.POINTER(ctypes.c_int) | |
def unshare(flags): | |
rc = libc.unshare(flags) | |
if rc == -1: | |
raise Exception(os.strerror(get_errno_loc()[0])) | |
def mount(special_file, target, fs_type, flags, data): | |
rc = libc.mount(special_file, | |
target, | |
fs_type, | |
flags, | |
data) | |
if rc == -1: | |
raise Exception(os.strerror(get_errno_loc()[0])) | |
def unshare_user(): | |
print("I'm %s" % os.getuid()) | |
unshare(CLONE_NEWUSER) | |
with open('/proc/self/uid_map', 'w') as file_: | |
file_.write('0 1000 1') | |
print("I'm %s" % os.getuid()) | |
def containerize(): | |
unshare_user() | |
unshare(CLONE_NEWNET ^ CLONE_NEWPID ^ CLONE_NEWNS) | |
process = Process(target=cmd) | |
process.start() | |
def cmd(): | |
root = ('/tmp/img') | |
host = os.path.join(root, 'host') | |
if not os.path.exists(host): | |
os.makedirs(host) | |
mount('none', '/', None, MS_REC ^ MS_PRIVATE, None) | |
mount(root, root, None, MS_REC ^ MS_BIND, None) | |
os.chdir(root) | |
pivot_root('.', 'host') | |
mount_proc() | |
os.execve('/bin/bash', ['/bin/bash'], {'PATH': os.getenv('PATH')}) | |
def mount_proc(): | |
if not os.path.exists('/proc'): | |
os.makedirs('/proc') | |
mount('proc', '/proc', 'proc', | |
MS_NODEV ^ MS_NOEXEC ^ MS_NOSUID, None) | |
def pivot_root(new, old): | |
rc = libc.pivot_root(new, old) | |
if rc == -1: | |
raise Exception(os.strerror(get_errno_loc()[0])) | |
containerize() |
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