# -*- coding: utf-8 eval: (blacken-mode 1) -*- # SPDX-License-Identifier: GPL-2.0-or-later # # June 10 2022, Christian Hopps # # Copyright (c) 2022, LabN Consulting, L.L.C. # """A module that gives access to linux unshare system call.""" import ctypes # pylint: disable=C0415 import ctypes.util # pylint: disable=C0415 import errno import functools import os libc = None def raise_oserror(enum): s = errno.errorcode[enum] if enum in errno.errorcode else str(enum) error = OSError(s) error.errno = enum error.strerror = s raise error def _load_libc(): global libc # pylint: disable=W0601,W0603 if libc: return lcpath = ctypes.util.find_library("c") libc = ctypes.CDLL(lcpath, use_errno=True) def pause(): if not libc: _load_libc() libc.pause() MS_RDONLY = 1 MS_NOSUID = 1 << 1 MS_NODEV = 1 << 2 MS_NOEXEC = 1 << 3 MS_SYNCHRONOUS = 1 << 4 MS_REMOUNT = 1 << 5 MS_MANDLOCK = 1 << 6 MS_DIRSYNC = 1 << 7 MS_NOSYMFOLLOW = 1 << 8 MS_NOATIME = 1 << 10 MS_NODIRATIME = 1 << 11 MS_BIND = 1 << 12 MS_MOVE = 1 << 13 MS_REC = 1 << 14 MS_SILENT = 1 << 15 MS_POSIXACL = 1 << 16 MS_UNBINDABLE = 1 << 17 MS_PRIVATE = 1 << 18 MS_SLAVE = 1 << 19 MS_SHARED = 1 << 20 MS_RELATIME = 1 << 21 MS_KERNMOUNT = 1 << 22 MS_I_VERSION = 1 << 23 MS_STRICTATIME = 1 << 24 MS_LAZYTIME = 1 << 25 def mount(source, target, fs, flags=0, options=""): if not libc: _load_libc() libc.mount.argtypes = ( ctypes.c_char_p, ctypes.c_char_p, ctypes.c_char_p, ctypes.c_ulong, ctypes.c_char_p, ) fsenc = fs.encode() if fs else None optenc = options.encode() if options else None ret = libc.mount(source.encode(), target.encode(), fsenc, flags, optenc) if ret < 0: err = ctypes.get_errno() raise OSError( err, f"Error mounting {source} ({fs}) on {target}" f" with options '{options}': {os.strerror(err)}", ) # unmout options MNT_FORCE = 0x1 MNT_DETACH = 0x2 MNT_EXPIRE = 0x4 UMOUNT_NOFOLLOW = 0x8 def umount(target, options): if not libc: _load_libc() libc.umount.argtypes = (ctypes.c_char_p, ctypes.c_uint) ret = libc.umount(target.encode(), int(options)) if ret < 0: err = ctypes.get_errno() raise OSError( err, f"Error umounting {target} with options '{options}': {os.strerror(err)}", ) def pidfd_open(pid, flags=0): if hasattr(os, "pidfd_open") and os.pidfd_open is not pidfd_open: return os.pidfd_open(pid, flags) # pylint: disable=no-member if not libc: _load_libc() try: pfof = libc.pidfd_open except AttributeError: __NR_pidfd_open = 434 _pidfd_open = libc.syscall _pidfd_open.restype = ctypes.c_int _pidfd_open.argtypes = ctypes.c_long, ctypes.c_uint, ctypes.c_uint pfof = functools.partial(_pidfd_open, __NR_pidfd_open) fd = pfof(int(pid), int(flags)) if fd == -1: raise_oserror(ctypes.get_errno()) return fd if not hasattr(os, "pidfd_open"): os.pidfd_open = pidfd_open def setns(fd, nstype): # noqa: D402 """See setns(2) manpage.""" if not libc: _load_libc() if libc.setns(int(fd), int(nstype)) == -1: raise_oserror(ctypes.get_errno()) def unshare(flags): # noqa: D402 """See unshare(2) manpage.""" if not libc: _load_libc() if libc.unshare(int(flags)) == -1: raise_oserror(ctypes.get_errno()) CLONE_NEWTIME = 0x00000080 CLONE_VM = 0x00000100 CLONE_FS = 0x00000200 CLONE_FILES = 0x00000400 CLONE_SIGHAND = 0x00000800 CLONE_PIDFD = 0x00001000 CLONE_PTRACE = 0x00002000 CLONE_VFORK = 0x00004000 CLONE_PARENT = 0x00008000 CLONE_THREAD = 0x00010000 CLONE_NEWNS = 0x00020000 CLONE_SYSVSEM = 0x00040000 CLONE_SETTLS = 0x00080000 CLONE_PARENT_SETTID = 0x00100000 CLONE_CHILD_CLEARTID = 0x00200000 CLONE_DETACHED = 0x00400000 CLONE_UNTRACED = 0x00800000 CLONE_CHILD_SETTID = 0x01000000 CLONE_NEWCGROUP = 0x02000000 CLONE_NEWUTS = 0x04000000 CLONE_NEWIPC = 0x08000000 CLONE_NEWUSER = 0x10000000 CLONE_NEWPID = 0x20000000 CLONE_NEWNET = 0x40000000 CLONE_IO = 0x80000000 clone_flag_names = { CLONE_NEWTIME: "CLONE_NEWTIME", CLONE_VM: "CLONE_VM", CLONE_FS: "CLONE_FS", CLONE_FILES: "CLONE_FILES", CLONE_SIGHAND: "CLONE_SIGHAND", CLONE_PIDFD: "CLONE_PIDFD", CLONE_PTRACE: "CLONE_PTRACE", CLONE_VFORK: "CLONE_VFORK", CLONE_PARENT: "CLONE_PARENT", CLONE_THREAD: "CLONE_THREAD", CLONE_NEWNS: "CLONE_NEWNS", CLONE_SYSVSEM: "CLONE_SYSVSEM", CLONE_SETTLS: "CLONE_SETTLS", CLONE_PARENT_SETTID: "CLONE_PARENT_SETTID", CLONE_CHILD_CLEARTID: "CLONE_CHILD_CLEARTID", CLONE_DETACHED: "CLONE_DETACHED", CLONE_UNTRACED: "CLONE_UNTRACED", CLONE_CHILD_SETTID: "CLONE_CHILD_SETTID", CLONE_NEWCGROUP: "CLONE_NEWCGROUP", CLONE_NEWUTS: "CLONE_NEWUTS", CLONE_NEWIPC: "CLONE_NEWIPC", CLONE_NEWUSER: "CLONE_NEWUSER", CLONE_NEWPID: "CLONE_NEWPID", CLONE_NEWNET: "CLONE_NEWNET", CLONE_IO: "CLONE_IO", } def clone_flag_string(flags): ns = [v for k, v in clone_flag_names.items() if k & flags] if ns: return "|".join(ns) return "None" namespace_files = { CLONE_NEWUSER: "ns/user", CLONE_NEWCGROUP: "ns/cgroup", CLONE_NEWIPC: "ns/ipc", CLONE_NEWUTS: "ns/uts", CLONE_NEWNET: "ns/net", CLONE_NEWPID: "ns/pid_for_children", CLONE_NEWNS: "ns/mnt", CLONE_NEWTIME: "ns/time_for_children", } PR_SET_PDEATHSIG = 1 PR_GET_PDEATHSIG = 2 PR_SET_NAME = 15 PR_GET_NAME = 16 def set_process_name(name): if not libc: _load_libc() # Why does uncommenting this cause failure? # libc.prctl.argtypes = ( # ctypes.c_int, # ctypes.c_ulong, # ctypes.c_ulong, # ctypes.c_ulong, # ctypes.c_ulong, # ) s = ctypes.create_string_buffer(bytes(name, encoding="ascii")) sr = ctypes.byref(s) libc.prctl(PR_SET_NAME, sr, 0, 0, 0) def set_parent_death_signal(signum): if not libc: _load_libc() # Why does uncommenting this cause failure? libc.prctl.argtypes = ( ctypes.c_int, ctypes.c_ulong, ctypes.c_ulong, ctypes.c_ulong, ctypes.c_ulong, ) libc.prctl(PR_SET_PDEATHSIG, signum, 0, 0, 0)