diff options
| -rw-r--r-- | linuxnamespaces/__init__.py | 107 |
1 files changed, 69 insertions, 38 deletions
diff --git a/linuxnamespaces/__init__.py b/linuxnamespaces/__init__.py index 0fb54fb..9c82b22 100644 --- a/linuxnamespaces/__init__.py +++ b/linuxnamespaces/__init__.py @@ -266,6 +266,34 @@ def bind_mount( return mount(srcloc, tgtloc, None, mflags) +_P = typing.ParamSpec("_P") + +class _ExceptionExitCallback: + """Helper class that invokes a callback when a context manager exists with + a failure. + """ + def __init__( + self, + callback: typing.Callable[_P, typing.Any], + *args: _P.args, + **kwargs: _P.kwargs, + ) -> None: + self.callback = callback + self.args = args + self.kwargs = kwargs + + def __enter__(self) -> None: + pass + + def __exit__(self, + exc_type: type[BaseException] | None, + exc_value: BaseException | None, + traceback: typing.Any, + ) -> None: + if exc_type is not None: + self.callback(*self.args, **self.kwargs) + + def populate_dev( origroot: AtLocationLike, newroot: PathConvertible, @@ -280,6 +308,10 @@ def populate_dev( """ origdev = AtLocation(origroot) / "dev" newdev = AtLocation(newroot) / "dev" + bind_devices = "null zero full random urandom tty".split() + if fuse: + bind_devices.append("fuse") + bind_directories = [] mount( "devtmpfs", newdev, @@ -287,32 +319,31 @@ def populate_dev( MountFlags.NOSUID | MountFlags.NOEXEC, "mode=0755", ) - bind_devices = "null zero full random urandom tty".split() - bind_directories = [] - if fuse: - bind_devices.append("fuse") - if pidns: - (newdev / "pts").mkdir() - mount( - "devpts", - newdev / "pts", - "devpts", - MountFlags.NOSUID | MountFlags.NOEXEC, - "gid=5,mode=620,ptmxmode=666", - ) - (newdev / "ptmx").symlink("pts/ptmx") - else: - bind_devices.append("ptmx") - bind_directories.append("pts") - if tun: - (newdev / "net").mkdir() - bind_devices.append("net/tun") - for node in bind_devices: - (newdev / node).mknod(stat.S_IFREG) - bind_mount(origdev / node, newdev / node, True) - for node in bind_directories: - (newdev / node).mkdir() - bind_mount(origdev / node, newdev / node, True) + with _ExceptionExitCallback(umount, newdev, UmountFlags.DETACH): + if pidns: + (newdev / "pts").mkdir() + (newdev / "pts").chmod(0o755) + mount( + "devpts", + newdev / "pts", + "devpts", + MountFlags.NOSUID | MountFlags.NOEXEC, + "gid=5,mode=620,ptmxmode=666", + ) + (newdev / "ptmx").symlink("pts/ptmx") + else: + bind_devices.append("ptmx") + bind_directories.append("pts") + if tun: + (newdev / "net").mkdir() + (newdev / "net").chmod(0o755) + bind_devices.append("net/tun") + for node in bind_devices: + (newdev / node).mknod(stat.S_IFREG) + bind_mount(origdev / node, newdev / node, True) + for node in bind_directories: + (newdev / node).mkdir() + bind_mount(origdev / node, newdev / node, True) def populate_sys( @@ -348,18 +379,18 @@ def populate_sys( ) mount_setattr(modfd, True, MountAttrFlags.RDONLY) mount("sysfs", newsys, "tmpfs", mflags, "mode=0755") - try: - for subdir in ("fs", "fs/cgroup", "module"): - (newsys / subdir).mkdir() - (newsys / subdir).chmod(0o755) - mflags |= MountFlags.REMOUNT | MountFlags.RDONLY - mount("sysfs", newsys, "tmpfs", mflags, "mode=0755") - move_mount(cgfd, newsys / "fs/cgroup") - if module: - move_mount(modfd, newsys / "module") - except: - umount(newsys, UmountFlags.DETACH) - raise + + exitstack.enter_context( + _ExceptionExitCallback(umount, newsys, UmountFlags.DETACH) + ) + for subdir in ("fs", "fs/cgroup", "module"): + (newsys / subdir).mkdir() + (newsys / subdir).chmod(0o755) + mflags |= MountFlags.REMOUNT | MountFlags.RDONLY + mount("sysfs", newsys, "tmpfs", mflags, "mode=0755") + move_mount(cgfd, newsys / "fs/cgroup") + if module: + move_mount(modfd, newsys / "module") def unshare_user_idmap( |