105 lines
2.8 KiB
Python
105 lines
2.8 KiB
Python
# tractor: structured concurrent "actors".
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# Copyright 2018-eternity Tyler Goodlet.
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <https://www.gnu.org/licenses/>.
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'''
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Linux network-namespace actor-bootstrap primitives.
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'''
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from __future__ import annotations
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from collections.abc import Callable
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from pathlib import Path
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import os
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import sys
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_SELF_NETNS: Path = Path('/proc/self/ns/net')
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def enter_netns(
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namespace_fd: int,
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expected_inode: int,
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) -> int:
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'''
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Enter and verify one inherited Linux network namespace.
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The future spawn-bootstrap caller owns and closes `namespace_fd`.
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'''
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if sys.platform != 'linux':
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raise RuntimeError(
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'Network namespace entry is Linux-only!'
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)
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if (
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type(namespace_fd) is not int
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or
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namespace_fd < 0
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):
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raise ValueError(
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'`namespace_fd` must be a non-negative `int`!'
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)
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if (
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type(expected_inode) is not int
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or
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expected_inode <= 0
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):
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raise ValueError(
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'`expected_inode` must be a positive `int`!'
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)
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setns: Callable[[int, int], None]|None = getattr(
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os,
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'setns',
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None,
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)
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clone_newnet: int|None = getattr(
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os,
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'CLONE_NEWNET',
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None,
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)
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if (
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setns is None
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or
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clone_newnet is None
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):
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raise RuntimeError(
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'Python has no Linux network namespace entry support!'
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)
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inherited_inode: int = os.fstat(namespace_fd).st_ino
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if inherited_inode != expected_inode:
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raise ValueError(
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f'Inherited namespace FD inode {inherited_inode} does not '
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f'match expected inode {expected_inode}!'
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)
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try:
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setns(namespace_fd, clone_newnet)
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except OSError as exc:
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raise RuntimeError(
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f'Could not enter network namespace inode '
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f'{expected_inode}!'
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) from exc
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entered_inode: int = _SELF_NETNS.stat().st_ino
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if entered_inode != expected_inode:
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raise RuntimeError(
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f'Entered network namespace inode {entered_inode} does not '
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f'match expected inode {expected_inode}!'
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)
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return entered_inode
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