d5b321b557
New privileged helper at /usr/local/libexec/left4me/left4me-overlay (Python, system /usr/bin/python3, stdlib only) takes only the instance name, parses instance.env for L4D2_LOWERDIRS, validates each lowerdir against an allowlist (installation/, overlays/, global_overlay_cache/, workshop_cache/), refuses upperdirs tainted with user.fuseoverlayfs.* xattrs from the prior fuse era, and execs `nsenter --mount=/proc/1/ns/mnt -- mount -t overlay ...` so the resulting mount lives in the host namespace. Mirrors the existing left4me-systemctl / left4me-journalctl pattern; sudoers entry is verb-constrained. KernelOverlayFSMounter implements the existing OverlayMounter ABC, deriving the instance name from the merged path. No call sites use it yet — that's the next commit. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
53 lines
1.7 KiB
Python
53 lines
1.7 KiB
Python
from pathlib import Path
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from typing import Callable
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from l4d2host.fs.base import OverlayMounter
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from l4d2host.process import run_command
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HELPER_PATH = "/usr/local/libexec/left4me/left4me-overlay"
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class KernelOverlayFSMounter(OverlayMounter):
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# Delegates the actual mount/umount syscalls to the privileged
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# left4me-overlay helper. The helper takes only the instance name and
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# rederives lowerdirs/upper/work/merged from disk; the OverlayMounter
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# ABC accepts those args for compatibility, so we extract the name
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# from the merged path's parent directory.
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def mount(
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self,
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*,
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lowerdirs: str,
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upperdir: Path,
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workdir: Path,
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merged: Path,
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on_stdout: Callable[[str], None] | None = None,
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on_stderr: Callable[[str], None] | None = None,
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passthrough: bool = False,
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should_cancel: Callable[[], bool] | None = None,
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) -> None:
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del lowerdirs, upperdir, workdir
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run_command(
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["sudo", "-n", HELPER_PATH, "mount", merged.parent.name],
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on_stdout=on_stdout,
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on_stderr=on_stderr,
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passthrough=passthrough,
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should_cancel=should_cancel,
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)
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def unmount(
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self,
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*,
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merged: Path,
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on_stdout: Callable[[str], None] | None = None,
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on_stderr: Callable[[str], None] | None = None,
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passthrough: bool = False,
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should_cancel: Callable[[], bool] | None = None,
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) -> None:
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run_command(
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["sudo", "-n", HELPER_PATH, "umount", merged.parent.name],
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on_stdout=on_stdout,
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on_stderr=on_stderr,
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passthrough=passthrough,
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should_cancel=should_cancel,
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)
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