enroll/tests/test_manifest_safety.py
Miguel Jacq d2a46394fe
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More hardening
2026-07-03 12:24:08 +10:00

366 lines
13 KiB
Python

from __future__ import annotations
import os
from pathlib import Path
import pytest
from enroll.manifest_safety import (
ArtifactSafetyError,
ManifestOutputError,
copy_safe_artifact_file,
freeze_directory_bundle,
iter_safe_artifact_files,
prepare_manifest_output_dir,
safe_artifact_file,
validate_site_fqdn,
)
def test_validate_site_fqdn_accepts_and_normalises_simple_values():
assert validate_site_fqdn(None) is None
assert validate_site_fqdn(" ") is None
assert validate_site_fqdn("host_1.example") == "host_1.example"
@pytest.mark.parametrize(
"value", ["../host", "host/name", "host\\name", "host\nname", "-bad", ".", ".."]
)
def test_validate_site_fqdn_rejects_path_or_inventory_injection(value: str):
with pytest.raises(ManifestOutputError):
validate_site_fqdn(value)
def test_prepare_manifest_output_dir_allows_existing_clean_tree_in_site_mode(
tmp_path: Path,
):
out = tmp_path / "site"
out.mkdir()
# Match Enroll's root-run output safety expectations regardless of the
# ambient CI/container umask.
out.chmod(0o700)
(out / ".git").mkdir()
(out / ".git").chmod(0o700)
(out / ".git" / "ignored-link").symlink_to(tmp_path, target_is_directory=True)
assert prepare_manifest_output_dir(out, allow_existing=True) == out
def test_prepare_manifest_output_dir_rejects_existing_tree_symlink(tmp_path: Path):
out = tmp_path / "site"
out.mkdir()
# Keep the root-safety check from masking the specific symlink assertion on
# Forgejo/Docker hosts that run with umask 0002.
out.chmod(0o700)
(out / "bad-link").symlink_to(tmp_path, target_is_directory=True)
with pytest.raises(ManifestOutputError, match="contains a symlink"):
prepare_manifest_output_dir(out, allow_existing=True)
def test_safe_artifact_file_accepts_regular_file_and_copy(tmp_path: Path):
bundle = tmp_path / "bundle"
artifact = bundle / "artifacts" / "role" / "etc" / "app.conf"
artifact.parent.mkdir(parents=True)
artifact.write_text("managed=true\n", encoding="utf-8")
assert safe_artifact_file(bundle, "role", "etc/app.conf") == artifact
dst = tmp_path / "copy.conf"
copy_safe_artifact_file(artifact, dst)
assert dst.read_text(encoding="utf-8") == "managed=true\n"
def test_safe_artifact_file_rejects_unsafe_role_and_src(tmp_path: Path):
bundle = tmp_path / "bundle"
with pytest.raises(ArtifactSafetyError, match="must be relative"):
safe_artifact_file(bundle, "/role", "file")
with pytest.raises(ArtifactSafetyError, match="unsafe path component"):
safe_artifact_file(bundle, "role", "../file")
with pytest.raises(ArtifactSafetyError, match="NUL"):
safe_artifact_file(bundle, "role", "bad\x00file")
def test_safe_artifact_file_rejects_artifacts_symlink(tmp_path: Path):
bundle = tmp_path / "bundle"
bundle.mkdir()
(bundle / "artifacts").symlink_to(tmp_path, target_is_directory=True)
with pytest.raises(ArtifactSafetyError, match="artifacts directory is a symlink"):
safe_artifact_file(bundle, "role", "file")
def test_safe_artifact_file_rejects_bad_artifact_kinds(tmp_path: Path):
bundle = tmp_path / "bundle"
role_dir = bundle / "artifacts" / "role"
role_dir.mkdir(parents=True)
target = role_dir / "target"
target.write_text("x", encoding="utf-8")
(role_dir / "link").symlink_to(target)
with pytest.raises(ArtifactSafetyError, match="symlink"):
safe_artifact_file(bundle, "role", "link")
(role_dir / "dir-artifact").mkdir()
with pytest.raises(ArtifactSafetyError, match="not a regular file"):
safe_artifact_file(bundle, "role", "dir-artifact")
hardlink = role_dir / "hardlink"
os.link(target, hardlink)
with pytest.raises(ArtifactSafetyError, match="hardlinked"):
safe_artifact_file(bundle, "role", "target")
def test_iter_safe_artifact_files_handles_missing_and_bad_role_dirs(tmp_path: Path):
bundle = tmp_path / "bundle"
assert list(iter_safe_artifact_files(bundle, "missing")) == []
role_file = bundle / "artifacts" / "role"
role_file.parent.mkdir(parents=True)
role_file.write_text("not a dir", encoding="utf-8")
with pytest.raises(ArtifactSafetyError, match="not a directory"):
list(iter_safe_artifact_files(bundle, "role"))
def test_iter_safe_artifact_files_rejects_symlink_subdir(tmp_path: Path):
bundle = tmp_path / "bundle"
role_dir = bundle / "artifacts" / "role"
role_dir.mkdir(parents=True)
real = tmp_path / "real"
real.mkdir()
(role_dir / "linkdir").symlink_to(real, target_is_directory=True)
with pytest.raises(ArtifactSafetyError, match="directory is a symlink"):
list(iter_safe_artifact_files(bundle, "role"))
def _write_bundle(tmp_path: Path) -> Path:
bundle = tmp_path / "bundle"
art = bundle / "artifacts" / "app" / "etc" / "app"
art.mkdir(parents=True)
(art / "app.conf").write_text("original-content\n", encoding="utf-8")
(bundle / "state.json").write_text("{}\n", encoding="utf-8")
return bundle
def test_freeze_directory_bundle_copies_content(tmp_path: Path):
bundle = _write_bundle(tmp_path)
frozen_dir, td = freeze_directory_bundle(bundle)
try:
frozen = Path(frozen_dir)
assert frozen != bundle
assert (frozen / "state.json").read_text(encoding="utf-8") == "{}\n"
assert (frozen / "artifacts" / "app" / "etc" / "app" / "app.conf").read_text(
encoding="utf-8"
) == "original-content\n"
# The frozen copy is a private directory.
mode = (Path(frozen_dir)).stat().st_mode & 0o777
assert mode == 0o700
finally:
td.cleanup()
def test_freeze_directory_bundle_is_immutable_after_source_swap(tmp_path: Path):
"""The core TOCTOU regression: mutating the source after freezing must not
change what a consumer reads, and must not let a post-freeze symlink redirect
reads to a secret."""
bundle = _write_bundle(tmp_path)
art_file = bundle / "artifacts" / "app" / "etc" / "app" / "app.conf"
frozen_dir, td = freeze_directory_bundle(bundle)
try:
secret = tmp_path / "secret"
secret.write_text("TOP-SECRET\n", encoding="utf-8")
# Attacker swaps the validated regular file for a symlink to a secret and
# also rewrites another path's content. None of this may affect the frozen
# copy the consumer actually uses.
art_file.unlink()
art_file.symlink_to(secret)
frozen_file = (
Path(frozen_dir) / "artifacts" / "app" / "etc" / "app" / "app.conf"
)
assert not frozen_file.is_symlink()
assert frozen_file.read_text(encoding="utf-8") == "original-content\n"
assert "TOP-SECRET" not in frozen_file.read_text(encoding="utf-8")
finally:
td.cleanup()
def test_freeze_directory_bundle_rejects_symlinked_file(tmp_path: Path):
bundle = _write_bundle(tmp_path)
secret = tmp_path / "secret"
secret.write_text("secret\n", encoding="utf-8")
# A bundle that already contains a symlinked artifact at freeze time is
# rejected outright rather than silently following it.
link = bundle / "artifacts" / "app" / "etc" / "app" / "link.conf"
link.symlink_to(secret)
with pytest.raises(ArtifactSafetyError, match="symlink"):
freeze_directory_bundle(bundle)
def test_freeze_directory_bundle_rejects_symlinked_subdir(tmp_path: Path):
bundle = _write_bundle(tmp_path)
outside = tmp_path / "outside"
outside.mkdir()
(outside / "x.conf").write_text("x\n", encoding="utf-8")
(bundle / "artifacts" / "app" / "linkdir").symlink_to(
outside, target_is_directory=True
)
with pytest.raises(ArtifactSafetyError, match="symlink"):
freeze_directory_bundle(bundle)
def test_freeze_directory_bundle_rejects_hardlinked_file(tmp_path: Path):
bundle = _write_bundle(tmp_path)
secret = tmp_path / "secret"
secret.write_text("secret\n", encoding="utf-8")
hard = bundle / "artifacts" / "app" / "etc" / "app" / "hard.conf"
os.link(secret, hard)
with pytest.raises(ArtifactSafetyError, match="hardlink"):
freeze_directory_bundle(bundle)
def test_freeze_directory_bundle_fails_loudly_on_unreadable_subdir(tmp_path: Path):
"""An unreadable subtree must abort the freeze, not silently truncate it.
Regression test: os.walk() defaults to swallowing directory-listing errors,
which previously produced a partial frozen bundle with no error. The freeze
now passes onerror= so a PermissionError aborts with ArtifactSafetyError.
"""
if os.geteuid() == 0:
pytest.skip("root can read 0000 directories; cannot simulate the case")
bundle = _write_bundle(tmp_path)
locked = bundle / "artifacts" / "app" / "etc" / "app"
assert locked.is_dir()
os.chmod(locked, 0o000)
try:
with pytest.raises(ArtifactSafetyError, match="could not be fully read"):
freeze_directory_bundle(bundle)
finally:
# Restore perms so tmp_path cleanup can remove the tree.
os.chmod(locked, 0o755)
class _FakeStat:
"""Minimal stat_result stand-in so interior-dir tests can control uid/mode
independently of the CI runner's real uid and umask."""
def __init__(self, real_st, *, uid: int, mode_bits: int | None = None):
self.st_mode = real_st.st_mode if mode_bits is None else mode_bits
self.st_uid = uid
self.st_gid = getattr(real_st, "st_gid", 0)
def _patch_lstat(monkeypatch, ms, *, uid_for, mode_for=None):
"""Patch Path.lstat so directories report a chosen uid / mode.
``uid_for(path) -> int`` and optional ``mode_for(path) -> int|None`` let a
test simulate a non-root-owned or writable interior directory without
needing real root privileges.
"""
real_lstat = ms.Path.lstat
def fake_lstat(self):
st = real_lstat(self)
mode = None
if mode_for is not None:
mode = mode_for(self)
return _FakeStat(st, uid=uid_for(self), mode_bits=mode)
monkeypatch.setattr(ms.Path, "lstat", fake_lstat)
def test_existing_site_tree_rejects_world_writable_interior_dir_as_root(
tmp_path: Path, monkeypatch
):
"""Root-run site merge must refuse an attacker-writable interior directory.
A symlink-only scan is insufficient: an unprivileged owner of a
group/other-writable directory inside the output tree can plant files or a
symlink after the scan and race the merge. Under root, such a directory is
rejected up front.
"""
import enroll.manifest_safety as ms
out = tmp_path / "site"
out.mkdir()
(out / "roles").mkdir()
interior = (out / "roles").resolve()
monkeypatch.setattr(ms, "_effective_uid", lambda: 0)
# Everything root-owned; the interior "roles" dir is world-writable.
_patch_lstat(
monkeypatch,
ms,
uid_for=lambda p: 0,
mode_for=lambda p: (0o40777 if Path(p).resolve() == interior else 0o40700),
)
with pytest.raises(ManifestOutputError, match="group/other-writable"):
ms._assert_no_output_symlinks(out)
def test_existing_site_tree_rejects_non_root_owned_interior_dir_as_root(
tmp_path: Path, monkeypatch
):
"""Root-run site merge must refuse an interior directory owned by another
(unprivileged) user, even if it is not itself writable by group/other."""
import enroll.manifest_safety as ms
out = tmp_path / "site"
out.mkdir()
(out / "roles").mkdir()
interior = (out / "roles").resolve()
monkeypatch.setattr(ms, "_effective_uid", lambda: 0)
_patch_lstat(
monkeypatch,
ms,
uid_for=lambda p: (1000 if Path(p).resolve() == interior else 0),
mode_for=lambda p: 0o40755,
)
with pytest.raises(ManifestOutputError, match="not owned by root"):
ms._assert_no_output_symlinks(out)
def test_existing_site_tree_allows_clean_root_owned_interior_as_root(
tmp_path: Path, monkeypatch
):
"""A clean, root-owned, non-writable interior tree passes the merge check."""
import enroll.manifest_safety as ms
out = tmp_path / "site"
out.mkdir()
(out / "roles").mkdir()
(out / "roles" / "svc").mkdir()
monkeypatch.setattr(ms, "_effective_uid", lambda: 0)
_patch_lstat(
monkeypatch,
ms,
uid_for=lambda p: 0,
mode_for=lambda p: 0o40755,
)
# No exception: root-owned, not group/other-writable.
ms._assert_no_output_symlinks(out)
def test_existing_site_tree_interior_check_is_noop_for_non_root(
tmp_path: Path, monkeypatch
):
"""Non-root runs keep the original symlink-only semantics (no ownership or
writability enforcement), so ordinary user workflows are unaffected."""
import enroll.manifest_safety as ms
out = tmp_path / "site"
out.mkdir()
(out / "roles").mkdir()
(out / "roles").chmod(0o777)
monkeypatch.setattr(ms, "_effective_uid", lambda: 1000)
# No exception: interior writability is irrelevant when not running as root.
ms._assert_no_output_symlinks(out)