Fix all 8 security hardening blockers for PR #423

Co-authored-by: naturallaw777 <99053422+naturallaw777@users.noreply.github.com>
2026-08-11 15:38:08 +00:00
parent 894707a87c
commit 947c04834d
8 changed files with 979 additions and 452 deletions
@@ -0,0 +1,283 @@
+"""Sovran Hub — injectable support session operations.
+
+Functions here handle legacy migration, root-key removal, and support-session
+expiry.  All filesystem paths, clocks, and callback functions are injectable
+so that the test suite can exercise the exact production implementations with
+temporary files and mocks rather than maintaining separate copies.
+
+All functions depend only on the Python standard library and the co-located
+``security_helpers`` module.
+"""
+
+from __future__ import annotations
+
+import json
+import os
+import re
+import tempfile
+import time as _time_module
+from typing import Callable
+
+# ── Legacy Njalla curl line regex ─────────────────────────────────────────────
+#
+# Matches both forms written by old Hub versions:
+#   curl [flags] https://njal.la/...           (unquoted)
+#   curl [flags] "https://njal.la/..."          (quoted — historical form)
+#
+# Optional flags (in order): --silent, --max-time N, --fail
+#
+# Rejected outright: semicolons, pipes, backticks, redirects, newlines,
+# ${...} except the literal ${IP} placeholder, and any extra arguments.
+_LEGACY_NJALLA_CURL_RE = re.compile(
+    r'^curl\s+(?:--silent\s+)?(?:--max-time\s+\d+\s+)?(?:--fail\s+)?'
+    r'(?:'
+    r'"(https://(?:www\.)?njal\.la/(?:[^\s;|`$\x00-\x1f"]|\$\{IP\})+)"'   # group 1: quoted
+    r'|(https://(?:www\.)?njal\.la/(?:[^\s;|`$\x00-\x1f"]|\$\{IP\})+)'    # group 2: unquoted
+    r')$'
+)
+
+# The exact base64 blob of the historical fleet-wide root support key that
+# was shipped with old releases of Sovran_SystemsOS and must be removed from
+# /root/.ssh/authorized_keys on upgrade.
+LEGACY_ROOT_KEY_BLOB = (
+    "AAAAC3NzaC1lZDI1NTE5AAAAIPxPF2Qm11FQxC20wydKtlmn/Bo07YnDda3b9/CyXxQP"
+)
+
+
+def remove_legacy_root_key(
+    authorized_keys_path: str,
+    target_blob: str,
+    *,
+    audit_fn: Callable[[str, str], None] | None = None,
+) -> bool:
+    """Remove the exact historical fleet-wide support key from an authorized_keys file.
+
+    Identifies the key by its exact base64 blob (``parts[1]``), regardless of
+    algorithm prefix or comment field.  All other keys, blank lines, and comment
+    lines are preserved unchanged.  The file is written back atomically.
+
+    Args:
+        authorized_keys_path: Path to the authorized_keys file to modify.
+        target_blob: The exact base64 key blob to remove.  Only lines whose
+            second whitespace-delimited field matches this value are removed;
+            no substring or comment matching is performed.
+        audit_fn: Optional callback ``(event: str, details: str)`` for audit
+            logging.  The full key blob is **never** passed to this callback.
+
+    Returns:
+        ``True`` if the file was modified (at least one line removed),
+        ``False`` if unchanged or absent.
+    """
+
+    def _audit(event: str, details: str = "") -> None:
+        if audit_fn:
+            audit_fn(event, details)
+
+    try:
+        with open(authorized_keys_path, "r") as f:
+            lines = f.readlines()
+    except FileNotFoundError:
+        return False
+    except OSError:
+        return False
+
+    kept: list[str] = []
+    removed_count = 0
+    for line in lines:
+        stripped = line.rstrip("\n")
+        parts = stripped.split()
+        # Key lines have at least two space-separated fields: algorithm + blob.
+        # Remove only lines whose blob (parts[1]) matches exactly — no
+        # substring matching, no comment matching.
+        if len(parts) >= 2 and parts[1] == target_blob:
+            removed_count += 1
+            # Audit without logging the key blob itself.
+            _audit("LEGACY_ROOT_KEY_REMOVED", "removed exact historical root support key")
+        else:
+            kept.append(line)
+
+    if removed_count == 0:
+        return False
+
+    # Atomic write: mkstemp in same directory + os.replace
+    auth_dir = os.path.dirname(os.path.abspath(authorized_keys_path))
+    fd, tmp = tempfile.mkstemp(dir=auth_dir, prefix=".authorized_keys_tmp")
+    try:
+        with os.fdopen(fd, "w") as f:
+            f.writelines(kept)
+        os.chmod(tmp, 0o600)
+        os.replace(tmp, authorized_keys_path)
+    except Exception:
+        try:
+            os.unlink(tmp)
+        except OSError:
+            pass
+        return False
+
+    _audit(
+        "LEGACY_ROOT_KEY_CLEANUP_COMPLETE",
+        f"removed={removed_count} keys_retained={len(kept)}",
+    )
+    return True
+
+
+def migrate_legacy_njalla_script(
+    script_path: str,
+    validate_fn: Callable[[str], str],
+    save_fn: Callable[[list[str]], None],
+    load_fn: Callable[[], list[str]],
+    *,
+    audit_fn: Callable[[str, str], None] | None = None,
+) -> None:
+    """Safely migrate legacy curl DDNS lines from a njalla.sh script to JSON store.
+
+    Reads the script **without** executing or sourcing it.  Parses only the
+    exact narrow curl-pattern lines (quoted or unquoted) written by old Hub
+    versions.  Any other line is silently discarded — never executed or logged
+    (it may contain secret tokens).
+
+    On successful persistence the script is archived with mode ``0o000`` so
+    it can no longer be executed.  If persistence fails the script is left
+    **untouched**.
+
+    Args:
+        script_path: Path to the legacy njalla.sh file.
+        validate_fn: URL validation function; raises ``ValueError`` on invalid
+            URLs.  Callers must substitute the ``${IP}`` placeholder before
+            calling — this function passes ``url.replace("${IP}", "127.0.0.1")``
+            to the validator.
+        save_fn: Callable that atomically writes a ``list[str]`` URL list to
+            the persistent JSON store.
+        load_fn: Callable that returns the current ``list[str]`` URL list from
+            the persistent store.
+        audit_fn: Optional callback ``(event: str, details: str)`` for audit
+            logging.  Token-bearing URLs are **never** passed to this callback.
+    """
+
+    def _audit(event: str, details: str = "") -> None:
+        if audit_fn:
+            audit_fn(event, details)
+
+    try:
+        with open(script_path, "r") as f:
+            content = f.read()
+    except FileNotFoundError:
+        return
+    except OSError:
+        return
+
+    existing_urls = load_fn()
+
+    new_urls: list[str] = []
+    for raw_line in content.splitlines():
+        line = raw_line.strip()
+        if not line or line.startswith("#") or line.startswith("IP=") or line.startswith("#!/"):
+            continue
+        m = _LEGACY_NJALLA_CURL_RE.match(line)
+        if not m:
+            # Unrecognised line — discard silently, do NOT log (may contain tokens)
+            continue
+        # group(1) = quoted form, group(2) = unquoted form
+        raw_url = m.group(1) or m.group(2)
+        # Substitute placeholder so host/scheme/path validation works
+        url_to_validate = raw_url.replace("${IP}", "127.0.0.1")
+        try:
+            validate_fn(url_to_validate)
+        except ValueError:
+            continue  # Silently discard invalid/non-Njal.la URLs
+        if raw_url not in existing_urls and raw_url not in new_urls:
+            new_urls.append(raw_url)
+
+    if new_urls:
+        combined = existing_urls + new_urls
+        try:
+            save_fn(combined)
+        except Exception:
+            # Persistence failed — leave the script untouched, return without
+            # archiving so the migration can be retried.
+            return
+        _audit("NJALLA_MIGRATION", f"migrated {len(new_urls)} DDNS URLs from legacy script")
+
+    # Archive: remove all permission bits so cron/any mechanism cannot run it
+    try:
+        os.chmod(script_path, 0o000)
+    except OSError:
+        pass
+
+
+def expire_if_stale(
+    status_file: str,
+    *,
+    clock_fn: Callable[[], float] | None = None,
+    disable_fn: Callable[[], bool] | None = None,
+    audit_fn: Callable[[str, str], None] | None = None,
+    session_id: str | None = None,
+    expected_expiry: float | None = None,
+    max_session_seconds: float = 86400.0,
+) -> bool:
+    """Expire a support session if its deadline has passed.
+
+    **Stale-timer guard:** when ``session_id`` and/or ``expected_expiry`` are
+    provided (used by the server-side timer callback), the stored session
+    metadata is compared field-by-field.  A mismatch means a replacement
+    session has been started after this timer was scheduled; in that case the
+    function returns ``False`` without touching anything.
+
+    Args:
+        status_file: Path to the JSON session metadata file.
+        clock_fn: Callable returning current Unix time (default: ``time.time``).
+        disable_fn: Callable that performs the full disable sequence — removes
+            the support key, removes wallet-unlock metadata, restores deny
+            ACLs, clears session metadata, and audits the event.  If ``None``,
+            expiry is detected but no action is taken (useful for tests that
+            want to inspect detection only).
+        audit_fn: Optional callback ``(event: str, details: str)`` for audit
+            logging.
+        session_id: If given, expiry is skipped unless the stored
+            ``session_id`` field matches exactly.
+        expected_expiry: If given, expiry is skipped unless the stored
+            ``expires_at`` field matches exactly.
+        max_session_seconds: Legacy fallback: maximum age (from ``enabled_at``)
+            when ``expires_at`` is absent.
+
+    Returns:
+        ``True`` if a session was expired, ``False`` otherwise.
+    """
+    _now = clock_fn if clock_fn is not None else _time_module.time
+
+    def _audit(event: str, details: str = "") -> None:
+        if audit_fn:
+            audit_fn(event, details)
+
+    def _disable() -> bool:
+        return disable_fn() if disable_fn is not None else True
+
+    try:
+        with open(status_file, "r") as f:
+            info = json.load(f)
+    except (FileNotFoundError, json.JSONDecodeError):
+        return False
+
+    # Stale-timer guard
+    if session_id is not None and info.get("session_id") != session_id:
+        return False
+    if expected_expiry is not None and info.get("expires_at") != expected_expiry:
+        return False
+
+    expires_at = info.get("expires_at")
+    now = _now()
+
+    if expires_at is None:
+        enabled_at = info.get("enabled_at", 0)
+        if enabled_at and (now - enabled_at) > max_session_seconds:
+            _audit("SUPPORT_EXPIRED", "legacy session without expires_at exceeded max duration")
+            _disable()
+            return True
+        return False
+
+    if now >= expires_at:
+        _audit("SUPPORT_EXPIRED", f"session expired at {expires_at:.0f}")
+        _disable()
+        return True
+
+    return False