security: triage the CodeQL backlog — 129 alerts, three of them live (#561)

* fix(web): escape quotes in every HTML escaper, not just & < > The escapers are all `div.textContent = x; return div.innerHTML`. That round-trip escapes &, < and > -- the only characters the HTML serializer must escape in a text node -- and leaves quotes alone. Every widget then interpolates the result into a quoted attribute value: value="${escapeHtml(v)}" title="${escapeHtml(v)}" so a value of `x" onmouseover="alert(1)` closes the attribute and adds an event handler of its own. CodeQL reported this 83 times (js/incomplete-html-attribute-sanitization) across the widget files. It is one bug, not 83: the widgets each carry a standalone fallback that did escape quotes, but they all prefer BaseWidget.escapeHtml when window.BaseWidget exists -- which it always does in the shipped page -- so the correct fallbacks were dead code and the incomplete shared one ran. Fixed at each source instead of at the call sites. app-shell.js already documented this exact gap in a comment and worked around it by building DOM nodes by hand; that workaround stays (setting a property cannot be got wrong), the comment is now accurate. cache.html's delete button interpolated the cache key into `onclick="deleteCacheFile('...')"`. Escaping cannot help there -- the browser HTML-decodes the attribute before parsing it as JS, so `'` becomes a real `'` again -- so the key moves to a data-cache-key attribute that the handler reads back. url-input.js additionally wrote a value straight into an <a href> after validating it against a schema-supplied protocol list, and that list accepted any RFC 3986 scheme -- "javascript" included. Scriptable schemes (javascript, data, vbscript, blob, filesystem) are now refused both when the list is normalised and when a URL is checked against it, and the render path routes its href through the same check instead of emitting whatever was stored (js/xss-through-dom). test/js/unit/test_html_escaping.js reads each escaper out of the shipped file and runs it, so losing the quote handling again fails a test rather than a scan. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> * fix(security): stop request-supplied names from reaching paths outside their base Three of the py/path-injection alerts were live, not lint: * GET /api/v3/plugins/<plugin_id>/static/<path:file_path> read any file whose resolved path *string-prefixed* the plugin directory. Flask's default converter forbids a slash but not dots, and get_plugin_directory('..') returned the parent of the plugins directory because it exists -- so every file under the project root then prefixed that directory, config/config_secrets.json included. The prefix check was also wrong on its own terms: with plugin dir "plugin-repos/foo", "../foo-evil/x" resolves to "plugin-repos/foo-evil/x", whose string does start with "plugin-repos/foo". * POST /api/v3/plugins/of-the-day/json/delete interpolated the request body's file_id into f"{file_id}.json" and unlinked it, unvalidated. A file_id of "../../../../etc/something" deleted that file. This is the one finding in the batch that destroyed data rather than exposing it. * POST /api/v3/cache/delete passed the body's key through CacheManager.clear_cache to DiskCache, which joined it as a filename and called os.remove. Same shape, same result. The guard goes in DiskCache.get_cache_path, the single choke point get/set/clear share, so every caller is covered rather than just this route. Real keys are the stems of files already flat in the cache directory -- that is how list_cache_files derives them -- so nothing legitimate is turned away. The rest of the cluster (web_interface/app.py's asset route, the plugin update handler, _get_plugin_version, the plugin-schema read in config.py) was guarded in ways that held, but each had grown its own version of the check. They now go through one helper, src/common/path_safety.py, which returns the *sanitised value* rather than a verdict -- so a caller cannot validate one string and open another, which is how the two real bugs above were shaped. Also: WiFiManager.connect_to_network took the SSID and password straight from POST /api/v3/wifi/connect into nmcli's argv. There is no shell there, so CodeQL's py/command-line-injection alert overstates the risk -- but nmcli reads a leading "-" as an option, so an SSID of "--ask" asks nmcli to run differently rather than to join a network. Both values are now checked for shape (802.11's 32-octet SSID limit, WPA's 8-63 char passphrase or 64-char hex key, no control characters, no leading dash) before any subprocess runs. test/test_path_traversal_guards.py asserts on the filesystem, not just the status code: a handler that returns 403 and deletes the file anyway would pass the weaker check. Twelve of its cases fail against the unpatched code. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> * fix(web): refuse a plugin id that is not a plain name, don't truncate it pages_v3 and scripts/dev_server.py ran request ids through os.path.basename and carried on with what came out, so "../weather" rendered the config form for "weather". Nothing escaped the plugins directory -- the relative_to guards held -- but the handler answered a request nobody made, and validating one string while the filesystem sees another is the shape both live traversals earlier in this branch had. Same treatment as the rest: safe_path_component rejects rather than truncates, resolve_under returns the path it checked, and the call sites use what those return. The three handlers that had hand-rolled resolve-and-relative_to blocks lose about twenty lines to the shared one. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> * docs(web): say what the plugin web_ui iframe actually is The docstring claimed the fragment runs "in a sandboxed iframe". The iframe in plugin_config.html carries no sandbox attribute, so the fragment runs with the interface's own origin. That is fine -- the file belongs to an installed plugin, and an installed plugin already runs Python on the device, so the trust boundary is install rather than this route -- but a comment promising containment that is not there is worse than no comment. This is the context for the py/reflective-xss alert on this handler. Also drops the now-unused os/os.path imports. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> * fix(web): inline url-input's scheme guard at the previewLink.href sink CodeQL flagged this line as a new high-severity js/xss-through-dom alert on this PR even though it is already covered by SCRIPTABLE_SCHEMES: the guard reached the sink through safeHref -> isValidUrl, two function calls away, which its DOM-based-XSS sanitizer recognition does not trace. Behavior is unchanged -- same scheme check, same SCRIPTABLE_SCHEMES list, same allowedProtocols gate -- just inlined directly above the previewLink.href assignment it guards, so the barrier is visible in the same scope as the sink. Added a regression test that runs the shipped onInput handler (not just the extracted helpers) against a mocked DOM, so a future change that reintroduces an unguarded previewLink.href assignment fails here. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> * fix(security): address CodeRabbit findings on the CodeQL triage PR - src/wifi_manager.py: reject non-ASCII WPA-PSK passphrases before any credential-saving or connect flow runs. NetworkManager only accepts printable ASCII passphrases (or a 64-char hex key); a non-ASCII value was previously saved/attempted before nmcli itself rejected it. - web_interface/blueprints/api_v3/config.py: fail closed when the plugin config schema path can't be resolved under the plugins directory (e.g. a symlinked plugin dir). Previously this fell through with secret_fields left empty, so submitted credentials for that plugin were saved as ordinary, unencrypted configuration. - web_interface/static/v3/js/widgets/plugin-file-manager.js: stop splicing the JSON day/column key into an inline oninput="..." handler string. escHtml() escapes quotes for a normal HTML attribute, but the browser HTML-decodes the attribute before running it as script, which undoes that escaping and lets a crafted column name (e.g. from an uploaded JSON file) break out of the JS string and execute. Cell edits now travel through data-day/data-col attributes read by one delegated 'input' listener instead. While in this file: fixed 6 pre-existing missing-')' typos on multi-line safeSetHTML(...) calls (already flagged by Biome in this PR's own CodeRabbit run as syntax errors blocking its lint pass). These predate this PR (present on main too) but made the whole file fail to parse in any JS engine, which is a bigger problem than the XSS finding itself and directly touches the same lines. Added/extended regression tests for each fix; full suites pass (pytest: 4580 passed, 62 skipped; JS: 84 assertions). Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
2026-10-04 22:35:08 +00:00 · 2026-09-11 15:32:03 -04:00
parent 5137e86d16
commit f6367d63ae
27 changed files with 1520 additions and 170 deletions
@@ -0,0 +1,125 @@
+"""One place to turn a request-supplied name into a path you can open.
+
+Every web handler that opens a file under a fixed directory had grown its own
+version of this: a regex here, an ``os.path.basename`` there, a
+``str(x).startswith(str(base))`` somewhere else. They were not equivalent.
+``startswith`` says ``plugin-repos/foo-evil`` is inside ``plugin-repos/foo``;
+validating a name in one place and rebuilding the path from the *raw* value in
+another leaves the guard checking something the filesystem never sees.
+
+Two functions, used the same way everywhere:
+
+``safe_path_component(value)``
+    ``value`` if it is one harmless path segment, otherwise ``None``.
+
+``resolve_under(base, *parts)``
+    the resolved path, or ``None`` if any part is unsafe or the result would
+    land outside ``base``.
+
+Both *return the sanitised value* rather than a boolean, so a caller cannot
+validate one string and then open another -- and so a scanner can follow what
+actually reaches ``open()``. ``os.path.basename`` does the stripping because it
+is the sanitiser CodeQL's path-injection query recognises; the equality check
+after it means an input with a directory part is rejected outright instead of
+being silently truncated to something the caller did not ask for.
+"""
+
+from __future__ import annotations
+
+import os
+from pathlib import Path
+from typing import Any, List, Optional, Union
+
+__all__ = [
+    'safe_path_component',
+    'safe_relative_parts',
+    'resolve_under',
+]
+
+# Names that are a path component syntactically but never name a real entry a
+# caller means to reach.
+_RESERVED_COMPONENTS = frozenset({'', '.', '..'})
+
+
+def safe_path_component(value: Any) -> Optional[str]:
+    """Return ``value`` when it is a single, harmless path segment.
+
+    Returns ``None`` for anything else: a non-string, an empty string, ``.`` or
+    ``..``, a value carrying a directory separator (either platform's), a drive
+    letter, or an embedded NUL.
+
+    The return value is what callers must join -- not the argument.
+    """
+    if not isinstance(value, str) or not value:
+        return None
+    if '\x00' in value:
+        return None
+
+    # basename strips any directory component, so what a caller joins cannot
+    # carry one. Comparing the result against the input rejects rather than
+    # truncates: "../etc/passwd" is an error, not a request for "passwd".
+    name = os.path.basename(value)
+    if name != value or name in _RESERVED_COMPONENTS:
+        return None
+
+    # basename only knows the host platform's separator. On POSIX a backslash
+    # is an ordinary character, and "C:" is a plausible-looking name that
+    # os.path.join would treat as a drive on Windows. Rule both out everywhere
+    # so behaviour does not depend on where the service happens to run.
+    if '/' in name or '\\' in name or os.sep in name or (os.altsep and os.altsep in name):
+        return None
+    if ':' in name and len(name) >= 2 and name[1] == ':':
+        return None
+
+    return name
+
+
+def safe_relative_parts(value: Any) -> Optional[List[str]]:
+    """Split a multi-segment relative path into safe components.
+
+    For Flask's ``<path:...>`` converter, where ``a/b/c.json`` is legitimate but
+    ``../../config/config_secrets.json`` is not. Returns the component list, or
+    ``None`` if any component fails :func:`safe_path_component`.
+    """
+    if not isinstance(value, str) or not value:
+        return None
+    if value.startswith('/') or value.startswith('\\'):
+        return None
+
+    parts: List[str] = []
+    for raw in value.replace('\\', '/').split('/'):
+        if raw == '':
+            # A trailing or doubled slash names nothing; skip it rather than
+            # rejecting a path a browser may well send.
+            continue
+        part = safe_path_component(raw)
+        if part is None:
+            return None
+        parts.append(part)
+
+    return parts or None
+
+
+def resolve_under(base: Union[str, Path], *parts: Any) -> Optional[Path]:
+    """Resolve ``base/parts...``, or ``None`` if that would escape ``base``.
+
+    Each part is validated with :func:`safe_path_component` first, so the value
+    that reaches the filesystem is the sanitised one. The containment check is
+    kept as well: it is what catches a symlink inside ``base`` pointing out of
+    it, which no amount of name validation can see.
+    """
+    safe_parts: List[str] = []
+    for part in parts:
+        component = safe_path_component(part)
+        if component is None:
+            return None
+        safe_parts.append(component)
+
+    try:
+        base_resolved = Path(base).resolve()
+        candidate = base_resolved.joinpath(*safe_parts).resolve()
+        candidate.relative_to(base_resolved)
+    except (OSError, ValueError, TypeError):
+        return None
+
+    return candidate