Squash Odysseus development history

tests/test_calendar_css_url_escape_js.py

@@ -0,0 +1,107 @@
+r"""DOM/CSS-injection regression for calendar background-image URL escaping.
+
+CodeQL `js/incomplete-sanitization` (#463 calendar.js:416, #464 calendar.js:1263)
+flagged event-background CSS that escaped `'` -> `\'` without first escaping
+backslashes. A `bg:`-color value (settable per event, and CalDAV-syncable, so
+untrusted) ending in or containing a backslash can then consume the closing
+quote of `url('...')` and break out of the CSS string.
+
+The fix is a single canonical escaper, `_cssUrlEscape`, in calendar/utils.js,
+used by both inline sinks and by `_calBgCss` (which had the same incomplete
+escaping). These tests pin the escaper: backslashes are doubled FIRST, then
+quotes, so no input can terminate the `url('...')` string early.
+"""
+
+import json
+import re
+import shutil
+import subprocess
+import textwrap
+from pathlib import Path
+
+import pytest
+
+_REPO = Path(__file__).resolve().parent.parent
+_UTILS = (_REPO / "static" / "js" / "calendar" / "utils.js").as_posix()
+_CALENDAR_JS = _REPO / "static" / "js" / "calendar.js"
+_HAS_NODE = shutil.which("node") is not None
+
+pytestmark = pytest.mark.skipif(not _HAS_NODE, reason="node binary not on PATH")
+
+
+def _run(js: str) -> str:
+    proc = subprocess.run(
+        ["node", "--input-type=module"],
+        input=js, capture_output=True, text=True, cwd=str(_REPO), timeout=30,
+    )
+    assert proc.returncode == 0, proc.stderr
+    return proc.stdout.strip()
+
+
+def test_cssurlescape_doubles_backslashes_before_quotes():
+    js = textwrap.dedent(
+        f"""
+        const {{ _cssUrlEscape }} = await import('{_UTILS}');
+        console.log(JSON.stringify({{
+          backslash: _cssUrlEscape('a\\\\b'),
+          trailing:  _cssUrlEscape('img\\\\'),
+          quote:     _cssUrlEscape("a'b"),
+          dquote:    _cssUrlEscape('a"b'),
+        }}));
+        """
+    )
+    out = json.loads(_run(js))
+    # one backslash -> two; the escape for "'" is not itself re-escaped
+    assert out["backslash"] == r"a\\b"
+    assert out["trailing"] == "img\\\\"   # 'img\' -> 'img\\'
+    assert out["quote"] == r"a\'b"
+    assert out["dquote"] == "a%22b"
+
+
+def test_backslash_breakout_payload_cannot_close_the_url_string():
+    # Without the backslash-first escape, "x\" would render url('x\') and the
+    # trailing backslash escapes the closing quote -> breakout. After the fix the
+    # backslash is doubled, so the quote we add still terminates the string.
+    js = textwrap.dedent(
+        f"""
+        const {{ _cssUrlEscape, _calBgCss }} = await import('{_UTILS}');
+        const payload = 'x\\\\';                       // a string ending in one backslash
+        console.log(JSON.stringify({{
+          esc: _cssUrlEscape(payload),
+          css: _calBgCss('bg:' + payload, 'var(--accent)'),
+        }}));
+        """
+    )
+    out = json.loads(_run(js))
+    assert out["esc"] == "x\\\\"                       # doubled backslash
+    # The rendered declaration keeps the backslash doubled inside url('...').
+    assert "url('x\\\\')" in out["css"]
+
+
+def test_calbgcss_escapes_quote_breakout():
+    js = textwrap.dedent(
+        f"""
+        const {{ _calBgCss }} = await import('{_UTILS}');
+        console.log(JSON.stringify(_calBgCss("bg:a'); X{{}}//", 'var(--accent)')));
+        """
+    )
+    css = json.loads(_run(js))
+    # the injected single quote is escaped, so the url() string is not closed early
+    assert r"\'" in css
+    assert "url('a\\'); X{}//')" in css
+
+
+def test_every_calendar_url_interpolation_is_escaped():
+    # Whole-file invariant: every CSS `url('${...}')` built in calendar.js must
+    # route its (CalDAV-syncable, untrusted) value through `_cssUrlEscape`. This
+    # is the guard that catches a *newly added* bg-image sink the centralization
+    # forgot - the failure mode that left calendar.js:2856 (edit-form color
+    # swatch) and :2953 (custom-dot preview) raw before this change.
+    src = _CALENDAR_JS.read_text(encoding="utf-8")
+    interps = re.findall(r"url\('\$\{([^}]*)\}'\)", src)
+    assert interps, "expected at least one url('${...}') interpolation in calendar.js"
+    unescaped = [expr for expr in interps if "_cssUrlEscape(" not in expr]
+    assert not unescaped, (
+        "bg-image url() interpolation(s) not routed through _cssUrlEscape: "
+        + ", ".join(repr(e) for e in unescaped)
+    )