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fix: escape HTML style text in foreign content #33

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fix: escape HTML style text in foreign content #33

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82 changes: 79 additions & 3 deletions lib/NodeUtils.js
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Original file line number Diff line number Diff line change
Expand Up @@ -117,6 +117,16 @@ function escapeAttr(s) {
});
}

function serializeForeignRawText(element) {
var s = '';
for (var child = element.firstChild; child; child = child.nextSibling) {
s += child.nodeType === 3 /*TEXT_NODE*/ ||
child.nodeType === 4 /*CDATA_SECTION_NODE*/ ?
escape(child.data) : serializeOne(child, element);
}
return s;
}

function attrname(a) {
var ns = a.namespaceURI;
if (!ns)
Expand Down Expand Up @@ -225,6 +235,68 @@ function escapeProcessingInstructionContent(rawContent) {
: rawContent;
}

var foreignContextCache = new WeakMap();

function cacheForeignContext(node, stop, foreign, clock) {
for (; node && node !== stop; node = node.parentNode) {
foreignContextCache.set(node, {
clock: clock,
document: node.ownerDocument,
foreign: foreign
});
}
return foreign;
}

function isInForeignContent(parent, kid) {
if (parent.nodeType === 0 && kid.parentNode)
parent = kid.parentNode;

var clock = parent.rooted && parent.ownerDocument.modclock;
var start = clock ? parent : null;
var childName = '';
var root = null;
while (parent && parent.nodeType === 1 /*ELEMENT_NODE*/) {
var cached = start && foreignContextCache.get(parent);
if (cached && cached.document === parent.ownerDocument &&
cached.clock === clock)
return cacheForeignContext(start, parent, cached.foreign, clock);

root = parent;
var name = utils.toASCIILowerCase(parent.localName);

if (name === 'svg' || name === 'math')
return cacheForeignContext(start, parent, true, clock);
if (name === 'foreignobject' || name === 'desc' || name === 'title')
return cacheForeignContext(start, parent, false, clock);
if (name === 'mi' || name === 'mo' || name === 'mn' ||
name === 'ms' || name === 'mtext')
return cacheForeignContext(start, parent,
childName === 'mglyph' || childName === 'malignmark', clock);
if (name === 'annotation-xml') {
start = null;
for (var i = 0; i < parent._numattrs; i++) {
var attribute = parent._attr(i);
if (utils.toASCIILowerCase(attrname(attribute)) === 'encoding') {
var encoding = attribute.value &&
utils.toASCIILowerCase(attribute.value);
if (encoding === 'text/html' ||
encoding === 'application/xhtml+xml')
return cacheForeignContext(start, parent, false, clock);
break;
}
}
}

childName = name;
parent = parent.parentNode;
}

return cacheForeignContext(start, parent, !!root &&
(root.namespaceURI === NAMESPACE.SVG ||
root.namespaceURI === NAMESPACE.MATHML), clock);
}

function serializeOne(kid, parent) {
var s = '';
switch(kid.nodeType) {
Expand All @@ -243,11 +315,15 @@ function serializeOne(kid, parent) {
s += '>';

if (!(html && emptyElements[tagname])) {
var ss = kid.serialize();
var upperTag = tagname.toUpperCase();
// If an element can have raw content, this content may
// potentially require escaping to avoid XSS.
var upperTag = tagname.toUpperCase();
if (hasRawContent[upperTag] && !hasRawContentFallback[upperTag]) {
var nonFallbackRawContent = hasRawContent[upperTag] &&
!hasRawContentFallback[upperTag];
var escapeRawText = html && nonFallbackRawContent && !kid._innerHTML &&
isInForeignContent(parent, kid);
var ss = escapeRawText ? serializeForeignRawText(kid) : kid.serialize();
if (!escapeRawText && nonFallbackRawContent) {
ss = escapeMatchingClosingTag(ss, tagname);
}
if (html && extraNewLine[tagname] && ss.charAt(0)==='\n') s += '\n';
Expand Down
191 changes: 191 additions & 0 deletions test/xss.js
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Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,197 @@ exports.fp170_37 = function () {
);
};

exports.htmlStyleTextMovedIntoForeignContentIsEscaped = function () {
const SVG = 'http://www.w3.org/2000/svg';
const payload =
'--literal:"&copy;\u00A0";/*<img><script>alert("foreign-style-xss")</script>*/';
const document = domino.createDocument('');
const svg = document.createElementNS(SVG, 'svg');
const group = document.createElementNS(SVG, 'g');
const wrapper = document.createElement('g');
const style = document.createElement('style');
const marker = document.createElement('span');
style.textContent = payload;
marker.textContent = 'kept';
style.appendChild(marker);
wrapper.appendChild(style);
svg.appendChild(group);
document.body.appendChild(svg);
document.body.appendChild(wrapper);
document.serialize().should.containEql('<style>' + payload);
group.appendChild(wrapper);

const html = document.serialize();
html.should.containEql(
'--literal:"&amp;copy;&nbsp;";/*&lt;img&gt;&lt;script&gt;',
);
html.should.containEql('&lt;/script&gt;*/');
html.should.containEql('<span>kept</span>');
return alertFired(html).should.eventually.be.false('alert fired for: ' + html);
};

exports.foreignContextCacheDoesNotCrossDocuments = function () {
const SVG = 'http://www.w3.org/2000/svg';
const payload = '{"x":"<img src=x onerror=alert(42)>"}';
const first = domino.createDocument('');
const wrapper = first.createElement('a');
const script = first.createElement('script');
script.type = 'application/json';
script.textContent = payload;
wrapper.appendChild(script);
first.body.appendChild(wrapper);
first.serialize().should.containEql(payload);

const second = domino.createDocument('');
const svg = second.createElementNS(SVG, 'svg');
second.body.appendChild(svg);
svg.appendChild(wrapper);

const html = second.serialize();
html.should.containEql('{"x":"&lt;img src=x onerror=alert(42)&gt;"}');
return alertFired(html).should.eventually.be.false('alert fired for: ' + html);
};

exports.foreignContextCacheSkipsUntrackedDocuments = function () {
const payload = '<img src=x onerror=alert(713)>';
const document = domino.createDocument(
'<main><a><style></style></a></main><svg><g></g></svg>',
).cloneNode(true);
const style = document.querySelector('style');
const wrapper = style.parentNode;
style.textContent = payload;
document.modclock.should.equal(0);
style.outerHTML.should.containEql('<style>' + payload + '</style>');
document.querySelector('svg g').appendChild(wrapper);

const html = document.serialize();
html.should.containEql(
'<style>&lt;img src=x onerror=alert(713)&gt;</style>',
);
return alertFired(html).should.eventually.be.false('alert fired for: ' + html);
};

const HTML_ELEMENT = null;
const SVG = 'http://www.w3.org/2000/svg';
const MATHML = 'http://www.w3.org/1998/Math/MathML';
const styleCss =
'@media (width < 600px) { svg > g { --label: "&"; } }' +
'/*<img><script>alert(1)</script>*/';
const serializedStyleCss =
'@media (width &lt; 600px) { svg &gt; g { --label: "&amp;"; } }' +
'/*&lt;img&gt;&lt;script&gt;alert(1)&lt;/script&gt;*/';

function createStyleDocument(ancestors) {
const document = domino.createDocument('');
let parent = document.body;
for (const [namespace, name, attributes = {}] of ancestors) {
const element = namespace ?
document.createElementNS(namespace, name) : document.createElement(name);
for (const attribute in attributes) {
element.setAttribute(attribute, attributes[attribute]);
}
parent.appendChild(element);
parent = element;
}

const style = document.createElement('style');
style.textContent = styleCss;
parent.appendChild(style);
return document;
}

function assertStyleSerialization(ancestors, expected) {
const document = createStyleDocument(ancestors);
document.body.serialize().should.containEql(
'<style>' + expected + '</style>',
);
return document;
}

exports.rawContentIsEscapedInForeignContent = function () {
const cases = [
[[SVG, 'svg']],
[[SVG, 'svg'], [HTML_ELEMENT, 'g']],
[[SVG, 'svg'], [SVG, 'foreignObject'], [HTML_ELEMENT, 'svg']],
[[MATHML, 'math'], [HTML_ELEMENT, 'mtext'], [HTML_ELEMENT, 'mglyph']],
[[MATHML, 'math'],
[MATHML, 'annotation-xml', { encoding: 'application/xml' }]],
];
for (const ancestors of cases) {
assertStyleSerialization(ancestors, serializedStyleCss);
}
};

exports.rawContentRemainsRawAtHtmlIntegrationPoints = function () {
const cases = [
[[SVG, 'svg'], [SVG, 'foreignObject'], [HTML_ELEMENT, 'div']],
[[SVG, 'svg'], [SVG, 'foreignObject'], [SVG, 'a']],
[[MATHML, 'math'], [HTML_ELEMENT, 'mtext']],
];
for (const ancestors of cases) {
assertStyleSerialization(ancestors, styleCss);
}
};

exports.annotationXmlEncodingChangeUpdatesRawContentContext = function () {
const document = assertStyleSerialization(
[[MATHML, 'math'],
[MATHML, 'annotation-xml', { ENCODING: 'TEXT/HTML' }],
[HTML_ELEMENT, 'div']],
styleCss,
);
document.querySelector('annotation-xml')
.setAttribute('ENCODING', 'application/xml');
document.body.serialize().should.containEql(
'<style>' + serializedStyleCss + '</style>',
);
};

exports.detachedRawContentUsesSerializedRootContext = function () {
for (const [namespace, name] of [
[SVG, 'g'],
[HTML_ELEMENT, 'svg'],
['http://www.w3.org/1999/xhtml', 'SvG'],
]) {
const document = domino.createDocument('');
const root = namespace ?
document.createElementNS(namespace, name) : document.createElement(name);
const style = document.createElement('style');
style.textContent = styleCss;
root.appendChild(style);
root.outerHTML
.should.containEql('<style>' + serializedStyleCss + '</style>');
}
};

exports.serializedForeignStylePreservesCssSemantics = async function () {
const page = await browser.newPage();
await page.setContent(
'<svg><style>' + serializedStyleCss + '</style></svg>',
);
(await page.$eval('style', (element) => element.textContent))
.should.equal(styleCss);
await page.close();
};

exports.plaintextInForeignObjectKeepsParserFixture = function () {
const document = domino.createDocument(
'<svg><foreignObject><div>foo</div><plaintext>' +
'</foreignObject></svg><div>bar</div>',
);
document.serialize().should.equal(
'<html><head></head><body>' +
'<svg><foreignObject><div>foo</div><plaintext>' +
'</foreignObject></svg><div>bar</div></plaintext>' +
'</foreignObject></svg></body></html>',
);
document.body.innerHTML.should.equal(
'<svg><foreignObject><div>foo</div><plaintext>' +
'</foreignObject></svg><div>bar</div></plaintext>' +
'</foreignObject></svg>',
);
};

exports.escapeAngleBracketsInDivAttr = function () {
var document = domino.createDocument(
`<div>You don't have JS! Click<a href="#" title="Search for </div><script>alert(1)</script> without JS">here</a> to go to the no-js website.</div>`,
Expand Down