Fix purify and highlight
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- purify: apply target=_blank to links
- purify: remove ALLOWED_URI_REGEXP - this breaks external links in
  anchor elements
- purify: return a DOM fragment instead of a string
- postprocess: only highlight pre
- postprocess: remove nested code inside pre
- better style messages with css
This commit is contained in:
Cadence Ember 2020-11-05 17:32:36 +13:00
parent 8ba9d73b33
commit a7165fe633
Signed by: cadence
GPG key ID: BC1C2C61CF521B17
4 changed files with 82 additions and 28 deletions

View file

@ -2,8 +2,16 @@ const {ElemJS} = require("../basic")
const {lazyLoad} = require("../lazy-load-module")
class HighlightedCode extends ElemJS {
constructor(code) {
super(code)
constructor(element) {
super(element)
if (this.element.tagName === "PRE" && this.element.children.length === 1 && this.element.children[0].tagName === "CODE") {
// we shouldn't nest code inside a pre. put the text in the pre directly.
const code = this.element.children[0]
this.clearChildren()
for (const child of code.childNodes) {
this.element.appendChild(child)
}
}
lazyLoad("./static/hljs.js").then(hljs => hljs.highlightBlock(this.element))
}
}

View file

@ -12,61 +12,80 @@ purifier.addHook("uponSanitizeAttribute", (node, hookevent, config) => {
const allowedElementAttributes = {
"FONT": ["data-mx-bg-color", "data-mx-color", "color"],
"SPAN": ["data-mx-bg-color", "data-mx-color", "color"],
"SPAN": ["data-mx-bg-color", "data-mx-color"],
"A": ["name", "target", "href"],
"IMG": ["width", "height", "alt", "title", "src", "data-mx-emoticon"],
"OL": ["start"],
"CODE": ["class"],
}
const allowed_attributes = allowedElementAttributes[node.tagName] || []
hookevent.keepAttr = allowed_attributes.indexOf(hookevent.attrName) > -1;
const allowedAttributes = allowedElementAttributes[node.tagName] || []
hookevent.keepAttr = allowedAttributes.indexOf(hookevent.attrName) > -1
})
purifier.addHook("uponSanitizeElement", (node, hookevent, config) => {
// Remove bad classes from our code element
if (node.tagName == "CODE") {
if (node.tagName === "CODE") {
node.classList.forEach(c => {
if (!c.startsWith("language-")) {
node.classList.remove(c)
}
})
}
if (node.tagName == "A") {
node.setAttribute("rel", "noopener")
if (node.tagName === "A") {
node.setAttribute("rel", "noopener") // prevent the opening page from accessing carbon
node.setAttribute("target", "_blank") // open in a new tab instead of replacing carbon
}
return node
})
function cleanHTML(html) {
const config = {
ALLOWED_URI_REGEXP: /^mxc:\/\/[a-zA-Z0-9\.]+\/[a-zA-Z0-9]+$/, // As per the spec we only allow mxc uris
ALLOWED_TAGS: ['font', 'del', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'blockquote', 'p', 'a', 'ul', 'ol', 'sup', 'sub', 'li', 'b', 'i', 'u', 'strong', 'em', 'strike', 'code', 'hr', 'br', 'div', 'table', 'thead', 'tbody', 'tr', 'th', 'td', 'caption', 'pre', 'span', 'img'],
ALLOWED_TAGS: [
"font", "del", "h1", "h2", "h3", "h4", "h5", "h6", "blockquote", "p",
"a", "ul", "ol", "sup", "sub", "li", "b", "i", "u", "strong", "em",
"strike", "code", "hr", "br", "div", "table", "thead", "tbody", "tr",
"th", "td", "caption", "pre", "span", "img",
// matrix tags
"mx-reply"
],
// In case we mess up in the uponSanitizeAttribute hook
ALLOWED_ATTR: ["data-mx-bg-color", "data-mx-color", "color",
"name", "target", "href",
"width", "height", "alt", "title", "src", "data-mx-emoticon",
"start", "class"],
ALLOWED_ATTR: [
"color", "name", "target", "href", "width", "height", "alt", "title",
"src", "start", "class", "noreferrer", "noopener",
// matrix attrs
"data-mx-emoticon", "data-mx-bg-color", "data-mx-color"
],
// Return a DOM fragment instead of a string, avoids potential future mutation XSS
// should also be faster than the browser parsing HTML twice
// https://research.securitum.com/mutation-xss-via-mathml-mutation-dompurify-2-0-17-bypass/
RETURN_DOM_FRAGMENT: true,
RETURN_DOM_IMPORT: true
}
return purifier.sanitize(html)
return purifier.sanitize(html, config)
}
// Here we put all the processing of the messages that isn't as likely to potentially lead to security issues
function postProcessElements(rootNode) {
const element = rootNode.element
element.querySelectorAll("code").forEach((n) => rootNode.child(new HighlightedCode(n)))
element.querySelectorAll("img").forEach((n) => {
element.querySelectorAll("pre").forEach(n => {
new HighlightedCode(n)
})
element.querySelectorAll("img").forEach(n => {
let src = n.getAttribute("src")
if (src) src = resolveMxc(src)
n.setAttribute("src", src)
})
element.querySelectorAll("font, span").forEach((n) => {
element.querySelectorAll("font, span").forEach(n => {
const color = n.getAttribute("data-mx-color") || n.getAttribute("color")
const bgColor = n.getAttribute("data-mx-bg-color")
if (color) n.style.color = color;
if (bgColor) n.style.backgroundColor = bgColor;
if (color) n.style.color = color
if (bgColor) n.style.backgroundColor = bgColor
})
}
@ -78,8 +97,8 @@ class HTMLMessage extends MatrixEvent {
let html = this.data.content.formatted_body
const content = ejs("div")
html = cleanHTML(html)
content.html(html)
const fragment = cleanHTML(html)
content.element.appendChild(fragment)
postProcessElements(content)
this.child(content)
@ -89,24 +108,23 @@ class HTMLMessage extends MatrixEvent {
static canRender(event) {
const content = event.content
return event.type == "m.room.message" && content.msgtype == "m.text" && content.format == "org.matrix.custom.html" && content.formatted_body
return event.type === "m.room.message" && content.msgtype === "m.text" && content.format === "org.matrix.custom.html" && content.formatted_body
}
canGroup() {
return true
}
}
class TextMessage extends MatrixEvent {
render() {
this.clearChildren()
this.text(this.data.content.body)
return super.render()
super.render()
}
static canRender(event) {
return event.type == "m.room.message"
return event.type === "m.room.message"
}
canGroup() {

View file

@ -5,3 +5,4 @@ $mild: #393c42
$milder: #42454a
$divider: #4b4e54
$muted: #999
$link: #57bffd

View file

@ -1,6 +1,6 @@
@use "../colors" as c
.c-event-groups *
.c-event-groups > *
overflow-anchor: none
.c-message-group, .c-message-event
@ -67,6 +67,33 @@
&:hover
background-color: c.$darker
// message formatting rules
code, pre
border-radius: 4px
font-size: 0.9em
pre
background-color: c.$darkest
padding: 8px
border: 1px solid c.$divider
code
background-color: c.$darker
padding: 2px 4px
a
color: c.$link
p, pre
margin: 16px 0px
&:first-child
margin-top: 0px
&:last-child
margin-bottom: 0px
.c-message-event
padding-top: 10px
padding-left: 6px