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authorWojtek Kosior <koszko@koszko.org>2021-09-08 19:55:33 +0200
committerWojtek Kosior <koszko@koszko.org>2021-09-08 19:55:33 +0200
commite2d26bad35bbe3876862b482f7963d713238313b (patch)
tree47e6647c239e8f85fa764cfa5750e0f73e1efd74
parent704f2da0673dc714f72b9bb82f6bf648795d4335 (diff)
downloadbrowser-extension-e2d26bad35bbe3876862b482f7963d713238313b.tar.gz
browser-extension-e2d26bad35bbe3876862b482f7963d713238313b.zip
Fix sanitizing of non-HTML XMLDocument's
-rwxr-xr-xbuild.sh4
-rw-r--r--common/misc.js4
-rw-r--r--content/activity_info_server.js6
-rw-r--r--content/main.js195
-rw-r--r--content/page_actions.js6
-rw-r--r--html/display-panel.js4
6 files changed, 109 insertions, 110 deletions
diff --git a/build.sh b/build.sh
index 66f709c..478ca04 100755
--- a/build.sh
+++ b/build.sh
@@ -201,9 +201,7 @@ main() {
if [ "$BROWSER" = "chromium" ]; then
CHROMIUM_KEY="$(dd if=/dev/urandom bs=32 count=1 2>/dev/null | base64)"
- echo "chromium key is" $CHROMIUM_KEY
- CHROMIUM_KEY="chromium-key-dummy-file-$CHROMIUM_KEY"
- CHROMIUM_KEY=$(echo $CHROMIUM_KEY | tr / -);
+ CHROMIUM_KEY=$(echo chromium-key-dummy-file-$CHROMIUM_KEY | tr / -)
touch $BUILDDIR/$CHROMIUM_KEY
CHROMIUM_KEY="\n\
diff --git a/common/misc.js b/common/misc.js
index 91d60d2..6adaf1e 100644
--- a/common/misc.js
+++ b/common/misc.js
@@ -36,9 +36,9 @@ function Uint8toHex(data)
return returnValue;
}
-function gen_nonce(length) // Default 16
+function gen_nonce(length=16)
{
- let randomData = new Uint8Array(length || 16);
+ let randomData = new Uint8Array(length);
crypto.getRandomValues(randomData);
return Uint8toHex(randomData);
}
diff --git a/content/activity_info_server.js b/content/activity_info_server.js
index beecb1a..1b69703 100644
--- a/content/activity_info_server.js
+++ b/content/activity_info_server.js
@@ -44,9 +44,9 @@ function report_settings(settings)
report_activity("settings", settings);
}
-function report_content_type(content_type)
+function report_document_type(is_html)
{
- report_activity("content_type", content_type);
+ report_activity("is_html", is_html);
}
function report_repo_query_action(update, port)
@@ -96,6 +96,6 @@ function start_activity_info_server()
* EXPORT start_activity_info_server
* EXPORT report_script
* EXPORT report_settings
- * EXPORT report_content_type
+ * EXPORT report_document_type
* EXPORTS_END
*/
diff --git a/content/main.js b/content/main.js
index a183913..fb334dd 100644
--- a/content/main.js
+++ b/content/main.js
@@ -22,6 +22,12 @@
* IMPORTS_END
*/
+document.content_loaded = document.readyState === "complete";
+const wait_loaded = e => e.content_loaded ? Promise.resolve() :
+ new Promise(c => e.addEventListener("DOMContentLoaded", c, {once: true}));
+
+wait_loaded(document).then(() => document.content_loaded = true);
+
function extract_cookie_policy(cookie, min_time)
{
let best_result = {time: -1};
@@ -86,18 +92,17 @@ function employ_nonhttp_policy(policy)
}
/*
+ * In the case of HTML documents:
* 1. When injecting some payload we need to sanitize <meta> CSP tags before
* they reach the document.
* 2. Only <meta> tags inside <head> are considered valid by the browser and
* need to be considered.
* 3. We want to detach <html> from document, wait until its <head> completes
* loading, sanitize it and re-attach <html>.
- * 4. Browsers are eager to add <meta>'s that appear after `</head>' but before
- * `<body>'. Due to this behavior the `DOMContentLoaded' event is considered
- * unreliable (although it could still work properly, it is just problematic
- * to verify).
- * 5. We shall wait for anything to appear in or after <body> and take that as
- * a sign <head> has _really_ finished loading.
+ * 4. We shall wait for anything to appear in or after <body> and take that as
+ * a sign <head> has finished loading.
+ * 5. Otherwise, getting the `DOMContentLoaded' event on the document shall also
+ * be a sign that <head> is fully loaded.
*/
function make_body_start_observer(DOM_element, waiting)
@@ -123,8 +128,10 @@ function try_body_started(waiting)
function finish_waiting(waiting)
{
+ if (waiting.finished)
+ return;
+ waiting.finished = true;
waiting.observers.forEach(observer => observer.disconnect());
- waiting.doc.removeEventListener("DOMContentLoaded", waiting.loaded_cb);
setTimeout(waiting.callback, 0);
}
@@ -132,19 +139,12 @@ function _wait_for_head(doc, detached_html, callback)
{
const waiting = {doc, detached_html, callback, observers: []};
- /*
- * For XML and SVG documents, instead of waiting for `<head>', we wait
- * for the entire document to finish loading.
- */
- if (doc instanceof HTMLDocument) {
- if (try_body_started(waiting))
- return;
+ if (try_body_started(waiting))
+ return;
- waiting.observers = [make_body_start_observer(detached_html, waiting)];
- }
+ waiting.observers = [make_body_start_observer(detached_html, waiting)];
- waiting.loaded_cb = () => finish_waiting(waiting);
- doc.addEventListener("DOMContentLoaded", waiting.loaded_cb);
+ wait_loaded(doc).then(() => finish_waiting(waiting));
}
function wait_for_head(doc, detached_html)
@@ -154,42 +154,43 @@ function wait_for_head(doc, detached_html)
const blocked_str = "blocked";
-function block_attribute(node, attr)
+function block_attribute(node, attr, ns=null)
{
+ const [hasa, geta, seta, rema] = ["has", "get", "set", "remove"]
+ .map(m => (n, ...args) => typeof ns === "string" ?
+ n[`${m}AttributeNS`](ns, ...args) : n[`${m}Attribute`](...args));
/*
- * Disabling attributes this way allows them to still be relatively
- * easily accessed in case they contain some useful data.
+ * Disabling attributes by prepending `-blocked' allows them to still be
+ * relatively easily accessed in case they contain some useful data.
*/
const construct_name = [attr];
- while (node.hasAttribute(construct_name.join("")))
+ while (hasa(node, construct_name.join("")))
construct_name.unshift(blocked_str);
while (construct_name.length > 1) {
construct_name.shift();
const name = construct_name.join("");
- node.setAttribute(`${blocked_str}-${name}`, node.getAttribute(name));
+ seta(node, `${blocked_str}-${name}`, geta(node, name));
}
-
- node.removeAttribute(attr);
}
function sanitize_meta(meta, policy)
{
- const http_equiv = meta.getAttribute("http-equiv");
- const value = meta.content;
+ const value = meta.content || "";
- if (!value || !is_csp_header_name(http_equiv, true))
+ if (!value || !is_csp_header_name(meta.httpEquiv || "", true))
return;
block_attribute(meta, "content");
-
- if (is_csp_header_name(http_equiv, false))
- meta.content = sanitize_csp_header({value}, policy).value;
}
+/*
+ * Used to disable <script> that has not yet been added to live DOM (doesn't
+ * work for those already added).
+ */
function sanitize_script(script)
{
- script.hachette_blocked_type = script.type;
+ script.hachette_blocked_type = script.getAttribute("type");
script.type = "text/plain";
}
@@ -201,102 +202,101 @@ function desanitize_script(script, policy)
{
script.setAttribute("type", script.hachette_blocked_type);
- if (script.hachette_blocked_type === undefined)
+ if (script.hachette_blocked_type === null)
script.removeAttribute("type");
delete script.hachette_blocked_type;
}
-function apply_hachette_csp_rules(doc, head, policy)
-{
- const meta = doc.createElement("meta");
- meta.setAttribute("http-equiv", "Content-Security-Policy");
- meta.setAttribute("content", csp_rule(policy.nonce));
- head.append(meta);
- /* CSP is already in effect, we can remove the <meta> now. */
- meta.remove();
-}
-
+const bad_url_reg = /^data:([^,;]*ml|unknown-content-type)/i;
function sanitize_urls(element)
{
- for (const attribute of [...element.attributes]) {
- if (/^(href|src|data)$/i.test(attribute.localName) &&
- /^data:([^,;]*ml|unknown-content-type)/i.test(attribute.value))
- block_attribute(element, attribute.localName);
- }
+ for (const attr of [...element.attributes || []]
+ .filter(attr => /^(href|src|data)$/i.test(attr.localName))
+ .filter(attr => bad_url_reg.test(attr.value)))
+ block_attribute(element, attr.localName, attr.namespaceURI);
}
function start_data_urls_sanitizing(doc)
{
doc.querySelectorAll("*[href], *[src], *[data]").forEach(sanitize_urls);
- const mutation_handler = m => m.addedNodes.forEach(sanitize_urls);
- const mo = new MutationObserver(ms => ms.forEach(mutation_handler));
- mo.observe(doc, {childList: true, subtree: true});
+ if (!doc.content_loaded) {
+ const mutation_handler = m => m.addedNodes.forEach(sanitize_urls);
+ const mo = new MutationObserver(ms => ms.forEach(mutation_handler));
+ mo.observe(doc, {childList: true, subtree: true});
+ wait_loaded(doc).then(() => mo.disconnect());
+ }
}
-function apply_intrinsics_sanitizing(root_element)
+/*
+ * Normally, we block scripts with CSP. However, Mozilla does optimizations that
+ * cause part of the DOM to be loaded when our content scripts get to run. Thus,
+ * before the CSP rules we inject (for non-HTTP pages) become effective, we need
+ * to somehow block the execution of `<script>'s and intrinsics that were
+ * already there.
+ */
+function mozilla_initial_block(doc)
{
- for (const subelem of root_element.querySelectorAll("*")) {
- [...subelem.attributes]
- .filter(a => /^on/i.test(a.localName))
- .filter(a => /^javascript:/i.test(a.value))
- .forEach(a => block_attribute(subelem, a.localName));
- }
+ const blocker = e => e.preventDefault();
+ doc.addEventListener("beforescriptexecute", blocker);
+ setTimeout(() => doc.removeEventListener("beforescriptexecute", blocker));
+
+ [...doc.all].flatMap(ele => [...ele.attributes].map(attr => [ele, attr]))
+ .map(([ele, attr]) => [ele, attr.localName])
+ .filter(([ele, attr]) => /^on/.test(attr) && ele.wrappedJSObject[attr])
+ .forEach(([ele, attr]) => ele.wrappedJSObject[attr] = null);
}
+/*
+ * Here we block all scripts of a document which might be either and
+ * HTMLDocument or an XMLDocument. Modifying an XML document might disrupt
+ * Mozilla's XML preview. This is an unfortunate thing we have to accept for
+ * now. XML documents *have to* be sanitized as well because they might
+ * contain `<script>' tags (or on* attributes) with namespace declared as
+ * "http://www.w3.org/1999/xhtml" or "http://www.w3.org/2000/svg" which allows
+ * javascript execution.
+ */
async function sanitize_document(doc, policy)
{
/*
* Blocking of scripts that are in the DOM from the beginning. Needed for
- * Mozilla, harmless on Chromium.
- * Note that at least in SVG documents the `src' attr on `<script>'s seems
- * to be ignored by Firefox, so we don't need to sanitize it.
+ * Mozilla.
*/
- for (const script of document.getElementsByTagName("script")) {
- const old_children = [...script.childNodes];
- script.innerHTML = "";
- setTimeout(() => old_children.forEach(c => script.append(c)), 0);
- }
+ if (is_mozilla)
+ mozilla_initial_block(doc);
/*
* Ensure our CSP rules are employed from the beginning. This CSP injection
* method is, when possible, going to be applied together with CSP rules
* injected using webRequest.
- * For non-HTML documents this is just a dummy operation of adding and
- * removing `head'.
+ * Using elements namespaced as HTML makes this CSP injection also work for
+ * non-HTML documents.
*/
- let added_head = doc.createElement("head");
- if (!doc.head)
- doc.documentElement.prepend(added_head);
-
- apply_hachette_csp_rules(doc, added_head, policy);
-
- /* Proceed with DOM in its initial state. */
- added_head.remove();
+ const html = new DOMParser().parseFromString(`<html><head><meta \
+http-equiv="Content-Security-Policy" content="${csp_rule(policy.nonce)}"\
+/></head><body>Loading...</body></html>`, "text/html").documentElement;
/*
- * <html> node gets hijacked now, to be re-attached after <head> is loaded
+ * Root node gets hijacked now, to be re-attached after <head> is loaded
* and sanitized.
*/
- const old_html = doc.documentElement;
- const new_html = doc.createElement("html");
- old_html.replaceWith(new_html);
+ const root = doc.documentElement;
+ root.replaceWith(html);
- await wait_for_head(doc, old_html);
-
- for (const meta of old_html.querySelectorAll("head meta"))
- sanitize_meta(meta, policy);
-
- for (const script of old_html.querySelectorAll("script"))
- sanitize_script(script, policy);
-
- if (!(doc instanceof HTMLDocument))
- apply_intrinsics_sanitizing(old_html);
+ /*
+ * For XML documents, we don't intend to inject payload, so we neither block
+ * document's CSP `<meta>' tags nor wait for `<head>' to be parsed.
+ */
+ if (document instanceof HTMLDocument) {
+ await wait_for_head(doc, root);
- new_html.replaceWith(old_html);
+ root.querySelectorAll("head meta")
+ .forEach(m => sanitize_meta(m, policy));
+ }
- for (const script of old_html.querySelectorAll("script"))
- desanitize_script(script, policy);
+ root.querySelectorAll("script").forEach(s => sanitize_script(s, policy));
+ html.replaceWith(root);
+ root.querySelectorAll("script").forEach(s => desanitize_script(s, policy));
start_data_urls_sanitizing(doc);
}
@@ -329,14 +329,15 @@ if (!is_privileged_url(document.URL)) {
}
if (!policy) {
- console.warn("Using fallback policy!");
+ console.debug("Using fallback policy!");
policy = {allow: false, nonce: gen_nonce()};
}
+ console.debug("current policy", policy);
+
const doc_ready = Promise.all([
- policy.allow ? Promise.resolve : sanitize_document(document, policy),
- new Promise(cb => document.addEventListener("DOMContentLoaded",
- cb, {once: true}))
+ policy.allow ? Promise.resolve() : sanitize_document(document, policy),
+ wait_loaded(document)
]);
handle_page_actions(policy.nonce, policy_received_callback, doc_ready);
diff --git a/content/page_actions.js b/content/page_actions.js
index 8057541..040b4ab 100644
--- a/content/page_actions.js
+++ b/content/page_actions.js
@@ -11,7 +11,7 @@
* IMPORT browser
* IMPORT report_script
* IMPORT report_settings
- * IMPORT report_content_type
+ * IMPORT report_document_type
* IMPORTS_END
*/
@@ -70,8 +70,8 @@ function handle_page_actions(script_nonce, policy_received_cb,
doc_ready_promise) {
policy_received_callback = policy_received_cb;
url = document.URL;
- is_html = /html/.test(document.contentType);
- report_content_type(document.contentType);
+ is_html = document instanceof HTMLDocument;
+ report_document_type(is_html);
doc_ready_promise.then(document_ready);
diff --git a/html/display-panel.js b/html/display-panel.js
index 7d801c9..623ff36 100644
--- a/html/display-panel.js
+++ b/html/display-panel.js
@@ -276,8 +276,8 @@ function handle_activity_report(message)
template.script_contents.textContent = data;
container_for_injected.appendChild(template.div);
}
- if (type === "content_type") {
- if (!/html/.test(data))
+ if (type === "is_html") {
+ if (!data)
content_type_cell.classList.remove("hide");
}
if (type === "repo_query_action") {