implement smuggling via cookies instead of URL

1 files changed, 65 insertions, 125 deletions

diff --git a/background/policy_injector.js b/background/policy_injector.js
index 9725e99..947812e 100644
--- a/background/policy_injector.js
+++ b/background/policy_injector.js
@@ -8,19 +8,16 @@
 
 /*
  * IMPORTS_START
- * IMPORT TYPE_PREFIX
  * IMPORT get_storage
  * IMPORT browser
  * IMPORT is_chrome
- * IMPORT is_mozilla
- * IMPORT gen_unique
  * IMPORT gen_nonce
  * IMPORT is_privileged_url
- * IMPORT url_item
- * IMPORT url_extract_target
- * IMPORT sign_policy
+ * IMPORT sign_data
+ * IMPORT extract_signed
  * IMPORT query_best
  * IMPORT sanitize_csp_header
+ * IMPORT csp_rule
  * IMPORTS_END
  */
 
@@ -32,129 +29,81 @@ const csp_header_names = new Set([
     "x-content-security-policy"
 ]);
 
-/* TODO: variable no longer in use; remove if not needed */
-const unwanted_csp_directives = new Set([
-    "report-to",
-    "report-uri",
-    "script-src",
-    "script-src-elem",
-    "prefetch-src"
-]);
-
 const report_only = "content-security-policy-report-only";
 
-function url_inject(details)
+function headers_inject(details)
 {
-    if (is_privileged_url(details.url))
+    console.log("ijnector details", details);
+    const url = details.url;
+    if (is_privileged_url(url))
 	return;
 
-    const targets = url_extract_target(details.url);
-    if (targets.current)
-	return;
+    const [pattern, settings] = query_best(storage, url);
+    const allow = !!(settings && settings.allow);
+    const nonce = gen_nonce();
+    const rule = `'nonce-${nonce}'`;
 
-    /* Redirect; update policy */
-    if (targets.policy)
-	targets.target = "";
-
-    let [pattern, settings] = query_best(storage, targets.base_url);
-    /* Defaults */
-    if (!pattern)
-	settings = {};
-
-    const policy = encodeURIComponent(
-	JSON.stringify({
-	    allow: settings.allow,
-	    nonce: gen_nonce(),
-	    base_url: targets.base_url
-	})
-    );
+    let orig_csp_headers;
+    let old_signature;
+    let hachette_header;
+    let headers = details.responseHeaders;
 
-    return {
-	redirectUrl: [
-	    targets.base_url,
-	    '#', sign_policy(policy, new Date()), policy,
-	    targets.target,
-	    targets.target2
-	].join("")
-    };
-}
+    for (const header of headers.filter(h => h.name === "x-hachette")) {
+	const match = /^([^%])(%.*)$/.exec(header.value);
+	if (!match)
+	    continue;
 
-function headers_inject(details)
-{
-    const targets = url_extract_target(details.url);
-    /* Block mis-/unsigned requests */
-    if (!targets.current)
-	return {cancel: true};
-
-    let orig_csp_headers = is_chrome ? null : [];
-    let headers = [];
-    let csp_headers = is_chrome ? headers : [];
-
-    const rule = `'nonce-${targets.policy.nonce}'`;
-    const block = !targets.policy.allow;
-
-    for (const header of details.responseHeaders) {
-	if (!csp_header_names.has(header)) {
-	    /* Remove headers that only snitch on us */
-	    if (header.name.toLowerCase() === report_only && block)
-		continue;
-	    headers.push(header);
-
-	    /* If these are the original CSP headers, use them instead */
-	    /* Test based on url_extract_target() in misc.js */
-	    if (is_mozilla && header.name === "x-orig-csp") {
-		let index = header.value.indexOf('%5B');
-		if (index === -1)
-		    continue;
-
-		let sig = header.value.substring(0, index);
-		let data = header.value.substring(index);
-		if (sig !== sign_policy(data, 0))
-		    continue;
-
-		/* Confirmed- it's the originals, smuggled in! */
-		try {
-		    data = JSON.parse(decodeURIComponent(data));
-		} catch (e) {
-		    /* This should not be reached -
-			it's our self-produced valid JSON. */
-		    console.log("Unexpected internal error - invalid JSON smuggled!", e);
-		}
-
-		orig_csp_headers = csp_headers = null;
-		for (const header of data)
-		    headers.push(sanitize_csp_header(header, rule, block));
-	    }
-	} else if (is_chrome || !orig_csp_headers) {
-	    csp_headers.push(sanitize_csp_header(header, rule, block));
-	    if (is_mozilla)
-		orig_csp_headers.push(header);
-	}
+	const old_data = extract_signed(...match.splice(1, 2), [[0]]);
+	if (!old_data || old_data.url !== url)
+	    continue;
+
+	/* Confirmed- it's the originals, smuggled in! */
+	orig_csp_headers = old_data.csp_headers;
+	old_signature = old_data.policy_signature;
+
+	hachette_header = header;
+	break;
     }
 
-    if (orig_csp_headers) {
-	/** Smuggle in the original CSP headers for future use.
-	  * These are signed with a time of 0, as it's not clear there
-	  * is a limit on how long Firefox might retain these headers in
-	  * the cache.
-	  */
-	orig_csp_headers = encodeURIComponent(JSON.stringify(orig_csp_headers));
-	headers.push({
-	    name: "x-orig-csp",
-	    value: sign_policy(orig_csp_headers, 0) + orig_csp_headers
-	});
-
-	headers = headers.concat(csp_headers);
+    if (!hachette_header) {
+	hachette_header = {name: "x-hachette"};
+	headers.push(hachette_header);
     }
 
+    orig_csp_headers ||=
+	headers.filter(h => csp_header_names.has(h.name.toLowerCase()));
+    headers = headers.filter(h => !csp_header_names.has(h.name.toLowerCase()));
+
+    /* Remove headers that only snitch on us */
+    if (!allow)
+	headers = headers.filter(h => h.name.toLowerCase() !== report_only);
+
+    if (old_signature)
+	headers = headers.filter(h => h.name.search(old_signature) === -1);
+
+    const sanitizer = h => sanitize_csp_header(h, rule, allow);
+    headers.push(...orig_csp_headers.map(sanitizer));
+
+    const policy = encodeURIComponent(JSON.stringify({allow, nonce, url}));
+    const policy_signature = sign_data(policy, new Date());
+    const later_30sec = new Date(new Date().getTime() + 30000).toGMTString();
+    headers.push({
+	name: "Set-Cookie",
+	value: `hachette-${policy_signature}=${policy}; Expires=${later_30sec};`
+    });
+
+    /*
+     * Smuggle in the signature and the original CSP headers for future use.
+     * These are signed with a time of 0, as it's not clear there is a limit on
+     * how long Firefox might retain headers in the cache.
+     */
+    let hachette_data = {csp_headers: orig_csp_headers, policy_signature, url};
+    hachette_data = encodeURIComponent(JSON.stringify(hachette_data));
+    hachette_header.value = sign_data(hachette_data, 0) + hachette_data;
+
     /* To ensure there is a CSP header if required */
-    if (block) {
-	headers.push({
-	    name: "content-security-policy",
-	    value: `script-src ${rule}; script-src-elem ${rule}; ` +
-		"script-src-attr 'none'; prefetch-src 'none';"
-	});
-    }
+    if (!allow)
+	headers.push({name: "content-security-policy", value: csp_rule(nonce)});
 
     return {responseHeaders: headers};
 }
@@ -167,15 +116,6 @@ async function start_policy_injector()
     if (is_chrome)
 	extra_opts.push("extraHeaders");
 
-    browser.webRequest.onBeforeRequest.addListener(
-	url_inject,
-	{
-	    urls: ["<all_urls>"],
-	    types: ["main_frame", "sub_frame"]
-	},
-	["blocking"]
-    );
-
     browser.webRequest.onHeadersReceived.addListener(
 	headers_inject,
 	{