File

spec/util_xml_spec.lua @ 12180:53e0ae770917

util.xml: Do not allow doctypes, comments or processing instructions Yes. This is as bad as it sounds. CVE pending. In Prosody itself, this only affects mod_websocket, which uses util.xml to parse the <open/> frame, thus allowing unauthenticated remote DoS using Billion Laughs. However, third-party modules using util.xml may also be affected by this. This commit installs handlers which disallow the use of doctype declarations and processing instructions without any escape hatch. It, by default, also introduces such a handler for comments, however, there is a way to enable comments nontheless. This is because util.xml is used to parse human-facing data, where comments are generally a desirable feature, and also because comments are generally harmless.
author Jonas Schäfer <jonas@wielicki.name>
date Mon, 10 Jan 2022 18:23:54 +0100
parent 8236:4878e4159e12
child 12270:c78639ee6ccb
line wrap: on
line source


local xml = require "util.xml";

describe("util.xml", function()
	describe("#parse()", function()
		it("should work", function()
			local x =
[[<x xmlns:a="b">
	<y xmlns:a="c"> <!-- this overwrites 'a' -->
	    <a:z/>
	</y>
	<a:z/> <!-- prefix 'a' is nil here, but should be 'b' -->
</x>
]]
			local stanza = xml.parse(x, {allow_comments = true});
			assert.are.equal(stanza.tags[2].attr.xmlns, "b");
			assert.are.equal(stanza.tags[2].namespaces["a"], "b");
		end);

		it("should reject doctypes", function()
			local x = "<!DOCTYPE foo []><foo/>";
			local ok = xml.parse(x);
			assert.falsy(ok);
		end);

		it("should reject comments by default", function()
			local x = "<foo><!-- foo --></foo>";
			local ok = xml.parse(x);
			assert.falsy(ok);
		end);

		it("should allow comments if asked nicely", function()
			local x = "<foo><!-- foo --></foo>";
			local stanza = xml.parse(x, {allow_comments = true});
			assert.are.equal(stanza.name, "foo");
			assert.are.equal(#stanza, 0);
		end);

		it("should reject processing instructions", function()
			local x = "<foo><?php die(); ?></foo>";
			local ok = xml.parse(x);
			assert.falsy(ok);
		end);

		it("should allow an xml declaration", function()
			local x = "<?xml version='1.0'?><foo/>";
			local stanza = xml.parse(x);
			assert.truthy(stanza);
			assert.are.equal(stanza.name, "foo");
		end);
	end);
end);