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.
local config = require "core.configmanager";
local certmanager = require "core.certmanager";
local server = require "net.server";
local socket = require "socket";
local log = require "util.logger".init("portmanager");
local multitable = require "util.multitable";
local set = require "util.set";
local table = table;
local setmetatable, rawset, rawget = setmetatable, rawset, rawget;
local type, tonumber, tostring, ipairs = type, tonumber, tostring, ipairs;
local prosody = prosody;
local fire_event = prosody.events.fire_event;
local _ENV = nil;
-- luacheck: std none
--- Config
local default_interfaces = { };
local default_local_interfaces = { };
if config.get("*", "use_ipv4") ~= false then
table.insert(default_interfaces, "*");
table.insert(default_local_interfaces, "127.0.0.1");
end
if socket.tcp6 and config.get("*", "use_ipv6") ~= false then
table.insert(default_interfaces, "::");
table.insert(default_local_interfaces, "::1");
end
local default_mode = config.get("*", "network_default_read_size") or 4096;
--- Private state
-- service_name -> { service_info, ... }
local services = setmetatable({}, { __index = function (t, k) rawset(t, k, {}); return rawget(t, k); end });
-- service_name, interface (string), port (number)
local active_services = multitable.new();
--- Private helpers
local function error_to_friendly_message(service_name, port, err) --luacheck: ignore 212/service_name
local friendly_message = err;
if err:match(" in use") then
-- FIXME: Use service_name here
if port == 5222 or port == 5223 or port == 5269 then
friendly_message = "check that Prosody or another XMPP server is "
.."not already running and using this port";
elseif port == 80 or port == 81 then
friendly_message = "check that a HTTP server is not already using "
.."this port";
elseif port == 5280 then
friendly_message = "check that Prosody or a BOSH connection manager "
.."is not already running";
else
friendly_message = "this port is in use by another application";
end
elseif err:match("permission") then
friendly_message = "Prosody does not have sufficient privileges to use this port";
end
return friendly_message;
end
--- Public API
local function activate(service_name)
local service_info = services[service_name][1];
if not service_info then
return nil, "Unknown service: "..service_name;
end
local listener = service_info.listener;
local config_prefix = (service_info.config_prefix or service_name).."_";
if config_prefix == "_" then
config_prefix = "";
end
local bind_interfaces = config.get("*", config_prefix.."interfaces")
or config.get("*", config_prefix.."interface") -- COMPAT w/pre-0.9
or (service_info.private and (config.get("*", "local_interfaces") or default_local_interfaces))
or config.get("*", "interfaces")
or config.get("*", "interface") -- COMPAT w/pre-0.9
or listener.default_interface -- COMPAT w/pre0.9
or default_interfaces
bind_interfaces = set.new(type(bind_interfaces)~="table" and {bind_interfaces} or bind_interfaces);
local bind_ports = config.get("*", config_prefix.."ports")
or service_info.default_ports
or {service_info.default_port
or listener.default_port -- COMPAT w/pre-0.9
}
bind_ports = set.new(type(bind_ports) ~= "table" and { bind_ports } or bind_ports );
local mode, ssl = listener.default_mode or default_mode;
local hooked_ports = {};
for interface in bind_interfaces do
for port in bind_ports do
local port_number = tonumber(port);
if not port_number then
log("error", "Invalid port number specified for service '%s': %s", service_info.name, tostring(port));
elseif #active_services:search(nil, interface, port_number) > 0 then
log("error", "Multiple services configured to listen on the same port ([%s]:%d): %s, %s", interface, port,
active_services:search(nil, interface, port)[1][1].service.name or "<unnamed>", service_name or "<unnamed>");
else
local err;
-- Create SSL context for this service/port
if service_info.encryption == "ssl" then
local global_ssl_config = config.get("*", "ssl") or {};
local prefix_ssl_config = config.get("*", config_prefix.."ssl") or global_ssl_config;
log("debug", "Creating context for direct TLS service %s on port %d", service_info.name, port);
ssl, err = certmanager.create_context(service_info.name.." port "..port, "server",
prefix_ssl_config[interface],
prefix_ssl_config[port],
prefix_ssl_config,
service_info.ssl_config or {},
global_ssl_config[interface],
global_ssl_config[port]);
if not ssl then
log("error", "Error binding encrypted port for %s: %s", service_info.name,
error_to_friendly_message(service_name, port_number, err) or "unknown error");
end
end
if not err then
-- Start listening on interface+port
local handler, err = server.addserver(interface, port_number, listener, mode, ssl);
if not handler then
log("error", "Failed to open server port %d on %s, %s", port_number, interface,
error_to_friendly_message(service_name, port_number, err));
else
table.insert(hooked_ports, "["..interface.."]:"..port_number);
log("debug", "Added listening service %s to [%s]:%d", service_name, interface, port_number);
active_services:add(service_name, interface, port_number, {
server = handler;
service = service_info;
});
end
end
end
end
end
log("info", "Activated service '%s' on %s", service_name,
#hooked_ports == 0 and "no ports" or table.concat(hooked_ports, ", "));
return true;
end
local close; -- forward declaration
local function deactivate(service_name, service_info)
for name, interface, port, n, active_service --luacheck: ignore 213/name 213/n
in active_services:iter(service_name or service_info and service_info.name, nil, nil, nil) do
if service_info == nil or active_service.service == service_info then
close(interface, port);
end
end
log("info", "Deactivated service '%s'", service_name or service_info.name);
end
local function register_service(service_name, service_info)
table.insert(services[service_name], service_info);
if not active_services:get(service_name) then
log("debug", "No active service for %s, activating...", service_name);
local ok, err = activate(service_name);
if not ok then
log("error", "Failed to activate service '%s': %s", service_name, err or "unknown error");
end
end
fire_event("service-added", { name = service_name, service = service_info });
return true;
end
local function unregister_service(service_name, service_info)
log("debug", "Unregistering service: %s", service_name);
local service_info_list = services[service_name];
for i, service in ipairs(service_info_list) do
if service == service_info then
table.remove(service_info_list, i);
end
end
deactivate(nil, service_info);
if #service_info_list > 0 then -- Other services registered with this name
activate(service_name); -- Re-activate with the next available one
end
fire_event("service-removed", { name = service_name, service = service_info });
end
local get_service_at -- forward declaration
function close(interface, port)
local service, service_server = get_service_at(interface, port);
if not service then
return false, "port-not-open";
end
service_server:close();
active_services:remove(service.name, interface, port);
log("debug", "Removed listening service %s from [%s]:%d", service.name, interface, port);
return true;
end
function get_service_at(interface, port)
local data = active_services:search(nil, interface, port)[1][1];
return data.service, data.server;
end
local function get_service(service_name)
return (services[service_name] or {})[1];
end
local function get_active_services()
return active_services;
end
local function get_registered_services()
return services;
end
-- Event handlers
prosody.events.add_handler("item-added/net-provider", function (event)
local item = event.item;
register_service(item.name, item);
end);
prosody.events.add_handler("item-removed/net-provider", function (event)
local item = event.item;
unregister_service(item.name, item);
end);
return {
activate = activate;
deactivate = deactivate;
register_service = register_service;
unregister_service = unregister_service;
close = close;
get_service_at = get_service_at;
get_service = get_service;
get_active_services = get_active_services;
get_registered_services = get_registered_services;
};