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util/jid.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 | 11056:0b0a42542456 |
child | 12190:3616128cd2e3 |
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-- Prosody IM -- Copyright (C) 2008-2010 Matthew Wild -- Copyright (C) 2008-2010 Waqas Hussain -- -- This project is MIT/X11 licensed. Please see the -- COPYING file in the source package for more information. -- local select = select; local match, sub = string.match, string.sub; local nodeprep = require "util.encodings".stringprep.nodeprep; local nameprep = require "util.encodings".stringprep.nameprep; local resourceprep = require "util.encodings".stringprep.resourceprep; local escapes = { [" "] = "\\20"; ['"'] = "\\22"; ["&"] = "\\26"; ["'"] = "\\27"; ["/"] = "\\2f"; [":"] = "\\3a"; ["<"] = "\\3c"; [">"] = "\\3e"; ["@"] = "\\40"; ["\\"] = "\\5c"; }; local unescapes = {}; local backslash_escapes = {}; for k,v in pairs(escapes) do unescapes[v] = k; backslash_escapes[v] = v:gsub("\\", escapes) end local _ENV = nil; -- luacheck: std none local function split(jid) if not jid then return; end local node, nodepos = match(jid, "^([^@/]+)@()"); local host, hostpos = match(jid, "^([^@/]+)()", nodepos); if node and not host then return nil, nil, nil; end local resource = match(jid, "^/(.+)$", hostpos); if (not host) or ((not resource) and #jid >= hostpos) then return nil, nil, nil; end return node, host, resource; end local function bare(jid) local node, host = split(jid); if node and host then return node.."@"..host; end return host; end local function prepped_split(jid, strict) local node, host, resource = split(jid); if host and host ~= "." then if sub(host, -1, -1) == "." then -- Strip empty root label host = sub(host, 1, -2); end host = nameprep(host, strict); if not host then return; end if node then node = nodeprep(node, strict); if not node then return; end end if resource then resource = resourceprep(resource, strict); if not resource then return; end end return node, host, resource; end end local function join(node, host, resource) if not host then return end if node and resource then return node.."@"..host.."/"..resource; elseif node then return node.."@"..host; elseif resource then return host.."/"..resource; end return host; end local function prep(jid, strict) local node, host, resource = prepped_split(jid, strict); return join(node, host, resource); end local function compare(jid, acl) -- compare jid to single acl rule -- TODO compare to table of rules? local jid_node, jid_host, jid_resource = split(jid); local acl_node, acl_host, acl_resource = split(acl); if ((acl_node ~= nil and acl_node == jid_node) or acl_node == nil) and ((acl_host ~= nil and acl_host == jid_host) or acl_host == nil) and ((acl_resource ~= nil and acl_resource == jid_resource) or acl_resource == nil) then return true end return false end local function node(jid) return (select(1, split(jid))); end local function host(jid) return (select(2, split(jid))); end local function resource(jid) return (select(3, split(jid))); end local function escape(s) return s and (s:gsub("\\%x%x", backslash_escapes):gsub("[\"&'/:<>@ ]", escapes)); end local function unescape(s) return s and (s:gsub("\\%x%x", unescapes)); end return { split = split; bare = bare; prepped_split = prepped_split; join = join; prep = prep; compare = compare; node = node; host = host; resource = resource; escape = escape; unescape = unescape; };