Software / code / prosody
File
tools/form2table.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 | 11194:9d1ce6f28401 |
| child | 13142:879a6a33c21b |
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-- Read an XML dataform and spit out a serialized Lua table of it local function from_stanza(stanza) local layout = { title = stanza:get_child_text("title"); instructions = stanza:get_child_text("instructions"); }; for tag in stanza:childtags("field") do local field = { name = tag.attr.var; type = tag.attr.type; label = tag.attr.label; desc = tag:get_child_text("desc"); required = tag:get_child("required") and true or nil; value = tag:get_child_text("value"); options = nil; }; if field.type == "list-single" or field.type == "list-multi" then local options = {}; for option in tag:childtags("option") do options[#options+1] = { label = option.attr.label, value = option:get_child_text("value") }; end field.options = options; end if field.type == "jid-multi" or field.type == "list-multi" or field.type == "text-multi" then local values = {}; for value in tag:childtags("value") do values[#values+1] = value:get_text(); end if field.type == "text-multi" then values = table.concat(values, "\n"); end field.value = values; end if field.type == "boolean" then field.value = field.value == "true" or field.value == "1"; end layout[#layout+1] = field; end return layout; end print("dataforms.new " .. require "util.serialization".serialize(from_stanza(require "util.xml".parse(io.read("*a"))), { unquoted = true }))