Software / code / prosody
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util/dependencies.lua @ 13801:a5d5fefb8b68 13.0
mod_tls: Enable Prosody's certificate checking for incoming s2s connections (fixes #1916) (thanks Damian, Zash)
Various options in Prosody allow control over the behaviour of the certificate
verification process For example, some deployments choose to allow falling
back to traditional "dialback" authentication (XEP-0220), while others verify
via DANE, hard-coded fingerprints, or other custom plugins.
Implementing this flexibility requires us to override OpenSSL's default
certificate verification, to allow Prosody to verify the certificate itself,
apply custom policies and make decisions based on the outcome.
To enable our custom logic, we have to suppress OpenSSL's default behaviour of
aborting the connection with a TLS alert message. With LuaSec, this can be
achieved by using the verifyext "lsec_continue" flag.
We also need to use the lsec_ignore_purpose flag, because XMPP s2s uses server
certificates as "client" certificates (for mutual TLS verification in outgoing
s2s connections).
Commit 99d2100d2918 moved these settings out of the defaults and into mod_s2s,
because we only really need these changes for s2s, and they should be opt-in,
rather than automatically applied to all TLS services we offer.
That commit was incomplete, because it only added the flags for incoming
direct TLS connections. StartTLS connections are handled by mod_tls, which was
not applying the lsec_* flags. It previously worked because they were already
in the defaults.
This resulted in incoming s2s connections with "invalid" certificates being
aborted early by OpenSSL, even if settings such as `s2s_secure_auth = false`
or DANE were present in the config.
Outgoing s2s connections inherit verify "none" from the defaults, which means
OpenSSL will receive the cert but will not terminate the connection when it is
deemed invalid. This means we don't need lsec_continue there, and we also
don't need lsec_ignore_purpose (because the remote peer is a "server").
Wondering why we can't just use verify "none" for incoming s2s? It's because
in that mode, OpenSSL won't request a certificate from the peer for incoming
connections. Setting verify "peer" is how you ask OpenSSL to request a
certificate from the client, but also what triggers its built-in verification.
| author | Matthew Wild <mwild1@gmail.com> |
|---|---|
| date | Tue, 01 Apr 2025 17:26:56 +0100 |
| parent | 13114:025c38ee885d |
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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 function softreq(...) local ok, lib = pcall(require, ...); if ok then return lib; else return nil, lib; end end -- Required to be able to find packages installed with luarocks if not softreq "luarocks.loader" then -- LuaRocks 2.x softreq "luarocks.require"; -- LuaRocks <1.x end local function missingdep(name, sources, msg, err) -- luacheck: ignore err -- TODO print something about the underlying error, useful for debugging print(""); print("**************************"); print("Prosody was unable to find "..tostring(name)); print("This package can be obtained in the following ways:"); print(""); for _, row in ipairs(sources) do print(string.format("%15s | %s", table.unpack(row))); end print(""); print(msg or (name.." is required for Prosody to run, so we will now exit.")); print("More help can be found on our website, at https://prosody.im/doc/depends"); print("**************************"); print(""); end local function check_dependencies() if _VERSION < "Lua 5.2" then print "***********************************" print("Unsupported Lua version: ".._VERSION); print("At least Lua 5.2 is required."); print "***********************************" return false; end local fatal; local lxp, err = softreq "lxp" if not lxp then missingdep("luaexpat", { { "Debian/Ubuntu", "sudo apt install lua-expat" }; { "luarocks", "luarocks install luaexpat" }; { "Source", "http://matthewwild.co.uk/projects/luaexpat/" }; }, nil, err); fatal = true; end local socket, err = softreq "socket" if not socket then missingdep("luasocket", { { "Debian/Ubuntu", "sudo apt install lua-socket" }; { "luarocks", "luarocks install luasocket" }; { "Source", "http://www.tecgraf.puc-rio.br/~diego/professional/luasocket/" }; }, nil, err); fatal = true; elseif not socket.tcp4 then -- COMPAT LuaSocket before being IP-version agnostic socket.tcp4 = socket.tcp; socket.udp4 = socket.udp; end local lfs, err = softreq "lfs" if not lfs then missingdep("luafilesystem", { { "luarocks", "luarocks install luafilesystem" }; { "Debian/Ubuntu", "sudo apt install lua-filesystem" }; { "Source", "http://www.keplerproject.org/luafilesystem/" }; }, nil, err); fatal = true; end local ssl, err = softreq "ssl" if not ssl then missingdep("LuaSec", { { "Debian/Ubuntu", "sudo apt install lua-sec" }; { "luarocks", "luarocks install luasec" }; { "Source", "https://github.com/brunoos/luasec" }; }, nil, err); end local bit, err = softreq"prosody.util.bitcompat"; if not bit then missingdep("lua-bitops", { { "Debian/Ubuntu", "sudo apt install lua-bitop" }; { "luarocks", "luarocks install luabitop" }; { "Source", "http://bitop.luajit.org/" }; }, "WebSocket support will not be available", err); end local unbound, err = softreq"lunbound"; -- luacheck: ignore 211/err if not unbound then missingdep("lua-unbound", { { "Debian/Ubuntu", "sudo apt install lua-unbound" }; { "luarocks", "luarocks install luaunbound" }; { "Source", "https://www.zash.se/luaunbound.html" }; }, "Old DNS resolver library will be used", err); else package.preload["prosody.net.adns"] = function () local ub = require "prosody.net.unbound"; return ub; end end local encodings, err = softreq "prosody.util.encodings" if not encodings then if err:match("module '[^']*' not found") then missingdep("prosody.util.encodings", { { "Windows", "Make sure you have encodings.dll from the Prosody distribution in util/" }; { "GNU/Linux", "Run './configure' and 'make' in the Prosody source directory to build util/encodings.so" }; }); else print "***********************************" print("util/encodings couldn't be loaded. Check that you have a recent version of libidn"); print "" print("The full error was:"); print(err) print "***********************************" end fatal = true; end local hashes, err = softreq "prosody.util.hashes" if not hashes then if err:match("module '[^']*' not found") then missingdep("prosody.util.hashes", { { "Windows", "Make sure you have hashes.dll from the Prosody distribution in util/" }; { "GNU/Linux", "Run './configure' and 'make' in the Prosody source directory to build util/hashes.so" }; }); else print "***********************************" print("util/hashes couldn't be loaded. Check that you have a recent version of OpenSSL (libcrypto in particular)"); print "" print("The full error was:"); print(err) print "***********************************" end fatal = true; end return not fatal; end local function log_warnings() if _VERSION > "Lua 5.4" then prosody.log("warn", "Support for %s is experimental, please report any issues", _VERSION); elseif _VERSION < "Lua 5.2" then prosody.log("warn", "%s support is deprecated, upgrade as soon as possible", _VERSION); end local ssl = softreq"ssl"; if ssl then local major, minor, veryminor, patched = ssl._VERSION:match("(%d+)%.(%d+)%.?(%d*)(M?)"); if not major or ((tonumber(major) == 0 and (tonumber(minor) or 0) <= 3 and (tonumber(veryminor) or 0) <= 2) and patched ~= "M") then prosody.log("error", "This version of LuaSec contains a known bug that causes disconnects, see https://prosody.im/doc/depends"); end end local lxp = softreq"lxp"; if lxp then if not pcall(lxp.new, { StartDoctypeDecl = false }) then prosody.log("error", "The version of LuaExpat on your system leaves Prosody " .."vulnerable to denial-of-service attacks. You should upgrade to " .."LuaExpat 1.3.0 or higher as soon as possible. See " .."https://prosody.im/doc/depends#luaexpat for more information."); end if not lxp.new({}).getcurrentbytecount then prosody.log("error", "The version of LuaExpat on your system does not support " .."stanza size limits, which may leave servers on untrusted " .."networks (e.g. the internet) vulnerable to denial-of-service " .."attacks. You should upgrade to LuaExpat 1.3.0 or higher as " .."soon as possible. See " .."https://prosody.im/doc/depends#luaexpat for more information."); end end end return { softreq = softreq; missingdep = missingdep; check_dependencies = check_dependencies; log_warnings = log_warnings; };