-- Prosody IM -- Copyright (C) 2010 Matthew Wild -- Copyright (C) 2010 Paul Aurich -- -- This project is MIT/X11 licensed. Please see the -- COPYING file in the source package for more information. -- -- TODO: I feel a fair amount of this logic should be integrated into Luasec, -- so that everyone isn't re-inventing the wheel. Dependencies on -- IDN libraries complicate that. -- [TLS-CERTS] - http://tools.ietf.org/html/rfc6125 -- [XMPP-CORE] - http://tools.ietf.org/html/rfc6120 -- [SRV-ID] - http://tools.ietf.org/html/rfc4985 -- [IDNA] - http://tools.ietf.org/html/rfc5890 -- [LDAP] - http://tools.ietf.org/html/rfc4519 -- [PKIX] - http://tools.ietf.org/html/rfc5280 local nameprep = require "util.encodings".stringprep.nameprep; local idna_to_ascii = require "util.encodings".idna.to_ascii; local idna_to_unicode = require "util.encodings".idna.to_unicode; local base64 = require "util.encodings".base64; local log = require "util.logger".init("x509"); local s_format = string.format; local _ENV = nil; -- luacheck: std none local oid_commonname = "2.5.4.3"; -- [LDAP] 2.3 local oid_subjectaltname = "2.5.29.17"; -- [PKIX] 4.2.1.6 local oid_xmppaddr = "1.3.6.1.5.5.7.8.5"; -- [XMPP-CORE] local oid_dnssrv = "1.3.6.1.5.5.7.8.7"; -- [SRV-ID] -- Compare a hostname (possibly international) with asserted names -- extracted from a certificate. -- This function follows the rules laid out in -- sections 6.4.1 and 6.4.2 of [TLS-CERTS] -- -- A wildcard ("*") all by itself is allowed only as the left-most label local function compare_dnsname(host, asserted_names) -- TODO: Sufficient normalization? Review relevant specs. local norm_host = idna_to_ascii(host) if norm_host == nil then log("info", "Host %s failed IDNA ToASCII operation", host) return false end norm_host = norm_host:lower() local host_chopped = norm_host:gsub("^[^.]+%.", "") -- everything after the first label for i=1,#asserted_names do local name = asserted_names[i] if norm_host == name:lower() then log("debug", "Cert dNSName %s matched hostname", name); return true end -- Allow the left most label to be a "*" if name:match("^%*%.") then local rest_name = name:gsub("^[^.]+%.", "") if host_chopped == rest_name:lower() then log("debug", "Cert dNSName %s matched hostname", name); return true end end end return false end -- Compare an XMPP domain name with the asserted id-on-xmppAddr -- identities extracted from a certificate. Both are UTF8 strings. -- -- Per [XMPP-CORE], matches against asserted identities don't include -- wildcards, so we just do a normalize on both and then a string comparison -- -- TODO: Support for full JIDs? local function compare_xmppaddr(host, asserted_names) local norm_host = nameprep(host) for i=1,#asserted_names do local name = asserted_names[i] -- We only want to match against bare domains right now, not -- those crazy full-er JIDs. if name:match("[@/]") then log("debug", "Ignoring xmppAddr %s because it's not a bare domain", name) else local norm_name = nameprep(name) if norm_name == nil then log("info", "Ignoring xmppAddr %s, failed nameprep!", name) else if norm_host == norm_name then log("debug", "Cert xmppAddr %s matched hostname", name) return true end end end end return false end -- Compare a host + service against the asserted id-on-dnsSRV (SRV-ID) -- identities extracted from a certificate. -- -- Per [SRV-ID], the asserted identities will be encoded in ASCII via ToASCII. -- Comparison is done case-insensitively, and a wildcard ("*") all by itself -- is allowed only as the left-most non-service label. local function compare_srvname(host, service, asserted_names) local norm_host = idna_to_ascii(host) if norm_host == nil then log("info", "Host %s failed IDNA ToASCII operation", host); return false end -- Service names start with a "_" if service:match("^_") == nil then service = "_"..service end norm_host = norm_host:lower(); local host_chopped = norm_host:gsub("^[^.]+%.", "") -- everything after the first label for i=1,#asserted_names do local asserted_service, name = asserted_names[i]:match("^(_[^.]+)%.(.*)"); if service == asserted_service then if norm_host == name:lower() then log("debug", "Cert SRVName %s matched hostname", name); return true; end -- Allow the left most label to be a "*" if name:match("^%*%.") then local rest_name = name:gsub("^[^.]+%.", "") if host_chopped == rest_name:lower() then log("debug", "Cert SRVName %s matched hostname", name) return true end end if norm_host == name:lower() then log("debug", "Cert SRVName %s matched hostname", name); return true end end end return false end local function verify_identity(host, service, cert) if cert.setencode then cert:setencode("utf8"); end local ext = cert:extensions() if ext[oid_subjectaltname] then local sans = ext[oid_subjectaltname]; -- Per [TLS-CERTS] 6.3, 6.4.4, "a client MUST NOT seek a match for a -- reference identifier if the presented identifiers include a DNS-ID -- SRV-ID, URI-ID, or any application-specific identifier types" local had_supported_altnames = false if sans[oid_xmppaddr] then had_supported_altnames = true if service == "_xmpp-client" or service == "_xmpp-server" then if compare_xmppaddr(host, sans[oid_xmppaddr]) then return true end end end if sans[oid_dnssrv] then had_supported_altnames = true -- Only check srvNames if the caller specified a service if service and compare_srvname(host, service, sans[oid_dnssrv]) then return true end end if sans["dNSName"] then had_supported_altnames = true if compare_dnsname(host, sans["dNSName"]) then return true end end -- We don't need URIs, but [TLS-CERTS] is clear. if sans["uniformResourceIdentifier"] then had_supported_altnames = true end if had_supported_altnames then return false end end -- Extract a common name from the certificate, and check it as if it were -- a dNSName subjectAltName (wildcards may apply for, and receive, -- cat treats) -- -- Per [TLS-CERTS] 1.8, a CN-ID is the Common Name from a cert subject -- which has one and only one Common Name local subject = cert:subject() local cn = nil for i=1,#subject do local dn = subject[i] if dn["oid"] == oid_commonname then if cn then log("info", "Certificate has multiple common names") return false end cn = dn["value"]; end end if cn then -- Per [TLS-CERTS] 6.4.4, follow the comparison rules for dNSName SANs. return compare_dnsname(host, { cn }) end -- If all else fails, well, why should we be any different? return false end -- TODO Support other SANs local function get_identities(cert) --> set of names if cert.setencode then cert:setencode("utf8"); end local names = {}; local ext = cert:extensions(); local sans = ext[oid_subjectaltname]; if sans and sans["dNSName"] then for i = 1, #sans["dNSName"] do names[ idna_to_unicode(sans["dNSName"][i]) ] = true; end end local subject = cert:subject(); for i = 1, #subject do local dn = subject[i]; if dn.oid == oid_commonname then local name = nameprep(dn.value); if name and idna_to_ascii(name) then names[name] = true; end end end return names; end local pat = "%-%-%-%-%-BEGIN ([A-Z ]+)%-%-%-%-%-\r?\n".. "([0-9A-Za-z+/=\r\n]*)\r?\n%-%-%-%-%-END %1%-%-%-%-%-"; local function pem2der(pem) local typ, data = pem:match(pat); if typ and data then return base64.decode(data), typ; end end local wrap = ('.'):rep(64); local envelope = "-----BEGIN %s-----\n%s\n-----END %s-----\n" local function der2pem(data, typ) typ = typ and typ:upper() or "CERTIFICATE"; data = base64.encode(data); return s_format(envelope, typ, data:gsub(wrap, '%0\n', (#data-1)/64), typ); end return { verify_identity = verify_identity; get_identities = get_identities; pem2der = pem2der; der2pem = der2pem; };