--- a/util/certverification.lua Tue Dec 14 18:54:55 2010 +0100
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,211 +0,0 @@
--- 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/draft-saintandre-tls-server-id-check-10
--- [XMPP-CORE] - http://tools.ietf.org/html/draft-ietf-xmpp-3920bis-18
--- [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 log = require "util.logger".init("certverification");
-
-module "certverification"
-
-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 4.4.1 and 4.4.2 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
-
-function verify_identity(host, service, cert)
- local ext = cert:extensions()
- if ext[oid_subjectaltname] then
- local sans = ext[oid_subjectaltname];
-
- -- Per [TLS-CERTS] 4.3, 4.4.4, "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 compare_xmppaddr(host, sans[oid_xmppaddr]) then return true 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] 1.5, 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] 4.4.4, 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
-
-return _M;