2 -- Copyright (C) 2010 Matthew Wild
3 -- Copyright (C) 2010 Paul Aurich
5 -- This project is MIT/X11 licensed. Please see the
6 -- COPYING file in the source package for more information.
9 -- TODO: I feel a fair amount of this logic should be integrated into Luasec,
10 -- so that everyone isn't re-inventing the wheel. Dependencies on
11 -- IDN libraries complicate that.
14 -- [TLS-CERTS] - http://tools.ietf.org/html/rfc6125
15 -- [XMPP-CORE] - http://tools.ietf.org/html/rfc6120
16 -- [SRV-ID] - http://tools.ietf.org/html/rfc4985
17 -- [IDNA] - http://tools.ietf.org/html/rfc5890
18 -- [LDAP] - http://tools.ietf.org/html/rfc4519
19 -- [PKIX] - http://tools.ietf.org/html/rfc5280
21 local nameprep = require "util.encodings".stringprep.nameprep;
22 local idna_to_ascii = require "util.encodings".idna.to_ascii;
23 local base64 = require "util.encodings".base64;
24 local log = require "util.logger".init("x509");
25 local pairs, ipairs = pairs, ipairs;
26 local s_format = string.format;
27 local t_insert = table.insert;
28 local t_concat = table.concat;
32 local oid_commonname = "2.5.4.3"; -- [LDAP] 2.3
33 local oid_subjectaltname = "2.5.29.17"; -- [PKIX] 4.2.1.6
34 local oid_xmppaddr = "1.3.6.1.5.5.7.8.5"; -- [XMPP-CORE]
35 local oid_dnssrv = "1.3.6.1.5.5.7.8.7"; -- [SRV-ID]
37 -- Compare a hostname (possibly international) with asserted names
38 -- extracted from a certificate.
39 -- This function follows the rules laid out in
40 -- sections 6.4.1 and 6.4.2 of [TLS-CERTS]
42 -- A wildcard ("*") all by itself is allowed only as the left-most label
43 local function compare_dnsname(host, asserted_names)
44 -- TODO: Sufficient normalization? Review relevant specs.
45 local norm_host = idna_to_ascii(host)
46 if norm_host == nil then
47 log("info", "Host %s failed IDNA ToASCII operation", host)
51 norm_host = norm_host:lower()
53 local host_chopped = norm_host:gsub("^[^.]+%.", "") -- everything after the first label
55 for i=1,#asserted_names do
56 local name = asserted_names[i]
57 if norm_host == name:lower() then
58 log("debug", "Cert dNSName %s matched hostname", name);
62 -- Allow the left most label to be a "*"
63 if name:match("^%*%.") then
64 local rest_name = name:gsub("^[^.]+%.", "")
65 if host_chopped == rest_name:lower() then
66 log("debug", "Cert dNSName %s matched hostname", name);
75 -- Compare an XMPP domain name with the asserted id-on-xmppAddr
76 -- identities extracted from a certificate. Both are UTF8 strings.
78 -- Per [XMPP-CORE], matches against asserted identities don't include
79 -- wildcards, so we just do a normalize on both and then a string comparison
81 -- TODO: Support for full JIDs?
82 local function compare_xmppaddr(host, asserted_names)
83 local norm_host = nameprep(host)
85 for i=1,#asserted_names do
86 local name = asserted_names[i]
88 -- We only want to match against bare domains right now, not
89 -- those crazy full-er JIDs.
90 if name:match("[@/]") then
91 log("debug", "Ignoring xmppAddr %s because it's not a bare domain", name)
93 local norm_name = nameprep(name)
94 if norm_name == nil then
95 log("info", "Ignoring xmppAddr %s, failed nameprep!", name)
97 if norm_host == norm_name then
98 log("debug", "Cert xmppAddr %s matched hostname", name)
108 -- Compare a host + service against the asserted id-on-dnsSRV (SRV-ID)
109 -- identities extracted from a certificate.
111 -- Per [SRV-ID], the asserted identities will be encoded in ASCII via ToASCII.
112 -- Comparison is done case-insensitively, and a wildcard ("*") all by itself
113 -- is allowed only as the left-most non-service label.
114 local function compare_srvname(host, service, asserted_names)
115 local norm_host = idna_to_ascii(host)
116 if norm_host == nil then
117 log("info", "Host %s failed IDNA ToASCII operation", host);
121 -- Service names start with a "_"
122 if service:match("^_") == nil then service = "_"..service end
124 norm_host = norm_host:lower();
125 local host_chopped = norm_host:gsub("^[^.]+%.", "") -- everything after the first label
127 for i=1,#asserted_names do
128 local asserted_service, name = asserted_names[i]:match("^(_[^.]+)%.(.*)");
129 if service == asserted_service then
130 if norm_host == name:lower() then
131 log("debug", "Cert SRVName %s matched hostname", name);
135 -- Allow the left most label to be a "*"
136 if name:match("^%*%.") then
137 local rest_name = name:gsub("^[^.]+%.", "")
138 if host_chopped == rest_name:lower() then
139 log("debug", "Cert SRVName %s matched hostname", name)
143 if norm_host == name:lower() then
144 log("debug", "Cert SRVName %s matched hostname", name);
153 function verify_identity(host, service, cert)
154 local ext = cert:extensions()
155 if ext[oid_subjectaltname] then
156 local sans = ext[oid_subjectaltname];
158 -- Per [TLS-CERTS] 6.3, 6.4.4, "a client MUST NOT seek a match for a
159 -- reference identifier if the presented identifiers include a DNS-ID
160 -- SRV-ID, URI-ID, or any application-specific identifier types"
161 local had_supported_altnames = false
163 if sans[oid_xmppaddr] then
164 had_supported_altnames = true
165 if service == "_xmpp-client" or service == "_xmpp-server" then
166 if compare_xmppaddr(host, sans[oid_xmppaddr]) then return true end
170 if sans[oid_dnssrv] then
171 had_supported_altnames = true
172 -- Only check srvNames if the caller specified a service
173 if service and compare_srvname(host, service, sans[oid_dnssrv]) then return true end
176 if sans["dNSName"] then
177 had_supported_altnames = true
178 if compare_dnsname(host, sans["dNSName"]) then return true end
181 -- We don't need URIs, but [TLS-CERTS] is clear.
182 if sans["uniformResourceIdentifier"] then
183 had_supported_altnames = true
186 if had_supported_altnames then return false end
189 -- Extract a common name from the certificate, and check it as if it were
190 -- a dNSName subjectAltName (wildcards may apply for, and receive,
193 -- Per [TLS-CERTS] 1.8, a CN-ID is the Common Name from a cert subject
194 -- which has one and only one Common Name
195 local subject = cert:subject()
198 local dn = subject[i]
199 if dn["oid"] == oid_commonname then
201 log("info", "Certificate has multiple common names")
210 -- Per [TLS-CERTS] 6.4.4, follow the comparison rules for dNSName SANs.
211 return compare_dnsname(host, { cn })
214 -- If all else fails, well, why should we be any different?
218 local pat = "%-%-%-%-%-BEGIN ([A-Z ]+)%-%-%-%-%-\r?\n"..
219 "([0-9A-Za-z+/=\r\n]*)\r?\n%-%-%-%-%-END %1%-%-%-%-%-";
221 function pem2der(pem)
222 local typ, data = pem:match(pat);
224 return base64.decode(data), typ;
228 local wrap = ('.'):rep(64);
229 local envelope = "-----BEGIN %s-----\n%s\n-----END %s-----\n"
231 function der2pem(data, typ)
232 typ = typ and typ:upper() or "CERTIFICATE";
233 data = base64.encode(data);
234 return s_format(envelope, typ, data:gsub(wrap, '%0\n', (#data-1)/64), typ);