Mercurial > lxmppd-hg-xmllex / file comparison
comparison: util/x509.lua
util/x509.lua
- changeset 3733
- 26571a99f6e6
- parent 3649
- 337391d34b70
- child 3735
- 40b54c46a14c
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| 3732:bf449ecf2144 | 3733:26571a99f6e6 |
|---|---|
| 1 -- Prosody IM | |
| 2 -- Copyright (C) 2010 Matthew Wild | |
| 3 -- Copyright (C) 2010 Paul Aurich | |
| 4 -- | |
| 5 -- This project is MIT/X11 licensed. Please see the | |
| 6 -- COPYING file in the source package for more information. | |
| 7 -- | |
| 8 | |
| 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. | |
| 12 | |
| 13 | |
| 14 -- [TLS-CERTS] - http://tools.ietf.org/html/draft-saintandre-tls-server-id-check-10 | |
| 15 -- [XMPP-CORE] - http://tools.ietf.org/html/draft-ietf-xmpp-3920bis-18 | |
| 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 | |
| 20 | |
| 21 local nameprep = require "util.encodings".stringprep.nameprep; | |
| 22 local idna_to_ascii = require "util.encodings".idna.to_ascii; | |
| 23 local log = require "util.logger".init("certverification"); | |
| 24 | |
| 25 module "certverification" | |
| 26 | |
| 27 local oid_commonname = "2.5.4.3"; -- [LDAP] 2.3 | |
| 28 local oid_subjectaltname = "2.5.29.17"; -- [PKIX] 4.2.1.6 | |
| 29 local oid_xmppaddr = "1.3.6.1.5.5.7.8.5"; -- [XMPP-CORE] | |
| 30 local oid_dnssrv = "1.3.6.1.5.5.7.8.7"; -- [SRV-ID] | |
| 31 | |
| 32 -- Compare a hostname (possibly international) with asserted names | |
| 33 -- extracted from a certificate. | |
| 34 -- This function follows the rules laid out in | |
| 35 -- sections 4.4.1 and 4.4.2 of [TLS-CERTS] | |
| 36 -- | |
| 37 -- A wildcard ("*") all by itself is allowed only as the left-most label | |
| 38 local function compare_dnsname(host, asserted_names) | |
| 39 -- TODO: Sufficient normalization? Review relevant specs. | |
| 40 local norm_host = idna_to_ascii(host) | |
| 41 if norm_host == nil then | |
| 42 log("info", "Host %s failed IDNA ToASCII operation", host) | |
| 43 return false | |
| 44 end | |
| 45 | |
| 46 norm_host = norm_host:lower() | |
| 47 | |
| 48 local host_chopped = norm_host:gsub("^[^.]+%.", "") -- everything after the first label | |
| 49 | |
| 50 for i=1,#asserted_names do | |
| 51 local name = asserted_names[i] | |
| 52 if norm_host == name:lower() then | |
| 53 log("debug", "Cert dNSName %s matched hostname", name); | |
| 54 return true | |
| 55 end | |
| 56 | |
| 57 -- Allow the left most label to be a "*" | |
| 58 if name:match("^%*%.") then | |
| 59 local rest_name = name:gsub("^[^.]+%.", "") | |
| 60 if host_chopped == rest_name:lower() then | |
| 61 log("debug", "Cert dNSName %s matched hostname", name); | |
| 62 return true | |
| 63 end | |
| 64 end | |
| 65 end | |
| 66 | |
| 67 return false | |
| 68 end | |
| 69 | |
| 70 -- Compare an XMPP domain name with the asserted id-on-xmppAddr | |
| 71 -- identities extracted from a certificate. Both are UTF8 strings. | |
| 72 -- | |
| 73 -- Per [XMPP-CORE], matches against asserted identities don't include | |
| 74 -- wildcards, so we just do a normalize on both and then a string comparison | |
| 75 -- | |
| 76 -- TODO: Support for full JIDs? | |
| 77 local function compare_xmppaddr(host, asserted_names) | |
| 78 local norm_host = nameprep(host) | |
| 79 | |
| 80 for i=1,#asserted_names do | |
| 81 local name = asserted_names[i] | |
| 82 | |
| 83 -- We only want to match against bare domains right now, not | |
| 84 -- those crazy full-er JIDs. | |
| 85 if name:match("[@/]") then | |
| 86 log("debug", "Ignoring xmppAddr %s because it's not a bare domain", name) | |
| 87 else | |
| 88 local norm_name = nameprep(name) | |
| 89 if norm_name == nil then | |
| 90 log("info", "Ignoring xmppAddr %s, failed nameprep!", name) | |
| 91 else | |
| 92 if norm_host == norm_name then | |
| 93 log("debug", "Cert xmppAddr %s matched hostname", name) | |
| 94 return true | |
| 95 end | |
| 96 end | |
| 97 end | |
| 98 end | |
| 99 | |
| 100 return false | |
| 101 end | |
| 102 | |
| 103 -- Compare a host + service against the asserted id-on-dnsSRV (SRV-ID) | |
| 104 -- identities extracted from a certificate. | |
| 105 -- | |
| 106 -- Per [SRV-ID], the asserted identities will be encoded in ASCII via ToASCII. | |
| 107 -- Comparison is done case-insensitively, and a wildcard ("*") all by itself | |
| 108 -- is allowed only as the left-most non-service label. | |
| 109 local function compare_srvname(host, service, asserted_names) | |
| 110 local norm_host = idna_to_ascii(host) | |
| 111 if norm_host == nil then | |
| 112 log("info", "Host %s failed IDNA ToASCII operation", host); | |
| 113 return false | |
| 114 end | |
| 115 | |
| 116 -- Service names start with a "_" | |
| 117 if service:match("^_") == nil then service = "_"..service end | |
| 118 | |
| 119 norm_host = norm_host:lower(); | |
| 120 local host_chopped = norm_host:gsub("^[^.]+%.", "") -- everything after the first label | |
| 121 | |
| 122 for i=1,#asserted_names do | |
| 123 local asserted_service, name = asserted_names[i]:match("^(_[^.]+)%.(.*)"); | |
| 124 if service == asserted_service then | |
| 125 if norm_host == name:lower() then | |
| 126 log("debug", "Cert SRVName %s matched hostname", name); | |
| 127 return true; | |
| 128 end | |
| 129 | |
| 130 -- Allow the left most label to be a "*" | |
| 131 if name:match("^%*%.") then | |
| 132 local rest_name = name:gsub("^[^.]+%.", "") | |
| 133 if host_chopped == rest_name:lower() then | |
| 134 log("debug", "Cert SRVName %s matched hostname", name) | |
| 135 return true | |
| 136 end | |
| 137 end | |
| 138 if norm_host == name:lower() then | |
| 139 log("debug", "Cert SRVName %s matched hostname", name); | |
| 140 return true | |
| 141 end | |
| 142 end | |
| 143 end | |
| 144 | |
| 145 return false | |
| 146 end | |
| 147 | |
| 148 function verify_identity(host, service, cert) | |
| 149 local ext = cert:extensions() | |
| 150 if ext[oid_subjectaltname] then | |
| 151 local sans = ext[oid_subjectaltname]; | |
| 152 | |
| 153 -- Per [TLS-CERTS] 4.3, 4.4.4, "a client MUST NOT seek a match for a | |
| 154 -- reference identifier if the presented identifiers include a DNS-ID | |
| 155 -- SRV-ID, URI-ID, or any application-specific identifier types" | |
| 156 local had_supported_altnames = false | |
| 157 | |
| 158 if sans[oid_xmppaddr] then | |
| 159 had_supported_altnames = true | |
| 160 if compare_xmppaddr(host, sans[oid_xmppaddr]) then return true end | |
| 161 end | |
| 162 | |
| 163 if sans[oid_dnssrv] then | |
| 164 had_supported_altnames = true | |
| 165 -- Only check srvNames if the caller specified a service | |
| 166 if service and compare_srvname(host, service, sans[oid_dnssrv]) then return true end | |
| 167 end | |
| 168 | |
| 169 if sans["dNSName"] then | |
| 170 had_supported_altnames = true | |
| 171 if compare_dnsname(host, sans["dNSName"]) then return true end | |
| 172 end | |
| 173 | |
| 174 -- We don't need URIs, but [TLS-CERTS] is clear. | |
| 175 if sans["uniformResourceIdentifier"] then | |
| 176 had_supported_altnames = true | |
| 177 end | |
| 178 | |
| 179 if had_supported_altnames then return false end | |
| 180 end | |
| 181 | |
| 182 -- Extract a common name from the certificate, and check it as if it were | |
| 183 -- a dNSName subjectAltName (wildcards may apply for, and receive, | |
| 184 -- cat treats) | |
| 185 -- | |
| 186 -- Per [TLS-CERTS] 1.5, a CN-ID is the Common Name from a cert subject | |
| 187 -- which has one and only one Common Name | |
| 188 local subject = cert:subject() | |
| 189 local cn = nil | |
| 190 for i=1,#subject do | |
| 191 local dn = subject[i] | |
| 192 if dn["oid"] == oid_commonname then | |
| 193 if cn then | |
| 194 log("info", "Certificate has multiple common names") | |
| 195 return false | |
| 196 end | |
| 197 | |
| 198 cn = dn["value"]; | |
| 199 end | |
| 200 end | |
| 201 | |
| 202 if cn then | |
| 203 -- Per [TLS-CERTS] 4.4.4, follow the comparison rules for dNSName SANs. | |
| 204 return compare_dnsname(host, { cn }) | |
| 205 end | |
| 206 | |
| 207 -- If all else fails, well, why should we be any different? | |
| 208 return false | |
| 209 end | |
| 210 | |
| 211 return _M; |
