Damien Miller | a8e06ce | 2003-11-21 23:48:55 +1100 | [diff] [blame^] | 1 | /* $OpenBSD: auth2-gss.c,v 1.7 2003/11/21 11:57:03 djm Exp $ */ |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 2 | |
| 3 | /* |
| 4 | * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved. |
| 5 | * |
| 6 | * Redistribution and use in source and binary forms, with or without |
| 7 | * modification, are permitted provided that the following conditions |
| 8 | * are met: |
| 9 | * 1. Redistributions of source code must retain the above copyright |
| 10 | * notice, this list of conditions and the following disclaimer. |
| 11 | * 2. Redistributions in binary form must reproduce the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer in the |
| 13 | * documentation and/or other materials provided with the distribution. |
| 14 | * |
| 15 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AS IS'' AND ANY EXPRESS OR |
| 16 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 17 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 18 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 19 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 20 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 21 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 22 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 23 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 24 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 25 | */ |
| 26 | |
| 27 | #include "includes.h" |
| 28 | |
| 29 | #ifdef GSSAPI |
| 30 | |
| 31 | #include "auth.h" |
| 32 | #include "ssh2.h" |
| 33 | #include "xmalloc.h" |
| 34 | #include "log.h" |
| 35 | #include "dispatch.h" |
| 36 | #include "servconf.h" |
| 37 | #include "compat.h" |
| 38 | #include "packet.h" |
| 39 | #include "monitor_wrap.h" |
| 40 | |
| 41 | #include "ssh-gss.h" |
| 42 | |
| 43 | extern ServerOptions options; |
| 44 | |
| 45 | static void input_gssapi_token(int type, u_int32_t plen, void *ctxt); |
Damien Miller | 0425d40 | 2003-11-17 22:18:21 +1100 | [diff] [blame] | 46 | static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 47 | static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt); |
| 48 | static void input_gssapi_errtok(int, u_int32_t, void *); |
| 49 | |
| 50 | /* |
| 51 | * We only support those mechanisms that we know about (ie ones that we know |
| 52 | * how to check local user kuserok and the like |
| 53 | */ |
| 54 | static int |
| 55 | userauth_gssapi(Authctxt *authctxt) |
| 56 | { |
| 57 | gss_OID_desc oid = {0, NULL}; |
| 58 | Gssctxt *ctxt = NULL; |
| 59 | int mechs; |
| 60 | gss_OID_set supported; |
| 61 | int present; |
| 62 | OM_uint32 ms; |
| 63 | u_int len; |
| 64 | char *doid = NULL; |
| 65 | |
| 66 | if (!authctxt->valid || authctxt->user == NULL) |
| 67 | return (0); |
| 68 | |
| 69 | mechs = packet_get_int(); |
| 70 | if (mechs == 0) { |
| 71 | debug("Mechanism negotiation is not supported"); |
| 72 | return (0); |
| 73 | } |
| 74 | |
| 75 | ssh_gssapi_supported_oids(&supported); |
| 76 | do { |
| 77 | mechs--; |
| 78 | |
| 79 | if (doid) |
| 80 | xfree(doid); |
| 81 | |
Darren Tucker | 655a5e0 | 2003-11-03 20:09:03 +1100 | [diff] [blame] | 82 | present = 0; |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 83 | doid = packet_get_string(&len); |
| 84 | |
Damien Miller | a8e06ce | 2003-11-21 23:48:55 +1100 | [diff] [blame^] | 85 | if (len > 2 && |
Darren Tucker | 655a5e0 | 2003-11-03 20:09:03 +1100 | [diff] [blame] | 86 | doid[0] == SSH_GSS_OIDTYPE && |
| 87 | doid[1] == len - 2) { |
Damien Miller | a8e06ce | 2003-11-21 23:48:55 +1100 | [diff] [blame^] | 88 | oid.elements = doid + 2; |
| 89 | oid.length = len - 2; |
Darren Tucker | 655a5e0 | 2003-11-03 20:09:03 +1100 | [diff] [blame] | 90 | gss_test_oid_set_member(&ms, &oid, supported, |
| 91 | &present); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 92 | } else { |
Darren Tucker | 655a5e0 | 2003-11-03 20:09:03 +1100 | [diff] [blame] | 93 | logit("Badly formed OID received"); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 94 | } |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 95 | } while (mechs > 0 && !present); |
| 96 | |
| 97 | gss_release_oid_set(&ms, &supported); |
| 98 | |
| 99 | if (!present) { |
| 100 | xfree(doid); |
| 101 | return (0); |
| 102 | } |
| 103 | |
Damien Miller | 982d326 | 2003-09-02 22:59:01 +1000 | [diff] [blame] | 104 | if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid)))) { |
| 105 | xfree(doid); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 106 | return (0); |
Damien Miller | 982d326 | 2003-09-02 22:59:01 +1000 | [diff] [blame] | 107 | } |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 108 | |
| 109 | authctxt->methoddata=(void *)ctxt; |
| 110 | |
| 111 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE); |
| 112 | |
Darren Tucker | 655a5e0 | 2003-11-03 20:09:03 +1100 | [diff] [blame] | 113 | /* Return the OID that we received */ |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 114 | packet_put_string(doid, len); |
| 115 | |
| 116 | packet_send(); |
| 117 | xfree(doid); |
| 118 | |
| 119 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); |
| 120 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); |
| 121 | authctxt->postponed = 1; |
| 122 | |
| 123 | return (0); |
| 124 | } |
| 125 | |
| 126 | static void |
| 127 | input_gssapi_token(int type, u_int32_t plen, void *ctxt) |
| 128 | { |
| 129 | Authctxt *authctxt = ctxt; |
| 130 | Gssctxt *gssctxt; |
| 131 | gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; |
| 132 | gss_buffer_desc recv_tok; |
Damien Miller | 0425d40 | 2003-11-17 22:18:21 +1100 | [diff] [blame] | 133 | OM_uint32 maj_status, min_status, flags; |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 134 | u_int len; |
| 135 | |
| 136 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) |
| 137 | fatal("No authentication or GSSAPI context"); |
| 138 | |
| 139 | gssctxt = authctxt->methoddata; |
| 140 | recv_tok.value = packet_get_string(&len); |
| 141 | recv_tok.length = len; /* u_int vs. size_t */ |
| 142 | |
| 143 | packet_check_eom(); |
| 144 | |
| 145 | maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, |
Damien Miller | 0425d40 | 2003-11-17 22:18:21 +1100 | [diff] [blame] | 146 | &send_tok, &flags)); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 147 | |
| 148 | xfree(recv_tok.value); |
| 149 | |
| 150 | if (GSS_ERROR(maj_status)) { |
| 151 | if (send_tok.length != 0) { |
| 152 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); |
| 153 | packet_put_string(send_tok.value, send_tok.length); |
| 154 | packet_send(); |
| 155 | } |
| 156 | authctxt->postponed = 0; |
| 157 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); |
Damien Miller | 0425d40 | 2003-11-17 22:18:21 +1100 | [diff] [blame] | 158 | userauth_finish(authctxt, 0, "gssapi-with-mic"); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 159 | } else { |
| 160 | if (send_tok.length != 0) { |
| 161 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); |
| 162 | packet_put_string(send_tok.value, send_tok.length); |
| 163 | packet_send(); |
| 164 | } |
| 165 | if (maj_status == GSS_S_COMPLETE) { |
| 166 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); |
Damien Miller | 0425d40 | 2003-11-17 22:18:21 +1100 | [diff] [blame] | 167 | if (flags & GSS_C_INTEG_FLAG) |
| 168 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, |
| 169 | &input_gssapi_mic); |
| 170 | else |
| 171 | dispatch_set( |
| 172 | SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, |
| 173 | &input_gssapi_exchange_complete); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 174 | } |
| 175 | } |
| 176 | |
| 177 | gss_release_buffer(&min_status, &send_tok); |
| 178 | } |
| 179 | |
| 180 | static void |
| 181 | input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) |
| 182 | { |
| 183 | Authctxt *authctxt = ctxt; |
| 184 | Gssctxt *gssctxt; |
| 185 | gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; |
| 186 | gss_buffer_desc recv_tok; |
| 187 | OM_uint32 maj_status; |
Damien Miller | 55c47ed | 2003-09-02 22:14:07 +1000 | [diff] [blame] | 188 | u_int len; |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 189 | |
| 190 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) |
| 191 | fatal("No authentication or GSSAPI context"); |
| 192 | |
| 193 | gssctxt = authctxt->methoddata; |
Damien Miller | 55c47ed | 2003-09-02 22:14:07 +1000 | [diff] [blame] | 194 | recv_tok.value = packet_get_string(&len); |
| 195 | recv_tok.length = len; |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 196 | |
| 197 | packet_check_eom(); |
| 198 | |
| 199 | /* Push the error token into GSSAPI to see what it says */ |
| 200 | maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, |
| 201 | &send_tok, NULL)); |
| 202 | |
| 203 | xfree(recv_tok.value); |
| 204 | |
| 205 | /* We can't return anything to the client, even if we wanted to */ |
| 206 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); |
| 207 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); |
| 208 | |
| 209 | /* The client will have already moved on to the next auth */ |
| 210 | |
| 211 | gss_release_buffer(&maj_status, &send_tok); |
| 212 | } |
| 213 | |
| 214 | /* |
| 215 | * This is called when the client thinks we've completed authentication. |
| 216 | * It should only be enabled in the dispatch handler by the function above, |
| 217 | * which only enables it once the GSSAPI exchange is complete. |
| 218 | */ |
| 219 | |
| 220 | static void |
| 221 | input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt) |
| 222 | { |
| 223 | Authctxt *authctxt = ctxt; |
| 224 | Gssctxt *gssctxt; |
| 225 | int authenticated; |
| 226 | |
| 227 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) |
| 228 | fatal("No authentication or GSSAPI context"); |
| 229 | |
| 230 | gssctxt = authctxt->methoddata; |
| 231 | |
| 232 | /* |
Damien Miller | 0425d40 | 2003-11-17 22:18:21 +1100 | [diff] [blame] | 233 | * We don't need to check the status, because we're only enabled in |
| 234 | * the dispatcher once the exchange is complete |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 235 | */ |
| 236 | |
| 237 | packet_check_eom(); |
| 238 | |
| 239 | authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); |
| 240 | |
| 241 | authctxt->postponed = 0; |
| 242 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); |
| 243 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); |
Damien Miller | 0425d40 | 2003-11-17 22:18:21 +1100 | [diff] [blame] | 244 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 245 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); |
Damien Miller | 0425d40 | 2003-11-17 22:18:21 +1100 | [diff] [blame] | 246 | userauth_finish(authctxt, authenticated, "gssapi-with-mic"); |
| 247 | } |
| 248 | |
| 249 | static void |
| 250 | input_gssapi_mic(int type, u_int32_t plen, void *ctxt) |
| 251 | { |
| 252 | Authctxt *authctxt = ctxt; |
| 253 | Gssctxt *gssctxt; |
| 254 | int authenticated = 0; |
| 255 | Buffer b; |
| 256 | gss_buffer_desc mic, gssbuf; |
| 257 | u_int len; |
| 258 | |
| 259 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) |
| 260 | fatal("No authentication or GSSAPI context"); |
| 261 | |
| 262 | gssctxt = authctxt->methoddata; |
| 263 | |
| 264 | mic.value = packet_get_string(&len); |
| 265 | mic.length = len; |
| 266 | |
| 267 | ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service, |
| 268 | "gssapi-with-mic"); |
| 269 | |
| 270 | gssbuf.value = buffer_ptr(&b); |
| 271 | gssbuf.length = buffer_len(&b); |
| 272 | |
| 273 | if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic)))) |
| 274 | authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); |
| 275 | else |
| 276 | logit("GSSAPI MIC check failed"); |
| 277 | |
| 278 | buffer_free(&b); |
| 279 | xfree(mic.value); |
| 280 | |
| 281 | authctxt->postponed = 0; |
| 282 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); |
| 283 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); |
| 284 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); |
| 285 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); |
| 286 | userauth_finish(authctxt, authenticated, "gssapi-with-mic"); |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 287 | } |
| 288 | |
| 289 | Authmethod method_gssapi = { |
Damien Miller | 0425d40 | 2003-11-17 22:18:21 +1100 | [diff] [blame] | 290 | "gssapi-with-mic", |
Darren Tucker | 0efd155 | 2003-08-26 11:49:55 +1000 | [diff] [blame] | 291 | userauth_gssapi, |
| 292 | &options.gss_authentication |
| 293 | }; |
| 294 | |
| 295 | #endif /* GSSAPI */ |