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31652869 | 1 | /* $OpenBSD: auth2-gss.c,v 1.15 2006/08/03 03:34:41 deraadt Exp $ */ |
7364bd04 | 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 | ||
9ae6b834 | 29 | #ifdef GSSAPI |
30 | ||
31652869 | 31 | #include <sys/types.h> |
7364bd04 | 32 | |
31652869 | 33 | #include "xmalloc.h" |
34 | #include "key.h" | |
35 | #include "hostfile.h" | |
7364bd04 | 36 | #include "auth.h" |
37 | #include "ssh2.h" | |
7364bd04 | 38 | #include "log.h" |
39 | #include "dispatch.h" | |
31652869 | 40 | #include "buffer.h" |
7364bd04 | 41 | #include "servconf.h" |
7364bd04 | 42 | #include "packet.h" |
7364bd04 | 43 | #include "ssh-gss.h" |
31652869 | 44 | #include "monitor_wrap.h" |
7364bd04 | 45 | |
46 | extern ServerOptions options; | |
47 | ||
48 | static void input_gssapi_token(int type, u_int32_t plen, void *ctxt); | |
0789992b | 49 | static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt); |
7364bd04 | 50 | static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt); |
51 | static void input_gssapi_errtok(int, u_int32_t, void *); | |
52 | ||
53 | /* | |
54 | * We only support those mechanisms that we know about (ie ones that we know | |
8442cc66 | 55 | * how to check local user kuserok and the like) |
7364bd04 | 56 | */ |
57 | static int | |
58 | userauth_gssapi(Authctxt *authctxt) | |
59 | { | |
ca75d7de | 60 | gss_OID_desc goid = {0, NULL}; |
7364bd04 | 61 | Gssctxt *ctxt = NULL; |
62 | int mechs; | |
63 | gss_OID_set supported; | |
64 | int present; | |
65 | OM_uint32 ms; | |
66 | u_int len; | |
2ceb8101 | 67 | u_char *doid = NULL; |
7364bd04 | 68 | |
69 | if (!authctxt->valid || authctxt->user == NULL) | |
70 | return (0); | |
71 | ||
72 | mechs = packet_get_int(); | |
73 | if (mechs == 0) { | |
74 | debug("Mechanism negotiation is not supported"); | |
75 | return (0); | |
76 | } | |
77 | ||
78 | ssh_gssapi_supported_oids(&supported); | |
79 | do { | |
80 | mechs--; | |
81 | ||
82 | if (doid) | |
83 | xfree(doid); | |
84 | ||
d8d9afd0 | 85 | present = 0; |
7364bd04 | 86 | doid = packet_get_string(&len); |
87 | ||
4e2e5cfd | 88 | if (len > 2 && doid[0] == SSH_GSS_OIDTYPE && |
89 | doid[1] == len - 2) { | |
ca75d7de | 90 | goid.elements = doid + 2; |
91 | goid.length = len - 2; | |
92 | gss_test_oid_set_member(&ms, &goid, supported, | |
d8d9afd0 | 93 | &present); |
7364bd04 | 94 | } else { |
d8d9afd0 | 95 | logit("Badly formed OID received"); |
7364bd04 | 96 | } |
7364bd04 | 97 | } while (mechs > 0 && !present); |
98 | ||
99 | gss_release_oid_set(&ms, &supported); | |
100 | ||
101 | if (!present) { | |
102 | xfree(doid); | |
103 | return (0); | |
104 | } | |
105 | ||
ca75d7de | 106 | if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) { |
0fa53840 | 107 | if (ctxt != NULL) |
108 | ssh_gssapi_delete_ctx(&ctxt); | |
4771605b | 109 | xfree(doid); |
7364bd04 | 110 | return (0); |
4771605b | 111 | } |
7364bd04 | 112 | |
8442cc66 | 113 | authctxt->methoddata = (void *)ctxt; |
7364bd04 | 114 | |
115 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE); | |
116 | ||
d8d9afd0 | 117 | /* Return the OID that we received */ |
7364bd04 | 118 | packet_put_string(doid, len); |
119 | ||
120 | packet_send(); | |
121 | xfree(doid); | |
122 | ||
123 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); | |
124 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); | |
125 | authctxt->postponed = 1; | |
126 | ||
127 | return (0); | |
128 | } | |
129 | ||
130 | static void | |
131 | input_gssapi_token(int type, u_int32_t plen, void *ctxt) | |
132 | { | |
133 | Authctxt *authctxt = ctxt; | |
134 | Gssctxt *gssctxt; | |
135 | gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; | |
136 | gss_buffer_desc recv_tok; | |
0789992b | 137 | OM_uint32 maj_status, min_status, flags; |
7364bd04 | 138 | u_int len; |
139 | ||
140 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) | |
141 | fatal("No authentication or GSSAPI context"); | |
142 | ||
143 | gssctxt = authctxt->methoddata; | |
144 | recv_tok.value = packet_get_string(&len); | |
145 | recv_tok.length = len; /* u_int vs. size_t */ | |
146 | ||
147 | packet_check_eom(); | |
148 | ||
149 | maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, | |
0789992b | 150 | &send_tok, &flags)); |
7364bd04 | 151 | |
152 | xfree(recv_tok.value); | |
153 | ||
154 | if (GSS_ERROR(maj_status)) { | |
155 | if (send_tok.length != 0) { | |
156 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); | |
157 | packet_put_string(send_tok.value, send_tok.length); | |
158 | packet_send(); | |
159 | } | |
160 | authctxt->postponed = 0; | |
161 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
0789992b | 162 | userauth_finish(authctxt, 0, "gssapi-with-mic"); |
7364bd04 | 163 | } else { |
164 | if (send_tok.length != 0) { | |
165 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); | |
166 | packet_put_string(send_tok.value, send_tok.length); | |
167 | packet_send(); | |
168 | } | |
169 | if (maj_status == GSS_S_COMPLETE) { | |
170 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
0789992b | 171 | if (flags & GSS_C_INTEG_FLAG) |
172 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, | |
173 | &input_gssapi_mic); | |
174 | else | |
175 | dispatch_set( | |
176 | SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, | |
177 | &input_gssapi_exchange_complete); | |
7364bd04 | 178 | } |
179 | } | |
180 | ||
181 | gss_release_buffer(&min_status, &send_tok); | |
182 | } | |
183 | ||
184 | static void | |
185 | input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) | |
186 | { | |
187 | Authctxt *authctxt = ctxt; | |
188 | Gssctxt *gssctxt; | |
189 | gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; | |
190 | gss_buffer_desc recv_tok; | |
191 | OM_uint32 maj_status; | |
eb18f58d | 192 | u_int len; |
7364bd04 | 193 | |
194 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) | |
195 | fatal("No authentication or GSSAPI context"); | |
196 | ||
197 | gssctxt = authctxt->methoddata; | |
eb18f58d | 198 | recv_tok.value = packet_get_string(&len); |
199 | recv_tok.length = len; | |
7364bd04 | 200 | |
201 | packet_check_eom(); | |
202 | ||
203 | /* Push the error token into GSSAPI to see what it says */ | |
204 | maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, | |
205 | &send_tok, NULL)); | |
206 | ||
207 | xfree(recv_tok.value); | |
208 | ||
209 | /* We can't return anything to the client, even if we wanted to */ | |
210 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
211 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); | |
212 | ||
213 | /* The client will have already moved on to the next auth */ | |
214 | ||
215 | gss_release_buffer(&maj_status, &send_tok); | |
216 | } | |
217 | ||
218 | /* | |
219 | * This is called when the client thinks we've completed authentication. | |
220 | * It should only be enabled in the dispatch handler by the function above, | |
221 | * which only enables it once the GSSAPI exchange is complete. | |
222 | */ | |
223 | ||
224 | static void | |
225 | input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt) | |
226 | { | |
227 | Authctxt *authctxt = ctxt; | |
228 | Gssctxt *gssctxt; | |
229 | int authenticated; | |
230 | ||
231 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) | |
232 | fatal("No authentication or GSSAPI context"); | |
233 | ||
234 | gssctxt = authctxt->methoddata; | |
235 | ||
236 | /* | |
0789992b | 237 | * We don't need to check the status, because we're only enabled in |
238 | * the dispatcher once the exchange is complete | |
7364bd04 | 239 | */ |
240 | ||
241 | packet_check_eom(); | |
242 | ||
243 | authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); | |
244 | ||
245 | authctxt->postponed = 0; | |
246 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
247 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); | |
0789992b | 248 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); |
249 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); | |
250 | userauth_finish(authctxt, authenticated, "gssapi-with-mic"); | |
251 | } | |
252 | ||
253 | static void | |
254 | input_gssapi_mic(int type, u_int32_t plen, void *ctxt) | |
255 | { | |
256 | Authctxt *authctxt = ctxt; | |
257 | Gssctxt *gssctxt; | |
258 | int authenticated = 0; | |
259 | Buffer b; | |
260 | gss_buffer_desc mic, gssbuf; | |
261 | u_int len; | |
b6453d99 | 262 | |
0789992b | 263 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) |
264 | fatal("No authentication or GSSAPI context"); | |
b6453d99 | 265 | |
0789992b | 266 | gssctxt = authctxt->methoddata; |
b6453d99 | 267 | |
0789992b | 268 | mic.value = packet_get_string(&len); |
269 | mic.length = len; | |
b6453d99 | 270 | |
0789992b | 271 | ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service, |
272 | "gssapi-with-mic"); | |
b6453d99 | 273 | |
0789992b | 274 | gssbuf.value = buffer_ptr(&b); |
275 | gssbuf.length = buffer_len(&b); | |
b6453d99 | 276 | |
0789992b | 277 | if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic)))) |
278 | authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); | |
279 | else | |
280 | logit("GSSAPI MIC check failed"); | |
281 | ||
282 | buffer_free(&b); | |
283 | xfree(mic.value); | |
b6453d99 | 284 | |
0789992b | 285 | authctxt->postponed = 0; |
286 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
287 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); | |
288 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); | |
7364bd04 | 289 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); |
0789992b | 290 | userauth_finish(authctxt, authenticated, "gssapi-with-mic"); |
7364bd04 | 291 | } |
292 | ||
293 | Authmethod method_gssapi = { | |
0789992b | 294 | "gssapi-with-mic", |
7364bd04 | 295 | userauth_gssapi, |
296 | &options.gss_authentication | |
297 | }; | |
9ae6b834 | 298 | |
299 | #endif /* GSSAPI */ |