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cdd66111 | 1 | /* $OpenBSD: auth2-gss.c,v 1.7 2003/11/21 11:57:03 djm Exp $ */ |
0fff78ff | 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); | |
cdd66111 | 46 | static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt); |
0fff78ff | 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 | ||
cdd66111 | 82 | present = 0; |
0fff78ff | 83 | doid = packet_get_string(&len); |
84 | ||
cdd66111 | 85 | if (len > 2 && |
86 | doid[0] == SSH_GSS_OIDTYPE && | |
87 | doid[1] == len - 2) { | |
0fff78ff | 88 | oid.elements = doid + 2; |
89 | oid.length = len - 2; | |
cdd66111 | 90 | gss_test_oid_set_member(&ms, &oid, supported, |
91 | &present); | |
92 | } else { | |
93 | logit("Badly formed OID received"); | |
0fff78ff | 94 | } |
0fff78ff | 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 | ||
104 | if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid)))) { | |
105 | xfree(doid); | |
106 | return (0); | |
107 | } | |
108 | ||
109 | authctxt->methoddata=(void *)ctxt; | |
110 | ||
111 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE); | |
112 | ||
cdd66111 | 113 | /* Return the OID that we received */ |
0fff78ff | 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; | |
cdd66111 | 133 | OM_uint32 maj_status, min_status, flags; |
0fff78ff | 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, | |
cdd66111 | 146 | &send_tok, &flags)); |
0fff78ff | 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); | |
cdd66111 | 158 | userauth_finish(authctxt, 0, "gssapi-with-mic"); |
0fff78ff | 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); | |
cdd66111 | 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); | |
0fff78ff | 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; | |
188 | u_int len; | |
189 | ||
190 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) | |
191 | fatal("No authentication or GSSAPI context"); | |
192 | ||
193 | gssctxt = authctxt->methoddata; | |
194 | recv_tok.value = packet_get_string(&len); | |
195 | recv_tok.length = len; | |
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 | /* | |
cdd66111 | 233 | * We don't need to check the status, because we're only enabled in |
234 | * the dispatcher once the exchange is complete | |
0fff78ff | 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); | |
cdd66111 | 244 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); |
245 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); | |
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); | |
0fff78ff | 285 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); |
cdd66111 | 286 | userauth_finish(authctxt, authenticated, "gssapi-with-mic"); |
0fff78ff | 287 | } |
288 | ||
289 | Authmethod method_gssapi = { | |
cdd66111 | 290 | "gssapi-with-mic", |
0fff78ff | 291 | userauth_gssapi, |
292 | &options.gss_authentication | |
293 | }; | |
294 | ||
295 | #endif /* GSSAPI */ |