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4e2e5cfd | 1 | /* $OpenBSD: auth2-gss.c,v 1.10 2005/07/17 07:17:54 djm 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 | ||
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); | |
0789992b | 46 | static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt); |
7364bd04 | 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 | { | |
ca75d7de | 57 | gss_OID_desc goid = {0, NULL}; |
7364bd04 | 58 | Gssctxt *ctxt = NULL; |
59 | int mechs; | |
60 | gss_OID_set supported; | |
61 | int present; | |
62 | OM_uint32 ms; | |
63 | u_int len; | |
2ceb8101 | 64 | u_char *doid = NULL; |
7364bd04 | 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 | ||
d8d9afd0 | 82 | present = 0; |
7364bd04 | 83 | doid = packet_get_string(&len); |
84 | ||
4e2e5cfd | 85 | if (len > 2 && doid[0] == SSH_GSS_OIDTYPE && |
86 | doid[1] == len - 2) { | |
ca75d7de | 87 | goid.elements = doid + 2; |
88 | goid.length = len - 2; | |
89 | gss_test_oid_set_member(&ms, &goid, supported, | |
d8d9afd0 | 90 | &present); |
7364bd04 | 91 | } else { |
d8d9afd0 | 92 | logit("Badly formed OID received"); |
7364bd04 | 93 | } |
7364bd04 | 94 | } while (mechs > 0 && !present); |
95 | ||
96 | gss_release_oid_set(&ms, &supported); | |
97 | ||
98 | if (!present) { | |
99 | xfree(doid); | |
100 | return (0); | |
101 | } | |
102 | ||
ca75d7de | 103 | if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) { |
4771605b | 104 | xfree(doid); |
7364bd04 | 105 | return (0); |
4771605b | 106 | } |
7364bd04 | 107 | |
108 | authctxt->methoddata=(void *)ctxt; | |
109 | ||
110 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE); | |
111 | ||
d8d9afd0 | 112 | /* Return the OID that we received */ |
7364bd04 | 113 | packet_put_string(doid, len); |
114 | ||
115 | packet_send(); | |
116 | xfree(doid); | |
117 | ||
118 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); | |
119 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); | |
120 | authctxt->postponed = 1; | |
121 | ||
122 | return (0); | |
123 | } | |
124 | ||
125 | static void | |
126 | input_gssapi_token(int type, u_int32_t plen, void *ctxt) | |
127 | { | |
128 | Authctxt *authctxt = ctxt; | |
129 | Gssctxt *gssctxt; | |
130 | gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; | |
131 | gss_buffer_desc recv_tok; | |
0789992b | 132 | OM_uint32 maj_status, min_status, flags; |
7364bd04 | 133 | u_int len; |
134 | ||
135 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) | |
136 | fatal("No authentication or GSSAPI context"); | |
137 | ||
138 | gssctxt = authctxt->methoddata; | |
139 | recv_tok.value = packet_get_string(&len); | |
140 | recv_tok.length = len; /* u_int vs. size_t */ | |
141 | ||
142 | packet_check_eom(); | |
143 | ||
144 | maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, | |
0789992b | 145 | &send_tok, &flags)); |
7364bd04 | 146 | |
147 | xfree(recv_tok.value); | |
148 | ||
149 | if (GSS_ERROR(maj_status)) { | |
150 | if (send_tok.length != 0) { | |
151 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); | |
152 | packet_put_string(send_tok.value, send_tok.length); | |
153 | packet_send(); | |
154 | } | |
155 | authctxt->postponed = 0; | |
156 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
0789992b | 157 | userauth_finish(authctxt, 0, "gssapi-with-mic"); |
7364bd04 | 158 | } else { |
159 | if (send_tok.length != 0) { | |
160 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); | |
161 | packet_put_string(send_tok.value, send_tok.length); | |
162 | packet_send(); | |
163 | } | |
164 | if (maj_status == GSS_S_COMPLETE) { | |
165 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
0789992b | 166 | if (flags & GSS_C_INTEG_FLAG) |
167 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, | |
168 | &input_gssapi_mic); | |
169 | else | |
170 | dispatch_set( | |
171 | SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, | |
172 | &input_gssapi_exchange_complete); | |
7364bd04 | 173 | } |
174 | } | |
175 | ||
176 | gss_release_buffer(&min_status, &send_tok); | |
177 | } | |
178 | ||
179 | static void | |
180 | input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) | |
181 | { | |
182 | Authctxt *authctxt = ctxt; | |
183 | Gssctxt *gssctxt; | |
184 | gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; | |
185 | gss_buffer_desc recv_tok; | |
186 | OM_uint32 maj_status; | |
eb18f58d | 187 | u_int len; |
7364bd04 | 188 | |
189 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) | |
190 | fatal("No authentication or GSSAPI context"); | |
191 | ||
192 | gssctxt = authctxt->methoddata; | |
eb18f58d | 193 | recv_tok.value = packet_get_string(&len); |
194 | recv_tok.length = len; | |
7364bd04 | 195 | |
196 | packet_check_eom(); | |
197 | ||
198 | /* Push the error token into GSSAPI to see what it says */ | |
199 | maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, | |
200 | &send_tok, NULL)); | |
201 | ||
202 | xfree(recv_tok.value); | |
203 | ||
204 | /* We can't return anything to the client, even if we wanted to */ | |
205 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
206 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); | |
207 | ||
208 | /* The client will have already moved on to the next auth */ | |
209 | ||
210 | gss_release_buffer(&maj_status, &send_tok); | |
211 | } | |
212 | ||
213 | /* | |
214 | * This is called when the client thinks we've completed authentication. | |
215 | * It should only be enabled in the dispatch handler by the function above, | |
216 | * which only enables it once the GSSAPI exchange is complete. | |
217 | */ | |
218 | ||
219 | static void | |
220 | input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt) | |
221 | { | |
222 | Authctxt *authctxt = ctxt; | |
223 | Gssctxt *gssctxt; | |
224 | int authenticated; | |
225 | ||
226 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) | |
227 | fatal("No authentication or GSSAPI context"); | |
228 | ||
229 | gssctxt = authctxt->methoddata; | |
230 | ||
231 | /* | |
0789992b | 232 | * We don't need to check the status, because we're only enabled in |
233 | * the dispatcher once the exchange is complete | |
7364bd04 | 234 | */ |
235 | ||
236 | packet_check_eom(); | |
237 | ||
238 | authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); | |
239 | ||
240 | authctxt->postponed = 0; | |
241 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
242 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); | |
0789992b | 243 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); |
244 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); | |
245 | userauth_finish(authctxt, authenticated, "gssapi-with-mic"); | |
246 | } | |
247 | ||
248 | static void | |
249 | input_gssapi_mic(int type, u_int32_t plen, void *ctxt) | |
250 | { | |
251 | Authctxt *authctxt = ctxt; | |
252 | Gssctxt *gssctxt; | |
253 | int authenticated = 0; | |
254 | Buffer b; | |
255 | gss_buffer_desc mic, gssbuf; | |
256 | u_int len; | |
b6453d99 | 257 | |
0789992b | 258 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) |
259 | fatal("No authentication or GSSAPI context"); | |
b6453d99 | 260 | |
0789992b | 261 | gssctxt = authctxt->methoddata; |
b6453d99 | 262 | |
0789992b | 263 | mic.value = packet_get_string(&len); |
264 | mic.length = len; | |
b6453d99 | 265 | |
0789992b | 266 | ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service, |
267 | "gssapi-with-mic"); | |
b6453d99 | 268 | |
0789992b | 269 | gssbuf.value = buffer_ptr(&b); |
270 | gssbuf.length = buffer_len(&b); | |
b6453d99 | 271 | |
0789992b | 272 | if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic)))) |
273 | authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); | |
274 | else | |
275 | logit("GSSAPI MIC check failed"); | |
276 | ||
277 | buffer_free(&b); | |
278 | xfree(mic.value); | |
b6453d99 | 279 | |
0789992b | 280 | authctxt->postponed = 0; |
281 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
282 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); | |
283 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL); | |
7364bd04 | 284 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); |
0789992b | 285 | userauth_finish(authctxt, authenticated, "gssapi-with-mic"); |
7364bd04 | 286 | } |
287 | ||
288 | Authmethod method_gssapi = { | |
0789992b | 289 | "gssapi-with-mic", |
7364bd04 | 290 | userauth_gssapi, |
291 | &options.gss_authentication | |
292 | }; | |
293 | ||
294 | #endif /* GSSAPI */ |