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9cb1827b | 1 | /* $OpenBSD: auth2-gss.c,v 1.3 2003/09/01 20:44:54 markus 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); | |
46 | static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt); | |
47 | static void input_gssapi_errtok(int, u_int32_t, void *); | |
48 | ||
49 | /* | |
50 | * We only support those mechanisms that we know about (ie ones that we know | |
51 | * how to check local user kuserok and the like | |
52 | */ | |
53 | static int | |
54 | userauth_gssapi(Authctxt *authctxt) | |
55 | { | |
56 | gss_OID_desc oid = {0, NULL}; | |
57 | Gssctxt *ctxt = NULL; | |
58 | int mechs; | |
59 | gss_OID_set supported; | |
60 | int present; | |
61 | OM_uint32 ms; | |
62 | u_int len; | |
63 | char *doid = NULL; | |
64 | ||
65 | if (!authctxt->valid || authctxt->user == NULL) | |
66 | return (0); | |
67 | ||
68 | mechs = packet_get_int(); | |
69 | if (mechs == 0) { | |
70 | debug("Mechanism negotiation is not supported"); | |
71 | return (0); | |
72 | } | |
73 | ||
74 | ssh_gssapi_supported_oids(&supported); | |
75 | do { | |
76 | mechs--; | |
77 | ||
78 | if (doid) | |
79 | xfree(doid); | |
80 | ||
81 | doid = packet_get_string(&len); | |
82 | ||
9cb1827b | 83 | if (doid[0] != SSH_GSS_OIDTYPE || doid[1] != len-2) { |
84 | logit("Mechanism OID received using the old encoding form"); | |
85 | oid.elements = doid; | |
86 | oid.length = len; | |
87 | } else { | |
0fff78ff | 88 | oid.elements = doid + 2; |
89 | oid.length = len - 2; | |
90 | } | |
9cb1827b | 91 | gss_test_oid_set_member(&ms, &oid, supported, &present); |
0fff78ff | 92 | } while (mechs > 0 && !present); |
93 | ||
94 | gss_release_oid_set(&ms, &supported); | |
95 | ||
96 | if (!present) { | |
97 | xfree(doid); | |
98 | return (0); | |
99 | } | |
100 | ||
101 | if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid)))) { | |
102 | xfree(doid); | |
103 | return (0); | |
104 | } | |
105 | ||
106 | authctxt->methoddata=(void *)ctxt; | |
107 | ||
108 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE); | |
109 | ||
9cb1827b | 110 | /* Return OID in same format as we received it*/ |
0fff78ff | 111 | packet_put_string(doid, len); |
112 | ||
113 | packet_send(); | |
114 | xfree(doid); | |
115 | ||
116 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token); | |
117 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok); | |
118 | authctxt->postponed = 1; | |
119 | ||
120 | return (0); | |
121 | } | |
122 | ||
123 | static void | |
124 | input_gssapi_token(int type, u_int32_t plen, void *ctxt) | |
125 | { | |
126 | Authctxt *authctxt = ctxt; | |
127 | Gssctxt *gssctxt; | |
128 | gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; | |
129 | gss_buffer_desc recv_tok; | |
9cb1827b | 130 | OM_uint32 maj_status, min_status; |
0fff78ff | 131 | u_int len; |
132 | ||
133 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) | |
134 | fatal("No authentication or GSSAPI context"); | |
135 | ||
136 | gssctxt = authctxt->methoddata; | |
137 | recv_tok.value = packet_get_string(&len); | |
138 | recv_tok.length = len; /* u_int vs. size_t */ | |
139 | ||
140 | packet_check_eom(); | |
141 | ||
142 | maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, | |
9cb1827b | 143 | &send_tok, NULL)); |
0fff78ff | 144 | |
145 | xfree(recv_tok.value); | |
146 | ||
147 | if (GSS_ERROR(maj_status)) { | |
148 | if (send_tok.length != 0) { | |
149 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK); | |
150 | packet_put_string(send_tok.value, send_tok.length); | |
151 | packet_send(); | |
152 | } | |
153 | authctxt->postponed = 0; | |
154 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
9cb1827b | 155 | userauth_finish(authctxt, 0, "gssapi"); |
0fff78ff | 156 | } else { |
157 | if (send_tok.length != 0) { | |
158 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); | |
159 | packet_put_string(send_tok.value, send_tok.length); | |
160 | packet_send(); | |
161 | } | |
162 | if (maj_status == GSS_S_COMPLETE) { | |
163 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
9cb1827b | 164 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, |
165 | &input_gssapi_exchange_complete); | |
0fff78ff | 166 | } |
167 | } | |
168 | ||
169 | gss_release_buffer(&min_status, &send_tok); | |
170 | } | |
171 | ||
172 | static void | |
173 | input_gssapi_errtok(int type, u_int32_t plen, void *ctxt) | |
174 | { | |
175 | Authctxt *authctxt = ctxt; | |
176 | Gssctxt *gssctxt; | |
177 | gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; | |
178 | gss_buffer_desc recv_tok; | |
179 | OM_uint32 maj_status; | |
180 | u_int len; | |
181 | ||
182 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) | |
183 | fatal("No authentication or GSSAPI context"); | |
184 | ||
185 | gssctxt = authctxt->methoddata; | |
186 | recv_tok.value = packet_get_string(&len); | |
187 | recv_tok.length = len; | |
188 | ||
189 | packet_check_eom(); | |
190 | ||
191 | /* Push the error token into GSSAPI to see what it says */ | |
192 | maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, | |
193 | &send_tok, NULL)); | |
194 | ||
195 | xfree(recv_tok.value); | |
196 | ||
197 | /* We can't return anything to the client, even if we wanted to */ | |
198 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
199 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); | |
200 | ||
201 | /* The client will have already moved on to the next auth */ | |
202 | ||
203 | gss_release_buffer(&maj_status, &send_tok); | |
204 | } | |
205 | ||
206 | /* | |
207 | * This is called when the client thinks we've completed authentication. | |
208 | * It should only be enabled in the dispatch handler by the function above, | |
209 | * which only enables it once the GSSAPI exchange is complete. | |
210 | */ | |
211 | ||
212 | static void | |
213 | input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt) | |
214 | { | |
215 | Authctxt *authctxt = ctxt; | |
216 | Gssctxt *gssctxt; | |
217 | int authenticated; | |
218 | ||
219 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) | |
220 | fatal("No authentication or GSSAPI context"); | |
221 | ||
222 | gssctxt = authctxt->methoddata; | |
223 | ||
224 | /* | |
9cb1827b | 225 | * We don't need to check the status, because the stored credentials |
226 | * which userok uses are only populated once the context init step | |
227 | * has returned complete. | |
0fff78ff | 228 | */ |
229 | ||
230 | packet_check_eom(); | |
231 | ||
232 | authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); | |
233 | ||
234 | authctxt->postponed = 0; | |
235 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
236 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL); | |
237 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); | |
9cb1827b | 238 | userauth_finish(authctxt, authenticated, "gssapi"); |
0fff78ff | 239 | } |
240 | ||
241 | Authmethod method_gssapi = { | |
9cb1827b | 242 | "gssapi", |
0fff78ff | 243 | userauth_gssapi, |
244 | &options.gss_authentication | |
245 | }; | |
246 | ||
247 | #endif /* GSSAPI */ |