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b59afbfe | 1 | /* |
2 | * Copyright (c) 2001,2002 Simon Wilkinson. All rights reserved. | |
3 | * | |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
7 | * 1. Redistributions of source code must retain the above copyright | |
8 | * notice, this list of conditions and the following disclaimer. | |
9 | * 2. Redistributions in binary form must reproduce the above copyright | |
10 | * notice, this list of conditions and the following disclaimer in the | |
11 | * documentation and/or other materials provided with the distribution. | |
12 | * | |
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AS IS'' AND ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
23 | */ | |
24 | ||
25 | #include "includes.h" | |
26 | ||
27 | #ifdef GSSAPI | |
28 | #include "auth.h" | |
29 | #include "ssh2.h" | |
30 | #include "ssh1.h" | |
31 | #include "xmalloc.h" | |
32 | #include "log.h" | |
33 | #include "dispatch.h" | |
34 | #include "servconf.h" | |
35 | #include "compat.h" | |
36 | #include "packet.h" | |
37 | #include "monitor_wrap.h" | |
38 | ||
39 | #include "ssh-gss.h" | |
40 | ||
41 | extern ServerOptions options; | |
42 | extern unsigned char ssh1_key_digest[16]; | |
43 | ||
44 | static int | |
45 | userauth_external(Authctxt *authctxt) | |
46 | { | |
47 | packet_check_eom(); | |
48 | ||
49 | return(PRIVSEP(ssh_gssapi_userok(authctxt->user))); | |
50 | } | |
51 | ||
52 | static void input_gssapi_token(int type, u_int32_t plen, void *ctxt); | |
53 | static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt); | |
54 | ||
55 | /* We only support those mechanisms that we know about (ie ones that we know | |
56 | * how to check local user kuserok and the like | |
57 | */ | |
58 | static int | |
59 | userauth_gssapi(Authctxt *authctxt) | |
60 | { | |
61 | gss_OID_desc oid= {0,NULL}; | |
62 | Gssctxt *ctxt = NULL; | |
63 | int mechs; | |
64 | gss_OID_set supported; | |
65 | int present; | |
66 | OM_uint32 ms; | |
67 | u_int len; | |
68 | ||
69 | if (!authctxt->valid || authctxt->user == NULL) | |
70 | return 0; | |
71 | ||
72 | if (datafellows & SSH_OLD_GSSAPI) { | |
73 | debug("Early drafts of GSSAPI userauth not supported"); | |
74 | return 0; | |
75 | } | |
76 | ||
77 | mechs=packet_get_int(); | |
78 | if (mechs==0) { | |
79 | debug("Mechanism negotiation is not supported"); | |
80 | return 0; | |
81 | } | |
82 | ||
83 | ssh_gssapi_supported_oids(&supported); | |
84 | do { | |
85 | if (oid.elements) | |
86 | xfree(oid.elements); | |
87 | oid.elements = packet_get_string(&len); | |
88 | oid.length = len; | |
89 | gss_test_oid_set_member(&ms, &oid, supported, &present); | |
90 | mechs--; | |
91 | } while (mechs>0 && !present); | |
92 | ||
93 | if (!present) { | |
94 | xfree(oid.elements); | |
95 | return(0); | |
96 | } | |
97 | ||
98 | if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt,&oid)))) | |
99 | return(0); | |
100 | ||
101 | authctxt->methoddata=(void *)ctxt; | |
102 | ||
103 | /* Send SSH_MSG_USERAUTH_GSSAPI_RESPONSE */ | |
104 | ||
105 | if (!compat20) | |
106 | packet_start(SSH_SMSG_AUTH_GSSAPI_RESPONSE); | |
107 | else | |
108 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE); | |
109 | packet_put_string(oid.elements,oid.length); | |
110 | packet_send(); | |
111 | packet_write_wait(); | |
112 | xfree(oid.elements); | |
113 | ||
114 | if (!compat20) | |
115 | dispatch_set(SSH_MSG_AUTH_GSSAPI_TOKEN, | |
116 | &input_gssapi_token); | |
117 | else | |
118 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, | |
119 | &input_gssapi_token); | |
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,recv_tok; | |
131 | OM_uint32 maj_status, min_status; | |
007914b3 | 132 | int len; |
b59afbfe | 133 | |
134 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) | |
135 | fatal("No authentication or GSSAPI context"); | |
136 | ||
137 | gssctxt=authctxt->methoddata; | |
007914b3 | 138 | recv_tok.value=packet_get_string(&len); |
139 | recv_tok.length=len; /* int vs. size_t */ | |
b59afbfe | 140 | |
141 | maj_status=PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok, | |
142 | &send_tok, NULL)); | |
143 | packet_check_eom(); | |
144 | ||
b59afbfe | 145 | if (send_tok.length != 0) { |
146 | /* Send a packet back to the client */ | |
147 | if (!compat20) | |
148 | packet_start(SSH_MSG_AUTH_GSSAPI_TOKEN); | |
149 | else | |
150 | packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN); | |
151 | packet_put_string(send_tok.value,send_tok.length); | |
152 | packet_send(); | |
153 | packet_write_wait(); | |
154 | gss_release_buffer(&min_status, &send_tok); | |
155 | } | |
156 | ||
705f2ba4 | 157 | if (GSS_ERROR(maj_status)) { |
158 | /* Failure <sniff> */ | |
e8bbb925 | 159 | if (gssctxt) { /* may be NULL under privsep */ |
160 | ssh_gssapi_send_error(gssctxt->oid,maj_status,min_status); | |
161 | } else { | |
162 | ssh_gssapi_send_error(GSS_C_NO_OID,maj_status,min_status); | |
163 | } | |
705f2ba4 | 164 | authctxt->postponed = 0; |
165 | dispatch_set(SSH_MSG_AUTH_GSSAPI_TOKEN, NULL); | |
166 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
167 | userauth_finish(authctxt, 0, "gssapi"); | |
168 | } | |
169 | ||
b59afbfe | 170 | if (maj_status == GSS_S_COMPLETE) { |
171 | dispatch_set(SSH_MSG_AUTH_GSSAPI_TOKEN, NULL); | |
172 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN,NULL); | |
173 | /* ssh1 does not have an extra message here */ | |
174 | if (!compat20) | |
175 | input_gssapi_exchange_complete(0, 0, ctxt); | |
176 | else | |
177 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, | |
178 | &input_gssapi_exchange_complete); | |
179 | } | |
180 | } | |
181 | ||
182 | /* This is called when the client thinks we've completed authentication. | |
183 | * It should only be enabled in the dispatch handler by the function above, | |
184 | * which only enables it once the GSSAPI exchange is complete. | |
185 | */ | |
186 | ||
187 | static void | |
188 | input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt) | |
189 | { | |
190 | Authctxt *authctxt = ctxt; | |
191 | Gssctxt *gssctxt; | |
192 | int authenticated; | |
193 | ||
194 | if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep)) | |
195 | fatal("No authentication or GSSAPI context"); | |
196 | ||
d13dfff4 | 197 | if ((strcmp(authctxt->user, "") == 0) && (authctxt->pw == NULL)) { |
198 | char *lname = NULL; | |
199 | PRIVSEP(ssh_gssapi_localname(&lname)); | |
200 | if (lname && lname[0] != '\0') { | |
201 | xfree(authctxt->user); | |
202 | authctxt->user = lname; | |
203 | debug("set username to %s from gssapi context", lname); | |
204 | authctxt->pw = PRIVSEP(getpwnamallow(authctxt->user)); | |
205 | } else { | |
206 | debug("failed to set username from gssapi context"); | |
207 | } | |
208 | } | |
209 | if (authctxt->pw) { | |
210 | #ifdef USE_PAM | |
211 | PRIVSEP(start_pam(authctxt->pw->pw_name)); | |
212 | #endif | |
213 | } else { | |
214 | authctxt->valid = 0; | |
215 | authenticated = 0; | |
216 | goto finish; | |
217 | } | |
218 | ||
b59afbfe | 219 | gssctxt=authctxt->methoddata; |
220 | ||
221 | /* ssh1 needs to exchange the hash of the keys */ | |
222 | if (!compat20) { | |
223 | ||
224 | OM_uint32 min_status; | |
225 | gss_buffer_desc dummy, msg_tok; | |
226 | ||
227 | /* ssh1 wraps the keys, in the monitor */ | |
228 | ||
229 | dummy.value=malloc(sizeof(ssh1_key_digest)); | |
230 | memcpy(dummy.value,ssh1_key_digest,sizeof(ssh1_key_digest)); | |
231 | dummy.length=sizeof(ssh1_key_digest); | |
232 | if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(gssctxt,&dummy,&msg_tok)))) | |
233 | fatal("Couldn't wrap keys"); | |
234 | ||
235 | packet_start(SSH_SMSG_AUTH_GSSAPI_HASH); | |
236 | packet_put_string((char *)msg_tok.value,msg_tok.length); | |
237 | packet_send(); | |
238 | packet_write_wait(); | |
239 | gss_release_buffer(&min_status,&msg_tok); | |
240 | } | |
241 | ||
242 | ||
243 | /* We don't need to check the status, because the stored credentials | |
244 | * which userok uses are only populated once the context init step | |
245 | * has returned complete. | |
246 | */ | |
247 | ||
248 | authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user)); | |
249 | ||
d13dfff4 | 250 | finish: |
b59afbfe | 251 | authctxt->postponed = 0; |
252 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
253 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); | |
254 | userauth_finish(authctxt, authenticated, "gssapi"); | |
255 | } | |
256 | ||
257 | Authmethod method_external = { | |
258 | "external-keyx", | |
259 | userauth_external, | |
260 | &options.gss_authentication | |
261 | }; | |
262 | ||
263 | Authmethod method_gssapi = { | |
264 | "gssapi", | |
265 | userauth_gssapi, | |
266 | &options.gss_authentication | |
267 | }; | |
268 | ||
269 | #endif /* GSSAPI */ |