Annotation of src/usr.bin/ssh/auth2-gss.c, Revision 1.12
1.12 ! stevesk 1: /* $OpenBSD: auth2-gss.c,v 1.11 2005/10/13 14:03:01 stevesk Exp $ */
1.1 markus 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 "packet.h"
38: #include "monitor_wrap.h"
39:
40: #include "ssh-gss.h"
41:
42: extern ServerOptions options;
43:
44: static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
1.6 markus 45: static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt);
1.1 markus 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
1.12 ! stevesk 51: * how to check local user kuserok and the like)
1.1 markus 52: */
53: static int
54: userauth_gssapi(Authctxt *authctxt)
55: {
1.8 avsm 56: gss_OID_desc goid = {0, NULL};
1.1 markus 57: Gssctxt *ctxt = NULL;
58: int mechs;
59: gss_OID_set supported;
60: int present;
61: OM_uint32 ms;
62: u_int len;
1.9 djm 63: u_char *doid = NULL;
1.1 markus 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:
1.5 markus 81: present = 0;
1.1 markus 82: doid = packet_get_string(&len);
83:
1.10 djm 84: if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
85: doid[1] == len - 2) {
1.8 avsm 86: goid.elements = doid + 2;
87: goid.length = len - 2;
88: gss_test_oid_set_member(&ms, &goid, supported,
1.5 markus 89: &present);
1.1 markus 90: } else {
1.5 markus 91: logit("Badly formed OID received");
1.1 markus 92: }
93: } while (mechs > 0 && !present);
94:
95: gss_release_oid_set(&ms, &supported);
96:
97: if (!present) {
98: xfree(doid);
99: return (0);
100: }
101:
1.8 avsm 102: if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
1.3 markus 103: xfree(doid);
1.1 markus 104: return (0);
1.3 markus 105: }
1.1 markus 106:
1.12 ! stevesk 107: authctxt->methoddata = (void *)ctxt;
1.1 markus 108:
109: packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
110:
1.5 markus 111: /* Return the OID that we received */
1.1 markus 112: packet_put_string(doid, len);
113:
114: packet_send();
115: xfree(doid);
116:
117: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
118: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
119: authctxt->postponed = 1;
120:
121: return (0);
122: }
123:
124: static void
125: input_gssapi_token(int type, u_int32_t plen, void *ctxt)
126: {
127: Authctxt *authctxt = ctxt;
128: Gssctxt *gssctxt;
129: gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
130: gss_buffer_desc recv_tok;
1.6 markus 131: OM_uint32 maj_status, min_status, flags;
1.1 markus 132: u_int len;
133:
134: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
135: fatal("No authentication or GSSAPI context");
136:
137: gssctxt = authctxt->methoddata;
138: recv_tok.value = packet_get_string(&len);
139: recv_tok.length = len; /* u_int vs. size_t */
140:
141: packet_check_eom();
142:
143: maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
1.6 markus 144: &send_tok, &flags));
1.1 markus 145:
146: xfree(recv_tok.value);
147:
148: if (GSS_ERROR(maj_status)) {
149: if (send_tok.length != 0) {
150: packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
151: packet_put_string(send_tok.value, send_tok.length);
152: packet_send();
153: }
154: authctxt->postponed = 0;
155: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
1.6 markus 156: userauth_finish(authctxt, 0, "gssapi-with-mic");
1.1 markus 157: } else {
158: if (send_tok.length != 0) {
159: packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
160: packet_put_string(send_tok.value, send_tok.length);
161: packet_send();
162: }
163: if (maj_status == GSS_S_COMPLETE) {
164: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
1.6 markus 165: if (flags & GSS_C_INTEG_FLAG)
166: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC,
167: &input_gssapi_mic);
168: else
169: dispatch_set(
170: SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
171: &input_gssapi_exchange_complete);
1.1 markus 172: }
173: }
174:
175: gss_release_buffer(&min_status, &send_tok);
176: }
177:
178: static void
179: input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
180: {
181: Authctxt *authctxt = ctxt;
182: Gssctxt *gssctxt;
183: gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
184: gss_buffer_desc recv_tok;
185: OM_uint32 maj_status;
1.2 deraadt 186: u_int len;
1.1 markus 187:
188: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
189: fatal("No authentication or GSSAPI context");
190:
191: gssctxt = authctxt->methoddata;
1.2 deraadt 192: recv_tok.value = packet_get_string(&len);
193: recv_tok.length = len;
1.1 markus 194:
195: packet_check_eom();
196:
197: /* Push the error token into GSSAPI to see what it says */
198: maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
199: &send_tok, NULL));
200:
201: xfree(recv_tok.value);
202:
203: /* We can't return anything to the client, even if we wanted to */
204: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
205: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
206:
207: /* The client will have already moved on to the next auth */
208:
209: gss_release_buffer(&maj_status, &send_tok);
210: }
211:
212: /*
213: * This is called when the client thinks we've completed authentication.
214: * It should only be enabled in the dispatch handler by the function above,
215: * which only enables it once the GSSAPI exchange is complete.
216: */
217:
218: static void
219: input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
220: {
221: Authctxt *authctxt = ctxt;
222: Gssctxt *gssctxt;
223: int authenticated;
224:
225: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
226: fatal("No authentication or GSSAPI context");
227:
228: gssctxt = authctxt->methoddata;
229:
230: /*
1.6 markus 231: * We don't need to check the status, because we're only enabled in
232: * the dispatcher once the exchange is complete
1.1 markus 233: */
234:
235: packet_check_eom();
236:
237: authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
238:
239: authctxt->postponed = 0;
240: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
241: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
1.6 markus 242: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
243: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
244: userauth_finish(authctxt, authenticated, "gssapi-with-mic");
245: }
246:
247: static void
248: input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
249: {
250: Authctxt *authctxt = ctxt;
251: Gssctxt *gssctxt;
252: int authenticated = 0;
253: Buffer b;
254: gss_buffer_desc mic, gssbuf;
255: u_int len;
1.7 djm 256:
1.6 markus 257: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
258: fatal("No authentication or GSSAPI context");
1.7 djm 259:
1.6 markus 260: gssctxt = authctxt->methoddata;
1.7 djm 261:
1.6 markus 262: mic.value = packet_get_string(&len);
263: mic.length = len;
1.7 djm 264:
1.6 markus 265: ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
266: "gssapi-with-mic");
1.7 djm 267:
1.6 markus 268: gssbuf.value = buffer_ptr(&b);
269: gssbuf.length = buffer_len(&b);
1.7 djm 270:
1.6 markus 271: if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
272: authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
273: else
274: logit("GSSAPI MIC check failed");
275:
276: buffer_free(&b);
277: xfree(mic.value);
1.7 djm 278:
1.6 markus 279: authctxt->postponed = 0;
280: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
281: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
282: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
1.1 markus 283: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
1.6 markus 284: userauth_finish(authctxt, authenticated, "gssapi-with-mic");
1.1 markus 285: }
286:
287: Authmethod method_gssapi = {
1.6 markus 288: "gssapi-with-mic",
1.1 markus 289: userauth_gssapi,
290: &options.gss_authentication
291: };
292:
293: #endif /* GSSAPI */
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