Annotation of src/usr.bin/ssh/auth2-gss.c, Revision 1.10
1.10 ! djm 1: /* $OpenBSD: auth2-gss.c,v 1.9 2005/06/17 02:44:32 djm 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 "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);
1.6 markus 46: static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt);
1.1 markus 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: {
1.8 avsm 57: gss_OID_desc goid = {0, NULL};
1.1 markus 58: Gssctxt *ctxt = NULL;
59: int mechs;
60: gss_OID_set supported;
61: int present;
62: OM_uint32 ms;
63: u_int len;
1.9 djm 64: u_char *doid = NULL;
1.1 markus 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:
1.5 markus 82: present = 0;
1.1 markus 83: doid = packet_get_string(&len);
84:
1.10 ! djm 85: if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
! 86: doid[1] == len - 2) {
1.8 avsm 87: goid.elements = doid + 2;
88: goid.length = len - 2;
89: gss_test_oid_set_member(&ms, &goid, supported,
1.5 markus 90: &present);
1.1 markus 91: } else {
1.5 markus 92: logit("Badly formed OID received");
1.1 markus 93: }
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:
1.8 avsm 103: if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
1.3 markus 104: xfree(doid);
1.1 markus 105: return (0);
1.3 markus 106: }
1.1 markus 107:
108: authctxt->methoddata=(void *)ctxt;
109:
110: packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
111:
1.5 markus 112: /* Return the OID that we received */
1.1 markus 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;
1.6 markus 132: OM_uint32 maj_status, min_status, flags;
1.1 markus 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,
1.6 markus 145: &send_tok, &flags));
1.1 markus 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);
1.6 markus 157: userauth_finish(authctxt, 0, "gssapi-with-mic");
1.1 markus 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);
1.6 markus 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);
1.1 markus 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;
1.2 deraadt 187: u_int len;
1.1 markus 188:
189: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
190: fatal("No authentication or GSSAPI context");
191:
192: gssctxt = authctxt->methoddata;
1.2 deraadt 193: recv_tok.value = packet_get_string(&len);
194: recv_tok.length = len;
1.1 markus 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: /*
1.6 markus 232: * We don't need to check the status, because we're only enabled in
233: * the dispatcher once the exchange is complete
1.1 markus 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);
1.6 markus 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;
1.7 djm 257:
1.6 markus 258: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
259: fatal("No authentication or GSSAPI context");
1.7 djm 260:
1.6 markus 261: gssctxt = authctxt->methoddata;
1.7 djm 262:
1.6 markus 263: mic.value = packet_get_string(&len);
264: mic.length = len;
1.7 djm 265:
1.6 markus 266: ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
267: "gssapi-with-mic");
1.7 djm 268:
1.6 markus 269: gssbuf.value = buffer_ptr(&b);
270: gssbuf.length = buffer_len(&b);
1.7 djm 271:
1.6 markus 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);
1.7 djm 279:
1.6 markus 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);
1.1 markus 284: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
1.6 markus 285: userauth_finish(authctxt, authenticated, "gssapi-with-mic");
1.1 markus 286: }
287:
288: Authmethod method_gssapi = {
1.6 markus 289: "gssapi-with-mic",
1.1 markus 290: userauth_gssapi,
291: &options.gss_authentication
292: };
293:
294: #endif /* GSSAPI */
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