Annotation of src/usr.bin/ssh/auth2-gss.c, Revision 1.20
1.20 ! djm 1: /* $OpenBSD: auth2-gss.c,v 1.19 2013/04/05 00:14:00 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:
1.16 dtucker 27: #ifdef GSSAPI
28:
1.15 deraadt 29: #include <sys/types.h>
1.1 markus 30:
1.15 deraadt 31: #include "xmalloc.h"
32: #include "key.h"
33: #include "hostfile.h"
1.1 markus 34: #include "auth.h"
35: #include "ssh2.h"
36: #include "log.h"
37: #include "dispatch.h"
1.15 deraadt 38: #include "buffer.h"
1.1 markus 39: #include "servconf.h"
40: #include "packet.h"
1.15 deraadt 41: #include "ssh-gss.h"
1.1 markus 42: #include "monitor_wrap.h"
43:
44: extern ServerOptions options;
45:
46: static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
1.6 markus 47: static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt);
1.1 markus 48: static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
49: static void input_gssapi_errtok(int, u_int32_t, void *);
50:
51: /*
52: * We only support those mechanisms that we know about (ie ones that we know
1.12 stevesk 53: * how to check local user kuserok and the like)
1.1 markus 54: */
55: static int
56: userauth_gssapi(Authctxt *authctxt)
57: {
1.8 avsm 58: gss_OID_desc goid = {0, NULL};
1.1 markus 59: Gssctxt *ctxt = NULL;
60: int mechs;
61: gss_OID_set supported;
62: int present;
63: OM_uint32 ms;
64: u_int len;
1.9 djm 65: u_char *doid = NULL;
1.1 markus 66:
67: if (!authctxt->valid || authctxt->user == NULL)
68: return (0);
69:
70: mechs = packet_get_int();
71: if (mechs == 0) {
72: debug("Mechanism negotiation is not supported");
73: return (0);
74: }
75:
76: ssh_gssapi_supported_oids(&supported);
77: do {
78: mechs--;
79:
1.20 ! djm 80: free(doid);
1.1 markus 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) {
1.20 ! djm 99: free(doid);
1.17 djm 100: authctxt->server_caused_failure = 1;
1.1 markus 101: return (0);
102: }
103:
1.8 avsm 104: if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
1.13 djm 105: if (ctxt != NULL)
106: ssh_gssapi_delete_ctx(&ctxt);
1.20 ! djm 107: free(doid);
1.17 djm 108: authctxt->server_caused_failure = 1;
1.1 markus 109: return (0);
1.3 markus 110: }
1.1 markus 111:
1.12 stevesk 112: authctxt->methoddata = (void *)ctxt;
1.1 markus 113:
114: packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
115:
1.5 markus 116: /* Return the OID that we received */
1.1 markus 117: packet_put_string(doid, len);
118:
119: packet_send();
1.20 ! djm 120: free(doid);
1.1 markus 121:
122: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
123: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
124: authctxt->postponed = 1;
125:
126: return (0);
127: }
128:
129: static void
130: input_gssapi_token(int type, u_int32_t plen, void *ctxt)
131: {
132: Authctxt *authctxt = ctxt;
133: Gssctxt *gssctxt;
134: gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
135: gss_buffer_desc recv_tok;
1.6 markus 136: OM_uint32 maj_status, min_status, flags;
1.1 markus 137: u_int len;
138:
139: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
140: fatal("No authentication or GSSAPI context");
141:
142: gssctxt = authctxt->methoddata;
143: recv_tok.value = packet_get_string(&len);
144: recv_tok.length = len; /* u_int vs. size_t */
145:
146: packet_check_eom();
147:
148: maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
1.6 markus 149: &send_tok, &flags));
1.1 markus 150:
1.20 ! djm 151: free(recv_tok.value);
1.1 markus 152:
153: if (GSS_ERROR(maj_status)) {
154: if (send_tok.length != 0) {
155: packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
156: packet_put_string(send_tok.value, send_tok.length);
157: packet_send();
158: }
159: authctxt->postponed = 0;
160: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
1.18 djm 161: userauth_finish(authctxt, 0, "gssapi-with-mic", NULL);
1.1 markus 162: } else {
163: if (send_tok.length != 0) {
164: packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
165: packet_put_string(send_tok.value, send_tok.length);
166: packet_send();
167: }
168: if (maj_status == GSS_S_COMPLETE) {
169: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
1.6 markus 170: if (flags & GSS_C_INTEG_FLAG)
171: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC,
172: &input_gssapi_mic);
173: else
174: dispatch_set(
175: SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
176: &input_gssapi_exchange_complete);
1.1 markus 177: }
178: }
179:
180: gss_release_buffer(&min_status, &send_tok);
181: }
182:
183: static void
184: input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
185: {
186: Authctxt *authctxt = ctxt;
187: Gssctxt *gssctxt;
188: gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
189: gss_buffer_desc recv_tok;
190: OM_uint32 maj_status;
1.2 deraadt 191: u_int len;
1.1 markus 192:
193: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
194: fatal("No authentication or GSSAPI context");
195:
196: gssctxt = authctxt->methoddata;
1.2 deraadt 197: recv_tok.value = packet_get_string(&len);
198: recv_tok.length = len;
1.1 markus 199:
200: packet_check_eom();
201:
202: /* Push the error token into GSSAPI to see what it says */
203: maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
204: &send_tok, NULL));
205:
1.20 ! djm 206: free(recv_tok.value);
1.1 markus 207:
208: /* We can't return anything to the client, even if we wanted to */
209: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
210: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
211:
212: /* The client will have already moved on to the next auth */
213:
214: gss_release_buffer(&maj_status, &send_tok);
215: }
216:
217: /*
218: * This is called when the client thinks we've completed authentication.
219: * It should only be enabled in the dispatch handler by the function above,
220: * which only enables it once the GSSAPI exchange is complete.
221: */
222:
223: static void
224: input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
225: {
226: Authctxt *authctxt = ctxt;
227: int authenticated;
228:
229: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
230: fatal("No authentication or GSSAPI context");
231:
232: /*
1.6 markus 233: * We don't need to check the status, because we're only enabled in
234: * the dispatcher once the exchange is complete
1.1 markus 235: */
236:
237: packet_check_eom();
238:
239: authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
240:
241: authctxt->postponed = 0;
242: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
243: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
1.6 markus 244: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
245: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
1.18 djm 246: userauth_finish(authctxt, authenticated, "gssapi-with-mic", NULL);
1.6 markus 247: }
248:
249: static void
250: input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
251: {
252: Authctxt *authctxt = ctxt;
253: Gssctxt *gssctxt;
254: int authenticated = 0;
255: Buffer b;
256: gss_buffer_desc mic, gssbuf;
257: u_int len;
1.7 djm 258:
1.6 markus 259: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
260: fatal("No authentication or GSSAPI context");
1.7 djm 261:
1.6 markus 262: gssctxt = authctxt->methoddata;
1.7 djm 263:
1.6 markus 264: mic.value = packet_get_string(&len);
265: mic.length = len;
1.7 djm 266:
1.6 markus 267: ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
268: "gssapi-with-mic");
1.7 djm 269:
1.6 markus 270: gssbuf.value = buffer_ptr(&b);
271: gssbuf.length = buffer_len(&b);
1.7 djm 272:
1.6 markus 273: if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
274: authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
275: else
276: logit("GSSAPI MIC check failed");
277:
278: buffer_free(&b);
1.20 ! djm 279: free(mic.value);
1.7 djm 280:
1.6 markus 281: authctxt->postponed = 0;
282: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
283: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
284: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
1.1 markus 285: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
1.18 djm 286: userauth_finish(authctxt, authenticated, "gssapi-with-mic", NULL);
1.1 markus 287: }
288:
289: Authmethod method_gssapi = {
1.6 markus 290: "gssapi-with-mic",
1.1 markus 291: userauth_gssapi,
292: &options.gss_authentication
293: };
1.16 dtucker 294: #endif
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