Annotation of src/usr.bin/ssh/auth2-gss.c, Revision 1.2
1.2 ! deraadt 1: /* $OpenBSD: auth2-gss.c,v 1.1 2003/08/22 10:56:08 markus 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);
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:
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 {
88: oid.elements = doid + 2;
89: oid.length = len - 2;
90: }
91: gss_test_oid_set_member(&ms, &oid, supported, &present);
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: return (0);
103:
104: authctxt->methoddata=(void *)ctxt;
105:
106: packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
107:
108: /* Return OID in same format as we received it*/
109: packet_put_string(doid, len);
110:
111: packet_send();
112: xfree(doid);
113:
114: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
115: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
116: authctxt->postponed = 1;
117:
118: return (0);
119: }
120:
121: static void
122: input_gssapi_token(int type, u_int32_t plen, void *ctxt)
123: {
124: Authctxt *authctxt = ctxt;
125: Gssctxt *gssctxt;
126: gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
127: gss_buffer_desc recv_tok;
128: OM_uint32 maj_status, min_status;
129: u_int len;
130:
131: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
132: fatal("No authentication or GSSAPI context");
133:
134: gssctxt = authctxt->methoddata;
135: recv_tok.value = packet_get_string(&len);
136: recv_tok.length = len; /* u_int vs. size_t */
137:
138: packet_check_eom();
139:
140: maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
141: &send_tok, NULL));
142:
143: xfree(recv_tok.value);
144:
145: if (GSS_ERROR(maj_status)) {
146: if (send_tok.length != 0) {
147: packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
148: packet_put_string(send_tok.value, send_tok.length);
149: packet_send();
150: }
151: authctxt->postponed = 0;
152: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
153: userauth_finish(authctxt, 0, "gssapi");
154: } else {
155: if (send_tok.length != 0) {
156: packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
157: packet_put_string(send_tok.value, send_tok.length);
158: packet_send();
159: }
160: if (maj_status == GSS_S_COMPLETE) {
161: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
162: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
163: &input_gssapi_exchange_complete);
164: }
165: }
166:
167: gss_release_buffer(&min_status, &send_tok);
168: }
169:
170: static void
171: input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
172: {
173: Authctxt *authctxt = ctxt;
174: Gssctxt *gssctxt;
175: gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
176: gss_buffer_desc recv_tok;
177: OM_uint32 maj_status;
1.2 ! deraadt 178: u_int len;
1.1 markus 179:
180: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
181: fatal("No authentication or GSSAPI context");
182:
183: gssctxt = authctxt->methoddata;
1.2 ! deraadt 184: recv_tok.value = packet_get_string(&len);
! 185: recv_tok.length = len;
1.1 markus 186:
187: packet_check_eom();
188:
189: /* Push the error token into GSSAPI to see what it says */
190: maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
191: &send_tok, NULL));
192:
193: xfree(recv_tok.value);
194:
195: /* We can't return anything to the client, even if we wanted to */
196: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
197: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
198:
199: /* The client will have already moved on to the next auth */
200:
201: gss_release_buffer(&maj_status, &send_tok);
202: }
203:
204: /*
205: * This is called when the client thinks we've completed authentication.
206: * It should only be enabled in the dispatch handler by the function above,
207: * which only enables it once the GSSAPI exchange is complete.
208: */
209:
210: static void
211: input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
212: {
213: Authctxt *authctxt = ctxt;
214: Gssctxt *gssctxt;
215: int authenticated;
216:
217: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
218: fatal("No authentication or GSSAPI context");
219:
220: gssctxt = authctxt->methoddata;
221:
222: /*
223: * We don't need to check the status, because the stored credentials
224: * which userok uses are only populated once the context init step
225: * has returned complete.
226: */
227:
228: packet_check_eom();
229:
230: authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
231:
232: authctxt->postponed = 0;
233: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
234: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
235: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
236: userauth_finish(authctxt, authenticated, "gssapi");
237: }
238:
239: Authmethod method_gssapi = {
240: "gssapi",
241: userauth_gssapi,
242: &options.gss_authentication
243: };
244:
245: #endif /* GSSAPI */
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