Annotation of src/usr.bin/ssh/auth2-gss.c, Revision 1.5
1.5 ! markus 1: /* $OpenBSD: auth2-gss.c,v 1.4 2003/10/21 09:50:06 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:
1.5 ! markus 81: present = 0;
1.1 markus 82: doid = packet_get_string(&len);
83:
1.5 ! markus 84: if (len > 2 &&
! 85: doid[0] == SSH_GSS_OIDTYPE &&
! 86: doid[1] == len - 2) {
! 87: oid.elements = doid + 2;
! 88: oid.length = len - 2;
! 89: gss_test_oid_set_member(&ms, &oid, supported,
! 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:
1.3 markus 103: if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid)))) {
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;
132: OM_uint32 maj_status, min_status;
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,
145: &send_tok, NULL));
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);
157: userauth_finish(authctxt, 0, "gssapi");
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);
166: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
167: &input_gssapi_exchange_complete);
168: }
169: }
170:
171: gss_release_buffer(&min_status, &send_tok);
172: }
173:
174: static void
175: input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
176: {
177: Authctxt *authctxt = ctxt;
178: Gssctxt *gssctxt;
179: gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
180: gss_buffer_desc recv_tok;
181: OM_uint32 maj_status;
1.2 deraadt 182: u_int len;
1.1 markus 183:
184: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
185: fatal("No authentication or GSSAPI context");
186:
187: gssctxt = authctxt->methoddata;
1.2 deraadt 188: recv_tok.value = packet_get_string(&len);
189: recv_tok.length = len;
1.1 markus 190:
191: packet_check_eom();
192:
193: /* Push the error token into GSSAPI to see what it says */
194: maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
195: &send_tok, NULL));
196:
197: xfree(recv_tok.value);
198:
199: /* We can't return anything to the client, even if we wanted to */
200: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
201: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
202:
203: /* The client will have already moved on to the next auth */
204:
205: gss_release_buffer(&maj_status, &send_tok);
206: }
207:
208: /*
209: * This is called when the client thinks we've completed authentication.
210: * It should only be enabled in the dispatch handler by the function above,
211: * which only enables it once the GSSAPI exchange is complete.
212: */
213:
214: static void
215: input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
216: {
217: Authctxt *authctxt = ctxt;
218: Gssctxt *gssctxt;
219: int authenticated;
220:
221: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
222: fatal("No authentication or GSSAPI context");
223:
224: gssctxt = authctxt->methoddata;
225:
226: /*
227: * We don't need to check the status, because the stored credentials
228: * which userok uses are only populated once the context init step
229: * has returned complete.
230: */
231:
232: packet_check_eom();
233:
234: authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
235:
236: authctxt->postponed = 0;
237: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
238: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
239: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
240: userauth_finish(authctxt, authenticated, "gssapi");
241: }
242:
243: Authmethod method_gssapi = {
244: "gssapi",
245: userauth_gssapi,
246: &options.gss_authentication
247: };
248:
249: #endif /* GSSAPI */
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