Annotation of src/usr.bin/ssh/auth2-gss.c, Revision 1.23
1.23 ! markus 1: /* $OpenBSD: auth2-gss.c,v 1.22 2015/01/19 20:07:45 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:
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:
1.22 markus 46: static int input_gssapi_token(int type, u_int32_t plen, void *ctxt);
47: static int input_gssapi_mic(int type, u_int32_t plen, void *ctxt);
48: static int input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
49: static int input_gssapi_errtok(int, u_int32_t, void *);
1.1 markus 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: 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: do {
76: mechs--;
77:
1.20 djm 78: free(doid);
1.1 markus 79:
1.5 markus 80: present = 0;
1.1 markus 81: doid = packet_get_string(&len);
82:
1.10 djm 83: if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
84: doid[1] == len - 2) {
1.8 avsm 85: goid.elements = doid + 2;
86: goid.length = len - 2;
1.21 djm 87: ssh_gssapi_test_oid_supported(&ms, &goid, &present);
1.1 markus 88: } else {
1.5 markus 89: logit("Badly formed OID received");
1.1 markus 90: }
91: } while (mechs > 0 && !present);
92:
93: if (!present) {
1.20 djm 94: free(doid);
1.17 djm 95: authctxt->server_caused_failure = 1;
1.1 markus 96: return (0);
97: }
98:
1.8 avsm 99: if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
1.13 djm 100: if (ctxt != NULL)
101: ssh_gssapi_delete_ctx(&ctxt);
1.20 djm 102: free(doid);
1.17 djm 103: authctxt->server_caused_failure = 1;
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();
1.20 djm 115: free(doid);
1.1 markus 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:
1.22 markus 124: static int
1.1 markus 125: input_gssapi_token(int type, u_int32_t plen, void *ctxt)
126: {
1.23 ! markus 127: struct ssh *ssh = ctxt;
! 128: Authctxt *authctxt = ssh->authctxt;
1.1 markus 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:
1.20 djm 147: free(recv_tok.value);
1.1 markus 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);
1.18 djm 157: userauth_finish(authctxt, 0, "gssapi-with-mic", NULL);
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);
1.22 markus 177: return 0;
1.1 markus 178: }
179:
1.22 markus 180: static int
1.1 markus 181: input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
182: {
1.23 ! markus 183: struct ssh *ssh = ctxt;
! 184: Authctxt *authctxt = ssh->authctxt;
1.1 markus 185: Gssctxt *gssctxt;
186: gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
187: gss_buffer_desc recv_tok;
188: OM_uint32 maj_status;
1.2 deraadt 189: u_int len;
1.1 markus 190:
191: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
192: fatal("No authentication or GSSAPI context");
193:
194: gssctxt = authctxt->methoddata;
1.2 deraadt 195: recv_tok.value = packet_get_string(&len);
196: recv_tok.length = len;
1.1 markus 197:
198: packet_check_eom();
199:
200: /* Push the error token into GSSAPI to see what it says */
201: maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
202: &send_tok, NULL));
203:
1.20 djm 204: free(recv_tok.value);
1.1 markus 205:
206: /* We can't return anything to the client, even if we wanted to */
207: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
208: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
209:
210: /* The client will have already moved on to the next auth */
211:
212: gss_release_buffer(&maj_status, &send_tok);
1.22 markus 213: return 0;
1.1 markus 214: }
215:
216: /*
217: * This is called when the client thinks we've completed authentication.
218: * It should only be enabled in the dispatch handler by the function above,
219: * which only enables it once the GSSAPI exchange is complete.
220: */
221:
1.22 markus 222: static int
1.1 markus 223: input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
224: {
1.23 ! markus 225: struct ssh *ssh = ctxt;
! 226: Authctxt *authctxt = ssh->authctxt;
1.1 markus 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);
1.22 markus 247: return 0;
1.6 markus 248: }
249:
1.22 markus 250: static int
1.6 markus 251: input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
252: {
1.23 ! markus 253: struct ssh *ssh = ctxt;
! 254: Authctxt *authctxt = ssh->authctxt;
1.6 markus 255: Gssctxt *gssctxt;
256: int authenticated = 0;
257: Buffer b;
258: gss_buffer_desc mic, gssbuf;
259: u_int len;
1.7 djm 260:
1.6 markus 261: if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
262: fatal("No authentication or GSSAPI context");
1.7 djm 263:
1.6 markus 264: gssctxt = authctxt->methoddata;
1.7 djm 265:
1.6 markus 266: mic.value = packet_get_string(&len);
267: mic.length = len;
1.7 djm 268:
1.6 markus 269: ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
270: "gssapi-with-mic");
1.7 djm 271:
1.6 markus 272: gssbuf.value = buffer_ptr(&b);
273: gssbuf.length = buffer_len(&b);
1.7 djm 274:
1.6 markus 275: if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
276: authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
277: else
278: logit("GSSAPI MIC check failed");
279:
280: buffer_free(&b);
1.20 djm 281: free(mic.value);
1.7 djm 282:
1.6 markus 283: authctxt->postponed = 0;
284: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
285: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
286: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
1.1 markus 287: dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
1.18 djm 288: userauth_finish(authctxt, authenticated, "gssapi-with-mic", NULL);
1.22 markus 289: return 0;
1.1 markus 290: }
291:
292: Authmethod method_gssapi = {
1.6 markus 293: "gssapi-with-mic",
1.1 markus 294: userauth_gssapi,
295: &options.gss_authentication
296: };
1.16 dtucker 297: #endif
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