1 /*
2 * Kerberos v5 authentication and ticket-passing routines.
3 *
4 * $FreeBSD: src/crypto/openssh/auth-krb5.c,v 1.6 2001/02/13 16:58:04 assar Exp $
5 */
6 /*
7 * Copyright (c) 2002 Daniel Kouril. All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30 #include "includes.h"
31 RCSID("$OpenBSD: auth-krb5.c,v 1.9 2002/09/09 06:48:06 itojun Exp $");
32
33 #pragma ident "%Z%%M% %I% %E% SMI"
34
35 #include "ssh.h"
36 #include "ssh1.h"
37 #include "packet.h"
38 #include "xmalloc.h"
39 #include "log.h"
40 #include "servconf.h"
41 #include "uidswap.h"
42 #include "auth.h"
43
44 #ifdef KRB5
45 #include <krb5.h>
46 #ifndef HEIMDAL
47 #define krb5_get_err_text(context,code) error_message(code)
48 #endif /* !HEIMDAL */
49
50 extern ServerOptions options;
51
52 static int
53 krb5_init(void *context)
54 {
55 Authctxt *authctxt = (Authctxt *)context;
56 krb5_error_code problem;
57 static int cleanup_registered = 0;
58
59 if (authctxt->krb5_ctx == NULL) {
60 problem = krb5_init_context(&authctxt->krb5_ctx);
61 if (problem)
62 return (problem);
63 krb5_init_ets(authctxt->krb5_ctx);
64 }
65 if (!cleanup_registered) {
66 fatal_add_cleanup(krb5_cleanup_proc, authctxt);
67 cleanup_registered = 1;
68 }
69 return (0);
70 }
71
72 /*
73 * Try krb5 authentication. server_user is passed for logging purposes
74 * only, in auth is received ticket, in client is returned principal
75 * from the ticket
76 */
77 int
78 auth_krb5(Authctxt *authctxt, krb5_data *auth, char **client, krb5_data *reply)
79 {
80 krb5_error_code problem;
81 krb5_principal server;
82 krb5_ticket *ticket;
83 int fd, ret;
84
85 ret = 0;
86 server = NULL;
87 ticket = NULL;
88 reply->length = 0;
89
90 problem = krb5_init(authctxt);
91 if (problem)
92 goto err;
93
94 problem = krb5_auth_con_init(authctxt->krb5_ctx,
95 &authctxt->krb5_auth_ctx);
96 if (problem)
97 goto err;
98
99 fd = packet_get_connection_in();
100 #ifdef HEIMDAL
101 problem = krb5_auth_con_setaddrs_from_fd(authctxt->krb5_ctx,
102 authctxt->krb5_auth_ctx, &fd);
103 #else
104 problem = krb5_auth_con_genaddrs(authctxt->krb5_ctx,
105 authctxt->krb5_auth_ctx,fd,
106 KRB5_AUTH_CONTEXT_GENERATE_REMOTE_FULL_ADDR |
107 KRB5_AUTH_CONTEXT_GENERATE_LOCAL_FULL_ADDR);
108 #endif
109 if (problem)
110 goto err;
111
112 problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL ,
113 KRB5_NT_SRV_HST, &server);
114 if (problem)
115 goto err;
116
117 problem = krb5_rd_req(authctxt->krb5_ctx, &authctxt->krb5_auth_ctx,
118 auth, server, NULL, NULL, &ticket);
119 if (problem)
120 goto err;
121
122 #ifdef HEIMDAL
123 problem = krb5_copy_principal(authctxt->krb5_ctx, ticket->client,
124 &authctxt->krb5_user);
125 #else
126 problem = krb5_copy_principal(authctxt->krb5_ctx,
127 ticket->enc_part2->client,
128 &authctxt->krb5_user);
129 #endif
130 if (problem)
131 goto err;
132
133 /* if client wants mutual auth */
134 problem = krb5_mk_rep(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
135 reply);
136 if (problem)
137 goto err;
138
139 /* Check .k5login authorization now. */
140 if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
141 authctxt->pw->pw_name))
142 goto err;
143
144 if (client)
145 krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
146 client);
147
148 ret = 1;
149 err:
150 if (server)
151 krb5_free_principal(authctxt->krb5_ctx, server);
152 if (ticket)
153 krb5_free_ticket(authctxt->krb5_ctx, ticket);
154 if (!ret && reply->length) {
155 xfree(reply->data);
156 memset(reply, 0, sizeof(*reply));
157 }
158
159 if (problem) {
160 if (authctxt->krb5_ctx != NULL)
161 debug("Kerberos v5 authentication failed: %s",
162 krb5_get_err_text(authctxt->krb5_ctx, problem));
163 else
164 debug("Kerberos v5 authentication failed: %d",
165 problem);
166 }
167
168 return (ret);
169 }
170
171 int
172 auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt)
173 {
174 krb5_error_code problem;
175 krb5_ccache ccache = NULL;
176 char *pname;
177 krb5_creds **creds;
178
179 if (authctxt->pw == NULL || authctxt->krb5_user == NULL)
180 return (0);
181
182 temporarily_use_uid(authctxt->pw);
183
184 #ifdef HEIMDAL
185 problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops, &ccache);
186 #else
187 {
188 char ccname[40];
189 int tmpfd;
190
191 snprintf(ccname,sizeof(ccname),"FILE:/tmp/krb5cc_%d_XXXXXX",geteuid());
192
193 if ((tmpfd = mkstemp(ccname+strlen("FILE:")))==-1) {
194 log("mkstemp(): %.100s", strerror(errno));
195 problem = errno;
196 goto fail;
197 }
198 if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
199 log("fchmod(): %.100s", strerror(errno));
200 close(tmpfd);
201 problem = errno;
202 goto fail;
203 }
204 close(tmpfd);
205 problem = krb5_cc_resolve(authctxt->krb5_ctx, ccname, &ccache);
206 }
207 #endif
208 if (problem)
209 goto fail;
210
211 problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
212 authctxt->krb5_user);
213 if (problem)
214 goto fail;
215
216 #ifdef HEIMDAL
217 problem = krb5_rd_cred2(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
218 ccache, tgt);
219 if (problem)
220 goto fail;
221 #else
222 problem = krb5_rd_cred(authctxt->krb5_ctx, authctxt->krb5_auth_ctx,
223 tgt, &creds, NULL);
224 if (problem)
225 goto fail;
226 problem = krb5_cc_store_cred(authctxt->krb5_ctx, ccache, *creds);
227 if (problem)
228 goto fail;
229 #endif
230
231 authctxt->krb5_fwd_ccache = ccache;
232 ccache = NULL;
233
234 authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
235
236 problem = krb5_unparse_name(authctxt->krb5_ctx, authctxt->krb5_user,
237 &pname);
238 if (problem)
239 goto fail;
240
241 debug("Kerberos v5 TGT accepted (%s)", pname);
242
243 restore_uid();
244
245 return (1);
246
247 fail:
248 if (problem)
249 debug("Kerberos v5 TGT passing failed: %s",
250 krb5_get_err_text(authctxt->krb5_ctx, problem));
251 if (ccache)
252 krb5_cc_destroy(authctxt->krb5_ctx, ccache);
253
254 restore_uid();
255
256 return (0);
257 }
258
259 int
260 auth_krb5_password(Authctxt *authctxt, const char *password)
261 {
262 #ifndef HEIMDAL
263 krb5_creds creds;
264 krb5_principal server;
265 char ccname[40];
266 int tmpfd;
267 #endif
268 krb5_error_code problem;
269
270 if (authctxt->pw == NULL)
271 return (0);
272
273 temporarily_use_uid(authctxt->pw);
274
275 problem = krb5_init(authctxt);
276 if (problem)
277 goto out;
278
279 problem = krb5_parse_name(authctxt->krb5_ctx, authctxt->pw->pw_name,
280 &authctxt->krb5_user);
281 if (problem)
282 goto out;
283
284 #ifdef HEIMDAL
285 problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops,
286 &authctxt->krb5_fwd_ccache);
287 if (problem)
288 goto out;
289
290 problem = krb5_cc_initialize(authctxt->krb5_ctx,
291 authctxt->krb5_fwd_ccache, authctxt->krb5_user);
292 if (problem)
293 goto out;
294
295 restore_uid();
296 problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
297 authctxt->krb5_fwd_ccache, password, 1, NULL);
298 temporarily_use_uid(authctxt->pw);
299
300 if (problem)
301 goto out;
302
303 #else
304 problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
305 authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
306 if (problem)
307 goto out;
308
309 problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
310 KRB5_NT_SRV_HST, &server);
311 if (problem)
312 goto out;
313
314 restore_uid();
315 problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
316 NULL, NULL, NULL);
317 krb5_free_principal(authctxt->krb5_ctx, server);
318 temporarily_use_uid(authctxt->pw);
319 if (problem)
320 goto out;
321
322 if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
323 authctxt->pw->pw_name)) {
324 problem = -1;
325 goto out;
326 }
327
328 snprintf(ccname,sizeof(ccname),"FILE:/tmp/krb5cc_%d_XXXXXX",geteuid());
329
330 if ((tmpfd = mkstemp(ccname+strlen("FILE:")))==-1) {
331 log("mkstemp(): %.100s", strerror(errno));
332 problem = errno;
333 goto out;
334 }
335
336 if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
337 log("fchmod(): %.100s", strerror(errno));
338 close(tmpfd);
339 problem = errno;
340 goto out;
341 }
342 close(tmpfd);
343
344 problem = krb5_cc_resolve(authctxt->krb5_ctx, ccname, &authctxt->krb5_fwd_ccache);
345 if (problem)
346 goto out;
347
348 problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
349 authctxt->krb5_user);
350 if (problem)
351 goto out;
352
353 problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
354 &creds);
355 if (problem)
356 goto out;
357 #endif
358
359 authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
360
361 out:
362 restore_uid();
363
364 if (problem) {
365 if (authctxt->krb5_ctx != NULL && problem!=-1)
366 debug("Kerberos password authentication failed: %s",
367 krb5_get_err_text(authctxt->krb5_ctx, problem));
368 else
369 debug("Kerberos password authentication failed: %d",
370 problem);
371
372 krb5_cleanup_proc(authctxt);
373
374 if (options.kerberos_or_local_passwd)
375 return (-1);
376 else
377 return (0);
378 }
379 return (1);
380 }
381
382 void
383 krb5_cleanup_proc(void *context)
384 {
385 Authctxt *authctxt = (Authctxt *)context;
386
387 debug("krb5_cleanup_proc called");
388 if (authctxt->krb5_fwd_ccache) {
389 krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
390 authctxt->krb5_fwd_ccache = NULL;
391 }
392 if (authctxt->krb5_user) {
393 krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
394 authctxt->krb5_user = NULL;
395 }
396 if (authctxt->krb5_auth_ctx) {
397 krb5_auth_con_free(authctxt->krb5_ctx,
398 authctxt->krb5_auth_ctx);
399 authctxt->krb5_auth_ctx = NULL;
400 }
401 if (authctxt->krb5_ctx) {
402 krb5_free_context(authctxt->krb5_ctx);
403 authctxt->krb5_ctx = NULL;
404 }
405 }
406
407 #endif /* KRB5 */