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1 | /* | |
2 | * Copyright (c) 1999 Dug Song. All rights reserved. | |
3 | * | |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
7 | * 1. Redistributions of source code must retain the above copyright | |
8 | * notice, this list of conditions and the following disclaimer. | |
9 | * 2. Redistributions in binary form must reproduce the above copyright | |
10 | * notice, this list of conditions and the following disclaimer in the | |
11 | * documentation and/or other materials provided with the distribution. | |
12 | * | |
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
23 | */ | |
24 | ||
25 | #include "includes.h" | |
26 | RCSID("$OpenBSD: auth-krb4.c,v 1.22 2001/01/21 19:05:41 markus Exp $"); | |
27 | ||
28 | #ifdef KRB4 | |
29 | #include "ssh.h" | |
30 | #include "ssh1.h" | |
31 | #include "packet.h" | |
32 | #include "xmalloc.h" | |
33 | #include "log.h" | |
34 | #include "servconf.h" | |
35 | #include "auth.h" | |
36 | #include "radix.h" | |
37 | ||
38 | char *ticket = NULL; | |
39 | ||
40 | extern ServerOptions options; | |
41 | ||
42 | /* | |
43 | * try krb4 authentication, | |
44 | * return 1 on success, 0 on failure, -1 if krb4 is not available | |
45 | */ | |
46 | ||
47 | int | |
48 | auth_krb4_password(struct passwd * pw, const char *password) | |
49 | { | |
50 | AUTH_DAT adata; | |
51 | KTEXT_ST tkt; | |
52 | struct hostent *hp; | |
53 | u_long faddr; | |
54 | char localhost[MAXHOSTNAMELEN]; | |
55 | char phost[INST_SZ]; | |
56 | char realm[REALM_SZ]; | |
57 | int r; | |
58 | ||
59 | /* | |
60 | * Try Kerberos password authentication only for non-root | |
61 | * users and only if Kerberos is installed. | |
62 | */ | |
63 | if (pw->pw_uid != 0 && krb_get_lrealm(realm, 1) == KSUCCESS) { | |
64 | ||
65 | /* Set up our ticket file. */ | |
66 | if (!krb4_init(pw->pw_uid)) { | |
67 | log("Couldn't initialize Kerberos ticket file for %s!", | |
68 | pw->pw_name); | |
69 | goto kerberos_auth_failure; | |
70 | } | |
71 | /* Try to get TGT using our password. */ | |
72 | r = krb_get_pw_in_tkt((char *) pw->pw_name, "", | |
73 | realm, "krbtgt", realm, | |
74 | DEFAULT_TKT_LIFE, (char *) password); | |
75 | if (r != INTK_OK) { | |
76 | packet_send_debug("Kerberos V4 password " | |
77 | "authentication for %s failed: %s", | |
78 | pw->pw_name, krb_err_txt[r]); | |
79 | goto kerberos_auth_failure; | |
80 | } | |
81 | /* Successful authentication. */ | |
82 | chown(tkt_string(), pw->pw_uid, pw->pw_gid); | |
83 | ||
84 | /* | |
85 | * Now that we have a TGT, try to get a local | |
86 | * "rcmd" ticket to ensure that we are not talking | |
87 | * to a bogus Kerberos server. | |
88 | */ | |
89 | (void) gethostname(localhost, sizeof(localhost)); | |
90 | (void) strlcpy(phost, (char *) krb_get_phost(localhost), | |
91 | INST_SZ); | |
92 | r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33); | |
93 | ||
94 | if (r == KSUCCESS) { | |
95 | if (!(hp = gethostbyname(localhost))) { | |
96 | log("Couldn't get local host address!"); | |
97 | goto kerberos_auth_failure; | |
98 | } | |
99 | memmove((void *) &faddr, (void *) hp->h_addr, | |
100 | sizeof(faddr)); | |
101 | ||
102 | /* Verify our "rcmd" ticket. */ | |
103 | r = krb_rd_req(&tkt, KRB4_SERVICE_NAME, phost, | |
104 | faddr, &adata, ""); | |
105 | if (r == RD_AP_UNDEC) { | |
106 | /* | |
107 | * Probably didn't have a srvtab on | |
108 | * localhost. Disallow login. | |
109 | */ | |
110 | log("Kerberos V4 TGT for %s unverifiable, " | |
111 | "no srvtab installed? krb_rd_req: %s", | |
112 | pw->pw_name, krb_err_txt[r]); | |
113 | goto kerberos_auth_failure; | |
114 | } else if (r != KSUCCESS) { | |
115 | log("Kerberos V4 %s ticket unverifiable: %s", | |
116 | KRB4_SERVICE_NAME, krb_err_txt[r]); | |
117 | goto kerberos_auth_failure; | |
118 | } | |
119 | } else if (r == KDC_PR_UNKNOWN) { | |
120 | /* | |
121 | * Disallow login if no rcmd service exists, and | |
122 | * log the error. | |
123 | */ | |
124 | log("Kerberos V4 TGT for %s unverifiable: %s; %s.%s " | |
125 | "not registered, or srvtab is wrong?", pw->pw_name, | |
126 | krb_err_txt[r], KRB4_SERVICE_NAME, phost); | |
127 | goto kerberos_auth_failure; | |
128 | } else { | |
129 | /* | |
130 | * TGT is bad, forget it. Possibly spoofed! | |
131 | */ | |
132 | packet_send_debug("WARNING: Kerberos V4 TGT " | |
133 | "possibly spoofed for %s: %s", | |
134 | pw->pw_name, krb_err_txt[r]); | |
135 | goto kerberos_auth_failure; | |
136 | } | |
137 | ||
138 | /* Authentication succeeded. */ | |
139 | return 1; | |
140 | ||
141 | kerberos_auth_failure: | |
142 | krb4_cleanup_proc(NULL); | |
143 | ||
144 | if (!options.kerberos_or_local_passwd) | |
145 | return 0; | |
146 | } else { | |
147 | /* Logging in as root or no local Kerberos realm. */ | |
148 | packet_send_debug("Unable to authenticate to Kerberos."); | |
149 | } | |
150 | /* Fall back to ordinary passwd authentication. */ | |
151 | return -1; | |
152 | } | |
153 | ||
154 | void | |
155 | krb4_cleanup_proc(void *ignore) | |
156 | { | |
157 | debug("krb4_cleanup_proc called"); | |
158 | if (ticket) { | |
159 | (void) dest_tkt(); | |
160 | xfree(ticket); | |
161 | ticket = NULL; | |
162 | } | |
163 | } | |
164 | ||
165 | int | |
166 | krb4_init(uid_t uid) | |
167 | { | |
168 | static int cleanup_registered = 0; | |
169 | const char *tkt_root = TKT_ROOT; | |
170 | struct stat st; | |
171 | int fd; | |
172 | ||
173 | if (!ticket) { | |
174 | /* Set unique ticket string manually since we're still root. */ | |
175 | ticket = xmalloc(MAXPATHLEN); | |
176 | #ifdef AFS | |
177 | if (lstat("/ticket", &st) != -1) | |
178 | tkt_root = "/ticket/"; | |
179 | #endif /* AFS */ | |
180 | snprintf(ticket, MAXPATHLEN, "%s%u_%d", tkt_root, uid, getpid()); | |
181 | (void) krb_set_tkt_string(ticket); | |
182 | } | |
183 | /* Register ticket cleanup in case of fatal error. */ | |
184 | if (!cleanup_registered) { | |
185 | fatal_add_cleanup(krb4_cleanup_proc, NULL); | |
186 | cleanup_registered = 1; | |
187 | } | |
188 | /* Try to create our ticket file. */ | |
189 | if ((fd = mkstemp(ticket)) != -1) { | |
190 | close(fd); | |
191 | return 1; | |
192 | } | |
193 | /* Ticket file exists - make sure user owns it (just passed ticket). */ | |
194 | if (lstat(ticket, &st) != -1) { | |
195 | if (st.st_mode == (S_IFREG | S_IRUSR | S_IWUSR) && | |
196 | st.st_uid == uid) | |
197 | return 1; | |
198 | } | |
199 | /* Failure - cancel cleanup function, leaving bad ticket for inspection. */ | |
200 | log("WARNING: bad ticket file %s", ticket); | |
201 | fatal_remove_cleanup(krb4_cleanup_proc, NULL); | |
202 | cleanup_registered = 0; | |
203 | xfree(ticket); | |
204 | ticket = NULL; | |
205 | ||
206 | return 0; | |
207 | } | |
208 | ||
209 | int | |
210 | auth_krb4(const char *server_user, KTEXT auth, char **client) | |
211 | { | |
212 | AUTH_DAT adat = {0}; | |
213 | KTEXT_ST reply; | |
214 | char instance[INST_SZ]; | |
215 | int r, s; | |
216 | socklen_t slen; | |
217 | u_int cksum; | |
218 | Key_schedule schedule; | |
219 | struct sockaddr_in local, foreign; | |
220 | ||
221 | s = packet_get_connection_in(); | |
222 | ||
223 | slen = sizeof(local); | |
224 | memset(&local, 0, sizeof(local)); | |
225 | if (getsockname(s, (struct sockaddr *) & local, &slen) < 0) | |
226 | debug("getsockname failed: %.100s", strerror(errno)); | |
227 | slen = sizeof(foreign); | |
228 | memset(&foreign, 0, sizeof(foreign)); | |
229 | if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) { | |
230 | debug("getpeername failed: %.100s", strerror(errno)); | |
231 | fatal_cleanup(); | |
232 | } | |
233 | instance[0] = '*'; | |
234 | instance[1] = 0; | |
235 | ||
236 | /* Get the encrypted request, challenge, and session key. */ | |
237 | if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, 0, &adat, ""))) { | |
238 | packet_send_debug("Kerberos V4 krb_rd_req: %.100s", krb_err_txt[r]); | |
239 | return 0; | |
240 | } | |
241 | des_key_sched((des_cblock *) adat.session, schedule); | |
242 | ||
243 | *client = xmalloc(MAX_K_NAME_SZ); | |
244 | (void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname, | |
245 | *adat.pinst ? "." : "", adat.pinst, adat.prealm); | |
246 | ||
247 | /* Check ~/.klogin authorization now. */ | |
248 | if (kuserok(&adat, (char *) server_user) != KSUCCESS) { | |
249 | packet_send_debug("Kerberos V4 .klogin authorization failed!"); | |
250 | log("Kerberos V4 .klogin authorization failed for %s to account %s", | |
251 | *client, server_user); | |
252 | xfree(*client); | |
253 | return 0; | |
254 | } | |
255 | /* Increment the checksum, and return it encrypted with the | |
256 | session key. */ | |
257 | cksum = adat.checksum + 1; | |
258 | cksum = htonl(cksum); | |
259 | ||
260 | /* If we can't successfully encrypt the checksum, we send back an | |
261 | empty message, admitting our failure. */ | |
262 | if ((r = krb_mk_priv((u_char *) & cksum, reply.dat, sizeof(cksum) + 1, | |
263 | schedule, &adat.session, &local, &foreign)) < 0) { | |
264 | packet_send_debug("Kerberos V4 mk_priv: (%d) %s", r, krb_err_txt[r]); | |
265 | reply.dat[0] = 0; | |
266 | reply.length = 0; | |
267 | } else | |
268 | reply.length = r; | |
269 | ||
270 | /* Clear session key. */ | |
271 | memset(&adat.session, 0, sizeof(&adat.session)); | |
272 | ||
273 | packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE); | |
274 | packet_put_string((char *) reply.dat, reply.length); | |
275 | packet_send(); | |
276 | packet_write_wait(); | |
277 | return 1; | |
278 | } | |
279 | #endif /* KRB4 */ | |
280 | ||
281 | #ifdef AFS | |
282 | int | |
283 | auth_kerberos_tgt(struct passwd *pw, const char *string) | |
284 | { | |
285 | CREDENTIALS creds; | |
286 | ||
287 | if (pw == NULL) | |
288 | goto auth_kerberos_tgt_failure; | |
289 | if (!radix_to_creds(string, &creds)) { | |
290 | log("Protocol error decoding Kerberos V4 tgt"); | |
291 | packet_send_debug("Protocol error decoding Kerberos V4 tgt"); | |
292 | goto auth_kerberos_tgt_failure; | |
293 | } | |
294 | if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */ | |
295 | strlcpy(creds.service, "krbtgt", sizeof creds.service); | |
296 | ||
297 | if (strcmp(creds.service, "krbtgt")) { | |
298 | log("Kerberos V4 tgt (%s%s%s@%s) rejected for %s", creds.pname, | |
299 | creds.pinst[0] ? "." : "", creds.pinst, creds.realm, | |
300 | pw->pw_name); | |
301 | packet_send_debug("Kerberos V4 tgt (%s%s%s@%s) rejected for %s", | |
302 | creds.pname, creds.pinst[0] ? "." : "", creds.pinst, | |
303 | creds.realm, pw->pw_name); | |
304 | goto auth_kerberos_tgt_failure; | |
305 | } | |
306 | if (!krb4_init(pw->pw_uid)) | |
307 | goto auth_kerberos_tgt_failure; | |
308 | ||
309 | if (in_tkt(creds.pname, creds.pinst) != KSUCCESS) | |
310 | goto auth_kerberos_tgt_failure; | |
311 | ||
312 | if (save_credentials(creds.service, creds.instance, creds.realm, | |
313 | creds.session, creds.lifetime, creds.kvno, | |
314 | &creds.ticket_st, creds.issue_date) != KSUCCESS) { | |
315 | packet_send_debug("Kerberos V4 tgt refused: couldn't save credentials"); | |
316 | goto auth_kerberos_tgt_failure; | |
317 | } | |
318 | /* Successful authentication, passed all checks. */ | |
319 | chown(tkt_string(), pw->pw_uid, pw->pw_gid); | |
320 | ||
321 | packet_send_debug("Kerberos V4 tgt accepted (%s.%s@%s, %s%s%s@%s)", | |
322 | creds.service, creds.instance, creds.realm, creds.pname, | |
323 | creds.pinst[0] ? "." : "", creds.pinst, creds.realm); | |
324 | memset(&creds, 0, sizeof(creds)); | |
325 | packet_start(SSH_SMSG_SUCCESS); | |
326 | packet_send(); | |
327 | packet_write_wait(); | |
328 | return 1; | |
329 | ||
330 | auth_kerberos_tgt_failure: | |
331 | krb4_cleanup_proc(NULL); | |
332 | memset(&creds, 0, sizeof(creds)); | |
333 | packet_start(SSH_SMSG_FAILURE); | |
334 | packet_send(); | |
335 | packet_write_wait(); | |
336 | return 0; | |
337 | } | |
338 | ||
339 | int | |
340 | auth_afs_token(struct passwd *pw, const char *token_string) | |
341 | { | |
342 | CREDENTIALS creds; | |
343 | uid_t uid; | |
344 | ||
345 | if (pw == NULL) { | |
346 | /* XXX fake protocol error */ | |
347 | packet_send_debug("Protocol error decoding AFS token"); | |
348 | packet_start(SSH_SMSG_FAILURE); | |
349 | packet_send(); | |
350 | packet_write_wait(); | |
351 | return 0; | |
352 | } | |
353 | if (!radix_to_creds(token_string, &creds)) { | |
354 | log("Protocol error decoding AFS token"); | |
355 | packet_send_debug("Protocol error decoding AFS token"); | |
356 | packet_start(SSH_SMSG_FAILURE); | |
357 | packet_send(); | |
358 | packet_write_wait(); | |
359 | return 0; | |
360 | } | |
361 | if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */ | |
362 | strlcpy(creds.service, "afs", sizeof creds.service); | |
363 | ||
364 | if (strncmp(creds.pname, "AFS ID ", 7) == 0) | |
365 | uid = atoi(creds.pname + 7); | |
366 | else | |
367 | uid = pw->pw_uid; | |
368 | ||
369 | if (kafs_settoken(creds.realm, uid, &creds)) { | |
370 | log("AFS token (%s@%s) rejected for %s", creds.pname, creds.realm, | |
371 | pw->pw_name); | |
372 | packet_send_debug("AFS token (%s@%s) rejected for %s", creds.pname, | |
373 | creds.realm, pw->pw_name); | |
374 | memset(&creds, 0, sizeof(creds)); | |
375 | packet_start(SSH_SMSG_FAILURE); | |
376 | packet_send(); | |
377 | packet_write_wait(); | |
378 | return 0; | |
379 | } | |
380 | packet_send_debug("AFS token accepted (%s@%s, %s@%s)", creds.service, | |
381 | creds.realm, creds.pname, creds.realm); | |
382 | memset(&creds, 0, sizeof(creds)); | |
383 | packet_start(SSH_SMSG_SUCCESS); | |
384 | packet_send(); | |
385 | packet_write_wait(); | |
386 | return 1; | |
387 | } | |
388 | #endif /* AFS */ |