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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 1.24 2001/06/26 16:15:22 dugsong Exp $"); | |
27 | ||
28 | #include "ssh.h" | |
29 | #include "ssh1.h" | |
30 | #include "packet.h" | |
31 | #include "xmalloc.h" | |
32 | #include "log.h" | |
33 | #include "servconf.h" | |
34 | #include "uidswap.h" | |
35 | #include "auth.h" | |
36 | ||
37 | #ifdef AFS | |
38 | #include "radix.h" | |
39 | #endif | |
40 | ||
41 | #ifdef KRB4 | |
42 | extern ServerOptions options; | |
43 | ||
44 | static int | |
45 | krb4_init(void *context) | |
46 | { | |
47 | static int cleanup_registered = 0; | |
48 | Authctxt *authctxt = (Authctxt *)context; | |
49 | const char *tkt_root = TKT_ROOT; | |
50 | struct stat st; | |
51 | int fd; | |
52 | ||
53 | if (!authctxt->krb4_ticket_file) { | |
54 | /* Set unique ticket string manually since we're still root. */ | |
55 | authctxt->krb4_ticket_file = xmalloc(MAXPATHLEN); | |
56 | #ifdef AFS | |
57 | if (lstat("/ticket", &st) != -1) | |
58 | tkt_root = "/ticket/"; | |
59 | #endif /* AFS */ | |
60 | snprintf(authctxt->krb4_ticket_file, MAXPATHLEN, "%s%u_%d", | |
61 | tkt_root, authctxt->pw->pw_uid, getpid()); | |
62 | krb_set_tkt_string(authctxt->krb4_ticket_file); | |
63 | } | |
64 | /* Register ticket cleanup in case of fatal error. */ | |
65 | if (!cleanup_registered) { | |
66 | fatal_add_cleanup(krb4_cleanup_proc, authctxt); | |
67 | cleanup_registered = 1; | |
68 | } | |
69 | /* Try to create our ticket file. */ | |
70 | if ((fd = mkstemp(authctxt->krb4_ticket_file)) != -1) { | |
71 | close(fd); | |
72 | return (1); | |
73 | } | |
74 | /* Ticket file exists - make sure user owns it (just passed ticket). */ | |
75 | if (lstat(authctxt->krb4_ticket_file, &st) != -1) { | |
76 | if (st.st_mode == (S_IFREG | S_IRUSR | S_IWUSR) && | |
77 | st.st_uid == authctxt->pw->pw_uid) | |
78 | return (1); | |
79 | } | |
80 | /* Failure - cancel cleanup function, leaving ticket for inspection. */ | |
81 | log("WARNING: bad ticket file %s", authctxt->krb4_ticket_file); | |
82 | ||
83 | fatal_remove_cleanup(krb4_cleanup_proc, authctxt); | |
84 | cleanup_registered = 0; | |
85 | ||
86 | xfree(authctxt->krb4_ticket_file); | |
87 | authctxt->krb4_ticket_file = NULL; | |
88 | ||
89 | return (0); | |
90 | } | |
91 | ||
92 | /* | |
93 | * try krb4 authentication, | |
94 | * return 1 on success, 0 on failure, -1 if krb4 is not available | |
95 | */ | |
96 | int | |
97 | auth_krb4_password(Authctxt *authctxt, const char *password) | |
98 | { | |
99 | AUTH_DAT adata; | |
100 | KTEXT_ST tkt; | |
101 | struct hostent *hp; | |
102 | struct passwd *pw; | |
103 | char localhost[MAXHOSTNAMELEN], phost[INST_SZ], realm[REALM_SZ]; | |
104 | u_int32_t faddr; | |
105 | int r; | |
106 | ||
107 | if ((pw = authctxt->pw) == NULL) | |
108 | return (0); | |
109 | ||
110 | /* | |
111 | * Try Kerberos password authentication only for non-root | |
112 | * users and only if Kerberos is installed. | |
113 | */ | |
114 | if (pw->pw_uid != 0 && krb_get_lrealm(realm, 1) == KSUCCESS) { | |
115 | /* Set up our ticket file. */ | |
116 | if (!krb4_init(authctxt)) { | |
117 | log("Couldn't initialize Kerberos ticket file for %s!", | |
118 | pw->pw_name); | |
119 | goto failure; | |
120 | } | |
121 | /* Try to get TGT using our password. */ | |
122 | r = krb_get_pw_in_tkt((char *) pw->pw_name, "", realm, | |
123 | "krbtgt", realm, DEFAULT_TKT_LIFE, (char *)password); | |
124 | if (r != INTK_OK) { | |
125 | debug("Kerberos v4 password authentication for %s " | |
126 | "failed: %s", pw->pw_name, krb_err_txt[r]); | |
127 | goto failure; | |
128 | } | |
129 | /* Successful authentication. */ | |
130 | chown(tkt_string(), pw->pw_uid, pw->pw_gid); | |
131 | ||
132 | /* | |
133 | * Now that we have a TGT, try to get a local | |
134 | * "rcmd" ticket to ensure that we are not talking | |
135 | * to a bogus Kerberos server. | |
136 | */ | |
137 | gethostname(localhost, sizeof(localhost)); | |
138 | strlcpy(phost, (char *)krb_get_phost(localhost), | |
139 | sizeof(phost)); | |
140 | r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33); | |
141 | ||
142 | if (r == KSUCCESS) { | |
143 | if ((hp = gethostbyname(localhost)) == NULL) { | |
144 | log("Couldn't get local host address!"); | |
145 | goto failure; | |
146 | } | |
147 | memmove((void *)&faddr, (void *)hp->h_addr, | |
148 | sizeof(faddr)); | |
149 | ||
150 | /* Verify our "rcmd" ticket. */ | |
151 | r = krb_rd_req(&tkt, KRB4_SERVICE_NAME, phost, | |
152 | faddr, &adata, ""); | |
153 | if (r == RD_AP_UNDEC) { | |
154 | /* | |
155 | * Probably didn't have a srvtab on | |
156 | * localhost. Disallow login. | |
157 | */ | |
158 | log("Kerberos v4 TGT for %s unverifiable, " | |
159 | "no srvtab installed? krb_rd_req: %s", | |
160 | pw->pw_name, krb_err_txt[r]); | |
161 | goto failure; | |
162 | } else if (r != KSUCCESS) { | |
163 | log("Kerberos v4 %s ticket unverifiable: %s", | |
164 | KRB4_SERVICE_NAME, krb_err_txt[r]); | |
165 | goto failure; | |
166 | } | |
167 | } else if (r == KDC_PR_UNKNOWN) { | |
168 | /* | |
169 | * Disallow login if no rcmd service exists, and | |
170 | * log the error. | |
171 | */ | |
172 | log("Kerberos v4 TGT for %s unverifiable: %s; %s.%s " | |
173 | "not registered, or srvtab is wrong?", pw->pw_name, | |
174 | krb_err_txt[r], KRB4_SERVICE_NAME, phost); | |
175 | goto failure; | |
176 | } else { | |
177 | /* | |
178 | * TGT is bad, forget it. Possibly spoofed! | |
179 | */ | |
180 | debug("WARNING: Kerberos v4 TGT possibly spoofed " | |
181 | "for %s: %s", pw->pw_name, krb_err_txt[r]); | |
182 | goto failure; | |
183 | } | |
184 | /* Authentication succeeded. */ | |
185 | return (1); | |
186 | } else | |
187 | /* Logging in as root or no local Kerberos realm. */ | |
188 | debug("Unable to authenticate to Kerberos."); | |
189 | ||
190 | failure: | |
191 | krb4_cleanup_proc(authctxt); | |
192 | ||
193 | if (!options.kerberos_or_local_passwd) | |
194 | return (0); | |
195 | ||
196 | /* Fall back to ordinary passwd authentication. */ | |
197 | return (-1); | |
198 | } | |
199 | ||
200 | void | |
201 | krb4_cleanup_proc(void *context) | |
202 | { | |
203 | Authctxt *authctxt = (Authctxt *)context; | |
204 | debug("krb4_cleanup_proc called"); | |
205 | if (authctxt->krb4_ticket_file) { | |
206 | (void) dest_tkt(); | |
207 | xfree(authctxt->krb4_ticket_file); | |
208 | authctxt->krb4_ticket_file = NULL; | |
209 | } | |
210 | } | |
211 | ||
212 | int | |
213 | auth_krb4(Authctxt *authctxt, KTEXT auth, char **client) | |
214 | { | |
215 | AUTH_DAT adat = {0}; | |
216 | KTEXT_ST reply; | |
217 | Key_schedule schedule; | |
218 | struct sockaddr_in local, foreign; | |
219 | char instance[INST_SZ]; | |
220 | socklen_t slen; | |
221 | u_int cksum; | |
222 | int r, s; | |
223 | ||
224 | s = packet_get_connection_in(); | |
225 | ||
226 | slen = sizeof(local); | |
227 | memset(&local, 0, sizeof(local)); | |
228 | if (getsockname(s, (struct sockaddr *) & local, &slen) < 0) | |
229 | debug("getsockname failed: %.100s", strerror(errno)); | |
230 | slen = sizeof(foreign); | |
231 | memset(&foreign, 0, sizeof(foreign)); | |
232 | if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) { | |
233 | debug("getpeername failed: %.100s", strerror(errno)); | |
234 | fatal_cleanup(); | |
235 | } | |
236 | instance[0] = '*'; | |
237 | instance[1] = 0; | |
238 | ||
239 | /* Get the encrypted request, challenge, and session key. */ | |
240 | if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, | |
241 | 0, &adat, ""))) { | |
242 | debug("Kerberos v4 krb_rd_req: %.100s", krb_err_txt[r]); | |
243 | return (0); | |
244 | } | |
245 | des_key_sched((des_cblock *) adat.session, schedule); | |
246 | ||
247 | *client = xmalloc(MAX_K_NAME_SZ); | |
248 | (void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname, | |
249 | *adat.pinst ? "." : "", adat.pinst, adat.prealm); | |
250 | ||
251 | /* Check ~/.klogin authorization now. */ | |
252 | if (kuserok(&adat, authctxt->user) != KSUCCESS) { | |
253 | log("Kerberos v4 .klogin authorization failed for %s to " | |
254 | "account %s", *client, authctxt->user); | |
255 | xfree(*client); | |
256 | return (0); | |
257 | } | |
258 | /* Increment the checksum, and return it encrypted with the | |
259 | session key. */ | |
260 | cksum = adat.checksum + 1; | |
261 | cksum = htonl(cksum); | |
262 | ||
263 | /* If we can't successfully encrypt the checksum, we send back an | |
264 | empty message, admitting our failure. */ | |
265 | if ((r = krb_mk_priv((u_char *) & cksum, reply.dat, sizeof(cksum) + 1, | |
266 | schedule, &adat.session, &local, &foreign)) < 0) { | |
267 | debug("Kerberos v4 mk_priv: (%d) %s", r, krb_err_txt[r]); | |
268 | reply.dat[0] = 0; | |
269 | reply.length = 0; | |
270 | } else | |
271 | reply.length = r; | |
272 | ||
273 | /* Clear session key. */ | |
274 | memset(&adat.session, 0, sizeof(&adat.session)); | |
275 | ||
276 | packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE); | |
277 | packet_put_string((char *) reply.dat, reply.length); | |
278 | packet_send(); | |
279 | packet_write_wait(); | |
280 | return (1); | |
281 | } | |
282 | #endif /* KRB4 */ | |
283 | ||
284 | #ifdef AFS | |
285 | int | |
286 | auth_krb4_tgt(Authctxt *authctxt, const char *string) | |
287 | { | |
288 | CREDENTIALS creds; | |
289 | struct passwd *pw; | |
290 | ||
291 | if ((pw = authctxt->pw) == NULL) | |
292 | goto failure; | |
293 | ||
294 | temporarily_use_uid(pw); | |
295 | ||
296 | if (!radix_to_creds(string, &creds)) { | |
297 | log("Protocol error decoding Kerberos v4 TGT"); | |
298 | goto failure; | |
299 | } | |
300 | if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */ | |
301 | strlcpy(creds.service, "krbtgt", sizeof creds.service); | |
302 | ||
303 | if (strcmp(creds.service, "krbtgt")) { | |
304 | log("Kerberos v4 TGT (%s%s%s@%s) rejected for %s", | |
305 | creds.pname, creds.pinst[0] ? "." : "", creds.pinst, | |
306 | creds.realm, pw->pw_name); | |
307 | goto failure; | |
308 | } | |
309 | if (!krb4_init(authctxt)) | |
310 | goto failure; | |
311 | ||
312 | if (in_tkt(creds.pname, creds.pinst) != KSUCCESS) | |
313 | goto failure; | |
314 | ||
315 | if (save_credentials(creds.service, creds.instance, creds.realm, | |
316 | creds.session, creds.lifetime, creds.kvno, &creds.ticket_st, | |
317 | creds.issue_date) != KSUCCESS) { | |
318 | debug("Kerberos v4 TGT refused: couldn't save credentials"); | |
319 | goto failure; | |
320 | } | |
321 | /* Successful authentication, passed all checks. */ | |
322 | chown(tkt_string(), pw->pw_uid, pw->pw_gid); | |
323 | ||
324 | debug("Kerberos v4 TGT accepted (%s%s%s@%s)", | |
325 | creds.pname, creds.pinst[0] ? "." : "", creds.pinst, creds.realm); | |
326 | memset(&creds, 0, sizeof(creds)); | |
327 | ||
328 | restore_uid(); | |
329 | ||
330 | return (1); | |
331 | ||
332 | failure: | |
333 | krb4_cleanup_proc(authctxt); | |
334 | memset(&creds, 0, sizeof(creds)); | |
335 | restore_uid(); | |
336 | ||
337 | return (0); | |
338 | } | |
339 | ||
340 | int | |
341 | auth_afs_token(Authctxt *authctxt, const char *token_string) | |
342 | { | |
343 | CREDENTIALS creds; | |
344 | struct passwd *pw; | |
345 | uid_t uid; | |
346 | ||
347 | if ((pw = authctxt->pw) == NULL) | |
348 | return (0); | |
349 | ||
350 | if (!radix_to_creds(token_string, &creds)) { | |
351 | log("Protocol error decoding AFS token"); | |
352 | return (0); | |
353 | } | |
354 | if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */ | |
355 | strlcpy(creds.service, "afs", sizeof creds.service); | |
356 | ||
357 | if (strncmp(creds.pname, "AFS ID ", 7) == 0) | |
358 | uid = atoi(creds.pname + 7); | |
359 | else | |
360 | uid = pw->pw_uid; | |
361 | ||
362 | if (kafs_settoken(creds.realm, uid, &creds)) { | |
363 | log("AFS token (%s@%s) rejected for %s", | |
364 | creds.pname, creds.realm, pw->pw_name); | |
365 | memset(&creds, 0, sizeof(creds)); | |
366 | return (0); | |
367 | } | |
368 | debug("AFS token accepted (%s@%s)", creds.pname, creds.realm); | |
369 | memset(&creds, 0, sizeof(creds)); | |
370 | ||
371 | return (1); | |
372 | } | |
373 | #endif /* AFS */ |