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3c0ef626 | 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" | |
41b2f314 | 26 | RCSID("$OpenBSD: auth-krb4.c,v 1.28 2002/09/26 11:38:43 markus Exp $"); |
3c0ef626 | 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; | |
e9a17296 | 52 | |
3c0ef626 | 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 */ | |
f5799ae1 | 60 | snprintf(authctxt->krb4_ticket_file, MAXPATHLEN, "%s%u_%ld", |
61 | tkt_root, authctxt->pw->pw_uid, (long)getpid()); | |
3c0ef626 | 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); | |
e9a17296 | 82 | |
3c0ef626 | 83 | fatal_remove_cleanup(krb4_cleanup_proc, authctxt); |
84 | cleanup_registered = 0; | |
e9a17296 | 85 | |
3c0ef626 | 86 | xfree(authctxt->krb4_ticket_file); |
87 | authctxt->krb4_ticket_file = NULL; | |
e9a17296 | 88 | |
3c0ef626 | 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; | |
e9a17296 | 106 | |
3c0ef626 | 107 | if ((pw = authctxt->pw) == NULL) |
108 | return (0); | |
e9a17296 | 109 | |
3c0ef626 | 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); | |
e9a17296 | 131 | |
3c0ef626 | 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); | |
e9a17296 | 141 | |
3c0ef626 | 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)); | |
e9a17296 | 149 | |
3c0ef626 | 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."); | |
e9a17296 | 189 | |
3c0ef626 | 190 | failure: |
191 | krb4_cleanup_proc(authctxt); | |
e9a17296 | 192 | |
3c0ef626 | 193 | if (!options.kerberos_or_local_passwd) |
194 | return (0); | |
e9a17296 | 195 | |
3c0ef626 | 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 | |
41b2f314 | 213 | auth_krb4(Authctxt *authctxt, KTEXT auth, char **client, KTEXT reply) |
3c0ef626 | 214 | { |
215 | AUTH_DAT adat = {0}; | |
3c0ef626 | 216 | Key_schedule schedule; |
217 | struct sockaddr_in local, foreign; | |
218 | char instance[INST_SZ]; | |
219 | socklen_t slen; | |
220 | u_int cksum; | |
221 | int r, s; | |
e9a17296 | 222 | |
3c0ef626 | 223 | s = packet_get_connection_in(); |
e9a17296 | 224 | |
3c0ef626 | 225 | slen = sizeof(local); |
226 | memset(&local, 0, sizeof(local)); | |
227 | if (getsockname(s, (struct sockaddr *) & local, &slen) < 0) | |
228 | debug("getsockname failed: %.100s", strerror(errno)); | |
229 | slen = sizeof(foreign); | |
230 | memset(&foreign, 0, sizeof(foreign)); | |
231 | if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) { | |
232 | debug("getpeername failed: %.100s", strerror(errno)); | |
233 | fatal_cleanup(); | |
234 | } | |
235 | instance[0] = '*'; | |
236 | instance[1] = 0; | |
e9a17296 | 237 | |
3c0ef626 | 238 | /* Get the encrypted request, challenge, and session key. */ |
239 | if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, | |
240 | 0, &adat, ""))) { | |
241 | debug("Kerberos v4 krb_rd_req: %.100s", krb_err_txt[r]); | |
242 | return (0); | |
243 | } | |
244 | des_key_sched((des_cblock *) adat.session, schedule); | |
e9a17296 | 245 | |
3c0ef626 | 246 | *client = xmalloc(MAX_K_NAME_SZ); |
247 | (void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname, | |
248 | *adat.pinst ? "." : "", adat.pinst, adat.prealm); | |
e9a17296 | 249 | |
3c0ef626 | 250 | /* Check ~/.klogin authorization now. */ |
251 | if (kuserok(&adat, authctxt->user) != KSUCCESS) { | |
252 | log("Kerberos v4 .klogin authorization failed for %s to " | |
253 | "account %s", *client, authctxt->user); | |
254 | xfree(*client); | |
700318f3 | 255 | *client = NULL; |
3c0ef626 | 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); | |
e9a17296 | 262 | |
3c0ef626 | 263 | /* If we can't successfully encrypt the checksum, we send back an |
264 | empty message, admitting our failure. */ | |
41b2f314 | 265 | if ((r = krb_mk_priv((u_char *) & cksum, reply->dat, sizeof(cksum) + 1, |
3c0ef626 | 266 | schedule, &adat.session, &local, &foreign)) < 0) { |
267 | debug("Kerberos v4 mk_priv: (%d) %s", r, krb_err_txt[r]); | |
41b2f314 | 268 | reply->dat[0] = 0; |
269 | reply->length = 0; | |
3c0ef626 | 270 | } else |
41b2f314 | 271 | reply->length = r; |
e9a17296 | 272 | |
3c0ef626 | 273 | /* Clear session key. */ |
274 | memset(&adat.session, 0, sizeof(&adat.session)); | |
3c0ef626 | 275 | return (1); |
276 | } | |
277 | #endif /* KRB4 */ | |
278 | ||
279 | #ifdef AFS | |
280 | int | |
281 | auth_krb4_tgt(Authctxt *authctxt, const char *string) | |
282 | { | |
283 | CREDENTIALS creds; | |
284 | struct passwd *pw; | |
e9a17296 | 285 | |
3c0ef626 | 286 | if ((pw = authctxt->pw) == NULL) |
287 | goto failure; | |
e9a17296 | 288 | |
3c0ef626 | 289 | temporarily_use_uid(pw); |
e9a17296 | 290 | |
3c0ef626 | 291 | if (!radix_to_creds(string, &creds)) { |
292 | log("Protocol error decoding Kerberos v4 TGT"); | |
293 | goto failure; | |
294 | } | |
295 | if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */ | |
296 | strlcpy(creds.service, "krbtgt", sizeof creds.service); | |
e9a17296 | 297 | |
3c0ef626 | 298 | if (strcmp(creds.service, "krbtgt")) { |
299 | log("Kerberos v4 TGT (%s%s%s@%s) rejected for %s", | |
300 | creds.pname, creds.pinst[0] ? "." : "", creds.pinst, | |
301 | creds.realm, pw->pw_name); | |
302 | goto failure; | |
303 | } | |
304 | if (!krb4_init(authctxt)) | |
305 | goto failure; | |
e9a17296 | 306 | |
3c0ef626 | 307 | if (in_tkt(creds.pname, creds.pinst) != KSUCCESS) |
308 | goto failure; | |
e9a17296 | 309 | |
3c0ef626 | 310 | if (save_credentials(creds.service, creds.instance, creds.realm, |
311 | creds.session, creds.lifetime, creds.kvno, &creds.ticket_st, | |
312 | creds.issue_date) != KSUCCESS) { | |
313 | debug("Kerberos v4 TGT refused: couldn't save credentials"); | |
314 | goto failure; | |
315 | } | |
316 | /* Successful authentication, passed all checks. */ | |
317 | chown(tkt_string(), pw->pw_uid, pw->pw_gid); | |
e9a17296 | 318 | |
3c0ef626 | 319 | debug("Kerberos v4 TGT accepted (%s%s%s@%s)", |
320 | creds.pname, creds.pinst[0] ? "." : "", creds.pinst, creds.realm); | |
321 | memset(&creds, 0, sizeof(creds)); | |
e9a17296 | 322 | |
3c0ef626 | 323 | restore_uid(); |
e9a17296 | 324 | |
3c0ef626 | 325 | return (1); |
e9a17296 | 326 | |
3c0ef626 | 327 | failure: |
328 | krb4_cleanup_proc(authctxt); | |
329 | memset(&creds, 0, sizeof(creds)); | |
330 | restore_uid(); | |
e9a17296 | 331 | |
3c0ef626 | 332 | return (0); |
333 | } | |
334 | ||
335 | int | |
336 | auth_afs_token(Authctxt *authctxt, const char *token_string) | |
337 | { | |
338 | CREDENTIALS creds; | |
339 | struct passwd *pw; | |
340 | uid_t uid; | |
e9a17296 | 341 | |
3c0ef626 | 342 | if ((pw = authctxt->pw) == NULL) |
343 | return (0); | |
e9a17296 | 344 | |
3c0ef626 | 345 | if (!radix_to_creds(token_string, &creds)) { |
346 | log("Protocol error decoding AFS token"); | |
347 | return (0); | |
348 | } | |
349 | if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */ | |
350 | strlcpy(creds.service, "afs", sizeof creds.service); | |
e9a17296 | 351 | |
3c0ef626 | 352 | if (strncmp(creds.pname, "AFS ID ", 7) == 0) |
353 | uid = atoi(creds.pname + 7); | |
354 | else | |
355 | uid = pw->pw_uid; | |
e9a17296 | 356 | |
3c0ef626 | 357 | if (kafs_settoken(creds.realm, uid, &creds)) { |
358 | log("AFS token (%s@%s) rejected for %s", | |
359 | creds.pname, creds.realm, pw->pw_name); | |
360 | memset(&creds, 0, sizeof(creds)); | |
361 | return (0); | |
362 | } | |
363 | debug("AFS token accepted (%s@%s)", creds.pname, creds.realm); | |
364 | memset(&creds, 0, sizeof(creds)); | |
e9a17296 | 365 | |
3c0ef626 | 366 | return (1); |
367 | } | |
368 | #endif /* AFS */ |