]> andersk Git - openssh.git/blame - auth-krb4.c
- dugsong@cvs.openbsd.org 2001/06/26 16:15:25
[openssh.git] / auth-krb4.c
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8efc0c15 1/*
bcbf86ec 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.
5260325f 23 */
8efc0c15 24
25#include "includes.h"
ced49be2 26RCSID("$OpenBSD: auth-krb4.c,v 1.24 2001/06/26 16:15:22 dugsong Exp $");
42f11eb2 27
42f11eb2 28#include "ssh.h"
29#include "ssh1.h"
8efc0c15 30#include "packet.h"
31#include "xmalloc.h"
42f11eb2 32#include "log.h"
57112b5a 33#include "servconf.h"
ced49be2 34#include "uidswap.h"
42f11eb2 35#include "auth.h"
53a24016 36
37#ifdef AFS
42f11eb2 38#include "radix.h"
53a24016 39#endif
8efc0c15 40
53a24016 41#ifdef KRB4
57112b5a 42extern ServerOptions options;
43
ced49be2 44static int
45krb4_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
57112b5a 92/*
93 * try krb4 authentication,
94 * return 1 on success, 0 on failure, -1 if krb4 is not available
95 */
6ae2364d 96int
ced49be2 97auth_krb4_password(Authctxt *authctxt, const char *password)
57112b5a 98{
99 AUTH_DAT adata;
100 KTEXT_ST tkt;
101 struct hostent *hp;
ced49be2 102 struct passwd *pw;
103 char localhost[MAXHOSTNAMELEN], phost[INST_SZ], realm[REALM_SZ];
104 u_int32_t faddr;
57112b5a 105 int r;
ced49be2 106
107 if ((pw = authctxt->pw) == NULL)
108 return (0);
109
57112b5a 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) {
57112b5a 115 /* Set up our ticket file. */
ced49be2 116 if (!krb4_init(authctxt)) {
57112b5a 117 log("Couldn't initialize Kerberos ticket file for %s!",
118 pw->pw_name);
ced49be2 119 goto failure;
57112b5a 120 }
121 /* Try to get TGT using our password. */
ced49be2 122 r = krb_get_pw_in_tkt((char *) pw->pw_name, "", realm,
123 "krbtgt", realm, DEFAULT_TKT_LIFE, (char *)password);
57112b5a 124 if (r != INTK_OK) {
ced49be2 125 debug("Kerberos v4 password authentication for %s "
126 "failed: %s", pw->pw_name, krb_err_txt[r]);
127 goto failure;
57112b5a 128 }
129 /* Successful authentication. */
130 chown(tkt_string(), pw->pw_uid, pw->pw_gid);
ced49be2 131
57112b5a 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 */
ced49be2 137 gethostname(localhost, sizeof(localhost));
138 strlcpy(phost, (char *)krb_get_phost(localhost),
139 sizeof(phost));
57112b5a 140 r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33);
ced49be2 141
57112b5a 142 if (r == KSUCCESS) {
ced49be2 143 if ((hp = gethostbyname(localhost)) == NULL) {
57112b5a 144 log("Couldn't get local host address!");
ced49be2 145 goto failure;
57112b5a 146 }
ced49be2 147 memmove((void *)&faddr, (void *)hp->h_addr,
57112b5a 148 sizeof(faddr));
ced49be2 149
57112b5a 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
c345cf9d 156 * localhost. Disallow login.
57112b5a 157 */
ced49be2 158 log("Kerberos v4 TGT for %s unverifiable, "
57112b5a 159 "no srvtab installed? krb_rd_req: %s",
160 pw->pw_name, krb_err_txt[r]);
ced49be2 161 goto failure;
57112b5a 162 } else if (r != KSUCCESS) {
ced49be2 163 log("Kerberos v4 %s ticket unverifiable: %s",
57112b5a 164 KRB4_SERVICE_NAME, krb_err_txt[r]);
ced49be2 165 goto failure;
57112b5a 166 }
167 } else if (r == KDC_PR_UNKNOWN) {
168 /*
c345cf9d 169 * Disallow login if no rcmd service exists, and
57112b5a 170 * log the error.
171 */
ced49be2 172 log("Kerberos v4 TGT for %s unverifiable: %s; %s.%s "
57112b5a 173 "not registered, or srvtab is wrong?", pw->pw_name,
ced49be2 174 krb_err_txt[r], KRB4_SERVICE_NAME, phost);
175 goto failure;
57112b5a 176 } else {
177 /*
178 * TGT is bad, forget it. Possibly spoofed!
179 */
ced49be2 180 debug("WARNING: Kerberos v4 TGT possibly spoofed "
181 "for %s: %s", pw->pw_name, krb_err_txt[r]);
182 goto failure;
57112b5a 183 }
57112b5a 184 /* Authentication succeeded. */
ced49be2 185 return (1);
186 } else
57112b5a 187 /* Logging in as root or no local Kerberos realm. */
ced49be2 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
57112b5a 196 /* Fall back to ordinary passwd authentication. */
ced49be2 197 return (-1);
57112b5a 198}
199
6a17f9c2 200void
ced49be2 201krb4_cleanup_proc(void *context)
6a17f9c2 202{
ced49be2 203 Authctxt *authctxt = (Authctxt *)context;
5260325f 204 debug("krb4_cleanup_proc called");
ced49be2 205 if (authctxt->krb4_ticket_file) {
5260325f 206 (void) dest_tkt();
ced49be2 207 xfree(authctxt->krb4_ticket_file);
208 authctxt->krb4_ticket_file = NULL;
5260325f 209 }
8efc0c15 210}
211
6ae2364d 212int
ced49be2 213auth_krb4(Authctxt *authctxt, KTEXT auth, char **client)
8efc0c15 214{
5260325f 215 AUTH_DAT adat = {0};
216 KTEXT_ST reply;
ced49be2 217 Key_schedule schedule;
218 struct sockaddr_in local, foreign;
5260325f 219 char instance[INST_SZ];
610cd5c6 220 socklen_t slen;
5260325f 221 u_int cksum;
ced49be2 222 int r, s;
223
5260325f 224 s = packet_get_connection_in();
ced49be2 225
610cd5c6 226 slen = sizeof(local);
5260325f 227 memset(&local, 0, sizeof(local));
610cd5c6 228 if (getsockname(s, (struct sockaddr *) & local, &slen) < 0)
5260325f 229 debug("getsockname failed: %.100s", strerror(errno));
610cd5c6 230 slen = sizeof(foreign);
5260325f 231 memset(&foreign, 0, sizeof(foreign));
610cd5c6 232 if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) {
5260325f 233 debug("getpeername failed: %.100s", strerror(errno));
234 fatal_cleanup();
235 }
236 instance[0] = '*';
237 instance[1] = 0;
ced49be2 238
5260325f 239 /* Get the encrypted request, challenge, and session key. */
ced49be2 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);
5260325f 244 }
245 des_key_sched((des_cblock *) adat.session, schedule);
ced49be2 246
5260325f 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);
ced49be2 250
5260325f 251 /* Check ~/.klogin authorization now. */
ced49be2 252 if (kuserok(&adat, authctxt->user) != KSUCCESS) {
253 log("Kerberos v4 .klogin authorization failed for %s to "
254 "account %s", *client, authctxt->user);
5260325f 255 xfree(*client);
ced49be2 256 return (0);
5260325f 257 }
258 /* Increment the checksum, and return it encrypted with the
259 session key. */
260 cksum = adat.checksum + 1;
261 cksum = htonl(cksum);
ced49be2 262
5260325f 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) {
ced49be2 267 debug("Kerberos v4 mk_priv: (%d) %s", r, krb_err_txt[r]);
5260325f 268 reply.dat[0] = 0;
269 reply.length = 0;
270 } else
271 reply.length = r;
ced49be2 272
5260325f 273 /* Clear session key. */
274 memset(&adat.session, 0, sizeof(&adat.session));
ced49be2 275
5260325f 276 packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
277 packet_put_string((char *) reply.dat, reply.length);
278 packet_send();
279 packet_write_wait();
ced49be2 280 return (1);
8efc0c15 281}
282#endif /* KRB4 */
283
284#ifdef AFS
6ae2364d 285int
ced49be2 286auth_krb4_tgt(Authctxt *authctxt, const char *string)
8efc0c15 287{
5260325f 288 CREDENTIALS creds;
ced49be2 289 struct passwd *pw;
290
291 if ((pw = authctxt->pw) == NULL)
292 goto failure;
293
294 temporarily_use_uid(pw);
295
5260325f 296 if (!radix_to_creds(string, &creds)) {
ced49be2 297 log("Protocol error decoding Kerberos v4 TGT");
298 goto failure;
5260325f 299 }
300 if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
301 strlcpy(creds.service, "krbtgt", sizeof creds.service);
ced49be2 302
5260325f 303 if (strcmp(creds.service, "krbtgt")) {
ced49be2 304 log("Kerberos v4 TGT (%s%s%s@%s) rejected for %s",
5260325f 305 creds.pname, creds.pinst[0] ? "." : "", creds.pinst,
306 creds.realm, pw->pw_name);
ced49be2 307 goto failure;
5260325f 308 }
ced49be2 309 if (!krb4_init(authctxt))
310 goto failure;
311
5260325f 312 if (in_tkt(creds.pname, creds.pinst) != KSUCCESS)
ced49be2 313 goto failure;
314
5260325f 315 if (save_credentials(creds.service, creds.instance, creds.realm,
ced49be2 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;
5260325f 320 }
321 /* Successful authentication, passed all checks. */
322 chown(tkt_string(), pw->pw_uid, pw->pw_gid);
ced49be2 323
324 debug("Kerberos v4 TGT accepted (%s%s%s@%s)",
325 creds.pname, creds.pinst[0] ? "." : "", creds.pinst, creds.realm);
5260325f 326 memset(&creds, 0, sizeof(creds));
ced49be2 327
328 restore_uid();
329
330 return (1);
331
332 failure:
333 krb4_cleanup_proc(authctxt);
5260325f 334 memset(&creds, 0, sizeof(creds));
ced49be2 335 restore_uid();
336
337 return (0);
8efc0c15 338}
339
6ae2364d 340int
ced49be2 341auth_afs_token(Authctxt *authctxt, const char *token_string)
8efc0c15 342{
5260325f 343 CREDENTIALS creds;
ced49be2 344 struct passwd *pw;
94ec8c6b 345 uid_t uid;
ced49be2 346
347 if ((pw = authctxt->pw) == NULL)
348 return (0);
349
5260325f 350 if (!radix_to_creds(token_string, &creds)) {
351 log("Protocol error decoding AFS token");
ced49be2 352 return (0);
5260325f 353 }
354 if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
355 strlcpy(creds.service, "afs", sizeof creds.service);
ced49be2 356
5260325f 357 if (strncmp(creds.pname, "AFS ID ", 7) == 0)
358 uid = atoi(creds.pname + 7);
94ec8c6b 359 else
360 uid = pw->pw_uid;
ced49be2 361
5260325f 362 if (kafs_settoken(creds.realm, uid, &creds)) {
ced49be2 363 log("AFS token (%s@%s) rejected for %s",
364 creds.pname, creds.realm, pw->pw_name);
5260325f 365 memset(&creds, 0, sizeof(creds));
ced49be2 366 return (0);
5260325f 367 }
ced49be2 368 debug("AFS token accepted (%s@%s)", creds.pname, creds.realm);
5260325f 369 memset(&creds, 0, sizeof(creds));
ced49be2 370
371 return (1);
8efc0c15 372}
373#endif /* AFS */
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