blob: e32089b74379a7edfebdd31b87c6a9dcd8e75d04 [file] [log] [blame]
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001/*
Damien Miller95def091999-11-25 00:26:21 +11002 * Dug Song <dugsong@UMICH.EDU>
3 * Kerberos v4 authentication and ticket-passing routines.
4 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +10005
6#include "includes.h"
7#include "packet.h"
8#include "xmalloc.h"
9#include "ssh.h"
Damien Milleraae6c611999-12-06 11:47:28 +110010#include "servconf.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100011
Damien Millerbf7f4662000-06-23 10:16:38 +100012RCSID("$OpenBSD: auth-krb4.c,v 1.15 2000/06/22 23:54:59 djm Exp $");
13
Damien Millerd4a8b7e1999-10-27 13:42:43 +100014#ifdef KRB4
Damien Miller5ce662a1999-11-11 17:57:39 +110015char *ticket = NULL;
16
Damien Milleraae6c611999-12-06 11:47:28 +110017extern ServerOptions options;
18
19/*
20 * try krb4 authentication,
21 * return 1 on success, 0 on failure, -1 if krb4 is not available
22 */
23
Damien Miller4af51302000-04-16 11:18:38 +100024int
Damien Milleraae6c611999-12-06 11:47:28 +110025auth_krb4_password(struct passwd * pw, const char *password)
26{
27 AUTH_DAT adata;
28 KTEXT_ST tkt;
29 struct hostent *hp;
30 unsigned long faddr;
31 char localhost[MAXHOSTNAMELEN];
32 char phost[INST_SZ];
33 char realm[REALM_SZ];
34 int r;
35
36 /*
37 * Try Kerberos password authentication only for non-root
38 * users and only if Kerberos is installed.
39 */
40 if (pw->pw_uid != 0 && krb_get_lrealm(realm, 1) == KSUCCESS) {
41
42 /* Set up our ticket file. */
43 if (!krb4_init(pw->pw_uid)) {
44 log("Couldn't initialize Kerberos ticket file for %s!",
45 pw->pw_name);
46 goto kerberos_auth_failure;
47 }
48 /* Try to get TGT using our password. */
49 r = krb_get_pw_in_tkt((char *) pw->pw_name, "",
50 realm, "krbtgt", realm,
51 DEFAULT_TKT_LIFE, (char *) password);
52 if (r != INTK_OK) {
53 packet_send_debug("Kerberos V4 password "
54 "authentication for %s failed: %s",
55 pw->pw_name, krb_err_txt[r]);
56 goto kerberos_auth_failure;
57 }
58 /* Successful authentication. */
59 chown(tkt_string(), pw->pw_uid, pw->pw_gid);
60
61 /*
62 * Now that we have a TGT, try to get a local
63 * "rcmd" ticket to ensure that we are not talking
64 * to a bogus Kerberos server.
65 */
66 (void) gethostname(localhost, sizeof(localhost));
67 (void) strlcpy(phost, (char *) krb_get_phost(localhost),
68 INST_SZ);
69 r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33);
70
71 if (r == KSUCCESS) {
72 if (!(hp = gethostbyname(localhost))) {
73 log("Couldn't get local host address!");
74 goto kerberos_auth_failure;
75 }
76 memmove((void *) &faddr, (void *) hp->h_addr,
77 sizeof(faddr));
78
79 /* Verify our "rcmd" ticket. */
80 r = krb_rd_req(&tkt, KRB4_SERVICE_NAME, phost,
81 faddr, &adata, "");
82 if (r == RD_AP_UNDEC) {
83 /*
84 * Probably didn't have a srvtab on
85 * localhost. Allow login.
86 */
87 log("Kerberos V4 TGT for %s unverifiable, "
88 "no srvtab installed? krb_rd_req: %s",
89 pw->pw_name, krb_err_txt[r]);
90 } else if (r != KSUCCESS) {
91 log("Kerberos V4 %s ticket unverifiable: %s",
92 KRB4_SERVICE_NAME, krb_err_txt[r]);
93 goto kerberos_auth_failure;
94 }
95 } else if (r == KDC_PR_UNKNOWN) {
96 /*
97 * Allow login if no rcmd service exists, but
98 * log the error.
99 */
100 log("Kerberos V4 TGT for %s unverifiable: %s; %s.%s "
101 "not registered, or srvtab is wrong?", pw->pw_name,
102 krb_err_txt[r], KRB4_SERVICE_NAME, phost);
103 } else {
104 /*
105 * TGT is bad, forget it. Possibly spoofed!
106 */
107 packet_send_debug("WARNING: Kerberos V4 TGT "
108 "possibly spoofed for %s: %s",
109 pw->pw_name, krb_err_txt[r]);
110 goto kerberos_auth_failure;
111 }
112
113 /* Authentication succeeded. */
114 return 1;
115
116kerberos_auth_failure:
117 krb4_cleanup_proc(NULL);
118
119 if (!options.kerberos_or_local_passwd)
120 return 0;
121 } else {
122 /* Logging in as root or no local Kerberos realm. */
123 packet_send_debug("Unable to authenticate to Kerberos.");
124 }
125 /* Fall back to ordinary passwd authentication. */
126 return -1;
127}
128
Damien Miller5ce662a1999-11-11 17:57:39 +1100129void
130krb4_cleanup_proc(void *ignore)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000131{
Damien Miller95def091999-11-25 00:26:21 +1100132 debug("krb4_cleanup_proc called");
133 if (ticket) {
134 (void) dest_tkt();
135 xfree(ticket);
136 ticket = NULL;
137 }
Damien Miller5ce662a1999-11-11 17:57:39 +1100138}
139
Damien Miller4af51302000-04-16 11:18:38 +1000140int
Damien Miller95def091999-11-25 00:26:21 +1100141krb4_init(uid_t uid)
Damien Miller5ce662a1999-11-11 17:57:39 +1100142{
Damien Miller95def091999-11-25 00:26:21 +1100143 static int cleanup_registered = 0;
Damien Miller450a7a12000-03-26 13:04:51 +1000144 const char *tkt_root = TKT_ROOT;
Damien Miller95def091999-11-25 00:26:21 +1100145 struct stat st;
146 int fd;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000147
Damien Miller95def091999-11-25 00:26:21 +1100148 if (!ticket) {
149 /* Set unique ticket string manually since we're still root. */
150 ticket = xmalloc(MAXPATHLEN);
Damien Miller5ce662a1999-11-11 17:57:39 +1100151#ifdef AFS
Damien Miller95def091999-11-25 00:26:21 +1100152 if (lstat("/ticket", &st) != -1)
153 tkt_root = "/ticket/";
Damien Miller5ce662a1999-11-11 17:57:39 +1100154#endif /* AFS */
Damien Miller95def091999-11-25 00:26:21 +1100155 snprintf(ticket, MAXPATHLEN, "%s%d_%d", tkt_root, uid, getpid());
156 (void) krb_set_tkt_string(ticket);
157 }
158 /* Register ticket cleanup in case of fatal error. */
159 if (!cleanup_registered) {
160 fatal_add_cleanup(krb4_cleanup_proc, NULL);
161 cleanup_registered = 1;
162 }
163 /* Try to create our ticket file. */
164 if ((fd = mkstemp(ticket)) != -1) {
165 close(fd);
166 return 1;
167 }
168 /* Ticket file exists - make sure user owns it (just passed ticket). */
169 if (lstat(ticket, &st) != -1) {
170 if (st.st_mode == (S_IFREG | S_IRUSR | S_IWUSR) &&
171 st.st_uid == uid)
172 return 1;
173 }
174 /* Failure - cancel cleanup function, leaving bad ticket for inspection. */
175 log("WARNING: bad ticket file %s", ticket);
176 fatal_remove_cleanup(krb4_cleanup_proc, NULL);
177 cleanup_registered = 0;
178 xfree(ticket);
179 ticket = NULL;
180
181 return 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000182}
183
Damien Miller4af51302000-04-16 11:18:38 +1000184int
Damien Miller95def091999-11-25 00:26:21 +1100185auth_krb4(const char *server_user, KTEXT auth, char **client)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000186{
Damien Miller95def091999-11-25 00:26:21 +1100187 AUTH_DAT adat = {0};
188 KTEXT_ST reply;
189 char instance[INST_SZ];
190 int r, s;
Damien Miller7684ee12000-03-17 23:40:15 +1100191 socklen_t slen;
Damien Miller95def091999-11-25 00:26:21 +1100192 u_int cksum;
193 Key_schedule schedule;
194 struct sockaddr_in local, foreign;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000195
Damien Miller95def091999-11-25 00:26:21 +1100196 s = packet_get_connection_in();
197
Damien Miller7684ee12000-03-17 23:40:15 +1100198 slen = sizeof(local);
Damien Miller95def091999-11-25 00:26:21 +1100199 memset(&local, 0, sizeof(local));
Damien Miller7684ee12000-03-17 23:40:15 +1100200 if (getsockname(s, (struct sockaddr *) & local, &slen) < 0)
Damien Miller95def091999-11-25 00:26:21 +1100201 debug("getsockname failed: %.100s", strerror(errno));
Damien Miller7684ee12000-03-17 23:40:15 +1100202 slen = sizeof(foreign);
Damien Miller95def091999-11-25 00:26:21 +1100203 memset(&foreign, 0, sizeof(foreign));
Damien Miller7684ee12000-03-17 23:40:15 +1100204 if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) {
Damien Miller95def091999-11-25 00:26:21 +1100205 debug("getpeername failed: %.100s", strerror(errno));
206 fatal_cleanup();
207 }
208 instance[0] = '*';
209 instance[1] = 0;
210
211 /* Get the encrypted request, challenge, and session key. */
212 if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, 0, &adat, ""))) {
213 packet_send_debug("Kerberos V4 krb_rd_req: %.100s", krb_err_txt[r]);
214 return 0;
215 }
216 des_key_sched((des_cblock *) adat.session, schedule);
217
218 *client = xmalloc(MAX_K_NAME_SZ);
219 (void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname,
220 *adat.pinst ? "." : "", adat.pinst, adat.prealm);
221
222 /* Check ~/.klogin authorization now. */
223 if (kuserok(&adat, (char *) server_user) != KSUCCESS) {
224 packet_send_debug("Kerberos V4 .klogin authorization failed!");
225 log("Kerberos V4 .klogin authorization failed for %s to account %s",
226 *client, server_user);
227 xfree(*client);
228 return 0;
229 }
230 /* Increment the checksum, and return it encrypted with the
231 session key. */
232 cksum = adat.checksum + 1;
233 cksum = htonl(cksum);
234
235 /* If we can't successfully encrypt the checksum, we send back an
236 empty message, admitting our failure. */
237 if ((r = krb_mk_priv((u_char *) & cksum, reply.dat, sizeof(cksum) + 1,
238 schedule, &adat.session, &local, &foreign)) < 0) {
239 packet_send_debug("Kerberos V4 mk_priv: (%d) %s", r, krb_err_txt[r]);
240 reply.dat[0] = 0;
241 reply.length = 0;
242 } else
243 reply.length = r;
244
245 /* Clear session key. */
246 memset(&adat.session, 0, sizeof(&adat.session));
247
248 packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
249 packet_put_string((char *) reply.dat, reply.length);
250 packet_send();
251 packet_write_wait();
252 return 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000253}
254#endif /* KRB4 */
255
256#ifdef AFS
Damien Miller4af51302000-04-16 11:18:38 +1000257int
Damien Miller95def091999-11-25 00:26:21 +1100258auth_kerberos_tgt(struct passwd *pw, const char *string)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000259{
Damien Miller95def091999-11-25 00:26:21 +1100260 CREDENTIALS creds;
Damien Miller5ce662a1999-11-11 17:57:39 +1100261
Damien Miller95def091999-11-25 00:26:21 +1100262 if (!radix_to_creds(string, &creds)) {
263 log("Protocol error decoding Kerberos V4 tgt");
264 packet_send_debug("Protocol error decoding Kerberos V4 tgt");
265 goto auth_kerberos_tgt_failure;
266 }
267 if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
268 strlcpy(creds.service, "krbtgt", sizeof creds.service);
269
270 if (strcmp(creds.service, "krbtgt")) {
271 log("Kerberos V4 tgt (%s%s%s@%s) rejected for %s", creds.pname,
272 creds.pinst[0] ? "." : "", creds.pinst, creds.realm,
273 pw->pw_name);
274 packet_send_debug("Kerberos V4 tgt (%s%s%s@%s) rejected for %s",
275 creds.pname, creds.pinst[0] ? "." : "", creds.pinst,
276 creds.realm, pw->pw_name);
277 goto auth_kerberos_tgt_failure;
278 }
279 if (!krb4_init(pw->pw_uid))
280 goto auth_kerberos_tgt_failure;
281
282 if (in_tkt(creds.pname, creds.pinst) != KSUCCESS)
283 goto auth_kerberos_tgt_failure;
284
285 if (save_credentials(creds.service, creds.instance, creds.realm,
286 creds.session, creds.lifetime, creds.kvno,
287 &creds.ticket_st, creds.issue_date) != KSUCCESS) {
288 packet_send_debug("Kerberos V4 tgt refused: couldn't save credentials");
289 goto auth_kerberos_tgt_failure;
290 }
291 /* Successful authentication, passed all checks. */
292 chown(tkt_string(), pw->pw_uid, pw->pw_gid);
293
294 packet_send_debug("Kerberos V4 tgt accepted (%s.%s@%s, %s%s%s@%s)",
295 creds.service, creds.instance, creds.realm, creds.pname,
296 creds.pinst[0] ? "." : "", creds.pinst, creds.realm);
297 memset(&creds, 0, sizeof(creds));
298 packet_start(SSH_SMSG_SUCCESS);
299 packet_send();
300 packet_write_wait();
301 return 1;
302
303auth_kerberos_tgt_failure:
304 krb4_cleanup_proc(NULL);
305 memset(&creds, 0, sizeof(creds));
306 packet_start(SSH_SMSG_FAILURE);
307 packet_send();
308 packet_write_wait();
309 return 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000310}
311
Damien Miller4af51302000-04-16 11:18:38 +1000312int
Damien Miller95def091999-11-25 00:26:21 +1100313auth_afs_token(struct passwd *pw, const char *token_string)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000314{
Damien Miller95def091999-11-25 00:26:21 +1100315 CREDENTIALS creds;
316 uid_t uid = pw->pw_uid;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000317
Damien Miller95def091999-11-25 00:26:21 +1100318 if (!radix_to_creds(token_string, &creds)) {
319 log("Protocol error decoding AFS token");
320 packet_send_debug("Protocol error decoding AFS token");
321 packet_start(SSH_SMSG_FAILURE);
322 packet_send();
323 packet_write_wait();
324 return 0;
325 }
326 if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
327 strlcpy(creds.service, "afs", sizeof creds.service);
328
329 if (strncmp(creds.pname, "AFS ID ", 7) == 0)
330 uid = atoi(creds.pname + 7);
331
332 if (kafs_settoken(creds.realm, uid, &creds)) {
333 log("AFS token (%s@%s) rejected for %s", creds.pname, creds.realm,
334 pw->pw_name);
335 packet_send_debug("AFS token (%s@%s) rejected for %s", creds.pname,
336 creds.realm, pw->pw_name);
337 memset(&creds, 0, sizeof(creds));
338 packet_start(SSH_SMSG_FAILURE);
339 packet_send();
340 packet_write_wait();
341 return 0;
342 }
343 packet_send_debug("AFS token accepted (%s@%s, %s@%s)", creds.service,
344 creds.realm, creds.pname, creds.realm);
345 memset(&creds, 0, sizeof(creds));
346 packet_start(SSH_SMSG_SUCCESS);
347 packet_send();
348 packet_write_wait();
349 return 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000350}
351#endif /* AFS */