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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
12#ifdef KRB4
Damien Miller5ce662a1999-11-11 17:57:39 +110013char *ticket = NULL;
14
Damien Milleraae6c611999-12-06 11:47:28 +110015extern ServerOptions options;
16
17/*
18 * try krb4 authentication,
19 * return 1 on success, 0 on failure, -1 if krb4 is not available
20 */
21
22int
23auth_krb4_password(struct passwd * pw, const char *password)
24{
25 AUTH_DAT adata;
26 KTEXT_ST tkt;
27 struct hostent *hp;
28 unsigned long faddr;
29 char localhost[MAXHOSTNAMELEN];
30 char phost[INST_SZ];
31 char realm[REALM_SZ];
32 int r;
33
34 /*
35 * Try Kerberos password authentication only for non-root
36 * users and only if Kerberos is installed.
37 */
38 if (pw->pw_uid != 0 && krb_get_lrealm(realm, 1) == KSUCCESS) {
39
40 /* Set up our ticket file. */
41 if (!krb4_init(pw->pw_uid)) {
42 log("Couldn't initialize Kerberos ticket file for %s!",
43 pw->pw_name);
44 goto kerberos_auth_failure;
45 }
46 /* Try to get TGT using our password. */
47 r = krb_get_pw_in_tkt((char *) pw->pw_name, "",
48 realm, "krbtgt", realm,
49 DEFAULT_TKT_LIFE, (char *) password);
50 if (r != INTK_OK) {
51 packet_send_debug("Kerberos V4 password "
52 "authentication for %s failed: %s",
53 pw->pw_name, krb_err_txt[r]);
54 goto kerberos_auth_failure;
55 }
56 /* Successful authentication. */
57 chown(tkt_string(), pw->pw_uid, pw->pw_gid);
58
59 /*
60 * Now that we have a TGT, try to get a local
61 * "rcmd" ticket to ensure that we are not talking
62 * to a bogus Kerberos server.
63 */
64 (void) gethostname(localhost, sizeof(localhost));
65 (void) strlcpy(phost, (char *) krb_get_phost(localhost),
66 INST_SZ);
67 r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33);
68
69 if (r == KSUCCESS) {
70 if (!(hp = gethostbyname(localhost))) {
71 log("Couldn't get local host address!");
72 goto kerberos_auth_failure;
73 }
74 memmove((void *) &faddr, (void *) hp->h_addr,
75 sizeof(faddr));
76
77 /* Verify our "rcmd" ticket. */
78 r = krb_rd_req(&tkt, KRB4_SERVICE_NAME, phost,
79 faddr, &adata, "");
80 if (r == RD_AP_UNDEC) {
81 /*
82 * Probably didn't have a srvtab on
83 * localhost. Allow login.
84 */
85 log("Kerberos V4 TGT for %s unverifiable, "
86 "no srvtab installed? krb_rd_req: %s",
87 pw->pw_name, krb_err_txt[r]);
88 } else if (r != KSUCCESS) {
89 log("Kerberos V4 %s ticket unverifiable: %s",
90 KRB4_SERVICE_NAME, krb_err_txt[r]);
91 goto kerberos_auth_failure;
92 }
93 } else if (r == KDC_PR_UNKNOWN) {
94 /*
95 * Allow login if no rcmd service exists, but
96 * log the error.
97 */
98 log("Kerberos V4 TGT for %s unverifiable: %s; %s.%s "
99 "not registered, or srvtab is wrong?", pw->pw_name,
100 krb_err_txt[r], KRB4_SERVICE_NAME, phost);
101 } else {
102 /*
103 * TGT is bad, forget it. Possibly spoofed!
104 */
105 packet_send_debug("WARNING: Kerberos V4 TGT "
106 "possibly spoofed for %s: %s",
107 pw->pw_name, krb_err_txt[r]);
108 goto kerberos_auth_failure;
109 }
110
111 /* Authentication succeeded. */
112 return 1;
113
114kerberos_auth_failure:
115 krb4_cleanup_proc(NULL);
116
117 if (!options.kerberos_or_local_passwd)
118 return 0;
119 } else {
120 /* Logging in as root or no local Kerberos realm. */
121 packet_send_debug("Unable to authenticate to Kerberos.");
122 }
123 /* Fall back to ordinary passwd authentication. */
124 return -1;
125}
126
Damien Miller5ce662a1999-11-11 17:57:39 +1100127void
128krb4_cleanup_proc(void *ignore)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000129{
Damien Miller95def091999-11-25 00:26:21 +1100130 debug("krb4_cleanup_proc called");
131 if (ticket) {
132 (void) dest_tkt();
133 xfree(ticket);
134 ticket = NULL;
135 }
Damien Miller5ce662a1999-11-11 17:57:39 +1100136}
137
Damien Miller95def091999-11-25 00:26:21 +1100138int
139krb4_init(uid_t uid)
Damien Miller5ce662a1999-11-11 17:57:39 +1100140{
Damien Miller95def091999-11-25 00:26:21 +1100141 static int cleanup_registered = 0;
142 char *tkt_root = TKT_ROOT;
143 struct stat st;
144 int fd;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000145
Damien Miller95def091999-11-25 00:26:21 +1100146 if (!ticket) {
147 /* Set unique ticket string manually since we're still root. */
148 ticket = xmalloc(MAXPATHLEN);
Damien Miller5ce662a1999-11-11 17:57:39 +1100149#ifdef AFS
Damien Miller95def091999-11-25 00:26:21 +1100150 if (lstat("/ticket", &st) != -1)
151 tkt_root = "/ticket/";
Damien Miller5ce662a1999-11-11 17:57:39 +1100152#endif /* AFS */
Damien Miller95def091999-11-25 00:26:21 +1100153 snprintf(ticket, MAXPATHLEN, "%s%d_%d", tkt_root, uid, getpid());
154 (void) krb_set_tkt_string(ticket);
155 }
156 /* Register ticket cleanup in case of fatal error. */
157 if (!cleanup_registered) {
158 fatal_add_cleanup(krb4_cleanup_proc, NULL);
159 cleanup_registered = 1;
160 }
161 /* Try to create our ticket file. */
162 if ((fd = mkstemp(ticket)) != -1) {
163 close(fd);
164 return 1;
165 }
166 /* Ticket file exists - make sure user owns it (just passed ticket). */
167 if (lstat(ticket, &st) != -1) {
168 if (st.st_mode == (S_IFREG | S_IRUSR | S_IWUSR) &&
169 st.st_uid == uid)
170 return 1;
171 }
172 /* Failure - cancel cleanup function, leaving bad ticket for inspection. */
173 log("WARNING: bad ticket file %s", ticket);
174 fatal_remove_cleanup(krb4_cleanup_proc, NULL);
175 cleanup_registered = 0;
176 xfree(ticket);
177 ticket = NULL;
178
179 return 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000180}
181
Damien Miller95def091999-11-25 00:26:21 +1100182int
183auth_krb4(const char *server_user, KTEXT auth, char **client)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000184{
Damien Miller95def091999-11-25 00:26:21 +1100185 AUTH_DAT adat = {0};
186 KTEXT_ST reply;
187 char instance[INST_SZ];
188 int r, s;
189 u_int cksum;
190 Key_schedule schedule;
191 struct sockaddr_in local, foreign;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000192
Damien Miller95def091999-11-25 00:26:21 +1100193 s = packet_get_connection_in();
194
195 r = sizeof(local);
196 memset(&local, 0, sizeof(local));
197 if (getsockname(s, (struct sockaddr *) & local, &r) < 0)
198 debug("getsockname failed: %.100s", strerror(errno));
199 r = sizeof(foreign);
200 memset(&foreign, 0, sizeof(foreign));
201 if (getpeername(s, (struct sockaddr *) & foreign, &r) < 0) {
202 debug("getpeername failed: %.100s", strerror(errno));
203 fatal_cleanup();
204 }
205 instance[0] = '*';
206 instance[1] = 0;
207
208 /* Get the encrypted request, challenge, and session key. */
209 if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, 0, &adat, ""))) {
210 packet_send_debug("Kerberos V4 krb_rd_req: %.100s", krb_err_txt[r]);
211 return 0;
212 }
213 des_key_sched((des_cblock *) adat.session, schedule);
214
215 *client = xmalloc(MAX_K_NAME_SZ);
216 (void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname,
217 *adat.pinst ? "." : "", adat.pinst, adat.prealm);
218
219 /* Check ~/.klogin authorization now. */
220 if (kuserok(&adat, (char *) server_user) != KSUCCESS) {
221 packet_send_debug("Kerberos V4 .klogin authorization failed!");
222 log("Kerberos V4 .klogin authorization failed for %s to account %s",
223 *client, server_user);
224 xfree(*client);
225 return 0;
226 }
227 /* Increment the checksum, and return it encrypted with the
228 session key. */
229 cksum = adat.checksum + 1;
230 cksum = htonl(cksum);
231
232 /* If we can't successfully encrypt the checksum, we send back an
233 empty message, admitting our failure. */
234 if ((r = krb_mk_priv((u_char *) & cksum, reply.dat, sizeof(cksum) + 1,
235 schedule, &adat.session, &local, &foreign)) < 0) {
236 packet_send_debug("Kerberos V4 mk_priv: (%d) %s", r, krb_err_txt[r]);
237 reply.dat[0] = 0;
238 reply.length = 0;
239 } else
240 reply.length = r;
241
242 /* Clear session key. */
243 memset(&adat.session, 0, sizeof(&adat.session));
244
245 packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
246 packet_put_string((char *) reply.dat, reply.length);
247 packet_send();
248 packet_write_wait();
249 return 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000250}
251#endif /* KRB4 */
252
253#ifdef AFS
Damien Miller95def091999-11-25 00:26:21 +1100254int
255auth_kerberos_tgt(struct passwd *pw, const char *string)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000256{
Damien Miller95def091999-11-25 00:26:21 +1100257 CREDENTIALS creds;
Damien Miller5ce662a1999-11-11 17:57:39 +1100258
Damien Miller95def091999-11-25 00:26:21 +1100259 if (!radix_to_creds(string, &creds)) {
260 log("Protocol error decoding Kerberos V4 tgt");
261 packet_send_debug("Protocol error decoding Kerberos V4 tgt");
262 goto auth_kerberos_tgt_failure;
263 }
264 if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
265 strlcpy(creds.service, "krbtgt", sizeof creds.service);
266
267 if (strcmp(creds.service, "krbtgt")) {
268 log("Kerberos V4 tgt (%s%s%s@%s) rejected for %s", creds.pname,
269 creds.pinst[0] ? "." : "", creds.pinst, creds.realm,
270 pw->pw_name);
271 packet_send_debug("Kerberos V4 tgt (%s%s%s@%s) rejected for %s",
272 creds.pname, creds.pinst[0] ? "." : "", creds.pinst,
273 creds.realm, pw->pw_name);
274 goto auth_kerberos_tgt_failure;
275 }
276 if (!krb4_init(pw->pw_uid))
277 goto auth_kerberos_tgt_failure;
278
279 if (in_tkt(creds.pname, creds.pinst) != KSUCCESS)
280 goto auth_kerberos_tgt_failure;
281
282 if (save_credentials(creds.service, creds.instance, creds.realm,
283 creds.session, creds.lifetime, creds.kvno,
284 &creds.ticket_st, creds.issue_date) != KSUCCESS) {
285 packet_send_debug("Kerberos V4 tgt refused: couldn't save credentials");
286 goto auth_kerberos_tgt_failure;
287 }
288 /* Successful authentication, passed all checks. */
289 chown(tkt_string(), pw->pw_uid, pw->pw_gid);
290
291 packet_send_debug("Kerberos V4 tgt accepted (%s.%s@%s, %s%s%s@%s)",
292 creds.service, creds.instance, creds.realm, creds.pname,
293 creds.pinst[0] ? "." : "", creds.pinst, creds.realm);
294 memset(&creds, 0, sizeof(creds));
295 packet_start(SSH_SMSG_SUCCESS);
296 packet_send();
297 packet_write_wait();
298 return 1;
299
300auth_kerberos_tgt_failure:
301 krb4_cleanup_proc(NULL);
302 memset(&creds, 0, sizeof(creds));
303 packet_start(SSH_SMSG_FAILURE);
304 packet_send();
305 packet_write_wait();
306 return 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000307}
308
Damien Miller95def091999-11-25 00:26:21 +1100309int
310auth_afs_token(struct passwd *pw, const char *token_string)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000311{
Damien Miller95def091999-11-25 00:26:21 +1100312 CREDENTIALS creds;
313 uid_t uid = pw->pw_uid;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000314
Damien Miller95def091999-11-25 00:26:21 +1100315 if (!radix_to_creds(token_string, &creds)) {
316 log("Protocol error decoding AFS token");
317 packet_send_debug("Protocol error decoding AFS token");
318 packet_start(SSH_SMSG_FAILURE);
319 packet_send();
320 packet_write_wait();
321 return 0;
322 }
323 if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
324 strlcpy(creds.service, "afs", sizeof creds.service);
325
326 if (strncmp(creds.pname, "AFS ID ", 7) == 0)
327 uid = atoi(creds.pname + 7);
328
329 if (kafs_settoken(creds.realm, uid, &creds)) {
330 log("AFS token (%s@%s) rejected for %s", creds.pname, creds.realm,
331 pw->pw_name);
332 packet_send_debug("AFS token (%s@%s) rejected for %s", creds.pname,
333 creds.realm, pw->pw_name);
334 memset(&creds, 0, sizeof(creds));
335 packet_start(SSH_SMSG_FAILURE);
336 packet_send();
337 packet_write_wait();
338 return 0;
339 }
340 packet_send_debug("AFS token accepted (%s@%s, %s@%s)", creds.service,
341 creds.realm, creds.pname, creds.realm);
342 memset(&creds, 0, sizeof(creds));
343 packet_start(SSH_SMSG_SUCCESS);
344 packet_send();
345 packet_write_wait();
346 return 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000347}
348#endif /* AFS */