Annotation of src/usr.bin/ssh/auth-krb4.c, Revision 1.22
1.1 deraadt 1: /*
1.18 deraadt 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.
1.10 deraadt 23: */
1.1 deraadt 24:
25: #include "includes.h"
1.22 ! markus 26: RCSID("$OpenBSD: auth-krb4.c,v 1.21 2001/01/19 15:55:10 markus Exp $");
! 27:
! 28: #include "ssh.h"
! 29: #include "ssh1.h"
1.1 deraadt 30: #include "packet.h"
31: #include "xmalloc.h"
1.22 ! markus 32: #include "log.h"
1.11 markus 33: #include "servconf.h"
1.22 ! markus 34: #include "auth.h"
! 35: #include "radix.h"
1.15 djm 36:
1.1 deraadt 37: #ifdef KRB4
1.6 markus 38: char *ticket = NULL;
1.11 markus 39:
40: extern ServerOptions options;
41:
42: /*
43: * try krb4 authentication,
44: * return 1 on success, 0 on failure, -1 if krb4 is not available
45: */
46:
1.14 markus 47: int
1.11 markus 48: auth_krb4_password(struct passwd * pw, const char *password)
49: {
50: AUTH_DAT adata;
51: KTEXT_ST tkt;
52: struct hostent *hp;
1.20 markus 53: u_long faddr;
1.11 markus 54: char localhost[MAXHOSTNAMELEN];
55: char phost[INST_SZ];
56: char realm[REALM_SZ];
57: int r;
58:
59: /*
60: * Try Kerberos password authentication only for non-root
61: * users and only if Kerberos is installed.
62: */
63: if (pw->pw_uid != 0 && krb_get_lrealm(realm, 1) == KSUCCESS) {
64:
65: /* Set up our ticket file. */
66: if (!krb4_init(pw->pw_uid)) {
67: log("Couldn't initialize Kerberos ticket file for %s!",
68: pw->pw_name);
69: goto kerberos_auth_failure;
70: }
71: /* Try to get TGT using our password. */
72: r = krb_get_pw_in_tkt((char *) pw->pw_name, "",
73: realm, "krbtgt", realm,
74: DEFAULT_TKT_LIFE, (char *) password);
75: if (r != INTK_OK) {
76: packet_send_debug("Kerberos V4 password "
77: "authentication for %s failed: %s",
78: pw->pw_name, krb_err_txt[r]);
79: goto kerberos_auth_failure;
80: }
81: /* Successful authentication. */
82: chown(tkt_string(), pw->pw_uid, pw->pw_gid);
83:
84: /*
85: * Now that we have a TGT, try to get a local
86: * "rcmd" ticket to ensure that we are not talking
87: * to a bogus Kerberos server.
88: */
89: (void) gethostname(localhost, sizeof(localhost));
90: (void) strlcpy(phost, (char *) krb_get_phost(localhost),
91: INST_SZ);
92: r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33);
93:
94: if (r == KSUCCESS) {
95: if (!(hp = gethostbyname(localhost))) {
96: log("Couldn't get local host address!");
97: goto kerberos_auth_failure;
98: }
99: memmove((void *) &faddr, (void *) hp->h_addr,
100: sizeof(faddr));
101:
102: /* Verify our "rcmd" ticket. */
103: r = krb_rd_req(&tkt, KRB4_SERVICE_NAME, phost,
104: faddr, &adata, "");
105: if (r == RD_AP_UNDEC) {
106: /*
107: * Probably didn't have a srvtab on
1.16 provos 108: * localhost. Disallow login.
1.11 markus 109: */
110: log("Kerberos V4 TGT for %s unverifiable, "
111: "no srvtab installed? krb_rd_req: %s",
112: pw->pw_name, krb_err_txt[r]);
1.16 provos 113: goto kerberos_auth_failure;
1.11 markus 114: } else if (r != KSUCCESS) {
115: log("Kerberos V4 %s ticket unverifiable: %s",
116: KRB4_SERVICE_NAME, krb_err_txt[r]);
117: goto kerberos_auth_failure;
118: }
119: } else if (r == KDC_PR_UNKNOWN) {
120: /*
1.16 provos 121: * Disallow login if no rcmd service exists, and
1.11 markus 122: * log the error.
123: */
124: log("Kerberos V4 TGT for %s unverifiable: %s; %s.%s "
125: "not registered, or srvtab is wrong?", pw->pw_name,
126: krb_err_txt[r], KRB4_SERVICE_NAME, phost);
1.16 provos 127: goto kerberos_auth_failure;
1.11 markus 128: } else {
129: /*
130: * TGT is bad, forget it. Possibly spoofed!
131: */
132: packet_send_debug("WARNING: Kerberos V4 TGT "
133: "possibly spoofed for %s: %s",
134: pw->pw_name, krb_err_txt[r]);
135: goto kerberos_auth_failure;
136: }
137:
138: /* Authentication succeeded. */
139: return 1;
140:
141: kerberos_auth_failure:
142: krb4_cleanup_proc(NULL);
143:
144: if (!options.kerberos_or_local_passwd)
145: return 0;
146: } else {
147: /* Logging in as root or no local Kerberos realm. */
148: packet_send_debug("Unable to authenticate to Kerberos.");
149: }
150: /* Fall back to ordinary passwd authentication. */
151: return -1;
152: }
1.6 markus 153:
154: void
155: krb4_cleanup_proc(void *ignore)
1.1 deraadt 156: {
1.9 markus 157: debug("krb4_cleanup_proc called");
158: if (ticket) {
159: (void) dest_tkt();
160: xfree(ticket);
161: ticket = NULL;
162: }
1.6 markus 163: }
164:
1.14 markus 165: int
1.9 markus 166: krb4_init(uid_t uid)
1.6 markus 167: {
1.9 markus 168: static int cleanup_registered = 0;
1.13 markus 169: const char *tkt_root = TKT_ROOT;
1.9 markus 170: struct stat st;
171: int fd;
172:
173: if (!ticket) {
174: /* Set unique ticket string manually since we're still root. */
175: ticket = xmalloc(MAXPATHLEN);
1.1 deraadt 176: #ifdef AFS
1.9 markus 177: if (lstat("/ticket", &st) != -1)
178: tkt_root = "/ticket/";
1.1 deraadt 179: #endif /* AFS */
1.17 deraadt 180: snprintf(ticket, MAXPATHLEN, "%s%u_%d", tkt_root, uid, getpid());
1.9 markus 181: (void) krb_set_tkt_string(ticket);
182: }
183: /* Register ticket cleanup in case of fatal error. */
184: if (!cleanup_registered) {
185: fatal_add_cleanup(krb4_cleanup_proc, NULL);
186: cleanup_registered = 1;
187: }
188: /* Try to create our ticket file. */
189: if ((fd = mkstemp(ticket)) != -1) {
190: close(fd);
191: return 1;
192: }
193: /* Ticket file exists - make sure user owns it (just passed ticket). */
194: if (lstat(ticket, &st) != -1) {
195: if (st.st_mode == (S_IFREG | S_IRUSR | S_IWUSR) &&
196: st.st_uid == uid)
197: return 1;
198: }
199: /* Failure - cancel cleanup function, leaving bad ticket for inspection. */
200: log("WARNING: bad ticket file %s", ticket);
201: fatal_remove_cleanup(krb4_cleanup_proc, NULL);
202: cleanup_registered = 0;
203: xfree(ticket);
204: ticket = NULL;
205:
206: return 0;
1.1 deraadt 207: }
208:
1.14 markus 209: int
1.9 markus 210: auth_krb4(const char *server_user, KTEXT auth, char **client)
1.1 deraadt 211: {
1.9 markus 212: AUTH_DAT adat = {0};
213: KTEXT_ST reply;
214: char instance[INST_SZ];
215: int r, s;
1.12 markus 216: socklen_t slen;
1.9 markus 217: u_int cksum;
218: Key_schedule schedule;
219: struct sockaddr_in local, foreign;
220:
221: s = packet_get_connection_in();
222:
1.12 markus 223: slen = sizeof(local);
1.9 markus 224: memset(&local, 0, sizeof(local));
1.12 markus 225: if (getsockname(s, (struct sockaddr *) & local, &slen) < 0)
1.9 markus 226: debug("getsockname failed: %.100s", strerror(errno));
1.12 markus 227: slen = sizeof(foreign);
1.9 markus 228: memset(&foreign, 0, sizeof(foreign));
1.12 markus 229: if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) {
1.9 markus 230: debug("getpeername failed: %.100s", strerror(errno));
231: fatal_cleanup();
232: }
233: instance[0] = '*';
234: instance[1] = 0;
235:
236: /* Get the encrypted request, challenge, and session key. */
237: if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, 0, &adat, ""))) {
238: packet_send_debug("Kerberos V4 krb_rd_req: %.100s", krb_err_txt[r]);
239: return 0;
240: }
241: des_key_sched((des_cblock *) adat.session, schedule);
242:
243: *client = xmalloc(MAX_K_NAME_SZ);
244: (void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname,
1.10 deraadt 245: *adat.pinst ? "." : "", adat.pinst, adat.prealm);
1.9 markus 246:
247: /* Check ~/.klogin authorization now. */
248: if (kuserok(&adat, (char *) server_user) != KSUCCESS) {
249: packet_send_debug("Kerberos V4 .klogin authorization failed!");
250: log("Kerberos V4 .klogin authorization failed for %s to account %s",
251: *client, server_user);
252: xfree(*client);
253: return 0;
254: }
255: /* Increment the checksum, and return it encrypted with the
256: session key. */
257: cksum = adat.checksum + 1;
258: cksum = htonl(cksum);
259:
260: /* If we can't successfully encrypt the checksum, we send back an
261: empty message, admitting our failure. */
262: if ((r = krb_mk_priv((u_char *) & cksum, reply.dat, sizeof(cksum) + 1,
1.10 deraadt 263: schedule, &adat.session, &local, &foreign)) < 0) {
1.9 markus 264: packet_send_debug("Kerberos V4 mk_priv: (%d) %s", r, krb_err_txt[r]);
265: reply.dat[0] = 0;
266: reply.length = 0;
267: } else
268: reply.length = r;
269:
270: /* Clear session key. */
271: memset(&adat.session, 0, sizeof(&adat.session));
272:
273: packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
274: packet_put_string((char *) reply.dat, reply.length);
275: packet_send();
276: packet_write_wait();
277: return 1;
1.1 deraadt 278: }
279: #endif /* KRB4 */
280:
281: #ifdef AFS
1.14 markus 282: int
1.9 markus 283: auth_kerberos_tgt(struct passwd *pw, const char *string)
1.1 deraadt 284: {
1.9 markus 285: CREDENTIALS creds;
286:
1.19 markus 287: if (pw == NULL)
288: goto auth_kerberos_tgt_failure;
1.9 markus 289: if (!radix_to_creds(string, &creds)) {
290: log("Protocol error decoding Kerberos V4 tgt");
291: packet_send_debug("Protocol error decoding Kerberos V4 tgt");
292: goto auth_kerberos_tgt_failure;
293: }
294: if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
295: strlcpy(creds.service, "krbtgt", sizeof creds.service);
296:
297: if (strcmp(creds.service, "krbtgt")) {
298: log("Kerberos V4 tgt (%s%s%s@%s) rejected for %s", creds.pname,
1.10 deraadt 299: creds.pinst[0] ? "." : "", creds.pinst, creds.realm,
300: pw->pw_name);
1.9 markus 301: packet_send_debug("Kerberos V4 tgt (%s%s%s@%s) rejected for %s",
1.10 deraadt 302: creds.pname, creds.pinst[0] ? "." : "", creds.pinst,
303: creds.realm, pw->pw_name);
1.9 markus 304: goto auth_kerberos_tgt_failure;
305: }
306: if (!krb4_init(pw->pw_uid))
307: goto auth_kerberos_tgt_failure;
308:
309: if (in_tkt(creds.pname, creds.pinst) != KSUCCESS)
310: goto auth_kerberos_tgt_failure;
311:
312: if (save_credentials(creds.service, creds.instance, creds.realm,
1.10 deraadt 313: creds.session, creds.lifetime, creds.kvno,
314: &creds.ticket_st, creds.issue_date) != KSUCCESS) {
1.9 markus 315: packet_send_debug("Kerberos V4 tgt refused: couldn't save credentials");
316: goto auth_kerberos_tgt_failure;
317: }
318: /* Successful authentication, passed all checks. */
319: chown(tkt_string(), pw->pw_uid, pw->pw_gid);
320:
321: packet_send_debug("Kerberos V4 tgt accepted (%s.%s@%s, %s%s%s@%s)",
1.10 deraadt 322: creds.service, creds.instance, creds.realm, creds.pname,
323: creds.pinst[0] ? "." : "", creds.pinst, creds.realm);
1.9 markus 324: memset(&creds, 0, sizeof(creds));
325: packet_start(SSH_SMSG_SUCCESS);
326: packet_send();
327: packet_write_wait();
328: return 1;
329:
330: auth_kerberos_tgt_failure:
331: krb4_cleanup_proc(NULL);
332: memset(&creds, 0, sizeof(creds));
333: packet_start(SSH_SMSG_FAILURE);
334: packet_send();
335: packet_write_wait();
336: return 0;
1.1 deraadt 337: }
338:
1.14 markus 339: int
1.9 markus 340: auth_afs_token(struct passwd *pw, const char *token_string)
1.1 deraadt 341: {
1.9 markus 342: CREDENTIALS creds;
1.19 markus 343: uid_t uid;
1.1 deraadt 344:
1.19 markus 345: if (pw == NULL) {
346: /* XXX fake protocol error */
347: packet_send_debug("Protocol error decoding AFS token");
348: packet_start(SSH_SMSG_FAILURE);
349: packet_send();
350: packet_write_wait();
351: return 0;
352: }
1.9 markus 353: if (!radix_to_creds(token_string, &creds)) {
354: log("Protocol error decoding AFS token");
355: packet_send_debug("Protocol error decoding AFS token");
356: packet_start(SSH_SMSG_FAILURE);
357: packet_send();
358: packet_write_wait();
359: return 0;
360: }
361: if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
362: strlcpy(creds.service, "afs", sizeof creds.service);
363:
364: if (strncmp(creds.pname, "AFS ID ", 7) == 0)
365: uid = atoi(creds.pname + 7);
1.19 markus 366: else
367: uid = pw->pw_uid;
1.9 markus 368:
369: if (kafs_settoken(creds.realm, uid, &creds)) {
370: log("AFS token (%s@%s) rejected for %s", creds.pname, creds.realm,
371: pw->pw_name);
372: packet_send_debug("AFS token (%s@%s) rejected for %s", creds.pname,
1.10 deraadt 373: creds.realm, pw->pw_name);
1.9 markus 374: memset(&creds, 0, sizeof(creds));
375: packet_start(SSH_SMSG_FAILURE);
376: packet_send();
377: packet_write_wait();
378: return 0;
379: }
380: packet_send_debug("AFS token accepted (%s@%s, %s@%s)", creds.service,
1.10 deraadt 381: creds.realm, creds.pname, creds.realm);
1.9 markus 382: memset(&creds, 0, sizeof(creds));
383: packet_start(SSH_SMSG_SUCCESS);
384: packet_send();
385: packet_write_wait();
386: return 1;
1.1 deraadt 387: }
388: #endif /* AFS */
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