Annotation of src/usr.bin/ssh/auth-krb4.c, Revision 1.18
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"
26: #include "packet.h"
27: #include "xmalloc.h"
28: #include "ssh.h"
1.11 markus 29: #include "servconf.h"
1.1 deraadt 30:
1.18 ! deraadt 31: RCSID("$OpenBSD: auth-krb4.c,v 1.17 2000/08/28 03:50:54 deraadt Exp $");
1.15 djm 32:
1.1 deraadt 33: #ifdef KRB4
1.6 markus 34: char *ticket = NULL;
1.11 markus 35:
36: extern ServerOptions options;
37:
38: /*
39: * try krb4 authentication,
40: * return 1 on success, 0 on failure, -1 if krb4 is not available
41: */
42:
1.14 markus 43: int
1.11 markus 44: auth_krb4_password(struct passwd * pw, const char *password)
45: {
46: AUTH_DAT adata;
47: KTEXT_ST tkt;
48: struct hostent *hp;
49: unsigned long faddr;
50: char localhost[MAXHOSTNAMELEN];
51: char phost[INST_SZ];
52: char realm[REALM_SZ];
53: int r;
54:
55: /*
56: * Try Kerberos password authentication only for non-root
57: * users and only if Kerberos is installed.
58: */
59: if (pw->pw_uid != 0 && krb_get_lrealm(realm, 1) == KSUCCESS) {
60:
61: /* Set up our ticket file. */
62: if (!krb4_init(pw->pw_uid)) {
63: log("Couldn't initialize Kerberos ticket file for %s!",
64: pw->pw_name);
65: goto kerberos_auth_failure;
66: }
67: /* Try to get TGT using our password. */
68: r = krb_get_pw_in_tkt((char *) pw->pw_name, "",
69: realm, "krbtgt", realm,
70: DEFAULT_TKT_LIFE, (char *) password);
71: if (r != INTK_OK) {
72: packet_send_debug("Kerberos V4 password "
73: "authentication for %s failed: %s",
74: pw->pw_name, krb_err_txt[r]);
75: goto kerberos_auth_failure;
76: }
77: /* Successful authentication. */
78: chown(tkt_string(), pw->pw_uid, pw->pw_gid);
79:
80: /*
81: * Now that we have a TGT, try to get a local
82: * "rcmd" ticket to ensure that we are not talking
83: * to a bogus Kerberos server.
84: */
85: (void) gethostname(localhost, sizeof(localhost));
86: (void) strlcpy(phost, (char *) krb_get_phost(localhost),
87: INST_SZ);
88: r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33);
89:
90: if (r == KSUCCESS) {
91: if (!(hp = gethostbyname(localhost))) {
92: log("Couldn't get local host address!");
93: goto kerberos_auth_failure;
94: }
95: memmove((void *) &faddr, (void *) hp->h_addr,
96: sizeof(faddr));
97:
98: /* Verify our "rcmd" ticket. */
99: r = krb_rd_req(&tkt, KRB4_SERVICE_NAME, phost,
100: faddr, &adata, "");
101: if (r == RD_AP_UNDEC) {
102: /*
103: * Probably didn't have a srvtab on
1.16 provos 104: * localhost. Disallow login.
1.11 markus 105: */
106: log("Kerberos V4 TGT for %s unverifiable, "
107: "no srvtab installed? krb_rd_req: %s",
108: pw->pw_name, krb_err_txt[r]);
1.16 provos 109: goto kerberos_auth_failure;
1.11 markus 110: } else if (r != KSUCCESS) {
111: log("Kerberos V4 %s ticket unverifiable: %s",
112: KRB4_SERVICE_NAME, krb_err_txt[r]);
113: goto kerberos_auth_failure;
114: }
115: } else if (r == KDC_PR_UNKNOWN) {
116: /*
1.16 provos 117: * Disallow login if no rcmd service exists, and
1.11 markus 118: * log the error.
119: */
120: log("Kerberos V4 TGT for %s unverifiable: %s; %s.%s "
121: "not registered, or srvtab is wrong?", pw->pw_name,
122: krb_err_txt[r], KRB4_SERVICE_NAME, phost);
1.16 provos 123: goto kerberos_auth_failure;
1.11 markus 124: } else {
125: /*
126: * TGT is bad, forget it. Possibly spoofed!
127: */
128: packet_send_debug("WARNING: Kerberos V4 TGT "
129: "possibly spoofed for %s: %s",
130: pw->pw_name, krb_err_txt[r]);
131: goto kerberos_auth_failure;
132: }
133:
134: /* Authentication succeeded. */
135: return 1;
136:
137: kerberos_auth_failure:
138: krb4_cleanup_proc(NULL);
139:
140: if (!options.kerberos_or_local_passwd)
141: return 0;
142: } else {
143: /* Logging in as root or no local Kerberos realm. */
144: packet_send_debug("Unable to authenticate to Kerberos.");
145: }
146: /* Fall back to ordinary passwd authentication. */
147: return -1;
148: }
1.6 markus 149:
150: void
151: krb4_cleanup_proc(void *ignore)
1.1 deraadt 152: {
1.9 markus 153: debug("krb4_cleanup_proc called");
154: if (ticket) {
155: (void) dest_tkt();
156: xfree(ticket);
157: ticket = NULL;
158: }
1.6 markus 159: }
160:
1.14 markus 161: int
1.9 markus 162: krb4_init(uid_t uid)
1.6 markus 163: {
1.9 markus 164: static int cleanup_registered = 0;
1.13 markus 165: const char *tkt_root = TKT_ROOT;
1.9 markus 166: struct stat st;
167: int fd;
168:
169: if (!ticket) {
170: /* Set unique ticket string manually since we're still root. */
171: ticket = xmalloc(MAXPATHLEN);
1.1 deraadt 172: #ifdef AFS
1.9 markus 173: if (lstat("/ticket", &st) != -1)
174: tkt_root = "/ticket/";
1.1 deraadt 175: #endif /* AFS */
1.17 deraadt 176: snprintf(ticket, MAXPATHLEN, "%s%u_%d", tkt_root, uid, getpid());
1.9 markus 177: (void) krb_set_tkt_string(ticket);
178: }
179: /* Register ticket cleanup in case of fatal error. */
180: if (!cleanup_registered) {
181: fatal_add_cleanup(krb4_cleanup_proc, NULL);
182: cleanup_registered = 1;
183: }
184: /* Try to create our ticket file. */
185: if ((fd = mkstemp(ticket)) != -1) {
186: close(fd);
187: return 1;
188: }
189: /* Ticket file exists - make sure user owns it (just passed ticket). */
190: if (lstat(ticket, &st) != -1) {
191: if (st.st_mode == (S_IFREG | S_IRUSR | S_IWUSR) &&
192: st.st_uid == uid)
193: return 1;
194: }
195: /* Failure - cancel cleanup function, leaving bad ticket for inspection. */
196: log("WARNING: bad ticket file %s", ticket);
197: fatal_remove_cleanup(krb4_cleanup_proc, NULL);
198: cleanup_registered = 0;
199: xfree(ticket);
200: ticket = NULL;
201:
202: return 0;
1.1 deraadt 203: }
204:
1.14 markus 205: int
1.9 markus 206: auth_krb4(const char *server_user, KTEXT auth, char **client)
1.1 deraadt 207: {
1.9 markus 208: AUTH_DAT adat = {0};
209: KTEXT_ST reply;
210: char instance[INST_SZ];
211: int r, s;
1.12 markus 212: socklen_t slen;
1.9 markus 213: u_int cksum;
214: Key_schedule schedule;
215: struct sockaddr_in local, foreign;
216:
217: s = packet_get_connection_in();
218:
1.12 markus 219: slen = sizeof(local);
1.9 markus 220: memset(&local, 0, sizeof(local));
1.12 markus 221: if (getsockname(s, (struct sockaddr *) & local, &slen) < 0)
1.9 markus 222: debug("getsockname failed: %.100s", strerror(errno));
1.12 markus 223: slen = sizeof(foreign);
1.9 markus 224: memset(&foreign, 0, sizeof(foreign));
1.12 markus 225: if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) {
1.9 markus 226: debug("getpeername failed: %.100s", strerror(errno));
227: fatal_cleanup();
228: }
229: instance[0] = '*';
230: instance[1] = 0;
231:
232: /* Get the encrypted request, challenge, and session key. */
233: if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, 0, &adat, ""))) {
234: packet_send_debug("Kerberos V4 krb_rd_req: %.100s", krb_err_txt[r]);
235: return 0;
236: }
237: des_key_sched((des_cblock *) adat.session, schedule);
238:
239: *client = xmalloc(MAX_K_NAME_SZ);
240: (void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname,
1.10 deraadt 241: *adat.pinst ? "." : "", adat.pinst, adat.prealm);
1.9 markus 242:
243: /* Check ~/.klogin authorization now. */
244: if (kuserok(&adat, (char *) server_user) != KSUCCESS) {
245: packet_send_debug("Kerberos V4 .klogin authorization failed!");
246: log("Kerberos V4 .klogin authorization failed for %s to account %s",
247: *client, server_user);
248: xfree(*client);
249: return 0;
250: }
251: /* Increment the checksum, and return it encrypted with the
252: session key. */
253: cksum = adat.checksum + 1;
254: cksum = htonl(cksum);
255:
256: /* If we can't successfully encrypt the checksum, we send back an
257: empty message, admitting our failure. */
258: if ((r = krb_mk_priv((u_char *) & cksum, reply.dat, sizeof(cksum) + 1,
1.10 deraadt 259: schedule, &adat.session, &local, &foreign)) < 0) {
1.9 markus 260: packet_send_debug("Kerberos V4 mk_priv: (%d) %s", r, krb_err_txt[r]);
261: reply.dat[0] = 0;
262: reply.length = 0;
263: } else
264: reply.length = r;
265:
266: /* Clear session key. */
267: memset(&adat.session, 0, sizeof(&adat.session));
268:
269: packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
270: packet_put_string((char *) reply.dat, reply.length);
271: packet_send();
272: packet_write_wait();
273: return 1;
1.1 deraadt 274: }
275: #endif /* KRB4 */
276:
277: #ifdef AFS
1.14 markus 278: int
1.9 markus 279: auth_kerberos_tgt(struct passwd *pw, const char *string)
1.1 deraadt 280: {
1.9 markus 281: CREDENTIALS creds;
282:
283: if (!radix_to_creds(string, &creds)) {
284: log("Protocol error decoding Kerberos V4 tgt");
285: packet_send_debug("Protocol error decoding Kerberos V4 tgt");
286: goto auth_kerberos_tgt_failure;
287: }
288: if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
289: strlcpy(creds.service, "krbtgt", sizeof creds.service);
290:
291: if (strcmp(creds.service, "krbtgt")) {
292: log("Kerberos V4 tgt (%s%s%s@%s) rejected for %s", creds.pname,
1.10 deraadt 293: creds.pinst[0] ? "." : "", creds.pinst, creds.realm,
294: pw->pw_name);
1.9 markus 295: packet_send_debug("Kerberos V4 tgt (%s%s%s@%s) rejected for %s",
1.10 deraadt 296: creds.pname, creds.pinst[0] ? "." : "", creds.pinst,
297: creds.realm, pw->pw_name);
1.9 markus 298: goto auth_kerberos_tgt_failure;
299: }
300: if (!krb4_init(pw->pw_uid))
301: goto auth_kerberos_tgt_failure;
302:
303: if (in_tkt(creds.pname, creds.pinst) != KSUCCESS)
304: goto auth_kerberos_tgt_failure;
305:
306: if (save_credentials(creds.service, creds.instance, creds.realm,
1.10 deraadt 307: creds.session, creds.lifetime, creds.kvno,
308: &creds.ticket_st, creds.issue_date) != KSUCCESS) {
1.9 markus 309: packet_send_debug("Kerberos V4 tgt refused: couldn't save credentials");
310: goto auth_kerberos_tgt_failure;
311: }
312: /* Successful authentication, passed all checks. */
313: chown(tkt_string(), pw->pw_uid, pw->pw_gid);
314:
315: packet_send_debug("Kerberos V4 tgt accepted (%s.%s@%s, %s%s%s@%s)",
1.10 deraadt 316: creds.service, creds.instance, creds.realm, creds.pname,
317: creds.pinst[0] ? "." : "", creds.pinst, creds.realm);
1.9 markus 318: memset(&creds, 0, sizeof(creds));
319: packet_start(SSH_SMSG_SUCCESS);
320: packet_send();
321: packet_write_wait();
322: return 1;
323:
324: auth_kerberos_tgt_failure:
325: krb4_cleanup_proc(NULL);
326: memset(&creds, 0, sizeof(creds));
327: packet_start(SSH_SMSG_FAILURE);
328: packet_send();
329: packet_write_wait();
330: return 0;
1.1 deraadt 331: }
332:
1.14 markus 333: int
1.9 markus 334: auth_afs_token(struct passwd *pw, const char *token_string)
1.1 deraadt 335: {
1.9 markus 336: CREDENTIALS creds;
337: uid_t uid = pw->pw_uid;
1.1 deraadt 338:
1.9 markus 339: if (!radix_to_creds(token_string, &creds)) {
340: log("Protocol error decoding AFS token");
341: packet_send_debug("Protocol error decoding AFS token");
342: packet_start(SSH_SMSG_FAILURE);
343: packet_send();
344: packet_write_wait();
345: return 0;
346: }
347: if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
348: strlcpy(creds.service, "afs", sizeof creds.service);
349:
350: if (strncmp(creds.pname, "AFS ID ", 7) == 0)
351: uid = atoi(creds.pname + 7);
352:
353: if (kafs_settoken(creds.realm, uid, &creds)) {
354: log("AFS token (%s@%s) rejected for %s", creds.pname, creds.realm,
355: pw->pw_name);
356: packet_send_debug("AFS token (%s@%s) rejected for %s", creds.pname,
1.10 deraadt 357: creds.realm, pw->pw_name);
1.9 markus 358: memset(&creds, 0, sizeof(creds));
359: packet_start(SSH_SMSG_FAILURE);
360: packet_send();
361: packet_write_wait();
362: return 0;
363: }
364: packet_send_debug("AFS token accepted (%s@%s, %s@%s)", creds.service,
1.10 deraadt 365: creds.realm, creds.pname, creds.realm);
1.9 markus 366: memset(&creds, 0, sizeof(creds));
367: packet_start(SSH_SMSG_SUCCESS);
368: packet_send();
369: packet_write_wait();
370: return 1;
1.1 deraadt 371: }
372: #endif /* AFS */
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