Annotation of src/usr.bin/ssh/auth-krb4.c, Revision 1.19.2.3
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"
1.19.2.1 jason 26: RCSID("$OpenBSD: auth-krb4.c,v 1.23 2001/01/22 08:15:00 markus Exp $");
27:
28: #include "ssh.h"
29: #include "ssh1.h"
1.1 deraadt 30: #include "packet.h"
31: #include "xmalloc.h"
1.19.2.1 jason 32: #include "log.h"
1.11 markus 33: #include "servconf.h"
1.19.2.1 jason 34: #include "auth.h"
1.1 deraadt 35:
1.19.2.1 jason 36: #ifdef AFS
37: #include "radix.h"
38: #endif
1.15 djm 39:
1.1 deraadt 40: #ifdef KRB4
1.6 markus 41: char *ticket = NULL;
1.11 markus 42:
43: extern ServerOptions options;
44:
45: /*
46: * try krb4 authentication,
47: * return 1 on success, 0 on failure, -1 if krb4 is not available
48: */
49:
1.14 markus 50: int
1.11 markus 51: auth_krb4_password(struct passwd * pw, const char *password)
52: {
53: AUTH_DAT adata;
54: KTEXT_ST tkt;
55: struct hostent *hp;
1.19.2.1 jason 56: u_long faddr;
1.11 markus 57: char localhost[MAXHOSTNAMELEN];
58: char phost[INST_SZ];
59: char realm[REALM_SZ];
60: int r;
61:
62: /*
63: * Try Kerberos password authentication only for non-root
64: * users and only if Kerberos is installed.
65: */
66: if (pw->pw_uid != 0 && krb_get_lrealm(realm, 1) == KSUCCESS) {
67:
68: /* Set up our ticket file. */
69: if (!krb4_init(pw->pw_uid)) {
70: log("Couldn't initialize Kerberos ticket file for %s!",
71: pw->pw_name);
72: goto kerberos_auth_failure;
73: }
74: /* Try to get TGT using our password. */
75: r = krb_get_pw_in_tkt((char *) pw->pw_name, "",
76: realm, "krbtgt", realm,
77: DEFAULT_TKT_LIFE, (char *) password);
78: if (r != INTK_OK) {
79: packet_send_debug("Kerberos V4 password "
80: "authentication for %s failed: %s",
81: pw->pw_name, krb_err_txt[r]);
82: goto kerberos_auth_failure;
83: }
84: /* Successful authentication. */
85: chown(tkt_string(), pw->pw_uid, pw->pw_gid);
86:
87: /*
88: * Now that we have a TGT, try to get a local
89: * "rcmd" ticket to ensure that we are not talking
90: * to a bogus Kerberos server.
91: */
92: (void) gethostname(localhost, sizeof(localhost));
93: (void) strlcpy(phost, (char *) krb_get_phost(localhost),
94: INST_SZ);
95: r = krb_mk_req(&tkt, KRB4_SERVICE_NAME, phost, realm, 33);
96:
97: if (r == KSUCCESS) {
98: if (!(hp = gethostbyname(localhost))) {
99: log("Couldn't get local host address!");
100: goto kerberos_auth_failure;
101: }
102: memmove((void *) &faddr, (void *) hp->h_addr,
103: sizeof(faddr));
104:
105: /* Verify our "rcmd" ticket. */
106: r = krb_rd_req(&tkt, KRB4_SERVICE_NAME, phost,
107: faddr, &adata, "");
108: if (r == RD_AP_UNDEC) {
109: /*
110: * Probably didn't have a srvtab on
1.16 provos 111: * localhost. Disallow login.
1.11 markus 112: */
113: log("Kerberos V4 TGT for %s unverifiable, "
114: "no srvtab installed? krb_rd_req: %s",
115: pw->pw_name, krb_err_txt[r]);
1.16 provos 116: goto kerberos_auth_failure;
1.11 markus 117: } else if (r != KSUCCESS) {
118: log("Kerberos V4 %s ticket unverifiable: %s",
119: KRB4_SERVICE_NAME, krb_err_txt[r]);
120: goto kerberos_auth_failure;
121: }
122: } else if (r == KDC_PR_UNKNOWN) {
123: /*
1.16 provos 124: * Disallow login if no rcmd service exists, and
1.11 markus 125: * log the error.
126: */
127: log("Kerberos V4 TGT for %s unverifiable: %s; %s.%s "
128: "not registered, or srvtab is wrong?", pw->pw_name,
129: krb_err_txt[r], KRB4_SERVICE_NAME, phost);
1.16 provos 130: goto kerberos_auth_failure;
1.11 markus 131: } else {
132: /*
133: * TGT is bad, forget it. Possibly spoofed!
134: */
135: packet_send_debug("WARNING: Kerberos V4 TGT "
136: "possibly spoofed for %s: %s",
137: pw->pw_name, krb_err_txt[r]);
138: goto kerberos_auth_failure;
139: }
140:
141: /* Authentication succeeded. */
142: return 1;
143:
144: kerberos_auth_failure:
145: krb4_cleanup_proc(NULL);
146:
147: if (!options.kerberos_or_local_passwd)
148: return 0;
149: } else {
150: /* Logging in as root or no local Kerberos realm. */
151: packet_send_debug("Unable to authenticate to Kerberos.");
152: }
153: /* Fall back to ordinary passwd authentication. */
154: return -1;
155: }
1.6 markus 156:
157: void
158: krb4_cleanup_proc(void *ignore)
1.1 deraadt 159: {
1.9 markus 160: debug("krb4_cleanup_proc called");
161: if (ticket) {
162: (void) dest_tkt();
163: xfree(ticket);
164: ticket = NULL;
165: }
1.6 markus 166: }
167:
1.14 markus 168: int
1.9 markus 169: krb4_init(uid_t uid)
1.6 markus 170: {
1.9 markus 171: static int cleanup_registered = 0;
1.13 markus 172: const char *tkt_root = TKT_ROOT;
1.9 markus 173: struct stat st;
174: int fd;
175:
176: if (!ticket) {
177: /* Set unique ticket string manually since we're still root. */
178: ticket = xmalloc(MAXPATHLEN);
1.1 deraadt 179: #ifdef AFS
1.9 markus 180: if (lstat("/ticket", &st) != -1)
181: tkt_root = "/ticket/";
1.1 deraadt 182: #endif /* AFS */
1.17 deraadt 183: snprintf(ticket, MAXPATHLEN, "%s%u_%d", tkt_root, uid, getpid());
1.9 markus 184: (void) krb_set_tkt_string(ticket);
185: }
186: /* Register ticket cleanup in case of fatal error. */
187: if (!cleanup_registered) {
188: fatal_add_cleanup(krb4_cleanup_proc, NULL);
189: cleanup_registered = 1;
190: }
191: /* Try to create our ticket file. */
192: if ((fd = mkstemp(ticket)) != -1) {
193: close(fd);
194: return 1;
195: }
196: /* Ticket file exists - make sure user owns it (just passed ticket). */
197: if (lstat(ticket, &st) != -1) {
198: if (st.st_mode == (S_IFREG | S_IRUSR | S_IWUSR) &&
199: st.st_uid == uid)
200: return 1;
201: }
202: /* Failure - cancel cleanup function, leaving bad ticket for inspection. */
203: log("WARNING: bad ticket file %s", ticket);
204: fatal_remove_cleanup(krb4_cleanup_proc, NULL);
205: cleanup_registered = 0;
206: xfree(ticket);
207: ticket = NULL;
208:
209: return 0;
1.1 deraadt 210: }
211:
1.14 markus 212: int
1.9 markus 213: auth_krb4(const char *server_user, KTEXT auth, char **client)
1.1 deraadt 214: {
1.9 markus 215: AUTH_DAT adat = {0};
216: KTEXT_ST reply;
217: char instance[INST_SZ];
218: int r, s;
1.12 markus 219: socklen_t slen;
1.9 markus 220: u_int cksum;
221: Key_schedule schedule;
222: struct sockaddr_in local, foreign;
223:
224: s = packet_get_connection_in();
225:
1.12 markus 226: slen = sizeof(local);
1.9 markus 227: memset(&local, 0, sizeof(local));
1.12 markus 228: if (getsockname(s, (struct sockaddr *) & local, &slen) < 0)
1.9 markus 229: debug("getsockname failed: %.100s", strerror(errno));
1.12 markus 230: slen = sizeof(foreign);
1.9 markus 231: memset(&foreign, 0, sizeof(foreign));
1.12 markus 232: if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) {
1.9 markus 233: debug("getpeername failed: %.100s", strerror(errno));
234: fatal_cleanup();
235: }
236: instance[0] = '*';
237: instance[1] = 0;
238:
239: /* Get the encrypted request, challenge, and session key. */
240: if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, 0, &adat, ""))) {
241: packet_send_debug("Kerberos V4 krb_rd_req: %.100s", krb_err_txt[r]);
242: return 0;
243: }
244: des_key_sched((des_cblock *) adat.session, schedule);
245:
246: *client = xmalloc(MAX_K_NAME_SZ);
247: (void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname,
1.10 deraadt 248: *adat.pinst ? "." : "", adat.pinst, adat.prealm);
1.9 markus 249:
250: /* Check ~/.klogin authorization now. */
251: if (kuserok(&adat, (char *) server_user) != KSUCCESS) {
252: packet_send_debug("Kerberos V4 .klogin authorization failed!");
253: log("Kerberos V4 .klogin authorization failed for %s to account %s",
254: *client, server_user);
255: xfree(*client);
256: return 0;
257: }
258: /* Increment the checksum, and return it encrypted with the
259: session key. */
260: cksum = adat.checksum + 1;
261: cksum = htonl(cksum);
262:
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,
1.10 deraadt 266: schedule, &adat.session, &local, &foreign)) < 0) {
1.9 markus 267: packet_send_debug("Kerberos V4 mk_priv: (%d) %s", r, krb_err_txt[r]);
268: reply.dat[0] = 0;
269: reply.length = 0;
270: } else
271: reply.length = r;
272:
273: /* Clear session key. */
274: memset(&adat.session, 0, sizeof(&adat.session));
275:
276: packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
277: packet_put_string((char *) reply.dat, reply.length);
278: packet_send();
279: packet_write_wait();
280: return 1;
1.1 deraadt 281: }
282: #endif /* KRB4 */
283:
284: #ifdef AFS
1.14 markus 285: int
1.9 markus 286: auth_kerberos_tgt(struct passwd *pw, const char *string)
1.1 deraadt 287: {
1.9 markus 288: CREDENTIALS creds;
289:
1.19 markus 290: if (pw == NULL)
291: goto auth_kerberos_tgt_failure;
1.9 markus 292: if (!radix_to_creds(string, &creds)) {
293: log("Protocol error decoding Kerberos V4 tgt");
294: packet_send_debug("Protocol error decoding Kerberos V4 tgt");
295: goto auth_kerberos_tgt_failure;
296: }
297: if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
298: strlcpy(creds.service, "krbtgt", sizeof creds.service);
299:
300: if (strcmp(creds.service, "krbtgt")) {
301: log("Kerberos V4 tgt (%s%s%s@%s) rejected for %s", creds.pname,
1.10 deraadt 302: creds.pinst[0] ? "." : "", creds.pinst, creds.realm,
303: pw->pw_name);
1.9 markus 304: packet_send_debug("Kerberos V4 tgt (%s%s%s@%s) rejected for %s",
1.10 deraadt 305: creds.pname, creds.pinst[0] ? "." : "", creds.pinst,
306: creds.realm, pw->pw_name);
1.9 markus 307: goto auth_kerberos_tgt_failure;
308: }
309: if (!krb4_init(pw->pw_uid))
310: goto auth_kerberos_tgt_failure;
311:
312: if (in_tkt(creds.pname, creds.pinst) != KSUCCESS)
313: goto auth_kerberos_tgt_failure;
314:
315: if (save_credentials(creds.service, creds.instance, creds.realm,
1.10 deraadt 316: creds.session, creds.lifetime, creds.kvno,
317: &creds.ticket_st, creds.issue_date) != KSUCCESS) {
1.9 markus 318: packet_send_debug("Kerberos V4 tgt refused: couldn't save credentials");
319: goto auth_kerberos_tgt_failure;
320: }
321: /* Successful authentication, passed all checks. */
322: chown(tkt_string(), pw->pw_uid, pw->pw_gid);
323:
324: packet_send_debug("Kerberos V4 tgt accepted (%s.%s@%s, %s%s%s@%s)",
1.10 deraadt 325: creds.service, creds.instance, creds.realm, creds.pname,
326: creds.pinst[0] ? "." : "", creds.pinst, creds.realm);
1.9 markus 327: memset(&creds, 0, sizeof(creds));
328: packet_start(SSH_SMSG_SUCCESS);
329: packet_send();
330: packet_write_wait();
331: return 1;
332:
333: auth_kerberos_tgt_failure:
334: krb4_cleanup_proc(NULL);
335: memset(&creds, 0, sizeof(creds));
336: packet_start(SSH_SMSG_FAILURE);
337: packet_send();
338: packet_write_wait();
339: return 0;
1.1 deraadt 340: }
341:
1.14 markus 342: int
1.9 markus 343: auth_afs_token(struct passwd *pw, const char *token_string)
1.1 deraadt 344: {
1.9 markus 345: CREDENTIALS creds;
1.19 markus 346: uid_t uid;
1.1 deraadt 347:
1.19 markus 348: if (pw == NULL) {
349: /* XXX fake protocol error */
350: packet_send_debug("Protocol error decoding AFS token");
351: packet_start(SSH_SMSG_FAILURE);
352: packet_send();
353: packet_write_wait();
354: return 0;
355: }
1.9 markus 356: if (!radix_to_creds(token_string, &creds)) {
357: log("Protocol error decoding AFS token");
358: packet_send_debug("Protocol error decoding AFS token");
359: packet_start(SSH_SMSG_FAILURE);
360: packet_send();
361: packet_write_wait();
362: return 0;
363: }
364: if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
365: strlcpy(creds.service, "afs", sizeof creds.service);
366:
367: if (strncmp(creds.pname, "AFS ID ", 7) == 0)
368: uid = atoi(creds.pname + 7);
1.19 markus 369: else
370: uid = pw->pw_uid;
1.9 markus 371:
372: if (kafs_settoken(creds.realm, uid, &creds)) {
373: log("AFS token (%s@%s) rejected for %s", creds.pname, creds.realm,
374: pw->pw_name);
375: packet_send_debug("AFS token (%s@%s) rejected for %s", creds.pname,
1.10 deraadt 376: creds.realm, pw->pw_name);
1.9 markus 377: memset(&creds, 0, sizeof(creds));
378: packet_start(SSH_SMSG_FAILURE);
379: packet_send();
380: packet_write_wait();
381: return 0;
382: }
383: packet_send_debug("AFS token accepted (%s@%s, %s@%s)", creds.service,
1.10 deraadt 384: creds.realm, creds.pname, creds.realm);
1.9 markus 385: memset(&creds, 0, sizeof(creds));
386: packet_start(SSH_SMSG_SUCCESS);
387: packet_send();
388: packet_write_wait();
389: return 1;
1.1 deraadt 390: }
391: #endif /* AFS */
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