Annotation of src/usr.bin/ssh/auth-krb4.c, Revision 1.14.2.1
1.1 deraadt 1: /*
1.10 deraadt 2: * Dug Song <dugsong@UMICH.EDU>
3: * Kerberos v4 authentication and ticket-passing routines.
4: */
1.1 deraadt 5:
6: #include "includes.h"
7: #include "packet.h"
8: #include "xmalloc.h"
9: #include "ssh.h"
1.11 markus 10: #include "servconf.h"
1.1 deraadt 11:
1.14.2.1! jason 12: RCSID("$OpenBSD: auth-krb4.c,v 1.17 2000/08/28 03:50:54 deraadt Exp $");
! 13:
1.1 deraadt 14: #ifdef KRB4
1.6 markus 15: char *ticket = NULL;
1.11 markus 16:
17: extern ServerOptions options;
18:
19: /*
20: * try krb4 authentication,
21: * return 1 on success, 0 on failure, -1 if krb4 is not available
22: */
23:
1.14 markus 24: int
1.11 markus 25: auth_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
1.14.2.1! jason 85: * localhost. Disallow login.
1.11 markus 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]);
1.14.2.1! jason 90: goto kerberos_auth_failure;
1.11 markus 91: } else if (r != KSUCCESS) {
92: log("Kerberos V4 %s ticket unverifiable: %s",
93: KRB4_SERVICE_NAME, krb_err_txt[r]);
94: goto kerberos_auth_failure;
95: }
96: } else if (r == KDC_PR_UNKNOWN) {
97: /*
1.14.2.1! jason 98: * Disallow login if no rcmd service exists, and
1.11 markus 99: * log the error.
100: */
101: log("Kerberos V4 TGT for %s unverifiable: %s; %s.%s "
102: "not registered, or srvtab is wrong?", pw->pw_name,
103: krb_err_txt[r], KRB4_SERVICE_NAME, phost);
1.14.2.1! jason 104: goto kerberos_auth_failure;
1.11 markus 105: } else {
106: /*
107: * TGT is bad, forget it. Possibly spoofed!
108: */
109: packet_send_debug("WARNING: Kerberos V4 TGT "
110: "possibly spoofed for %s: %s",
111: pw->pw_name, krb_err_txt[r]);
112: goto kerberos_auth_failure;
113: }
114:
115: /* Authentication succeeded. */
116: return 1;
117:
118: kerberos_auth_failure:
119: krb4_cleanup_proc(NULL);
120:
121: if (!options.kerberos_or_local_passwd)
122: return 0;
123: } else {
124: /* Logging in as root or no local Kerberos realm. */
125: packet_send_debug("Unable to authenticate to Kerberos.");
126: }
127: /* Fall back to ordinary passwd authentication. */
128: return -1;
129: }
1.6 markus 130:
131: void
132: krb4_cleanup_proc(void *ignore)
1.1 deraadt 133: {
1.9 markus 134: debug("krb4_cleanup_proc called");
135: if (ticket) {
136: (void) dest_tkt();
137: xfree(ticket);
138: ticket = NULL;
139: }
1.6 markus 140: }
141:
1.14 markus 142: int
1.9 markus 143: krb4_init(uid_t uid)
1.6 markus 144: {
1.9 markus 145: static int cleanup_registered = 0;
1.13 markus 146: const char *tkt_root = TKT_ROOT;
1.9 markus 147: struct stat st;
148: int fd;
149:
150: if (!ticket) {
151: /* Set unique ticket string manually since we're still root. */
152: ticket = xmalloc(MAXPATHLEN);
1.1 deraadt 153: #ifdef AFS
1.9 markus 154: if (lstat("/ticket", &st) != -1)
155: tkt_root = "/ticket/";
1.1 deraadt 156: #endif /* AFS */
1.14.2.1! jason 157: snprintf(ticket, MAXPATHLEN, "%s%u_%d", tkt_root, uid, getpid());
1.9 markus 158: (void) krb_set_tkt_string(ticket);
159: }
160: /* Register ticket cleanup in case of fatal error. */
161: if (!cleanup_registered) {
162: fatal_add_cleanup(krb4_cleanup_proc, NULL);
163: cleanup_registered = 1;
164: }
165: /* Try to create our ticket file. */
166: if ((fd = mkstemp(ticket)) != -1) {
167: close(fd);
168: return 1;
169: }
170: /* Ticket file exists - make sure user owns it (just passed ticket). */
171: if (lstat(ticket, &st) != -1) {
172: if (st.st_mode == (S_IFREG | S_IRUSR | S_IWUSR) &&
173: st.st_uid == uid)
174: return 1;
175: }
176: /* Failure - cancel cleanup function, leaving bad ticket for inspection. */
177: log("WARNING: bad ticket file %s", ticket);
178: fatal_remove_cleanup(krb4_cleanup_proc, NULL);
179: cleanup_registered = 0;
180: xfree(ticket);
181: ticket = NULL;
182:
183: return 0;
1.1 deraadt 184: }
185:
1.14 markus 186: int
1.9 markus 187: auth_krb4(const char *server_user, KTEXT auth, char **client)
1.1 deraadt 188: {
1.9 markus 189: AUTH_DAT adat = {0};
190: KTEXT_ST reply;
191: char instance[INST_SZ];
192: int r, s;
1.12 markus 193: socklen_t slen;
1.9 markus 194: u_int cksum;
195: Key_schedule schedule;
196: struct sockaddr_in local, foreign;
197:
198: s = packet_get_connection_in();
199:
1.12 markus 200: slen = sizeof(local);
1.9 markus 201: memset(&local, 0, sizeof(local));
1.12 markus 202: if (getsockname(s, (struct sockaddr *) & local, &slen) < 0)
1.9 markus 203: debug("getsockname failed: %.100s", strerror(errno));
1.12 markus 204: slen = sizeof(foreign);
1.9 markus 205: memset(&foreign, 0, sizeof(foreign));
1.12 markus 206: if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) {
1.9 markus 207: debug("getpeername failed: %.100s", strerror(errno));
208: fatal_cleanup();
209: }
210: instance[0] = '*';
211: instance[1] = 0;
212:
213: /* Get the encrypted request, challenge, and session key. */
214: if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, 0, &adat, ""))) {
215: packet_send_debug("Kerberos V4 krb_rd_req: %.100s", krb_err_txt[r]);
216: return 0;
217: }
218: des_key_sched((des_cblock *) adat.session, schedule);
219:
220: *client = xmalloc(MAX_K_NAME_SZ);
221: (void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname,
1.10 deraadt 222: *adat.pinst ? "." : "", adat.pinst, adat.prealm);
1.9 markus 223:
224: /* Check ~/.klogin authorization now. */
225: if (kuserok(&adat, (char *) server_user) != KSUCCESS) {
226: packet_send_debug("Kerberos V4 .klogin authorization failed!");
227: log("Kerberos V4 .klogin authorization failed for %s to account %s",
228: *client, server_user);
229: xfree(*client);
230: return 0;
231: }
232: /* Increment the checksum, and return it encrypted with the
233: session key. */
234: cksum = adat.checksum + 1;
235: cksum = htonl(cksum);
236:
237: /* If we can't successfully encrypt the checksum, we send back an
238: empty message, admitting our failure. */
239: if ((r = krb_mk_priv((u_char *) & cksum, reply.dat, sizeof(cksum) + 1,
1.10 deraadt 240: schedule, &adat.session, &local, &foreign)) < 0) {
1.9 markus 241: packet_send_debug("Kerberos V4 mk_priv: (%d) %s", r, krb_err_txt[r]);
242: reply.dat[0] = 0;
243: reply.length = 0;
244: } else
245: reply.length = r;
246:
247: /* Clear session key. */
248: memset(&adat.session, 0, sizeof(&adat.session));
249:
250: packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
251: packet_put_string((char *) reply.dat, reply.length);
252: packet_send();
253: packet_write_wait();
254: return 1;
1.1 deraadt 255: }
256: #endif /* KRB4 */
257:
258: #ifdef AFS
1.14 markus 259: int
1.9 markus 260: auth_kerberos_tgt(struct passwd *pw, const char *string)
1.1 deraadt 261: {
1.9 markus 262: CREDENTIALS creds;
263:
264: if (!radix_to_creds(string, &creds)) {
265: log("Protocol error decoding Kerberos V4 tgt");
266: packet_send_debug("Protocol error decoding Kerberos V4 tgt");
267: goto auth_kerberos_tgt_failure;
268: }
269: if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
270: strlcpy(creds.service, "krbtgt", sizeof creds.service);
271:
272: if (strcmp(creds.service, "krbtgt")) {
273: log("Kerberos V4 tgt (%s%s%s@%s) rejected for %s", creds.pname,
1.10 deraadt 274: creds.pinst[0] ? "." : "", creds.pinst, creds.realm,
275: pw->pw_name);
1.9 markus 276: packet_send_debug("Kerberos V4 tgt (%s%s%s@%s) rejected for %s",
1.10 deraadt 277: creds.pname, creds.pinst[0] ? "." : "", creds.pinst,
278: creds.realm, pw->pw_name);
1.9 markus 279: goto auth_kerberos_tgt_failure;
280: }
281: if (!krb4_init(pw->pw_uid))
282: goto auth_kerberos_tgt_failure;
283:
284: if (in_tkt(creds.pname, creds.pinst) != KSUCCESS)
285: goto auth_kerberos_tgt_failure;
286:
287: if (save_credentials(creds.service, creds.instance, creds.realm,
1.10 deraadt 288: creds.session, creds.lifetime, creds.kvno,
289: &creds.ticket_st, creds.issue_date) != KSUCCESS) {
1.9 markus 290: packet_send_debug("Kerberos V4 tgt refused: couldn't save credentials");
291: goto auth_kerberos_tgt_failure;
292: }
293: /* Successful authentication, passed all checks. */
294: chown(tkt_string(), pw->pw_uid, pw->pw_gid);
295:
296: packet_send_debug("Kerberos V4 tgt accepted (%s.%s@%s, %s%s%s@%s)",
1.10 deraadt 297: creds.service, creds.instance, creds.realm, creds.pname,
298: creds.pinst[0] ? "." : "", creds.pinst, creds.realm);
1.9 markus 299: memset(&creds, 0, sizeof(creds));
300: packet_start(SSH_SMSG_SUCCESS);
301: packet_send();
302: packet_write_wait();
303: return 1;
304:
305: auth_kerberos_tgt_failure:
306: krb4_cleanup_proc(NULL);
307: memset(&creds, 0, sizeof(creds));
308: packet_start(SSH_SMSG_FAILURE);
309: packet_send();
310: packet_write_wait();
311: return 0;
1.1 deraadt 312: }
313:
1.14 markus 314: int
1.9 markus 315: auth_afs_token(struct passwd *pw, const char *token_string)
1.1 deraadt 316: {
1.9 markus 317: CREDENTIALS creds;
318: uid_t uid = pw->pw_uid;
1.1 deraadt 319:
1.9 markus 320: if (!radix_to_creds(token_string, &creds)) {
321: log("Protocol error decoding AFS token");
322: packet_send_debug("Protocol error decoding AFS token");
323: packet_start(SSH_SMSG_FAILURE);
324: packet_send();
325: packet_write_wait();
326: return 0;
327: }
328: if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
329: strlcpy(creds.service, "afs", sizeof creds.service);
330:
331: if (strncmp(creds.pname, "AFS ID ", 7) == 0)
332: uid = atoi(creds.pname + 7);
333:
334: if (kafs_settoken(creds.realm, uid, &creds)) {
335: log("AFS token (%s@%s) rejected for %s", creds.pname, creds.realm,
336: pw->pw_name);
337: packet_send_debug("AFS token (%s@%s) rejected for %s", creds.pname,
1.10 deraadt 338: creds.realm, pw->pw_name);
1.9 markus 339: memset(&creds, 0, sizeof(creds));
340: packet_start(SSH_SMSG_FAILURE);
341: packet_send();
342: packet_write_wait();
343: return 0;
344: }
345: packet_send_debug("AFS token accepted (%s@%s, %s@%s)", creds.service,
1.10 deraadt 346: creds.realm, creds.pname, creds.realm);
1.9 markus 347: memset(&creds, 0, sizeof(creds));
348: packet_start(SSH_SMSG_SUCCESS);
349: packet_send();
350: packet_write_wait();
351: return 1;
1.1 deraadt 352: }
353: #endif /* AFS */
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