Annotation of src/usr.bin/ssh/auth-krb4.c, Revision 1.12
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:
12: #ifdef KRB4
1.6 markus 13: char *ticket = NULL;
1.11 markus 14:
15: extern ServerOptions options;
16:
17: /*
18: * try krb4 authentication,
19: * return 1 on success, 0 on failure, -1 if krb4 is not available
20: */
21:
22: int
23: auth_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:
114: kerberos_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: }
1.6 markus 126:
127: void
128: krb4_cleanup_proc(void *ignore)
1.1 deraadt 129: {
1.9 markus 130: debug("krb4_cleanup_proc called");
131: if (ticket) {
132: (void) dest_tkt();
133: xfree(ticket);
134: ticket = NULL;
135: }
1.6 markus 136: }
137:
1.9 markus 138: int
139: krb4_init(uid_t uid)
1.6 markus 140: {
1.9 markus 141: static int cleanup_registered = 0;
142: char *tkt_root = TKT_ROOT;
143: struct stat st;
144: int fd;
145:
146: if (!ticket) {
147: /* Set unique ticket string manually since we're still root. */
148: ticket = xmalloc(MAXPATHLEN);
1.1 deraadt 149: #ifdef AFS
1.9 markus 150: if (lstat("/ticket", &st) != -1)
151: tkt_root = "/ticket/";
1.1 deraadt 152: #endif /* AFS */
1.9 markus 153: 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;
1.1 deraadt 180: }
181:
1.9 markus 182: int
183: auth_krb4(const char *server_user, KTEXT auth, char **client)
1.1 deraadt 184: {
1.9 markus 185: AUTH_DAT adat = {0};
186: KTEXT_ST reply;
187: char instance[INST_SZ];
188: int r, s;
1.12 ! markus 189: socklen_t slen;
1.9 markus 190: u_int cksum;
191: Key_schedule schedule;
192: struct sockaddr_in local, foreign;
193:
194: s = packet_get_connection_in();
195:
1.12 ! markus 196: slen = sizeof(local);
1.9 markus 197: memset(&local, 0, sizeof(local));
1.12 ! markus 198: if (getsockname(s, (struct sockaddr *) & local, &slen) < 0)
1.9 markus 199: debug("getsockname failed: %.100s", strerror(errno));
1.12 ! markus 200: slen = sizeof(foreign);
1.9 markus 201: memset(&foreign, 0, sizeof(foreign));
1.12 ! markus 202: if (getpeername(s, (struct sockaddr *) & foreign, &slen) < 0) {
1.9 markus 203: debug("getpeername failed: %.100s", strerror(errno));
204: fatal_cleanup();
205: }
206: instance[0] = '*';
207: instance[1] = 0;
208:
209: /* Get the encrypted request, challenge, and session key. */
210: if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, 0, &adat, ""))) {
211: packet_send_debug("Kerberos V4 krb_rd_req: %.100s", krb_err_txt[r]);
212: return 0;
213: }
214: des_key_sched((des_cblock *) adat.session, schedule);
215:
216: *client = xmalloc(MAX_K_NAME_SZ);
217: (void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname,
1.10 deraadt 218: *adat.pinst ? "." : "", adat.pinst, adat.prealm);
1.9 markus 219:
220: /* Check ~/.klogin authorization now. */
221: if (kuserok(&adat, (char *) server_user) != KSUCCESS) {
222: packet_send_debug("Kerberos V4 .klogin authorization failed!");
223: log("Kerberos V4 .klogin authorization failed for %s to account %s",
224: *client, server_user);
225: xfree(*client);
226: return 0;
227: }
228: /* Increment the checksum, and return it encrypted with the
229: session key. */
230: cksum = adat.checksum + 1;
231: cksum = htonl(cksum);
232:
233: /* If we can't successfully encrypt the checksum, we send back an
234: empty message, admitting our failure. */
235: if ((r = krb_mk_priv((u_char *) & cksum, reply.dat, sizeof(cksum) + 1,
1.10 deraadt 236: schedule, &adat.session, &local, &foreign)) < 0) {
1.9 markus 237: packet_send_debug("Kerberos V4 mk_priv: (%d) %s", r, krb_err_txt[r]);
238: reply.dat[0] = 0;
239: reply.length = 0;
240: } else
241: reply.length = r;
242:
243: /* Clear session key. */
244: memset(&adat.session, 0, sizeof(&adat.session));
245:
246: packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
247: packet_put_string((char *) reply.dat, reply.length);
248: packet_send();
249: packet_write_wait();
250: return 1;
1.1 deraadt 251: }
252: #endif /* KRB4 */
253:
254: #ifdef AFS
1.9 markus 255: int
256: auth_kerberos_tgt(struct passwd *pw, const char *string)
1.1 deraadt 257: {
1.9 markus 258: CREDENTIALS creds;
259:
260: if (!radix_to_creds(string, &creds)) {
261: log("Protocol error decoding Kerberos V4 tgt");
262: packet_send_debug("Protocol error decoding Kerberos V4 tgt");
263: goto auth_kerberos_tgt_failure;
264: }
265: if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
266: strlcpy(creds.service, "krbtgt", sizeof creds.service);
267:
268: if (strcmp(creds.service, "krbtgt")) {
269: log("Kerberos V4 tgt (%s%s%s@%s) rejected for %s", creds.pname,
1.10 deraadt 270: creds.pinst[0] ? "." : "", creds.pinst, creds.realm,
271: pw->pw_name);
1.9 markus 272: packet_send_debug("Kerberos V4 tgt (%s%s%s@%s) rejected for %s",
1.10 deraadt 273: creds.pname, creds.pinst[0] ? "." : "", creds.pinst,
274: creds.realm, pw->pw_name);
1.9 markus 275: goto auth_kerberos_tgt_failure;
276: }
277: if (!krb4_init(pw->pw_uid))
278: goto auth_kerberos_tgt_failure;
279:
280: if (in_tkt(creds.pname, creds.pinst) != KSUCCESS)
281: goto auth_kerberos_tgt_failure;
282:
283: if (save_credentials(creds.service, creds.instance, creds.realm,
1.10 deraadt 284: creds.session, creds.lifetime, creds.kvno,
285: &creds.ticket_st, creds.issue_date) != KSUCCESS) {
1.9 markus 286: packet_send_debug("Kerberos V4 tgt refused: couldn't save credentials");
287: goto auth_kerberos_tgt_failure;
288: }
289: /* Successful authentication, passed all checks. */
290: chown(tkt_string(), pw->pw_uid, pw->pw_gid);
291:
292: packet_send_debug("Kerberos V4 tgt accepted (%s.%s@%s, %s%s%s@%s)",
1.10 deraadt 293: creds.service, creds.instance, creds.realm, creds.pname,
294: creds.pinst[0] ? "." : "", creds.pinst, creds.realm);
1.9 markus 295: memset(&creds, 0, sizeof(creds));
296: packet_start(SSH_SMSG_SUCCESS);
297: packet_send();
298: packet_write_wait();
299: return 1;
300:
301: auth_kerberos_tgt_failure:
302: krb4_cleanup_proc(NULL);
303: memset(&creds, 0, sizeof(creds));
304: packet_start(SSH_SMSG_FAILURE);
305: packet_send();
306: packet_write_wait();
307: return 0;
1.1 deraadt 308: }
309:
1.9 markus 310: int
311: auth_afs_token(struct passwd *pw, const char *token_string)
1.1 deraadt 312: {
1.9 markus 313: CREDENTIALS creds;
314: uid_t uid = pw->pw_uid;
1.1 deraadt 315:
1.9 markus 316: if (!radix_to_creds(token_string, &creds)) {
317: log("Protocol error decoding AFS token");
318: packet_send_debug("Protocol error decoding AFS token");
319: packet_start(SSH_SMSG_FAILURE);
320: packet_send();
321: packet_write_wait();
322: return 0;
323: }
324: if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
325: strlcpy(creds.service, "afs", sizeof creds.service);
326:
327: if (strncmp(creds.pname, "AFS ID ", 7) == 0)
328: uid = atoi(creds.pname + 7);
329:
330: if (kafs_settoken(creds.realm, uid, &creds)) {
331: log("AFS token (%s@%s) rejected for %s", creds.pname, creds.realm,
332: pw->pw_name);
333: packet_send_debug("AFS token (%s@%s) rejected for %s", creds.pname,
1.10 deraadt 334: creds.realm, pw->pw_name);
1.9 markus 335: memset(&creds, 0, sizeof(creds));
336: packet_start(SSH_SMSG_FAILURE);
337: packet_send();
338: packet_write_wait();
339: return 0;
340: }
341: packet_send_debug("AFS token accepted (%s@%s, %s@%s)", creds.service,
1.10 deraadt 342: creds.realm, creds.pname, creds.realm);
1.9 markus 343: memset(&creds, 0, sizeof(creds));
344: packet_start(SSH_SMSG_SUCCESS);
345: packet_send();
346: packet_write_wait();
347: return 1;
1.1 deraadt 348: }
349: #endif /* AFS */
![[BACK]](/icons/back.gif){kind=icon}
Return to auth-krb4.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh