1 /*-
2 * Copyright (c) 1991, 1993
3 * Dave Safford. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 */
30
31 #include <sys/cdefs.h>
32
33 __FBSDID("$FreeBSD$");
34
35 #ifdef SRA
36 #ifdef ENCRYPTION
37 #include <sys/types.h>
38 #include <arpa/telnet.h>
39 #include <pwd.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <syslog.h>
44 #include <ttyent.h>
45
46 #ifndef NOPAM
47 #include <security/pam_appl.h>
48 #else
49 #include <unistd.h>
50 #endif
51
52 #include "auth.h"
53 #include "misc.h"
54 #include "encrypt.h"
55 #include "pk.h"
56
57 char pka[HEXKEYBYTES+1], ska[HEXKEYBYTES+1], pkb[HEXKEYBYTES+1];
58 char *user, *pass, *xuser, *xpass;
59 DesData ck;
60 IdeaData ik;
61
62 extern int auth_debug_mode;
63 extern char line[];
64
65 static int sra_valid = 0;
66 static int passwd_sent = 0;
67
68 static unsigned char str_data[1024] = { IAC, SB, TELOPT_AUTHENTICATION, 0,
69 AUTHTYPE_SRA, };
70
71 #define SRA_KEY 0
72 #define SRA_USER 1
73 #define SRA_CONTINUE 2
74 #define SRA_PASS 3
75 #define SRA_ACCEPT 4
76 #define SRA_REJECT 5
77
78 static int check_user(char *, char *);
79
80 /* support routine to send out authentication message */
81 static int
Data(Authenticator * ap,int type,void * d,int c)82 Data(Authenticator *ap, int type, void *d, int c)
83 {
84 unsigned char *p = str_data + 4;
85 unsigned char *cd = (unsigned char *)d;
86
87 if (c == -1)
88 c = strlen((char *)cd);
89
90 if (auth_debug_mode) {
91 printf("%s:%d: [%d] (%d)",
92 str_data[3] == TELQUAL_IS ? ">>>IS" : ">>>REPLY",
93 str_data[3],
94 type, c);
95 printd(d, c);
96 printf("\r\n");
97 }
98 *p++ = ap->type;
99 *p++ = ap->way;
100 *p++ = type;
101 while (c-- > 0) {
102 if ((*p++ = *cd++) == IAC)
103 *p++ = IAC;
104 }
105 *p++ = IAC;
106 *p++ = SE;
107 if (str_data[3] == TELQUAL_IS)
108 printsub('>', &str_data[2], p - (&str_data[2]));
109 return(net_write(str_data, p - str_data));
110 }
111
112 int
sra_init(Authenticator * ap __unused,int server)113 sra_init(Authenticator *ap __unused, int server)
114 {
115 if (server)
116 str_data[3] = TELQUAL_REPLY;
117 else
118 str_data[3] = TELQUAL_IS;
119
120 user = (char *)malloc(256);
121 xuser = (char *)malloc(513);
122 pass = (char *)malloc(256);
123 xpass = (char *)malloc(513);
124
125 if (user == NULL || xuser == NULL || pass == NULL || xpass ==
126 NULL)
127 return 0; /* malloc failed */
128
129 passwd_sent = 0;
130
131 genkeys(pka,ska);
132 return(1);
133 }
134
135 /* client received a go-ahead for sra */
136 int
sra_send(Authenticator * ap)137 sra_send(Authenticator *ap)
138 {
139 /* send PKA */
140
141 if (auth_debug_mode)
142 printf("Sent PKA to server.\r\n" );
143 printf("Trying SRA secure login:\r\n");
144 if (!Data(ap, SRA_KEY, (void *)pka, HEXKEYBYTES)) {
145 if (auth_debug_mode)
146 printf("Not enough room for authentication data\r\n");
147 return(0);
148 }
149
150 return(1);
151 }
152
153 /* server received an IS -- could be SRA KEY, USER, or PASS */
154 void
sra_is(Authenticator * ap,unsigned char * data,int cnt)155 sra_is(Authenticator *ap, unsigned char *data, int cnt)
156 {
157 int valid;
158 Session_Key skey;
159
160 if (cnt-- < 1)
161 goto bad;
162 switch (*data++) {
163
164 case SRA_KEY:
165 if (cnt < HEXKEYBYTES) {
166 Data(ap, SRA_REJECT, (void *)0, 0);
167 auth_finished(ap, AUTH_USER);
168 if (auth_debug_mode) {
169 printf("SRA user rejected for bad PKB\r\n");
170 }
171 return;
172 }
173 if (auth_debug_mode)
174 printf("Sent pka\r\n");
175 if (!Data(ap, SRA_KEY, (void *)pka, HEXKEYBYTES)) {
176 if (auth_debug_mode)
177 printf("Not enough room\r\n");
178 return;
179 }
180 memcpy(pkb,data,HEXKEYBYTES);
181 pkb[HEXKEYBYTES] = '\0';
182 common_key(ska,pkb,&ik,&ck);
183 return;
184
185 case SRA_USER:
186 /* decode KAB(u) */
187 if (cnt > 512) /* Attempted buffer overflow */
188 break;
189 memcpy(xuser,data,cnt);
190 xuser[cnt] = '\0';
191 pk_decode(xuser,user,&ck);
192 auth_encrypt_user(user);
193 Data(ap, SRA_CONTINUE, (void *)0, 0);
194
195 return;
196
197 case SRA_PASS:
198 if (cnt > 512) /* Attempted buffer overflow */
199 break;
200 /* decode KAB(P) */
201 memcpy(xpass,data,cnt);
202 xpass[cnt] = '\0';
203 pk_decode(xpass,pass,&ck);
204
205 /* check user's password */
206 valid = check_user(user,pass);
207
208 if(valid) {
209 Data(ap, SRA_ACCEPT, (void *)0, 0);
210 skey.data = ck;
211 skey.type = SK_DES;
212 skey.length = 8;
213 encrypt_session_key(&skey, 1);
214
215 sra_valid = 1;
216 auth_finished(ap, AUTH_VALID);
217 if (auth_debug_mode) {
218 printf("SRA user accepted\r\n");
219 }
220 }
221 else {
222 Data(ap, SRA_CONTINUE, (void *)0, 0);
223 /*
224 Data(ap, SRA_REJECT, (void *)0, 0);
225 sra_valid = 0;
226 auth_finished(ap, AUTH_REJECT);
227 */
228 if (auth_debug_mode) {
229 printf("SRA user failed\r\n");
230 }
231 }
232 return;
233
234 default:
235 if (auth_debug_mode)
236 printf("Unknown SRA option %d\r\n", data[-1]);
237 }
238 bad:
239 Data(ap, SRA_REJECT, 0, 0);
240 sra_valid = 0;
241 auth_finished(ap, AUTH_REJECT);
242 }
243
244 /* client received REPLY -- could be SRA KEY, CONTINUE, ACCEPT, or REJECT */
245 void
sra_reply(Authenticator * ap,unsigned char * data,int cnt)246 sra_reply(Authenticator *ap, unsigned char *data, int cnt)
247 {
248 char uprompt[256],tuser[256];
249 Session_Key skey;
250 size_t i;
251
252 if (cnt-- < 1)
253 return;
254 switch (*data++) {
255
256 case SRA_KEY:
257 /* calculate common key */
258 if (cnt < HEXKEYBYTES) {
259 if (auth_debug_mode) {
260 printf("SRA user rejected for bad PKB\r\n");
261 }
262 return;
263 }
264 memcpy(pkb,data,HEXKEYBYTES);
265 pkb[HEXKEYBYTES] = '\0';
266
267 common_key(ska,pkb,&ik,&ck);
268
269 enc_user:
270
271 /* encode user */
272 memset(tuser,0,sizeof(tuser));
273 sprintf(uprompt,"User (%s): ",UserNameRequested);
274 telnet_gets(uprompt,tuser,255,1);
275 if (tuser[0] == '\n' || tuser[0] == '\r' )
276 strcpy(user,UserNameRequested);
277 else {
278 /* telnet_gets leaves the newline on */
279 for(i=0;i<sizeof(tuser);i++) {
280 if (tuser[i] == '\n') {
281 tuser[i] = '\0';
282 break;
283 }
284 }
285 strcpy(user,tuser);
286 }
287 pk_encode(user,xuser,&ck);
288
289 /* send it off */
290 if (auth_debug_mode)
291 printf("Sent KAB(U)\r\n");
292 if (!Data(ap, SRA_USER, (void *)xuser, strlen(xuser))) {
293 if (auth_debug_mode)
294 printf("Not enough room\r\n");
295 return;
296 }
297 break;
298
299 case SRA_CONTINUE:
300 if (passwd_sent) {
301 passwd_sent = 0;
302 printf("[ SRA login failed ]\r\n");
303 goto enc_user;
304 }
305 /* encode password */
306 memset(pass,0,256);
307 telnet_gets("Password: ",pass,255,0);
308 pk_encode(pass,xpass,&ck);
309 /* send it off */
310 if (auth_debug_mode)
311 printf("Sent KAB(P)\r\n");
312 if (!Data(ap, SRA_PASS, (void *)xpass, strlen(xpass))) {
313 if (auth_debug_mode)
314 printf("Not enough room\r\n");
315 return;
316 }
317 passwd_sent = 1;
318 break;
319
320 case SRA_REJECT:
321 printf("[ SRA refuses authentication ]\r\n");
322 printf("Trying plaintext login:\r\n");
323 auth_finished(0,AUTH_REJECT);
324 return;
325
326 case SRA_ACCEPT:
327 printf("[ SRA accepts you ]\r\n");
328 skey.data = ck;
329 skey.type = SK_DES;
330 skey.length = 8;
331 encrypt_session_key(&skey, 0);
332
333 auth_finished(ap, AUTH_VALID);
334 return;
335 default:
336 if (auth_debug_mode)
337 printf("Unknown SRA option %d\r\n", data[-1]);
338 return;
339 }
340 }
341
342 int
sra_status(Authenticator * ap __unused,char * name,int level)343 sra_status(Authenticator *ap __unused, char *name, int level)
344 {
345 if (level < AUTH_USER)
346 return(level);
347 if (UserNameRequested && sra_valid) {
348 strcpy(name, UserNameRequested);
349 return(AUTH_VALID);
350 } else
351 return(AUTH_USER);
352 }
353
354 #define BUMP(buf, len) while (*(buf)) {++(buf), --(len);}
355 #define ADDC(buf, len, c) if ((len) > 0) {*(buf)++ = (c); --(len);}
356
357 void
sra_printsub(unsigned char * data,int cnt,unsigned char * buf,int buflen)358 sra_printsub(unsigned char *data, int cnt, unsigned char *buf, int buflen)
359 {
360 char lbuf[32];
361 int i;
362
363 buf[buflen-1] = '\0'; /* make sure its NULL terminated */
364 buflen -= 1;
365
366 switch(data[3]) {
367
368 case SRA_CONTINUE:
369 strncpy((char *)buf, " CONTINUE ", buflen);
370 goto common;
371
372 case SRA_REJECT: /* Rejected (reason might follow) */
373 strncpy((char *)buf, " REJECT ", buflen);
374 goto common;
375
376 case SRA_ACCEPT: /* Accepted (name might follow) */
377 strncpy((char *)buf, " ACCEPT ", buflen);
378
379 common:
380 BUMP(buf, buflen);
381 if (cnt <= 4)
382 break;
383 ADDC(buf, buflen, '"');
384 for (i = 4; i < cnt; i++)
385 ADDC(buf, buflen, data[i]);
386 ADDC(buf, buflen, '"');
387 ADDC(buf, buflen, '\0');
388 break;
389
390 case SRA_KEY: /* Authentication data follows */
391 strncpy((char *)buf, " KEY ", buflen);
392 goto common2;
393
394 case SRA_USER:
395 strncpy((char *)buf, " USER ", buflen);
396 goto common2;
397
398 case SRA_PASS:
399 strncpy((char *)buf, " PASS ", buflen);
400 goto common2;
401
402 default:
403 sprintf(lbuf, " %d (unknown)", data[3]);
404 strncpy((char *)buf, lbuf, buflen);
405 common2:
406 BUMP(buf, buflen);
407 for (i = 4; i < cnt; i++) {
408 sprintf(lbuf, " %d", data[i]);
409 strncpy((char *)buf, lbuf, buflen);
410 BUMP(buf, buflen);
411 }
412 break;
413 }
414 }
415
416 static int
isroot(const char * usr)417 isroot(const char *usr)
418 {
419 struct passwd *pwd;
420
421 if ((pwd=getpwnam(usr))==NULL)
422 return 0;
423 return (!pwd->pw_uid);
424 }
425
426 static int
rootterm(char * ttyn)427 rootterm(char *ttyn)
428 {
429 struct ttyent *t;
430
431 return ((t = getttynam(ttyn)) && t->ty_status & TTY_SECURE);
432 }
433
434 #ifdef NOPAM
435 static int
check_user(char * name,char * cred)436 check_user(char *name, char *cred)
437 {
438 char *cp;
439 char *xpasswd, *salt;
440
441 if (isroot(name) && !rootterm(line))
442 {
443 crypt("AA","*"); /* Waste some time to simulate success */
444 return(0);
445 }
446
447 if (pw = sgetpwnam(name)) {
448 if (pw->pw_shell == NULL) {
449 pw = (struct passwd *) NULL;
450 return(0);
451 }
452
453 salt = pw->pw_passwd;
454 xpasswd = crypt(cred, salt);
455 /* The strcmp does not catch null passwords! */
456 if (pw == NULL || *pw->pw_passwd == '\0' ||
457 strcmp(xpasswd, pw->pw_passwd)) {
458 pw = (struct passwd *) NULL;
459 return(0);
460 }
461 return(1);
462 }
463 return(0);
464 }
465 #else
466
467 /*
468 * The following is stolen from ftpd, which stole it from the imap-uw
469 * PAM module and login.c. It is needed because we can't really
470 * "converse" with the user, having already gone to the trouble of
471 * getting their username and password through an encrypted channel.
472 */
473
474 #define COPY_STRING(s) (s ? strdup(s):NULL)
475
476 struct cred_t {
477 const char *uname;
478 const char *pass;
479 };
480 typedef struct cred_t cred_t;
481
482 static int
auth_conv(int num_msg,const struct pam_message ** msg,struct pam_response ** resp,void * appdata)483 auth_conv(int num_msg, const struct pam_message **msg, struct pam_response **resp, void *appdata)
484 {
485 int i;
486 cred_t *cred = (cred_t *) appdata;
487 struct pam_response *reply =
488 malloc(sizeof(struct pam_response) * num_msg);
489
490 if (reply == NULL)
491 return PAM_BUF_ERR;
492
493 for (i = 0; i < num_msg; i++) {
494 switch (msg[i]->msg_style) {
495 case PAM_PROMPT_ECHO_ON: /* assume want user name */
496 reply[i].resp_retcode = PAM_SUCCESS;
497 reply[i].resp = COPY_STRING(cred->uname);
498 /* PAM frees resp. */
499 break;
500 case PAM_PROMPT_ECHO_OFF: /* assume want password */
501 reply[i].resp_retcode = PAM_SUCCESS;
502 reply[i].resp = COPY_STRING(cred->pass);
503 /* PAM frees resp. */
504 break;
505 case PAM_TEXT_INFO:
506 case PAM_ERROR_MSG:
507 reply[i].resp_retcode = PAM_SUCCESS;
508 reply[i].resp = NULL;
509 break;
510 default: /* unknown message style */
511 free(reply);
512 return PAM_CONV_ERR;
513 }
514 }
515
516 *resp = reply;
517 return PAM_SUCCESS;
518 }
519
520 /*
521 * The PAM version as a side effect may put a new username in *name.
522 */
523 static int
check_user(char * name,char * cred)524 check_user(char *name, char *cred)
525 {
526 pam_handle_t *pamh = NULL;
527 const void *item;
528 int rval;
529 int e;
530 cred_t auth_cred = { name, cred };
531 struct pam_conv conv = { &auth_conv, &auth_cred };
532
533 e = pam_start("telnetd", name, &conv, &pamh);
534 if (e != PAM_SUCCESS) {
535 syslog(LOG_ERR, "pam_start: %s", pam_strerror(pamh, e));
536 return 0;
537 }
538
539 #if 0 /* Where can we find this value? */
540 e = pam_set_item(pamh, PAM_RHOST, remotehost);
541 if (e != PAM_SUCCESS) {
542 syslog(LOG_ERR, "pam_set_item(PAM_RHOST): %s",
543 pam_strerror(pamh, e));
544 return 0;
545 }
546 #endif
547
548 e = pam_authenticate(pamh, 0);
549 switch (e) {
550 case PAM_SUCCESS:
551 /*
552 * With PAM we support the concept of a "template"
553 * user. The user enters a login name which is
554 * authenticated by PAM, usually via a remote service
555 * such as RADIUS or TACACS+. If authentication
556 * succeeds, a different but related "template" name
557 * is used for setting the credentials, shell, and
558 * home directory. The name the user enters need only
559 * exist on the remote authentication server, but the
560 * template name must be present in the local password
561 * database.
562 *
563 * This is supported by two various mechanisms in the
564 * individual modules. However, from the application's
565 * point of view, the template user is always passed
566 * back as a changed value of the PAM_USER item.
567 */
568 if ((e = pam_get_item(pamh, PAM_USER, &item)) ==
569 PAM_SUCCESS) {
570 strcpy(name, item);
571 } else
572 syslog(LOG_ERR, "Couldn't get PAM_USER: %s",
573 pam_strerror(pamh, e));
574 if (isroot(name) && !rootterm(line))
575 rval = 0;
576 else
577 rval = 1;
578 break;
579
580 case PAM_AUTH_ERR:
581 case PAM_USER_UNKNOWN:
582 case PAM_MAXTRIES:
583 rval = 0;
584 break;
585
586 default:
587 syslog(LOG_ERR, "auth_pam: %s", pam_strerror(pamh, e));
588 rval = 0;
589 break;
590 }
591
592 if ((e = pam_end(pamh, e)) != PAM_SUCCESS) {
593 syslog(LOG_ERR, "pam_end: %s", pam_strerror(pamh, e));
594 rval = 0;
595 }
596 return rval;
597 }
598
599 #endif
600
601 #endif /* ENCRYPTION */
602 #endif /* SRA */
603