1/*	$OpenBSD: upap.c,v 1.11 2017/11/17 20:48:30 jca Exp $	*/
2
3/*
4 * upap.c - User/Password Authentication Protocol.
5 *
6 * Copyright (c) 1984-2000 Carnegie Mellon University. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in
17 *    the documentation and/or other materials provided with the
18 *    distribution.
19 *
20 * 3. The name "Carnegie Mellon University" must not be used to
21 *    endorse or promote products derived from this software without
22 *    prior written permission. For permission or any legal
23 *    details, please contact
24 *      Office of Technology Transfer
25 *      Carnegie Mellon University
26 *      5000 Forbes Avenue
27 *      Pittsburgh, PA  15213-3890
28 *      (412) 268-4387, fax: (412) 268-7395
29 *      tech-transfer@andrew.cmu.edu
30 *
31 * 4. Redistributions of any form whatsoever must retain the following
32 *    acknowledgment:
33 *    "This product includes software developed by Computing Services
34 *     at Carnegie Mellon University (http://www.cmu.edu/computing/)."
35 *
36 * CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
37 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
38 * AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
39 * FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
40 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
41 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
42 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
43 */
44
45/*
46 * TODO:
47 */
48
49#include <stdio.h>
50#include <string.h>
51#include <sys/types.h>
52#include <sys/time.h>
53#include <syslog.h>
54
55#include "pppd.h"
56#include "upap.h"
57
58/*
59 * Protocol entry points.
60 */
61static void upap_init(int);
62static void upap_lowerup(int);
63static void upap_lowerdown(int);
64static void upap_input(int, u_char *, int);
65static void upap_protrej(int);
66static int  upap_printpkt(u_char *, int, void (*)(void *, char *, ...), void *);
67
68struct protent pap_protent = {
69    PPP_PAP,
70    upap_init,
71    upap_input,
72    upap_protrej,
73    upap_lowerup,
74    upap_lowerdown,
75    NULL,
76    NULL,
77    upap_printpkt,
78    NULL,
79    1,
80    "PAP",
81    NULL,
82    NULL,
83    NULL
84};
85
86upap_state upap[NUM_PPP];		/* UPAP state; one for each unit */
87
88static void upap_timeout(void *);
89static void upap_reqtimeout(void *);
90static void upap_rauthreq(upap_state *, u_char *, int, int);
91static void upap_rauthack(upap_state *, u_char *, int, int);
92static void upap_rauthnak(upap_state *, u_char *, int, int);
93static void upap_sauthreq(upap_state *);
94static void upap_sresp(upap_state *, int, int, char *, int);
95
96
97/*
98 * upap_init - Initialize a UPAP unit.
99 */
100static void
101upap_init(unit)
102    int unit;
103{
104    upap_state *u = &upap[unit];
105
106    u->us_unit = unit;
107    u->us_user = NULL;
108    u->us_userlen = 0;
109    u->us_passwd = NULL;
110    u->us_passwdlen = 0;
111    u->us_clientstate = UPAPCS_INITIAL;
112    u->us_serverstate = UPAPSS_INITIAL;
113    u->us_id = 0;
114    u->us_timeouttime = UPAP_DEFTIMEOUT;
115    u->us_maxtransmits = 10;
116    u->us_reqtimeout = UPAP_DEFREQTIME;
117}
118
119
120/*
121 * upap_authwithpeer - Authenticate us with our peer (start client).
122 *
123 * Set new state and send authenticate's.
124 */
125void
126upap_authwithpeer(unit, user, password)
127    int unit;
128    char *user, *password;
129{
130    upap_state *u = &upap[unit];
131
132    /* Save the username and password we're given */
133    u->us_user = user;
134    u->us_userlen = strlen(user);
135    u->us_passwd = password;
136    u->us_passwdlen = strlen(password);
137    u->us_transmits = 0;
138
139    /* Lower layer up yet? */
140    if (u->us_clientstate == UPAPCS_INITIAL ||
141	u->us_clientstate == UPAPCS_PENDING) {
142	u->us_clientstate = UPAPCS_PENDING;
143	return;
144    }
145
146    upap_sauthreq(u);			/* Start protocol */
147}
148
149
150/*
151 * upap_authpeer - Authenticate our peer (start server).
152 *
153 * Set new state.
154 */
155void
156upap_authpeer(unit)
157    int unit;
158{
159    upap_state *u = &upap[unit];
160
161    /* Lower layer up yet? */
162    if (u->us_serverstate == UPAPSS_INITIAL ||
163	u->us_serverstate == UPAPSS_PENDING) {
164	u->us_serverstate = UPAPSS_PENDING;
165	return;
166    }
167
168    u->us_serverstate = UPAPSS_LISTEN;
169    if (u->us_reqtimeout > 0)
170	TIMEOUT(upap_reqtimeout, u, u->us_reqtimeout);
171}
172
173
174/*
175 * upap_timeout - Retransmission timer for sending auth-reqs expired.
176 */
177static void
178upap_timeout(arg)
179    void *arg;
180{
181    upap_state *u = (upap_state *) arg;
182
183    if (u->us_clientstate != UPAPCS_AUTHREQ)
184	return;
185
186    if (u->us_transmits >= u->us_maxtransmits) {
187	/* give up in disgust */
188	syslog(LOG_ERR, "No response to PAP authenticate-requests");
189	u->us_clientstate = UPAPCS_BADAUTH;
190	auth_withpeer_fail(u->us_unit, PPP_PAP);
191	return;
192    }
193
194    upap_sauthreq(u);		/* Send Authenticate-Request */
195}
196
197
198/*
199 * upap_reqtimeout - Give up waiting for the peer to send an auth-req.
200 */
201static void
202upap_reqtimeout(arg)
203    void *arg;
204{
205    upap_state *u = (upap_state *) arg;
206
207    if (u->us_serverstate != UPAPSS_LISTEN)
208	return;			/* huh?? */
209
210    auth_peer_fail(u->us_unit, PPP_PAP);
211    u->us_serverstate = UPAPSS_BADAUTH;
212}
213
214
215/*
216 * upap_lowerup - The lower layer is up.
217 *
218 * Start authenticating if pending.
219 */
220static void
221upap_lowerup(unit)
222    int unit;
223{
224    upap_state *u = &upap[unit];
225
226    if (u->us_clientstate == UPAPCS_INITIAL)
227	u->us_clientstate = UPAPCS_CLOSED;
228    else if (u->us_clientstate == UPAPCS_PENDING) {
229	upap_sauthreq(u);	/* send an auth-request */
230    }
231
232    if (u->us_serverstate == UPAPSS_INITIAL)
233	u->us_serverstate = UPAPSS_CLOSED;
234    else if (u->us_serverstate == UPAPSS_PENDING) {
235	u->us_serverstate = UPAPSS_LISTEN;
236	if (u->us_reqtimeout > 0)
237	    TIMEOUT(upap_reqtimeout, u, u->us_reqtimeout);
238    }
239}
240
241
242/*
243 * upap_lowerdown - The lower layer is down.
244 *
245 * Cancel all timeouts.
246 */
247static void
248upap_lowerdown(unit)
249    int unit;
250{
251    upap_state *u = &upap[unit];
252
253    if (u->us_clientstate == UPAPCS_AUTHREQ)	/* Timeout pending? */
254	UNTIMEOUT(upap_timeout, u);	/* Cancel timeout */
255    if (u->us_serverstate == UPAPSS_LISTEN && u->us_reqtimeout > 0)
256	UNTIMEOUT(upap_reqtimeout, u);
257
258    u->us_clientstate = UPAPCS_INITIAL;
259    u->us_serverstate = UPAPSS_INITIAL;
260}
261
262
263/*
264 * upap_protrej - Peer doesn't speak this protocol.
265 *
266 * This shouldn't happen.  In any case, pretend lower layer went down.
267 */
268static void
269upap_protrej(unit)
270    int unit;
271{
272    upap_state *u = &upap[unit];
273
274    if (u->us_clientstate == UPAPCS_AUTHREQ) {
275	syslog(LOG_ERR, "PAP authentication failed due to protocol-reject");
276	auth_withpeer_fail(unit, PPP_PAP);
277    }
278    if (u->us_serverstate == UPAPSS_LISTEN) {
279	syslog(LOG_ERR, "PAP authentication of peer failed (protocol-reject)");
280	auth_peer_fail(unit, PPP_PAP);
281    }
282    upap_lowerdown(unit);
283}
284
285
286/*
287 * upap_input - Input UPAP packet.
288 */
289static void
290upap_input(unit, inpacket, l)
291    int unit;
292    u_char *inpacket;
293    int l;
294{
295    upap_state *u = &upap[unit];
296    u_char *inp;
297    u_char code, id;
298    int len;
299
300    /*
301     * Parse header (code, id and length).
302     * If packet too short, drop it.
303     */
304    inp = inpacket;
305    if (l < UPAP_HEADERLEN) {
306	UPAPDEBUG((LOG_INFO, "pap_input: rcvd short header."));
307	return;
308    }
309    GETCHAR(code, inp);
310    GETCHAR(id, inp);
311    GETSHORT(len, inp);
312    if (len < UPAP_HEADERLEN) {
313	UPAPDEBUG((LOG_INFO, "pap_input: rcvd illegal length."));
314	return;
315    }
316    if (len > l) {
317	UPAPDEBUG((LOG_INFO, "pap_input: rcvd short packet."));
318	return;
319    }
320    len -= UPAP_HEADERLEN;
321
322    /*
323     * Action depends on code.
324     */
325    switch (code) {
326    case UPAP_AUTHREQ:
327	upap_rauthreq(u, inp, id, len);
328	break;
329
330    case UPAP_AUTHACK:
331	upap_rauthack(u, inp, id, len);
332	break;
333
334    case UPAP_AUTHNAK:
335	upap_rauthnak(u, inp, id, len);
336	break;
337
338    default:				/* XXX Need code reject */
339	break;
340    }
341}
342
343
344/*
345 * upap_rauth - Receive Authenticate.
346 */
347static void
348upap_rauthreq(u, inp, id, len)
349    upap_state *u;
350    u_char *inp;
351    int id;
352    int len;
353{
354    u_char ruserlen, rpasswdlen;
355    char *ruser, *rpasswd;
356    int retcode;
357    char *msg;
358    int msglen;
359
360    UPAPDEBUG((LOG_INFO, "pap_rauth: Rcvd id %d.", id));
361
362    if (u->us_serverstate < UPAPSS_LISTEN)
363	return;
364
365    /*
366     * If we receive a duplicate authenticate-request, we are
367     * supposed to return the same status as for the first request.
368     */
369    if (u->us_serverstate == UPAPSS_OPEN) {
370	upap_sresp(u, UPAP_AUTHACK, id, "", 0);	/* return auth-ack */
371	return;
372    }
373    if (u->us_serverstate == UPAPSS_BADAUTH) {
374	upap_sresp(u, UPAP_AUTHNAK, id, "", 0);	/* return auth-nak */
375	return;
376    }
377
378    /*
379     * Parse user/passwd.
380     */
381    if (len < sizeof (u_char)) {
382	UPAPDEBUG((LOG_INFO, "pap_rauth: rcvd short packet."));
383	return;
384    }
385    GETCHAR(ruserlen, inp);
386    len -= sizeof (u_char) + ruserlen + sizeof (u_char);
387    if (len < 0) {
388	UPAPDEBUG((LOG_INFO, "pap_rauth: rcvd short packet."));
389	return;
390    }
391    ruser = (char *) inp;
392    INCPTR(ruserlen, inp);
393    GETCHAR(rpasswdlen, inp);
394    if (len < rpasswdlen) {
395	UPAPDEBUG((LOG_INFO, "pap_rauth: rcvd short packet."));
396	return;
397    }
398    rpasswd = (char *) inp;
399
400    /*
401     * Check the username and password given.
402     */
403    retcode = check_passwd(u->us_unit, ruser, ruserlen, rpasswd,
404			   rpasswdlen, &msg, &msglen);
405    EXPLICIT_BZERO(rpasswd, rpasswdlen);
406
407    upap_sresp(u, retcode, id, msg, msglen);
408
409    if (retcode == UPAP_AUTHACK) {
410	u->us_serverstate = UPAPSS_OPEN;
411	auth_peer_success(u->us_unit, PPP_PAP, ruser, ruserlen);
412    } else {
413	u->us_serverstate = UPAPSS_BADAUTH;
414	auth_peer_fail(u->us_unit, PPP_PAP);
415    }
416
417    if (u->us_reqtimeout > 0)
418	UNTIMEOUT(upap_reqtimeout, u);
419}
420
421
422/*
423 * upap_rauthack - Receive Authenticate-Ack.
424 */
425static void
426upap_rauthack(u, inp, id, len)
427    upap_state *u;
428    u_char *inp;
429    int id;
430    int len;
431{
432    u_char msglen;
433    char *msg;
434
435    UPAPDEBUG((LOG_INFO, "pap_rauthack: Rcvd id %d.", id));
436    if (u->us_clientstate != UPAPCS_AUTHREQ) /* XXX */
437	return;
438
439    /*
440     * Parse message.
441     */
442    if (len < sizeof (u_char)) {
443	UPAPDEBUG((LOG_INFO, "pap_rauthack: rcvd short packet."));
444	return;
445    }
446    GETCHAR(msglen, inp);
447    len -= sizeof (u_char);
448    if (len < msglen) {
449	UPAPDEBUG((LOG_INFO, "pap_rauthack: rcvd short packet."));
450	return;
451    }
452    msg = (char *) inp;
453    PRINTMSG(msg, msglen);
454
455    u->us_clientstate = UPAPCS_OPEN;
456
457    auth_withpeer_success(u->us_unit, PPP_PAP);
458}
459
460
461/*
462 * upap_rauthnak - Receive Authenticate-Nakk.
463 */
464static void
465upap_rauthnak(u, inp, id, len)
466    upap_state *u;
467    u_char *inp;
468    int id;
469    int len;
470{
471    u_char msglen;
472    char *msg;
473
474    UPAPDEBUG((LOG_INFO, "pap_rauthnak: Rcvd id %d.", id));
475    if (u->us_clientstate != UPAPCS_AUTHREQ) /* XXX */
476	return;
477
478    /*
479     * Parse message.
480     */
481    if (len < sizeof (u_char)) {
482	UPAPDEBUG((LOG_INFO, "pap_rauthnak: rcvd short packet."));
483	return;
484    }
485    GETCHAR(msglen, inp);
486    len -= sizeof (u_char);
487    if (len < msglen) {
488	UPAPDEBUG((LOG_INFO, "pap_rauthnak: rcvd short packet."));
489	return;
490    }
491    msg = (char *) inp;
492    PRINTMSG(msg, msglen);
493
494    u->us_clientstate = UPAPCS_BADAUTH;
495
496    syslog(LOG_ERR, "PAP authentication failed");
497    auth_withpeer_fail(u->us_unit, PPP_PAP);
498}
499
500
501/*
502 * upap_sauthreq - Send an Authenticate-Request.
503 */
504static void
505upap_sauthreq(u)
506    upap_state *u;
507{
508    u_char *outp;
509    int outlen;
510
511    outlen = UPAP_HEADERLEN + 2 * sizeof (u_char) +
512	u->us_userlen + u->us_passwdlen;
513    outp = outpacket_buf;
514
515    MAKEHEADER(outp, PPP_PAP);
516
517    PUTCHAR(UPAP_AUTHREQ, outp);
518    PUTCHAR(++u->us_id, outp);
519    PUTSHORT(outlen, outp);
520    PUTCHAR(u->us_userlen, outp);
521    BCOPY(u->us_user, outp, u->us_userlen);
522    INCPTR(u->us_userlen, outp);
523    PUTCHAR(u->us_passwdlen, outp);
524    BCOPY(u->us_passwd, outp, u->us_passwdlen);
525
526    output(u->us_unit, outpacket_buf, outlen + PPP_HDRLEN);
527
528    UPAPDEBUG((LOG_INFO, "pap_sauth: Sent id %d.", u->us_id));
529
530    TIMEOUT(upap_timeout, u, u->us_timeouttime);
531    ++u->us_transmits;
532    u->us_clientstate = UPAPCS_AUTHREQ;
533}
534
535
536/*
537 * upap_sresp - Send a response (ack or nak).
538 */
539static void
540upap_sresp(u, code, id, msg, msglen)
541    upap_state *u;
542    u_char code, id;
543    char *msg;
544    int msglen;
545{
546    u_char *outp;
547    int outlen;
548
549    outlen = UPAP_HEADERLEN + sizeof (u_char) + msglen;
550    outp = outpacket_buf;
551    MAKEHEADER(outp, PPP_PAP);
552
553    PUTCHAR(code, outp);
554    PUTCHAR(id, outp);
555    PUTSHORT(outlen, outp);
556    PUTCHAR(msglen, outp);
557    BCOPY(msg, outp, msglen);
558    output(u->us_unit, outpacket_buf, outlen + PPP_HDRLEN);
559
560    UPAPDEBUG((LOG_INFO, "pap_sresp: Sent code %d, id %d.", code, id));
561}
562
563/*
564 * upap_printpkt - print the contents of a PAP packet.
565 */
566static char *upap_codenames[] = {
567    "AuthReq", "AuthAck", "AuthNak"
568};
569
570static int
571upap_printpkt(p, plen, printer, arg)
572    u_char *p;
573    int plen;
574    void (*printer)(void *, char *, ...);
575    void *arg;
576{
577    int code, id, len;
578    int mlen, ulen, wlen;
579    char *user, *pwd, *msg;
580    u_char *pstart;
581
582    if (plen < UPAP_HEADERLEN)
583	return 0;
584    pstart = p;
585    GETCHAR(code, p);
586    GETCHAR(id, p);
587    GETSHORT(len, p);
588    if (len < UPAP_HEADERLEN || len > plen)
589	return 0;
590
591    if (code >= 1 && code <= sizeof(upap_codenames) / sizeof(char *))
592	printer(arg, " %s", upap_codenames[code-1]);
593    else
594	printer(arg, " code=0x%x", code);
595    printer(arg, " id=0x%x", id);
596    len -= UPAP_HEADERLEN;
597    switch (code) {
598    case UPAP_AUTHREQ:
599	if (len < 1)
600	    break;
601	ulen = p[0];
602	if (len < ulen + 2)
603	    break;
604	wlen = p[ulen + 1];
605	if (len < ulen + wlen + 2)
606	    break;
607	user = (char *) (p + 1);
608	pwd = (char *) (p + ulen + 2);
609	p += ulen + wlen + 2;
610	len -= ulen + wlen + 2;
611	printer(arg, " user=");
612	print_string(user, ulen, printer, arg);
613	printer(arg, " password=");
614	print_string(pwd, wlen, printer, arg);
615	break;
616    case UPAP_AUTHACK:
617    case UPAP_AUTHNAK:
618	if (len < 1)
619	    break;
620	mlen = p[0];
621	if (len < mlen + 1)
622	    break;
623	msg = (char *) (p + 1);
624	p += mlen + 1;
625	len -= mlen + 1;
626	printer(arg, " ");
627	print_string(msg, mlen, printer, arg);
628	break;
629    }
630
631    /* print the rest of the bytes in the packet */
632    for (; len > 0; --len) {
633	GETCHAR(code, p);
634	printer(arg, " %.2x", code);
635    }
636
637    return p - pstart;
638}
639