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      1 /*
      2  * upap.c - User/Password Authentication Protocol.
      3  *
      4  * Copyright (c) 1984-2000 Carnegie Mellon University. All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  *
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  *
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in
     15  *    the documentation and/or other materials provided with the
     16  *    distribution.
     17  *
     18  * 3. The name "Carnegie Mellon University" must not be used to
     19  *    endorse or promote products derived from this software without
     20  *    prior written permission. For permission or any legal
     21  *    details, please contact
     22  *      Office of Technology Transfer
     23  *      Carnegie Mellon University
     24  *      5000 Forbes Avenue
     25  *      Pittsburgh, PA  15213-3890
     26  *      (412) 268-4387, fax: (412) 268-7395
     27  *      tech-transfer (at) andrew.cmu.edu
     28  *
     29  * 4. Redistributions of any form whatsoever must retain the following
     30  *    acknowledgment:
     31  *    "This product includes software developed by Computing Services
     32  *     at Carnegie Mellon University (http://www.cmu.edu/computing/)."
     33  *
     34  * CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
     35  * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
     36  * AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
     37  * FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     38  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
     39  * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
     40  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     41  */
     42 
     43 #define RCSID	"$Id: upap.c,v 1.29 2002/12/04 23:03:33 paulus Exp $"
     44 
     45 /*
     46  * TODO:
     47  */
     48 
     49 #include <stdio.h>
     50 #include <string.h>
     51 
     52 #include "pppd.h"
     53 #include "upap.h"
     54 
     55 static const char rcsid[] = RCSID;
     56 
     57 static bool hide_password = 1;
     58 
     59 /*
     60  * Command-line options.
     61  */
     62 static option_t pap_option_list[] = {
     63     { "hide-password", o_bool, &hide_password,
     64       "Don't output passwords to log", OPT_PRIO | 1 },
     65     { "show-password", o_bool, &hide_password,
     66       "Show password string in debug log messages", OPT_PRIOSUB | 0 },
     67 
     68     { "pap-restart", o_int, &upap[0].us_timeouttime,
     69       "Set retransmit timeout for PAP", OPT_PRIO },
     70     { "pap-max-authreq", o_int, &upap[0].us_maxtransmits,
     71       "Set max number of transmissions for auth-reqs", OPT_PRIO },
     72     { "pap-timeout", o_int, &upap[0].us_reqtimeout,
     73       "Set time limit for peer PAP authentication", OPT_PRIO },
     74 
     75     { NULL }
     76 };
     77 
     78 /*
     79  * Protocol entry points.
     80  */
     81 static void upap_init __P((int));
     82 static void upap_lowerup __P((int));
     83 static void upap_lowerdown __P((int));
     84 static void upap_input __P((int, u_char *, int));
     85 static void upap_protrej __P((int));
     86 static int  upap_printpkt __P((u_char *, int,
     87 			       void (*) __P((void *, char *, ...)), void *));
     88 
     89 struct protent pap_protent = {
     90     PPP_PAP,
     91     upap_init,
     92     upap_input,
     93     upap_protrej,
     94     upap_lowerup,
     95     upap_lowerdown,
     96     NULL,
     97     NULL,
     98     upap_printpkt,
     99     NULL,
    100     1,
    101     "PAP",
    102     NULL,
    103     pap_option_list,
    104     NULL,
    105     NULL,
    106     NULL
    107 };
    108 
    109 upap_state upap[NUM_PPP];		/* UPAP state; one for each unit */
    110 
    111 static void upap_timeout __P((void *));
    112 static void upap_reqtimeout __P((void *));
    113 static void upap_rauthreq __P((upap_state *, u_char *, int, int));
    114 static void upap_rauthack __P((upap_state *, u_char *, int, int));
    115 static void upap_rauthnak __P((upap_state *, u_char *, int, int));
    116 static void upap_sauthreq __P((upap_state *));
    117 static void upap_sresp __P((upap_state *, int, int, char *, int));
    118 
    119 
    120 /*
    121  * upap_init - Initialize a UPAP unit.
    122  */
    123 static void
    124 upap_init(unit)
    125     int unit;
    126 {
    127     upap_state *u = &upap[unit];
    128 
    129     u->us_unit = unit;
    130     u->us_user = NULL;
    131     u->us_userlen = 0;
    132     u->us_passwd = NULL;
    133     u->us_passwdlen = 0;
    134     u->us_clientstate = UPAPCS_INITIAL;
    135     u->us_serverstate = UPAPSS_INITIAL;
    136     u->us_id = 0;
    137     u->us_timeouttime = UPAP_DEFTIMEOUT;
    138     u->us_maxtransmits = 10;
    139     u->us_reqtimeout = UPAP_DEFREQTIME;
    140 }
    141 
    142 
    143 /*
    144  * upap_authwithpeer - Authenticate us with our peer (start client).
    145  *
    146  * Set new state and send authenticate's.
    147  */
    148 void
    149 upap_authwithpeer(unit, user, password)
    150     int unit;
    151     char *user, *password;
    152 {
    153     upap_state *u = &upap[unit];
    154 
    155     /* Save the username and password we're given */
    156     u->us_user = user;
    157     u->us_userlen = strlen(user);
    158     u->us_passwd = password;
    159     u->us_passwdlen = strlen(password);
    160     u->us_transmits = 0;
    161 
    162     /* Lower layer up yet? */
    163     if (u->us_clientstate == UPAPCS_INITIAL ||
    164 	u->us_clientstate == UPAPCS_PENDING) {
    165 	u->us_clientstate = UPAPCS_PENDING;
    166 	return;
    167     }
    168 
    169     upap_sauthreq(u);			/* Start protocol */
    170 }
    171 
    172 
    173 /*
    174  * upap_authpeer - Authenticate our peer (start server).
    175  *
    176  * Set new state.
    177  */
    178 void
    179 upap_authpeer(unit)
    180     int unit;
    181 {
    182     upap_state *u = &upap[unit];
    183 
    184     /* Lower layer up yet? */
    185     if (u->us_serverstate == UPAPSS_INITIAL ||
    186 	u->us_serverstate == UPAPSS_PENDING) {
    187 	u->us_serverstate = UPAPSS_PENDING;
    188 	return;
    189     }
    190 
    191     u->us_serverstate = UPAPSS_LISTEN;
    192     if (u->us_reqtimeout > 0)
    193 	TIMEOUT(upap_reqtimeout, u, u->us_reqtimeout);
    194 }
    195 
    196 
    197 /*
    198  * upap_timeout - Retransmission timer for sending auth-reqs expired.
    199  */
    200 static void
    201 upap_timeout(arg)
    202     void *arg;
    203 {
    204     upap_state *u = (upap_state *) arg;
    205 
    206     if (u->us_clientstate != UPAPCS_AUTHREQ)
    207 	return;
    208 
    209     if (u->us_transmits >= u->us_maxtransmits) {
    210 	/* give up in disgust */
    211 	error("No response to PAP authenticate-requests");
    212 	u->us_clientstate = UPAPCS_BADAUTH;
    213 	auth_withpeer_fail(u->us_unit, PPP_PAP);
    214 	return;
    215     }
    216 
    217     upap_sauthreq(u);		/* Send Authenticate-Request */
    218 }
    219 
    220 
    221 /*
    222  * upap_reqtimeout - Give up waiting for the peer to send an auth-req.
    223  */
    224 static void
    225 upap_reqtimeout(arg)
    226     void *arg;
    227 {
    228     upap_state *u = (upap_state *) arg;
    229 
    230     if (u->us_serverstate != UPAPSS_LISTEN)
    231 	return;			/* huh?? */
    232 
    233     auth_peer_fail(u->us_unit, PPP_PAP);
    234     u->us_serverstate = UPAPSS_BADAUTH;
    235 }
    236 
    237 
    238 /*
    239  * upap_lowerup - The lower layer is up.
    240  *
    241  * Start authenticating if pending.
    242  */
    243 static void
    244 upap_lowerup(unit)
    245     int unit;
    246 {
    247     upap_state *u = &upap[unit];
    248 
    249     if (u->us_clientstate == UPAPCS_INITIAL)
    250 	u->us_clientstate = UPAPCS_CLOSED;
    251     else if (u->us_clientstate == UPAPCS_PENDING) {
    252 	upap_sauthreq(u);	/* send an auth-request */
    253     }
    254 
    255     if (u->us_serverstate == UPAPSS_INITIAL)
    256 	u->us_serverstate = UPAPSS_CLOSED;
    257     else if (u->us_serverstate == UPAPSS_PENDING) {
    258 	u->us_serverstate = UPAPSS_LISTEN;
    259 	if (u->us_reqtimeout > 0)
    260 	    TIMEOUT(upap_reqtimeout, u, u->us_reqtimeout);
    261     }
    262 }
    263 
    264 
    265 /*
    266  * upap_lowerdown - The lower layer is down.
    267  *
    268  * Cancel all timeouts.
    269  */
    270 static void
    271 upap_lowerdown(unit)
    272     int unit;
    273 {
    274     upap_state *u = &upap[unit];
    275 
    276     if (u->us_clientstate == UPAPCS_AUTHREQ)	/* Timeout pending? */
    277 	UNTIMEOUT(upap_timeout, u);		/* Cancel timeout */
    278     if (u->us_serverstate == UPAPSS_LISTEN && u->us_reqtimeout > 0)
    279 	UNTIMEOUT(upap_reqtimeout, u);
    280 
    281     u->us_clientstate = UPAPCS_INITIAL;
    282     u->us_serverstate = UPAPSS_INITIAL;
    283 }
    284 
    285 
    286 /*
    287  * upap_protrej - Peer doesn't speak this protocol.
    288  *
    289  * This shouldn't happen.  In any case, pretend lower layer went down.
    290  */
    291 static void
    292 upap_protrej(unit)
    293     int unit;
    294 {
    295     upap_state *u = &upap[unit];
    296 
    297     if (u->us_clientstate == UPAPCS_AUTHREQ) {
    298 	error("PAP authentication failed due to protocol-reject");
    299 	auth_withpeer_fail(unit, PPP_PAP);
    300     }
    301     if (u->us_serverstate == UPAPSS_LISTEN) {
    302 	error("PAP authentication of peer failed (protocol-reject)");
    303 	auth_peer_fail(unit, PPP_PAP);
    304     }
    305     upap_lowerdown(unit);
    306 }
    307 
    308 
    309 /*
    310  * upap_input - Input UPAP packet.
    311  */
    312 static void
    313 upap_input(unit, inpacket, l)
    314     int unit;
    315     u_char *inpacket;
    316     int l;
    317 {
    318     upap_state *u = &upap[unit];
    319     u_char *inp;
    320     u_char code, id;
    321     int len;
    322 
    323     /*
    324      * Parse header (code, id and length).
    325      * If packet too short, drop it.
    326      */
    327     inp = inpacket;
    328     if (l < UPAP_HEADERLEN) {
    329 	UPAPDEBUG(("pap_input: rcvd short header."));
    330 	return;
    331     }
    332     GETCHAR(code, inp);
    333     GETCHAR(id, inp);
    334     GETSHORT(len, inp);
    335     if (len < UPAP_HEADERLEN) {
    336 	UPAPDEBUG(("pap_input: rcvd illegal length."));
    337 	return;
    338     }
    339     if (len > l) {
    340 	UPAPDEBUG(("pap_input: rcvd short packet."));
    341 	return;
    342     }
    343     len -= UPAP_HEADERLEN;
    344 
    345     /*
    346      * Action depends on code.
    347      */
    348     switch (code) {
    349     case UPAP_AUTHREQ:
    350 	upap_rauthreq(u, inp, id, len);
    351 	break;
    352 
    353     case UPAP_AUTHACK:
    354 	upap_rauthack(u, inp, id, len);
    355 	break;
    356 
    357     case UPAP_AUTHNAK:
    358 	upap_rauthnak(u, inp, id, len);
    359 	break;
    360 
    361     default:				/* XXX Need code reject */
    362 	break;
    363     }
    364 }
    365 
    366 
    367 /*
    368  * upap_rauth - Receive Authenticate.
    369  */
    370 static void
    371 upap_rauthreq(u, inp, id, len)
    372     upap_state *u;
    373     u_char *inp;
    374     int id;
    375     int len;
    376 {
    377     u_char ruserlen, rpasswdlen;
    378     char *ruser, *rpasswd;
    379     char rhostname[256];
    380     int retcode;
    381     char *msg;
    382     int msglen;
    383 
    384     if (u->us_serverstate < UPAPSS_LISTEN)
    385 	return;
    386 
    387     /*
    388      * If we receive a duplicate authenticate-request, we are
    389      * supposed to return the same status as for the first request.
    390      */
    391     if (u->us_serverstate == UPAPSS_OPEN) {
    392 	upap_sresp(u, UPAP_AUTHACK, id, "", 0);	/* return auth-ack */
    393 	return;
    394     }
    395     if (u->us_serverstate == UPAPSS_BADAUTH) {
    396 	upap_sresp(u, UPAP_AUTHNAK, id, "", 0);	/* return auth-nak */
    397 	return;
    398     }
    399 
    400     /*
    401      * Parse user/passwd.
    402      */
    403     if (len < 1) {
    404 	UPAPDEBUG(("pap_rauth: rcvd short packet."));
    405 	return;
    406     }
    407     GETCHAR(ruserlen, inp);
    408     len -= sizeof (u_char) + ruserlen + sizeof (u_char);
    409     if (len < 0) {
    410 	UPAPDEBUG(("pap_rauth: rcvd short packet."));
    411 	return;
    412     }
    413     ruser = (char *) inp;
    414     INCPTR(ruserlen, inp);
    415     GETCHAR(rpasswdlen, inp);
    416     if (len < rpasswdlen) {
    417 	UPAPDEBUG(("pap_rauth: rcvd short packet."));
    418 	return;
    419     }
    420     rpasswd = (char *) inp;
    421 
    422     /*
    423      * Check the username and password given.
    424      */
    425     retcode = check_passwd(u->us_unit, ruser, ruserlen, rpasswd,
    426 			   rpasswdlen, &msg);
    427     BZERO(rpasswd, rpasswdlen);
    428 
    429     /*
    430      * Check remote number authorization.  A plugin may have filled in
    431      * the remote number or added an allowed number, and rather than
    432      * return an authenticate failure, is leaving it for us to verify.
    433      */
    434     if (retcode == UPAP_AUTHACK) {
    435 	if (!auth_number()) {
    436 	    /* We do not want to leak info about the pap result. */
    437 	    retcode = UPAP_AUTHNAK; /* XXX exit value will be "wrong" */
    438 	    warn("calling number %q is not authorized", remote_number);
    439 	}
    440     }
    441 
    442     msglen = strlen(msg);
    443     if (msglen > 255)
    444 	msglen = 255;
    445     upap_sresp(u, retcode, id, msg, msglen);
    446 
    447     /* Null terminate and clean remote name. */
    448     slprintf(rhostname, sizeof(rhostname), "%.*v", ruserlen, ruser);
    449 
    450     if (retcode == UPAP_AUTHACK) {
    451 	u->us_serverstate = UPAPSS_OPEN;
    452 	notice("PAP peer authentication succeeded for %q", rhostname);
    453 	auth_peer_success(u->us_unit, PPP_PAP, 0, ruser, ruserlen);
    454     } else {
    455 	u->us_serverstate = UPAPSS_BADAUTH;
    456 	warn("PAP peer authentication failed for %q", rhostname);
    457 	auth_peer_fail(u->us_unit, PPP_PAP);
    458     }
    459 
    460     if (u->us_reqtimeout > 0)
    461 	UNTIMEOUT(upap_reqtimeout, u);
    462 }
    463 
    464 
    465 /*
    466  * upap_rauthack - Receive Authenticate-Ack.
    467  */
    468 static void
    469 upap_rauthack(u, inp, id, len)
    470     upap_state *u;
    471     u_char *inp;
    472     int id;
    473     int len;
    474 {
    475     u_char msglen;
    476     char *msg;
    477 
    478     if (u->us_clientstate != UPAPCS_AUTHREQ) /* XXX */
    479 	return;
    480 
    481     /*
    482      * Parse message.
    483      */
    484     if (len < 1) {
    485 	UPAPDEBUG(("pap_rauthack: ignoring missing msg-length."));
    486     } else {
    487 	GETCHAR(msglen, inp);
    488 	if (msglen > 0) {
    489 	    len -= sizeof (u_char);
    490 	    if (len < msglen) {
    491 		UPAPDEBUG(("pap_rauthack: rcvd short packet."));
    492 		return;
    493 	    }
    494 	    msg = (char *) inp;
    495 	    PRINTMSG(msg, msglen);
    496 	}
    497     }
    498 
    499     u->us_clientstate = UPAPCS_OPEN;
    500 
    501     notice("PAP authentication succeeded");
    502     auth_withpeer_success(u->us_unit, PPP_PAP, 0);
    503 }
    504 
    505 
    506 /*
    507  * upap_rauthnak - Receive Authenticate-Nak.
    508  */
    509 static void
    510 upap_rauthnak(u, inp, id, len)
    511     upap_state *u;
    512     u_char *inp;
    513     int id;
    514     int len;
    515 {
    516     u_char msglen;
    517     char *msg;
    518 
    519     if (u->us_clientstate != UPAPCS_AUTHREQ) /* XXX */
    520 	return;
    521 
    522     /*
    523      * Parse message.
    524      */
    525     if (len < 1) {
    526 	UPAPDEBUG(("pap_rauthnak: ignoring missing msg-length."));
    527     } else {
    528 	GETCHAR(msglen, inp);
    529 	if (msglen > 0) {
    530 	    len -= sizeof (u_char);
    531 	    if (len < msglen) {
    532 		UPAPDEBUG(("pap_rauthnak: rcvd short packet."));
    533 		return;
    534 	    }
    535 	    msg = (char *) inp;
    536 	    PRINTMSG(msg, msglen);
    537 	}
    538     }
    539 
    540     u->us_clientstate = UPAPCS_BADAUTH;
    541 
    542     error("PAP authentication failed");
    543     auth_withpeer_fail(u->us_unit, PPP_PAP);
    544 }
    545 
    546 
    547 /*
    548  * upap_sauthreq - Send an Authenticate-Request.
    549  */
    550 static void
    551 upap_sauthreq(u)
    552     upap_state *u;
    553 {
    554     u_char *outp;
    555     int outlen;
    556 
    557     outlen = UPAP_HEADERLEN + 2 * sizeof (u_char) +
    558 	u->us_userlen + u->us_passwdlen;
    559     outp = outpacket_buf;
    560 
    561     MAKEHEADER(outp, PPP_PAP);
    562 
    563     PUTCHAR(UPAP_AUTHREQ, outp);
    564     PUTCHAR(++u->us_id, outp);
    565     PUTSHORT(outlen, outp);
    566     PUTCHAR(u->us_userlen, outp);
    567     BCOPY(u->us_user, outp, u->us_userlen);
    568     INCPTR(u->us_userlen, outp);
    569     PUTCHAR(u->us_passwdlen, outp);
    570     BCOPY(u->us_passwd, outp, u->us_passwdlen);
    571 
    572     output(u->us_unit, outpacket_buf, outlen + PPP_HDRLEN);
    573 
    574     TIMEOUT(upap_timeout, u, u->us_timeouttime);
    575     ++u->us_transmits;
    576     u->us_clientstate = UPAPCS_AUTHREQ;
    577 }
    578 
    579 
    580 /*
    581  * upap_sresp - Send a response (ack or nak).
    582  */
    583 static void
    584 upap_sresp(u, code, id, msg, msglen)
    585     upap_state *u;
    586     u_char code, id;
    587     char *msg;
    588     int msglen;
    589 {
    590     u_char *outp;
    591     int outlen;
    592 
    593     outlen = UPAP_HEADERLEN + sizeof (u_char) + msglen;
    594     outp = outpacket_buf;
    595     MAKEHEADER(outp, PPP_PAP);
    596 
    597     PUTCHAR(code, outp);
    598     PUTCHAR(id, outp);
    599     PUTSHORT(outlen, outp);
    600     PUTCHAR(msglen, outp);
    601     BCOPY(msg, outp, msglen);
    602     output(u->us_unit, outpacket_buf, outlen + PPP_HDRLEN);
    603 }
    604 
    605 /*
    606  * upap_printpkt - print the contents of a PAP packet.
    607  */
    608 static char *upap_codenames[] = {
    609     "AuthReq", "AuthAck", "AuthNak"
    610 };
    611 
    612 static int
    613 upap_printpkt(p, plen, printer, arg)
    614     u_char *p;
    615     int plen;
    616     void (*printer) __P((void *, char *, ...));
    617     void *arg;
    618 {
    619     int code, id, len;
    620     int mlen, ulen, wlen;
    621     char *user, *pwd, *msg;
    622     u_char *pstart;
    623 
    624     if (plen < UPAP_HEADERLEN)
    625 	return 0;
    626     pstart = p;
    627     GETCHAR(code, p);
    628     GETCHAR(id, p);
    629     GETSHORT(len, p);
    630     if (len < UPAP_HEADERLEN || len > plen)
    631 	return 0;
    632 
    633     if (code >= 1 && code <= sizeof(upap_codenames) / sizeof(char *))
    634 	printer(arg, " %s", upap_codenames[code-1]);
    635     else
    636 	printer(arg, " code=0x%x", code);
    637     printer(arg, " id=0x%x", id);
    638     len -= UPAP_HEADERLEN;
    639     switch (code) {
    640     case UPAP_AUTHREQ:
    641 	if (len < 1)
    642 	    break;
    643 	ulen = p[0];
    644 	if (len < ulen + 2)
    645 	    break;
    646 	wlen = p[ulen + 1];
    647 	if (len < ulen + wlen + 2)
    648 	    break;
    649 	user = (char *) (p + 1);
    650 	pwd = (char *) (p + ulen + 2);
    651 	p += ulen + wlen + 2;
    652 	len -= ulen + wlen + 2;
    653 	printer(arg, " user=");
    654 	print_string(user, ulen, printer, arg);
    655 	printer(arg, " password=");
    656 	if (!hide_password)
    657 	    print_string(pwd, wlen, printer, arg);
    658 	else
    659 	    printer(arg, "<hidden>");
    660 	break;
    661     case UPAP_AUTHACK:
    662     case UPAP_AUTHNAK:
    663 	if (len < 1)
    664 	    break;
    665 	mlen = p[0];
    666 	if (len < mlen + 1)
    667 	    break;
    668 	msg = (char *) (p + 1);
    669 	p += mlen + 1;
    670 	len -= mlen + 1;
    671 	printer(arg, " ");
    672 	print_string(msg, mlen, printer, arg);
    673 	break;
    674     }
    675 
    676     /* print the rest of the bytes in the packet */
    677     for (; len > 0; --len) {
    678 	GETCHAR(code, p);
    679 	printer(arg, " %.2x", code);
    680     }
    681 
    682     return p - pstart;
    683 }
    684