2 * chap-new.c - New CHAP implementation.
4 * Copyright (c) 2003 Paul Mackerras. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
13 * 2. The name(s) of the authors of this software must not be used to
14 * endorse or promote products derived from this software without
15 * prior written permission.
17 * 3. Redistributions of any form whatsoever must retain the following
19 * "This product includes software developed by Paul Mackerras
20 * <paulus@samba.org>".
22 * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
23 * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
24 * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
25 * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
26 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
27 * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
28 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
31 #define RCSID "$Id: chap-new.c,v 1.9 2007/06/19 02:08:35 carlsonj Exp $"
42 #define MDTYPE_ALL (MDTYPE_MICROSOFT_V2 | MDTYPE_MICROSOFT | MDTYPE_MD5)
44 #define MDTYPE_ALL (MDTYPE_MD5)
47 int chap_mdtype_all = MDTYPE_ALL;
49 /* Hook for a plugin to validate CHAP challenge */
50 int (*chap_verify_hook)(char *name, char *ourname, int id,
51 struct chap_digest_type *digest,
52 unsigned char *challenge, unsigned char *response,
53 char *message, int message_space) = NULL;
58 int chap_timeout_time = 3;
59 int chap_max_transmits = 10;
60 int chap_rechallenge_time = 0;
63 * Command-line options.
65 static option_t chap_option_list[] = {
66 { "chap-restart", o_int, &chap_timeout_time,
67 "Set timeout for CHAP", OPT_PRIO },
68 { "chap-max-challenge", o_int, &chap_max_transmits,
69 "Set max #xmits for challenge", OPT_PRIO },
70 { "chap-interval", o_int, &chap_rechallenge_time,
71 "Set interval for rechallenge", OPT_PRIO },
78 static struct chap_client_state {
81 struct chap_digest_type *digest;
82 unsigned char priv[64]; /* private area for digest's use */
86 * These limits apply to challenge and response packets we send.
87 * The +4 is the +1 that we actually need rounded up.
89 #define CHAL_MAX_PKTLEN (PPP_HDRLEN + CHAP_HDRLEN + 4 + MAX_CHALLENGE_LEN + MAXNAMELEN)
90 #define RESP_MAX_PKTLEN (PPP_HDRLEN + CHAP_HDRLEN + 4 + MAX_RESPONSE_LEN + MAXNAMELEN)
92 static struct chap_server_state {
96 struct chap_digest_type *digest;
99 unsigned char challenge[CHAL_MAX_PKTLEN];
103 /* Values for flags in chap_client_state and chap_server_state */
105 #define AUTH_STARTED 2
107 #define AUTH_FAILED 8
108 #define TIMEOUT_PENDING 0x10
109 #define CHALLENGE_VALID 0x20
114 static void chap_init(int unit);
115 static void chap_lowerup(int unit);
116 static void chap_lowerdown(int unit);
117 static void chap_timeout(void *arg);
118 static void chap_generate_challenge(struct chap_server_state *ss);
119 static void chap_handle_response(struct chap_server_state *ss, int code,
120 unsigned char *pkt, int len);
121 static int chap_verify_response(char *name, char *ourname, int id,
122 struct chap_digest_type *digest,
123 unsigned char *challenge, unsigned char *response,
124 char *message, int message_space);
125 static void chap_respond(struct chap_client_state *cs, int id,
126 unsigned char *pkt, int len);
127 static void chap_handle_status(struct chap_client_state *cs, int code, int id,
128 unsigned char *pkt, int len);
129 static void chap_protrej(int unit);
130 static void chap_input(int unit, unsigned char *pkt, int pktlen);
131 static int chap_print_pkt(unsigned char *p, int plen,
132 void (*printer) __P((void *, char *, ...)), void *arg);
134 /* List of digest types that we know about */
135 static struct chap_digest_type *chap_digests;
138 * chap_init - reset to initial state.
143 memset(&client, 0, sizeof(client));
144 memset(&server, 0, sizeof(server));
153 * Add a new digest type to the list.
156 chap_register_digest(struct chap_digest_type *dp)
158 dp->next = chap_digests;
163 * chap_lowerup - we can start doing stuff now.
166 chap_lowerup(int unit)
168 struct chap_client_state *cs = &client;
169 struct chap_server_state *ss = &server;
171 cs->flags |= LOWERUP;
172 ss->flags |= LOWERUP;
173 if (ss->flags & AUTH_STARTED)
178 chap_lowerdown(int unit)
180 struct chap_client_state *cs = &client;
181 struct chap_server_state *ss = &server;
184 if (ss->flags & TIMEOUT_PENDING)
185 UNTIMEOUT(chap_timeout, ss);
190 * chap_auth_peer - Start authenticating the peer.
191 * If the lower layer is already up, we start sending challenges,
192 * otherwise we wait for the lower layer to come up.
195 chap_auth_peer(int unit, char *our_name, int digest_code)
197 struct chap_server_state *ss = &server;
198 struct chap_digest_type *dp;
200 if (ss->flags & AUTH_STARTED) {
201 error("CHAP: peer authentication already started!");
204 for (dp = chap_digests; dp != NULL; dp = dp->next)
205 if (dp->code == digest_code)
208 fatal("CHAP digest 0x%x requested but not available",
213 /* Start with a random ID value */
214 ss->id = (unsigned char)(drand48() * 256);
215 ss->flags |= AUTH_STARTED;
216 if (ss->flags & LOWERUP)
221 * chap_auth_with_peer - Prepare to authenticate ourselves to the peer.
222 * There isn't much to do until we receive a challenge.
225 chap_auth_with_peer(int unit, char *our_name, int digest_code)
227 struct chap_client_state *cs = &client;
228 struct chap_digest_type *dp;
230 if (cs->flags & AUTH_STARTED) {
231 error("CHAP: authentication with peer already started!");
234 for (dp = chap_digests; dp != NULL; dp = dp->next)
235 if (dp->code == digest_code)
238 fatal("CHAP digest 0x%x requested but not available",
243 cs->flags |= AUTH_STARTED;
247 * chap_timeout - It's time to send another challenge to the peer.
248 * This could be either a retransmission of a previous challenge,
249 * or a new challenge to start re-authentication.
252 chap_timeout(void *arg)
254 struct chap_server_state *ss = arg;
256 ss->flags &= ~TIMEOUT_PENDING;
257 if ((ss->flags & CHALLENGE_VALID) == 0) {
258 ss->challenge_xmits = 0;
259 chap_generate_challenge(ss);
260 ss->flags |= CHALLENGE_VALID;
261 } else if (ss->challenge_xmits >= chap_max_transmits) {
262 ss->flags &= ~CHALLENGE_VALID;
263 ss->flags |= AUTH_DONE | AUTH_FAILED;
264 auth_peer_fail(0, PPP_CHAP);
268 output(0, ss->challenge, ss->challenge_pktlen);
269 ++ss->challenge_xmits;
270 ss->flags |= TIMEOUT_PENDING;
271 TIMEOUT(chap_timeout, arg, chap_timeout_time);
275 * chap_generate_challenge - generate a challenge string and format
276 * the challenge packet in ss->challenge_pkt.
279 chap_generate_challenge(struct chap_server_state *ss)
281 int clen = 1, nlen, len;
285 MAKEHEADER(p, PPP_CHAP);
287 ss->digest->generate_challenge(p);
289 nlen = strlen(ss->name);
290 memcpy(p + 1 + clen, ss->name, nlen);
292 len = CHAP_HDRLEN + 1 + clen + nlen;
293 ss->challenge_pktlen = PPP_HDRLEN + len;
295 p = ss->challenge + PPP_HDRLEN;
296 p[0] = CHAP_CHALLENGE;
303 * chap_handle_response - check the response to our challenge.
306 chap_handle_response(struct chap_server_state *ss, int id,
307 unsigned char *pkt, int len)
309 int response_len, ok, mlen;
310 unsigned char *response, *p;
311 char *name = NULL; /* initialized to shut gcc up */
312 int (*verifier)(char *, char *, int, struct chap_digest_type *,
313 unsigned char *, unsigned char *, char *, int);
314 char rname[MAXNAMELEN+1];
316 if ((ss->flags & LOWERUP) == 0)
318 if (id != ss->challenge[PPP_HDRLEN+1] || len < 2)
320 if (ss->flags & CHALLENGE_VALID) {
322 GETCHAR(response_len, pkt);
323 len -= response_len + 1; /* length of name */
324 name = (char *)pkt + response_len;
328 if (ss->flags & TIMEOUT_PENDING) {
329 ss->flags &= ~TIMEOUT_PENDING;
330 UNTIMEOUT(chap_timeout, ss);
333 if (explicit_remote) {
336 /* Null terminate and clean remote name. */
337 slprintf(rname, sizeof(rname), "%.*v", len, name);
341 if (chap_verify_hook)
342 verifier = chap_verify_hook;
344 verifier = chap_verify_response;
345 ok = (*verifier)(name, ss->name, id, ss->digest,
346 ss->challenge + PPP_HDRLEN + CHAP_HDRLEN,
347 response, ss->message, sizeof(ss->message));
348 if (!ok || !auth_number()) {
349 ss->flags |= AUTH_FAILED;
350 warn("Peer %q failed CHAP authentication", name);
352 } else if ((ss->flags & AUTH_DONE) == 0)
355 /* send the response */
357 MAKEHEADER(p, PPP_CHAP);
358 mlen = strlen(ss->message);
359 len = CHAP_HDRLEN + mlen;
360 p[0] = (ss->flags & AUTH_FAILED)? CHAP_FAILURE: CHAP_SUCCESS;
365 memcpy(p + CHAP_HDRLEN, ss->message, mlen);
366 output(0, outpacket_buf, PPP_HDRLEN + len);
368 if (ss->flags & CHALLENGE_VALID) {
369 ss->flags &= ~CHALLENGE_VALID;
370 if (!(ss->flags & AUTH_DONE) && !(ss->flags & AUTH_FAILED)) {
372 * Auth is OK, so now we need to check session restrictions
373 * to ensure everything is OK, but only if we used a
374 * plugin, and only if we're configured to check. This
375 * allows us to do PAM checks on PPP servers that
376 * authenticate against ActiveDirectory, and use AD for
377 * account info (like when using Winbind integrated with
381 session_check(name, NULL, devnam, NULL) == 0) {
382 ss->flags |= AUTH_FAILED;
383 warn("Peer %q failed CHAP Session verification", name);
386 if (ss->flags & AUTH_FAILED) {
387 auth_peer_fail(0, PPP_CHAP);
389 if ((ss->flags & AUTH_DONE) == 0)
390 auth_peer_success(0, PPP_CHAP,
393 if (chap_rechallenge_time) {
394 ss->flags |= TIMEOUT_PENDING;
395 TIMEOUT(chap_timeout, ss,
396 chap_rechallenge_time);
399 ss->flags |= AUTH_DONE;
404 * chap_verify_response - check whether the peer's response matches
405 * what we think it should be. Returns 1 if it does (authentication
406 * succeeded), or 0 if it doesn't.
409 chap_verify_response(char *name, char *ourname, int id,
410 struct chap_digest_type *digest,
411 unsigned char *challenge, unsigned char *response,
412 char *message, int message_space)
415 unsigned char secret[MAXSECRETLEN];
418 /* Get the secret that the peer is supposed to know */
419 if (!get_secret(0, name, ourname, (char *)secret, &secret_len, 1)) {
420 error("No CHAP secret found for authenticating %q", name);
424 ok = digest->verify_response(id, name, secret, secret_len, challenge,
425 response, message, message_space);
426 memset(secret, 0, sizeof(secret));
432 * chap_respond - Generate and send a response to a challenge.
435 chap_respond(struct chap_client_state *cs, int id,
436 unsigned char *pkt, int len)
441 unsigned char response[RESP_MAX_PKTLEN];
442 char rname[MAXNAMELEN+1];
443 char secret[MAXSECRETLEN+1];
445 if ((cs->flags & (LOWERUP | AUTH_STARTED)) != (LOWERUP | AUTH_STARTED))
446 return; /* not ready */
447 if (len < 2 || len < pkt[0] + 1)
448 return; /* too short */
450 nlen = len - (clen + 1);
452 /* Null terminate and clean remote name. */
453 slprintf(rname, sizeof(rname), "%.*v", nlen, pkt + clen + 1);
455 /* Microsoft doesn't send their name back in the PPP packet */
456 if (explicit_remote || (remote_name[0] != 0 && rname[0] == 0))
457 strlcpy(rname, remote_name, sizeof(rname));
459 /* get secret for authenticating ourselves with the specified host */
460 if (!get_secret(0, cs->name, rname, secret, &secret_len, 0)) {
461 secret_len = 0; /* assume null secret if can't find one */
462 warn("No CHAP secret found for authenticating us to %q", rname);
466 MAKEHEADER(p, PPP_CHAP);
469 cs->digest->make_response(p, id, cs->name, pkt,
470 secret, secret_len, cs->priv);
471 memset(secret, 0, secret_len);
474 nlen = strlen(cs->name);
475 memcpy(p + clen + 1, cs->name, nlen);
477 p = response + PPP_HDRLEN;
478 len = CHAP_HDRLEN + clen + 1 + nlen;
479 p[0] = CHAP_RESPONSE;
484 output(0, response, PPP_HDRLEN + len);
488 chap_handle_status(struct chap_client_state *cs, int code, int id,
489 unsigned char *pkt, int len)
491 const char *msg = NULL;
493 if ((cs->flags & (AUTH_DONE|AUTH_STARTED|LOWERUP))
494 != (AUTH_STARTED|LOWERUP))
496 cs->flags |= AUTH_DONE;
498 if (code == CHAP_SUCCESS) {
499 /* used for MS-CHAP v2 mutual auth, yuck */
500 if (cs->digest->check_success != NULL) {
501 if (!(*cs->digest->check_success)(id, pkt, len))
504 msg = "CHAP authentication succeeded";
506 if (cs->digest->handle_failure != NULL)
507 (*cs->digest->handle_failure)(pkt, len);
509 msg = "CHAP authentication failed";
513 info("%s: %.*v", msg, len, pkt);
517 if (code == CHAP_SUCCESS)
518 auth_withpeer_success(0, PPP_CHAP, cs->digest->code);
520 cs->flags |= AUTH_FAILED;
521 error("CHAP authentication failed");
522 auth_withpeer_fail(0, PPP_CHAP);
527 chap_input(int unit, unsigned char *pkt, int pktlen)
529 struct chap_client_state *cs = &client;
530 struct chap_server_state *ss = &server;
531 unsigned char code, id;
534 if (pktlen < CHAP_HDRLEN)
539 if (len < CHAP_HDRLEN || len > pktlen)
545 chap_respond(cs, id, pkt, len);
548 chap_handle_response(ss, id, pkt, len);
552 chap_handle_status(cs, code, id, pkt, len);
558 chap_protrej(int unit)
560 struct chap_client_state *cs = &client;
561 struct chap_server_state *ss = &server;
563 if (ss->flags & TIMEOUT_PENDING) {
564 ss->flags &= ~TIMEOUT_PENDING;
565 UNTIMEOUT(chap_timeout, ss);
567 if (ss->flags & AUTH_STARTED) {
569 auth_peer_fail(0, PPP_CHAP);
571 if ((cs->flags & (AUTH_STARTED|AUTH_DONE)) == AUTH_STARTED) {
572 cs->flags &= ~AUTH_STARTED;
573 error("CHAP authentication failed due to protocol-reject");
574 auth_withpeer_fail(0, PPP_CHAP);
579 * chap_print_pkt - print the contents of a CHAP packet.
581 static char *chap_code_names[] = {
582 "Challenge", "Response", "Success", "Failure"
586 chap_print_pkt(unsigned char *p, int plen,
587 void (*printer) __P((void *, char *, ...)), void *arg)
593 if (plen < CHAP_HDRLEN)
598 if (len < CHAP_HDRLEN || len > plen)
601 if (code >= 1 && code <= sizeof(chap_code_names) / sizeof(char *))
602 printer(arg, " %s", chap_code_names[code-1]);
604 printer(arg, " code=0x%x", code);
605 printer(arg, " id=0x%x", id);
616 nlen = len - clen - 1;
618 for (; clen > 0; --clen) {
620 printer(arg, "%.2x", x);
622 printer(arg, ">, name = ");
623 print_string((char *)p, nlen, printer, arg);
628 print_string((char *)p, len, printer, arg);
631 for (clen = len; clen > 0; --clen) {
633 printer(arg, " %.2x", x);
637 return len + CHAP_HDRLEN;
640 struct protent chap_protent = {
650 NULL, /* datainput */
651 1, /* enabled_flag */
653 NULL, /* data_name */
655 NULL, /* check_options */