chap.c revision 37926 
1/*
2 *			PPP CHAP Module
3 *
4 *	    Written by Toshiharu OHNO (tony-o@iij.ad.jp)
5 *
6 *   Copyright (C) 1993, Internet Initiative Japan, Inc. All rights reserverd.
7 *
8 * Redistribution and use in source and binary forms are permitted
9 * provided that the above copyright notice and this paragraph are
10 * duplicated in all such forms and that any documentation,
11 * advertising materials, and other materials related to such
12 * distribution and use acknowledge that the software was developed
13 * by the Internet Initiative Japan, Inc.  The name of the
14 * IIJ may not be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
18 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
19 *
20 * $Id: chap.c,v 1.34 1998/06/27 23:48:41 brian Exp $
21 *
22 *	TODO:
23 */
24#include <sys/types.h>
25#include <netinet/in.h>
26#include <netinet/in_systm.h>
27#include <netinet/ip.h>
28#include <sys/un.h>
29
30#ifdef HAVE_DES
31#include <md4.h>
32#endif
33#include <md5.h>
34#include <stdlib.h>
35#include <string.h>
36#include <termios.h>
37
38#include "mbuf.h"
39#include "log.h"
40#include "defs.h"
41#include "timer.h"
42#include "fsm.h"
43#include "lcpproto.h"
44#include "lcp.h"
45#include "lqr.h"
46#include "hdlc.h"
47#include "auth.h"
48#include "chap.h"
49#include "async.h"
50#include "throughput.h"
51#include "descriptor.h"
52#include "iplist.h"
53#include "slcompress.h"
54#include "ipcp.h"
55#include "filter.h"
56#include "ccp.h"
57#include "link.h"
58#include "physical.h"
59#include "mp.h"
60#include "bundle.h"
61#include "chat.h"
62#include "datalink.h"
63#ifdef HAVE_DES
64#include "chap_ms.h"
65#endif
66
67static const char *chapcodes[] = {
68  "???", "CHALLENGE", "RESPONSE", "SUCCESS", "FAILURE"
69};
70
71static void
72ChapOutput(struct physical *physical, u_int code, u_int id,
73	   const u_char * ptr, int count, const char *text)
74{
75  int plen;
76  struct fsmheader lh;
77  struct mbuf *bp;
78
79  plen = sizeof(struct fsmheader) + count;
80  lh.code = code;
81  lh.id = id;
82  lh.length = htons(plen);
83  bp = mbuf_Alloc(plen, MB_FSM);
84  memcpy(MBUF_CTOP(bp), &lh, sizeof(struct fsmheader));
85  if (count)
86    memcpy(MBUF_CTOP(bp) + sizeof(struct fsmheader), ptr, count);
87  log_DumpBp(LogDEBUG, "ChapOutput", bp);
88  if (text == NULL)
89    log_Printf(LogPHASE, "Chap Output: %s\n", chapcodes[code]);
90  else
91    log_Printf(LogPHASE, "Chap Output: %s (%s)\n", chapcodes[code], text);
92  hdlc_Output(&physical->link, PRI_LINK, PROTO_CHAP, bp);
93}
94
95void
96chap_SendChallenge(struct authinfo *auth, int chapid, struct physical *physical)
97{
98  struct chap *chap = auth2chap(auth);
99  int len, i;
100  char *cp;
101
102  randinit();
103  cp = chap->challenge_data;
104  *cp++ = chap->challenge_len = random() % 32 + 16;
105  for (i = 0; i < chap->challenge_len; i++)
106    *cp++ = random() & 0xff;
107  len = strlen(physical->dl->bundle->cfg.auth.name);
108  memcpy(cp, physical->dl->bundle->cfg.auth.name, len);
109  cp += len;
110  ChapOutput(physical, CHAP_CHALLENGE, chapid, chap->challenge_data,
111	     cp - chap->challenge_data, NULL);
112}
113
114static void
115RecvChapTalk(struct bundle *bundle, struct fsmheader *chp, struct mbuf *bp,
116             struct physical *physical)
117{
118  int valsize, len;
119  int arglen, keylen, namelen;
120  char *cp, *argp, *ap, *name, *digest;
121  char *keyp;
122  MD5_CTX MD5context;		/* context for MD5 */
123  char answer[100];
124  char cdigest[16];
125#ifdef HAVE_DES
126  int ix;
127  MD4_CTX MD4context;		/* context for MD4 */
128#endif
129
130  len = ntohs(chp->length);
131  log_Printf(LogDEBUG, "RecvChapTalk: length: %d\n", len);
132  arglen = len - sizeof(struct fsmheader);
133  cp = (char *) MBUF_CTOP(bp);
134  valsize = *cp++ & 255;
135  name = cp + valsize;
136  namelen = arglen - valsize - 1;
137  name[namelen] = 0;
138
139  log_Printf(LogPHASE, "Chap Input: %s (from %s)\n",
140             chapcodes[chp->code], name);
141
142  switch (chp->code) {
143  case CHAP_CHALLENGE:
144    keyp = bundle->cfg.auth.key;
145    keylen = strlen(bundle->cfg.auth.key);
146    name = bundle->cfg.auth.name;
147    namelen = strlen(bundle->cfg.auth.name);
148
149#ifdef HAVE_DES
150    if (physical->dl->chap.using_MSChap)
151      argp = malloc(1 + namelen + MS_CHAP_RESPONSE_LEN);
152    else
153#endif
154      argp = malloc(1 + valsize + namelen + 16);
155
156    if (argp == NULL) {
157      ChapOutput(physical, CHAP_FAILURE, chp->id, "Out of memory!", 14, NULL);
158      return;
159    }
160#ifdef HAVE_DES
161    if (physical->dl->chap.using_MSChap) {
162      digest = argp;     /* this is the response */
163      *digest++ = MS_CHAP_RESPONSE_LEN;   /* 49 */
164      memset(digest, '\0', 24);
165      digest += 24;
166
167      ap = answer;       /* this is the challenge */
168      memcpy(ap, keyp, keylen);
169      ap += 2 * keylen;
170      memcpy(ap, cp, valsize);
171      log_DumpBuff(LogDEBUG, "recv", ap, valsize);
172      ap += valsize;
173      for (ix = keylen; ix > 0 ; ix--) {
174          answer[2*ix-2] = answer[ix-1];
175          answer[2*ix-1] = 0;
176      }
177      MD4Init(&MD4context);
178      MD4Update(&MD4context, answer, 2 * keylen);
179      MD4Final(digest, &MD4context);
180      memcpy(digest + 25, name, namelen);
181      ap += 2 * keylen;
182      chap_MS(digest, answer + 2 * keylen, valsize);
183      log_DumpBuff(LogDEBUG, "answer", digest, 24);
184      ChapOutput(physical, CHAP_RESPONSE, chp->id, argp,
185		 namelen + MS_CHAP_RESPONSE_LEN + 1, name);
186    } else {
187#endif
188      digest = argp;
189      *digest++ = 16;		/* value size */
190      ap = answer;
191      *ap++ = chp->id;
192      memcpy(ap, keyp, keylen);
193      ap += keylen;
194      memcpy(ap, cp, valsize);
195      log_DumpBuff(LogDEBUG, "recv", ap, valsize);
196      ap += valsize;
197      MD5Init(&MD5context);
198      MD5Update(&MD5context, answer, ap - answer);
199      MD5Final(digest, &MD5context);
200      log_DumpBuff(LogDEBUG, "answer", digest, 16);
201      memcpy(digest + 16, name, namelen);
202      ap += namelen;
203      /* Send answer to the peer */
204      ChapOutput(physical, CHAP_RESPONSE, chp->id, argp, namelen + 17, name);
205#ifdef HAVE_DES
206    }
207#endif
208    free(argp);
209    if (*name == '\0')
210      log_Printf(LogWARN, "Sending empty CHAP authname!\n");
211    break;
212  case CHAP_RESPONSE:
213    /*
214     * Get a secret key corresponds to the peer
215     */
216    keyp = auth_GetSecret(bundle, name, namelen, physical);
217    if (keyp) {
218      /*
219       * Compute correct digest value
220       */
221      keylen = strlen(keyp);
222      ap = answer;
223      *ap++ = chp->id;
224      memcpy(ap, keyp, keylen);
225      ap += keylen;
226      MD5Init(&MD5context);
227      MD5Update(&MD5context, answer, ap - answer);
228      MD5Update(&MD5context, physical->dl->chap.challenge_data + 1,
229                physical->dl->chap.challenge_len);
230      MD5Final(cdigest, &MD5context);
231      log_DumpBuff(LogDEBUG, "got", cp, 16);
232      log_DumpBuff(LogDEBUG, "expect", cdigest, 16);
233
234      /*
235       * Compare with the response
236       */
237      if (memcmp(cp, cdigest, 16) == 0) {
238        datalink_GotAuthname(physical->dl, name, namelen);
239	ChapOutput(physical, CHAP_SUCCESS, chp->id, "Welcome!!", 10, NULL);
240	physical->link.lcp.auth_ineed = 0;
241        if (Enabled(bundle, OPT_UTMP))
242          physical_Login(physical, name);
243
244        if (physical->link.lcp.auth_iwait == 0)
245          /*
246           * Either I didn't need to authenticate, or I've already been
247           * told that I got the answer right.
248           */
249          datalink_AuthOk(physical->dl);
250
251	break;
252      }
253    }
254
255    /*
256     * Peer is not registerd, or response digest is wrong.
257     */
258    ChapOutput(physical, CHAP_FAILURE, chp->id, "Invalid!!", 9, NULL);
259    datalink_AuthNotOk(physical->dl);
260    break;
261  }
262}
263
264static void
265RecvChapResult(struct bundle *bundle, struct fsmheader *chp, struct mbuf *bp,
266	       struct physical *physical)
267{
268  int len;
269
270  len = ntohs(chp->length);
271  log_Printf(LogDEBUG, "RecvChapResult: length: %d\n", len);
272  if (chp->code == CHAP_SUCCESS) {
273    if (physical->link.lcp.auth_iwait == PROTO_CHAP) {
274      physical->link.lcp.auth_iwait = 0;
275      if (physical->link.lcp.auth_ineed == 0)
276        /*
277         * We've succeeded in our ``login''
278         * If we're not expecting  the peer to authenticate (or he already
279         * has), proceed to network phase.
280         */
281        datalink_AuthOk(physical->dl);
282    }
283  } else {
284    /* CHAP failed - it's not going to get any better */
285    log_Printf(LogPHASE, "Chap Input: Giving up after name/key FAILURE\n");
286    datalink_AuthNotOk(physical->dl);
287  }
288}
289
290void
291chap_Input(struct bundle *bundle, struct mbuf *bp, struct physical *physical)
292{
293  int len = mbuf_Length(bp);
294  struct fsmheader *chp;
295
296  if (len >= sizeof(struct fsmheader)) {
297    chp = (struct fsmheader *) MBUF_CTOP(bp);
298    if (len >= ntohs(chp->length)) {
299      if (chp->code < 1 || chp->code > 4)
300	chp->code = 0;
301      bp->offset += sizeof(struct fsmheader);
302      bp->cnt -= sizeof(struct fsmheader);
303
304      switch (chp->code) {
305      case CHAP_RESPONSE:
306	auth_StopTimer(&physical->dl->chap.auth);
307	/* Fall into.. */
308      case CHAP_CHALLENGE:
309	RecvChapTalk(bundle, chp, bp, physical);
310	break;
311      case CHAP_SUCCESS:
312      case CHAP_FAILURE:
313        log_Printf(LogPHASE, "Chap Input: %s\n", chapcodes[chp->code]);
314	RecvChapResult(bundle, chp, bp, physical);
315	break;
316      }
317    }
318  }
319  mbuf_Free(bp);
320}
321