/*
- * chap.c - Challenge Handshake Authentication Protocol.
+ * chap_ms.c - Challenge Handshake Authentication Protocol.
*
* Copyright (c) 1993 The Australian National University.
* All rights reserved.
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
-#define RCSID "$Id: chap.c,v 1.24 1999/11/15 01:51:50 paulus Exp $"
+#define RCSID "$Id: chap.c,v 1.36 2002/10/12 02:30:21 fcusack Exp $"
/*
* TODO:
*/
#include <stdio.h>
+#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/time.h>
#include "chap_ms.h"
#endif
+/* Hook for a plugin to say if we can possibly authenticate a peer using CHAP */
+int (*chap_check_hook) __P((void)) = NULL;
+
+/* Hook for a plugin to get the CHAP password for authenticating us */
+int (*chap_passwd_hook) __P((char *user, char *passwd)) = NULL;
+
+/* Hook for a plugin to validate CHAP challenge */
+int (*chap_auth_hook) __P((char *user,
+ u_char *remmd,
+ int remmd_len,
+ chap_state *cstate)) = NULL;
+
static const char rcsid[] = RCSID;
+#ifdef CHAPMS
+/* For MPPE debug */
+/* Use "[]|}{?/><,`!2&&(" (sans quotes) for RFC 3079 MS-CHAPv2 test value */
+static char *mschap_challenge = NULL;
+/* Use "!@\#$%^&*()_+:3|~" (sans quotes, backslash is to escape #) for ... */
+static char *mschap2_peer_challenge = NULL;
+#endif
+
/*
* Command-line options.
*/
static option_t chap_option_list[] = {
{ "chap-restart", o_int, &chap[0].timeouttime,
- "Set timeout for CHAP" },
+ "Set timeout for CHAP", OPT_PRIO },
{ "chap-max-challenge", o_int, &chap[0].max_transmits,
- "Set max #xmits for challenge" },
+ "Set max #xmits for challenge", OPT_PRIO },
{ "chap-interval", o_int, &chap[0].chal_interval,
- "Set interval for rechallenge" },
+ "Set interval for rechallenge", OPT_PRIO },
#ifdef MSLANMAN
{ "ms-lanman", o_bool, &ms_lanman,
"Use LanMan passwd when using MS-CHAP", 1 },
+#endif
+#ifdef DEBUGMPPEKEY
+ { "mschap-challenge", o_string, &mschap_challenge,
+ "specify CHAP challenge" },
+ { "mschap2-peer-challenge", o_string, &mschap2_peer_challenge,
+ "specify CHAP peer challenge" },
#endif
{ NULL }
};
/*
* We get here as a result of LCP coming up.
- * So even if CHAP was open before, we will
+ * So even if CHAP was open before, we will
* have to re-authenticate ourselves.
*/
cstate->clientstate = CHAPCS_LISTEN;
int digest;
{
chap_state *cstate = &chap[unit];
-
+
cstate->chal_name = our_name;
cstate->chal_type = digest;
void *arg;
{
chap_state *cstate = (chap_state *) arg;
-
+
/* if we aren't sending challenges, don't worry. then again we */
/* probably shouldn't be here either */
if (cstate->serverstate != CHAPSS_INITIAL_CHAL &&
int unit;
{
chap_state *cstate = &chap[unit];
-
+
if (cstate->clientstate == CHAPCS_INITIAL)
cstate->clientstate = CHAPCS_CLOSED;
else if (cstate->clientstate == CHAPCS_PENDING)
int unit;
{
chap_state *cstate = &chap[unit];
-
+
/* Timeout(s) pending? Cancel if so. */
if (cstate->serverstate == CHAPSS_INITIAL_CHAL ||
cstate->serverstate == CHAPSS_RECHALLENGE)
u_char *inp;
u_char code, id;
int len;
-
+
/*
* Parse header (code, id and length).
* If packet too short, drop it.
return;
}
len -= CHAP_HEADERLEN;
-
+
/*
* Action depends on code (as in fact it usually does :-).
*/
case CHAP_CHALLENGE:
ChapReceiveChallenge(cstate, inp, id, len);
break;
-
+
case CHAP_RESPONSE:
ChapReceiveResponse(cstate, inp, id, len);
break;
-
+
case CHAP_FAILURE:
ChapReceiveFailure(cstate, inp, id, len);
break;
char rhostname[256];
MD5_CTX mdContext;
u_char hash[MD5_SIGNATURE_SIZE];
-
+
if (cstate->clientstate == CHAPCS_CLOSED ||
cstate->clientstate == CHAPCS_PENDING) {
CHAPDEBUG(("ChapReceiveChallenge: in state %d", cstate->clientstate));
rchallenge = inp;
INCPTR(rchallenge_len, inp);
- if (len >= sizeof(rhostname))
- len = sizeof(rhostname) - 1;
- BCOPY(inp, rhostname, len);
- rhostname[len] = '\000';
+ /* Null terminate and clean remote name. */
+ slprintf(rhostname, sizeof(rhostname), "%.*v", len, inp);
/* Microsoft doesn't send their name back in the PPP packet */
if (explicit_remote || (remote_name[0] != 0 && rhostname[0] == 0)) {
cstate->resp_transmits = 0;
/* generate MD based on negotiated type */
- switch (cstate->resp_type) {
+ switch (cstate->resp_type) {
case CHAP_DIGEST_MD5:
MD5Init(&mdContext);
#ifdef CHAPMS
case CHAP_MICROSOFT:
- ChapMS(cstate, rchallenge, rchallenge_len, secret, secret_len);
+ ChapMS(cstate, rchallenge, secret, secret_len,
+ (MS_ChapResponse *) cstate->response);
break;
-#endif
+
+ case CHAP_MICROSOFT_V2:
+ ChapMS2(cstate, rchallenge,
+ mschap2_peer_challenge? mschap2_peer_challenge: NULL,
+ cstate->resp_name, secret, secret_len,
+ (MS_Chap2Response *) cstate->response, cstate->earesponse,
+ MS_CHAP2_AUTHENTICATEE);
+ break;
+#endif /* CHAPMS */
default:
CHAPDEBUG(("unknown digest type %d", cstate->resp_type));
BCOPY(inp, rhostname, len);
rhostname[len] = '\000';
+#ifdef CHAPMS
+ /* copy the flags into cstate for use elsewhere */
+ if (cstate->chal_type == CHAP_MICROSOFT_V2)
+ cstate->resp_flags = ((MS_Chap2Response *) remmd)->Flags[0];
+#endif /* CHAPMS */
/*
* Get secret for authenticating them with us,
* do the hash ourselves, and compare the result.
*/
code = CHAP_FAILURE;
- if (!get_secret(cstate->unit, (explicit_remote? remote_name: rhostname),
- cstate->chal_name, secret, &secret_len, 1)) {
- warn("No CHAP secret found for authenticating %q", rhostname);
- } else {
- /* generate MD based on negotiated type */
- switch (cstate->chal_type) {
-
- case CHAP_DIGEST_MD5: /* only MD5 is defined for now */
- if (remmd_len != MD5_SIGNATURE_SIZE)
- break; /* it's not even the right length */
- MD5Init(&mdContext);
- MD5Update(&mdContext, &cstate->chal_id, 1);
- MD5Update(&mdContext, secret, secret_len);
- MD5Update(&mdContext, cstate->challenge, cstate->chal_len);
- MD5Final(hash, &mdContext);
-
- /* compare local and remote MDs and send the appropriate status */
- if (memcmp (hash, remmd, MD5_SIGNATURE_SIZE) == 0)
- code = CHAP_SUCCESS; /* they are the same! */
- break;
+ /* If a plugin will verify the response, let the plugin do it. */
+ if (chap_auth_hook) {
+ code = (*chap_auth_hook) ( (explicit_remote ? remote_name : rhostname),
+ remmd, (int) remmd_len,
+ cstate );
+ /*
+ * Check remote number authorization. A plugin may have filled in
+ * the remote number or added an allowed number, and rather than
+ * return an authenticate failure, is leaving it for us to verify.
+ */
+ if (code == CHAP_SUCCESS) {
+ if (!auth_number()) {
+ /* We do not want to leak info about the chap result. */
+ code = CHAP_FAILURE; /* XXX exit value will be "wrong" */
+ warn("calling number %q is not authorized", remote_number);
+ }
+ }
- default:
- CHAPDEBUG(("unknown digest type %d", cstate->chal_type));
+ } else {
+ if (!get_secret(cstate->unit, (explicit_remote? remote_name: rhostname),
+ cstate->chal_name, secret, &secret_len, 1)) {
+ warn("No CHAP secret found for authenticating %q", rhostname);
+ } else {
+
+ /* generate MD based on negotiated type */
+ switch (cstate->chal_type) {
+
+ case CHAP_DIGEST_MD5:
+ if (remmd_len != MD5_SIGNATURE_SIZE)
+ break; /* not even the right length */
+ MD5Init(&mdContext);
+ MD5Update(&mdContext, &cstate->chal_id, 1);
+ MD5Update(&mdContext, secret, secret_len);
+ MD5Update(&mdContext, cstate->challenge, cstate->chal_len);
+ MD5Final(hash, &mdContext);
+
+ /* compare MDs and send the appropriate status */
+ if (memcmp(hash, remmd, MD5_SIGNATURE_SIZE) == 0)
+ code = CHAP_SUCCESS; /* they are the same! */
+ break;
+
+#ifdef CHAPMS
+ case CHAP_MICROSOFT:
+ {
+ int response_offset, response_size;
+ MS_ChapResponse *rmd = (MS_ChapResponse *) remmd;
+ MS_ChapResponse md;
+
+ if (remmd_len != MS_CHAP_RESPONSE_LEN)
+ break; /* not even the right length */
+
+ /* Determine which part of response to verify against */
+ if (rmd->UseNT[0]) {
+ response_offset = offsetof(MS_ChapResponse, NTResp);
+ response_size = sizeof(rmd->NTResp);
+ } else {
+#ifdef MSLANMAN
+ response_offset = offsetof(MS_ChapResponse, LANManResp);
+ response_size = sizeof(rmd->LANManResp);
+#else
+ /* Should really propagate this into the error packet. */
+ notice("Peer request for LANMAN auth not supported");
+ break;
+#endif /* MSLANMAN */
+ }
+
+ /* Generate the expected response. */
+ ChapMS(cstate, cstate->challenge, secret, secret_len, &md);
+
+ /* compare MDs and send the appropriate status */
+ if (memcmp((u_char *) &md + response_offset,
+ (u_char *) remmd + response_offset,
+ response_size) == 0)
+ code = CHAP_SUCCESS; /* they are the same! */
+ break;
+ }
+
+ case CHAP_MICROSOFT_V2:
+ {
+ MS_Chap2Response *rmd = (MS_Chap2Response *) remmd;
+ MS_Chap2Response md;
+
+ if (remmd_len != MS_CHAP2_RESPONSE_LEN)
+ break; /* not even the right length */
+
+ /* Generate the expected response and our mutual auth. */
+ ChapMS2(cstate, cstate->challenge, rmd->PeerChallenge,
+ (explicit_remote? remote_name: rhostname),
+ secret, secret_len, &md,
+ cstate->saresponse, MS_CHAP2_AUTHENTICATOR);
+
+ /* compare MDs and send the appropriate status */
+ if (memcmp(md.NTResp, rmd->NTResp, sizeof(md.NTResp)) == 0)
+ code = CHAP_SUCCESS; /* yay! */
+ break;
+ }
+#endif /* CHAPMS */
+
+ default:
+ CHAPDEBUG(("unknown digest type %d", cstate->chal_type));
+ }
}
- }
- BZERO(secret, sizeof(secret));
+ BZERO(secret, sizeof(secret));
+ }
ChapSendStatus(cstate, code);
if (code == CHAP_SUCCESS) {
old_state = cstate->serverstate;
cstate->serverstate = CHAPSS_OPEN;
if (old_state == CHAPSS_INITIAL_CHAL) {
- auth_peer_success(cstate->unit, PPP_CHAP, rhostname, len);
+ auth_peer_success(cstate->unit, PPP_CHAP, cstate->chal_type,
+ rhostname, len);
}
if (cstate->chal_interval != 0)
TIMEOUT(ChapRechallenge, cstate, cstate->chal_interval);
notice("CHAP peer authentication succeeded for %q", rhostname);
} else {
- error("CHAP peer authentication failed for remote host %q", rhostname);
+ warn("CHAP peer authentication failed for %q", rhostname);
cstate->serverstate = CHAPSS_BADAUTH;
auth_peer_fail(cstate->unit, PPP_CHAP);
}
UNTIMEOUT(ChapResponseTimeout, cstate);
+#ifdef CHAPMS
+ /*
+ * For MS-CHAPv2, we must verify that the peer knows our secret.
+ */
+ if (cstate->resp_type == CHAP_MICROSOFT_V2) {
+ if ((len >= MS_AUTH_RESPONSE_LENGTH + 2) && !strncmp(inp, "S=", 2)) {
+ inp += 2; len -= 2;
+ if (!memcmp(inp, cstate->earesponse, MS_AUTH_RESPONSE_LENGTH)) {
+ /* Authenticator Response matches. */
+ inp += MS_AUTH_RESPONSE_LENGTH; /* Eat it */
+ len -= MS_AUTH_RESPONSE_LENGTH;
+ if ((len >= 3) && !strncmp(inp, " M=", 3)) {
+ inp += 3; len -= 3; /* Eat the delimiter */
+ } else if (len) {
+ /* Packet has extra text which does not begin " M=" */
+ error("MS-CHAPv2 Success packet is badly formed.");
+ auth_withpeer_fail(cstate->unit, PPP_CHAP);
+ }
+ } else {
+ /* Authenticator Response did not match expected. */
+ error("MS-CHAPv2 mutual authentication failed.");
+ auth_withpeer_fail(cstate->unit, PPP_CHAP);
+ }
+ } else {
+ /* Packet does not start with "S=" */
+ error("MS-CHAPv2 Success packet is badly formed.");
+ auth_withpeer_fail(cstate->unit, PPP_CHAP);
+ }
+ }
+#endif
+
/*
* Print message.
*/
cstate->clientstate = CHAPCS_OPEN;
- auth_withpeer_success(cstate->unit, PPP_CHAP);
+ notice("CHAP authentication succeeded");
+ auth_withpeer_success(cstate->unit, PPP_CHAP, cstate->resp_type);
}
u_char id;
int len;
{
+ u_char *msg;
+ u_char *p = inp;
+
if (cstate->clientstate != CHAPCS_RESPONSE) {
/* don't know what this is */
CHAPDEBUG(("ChapReceiveFailure: in state %d\n", cstate->clientstate));
return;
}
+#ifdef CHAPMS
+ /* We want a null-terminated string for strxxx(). */
+ msg = malloc(len + 1);
+ if (!msg) {
+ p = NULL;
+ notice("Out of memory in ChapReceiveFailure");
+ goto print_msg;
+ }
+ BCOPY(inp, msg, len);
+ p = msg + len; *p = '\0'; p = msg;
+#endif
+
UNTIMEOUT(ChapResponseTimeout, cstate);
+#ifdef CHAPMS
+ if ((cstate->resp_type == CHAP_MICROSOFT_V2) ||
+ (cstate->resp_type == CHAP_MICROSOFT)) {
+ int error;
+
+ /*
+ * Deal with MS-CHAP formatted failure messages; just print the
+ * M=<message> part (if any). For MS-CHAP we're not really supposed
+ * to use M=<message>, but it shouldn't hurt. See ChapSendStatus().
+ */
+ if (!strncmp(p, "E=", 2))
+ error = (int) strtol(p, NULL, 10); /* Remember the error code. */
+ else
+ goto print_msg; /* Message is badly formatted. */
+
+ if (len && ((p = strstr(p, " M=")) != NULL)) {
+ /* M=<message> field found. */
+ p += 3;
+ } else {
+ /* No M=<message>; use the error code. */
+ switch(error) {
+ case MS_CHAP_ERROR_RESTRICTED_LOGON_HOURS:
+ p = "E=646 Restricted logon hours";
+ break;
+
+ case MS_CHAP_ERROR_ACCT_DISABLED:
+ p = "E=647 Account disabled";
+ break;
+
+ case MS_CHAP_ERROR_PASSWD_EXPIRED:
+ p = "E=648 Password expired";
+ break;
+
+ case MS_CHAP_ERROR_NO_DIALIN_PERMISSION:
+ p = "E=649 No dialin permission";
+ break;
+
+ case MS_CHAP_ERROR_AUTHENTICATION_FAILURE:
+ p = "E=691 Authentication failure";
+ break;
+
+ case MS_CHAP_ERROR_CHANGING_PASSWORD:
+ /* Should never see this, we don't support Change Password. */
+ p = "E=709 Error changing password";
+ break;
+
+ default:
+ free(msg);
+ p = msg = malloc(len + 33);
+ if (!msg) {
+ novm("ChapReceiveFailure");
+ goto print_msg;
+ }
+ slprintf(p, len + 33, "Unknown authentication failure: %.*s",
+ len, inp);
+ break;
+ }
+ }
+ len = strlen(p);
+ }
+#endif
+
/*
* Print message.
*/
- if (len > 0)
- PRINTMSG(inp, len);
+print_msg:
+ if (len > 0 && p != NULL)
+ PRINTMSG(p, len);
error("CHAP authentication failed");
auth_withpeer_fail(cstate->unit, PPP_CHAP);
+#ifdef CHAPMS
+ if (msg) free(msg);
+#endif
}
BCOPY(cstate->chal_name, outp, name_len); /* append hostname */
output(cstate->unit, outpacket_buf, outlen + PPP_HDRLEN);
-
+
TIMEOUT(ChapChallengeTimeout, cstate, cstate->timeouttime);
++cstate->chal_transmits;
}
/*
* ChapSendStatus - Send a status response (ack or nak).
+ * See RFC 2433 and RFC 2759 for MS-CHAP and MS-CHAPv2 message formats.
*/
static void
ChapSendStatus(cstate, code)
int code;
{
u_char *outp;
- int outlen, msglen;
+ int i, outlen, msglen;
char msg[256];
+ char *p, *q;
- if (code == CHAP_SUCCESS)
- slprintf(msg, sizeof(msg), "Welcome to %s.", hostname);
- else
- slprintf(msg, sizeof(msg), "I don't like you. Go 'way.");
+ p = msg;
+ q = p + sizeof(msg); /* points 1 byte past msg */
+
+ if (code == CHAP_SUCCESS) {
+#ifdef CHAPMS
+ if (cstate->chal_type == CHAP_MICROSOFT_V2) {
+ /*
+ * Per RFC 2759, success message must be formatted as
+ * "S=<auth_string> M=<message>"
+ * where
+ * <auth_string> is the Authenticator Response (mutual auth)
+ * <message> is a text message
+ *
+ * However, some versions of Windows (win98 tested) do not know
+ * about the M=<message> part (required per RFC 2759) and flag
+ * it as an error (reported incorrectly as an encryption error
+ * to the user). Since the RFC requires it, and it can be
+ * useful information, we supply it if the peer is a conforming
+ * system. Luckily (?), win98 sets the Flags field to 0x04
+ * (contrary to RFC requirements) so we can use that to
+ * distinguish between conforming and non-conforming systems.
+ *
+ * Special thanks to Alex Swiridov <say@real.kharkov.ua> for
+ * help debugging this.
+ */
+ slprintf(p, q - p, "S=");
+ p += 2;
+ slprintf(p, q - p, "%s", cstate->saresponse);
+ p += strlen(cstate->saresponse);
+ if (cstate->resp_flags != 0)
+ goto msgdone;
+ slprintf(p, q - p, " M=");
+ p += 3;
+ }
+#endif /* CHAPMS */
+
+ slprintf(p, q - p, "Welcome to %s.", hostname);
+ } else {
+#ifdef CHAPMS
+ if ((cstate->chal_type == CHAP_MICROSOFT_V2) ||
+ (cstate->chal_type == CHAP_MICROSOFT)) {
+ /*
+ * Failure message must be formatted as
+ * "E=e R=r C=c V=v M=m"
+ * where
+ * e = error code (we use 691, ERROR_AUTHENTICATION_FAILURE)
+ * r = retry (we use 1, ok to retry)
+ * c = challenge to use for next response, we reuse previous
+ * v = Change Password version supported, we use 0
+ * m = text message
+ *
+ * The M=m part is only for MS-CHAPv2, but MS-CHAP should ignore
+ * any extra text according to RFC 2433. So we'll go the easy
+ * (read: lazy) route and include it always. Neither win2k nor
+ * win98 (others untested) display the message to the user anyway.
+ * They also both ignore the E=e code.
+ *
+ * Note that it's safe to reuse the same challenge as we don't
+ * actually accept another response based on the error message
+ * (and no clients try to resend a response anyway).
+ *
+ * Basically, this whole bit is useless code, even the small
+ * implementation here is only because of overspecification.
+ */
+ slprintf(p, q - p, "E=691 R=1 C=");
+ p += 12;
+ for (i = 0; i < cstate->chal_len; i++)
+ sprintf(p + i * 2, "%02X", cstate->challenge[i]);
+ p += cstate->chal_len * 2;
+ slprintf(p, q - p, " V=0 M=");
+ p += 7;
+ }
+#endif /* CHAPMS */
+
+ slprintf(p, q - p, "I don't like you. Go 'way.");
+ }
+msgdone:
msglen = strlen(msg);
outlen = CHAP_HEADERLEN + msglen;
outp = outpacket_buf;
MAKEHEADER(outp, PPP_CHAP); /* paste in a header */
-
+
PUTCHAR(code, outp);
PUTCHAR(cstate->chal_id, outp);
PUTSHORT(outlen, outp);
ChapGenChallenge(cstate)
chap_state *cstate;
{
- int chal_len;
+ int chal_len = 0; /* Avoid compiler warning */
u_char *ptr = cstate->challenge;
int i;
- /* pick a random challenge length between MIN_CHALLENGE_LENGTH and
- MAX_CHALLENGE_LENGTH */
- chal_len = (unsigned) ((drand48() *
- (MAX_CHALLENGE_LENGTH - MIN_CHALLENGE_LENGTH)) +
- MIN_CHALLENGE_LENGTH);
+ switch (cstate->chal_type) {
+ case CHAP_DIGEST_MD5:
+ /*
+ * pick a random challenge length between MIN_CHALLENGE_LENGTH and
+ * MAX_CHALLENGE_LENGTH
+ */
+ chal_len = (unsigned) ((drand48() *
+ (MAX_CHALLENGE_LENGTH - MIN_CHALLENGE_LENGTH)) +
+ MIN_CHALLENGE_LENGTH);
+ break;
+
+#ifdef CHAPMS
+ case CHAP_MICROSOFT:
+ /* MS-CHAP is fixed to an 8 octet challenge. */
+ chal_len = 8;
+ break;
+
+ case CHAP_MICROSOFT_V2:
+ /* MS-CHAPv2 is fixed to a 16 octet challenge. */
+ chal_len = 16;
+ break;
+#endif
+ default:
+ fatal("ChapGenChallenge: Unsupported challenge type %d",
+ (int) cstate->chal_type);
+ break;
+ }
+
cstate->chal_len = chal_len;
cstate->chal_id = ++cstate->id;
cstate->chal_transmits = 0;
- /* generate a random string */
- for (i = 0; i < chal_len; i++)
- *ptr++ = (char) (drand48() * 0xff);
+#ifdef CHAPMS
+ if (mschap_challenge)
+ for (i = 0; i < chal_len; i++)
+ *ptr++ = mschap_challenge[i];
+ else
+#endif
+ /* generate a random string */
+ for (i = 0; i < chal_len; i++)
+ *ptr++ = (char) (drand48() * 0xff);
}
/*
projects / ppp.git / blobdiff