static int chap_md5_verify_response(int id, char *name,
unsigned char *secret, int secret_len,
unsigned char *challenge, unsigned char *response,
char *message, int message_space) {
md5_context ctx;
unsigned char idbyte = id;
unsigned char hash[MD5_HASH_SIZE];
int challenge_len, response_len;
LWIP_UNUSED_ARG(name);
challenge_len = *challenge++;
response_len = *response++;
if (response_len == MD5_HASH_SIZE) {
/* Generate hash of ID, secret, challenge */
md5_starts(&ctx);
md5_update(&ctx, &idbyte, 1);
md5_update(&ctx, secret, secret_len);
md5_update(&ctx, challenge, challenge_len);
md5_finish(&ctx, hash);
/* Test if our hash matches the peer's response */
if (memcmp(hash, response, MD5_HASH_SIZE) == 0) {
ppp_slprintf(message, message_space, "Access granted");
return 1;
}
}
ppp_slprintf(message, message_space, "Access denied");
return 0;
}
static int chapms_verify_response(ppp_pcb *pcb, int id, const char *name,
const unsigned char *secret, int secret_len,
const unsigned char *challenge, const unsigned char *response,
char *message, int message_space) {
unsigned char md[MS_CHAP_RESPONSE_LEN];
int diff;
int challenge_len, response_len;
LWIP_UNUSED_ARG(id);
LWIP_UNUSED_ARG(name);
challenge_len = *challenge++; /* skip length, is 8 */
response_len = *response++;
if (response_len != MS_CHAP_RESPONSE_LEN)
goto bad;
#ifndef MSLANMAN
if (!response[MS_CHAP_USENT]) {
/* Should really propagate this into the error packet. */
ppp_notice("Peer request for LANMAN auth not supported");
goto bad;
}
#endif
/* Generate the expected response. */
ChapMS(pcb, (const u_char *)challenge, (const char *)secret, secret_len, md);
#ifdef MSLANMAN
/* Determine which part of response to verify against */
if (!response[MS_CHAP_USENT])
diff = memcmp(&response[MS_CHAP_LANMANRESP],
&md[MS_CHAP_LANMANRESP], MS_CHAP_LANMANRESP_LEN);
else
#endif
diff = memcmp(&response[MS_CHAP_NTRESP], &md[MS_CHAP_NTRESP],
MS_CHAP_NTRESP_LEN);
if (diff == 0) {
ppp_slprintf(message, message_space, "Access granted");
return 1;
}
bad:
/* See comments below for MS-CHAP V2 */
ppp_slprintf(message, message_space, "E=691 R=1 C=%0.*B V=0",
challenge_len, challenge);
return 0;
}
/*
* chap_respond - Generate and send a response to a challenge.
*/
static void chap_respond(ppp_pcb *pcb, int id,
unsigned char *pkt, int len) {
int clen, nlen;
int secret_len;
struct pbuf *p;
u_char *outp;
char rname[MAXNAMELEN+1];
char secret[MAXSECRETLEN+1];
p = pbuf_alloc(PBUF_RAW, (u16_t)(RESP_MAX_PKTLEN), PPP_CTRL_PBUF_TYPE);
if(NULL == p)
return;
if(p->tot_len != p->len) {
pbuf_free(p);
return;
}
if ((pcb->chap_client.flags & (LOWERUP | AUTH_STARTED)) != (LOWERUP | AUTH_STARTED))
return; /* not ready */
if (len < 2 || len < pkt[0] + 1)
return; /* too short */
clen = pkt[0];
nlen = len - (clen + 1);
/* Null terminate and clean remote name. */
ppp_slprintf(rname, sizeof(rname), "%.*v", nlen, pkt + clen + 1);
#if PPP_REMOTENAME
/* Microsoft doesn't send their name back in the PPP packet */
if (pcb->settings.explicit_remote || (pcb->settings.remote_name[0] != 0 && rname[0] == 0))
strlcpy(rname, pcb->settings.remote_name, sizeof(rname));
#endif /* PPP_REMOTENAME */
/* get secret for authenticating ourselves with the specified host */
if (!get_secret(pcb, pcb->chap_client.name, rname, secret, &secret_len, 0)) {
secret_len = 0; /* assume null secret if can't find one */
ppp_warn("No CHAP secret found for authenticating us to %q", rname);
}
outp = (u_char*)p->payload;
MAKEHEADER(outp, PPP_CHAP);
outp += CHAP_HDRLEN;
pcb->chap_client.digest->make_response(pcb, outp, id, pcb->chap_client.name, pkt,
secret, secret_len, pcb->chap_client.priv);
memset(secret, 0, secret_len);
clen = *outp;
nlen = strlen(pcb->chap_client.name);
memcpy(outp + clen + 1, pcb->chap_client.name, nlen);
outp = (u_char*)p->payload + PPP_HDRLEN;
len = CHAP_HDRLEN + clen + 1 + nlen;
outp[0] = CHAP_RESPONSE;
outp[1] = id;
outp[2] = len >> 8;
outp[3] = len;
pbuf_realloc(p, PPP_HDRLEN + len);
ppp_write(pcb, p);
}
/*
* chap_handle_response - check the response to our challenge.
*/
static void chap_handle_response(ppp_pcb *pcb, int id,
unsigned char *pkt, int len) {
int response_len, ok, mlen;
const unsigned char *response;
unsigned char *outp;
struct pbuf *p;
const char *name = NULL; /* initialized to shut gcc up */
#if 0 /* UNUSED */
int (*verifier)(const char *, const char *, int, const struct chap_digest_type *,
const unsigned char *, const unsigned char *, char *, int);
#endif /* UNUSED */
char rname[MAXNAMELEN+1];
char message[256];
if ((pcb->chap_server.flags & LOWERUP) == 0)
return;
if (id != pcb->chap_server.challenge[PPP_HDRLEN+1] || len < 2)
return;
if (pcb->chap_server.flags & CHALLENGE_VALID) {
response = pkt;
GETCHAR(response_len, pkt);
len -= response_len + 1; /* length of name */
name = (char *)pkt + response_len;
if (len < 0)
return;
if (pcb->chap_server.flags & TIMEOUT_PENDING) {
pcb->chap_server.flags &= ~TIMEOUT_PENDING;
UNTIMEOUT(chap_timeout, pcb);
}
#if PPP_REMOTENAME
if (pcb->settings.explicit_remote) {
name = pcb->remote_name;
} else
#endif /* PPP_REMOTENAME */
{
/* Null terminate and clean remote name. */
ppp_slprintf(rname, sizeof(rname), "%.*v", len, name);
name = rname;
}
#if 0 /* UNUSED */
if (chap_verify_hook)
verifier = chap_verify_hook;
else
verifier = chap_verify_response;
ok = (*verifier)(name, pcb->chap_server.name, id, pcb->chap_server.digest,
pcb->chap_server.challenge + PPP_HDRLEN + CHAP_HDRLEN,
response, pcb->chap_server.message, sizeof(pcb->chap_server.message));
#endif /* UNUSED */
ok = chap_verify_response(pcb, name, pcb->chap_server.name, id, pcb->chap_server.digest,
pcb->chap_server.challenge + PPP_HDRLEN + CHAP_HDRLEN,
response, message, sizeof(message));
#if 0 /* UNUSED */
if (!ok || !auth_number()) {
#endif /* UNUSED */
if (!ok) {
pcb->chap_server.flags |= AUTH_FAILED;
ppp_warn("Peer %q failed CHAP authentication", name);
}
} else if ((pcb->chap_server.flags & AUTH_DONE) == 0)
return;
/* send the response */
mlen = strlen(message);
len = CHAP_HDRLEN + mlen;
p = pbuf_alloc(PBUF_RAW, (u16_t)(PPP_HDRLEN +len), PPP_CTRL_PBUF_TYPE);
if(NULL == p)
return;
if(p->tot_len != p->len) {
pbuf_free(p);
return;
}
outp = (unsigned char *)p->payload;
MAKEHEADER(outp, PPP_CHAP);
outp[0] = (pcb->chap_server.flags & AUTH_FAILED)? CHAP_FAILURE: CHAP_SUCCESS;
outp[1] = id;
outp[2] = len >> 8;
outp[3] = len;
if (mlen > 0)
memcpy(outp + CHAP_HDRLEN, message, mlen);
ppp_write(pcb, p);
if (pcb->chap_server.flags & CHALLENGE_VALID) {
pcb->chap_server.flags &= ~CHALLENGE_VALID;
if (!(pcb->chap_server.flags & AUTH_DONE) && !(pcb->chap_server.flags & AUTH_FAILED)) {
#if 0 /* UNUSED */
/*
* Auth is OK, so now we need to check session restrictions
* to ensure everything is OK, but only if we used a
* plugin, and only if we're configured to check. This
* allows us to do PAM checks on PPP servers that
* authenticate against ActiveDirectory, and use AD for
* account info (like when using Winbind integrated with
* PAM).
*/
if (session_mgmt &&
session_check(name, NULL, devnam, NULL) == 0) {
pcb->chap_server.flags |= AUTH_FAILED;
ppp_warn("Peer %q failed CHAP Session verification", name);
}
#endif /* UNUSED */
}
if (pcb->chap_server.flags & AUTH_FAILED) {
auth_peer_fail(pcb, PPP_CHAP);
} else {
if ((pcb->chap_server.flags & AUTH_DONE) == 0)
auth_peer_success(pcb, PPP_CHAP,
pcb->chap_server.digest->code,
name, strlen(name));
if (pcb->settings.chap_rechallenge_time) {
pcb->chap_server.flags |= TIMEOUT_PENDING;
TIMEOUT(chap_timeout, pcb,
pcb->settings.chap_rechallenge_time);
}
}
pcb->chap_server.flags |= AUTH_DONE;
}
}
static int chapms2_verify_response(ppp_pcb *pcb, int id, const char *name,
const unsigned char *secret, int secret_len,
const unsigned char *challenge, const unsigned char *response,
char *message, int message_space) {
unsigned char md[MS_CHAP2_RESPONSE_LEN];
char saresponse[MS_AUTH_RESPONSE_LENGTH+1];
int challenge_len, response_len;
LWIP_UNUSED_ARG(id);
challenge_len = *challenge++; /* skip length, is 16 */
response_len = *response++;
if (response_len != MS_CHAP2_RESPONSE_LEN)
goto bad; /* not even the right length */
/* Generate the expected response and our mutual auth. */
ChapMS2(pcb, (const u_char*)challenge, (const u_char*)&response[MS_CHAP2_PEER_CHALLENGE], name,
(const char *)secret, secret_len, md,
(unsigned char *)saresponse, MS_CHAP2_AUTHENTICATOR);
/* compare MDs and send the appropriate status */
/*
* 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 <*****@*****.**> for
* help debugging this.
*/
if (memcmp(&md[MS_CHAP2_NTRESP], &response[MS_CHAP2_NTRESP],
MS_CHAP2_NTRESP_LEN) == 0) {
if (response[MS_CHAP2_FLAGS])
ppp_slprintf(message, message_space, "S=%s", saresponse);
else
ppp_slprintf(message, message_space, "S=%s M=%s",
saresponse, "Access granted");
return 1;
}
bad:
/*
* 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. 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.
*/
ppp_slprintf(message, message_space, "E=691 R=1 C=%0.*B V=0 M=%s",
challenge_len, challenge, "Access denied");
return 0;
}
/*
* upap_rauth - Receive Authenticate.
*/
static void upap_rauthreq(ppp_pcb *pcb, u_char *inp, int id, int len) {
u_char ruserlen, rpasswdlen;
char *ruser;
char *rpasswd;
char rhostname[256];
int retcode;
const char *msg;
int msglen;
if (pcb->upap.us_serverstate < UPAPSS_LISTEN)
return;
/*
* If we receive a duplicate authenticate-request, we are
* supposed to return the same status as for the first request.
*/
if (pcb->upap.us_serverstate == UPAPSS_OPEN) {
upap_sresp(pcb, UPAP_AUTHACK, id, "", 0); /* return auth-ack */
return;
}
if (pcb->upap.us_serverstate == UPAPSS_BADAUTH) {
upap_sresp(pcb, UPAP_AUTHNAK, id, "", 0); /* return auth-nak */
return;
}
/*
* Parse user/passwd.
*/
if (len < 1) {
UPAPDEBUG(("pap_rauth: rcvd short packet."));
return;
}
GETCHAR(ruserlen, inp);
len -= sizeof (u_char) + ruserlen + sizeof (u_char);
if (len < 0) {
UPAPDEBUG(("pap_rauth: rcvd short packet."));
return;
}
ruser = (char *) inp;
INCPTR(ruserlen, inp);
GETCHAR(rpasswdlen, inp);
if (len < rpasswdlen) {
UPAPDEBUG(("pap_rauth: rcvd short packet."));
return;
}
rpasswd = (char *) inp;
/*
* Check the username and password given.
*/
retcode = UPAP_AUTHNAK;
if (auth_check_passwd(pcb, ruser, ruserlen, rpasswd, rpasswdlen, &msg, &msglen)) {
retcode = UPAP_AUTHACK;
}
BZERO(rpasswd, rpasswdlen);
#if 0 /* UNUSED */
/*
* 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 (retcode == UPAP_AUTHACK) {
if (!auth_number()) {
/* We do not want to leak info about the pap result. */
retcode = UPAP_AUTHNAK; /* XXX exit value will be "wrong" */
warn("calling number %q is not authorized", remote_number);
}
}
msglen = strlen(msg);
if (msglen > 255)
msglen = 255;
#endif /* UNUSED */
upap_sresp(pcb, retcode, id, msg, msglen);
/* Null terminate and clean remote name. */
ppp_slprintf(rhostname, sizeof(rhostname), "%.*v", ruserlen, ruser);
if (retcode == UPAP_AUTHACK) {
pcb->upap.us_serverstate = UPAPSS_OPEN;
ppp_notice("PAP peer authentication succeeded for %q", rhostname);
auth_peer_success(pcb, PPP_PAP, 0, ruser, ruserlen);
} else {
pcb->upap.us_serverstate = UPAPSS_BADAUTH;
ppp_warn("PAP peer authentication failed for %q", rhostname);
auth_peer_fail(pcb, PPP_PAP);
}
if (pcb->settings.pap_req_timeout > 0)
UNTIMEOUT(upap_reqtimeout, pcb);
}
