static void chapms2_make_response(ppp_pcb *pcb, unsigned char *response, int id, const char *our_name,
const unsigned char *challenge, const char *secret, int secret_len,
unsigned char *private_) {
LWIP_UNUSED_ARG(id);
challenge++; /* skip length, should be 16 */
*response++ = MS_CHAP2_RESPONSE_LEN;
ChapMS2(pcb, challenge,
#ifdef DEBUGMPPEKEY
mschap2_peer_challenge,
#else
NULL,
#endif
our_name, secret, secret_len, response, private_,
MS_CHAP2_AUTHENTICATEE);
}
static int
chapms2_verify_response(int id, char *name,
unsigned char *secret, int secret_len,
unsigned char *challenge, unsigned char *response,
char *message, int message_space)
{
MS_Chap2Response *rmd;
MS_Chap2Response md;
char saresponse[MS_AUTH_RESPONSE_LENGTH+1];
int challenge_len, response_len;
challenge_len = *challenge++;
response_len = *response++;
if (response_len != MS_CHAP2_RESPONSE_LEN)
goto bad;
rmd = (MS_Chap2Response *) response;
ChapMS2(challenge, rmd->PeerChallenge, name,
(char *)secret, secret_len, &md,
(unsigned char *)saresponse, MS_CHAP2_AUTHENTICATOR);
if (memcmp(md.NTResp, rmd->NTResp, sizeof(md.NTResp)) == 0) {
if (rmd->Flags[0])
slprintf(message, message_space, "S=%s", saresponse);
else
slprintf(message, message_space, "S=%s M=%s",
saresponse, "Access granted");
return 1;
}
bad:
slprintf(message, message_space, "E=691 R=1 C=%0.*B V=0 M=%s",
challenge_len, challenge, "Access denied");
return 0;
}
static int
chapms2_verify_response(int id, char *name,
unsigned char *secret, int secret_len,
unsigned char *challenge, 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;
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(challenge, &response[MS_CHAP2_PEER_CHALLENGE], name,
(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])
slprintf(message, message_space, "S=%s", saresponse);
else
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.
*/
slprintf(message, message_space, "E=691 R=1 C=%0.*B V=0 M=%s",
challenge_len, challenge, "Access denied");
return 0;
}
static tDataBufferPtr dsauth_agent_authbuffer(tDirReference dirRef, const char *keyaccessName, u_int32_t keyaccessNameSize,
const char *keyaccessPassword, u_int32_t keyaccessPasswordSize,
const unsigned char *challenge)
{
tDataBufferPtr authDataBufPtr;
u_int32_t authDataSize;
char *ptr;
MS_Chap2Response keyResponse;
unsigned char priv[64];
authDataSize = (2 * keyaccessNameSize) + NT_RESPONSE_SIZE + (2 * CHALLENGE_SIZE) + (5 * sizeof(u_int32_t));
if ((authDataBufPtr = dsDataBufferAllocate(dirRef, authDataSize)) != 0) {
authDataBufPtr->fBufferLength = authDataSize;
// setup the response buffer
ptr = (char *)(authDataBufPtr->fBufferData);
// 4 byte length & user name
*((u_int32_t*)ptr) = keyaccessNameSize;
ptr += sizeof(u_int32_t);
memcpy(ptr, keyaccessName, keyaccessNameSize);
ptr += keyaccessNameSize;
// 4 byte length & server challenge
*((u_int32_t*)ptr) = CHALLENGE_SIZE;
ptr += sizeof(u_int32_t);
memcpy(ptr, challenge, CHALLENGE_SIZE);
ptr += CHALLENGE_SIZE;
// Generate MSCHAPv2 response for VPN agent as client of OD
bzero(priv, sizeof(priv));
bzero(&keyResponse, sizeof(keyResponse));
ChapMS2((u_char *)challenge, NULL,
(char *)keyaccessName,
(u_char *)keyaccessPassword, keyaccessPasswordSize,
&keyResponse, priv,
MS_CHAP2_AUTHENTICATEE);
#ifdef DSAUTH_DEBUG
DSAuth_hex_print("VPN agent Name", keyaccessName, keyaccessNameSize);
DSAuth_hex_print("Pwd", keyaccessPassword, keyaccessPasswordSize);
DSAuth_hex_print("Challenge", challenge, CHALLENGE_SIZE);
DSAuth_hex_print("PeerChallenge", keyResponse.PeerChallenge, CHALLENGE_SIZE);
DSAuth_hex_print("response", keyResponse.NTResp, 24);
#endif
// 4 byte length & peer challenge
*((u_int32_t*)ptr) = CHALLENGE_SIZE;
ptr += sizeof(u_int32_t);
memcpy(ptr, keyResponse.PeerChallenge, CHALLENGE_SIZE);
ptr += CHALLENGE_SIZE;
// 4 byte length & client digest
*((u_int32_t*)ptr) = NT_RESPONSE_SIZE;
ptr += sizeof(u_int32_t);
memcpy(ptr, keyResponse.NTResp, NT_RESPONSE_SIZE);
ptr += NT_RESPONSE_SIZE;
// 4 byte length & user name (repeated)
*((u_int32_t*)ptr) = keyaccessNameSize;
ptr += sizeof(u_int32_t);
memcpy(ptr, keyaccessName, keyaccessNameSize);
}
return authDataBufPtr;
}