*
*/
-#define RCSID "$Id: chap_ms.c,v 1.28 2003/01/10 07:12:36 fcusack Exp $"
+#define RCSID "$Id: chap_ms.c,v 1.29 2003/06/11 23:56:26 paulus Exp $"
#ifdef CHAPMS
#include <unistd.h>
#include "pppd.h"
-#include "chap.h"
+#include "chap-new.h"
#include "chap_ms.h"
#include "md4.h"
#include "sha1.h"
#include "pppcrypt.h"
+#include "magic.h"
static const char rcsid[] = RCSID;
static void SetMasterKeys __P((char *, int, u_char[24], int));
#endif
-extern double drand48 __P((void));
-
#ifdef MSLANMAN
bool ms_lanman = 0; /* Use LanMan password instead of NT */
/* Has meaning only with MS-CHAP challenges */
u_char mppe_recv_key[MPPE_MAX_KEY_LEN];
int mppe_keys_set = 0; /* Have the MPPE keys been set? */
+/* For MPPE debug */
+/* Use "[]|}{?/><,`!2&&(" (sans quotes) for RFC 3079 MS-CHAPv2 test value */
+static char *mschap_challenge = NULL;
+/* Use "!@\#$%^&*()_+:3|~" (sans quotes, backslash is to escape #) for ... */
+static char *mschap2_peer_challenge = NULL;
+
#include "fsm.h" /* Need to poke MPPE options */
#include "ccp.h"
#include <net/ppp-comp.h>
#endif
+/*
+ * Command-line options.
+ */
+static option_t chapms_option_list[] = {
+#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 }
+};
+
+/*
+ * chapms_generate_challenge - generate a challenge for MS-CHAP.
+ * For MS-CHAP the challenge length is fixed at 8 bytes.
+ * The length goes in challenge[0] and the actual challenge starts
+ * at challenge[1].
+ */
+static void
+chapms_generate_challenge(unsigned char *challenge)
+{
+ *challenge++ = 8;
+ if (mschap_challenge && strlen(mschap_challenge) == 8)
+ memcpy(challenge, mschap_challenge, 8);
+ else
+ random_bytes(challenge, 8);
+}
+
+static void
+chapms2_generate_challenge(unsigned char *challenge)
+{
+ *challenge++ = 16;
+ if (mschap_challenge && strlen(mschap_challenge) == 16)
+ memcpy(challenge, mschap_challenge, 16);
+ else
+ random_bytes(challenge, 16);
+}
+
+static int
+chapms_verify_response(int id, char *name,
+ unsigned char *secret, int secret_len,
+ unsigned char *challenge, unsigned char *response,
+ char *message, int message_space)
+{
+ MS_ChapResponse *rmd = (MS_ChapResponse *) response;
+ MS_ChapResponse md;
+ int diff;
+ int challenge_len, response_len;
+
+ challenge_len = *challenge++; /* skip length, is 8 */
+
+ response_len = *response++;
+ if (response_len != MS_CHAP_RESPONSE_LEN)
+ goto bad;
+
+#ifndef MSLANMAN
+ if (!rmd->UseNT[0]) {
+ /* Should really propagate this into the error packet. */
+ notice("Peer request for LANMAN auth not supported");
+ goto bad;
+ }
+#endif
+
+ /* Generate the expected response. */
+ ChapMS(challenge, secret, secret_len, &md);
+
+#ifdef MSLANMAN
+ /* Determine which part of response to verify against */
+ if (!rmd->UseNT[0])
+ diff = memcmp(&rmd->LANManResp, &md.LANManResp,
+ sizeof(md.LANManResp));
+ else
+#endif
+ diff = memcmp(&rmd->NTResp, &md.NTResp, sizeof(md.NTResp));
+
+ if (diff == 0) {
+ slprintf(message, message_space, "Access granted");
+ return 1;
+ }
+
+ bad:
+ /* See comments below for MS-CHAP V2 */
+ slprintf(message, message_space, "E=691 R=1 C=%0.*B V=0",
+ challenge_len, challenge);
+ 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)
+{
+ MS_Chap2Response *rmd = (MS_Chap2Response *) response;
+ MS_Chap2Response md;
+ 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, rmd->PeerChallenge, name,
+ secret, secret_len, &md,
+ 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 <say@real.kharkov.ua> for
+ * help debugging this.
+ */
+ 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:
+ /*
+ * 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 void
+chapms_make_response(unsigned char *response, int id, char *our_name,
+ unsigned char *challenge, char *secret, int secret_len,
+ unsigned char *private)
+{
+ challenge++; /* skip length, should be 8 */
+ *response++ = MS_CHAP_RESPONSE_LEN;
+ ChapMS(challenge, secret, secret_len, (MS_ChapResponse *) response);
+}
+
+static void
+chapms2_make_response(unsigned char *response, int id, char *our_name,
+ unsigned char *challenge, char *secret, int secret_len,
+ unsigned char *private)
+{
+ challenge++; /* skip length, should be 16 */
+ *response++ = MS_CHAP2_RESPONSE_LEN;
+ ChapMS2(challenge, mschap2_peer_challenge, our_name,
+ secret, secret_len,
+ (MS_Chap2Response *) response, private,
+ MS_CHAP2_AUTHENTICATEE);
+}
+
+static int
+chapms2_check_success(unsigned char *msg, int len, unsigned char *private)
+{
+ if ((len < MS_AUTH_RESPONSE_LENGTH + 2) || strncmp(msg, "S=", 2)) {
+ /* Packet does not start with "S=" */
+ error("MS-CHAPv2 Success packet is badly formed.");
+ return 0;
+ }
+ msg += 2;
+ len -= 2;
+ if (len < MS_AUTH_RESPONSE_LENGTH
+ || memcmp(msg, private, MS_AUTH_RESPONSE_LENGTH)) {
+ /* Authenticator Response did not match expected. */
+ error("MS-CHAPv2 mutual authentication failed.");
+ return 0;
+ }
+ /* Authenticator Response matches. */
+ msg += MS_AUTH_RESPONSE_LENGTH; /* Eat it */
+ len -= MS_AUTH_RESPONSE_LENGTH;
+ if ((len >= 3) && !strncmp(msg, " M=", 3)) {
+ msg += 3; /* Eat the delimiter */
+ } else if (len) {
+ /* Packet has extra text which does not begin " M=" */
+ error("MS-CHAPv2 Success packet is badly formed.");
+ return 0;
+ }
+ return 1;
+}
+
+static void
+chapms_handle_failure(unsigned char *inp, int len)
+{
+ int err;
+ char *p, *msg;
+
+ /* We want a null-terminated string for strxxx(). */
+ msg = malloc(len + 1);
+ if (!msg) {
+ notice("Out of memory in chapms_handle_failure");
+ return;
+ }
+ BCOPY(inp, msg, len);
+ msg[len] = 0;
+ p = msg;
+
+ /*
+ * 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
+ * chapms[2]_verify_response.
+ */
+ if (!strncmp(p, "E=", 2))
+ err = 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 (err) {
+ 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);
+ error("Unknown MS-CHAP authentication failure: %.*v",
+ len, inp);
+ return;
+ }
+ }
+print_msg:
+ if (p != NULL)
+ error("MS-CHAP authentication failed: %v", p);
+ free(msg);
+}
+
static void
ChallengeResponse(u_char *challenge,
u_char PasswordHash[MD4_SIGNATURE_SIZE],
void
-ChapMS(chap_state *cstate, u_char *rchallenge, char *secret, int secret_len,
+ChapMS(u_char *rchallenge, char *secret, int secret_len,
MS_ChapResponse *response)
{
#if 0
response->UseNT[0] = 1;
#endif
- cstate->resp_length = MS_CHAP_RESPONSE_LEN;
-
#ifdef MPPE
Set_Start_Key(rchallenge, secret, secret_len);
mppe_keys_set = 1;
* Authenticator Response.
*/
void
-ChapMS2(chap_state *cstate, u_char *rchallenge, u_char *PeerChallenge,
+ChapMS2(u_char *rchallenge, u_char *PeerChallenge,
char *user, char *secret, int secret_len, MS_Chap2Response *response,
- u_char authResponse[MS_AUTH_RESPONSE_LENGTH+1], int authenticator)
+ u_char authResponse[], int authenticator)
{
/* ARGSUSED */
u_char *p = response->PeerChallenge;
response->PeerChallenge, rchallenge,
user, authResponse);
- cstate->resp_length = MS_CHAP2_RESPONSE_LEN;
-
#ifdef MPPE
SetMasterKeys(secret, secret_len, response->NTResp, authenticator);
mppe_keys_set = 1;
}
#endif /* MPPE */
+static struct chap_digest_type chapms_digest = {
+ CHAP_MICROSOFT, /* code */
+ chapms_generate_challenge,
+ chapms_verify_response,
+ chapms_make_response,
+ NULL, /* check_success */
+ chapms_handle_failure,
+};
+
+static struct chap_digest_type chapms2_digest = {
+ CHAP_MICROSOFT_V2, /* code */
+ chapms2_generate_challenge,
+ chapms2_verify_response,
+ chapms2_make_response,
+ chapms2_check_success,
+ chapms_handle_failure,
+};
+
+void
+chapms_init(void)
+{
+ chap_register_digest(&chapms_digest);
+ chap_register_digest(&chapms2_digest);
+ add_options(chapms_option_list);
+}
+
#endif /* CHAPMS */
projects / ppp.git / blobdiff