git: 9front

Download patch

ref: 2a80b2a1f265e4d7e25071246968279e91d24c51
parent: 17f8db33730ba44170fe7e3bd4ee534b01e34f50
author: cinap_lenrek <cinap_lenrek@felloff.net>
date: Sun Jan 21 17:35:01 EST 2018 

factotum: implement mschapv2 role=server authentication (for ppp)

this implements the server part of mschapv2 with the new
authserver changes.

we also provide AuthInfo for the client now with the
MPPE secret and the authenticator.


--- a/sys/src/cmd/auth/factotum/chap.c
+++ b/sys/src/cmd/auth/factotum/chap.c
@@ -1,7 +1,7 @@
 /*
  * CHAP, MSCHAP
  * 
- * The client does not authenticate the server, hence no CAI
+ * The client does not authenticate the server
  *
  * Client protocol:
  *	write Chapchal 
@@ -8,7 +8,7 @@
  *	read response Chapreply or MSchaprely structure
  *
  * Server protocol:
- *	read challenge: 8 bytes binary
+ *	read challenge: 8 bytes binary (or 16 bytes for mschapv2)
  *	write user: utf8
  *	write response: Chapreply or MSchapreply structure
  */
@@ -24,6 +24,7 @@
 	MShashlen = 16,
 	MSchallen = 8,
 	MSresplen = 24,
+
 	MSchallenv2 = 16,
 
 	Chapreplylen = MD5LEN+1,
@@ -35,6 +36,7 @@
 static int dochap(char *passwd, int id, char chal[ChapChallen], uchar *resp, int resplen);
 static int domschap(char *passwd, uchar chal[MSchallen], uchar *resp, int resplen);
 static int domschap2(char *passwd, char *user, char *dom, uchar chal[MSchallen], uchar *resp, int resplen);
+static void nthash(uchar hash[MShashlen], char *passwd);
 
 struct State
 {
@@ -44,12 +46,13 @@
 	Authkey k;
 	Ticket t;
 	Ticketreq tr;
-	char chal[ChapChallen];
+	int nchal;
+	char chal[16];
 	int nresp;
 	uchar resp[4096];
 	char err[ERRMAX];
 	char user[64];
-	uchar secret[16];	/* for mschap */
+	uchar secret[16+20];	/* for mschap: MPPE Master secret + authenticator (v2) */
 	int nsecret;
 };
 
@@ -61,8 +64,6 @@
 	SHaveChal,
 	SNeedUser,
 	SNeedResp,
-	SHaveZero,
-	SHaveCAI,
 
 	Maxphase
 };
@@ -75,8 +76,6 @@
 [SHaveChal]	"SHaveChal",
 [SNeedUser]	"SNeedUser",
 [SNeedResp]	"SNeedResp",
-[SHaveZero]	"SHaveZero",
-[SHaveCAI]	"SHaveCAI",
 };
 
 static int
@@ -88,19 +87,24 @@
 	if((iscli = isclient(_strfindattr(fss->attr, "role"))) < 0)
 		return failure(fss, nil);
 
-	if(!iscli && p == &mschapv2)
-		return failure(fss, "role must be client");
-
 	s = emalloc(sizeof *s);
 	s->nresp = 0;
 	s->nsecret = 0;
+	strcpy(s->user, "none");
 	fss->phasename = phasenames;
 	fss->maxphase = Maxphase;
 	s->asfd = -1;
-	if(p == &mschap || p == &mschapv2 || p == &mschap2){
-		s->astype = AuthMSchap;
-	}else {
-		s->astype = AuthChap;
+	if(p == &mschapv2) {
+		s->nchal = MSchallenv2;
+		s->astype = AuthMSchapv2;
+	} else {
+		if(p == &mschap || p == &mschap2){
+			s->nchal = MSchallen;
+			s->astype = AuthMSchap;
+		}else {
+			s->nchal = ChapChallen;
+			s->astype = AuthChap;
+		}
 	}
 	if(iscli)
 		fss->phase = CNeedChal;
@@ -137,7 +141,7 @@
 chapwrite(Fsstate *fss, void *va, uint n)
 {
 	int ret, nreply;
-	char *a, *v;
+	char *a, *pass;
 	Key *k;
 	Keyinfo ki;
 	State *s;
@@ -145,8 +149,11 @@
 	MSchapreply *mcr;
 	OChapreply *ocr;
 	OMSchapreply *omcr;
+	uchar pchal[MSchallenv2];
+	uchar digest[SHA1dlen];
 	uchar reply[4096];
 	char *user, *dom;
+	DigestState *ds;
 
 	s = fss->ps;
 	a = va;
@@ -158,11 +165,13 @@
 		ret = findkey(&k, mkkeyinfo(&ki, fss, nil), "%s", fss->proto->keyprompt);
 		if(ret != RpcOk)
 			return ret;
-		v = _strfindattr(k->privattr, "!password");
-		if(v == nil){
+		user = nil;
+		pass = _strfindattr(k->privattr, "!password");
+		if(pass == nil){
 			closekey(k);
 			return failure(fss, "key has no password");
 		}
+		s->nsecret = 0;
 		s->nresp = 0;
 		memset(s->resp, 0, sizeof(s->resp));
 		setattrs(fss->attr, k->attr);
@@ -177,46 +186,64 @@
 				dom = _strfindattr(fss->attr, "windom");
 				if(dom == nil)
 					dom = "";
-				s->nresp = domschap2(v, user, dom, (uchar*)a, s->resp, sizeof(s->resp));
+				s->nresp = domschap2(pass, user, dom, (uchar*)a, s->resp, sizeof(s->resp));
+			} else {
+				s->nresp = domschap(pass, (uchar*)a, s->resp, sizeof(s->resp));
 			}
-			else if(fss->proto == &mschapv2 || n == MSchallenv2){
-				uchar pchal[MSchallenv2];
-				DigestState *ds;
+			nthash(digest, pass);
+			md4(digest, 16, digest, nil);
+			ds = sha1(digest, 16, nil, nil);
+			sha1(digest, 16, nil, ds);
+			sha1((uchar*)a, 8, s->secret, ds);
+			s->nsecret = 16;
+			break;
+		case AuthMSchapv2:
+			if(n < MSchallenv2)
+				break;
+			user = _strfindattr(fss->attr, "user");
+			if(user == nil)
+				break;
+			genrandom((uchar*)pchal, MSchallenv2);
 
-				if(n < MSchallenv2)
-					break;
-				user = _strfindattr(fss->attr, "user");
-				if(user == nil)
-					break;
+			/* ChallengeHash() */
+			ds = sha1(pchal, MSchallenv2, nil, nil);
+			ds = sha1((uchar*)a, MSchallenv2, nil, ds);
+			sha1((uchar*)user, strlen(user), reply, ds);
 
-				genrandom((uchar*)pchal, MSchallenv2);
+			s->nresp = domschap(pass, reply, s->resp, sizeof(s->resp));
+			if(s->nresp <= 0)
+				break;
 
-				/* ChallengeHash() */
-				ds = sha1(pchal, MSchallenv2, nil, nil);
-				ds = sha1((uchar*)a, MSchallenv2, nil, ds);
-				sha1((uchar*)user, strlen(user), reply, ds);
+			mcr = (MSchapreply*)s->resp;
+			memset(mcr->LMresp, 0, sizeof(mcr->LMresp));
+			memmove(mcr->LMresp, pchal, MSchallenv2);
 
-				s->nresp = domschap(v, reply, s->resp, sizeof(s->resp));
-				if(s->nresp <= 0)
-					break;
+			nthash(digest, pass);
+			md4(digest, 16, digest, nil);
+			ds = sha1(digest, 16, nil, nil);
+			sha1((uchar*)mcr->NTresp, MSresplen, nil, ds);
+			sha1((uchar*)"This is the MPPE Master Key", 27, s->secret, ds);
 
-				mcr = (MSchapreply*)s->resp;
-				memset(mcr->LMresp, 0, sizeof(mcr->LMresp));
-				memmove(mcr->LMresp, pchal, MSchallenv2);
-			}
-			else {
-				s->nresp = domschap(v, (uchar*)a, s->resp, sizeof(s->resp));
-			}
+			ds = sha1(digest, 16, nil, nil);
+			sha1((uchar*)mcr->NTresp, MSresplen, nil, ds);
+			sha1((uchar*)"Magic server to client signing constant", 39, digest, ds);
+
+			ds = sha1(digest, 20, nil, nil);
+			sha1(reply, 8, nil, ds);	/* ChallngeHash */
+			sha1((uchar*)"Pad to make it do more than one iteration", 41, s->secret+16, ds);
+			s->nsecret = 16+20;
 			break;
 		case AuthChap:
 			if(n < ChapChallen+1)
 				break;
-			s->nresp = dochap(v, *a, a+1, s->resp, sizeof(s->resp));
+			s->nresp = dochap(pass, *a, a+1, s->resp, sizeof(s->resp));
 			break;
 		}
 		closekey(k);
 		if(s->nresp <= 0)
 			return failure(fss, "chap botch");
+		if(user != nil)
+			safecpy(s->user, user, sizeof s->user);
 		fss->phase = CHaveResp;
 		return RpcOk;
 
@@ -244,6 +271,7 @@
 			memmove(ocr->resp, cr->resp, sizeof(ocr->resp));
 			break;
 		case AuthMSchap:
+		case AuthMSchapv2:
 			if(n < MSchapreplylen)
 				return failure(fss, "did not get MSchapreply");
 			if(n > sizeof(reply)+MSchapreplylen-OMSCHAPREPLYLEN)
@@ -284,12 +312,20 @@
 			*n = s->nresp;
 		memmove(va, s->resp, *n);
 		fss->phase = Established;
-		fss->haveai = 0;
+		if(s->nsecret == 0){
+			fss->haveai = 0;
+			return RpcOk;
+		}
+		fss->ai.cuid = s->user;
+		fss->ai.suid = "none";	/* server not authenticated */
+		fss->ai.secret = s->secret;
+		fss->ai.nsecret = s->nsecret;
+		fss->haveai = 1;
 		return RpcOk;
 
 	case SHaveChal:
-		if(*n > sizeof s->chal)
-			*n = sizeof s->chal;
+		if(*n > s->nchal)
+			*n = s->nchal;
 		memmove(va, s->chal, *n);
 		fss->phase = SNeedUser;
 		return RpcOk;
@@ -322,9 +358,9 @@
 		goto err;
 	
 	alarm(30*1000);
-	n = readn(s->asfd, s->chal, sizeof s->chal);
+	n = readn(s->asfd, s->chal, s->nchal);
 	alarm(0);
-	if(n != sizeof s->chal)
+	if(n != s->nchal)
 		goto err;
 
 	return 0;
@@ -348,15 +384,11 @@
 		goto err;
 	}
 	n = _asgetresp(s->asfd, &s->t, &a, &s->k);
+	alarm(0);
 	if(n < 0){
-		alarm(0);
 		/* leave connection open so we can try again */
 		return -1;
 	}
-	s->nsecret = readn(s->asfd, s->secret, sizeof s->secret);
-	alarm(0);
-	if(s->nsecret < 0)
-		s->nsecret = 0;
 	close(s->asfd);
 	s->asfd = -1;
 
@@ -372,6 +404,17 @@
 	|| tsmemcmp(a.chal, s->tr.chal, sizeof(a.chal)) != 0){
 		werrstr(Easproto);
 		return -1;
+	}
+	s->nsecret = 0;
+	if(s->t.form != 0){
+		if(s->astype == AuthMSchap || s->astype == AuthMSchapv2){
+			memmove(s->secret, s->t.key, 16);
+			if(s->astype == AuthMSchapv2){
+				memmove(s->secret+16, a.rand, 20);
+				s->nsecret = 16+20;
+			} else
+				s->nsecret = 16;
+		}
 	}
 	return 0;
 err:
-- 
⑨