plan9port

p9sk1.c (7389B)

---

 /*
  * p9sk1, p9sk2 - Plan 9 secret (private) key authentication.
  * p9sk2 is an incomplete flawed variant of p9sk1.
  *
  * Client protocol:
  *	write challenge[challen]	(p9sk1 only)
  *	read tickreq[tickreqlen]
  *	write ticket[ticketlen]
  *	read authenticator[authentlen]
  *
  * Server protocol:
  * 	read challenge[challen]	(p9sk1 only)
  *	write tickreq[tickreqlen]
  *	read ticket[ticketlen]
  *	write authenticator[authentlen]
  */
 
 #include "std.h"
 #include "dat.h"
 
 extern Proto p9sk1, p9sk2;
 static int gettickets(Ticketreq*, char*, Key*);
 
 #define max(a, b) ((a) > (b) ? (a) : (b))
 enum
 {
 	MAXAUTH = max(TICKREQLEN, TICKETLEN+max(TICKETLEN, AUTHENTLEN))
 };
 
 static int
 p9skclient(Conv *c)
 {
 	char *user;
 	char cchal[CHALLEN];
 	uchar secret[8];
 	char buf[MAXAUTH];
 	int speakfor, ret;
 	Attr *a;
 	Authenticator au;
 	Key *k;
 	Ticket t;
 	Ticketreq tr;
 
 	ret = -1;
 	a = nil;
 	k = nil;
 
 	/* p9sk1: send client challenge */
 	if(c->proto == &p9sk1){
 		c->state = "write challenge";
 		memrandom(cchal, CHALLEN);
 		if(convwrite(c, cchal, CHALLEN) < 0)
 			goto out;
 	}
 
 	/* read ticket request */
 	c->state = "read tickreq";
 	if(convread(c, buf, TICKREQLEN) < 0)
 		goto out;
 	convM2TR(buf, &tr);
 
 	/* p9sk2: use server challenge as client challenge */
 	if(c->proto == &p9sk2)
 		memmove(cchal, tr.chal, CHALLEN);
 
 	/*
 	 * find a key.
 	 *
 	 * if the user is the factotum owner, any key will do.
 	 * if not, then if we have a speakfor key,
 	 * we will only vouch for the user's local identity.
 	 *
 	 * this logic is duplicated in p9any.c
 	 */
 	user = strfindattr(c->attr, "user");
 	a = delattr(copyattr(c->attr), "role");
 	a = addattr(a, "proto=p9sk1");
 
 	if(strcmp(c->sysuser, owner) == 0){
 		speakfor = 0;
 		a = addattr(a, "proto=p9sk1 user? dom=%q", tr.authdom);
 	}else if(user==nil || strcmp(c->sysuser, user)==0){
 		speakfor = 1;
 		a = delattr(a, "user");
 		a = addattr(a, "proto=p9sk1 user? dom=%q role=speakfor", tr.authdom);
 	}else{
 		werrstr("will not authenticate for %q as %q", c->sysuser, user);
 		goto out;
 	}
 
 	for(;;){
 		c->state = "find key";
 		k = keyfetch(c, "%A", a);
 		if(k == nil)
 			goto out;
 
 		/* relay ticket request to auth server, get tickets */
 		strcpy(tr.hostid, strfindattr(k->attr, "user"));
 		if(speakfor)
 			strcpy(tr.uid, c->sysuser);
 		else
 			strcpy(tr.uid, tr.hostid);
 
 		c->state = "get tickets";
 		if(gettickets(&tr, buf, k) < 0)
 			goto out;
 
 		convM2T(buf, &t, k->priv);
 		if(t.num == AuthTc)
 			break;
 
 		/* we don't agree with the auth server about the key; try again */
 		c->state = "replace key";
 		if((k = keyreplace(c, k, "key mismatch with auth server")) == nil){
 			werrstr("key mismatch with auth server");
 			goto out;
 		}
 	}
 
 	/* send second ticket and authenticator to server */
 	c->state = "write ticket+auth";
 	memmove(buf, buf+TICKETLEN, TICKETLEN);
 	au.num = AuthAc;
 	memmove(au.chal, tr.chal, CHALLEN);
 	au.id = 0;
 	convA2M(&au, buf+TICKETLEN, t.key);
 	if(convwrite(c, buf, TICKETLEN+AUTHENTLEN) < 0)
 		goto out;
 
 	/* read authenticator from server */
 	c->state = "read auth";
 	if(convread(c, buf, AUTHENTLEN) < 0)
 		goto out;
 	convM2A(buf, &au, t.key);
 	if(au.num != AuthAs || memcmp(au.chal, cchal, CHALLEN) != 0 || au.id != 0){
 		werrstr("server lies through his teeth");
 		goto out;
 	}
 
 	/* success */
 	c->attr = addcap(c->attr, c->sysuser, &t);
 	flog("p9skclient success %A", c->attr);	/* before adding secret! */
 	des56to64((uchar*)t.key, secret);
 	c->attr = addattr(c->attr, "secret=%.8H", secret);
 	ret = 0;
 
 out:
 	if(ret < 0)
 		flog("p9skclient: %r");
 	freeattr(a);
 	keyclose(k);
 	return ret;
 }
 
 static int
 p9skserver(Conv *c)
 {
 	char cchal[CHALLEN], buf[MAXAUTH];
 	uchar secret[8];
 	int ret;
 	Attr *a;
 	Authenticator au;
 	Key *k;
 	Ticketreq tr;
 	Ticket t;
 
 	ret = -1;
 
 	a = addattr(copyattr(c->attr), "user? dom?");
 	a = addattr(a, "user? dom? proto=p9sk1");
 	if((k = keyfetch(c, "%A", a)) == nil)
 		goto out;
 
 	/* p9sk1: read client challenge */
 	if(c->proto == &p9sk1){
 		if(convread(c, cchal, CHALLEN) < 0)
 			goto out;
 	}
 
 	/* send ticket request */
 	memset(&tr, 0, sizeof tr);
 	tr.type = AuthTreq;
 	strcpy(tr.authid, strfindattr(k->attr, "user"));
 	strcpy(tr.authdom, strfindattr(k->attr, "dom"));
 	memrandom(tr.chal, sizeof tr.chal);
 	convTR2M(&tr, buf);
 	if(convwrite(c, buf, TICKREQLEN) < 0)
 		goto out;
 
 	/* p9sk2: use server challenge as client challenge */
 	if(c->proto == &p9sk2)
 		memmove(cchal, tr.chal, sizeof tr.chal);
 
 	/* read ticket+authenticator */
 	if(convread(c, buf, TICKETLEN+AUTHENTLEN) < 0)
 		goto out;
 
 	convM2T(buf, &t, k->priv);
 	if(t.num != AuthTs || memcmp(t.chal, tr.chal, CHALLEN) != 0){
 		/* BUG badkey */
 		werrstr("key mismatch with auth server");
 		goto out;
 	}
 
 	convM2A(buf+TICKETLEN, &au, t.key);
 	if(au.num != AuthAc || memcmp(au.chal, tr.chal, CHALLEN) != 0 || au.id != 0){
 		werrstr("client lies through his teeth");
 		goto out;
 	}
 
 	/* send authenticator */
 	au.num = AuthAs;
 	memmove(au.chal, cchal, CHALLEN);
 	convA2M(&au, buf, t.key);
 	if(convwrite(c, buf, AUTHENTLEN) < 0)
 		goto out;
 
 	/* success */
 	c->attr = addcap(c->attr, c->sysuser, &t);
 	flog("p9skserver success %A", c->attr);	/* before adding secret! */
 	des56to64((uchar*)t.key, secret);
 	c->attr = addattr(c->attr, "secret=%.8H", secret);
 	ret = 0;
 
 out:
 	if(ret < 0)
 		flog("p9skserver: %r");
 	freeattr(a);
 	keyclose(k);
 	return ret;
 }
 
 int
 _asgetticket(int fd, char *trbuf, char *tbuf)
 {
 	if(write(fd, trbuf, TICKREQLEN) < 0){
 		close(fd);
 		return -1;
 	}
 	return _asrdresp(fd, tbuf, 2*TICKETLEN);
 }
 static int
 getastickets(Ticketreq *tr, char *buf)
 {
 	int asfd;
 	int ret;
 
 	if((asfd = xioauthdial(nil, tr->authdom)) < 0)
 		return -1;
 	convTR2M(tr, buf);
 	ret = xioasgetticket(asfd, buf, buf);
 	xioclose(asfd);
 	return ret;
 }
 
 static int
 mktickets(Ticketreq *tr, char *buf, Key *k)
 {
 	Ticket t;
 
 	if(strcmp(tr->authid, tr->hostid) != 0)
 		return -1;
 
 	memset(&t, 0, sizeof t);
 	memmove(t.chal, tr->chal, CHALLEN);
 	strcpy(t.cuid, tr->uid);
 	strcpy(t.suid, tr->uid);
 	memrandom(t.key, DESKEYLEN);
 	t.num = AuthTc;
 	convT2M(&t, buf, k->priv);
 	t.num = AuthTs;
 	convT2M(&t, buf+TICKETLEN, k->priv);
 	return 0;
 }
 
 static int
 gettickets(Ticketreq *tr, char *buf, Key *k)
 {
 	if(getastickets(tr, buf) == 0)
 		return 0;
 	if(mktickets(tr, buf, k) == 0)
 		return 0;
 	werrstr("gettickets: %r");
 	return -1;
 }
 
 static int
 p9sk1check(Key *k)
 {
 	char *user, *dom, *pass;
 	Ticketreq tr;
 
 	user = strfindattr(k->attr, "user");
 	dom = strfindattr(k->attr, "dom");
 	if(user==nil || dom==nil){
 		werrstr("need user and dom attributes");
 		return -1;
 	}
 	if(strlen(user) >= sizeof tr.authid){
 		werrstr("user name too long");
 		return -1;
 	}
 	if(strlen(dom) >= sizeof tr.authdom){
 		werrstr("auth dom name too long");
 		return -1;
 	}
 
 	k->priv = emalloc(DESKEYLEN);
 	if(pass = strfindattr(k->privattr, "!password"))
 		passtokey(k->priv, pass);
 	else if(pass = strfindattr(k->privattr, "!hex")){
 		if(hexparse(pass, k->priv, 7) < 0){
 			werrstr("malformed !hex key data");
 			return -1;
 		}
 	}else{
 		werrstr("need !password or !hex attribute");
 		return -1;
 	}
 
 	return 0;
 }
 
 static void
 p9sk1close(Key *k)
 {
 	free(k->priv);
 	k->priv = nil;
 }
 
 static Role
 p9sk1roles[] =
 {
 	"client",	p9skclient,
 	"server",	p9skserver,
 	0
 };
 
 static Role
 p9sk2roles[] =
 {
 	"client",	p9skclient,
 	"server",	p9skserver,
 	0
 };
 
 Proto p9sk1 = {
 	"p9sk1",
 	p9sk1roles,
 	"user? dom? !password?",
 	p9sk1check,
 	p9sk1close
 };
 
 Proto p9sk2 = {
 	"p9sk2",
 	p9sk2roles
 };