ref: bf4f158707ebfeacb15826ad4283ff247d7d81ae
dir: /sys/src/cmd/auth/factotum/p9sk1.c/
/*
* p9sk1, dp9ik - Plan 9 secret (private) key authentication.
* dp9ik uses AuthPAK diffie hellman key exchange with the
* auth server to protect the password derived key from offline
* dictionary attacks.
*
* Client protocol:
* write challenge[challen]
* read pakreq[ticketreqlen + pakylen] (dp9ik only)
* write paky[pakylen]
* read tickreq[tickreqlen] (p9sk1 only)
* write ticket + authenticator
* read authenticator
*
* Server protocol:
* read challenge[challen]
* write pakreq[ticketreqlen + pakylen] (dp9ik only)
* read paky[pakylen]
* write tickreq[tickreqlen] (p9sk1 only)
* read ticket + authenticator
* write authenticator
*
* Login protocol:
* write user
* write password
*/
#include "dat.h"
struct State
{
Key *key;
Ticket t;
Ticketreq tr;
Authkey k;
PAKpriv p;
char cchal[CHALLEN];
uchar y[PAKYLEN], rand[2*NONCELEN];
char tbuf[MAXTICKETLEN + MAXAUTHENTLEN];
int tbuflen;
uchar *secret;
int speakfor;
};
enum
{
/* client phases */
CHaveChal,
CNeedPAKreq, /* dp9ik only */
CHavePAKy,
CNeedTreq, /* p9sk1 only */
CHaveTicket,
CNeedAuth,
/* server phases */
SNeedChal,
SHavePAKreq, /* dp9ik only */
SNeedPAKy,
SHaveTreq, /* p9sk1 only */
SNeedTicket,
SHaveAuth,
/* login phases */
SNeedUser,
SNeedPass,
Maxphase,
};
static char *phasenames[Maxphase] =
{
[CHaveChal] "CHaveChal",
[CNeedPAKreq] "CNeedPAKreq",
[CHavePAKy] "CHavePAKy",
[CNeedTreq] "CNeedTreq",
[CHaveTicket] "CHaveTicket",
[CNeedAuth] "CNeedAuth",
[SNeedChal] "SNeedChal",
[SHavePAKreq] "SHavePAKreq",
[SNeedPAKy] "SNeedPAKy",
[SHaveTreq] "SHaveTreq",
[SNeedTicket] "SNeedTicket",
[SHaveAuth] "SHaveAuth",
[SNeedUser] "SNeedUser",
[SNeedPass] "SNeedPass",
};
static int gettickets(State*, uchar*, char*, int);
static int
p9skinit(Proto *p, Fsstate *fss)
{
State *s;
int iscli, ret;
Key *k;
Keyinfo ki;
Attr *attr;
char *role;
role = _strfindattr(fss->attr, "role");
if(role != nil && strcmp(role, "login") == 0)
iscli = 0;
else if((iscli = isclient(role)) < 0)
return failure(fss, nil);
s = emalloc(sizeof *s);
fss = fss;
fss->phasename = phasenames;
fss->maxphase = Maxphase;
fss->proto = p;
if(iscli){
fss->phase = CHaveChal;
genrandom((uchar*)s->cchal, CHALLEN);
}else{
fss->phase = SNeedChal;
s->tr.type = AuthTreq;
attr = setattr(_copyattr(fss->attr), "proto=%q", p->name);
if(strcmp(role, "login") == 0){
attr = setattr(attr, "role=server");
fss->phase = SNeedUser;
}
mkkeyinfo(&ki, fss, attr);
ki.user = nil;
ret = findkey(&k, &ki, "user? dom?");
_freeattr(attr);
if(ret != RpcOk){
free(s);
return ret;
}
safecpy(s->tr.authid, _strfindattr(k->attr, "user"), sizeof(s->tr.authid));
safecpy(s->tr.authdom, _strfindattr(k->attr, "dom"), sizeof(s->tr.authdom));
s->key = k;
memmove(&s->k, k->priv, sizeof(Authkey));
genrandom((uchar*)s->tr.chal, sizeof s->tr.chal);
}
s->tbuflen = 0;
s->secret = nil;
fss->ps = s;
return RpcOk;
}
static int
establish(Fsstate *fss)
{
AuthInfo *ai;
State *s;
s = fss->ps;
ai = &fss->ai;
ai->cuid = s->t.cuid;
ai->suid = s->t.suid;
if(fss->proto == &dp9ik){
static char info[] = "Plan 9 session secret";
ai->nsecret = 256;
ai->secret = emalloc(ai->nsecret);
hkdf_x( s->rand, 2*NONCELEN,
(uchar*)info, sizeof(info)-1,
s->t.key, NONCELEN,
ai->secret, ai->nsecret,
hmac_sha2_256, SHA2_256dlen);
} else {
ai->nsecret = 8;
ai->secret = emalloc(ai->nsecret);
des56to64((uchar*)s->t.key, ai->secret);
}
s->secret = ai->secret;
fss->haveai = 1;
fss->phase = Established;
return RpcOk;
}
static int
p9skread(Fsstate *fss, void *a, uint *n)
{
int m;
State *s;
s = fss->ps;
switch(fss->phase){
default:
return phaseerror(fss, "read");
case CHaveChal:
m = CHALLEN;
if(*n < m)
return toosmall(fss, m);
*n = m;
memmove(a, s->cchal, m);
if(fss->proto == &dp9ik)
fss->phase = CNeedPAKreq;
else
fss->phase = CNeedTreq;
return RpcOk;
case SHavePAKreq:
m = TICKREQLEN + PAKYLEN;
if(*n < m)
return toosmall(fss, m);
s->tr.type = AuthPAK;
*n = convTR2M(&s->tr, a, *n);
authpak_new(&s->p, &s->k, (uchar*)a + *n, 1);
*n += PAKYLEN;
fss->phase = SNeedPAKy;
return RpcOk;
case CHavePAKy:
m = PAKYLEN;
if(*n < m)
return toosmall(fss, m);
*n = m;
memmove(a, s->y, m);
fss->phase = CHaveTicket;
return RpcOk;
case SHaveTreq:
m = TICKREQLEN;
if(*n < m)
return toosmall(fss, m);
s->tr.type = AuthTreq;
*n = convTR2M(&s->tr, a, *n);
fss->phase = SNeedTicket;
return RpcOk;
case CHaveTicket:
m = s->tbuflen;
if(*n < m)
return toosmall(fss, m);
*n = m;
memmove(a, s->tbuf, m);
fss->phase = CNeedAuth;
return RpcOk;
case SHaveAuth:
m = s->tbuflen;
if(*n < m)
return toosmall(fss, m);
*n = m;
memmove(a, s->tbuf, m);
return establish(fss);
}
}
static int
p9skwrite(Fsstate *fss, void *a, uint n)
{
int m, ret, sret;
char tbuf[2*PAKYLEN+2*MAXTICKETLEN], *user;
Attr *attr;
State *s;
Key *srvkey;
Keyinfo ki;
Authenticator auth;
s = fss->ps;
switch(fss->phase){
default:
return phaseerror(fss, "write");
case SNeedChal:
m = CHALLEN;
if(n < m)
return toosmall(fss, m);
memmove(s->cchal, a, m);
if(fss->proto == &dp9ik)
fss->phase = SHavePAKreq;
else
fss->phase = SHaveTreq;
return RpcOk;
case CNeedPAKreq:
m = TICKREQLEN+PAKYLEN;
if(n < m)
return toosmall(fss, m);
case CNeedTreq:
m = TICKREQLEN;
if(n < m)
return toosmall(fss, m);
m = convM2TR(a, n, &s->tr);
if(m <= 0 || s->tr.type != (fss->phase==CNeedPAKreq ? AuthPAK : AuthTreq))
return failure(fss, Easproto);
if(s->key != nil)
closekey(s->key);
attr = _delattr(_delattr(_copyattr(fss->attr), "role"), "user");
attr = setattr(attr, "proto=%q", fss->proto->name);
user = _strfindattr(fss->attr, "user");
/*
* If our client is the user who started factotum (client==owner), then
* he can use whatever keys we have to speak as whoever he pleases.
* If, on the other hand, we're speaking on behalf of someone else,
* we will only vouch for their name on the local system.
*
* We do the sysuser findkey second so that if we return RpcNeedkey,
* the correct key information gets asked for.
*/
srvkey = nil;
s->speakfor = 0;
sret = RpcFailure;
if(user==nil || strcmp(user, fss->sysuser) == 0){
mkkeyinfo(&ki, fss, attr);
ki.user = nil;
sret = findkey(&srvkey, &ki,
"role=speakfor dom=%q user?", s->tr.authdom);
}
if(user != nil)
attr = setattr(attr, "user=%q", user);
mkkeyinfo(&ki, fss, attr);
ret = findkey(&s->key, &ki,
"role=client dom=%q %s", s->tr.authdom, fss->proto->keyprompt);
if(ret == RpcOk)
closekey(srvkey);
else if(sret == RpcOk){
s->key = srvkey;
s->speakfor = 1;
}else if(ret == RpcConfirm || sret == RpcConfirm){
_freeattr(attr);
return RpcConfirm;
}else{
_freeattr(attr);
return ret;
}
/* fill in the rest of the request */
safecpy(s->tr.hostid, _strfindattr(s->key->attr, "user"), sizeof s->tr.hostid);
if(s->speakfor)
safecpy(s->tr.uid, fss->sysuser, sizeof s->tr.uid);
else
safecpy(s->tr.uid, s->tr.hostid, sizeof s->tr.uid);
/* get tickets from authserver or invent if we can */
memmove(&s->k, s->key->priv, sizeof(Authkey));
if(fss->phase == CNeedPAKreq)
ret = gettickets(s, (uchar*)a + m, tbuf, sizeof(tbuf));
else
ret = gettickets(s, nil, tbuf, sizeof(tbuf));
if(ret <= 0){
_freeattr(attr);
return failure(fss, nil);
}
m = convM2T(tbuf, ret, &s->t, &s->k);
if(m <= 0 || (fss->proto == &dp9ik && s->t.form == 0)){
_freeattr(attr);
return failure(fss, Easproto);
}
if(s->t.num != AuthTc){
if(s->key->successes == 0 && !s->speakfor)
disablekey(s->key);
if(askforkeys && !s->speakfor){
snprint(fss->keyinfo, sizeof fss->keyinfo,
"%A %s", attr, fss->proto->keyprompt);
_freeattr(attr);
return RpcNeedkey;
}else{
_freeattr(attr);
return failure(fss, Ebadkey);
}
}
s->key->successes++;
_freeattr(attr);
ret -= m;
memmove(s->tbuf, tbuf+m, ret);
genrandom(s->rand, NONCELEN);
auth.num = AuthAc;
memmove(auth.chal, s->tr.chal, CHALLEN);
memmove(auth.rand, s->rand, NONCELEN);
ret += convA2M(&auth, s->tbuf+ret, sizeof(s->tbuf)-ret, &s->t);
s->tbuflen = ret;
if(fss->phase == CNeedPAKreq)
fss->phase = CHavePAKy;
else
fss->phase = CHaveTicket;
return RpcOk;
case SNeedPAKy:
m = PAKYLEN;
if(n < m)
return toosmall(fss, m);
if(authpak_finish(&s->p, &s->k, (uchar*)a))
return failure(fss, Easproto);
fss->phase = SNeedTicket;
return RpcOk;
case SNeedTicket:
m = convM2T(a, n, &s->t, &s->k);
if(m <= 0 || convM2A((char*)a+m, n-m, &auth, &s->t) <= 0)
return toosmall(fss, MAXTICKETLEN + MAXAUTHENTLEN);
if(fss->proto == &dp9ik && s->t.form == 0)
return failure(fss, Easproto);
if(s->t.num != AuthTs
|| tsmemcmp(s->t.chal, s->tr.chal, CHALLEN) != 0)
return failure(fss, Easproto);
if(auth.num != AuthAc
|| tsmemcmp(auth.chal, s->tr.chal, CHALLEN) != 0)
return failure(fss, Easproto);
memmove(s->rand, auth.rand, NONCELEN);
genrandom(s->rand + NONCELEN, NONCELEN);
auth.num = AuthAs;
memmove(auth.chal, s->cchal, CHALLEN);
memmove(auth.rand, s->rand + NONCELEN, NONCELEN);
s->tbuflen = convA2M(&auth, s->tbuf, sizeof(s->tbuf), &s->t);
fss->phase = SHaveAuth;
return RpcOk;
case CNeedAuth:
m = convM2A(a, n, &auth, &s->t);
if(m <= 0)
return toosmall(fss, -m);
if(auth.num != AuthAs
|| tsmemcmp(auth.chal, s->cchal, CHALLEN) != 0)
return failure(fss, Easproto);
memmove(s->rand+NONCELEN, auth.rand, NONCELEN);
return establish(fss);
case SNeedUser:
if(n >= sizeof(s->tr.hostid))
return failure(fss, "user id too long");
strncpy(s->tr.hostid, a, n);
s->tr.hostid[n] = 0;
strncpy(s->tr.uid, a, n);
s->tr.uid[n] = 0;
fss->phase = SNeedPass;
return RpcOk;
case SNeedPass:
{
Authkey ks;
uchar tk[NONCELEN];
char pass[PASSWDLEN];
if(n >= sizeof(pass))
return failure(fss, "password too long");
/* save server key */
memmove(&ks, &s->k, sizeof(ks));
/* derive client key */
strncpy(pass, a, n);
pass[n] = 0;
passtokey(&s->k, pass);
memset(pass, 0, sizeof(pass));
if(fss->proto == &dp9ik){
uchar ys[PAKYLEN];
PAKpriv ps;
authpak_hash(&s->k, s->tr.hostid);
authpak_new(&ps, &ks, ys, 1);
ret = gettickets(s, ys, tbuf, sizeof(tbuf));
if(ret > 0 && authpak_finish(&ps, &ks, s->y))
return failure(fss, Easproto);
} else {
ret = gettickets(s, nil, tbuf, sizeof(tbuf));
}
if(ret <= 0)
return failure(fss, nil);
/* verify client ticket */
m = convM2T(tbuf, ret, &s->t, &s->k);
if(m <= 0 || (fss->proto == &dp9ik && s->t.form == 0))
return failure(fss, Easproto);
if(s->t.num != AuthTc || tsmemcmp(s->t.chal, s->tr.chal, CHALLEN) != 0)
return failure(fss, Ebadkey);
memmove(tk, s->t.key, sizeof(tk));
/* restore sever key */
memmove(&s->k, &ks, sizeof(ks));
/* verify server ticket */
m = convM2T(tbuf+m, ret-m, &s->t, &s->k);
if(m <= 0 || (fss->proto == &dp9ik && s->t.form == 0))
return failure(fss, Easproto);
if(s->t.num != AuthTs || tsmemcmp(s->t.chal, s->tr.chal, CHALLEN) != 0
|| tsmemcmp(tk, s->t.key, sizeof(tk)) != 0)
return failure(fss, Ebadkey);
}
genrandom(s->rand, 2*NONCELEN);
return establish(fss);
}
}
static void
p9skclose(Fsstate *fss)
{
State *s;
s = fss->ps;
if(s->secret != nil){
free(s->secret);
s->secret = nil;
}
if(s->key != nil){
closekey(s->key);
s->key = nil;
}
memset(s, 0, sizeof(State));
free(s);
}
static int
p9skaddkey(Key *k, int before)
{
Authkey *akey;
char *s, *u;
u = _strfindattr(k->attr, "user");
if(u == nil){
werrstr("no user attribute");
return -1;
}
akey = emalloc(sizeof(Authkey));
if(s = _strfindattr(k->privattr, "!hex")){
if(k->proto == &dp9ik){
if(dec16(akey->aes, AESKEYLEN, s, strlen(s)) != AESKEYLEN){
free(akey);
werrstr("malformed key data");
return -1;
}
} else {
if(dec16((uchar*)akey->des, DESKEYLEN, s, strlen(s)) != DESKEYLEN){
free(akey);
werrstr("malformed key data");
return -1;
}
}
}else if(s = _strfindattr(k->privattr, "!password")){
passtokey(akey, s);
}else{
werrstr("no key data");
free(akey);
return -1;
}
if(k->proto == &dp9ik)
authpak_hash(akey, u);
else
memset(akey->aes, 0, AESKEYLEN); /* don't attempt AuthPAK for p9sk1 key */
k->priv = akey;
return replacekey(k, before);
}
static void
p9skclosekey(Key *k)
{
if(k->priv == nil)
return;
memset(k->priv, 0, sizeof(Authkey));
free(k->priv);
}
static int
mkservertickets(State *s, uchar *y, char *tbuf, int tbuflen)
{
Ticketreq *tr = &s->tr;
Ticket t;
int ret;
if(strcmp(tr->authid, tr->hostid) != 0)
return -1;
/* this keeps creating accounts on martha from working. -- presotto
if(strcmp(tr->uid, "none") == 0)
return -1;
*/
memset(&t, 0, sizeof(t));
ret = 0;
if(y != nil){
t.form = 1;
authpak_new(&s->p, &s->k, s->y, 0);
authpak_finish(&s->p, &s->k, y);
}
memmove(t.chal, tr->chal, CHALLEN);
strcpy(t.cuid, tr->uid);
strcpy(t.suid, tr->uid);
genrandom((uchar*)t.key, sizeof(t.key));
t.num = AuthTc;
ret += convT2M(&t, tbuf+ret, tbuflen-ret, &s->k);
t.num = AuthTs;
ret += convT2M(&t, tbuf+ret, tbuflen-ret, &s->k);
memset(&t, 0, sizeof(t));
return ret;
}
static int
getastickets(State *s, uchar *y, char *tbuf, int tbuflen)
{
Ticketreq *tr = &s->tr;
int asfd, rv;
char *dom;
if((dom = _strfindattr(s->key->attr, "dom")) == nil){
werrstr("auth key has no domain");
return -1;
}
asfd = _authdial(dom);
if(asfd < 0)
return -1;
alarm(30*1000);
if(y != nil){
rv = -1;
s->tr.type = AuthPAK;
if(_asrequest(asfd, tr) != 0 || write(asfd, y, PAKYLEN) != PAKYLEN)
goto Out;
authpak_new(&s->p, &s->k, (uchar*)tbuf, 1);
if(write(asfd, tbuf, PAKYLEN) != PAKYLEN)
goto Out;
if(_asrdresp(asfd, tbuf, 2*PAKYLEN) != 2*PAKYLEN)
goto Out;
memmove(s->y, tbuf, PAKYLEN);
if(authpak_finish(&s->p, &s->k, (uchar*)tbuf+PAKYLEN))
goto Out;
}
s->tr.type = AuthTreq;
rv = _asgetticket(asfd, tr, tbuf, tbuflen);
Out:
alarm(0);
close(asfd);
return rv;
}
static int
gettickets(State *s, uchar *y, char *tbuf, int tbuflen)
{
int ret;
if(s->tr.authdom[0] == 0
|| s->tr.authid[0] == 0
|| s->tr.hostid[0] == 0
|| s->tr.uid[0] == 0){
werrstr("bad ticket request");
return -1;
}
ret = getastickets(s, y, tbuf, tbuflen);
if(ret > 0)
return ret;
return mkservertickets(s, y, tbuf, tbuflen);
}
Proto p9sk1 = {
.name= "p9sk1",
.init= p9skinit,
.write= p9skwrite,
.read= p9skread,
.close= p9skclose,
.addkey= p9skaddkey,
.closekey= p9skclosekey,
.keyprompt= "user? !password?"
};
Proto dp9ik = {
.name= "dp9ik",
.init= p9skinit,
.write= p9skwrite,
.read= p9skread,
.close= p9skclose,
.addkey= p9skaddkey,
.closekey= p9skclosekey,
.keyprompt= "user? !password?"
};