ref: a1c3c34c70431447a89fbe08c3475dbfaee7b672
dir: /sys/src/cmd/auth/factotum/p9cr.c/
/*
* p9cr, vnc - textual challenge/response authentication
*
* Client protocol: [currently unimplemented]
* write challenge
* read response
*
* Server protocol:
* write user
* read challenge
* write response
*/
#include "dat.h"
enum
{
Maxchal= 64,
};
typedef struct State State;
struct State
{
Key *key;
int astype;
int asfd;
Authkey k;
Ticket t;
Ticketreq tr;
char chal[Maxchal];
int challen;
char resp[Maxchal];
int resplen;
};
enum
{
CNeedChal,
CHaveResp,
SHaveChal,
SNeedResp,
Maxphase,
};
static char *phasenames[Maxphase] =
{
[CNeedChal] "CNeedChal",
[CHaveResp] "CHaveResp",
[SHaveChal] "SHaveChal",
[SNeedResp] "SNeedResp",
};
static void
p9crclose(Fsstate *fss)
{
State *s;
s = fss->ps;
if(s->asfd >= 0){
close(s->asfd);
s->asfd = -1;
}
free(s);
}
static int getchal(State*, Fsstate*);
static int
p9crinit(Proto *p, Fsstate *fss)
{
int iscli, ret;
char *user;
State *s;
Attr *attr;
Keyinfo ki;
if((iscli = isclient(_strfindattr(fss->attr, "role"))) < 0)
return failure(fss, nil);
s = emalloc(sizeof(*s));
s->asfd = -1;
if(p == &p9cr){
s->astype = AuthChal;
s->challen = NETCHLEN;
}else if(p == &vnc){
s->astype = AuthVNC;
s->challen = Maxchal;
}else
abort();
if(iscli){
fss->phase = CNeedChal;
if(p == &p9cr)
attr = setattr(_copyattr(fss->attr), "proto=p9sk1");
else
attr = nil;
ret = findkey(&s->key, mkkeyinfo(&ki, fss, attr),
"role=client %s", p->keyprompt);
_freeattr(attr);
if(ret != RpcOk){
free(s);
return ret;
}
fss->ps = s;
}else{
if((ret = findp9authkey(&s->key, fss)) != RpcOk){
free(s);
return ret;
}
if((user = _strfindattr(fss->attr, "user")) == nil){
free(s);
return failure(fss, "no user name specified in start msg");
}
if(strlen(user) >= sizeof s->tr.uid){
free(s);
return failure(fss, "user name too long");
}
fss->ps = s;
strcpy(s->tr.uid, user);
ret = getchal(s, fss);
if(ret != RpcOk){
p9crclose(fss); /* frees s */
fss->ps = nil;
}
}
fss->phasename = phasenames;
fss->maxphase = Maxphase;
return ret;
}
static int
p9crread(Fsstate *fss, void *va, uint *n)
{
int m;
State *s;
s = fss->ps;
switch(fss->phase){
default:
return phaseerror(fss, "read");
case CHaveResp:
if(s->resplen < *n)
*n = s->resplen;
memmove(va, s->resp, *n);
fss->phase = Established;
return RpcOk;
case SHaveChal:
if(s->astype == AuthChal)
m = strlen(s->chal); /* ascii string */
else
m = s->challen; /* fixed length binary */
if(m > *n)
return toosmall(fss, m);
*n = m;
memmove(va, s->chal, m);
fss->phase = SNeedResp;
return RpcOk;
}
}
static int
p9response(Fsstate *fss, State *s)
{
Authkey *akey;
uchar buf[8];
ulong chal;
memset(buf, 0, 8);
sprint((char*)buf, "%d", atoi(s->chal));
akey = (Authkey*)s->key->priv;
if(encrypt(akey->des, buf, 8) < 0)
return failure(fss, "can't encrypt response");
chal = (buf[0]<<24)+(buf[1]<<16)+(buf[2]<<8)+buf[3];
s->resplen = snprint(s->resp, sizeof s->resp, "%.8lux", chal);
return RpcOk;
}
static uchar tab[256];
/* VNC reverses the bits of each byte before using as a des key */
static void
mktab(void)
{
int i, j, k;
static int once;
if(once)
return;
once = 1;
for(i=0; i<256; i++) {
j=i;
tab[i] = 0;
for(k=0; k<8; k++) {
tab[i] = (tab[i]<<1) | (j&1);
j >>= 1;
}
}
}
static int
vncaddkey(Key *k, int before)
{
uchar *p;
char *s;
k->priv = emalloc(8+1);
if(s = _strfindattr(k->privattr, "!password")){
mktab();
memset(k->priv, 0, 8+1);
strncpy((char*)k->priv, s, 8);
for(p=k->priv; *p; p++)
*p = tab[*p];
}else{
werrstr("no key data");
return -1;
}
return replacekey(k, before);
}
static void
vncclosekey(Key *k)
{
free(k->priv);
}
static int
vncresponse(Fsstate*, State *s)
{
DESstate des;
memmove(s->resp, s->chal, sizeof s->chal);
setupDESstate(&des, s->key->priv, nil);
desECBencrypt((uchar*)s->resp, s->challen, &des);
s->resplen = s->challen;
return RpcOk;
}
static int
p9crwrite(Fsstate *fss, void *va, uint n)
{
State *s;
char *data = va;
Authenticator a;
char resp[Maxchal];
int ret;
s = fss->ps;
switch(fss->phase){
default:
return phaseerror(fss, "write");
case CNeedChal:
if(n >= sizeof(s->chal))
return failure(fss, Ebadarg);
memset(s->chal, 0, sizeof s->chal);
memmove(s->chal, data, n);
s->challen = n;
if(s->astype == AuthChal)
ret = p9response(fss, s);
else
ret = vncresponse(fss, s);
if(ret != RpcOk)
return ret;
fss->phase = CHaveResp;
return RpcOk;
case SNeedResp:
/* send response to auth server and get ticket */
if(n > sizeof(resp))
return failure(fss, Ebadarg);
memset(resp, 0, sizeof resp);
memmove(resp, data, n);
alarm(30*1000);
if(write(s->asfd, resp, s->challen) != s->challen){
alarm(0);
return failure(fss, Easproto);
}
/* get ticket plus authenticator from auth server */
ret = _asgetresp(s->asfd, &s->t, &a, &s->k);
alarm(0);
if(ret < 0)
return failure(fss, nil);
/* check ticket */
if(s->t.num != AuthTs
|| tsmemcmp(s->t.chal, s->tr.chal, sizeof(s->t.chal)) != 0){
if (s->key->successes == 0)
disablekey(s->key);
return failure(fss, Easproto);
}
s->key->successes++;
if(a.num != AuthAc
|| tsmemcmp(a.chal, s->tr.chal, sizeof(a.chal)) != 0)
return failure(fss, Easproto);
fss->haveai = 1;
fss->ai.cuid = s->t.cuid;
fss->ai.suid = s->t.suid;
fss->ai.nsecret = 0;
fss->ai.secret = nil;
fss->phase = Established;
return RpcOk;
}
}
static int
getchal(State *s, Fsstate *fss)
{
int n;
memmove(&s->k, s->key->priv, sizeof(Authkey));
safecpy(s->tr.hostid, _strfindattr(s->key->attr, "user"), sizeof(s->tr.hostid));
safecpy(s->tr.authdom, _strfindattr(s->key->attr, "dom"), sizeof(s->tr.authdom));
s->tr.type = s->astype;
s->asfd = _authreq(&s->tr, &s->k);
if(s->asfd < 0)
return failure(fss, Easproto);
alarm(30*1000);
n = _asrdresp(s->asfd, s->chal, s->challen);
alarm(0);
if(n <= 0){
if(n == 0)
werrstr("_asrdresp short read");
return failure(fss, nil);
}
s->challen = n;
fss->phase = SHaveChal;
return RpcOk;
}
Proto p9cr =
{
.name= "p9cr",
.init= p9crinit,
.write= p9crwrite,
.read= p9crread,
.close= p9crclose,
.keyprompt= "user? !password?",
};
Proto vnc =
{
.name= "vnc",
.init= p9crinit,
.write= p9crwrite,
.read= p9crread,
.close= p9crclose,
.keyprompt= "!password?",
.addkey= vncaddkey,
};