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/*
* Various files from /sys/src/cmd/auth/secstore, just enough
* to download a file at boot time.
*/
#include <u.h>
#include <libc.h>
#include <mp.h>
#include <libsec.h>
#include "drawterm.h"
static void*
emalloc(ulong n)
{
return mallocz(n, 1);
}
enum{ CHK = 16};
enum{ MAXFILESIZE = 10*1024*1024 };
enum{// PW status bits
Enabled = (1<<0),
STA = (1<<1), // extra SecurID step
};
static char testmess[] = "__secstore\tPAK\nC=%s\nm=0\n";
int
secdial(char *secstore)
{
char *p, buf[80], *f[3];
int fd, nf;
p = secstore; /* take it from writehostowner, if set there */
if(*p == 0) /* else use the authserver */
p = "$auth";
/* translate $auth ourselves.
* authaddr is something like il!host!566 or tcp!host!567.
* extract host, accounting for a change of format to something
* like il!host or tcp!host or host.
*/
if(strcmp(p, "$auth")==0){
if(authserver == nil)
return -1;
strecpy(buf, buf+sizeof buf, authserver);
nf = getfields(buf, f, nelem(f), 0, "!");
switch(nf){
default:
return -1;
case 1:
p = f[0];
break;
case 2:
case 3:
p = f[1];
break;
}
}
fd = dial(netmkaddr(p, "tcp", "5356"), 0, 0, 0);
if(fd >= 0)
return fd;
return -1;
}
int
havesecstore(char *addr, char *owner)
{
int m, n, fd;
uchar buf[500];
n = snprint((char*)buf, sizeof buf, testmess, owner);
hnputs(buf, 0x8000+n-2);
fd = secdial(addr);
if(fd < 0)
return 0;
if(write(fd, buf, n) != n || readn(fd, buf, 2) != 2){
close(fd);
return 0;
}
n = ((buf[0]&0x7f)<<8) + buf[1];
if(n+1 > sizeof buf){
werrstr("implausibly large count %d", n);
close(fd);
return 0;
}
m = readn(fd, buf, n);
close(fd);
if(m != n){
if(m >= 0)
werrstr("short read from secstore");
return 0;
}
buf[n] = 0;
if(strcmp((char*)buf, "!account expired") == 0){
werrstr("account expired");
return 0;
}
return strcmp((char*)buf, "!account exists") == 0;
}
// delimited, authenticated, encrypted connection
enum{ Maxmsg=4096 }; // messages > Maxmsg bytes are truncated
typedef struct SConn SConn;
extern SConn* newSConn(int); // arg is open file descriptor
struct SConn{
void *chan;
int secretlen;
int (*secret)(SConn*, uchar*, int);//
int (*read)(SConn*, uchar*, int); // <0 if error; errmess in buffer
int (*write)(SConn*, uchar*, int);
void (*free)(SConn*); // also closes file descriptor
};
// secret(s,b,dir) sets secret for digest, encrypt, using the secretlen
// bytes in b to form keys for the two directions;
// set dir=0 in client, dir=1 in server
// error convention: write !message in-band
#define readstr secstore_readstr
static void writerr(SConn*, char*);
static int readstr(SConn*, char*); // call with buf of size Maxmsg+1
// returns -1 upon error, with error message in buf
typedef struct ConnState {
uchar secret[SHA1dlen];
ulong seqno;
RC4state rc4;
} ConnState;
typedef struct SS{
int fd; // file descriptor for read/write of encrypted data
int alg; // if nonzero, "alg sha rc4_128"
ConnState in, out;
} SS;
static int
SC_secret(SConn *conn, uchar *sigma, int direction)
{
SS *ss = (SS*)(conn->chan);
int nsigma = conn->secretlen;
if(direction != 0){
hmac_sha1(sigma, nsigma, (uchar*)"one", 3, ss->out.secret, nil);
hmac_sha1(sigma, nsigma, (uchar*)"two", 3, ss->in.secret, nil);
}else{
hmac_sha1(sigma, nsigma, (uchar*)"two", 3, ss->out.secret, nil);
hmac_sha1(sigma, nsigma, (uchar*)"one", 3, ss->in.secret, nil);
}
setupRC4state(&ss->in.rc4, ss->in.secret, 16); // restrict to 128 bits
setupRC4state(&ss->out.rc4, ss->out.secret, 16);
ss->alg = 1;
return 0;
}
static void
hash(uchar secret[SHA1dlen], uchar *data, int len, int seqno, uchar d[SHA1dlen])
{
DigestState sha;
uchar seq[4];
seq[0] = seqno>>24;
seq[1] = seqno>>16;
seq[2] = seqno>>8;
seq[3] = seqno;
memset(&sha, 0, sizeof sha);
sha1(secret, SHA1dlen, nil, &sha);
sha1(data, len, nil, &sha);
sha1(seq, 4, d, &sha);
}
static int
verify(uchar secret[SHA1dlen], uchar *data, int len, int seqno, uchar d[SHA1dlen])
{
DigestState sha;
uchar seq[4];
uchar digest[SHA1dlen];
seq[0] = seqno>>24;
seq[1] = seqno>>16;
seq[2] = seqno>>8;
seq[3] = seqno;
memset(&sha, 0, sizeof sha);
sha1(secret, SHA1dlen, nil, &sha);
sha1(data, len, nil, &sha);
sha1(seq, 4, digest, &sha);
return memcmp(d, digest, SHA1dlen);
}
static int
SC_read(SConn *conn, uchar *buf, int n)
{
SS *ss = (SS*)(conn->chan);
uchar count[2], digest[SHA1dlen];
int len, nr;
if(read(ss->fd, count, 2) != 2 || (count[0]&0x80) == 0){
werrstr("!SC_read invalid count");
return -1;
}
len = (count[0]&0x7f)<<8 | count[1]; // SSL-style count; no pad
if(ss->alg){
len -= SHA1dlen;
if(len <= 0 || readn(ss->fd, digest, SHA1dlen) != SHA1dlen){
werrstr("!SC_read missing sha1");
return -1;
}
if(len > n || readn(ss->fd, buf, len) != len){
werrstr("!SC_read missing data");
return -1;
}
rc4(&ss->in.rc4, digest, SHA1dlen);
rc4(&ss->in.rc4, buf, len);
if(verify(ss->in.secret, buf, len, ss->in.seqno, digest) != 0){
werrstr("!SC_read integrity check failed");
return -1;
}
}else{
if(len <= 0 || len > n){
werrstr("!SC_read implausible record length");
return -1;
}
if( (nr = readn(ss->fd, buf, len)) != len){
werrstr("!SC_read expected %d bytes, but got %d", len, nr);
return -1;
}
}
ss->in.seqno++;
return len;
}
static int
SC_write(SConn *conn, uchar *buf, int n)
{
SS *ss = (SS*)(conn->chan);
uchar count[2], digest[SHA1dlen];
int len;
if(n <= 0 || n > Maxmsg+1){
werrstr("!SC_write invalid n %d", n);
return -1;
}
len = n;
if(ss->alg)
len += SHA1dlen;
count[0] = 0x80 | len>>8;
count[1] = len;
if(write(ss->fd, count, 2) != 2){
werrstr("!SC_write invalid count");
return -1;
}
if(ss->alg){
hash(ss->out.secret, buf, n, ss->out.seqno, digest);
rc4(&ss->out.rc4, digest, SHA1dlen);
rc4(&ss->out.rc4, buf, n);
if(write(ss->fd, digest, SHA1dlen) != SHA1dlen ||
write(ss->fd, buf, n) != n){
werrstr("!SC_write error on send");
return -1;
}
}else{
if(write(ss->fd, buf, n) != n){
werrstr("!SC_write error on send");
return -1;
}
}
ss->out.seqno++;
return n;
}
static void
SC_free(SConn *conn)
{
SS *ss = (SS*)(conn->chan);
close(ss->fd);
free(ss);
free(conn);
}
SConn*
newSConn(int fd)
{
SS *ss;
SConn *conn;
if(fd < 0)
return nil;
ss = (SS*)emalloc(sizeof(*ss));
conn = (SConn*)emalloc(sizeof(*conn));
ss->fd = fd;
ss->alg = 0;
conn->chan = (void*)ss;
conn->secretlen = SHA1dlen;
conn->free = SC_free;
conn->secret = SC_secret;
conn->read = SC_read;
conn->write = SC_write;
return conn;
}
static void
writerr(SConn *conn, char *s)
{
char buf[Maxmsg];
snprint(buf, Maxmsg, "!%s", s);
conn->write(conn, (uchar*)buf, strlen(buf));
}
static int
readstr(SConn *conn, char *s)
{
int n;
n = conn->read(conn, (uchar*)s, Maxmsg);
if(n >= 0){
s[n] = 0;
if(s[0] == '!'){
memmove(s, s+1, n);
n = -1;
}
}else{
strcpy(s, "read error");
}
return n;
}
static char*
getfile(SConn *conn, uchar *key, int nkey)
{
char *buf;
int nbuf, n, nr, len;
char s[Maxmsg+1], *gf;
uchar skey[SHA1dlen], ib[Maxmsg+CHK], *ibr, *ibw;
AESstate aes;
DigestState *sha;
gf = "factotum";
memset(&aes, 0, sizeof aes);
snprint(s, Maxmsg, "GET %s\n", gf);
conn->write(conn, (uchar*)s, strlen(s));
/* get file size */
s[0] = '\0';
if(readstr(conn, s) < 0){
werrstr("secstore: %r");
return nil;
}
if((len = atoi(s)) < 0){
werrstr("secstore: remote file %s does not exist", gf);
return nil;
}else if(len > MAXFILESIZE){//assert
werrstr("secstore: implausible file size %d for %s", len, gf);
return nil;
}
ibr = ibw = ib;
buf = nil;
nbuf = 0;
for(nr=0; nr < len;){
if((n = conn->read(conn, ibw, Maxmsg)) <= 0){
werrstr("secstore: empty file chunk n=%d nr=%d len=%d: %r", n, nr, len);
return nil;
}
nr += n;
ibw += n;
if(!aes.setup){ /* first time, read 16 byte IV */
if(n < 16){
werrstr("secstore: no IV in file");
return nil;
}
sha = sha1((uchar*)"aescbc file", 11, nil, nil);
sha1(key, nkey, skey, sha);
setupAESstate(&aes, skey, AESbsize, ibr);
memset(skey, 0, sizeof skey);
ibr += AESbsize;
n -= AESbsize;
}
aesCBCdecrypt(ibw-n, n, &aes);
n = ibw-ibr-CHK;
if(n > 0){
buf = realloc(buf, nbuf+n+1);
if(buf == nil)
sysfatal("out of memory");
memmove(buf+nbuf, ibr, n);
nbuf += n;
ibr += n;
}
memmove(ib, ibr, ibw-ibr);
ibw = ib + (ibw-ibr);
ibr = ib;
}
n = ibw-ibr;
if((n != CHK) || (memcmp(ib, "XXXXXXXXXXXXXXXX", CHK) != 0)){
werrstr("secstore: decrypted file failed to authenticate!");
free(buf);
return nil;
}
if(nbuf == 0){
werrstr("secstore got empty file");
return nil;
}
buf[nbuf] = '\0';
return buf;
}
static char VERSION[] = "secstore";
typedef struct PAKparams{
mpint *q, *p, *r, *g;
} PAKparams;
static PAKparams *pak;
// This group was generated by the seed EB7B6E35F7CD37B511D96C67D6688CC4DD440E1E.
static void
initPAKparams(void)
{
if(pak)
return;
pak = (PAKparams*)emalloc(sizeof(*pak));
pak->q = strtomp("E0F0EF284E10796C5A2A511E94748BA03C795C13", nil, 16, nil);
pak->p = strtomp("C41CFBE4D4846F67A3DF7DE9921A49D3B42DC33728427AB159CEC8CBBD"
"B12B5F0C244F1A734AEB9840804EA3C25036AD1B61AFF3ABBC247CD4B384224567A86"
"3A6F020E7EE9795554BCD08ABAD7321AF27E1E92E3DB1C6E7E94FAAE590AE9C48F96D9"
"3D178E809401ABE8A534A1EC44359733475A36A70C7B425125062B1142D", nil, 16, nil);
pak->r = strtomp("DF310F4E54A5FEC5D86D3E14863921E834113E060F90052AD332B3241CEF"
"2497EFA0303D6344F7C819691A0F9C4A773815AF8EAECFB7EC1D98F039F17A32A7E887"
"D97251A927D093F44A55577F4D70444AEBD06B9B45695EC23962B175F266895C67D21"
"C4656848614D888A4", nil, 16, nil);
pak->g = strtomp("2F1C308DC46B9A44B52DF7DACCE1208CCEF72F69C743ADD4D2327173444"
"ED6E65E074694246E07F9FD4AE26E0FDDD9F54F813C40CB9BCD4338EA6F242AB94CD41"
"0E676C290368A16B1A3594877437E516C53A6EEE5493A038A017E955E218E7819734E3E"
"2A6E0BAE08B14258F8C03CC1B30E0DDADFCF7CEDF0727684D3D255F1", nil, 16, nil);
}
// H = (sha(ver,C,sha(passphrase)))^r mod p,
// a hash function expensive to attack by brute force.
static void
longhash(char *ver, char *C, uchar *passwd, mpint *H)
{
uchar *Cp;
int i, n, nver, nC;
uchar buf[140], key[1];
nver = strlen(ver);
nC = strlen(C);
n = nver + nC + SHA1dlen;
Cp = (uchar*)emalloc(n);
memmove(Cp, ver, nver);
memmove(Cp+nver, C, nC);
memmove(Cp+nver+nC, passwd, SHA1dlen);
for(i = 0; i < 7; i++){
key[0] = 'A'+i;
hmac_sha1(Cp, n, key, sizeof key, buf+i*SHA1dlen, nil);
}
memset(Cp, 0, n);
free(Cp);
betomp(buf, sizeof buf, H);
mpmod(H, pak->p, H);
mpexp(H, pak->r, pak->p, H);
}
// Hi = H^-1 mod p
static char *
PAK_Hi(char *C, char *passphrase, mpint *H, mpint *Hi)
{
uchar passhash[SHA1dlen];
sha1((uchar *)passphrase, strlen(passphrase), passhash, nil);
initPAKparams();
longhash(VERSION, C, passhash, H);
mpinvert(H, pak->p, Hi);
return mptoa(Hi, 64, nil, 0);
}
// another, faster, hash function for each party to
// confirm that the other has the right secrets.
static void
shorthash(char *mess, char *C, char *S, char *m, char *mu, char *sigma, char *Hi, uchar *digest)
{
SHA1state *state;
state = sha1((uchar*)mess, strlen(mess), 0, 0);
state = sha1((uchar*)C, strlen(C), 0, state);
state = sha1((uchar*)S, strlen(S), 0, state);
state = sha1((uchar*)m, strlen(m), 0, state);
state = sha1((uchar*)mu, strlen(mu), 0, state);
state = sha1((uchar*)sigma, strlen(sigma), 0, state);
state = sha1((uchar*)Hi, strlen(Hi), 0, state);
state = sha1((uchar*)mess, strlen(mess), 0, state);
state = sha1((uchar*)C, strlen(C), 0, state);
state = sha1((uchar*)S, strlen(S), 0, state);
state = sha1((uchar*)m, strlen(m), 0, state);
state = sha1((uchar*)mu, strlen(mu), 0, state);
state = sha1((uchar*)sigma, strlen(sigma), 0, state);
sha1((uchar*)Hi, strlen(Hi), digest, state);
}
// On input, conn provides an open channel to the server;
// C is the name this client calls itself;
// pass is the user's passphrase
// On output, session secret has been set in conn
// (unless return code is negative, which means failure).
// If pS is not nil, it is set to the (alloc'd) name the server calls itself.
static int
PAKclient(SConn *conn, char *C, char *pass, char **pS)
{
char *mess, *mess2, *eol, *S, *hexmu, *ks, *hexm, *hexsigma = nil, *hexHi;
char kc[2*SHA1dlen+1];
uchar digest[SHA1dlen];
int rc = -1, n;
mpint *x, *m = mpnew(0), *mu = mpnew(0), *sigma = mpnew(0);
mpint *H = mpnew(0), *Hi = mpnew(0);
hexHi = PAK_Hi(C, pass, H, Hi);
// random 1<=x<=q-1; send C, m=g**x H
x = mprand(164, genrandom, nil);
mpmod(x, pak->q, x);
if(mpcmp(x, mpzero) == 0)
mpassign(mpone, x);
mpexp(pak->g, x, pak->p, m);
mpmul(m, H, m);
mpmod(m, pak->p, m);
hexm = mptoa(m, 64, nil, 0);
mess = (char*)emalloc(2*Maxmsg+2);
mess2 = mess+Maxmsg+1;
snprint(mess, Maxmsg, "%s\tPAK\nC=%s\nm=%s\n", VERSION, C, hexm);
conn->write(conn, (uchar*)mess, strlen(mess));
// recv g**y, S, check hash1(g**xy)
if(readstr(conn, mess) < 0){
fprint(2, "error: %s\n", mess);
writerr(conn, "couldn't read g**y");
goto done;
}
eol = strchr(mess, '\n');
if(strncmp("mu=", mess, 3) != 0 || !eol || strncmp("\nk=", eol, 3) != 0){
writerr(conn, "verifier syntax error");
goto done;
}
hexmu = mess+3;
*eol = 0;
ks = eol+3;
eol = strchr(ks, '\n');
if(!eol || strncmp("\nS=", eol, 3) != 0){
writerr(conn, "verifier syntax error for secstore 1.0");
goto done;
}
*eol = 0;
S = eol+3;
eol = strchr(S, '\n');
if(!eol){
writerr(conn, "verifier syntax error for secstore 1.0");
goto done;
}
*eol = 0;
if(pS)
*pS = strdup(S);
strtomp(hexmu, nil, 64, mu);
mpexp(mu, x, pak->p, sigma);
hexsigma = mptoa(sigma, 64, nil, 0);
shorthash("server", C, S, hexm, hexmu, hexsigma, hexHi, digest);
enc64(kc, sizeof kc, digest, SHA1dlen);
if(strcmp(ks, kc) != 0){
writerr(conn, "verifier didn't match");
goto done;
}
// send hash2(g**xy)
shorthash("client", C, S, hexm, hexmu, hexsigma, hexHi, digest);
enc64(kc, sizeof kc, digest, SHA1dlen);
snprint(mess2, Maxmsg, "k'=%s\n", kc);
conn->write(conn, (uchar*)mess2, strlen(mess2));
// set session key
shorthash("session", C, S, hexm, hexmu, hexsigma, hexHi, digest);
memset(hexsigma, 0, strlen(hexsigma));
n = conn->secret(conn, digest, 0);
memset(digest, 0, SHA1dlen);
if(n < 0){//assert
writerr(conn, "can't set secret");
goto done;
}
rc = 0;
done:
mpfree(x);
mpfree(sigma);
mpfree(mu);
mpfree(m);
mpfree(Hi);
mpfree(H);
free(hexsigma);
free(hexHi);
free(hexm);
free(mess);
return rc;
}
char*
secstorefetch(char *addr, char *owner, char *password)
{
int fd;
char *rv;
char s[Maxmsg+1], bye[10];
SConn *conn;
char *pass, *sta;
sta = nil;
conn = nil;
rv = nil;
if(password != nil && *password)
pass = strdup(password);
else
pass = readcons("secstore password", nil, 1);
if(pass==nil || strlen(pass)==0){
werrstr("cancel");
goto Out;
}
if((fd = secdial(addr)) < 0)
goto Out;
if((conn = newSConn(fd)) == nil)
goto Out;
if(PAKclient(conn, owner, pass, nil) < 0){
werrstr("password mistyped?");
goto Out;
}
if(readstr(conn, s) < 0)
goto Out;
if(strcmp(s, "STA") == 0){
sta = readcons("STA PIN+SecureID", nil, 1);
if(sta==nil || strlen(sta)==0){
werrstr("cancel");
goto Out;
}
if(strlen(sta) >= sizeof s - 3){
werrstr("STA response too long");
goto Out;
}
strcpy(s+3, sta);
conn->write(conn, (uchar*)s, strlen(s));
readstr(conn, s);
}
if(strcmp(s, "OK") !=0){
werrstr("%s", s);
goto Out;
}
if((rv = getfile(conn, (uchar*)pass, strlen(pass))) == nil)
goto Out;
strcpy(bye, "BYE");
conn->write(conn, (uchar*)bye, 3);
Out:
if(conn)
conn->free(conn);
if(pass)
free(pass);
if(sta)
free(sta);
return rv;
}