ref: 5c1feb0ef0b795e5de71e956f9ccddcd5c4b7f21
dir: /sys/src/cmd/ssh/agent.c/
#include "ssh.h"
#include <bio.h>
typedef struct Key Key;
struct Key
{
mpint *mod;
mpint *ek;
char *comment;
};
typedef struct Achan Achan;
struct Achan
{
int open;
u32int chan; /* of remote */
uchar lbuf[4];
uint nlbuf;
uint len;
uchar *data;
int ndata;
int needeof;
int needclosed;
};
Achan achan[16];
static char*
find(char **f, int nf, char *k)
{
int i, len;
len = strlen(k);
for(i=1; i<nf; i++) /* i=1: f[0] is "key" */
if(strncmp(f[i], k, len) == 0 && f[i][len] == '=')
return f[i]+len+1;
return nil;
}
static int
listkeys(Key **kp)
{
Biobuf *b;
Key *k;
int nk;
char *p, *f[20];
int nf;
mpint *mod, *ek;
*kp = nil;
if((b = Bopen("/mnt/factotum/ctl", OREAD)) == nil)
return -1;
k = nil;
nk = 0;
while((p = Brdline(b, '\n')) != nil){
p[Blinelen(b)-1] = '\0';
nf = tokenize(p, f, nelem(f));
if(nf == 0 || strcmp(f[0], "key") != 0)
continue;
p = find(f, nf, "proto");
if(p == nil || strcmp(p, "rsa") != 0)
continue;
p = find(f, nf, "n");
if(p == nil || (mod = strtomp(p, nil, 16, nil)) == nil)
continue;
p = find(f, nf, "ek");
if(p == nil || (ek = strtomp(p, nil, 16, nil)) == nil){
mpfree(mod);
continue;
}
p = find(f, nf, "comment");
if(p == nil)
p = "";
k = erealloc(k, (nk+1)*sizeof(k[0]));
k[nk].mod = mod;
k[nk].ek = ek;
k[nk].comment = emalloc(strlen(p)+1);
strcpy(k[nk].comment, p);
nk++;
}
Bterm(b);
*kp = k;
return nk;
}
static int
dorsa(mpint *mod, mpint *exp, mpint *chal, uchar chalbuf[32])
{
int afd;
AuthRpc *rpc;
mpint *m;
char buf[4096], *p;
mpint *decr, *unpad;
USED(exp);
snprint(buf, sizeof buf, "proto=rsa service=ssh role=client");
if((afd = open("/mnt/factotum/rpc", ORDWR)) < 0){
debug(DBG_AUTH, "open /mnt/factotum/rpc: %r\n");
return -1;
}
if((rpc = auth_allocrpc(afd)) == nil){
debug(DBG_AUTH, "auth_allocrpc: %r\n");
close(afd);
return -1;
}
if(auth_rpc(rpc, "start", buf, strlen(buf)) != ARok){
debug(DBG_AUTH, "auth_rpc start failed: %r\n");
Die:
auth_freerpc(rpc);
close(afd);
return -1;
}
m = nil;
debug(DBG_AUTH, "trying factotum rsa keys\n");
while(auth_rpc(rpc, "read", nil, 0) == ARok){
debug(DBG_AUTH, "try %s\n", (char*)rpc->arg);
m = strtomp(rpc->arg, nil, 16, nil);
if(mpcmp(m, mod) == 0)
break;
mpfree(m);
m = nil;
}
if(m == nil)
goto Die;
mpfree(m);
p = mptoa(chal, 16, nil, 0);
if(p == nil){
debug(DBG_AUTH, "\tmptoa failed: %r\n");
goto Die;
}
if(auth_rpc(rpc, "write", p, strlen(p)) != ARok){
debug(DBG_AUTH, "\tauth_rpc write failed: %r\n");
free(p);
goto Die;
}
free(p);
if(auth_rpc(rpc, "read", nil, 0) != ARok){
debug(DBG_AUTH, "\tauth_rpc read failed: %r\n");
goto Die;
}
decr = strtomp(rpc->arg, nil, 16, nil);
if(decr == nil){
debug(DBG_AUTH, "\tdecr %s failed\n", rpc->arg);
goto Die;
}
debug(DBG_AUTH, "\tdecrypted %B\n", decr);
unpad = rsaunpad(decr);
if(unpad == nil){
debug(DBG_AUTH, "\tunpad %B failed\n", decr);
mpfree(decr);
goto Die;
}
debug(DBG_AUTH, "\tunpadded %B\n", unpad);
mpfree(decr);
mptoberjust(unpad, chalbuf, 32);
mpfree(unpad);
auth_freerpc(rpc);
close(afd);
return 0;
}
int
startagent(Conn *c)
{
int ret;
Msg *m;
m = allocmsg(c, SSH_CMSG_AGENT_REQUEST_FORWARDING, 0);
sendmsg(m);
m = recvmsg(c, -1);
switch(m->type){
case SSH_SMSG_SUCCESS:
debug(DBG_AUTH, "agent allocated\n");
ret = 0;
break;
case SSH_SMSG_FAILURE:
debug(DBG_AUTH, "agent failed to allocate\n");
ret = -1;
break;
default:
badmsg(m, 0);
ret = -1;
break;
}
free(m);
return ret;
}
void handlefullmsg(Conn*, Achan*);
void
handleagentmsg(Msg *m)
{
u32int chan, len;
int n;
Achan *a;
assert(m->type == SSH_MSG_CHANNEL_DATA);
debug(DBG_AUTH, "agent data\n");
debug(DBG_AUTH, "\t%.*H\n", (int)(m->ep - m->rp), m->rp);
chan = getlong(m);
len = getlong(m);
if(m->rp+len != m->ep)
sysfatal("got bad channel data");
if(chan >= nelem(achan))
error("bad channel in agent request");
a = &achan[chan];
while(m->rp < m->ep){
if(a->nlbuf < 4){
a->lbuf[a->nlbuf++] = getbyte(m);
if(a->nlbuf == 4){
a->len = (a->lbuf[0]<<24) | (a->lbuf[1]<<16) | (a->lbuf[2]<<8) | a->lbuf[3];
a->data = erealloc(a->data, a->len);
a->ndata = 0;
}
continue;
}
if(a->ndata < a->len){
n = a->len - a->ndata;
if(n > m->ep - m->rp)
n = m->ep - m->rp;
memmove(a->data+a->ndata, getbytes(m, n), n);
a->ndata += n;
}
if(a->ndata == a->len){
handlefullmsg(m->c, a);
a->nlbuf = 0;
}
}
}
void
handlefullmsg(Conn *c, Achan *a)
{
int i;
u32int chan, len, n, rt;
uchar type;
Msg *m, mm;
Msg *r;
Key *k;
int nk;
mpint *mod, *ek, *chal;
uchar sessid[16];
uchar chalbuf[32];
uchar digest[16];
DigestState *s;
static int first;
assert(a->len == a->ndata);
chan = a->chan;
mm.rp = a->data;
mm.ep = a->data+a->ndata;
mm.c = c;
m = &mm;
type = getbyte(m);
if(first == 0){
first++;
fmtinstall('H', encodefmt);
}
switch(type){
default:
debug(DBG_AUTH, "unknown msg type\n");
Failure:
debug(DBG_AUTH, "agent sending failure\n");
r = allocmsg(m->c, SSH_MSG_CHANNEL_DATA, 13);
putlong(r, chan);
putlong(r, 5);
putlong(r, 1);
putbyte(r, SSH_AGENT_FAILURE);
sendmsg(r);
return;
case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
debug(DBG_AUTH, "agent request identities\n");
nk = listkeys(&k);
if(nk < 0)
goto Failure;
len = 1+4; /* type, nk */
for(i=0; i<nk; i++){
len += 4;
len += 2+(mpsignif(k[i].ek)+7)/8;
len += 2+(mpsignif(k[i].mod)+7)/8;
len += 4+strlen(k[i].comment);
}
r = allocmsg(m->c, SSH_MSG_CHANNEL_DATA, 12+len);
putlong(r, chan);
putlong(r, len+4);
putlong(r, len);
putbyte(r, SSH_AGENT_RSA_IDENTITIES_ANSWER);
putlong(r, nk);
for(i=0; i<nk; i++){
debug(DBG_AUTH, "\t%B %B %s\n", k[i].ek, k[i].mod, k[i].comment);
putlong(r, mpsignif(k[i].mod));
putmpint(r, k[i].ek);
putmpint(r, k[i].mod);
putstring(r, k[i].comment);
mpfree(k[i].ek);
mpfree(k[i].mod);
free(k[i].comment);
}
free(k);
sendmsg(r);
break;
case SSH_AGENTC_RSA_CHALLENGE:
n = getlong(m);
USED(n); /* number of bits in key; who cares? */
ek = getmpint(m);
mod = getmpint(m);
chal = getmpint(m);
memmove(sessid, getbytes(m, 16), 16);
rt = getlong(m);
debug(DBG_AUTH, "agent challenge %B %B %B %ud (%p %p)\n",
ek, mod, chal, rt, m->rp, m->ep);
if(rt != 1 || dorsa(mod, ek, chal, chalbuf) < 0){
mpfree(ek);
mpfree(mod);
mpfree(chal);
goto Failure;
}
s = md5(chalbuf, 32, nil, nil);
md5(sessid, 16, digest, s);
r = allocmsg(m->c, SSH_MSG_CHANNEL_DATA, 12+1+16);
putlong(r, chan);
putlong(r, 4+16+1);
putlong(r, 16+1);
putbyte(r, SSH_AGENT_RSA_RESPONSE);
putbytes(r, digest, 16);
debug(DBG_AUTH, "digest %.16H\n", digest);
sendmsg(r);
mpfree(ek);
mpfree(mod);
mpfree(chal);
return;
case SSH_AGENTC_ADD_RSA_IDENTITY:
goto Failure;
/*
n = getlong(m);
pubmod = getmpint(m);
pubexp = getmpint(m);
privexp = getmpint(m);
pinversemodq = getmpint(m);
p = getmpint(m);
q = getmpint(m);
comment = getstring(m);
add to factotum;
send SSH_AGENT_SUCCESS or SSH_AGENT_FAILURE;
*/
case SSH_AGENTC_REMOVE_RSA_IDENTITY:
goto Failure;
/*
n = getlong(m);
pubmod = getmpint(m);
pubexp = getmpint(m);
tell factotum to del key
send SSH_AGENT_SUCCESS or SSH_AGENT_FAILURE;
*/
}
}
void
handleagentopen(Msg *m)
{
int i;
u32int remote;
assert(m->type == SSH_SMSG_AGENT_OPEN);
remote = getlong(m);
debug(DBG_AUTH, "agent open %d\n", remote);
for(i=0; i<nelem(achan); i++)
if(achan[i].open == 0 && achan[i].needeof == 0 && achan[i].needclosed == 0)
break;
if(i == nelem(achan)){
m = allocmsg(m->c, SSH_MSG_CHANNEL_OPEN_FAILURE, 4);
putlong(m, remote);
sendmsg(m);
return;
}
debug(DBG_AUTH, "\tremote %d is local %d\n", remote, i);
achan[i].open = 1;
achan[i].needeof = 1;
achan[i].needclosed = 1;
achan[i].nlbuf = 0;
achan[i].chan = remote;
m = allocmsg(m->c, SSH_MSG_CHANNEL_OPEN_CONFIRMATION, 8);
putlong(m, remote);
putlong(m, i);
sendmsg(m);
}
void
handleagentieof(Msg *m)
{
u32int local;
assert(m->type == SSH_MSG_CHANNEL_INPUT_EOF);
local = getlong(m);
debug(DBG_AUTH, "agent close %d\n", local);
if(local < nelem(achan)){
debug(DBG_AUTH, "\tlocal %d is remote %d\n", local, achan[local].chan);
achan[local].open = 0;
/*
m = allocmsg(m->c, SSH_MSG_CHANNEL_OUTPUT_CLOSED, 4);
putlong(m, achan[local].chan);
sendmsg(m);
*/
if(achan[local].needeof){
achan[local].needeof = 0;
m = allocmsg(m->c, SSH_MSG_CHANNEL_INPUT_EOF, 4);
putlong(m, achan[local].chan);
sendmsg(m);
}
}
}
void
handleagentoclose(Msg *m)
{
u32int local;
assert(m->type == SSH_MSG_CHANNEL_OUTPUT_CLOSED);
local = getlong(m);
debug(DBG_AUTH, "agent close %d\n", local);
if(local < nelem(achan)){
debug(DBG_AUTH, "\tlocal %d is remote %d\n", local, achan[local].chan);
if(achan[local].needclosed){
achan[local].needclosed = 0;
m = allocmsg(m->c, SSH_MSG_CHANNEL_OUTPUT_CLOSED, 4);
putlong(m, achan[local].chan);
sendmsg(m);
}
}
}