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proxychains-ng
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fix potential double-close of file descriptors 

in case of an error condition, both start_chain() and chain_step()
were closing the fd to be acted upon, without setting it to -1,
and the function calling them would close them again.

this could affect multi-threaded applications that opened new fds
between the first and the second close, invalidating those fds
in the targeted app.

patch loosely based on report and PR by @jhfrontz.

closes #542
pull/476/merge
rofl0r 2024-01-02 14:45:25 +00:00
parent 0279dda939
commit 1d0bc349eb
1 changed files with 26 additions and 21 deletions
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47
src/core.c
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@ -462,8 +462,10 @@ static int start_chain(int *fd, proxy_data * pd, char *begin_mark) {
error1:
proxychains_write_log(TP " timeout\n");
error:
if(*fd != -1)
if(*fd != -1) {
close(*fd);
*fd = -1;
}
return SOCKET_ERROR;
}
@ -520,9 +522,9 @@ static unsigned int calc_alive(proxy_data * pd, unsigned int proxy_count) {
}
static int chain_step(int ns, proxy_data * pfrom, proxy_data * pto) {
static int chain_step(int *ns, proxy_data * pfrom, proxy_data * pto) {
int retcode = -1;
char *hostname;
char *hostname, *errmsg = 0;
char hostname_buf[MSG_LEN_MAX];
char ip_buf[INET6_ADDRSTRLEN];
int v6 = pto->ip.is_v6;
@ -536,31 +538,34 @@ static int chain_step(int ns, proxy_data * pfrom, proxy_data * pto) {
usenumericip:
if(!inet_ntop(v6?AF_INET6:AF_INET,pto->ip.addr.v6,ip_buf,sizeof ip_buf)) {
pto->ps = DOWN_STATE;
proxychains_write_log("<--ip conversion error!\n");
close(ns);
return SOCKET_ERROR;
errmsg = "<--ip conversion error!\n";
retcode = SOCKET_ERROR;
goto err;
}
hostname = ip_buf;
}
proxychains_write_log(TP " %s:%d ", hostname, htons(pto->port));
retcode = tunnel_to(ns, pto->ip, pto->port, pfrom->pt, pfrom->user, pfrom->pass);
retcode = tunnel_to(*ns, pto->ip, pto->port, pfrom->pt, pfrom->user, pfrom->pass);
switch (retcode) {
case SUCCESS:
pto->ps = BUSY_STATE;
break;
case BLOCKED:
pto->ps = BLOCKED_STATE;
proxychains_write_log("<--denied\n");
close(ns);
break;
errmsg = "<--denied\n";
goto err;
case SOCKET_ERROR:
pto->ps = DOWN_STATE;
proxychains_write_log("<--socket error or timeout!\n");
close(ns);
break;
errmsg = "<--socket error or timeout!\n";
goto err;
}
return retcode;
err:
if(errmsg) proxychains_write_log(errmsg);
if(*ns != -1) close(*ns);
*ns = -1;
return retcode;
}
int connect_proxy_chain(int sock, ip_type target_ip,
@ -596,7 +601,7 @@ int connect_proxy_chain(int sock, ip_type target_ip,
p2 = select_proxy(FIFOLY, pd, proxy_count, &offset);
if(!p2)
break;
if(SUCCESS != chain_step(ns, p1, p2)) {
if(SUCCESS != chain_step(&ns, p1, p2)) {
PDEBUG("GOTO AGAIN 1\n");
goto again;
}
@ -605,7 +610,7 @@ int connect_proxy_chain(int sock, ip_type target_ip,
//proxychains_write_log(TP);
p3->ip = target_ip;
p3->port = target_port;
if(SUCCESS != chain_step(ns, p1, p3))
if(SUCCESS != chain_step(&ns, p1, p3))
goto error;
break;
@ -643,7 +648,7 @@ int connect_proxy_chain(int sock, ip_type target_ip,
/* Try from the beginning to where we started */
offset = 0;
continue;
} else if(SUCCESS != chain_step(ns, p1, p2)) {
} else if(SUCCESS != chain_step(&ns, p1, p2)) {
PDEBUG("GOTO AGAIN 1\n");
goto again;
} else
@ -655,7 +660,7 @@ int connect_proxy_chain(int sock, ip_type target_ip,
p3->port = target_port;
proxychains_proxy_offset = offset+1;
PDEBUG("pd_offset = %d, curr_len = %d\n", proxychains_proxy_offset, curr_len);
if(SUCCESS != chain_step(ns, p1, p3))
if(SUCCESS != chain_step(&ns, p1, p3))
goto error;
break;
@ -673,7 +678,7 @@ int connect_proxy_chain(int sock, ip_type target_ip,
while(offset < proxy_count) {
if(!(p2 = select_proxy(FIFOLY, pd, proxy_count, &offset)))
break;
if(SUCCESS != chain_step(ns, p1, p2)) {
if(SUCCESS != chain_step(&ns, p1, p2)) {
PDEBUG("chain_step failed\n");
goto error_strict;
}
@ -682,7 +687,7 @@ int connect_proxy_chain(int sock, ip_type target_ip,
//proxychains_write_log(TP);
p3->ip = target_ip;
p3->port = target_port;
if(SUCCESS != chain_step(ns, p1, p3))
if(SUCCESS != chain_step(&ns, p1, p3))
goto error;
break;
@ -698,7 +703,7 @@ int connect_proxy_chain(int sock, ip_type target_ip,
while(++curr_len < max_chain) {
if(!(p2 = select_proxy(RANDOMLY, pd, proxy_count, &offset)))
goto error_more;
if(SUCCESS != chain_step(ns, p1, p2)) {
if(SUCCESS != chain_step(&ns, p1, p2)) {
PDEBUG("GOTO AGAIN 2\n");
goto again;
}
@ -707,7 +712,7 @@ int connect_proxy_chain(int sock, ip_type target_ip,
//proxychains_write_log(TP);
p3->ip = target_ip;
p3->port = target_port;
if(SUCCESS != chain_step(ns, p1, p3))
if(SUCCESS != chain_step(&ns, p1, p3))
goto error;
}