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fw-daemon/socks_server_chain.go

263 lines
6.0 KiB

package main
import (
"io"
"net"
"os"
"sync"
"github.com/subgraph/fw-daemon/socks5"
"github.com/subgraph/go-procsnitch"
"strconv"
)
type socksChainConfig struct {
TargetSocksNet string
TargetSocksAddr string
ListenSocksNet string
ListenSocksAddr string
}
type socksChain struct {
cfg *socksChainConfig
fw *Firewall
listener net.Listener
wg *sync.WaitGroup
procInfo procsnitch.ProcInfo
}
type socksChainSession struct {
cfg *socksChainConfig
clientConn net.Conn
upstreamConn net.Conn
req *socks5.Request
bndAddr *socks5.Address
optData []byte
procInfo procsnitch.ProcInfo
server *socksChain
}
const (
socksVerdictDrop = 1
socksVerdictAccept = 2
)
type pendingSocksConnection struct {
pol *Policy
hname string
destIP net.IP
destPort uint16
pinfo *procsnitch.Info
verdict chan int
}
func (sc *pendingSocksConnection) policy() *Policy {
return sc.pol
}
func (sc *pendingSocksConnection) procInfo() *procsnitch.Info {
return sc.pinfo
}
func (sc *pendingSocksConnection) hostname() string {
return sc.hname
}
func (sc *pendingSocksConnection) dst() net.IP {
return sc.destIP
}
func (sc *pendingSocksConnection) dstPort() uint16 {
return sc.destPort
}
func (sc *pendingSocksConnection) deliverVerdict(v int) {
sc.verdict <- v
close(sc.verdict)
}
func (sc *pendingSocksConnection) accept() { sc.deliverVerdict(socksVerdictAccept) }
func (sc *pendingSocksConnection) drop() { sc.deliverVerdict(socksVerdictDrop) }
func (sc *pendingSocksConnection) print() string { return "socks connection" }
func NewSocksChain(cfg *socksChainConfig, wg *sync.WaitGroup, fw *Firewall) *socksChain {
chain := socksChain{
cfg: cfg,
fw: fw,
wg: wg,
procInfo: procsnitch.SystemProcInfo{},
}
return &chain
}
// Start initializes the SOCKS 5 server and starts
// accepting connections.
func (s *socksChain) start() {
var err error
s.listener, err = net.Listen(s.cfg.ListenSocksNet, s.cfg.ListenSocksAddr)
if err != nil {
log.Errorf("ERR/socks: Failed to listen on the socks address: %v", err)
os.Exit(1)
}
s.wg.Add(1)
go s.socksAcceptLoop()
}
func (s *socksChain) socksAcceptLoop() error {
defer s.wg.Done()
defer s.listener.Close()
for {
conn, err := s.listener.Accept()
if err != nil {
if e, ok := err.(net.Error); ok && !e.Temporary() {
log.Infof("ERR/socks: Failed to Accept(): %v", err)
return err
}
continue
}
session := &socksChainSession{cfg: s.cfg, clientConn: conn, procInfo: s.procInfo, server: s}
go session.sessionWorker()
}
}
func (c *socksChainSession) sessionWorker() {
defer c.clientConn.Close()
clientAddr := c.clientConn.RemoteAddr()
log.Infof("INFO/socks: New connection from: %v", clientAddr)
// Do the SOCKS handshake with the client, and read the command.
var err error
if c.req, err = socks5.Handshake(c.clientConn); err != nil {
log.Infof("ERR/socks: Failed SOCKS5 handshake: %v", err)
return
}
switch c.req.Cmd {
case socks5.CommandTorResolve, socks5.CommandTorResolvePTR:
err = c.dispatchTorSOCKS()
// If we reach here, the request has been dispatched and completed.
if err == nil {
// Successfully even, send the response back with the addresc.
c.req.ReplyAddr(socks5.ReplySucceeded, c.bndAddr)
}
case socks5.CommandConnect:
if !c.filterConnect() {
c.req.Reply(socks5.ReplyConnectionRefused)
return
}
c.handleConnect()
default:
// Should *NEVER* happen, validated as part of handshake.
log.Infof("BUG/socks: Unsupported SOCKS command: 0x%02x", c.req.Cmd)
c.req.Reply(socks5.ReplyCommandNotSupported)
}
}
func (c *socksChainSession) addressDetails() (string, net.IP, uint16) {
addr := c.req.Addr
host, pstr := addr.HostPort()
port, err := strconv.ParseUint(pstr, 10, 16)
if err != nil || port == 0 || port > 0xFFFF {
log.Warningf("Illegal port value in socks address: %v", addr)
return "", nil, 0
}
if addr.Type() == 3 {
return host, nil, uint16(port)
}
ip := net.ParseIP(host)
if ip == nil {
log.Warningf("Failed to extract address information from socks address: %v", addr)
}
return "", ip, uint16(port)
}
func (c *socksChainSession) filterConnect() bool {
pinfo := procsnitch.FindProcessForConnection(c.clientConn, c.procInfo)
if pinfo == nil {
log.Warningf("No proc found for connection from: %s", c.clientConn.RemoteAddr())
return false
}
policy := c.server.fw.PolicyForPath(pinfo.ExePath)
hostname, ip, port := c.addressDetails()
if ip == nil && hostname == "" {
return false
}
result := policy.rules.filter(ip, port, hostname, pinfo)
switch result {
case FILTER_DENY:
return false
case FILTER_ALLOW:
return true
case FILTER_PROMPT:
pending := &pendingSocksConnection{
pol: policy,
hname: hostname,
destIP: ip,
destPort: port,
pinfo: pinfo,
verdict: make(chan int),
}
policy.processPromptResult(pending)
v := <-pending.verdict
if v == socksVerdictAccept {
return true
}
}
return false
}
func (c *socksChainSession) handleConnect() {
err := c.dispatchTorSOCKS()
if err != nil {
return
}
c.req.Reply(socks5.ReplySucceeded)
defer c.upstreamConn.Close()
if c.optData != nil {
if _, err = c.upstreamConn.Write(c.optData); err != nil {
log.Infof("ERR/socks: Failed writing OptData: %v", err)
return
}
c.optData = nil
}
// A upstream connection has been established, push data back and forth
// till the session is done.
c.forwardTraffic()
log.Infof("INFO/socks: Closed SOCKS connection from: %v", c.clientConn.RemoteAddr())
}
func (c *socksChainSession) forwardTraffic() {
var wg sync.WaitGroup
wg.Add(2)
copyLoop := func(dst, src net.Conn) {
defer wg.Done()
defer dst.Close()
io.Copy(dst, src)
}
go copyLoop(c.upstreamConn, c.clientConn)
go copyLoop(c.clientConn, c.upstreamConn)
wg.Wait()
}
func (c *socksChainSession) dispatchTorSOCKS() (err error) {
c.upstreamConn, c.bndAddr, err = socks5.Redispatch(c.cfg.TargetSocksNet, c.cfg.TargetSocksAddr, c.req)
if err != nil {
c.req.Reply(socks5.ErrorToReplyCode(err))
}
return
}