Files
rdpgw/cmd/rdpgw/main.go
2023-05-15 10:43:38 +02:00

275 lines
7.9 KiB
Go

package main
import (
"context"
"crypto/tls"
"fmt"
"github.com/bolkedebruin/gokrb5/v8/keytab"
"github.com/bolkedebruin/gokrb5/v8/service"
"github.com/bolkedebruin/gokrb5/v8/spnego"
"github.com/bolkedebruin/rdpgw/cmd/rdpgw/config"
"github.com/bolkedebruin/rdpgw/cmd/rdpgw/kdcproxy"
"github.com/bolkedebruin/rdpgw/cmd/rdpgw/protocol"
"github.com/bolkedebruin/rdpgw/cmd/rdpgw/security"
"github.com/bolkedebruin/rdpgw/cmd/rdpgw/web"
"github.com/coreos/go-oidc/v3/oidc"
"github.com/gorilla/mux"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/thought-machine/go-flags"
"golang.org/x/crypto/acme/autocert"
"golang.org/x/oauth2"
"log"
"net/http"
"net/url"
"os"
"strconv"
)
const (
gatewayEndPoint = "/remoteDesktopGateway/"
kdcProxyEndPoint = "/KdcProxy"
)
var opts struct {
ConfigFile string `short:"c" long:"conf" default:"rdpgw.yaml" description:"config file (yaml)"`
}
var conf config.Configuration
func initOIDC(callbackUrl *url.URL) *web.OIDC {
// set oidc config
provider, err := oidc.NewProvider(context.Background(), conf.OpenId.ProviderUrl)
if err != nil {
log.Fatalf("Cannot get oidc provider: %s", err)
}
oidcConfig := &oidc.Config{
ClientID: conf.OpenId.ClientId,
}
verifier := provider.Verifier(oidcConfig)
oauthConfig := oauth2.Config{
ClientID: conf.OpenId.ClientId,
ClientSecret: conf.OpenId.ClientSecret,
RedirectURL: callbackUrl.String(),
Endpoint: provider.Endpoint(),
Scopes: []string{oidc.ScopeOpenID, "profile", "email"},
}
security.OIDCProvider = provider
security.Oauth2Config = oauthConfig
o := web.OIDCConfig{
OAuth2Config: &oauthConfig,
OIDCTokenVerifier: verifier,
}
return o.New()
}
func main() {
// load config
_, err := flags.Parse(&opts)
if err != nil {
panic(err)
}
conf = config.Load(opts.ConfigFile)
// set callback url and external advertised gateway address
url, err := url.Parse(conf.Server.GatewayAddress)
if err != nil {
log.Printf("Cannot parse server gateway address %s due to %s", url, err)
}
if url.Scheme == "" {
url.Scheme = "https"
}
url.Path = "callback"
// set security options
security.VerifyClientIP = conf.Security.VerifyClientIp
security.SigningKey = []byte(conf.Security.PAATokenSigningKey)
security.EncryptionKey = []byte(conf.Security.PAATokenEncryptionKey)
security.UserEncryptionKey = []byte(conf.Security.UserTokenEncryptionKey)
security.UserSigningKey = []byte(conf.Security.UserTokenSigningKey)
security.QuerySigningKey = []byte(conf.Security.QueryTokenSigningKey)
security.HostSelection = conf.Server.HostSelection
security.Hosts = conf.Server.Hosts
// init session store
web.InitStore([]byte(conf.Server.SessionKey),
[]byte(conf.Server.SessionEncryptionKey),
conf.Server.SessionStore,
conf.Server.MaxSessionLength,
)
// configure web backend
w := &web.Config{
QueryInfo: security.QueryInfo,
QueryTokenIssuer: conf.Security.QueryTokenIssuer,
EnableUserToken: conf.Security.EnableUserToken,
Hosts: conf.Server.Hosts,
HostSelection: conf.Server.HostSelection,
RdpOpts: web.RdpOpts{
UsernameTemplate: conf.Client.UsernameTemplate,
SplitUserDomain: conf.Client.SplitUserDomain,
},
GatewayAddress: url,
TemplateFile: conf.Client.Defaults,
}
if conf.Caps.TokenAuth {
w.PAATokenGenerator = security.GeneratePAAToken
}
if conf.Security.EnableUserToken {
w.UserTokenGenerator = security.GenerateUserToken
}
h := w.NewHandler()
log.Printf("Starting remote desktop gateway server")
cfg := &tls.Config{}
// configure tls security
if conf.Server.Tls == config.TlsDisable {
log.Printf("TLS disabled - rdp gw connections require tls, make sure to have a terminator")
} else {
// auto config
tlsConfigured := false
tlsDebug := os.Getenv("SSLKEYLOGFILE")
if tlsDebug != "" {
w, err := os.OpenFile(tlsDebug, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
if err != nil {
log.Fatalf("Cannot open key log file %s for writing %s", tlsDebug, err)
}
log.Printf("Key log file set to: %s", tlsDebug)
cfg.KeyLogWriter = w
}
if conf.Server.KeyFile != "" && conf.Server.CertFile != "" {
cert, err := tls.LoadX509KeyPair(conf.Server.CertFile, conf.Server.KeyFile)
if err != nil {
log.Printf("Cannot load certfile or keyfile (%s) falling back to acme", err)
}
cfg.Certificates = append(cfg.Certificates, cert)
tlsConfigured = true
}
if !tlsConfigured {
log.Printf("Using acme / letsencrypt for tls configuration. Enabling http (port 80) for verification")
// setup a simple handler which sends a HTHS header for six months (!)
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Strict-Transport-Security", "max-age=15768000 ; includeSubDomains")
fmt.Fprintf(w, "Hello from RDPGW")
})
certMgr := autocert.Manager{
Prompt: autocert.AcceptTOS,
HostPolicy: autocert.HostWhitelist(url.Host),
Cache: autocert.DirCache("/tmp/rdpgw"),
}
cfg.GetCertificate = certMgr.GetCertificate
go func() {
http.ListenAndServe(":80", certMgr.HTTPHandler(nil))
}()
}
}
// gateway confg
gw := protocol.Gateway{
RedirectFlags: protocol.RedirectFlags{
Clipboard: conf.Caps.EnableClipboard,
Drive: conf.Caps.EnableDrive,
Printer: conf.Caps.EnablePrinter,
Port: conf.Caps.EnablePort,
Pnp: conf.Caps.EnablePnp,
DisableAll: conf.Caps.DisableRedirect,
EnableAll: conf.Caps.RedirectAll,
},
IdleTimeout: conf.Caps.IdleTimeout,
SmartCardAuth: conf.Caps.SmartCardAuth,
TokenAuth: conf.Caps.TokenAuth,
ReceiveBuf: conf.Server.ReceiveBuf,
SendBuf: conf.Server.SendBuf,
}
if conf.Caps.TokenAuth {
gw.CheckPAACookie = security.CheckPAACookie
gw.CheckHost = security.CheckSession(security.CheckHost)
} else {
gw.CheckHost = security.CheckHost
}
r := mux.NewRouter()
// ensure identity is set in context and get some extra info
r.Use(web.EnrichContext)
// prometheus metrics
r.Handle("/metrics", promhttp.Handler())
// for sso callbacks
r.HandleFunc("/tokeninfo", web.TokenInfo)
// gateway endpoint
rdp := r.PathPrefix(gatewayEndPoint).Subrouter()
// openid
if conf.Server.OpenIDEnabled() {
log.Printf("enabling openid extended authentication")
o := initOIDC(url)
r.Handle("/connect", o.Authenticated(http.HandlerFunc(h.HandleDownload)))
r.HandleFunc("/callback", o.HandleCallback)
// only enable un-auth endpoint for openid only config
if !conf.Server.KerberosEnabled() || !conf.Server.BasicAuthEnabled() {
rdp.Name("gw").HandlerFunc(gw.HandleGatewayProtocol)
}
}
// for stacking of authentication
auth := web.NewAuthMux()
rdp.MatcherFunc(web.NoAuthz).HandlerFunc(auth.SetAuthenticate)
// basic auth
if conf.Server.BasicAuthEnabled() {
log.Printf("enabling basic authentication")
q := web.BasicAuthHandler{SocketAddress: conf.Server.AuthSocket}
rdp.NewRoute().HeadersRegexp("Authorization", "Basic").HandlerFunc(q.BasicAuth(gw.HandleGatewayProtocol))
auth.Register(`Basic realm="restricted", charset="UTF-8"`)
}
// spnego / kerberos
if conf.Server.KerberosEnabled() {
log.Printf("enabling kerberos authentication")
keytab, err := keytab.Load(conf.Kerberos.Keytab)
if err != nil {
log.Fatalf("Cannot load keytab: %s", err)
}
rdp.NewRoute().HeadersRegexp("Authorization", "Negotiate").Handler(
spnego.SPNEGOKRB5Authenticate(web.TransposeSPNEGOContext(http.HandlerFunc(gw.HandleGatewayProtocol)),
keytab,
service.Logger(log.Default())))
// kdcproxy
k := kdcproxy.InitKdcProxy(conf.Kerberos.Krb5Conf)
r.HandleFunc(kdcProxyEndPoint, k.Handler).Methods("POST")
auth.Register("Negotiate")
}
// setup server
server := http.Server{
Addr: ":" + strconv.Itoa(conf.Server.Port),
Handler: r,
TLSConfig: cfg,
TLSNextProto: make(map[string]func(*http.Server, *tls.Conn, http.Handler)), // disable http2
}
if conf.Server.Tls == config.TlsDisable {
err = server.ListenAndServe()
} else {
err = server.ListenAndServeTLS("", "")
}
if err != nil {
log.Fatal("ListenAndServe: ", err)
}
}