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AUTH-2369: RDP Bastion prototype

This commit is contained in:
Michael Borkenstein 2020-05-04 15:15:17 -05:00
parent 6a7418e1af
commit b89cc22896
8 changed files with 78 additions and 33 deletions
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3
carrier/carrier.go
View File

@ -11,6 +11,7 @@ import (
"strings"
"github.com/cloudflare/cloudflared/cmd/cloudflared/token"
"github.com/cloudflare/cloudflared/h2mux"
"github.com/pkg/errors"
)
@ -145,7 +146,7 @@ func BuildAccessRequest(options *StartOptions) (*http.Request, error) {
if err != nil {
return nil, err
}
originRequest.Header.Set("cf-access-token", token)
originRequest.Header.Set(h2mux.CFAccessTokenHeader, token)
for k, v := range options.Headers {
if len(v) >= 1 {

7
cmd/cloudflared/access/carrier.go
View File

@ -7,6 +7,7 @@ import (
"github.com/cloudflare/cloudflared/carrier"
"github.com/cloudflare/cloudflared/cmd/cloudflared/config"
"github.com/cloudflare/cloudflared/h2mux"
"github.com/cloudflare/cloudflared/validation"
"github.com/pkg/errors"
cli "gopkg.in/urfave/cli.v2"
@ -54,15 +55,15 @@ func ssh(c *cli.Context) error {
// get the headers from the cmdline and add them
headers := buildRequestHeaders(c.StringSlice(sshHeaderFlag))
if c.IsSet(sshTokenIDFlag) {
headers.Add("CF-Access-Client-Id", c.String(sshTokenIDFlag))
headers.Add(h2mux.CFAccessClientIDHeader, c.String(sshTokenIDFlag))
}
if c.IsSet(sshTokenSecretFlag) {
headers.Add("CF-Access-Client-Secret", c.String(sshTokenSecretFlag))
headers.Add(h2mux.CFAccessClientSecretHeader, c.String(sshTokenSecretFlag))
}
destination := c.String(sshDestinationFlag)
if destination != "" {
headers.Add("CF-Access-SSH-Destination", destination)
headers.Add(h2mux.CFJumpDestinationHeader, destination)
}
options := &carrier.StartOptions{

7
cmd/cloudflared/access/cmd.go
View File

@ -13,6 +13,7 @@ import (
"github.com/cloudflare/cloudflared/cmd/cloudflared/cliutil"
"github.com/cloudflare/cloudflared/cmd/cloudflared/shell"
"github.com/cloudflare/cloudflared/cmd/cloudflared/token"
"github.com/cloudflare/cloudflared/h2mux"
"github.com/cloudflare/cloudflared/sshgen"
"github.com/cloudflare/cloudflared/validation"
"github.com/pkg/errors"
@ -262,7 +263,7 @@ func curl(c *cli.Context) error {
}
cmdArgs = append(cmdArgs, "-H")
cmdArgs = append(cmdArgs, fmt.Sprintf("cf-access-token: %s", tok))
cmdArgs = append(cmdArgs, fmt.Sprintf("%s: %s", h2mux.CFAccessTokenHeader, tok))
return shell.Run("curl", cmdArgs...)
}
@ -415,10 +416,10 @@ func isFileThere(candidate string) bool {
func verifyTokenAtEdge(appUrl *url.URL, c *cli.Context) error {
headers := buildRequestHeaders(c.StringSlice(sshHeaderFlag))
if c.IsSet(sshTokenIDFlag) {
headers.Add("CF-Access-Client-Id", c.String(sshTokenIDFlag))
headers.Add(h2mux.CFAccessClientIDHeader, c.String(sshTokenIDFlag))
}
if c.IsSet(sshTokenSecretFlag) {
headers.Add("CF-Access-Client-Secret", c.String(sshTokenSecretFlag))
headers.Add(h2mux.CFAccessClientSecretHeader, c.String(sshTokenSecretFlag))
}
options := &carrier.StartOptions{OriginURL: appUrl.String(), Headers: headers}

44
cmd/cloudflared/tunnel/cmd.go
View File

@ -6,6 +6,7 @@ import (
"fmt"
"io/ioutil"
"net"
"net/http"
"net/url"
"os"
"reflect"
@ -22,6 +23,7 @@ import (
"github.com/cloudflare/cloudflared/cmd/cloudflared/updater"
"github.com/cloudflare/cloudflared/connection"
"github.com/cloudflare/cloudflared/dbconnect"
"github.com/cloudflare/cloudflared/h2mux"
"github.com/cloudflare/cloudflared/hello"
"github.com/cloudflare/cloudflared/metrics"
"github.com/cloudflare/cloudflared/origin"
@ -81,9 +83,15 @@ const (
// hostKeyPath is the path of the dir to save SSH host keys too
hostKeyPath = "host-key-path"
//sshServerFlag enables cloudflared ssh proxy server
sshServerFlag = "ssh-server"
// socks5Flag is to enable the socks server to deframe
socks5Flag = "socks5"
// bastionFlag is to enable bastion, or jump host, operation
bastionFlag = "bastion"
noIntentMsg = "The --intent argument is required. Cloudflared looks up an Intent to determine what configuration to use (i.e. which tunnels to start). If you don't have any Intents yet, you can use a placeholder Intent Label for now. Then, when you make an Intent with that label, cloudflared will get notified and open the tunnels you specified in that Intent."
)
@ -343,12 +351,11 @@ func StartServer(c *cli.Context, version string, shutdownC, graceShutdownC chan
c.Set("url", "https://"+helloListener.Addr().String())
}
if c.IsSet("ssh-server") {
if c.IsSet(sshServerFlag) {
if runtime.GOOS != "darwin" && runtime.GOOS != "linux" {
msg := fmt.Sprintf("--ssh-server is not supported on %s", runtime.GOOS)
logger.Error(msg)
return errors.New(msg)
}
logger.Infof("ssh-server set")
@ -394,7 +401,7 @@ func StartServer(c *cli.Context, version string, shutdownC, graceShutdownC chan
c.Set("url", "ssh://"+localServerAddress)
}
if host := hostnameFromURI(c.String("url")); host != "" {
if staticHost := hostnameFromURI(c.String("url")); isProxyDestinationConfigured(staticHost, c) {
listener, err := net.Listen("tcp", "127.0.0.1:")
if err != nil {
logger.WithError(err).Error("Cannot start Websocket Proxy Server")
@ -406,15 +413,26 @@ func StartServer(c *cli.Context, version string, shutdownC, graceShutdownC chan
streamHandler := websocket.DefaultStreamHandler
if c.IsSet(socks5Flag) {
logger.Info("SOCKS5 server started")
streamHandler = func(wsConn *websocket.Conn, remoteConn net.Conn) {
streamHandler = func(wsConn *websocket.Conn, remoteConn net.Conn, _ http.Header) {
dialer := socks.NewConnDialer(remoteConn)
requestHandler := socks.NewRequestHandler(dialer)
socksServer := socks.NewConnectionHandler(requestHandler)
socksServer.Serve(wsConn)
}
} else if c.IsSet(sshServerFlag) {
streamHandler = func(wsConn *websocket.Conn, remoteConn net.Conn, requestHeaders http.Header) {
if finalDestination := requestHeaders.Get(h2mux.CFJumpDestinationHeader); finalDestination != "" {
token := requestHeaders.Get(h2mux.CFAccessTokenHeader)
if err := websocket.SendSSHPreamble(remoteConn, finalDestination, token); err != nil {
logger.WithError(err).Error("Failed to send SSH preamble")
return
}
}
websocket.DefaultStreamHandler(wsConn, remoteConn, requestHeaders)
}
}
errC <- websocket.StartProxyServer(logger, listener, host, shutdownC, streamHandler)
errC <- websocket.StartProxyServer(logger, listener, staticHost, shutdownC, streamHandler)
}()
c.Set("url", "http://"+listener.Addr().String())
}
@ -457,6 +475,11 @@ func Before(c *cli.Context) error {
return nil
}
// isProxyDestinationConfigured returns true if there is a static host set or if bastion mode is set.
func isProxyDestinationConfigured(staticHost string, c *cli.Context) bool {
return staticHost != "" || c.IsSet(bastionFlag)
}
func startDeclarativeTunnel(ctx context.Context,
c *cli.Context,
cloudflaredID uuid.UUID,
@ -882,7 +905,7 @@ func tunnelFlags(shouldHide bool) []cli.Flag {
Hidden: shouldHide,
}),
altsrc.NewBoolFlag(&cli.BoolFlag{
Name: "ssh-server",
Name: sshServerFlag,
Value: false,
Usage: "Run an SSH Server",
EnvVars: []string{"TUNNEL_SSH_SERVER"},
@ -1118,7 +1141,14 @@ func tunnelFlags(shouldHide bool) []cli.Flag {
Usage: "specify if this tunnel is running as a SOCK5 Server",
EnvVars: []string{"TUNNEL_SOCKS"},
Value: false,
Hidden: false,
Hidden: shouldHide,
}),
altsrc.NewBoolFlag(&cli.BoolFlag{
Name: bastionFlag,
Value: false,
Usage: "Runs as jump host",
EnvVars: []string{"TUNNEL_BASTION"},
Hidden: shouldHide,
}),
}
}

9
cmd/cloudflared/tunnel/configuration.go
View File

@ -233,10 +233,11 @@ func prepareTunnelConfig(
if !c.IsSet("hello-world") && c.IsSet("origin-server-name") {
httpTransport.TLSClientConfig.ServerName = c.String("origin-server-name")
}
err = validation.ValidateHTTPService(originURL, hostname, httpTransport)
if err != nil {
logger.WithError(err).Error("unable to connect to the origin")
// If tunnel running in bastion mode, a connection to origin will not exist until initiated by the client.
if !c.IsSet(bastionFlag) {
if err = validation.ValidateHTTPService(originURL, hostname, httpTransport); err != nil {
logger.WithError(err).Error("unable to connect to the origin")
}
}
toEdgeTLSConfig, err := tlsconfig.CreateTunnelConfig(c)

5
h2mux/header.go
View File

@ -25,6 +25,11 @@ const (
ResponseMetaHeaderField = "cf-cloudflared-response-meta"
ResponseSourceCloudflared = "cloudflared"
ResponseSourceOrigin = "origin"
CFAccessTokenHeader = "cf-access-token"
CFJumpDestinationHeader = "CF-Access-Jump-Destination"
CFAccessClientIDHeader = "CF-Access-Client-Id"
CFAccessClientSecretHeader = "CF-Access-Client-Secret"
)
// H2RequestHeadersToH1Request converts the HTTP/2 headers coming from origintunneld

1
sshserver/sshserver_unix.go
View File

@ -267,6 +267,7 @@ func (s *SSHProxy) proxyChannel(localChan, remoteChan gossh.Channel, localChanRe
}
}
// readPreamble reads a preamble from the SSH connection before any SSH traffic is sent.
// This preamble is a JSON encoded struct containing the users JWT and ultimate destination.
// The first 4 bytes contain the length of the preamble which follows immediately.

35
websocket/websocket.go
View File

@ -13,6 +13,7 @@ import (
"net/http"
"time"
"github.com/cloudflare/cloudflared/h2mux"
"github.com/cloudflare/cloudflared/sshserver"
"github.com/gorilla/websocket"
"github.com/sirupsen/logrus"
@ -118,13 +119,13 @@ func Stream(conn, backendConn io.ReadWriter) {
// DefaultStreamHandler is provided to the the standard websocket to origin stream
// This exist to allow SOCKS to deframe data before it gets to the origin
func DefaultStreamHandler(wsConn *Conn, remoteConn net.Conn) {
func DefaultStreamHandler(wsConn *Conn, remoteConn net.Conn, _ http.Header) {
Stream(wsConn, remoteConn)
}
// StartProxyServer will start a websocket server that will decode
// the websocket data and write the resulting data to the provided
func StartProxyServer(logger *logrus.Logger, listener net.Listener, remote string, shutdownC <-chan struct{}, streamHandler func(wsConn *Conn, remoteConn net.Conn)) error {
func StartProxyServer(logger *logrus.Logger, listener net.Listener, staticHost string, shutdownC <-chan struct{}, streamHandler func(wsConn *Conn, remoteConn net.Conn, requestHeaders http.Header)) error {
upgrader := websocket.Upgrader{
ReadBufferSize: 1024,
WriteBufferSize: 1024,
@ -137,7 +138,18 @@ func StartProxyServer(logger *logrus.Logger, listener net.Listener, remote strin
}()
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
stream, err := net.Dial("tcp", remote)
// If remote is an empty string, get the destination from the client.
finalDestination := staticHost
if finalDestination == "" {
if jumpDestination := r.Header.Get(h2mux.CFJumpDestinationHeader); jumpDestination == "" {
logger.Error("Did not receive final destination from client. The --destination flag is likely not set")
return
} else {
finalDestination = jumpDestination
}
}
stream, err := net.Dial("tcp", finalDestination)
if err != nil {
logger.WithError(err).Error("Cannot connect to remote.")
return
@ -162,24 +174,17 @@ func StartProxyServer(logger *logrus.Logger, listener net.Listener, remote strin
conn.Close()
}()
token := r.Header.Get("cf-access-token")
if destination := r.Header.Get("CF-Access-SSH-Destination"); destination != "" {
if err := sendSSHPreamble(stream, destination, token); err != nil {
logger.WithError(err).Error("Failed to send SSH preamble")
return
}
}
streamHandler(&Conn{conn}, stream)
streamHandler(&Conn{conn}, stream, r.Header)
})
return httpServer.Serve(listener)
}
// sendSSHPreamble sends the final SSH destination address to the cloudflared SSH proxy
// SendSSHPreamble sends the final SSH destination address to the cloudflared SSH proxy
// The destination is preceded by its length
func sendSSHPreamble(stream net.Conn, destination, token string) error {
preamble := &sshserver.SSHPreamble{Destination: destination, JWT: token}
// Not part of sshserver module to fix compilation for incompatible operating systems
func SendSSHPreamble(stream net.Conn, destination, token string) error {
preamble := sshserver.SSHPreamble{Destination: destination, JWT: token}
payload, err := json.Marshal(preamble)
if err != nil {
return err