AUTH-1781: fixed race condition for short lived certs, doc required config

carrier/carrier.go

@@ -12,7 +12,6 @@ import (
 	"strings"
 
 	"github.com/cloudflare/cloudflared/cmd/cloudflared/token"
-	"github.com/cloudflare/cloudflared/sshgen"
 	"github.com/cloudflare/cloudflared/websocket"
 	"github.com/sirupsen/logrus"
 )
@@ -20,7 +19,6 @@ import (
 type StartOptions struct {
 	OriginURL string
 	Headers   http.Header
-	ShouldGenCert bool
 }
 
 // StdinoutStream is empty struct for wrapping stdin/stdout
@@ -116,17 +114,11 @@ func createWebsocketStream(options *StartOptions) (*websocket.Conn, error) {
 		if !strings.Contains(location.String(), "cdn-cgi/access/login") {
 			return nil, errors.New("not an Access redirect")
 		}
-		req, token, err := buildAccessRequest(options.OriginURL)
+		req, err := buildAccessRequest(options.OriginURL)
 		if err != nil {
 			return nil, err
 		}
 
-		if options.ShouldGenCert {
-			if err := sshgen.GenerateShortLivedCertificate(req.URL, token); err != nil {
-				return nil, err
-			}
-		}
-
 		wsConn, _, err = websocket.ClientConnect(req, nil)
 		if err != nil {
 			return nil, err
@@ -139,24 +131,24 @@ func createWebsocketStream(options *StartOptions) (*websocket.Conn, error) {
 }
 
 // buildAccessRequest builds an HTTP request with the Access token set
-func buildAccessRequest(originURL string) (*http.Request, string, error) {
+func buildAccessRequest(originURL string) (*http.Request, error) {
 	req, err := http.NewRequest(http.MethodGet, originURL, nil)
 	if err != nil {
-		return nil, "", err
+		return nil, err
 	}
 
 	token, err := token.FetchToken(req.URL)
 	if err != nil {
-		return nil, "", err
+		return nil, err
 	}
 
 	// We need to create a new request as FetchToken will modify req (boo mutable)
 	// as it has to follow redirect on the API and such, so here we init a new one
 	originRequest, err := http.NewRequest(http.MethodGet, originURL, nil)
 	if err != nil {
-		return nil, "", err
+		return nil, err
 	}
 	originRequest.Header.Set("cf-access-token", token)
 
-	return originRequest, token, nil
+	return originRequest, nil
 }

carrier/carrier_test.go

@@ -51,7 +51,6 @@ func TestStartClient(t *testing.T) {
 	options := &StartOptions{
 		OriginURL: "http://" + ts.Listener.Addr().String(),
 		Headers:   nil,
-		ShouldGenCert: false,
 	}
 	err := StartClient(logger, buf, options)
 	assert.NoError(t, err)
@@ -75,7 +74,6 @@ func TestStartServer(t *testing.T) {
 	options := &StartOptions{
 		OriginURL: "http://" + ts.Listener.Addr().String(),
 		Headers:   nil,
-		ShouldGenCert: false,
 	}
 
 	go func() {

cmd/cloudflared/access/carrier.go

@@ -34,12 +34,9 @@ func ssh(c *cli.Context) error {
 		headers.Add("CF-Access-Client-Secret", c.String(sshTokenSecretFlag))
 	}
 
-	genCertBool := c.Bool(sshGenCertFlag)
-
 	options := &carrier.StartOptions{
 		OriginURL: originURL,
 		Headers:   headers,
-		ShouldGenCert: genCertBool,
 	}
 
 	if c.NArg() > 0 || c.IsSet(sshURLFlag) {

cmd/cloudflared/access/cmd.go

@@ -3,12 +3,15 @@ package access
 import (
 	"errors"
 	"fmt"
+	"html/template"
 	"net/url"
 	"os"
 	"strings"
 
 	"github.com/cloudflare/cloudflared/cmd/cloudflared/shell"
 	"github.com/cloudflare/cloudflared/cmd/cloudflared/token"
+	"github.com/cloudflare/cloudflared/sshgen"
+	"github.com/cloudflare/cloudflared/validation"
 	"golang.org/x/net/idna"
 
 	"github.com/cloudflare/cloudflared/log"
@@ -22,7 +25,23 @@ const (
 	sshHeaderFlag      = "header"
 	sshTokenIDFlag     = "service-token-id"
 	sshTokenSecretFlag = "service-token-secret"
-	sshGenCertFlag     = "gen-cert"
+	sshGenCertFlag     = "short-lived-cert"
+	sshConfigTemplate  = `
+Add this configuration block to your {{.Home}}/.ssh/config:
+
+Host {{.Hostname}}
+{{- if .ShortLivedCerts}}
+	ProxyCommand bash -c '{{.Cloudflared}} access ssh-gen --hostname %h; ssh -tt cfpipe >&2 <&1' 
+
+Host cfpipe-{{.Hostname}}
+	HostName {{.Hostname}}
+	ProxyCommand {{.Cloudflared}} access ssh --hostname %h
+	IdentityFile ~/.cloudflared/{{.Hostname}}.me-cf_key
+	CertificateFile ~/.cloudflared/{{.Hostname}}-cf_key-cert.pub
+{{- else}}
+	ProxyCommand {{.Cloudflared}} access ssh --hostname %h
+{{end}}
+`
 )
 
 const sentryDSN = "https://56a9c9fa5c364ab28f34b14f35ea0f1b@sentry.io/189878"
@@ -124,6 +143,18 @@ func Commands() []*cli.Command {
 							Aliases: []string{"secret"},
 							Usage:   "specify an Access service token secret you wish to use.",
 						},
+					},
+				},
+				{
+					Name:        "ssh-config",
+					Action:      sshConfig,
+					Usage:       "",
+					Description: `Prints an example configuration ~/.ssh/config`,
+					Flags: []cli.Flag{
+						&cli.StringFlag{
+							Name:  sshHostnameFlag,
+							Usage: "specify the hostname of your application.",
+						},
 						&cli.BoolFlag{
 							Name:  sshGenCertFlag,
 							Usage: "specify if you wish to generate short lived certs.",
@@ -131,10 +162,16 @@ func Commands() []*cli.Command {
 					},
 				},
 				{
-					Name:        "ssh-config",
-					Action:      sshConfig,
-					Usage:       "ssh-config",
-					Description: `Prints an example configuration ~/.ssh/config`,
+					Name:        "ssh-gen",
+					Action:      sshGen,
+					Usage:       "",
+					Description: `Generates a short lived certificate for given hostname`,
+					Flags: []cli.Flag{
+						&cli.StringFlag{
+							Name:  sshHostnameFlag,
+							Usage: "specify the hostname of your application.",
+						},
+					},
 				},
 			},
 		},
@@ -218,8 +255,49 @@ func generateToken(c *cli.Context) error {
 
 // sshConfig prints an example SSH config to stdout
 func sshConfig(c *cli.Context) error {
-	outputMessage := "Add this configuration block to your %s/.ssh/config:\n\nHost [your hostname]\n\tProxyCommand %s access ssh --hostname %%h\n"
-	logger.Printf(outputMessage, os.Getenv("HOME"), cloudflaredPath())
+	genCertBool := c.Bool(sshGenCertFlag)
+	hostname := c.String(sshHostnameFlag)
+	if hostname == "" {
+		hostname = "[your hostname]"
+	}
+
+	type config struct {
+		Home            string
+		ShortLivedCerts bool
+		Hostname        string
+		Cloudflared     string
+	}
+
+	t := template.Must(template.New("sshConfig").Parse(sshConfigTemplate))
+	return t.Execute(os.Stdout, config{Home: os.Getenv("HOME"), ShortLivedCerts: genCertBool, Hostname: hostname, Cloudflared: cloudflaredPath()})
+}
+
+// sshGen generates a short lived certificate for provided hostname
+func sshGen(c *cli.Context) error {
+	// get the hostname from the cmdline and error out if its not provided
+	rawHostName := c.String(sshHostnameFlag)
+	hostname, err := validation.ValidateHostname(rawHostName)
+	if err != nil || rawHostName == "" {
+		return cli.ShowCommandHelp(c, "ssh-gen")
+	}
+
+	originURL, err := url.Parse("https://" + hostname)
+	if err != nil {
+		return err
+	}
+
+	// this fetchToken function mutates the appURL param. We should refactor that
+	fetchTokenURL := &url.URL{}
+	*fetchTokenURL = *originURL
+	token, err := token.FetchToken(fetchTokenURL)
+	if err != nil {
+		return err
+	}
+
+	if err := sshgen.GenerateShortLivedCertificate(originURL, token); err != nil {
+		return err
+	}
+
 	return nil
 }