X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/0a39317d5ec49ad439833df0a70965394cafb6e8..13f6d45704efc68ca8419e8917376aa44fdee1be:/lib/crunchrun/container_gateway.go

diff --git a/lib/crunchrun/container_gateway.go b/lib/crunchrun/container_gateway.go
index 92c11383f4..01457015e1 100644
--- a/lib/crunchrun/container_gateway.go
+++ b/lib/crunchrun/container_gateway.go
@@ -5,8 +5,11 @@
 package crunchrun
 
 import (
+	"crypto/hmac"
 	"crypto/rand"
 	"crypto/rsa"
+	"crypto/sha256"
+	"crypto/tls"
 	"fmt"
 	"io"
 	"net"
@@ -16,24 +19,55 @@ import (
 	"sync"
 	"syscall"
 
+	"git.arvados.org/arvados.git/lib/selfsigned"
+	"git.arvados.org/arvados.git/sdk/go/ctxlog"
 	"git.arvados.org/arvados.git/sdk/go/httpserver"
 	"github.com/creack/pty"
 	"github.com/google/shlex"
 	"golang.org/x/crypto/ssh"
+	"golang.org/x/net/context"
 )
 
-// startGatewayServer starts an http server that allows authenticated
-// clients to open an interactive "docker exec" session and (in
-// future) connect to tcp ports inside the docker container.
-func (runner *ContainerRunner) startGatewayServer() error {
-	runner.gatewaySSHConfig = &ssh.ServerConfig{
+type GatewayTarget interface {
+	// Command that will execute cmd inside the container
+	InjectCommand(ctx context.Context, detachKeys, username string, usingTTY bool, cmd []string) (*exec.Cmd, error)
+
+	// IP address inside container
+	IPAddress() (string, error)
+}
+
+type GatewayTargetStub struct{}
+
+func (GatewayTargetStub) IPAddress() (string, error) { return "127.0.0.1", nil }
+func (GatewayTargetStub) InjectCommand(ctx context.Context, detachKeys, username string, usingTTY bool, cmd []string) (*exec.Cmd, error) {
+	return exec.CommandContext(ctx, cmd[0], cmd[1:]...), nil
+}
+
+type Gateway struct {
+	ContainerUUID string
+	Address       string // listen host:port; if port=0, Start() will change it to the selected port
+	AuthSecret    string
+	Target        GatewayTarget
+	Log           interface {
+		Printf(fmt string, args ...interface{})
+	}
+
+	sshConfig   ssh.ServerConfig
+	requestAuth string
+	respondAuth string
+}
+
+// Start starts an http server that allows authenticated clients to open an
+// interactive "docker exec" session and (in future) connect to tcp ports
+// inside the docker container.
+func (gw *Gateway) Start() error {
+	gw.sshConfig = ssh.ServerConfig{
 		NoClientAuth: true,
 		PasswordCallback: func(c ssh.ConnMetadata, pass []byte) (*ssh.Permissions, error) {
 			if c.User() == "_" {
 				return nil, nil
-			} else {
-				return nil, fmt.Errorf("cannot specify user %q via ssh client", c.User())
 			}
+			return nil, fmt.Errorf("cannot specify user %q via ssh client", c.User())
 		},
 		PublicKeyCallback: func(c ssh.ConnMetadata, pubKey ssh.PublicKey) (*ssh.Permissions, error) {
 			if c.User() == "_" {
@@ -42,12 +76,11 @@ func (runner *ContainerRunner) startGatewayServer() error {
 						"pubkey-fp": ssh.FingerprintSHA256(pubKey),
 					},
 				}, nil
-			} else {
-				return nil, fmt.Errorf("cannot specify user %q via ssh client", c.User())
 			}
+			return nil, fmt.Errorf("cannot specify user %q via ssh client", c.User())
 		},
 	}
-	pvt, err := rsa.GenerateKey(rand.Reader, 4096)
+	pvt, err := rsa.GenerateKey(rand.Reader, 2048)
 	if err != nil {
 		return err
 	}
@@ -59,20 +92,34 @@ func (runner *ContainerRunner) startGatewayServer() error {
 	if err != nil {
 		return err
 	}
-	runner.gatewaySSHConfig.AddHostKey(signer)
+	gw.sshConfig.AddHostKey(signer)
 
-	// GatewayAddress (provided by arvados-dispatch-cloud) is
+	// Address (typically provided by arvados-dispatch-cloud) is
 	// HOST:PORT where HOST is our IP address or hostname as seen
 	// from arvados-controller, and PORT is either the desired
-	// port where we should run our gateway server, or "0" if
-	// we should choose an available port.
-	host, port, err := net.SplitHostPort(os.Getenv("GatewayAddress"))
+	// port where we should run our gateway server, or "0" if we
+	// should choose an available port.
+	host, port, err := net.SplitHostPort(gw.Address)
+	if err != nil {
+		return err
+	}
+	cert, err := selfsigned.CertGenerator{}.Generate()
 	if err != nil {
 		return err
 	}
+	h := hmac.New(sha256.New, []byte(gw.AuthSecret))
+	h.Write(cert.Certificate[0])
+	gw.requestAuth = fmt.Sprintf("%x", h.Sum(nil))
+	h.Reset()
+	h.Write([]byte(gw.requestAuth))
+	gw.respondAuth = fmt.Sprintf("%x", h.Sum(nil))
+
 	srv := &httpserver.Server{
 		Server: http.Server{
-			Handler: http.HandlerFunc(runner.handleSSH),
+			Handler: http.HandlerFunc(gw.handleSSH),
+			TLSConfig: &tls.Config{
+				Certificates: []tls.Certificate{cert},
+			},
 		},
 		Addr: ":" + port,
 	}
@@ -90,12 +137,13 @@ func (runner *ContainerRunner) startGatewayServer() error {
 	// gateway_address to "HOST:PORT" where HOST is our
 	// external hostname/IP as provided by arvados-dispatch-cloud,
 	// and PORT is the port number we ended up listening on.
-	runner.gatewayAddress = net.JoinHostPort(host, port)
+	gw.Address = net.JoinHostPort(host, port)
 	return nil
 }
 
-// handleSSH connects to an SSH server that runs commands as root in
-// the container. The tunnel itself can only be created by an
+// handleSSH connects to an SSH server that allows the caller to run
+// interactive commands as root (or any other desired user) inside the
+// container. The tunnel itself can only be created by an
 // authenticated caller, so the SSH server itself is wide open (any
 // password or key will be accepted).
 //
@@ -104,15 +152,17 @@ func (runner *ContainerRunner) startGatewayServer() error {
 // Connection: upgrade
 // Upgrade: ssh
 // X-Arvados-Target-Uuid: uuid of container
-// X-Arvados-Authorization: must match GatewayAuthSecret provided by
-// a-d-c (this prevents other containers and shell nodes from
-// connecting directly)
+// X-Arvados-Authorization: must match
+// hmac(AuthSecret,certfingerprint) (this prevents other containers
+// and shell nodes from connecting directly)
 //
-// Optional header:
+// Optional headers:
 //
-// X-Arvados-Detach-Keys: argument to "docker attach --detach-keys",
+// X-Arvados-Detach-Keys: argument to "docker exec --detach-keys",
 // e.g., "ctrl-p,ctrl-q"
-func (runner *ContainerRunner) handleSSH(w http.ResponseWriter, req *http.Request) {
+// X-Arvados-Login-Username: argument to "docker exec --user": account
+// used to run command(s) inside the container.
+func (gw *Gateway) handleSSH(w http.ResponseWriter, req *http.Request) {
 	// In future we'll handle browser traffic too, but for now the
 	// only traffic we expect is an SSH tunnel from
 	// (*lib/controller/localdb.Conn)ContainerSSH()
@@ -120,11 +170,11 @@ func (runner *ContainerRunner) handleSSH(w http.ResponseWriter, req *http.Reques
 		http.Error(w, "path not found", http.StatusNotFound)
 		return
 	}
-	if want := req.Header.Get("X-Arvados-Target-Uuid"); want != runner.Container.UUID {
-		http.Error(w, fmt.Sprintf("misdirected request: meant for %q but received by crunch-run %q", want, runner.Container.UUID), http.StatusBadGateway)
+	if want := req.Header.Get("X-Arvados-Target-Uuid"); want != gw.ContainerUUID {
+		http.Error(w, fmt.Sprintf("misdirected request: meant for %q but received by crunch-run %q", want, gw.ContainerUUID), http.StatusBadGateway)
 		return
 	}
-	if req.Header.Get("X-Arvados-Authorization") != runner.gatewayAuthSecret {
+	if req.Header.Get("X-Arvados-Authorization") != gw.requestAuth {
 		http.Error(w, "bad X-Arvados-Authorization header", http.StatusUnauthorized)
 		return
 	}
@@ -146,151 +196,217 @@ func (runner *ContainerRunner) handleSSH(w http.ResponseWriter, req *http.Reques
 	defer netconn.Close()
 	w.Header().Set("Connection", "upgrade")
 	w.Header().Set("Upgrade", "ssh")
+	w.Header().Set("X-Arvados-Authorization-Response", gw.respondAuth)
 	netconn.Write([]byte("HTTP/1.1 101 Switching Protocols\r\n"))
 	w.Header().Write(netconn)
 	netconn.Write([]byte("\r\n"))
 
 	ctx := req.Context()
 
-	conn, newchans, reqs, err := ssh.NewServerConn(netconn, runner.gatewaySSHConfig)
+	conn, newchans, reqs, err := ssh.NewServerConn(netconn, &gw.sshConfig)
 	if err != nil {
-		runner.CrunchLog.Printf("ssh.NewServerConn: %s", err)
+		gw.Log.Printf("ssh.NewServerConn: %s", err)
 		return
 	}
 	defer conn.Close()
 	go ssh.DiscardRequests(reqs)
 	for newch := range newchans {
-		if newch.ChannelType() != "session" {
-			newch.Reject(ssh.UnknownChannelType, "unknown channel type")
-			continue
+		switch newch.ChannelType() {
+		case "direct-tcpip":
+			go gw.handleDirectTCPIP(ctx, newch)
+		case "session":
+			go gw.handleSession(ctx, newch, detachKeys, username)
+		default:
+			go newch.Reject(ssh.UnknownChannelType, fmt.Sprintf("unsupported channel type %q", newch.ChannelType()))
 		}
-		ch, reqs, err := newch.Accept()
-		if err != nil {
-			runner.CrunchLog.Printf("accept channel: %s", err)
-			return
-		}
-		var pty0, tty0 *os.File
-		go func() {
-			defer pty0.Close()
-			defer tty0.Close()
-			// Where to send errors/messages for the
-			// client to see
-			logw := io.Writer(ch.Stderr())
-			// How to end lines when sending
-			// errors/messages to the client (changes to
-			// \r\n when using a pty)
-			eol := "\n"
-			// Env vars to add to child process
-			termEnv := []string(nil)
-			for req := range reqs {
-				ok := false
-				switch req.Type {
-				case "shell", "exec":
-					ok = true
-					var payload struct {
-						Command string
-					}
-					ssh.Unmarshal(req.Payload, &payload)
-					execargs, err := shlex.Split(payload.Command)
-					if err != nil {
-						fmt.Fprintf(logw, "error parsing supplied command: %s"+eol, err)
-						return
-					}
-					if len(execargs) == 0 {
-						execargs = []string{"/bin/bash", "-login"}
-					}
-					go func() {
-						cmd := exec.CommandContext(ctx, "docker", "exec", "-i", "--detach-keys="+detachKeys, "--user="+username)
-						cmd.Stdin = ch
-						cmd.Stdout = ch
-						cmd.Stderr = ch.Stderr()
-						if tty0 != nil {
-							cmd.Args = append(cmd.Args, "-t")
-							cmd.Stdin = tty0
-							cmd.Stdout = tty0
-							cmd.Stderr = tty0
-							var wg sync.WaitGroup
-							defer wg.Wait()
-							wg.Add(2)
-							go func() { io.Copy(ch, pty0); wg.Done() }()
-							go func() { io.Copy(pty0, ch); wg.Done() }()
-							// Send our own debug messages to tty as well.
-							logw = tty0
-						}
-						cmd.Args = append(cmd.Args, runner.ContainerID)
-						cmd.Args = append(cmd.Args, execargs...)
-						cmd.SysProcAttr = &syscall.SysProcAttr{
-							Setctty: tty0 != nil,
-							Setsid:  true,
-						}
-						cmd.Env = append(os.Environ(), termEnv...)
-						err := cmd.Run()
-						errClose := ch.CloseWrite()
-						var resp struct {
-							Status uint32
-						}
-						if err, ok := err.(*exec.ExitError); ok {
-							if status, ok := err.Sys().(syscall.WaitStatus); ok {
-								resp.Status = uint32(status.ExitStatus())
-							}
-						}
-						if resp.Status == 0 && (err != nil || errClose != nil) {
-							resp.Status = 1
-						}
-						ch.SendRequest("exit-status", false, ssh.Marshal(&resp))
-						ch.Close()
-					}()
-				case "pty-req":
-					eol = "\r\n"
-					p, t, err := pty.Open()
-					if err != nil {
-						fmt.Fprintf(ch.Stderr(), "pty failed: %s"+eol, err)
-						break
-					}
-					pty0, tty0 = p, t
-					ok = true
-					var payload struct {
-						Term string
-						Cols uint32
-						Rows uint32
-						X    uint32
-						Y    uint32
-					}
-					ssh.Unmarshal(req.Payload, &payload)
-					termEnv = []string{"TERM=" + payload.Term, "USE_TTY=1"}
-					err = pty.Setsize(pty0, &pty.Winsize{Rows: uint16(payload.Rows), Cols: uint16(payload.Cols), X: uint16(payload.X), Y: uint16(payload.Y)})
-					if err != nil {
-						fmt.Fprintf(logw, "pty-req: setsize failed: %s"+eol, err)
-					}
-				case "window-change":
-					var payload struct {
-						Cols uint32
-						Rows uint32
-						X    uint32
-						Y    uint32
-					}
-					ssh.Unmarshal(req.Payload, &payload)
-					err := pty.Setsize(pty0, &pty.Winsize{Rows: uint16(payload.Rows), Cols: uint16(payload.Cols), X: uint16(payload.X), Y: uint16(payload.Y)})
-					if err != nil {
-						fmt.Fprintf(logw, "window-change: setsize failed: %s"+eol, err)
-						break
+	}
+}
+
+func (gw *Gateway) handleDirectTCPIP(ctx context.Context, newch ssh.NewChannel) {
+	ch, reqs, err := newch.Accept()
+	if err != nil {
+		gw.Log.Printf("accept direct-tcpip channel: %s", err)
+		return
+	}
+	defer ch.Close()
+	go ssh.DiscardRequests(reqs)
+
+	// RFC 4254 7.2 (copy of channelOpenDirectMsg in
+	// golang.org/x/crypto/ssh)
+	var msg struct {
+		Raddr string
+		Rport uint32
+		Laddr string
+		Lport uint32
+	}
+	err = ssh.Unmarshal(newch.ExtraData(), &msg)
+	if err != nil {
+		fmt.Fprintf(ch.Stderr(), "unmarshal direct-tcpip extradata: %s\n", err)
+		return
+	}
+	switch msg.Raddr {
+	case "localhost", "0.0.0.0", "127.0.0.1", "::1", "::":
+	default:
+		fmt.Fprintf(ch.Stderr(), "cannot forward to ports on %q, only localhost\n", msg.Raddr)
+		return
+	}
+
+	dstaddr, err := gw.Target.IPAddress()
+	if err != nil {
+		fmt.Fprintf(ch.Stderr(), "container has no IP address: %s\n", err)
+		return
+	} else if dstaddr == "" {
+		fmt.Fprintf(ch.Stderr(), "container has no IP address\n")
+		return
+	}
+
+	dst := net.JoinHostPort(dstaddr, fmt.Sprintf("%d", msg.Rport))
+	tcpconn, err := net.Dial("tcp", dst)
+	if err != nil {
+		fmt.Fprintf(ch.Stderr(), "%s: %s\n", dst, err)
+		return
+	}
+	go func() {
+		n, _ := io.Copy(ch, tcpconn)
+		ctxlog.FromContext(ctx).Debugf("tcpip: sent %d bytes\n", n)
+		ch.CloseWrite()
+	}()
+	n, _ := io.Copy(tcpconn, ch)
+	ctxlog.FromContext(ctx).Debugf("tcpip: received %d bytes\n", n)
+}
+
+func (gw *Gateway) handleSession(ctx context.Context, newch ssh.NewChannel, detachKeys, username string) {
+	ch, reqs, err := newch.Accept()
+	if err != nil {
+		gw.Log.Printf("accept session channel: %s", err)
+		return
+	}
+	var pty0, tty0 *os.File
+	// Where to send errors/messages for the client to see
+	logw := io.Writer(ch.Stderr())
+	// How to end lines when sending errors/messages to the client
+	// (changes to \r\n when using a pty)
+	eol := "\n"
+	// Env vars to add to child process
+	termEnv := []string(nil)
+	for req := range reqs {
+		ok := false
+		switch req.Type {
+		case "shell", "exec":
+			ok = true
+			var payload struct {
+				Command string
+			}
+			ssh.Unmarshal(req.Payload, &payload)
+			execargs, err := shlex.Split(payload.Command)
+			if err != nil {
+				fmt.Fprintf(logw, "error parsing supplied command: %s"+eol, err)
+				return
+			}
+			if len(execargs) == 0 {
+				execargs = []string{"/bin/bash", "-login"}
+			}
+			go func() {
+				var resp struct {
+					Status uint32
+				}
+				defer func() {
+					ch.SendRequest("exit-status", false, ssh.Marshal(&resp))
+					ch.Close()
+				}()
+
+				cmd, err := gw.Target.InjectCommand(ctx, detachKeys, username, tty0 != nil, execargs)
+				if err != nil {
+					fmt.Fprintln(ch.Stderr(), err)
+					ch.CloseWrite()
+					resp.Status = 1
+					return
+				}
+				cmd.Stdin = ch
+				cmd.Stdout = ch
+				cmd.Stderr = ch.Stderr()
+				if tty0 != nil {
+					cmd.Stdin = tty0
+					cmd.Stdout = tty0
+					cmd.Stderr = tty0
+					var wg sync.WaitGroup
+					defer wg.Wait()
+					wg.Add(2)
+					go func() { io.Copy(ch, pty0); wg.Done() }()
+					go func() { io.Copy(pty0, ch); wg.Done() }()
+					// Send our own debug messages to tty as well.
+					logw = tty0
+				}
+				cmd.SysProcAttr = &syscall.SysProcAttr{
+					Setctty: tty0 != nil,
+					Setsid:  true,
+				}
+				cmd.Env = append(os.Environ(), termEnv...)
+				err = cmd.Run()
+				if exiterr, ok := err.(*exec.ExitError); ok {
+					if status, ok := exiterr.Sys().(syscall.WaitStatus); ok {
+						resp.Status = uint32(status.ExitStatus())
 					}
-					ok = true
-				case "env":
-					// TODO: implement "env"
-					// requests by setting env
-					// vars in the docker-exec
-					// command (not docker-exec's
-					// own environment, which
-					// would be a gaping security
-					// hole).
-				default:
-					// fmt.Fprintf(logw, "declining %q req"+eol, req.Type)
+				} else if err != nil {
+					// Propagate errors like `exec: "docker": executable file not found in $PATH`
+					fmt.Fprintln(ch.Stderr(), err)
 				}
-				if req.WantReply {
-					req.Reply(ok, nil)
+				errClose := ch.CloseWrite()
+				if resp.Status == 0 && (err != nil || errClose != nil) {
+					resp.Status = 1
 				}
+			}()
+		case "pty-req":
+			eol = "\r\n"
+			p, t, err := pty.Open()
+			if err != nil {
+				fmt.Fprintf(ch.Stderr(), "pty failed: %s"+eol, err)
+				break
+			}
+			defer p.Close()
+			defer t.Close()
+			pty0, tty0 = p, t
+			ok = true
+			var payload struct {
+				Term string
+				Cols uint32
+				Rows uint32
+				X    uint32
+				Y    uint32
+			}
+			ssh.Unmarshal(req.Payload, &payload)
+			termEnv = []string{"TERM=" + payload.Term, "USE_TTY=1"}
+			err = pty.Setsize(pty0, &pty.Winsize{Rows: uint16(payload.Rows), Cols: uint16(payload.Cols), X: uint16(payload.X), Y: uint16(payload.Y)})
+			if err != nil {
+				fmt.Fprintf(logw, "pty-req: setsize failed: %s"+eol, err)
 			}
-		}()
+		case "window-change":
+			var payload struct {
+				Cols uint32
+				Rows uint32
+				X    uint32
+				Y    uint32
+			}
+			ssh.Unmarshal(req.Payload, &payload)
+			err := pty.Setsize(pty0, &pty.Winsize{Rows: uint16(payload.Rows), Cols: uint16(payload.Cols), X: uint16(payload.X), Y: uint16(payload.Y)})
+			if err != nil {
+				fmt.Fprintf(logw, "window-change: setsize failed: %s"+eol, err)
+				break
+			}
+			ok = true
+		case "env":
+			// TODO: implement "env"
+			// requests by setting env
+			// vars in the docker-exec
+			// command (not docker-exec's
+			// own environment, which
+			// would be a gaping security
+			// hole).
+		default:
+			// fmt.Fprintf(logw, "declining %q req"+eol, req.Type)
+		}
+		if req.WantReply {
+			req.Reply(ok, nil)
+		}
 	}
 }