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api.go
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api.go
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/*
Copyright 2016 Gravitational, Inc.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package client
import (
"bufio"
"context"
"crypto/tls"
"crypto/x509"
"encoding/pem"
"fmt"
"io"
"io/ioutil"
"net"
"os"
"os/exec"
"os/signal"
"os/user"
"path"
"path/filepath"
"strconv"
"strings"
"syscall"
"time"
"github.com/gravitational/teleport"
"github.com/gravitational/teleport/lib/auth"
"github.com/gravitational/teleport/lib/backend"
"github.com/gravitational/teleport/lib/backend/dir"
"github.com/gravitational/teleport/lib/defaults"
"github.com/gravitational/teleport/lib/events"
"github.com/gravitational/teleport/lib/services"
"github.com/gravitational/teleport/lib/session"
"github.com/gravitational/teleport/lib/shell"
"github.com/gravitational/teleport/lib/state"
"github.com/gravitational/teleport/lib/utils"
"github.com/gravitational/trace"
"github.com/moby/moby/pkg/term"
log "github.com/sirupsen/logrus"
"golang.org/x/crypto/ssh"
"golang.org/x/crypto/ssh/agent"
"golang.org/x/crypto/ssh/terminal"
)
const (
// Directory location where tsh profiles (and session keys) are stored
ProfileDir = ".tsh"
)
// ForwardedPort specifies local tunnel to remote
// destination managed by the client, is equivalent
// of ssh -L src:host:dst command
type ForwardedPort struct {
SrcIP string
SrcPort int
DestPort int
DestHost string
}
type ForwardedPorts []ForwardedPort
// ToString() returns a string representation of a forwarded port spec, compatible
// with OpenSSH's -L flag, i.e. "src_host:src_port:dest_host:dest_port"
func (p *ForwardedPort) ToString() string {
sport := strconv.Itoa(p.SrcPort)
dport := strconv.Itoa(p.DestPort)
if utils.IsLocalhost(p.SrcIP) {
return sport + ":" + net.JoinHostPort(p.DestHost, dport)
}
return net.JoinHostPort(p.SrcIP, sport) + ":" + net.JoinHostPort(p.DestHost, dport)
}
// HostKeyCallback is called by SSH client when it needs to check
// remote host key or certificate validity
type HostKeyCallback func(host string, ip net.Addr, key ssh.PublicKey) error
// Config is a client config
type Config struct {
// Username is the Teleport account username (for logging into Teleport proxies)
Username string
// Remote host to connect
Host string
// Labels represent host Labels
Labels map[string]string
// Namespace is nodes namespace
Namespace string
// HostLogin is a user login on a remote host
HostLogin string
// HostPort is a remote host port to connect to. This is used for **explicit**
// port setting via -p flag, otherwise '0' is passed which means "use server default"
HostPort int
// ProxyHostPort is a host or IP of the proxy (with optional ":ssh_port,https_port").
// The value is taken from the --proxy flag and can look like --proxy=host:5025,5080
ProxyHostPort string
// KeyTTL is a time to live for the temporary SSH keypair to remain valid:
KeyTTL time.Duration
// InsecureSkipVerify is an option to skip HTTPS cert check
InsecureSkipVerify bool
// SkipLocalAuth tells the client to use AuthMethods parameter for authentication and NOT
// use its own SSH agent or ask user for passwords. This is used by external programs linking
// against Teleport client and obtaining credentials from elsewhere.
SkipLocalAuth bool
// Agent is used when SkipLocalAuth is true
Agent agent.Agent
// ForwardAgent is used by the client to request agent forwarding from the server.
ForwardAgent bool
// AuthMethods are used to login into the cluster. If specified, the client will
// use them in addition to certs stored in its local agent (from disk)
AuthMethods []ssh.AuthMethod
// TLSConfig is TLS configuration, if specified, the client
// will use this TLS configuration to access API endpoints
TLS *tls.Config
// DefaultPrincipal determines the default SSH username (principal) the client should be using
// when connecting to auth/proxy servers. Usually it's returned with a certificate,
// but this variables provides a default (used by the web-based terminal client)
DefaultPrincipal string
Stdout io.Writer
Stderr io.Writer
Stdin io.Reader
// ExitStatus carries the returned value (exit status) of the remote
// process execution (via SSH exec)
ExitStatus int
// SiteName specifies site to execute operation,
// if omitted, first available site will be selected
SiteName string
// Locally forwarded ports (parameters to -L ssh flag)
LocalForwardPorts ForwardedPorts
// HostKeyCallback will be called to check host keys of the remote
// node, if not specified will be using CheckHostSignature function
// that uses local cache to validate hosts
HostKeyCallback HostKeyCallback
// KeyDir defines where temporary session keys will be stored.
// if empty, they'll go to ~/.tsh
KeysDir string
// Env is a map of environmnent variables to send when opening session
Env map[string]string
// Interactive, when set to true, tells tsh to launch a remote command
// in interactive mode, i.e. attaching the temrinal to it
Interactive bool
// ClientAddr (if set) specifies the true client IP. Usually it's not needed (since the server
// can look at the connecting address to determine client's IP) but for cases when the
// client is web-based, this must be set to HTTP's remote addr
ClientAddr string
// CachePolicy defines local caching policy in case if discovery goes down
// by default does not use caching
CachePolicy *CachePolicy
// CertificateFormat is the format of the SSH certificate.
CertificateFormat string
// AuthConnector is the name of the authentication connector to use.
AuthConnector string
}
// CachePolicy defines cache policy for local clients
type CachePolicy struct {
// CacheTTL defines cache TTL
CacheTTL time.Duration
// NeverExpire never expires local cache information
NeverExpires bool
}
func MakeDefaultConfig() *Config {
return &Config{
Stdout: os.Stdout,
Stderr: os.Stderr,
Stdin: os.Stdin,
}
}
// LoadProfile populates Config with the values stored in the given
// profiles directory. If profileDir is an empty string, the default profile
// directory ~/.tsh is used.
func (c *Config) LoadProfile(profileDir string, proxyName string) error {
profileDir = FullProfilePath(profileDir)
// read the profile:
cp, err := ProfileFromDir(profileDir, proxyName)
if err != nil {
if trace.IsNotFound(err) {
return nil
}
return trace.Wrap(err)
}
// apply the profile to the current configuration:
c.SetProxy(cp.ProxyHost, cp.ProxyWebPort, cp.ProxySSHPort)
c.Username = cp.Username
c.SiteName = cp.SiteName
c.LocalForwardPorts, err = ParsePortForwardSpec(cp.ForwardedPorts)
if err != nil {
log.Warnf("Error parsing user profile: %v", err)
}
return nil
}
// SaveProfile updates the given profiles directory with the current configuration
// If profileDir is an empty string, the default ~/.tsh is used
func (c *Config) SaveProfile(profileDir string) error {
if c.ProxyHostPort == "" {
return nil
}
profileDir = FullProfilePath(profileDir)
profilePath := path.Join(profileDir, c.ProxyHost()) + ".yaml"
var cp ClientProfile
cp.ProxyHost = c.ProxyHost()
cp.Username = c.Username
cp.ProxySSHPort = c.ProxySSHPort()
cp.ProxyWebPort = c.ProxyWebPort()
cp.ForwardedPorts = c.LocalForwardPorts.ToStringSpec()
cp.SiteName = c.SiteName
// create a profile file:
if err := cp.SaveTo(profilePath, ProfileMakeCurrent); err != nil {
return trace.Wrap(err)
}
return nil
}
func (c *Config) SetProxy(host string, webPort, sshPort int) {
c.ProxyHostPort = fmt.Sprintf("%s:%d,%d", host, webPort, sshPort)
}
// ProxyHost returns the hostname of the proxy server (without any port numbers)
func (c *Config) ProxyHost() string {
host, _, err := net.SplitHostPort(c.ProxyHostPort)
if err != nil {
return c.ProxyHostPort
}
return host
}
func (c *Config) ProxySSHHostPort() string {
return net.JoinHostPort(c.ProxyHost(), strconv.Itoa(c.ProxySSHPort()))
}
func (c *Config) ProxyWebHostPort() string {
return net.JoinHostPort(c.ProxyHost(), strconv.Itoa(c.ProxyWebPort()))
}
// ProxyWebPort returns the port number of teleport HTTP proxy stored in the config
// usually 3080 by default.
func (c *Config) ProxyWebPort() (retval int) {
retval = defaults.HTTPListenPort
_, port, err := net.SplitHostPort(c.ProxyHostPort)
if err == nil && len(port) > 0 && port[0] != ',' {
ports := strings.Split(port, ",")
if len(ports) > 0 {
retval, err = strconv.Atoi(ports[0])
if err != nil {
log.Warnf("invalid proxy web port: '%v': %v", ports, err)
}
}
}
return retval
}
// ProxySSHPort returns the port number of teleport SSH proxy stored in the config
// usually 3023 by default.
func (c *Config) ProxySSHPort() (retval int) {
retval = defaults.SSHProxyListenPort
_, port, err := net.SplitHostPort(c.ProxyHostPort)
if err == nil && len(port) > 0 {
ports := strings.Split(port, ",")
if len(ports) > 1 {
retval, err = strconv.Atoi(ports[1])
if err != nil {
log.Warnf("invalid proxy SSH port: '%v': %v", ports, err)
}
}
}
return retval
}
// ProxySpecified returns true if proxy has been specified
func (c *Config) ProxySpecified() bool {
return len(c.ProxyHostPort) > 0
}
// TeleportClient is a wrapper around SSH client with teleport specific
// workflow built in
type TeleportClient struct {
Config
localAgent *LocalKeyAgent
// OnShellCreated gets called when the shell is created. It's
// safe to keep it nil
OnShellCreated ShellCreatedCallback
}
// ShellCreatedCallback can be supplied for every teleport client. It will
// be called right after the remote shell is created, but the session
// hasn't begun yet.
//
// It allows clients to cancel SSH action
type ShellCreatedCallback func(s *ssh.Session, c *ssh.Client, terminal io.ReadWriteCloser) (exit bool, err error)
// NewClient creates a TeleportClient object and fully configures it
func NewClient(c *Config) (tc *TeleportClient, err error) {
// validate configuration
if c.Username == "" {
c.Username, err = Username()
if err != nil {
return nil, trace.Wrap(err)
}
log.Infof("no teleport login given. defaulting to %s", c.Username)
}
if c.ProxyHostPort == "" {
return nil, trace.BadParameter("No proxy address specified, missed --proxy flag?")
}
if c.HostLogin == "" {
c.HostLogin, err = Username()
if err != nil {
return nil, trace.Wrap(err)
}
log.Infof("no host login given. defaulting to %s", c.HostLogin)
}
if c.KeyTTL == 0 {
c.KeyTTL = defaults.CertDuration
} else if c.KeyTTL > defaults.MaxCertDuration || c.KeyTTL < defaults.MinCertDuration {
return nil, trace.BadParameter("invalid requested cert TTL")
}
c.Namespace = services.ProcessNamespace(c.Namespace)
tc = &TeleportClient{Config: *c}
if tc.Stdout == nil {
tc.Stdout = os.Stdout
}
if tc.Stderr == nil {
tc.Stderr = os.Stderr
}
if tc.Stdin == nil {
tc.Stdin = os.Stdin
}
// sometimes we need to use external auth without using local auth
// methods, e.g. in automation daemons
if c.SkipLocalAuth {
if len(c.AuthMethods) == 0 {
return nil, trace.BadParameter("SkipLocalAuth is true but no AuthMethods provided")
}
if c.TLS == nil {
return nil, trace.BadParameter("SkipLocalAuth is true but no TLS config is provided")
}
// if the client was passed an agent in the configuration and skip local auth, use
// the passed in agent.
if c.Agent != nil {
tc.localAgent = &LocalKeyAgent{Agent: c.Agent}
}
} else {
// initialize the local agent (auth agent which uses local SSH keys signed by the CA):
tc.localAgent, err = NewLocalAgent(c.KeysDir, c.Username)
if err != nil {
return nil, trace.Wrap(err)
}
if tc.HostKeyCallback == nil {
tc.HostKeyCallback = tc.localAgent.CheckHostSignature
}
}
return tc, nil
}
// accessPoint returns access point based on the cache policy
func (tc *TeleportClient) accessPoint(clt auth.AccessPoint, proxyHostPort string, clusterName string) (auth.AccessPoint, error) {
if tc.CachePolicy == nil {
log.Debugf("not using caching access point")
return clt, nil
}
dirPath, err := initKeysDir(tc.KeysDir)
if err != nil {
return nil, trace.Wrap(err)
}
path := filepath.Join(dirPath, "cache", proxyHostPort, clusterName)
log.Debugf("using caching access point %v", path)
cacheBackend, err := dir.New(backend.Params{"path": path})
if err != nil {
return nil, trace.Wrap(err)
}
// make a caching auth client for the auth server:
return state.NewCachingAuthClient(state.Config{
SkipPreload: true,
AccessPoint: clt,
Backend: cacheBackend,
CacheTTL: tc.CachePolicy.CacheTTL,
NeverExpires: tc.CachePolicy.NeverExpires,
})
}
func (tc *TeleportClient) LocalAgent() *LocalKeyAgent {
return tc.localAgent
}
// getTargetNodes returns a list of node addresses this SSH command needs to
// operate on.
func (tc *TeleportClient) getTargetNodes(ctx context.Context, proxy *ProxyClient) ([]string, error) {
var (
err error
nodes []services.Server
retval = make([]string, 0)
)
if tc.Labels != nil && len(tc.Labels) > 0 {
nodes, err = proxy.FindServersByLabels(ctx, tc.Namespace, tc.Labels)
if err != nil {
return nil, trace.Wrap(err)
}
for i := 0; i < len(nodes); i++ {
retval = append(retval, nodes[i].GetAddr())
}
}
if len(nodes) == 0 {
retval = append(retval, net.JoinHostPort(tc.Host, strconv.Itoa(tc.HostPort)))
}
return retval, nil
}
// SSH connects to a node and, if 'command' is specified, executes the command on it,
// otherwise runs interactive shell
//
// Returns nil if successful, or (possibly) *exec.ExitError
func (tc *TeleportClient) SSH(ctx context.Context, command []string, runLocally bool) error {
// connect to proxy first:
if !tc.Config.ProxySpecified() {
return trace.BadParameter("proxy server is not specified")
}
proxyClient, err := tc.ConnectToProxy()
if err != nil {
return trace.Wrap(err)
}
defer proxyClient.Close()
siteInfo, err := proxyClient.currentCluster()
if err != nil {
return trace.Wrap(err)
}
// which nodes are we executing this commands on?
nodeAddrs, err := tc.getTargetNodes(ctx, proxyClient)
if err != nil {
return trace.Wrap(err)
}
if len(nodeAddrs) == 0 {
return trace.BadParameter("no target host specified")
}
// more than one node for an interactive shell?
// that can't be!
if len(nodeAddrs) != 1 {
fmt.Printf(
"\x1b[1mWARNING\x1b[0m: multiple nodes match the label selector. Picking %v (first)\n",
nodeAddrs[0])
}
nodeClient, err := proxyClient.ConnectToNode(
ctx,
nodeAddrs[0]+"@"+tc.Namespace+"@"+siteInfo.Name,
tc.Config.HostLogin,
false)
if err != nil {
tc.ExitStatus = 1
return trace.Wrap(err)
}
// proxy local ports (forward incoming connections to remote host ports)
tc.startPortForwarding(nodeClient)
// local execution?
if runLocally {
if len(tc.Config.LocalForwardPorts) == 0 {
fmt.Println("Executing command locally without connecting to any servers. This makes no sense.")
}
return runLocalCommand(command)
}
// execute command(s) or a shell on remote node(s)
if len(command) > 0 {
return tc.runCommand(ctx, siteInfo.Name, nodeAddrs, proxyClient, command)
}
return tc.runShell(nodeClient, nil)
}
func (tc *TeleportClient) startPortForwarding(nodeClient *NodeClient) error {
if len(tc.Config.LocalForwardPorts) > 0 {
for _, fp := range tc.Config.LocalForwardPorts {
socket, err := net.Listen("tcp", net.JoinHostPort(fp.SrcIP, strconv.Itoa(fp.SrcPort)))
if err != nil {
return trace.Wrap(err)
}
go nodeClient.listenAndForward(socket, net.JoinHostPort(fp.DestHost, strconv.Itoa(fp.DestPort)))
}
}
return nil
}
// Join connects to the existing/active SSH session
func (tc *TeleportClient) Join(ctx context.Context, namespace string, sessionID session.ID, input io.Reader) (err error) {
if namespace == "" {
return trace.BadParameter(auth.MissingNamespaceError)
}
tc.Stdin = input
if sessionID.Check() != nil {
return trace.Errorf("Invalid session ID format: %s", string(sessionID))
}
var notFoundErrorMessage = fmt.Sprintf("session '%s' not found or it has ended", sessionID)
// connect to proxy:
if !tc.Config.ProxySpecified() {
return trace.BadParameter("proxy server is not specified")
}
proxyClient, err := tc.ConnectToProxy()
if err != nil {
return trace.Wrap(err)
}
defer proxyClient.Close()
site, err := proxyClient.ConnectToSite(ctx, false)
if err != nil {
return trace.Wrap(err)
}
// find the session ID on the site:
sessions, err := site.GetSessions(namespace)
if err != nil {
return trace.Wrap(err)
}
var session *session.Session
for _, s := range sessions {
if s.ID == sessionID {
session = &s
break
}
}
if session == nil {
return trace.NotFound(notFoundErrorMessage)
}
// pick the 1st party of the session and use his server ID to connect to
if len(session.Parties) == 0 {
return trace.NotFound(notFoundErrorMessage)
}
serverID := session.Parties[0].ServerID
// find a server address by its ID
nodes, err := site.GetNodes(namespace)
if err != nil {
return trace.Wrap(err)
}
var node services.Server
for _, n := range nodes {
if n.GetName() == serverID {
node = n
break
}
}
if node == nil {
return trace.NotFound(notFoundErrorMessage)
}
// connect to server:
fullNodeAddr := node.GetAddr()
if tc.SiteName != "" {
fullNodeAddr = fmt.Sprintf("%s@%s@%s", node.GetAddr(), tc.Namespace, tc.SiteName)
}
nc, err := proxyClient.ConnectToNode(ctx, fullNodeAddr, tc.Config.HostLogin, false)
if err != nil {
return trace.Wrap(err)
}
defer nc.Close()
// start forwarding ports, if configured:
tc.startPortForwarding(nc)
// running shell with a given session means "join" it:
return tc.runShell(nc, session)
}
// Play replays the recorded session
func (tc *TeleportClient) Play(ctx context.Context, namespace, sessionId string) (err error) {
if namespace == "" {
return trace.BadParameter(auth.MissingNamespaceError)
}
sid, err := session.ParseID(sessionId)
if err != nil {
return fmt.Errorf("'%v' is not a valid session ID (must be GUID)", sid)
}
// connect to the auth server (site) who made the recording
proxyClient, err := tc.ConnectToProxy()
if err != nil {
return trace.Wrap(err)
}
site, err := proxyClient.ConnectToSite(ctx, false)
if err != nil {
return trace.Wrap(err)
}
// request events for that session (to get timing data)
sessionEvents, err := site.GetSessionEvents(namespace, *sid, 0)
if err != nil {
return trace.Wrap(err)
}
// read the stream into a buffer:
var stream []byte
for err == nil {
tmp, err := site.GetSessionChunk(namespace, *sid, len(stream), events.MaxChunkBytes)
if err != nil {
return trace.Wrap(err)
}
if len(tmp) == 0 {
err = io.EOF
break
}
stream = append(stream, tmp...)
}
// configure terminal for direct unbuffered echo-less input:
if term.IsTerminal(0) {
state, err := term.SetRawTerminal(0)
if err != nil {
return nil
}
defer term.RestoreTerminal(0, state)
}
player := newSessionPlayer(sessionEvents, stream)
// keys:
const (
keyCtrlC = 3
keyCtrlD = 4
keySpace = 32
keyLeft = 68
keyRight = 67
keyUp = 65
keyDown = 66
)
// playback control goroutine
go func() {
defer player.Stop()
key := make([]byte, 1)
for {
_, err = os.Stdin.Read(key)
if err != nil {
return
}
switch key[0] {
// Ctrl+C or Ctrl+D
case keyCtrlC, keyCtrlD:
return
// Space key
case keySpace:
player.TogglePause()
// <- arrow
case keyLeft, keyDown:
player.Rewind()
// -> arrow
case keyRight, keyUp:
player.Forward()
}
}
}()
// player starts playing in its own goroutine
player.Play()
// wait for keypresses loop to end
<-player.stopC
fmt.Println("\n\nend of session playback")
return trace.Wrap(err)
}
// SCP securely copies file(s) from one SSH server to another
func (tc *TeleportClient) SCP(ctx context.Context, args []string, port int, recursive bool, quiet bool) (err error) {
if len(args) < 2 {
return trace.Errorf("Need at least two arguments for scp")
}
first := args[0]
last := args[len(args)-1]
// local copy?
if !isRemoteDest(first) && !isRemoteDest(last) {
return trace.BadParameter("making local copies is not supported")
}
if !tc.Config.ProxySpecified() {
return trace.BadParameter("proxy server is not specified")
}
log.Infof("Connecting to proxy to copy (recursively=%v)...", recursive)
proxyClient, err := tc.ConnectToProxy()
if err != nil {
return trace.Wrap(err)
}
defer proxyClient.Close()
// helper function connects to the src/target node:
connectToNode := func(addr string) (*NodeClient, error) {
// determine which cluster we're connecting to:
siteInfo, err := proxyClient.currentCluster()
if err != nil {
return nil, trace.Wrap(err)
}
return proxyClient.ConnectToNode(ctx, addr+"@"+tc.Namespace+"@"+siteInfo.Name, tc.HostLogin, false)
}
var progressWriter io.Writer
if !quiet {
progressWriter = tc.Stdout
}
// gets called to convert SSH error code to tc.ExitStatus
onError := func(err error) error {
exitError, _ := trace.Unwrap(err).(*ssh.ExitError)
if exitError != nil {
tc.ExitStatus = exitError.ExitStatus()
}
return err
}
// upload:
if isRemoteDest(last) {
login, host, dest := parseSCPDestination(last)
if login != "" {
tc.HostLogin = login
}
addr := net.JoinHostPort(host, strconv.Itoa(port))
client, err := connectToNode(addr)
if err != nil {
return trace.Wrap(err)
}
// copy everything except the last arg (that's destination)
for _, src := range args[:len(args)-1] {
err = client.Upload(src, dest, recursive, tc.Stderr, progressWriter)
if err != nil {
return onError(err)
}
}
// download:
} else {
login, host, src := parseSCPDestination(first)
addr := net.JoinHostPort(host, strconv.Itoa(port))
if login != "" {
tc.HostLogin = login
}
client, err := connectToNode(addr)
if err != nil {
return trace.Wrap(err)
}
// copy everything except the last arg (that's destination)
for _, dest := range args[1:] {
err = client.Download(src, dest, recursive, tc.Stderr, progressWriter)
if err != nil {
return onError(err)
}
}
}
return nil
}
// parseSCPDestination takes a string representing a remote resource for SCP
// to download/upload, like "user@host:/path/to/resource.txt" and returns
// 3 components of it
func parseSCPDestination(s string) (login, host, dest string) {
parts := strings.SplitN(s, "@", 2)
if len(parts) > 1 {
login = parts[0]
host = parts[1]
} else {
host = parts[0]
}
parts = strings.SplitN(host, ":", 2)
if len(parts) > 1 {
host = parts[0]
dest = parts[1]
}
if len(dest) == 0 {
dest = "."
}
return login, host, dest
}
func isRemoteDest(name string) bool {
return strings.IndexRune(name, ':') >= 0
}
// ListNodes returns a list of nodes connected to a proxy
func (tc *TeleportClient) ListNodes(ctx context.Context) ([]services.Server, error) {
var err error
// userhost is specified? that must be labels
if tc.Host != "" {
tc.Labels, err = ParseLabelSpec(tc.Host)
if err != nil {
return nil, trace.Wrap(err)
}
}
// connect to the proxy and ask it to return a full list of servers
proxyClient, err := tc.ConnectToProxy()
if err != nil {
return nil, trace.Wrap(err)
}
defer proxyClient.Close()
return proxyClient.FindServersByLabels(ctx, tc.Namespace, tc.Labels)
}
// runCommand executes a given bash command on a bunch of remote nodes
func (tc *TeleportClient) runCommand(
ctx context.Context, siteName string, nodeAddresses []string, proxyClient *ProxyClient, command []string) error {
resultsC := make(chan error, len(nodeAddresses))
for _, address := range nodeAddresses {
go func(address string) {
var (
err error
nodeSession *NodeSession
)
defer func() {
resultsC <- err
}()
var nodeClient *NodeClient
nodeClient, err = proxyClient.ConnectToNode(ctx, address+"@"+tc.Namespace+"@"+siteName, tc.Config.HostLogin, false)
if err != nil {
fmt.Fprintln(tc.Stderr, err)
return
}
defer nodeClient.Close()
// run the command on one node:
if len(nodeAddresses) > 1 {
fmt.Printf("Running command on %v:\n", address)
}
nodeSession, err = newSession(nodeClient, nil, tc.Config.Env, tc.Stdin, tc.Stdout, tc.Stderr)
if err != nil {
log.Error(err)
return
}
defer nodeSession.Close()
if err = nodeSession.runCommand(command, tc.OnShellCreated, tc.Config.Interactive); err != nil {
originErr := trace.Unwrap(err)
exitErr, ok := originErr.(*ssh.ExitError)
if ok {
tc.ExitStatus = exitErr.ExitStatus()
} else {
// if an error occurs, but no exit status is passed back, GoSSH returns
// a generic error like this. in this case the error message is printed
// to stderr by the remote process so we have to quietly return 1:
if strings.Contains(originErr.Error(), "exited without exit status") {
tc.ExitStatus = 1
}
}
}
}(address)
}
var lastError error
for range nodeAddresses {
if err := <-resultsC; err != nil {
lastError = err
}
}
return trace.Wrap(lastError)
}
// runShell starts an interactive SSH session/shell.
// sessionID : when empty, creates a new shell. otherwise it tries to join the existing session.
func (tc *TeleportClient) runShell(nodeClient *NodeClient, sessToJoin *session.Session) error {
nodeSession, err := newSession(nodeClient, sessToJoin, tc.Env, tc.Stdin, tc.Stdout, tc.Stderr)
if err != nil {
return trace.Wrap(err)
}
if err = nodeSession.runShell(tc.OnShellCreated); err != nil {
return trace.Wrap(err)
}
if nodeSession.ExitMsg == "" {
fmt.Fprintln(tc.Stderr, "the connection was closed on the remote side on ", time.Now().Format(time.RFC822))
} else {
fmt.Fprintln(tc.Stderr, nodeSession.ExitMsg)
}
return nil
}
// getProxyLogin determines which SSH principal to use when connecting to proxy.
func (tc *TeleportClient) getProxySSHPrincipal() string {
proxyPrincipal := tc.Config.HostLogin
if tc.DefaultPrincipal != "" {
proxyPrincipal = tc.DefaultPrincipal
}
// see if we already have a signed key in the cache, we'll use that instead
if !tc.Config.SkipLocalAuth && tc.LocalAgent() != nil {
signers, err := tc.LocalAgent().Signers()
if err != nil || len(signers) == 0 {
return proxyPrincipal
}
cert, ok := signers[0].PublicKey().(*ssh.Certificate)
if ok && len(cert.ValidPrincipals) > 0 {
return cert.ValidPrincipals[0]
}
}
return proxyPrincipal
}
// authMethods returns a list (slice) of all SSH auth methods this client
// can use to try to authenticate
func (tc *TeleportClient) authMethods() []ssh.AuthMethod {
m := append([]ssh.AuthMethod(nil), tc.Config.AuthMethods...)
if tc.LocalAgent() != nil {
m = append(m, tc.LocalAgent().AuthMethods()...)
}
return m
}
// ConnectToProxy dials the proxy server and returns ProxyClient if successful
func (tc *TeleportClient) ConnectToProxy() (*ProxyClient, error) {
var err error
proxyPrincipal := tc.getProxySSHPrincipal()
proxyAddr := tc.Config.ProxySSHHostPort()
sshConfig := &ssh.ClientConfig{
User: proxyPrincipal,
HostKeyCallback: tc.HostKeyCallback,
}
// helper to create a ProxyClient struct
makeProxyClient := func(sshClient *ssh.Client, m ssh.AuthMethod) *ProxyClient {
return &ProxyClient{
teleportClient: tc,
Client: sshClient,
proxyAddress: proxyAddr,
proxyPrincipal: proxyPrincipal,
hostKeyCallback: sshConfig.HostKeyCallback,
authMethod: m,
hostLogin: tc.Config.HostLogin,
siteName: tc.Config.SiteName,
clientAddr: tc.ClientAddr,
}
}
successMsg := fmt.Sprintf("[CLIENT] successful auth with proxy %v", proxyAddr)
// try to authenticate using every non interactive auth method we have:
for i, m := range tc.authMethods() {
log.Infof("[CLIENT] connecting proxy=%v login='%v' method=%d", proxyAddr, sshConfig.User, i)
var sshClient *ssh.Client
sshConfig.Auth = []ssh.AuthMethod{m}
sshClient, err = ssh.Dial("tcp", proxyAddr, sshConfig)
if err != nil {
if utils.IsHandshakeFailedError(err) {
log.Warn(err)
continue
}
return nil, trace.Wrap(err)
}
log.Infof(successMsg)
return makeProxyClient(sshClient, m), nil
}
// we have exhausted all auth existing auth methods and local login
// is disabled in configuration, or the user refused connecting to untrusted hosts
if tc.Config.SkipLocalAuth || tc.localAgent.UserRefusedHosts() {
if err == nil {
err = trace.BadParameter("failed to authenticate with proxy %v", proxyAddr)
}
return nil, trace.Wrap(err)
}
// if we get here, it means we failed to authenticate using stored keys
// and we need to ask for the login information
key, err := tc.Login(true)
if err != nil {
// we need to communicate directly to user here,
// otherwise user will see endless loop with no explanation
if trace.IsTrustError(err) {
fmt.Printf("Refusing to connect to untrusted proxy %v without --insecure flag\n", proxyAddr)