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AUTH-2036: Refactor user retrieval, shutdown after ssh server stops, add custom version string

This commit is contained in:
Michael Borkenstein 2019-09-04 10:37:53 -05:00
parent ee588eeeaa
commit d3b254f9ae
5 changed files with 60 additions and 67 deletions
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6
cmd/cloudflared/tunnel/cmd.go
View File

@ -387,7 +387,7 @@ func StartServer(c *cli.Context, version string, shutdownC, graceShutdownC chan
}
sshServerAddress := "127.0.0.1:" + c.String(sshPortFlag)
server, err := sshserver.New(logManager, logger, sshServerAddress, shutdownC, c.Duration(sshIdleTimeoutFlag), c.Duration(sshMaxTimeoutFlag))
server, err := sshserver.New(logManager, logger, version, sshServerAddress, shutdownC, c.Duration(sshIdleTimeoutFlag), c.Duration(sshMaxTimeoutFlag))
if err != nil {
logger.WithError(err).Error("Cannot create new SSH Server")
return errors.Wrap(err, "Cannot create new SSH Server")
@ -398,6 +398,8 @@ func StartServer(c *cli.Context, version string, shutdownC, graceShutdownC chan
if err = server.Start(); err != nil && err != ssh.ErrServerClosed {
logger.WithError(err).Error("SSH server error")
}
// TODO: remove when declarative tunnels are implemented.
close(shutdownC)
}()
c.Set("url", "ssh://"+sshServerAddress)
}
@ -966,7 +968,7 @@ func tunnelFlags(shouldHide bool) []cli.Flag {
altsrc.NewStringFlag(&cli.StringFlag{
Name: sshPortFlag,
Usage: "Localhost port that cloudflared SSH server will run on",
Value: "22",
Value: "2222",
EnvVars: []string{"LOCAL_SSH_PORT"},
Hidden: true,
}),

23
sshserver/authentication.go
View File

@ -27,7 +27,15 @@ func (s *SSHServer) configureAuthentication() {
s.PublicKeyHandler = s.authenticationHandler
}
// authenticationHandler is a callback that returns true if the user attempting to connect is authenticated.
func (s *SSHServer) authenticationHandler(ctx ssh.Context, key ssh.PublicKey) bool {
sshUser, err := lookupUser(ctx.User())
if err != nil {
s.logger.Debugf("Invalid user: %s", ctx.User())
return false
}
ctx.SetValue("sshUser", sshUser)
cert, ok := key.(*gossh.Certificate)
if !ok {
return s.authorizedKeyHandler(ctx, key)
@ -36,9 +44,9 @@ func (s *SSHServer) authenticationHandler(ctx ssh.Context, key ssh.PublicKey) bo
}
func (s *SSHServer) authorizedKeyHandler(ctx ssh.Context, key ssh.PublicKey) bool {
sshUser, err := s.getUserFunc(ctx.User())
if err != nil {
s.logger.Debugf("Invalid user: %s", ctx.User())
sshUser, ok := ctx.Value("sshUser").(*User)
if !ok {
s.logger.Error("Failed to retrieve user from context")
return false
}
@ -55,7 +63,6 @@ func (s *SSHServer) authorizedKeyHandler(ctx ssh.Context, key ssh.PublicKey) boo
}
for len(authorizedKeysBytes) > 0 {
// Skips invalid keys. Returns error if no valid keys remain.
pubKey, _, _, rest, err := ssh.ParseAuthorizedKey(authorizedKeysBytes)
authorizedKeysBytes = rest
@ -65,7 +72,6 @@ func (s *SSHServer) authorizedKeyHandler(ctx ssh.Context, key ssh.PublicKey) boo
}
if ssh.KeysEqual(pubKey, key) {
ctx.SetValue("sshUser", sshUser)
return true
}
}
@ -83,13 +89,6 @@ func (s *SSHServer) shortLivedCertHandler(ctx ssh.Context, cert *gossh.Certifica
if err := checker.CheckCert(ctx.User(), cert); err != nil {
s.logger.Debug(err)
return false
} else {
sshUser, err := s.getUserFunc(ctx.User())
if err != nil {
s.logger.Debugf("Invalid user: %s", ctx.User())
return false
}
ctx.SetValue("sshUser", sshUser)
}
return true
}

70
sshserver/authentication_test.go
View File

@ -22,7 +22,6 @@ import (
)
const (
validPrincipal = "testUser"
testDir = "testdata"
testUserKeyFilename = "id_rsa.pub"
testCAFilename = "ca.pub"
@ -30,7 +29,10 @@ const (
testUserCertFilename = "id_rsa-cert.pub"
)
var logger, hook = test.NewNullLogger()
var (
logger, hook = test.NewNullLogger()
mockUser = &User{Username: "testUser", HomeDir: testDir}
)
func TestMain(m *testing.M) {
authorizedKeysDir = testUserKeyFilename
@ -40,20 +42,20 @@ func TestMain(m *testing.M) {
}
func TestPublicKeyAuth_Success(t *testing.T) {
context, cancel := newMockContext(validPrincipal)
context, cancel := newMockContext(mockUser)
defer cancel()
sshServer := SSHServer{getUserFunc: getMockUser}
sshServer := SSHServer{logger: logger}
pubKey := getKey(t, testUserKeyFilename)
assert.True(t, sshServer.authorizedKeyHandler(context, pubKey))
}
func TestPublicKeyAuth_MissingKey(t *testing.T) {
context, cancel := newMockContext(validPrincipal)
context, cancel := newMockContext(mockUser)
defer cancel()
sshServer := SSHServer{logger: logger, getUserFunc: getMockUser}
sshServer := SSHServer{logger: logger}
pubKey := getKey(t, testOtherCAFilename)
assert.False(t, sshServer.authorizedKeyHandler(context, pubKey))
@ -61,23 +63,27 @@ func TestPublicKeyAuth_MissingKey(t *testing.T) {
}
func TestPublicKeyAuth_InvalidUser(t *testing.T) {
context, cancel := newMockContext("notAUser")
context, cancel := newMockContext(&User{Username: "notAUser"})
defer cancel()
sshServer := SSHServer{logger: logger, getUserFunc: lookupUser}
sshServer := SSHServer{logger: logger}
pubKey := getKey(t, testUserKeyFilename)
assert.False(t, sshServer.authorizedKeyHandler(context, pubKey))
assert.False(t, sshServer.authenticationHandler(context, pubKey))
assert.Contains(t, hook.LastEntry().Message, "Invalid user")
}
func TestPublicKeyAuth_MissingFile(t *testing.T) {
currentUser, err := user.Current()
tempUser, err := user.Current()
require.Nil(t, err)
context, cancel := newMockContext(currentUser.Username)
currentUser, err := lookupUser(tempUser.Username)
require.Nil(t, err)
require.Nil(t, err)
context, cancel := newMockContext(currentUser)
defer cancel()
sshServer := SSHServer{Server: ssh.Server{}, logger: logger, getUserFunc: lookupUser}
sshServer := SSHServer{Server: ssh.Server{}, logger: logger}
pubKey := getKey(t, testUserKeyFilename)
assert.False(t, sshServer.authorizedKeyHandler(context, pubKey))
@ -85,11 +91,11 @@ func TestPublicKeyAuth_MissingFile(t *testing.T) {
}
func TestShortLivedCerts_Success(t *testing.T) {
context, cancel := newMockContext(validPrincipal)
context, cancel := newMockContext(mockUser)
defer cancel()
caCert := getKey(t, testCAFilename)
sshServer := SSHServer{logger: log.CreateLogger(), caCert: caCert, getUserFunc: getMockUser}
sshServer := SSHServer{logger: log.CreateLogger(), caCert: caCert}
userCert, ok := getKey(t, testUserCertFilename).(*gossh.Certificate)
require.True(t, ok)
@ -97,11 +103,11 @@ func TestShortLivedCerts_Success(t *testing.T) {
}
func TestShortLivedCerts_CAsDontMatch(t *testing.T) {
context, cancel := newMockContext(validPrincipal)
context, cancel := newMockContext(mockUser)
defer cancel()
caCert := getKey(t, testOtherCAFilename)
sshServer := SSHServer{logger: logger, caCert: caCert, getUserFunc: getMockUser}
sshServer := SSHServer{logger: logger, caCert: caCert}
userCert, ok := getKey(t, testUserCertFilename).(*gossh.Certificate)
require.True(t, ok)
@ -109,25 +115,12 @@ func TestShortLivedCerts_CAsDontMatch(t *testing.T) {
assert.Equal(t, "CA certificate does not match user certificate signer", hook.LastEntry().Message)
}
func TestShortLivedCerts_UserDoesNotExist(t *testing.T) {
context, cancel := newMockContext(validPrincipal)
defer cancel()
caCert := getKey(t, testCAFilename)
sshServer := SSHServer{logger: logger, caCert: caCert, getUserFunc: lookupUser}
userCert, ok := getKey(t, testUserCertFilename).(*gossh.Certificate)
require.True(t, ok)
assert.False(t, sshServer.shortLivedCertHandler(context, userCert))
assert.Contains(t, hook.LastEntry().Message, "Invalid user")
}
func TestShortLivedCerts_InvalidPrincipal(t *testing.T) {
context, cancel := newMockContext("notAUser")
context, cancel := newMockContext(&User{Username: "NotAUser"})
defer cancel()
caCert := getKey(t, testCAFilename)
sshServer := SSHServer{logger: logger, caCert: caCert, getUserFunc: lookupUser}
sshServer := SSHServer{logger: logger, caCert: caCert}
userCert, ok := getKey(t, testUserCertFilename).(*gossh.Certificate)
require.True(t, ok)
@ -135,14 +128,6 @@ func TestShortLivedCerts_InvalidPrincipal(t *testing.T) {
assert.Contains(t, hook.LastEntry().Message, "not in the set of valid principals for given certificate")
}
func getMockUser(_ string) (*User, error) {
return &User{
Username: validPrincipal,
HomeDir: testDir,
}, nil
}
func getKey(t *testing.T, filename string) ssh.PublicKey {
path := path.Join(testDir, filename)
bytes, err := ioutil.ReadFile(path)
@ -157,10 +142,13 @@ type mockSSHContext struct {
*sync.Mutex
}
func newMockContext(user string) (*mockSSHContext, context.CancelFunc) {
func newMockContext(user *User) (*mockSSHContext, context.CancelFunc) {
innerCtx, cancel := context.WithCancel(context.Background())
mockCtx := &mockSSHContext{innerCtx, &sync.Mutex{}}
mockCtx.SetValue("user", user)
mockCtx.SetValue("sshUser", user)
// This naming is confusing but we cant change it because this mocks the SSHContext struct in gliderlabs/ssh
mockCtx.SetValue("user", user.Username)
return mockCtx, cancel
}

12
sshserver/sshserver_unix.go
View File

@ -9,6 +9,7 @@ import (
"os"
"os/exec"
"os/user"
"runtime"
"strconv"
"syscall"
"time"
@ -27,11 +28,10 @@ type SSHServer struct {
logger *logrus.Logger
shutdownC chan struct{}
caCert ssh.PublicKey
getUserFunc func(string) (*User, error)
logManager sshlog.Manager
}
func New(logManager sshlog.Manager, logger *logrus.Logger, address string, shutdownC chan struct{}, idleTimeout, maxTimeout time.Duration) (*SSHServer, error) {
func New(logManager sshlog.Manager, logger *logrus.Logger, version, address string, shutdownC chan struct{}, idleTimeout, maxTimeout time.Duration) (*SSHServer, error) {
currentUser, err := user.Current()
if err != nil {
return nil, err
@ -41,10 +41,14 @@ func New(logManager sshlog.Manager, logger *logrus.Logger, address string, shutd
}
sshServer := SSHServer{
Server: ssh.Server{Addr: address, MaxTimeout: maxTimeout, IdleTimeout: idleTimeout},
Server: ssh.Server{
Addr: address,
MaxTimeout: maxTimeout,
IdleTimeout: idleTimeout,
Version: fmt.Sprintf("SSH-2.0-Cloudflare-Access_%s_%s", version, runtime.GOOS),
},
logger: logger,
shutdownC: shutdownC,
getUserFunc: lookupUser,
logManager: logManager,
}

2
sshserver/sshserver_windows.go
View File

@ -13,7 +13,7 @@ import (
type SSHServer struct{}
func New(_ sshlog.Manager, _ *logrus.Logger, _ string, _ chan struct{}, _, _ time.Duration) (*SSHServer, error) {
func New(_ sshlog.Manager, _ *logrus.Logger, _, _ string, _ chan struct{}, _, _ time.Duration) (*SSHServer, error) {
return nil, errors.New("cloudflared ssh server is not supported on windows")
}