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[sec_scan][20] add ReportSecrets forwarder to proxy's gRPC insecure server #44324

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Jul 18, 2024
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90 changes: 11 additions & 79 deletions lib/auth/join/join.go
Original file line number Diff line number Diff line change
Expand Up @@ -18,43 +18,35 @@ package join

import (
"context"
"crypto/tls"
"crypto/x509"
"log/slog"
"os"
"slices"
"time"

"github.com/gravitational/trace"
"github.com/jonboulle/clockwork"
log "github.com/sirupsen/logrus"
"go.opentelemetry.io/otel"
"golang.org/x/net/http2"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials"

"github.com/gravitational/teleport"
"github.com/gravitational/teleport/api/breaker"
"github.com/gravitational/teleport/api/client"
"github.com/gravitational/teleport/api/client/proto"
"github.com/gravitational/teleport/api/constants"
apidefaults "github.com/gravitational/teleport/api/defaults"
"github.com/gravitational/teleport/api/metadata"
"github.com/gravitational/teleport/api/observability/tracing"
"github.com/gravitational/teleport/api/types"
"github.com/gravitational/teleport/api/utils/aws"
"github.com/gravitational/teleport/lib/auth/authclient"
"github.com/gravitational/teleport/lib/auth/join/iam"
"github.com/gravitational/teleport/lib/auth/state"
"github.com/gravitational/teleport/lib/circleci"
proxyinsecureclient "github.com/gravitational/teleport/lib/client/proxy/insecure"
"github.com/gravitational/teleport/lib/cloud/imds/azure"
"github.com/gravitational/teleport/lib/cloud/imds/gcp"
"github.com/gravitational/teleport/lib/defaults"
"github.com/gravitational/teleport/lib/githubactions"
"github.com/gravitational/teleport/lib/gitlab"
"github.com/gravitational/teleport/lib/kubernetestoken"
"github.com/gravitational/teleport/lib/spacelift"
"github.com/gravitational/teleport/lib/srv/alpnproxy/common"
"github.com/gravitational/teleport/lib/tlsca"
"github.com/gravitational/teleport/lib/tpm"
"github.com/gravitational/teleport/lib/utils"
Expand Down Expand Up @@ -292,7 +284,16 @@ func registerThroughProxy(
switch params.JoinMethod {
case types.JoinMethodIAM, types.JoinMethodAzure, types.JoinMethodTPM:
// IAM and Azure join methods require gRPC client
conn, err := proxyJoinServiceConn(ctx, params, params.Insecure)
conn, err := proxyinsecureclient.NewConnection(
ctx,
proxyinsecureclient.ConnectionConfig{
ProxyServer: getHostAddresses(params)[0],
CipherSuites: params.CipherSuites,
Clock: params.Clock,
Insecure: params.Insecure,
Log: slog.Default(),
},
)
if err != nil {
return nil, trace.Wrap(err)
}
Expand Down Expand Up @@ -401,56 +402,6 @@ func registerThroughAuth(
return certs, trace.Wrap(err)
}

// proxyJoinServiceConn attempts to connect to the join service running on the
// proxy. The Proxy's TLS cert will be verified using the host's root CA pool
// (PKI) unless the --insecure flag was passed.
func proxyJoinServiceConn(
ctx context.Context, params RegisterParams, insecure bool,
) (*grpc.ClientConn, error) {
tlsConfig := utils.TLSConfig(params.CipherSuites)
tlsConfig.Time = params.Clock.Now
// set NextProtos for TLS routing, the actual protocol will be h2
tlsConfig.NextProtos = []string{string(common.ProtocolProxyGRPCInsecure), http2.NextProtoTLS}

if insecure {
tlsConfig.InsecureSkipVerify = true
log.Warnf("Joining cluster without validating the identity of the Proxy Server.")
}

// Check if proxy is behind a load balancer. If so, the connection upgrade
// will verify the load balancer's cert using system cert pool. This
// provides the same level of security as the client only verifies Proxy's
// web cert against system cert pool when connection upgrade is not
// required.
//
// With the ALPN connection upgrade, the tunneled TLS Routing request will
// skip verify as the Proxy server will present its host cert which is not
// fully verifiable at this point since the client does not have the host
// CAs yet before completing registration.
alpnConnUpgrade := client.IsALPNConnUpgradeRequired(ctx, getHostAddresses(params)[0], insecure)
if alpnConnUpgrade && !insecure {
tlsConfig.InsecureSkipVerify = true
tlsConfig.VerifyConnection = verifyALPNUpgradedConn(params.Clock)
}

dialer := client.NewDialer(
ctx,
apidefaults.DefaultIdleTimeout,
apidefaults.DefaultIOTimeout,
client.WithInsecureSkipVerify(insecure),
client.WithALPNConnUpgrade(alpnConnUpgrade),
)

conn, err := grpc.Dial(
getHostAddresses(params)[0],
grpc.WithContextDialer(client.GRPCContextDialer(dialer)),
grpc.WithUnaryInterceptor(metadata.UnaryClientInterceptor),
grpc.WithStreamInterceptor(metadata.StreamClientInterceptor),
grpc.WithTransportCredentials(credentials.NewTLS(tlsConfig)),
)
return conn, trace.Wrap(err)
}

func getHostAddresses(params RegisterParams) []string {
if !params.ProxyServer.IsEmpty() {
return []string{params.ProxyServer.String()}
Expand All @@ -459,25 +410,6 @@ func getHostAddresses(params RegisterParams) []string {
return utils.NetAddrsToStrings(params.AuthServers)
}

// verifyALPNUpgradedConn is a tls.Config.VerifyConnection callback function
// used by the tunneled TLS Routing request to verify the host cert of a Proxy
// behind a L7 load balancer.
//
// Since the client has not obtained the cluster CAs at this point, the
// presented cert cannot be fully verified yet. For now, this function only
// checks if "teleport.cluster.local" is present as one of the DNS names and
// verifies the cert is not expired.
func verifyALPNUpgradedConn(clock clockwork.Clock) func(tls.ConnectionState) error {
return func(server tls.ConnectionState) error {
for _, cert := range server.PeerCertificates {
if slices.Contains(cert.DNSNames, constants.APIDomain) && clock.Now().Before(cert.NotAfter) {
return nil
}
}
return trace.AccessDenied("server is not a Teleport proxy or server certificate is expired")
}
}

// insecureRegisterClient attempts to connects to the Auth Server using the
// CA on disk. If no CA is found on disk, Teleport will not verify the Auth
// Server it is connecting to.
Expand Down
47 changes: 0 additions & 47 deletions lib/auth/join/join_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,6 @@ package join

import (
"context"
"crypto/tls"
"errors"
"net"
"os"
Expand All @@ -40,7 +39,6 @@ import (
"github.com/gravitational/teleport/lib/auth/testauthority"
"github.com/gravitational/teleport/lib/defaults"
"github.com/gravitational/teleport/lib/events"
"github.com/gravitational/teleport/lib/fixtures"
"github.com/gravitational/teleport/lib/modules"
"github.com/gravitational/teleport/lib/tlsca"
"github.com/gravitational/teleport/lib/utils"
Expand Down Expand Up @@ -281,48 +279,3 @@ func newBotToken(t *testing.T, tokenName, botName string, role types.SystemRole,
require.NoError(t, err, "could not create bot token")
return token
}

func TestVerifyALPNUpgradedConn(t *testing.T) {
t.Parallel()

srv := newTestTLSServer(t)
proxy, err := auth.NewServerIdentity(srv.Auth(), "test-proxy", types.RoleProxy)
require.NoError(t, err)

tests := []struct {
name string
serverCert []byte
clock clockwork.Clock
checkError require.ErrorAssertionFunc
}{
{
name: "proxy verified",
serverCert: proxy.TLSCertBytes,
clock: srv.Clock(),
checkError: require.NoError,
},
{
name: "proxy expired",
serverCert: proxy.TLSCertBytes,
clock: clockwork.NewFakeClockAt(srv.Clock().Now().Add(defaults.CATTL + time.Hour)),
checkError: require.Error,
},
{
name: "not proxy",
serverCert: []byte(fixtures.TLSCACertPEM),
clock: srv.Clock(),
checkError: require.Error,
},
}

for _, test := range tests {
t.Run(test.name, func(t *testing.T) {
serverCert, err := utils.ReadCertificates(test.serverCert)
require.NoError(t, err)

test.checkError(t, verifyALPNUpgradedConn(test.clock)(tls.ConnectionState{
PeerCertificates: serverCert,
}))
})
}
}
136 changes: 136 additions & 0 deletions lib/client/proxy/insecure/insecure.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,136 @@
// Copyright 2024 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 insecure creates a client that access the proxy unauthenticated gRPC service.
package insecure

import (
"context"
"crypto/tls"
"log/slog"
"slices"

"github.com/gravitational/trace"
"github.com/jonboulle/clockwork"
"golang.org/x/net/http2"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials"

"github.com/gravitational/teleport/api/client"
"github.com/gravitational/teleport/api/constants"
apidefaults "github.com/gravitational/teleport/api/defaults"
"github.com/gravitational/teleport/api/metadata"
"github.com/gravitational/teleport/lib/srv/alpnproxy/common"
"github.com/gravitational/teleport/lib/utils"
)

// ConnectionConfig specifies parameters for the client to dial credentialless via the proxy.
type ConnectionConfig struct {
// ProxyServer is the address of the proxy server
ProxyServer string
// CipherSuites is a list of cipher suites to use for TLS client connection
CipherSuites []uint16
// Clock specifies the time provider. Will be used to override the time anchor
// for TLS certificate verification.
// Defaults to real clock if unspecified
Clock clockwork.Clock
// Insecure trusts the certificates from the Auth Server or Proxy during registration without verification.
Insecure bool
// Log is the logger.
Log *slog.Logger
}

// NewConnection attempts to connect to the proxy insecure grpc server.
// The Proxy's TLS cert will be verified using the host's root CA pool
// (PKI) unless the insecure flag was passed.
func NewConnection(
ctx context.Context, params ConnectionConfig,
) (*grpc.ClientConn, error) {
if params.ProxyServer == "" {
return nil, trace.BadParameter("missing ProxyServer")
}
if params.Clock == nil {
params.Clock = clockwork.NewRealClock()
}
if params.Log == nil {
params.Log = slog.Default()
}

tlsConfig, alpnConnUpgrade := buildTLSConfig(ctx, params)

dialer := client.NewDialer(
ctx,
apidefaults.DefaultIdleTimeout,
apidefaults.DefaultIOTimeout,
client.WithInsecureSkipVerify(params.Insecure),
client.WithALPNConnUpgrade(alpnConnUpgrade),
)

conn, err := grpc.NewClient(
params.ProxyServer,
grpc.WithContextDialer(client.GRPCContextDialer(dialer)),
grpc.WithUnaryInterceptor(metadata.UnaryClientInterceptor),
grpc.WithStreamInterceptor(metadata.StreamClientInterceptor),
grpc.WithTransportCredentials(credentials.NewTLS(tlsConfig)),
)
return conn, trace.Wrap(err)
}

// verifyALPNUpgradedConn is a tls.Config.VerifyConnection callback function
// used by the tunneled TLS Routing request to verify the host cert of a Proxy
// behind a L7 load balancer.
//
// Since the client has not obtained the cluster CAs at this point, the
// presented cert cannot be fully verified yet. For now, this function only
// checks if "teleport.cluster.local" is present as one of the DNS names and
// verifies the cert is not expired.
func verifyALPNUpgradedConn(clock clockwork.Clock) func(tls.ConnectionState) error {
return func(server tls.ConnectionState) error {
for _, cert := range server.PeerCertificates {
if slices.Contains(cert.DNSNames, constants.APIDomain) && clock.Now().Before(cert.NotAfter) {
return nil
}
}
return trace.AccessDenied("server is not a Teleport proxy or server certificate is expired")
}
}

func buildTLSConfig(ctx context.Context, params ConnectionConfig) (*tls.Config, bool) {
tlsConfig := utils.TLSConfig(params.CipherSuites)
tlsConfig.Time = params.Clock.Now
// set NextProtos for TLS routing, the actual protocol will be h2
tlsConfig.NextProtos = []string{string(common.ProtocolProxyGRPCInsecure), http2.NextProtoTLS}

if params.Insecure {
tlsConfig.InsecureSkipVerify = true
params.Log.WarnContext(ctx, "Connecting to the cluster without validating the identity of the Proxy Server.")
}

// Check if proxy is behind a load balancer. If so, the connection upgrade
// will verify the load balancer's cert using system cert pool. This
// provides the same level of security as the client only verifies Proxy's
// web cert against system cert pool when connection upgrade is not
// required.
//
// With the ALPN connection upgrade, the tunneled TLS Routing request will
// skip verify as the Proxy server will present its host cert which is not
// fully verifiable at this point since the client does not have the host
// CAs yet before completing registration.
alpnConnUpgrade := client.IsALPNConnUpgradeRequired(ctx, params.ProxyServer, params.Insecure)
if alpnConnUpgrade && !params.Insecure {
tlsConfig.InsecureSkipVerify = true
tlsConfig.VerifyConnection = verifyALPNUpgradedConn(params.Clock)
}
return tlsConfig, alpnConnUpgrade
}
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