Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Validate role and region for mTLS #7023

Merged
merged 2 commits into from
Jan 30, 2020
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
74 changes: 61 additions & 13 deletions nomad/server.go
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,8 @@ package nomad
import (
"context"
"crypto/tls"
"crypto/x509"
"errors"
"fmt"
"io/ioutil"
"net"
Expand All @@ -11,6 +13,7 @@ import (
"path/filepath"
"sort"
"strconv"
"strings"
"sync"
"sync/atomic"
"time"
Expand Down Expand Up @@ -279,7 +282,7 @@ func NewServer(config *Config, consulCatalog consul.CatalogAPI) (*Server, error)
if err != nil {
return nil, err
}
incomingTLS, tlsWrap, err := getTLSConf(config.TLSConfig.EnableRPC, tlsConf)
incomingTLS, tlsWrap, err := getTLSConf(config.TLSConfig.EnableRPC, tlsConf, config.Region)
if err != nil {
return nil, err
}
Expand Down Expand Up @@ -447,25 +450,70 @@ func (s *Server) createRPCListener() (*net.TCPListener, error) {

// getTLSConf gets the server's TLS configuration based on the config supplied
// by the operator
func getTLSConf(enableRPC bool, tlsConf *tlsutil.Config) (*tls.Config, tlsutil.RegionWrapper, error) {
func getTLSConf(enableRPC bool, tlsConf *tlsutil.Config, region string) (*tls.Config, tlsutil.RegionWrapper, error) {
var tlsWrap tlsutil.RegionWrapper
var incomingTLS *tls.Config
if enableRPC {
tw, err := tlsConf.OutgoingTLSWrapper()
if err != nil {
return nil, nil, err
}
tlsWrap = tw
if !enableRPC {
return incomingTLS, tlsWrap, nil
}

itls, err := tlsConf.IncomingTLSConfig()
if err != nil {
return nil, nil, err
}
tlsWrap, err := tlsConf.OutgoingTLSWrapper()
if err != nil {
return nil, nil, err
}

itls, err := tlsConf.IncomingTLSConfig()
if err != nil {
return nil, nil, err
}

if tlsConf.VerifyServerHostname {
incomingTLS = itls.Clone()
incomingTLS.VerifyPeerCertificate = rpcNameAndRegionValidator(region)
} else {
incomingTLS = itls
}
return incomingTLS, tlsWrap, nil
}

// implements signature of tls.Config.VerifyPeerCertificate which is called
// after the certs have been verified. We'll ignore the raw certs and only
// check the verified certs.
func rpcNameAndRegionValidator(region string) func([][]byte, [][]*x509.Certificate) error {
return func(_ [][]byte, certificates [][]*x509.Certificate) error {
if len(certificates) > 0 && len(certificates[0]) > 0 {
cert := certificates[0][0]
for _, dnsName := range cert.DNSNames {
if validateRPCRegionPeer(dnsName, region) {
return nil
}
}
if validateRPCRegionPeer(cert.Subject.CommonName, region) {
return nil
}
}
return errors.New("invalid role or region for certificate")
}
}

func validateRPCRegionPeer(name, region string) bool {
parts := strings.Split(name, ".")
if len(parts) < 3 {
// Invalid SAN
return false
}
if parts[len(parts)-1] != "nomad" {
// Incorrect service
return false
}
if parts[0] == "client" {
// Clients may only connect to servers in their region
return name == "client."+region+".nomad"
}
// Servers may connect to any Nomad RPC service for federation.
return parts[0] == "server"
}

// reloadTLSConnections updates a server's TLS configuration and reloads RPC
// connections.
func (s *Server) reloadTLSConnections(newTLSConfig *config.TLSConfig) error {
Expand All @@ -483,7 +531,7 @@ func (s *Server) reloadTLSConnections(newTLSConfig *config.TLSConfig) error {
return err
}

incomingTLS, tlsWrap, err := getTLSConf(newTLSConfig.EnableRPC, tlsConf)
incomingTLS, tlsWrap, err := getTLSConf(newTLSConfig.EnableRPC, tlsConf, s.config.Region)
if err != nil {
s.logger.Error("unable to reset TLS context", "error", err)
return err
Expand Down
27 changes: 27 additions & 0 deletions nomad/server_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -558,3 +558,30 @@ func TestServer_InvalidSchedulers(t *testing.T) {
require.NotNil(err)
require.Contains(err.Error(), "foo")
}

func TestServer_RPCNameAndRegionValidation(t *testing.T) {
t.Parallel()
for _, tc := range []struct {
name string
region string
expected bool
}{
// OK
{name: "client.global.nomad", region: "global", expected: true},
{name: "server.global.nomad", region: "global", expected: true},
{name: "server.other.nomad", region: "global", expected: true},
{name: "server.other.region.nomad", region: "other.region", expected: true},

// Bad
{name: "client.other.nomad", region: "global", expected: false},
{name: "client.global.nomad.other", region: "global", expected: false},
{name: "server.global.nomad.other", region: "global", expected: false},
{name: "other.global.nomad", region: "global", expected: false},
{name: "server.nomad", region: "global", expected: false},
{name: "localhost", region: "global", expected: false},
} {
assert.Equal(t, tc.expected, validateRPCRegionPeer(tc.name, tc.region),
"expected %q in region %q to validate as %v",
tc.name, tc.region, tc.expected)
}
}
21 changes: 21 additions & 0 deletions website/source/guides/upgrade/upgrade-specific.html.md
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,25 @@ standard upgrade flow.

## Nomad 0.10.3

### mTLS Certificate Validation

Nomad 0.10.3 includes a fix for a privilege escalation vulnerability in
validating TLS certificates for RPC with mTLS. Nomad RPC endpoints validated
that TLS client certificates had not expired and were signed by the same CA as
the Nomad node, but did not correctly check the certificate's name for the role
and region as described in the [Securing Nomad with TLS][tls-guide] guide. This
allows trusted operators with a client certificate signed by the CA to send RPC
calls as a Nomad client or server node, bypassing access control and accessing
any secrets available to a client.

Nomad clusters configured for mTLS following the [Securing Nomad with TLS][tls-guide]
guide or the [Vault PKI Secrets Engine Integration][tls-vault-guide] guide
should already have certificates that will pass validation. Before upgrading to
Nomad 0.10.3, operators using mTLS with `verify_server_hostname = true` should
confirm that the common name or SAN of all Nomad client node certs is
`client.<region>.nomad`, and that the common name or SAN of all Nomad server
node certs is `server.<region>.nomad`.

### Connection Limits Added

Nomad 0.10.3 introduces the [limits][limits] agent configuration parameters for
Expand Down Expand Up @@ -419,3 +438,5 @@ deleted and then Nomad 0.3.0 can be launched.
[task-config]: /docs/job-specification/task.html#config
[validate]: /docs/commands/job/validate.html
[update]: /docs/job-specification/update.html
[tls-guide]: /guides/security/securing-nomad.html
[tls-vault-guide]: /guides/security/vault-pki-integration.html