forked from gravitational/teleport
/
auth.go
159 lines (135 loc) · 4.65 KB
/
auth.go
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/*
* Teleport
* Copyright (C) 2023 Gravitational, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package sqlserver
import (
"context"
"crypto/x509"
"encoding/pem"
"errors"
"strings"
"github.com/gravitational/trace"
"github.com/jcmturner/gokrb5/v8/client"
"github.com/jcmturner/gokrb5/v8/config"
"github.com/jcmturner/gokrb5/v8/keytab"
"github.com/jcmturner/gokrb5/v8/spnego"
"github.com/gravitational/teleport/lib/auth/windows"
"github.com/gravitational/teleport/lib/srv/db/common"
"github.com/gravitational/teleport/lib/srv/db/sqlserver/kinit"
)
var (
errBadCertificate = errors.New("invalid certificate was provided via AD configuration")
)
// keytabClient returns a kerberos client using a keytab file
func (c *connector) keytabClient(session *common.Session) (*client.Client, error) {
// Load keytab.
kt, err := keytab.Load(session.Database.GetAD().KeytabFile)
if err != nil {
return nil, trace.Wrap(err)
}
// Load krb5.conf.
conf, err := config.Load(session.Database.GetAD().Krb5File)
if err != nil {
return nil, trace.Wrap(err)
}
// Create Kerberos client.
kbClient := client.NewWithKeytab(
session.DatabaseUser,
session.Database.GetAD().Domain,
kt,
conf,
// Active Directory does not commonly support FAST negotiation.
client.DisablePAFXFAST(true))
// Login.
err = kbClient.Login()
return kbClient, err
}
// kinitClient returns a kerberos client using a kinit ccache
func (c *connector) kinitClient(ctx context.Context, session *common.Session, auth windows.AuthInterface, dataDir string) (*client.Client, error) {
ldapPem, _ := pem.Decode([]byte(session.Database.GetAD().LDAPCert))
if ldapPem == nil {
return nil, trace.Wrap(errBadCertificate)
}
cert, err := x509.ParseCertificate(ldapPem.Bytes)
if err != nil {
return nil, trace.Wrap(err)
}
certGetter := &kinit.DBCertGetter{
Auth: auth,
KDCHostName: strings.ToUpper(session.Database.GetAD().KDCHostName),
RealmName: session.Database.GetAD().Domain,
AdminServerName: session.Database.GetAD().KDCHostName,
UserName: session.DatabaseUser,
LDAPCA: cert,
}
realmName := strings.ToUpper(session.Database.GetAD().Domain)
k := kinit.New(kinit.NewCommandLineInitializer(
kinit.CommandConfig{
AuthClient: auth,
User: session.DatabaseUser,
Realm: realmName,
KDCHost: session.Database.GetAD().KDCHostName,
AdminServer: session.Database.GetAD().Domain,
DataDir: dataDir,
LDAPCA: cert,
LDAPCAPEM: session.Database.GetAD().LDAPCert,
Command: c.kinitCommandGenerator,
CertGetter: certGetter,
}))
// create the kinit credentials cache using the previously prepared cert/key pair
cc, conf, err := k.UseOrCreateCredentialsCache(ctx)
if err != nil {
return nil, trace.Wrap(err)
}
// Create Kerberos client from ccache. No need to login, `kinit` will have already done that.
return client.NewFromCCache(cc, conf, client.DisablePAFXFAST(true))
}
// getAuth returns Kerberos authenticator used by SQL Server driver.
//
// TODO(r0mant): Unit-test this. In-memory Kerberos server?
func (c *connector) getAuth(sessionCtx *common.Session, kbClient *client.Client) (*krbAuth, error) {
// Obtain service ticket for the database's Service Principal Name.
ticket, encryptionKey, err := kbClient.GetServiceTicket(sessionCtx.Database.GetAD().SPN)
if err != nil {
return nil, trace.Wrap(err)
}
// Create init negotiation token.
initToken, err := spnego.NewNegTokenInitKRB5(kbClient, ticket, encryptionKey)
if err != nil {
return nil, trace.Wrap(err)
}
// Marshal init negotiation token.
initTokenBytes, err := initToken.Marshal()
if err != nil {
return nil, trace.Wrap(err)
}
return &krbAuth{
initToken: initTokenBytes,
}, nil
}
// krbAuth implements SQL Server driver's "auth" interface used during login
// to provide Kerberos authentication.
type krbAuth struct {
initToken []byte
}
func (a *krbAuth) InitialBytes() ([]byte, error) {
return a.initToken, nil
}
func (a *krbAuth) NextBytes(bytes []byte) ([]byte, error) {
return nil, nil
}
func (a *krbAuth) Free() {}