Terminate the console session if the machine changed (#19)

go.mod

@@ -9,6 +9,6 @@ require (
 	github.com/metal-stack/metal-go v0.15.7
 	github.com/metal-stack/v v1.0.3
 	github.com/stretchr/testify v1.7.0
-	go.uber.org/zap v1.19.0
+	go.uber.org/zap v1.19.1
 	golang.org/x/crypto v0.0.0-20210817164053-32db794688a5
 )

go.sum

@@ -944,6 +944,8 @@ go.uber.org/atomic v1.7.0 h1:ADUqmZGgLDDfbSL9ZmPxKTybcoEYHgpYfELNoN+7hsw=
 go.uber.org/atomic v1.7.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
 go.uber.org/goleak v1.1.10 h1:z+mqJhf6ss6BSfSM671tgKyZBFPTTJM+HLxnhPC3wu0=
 go.uber.org/goleak v1.1.10/go.mod h1:8a7PlsEVH3e/a/GLqe5IIrQx6GzcnRmZEufDUTk4A7A=
+go.uber.org/goleak v1.1.11-0.20210813005559-691160354723 h1:sHOAIxRGBp443oHZIPB+HsUGaksVCXVQENPxwTfQdH4=
+go.uber.org/goleak v1.1.11-0.20210813005559-691160354723/go.mod h1:cwTWslyiVhfpKIDGSZEM2HlOvcqm+tG4zioyIeLoqMQ=
 go.uber.org/multierr v1.1.0/go.mod h1:wR5kodmAFQ0UK8QlbwjlSNy0Z68gJhDJUG5sjR94q/0=
 go.uber.org/multierr v1.5.0/go.mod h1:FeouvMocqHpRaaGuG9EjoKcStLC43Zu/fmqdUMPcKYU=
 go.uber.org/multierr v1.6.0 h1:y6IPFStTAIT5Ytl7/XYmHvzXQ7S3g/IeZW9hyZ5thw4=
@@ -955,6 +957,8 @@ go.uber.org/zap v1.17.0/go.mod h1:MXVU+bhUf/A7Xi2HNOnopQOrmycQ5Ih87HtOu4q5SSo=
 go.uber.org/zap v1.18.1/go.mod h1:xg/QME4nWcxGxrpdeYfq7UvYrLh66cuVKdrbD1XF/NI=
 go.uber.org/zap v1.19.0 h1:mZQZefskPPCMIBCSEH0v2/iUqqLrYtaeqwD6FUGUnFE=
 go.uber.org/zap v1.19.0/go.mod h1:xg/QME4nWcxGxrpdeYfq7UvYrLh66cuVKdrbD1XF/NI=
+go.uber.org/zap v1.19.1 h1:ue41HOKd1vGURxrmeKIgELGb3jPW9DMUDGtsinblHwI=
+go.uber.org/zap v1.19.1/go.mod h1:j3DNczoxDZroyBnOT1L/Q79cfUMGZxlv/9dzN7SM1rI=
 golang.org/x/crypto v0.0.0-20171113213409-9f005a07e0d3/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/crypto v0.0.0-20180904163835-0709b304e793/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/crypto v0.0.0-20181009213950-7c1a557ab941/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
@@ -1273,6 +1277,7 @@ golang.org/x/tools v0.0.0-20210114065538-d78b04bdf963/go.mod h1:emZCQorbCU4vsT4f
 golang.org/x/tools v0.1.0/go.mod h1:xkSsbof2nBLbhDlRMhhhyNLN/zl3eTqcnHD5viDpcZ0=
 golang.org/x/tools v0.1.2 h1:kRBLX7v7Af8W7Gdbbc908OJcdgtK8bOz9Uaj8/F1ACA=
 golang.org/x/tools v0.1.2/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
+golang.org/x/tools v0.1.5/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

internal/console/consoleServer.go

@@ -7,9 +7,11 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"reflect"
 	"runtime"
 	"strings"
 	"sync"
+	"time"
 
 	metalgo "github.com/metal-stack/metal-go"
 	"github.com/metal-stack/metal-go/api/models"
@@ -20,10 +22,11 @@ import (
 )
 
 type consoleServer struct {
-	log    *zap.SugaredLogger
-	client *metalgo.Driver
-	spec   *Specification
-	ips    *sync.Map
+	log     *zap.SugaredLogger
+	client  *metalgo.Driver
+	spec    *Specification
+	ips     *sync.Map
+	pubKeys *sync.Map
 }
 
 func NewServer(log *zap.SugaredLogger, spec *Specification) (*consoleServer, error) {
@@ -32,10 +35,11 @@ func NewServer(log *zap.SugaredLogger, spec *Specification) (*consoleServer, err
 		return nil, err
 	}
 	return &consoleServer{
-		log:    log,
-		client: client,
-		spec:   spec,
-		ips:    new(sync.Map),
+		log:     log,
+		client:  client,
+		spec:    spec,
+		ips:     new(sync.Map),
+		pubKeys: new(sync.Map),
 	}, nil
 }
 
@@ -126,10 +130,6 @@ func (cs *consoleServer) sessionHandler(s ssh.Session) {
 		}
 	}
 
-	defer func() {
-		cs.exitSession(s)
-	}()
-
 	mgmtServiceAddress := m.Partition.Mgmtserviceaddress
 
 	if cs.spec.DevMode() {
@@ -162,6 +162,9 @@ func (cs *consoleServer) sessionHandler(s ssh.Session) {
 
 	cs.redirectIO(s, sshSession, done)
 
+	// check periodically if the session is still allowed.
+	go cs.terminateIfPublicKeysChanged(s)
+
 	err = sshSession.Start("bash")
 	if err != nil {
 		cs.log.Errorw("failed to start bash via SSH session", "error", err)
@@ -172,6 +175,57 @@ func (cs *consoleServer) sessionHandler(s ssh.Session) {
 	<-done
 }
 
+func (cs *consoleServer) terminateIfPublicKeysChanged(s ssh.Session) {
+	machineID := s.User()
+	ticker := time.NewTicker(20 * time.Second)
+	defer ticker.Stop()
+	done := make(chan bool)
+	for {
+		select {
+		case <-done:
+			return
+		case <-s.Context().Done():
+			cs.log.Infow("connection closed", "machine", machineID)
+			done <- true
+			continue
+		case <-ticker.C:
+			cs.log.Infow("checking if machine is still owned by the same user", "machine", machineID)
+
+			m, err := cs.client.MachineGet(machineID)
+			if err != nil {
+				cs.log.Warnw("unable to load machine", "machineID", machineID, "error", err)
+			}
+			if m.Machine == nil {
+				cs.log.Warnw("unable to load machine is nil", "machineID", machineID)
+			}
+			if m.Machine.Allocation == nil {
+				_, _ = io.WriteString(s, "machine is not allocated anymore, terminating console session\n")
+				cs.log.Infow("machine is not allocated anymore, terminating ssh session", "machineID", machineID)
+				cs.pubKeys.Delete(machineID)
+				cs.exitSession(s)
+				done <- true
+				continue
+			}
+			keys, ok := cs.pubKeys.Load(machineID)
+			if !ok {
+				_, _ = io.WriteString(s, "public key of machine removed, terminating console session\n")
+				cs.log.Infow("no ssh public key stored anymore, terminating ssh session", "machineID", machineID)
+				cs.exitSession(s)
+				done <- true
+				continue
+			}
+			sshKeys := keys.([]string)
+			if !reflect.DeepEqual(sshKeys, m.Machine.Allocation.SSHPubKeys) {
+				_, _ = io.WriteString(s, "public key of machine changed, terminating console session\n")
+				cs.log.Infow("ssh public keys changed, terminating ssh session", "machineID", machineID)
+				cs.exitSession(s)
+				done <- true
+				continue
+			}
+		}
+	}
+}
+
 func (cs *consoleServer) exitSession(session ssh.Session) {
 	err := session.Exit(1)
 	if err != nil {
@@ -374,8 +428,13 @@ func (cs *consoleServer) getAuthorizedKeysForMachine(machineID string) ([]ssh.Pu
 	if privateIP == "" {
 		return nil, fmt.Errorf("failed to detect private IP of machine:%s", machineID)
 	}
+
 	cs.ips.Store(machineID, privateIP)
 
+	_, ok := cs.pubKeys.Load(machineID)
+	if !ok {
+		cs.pubKeys.Store(machineID, resp.Allocation.SSHPubKeys)
+	}
 	var pubKeys []ssh.PublicKey
 	for _, key := range resp.Allocation.SSHPubKeys {
 		pubKey, _, _, _, err := ssh.ParseAuthorizedKey([]byte(key))