feat: Allow master configuration for ssh key crypto system

docs/reference/deploy/master-config-reference.rst

@@ -1524,6 +1524,11 @@ Specifies configuration settings for SSH.
 
 Number of bits to use when generating RSA keys for SSH for tasks. Maximum size is 16384.
 
+``key_type``
+============
+
+Specifies the crypto system for SSH. Currently accepts ``RSA``, ``ECDSA`` or ``ED25519``.
+
 ``authz``
 =========
 

docs/release-notes/ssh-crypto-system.rst

@@ -0,0 +1,8 @@
+:orphan:
+
+**Improvements**
+
+-  Master Configuration: Add support for crypto system configuration for ssh connection.
+   ``security.key_type`` now accepts ``RSA``, ``ECDSA`` or ``ED25519``. Default key type is changed
+   from ``1024-bit RSA`` to ``ED25519``, since ``ED25519`` keys are faster and more secure than the
+   old default, and ``ED25519`` is also the default key type for ``ssh-keygen``.

harness/determined/cli/shell.py

@@ -1,7 +1,6 @@
 import argparse
 import contextlib
 import functools
-import getpass
 import os
 import pathlib
 import platform
@@ -22,9 +21,6 @@
 
 def start_shell(args: argparse.Namespace) -> None:
     sess = cli.setup_session(args)
-    data = {}
-    if args.passphrase:
-        data["passphrase"] = getpass.getpass("Enter new passphrase: ")
     config = ntsc.parse_config(args.config_file, None, args.config, args.volume)
     workspace_id = cli.workspace.get_workspace_id_from_args(args)
 
@@ -35,7 +31,6 @@ def start_shell(args: argparse.Namespace) -> None:
         args.template,
         context_path=args.context,
         includes=args.include,
-        data=data,
         workspace_id=workspace_id,
     )
     shell = bindings.v1LaunchShellResponse.from_json(resp).shell
@@ -280,12 +275,6 @@ def _open_shell(
                         help=ntsc.INCLUDE_DESC,
                     ),
                     cli.Arg("--config", action="append", default=[], help=ntsc.CONFIG_DESC),
-                    cli.Arg(
-                        "-p",
-                        "--passphrase",
-                        action="store_true",
-                        help="passphrase to encrypt the shell private key",
-                    ),
                     cli.Arg(
                         "--template",
                         type=str,

master/internal/api_shell.go

@@ -3,7 +3,6 @@ package internal
 import (
 	"archive/tar"
 	"context"
-	"encoding/json"
 	"fmt"
 	"strconv"
 
@@ -253,20 +252,7 @@ func (a *apiServer) LaunchShell(
 	}
 	maps.Copy(launchReq.Spec.Base.ExtraEnvVars, oidcPachydermEnvVars)
 
-	var passphrase *string
-	if len(req.Data) > 0 {
-		var data map[string]interface{}
-		if err = json.Unmarshal(req.Data, &data); err != nil {
-			return nil, status.Errorf(codes.Internal, "failed to parse data %s: %s", req.Data, err)
-		}
-		if pwd, ok := data["passphrase"]; ok {
-			if typed, typedOK := pwd.(string); typedOK {
-				passphrase = &typed
-			}
-		}
-	}
-
-	keys, err := ssh.GenerateKey(launchReq.Spec.Base.SSHRsaSize, passphrase)
+	keys, err := ssh.GenerateKey(launchReq.Spec.Base.SSHConfig)
 	if err != nil {
 		return nil, status.Error(codes.Internal, err.Error())
 	}

master/internal/api_user_intg_test.go

@@ -118,7 +118,7 @@ func setupAPITest(t *testing.T, pgdb *db.PgDB,
 				TaskContainerDefaults: model.TaskContainerDefaultsConfig{},
 				ResourceConfig:        *config.DefaultResourceConfig(),
 			},
-			taskSpec: &tasks.TaskSpec{SSHRsaSize: 1024},
+			taskSpec: &tasks.TaskSpec{SSHConfig: config.SSHConfig{KeyType: "ED25519"}},
 			allRms:   map[string]rm.ResourceManager{config.DefaultClusterName: mockRM},
 		},
 	}

master/internal/config/config.go

@@ -42,6 +42,15 @@ const (
 	preemptionScheduler       = "preemption"
 )
 
+const (
+	// KeyTypeRSA uses RSA.
+	KeyTypeRSA = "RSA"
+	// KeyTypeECDSA uses ECDSA.
+	KeyTypeECDSA = "ECDSA"
+	// KeyTypeED25519 uses ED25519.
+	KeyTypeED25519 = "ED25519"
+)
+
 type (
 	// ExperimentConfigPatch is the updatedble fields for patching an experiment.
 	ExperimentConfigPatch struct {
@@ -108,7 +117,7 @@ func DefaultConfig() *Config {
 				Group: "root",
 			},
 			SSH: SSHConfig{
-				RsaKeySize: 1024,
+				KeyType: KeyTypeED25519,
 			},
 			AuthZ: *DefaultAuthZConfig(),
 		},
@@ -452,7 +461,8 @@ type SecurityConfig struct {
 
 // SSHConfig is the configuration setting for SSH.
 type SSHConfig struct {
-	RsaKeySize int `json:"rsa_key_size"`
+	RsaKeySize int    `json:"rsa_key_size"`
+	KeyType    string `json:"key_type"`
 }
 
 // TLSConfig is the configuration for setting up serving over TLS.
@@ -475,10 +485,15 @@ func (t *TLSConfig) Validate() []error {
 // Validate implements the check.Validatable interface.
 func (t *SSHConfig) Validate() []error {
 	var errs []error
-	if t.RsaKeySize < 1 {
-		errs = append(errs, errors.New("RSA Key size must be greater than 0"))
-	} else if t.RsaKeySize > 16384 {
-		errs = append(errs, errors.New("RSA Key size must be less than 16,384"))
+	if t.KeyType != KeyTypeRSA && t.KeyType != KeyTypeECDSA && t.KeyType != KeyTypeED25519 {
+		errs = append(errs, errors.New("Crypto system must be one of 'RSA', 'ECDSA' or 'ED25519'"))
+	}
+	if t.KeyType == KeyTypeRSA {
+		if t.RsaKeySize < 1 {
+			errs = append(errs, errors.New("RSA Key size must be greater than 0"))
+		} else if t.RsaKeySize > 16384 {
+			errs = append(errs, errors.New("RSA Key size must be less than 16,384"))
+		}
 	}
 	return errs
 }

master/internal/core.go

@@ -1242,7 +1242,7 @@ func (m *Master) Run(ctx context.Context, gRPCLogInitDone chan struct{}) error {
 		HarnessPath:           filepath.Join(m.config.Root, "wheels"),
 		TaskContainerDefaults: m.config.TaskContainerDefaults,
 		MasterCert:            config.GetCertPEM(cert),
-		SSHRsaSize:            m.config.Security.SSH.RsaKeySize,
+		SSHConfig:             m.config.Security.SSH,
 		SegmentEnabled:        m.config.Telemetry.Enabled && m.config.Telemetry.SegmentMasterKey != "",
 		SegmentAPIKey:         m.config.Telemetry.SegmentMasterKey,
 		LogRetentionDays:      m.config.RetentionPolicy.LogRetentionDays,

master/internal/core_intg_test.go

@@ -121,7 +121,7 @@ func TestRun(t *testing.T) {
 						DefaultLoggingConfig: &model.DefaultLoggingConfig{},
 					},
 				},
-				taskSpec: &tasks.TaskSpec{SSHRsaSize: 1024},
+				taskSpec: &tasks.TaskSpec{SSHConfig: config.SSHConfig{KeyType: "ED25519"}},
 			}
 			require.NoError(t, m.config.Resolve())
 			m.config.DB = config.DBConfig{

master/internal/experiment.go

@@ -158,7 +158,7 @@ func newExperiment(
 
 	taskSpec.AgentUserGroup = agentUserGroup
 
-	generatedKeys, err := ssh.GenerateKey(taskSpec.SSHRsaSize, nil)
+	generatedKeys, err := ssh.GenerateKey(taskSpec.SSHConfig)
 	if err != nil {
 		return nil, nil, errors.Wrap(err, "generating ssh keys for trials")
 	}

master/internal/trial_intg_test.go

@@ -172,7 +172,6 @@ func setup(t *testing.T) (
 		&model.Checkpoint{},
 		&tasks.TaskSpec{
 			AgentUserGroup: &model.AgentUserGroup{},
-			SSHRsaSize:     1024,
 			Workspace:      model.DefaultWorkspaceName,
 		},
 		ssh.PrivateAndPublicKeys{},

master/pkg/ssh/ssh.go

@@ -1,17 +1,23 @@
 package ssh
 
 import (
+	"crypto/ecdsa"
+	"crypto/ed25519"
+	"crypto/elliptic"
 	"crypto/rand"
 	"crypto/rsa"
 	"crypto/x509"
 	"encoding/pem"
 
 	"github.com/pkg/errors"
 	sshlib "golang.org/x/crypto/ssh"
+
+	"github.com/determined-ai/determined/master/internal/config"
 )
 
 const (
-	trialPEMBlockType = "RSA PRIVATE KEY"
+	rsaPEMBlockType   = "RSA PRIVATE KEY"
+	ecdsaPEMBlockType = "EC PRIVATE KEY"
 )
 
 // PrivateAndPublicKeys contains a private and public key.
@@ -21,40 +27,93 @@ type PrivateAndPublicKeys struct {
 }
 
 // GenerateKey returns a private and public SSH key.
-func GenerateKey(rsaKeySize int, passphrase *string) (PrivateAndPublicKeys, error) {
+func GenerateKey(conf config.SSHConfig) (PrivateAndPublicKeys, error) {
 	var generatedKeys PrivateAndPublicKeys
+	switch conf.KeyType {
+	case config.KeyTypeRSA:
+		return generateRSAKey(conf.RsaKeySize)
+	case config.KeyTypeECDSA:
+		return generateECDSAKey()
+	case config.KeyTypeED25519:
+		return generateED25519Key()
+	default:
+		return generatedKeys, errors.New("Invalid crypto system")
+	}
+}
+
+func generateRSAKey(rsaKeySize int) (PrivateAndPublicKeys, error) {
 	privateKey, err := rsa.GenerateKey(rand.Reader, rsaKeySize)
 	if err != nil {
-		return generatedKeys, errors.Wrap(err, "unable to generate private key")
+		return PrivateAndPublicKeys{}, errors.Wrap(err, "unable to generate RSA private key")
 	}
 
 	if err = privateKey.Validate(); err != nil {
-		return generatedKeys, err
+		return PrivateAndPublicKeys{}, err
 	}
 
 	block := &pem.Block{
-		Type:  trialPEMBlockType,
+		Type:  rsaPEMBlockType,
 		Bytes: x509.MarshalPKCS1PrivateKey(privateKey),
 	}
 
-	if passphrase != nil {
-		// TODO: Replace usage of deprecated x509.EncryptPEMBlock.
-		block, err = x509.EncryptPEMBlock( //nolint: staticcheck
-			rand.Reader, block.Type, block.Bytes, []byte(*passphrase), x509.PEMCipherAES256)
-		if err != nil {
-			return generatedKeys, errors.Wrap(err, "unable to encrypt private key")
-		}
+	publicKey, err := sshlib.NewPublicKey(&privateKey.PublicKey)
+	if err != nil {
+		return PrivateAndPublicKeys{}, errors.Wrap(err, "unable to generate RSA public key")
+	}
+
+	return PrivateAndPublicKeys{
+		PrivateKey: pem.EncodeToMemory(block),
+		PublicKey:  sshlib.MarshalAuthorizedKey(publicKey),
+	}, nil
+}
+
+func generateECDSAKey() (PrivateAndPublicKeys, error) {
+	// Curve size currently not configurable, using the NIST recommendation.
+	privateKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		return PrivateAndPublicKeys{}, errors.Wrap(err, "unable to generate ECDSA private key")
+	}
+
+	privateKeyBytes, err := x509.MarshalECPrivateKey(privateKey)
+	if err != nil {
+		return PrivateAndPublicKeys{}, errors.Wrap(err, "unable to marshal ECDSA private key")
+	}
+
+	block := &pem.Block{
+		Type:  ecdsaPEMBlockType,
+		Bytes: privateKeyBytes,
 	}
 
 	publicKey, err := sshlib.NewPublicKey(&privateKey.PublicKey)
 	if err != nil {
-		return generatedKeys, errors.Wrap(err, "unable to generate public key")
+		return PrivateAndPublicKeys{}, errors.Wrap(err, "unable to generate ECDSA public key")
 	}
 
-	generatedKeys = PrivateAndPublicKeys{
+	return PrivateAndPublicKeys{
 		PrivateKey: pem.EncodeToMemory(block),
 		PublicKey:  sshlib.MarshalAuthorizedKey(publicKey),
+	}, nil
+}
+
+func generateED25519Key() (PrivateAndPublicKeys, error) {
+	ed25519PublicKey, privateKey, err := ed25519.GenerateKey(nil)
+	if err != nil {
+		return PrivateAndPublicKeys{}, errors.Wrap(err, "unable to generate ED25519 private key")
 	}
 
-	return generatedKeys, nil
+	// Before OpenSSH 9.6, for ED25519 keys, only the OpenSSH private key format was supported.
+	block, err := sshlib.MarshalPrivateKey(privateKey, "")
+	if err != nil {
+		return PrivateAndPublicKeys{}, errors.Wrap(err, "unable to marshal ED25519 private key")
+	}
+
+	publicKey, err := sshlib.NewPublicKey(ed25519PublicKey)
+	if err != nil {
+		return PrivateAndPublicKeys{}, errors.Wrap(err, "unable to generate ED25519 public key")
+	}
+
+	return PrivateAndPublicKeys{
+		PrivateKey: pem.EncodeToMemory(block),
+		PublicKey:  sshlib.MarshalAuthorizedKey(publicKey),
+	}, nil
 }

master/pkg/ssh/ssh_test.go

@@ -0,0 +1,39 @@
+package ssh
+
+import (
+	"testing"
+
+	"golang.org/x/crypto/ssh"
+	"gotest.tools/assert"
+
+	"github.com/determined-ai/determined/master/internal/config"
+)
+
+func verifyKeys(t *testing.T, keys PrivateAndPublicKeys) {
+	privateKey, err := ssh.ParsePrivateKey(keys.PrivateKey)
+	assert.NilError(t, err)
+
+	publickKey, _, _, _, err := ssh.ParseAuthorizedKey(keys.PublicKey) //nolint:dogsled
+	assert.NilError(t, err)
+	assert.Equal(t, string(publickKey.Marshal()), string(privateKey.PublicKey().Marshal()))
+}
+
+func TestSSHKeyGenerate(t *testing.T) {
+	t.Run("generate RSA key", func(t *testing.T) {
+		keys, err := GenerateKey(config.SSHConfig{KeyType: config.KeyTypeRSA, RsaKeySize: 512})
+		assert.NilError(t, err)
+		verifyKeys(t, keys)
+	})
+
+	t.Run("generate ECDSA key", func(t *testing.T) {
+		keys, err := GenerateKey(config.SSHConfig{KeyType: config.KeyTypeECDSA})
+		assert.NilError(t, err)
+		verifyKeys(t, keys)
+	})
+
+	t.Run("generate ED25519 key", func(t *testing.T) {
+		keys, err := GenerateKey(config.SSHConfig{KeyType: config.KeyTypeED25519})
+		assert.NilError(t, err)
+		verifyKeys(t, keys)
+	})
+}

master/pkg/tasks/task.go

@@ -12,6 +12,7 @@ import (
 	"github.com/docker/docker/api/types/mount"
 	"github.com/jinzhu/copier"
 
+	"github.com/determined-ai/determined/master/internal/config"
 	"github.com/determined-ai/determined/master/pkg/archive"
 	"github.com/determined-ai/determined/master/pkg/cproto"
 	"github.com/determined-ai/determined/master/pkg/device"
@@ -70,7 +71,7 @@ type TaskSpec struct {
 	ClusterID   string
 	HarnessPath string
 	MasterCert  []byte
-	SSHRsaSize  int
+	SSHConfig   config.SSHConfig
 
 	SegmentEnabled bool
 	SegmentAPIKey  string

proto/src/determined/api/v1/shell.proto

@@ -102,7 +102,7 @@ message LaunchShellRequest {
   string template_name = 2;
   // The files to run with the command.
   repeated determined.util.v1.File files = 3;
-  // Additional data.
+  // Deprecated: Do not use.
   bytes data = 4;
   // Workspace ID. Defaults to 'Uncategorized' workspace if not specified.
   int32 workspace_id = 5;