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x/crypto/ssh: support more keytypes in the agent.

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This allows the golang ssh-agent to support the full suite of keys
the library accepts.

Currently constraints are ignored.

Change-Id: I7d48c78e9a355582eb54788571a483a736c3d3ef
Reviewed-on: https://go-review.googlesource.com/21536
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Peter Moody
2016-04-25 17:01:51 +00:00
committed by Han-Wen Nienhuys
parent f98fd1f5ec
commit e84a34b1ee
6 changed files with 391 additions and 49 deletions
Download Patch File Download Diff File Expand all files Collapse all files
ssh/agent/client.go
+12 -9
View File
@@ -184,10 +184,13 @@ func (k *Key) Marshal() []byte {
return k.Blob
}
// Verify satisfies the ssh.PublicKey interface, but is not
// implemented for agent keys.
// Verify satisfies the ssh.PublicKey interface.
func (k *Key) Verify(data []byte, sig *ssh.Signature) error {
return errors.New("agent: agent key does not know how to verify")
pubKey, err := ssh.ParsePublicKey(k.Blob)
if err != nil {
return fmt.Errorf("agent: bad public key")
}
return pubKey.Verify(data, sig)
}
type wireKey struct {
@@ -389,7 +392,7 @@ func unmarshal(packet []byte) (interface{}, error) {
}
type rsaKeyMsg struct {
Type string `sshtype:"17"`
Type string `sshtype:"17|25"`
N *big.Int
E *big.Int
D *big.Int
@@ -401,7 +404,7 @@ type rsaKeyMsg struct {
}
type dsaKeyMsg struct {
Type string `sshtype:"17"`
Type string `sshtype:"17|25"`
P *big.Int
Q *big.Int
G *big.Int
@@ -412,7 +415,7 @@ type dsaKeyMsg struct {
}
type ecdsaKeyMsg struct {
Type string `sshtype:"17"`
Type string `sshtype:"17|25"`
Curve string
KeyBytes []byte
D *big.Int
@@ -481,7 +484,7 @@ func (c *client) insertKey(s interface{}, comment string, constraints []byte) er
}
type rsaCertMsg struct {
Type string `sshtype:"17"`
Type string `sshtype:"17|25"`
CertBytes []byte
D *big.Int
Iqmp *big.Int // IQMP = Inverse Q Mod P
@@ -492,7 +495,7 @@ type rsaCertMsg struct {
}
type dsaCertMsg struct {
Type string `sshtype:"17"`
Type string `sshtype:"17|25"`
CertBytes []byte
X *big.Int
Comments string
@@ -500,7 +503,7 @@ type dsaCertMsg struct {
}
type ecdsaCertMsg struct {
Type string `sshtype:"17"`
Type string `sshtype:"17|25"`
CertBytes []byte
D *big.Int
Comments string
ssh/agent/server.go
+223 -19
View File
@@ -5,8 +5,12 @@
package agent
import (
"crypto/dsa"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rsa"
"encoding/binary"
"errors"
"fmt"
"io"
"log"
@@ -128,6 +132,7 @@ func (s *server) processRequest(data []byte) (interface{}, error) {
return nil, err
}
return &signResponseAgentMsg{SigBlob: ssh.Marshal(sig)}, nil
case agentRequestIdentities:
keys, err := s.agent.List()
if err != nil {
@@ -141,42 +146,241 @@ func (s *server) processRequest(data []byte) (interface{}, error) {
rep.Keys = append(rep.Keys, marshalKey(k)...)
}
return rep, nil
case agentAddIdentity:
case agentAddIdConstrained, agentAddIdentity:
return nil, s.insertIdentity(data)
}
return nil, fmt.Errorf("unknown opcode %d", data[0])
}
func parseRSAKey(req []byte) (*AddedKey, error) {
var k rsaKeyMsg
if err := ssh.Unmarshal(req, &k); err != nil {
return nil, err
}
if k.E.BitLen() > 30 {
return nil, errors.New("agent: RSA public exponent too large")
}
priv := &rsa.PrivateKey{
PublicKey: rsa.PublicKey{
E: int(k.E.Int64()),
N: k.N,
},
D: k.D,
Primes: []*big.Int{k.P, k.Q},
}
priv.Precompute()
return &AddedKey{PrivateKey: priv, Comment: k.Comments}, nil
}
func parseDSAKey(req []byte) (*AddedKey, error) {
var k dsaKeyMsg
if err := ssh.Unmarshal(req, &k); err != nil {
return nil, err
}
priv := &dsa.PrivateKey{
PublicKey: dsa.PublicKey{
Parameters: dsa.Parameters{
P: k.P,
Q: k.Q,
G: k.G,
},
Y: k.Y,
},
X: k.X,
}
return &AddedKey{PrivateKey: priv, Comment: k.Comments}, nil
}
func unmarshalECDSA(curveName string, keyBytes []byte, privScalar *big.Int) (priv *ecdsa.PrivateKey, err error) {
priv = &ecdsa.PrivateKey{
D: privScalar,
}
switch curveName {
case "nistp256":
priv.Curve = elliptic.P256()
case "nistp384":
priv.Curve = elliptic.P384()
case "nistp521":
priv.Curve = elliptic.P521()
default:
return nil, fmt.Errorf("agent: unknown curve %q", curveName)
}
priv.X, priv.Y = elliptic.Unmarshal(priv.Curve, keyBytes)
if priv.X == nil || priv.Y == nil {
return nil, errors.New("agent: point not on curve")
}
return priv, nil
}
func parseECDSAKey(req []byte) (*AddedKey, error) {
var k ecdsaKeyMsg
if err := ssh.Unmarshal(req, &k); err != nil {
return nil, err
}
priv, err := unmarshalECDSA(k.Curve, k.KeyBytes, k.D)
if err != nil {
return nil, err
}
return &AddedKey{PrivateKey: &priv, Comment: k.Comments}, nil
}
func parseRSACert(req []byte) (*AddedKey, error) {
var k rsaCertMsg
if err := ssh.Unmarshal(req, &k); err != nil {
return nil, err
}
pubKey, err := ssh.ParsePublicKey(k.CertBytes)
if err != nil {
return nil, err
}
cert, ok := pubKey.(*ssh.Certificate)
if !ok {
return nil, errors.New("agent: bad RSA certificate")
}
// An RSA publickey as marshaled by rsaPublicKey.Marshal() in keys.go
var rsaPub struct {
Name string
E *big.Int
N *big.Int
}
if err := ssh.Unmarshal(cert.Key.Marshal(), &rsaPub); err != nil {
return nil, fmt.Errorf("agent: Unmarshal failed to parse public key: %v", err)
}
if rsaPub.E.BitLen() > 30 {
return nil, errors.New("agent: RSA public exponent too large")
}
priv := rsa.PrivateKey{
PublicKey: rsa.PublicKey{
E: int(rsaPub.E.Int64()),
N: rsaPub.N,
},
D: k.D,
Primes: []*big.Int{k.Q, k.P},
}
priv.Precompute()
return &AddedKey{PrivateKey: &priv, Certificate: cert, Comment: k.Comments}, nil
}
func parseDSACert(req []byte) (*AddedKey, error) {
var k dsaCertMsg
if err := ssh.Unmarshal(req, &k); err != nil {
return nil, err
}
pubKey, err := ssh.ParsePublicKey(k.CertBytes)
if err != nil {
return nil, err
}
cert, ok := pubKey.(*ssh.Certificate)
if !ok {
return nil, errors.New("agent: bad DSA certificate")
}
// A DSA publickey as marshaled by dsaPublicKey.Marshal() in keys.go
var w struct {
Name string
P, Q, G, Y *big.Int
}
if err := ssh.Unmarshal(cert.Key.Marshal(), &w); err != nil {
return nil, fmt.Errorf("agent: Unmarshal failed to parse public key: %v", err)
}
priv := &dsa.PrivateKey{
PublicKey: dsa.PublicKey{
Parameters: dsa.Parameters{
P: w.P,
Q: w.Q,
G: w.G,
},
Y: w.Y,
},
X: k.X,
}
return &AddedKey{PrivateKey: priv, Certificate: cert, Comment: k.Comments}, nil
}
func parseECDSACert(req []byte) (*AddedKey, error) {
var k ecdsaCertMsg
if err := ssh.Unmarshal(req, &k); err != nil {
return nil, err
}
pubKey, err := ssh.ParsePublicKey(k.CertBytes)
if err != nil {
return nil, err
}
cert, ok := pubKey.(*ssh.Certificate)
if !ok {
return nil, errors.New("agent: bad ECDSA certificate")
}
// An ECDSA publickey as marshaled by ecdsaPublicKey.Marshal() in keys.go
var ecdsaPub struct {
Name string
ID string
Key []byte
}
if err := ssh.Unmarshal(cert.Key.Marshal(), &ecdsaPub); err != nil {
return nil, err
}
priv, err := unmarshalECDSA(ecdsaPub.ID, ecdsaPub.Key, k.D)
if err != nil {
return nil, err
}
return &AddedKey{PrivateKey: priv, Certificate: cert, Comment: k.Comments}, nil
}
func (s *server) insertIdentity(req []byte) error {
var record struct {
Type string `sshtype:"17"`
Type string `sshtype:"17|25"`
Rest []byte `ssh:"rest"`
}
if err := ssh.Unmarshal(req, &record); err != nil {
return err
}
var addedKey *AddedKey
var err error
switch record.Type {
case ssh.KeyAlgoRSA:
var k rsaKeyMsg
if err := ssh.Unmarshal(req, &k); err != nil {
return err
}
priv := rsa.PrivateKey{
PublicKey: rsa.PublicKey{
E: int(k.E.Int64()),
N: k.N,
},
D: k.D,
Primes: []*big.Int{k.P, k.Q},
}
priv.Precompute()
return s.agent.Add(AddedKey{PrivateKey: &priv, Comment: k.Comments})
addedKey, err = parseRSAKey(req)
case ssh.KeyAlgoDSA:
addedKey, err = parseDSAKey(req)
case ssh.KeyAlgoECDSA256, ssh.KeyAlgoECDSA384, ssh.KeyAlgoECDSA521:
addedKey, err = parseECDSACert(req)
case ssh.CertAlgoRSAv01:
addedKey, err = parseRSACert(req)
case ssh.CertAlgoDSAv01:
addedKey, err = parseDSACert(req)
case ssh.CertAlgoECDSA256v01, ssh.CertAlgoECDSA384v01, ssh.CertAlgoECDSA521v01:
addedKey, err = parseECDSACert(req)
default:
return fmt.Errorf("agent: not implemented: %q", record.Type)
}
return fmt.Errorf("not implemented: %s", record.Type)
if err != nil {
return err
}
return s.agent.Add(*addedKey)
}
// ServeAgent serves the agent protocol on the given connection. It
ssh/agent/server_test.go
+77
View File
@@ -5,6 +5,9 @@
package agent
import (
"crypto"
"crypto/rand"
"fmt"
"testing"
"golang.org/x/crypto/ssh"
@@ -107,3 +110,77 @@ func testV1ProtocolMessages(t *testing.T, c *client) {
t.Fatalf("invalid remove all response: %#v", reply)
}
}
func verifyKey(sshAgent Agent) error {
keys, err := sshAgent.List()
if err != nil {
return fmt.Errorf("listing keys: %v", err)
}
if len(keys) != 1 {
return fmt.Errorf("bad number of keys found. expected 1, got %d", len(keys))
}
buf := make([]byte, 128)
if _, err := rand.Read(buf); err != nil {
return fmt.Errorf("rand: %v", err)
}
sig, err := sshAgent.Sign(keys[0], buf)
if err != nil {
return fmt.Errorf("sign: %v", err)
}
if err := keys[0].Verify(buf, sig); err != nil {
return fmt.Errorf("verify: %v", err)
}
return nil
}
func addKeyToAgent(key crypto.PrivateKey) error {
sshAgent := NewKeyring()
if err := sshAgent.Add(AddedKey{PrivateKey: key}); err != nil {
return fmt.Errorf("add: %v", err)
}
return verifyKey(sshAgent)
}
func TestKeyTypes(t *testing.T) {
for k, v := range testPrivateKeys {
if err := addKeyToAgent(v); err != nil {
t.Errorf("error adding key type %s, %v", k, err)
}
}
}
func addCertToAgent(key crypto.PrivateKey, cert *ssh.Certificate) error {
sshAgent := NewKeyring()
if err := sshAgent.Add(AddedKey{PrivateKey: key, Certificate: cert}); err != nil {
return fmt.Errorf("add: %v", err)
}
return verifyKey(sshAgent)
}
func TestCertTypes(t *testing.T) {
for keyType, key := range testPublicKeys {
cert := &ssh.Certificate{
ValidPrincipals: []string{"gopher1"},
ValidAfter: 0,
ValidBefore: ssh.CertTimeInfinity,
Key: key,
Serial: 1,
CertType: ssh.UserCert,
SignatureKey: testPublicKeys["rsa"],
Permissions: ssh.Permissions{
CriticalOptions: map[string]string{},
Extensions: map[string]string{},
},
}
if err := cert.SignCert(rand.Reader, testSigners["rsa"]); err != nil {
t.Fatalf("signcert: %v", err)
}
if err := addCertToAgent(testPrivateKeys[keyType], cert); err != nil {
t.Fatalf("%v", err)
}
}
}
ssh/keys.go
+6
View File
@@ -319,6 +319,8 @@ func parseRSA(in []byte) (out PublicKey, rest []byte, err error) {
func (r *rsaPublicKey) Marshal() []byte {
e := new(big.Int).SetInt64(int64(r.E))
// RSA publickey struct layout should match the struct used by
// parseRSACert in the x/crypto/ssh/agent package.
wirekey := struct {
Name string
E *big.Int
@@ -369,6 +371,8 @@ func parseDSA(in []byte) (out PublicKey, rest []byte, err error) {
}
func (k *dsaPublicKey) Marshal() []byte {
// DSA publickey struct layout should match the struct used by
// parseDSACert in the x/crypto/ssh/agent package.
w := struct {
Name string
P, Q, G, Y *big.Int
@@ -507,6 +511,8 @@ func parseECDSA(in []byte) (out PublicKey, rest []byte, err error) {
func (key *ecdsaPublicKey) Marshal() []byte {
// See RFC 5656, section 3.1.
keyBytes := elliptic.Marshal(key.Curve, key.X, key.Y)
// ECDSA publickey struct layout should match the struct used by
// parseECDSACert in the x/crypto/ssh/agent package.
w := struct {
Name string
ID string
ssh/messages.go
+39 -21
View File
@@ -13,6 +13,7 @@ import (
"math/big"
"reflect"
"strconv"
"strings"
)
// These are SSH message type numbers. They are scattered around several
@@ -266,17 +267,19 @@ type userAuthPubKeyOkMsg struct {
PubKey []byte
}
// typeTag returns the type byte for the given type. The type should
// be struct.
func typeTag(structType reflect.Type) byte {
var tag byte
var tagStr string
tagStr = structType.Field(0).Tag.Get("sshtype")
i, err := strconv.Atoi(tagStr)
if err == nil {
tag = byte(i)
// typeTags returns the possible type bytes for the given reflect.Type, which
// should be a struct. The possible values are separated by a '|' character.
func typeTags(structType reflect.Type) (tags []byte) {
tagStr := structType.Field(0).Tag.Get("sshtype")
for _, tag := range strings.Split(tagStr, "|") {
i, err := strconv.Atoi(tag)
if err == nil {
tags = append(tags, byte(i))
}
}
return tag
return tags
}
func fieldError(t reflect.Type, field int, problem string) error {
@@ -290,19 +293,34 @@ var errShortRead = errors.New("ssh: short read")
// Unmarshal parses data in SSH wire format into a structure. The out
// argument should be a pointer to struct. If the first member of the
// struct has the "sshtype" tag set to a number in decimal, the packet
// must start that number. In case of error, Unmarshal returns a
// ParseError or UnexpectedMessageError.
// struct has the "sshtype" tag set to a '|'-separated set of numbers
// in decimal, the packet must start with one of those numbers. In
// case of error, Unmarshal returns a ParseError or
// UnexpectedMessageError.
func Unmarshal(data []byte, out interface{}) error {
v := reflect.ValueOf(out).Elem()
structType := v.Type()
expectedType := typeTag(structType)
expectedTypes := typeTags(structType)
var expectedType byte
if len(expectedTypes) > 0 {
expectedType = expectedTypes[0]
}
if len(data) == 0 {
return parseError(expectedType)
}
if expectedType > 0 {
if data[0] != expectedType {
return unexpectedMessageError(expectedType, data[0])
if len(expectedTypes) > 0 {
goodType := false
for _, e := range expectedTypes {
if e > 0 && data[0] == e {
goodType = true
break
}
}
if !goodType {
return fmt.Errorf("ssh: unexpected message type %d (expected one of %v)", data[0], expectedTypes)
}
data = data[1:]
}
@@ -386,7 +404,7 @@ func Unmarshal(data []byte, out interface{}) error {
return fieldError(structType, i, "pointer to unsupported type")
}
default:
return fieldError(structType, i, "unsupported type")
return fieldError(structType, i, fmt.Sprintf("unsupported type: %v", t))
}
}
@@ -409,9 +427,9 @@ func Marshal(msg interface{}) []byte {
func marshalStruct(out []byte, msg interface{}) []byte {
v := reflect.Indirect(reflect.ValueOf(msg))
msgType := typeTag(v.Type())
if msgType > 0 {
out = append(out, msgType)
msgTypes := typeTags(v.Type())
if len(msgTypes) > 0 {
out = append(out, msgTypes[0])
}
for i, n := 0, v.NumField(); i < n; i++ {
ssh/messages_test.go
+34
View File
@@ -172,6 +172,40 @@ func TestUnmarshalShortKexInitPacket(t *testing.T) {
}
}
func TestMarshalMultiTag(t *testing.T) {
var res struct {
A uint32 `sshtype:"1|2"`
}
good1 := struct {
A uint32 `sshtype:"1"`
}{
1,
}
good2 := struct {
A uint32 `sshtype:"2"`
}{
1,
}
if e := Unmarshal(Marshal(good1), &res); e != nil {
t.Errorf("error unmarshaling multipart tag: %v", e)
}
if e := Unmarshal(Marshal(good2), &res); e != nil {
t.Errorf("error unmarshaling multipart tag: %v", e)
}
bad1 := struct {
A uint32 `sshtype:"3"`
}{
1,
}
if e := Unmarshal(Marshal(bad1), &res); e == nil {
t.Errorf("bad struct unmarshaled without error")
}
}
func randomBytes(out []byte, rand *rand.Rand) {
for i := 0; i < len(out); i++ {
out[i] = byte(rand.Int31())