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ssh: reject unencrypted keys from ParsePrivateKeyWithPassphrase

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The behavior of ParsePrivateKeyWithPassphrase when the key is
unencrypted is unspecified. Currently, it just parses them like
ParsePrivateKey, which is unlikely to be what anyone wants: for us to
ignore a passphrase that they explicitly passed. It also makes the
implementation of encrypted OpenSSH keys in the next CL more confused.

Instead, make ParsePrivateKey return a PassphraseNeededError, so the
application logic can be ParsePrivateKey -> detect encrypted key ->
obtain passphrase -> ParsePrivateKeyWithPassphrase. That error will also
let us return the public key for OpenSSH keys.

Change-Id: Ife4fb2499ae538bef36e353adf9bc8e902662386
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/207599
Run-TryBot: Filippo Valsorda <filippo@golang.org>
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>
This commit is contained in:
Filippo Valsorda
2019-12-05 16:18:47 +00:00
committed by Filippo Valsorda
parent 86a70503ff
commit 0a08dada0f
3 changed files with 68 additions and 56 deletions
Download Patch File Download Diff File Expand all files Collapse all files
ssh/keys.go
+29 -19
View File
@@ -1055,7 +1055,8 @@ func NewPublicKey(key interface{}) (PublicKey, error) {
}
// ParsePrivateKey returns a Signer from a PEM encoded private key. It supports
// the same keys as ParseRawPrivateKey.
// the same keys as ParseRawPrivateKey. If the private key is encrypted, it
// will return a PassphraseMissingError.
func ParsePrivateKey(pemBytes []byte) (Signer, error) {
key, err := ParseRawPrivateKey(pemBytes)
if err != nil {
@@ -1068,8 +1069,8 @@ func ParsePrivateKey(pemBytes []byte) (Signer, error) {
// ParsePrivateKeyWithPassphrase returns a Signer from a PEM encoded private
// key and passphrase. It supports the same keys as
// ParseRawPrivateKeyWithPassphrase.
func ParsePrivateKeyWithPassphrase(pemBytes, passPhrase []byte) (Signer, error) {
key, err := ParseRawPrivateKeyWithPassphrase(pemBytes, passPhrase)
func ParsePrivateKeyWithPassphrase(pemBytes, passphrase []byte) (Signer, error) {
key, err := ParseRawPrivateKeyWithPassphrase(pemBytes, passphrase)
if err != nil {
return nil, err
}
@@ -1085,8 +1086,21 @@ func encryptedBlock(block *pem.Block) bool {
return strings.Contains(block.Headers["Proc-Type"], "ENCRYPTED")
}
// A PassphraseMissingError indicates that parsing this private key requires a
// passphrase. Use ParsePrivateKeyWithPassphrase.
type PassphraseMissingError struct {
// PublicKey will be set if the private key format includes an unencrypted
// public key along with the encrypted private key.
PublicKey PublicKey
}
func (*PassphraseMissingError) Error() string {
return "ssh: this private key is passphrase protected"
}
// ParseRawPrivateKey returns a private key from a PEM encoded private key. It
// supports RSA (PKCS#1), PKCS#8, DSA (OpenSSL), and ECDSA private keys.
// supports RSA (PKCS#1), PKCS#8, DSA (OpenSSL), and ECDSA private keys. If the
// private key is encrypted, it will return a PassphraseMissingError.
func ParseRawPrivateKey(pemBytes []byte) (interface{}, error) {
block, _ := pem.Decode(pemBytes)
if block == nil {
@@ -1094,7 +1108,7 @@ func ParseRawPrivateKey(pemBytes []byte) (interface{}, error) {
}
if encryptedBlock(block) {
return nil, errors.New("ssh: cannot decode encrypted private keys")
return nil, &PassphraseMissingError{}
}
switch block.Type {
@@ -1117,24 +1131,22 @@ func ParseRawPrivateKey(pemBytes []byte) (interface{}, error) {
// ParseRawPrivateKeyWithPassphrase returns a private key decrypted with
// passphrase from a PEM encoded private key. If wrong passphrase, return
// x509.IncorrectPasswordError.
func ParseRawPrivateKeyWithPassphrase(pemBytes, passPhrase []byte) (interface{}, error) {
func ParseRawPrivateKeyWithPassphrase(pemBytes, passphrase []byte) (interface{}, error) {
block, _ := pem.Decode(pemBytes)
if block == nil {
return nil, errors.New("ssh: no key found")
}
buf := block.Bytes
if encryptedBlock(block) {
if x509.IsEncryptedPEMBlock(block) {
var err error
buf, err = x509.DecryptPEMBlock(block, passPhrase)
if err != nil {
if err == x509.IncorrectPasswordError {
return nil, err
}
return nil, fmt.Errorf("ssh: cannot decode encrypted private keys: %v", err)
}
if !encryptedBlock(block) || !x509.IsEncryptedPEMBlock(block) {
return nil, errors.New("ssh: not an encrypted key")
}
buf, err := x509.DecryptPEMBlock(block, passphrase)
if err != nil {
if err == x509.IncorrectPasswordError {
return nil, err
}
return nil, fmt.Errorf("ssh: cannot decode encrypted private keys: %v", err)
}
switch block.Type {
@@ -1144,8 +1156,6 @@ func ParseRawPrivateKeyWithPassphrase(pemBytes, passPhrase []byte) (interface{},
return x509.ParseECPrivateKey(buf)
case "DSA PRIVATE KEY":
return ParseDSAPrivateKey(buf)
case "OPENSSH PRIVATE KEY":
return parseOpenSSHPrivateKey(buf)
default:
return nil, fmt.Errorf("ssh: unsupported key type %q", block.Type)
}
ssh/keys_test.go
+35 -34
View File
@@ -179,44 +179,45 @@ func TestParseECPrivateKey(t *testing.T) {
}
}
// See Issue https://github.com/golang/go/issues/6650.
func TestParseEncryptedPrivateKeysFails(t *testing.T) {
const wantSubstring = "encrypted"
for i, tt := range testdata.PEMEncryptedKeys {
_, err := ParsePrivateKey(tt.PEMBytes)
if err == nil {
t.Errorf("#%d key %s: ParsePrivateKey successfully parsed, expected an error", i, tt.Name)
continue
}
if !strings.Contains(err.Error(), wantSubstring) {
t.Errorf("#%d key %s: got error %q, want substring %q", i, tt.Name, err, wantSubstring)
}
}
}
// Parse encrypted private keys with passphrase
func TestParseEncryptedPrivateKeysWithPassphrase(t *testing.T) {
data := []byte("sign me")
for _, tt := range testdata.PEMEncryptedKeys {
s, err := ParsePrivateKeyWithPassphrase(tt.PEMBytes, []byte(tt.EncryptionKey))
if err != nil {
t.Fatalf("ParsePrivateKeyWithPassphrase returned error: %s", err)
continue
}
sig, err := s.Sign(rand.Reader, data)
if err != nil {
t.Fatalf("dsa.Sign: %v", err)
}
if err := s.PublicKey().Verify(data, sig); err != nil {
t.Errorf("Verify failed: %v", err)
}
}
t.Run(tt.Name, func(t *testing.T) {
_, err := ParsePrivateKeyWithPassphrase(tt.PEMBytes, []byte("incorrect"))
if err != x509.IncorrectPasswordError {
t.Errorf("got %v want IncorrectPasswordError", err)
}
tt := testdata.PEMEncryptedKeys[0]
_, err := ParsePrivateKeyWithPassphrase(tt.PEMBytes, []byte("incorrect"))
if err != x509.IncorrectPasswordError {
t.Fatalf("got %v want IncorrectPasswordError", err)
s, err := ParsePrivateKeyWithPassphrase(tt.PEMBytes, []byte(tt.EncryptionKey))
if err != nil {
t.Fatalf("ParsePrivateKeyWithPassphrase returned error: %s", err)
}
sig, err := s.Sign(rand.Reader, data)
if err != nil {
t.Fatalf("Signer.Sign: %v", err)
}
if err := s.PublicKey().Verify(data, sig); err != nil {
t.Errorf("Verify failed: %v", err)
}
_, err = ParsePrivateKey(tt.PEMBytes)
if err == nil {
t.Fatalf("ParsePrivateKey succeeded, expected an error")
}
if err, ok := err.(*PassphraseMissingError); !ok {
t.Errorf("got error %q, want PassphraseMissingError", err)
} else if tt.IncludesPublicKey {
if err.PublicKey == nil {
t.Fatalf("expected PassphraseMissingError.PublicKey not to be nil")
}
got, want := err.PublicKey.Marshal(), s.PublicKey().Marshal()
if !bytes.Equal(got, want) {
t.Errorf("error field %q doesn't match signer public key %q", got, want)
}
}
})
}
}
ssh/testdata/keys.go
Vendored
+4 -3
View File
@@ -164,9 +164,10 @@ var SSHCertificates = map[string][]byte{
}
var PEMEncryptedKeys = []struct {
Name string
EncryptionKey string
PEMBytes []byte
Name string
EncryptionKey string
IncludesPublicKey bool
PEMBytes []byte
}{
0: {
Name: "rsa-encrypted",