2d85d4c1c1
A server without TLS was added to serve the SCEP endpoints. According to the RFC, SCEP has to be served via HTTP. The `sscep` client, for example, will stop any URL that does not start with `http://` from being used, so serving SCEP seems to be the right way to do it. This commit adds a second server for which no TLS configuration is configured. A distinct field in the configuration, `insecureAddress` was added to specify the address for the insecure server. The SCEP endpoints will also still be served via HTTPS. Some clients may be able to work with that. This commit also improves how the crypto.Decrypter interface is handled for the different types of KMSes supported by step. The apiv1.Decrypter interface was added. Currently only SoftKMS implements this interface, providing a crypto.Decrypter required for SCEP operations.
206 lines
5.2 KiB
Go
206 lines
5.2 KiB
Go
package sshagentkms
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import (
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"context"
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"crypto"
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"crypto/ecdsa"
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"crypto/ed25519"
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"crypto/rsa"
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"crypto/x509"
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"io"
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"net"
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"os"
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"strings"
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"golang.org/x/crypto/ssh"
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"golang.org/x/crypto/ssh/agent"
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"github.com/pkg/errors"
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"github.com/smallstep/certificates/kms/apiv1"
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"go.step.sm/crypto/pemutil"
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)
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// SSHAgentKMS is a key manager that uses keys provided by ssh-agent
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type SSHAgentKMS struct {
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agentClient agent.Agent
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}
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// New returns a new SSHAgentKMS.
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func New(ctx context.Context, opts apiv1.Options) (*SSHAgentKMS, error) {
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socket := os.Getenv("SSH_AUTH_SOCK")
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conn, err := net.Dial("unix", socket)
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if err != nil {
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return nil, errors.Wrap(err, "failed to open SSH_AUTH_SOCK")
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}
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agentClient := agent.NewClient(conn)
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return &SSHAgentKMS{
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agentClient: agentClient,
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}, nil
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}
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// NewFromAgent initializes an SSHAgentKMS from a given agent, this method is
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// used for testing purposes.
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func NewFromAgent(ctx context.Context, opts apiv1.Options, agentClient agent.Agent) (*SSHAgentKMS, error) {
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return &SSHAgentKMS{
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agentClient: agentClient,
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}, nil
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}
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func init() {
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apiv1.Register(apiv1.SSHAgentKMS, func(ctx context.Context, opts apiv1.Options) (apiv1.KeyManager, error) {
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return New(ctx, opts)
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})
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}
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// Close closes the agent. This is a noop for the SSHAgentKMS.
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func (k *SSHAgentKMS) Close() error {
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return nil
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}
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// WrappedSSHSigner is a utility type to wrap a ssh.Signer as a crypto.Signer
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type WrappedSSHSigner struct {
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Sshsigner ssh.Signer
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}
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// Public returns the agent public key. The type of this public key is
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// *agent.Key.
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func (s *WrappedSSHSigner) Public() crypto.PublicKey {
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return s.Sshsigner.PublicKey()
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}
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// Sign signs the given digest using the ssh agent and returns the signature.
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func (s *WrappedSSHSigner) Sign(rand io.Reader, digest []byte, opts crypto.SignerOpts) (signature []byte, err error) {
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sig, err := s.Sshsigner.Sign(rand, digest)
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if err != nil {
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return nil, err
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}
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return sig.Blob, nil
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}
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// NewWrappedSignerFromSSHSigner returns a new crypto signer wrapping the given
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// one.
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func NewWrappedSignerFromSSHSigner(signer ssh.Signer) crypto.Signer {
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return &WrappedSSHSigner{signer}
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}
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func (k *SSHAgentKMS) findKey(signingKey string) (target int, err error) {
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if strings.HasPrefix(signingKey, "sshagentkms:") {
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var key = strings.TrimPrefix(signingKey, "sshagentkms:")
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l, err := k.agentClient.List()
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if err != nil {
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return -1, err
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}
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for i, s := range l {
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if s.Comment == key {
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return i, nil
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}
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}
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}
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return -1, errors.Errorf("SSHAgentKMS couldn't find %s", signingKey)
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}
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// CreateSigner returns a new signer configured with the given signing key.
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func (k *SSHAgentKMS) CreateSigner(req *apiv1.CreateSignerRequest) (crypto.Signer, error) {
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if req.Signer != nil {
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return req.Signer, nil
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}
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if strings.HasPrefix(req.SigningKey, "sshagentkms:") {
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target, err := k.findKey(req.SigningKey)
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if err != nil {
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return nil, err
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}
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s, err := k.agentClient.Signers()
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if err != nil {
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return nil, err
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}
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return NewWrappedSignerFromSSHSigner(s[target]), nil
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}
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// OK: We don't actually care about non-ssh certificates,
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// but we can't disable it in step-ca so this code is copy-pasted from
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// softkms just to keep step-ca happy.
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var opts []pemutil.Options
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if req.Password != nil {
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opts = append(opts, pemutil.WithPassword(req.Password))
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}
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switch {
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case len(req.SigningKeyPEM) != 0:
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v, err := pemutil.ParseKey(req.SigningKeyPEM, opts...)
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if err != nil {
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return nil, err
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}
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sig, ok := v.(crypto.Signer)
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if !ok {
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return nil, errors.New("signingKeyPEM is not a crypto.Signer")
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}
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return sig, nil
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case req.SigningKey != "":
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v, err := pemutil.Read(req.SigningKey, opts...)
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if err != nil {
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return nil, err
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}
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sig, ok := v.(crypto.Signer)
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if !ok {
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return nil, errors.New("signingKey is not a crypto.Signer")
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}
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return sig, nil
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default:
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return nil, errors.New("failed to load softKMS: please define signingKeyPEM or signingKey")
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}
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}
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// CreateKey generates a new key and returns both public and private key.
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func (k *SSHAgentKMS) CreateKey(req *apiv1.CreateKeyRequest) (*apiv1.CreateKeyResponse, error) {
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return nil, errors.Errorf("SSHAgentKMS doesn't support generating keys")
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}
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// GetPublicKey returns the public key from the file passed in the request name.
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func (k *SSHAgentKMS) GetPublicKey(req *apiv1.GetPublicKeyRequest) (crypto.PublicKey, error) {
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var v crypto.PublicKey
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if strings.HasPrefix(req.Name, "sshagentkms:") {
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target, err := k.findKey(req.Name)
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if err != nil {
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return nil, err
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}
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s, err := k.agentClient.Signers()
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if err != nil {
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return nil, err
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}
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sshPub := s[target].PublicKey()
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sshPubBytes := sshPub.Marshal()
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parsed, err := ssh.ParsePublicKey(sshPubBytes)
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if err != nil {
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return nil, err
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}
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parsedCryptoKey := parsed.(ssh.CryptoPublicKey)
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// Then, we can call CryptoPublicKey() to get the actual crypto.PublicKey
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v = parsedCryptoKey.CryptoPublicKey()
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} else {
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var err error
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v, err = pemutil.Read(req.Name)
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if err != nil {
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return nil, err
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}
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}
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switch vv := v.(type) {
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case *x509.Certificate:
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return vv.PublicKey, nil
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case *rsa.PublicKey, *ecdsa.PublicKey, ed25519.PublicKey:
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return vv, nil
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default:
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return nil, errors.Errorf("unsupported public key type %T", v)
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}
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}
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