Add support for multiple ssh roots.

Fixes #125

api/api.go

@@ -253,6 +253,7 @@ func (h *caHandler) Route(r Router) {
 	// SSH CA
 	r.MethodFunc("POST", "/ssh/sign", h.SignSSH)
 	r.MethodFunc("GET", "/ssh/keys", h.SSHKeys)
+	r.MethodFunc("GET", "/ssh/federation", h.SSHFederatedKeys)
 	r.MethodFunc("POST", "/ssh/config", h.SSHConfig)
 	r.MethodFunc("POST", "/ssh/config/{type}", h.SSHConfig)
 

api/ssh.go

@@ -18,6 +18,7 @@ type SSHAuthority interface {
 	SignSSH(key ssh.PublicKey, opts provisioner.SSHOptions, signOpts ...provisioner.SignOption) (*ssh.Certificate, error)
 	SignSSHAddUser(key ssh.PublicKey, cert *ssh.Certificate) (*ssh.Certificate, error)
 	GetSSHKeys() (*authority.SSHKeys, error)
+	GetSSHFederatedKeys() (*authority.SSHKeys, error)
 	GetSSHConfig(typ string, data map[string]string) ([]templates.Output, error)
 }
 
@@ -55,8 +56,8 @@ type SignSSHResponse struct {
 // SSHKeysResponse represents the response object that returns the SSH user and
 // host keys.
 type SSHKeysResponse struct {
-	UserKey *SSHPublicKey `json:"userKey,omitempty"`
-	HostKey *SSHPublicKey `json:"hostKey,omitempty"`
+	UserKeys []SSHPublicKey `json:"userKey,omitempty"`
+	HostKeys []SSHPublicKey `json:"hostKey,omitempty"`
 }
 
 // SSHCertificate represents the response SSH certificate.
@@ -241,23 +242,50 @@ func (h *caHandler) SignSSH(w http.ResponseWriter, r *http.Request) {
 // certificates.
 func (h *caHandler) SSHKeys(w http.ResponseWriter, r *http.Request) {
 	keys, err := h.Authority.GetSSHKeys()
+	if err != nil {
+		WriteError(w, InternalServerError(err))
+		return
+	}
+
+	if len(keys.HostKeys) == 0 && len(keys.UserKeys) == 0 {
+		WriteError(w, NotFound(errors.New("no keys found")))
+		return
+	}
+
+	resp := new(SSHKeysResponse)
+	for _, k := range keys.HostKeys {
+		resp.HostKeys = append(resp.HostKeys, SSHPublicKey{PublicKey: k})
+	}
+	for _, k := range keys.UserKeys {
+		resp.UserKeys = append(resp.UserKeys, SSHPublicKey{PublicKey: k})
+	}
+
+	JSON(w, resp)
+}
+
+// SSHFederatedKeys is an HTTP handler that returns the federated SSH public
+// keys for user and host certificates.
+func (h *caHandler) SSHFederatedKeys(w http.ResponseWriter, r *http.Request) {
+	keys, err := h.Authority.GetSSHFederatedKeys()
 	if err != nil {
 		WriteError(w, NotFound(err))
 		return
 	}
 
-	var host, user *SSHPublicKey
-	if keys.HostKey != nil {
-		host = &SSHPublicKey{PublicKey: keys.HostKey}
-	}
-	if keys.UserKey != nil {
-		user = &SSHPublicKey{PublicKey: keys.UserKey}
+	if len(keys.HostKeys) == 0 && len(keys.UserKeys) == 0 {
+		WriteError(w, NotFound(errors.New("no keys found")))
+		return
 	}
 
-	JSON(w, &SSHKeysResponse{
-		HostKey: host,
-		UserKey: user,
-	})
+	resp := new(SSHKeysResponse)
+	for _, k := range keys.HostKeys {
+		resp.HostKeys = append(resp.HostKeys, SSHPublicKey{PublicKey: k})
+	}
+	for _, k := range keys.UserKeys {
+		resp.UserKeys = append(resp.UserKeys, SSHPublicKey{PublicKey: k})
+	}
+
+	JSON(w, resp)
 }
 
 // SSHConfig is an HTTP handler that returns rendered templates for ssh clients

authority/authority.go

@@ -24,15 +24,19 @@ const (
 
 // Authority implements the Certificate Authority internal interface.
 type Authority struct {
-	config               *Config
-	rootX509Certs        []*x509.Certificate
-	intermediateIdentity *x509util.Identity
-	sshCAUserCertSignKey ssh.Signer
-	sshCAHostCertSignKey ssh.Signer
-	certificates         *sync.Map
-	startTime            time.Time
-	provisioners         *provisioner.Collection
-	db                   db.AuthDB
+	config                  *Config
+	rootX509Certs           []*x509.Certificate
+	intermediateIdentity    *x509util.Identity
+	sshCAUserCertSignKey    ssh.Signer
+	sshCAHostCertSignKey    ssh.Signer
+	sshCAUserCerts          []ssh.PublicKey
+	sshCAHostCerts          []ssh.PublicKey
+	sshCAUserFederatedCerts []ssh.PublicKey
+	sshCAHostFederatedCerts []ssh.PublicKey
+	certificates            *sync.Map
+	startTime               time.Time
+	provisioners            *provisioner.Collection
+	db                      db.AuthDB
 	// Do not re-initialize
 	initOnce bool
 }
@@ -136,6 +140,9 @@ func (a *Authority) init() error {
 			if err != nil {
 				return errors.Wrap(err, "error creating ssh signer")
 			}
+			// Append public key to list of host certs
+			a.sshCAHostCerts = append(a.sshCAHostCerts, a.sshCAHostCertSignKey.PublicKey())
+			a.sshCAHostFederatedCerts = append(a.sshCAHostFederatedCerts, a.sshCAHostCertSignKey.PublicKey())
 		}
 		if a.config.SSH.UserKey != "" {
 			signer, err := parseCryptoSigner(a.config.SSH.UserKey, a.config.Password)
@@ -146,6 +153,29 @@ func (a *Authority) init() error {
 			if err != nil {
 				return errors.Wrap(err, "error creating ssh signer")
 			}
+			// Append public key to list of user certs
+			a.sshCAUserCerts = append(a.sshCAUserCerts, a.sshCAHostCertSignKey.PublicKey())
+			a.sshCAUserFederatedCerts = append(a.sshCAUserFederatedCerts, a.sshCAUserCertSignKey.PublicKey())
+		}
+
+		// Append other public keys
+		for _, key := range a.config.SSH.Keys {
+			switch key.Type {
+			case provisioner.SSHHostCert:
+				if key.Federated {
+					a.sshCAHostFederatedCerts = append(a.sshCAHostFederatedCerts, key.PublicKey())
+				} else {
+					a.sshCAHostCerts = append(a.sshCAHostCerts, key.PublicKey())
+				}
+			case provisioner.SSHUserCert:
+				if key.Federated {
+					a.sshCAUserFederatedCerts = append(a.sshCAUserFederatedCerts, key.PublicKey())
+				} else {
+					a.sshCAUserCerts = append(a.sshCAUserCerts, key.PublicKey())
+				}
+			default:
+				return errors.Errorf("unsupported type %s", key.Type)
+			}
 		}
 	}
 

authority/config.go

@@ -104,14 +104,6 @@ func (c *AuthConfig) Validate(audiences provisioner.Audiences) error {
 	return nil
 }
 
-// SSHConfig contains the user and host keys.
-type SSHConfig struct {
-	HostKey          string `json:"hostKey"`
-	UserKey          string `json:"userKey"`
-	AddUserPrincipal string `json:"addUserPrincipal"`
-	AddUserCommand   string `json:"addUserCommand"`
-}
-
 // LoadConfiguration parses the given filename in JSON format and returns the
 // configuration struct.
 func LoadConfiguration(filename string) (*Config, error) {
@@ -184,6 +176,11 @@ func (c *Config) Validate() error {
 		c.TLS.Renegotiation = c.TLS.Renegotiation || DefaultTLSOptions.Renegotiation
 	}
 
+	// Validate ssh: nil is ok
+	if err := c.SSH.Validate(); err != nil {
+		return err
+	}
+
 	// Validate templates: nil is ok
 	if err := c.Templates.Validate(); err != nil {
 		return err

authority/ssh.go

@@ -10,6 +10,7 @@ import (
 	"github.com/smallstep/certificates/authority/provisioner"
 	"github.com/smallstep/certificates/templates"
 	"github.com/smallstep/cli/crypto/randutil"
+	"github.com/smallstep/cli/jose"
 	"golang.org/x/crypto/ssh"
 )
 
@@ -25,28 +26,81 @@ const (
 	SSHAddUserCommand = "sudo useradd -m <principal>; nc -q0 localhost 22"
 )
 
+// SSHConfig contains the user and host keys.
+type SSHConfig struct {
+	HostKey          string          `json:"hostKey"`
+	UserKey          string          `json:"userKey"`
+	Keys             []*SSHPublicKey `json:"keys,omitempty"`
+	AddUserPrincipal string          `json:"addUserPrincipal"`
+	AddUserCommand   string          `json:"addUserCommand"`
+}
+
+// Validate checks the fields in SSHConfig.
+func (c *SSHConfig) Validate() error {
+	if c == nil {
+		return nil
+	}
+	for _, k := range c.Keys {
+		if err := k.Validate(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// SSHPublicKey contains a public key used by federated CAs to keep old signing
+// keys for this ca.
+type SSHPublicKey struct {
+	Type      string          `json:"type"`
+	Federated bool            `json:"federated"`
+	Key       jose.JSONWebKey `json:"key"`
+	publicKey ssh.PublicKey
+}
+
+// Validate checks the fields in SSHPublicKey.
+func (k *SSHPublicKey) Validate() error {
+	switch {
+	case k.Type == "":
+		return errors.New("type cannot be empty")
+	case k.Type != provisioner.SSHHostCert && k.Type != provisioner.SSHUserCert:
+		return errors.Errorf("invalid type %s, it must be user or host", k.Type)
+	case !k.Key.IsPublic():
+		return errors.New("invalid key type, it must be a public key")
+	}
+
+	key, err := ssh.NewPublicKey(k.Key.Key)
+	if err != nil {
+		return errors.Wrap(err, "error creating ssh key")
+	}
+	k.publicKey = key
+	return nil
+}
+
+// PublicKey returns the ssh public key.
+func (k *SSHPublicKey) PublicKey() ssh.PublicKey {
+	return k.publicKey
+}
+
 // SSHKeys represents the SSH User and Host public keys.
 type SSHKeys struct {
-	UserKey ssh.PublicKey
-	HostKey ssh.PublicKey
+	UserKeys []ssh.PublicKey
+	HostKeys []ssh.PublicKey
 }
 
 // GetSSHKeys returns the SSH User and Host public keys.
 func (a *Authority) GetSSHKeys() (*SSHKeys, error) {
-	var keys SSHKeys
-	if a.sshCAUserCertSignKey != nil {
-		keys.UserKey = a.sshCAUserCertSignKey.PublicKey()
-	}
-	if a.sshCAHostCertSignKey != nil {
-		keys.HostKey = a.sshCAHostCertSignKey.PublicKey()
-	}
-	if keys.UserKey == nil && keys.HostKey == nil {
-		return nil, &apiError{
-			err:  errors.New("getSSHKeys: ssh is not configured"),
-			code: http.StatusNotFound,
-		}
-	}
-	return &keys, nil
+	return &SSHKeys{
+		HostKeys: a.sshCAHostCerts,
+		UserKeys: a.sshCAUserCerts,
+	}, nil
+}
+
+// GetSSHFederatedKeys returns the public keys for federated SSH signers.
+func (a *Authority) GetSSHFederatedKeys() (*SSHKeys, error) {
+	return &SSHKeys{
+		HostKeys: a.sshCAHostFederatedCerts,
+		UserKeys: a.sshCAUserFederatedCerts,
+	}, nil
 }
 
 // GetSSHConfig returns rendered templates for clients (user) or servers (host).

ca/client.go

@@ -527,7 +527,7 @@ func (c *Client) Federation() (*api.FederationResponse, error) {
 	return &federation, nil
 }
 
-// SSHKeys performs the get ssh keys request to the CA and returns the
+// SSHKeys performs the get /ssh/keys request to the CA and returns the
 // api.SSHKeysResponse struct.
 func (c *Client) SSHKeys() (*api.SSHKeysResponse, error) {
 	u := c.endpoint.ResolveReference(&url.URL{Path: "/ssh/keys"})
@@ -545,6 +545,24 @@ func (c *Client) SSHKeys() (*api.SSHKeysResponse, error) {
 	return &keys, nil
 }
 
+// SSHFederation performs the get /ssh/federation request to the CA and returns
+// the api.SSHKeysResponse struct.
+func (c *Client) SSHFederation() (*api.SSHKeysResponse, error) {
+	u := c.endpoint.ResolveReference(&url.URL{Path: "/ssh/federation"})
+	resp, err := c.client.Get(u.String())
+	if err != nil {
+		return nil, errors.Wrapf(err, "client GET %s failed", u)
+	}
+	if resp.StatusCode >= 400 {
+		return nil, readError(resp.Body)
+	}
+	var keys api.SSHKeysResponse
+	if err := readJSON(resp.Body, &keys); err != nil {
+		return nil, errors.Wrapf(err, "error reading %s", u)
+	}
+	return &keys, nil
+}
+
 // SSHConfig performs the POST request to the CA to get the ssh configuration
 // templates.
 func (c *Client) SSHConfig(req *api.SSHConfigRequest) (*api.SSHConfigResponse, error) {