Add multiuse capability to k8ssa provisioners

api/ssh.go

@@ -35,6 +35,7 @@ type SSHSignRequest struct {
 	ValidAfter       TimeDuration `json:"validAfter,omitempty"`
 	ValidBefore      TimeDuration `json:"validBefore,omitempty"`
 	AddUserPublicKey []byte       `json:"addUserPublicKey,omitempty"`
+	KeyID            string       `json:"keyID"`
 }
 
 // Validate validates the SSHSignRequest.
@@ -239,6 +240,7 @@ func (h *caHandler) SSHSign(w http.ResponseWriter, r *http.Request) {
 
 	opts := provisioner.SSHOptions{
 		CertType:    body.CertType,
+		KeyID:       body.KeyID,
 		Principals:  body.Principals,
 		ValidBefore: body.ValidBefore,
 		ValidAfter:  body.ValidAfter,

authority/provisioner/jwk.go

@@ -180,8 +180,7 @@ func (p *JWK) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption,
 	if !p.claimer.IsSSHCAEnabled() {
 		return nil, errors.Errorf("ssh ca is disabled for provisioner %s", p.GetID())
 	}
-	// TODO: fix audiences
+	claims, err := p.authorizeToken(token, p.audiences.SSHSign)
-	claims, err := p.authorizeToken(token, p.audiences.Sign)
 	if err != nil {
 		return nil, err
 	}
@@ -192,8 +191,6 @@ func (p *JWK) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption,
 	signOptions := []SignOption{
 		// validates user's SSHOptions with the ones in the token
 		sshCertificateOptionsValidator(*opts),
-		// set the key id to the token subject
-		sshCertificateKeyIDModifier(claims.Subject),
 	}
 
 	t := now()
@@ -219,6 +216,8 @@ func (p *JWK) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption,
 		&sshDefaultExtensionModifier{},
 		// Set the validity bounds if not set.
 		sshDefaultValidityModifier(p.claimer),
+		// Validate that the keyID is equivalent to the token subject.
+		sshCertKeyIDValidator(claims.Subject),
 		// Validate public key
 		&sshDefaultPublicKeyValidator{},
 		// Validate the validity period.
@@ -230,7 +229,6 @@ func (p *JWK) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption,
 
 // AuthorizeSSHRevoke returns nil if the token is valid, false otherwise.
 func (p *JWK) AuthorizeSSHRevoke(ctx context.Context, token string) error {
-	// TODO fix audience.
 	_, err := p.authorizeToken(token, p.audiences.SSHRevoke)
 	return err
 }

authority/provisioner/k8sSA.go

@@ -212,11 +212,6 @@ func (p *K8sSA) AuthorizeSign(ctx context.Context, token string) ([]SignOption,
 		return nil, err
 	}
 
-	// Check for SSH sign-ing request.
-	if MethodFromContext(ctx) == SignSSHMethod {
-		return nil, errors.New("ssh certificates not enabled for k8s ServiceAccount provisioners")
-	}
-
 	return []SignOption{
 		// modifiers / withOptions
 		newProvisionerExtensionOption(TypeK8sSA, p.Name, ""),
@@ -227,14 +222,41 @@ func (p *K8sSA) AuthorizeSign(ctx context.Context, token string) ([]SignOption,
 	}, nil
 }
 
-// AuthorizeRenewal returns an error if the renewal is disabled.
+// AuthorizeRenew returns an error if the renewal is disabled.
-func (p *K8sSA) AuthorizeRenewal(cert *x509.Certificate) error {
+func (p *K8sSA) AuthorizeRenew(ctx context.Context, cert *x509.Certificate) error {
 	if p.claimer.IsDisableRenewal() {
 		return errors.Errorf("renew is disabled for provisioner %s", p.GetID())
 	}
 	return nil
 }
 
+// AuthorizeSSHSign validates an request for an SSH certificate.
+func (p *K8sSA) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption, error) {
+	if !p.claimer.IsSSHCAEnabled() {
+		return nil, errors.Errorf("authorizeSSHSign: ssh ca is disabled for provisioner %s", p.GetID())
+	}
+	_, err := p.authorizeToken(token, p.audiences.SSHSign)
+	if err != nil {
+		return nil, errors.Wrap(err, "authorizeSSHSign")
+	}
+
+	// Default to a user certificate with no principals if not set
+	signOptions := []SignOption{sshCertificateDefaultsModifier{CertType: SSHUserCert}}
+
+	return append(signOptions,
+		// Set the default extensions.
+		&sshDefaultExtensionModifier{},
+		// Set the validity bounds if not set.
+		sshDefaultValidityModifier(p.claimer),
+		// Validate public key
+		&sshDefaultPublicKeyValidator{},
+		// Validate the validity period.
+		&sshCertificateValidityValidator{p.claimer},
+		// Require and validate all the default fields in the SSH certificate.
+		&sshCertificateDefaultValidator{},
+	), nil
+}
+
 /*
 func checkAccess(authz kauthz.AuthorizationV1Interface) error {
 	r := &kauthzApi.SelfSubjectAccessReview{

authority/provisioner/oidc.go

@@ -322,7 +322,7 @@ func (o *OIDC) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption
 		return nil, err
 	}
 	signOptions := []SignOption{
-		// set the key id to the token subject
+		// set the key id to the token email
 		sshCertificateKeyIDModifier(claims.Email),
 	}
 

authority/provisioner/sign_ssh_options.go

@@ -49,6 +49,7 @@ type SSHCertificateOptionsValidator interface {
 // SSHOptions contains the options that can be passed to the SignSSH method.
 type SSHOptions struct {
 	CertType    string       `json:"certType"`
+	KeyID       string       `json:"keyID"`
 	Principals  []string     `json:"principals"`
 	ValidAfter  TimeDuration `json:"validAfter,omitempty"`
 	ValidBefore TimeDuration `json:"validBefore,omitempty"`
@@ -70,6 +71,8 @@ func (o SSHOptions) Modify(cert *ssh.Certificate) error {
 	default:
 		return errors.Errorf("ssh certificate has an unknown type: %s", o.CertType)
 	}
+
+	cert.KeyId = o.KeyID
 	cert.ValidPrincipals = o.Principals
 	if !o.ValidAfter.IsZero() {
 		cert.ValidAfter = uint64(o.ValidAfter.Time().Unix())
@@ -373,6 +376,17 @@ func (v sshDefaultPublicKeyValidator) Valid(cert *ssh.Certificate) error {
 	}
 }
 
+// sshCertKeyIDValidator implements a validator for the KeyId attribute.
+type sshCertKeyIDValidator string
+
+// Valid returns an error if the given certificate does not contain the necessary fields.
+func (v sshCertKeyIDValidator) Valid(cert *ssh.Certificate) error {
+	if string(v) != cert.KeyId {
+		return errors.Errorf("invalid ssh certificate KeyId; want %s, but got %s", string(v), cert.KeyId)
+	}
+	return nil
+}
+
 // sshCertTypeUInt32
 func sshCertTypeUInt32(ct string) uint32 {
 	switch ct {

authority/provisioner/x5c.go

@@ -183,14 +183,6 @@ func (p *X5C) AuthorizeSign(ctx context.Context, token string) ([]SignOption, er
 		return nil, err
 	}
 
-	// Check for SSH sign-ing request.
-	if MethodFromContext(ctx) == SignSSHMethod {
-		if !p.claimer.IsSSHCAEnabled() {
-			return nil, errors.Errorf("ssh ca is disabled for provisioner %s", p.GetID())
-		}
-		return p.authorizeSSHSign(claims)
-	}
-
 	// NOTE: This is for backwards compatibility with older versions of cli
 	// and certificates. Older versions added the token subject as the only SAN
 	// in a CSR by default.
@@ -222,8 +214,17 @@ func (p *X5C) AuthorizeRenew(ctx context.Context, cert *x509.Certificate) error
 	return nil
 }
 
-// authorizeSSHSign returns the list of SignOption for a SignSSH request.
+// AuthorizeSSHSign returns the list of SignOption for a SignSSH request.
-func (p *X5C) authorizeSSHSign(claims *x5cPayload) ([]SignOption, error) {
+func (p *X5C) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption, error) {
+	if !p.claimer.IsSSHCAEnabled() {
+		return nil, errors.Errorf("ssh ca is disabled for provisioner %s", p.GetID())
+	}
+
+	claims, err := p.authorizeToken(token, p.audiences.SSHSign)
+	if err != nil {
+		return nil, err
+	}
+
 	if claims.Step == nil || claims.Step.SSH == nil {
 		return nil, errors.New("authorization token must be an SSH provisioning token")
 	}
@@ -231,8 +232,6 @@ func (p *X5C) authorizeSSHSign(claims *x5cPayload) ([]SignOption, error) {
 	signOptions := []SignOption{
 		// validates user's SSHOptions with the ones in the token
 		sshCertificateOptionsValidator(*opts),
-		// set the key id to the token subject
-		sshCertificateKeyIDModifier(claims.Subject),
 	}
 
 	// Add modifiers from custom claims
@@ -258,6 +257,8 @@ func (p *X5C) authorizeSSHSign(claims *x5cPayload) ([]SignOption, error) {
 		&sshDefaultExtensionModifier{},
 		// Checks the validity bounds, and set the validity if has not been set.
 		sshLimitValidityModifier(p.claimer, claims.chains[0][0].NotAfter),
+		// set the key id to the token subject
+		sshCertKeyIDValidator(claims.Subject),
 		// Validate public key.
 		&sshDefaultPublicKeyValidator{},
 		// Validate the validity period.