package api import ( "context" "crypto/x509" "encoding/base64" "encoding/json" "net/http" "time" "github.com/pkg/errors" "github.com/smallstep/certificates/authority" "github.com/smallstep/certificates/authority/provisioner" "github.com/smallstep/certificates/errs" "github.com/smallstep/certificates/templates" "golang.org/x/crypto/ssh" ) // SSHAuthority is the interface implemented by a SSH CA authority. type SSHAuthority interface { SignSSH(ctx context.Context, key ssh.PublicKey, opts provisioner.SignSSHOptions, signOpts ...provisioner.SignOption) (*ssh.Certificate, error) RenewSSH(ctx context.Context, cert *ssh.Certificate) (*ssh.Certificate, error) RekeySSH(ctx context.Context, cert *ssh.Certificate, key ssh.PublicKey, signOpts ...provisioner.SignOption) (*ssh.Certificate, error) SignSSHAddUser(ctx context.Context, key ssh.PublicKey, cert *ssh.Certificate) (*ssh.Certificate, error) GetSSHRoots(ctx context.Context) (*authority.SSHKeys, error) GetSSHFederation(ctx context.Context) (*authority.SSHKeys, error) GetSSHConfig(ctx context.Context, typ string, data map[string]string) ([]templates.Output, error) CheckSSHHost(ctx context.Context, principal string, token string) (bool, error) GetSSHHosts(ctx context.Context, cert *x509.Certificate) ([]authority.Host, error) GetSSHBastion(ctx context.Context, user string, hostname string) (*authority.Bastion, error) } // SSHSignRequest is the request body of an SSH certificate request. type SSHSignRequest struct { PublicKey []byte `json:"publicKey"` // base64 encoded OTT string `json:"ott"` CertType string `json:"certType,omitempty"` KeyID string `json:"keyID,omitempty"` Principals []string `json:"principals,omitempty"` ValidAfter TimeDuration `json:"validAfter,omitempty"` ValidBefore TimeDuration `json:"validBefore,omitempty"` AddUserPublicKey []byte `json:"addUserPublicKey,omitempty"` IdentityCSR CertificateRequest `json:"identityCSR,omitempty"` TemplateData json.RawMessage `json:"templateData,omitempty"` } // Validate validates the SSHSignRequest. func (s *SSHSignRequest) Validate() error { switch { case s.CertType != "" && s.CertType != provisioner.SSHUserCert && s.CertType != provisioner.SSHHostCert: return errors.Errorf("unknown certType %s", s.CertType) case len(s.PublicKey) == 0: return errors.New("missing or empty publicKey") case len(s.OTT) == 0: return errors.New("missing or empty ott") default: // Validate identity signature if provided if s.IdentityCSR.CertificateRequest != nil { if err := s.IdentityCSR.CertificateRequest.CheckSignature(); err != nil { return errors.Wrap(err, "invalid identityCSR") } } return nil } } // SSHSignResponse is the response object that returns the SSH certificate. type SSHSignResponse struct { Certificate SSHCertificate `json:"crt"` AddUserCertificate *SSHCertificate `json:"addUserCrt,omitempty"` IdentityCertificate []Certificate `json:"identityCrt,omitempty"` } // SSHRootsResponse represents the response object that returns the SSH user and // host keys. type SSHRootsResponse struct { UserKeys []SSHPublicKey `json:"userKey,omitempty"` HostKeys []SSHPublicKey `json:"hostKey,omitempty"` } // SSHCertificate represents the response SSH certificate. type SSHCertificate struct { *ssh.Certificate `json:"omitempty"` } // SSHGetHostsResponse is the response object that returns the list of valid // hosts for SSH. type SSHGetHostsResponse struct { Hosts []authority.Host `json:"hosts"` } // MarshalJSON implements the json.Marshaler interface. Returns a quoted, // base64 encoded, openssh wire format version of the certificate. func (c SSHCertificate) MarshalJSON() ([]byte, error) { if c.Certificate == nil { return []byte("null"), nil } s := base64.StdEncoding.EncodeToString(c.Certificate.Marshal()) return []byte(`"` + s + `"`), nil } // UnmarshalJSON implements the json.Unmarshaler interface. The certificate is // expected to be a quoted, base64 encoded, openssh wire formatted block of bytes. func (c *SSHCertificate) UnmarshalJSON(data []byte) error { var s string if err := json.Unmarshal(data, &s); err != nil { return errors.Wrap(err, "error decoding certificate") } if s == "" { c.Certificate = nil return nil } certData, err := base64.StdEncoding.DecodeString(s) if err != nil { return errors.Wrap(err, "error decoding ssh certificate") } pub, err := ssh.ParsePublicKey(certData) if err != nil { return errors.Wrap(err, "error parsing ssh certificate") } cert, ok := pub.(*ssh.Certificate) if !ok { return errors.Errorf("error decoding ssh certificate: %T is not an *ssh.Certificate", pub) } c.Certificate = cert return nil } // SSHPublicKey represents a public key in a response object. type SSHPublicKey struct { ssh.PublicKey } // MarshalJSON implements the json.Marshaler interface. Returns a quoted, // base64 encoded, openssh wire format version of the public key. func (p *SSHPublicKey) MarshalJSON() ([]byte, error) { if p == nil || p.PublicKey == nil { return []byte("null"), nil } s := base64.StdEncoding.EncodeToString(p.PublicKey.Marshal()) return []byte(`"` + s + `"`), nil } // UnmarshalJSON implements the json.Unmarshaler interface. The public key is // expected to be a quoted, base64 encoded, openssh wire formatted block of // bytes. func (p *SSHPublicKey) UnmarshalJSON(data []byte) error { var s string if err := json.Unmarshal(data, &s); err != nil { return errors.Wrap(err, "error decoding ssh public key") } if s == "" { p.PublicKey = nil return nil } data, err := base64.StdEncoding.DecodeString(s) if err != nil { return errors.Wrap(err, "error decoding ssh public key") } pub, err := ssh.ParsePublicKey(data) if err != nil { return errors.Wrap(err, "error parsing ssh public key") } p.PublicKey = pub return nil } // Template represents the output of a template. type Template = templates.Output // SSHConfigRequest is the request body used to get the SSH configuration // templates. type SSHConfigRequest struct { Type string `json:"type"` Data map[string]string `json:"data"` } // Validate checks the values of the SSHConfigurationRequest. func (r *SSHConfigRequest) Validate() error { switch r.Type { case "": r.Type = provisioner.SSHUserCert return nil case provisioner.SSHUserCert, provisioner.SSHHostCert: return nil default: return errors.Errorf("unsupported type %s", r.Type) } } // SSHConfigResponse is the response that returns the rendered templates. type SSHConfigResponse struct { UserTemplates []Template `json:"userTemplates,omitempty"` HostTemplates []Template `json:"hostTemplates,omitempty"` } // SSHCheckPrincipalRequest is the request body used to check if a principal // certificate has been created. Right now it only supported for hosts // certificates. type SSHCheckPrincipalRequest struct { Type string `json:"type"` Principal string `json:"principal"` Token string `json:"token,omitempty"` } // Validate checks the check principal request. func (r *SSHCheckPrincipalRequest) Validate() error { switch { case r.Type != provisioner.SSHHostCert: return errors.Errorf("unsupported type %s", r.Type) case r.Principal == "": return errors.New("missing or empty principal") default: return nil } } // SSHCheckPrincipalResponse is the response body used to check if a principal // exists. type SSHCheckPrincipalResponse struct { Exists bool `json:"exists"` } // SSHBastionRequest is the request body used to get the bastion for a given // host. type SSHBastionRequest struct { User string `json:"user"` Hostname string `json:"hostname"` } // Validate checks the values of the SSHBastionRequest. func (r *SSHBastionRequest) Validate() error { if r.Hostname == "" { return errors.New("missing or empty hostname") } return nil } // SSHBastionResponse is the response body used to return the bastion for a // given host. type SSHBastionResponse struct { Hostname string `json:"hostname"` Bastion *authority.Bastion `json:"bastion,omitempty"` } // SSHSign is an HTTP handler that reads an SignSSHRequest with a one-time-token // (ott) from the body and creates a new SSH certificate with the information in // the request. func (h *caHandler) SSHSign(w http.ResponseWriter, r *http.Request) { var body SSHSignRequest if err := ReadJSON(r.Body, &body); err != nil { WriteError(w, errs.Wrap(http.StatusBadRequest, err, "error reading request body")) return } logOtt(w, body.OTT) if err := body.Validate(); err != nil { WriteError(w, errs.BadRequestErr(err)) return } publicKey, err := ssh.ParsePublicKey(body.PublicKey) if err != nil { WriteError(w, errs.Wrap(http.StatusBadRequest, err, "error parsing publicKey")) return } var addUserPublicKey ssh.PublicKey if body.AddUserPublicKey != nil { addUserPublicKey, err = ssh.ParsePublicKey(body.AddUserPublicKey) if err != nil { WriteError(w, errs.Wrap(http.StatusBadRequest, err, "error parsing addUserPublicKey")) return } } opts := provisioner.SignSSHOptions{ CertType: body.CertType, KeyID: body.KeyID, Principals: body.Principals, ValidBefore: body.ValidBefore, ValidAfter: body.ValidAfter, TemplateData: body.TemplateData, } ctx := provisioner.NewContextWithMethod(r.Context(), provisioner.SSHSignMethod) signOpts, err := h.Authority.Authorize(ctx, body.OTT) if err != nil { WriteError(w, errs.UnauthorizedErr(err)) return } cert, err := h.Authority.SignSSH(ctx, publicKey, opts, signOpts...) if err != nil { WriteError(w, errs.ForbiddenErr(err)) return } var addUserCertificate *SSHCertificate if addUserPublicKey != nil && authority.IsValidForAddUser(cert) == nil { addUserCert, err := h.Authority.SignSSHAddUser(ctx, addUserPublicKey, cert) if err != nil { WriteError(w, errs.ForbiddenErr(err)) return } addUserCertificate = &SSHCertificate{addUserCert} } // Sign identity certificate if available. var identityCertificate []Certificate if cr := body.IdentityCSR.CertificateRequest; cr != nil { ctx := authority.NewContextWithSkipTokenReuse(r.Context()) ctx = provisioner.NewContextWithMethod(ctx, provisioner.SignMethod) signOpts, err := h.Authority.Authorize(ctx, body.OTT) if err != nil { WriteError(w, errs.UnauthorizedErr(err)) return } // Enforce the same duration as ssh certificate. signOpts = append(signOpts, &identityModifier{ NotBefore: time.Unix(int64(cert.ValidAfter), 0), NotAfter: time.Unix(int64(cert.ValidBefore), 0), }) certChain, err := h.Authority.Sign(cr, provisioner.SignOptions{}, signOpts...) if err != nil { WriteError(w, errs.ForbiddenErr(err)) return } identityCertificate = certChainToPEM(certChain) } JSONStatus(w, &SSHSignResponse{ Certificate: SSHCertificate{cert}, AddUserCertificate: addUserCertificate, IdentityCertificate: identityCertificate, }, http.StatusCreated) } // SSHRoots is an HTTP handler that returns the SSH public keys for user and host // certificates. func (h *caHandler) SSHRoots(w http.ResponseWriter, r *http.Request) { keys, err := h.Authority.GetSSHRoots(r.Context()) if err != nil { WriteError(w, errs.InternalServerErr(err)) return } if len(keys.HostKeys) == 0 && len(keys.UserKeys) == 0 { WriteError(w, errs.NotFound("no keys found")) return } resp := new(SSHRootsResponse) 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) } // SSHFederation is an HTTP handler that returns the federated SSH public keys // for user and host certificates. func (h *caHandler) SSHFederation(w http.ResponseWriter, r *http.Request) { keys, err := h.Authority.GetSSHFederation(r.Context()) if err != nil { WriteError(w, errs.InternalServerErr(err)) return } if len(keys.HostKeys) == 0 && len(keys.UserKeys) == 0 { WriteError(w, errs.NotFound("no keys found")) return } resp := new(SSHRootsResponse) 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 // and servers. func (h *caHandler) SSHConfig(w http.ResponseWriter, r *http.Request) { var body SSHConfigRequest if err := ReadJSON(r.Body, &body); err != nil { WriteError(w, errs.Wrap(http.StatusBadRequest, err, "error reading request body")) return } if err := body.Validate(); err != nil { WriteError(w, errs.BadRequestErr(err)) return } ts, err := h.Authority.GetSSHConfig(r.Context(), body.Type, body.Data) if err != nil { WriteError(w, errs.InternalServerErr(err)) return } var config SSHConfigResponse switch body.Type { case provisioner.SSHUserCert: config.UserTemplates = ts case provisioner.SSHHostCert: config.HostTemplates = ts default: WriteError(w, errs.InternalServer("it should hot get here")) return } JSON(w, config) } // SSHCheckHost is the HTTP handler that returns if a hosts certificate exists or not. func (h *caHandler) SSHCheckHost(w http.ResponseWriter, r *http.Request) { var body SSHCheckPrincipalRequest if err := ReadJSON(r.Body, &body); err != nil { WriteError(w, errs.Wrap(http.StatusBadRequest, err, "error reading request body")) return } if err := body.Validate(); err != nil { WriteError(w, errs.BadRequestErr(err)) return } exists, err := h.Authority.CheckSSHHost(r.Context(), body.Principal, body.Token) if err != nil { WriteError(w, errs.InternalServerErr(err)) return } JSON(w, &SSHCheckPrincipalResponse{ Exists: exists, }) } // SSHGetHosts is the HTTP handler that returns a list of valid ssh hosts. func (h *caHandler) SSHGetHosts(w http.ResponseWriter, r *http.Request) { var cert *x509.Certificate if r.TLS != nil && len(r.TLS.PeerCertificates) > 0 { cert = r.TLS.PeerCertificates[0] } hosts, err := h.Authority.GetSSHHosts(r.Context(), cert) if err != nil { WriteError(w, errs.InternalServerErr(err)) return } JSON(w, &SSHGetHostsResponse{ Hosts: hosts, }) } // SSHBastion provides returns the bastion configured if any. func (h *caHandler) SSHBastion(w http.ResponseWriter, r *http.Request) { var body SSHBastionRequest if err := ReadJSON(r.Body, &body); err != nil { WriteError(w, errs.Wrap(http.StatusBadRequest, err, "error reading request body")) return } if err := body.Validate(); err != nil { WriteError(w, errs.BadRequestErr(err)) return } bastion, err := h.Authority.GetSSHBastion(r.Context(), body.User, body.Hostname) if err != nil { WriteError(w, errs.InternalServerErr(err)) return } JSON(w, &SSHBastionResponse{ Hostname: body.Hostname, Bastion: bastion, }) } // identityModifier is a custom modifier used to force a fixed duration. type identityModifier struct { NotBefore time.Time NotAfter time.Time } func (m *identityModifier) Enforce(cert *x509.Certificate) error { cert.NotBefore = m.NotBefore cert.NotAfter = m.NotAfter return nil }