package provisioner import ( "context" "crypto/x509" "net/http" "time" "github.com/pkg/errors" "github.com/smallstep/certificates/errs" "go.step.sm/crypto/jose" "go.step.sm/crypto/sshutil" "go.step.sm/crypto/x509util" ) // jwtPayload extends jwt.Claims with step attributes. type jwtPayload struct { jose.Claims SANs []string `json:"sans,omitempty"` Step *stepPayload `json:"step,omitempty"` } type stepPayload struct { SSH *SignSSHOptions `json:"ssh,omitempty"` } // JWK is the default provisioner, an entity that can sign tokens necessary for // signature requests. type JWK struct { *base Type string `json:"type"` Name string `json:"name"` Key *jose.JSONWebKey `json:"key"` EncryptedKey string `json:"encryptedKey,omitempty"` Claims *Claims `json:"claims,omitempty"` Options *Options `json:"options,omitempty"` claimer *Claimer audiences Audiences } // GetID returns the provisioner unique identifier. The name and credential id // should uniquely identify any JWK provisioner. func (p *JWK) GetID() string { return p.Name + ":" + p.Key.KeyID } // GetTokenID returns the identifier of the token. func (p *JWK) GetTokenID(ott string) (string, error) { // Validate payload token, err := jose.ParseSigned(ott) if err != nil { return "", errors.Wrap(err, "error parsing token") } // Get claims w/out verification. We need to look up the provisioner // key in order to verify the claims and we need the issuer from the claims // before we can look up the provisioner. var claims jose.Claims if err = token.UnsafeClaimsWithoutVerification(&claims); err != nil { return "", errors.Wrap(err, "error verifying claims") } return claims.ID, nil } // GetName returns the name of the provisioner. func (p *JWK) GetName() string { return p.Name } // GetType returns the type of provisioner. func (p *JWK) GetType() Type { return TypeJWK } // GetEncryptedKey returns the base provisioner encrypted key if it's defined. func (p *JWK) GetEncryptedKey() (string, string, bool) { return p.Key.KeyID, p.EncryptedKey, len(p.EncryptedKey) > 0 } // Init initializes and validates the fields of a JWK type. func (p *JWK) Init(config Config) (err error) { switch { case p.Type == "": return errors.New("provisioner type cannot be empty") case p.Name == "": return errors.New("provisioner name cannot be empty") case p.Key == nil: return errors.New("provisioner key cannot be empty") } // Update claims with global ones if p.claimer, err = NewClaimer(p.Claims, config.Claims); err != nil { return err } p.audiences = config.Audiences return err } // authorizeToken performs common jwt authorization actions and returns the // claims for case specific downstream parsing. // e.g. a Sign request will auth/validate different fields than a Revoke request. func (p *JWK) authorizeToken(token string, audiences []string) (*jwtPayload, error) { jwt, err := jose.ParseSigned(token) if err != nil { return nil, errs.Wrap(http.StatusUnauthorized, err, "jwk.authorizeToken; error parsing jwk token") } var claims jwtPayload if err = jwt.Claims(p.Key, &claims); err != nil { return nil, errs.Wrap(http.StatusUnauthorized, err, "jwk.authorizeToken; error parsing jwk claims") } // According to "rfc7519 JSON Web Token" acceptable skew should be no // more than a few minutes. if err = claims.ValidateWithLeeway(jose.Expected{ Issuer: p.Name, Time: time.Now().UTC(), }, time.Minute); err != nil { return nil, errs.Wrapf(http.StatusUnauthorized, err, "jwk.authorizeToken; invalid jwk claims") } // validate audiences with the defaults if !matchesAudience(claims.Audience, audiences) { return nil, errs.Unauthorized("jwk.authorizeToken; invalid jwk token audience claim (aud); want %s, but got %s", audiences, claims.Audience) } if claims.Subject == "" { return nil, errs.Unauthorized("jwk.authorizeToken; jwk token subject cannot be empty") } return &claims, nil } // AuthorizeRevoke returns an error if the provisioner does not have rights to // revoke the certificate with serial number in the `sub` property. func (p *JWK) AuthorizeRevoke(ctx context.Context, token string) error { _, err := p.authorizeToken(token, p.audiences.Revoke) return errs.Wrap(http.StatusInternalServerError, err, "jwk.AuthorizeRevoke") } // AuthorizeSign validates the given token. func (p *JWK) AuthorizeSign(ctx context.Context, token string) ([]SignOption, error) { claims, err := p.authorizeToken(token, p.audiences.Sign) if err != nil { return nil, errs.Wrap(http.StatusInternalServerError, err, "jwk.AuthorizeSign") } // 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. if len(claims.SANs) == 0 { claims.SANs = []string{claims.Subject} } // Certificate templates data := x509util.CreateTemplateData(claims.Subject, claims.SANs) if v, err := unsafeParseSigned(token); err == nil { data.SetToken(v) } templateOptions, err := TemplateOptions(p.Options, data) if err != nil { return nil, errs.Wrap(http.StatusInternalServerError, err, "jwk.AuthorizeSign") } return []SignOption{ templateOptions, // modifiers / withOptions newProvisionerExtensionOption(TypeJWK, p.Name, p.Key.KeyID), profileDefaultDuration(p.claimer.DefaultTLSCertDuration()), // validators commonNameValidator(claims.Subject), defaultPublicKeyValidator{}, defaultSANsValidator(claims.SANs), newValidityValidator(p.claimer.MinTLSCertDuration(), p.claimer.MaxTLSCertDuration()), }, nil } // AuthorizeRenew returns an error if the renewal is disabled. // NOTE: This method does not actually validate the certificate or check it's // revocation status. Just confirms that the provisioner that created the // certificate was configured to allow renewals. func (p *JWK) AuthorizeRenew(ctx context.Context, cert *x509.Certificate) error { if p.claimer.IsDisableRenewal() { return errs.Unauthorized("jwk.AuthorizeRenew; renew is disabled for jwk provisioner %s", p.GetID()) } return nil } // AuthorizeSSHSign returns the list of SignOption for a SignSSH request. func (p *JWK) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption, error) { if !p.claimer.IsSSHCAEnabled() { return nil, errs.Unauthorized("jwk.AuthorizeSSHSign; sshCA is disabled for jwk provisioner %s", p.GetID()) } claims, err := p.authorizeToken(token, p.audiences.SSHSign) if err != nil { return nil, errs.Wrap(http.StatusInternalServerError, err, "jwk.AuthorizeSSHSign") } if claims.Step == nil || claims.Step.SSH == nil { return nil, errs.Unauthorized("jwk.AuthorizeSSHSign; jwk token must be an SSH provisioning token") } opts := claims.Step.SSH signOptions := []SignOption{ // validates user's SignSSHOptions with the ones in the token sshCertOptionsValidator(*opts), // validate users's KeyID is the token subject. sshCertOptionsValidator(SignSSHOptions{KeyID: claims.Subject}), } // Default template attributes. certType := sshutil.UserCert keyID := claims.Subject principals := []string{claims.Subject} // Use options in the token. if opts.CertType != "" { if certType, err = sshutil.CertTypeFromString(opts.CertType); err != nil { return nil, errs.Wrap(http.StatusBadRequest, err, "jwk.AuthorizeSSHSign") } } if opts.KeyID != "" { keyID = opts.KeyID } if len(opts.Principals) > 0 { principals = opts.Principals } // Certificate templates. data := sshutil.CreateTemplateData(certType, keyID, principals) if v, err := unsafeParseSigned(token); err == nil { data.SetToken(v) } templateOptions, err := TemplateSSHOptions(p.Options, data) if err != nil { return nil, errs.Wrap(http.StatusInternalServerError, err, "jwk.AuthorizeSign") } signOptions = append(signOptions, templateOptions) // Add modifiers from custom claims t := now() if !opts.ValidAfter.IsZero() { signOptions = append(signOptions, sshCertValidAfterModifier(opts.ValidAfter.RelativeTime(t).Unix())) } if !opts.ValidBefore.IsZero() { signOptions = append(signOptions, sshCertValidBeforeModifier(opts.ValidBefore.RelativeTime(t).Unix())) } return append(signOptions, // Set the validity bounds if not set. &sshDefaultDuration{p.claimer}, // Validate public key &sshDefaultPublicKeyValidator{}, // Validate the validity period. &sshCertValidityValidator{p.claimer}, // Require and validate all the default fields in the SSH certificate. &sshCertDefaultValidator{}, ), nil } // AuthorizeSSHRevoke returns nil if the token is valid, false otherwise. func (p *JWK) AuthorizeSSHRevoke(ctx context.Context, token string) error { _, err := p.authorizeToken(token, p.audiences.SSHRevoke) return errs.Wrap(http.StatusInternalServerError, err, "jwk.AuthorizeSSHRevoke") }