package provisioner import ( "context" "crypto/x509" "time" "github.com/pkg/errors" "github.com/smallstep/cli/crypto/x509util" "github.com/smallstep/cli/jose" ) // 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 *SSHOptions `json:"ssh,omitempty"` } // JWK is the default provisioner, an entity that can sign tokens necessary for // signature requests. type JWK struct { Type string `json:"type"` Name string `json:"name"` Key *jose.JSONWebKey `json:"key"` EncryptedKey string `json:"encryptedKey,omitempty"` Claims *Claims `json:"claims,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, errors.Wrapf(err, "error parsing token") } var claims jwtPayload if err = jwt.Claims(p.Key, &claims); err != nil { return nil, errors.Wrap(err, "error parsing 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, errors.Wrapf(err, "invalid token") } // validate audiences with the defaults if !matchesAudience(claims.Audience, audiences) { return nil, errors.New("invalid token: invalid audience claim (aud)") } if claims.Subject == "" { return nil, errors.New("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(token string) error { _, err := p.authorizeToken(token, p.audiences.Revoke) return err } // 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, err } // Check for SSH token if claims.Step != nil && claims.Step.SSH != nil { 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. if len(claims.SANs) == 0 { claims.SANs = []string{claims.Subject} } dnsNames, ips := x509util.SplitSANs(claims.SANs) return []SignOption{ commonNameValidator(claims.Subject), dnsNamesValidator(dnsNames), ipAddressesValidator(ips), profileDefaultDuration(p.claimer.DefaultTLSCertDuration()), newProvisionerExtensionOption(TypeJWK, p.Name, p.Key.KeyID), newValidityValidator(p.claimer.MinTLSCertDuration(), p.claimer.MaxTLSCertDuration()), }, nil } // AuthorizeRenewal returns an error if the renewal is disabled. func (p *JWK) AuthorizeRenewal(cert *x509.Certificate) error { if p.claimer.IsDisableRenewal() { return errors.Errorf("renew is disabled for provisioner %s", p.GetID()) } return nil } // authorizeSSHSign returns the list of SignOption for a SignSSH request. func (p *JWK) authorizeSSHSign(claims *jwtPayload) ([]SignOption, error) { t := now() opts := claims.Step.SSH 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 if opts.CertType != "" { signOptions = append(signOptions, sshCertificateCertTypeModifier(opts.CertType)) } if len(opts.Principals) > 0 { signOptions = append(signOptions, sshCertificatePrincipalsModifier(opts.Principals)) } if !opts.ValidAfter.IsZero() { signOptions = append(signOptions, sshCertificateValidAfterModifier(opts.ValidAfter.RelativeTime(t).Unix())) } if !opts.ValidBefore.IsZero() { signOptions = append(signOptions, sshCertificateValidBeforeModifier(opts.ValidBefore.RelativeTime(t).Unix())) } return append(signOptions, // set the default extensions &sshDefaultExtensionModifier{}, // checks the validity bounds, and set the validity if has not been set &sshCertificateValidityModifier{p.claimer}, // require all the fields in the SSH certificate &sshCertificateDefaultValidator{}, ), nil }