package provisioner import ( "context" "crypto/x509" "encoding/json" "net/http" "strings" "time" "github.com/pkg/errors" "github.com/smallstep/cli/jose" ) // openIDConfiguration contains the necessary properties in the // `/.well-known/openid-configuration` document. type openIDConfiguration struct { Issuer string `json:"issuer"` JWKSetURI string `json:"jwks_uri"` } // Validate validates the values in a well-known OpenID configuration endpoint. func (c openIDConfiguration) Validate() error { switch { case c.Issuer == "": return errors.New("issuer cannot be empty") case c.JWKSetURI == "": return errors.New("jwks_uri cannot be empty") default: return nil } } // openIDPayload represents the fields on the id_token JWT payload. type openIDPayload struct { jose.Claims AtHash string `json:"at_hash"` AuthorizedParty string `json:"azp"` Email string `json:"email"` EmailVerified bool `json:"email_verified"` Hd string `json:"hd"` Nonce string `json:"nonce"` Groups []string `json:"groups"` } // OIDC represents an OAuth 2.0 OpenID Connect provider. // // ClientSecret is mandatory, but it can be an empty string. type OIDC struct { Type string `json:"type"` Name string `json:"name"` ClientID string `json:"clientID"` ClientSecret string `json:"clientSecret"` ConfigurationEndpoint string `json:"configurationEndpoint"` Admins []string `json:"admins,omitempty"` Domains []string `json:"domains,omitempty"` Groups []string `json:"groups,omitempty"` Claims *Claims `json:"claims,omitempty"` configuration openIDConfiguration keyStore *keyStore claimer *Claimer } // IsAdmin returns true if the given email is in the Admins whitelist, false // otherwise. func (o *OIDC) IsAdmin(email string) bool { email = sanitizeEmail(email) for _, e := range o.Admins { if email == sanitizeEmail(e) { return true } } return false } func sanitizeEmail(email string) string { if i := strings.LastIndex(email, "@"); i >= 0 { email = email[:i] + strings.ToLower(email[i:]) } return email } // GetID returns the provisioner unique identifier, the OIDC provisioner the // uses the clientID for this. func (o *OIDC) GetID() string { return o.ClientID } // GetTokenID returns the provisioner unique identifier, the OIDC provisioner the // uses the clientID for this. func (o *OIDC) 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 openIDPayload if err = token.UnsafeClaimsWithoutVerification(&claims); err != nil { return "", errors.Wrap(err, "error verifying claims") } return claims.Nonce, nil } // GetName returns the name of the provisioner. func (o *OIDC) GetName() string { return o.Name } // GetType returns the type of provisioner. func (o *OIDC) GetType() Type { return TypeOIDC } // GetEncryptedKey is not available in an OIDC provisioner. func (o *OIDC) GetEncryptedKey() (kid string, key string, ok bool) { return "", "", false } // Init validates and initializes the OIDC provider. func (o *OIDC) Init(config Config) (err error) { switch { case o.Type == "": return errors.New("type cannot be empty") case o.Name == "": return errors.New("name cannot be empty") case o.ClientID == "": return errors.New("clientID cannot be empty") case o.ConfigurationEndpoint == "": return errors.New("configurationEndpoint cannot be empty") } // Update claims with global ones if o.claimer, err = NewClaimer(o.Claims, config.Claims); err != nil { return err } // Decode and validate openid-configuration endpoint if err := getAndDecode(o.ConfigurationEndpoint, &o.configuration); err != nil { return err } if err := o.configuration.Validate(); err != nil { return errors.Wrapf(err, "error parsing %s", o.ConfigurationEndpoint) } // Get JWK key set o.keyStore, err = newKeyStore(o.configuration.JWKSetURI) if err != nil { return err } return nil } // ValidatePayload validates the given token payload. func (o *OIDC) ValidatePayload(p openIDPayload) error { // According to "rfc7519 JSON Web Token" acceptable skew should be no more // than a few minutes. if err := p.ValidateWithLeeway(jose.Expected{ Issuer: o.configuration.Issuer, Audience: jose.Audience{o.ClientID}, Time: time.Now().UTC(), }, time.Minute); err != nil { return errors.Wrap(err, "failed to validate payload") } // Validate azp if present if p.AuthorizedParty != "" && p.AuthorizedParty != o.ClientID { return errors.New("failed to validate payload: invalid azp") } // Enforce an email claim if p.Email == "" { return errors.New("failed to validate payload: email not found") } // Validate domains (case-insensitive) if !o.IsAdmin(p.Email) && len(o.Domains) > 0 { email := sanitizeEmail(p.Email) var found bool for _, d := range o.Domains { if strings.HasSuffix(email, "@"+strings.ToLower(d)) { found = true break } } if !found { return errors.New("failed to validate payload: email is not allowed") } } // Filter by oidc group claim if len(o.Groups) > 0 { var found bool for _, group := range o.Groups { for _, g := range p.Groups { if g == group { found = true break } } } if !found { return errors.New("validation failed: invalid group") } } return nil } // authorizeToken applies the most common provisioner authorization claims, // leaving the rest to context specific methods. func (o *OIDC) authorizeToken(token string) (*openIDPayload, error) { jwt, err := jose.ParseSigned(token) if err != nil { return nil, errors.Wrapf(err, "error parsing token") } // Parse claims to get the kid var claims openIDPayload if err := jwt.UnsafeClaimsWithoutVerification(&claims); err != nil { return nil, errors.Wrap(err, "error parsing claims") } found := false kid := jwt.Headers[0].KeyID keys := o.keyStore.Get(kid) for _, key := range keys { if err := jwt.Claims(key, &claims); err == nil { found = true break } } if !found { return nil, errors.New("cannot validate token") } if err := o.ValidatePayload(claims); err != nil { return nil, err } 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. // Only tokens generated by an admin have the right to revoke a certificate. func (o *OIDC) AuthorizeRevoke(token string) error { claims, err := o.authorizeToken(token) if err != nil { return err } // Only admins can revoke certificates. if o.IsAdmin(claims.Email) { return nil } return errors.New("cannot revoke with non-admin token") } // AuthorizeSign validates the given token. func (o *OIDC) AuthorizeSign(ctx context.Context, token string) ([]SignOption, error) { claims, err := o.authorizeToken(token) if err != nil { return nil, err } // Check for the sign ssh method, default to sign X.509 if m := MethodFromContext(ctx); m == SignSSHMethod { if o.claimer.IsSSHCAEnabled() == false { return nil, errors.Errorf("ssh ca is disabled for provisioner %s", o.GetID()) } return o.authorizeSSHSign(claims) } // Admins should be able to authorize any SAN if o.IsAdmin(claims.Email) { return []SignOption{ profileDefaultDuration(o.claimer.DefaultTLSCertDuration()), newProvisionerExtensionOption(TypeOIDC, o.Name, o.ClientID), newValidityValidator(o.claimer.MinTLSCertDuration(), o.claimer.MaxTLSCertDuration()), }, nil } so := []SignOption{ defaultPublicKeyValidator{}, profileDefaultDuration(o.claimer.DefaultTLSCertDuration()), newProvisionerExtensionOption(TypeOIDC, o.Name, o.ClientID), newValidityValidator(o.claimer.MinTLSCertDuration(), o.claimer.MaxTLSCertDuration()), } // Admins should be able to authorize any SAN if o.IsAdmin(claims.Email) { return so, nil } return append(so, emailOnlyIdentity(claims.Email)), nil } // AuthorizeRenewal returns an error if the renewal is disabled. func (o *OIDC) AuthorizeRenewal(cert *x509.Certificate) error { if o.claimer.IsDisableRenewal() { return errors.Errorf("renew is disabled for provisioner %s", o.GetID()) } return nil } // authorizeSSHSign returns the list of SignOption for a SignSSH request. func (o *OIDC) authorizeSSHSign(claims *openIDPayload) ([]SignOption, error) { signOptions := []SignOption{ // set the key id to the token subject sshCertificateKeyIDModifier(claims.Email), } name := SanitizeSSHUserPrincipal(claims.Email) if !sshUserRegex.MatchString(name) { return nil, errors.Errorf("invalid principal '%s' from email address '%s'", name, claims.Email) } // Admin users will default to user + name but they can be changed by the // user options. Non-admins are only able to sign user certificates. defaults := SSHOptions{ CertType: SSHUserCert, Principals: []string{name}, } if !o.IsAdmin(claims.Email) { signOptions = append(signOptions, sshCertificateOptionsValidator(defaults)) } // Default to a user with name as principal if not set signOptions = append(signOptions, sshCertificateDefaultsModifier(defaults)) return append(signOptions, // set the default extensions &sshDefaultExtensionModifier{}, // checks the validity bounds, and set the validity if has not been set &sshCertificateValidityModifier{o.claimer}, // require all the fields in the SSH certificate &sshCertificateDefaultValidator{}, ), nil } func getAndDecode(uri string, v interface{}) error { resp, err := http.Get(uri) if err != nil { return errors.Wrapf(err, "failed to connect to %s", uri) } defer resp.Body.Close() if err := json.NewDecoder(resp.Body).Decode(v); err != nil { return errors.Wrapf(err, "error reading %s", uri) } return nil }