open-consul/internal/go-sso/oidcauth/oidc.go

286 lines
8.7 KiB
Go
Raw Normal View History

2020-05-12 01:59:29 +00:00
package oidcauth
import (
"context"
"encoding/json"
"errors"
"fmt"
"strings"
"time"
"github.com/coreos/go-oidc"
"github.com/hashicorp/go-uuid"
"golang.org/x/oauth2"
)
var (
oidcStateTimeout = 10 * time.Minute
oidcStateCleanupInterval = 1 * time.Minute
)
// GetAuthCodeURL is the first part of the OIDC authorization code workflow.
// The statePayload field is stored in the Authenticator instance keyed by the
// "state" key so it can be returned during a future call to
// ClaimsFromAuthCode.
//
// Requires the authenticator's config type be set to 'oidc'.
func (a *Authenticator) GetAuthCodeURL(ctx context.Context, redirectURI string, statePayload interface{}) (string, error) {
if a.config.authType() != authOIDCFlow {
return "", fmt.Errorf("GetAuthCodeURL is incompatible with type %q", TypeJWT)
}
if redirectURI == "" {
return "", errors.New("missing redirect_uri")
}
if !validRedirect(redirectURI, a.config.AllowedRedirectURIs) {
return "", fmt.Errorf("unauthorized redirect_uri: %s", redirectURI)
}
// "openid" is a required scope for OpenID Connect flows
scopes := append([]string{oidc.ScopeOpenID}, a.config.OIDCScopes...)
// Configure an OpenID Connect aware OAuth2 client
oauth2Config := oauth2.Config{
ClientID: a.config.OIDCClientID,
ClientSecret: a.config.OIDCClientSecret,
RedirectURL: redirectURI,
Endpoint: a.provider.Endpoint(),
Scopes: scopes,
}
stateID, nonce, err := a.createOIDCState(redirectURI, statePayload)
if err != nil {
return "", fmt.Errorf("error generating OAuth state: %v", err)
}
authCodeOpts := []oauth2.AuthCodeOption{
oidc.Nonce(nonce),
}
if len(a.config.OIDCACRValues) > 0 {
authCodeOpts = append(authCodeOpts, oauth2.SetAuthURLParam("acr_values", strings.Join(a.config.OIDCACRValues, " ")))
}
2020-05-12 01:59:29 +00:00
return oauth2Config.AuthCodeURL(stateID, authCodeOpts...), nil
}
// ClaimsFromAuthCode is the second part of the OIDC authorization code
// workflow. The interface{} return value is the statePayload previously passed
// via GetAuthCodeURL.
//
// The error may be of type *ProviderLoginFailedError or
// *TokenVerificationFailedError which can be detected via errors.As().
//
// Requires the authenticator's config type be set to 'oidc'.
func (a *Authenticator) ClaimsFromAuthCode(ctx context.Context, stateParam, code string) (*Claims, interface{}, error) {
if a.config.authType() != authOIDCFlow {
return nil, nil, fmt.Errorf("ClaimsFromAuthCode is incompatible with type %q", TypeJWT)
}
// TODO(sso): this could be because we ACTUALLY are getting OIDC error responses and
// should handle them elsewhere!
if code == "" {
return nil, nil, &ProviderLoginFailedError{
Err: fmt.Errorf("OAuth code parameter not provided"),
}
}
state := a.verifyOIDCState(stateParam)
if state == nil {
return nil, nil, &ProviderLoginFailedError{
Err: fmt.Errorf("Expired or missing OAuth state."),
}
}
oidcCtx := contextWithHttpClient(ctx, a.httpClient)
var oauth2Config = oauth2.Config{
ClientID: a.config.OIDCClientID,
ClientSecret: a.config.OIDCClientSecret,
RedirectURL: state.redirectURI,
Endpoint: a.provider.Endpoint(),
Scopes: []string{oidc.ScopeOpenID},
}
oauth2Token, err := oauth2Config.Exchange(oidcCtx, code)
if err != nil {
return nil, nil, &ProviderLoginFailedError{
Err: fmt.Errorf("Error exchanging oidc code: %w", err),
}
}
// Extract the ID Token from OAuth2 token.
rawToken, ok := oauth2Token.Extra("id_token").(string)
if !ok {
return nil, nil, &TokenVerificationFailedError{
Err: errors.New("No id_token found in response."),
}
}
if a.config.VerboseOIDCLogging && a.logger != nil {
a.logger.Debug("OIDC provider response", "ID token", rawToken)
}
// Parse and verify ID Token payload.
allClaims, err := a.verifyOIDCToken(ctx, rawToken) // TODO(sso): should this use oidcCtx?
if err != nil {
return nil, nil, &TokenVerificationFailedError{
Err: err,
}
}
if allClaims["nonce"] != state.nonce { // TODO(sso): does this need a cast?
return nil, nil, &TokenVerificationFailedError{
Err: errors.New("Invalid ID token nonce."),
}
}
delete(allClaims, "nonce")
// Attempt to fetch information from the /userinfo endpoint and merge it with
// the existing claims data. A failure to fetch additional information from this
// endpoint will not invalidate the authorization flow.
if userinfo, err := a.provider.UserInfo(oidcCtx, oauth2.StaticTokenSource(oauth2Token)); err == nil {
_ = userinfo.Claims(&allClaims)
} else {
if a.logger != nil {
logFunc := a.logger.Warn
if strings.Contains(err.Error(), "user info endpoint is not supported") {
logFunc = a.logger.Info
}
logFunc("error reading /userinfo endpoint", "error", err)
}
}
if a.config.VerboseOIDCLogging && a.logger != nil {
if c, err := json.Marshal(allClaims); err == nil {
a.logger.Debug("OIDC provider response", "claims", string(c))
} else {
a.logger.Debug("OIDC provider response", "marshalling error", err.Error())
}
}
c, err := a.extractClaims(allClaims)
if err != nil {
return nil, nil, &TokenVerificationFailedError{
Err: err,
}
}
if a.config.VerboseOIDCLogging && a.logger != nil {
a.logger.Debug("OIDC provider response", "extracted_claims", c)
}
return c, state.payload, nil
}
// ProviderLoginFailedError is an error type sometimes returned from
// ClaimsFromAuthCode().
//
// It represents a failure to complete the authorization code workflow with the
// provider such as losing important OIDC parameters or a failure to fetch an
// id_token.
//
// You can check for it with errors.As().
type ProviderLoginFailedError struct {
Err error
}
func (e *ProviderLoginFailedError) Error() string {
return fmt.Sprintf("Provider login failed: %v", e.Err)
}
func (e *ProviderLoginFailedError) Unwrap() error { return e.Err }
// TokenVerificationFailedError is an error type sometimes returned from
// ClaimsFromAuthCode().
//
// It represents a failure to vet the returned OIDC credentials for validity
// such as the id_token not passing verification or using an mismatched nonce.
//
// You can check for it with errors.As().
type TokenVerificationFailedError struct {
Err error
}
func (e *TokenVerificationFailedError) Error() string {
return fmt.Sprintf("Token verification failed: %v", e.Err)
}
func (e *TokenVerificationFailedError) Unwrap() error { return e.Err }
func (a *Authenticator) verifyOIDCToken(ctx context.Context, rawToken string) (map[string]interface{}, error) {
allClaims := make(map[string]interface{})
oidcConfig := &oidc.Config{
SupportedSigningAlgs: a.config.JWTSupportedAlgs,
}
switch a.config.authType() {
case authOIDCFlow:
oidcConfig.ClientID = a.config.OIDCClientID
case authOIDCDiscovery:
oidcConfig.SkipClientIDCheck = true
default:
return nil, fmt.Errorf("unsupported auth type for this verifyOIDCToken: %d", a.config.authType())
}
verifier := a.provider.Verifier(oidcConfig)
idToken, err := verifier.Verify(ctx, rawToken)
if err != nil {
return nil, fmt.Errorf("error validating signature: %v", err)
}
if err := idToken.Claims(&allClaims); err != nil {
return nil, fmt.Errorf("unable to successfully parse all claims from token: %v", err)
}
// TODO(sso): why isn't this strict for OIDC?
if err := validateAudience(a.config.BoundAudiences, idToken.Audience, false); err != nil {
return nil, fmt.Errorf("error validating claims: %v", err)
}
return allClaims, nil
}
// verifyOIDCState tests whether the provided state ID is valid and returns the
// associated state object if so. A nil state is returned if the ID is not found
// or expired. The state should only ever be retrieved once and is deleted as
// part of this request.
func (a *Authenticator) verifyOIDCState(stateID string) *oidcState {
defer a.oidcStates.Delete(stateID)
if stateRaw, ok := a.oidcStates.Get(stateID); ok {
return stateRaw.(*oidcState)
}
return nil
}
// createOIDCState make an expiring state object, associated with a random state ID
// that is passed throughout the OAuth process. A nonce is also included in the
// auth process, and for simplicity will be identical in length/format as the state ID.
func (a *Authenticator) createOIDCState(redirectURI string, payload interface{}) (string, string, error) {
// Get enough bytes for 2 160-bit IDs (per rfc6749#section-10.10)
bytes, err := uuid.GenerateRandomBytes(2 * 20)
if err != nil {
return "", "", err
}
stateID := fmt.Sprintf("%x", bytes[:20])
nonce := fmt.Sprintf("%x", bytes[20:])
a.oidcStates.SetDefault(stateID, &oidcState{
nonce: nonce,
redirectURI: redirectURI,
payload: payload,
})
return stateID, nonce, nil
}
// oidcState is created when an authURL is requested. The state
// identifier is passed throughout the OAuth process.
type oidcState struct {
nonce string
redirectURI string
payload interface{}
}