feat(auth): OIDC/Keycloak SSO-Login (additiv) — v1.2.91

SSO per OpenID Connect (Authorization Code + PKCE) zusätzlich zum lokalen Login. - Regeln: kein Auto-Provisioning (E-Mail muss als User existieren), Rolle aus DB (nie aus Token), lokaler Login+TOTP unangetastet. - Migration 0040: oidc_settings (Singleton, client_secret_enc via secrets.Box) + users.oidc_subject. - internal/services/oidc: Settings-Repo (write-only Secret) + lazy go-oidc Client (testbarer Authenticator-Seam). - internal/handlers/oidc.go: GET/PUT /oidc/settings (admin), GET /auth/oidc/{settings,login,callback}. Flow-State (state/PKCE/nonce) stateless im 5-min signierten HttpOnly-Cookie (SameSite=Lax). email_verified erzwungen, opportunistisches sub-Linking, Session via setSessionCookie+Signer. - session.SignBlob/VerifyBlob; users.Get/SetOIDCSubject; main.go-Wiring. - Frontend: App.tsx /auth/me-Bootstrap (für Cookie-Session nach Callback), Login-SSO-Button + sso_error, Settings OIDC-Card, i18n de/en. - Tests (guarded EG_FWTEST_DSN): Secret-Roundtrip + Callback (Rolle-aus-DB, no_account, disabled, unverified, nonce, state). Deps: go-oidc/v3, x/oauth2. Scope v1: nur Login (kein SLO/Refresh). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-05 16:04:13 +02:00
parent f85552a475
commit 3a707e2e3f
18 changed files with 1326 additions and 8 deletions
--- a/internal/services/oidc/client.go
+++ b/internal/services/oidc/client.go
@@ -0,0 +1,181 @@
+package oidc
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"strings"
+	"sync"
+
+	gooidc "github.com/coreos/go-oidc/v3/oidc"
+	"golang.org/x/oauth2"
+)
+
+// Claims sind die aus dem ID-Token extrahierten Felder, die der Login-
+// Flow braucht. Bewusst minimal — Rolle kommt NIE aus dem Token.
+type Claims struct {
+	Subject       string
+	Email         string
+	EmailVerified bool
+	Nonce         string
+}
+
+// Authenticator ist der testbare Seam: Aufbau der Auth-URL und der
+// Code-Exchange inkl. ID-Token-Verifikation + Claim-Extraktion. Der
+// Handler hängt nur hieran, sodass Tests einen Fake injizieren können.
+type Authenticator interface {
+	// AuthCodeURL baut die Redirect-URL zum IdP (state + nonce + PKCE-Challenge).
+	AuthCodeURL(ctx context.Context, redirectURI, state, nonce, pkceVerifier string) (string, error)
+	// Exchange tauscht den Code (PKCE), verifiziert das ID-Token und gibt
+	// die Claims zurück. Prüft Issuer/Audience/Signatur/Expiry.
+	Exchange(ctx context.Context, redirectURI, code, pkceVerifier string) (*Claims, error)
+}
+
+// Client implementiert Authenticator gegen einen echten OIDC-Provider.
+// Provider+Verifier werden lazy aufgebaut und gecached; bei geänderten
+// Settings (Fingerprint) neu aufgebaut.
+type Client struct {
+	repo *Repo
+
+	mu       sync.Mutex
+	cacheKey string
+	provider *gooidc.Provider
+	verifier *gooidc.IDTokenVerifier
+}
+
+func NewClient(repo *Repo) *Client { return &Client{repo: repo} }
+
+// loaded baut (oder reused) Provider+Verifier aus den aktuellen Settings.
+// Cache-Key = Fingerprint(issuer, client_id, scopes); Rebuild bei Änderung.
+func (c *Client) loaded(ctx context.Context) (*gooidc.Provider, *gooidc.IDTokenVerifier, error) {
+	s, err := c.repo.Get(ctx)
+	if err != nil {
+		return nil, nil, err
+	}
+	if !s.Enabled {
+		return nil, nil, ErrDisabled
+	}
+	if strings.TrimSpace(s.IssuerURL) == "" || strings.TrimSpace(s.ClientID) == "" {
+		return nil, nil, fmt.Errorf("oidc: issuer_url and client_id required")
+	}
+	key := fingerprint(s.IssuerURL, s.ClientID, s.Scopes)
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.provider == nil || c.cacheKey != key {
+		prov, err := gooidc.NewProvider(ctx, s.IssuerURL)
+		if err != nil {
+			return nil, nil, fmt.Errorf("oidc: discovery: %w", err)
+		}
+		c.provider = prov
+		c.verifier = prov.Verifier(&gooidc.Config{ClientID: s.ClientID})
+		c.cacheKey = key
+	}
+	return c.provider, c.verifier, nil
+}
+
+func (c *Client) oauthConfig(prov *gooidc.Provider, clientID, secret, redirectURI, scopes string) oauth2.Config {
+	return oauth2.Config{
+		ClientID:     clientID,
+		ClientSecret: secret,
+		Endpoint:     prov.Endpoint(),
+		RedirectURL:  redirectURI,
+		Scopes:       splitScopes(scopes),
+	}
+}
+
+// AuthCodeURL implementiert Authenticator.
+func (c *Client) AuthCodeURL(ctx context.Context, redirectURI, state, nonce, pkceVerifier string) (string, error) {
+	s, err := c.repo.Get(ctx)
+	if err != nil {
+		return "", err
+	}
+	prov, _, err := c.loaded(ctx)
+	if err != nil {
+		return "", err
+	}
+	secret, _ := c.repo.ClientSecret(ctx)
+	cfg := c.oauthConfig(prov, s.ClientID, secret, redirectURI, s.Scopes)
+	return cfg.AuthCodeURL(state,
+		gooidc.Nonce(nonce),
+		oauth2.S256ChallengeOption(pkceVerifier),
+	), nil
+}
+
+// Exchange implementiert Authenticator.
+func (c *Client) Exchange(ctx context.Context, redirectURI, code, pkceVerifier string) (*Claims, error) {
+	s, err := c.repo.Get(ctx)
+	if err != nil {
+		return nil, err
+	}
+	prov, verifier, err := c.loaded(ctx)
+	if err != nil {
+		return nil, err
+	}
+	secret, _ := c.repo.ClientSecret(ctx)
+	cfg := c.oauthConfig(prov, s.ClientID, secret, redirectURI, s.Scopes)
+
+	tok, err := cfg.Exchange(ctx, code, oauth2.VerifierOption(pkceVerifier))
+	if err != nil {
+		return nil, fmt.Errorf("oidc: code exchange: %w", err)
+	}
+	rawID, ok := tok.Extra("id_token").(string)
+	if !ok || rawID == "" {
+		return nil, errors.New("oidc: no id_token in response")
+	}
+	idToken, err := verifier.Verify(ctx, rawID)
+	if err != nil {
+		return nil, fmt.Errorf("oidc: id_token verify: %w", err)
+	}
+	return extractClaims(idToken, s.EmailClaim)
+}
+
+// extractClaims liest E-Mail (via konfigurierbarem Claim), email_verified,
+// sub und nonce aus dem verifizierten ID-Token.
+func extractClaims(idToken *gooidc.IDToken, emailClaim string) (*Claims, error) {
+	var raw map[string]any
+	if err := idToken.Claims(&raw); err != nil {
+		return nil, fmt.Errorf("oidc: decode claims: %w", err)
+	}
+	if emailClaim == "" {
+		emailClaim = "email"
+	}
+	out := &Claims{Subject: idToken.Subject}
+	if v, ok := raw[emailClaim].(string); ok {
+		out.Email = strings.TrimSpace(strings.ToLower(v))
+	}
+	// email_verified kann bool oder "true"/"false" sein.
+	switch ev := raw["email_verified"].(type) {
+	case bool:
+		out.EmailVerified = ev
+	case string:
+		out.EmailVerified = ev == "true"
+	}
+	if n, ok := raw["nonce"].(string); ok {
+		out.Nonce = n
+	}
+	return out, nil
+}
+
+func splitScopes(s string) []string {
+	out := []string{}
+	for _, p := range strings.Fields(s) {
+		if p != "" {
+			out = append(out, p)
+		}
+	}
+	if len(out) == 0 {
+		out = []string{gooidc.ScopeOpenID, "email", "profile"}
+	}
+	return out
+}
+
+func fingerprint(parts ...string) string {
+	h := sha256.New()
+	for _, p := range parts {
+		h.Write([]byte(p))
+		h.Write([]byte{0})
+	}
+	return hex.EncodeToString(h.Sum(nil))
+}