Add configurable JWT claim headers (#596)

config/options.go

@@ -135,6 +135,9 @@ type Options struct {
 	HeadersEnv string            `yaml:",omitempty"`
 	Headers    map[string]string `yaml:",omitempty"`
 
+	// List of JWT claims to insert as x-pomerium-claim-* headers on proxied requests
+	JWTClaimsHeaders []string `mapstructure:"jwt_claims_headers" yaml:"jwt_claims_headers,omitempty"`
+
 	// RefreshCooldown limits the rate a user can refresh her session
 	RefreshCooldown time.Duration `mapstructure:"refresh_cooldown" yaml:"refresh_cooldown,omitempty"`
 

docs/configuration/readme.md

@@ -674,6 +674,17 @@ Refresh cooldown is the minimum amount of time between allowed manually refreshe
 
 Default Upstream Timeout is the default timeout applied to a proxied route when no `timeout` key is specified by the policy.
 
+### JWT Claim Headers
+- Environmental Variable: `JWT_CLAIMS_HEADERS`
+- Config File Key: `jwt_claims_headers`
+- Type: `string list`
+- Example: `email,groups`, `user`
+- Optional
+  
+Set this option for the pomerium proxy to copy JWT claim information into request headers with the name `x-pomerium-claim-*`.  Any claim listed in the pomerium JWT can be placed into a corresponding header for downstream consumption.  This claim information is sourced from your IDP and pomerium's own session metadata.
+
+Use this option if you previously relied on `x-pomerium-authenticated-user-{email|user-id|groups}` for downstream authN/Z.  
+
 ## Cache Service
 
 The cache service is used for storing user session data.

docs/docs/upgrading.md

@@ -13,6 +13,8 @@ description: >-
 
 User detail headers ( `x-pomerium-authenticated-user-id` / `x-pomerium-authenticated-user-email` / `x-pomerium-authenticated-user-groups`) have been removed in favor of using the more secure, more data rich attestation jwt header (`x-pomerium-jwt-assertion`).
 
+If you still rely on individual claim headers, please see the `jwt_claims_headers` option [here](https://www.pomerium.io/configuration/#jwt-claim-headers).
+
 ### Non-standard port users
 
 Non-standard port users (e.g. those not using `443`/`80` where the port _would_ be part of the client's request) will have to clear their user's session before upgrading. Starting with version v0.7.0, audience (`aud`) and issuer (`iss`) claims will be port specific.

proxy/middleware.go

@@ -155,25 +155,50 @@ func SetResponseHeaders(headers map[string]string) func(next http.Handler) http.
 	}
 }
 
-func (p *Proxy) userDetailsLoggerMiddleware(next http.Handler) http.Handler {
+func (p *Proxy) jwtClaimMiddleware(next http.Handler) http.Handler {
 	return httputil.HandlerFunc(func(w http.ResponseWriter, r *http.Request) error {
 		if jwt, err := sessions.FromContext(r.Context()); err == nil {
-			var s sessions.State
-			if err := p.encoder.Unmarshal([]byte(jwt), &s); err == nil {
+			var jwtClaims map[string]interface{}
+			if err := p.encoder.Unmarshal([]byte(jwt), &jwtClaims); err == nil {
+				formattedJWTClaims := make(map[string]string)
+
+				// reformat claims into something resembling map[string]string
+				for claim, value := range jwtClaims {
+					var formattedClaim string
+					if cv, ok := value.([]interface{}); ok {
+						elements := make([]string, len(cv))
+
+						for i, v := range cv {
+							elements[i] = fmt.Sprintf("%v", v)
+						}
+						formattedClaim = strings.Join(elements, ",")
+					} else {
+						formattedClaim = fmt.Sprintf("%v", value)
+					}
+					formattedJWTClaims[claim] = formattedClaim
+				}
+
+				// log group, email, user claims
 				l := log.Ctx(r.Context())
+				for _, claimName := range []string{"groups", "email", "user"} {
+
 					l.UpdateContext(func(c zerolog.Context) zerolog.Context {
-					return c.Strs("groups", s.Groups)
-				})
-				l.UpdateContext(func(c zerolog.Context) zerolog.Context {
-					return c.Str("email", s.Email)
-				})
-				l.UpdateContext(func(c zerolog.Context) zerolog.Context {
-					return c.Str("user-id", s.User)
+						return c.Str(claimName, fmt.Sprintf("%v", formattedJWTClaims[claimName]))
 					})
+
+				}
+
+				// set headers for any claims specified by config
+				for _, claimName := range p.jwtClaimHeaders {
+					if _, ok := formattedJWTClaims[claimName]; ok {
+
+						headerName := fmt.Sprintf("x-pomerium-claim-%s", claimName)
+						r.Header.Set(headerName, formattedJWTClaims[claimName])
+					}
+				}
 			}
 		}
 		next.ServeHTTP(w, r)
 		return nil
 	})
-
 }

proxy/middleware_test.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/pomerium/pomerium/internal/encoding"
+	"github.com/pomerium/pomerium/internal/encoding/jws"
 	"github.com/pomerium/pomerium/internal/encoding/mock"
 	"github.com/pomerium/pomerium/internal/grpc/authorize"
 	"github.com/pomerium/pomerium/internal/grpc/authorize/client"
@@ -72,15 +73,72 @@ func TestProxy_AuthenticateSession(t *testing.T) {
 			r = r.WithContext(ctx)
 			r.Header.Set("Accept", "application/json")
 			w := httptest.NewRecorder()
-			got := a.userDetailsLoggerMiddleware(a.AuthenticateSession(fn))
+			got := a.jwtClaimMiddleware(a.AuthenticateSession(fn))
 			got.ServeHTTP(w, r)
 			if status := w.Code; status != tt.wantStatus {
 				t.Errorf("AuthenticateSession() error = %v, wantErr %v\n%v", w.Result().StatusCode, tt.wantStatus, w.Body.String())
 			}
+
 		})
 	}
 }
 
+func Test_jwtClaimMiddleware(t *testing.T) {
+	email := "test@pomerium.example"
+	groups := []string{"foo", "bar"}
+	claimHeaders := []string{"email", "groups", "missing"}
+	sharedKey := "80ldlrU2d7w+wVpKNfevk6fmb8otEx6CqOfshj2LwhQ="
+
+	session := &sessions.State{Email: email, Expiry: jwt.NewNumericDate(time.Now().Add(10 * time.Second)), Groups: groups}
+	encoder, _ := jws.NewHS256Signer([]byte(sharedKey), "https://authenticate.pomerium.example")
+	state, err := encoder.Marshal(session)
+
+	if err != nil {
+		t.Errorf("failed to marshal state: %s", err)
+	}
+
+	a := Proxy{
+		SharedKey:       sharedKey,
+		cookieSecret:    []byte("80ldlrU2d7w+wVpKNfevk6fmb8otEx6CqOfshj2LwhQ="),
+		encoder:         encoder,
+		jwtClaimHeaders: claimHeaders,
+	}
+
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	})
+
+	r := httptest.NewRequest(http.MethodGet, "/", nil)
+	ctx := r.Context()
+	ctx = sessions.NewContext(ctx, string(state), nil)
+	r = r.WithContext(ctx)
+	w := httptest.NewRecorder()
+	proxyHandler := a.jwtClaimMiddleware(handler)
+	proxyHandler.ServeHTTP(w, r)
+
+	t.Run("email claim", func(t *testing.T) {
+		emailHeader := r.Header.Get("x-pomerium-claim-email")
+		if emailHeader != email {
+			t.Errorf("did not find claim email, want=%q, got=%q", email, emailHeader)
+		}
+	})
+
+	t.Run("groups claim", func(t *testing.T) {
+		groupsHeader := r.Header.Get("x-pomerium-claim-groups")
+		if groupsHeader != strings.Join(groups, ",") {
+			t.Errorf("did not find claim groups, want=%q, got=%q", groups, groupsHeader)
+		}
+	})
+
+	t.Run("missing claim", func(t *testing.T) {
+		absentHeader := r.Header.Get("x-pomerium-claim-missing")
+		if absentHeader != "" {
+			t.Errorf("found claim that should not exist, got=%q", absentHeader)
+		}
+	})
+
+}
+
 func TestProxy_AuthorizeSession(t *testing.T) {
 	t.Parallel()
 	fn := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

proxy/proxy.go

@@ -90,6 +90,7 @@ type Proxy struct {
 	sessionStore           sessions.SessionStore
 	sessionLoaders         []sessions.SessionLoader
 	templates              *template.Template
+	jwtClaimHeaders        []string
 }
 
 // New takes a Proxy service from options and a validation function.
@@ -136,6 +137,7 @@ func New(opts config.Options) (*Proxy, error) {
 			header.NewStore(encoder, "Pomerium"),
 			queryparam.NewStore(encoder, "pomerium_session")},
 		templates:       template.Must(frontend.NewTemplates()),
+		jwtClaimHeaders: opts.JWTClaimsHeaders,
 	}
 	// errors checked in ValidateOptions
 	p.authorizeURL, _ = urlutil.DeepCopy(opts.AuthorizeURL)
@@ -269,8 +271,8 @@ func (p *Proxy) reverseProxyHandler(r *mux.Router, policy config.Policy) *mux.Ro
 	rp.Use(p.AuthorizeSession)
 	// 7. Strip the user session cookie from the downstream request
 	rp.Use(middleware.StripCookie(p.cookieOptions.Name))
-	// 8 . Add user details to the request logger context
-	rp.Use(p.userDetailsLoggerMiddleware)
+	// 8 . Add claim details to the request logger context and headers
+	rp.Use(p.jwtClaimMiddleware)
 
 	return r
 }