More unit tests for dynamic clients

- Add dynamic client unit tests for the upstream OIDC callback and
  POST login endpoints.
- Enhance a few log statements to print the full fosite error messages
  into the logs where they were previously only printing the name of
  the error type.

internal/oidc/auth/auth_handler_test.go

@@ -25,7 +25,6 @@ import (
 	"k8s.io/apiserver/pkg/authentication/user"
 	"k8s.io/client-go/kubernetes/fake"
 	v1 "k8s.io/client-go/kubernetes/typed/core/v1"
-	kubetesting "k8s.io/client-go/testing"
 	"k8s.io/utils/pointer"
 
 	supervisorfake "go.pinniped.dev/generated/latest/client/supervisor/clientset/versioned/fake"
@@ -3088,7 +3087,7 @@ func TestAuthorizationEndpoint(t *testing.T) {
 			// OIDC validations are checked in fosite after the OAuth authcode (and sometimes the OIDC session)
 			// is stored, so it is possible with an LDAP upstream to store objects and then return an error to
 			// the client anyway (which makes the stored objects useless, but oh well).
-			require.Len(t, filterActions(kubeClient.Actions()), test.wantUnnecessaryStoredRecords)
+			require.Len(t, oidctestutil.FilterClientSecretCreateActions(kubeClient.Actions()), test.wantUnnecessaryStoredRecords)
 		case test.wantRedirectLocationRegexp != "":
 			if test.wantDownstreamClientID == "" {
 				test.wantDownstreamClientID = pinnipedCLIClientID // default assertion value when not provided by test case
@@ -3301,20 +3300,3 @@ func requireEqualURLs(t *testing.T, actualURL string, expectedURL string, ignore
 	}
 	require.Equal(t, expectedLocationQuery, actualLocationQuery)
 }
-
-// filterActions ignores any reads made to get a storage secret corresponding to an OIDCClient, since these
-// are normal actions when the request is using a dynamic client's client_id, and we don't need to make assertions
-// about these Secrets since they are not related to session storage.
-func filterActions(actions []kubetesting.Action) []kubetesting.Action {
-	filtered := make([]kubetesting.Action, 0, len(actions))
-	for _, action := range actions {
-		if action.Matches("get", "secrets") {
-			getAction := action.(kubetesting.GetAction)
-			if strings.HasPrefix(getAction.GetName(), "pinniped-storage-oidc-client-secret-") {
-				continue // filter out OIDCClient's storage secret reads
-			}
-		}
-		filtered = append(filtered, action) // otherwise include the action
-	}
-	return filtered
-}

internal/oidc/callback/callback_handler.go

@@ -48,7 +48,8 @@ func NewHandler(
 		reconstitutedAuthRequest := &http.Request{Form: downstreamAuthParams}
 		authorizeRequester, err := oauthHelper.NewAuthorizeRequest(r.Context(), reconstitutedAuthRequest)
 		if err != nil {
-			plog.Error("error using state downstream auth params", err)
+			plog.Error("error using state downstream auth params", err,
+				"fositeErr", oidc.FositeErrorForLog(err))
 			return httperr.New(http.StatusBadRequest, "error using state downstream auth params")
 		}
 
@@ -83,7 +84,8 @@ func NewHandler(
 
 		authorizeResponder, err := oauthHelper.NewAuthorizeResponse(r.Context(), authorizeRequester, openIDSession)
 		if err != nil {
-			plog.WarningErr("error while generating and saving authcode", err, "upstreamName", upstreamIDPConfig.GetName())
+			plog.WarningErr("error while generating and saving authcode", err,
+				"upstreamName", upstreamIDPConfig.GetName(), "fositeErr", oidc.FositeErrorForLog(err))
 			return httperr.Wrap(http.StatusInternalServerError, "error while generating and saving authcode", err)
 		}
 

internal/oidc/callback/callback_handler_test.go

@@ -54,7 +54,9 @@ const (
 
 	downstreamIssuer              = "https://my-downstream-issuer.com/path"
 	downstreamRedirectURI         = "http://127.0.0.1/callback"
-	downstreamClientID            = "pinniped-cli"
+	downstreamPinnipedClientID    = "pinniped-cli"
+	downstreamDynamicClientID     = "client.oauth.pinniped.dev-test-name"
+	downstreamDynamicClientUID    = "fake-client-uid"
 	downstreamNonce               = "some-nonce-value"
 	downstreamPKCEChallenge       = "some-challenge"
 	downstreamPKCEChallengeMethod = "S256"
@@ -70,14 +72,19 @@ var (
 	happyDownstreamRequestParamsQuery = url.Values{
 		"response_type":         []string{"code"},
 		"scope":                 []string{strings.Join(happyDownstreamScopesRequested, " ")},
-		"client_id":             []string{downstreamClientID},
+		"client_id":             []string{downstreamPinnipedClientID},
 		"state":                 []string{happyDownstreamState},
 		"nonce":                 []string{downstreamNonce},
 		"code_challenge":        []string{downstreamPKCEChallenge},
 		"code_challenge_method": []string{downstreamPKCEChallengeMethod},
 		"redirect_uri":          []string{downstreamRedirectURI},
 	}
-	happyDownstreamRequestParams     = happyDownstreamRequestParamsQuery.Encode()
+	happyDownstreamRequestParams = happyDownstreamRequestParamsQuery.Encode()
+
+	happyDownstreamRequestParamsForDynamicClient = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
+		map[string]string{"client_id": downstreamDynamicClientID},
+	).Encode()
+
 	happyDownstreamCustomSessionData = &psession.CustomSessionData{
 		ProviderUID:  happyUpstreamIDPResourceUID,
 		ProviderName: happyUpstreamIDPName,
@@ -122,6 +129,7 @@ func TestCallbackEndpoint(t *testing.T) {
 	happyCookieCodec.SetSerializer(securecookie.JSONEncoder{})
 
 	happyState := happyUpstreamStateParam().Build(t, happyStateCodec)
+	happyStateForDynamicClient := happyUpstreamStateParamForDynamicClient().Build(t, happyStateCodec)
 
 	encodedIncomingCookieCSRFValue, err := happyCookieCodec.Encode("csrf", happyDownstreamCSRF)
 	require.NoError(t, err)
@@ -137,6 +145,13 @@ func TestCallbackEndpoint(t *testing.T) {
 	// Note that fosite puts the granted scopes as a param in the redirect URI even though the spec doesn't seem to require it
 	happyDownstreamRedirectLocationRegexp := downstreamRedirectURI + `\?code=([^&]+)&scope=openid\+groups&state=` + happyDownstreamState
 
+	addFullyCapableDynamicClientAndSecretToKubeResources := func(t *testing.T, supervisorClient *supervisorfake.Clientset, kubeClient *fake.Clientset) {
+		oidcClient, secret := testutil.FullyCapableOIDCClientAndStorageSecret(t,
+			"some-namespace", downstreamDynamicClientID, downstreamDynamicClientUID, downstreamRedirectURI, []string{testutil.HashedPassword1AtGoMinCost})
+		require.NoError(t, supervisorClient.Tracker().Add(oidcClient))
+		require.NoError(t, kubeClient.Tracker().Add(secret))
+	}
+
 	tests := []struct {
 		name string
 
@@ -157,6 +172,7 @@ func TestCallbackEndpoint(t *testing.T) {
 		wantDownstreamIDTokenGroups       []string
 		wantDownstreamRequestedScopes     []string
 		wantDownstreamNonce               string
+		wantDownstreamClientID            string
 		wantDownstreamPKCEChallenge       string
 		wantDownstreamPKCEChallengeMethod string
 		wantDownstreamCustomSessionData   *psession.CustomSessionData
@@ -185,6 +201,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -208,6 +225,32 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
+			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
+			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
+			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
+			wantAuthcodeExchangeCall: &expectedAuthcodeExchange{
+				performedByUpstreamName: happyUpstreamIDPName,
+				args:                    happyExchangeAndValidateTokensArgs,
+			},
+		},
+		{
+			name:                              "GET with good state and cookie and successful upstream token exchange returns 303 to downstream client callback with its state and code when using dynamic client",
+			idps:                              oidctestutil.NewUpstreamIDPListerBuilder().WithOIDC(happyUpstream().Build()),
+			kubeResources:                     addFullyCapableDynamicClientAndSecretToKubeResources,
+			method:                            http.MethodGet,
+			path:                              newRequestPath().WithState(happyStateForDynamicClient).String(),
+			csrfCookie:                        happyCSRFCookie,
+			wantStatus:                        http.StatusSeeOther,
+			wantRedirectLocationRegexp:        happyDownstreamRedirectLocationRegexp,
+			wantBody:                          "",
+			wantDownstreamIDTokenSubject:      oidcUpstreamIssuer + "?sub=" + oidcUpstreamSubjectQueryEscaped,
+			wantDownstreamIDTokenUsername:     oidcUpstreamUsername,
+			wantDownstreamIDTokenGroups:       oidcUpstreamGroupMembership,
+			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
+			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
+			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamDynamicClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -231,6 +274,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamAccessTokenCustomSessionData,
@@ -263,6 +307,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamRequestedScopes:     []string{"openid"},
 			wantDownstreamGrantedScopes:       []string{"openid"},
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -286,6 +331,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData: &psession.CustomSessionData{
@@ -321,6 +367,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -346,6 +393,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -373,6 +421,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -401,6 +450,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -531,6 +581,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -556,6 +607,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -581,6 +633,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -714,6 +767,42 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantContentType: htmlContentType,
 			wantBody:        "Bad Request: error using state downstream auth params\n",
 		},
+		{
+			name:   "state's downstream auth params have invalid client_id",
+			idps:   oidctestutil.NewUpstreamIDPListerBuilder().WithOIDC(happyUpstream().Build()),
+			method: http.MethodGet,
+			path: newRequestPath().WithState(
+				happyUpstreamStateParam().
+					WithAuthorizeRequestParams(shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery, map[string]string{"client_id": "bogus"}).Encode()).
+					Build(t, happyStateCodec),
+			).String(),
+			csrfCookie:      happyCSRFCookie,
+			wantStatus:      http.StatusBadRequest,
+			wantContentType: htmlContentType,
+			wantBody:        "Bad Request: error using state downstream auth params\n",
+		},
+		{
+			name:          "dynamic clients do not allow response_mode=form_post",
+			idps:          oidctestutil.NewUpstreamIDPListerBuilder().WithOIDC(happyUpstream().Build()),
+			kubeResources: addFullyCapableDynamicClientAndSecretToKubeResources,
+			method:        http.MethodGet,
+			path: newRequestPath().WithState(
+				happyUpstreamStateParam().WithAuthorizeRequestParams(
+					shallowCopyAndModifyQuery(
+						happyDownstreamRequestParamsQuery,
+						map[string]string{
+							"client_id":     downstreamDynamicClientID,
+							"response_mode": "form_post",
+							"scope":         "openid",
+						},
+					).Encode(),
+				).Build(t, happyStateCodec),
+			).String(),
+			csrfCookie:      happyCSRFCookie,
+			wantStatus:      http.StatusBadRequest,
+			wantContentType: htmlContentType,
+			wantBody:        "Bad Request: error using state downstream auth params\n",
+		},
 		{
 			name:   "state's downstream auth params does not contain openid scope",
 			idps:   oidctestutil.NewUpstreamIDPListerBuilder().WithOIDC(happyUpstream().Build()),
@@ -733,6 +822,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamGrantedScopes:       []string{"groups"},
 			wantDownstreamIDTokenGroups:       oidcUpstreamGroupMembership,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -759,6 +849,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamRequestedScopes:     []string{"profile", "email"},
 			wantDownstreamGrantedScopes:       []string{},
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -786,6 +877,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamGrantedScopes:       []string{"openid", "offline_access", "groups"},
 			wantDownstreamIDTokenGroups:       oidcUpstreamGroupMembership,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -884,6 +976,7 @@ func TestCallbackEndpoint(t *testing.T) {
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamIDTokenGroups:       []string{},
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClientID:            downstreamPinnipedClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   happyDownstreamCustomSessionData,
@@ -1139,7 +1232,7 @@ func TestCallbackEndpoint(t *testing.T) {
 					test.wantDownstreamPKCEChallenge,
 					test.wantDownstreamPKCEChallengeMethod,
 					test.wantDownstreamNonce,
-					downstreamClientID,
+					test.wantDownstreamClientID,
 					downstreamRedirectURI,
 					test.wantDownstreamCustomSessionData,
 				)
@@ -1166,7 +1259,7 @@ func TestCallbackEndpoint(t *testing.T) {
 					test.wantDownstreamPKCEChallenge,
 					test.wantDownstreamPKCEChallengeMethod,
 					test.wantDownstreamNonce,
-					downstreamClientID,
+					test.wantDownstreamClientID,
 					downstreamRedirectURI,
 					test.wantDownstreamCustomSessionData,
 				)
@@ -1237,6 +1330,12 @@ func happyUpstreamStateParam() *oidctestutil.UpstreamStateParamBuilder {
 	}
 }
 
+func happyUpstreamStateParamForDynamicClient() *oidctestutil.UpstreamStateParamBuilder {
+	p := happyUpstreamStateParam()
+	p.P = happyDownstreamRequestParamsForDynamicClient
+	return p
+}
+
 func happyUpstream() *oidctestutil.TestUpstreamOIDCIdentityProviderBuilder {
 	return oidctestutil.NewTestUpstreamOIDCIdentityProviderBuilder().
 		WithName(happyUpstreamIDPName).

internal/oidc/login/post_login_handler.go

@@ -41,7 +41,8 @@ func NewPostHandler(issuerURL string, upstreamIDPs oidc.UpstreamIdentityProvider
 		if err != nil {
 			// This shouldn't really happen because the authorization endpoint has already validated these params
 			// by calling NewAuthorizeRequest() itself.
-			plog.Error("error using state downstream auth params", err)
+			plog.Error("error using state downstream auth params", err,
+				"fositeErr", oidc.FositeErrorForLog(err))
 			return httperr.New(http.StatusBadRequest, "error using state downstream auth params")
 		}
 

internal/oidc/login/post_login_handler_test.go

@@ -38,7 +38,9 @@ func TestPostLoginEndpoint(t *testing.T) {
 
 		downstreamIssuer              = "https://my-downstream-issuer.com/path"
 		downstreamRedirectURI         = "http://127.0.0.1/callback"
-		downstreamClientID            = "pinniped-cli"
+		downstreamPinnipedCLIClientID = "pinniped-cli"
+		downstreamDynamicClientID     = "client.oauth.pinniped.dev-test-name"
+		downstreamDynamicClientUID    = "fake-client-uid"
 		happyDownstreamState          = "8b-state"
 		downstreamNonce               = "some-nonce-value"
 		downstreamPKCEChallenge       = "some-challenge"
@@ -90,7 +92,7 @@ func TestPostLoginEndpoint(t *testing.T) {
 	happyDownstreamRequestParamsQuery := url.Values{
 		"response_type":         []string{"code"},
 		"scope":                 []string{strings.Join(happyDownstreamScopesRequested, " ")},
-		"client_id":             []string{downstreamClientID},
+		"client_id":             []string{downstreamPinnipedCLIClientID},
 		"state":                 []string{happyDownstreamState},
 		"nonce":                 []string{downstreamNonce},
 		"code_challenge":        []string{downstreamPKCEChallenge},
@@ -99,14 +101,10 @@ func TestPostLoginEndpoint(t *testing.T) {
 	}
 	happyDownstreamRequestParams := happyDownstreamRequestParamsQuery.Encode()
 
-	copyOfHappyDownstreamRequestParamsQuery := func() url.Values {
+	happyDownstreamRequestParamsQueryForDynamicClient := shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-		params := url.Values{}
+		map[string]string{"client_id": downstreamDynamicClientID},
-		for k, v := range happyDownstreamRequestParamsQuery {
+	)
-			params[k] = make([]string, len(v))
+	happyDownstreamRequestParamsForDynamicClient := happyDownstreamRequestParamsQueryForDynamicClient.Encode()
-			copy(params[k], v)
-		}
-		return params
-	}
 
 	happyLDAPDecodedState := &oidc.UpstreamStateParamData{
 		AuthParams:    happyDownstreamRequestParams,
@@ -124,15 +122,20 @@ func TestPostLoginEndpoint(t *testing.T) {
 		return &copyOfHappyLDAPDecodedState
 	}
 
-	happyActiveDirectoryDecodedState := &oidc.UpstreamStateParamData{
+	happyLDAPDecodedStateForDynamicClient := modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-		AuthParams:    happyDownstreamRequestParams,
+		data.AuthParams = happyDownstreamRequestParamsForDynamicClient
-		UpstreamName:  activeDirectoryUpstreamName,
+	})
-		UpstreamType:  activeDirectoryUpstreamType,
+
-		Nonce:         happyDownstreamNonce,
+	happyActiveDirectoryDecodedState := modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-		CSRFToken:     happyDownstreamCSRF,
+		data.UpstreamName = activeDirectoryUpstreamName
-		PKCECode:      happyDownstreamPKCE,
+		data.UpstreamType = activeDirectoryUpstreamType
-		FormatVersion: happyDownstreamStateVersion,
+	})
-	}
+
+	happyActiveDirectoryDecodedStateForDynamicClient := modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
+		data.AuthParams = happyDownstreamRequestParamsForDynamicClient
+		data.UpstreamName = activeDirectoryUpstreamName
+		data.UpstreamType = activeDirectoryUpstreamType
+	})
 
 	happyLDAPUsername := "some-ldap-user"
 	happyLDAPUsernameFromAuthenticator := "some-mapped-ldap-username"
@@ -232,6 +235,13 @@ func TestPostLoginEndpoint(t *testing.T) {
 		return urlToReturn
 	}
 
+	addFullyCapableDynamicClientAndSecretToKubeResources := func(t *testing.T, supervisorClient *supervisorfake.Clientset, kubeClient *fake.Clientset) {
+		oidcClient, secret := testutil.FullyCapableOIDCClientAndStorageSecret(t,
+			"some-namespace", downstreamDynamicClientID, downstreamDynamicClientUID, downstreamRedirectURI, []string{testutil.HashedPassword1AtGoMinCost})
+		require.NoError(t, supervisorClient.Tracker().Add(oidcClient))
+		require.NoError(t, kubeClient.Tracker().Add(secret))
+	}
+
 	tests := []struct {
 		name          string
 		idps          *oidctestutil.UpstreamIDPListerBuilder
@@ -262,6 +272,7 @@ func TestPostLoginEndpoint(t *testing.T) {
 		wantDownstreamPKCEChallenge       string
 		wantDownstreamPKCEChallengeMethod string
 		wantDownstreamNonce               string
+		wantDownstreamClient              string
 		wantDownstreamCustomSessionData   *psession.CustomSessionData
 
 		// Authorization requests for either a successful OIDC upstream or for an error with any upstream
@@ -289,6 +300,31 @@ func TestPostLoginEndpoint(t *testing.T) {
 			wantDownstreamRedirectURI:         downstreamRedirectURI,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClient:              downstreamPinnipedCLIClientID,
+			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
+			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
+			wantDownstreamCustomSessionData:   expectedHappyLDAPUpstreamCustomSession,
+		},
+		{
+			name: "happy LDAP login with dynamic client",
+			idps: oidctestutil.NewUpstreamIDPListerBuilder().
+				WithLDAP(&upstreamLDAPIdentityProvider). // should pick this one
+				WithActiveDirectory(&erroringUpstreamLDAPIdentityProvider),
+			kubeResources:                     addFullyCapableDynamicClientAndSecretToKubeResources,
+			decodedState:                      happyLDAPDecodedStateForDynamicClient,
+			formParams:                        happyUsernamePasswordFormParams,
+			wantStatus:                        http.StatusSeeOther,
+			wantContentType:                   htmlContentType,
+			wantBodyString:                    "",
+			wantRedirectLocationRegexp:        happyAuthcodeDownstreamRedirectLocationRegexp,
+			wantDownstreamIDTokenSubject:      upstreamLDAPURL + "&sub=" + happyLDAPUID,
+			wantDownstreamIDTokenUsername:     happyLDAPUsernameFromAuthenticator,
+			wantDownstreamIDTokenGroups:       happyLDAPGroups,
+			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
+			wantDownstreamRedirectURI:         downstreamRedirectURI,
+			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
+			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClient:              downstreamDynamicClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   expectedHappyLDAPUpstreamCustomSession,
@@ -311,6 +347,31 @@ func TestPostLoginEndpoint(t *testing.T) {
 			wantDownstreamRedirectURI:         downstreamRedirectURI,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClient:              downstreamPinnipedCLIClientID,
+			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
+			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
+			wantDownstreamCustomSessionData:   expectedHappyActiveDirectoryUpstreamCustomSession,
+		},
+		{
+			name: "happy AD login with dynamic client",
+			idps: oidctestutil.NewUpstreamIDPListerBuilder().
+				WithLDAP(&erroringUpstreamLDAPIdentityProvider).
+				WithActiveDirectory(&upstreamActiveDirectoryIdentityProvider), // should pick this one
+			kubeResources:                     addFullyCapableDynamicClientAndSecretToKubeResources,
+			decodedState:                      happyActiveDirectoryDecodedStateForDynamicClient,
+			formParams:                        happyUsernamePasswordFormParams,
+			wantStatus:                        http.StatusSeeOther,
+			wantContentType:                   htmlContentType,
+			wantBodyString:                    "",
+			wantRedirectLocationRegexp:        happyAuthcodeDownstreamRedirectLocationRegexp,
+			wantDownstreamIDTokenSubject:      upstreamLDAPURL + "&sub=" + happyLDAPUID,
+			wantDownstreamIDTokenUsername:     happyLDAPUsernameFromAuthenticator,
+			wantDownstreamIDTokenGroups:       happyLDAPGroups,
+			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
+			wantDownstreamRedirectURI:         downstreamRedirectURI,
+			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
+			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClient:              downstreamDynamicClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   expectedHappyActiveDirectoryUpstreamCustomSession,
@@ -319,9 +380,9 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "happy LDAP login when downstream response_mode=form_post returns 200 with HTML+JS form",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				query["response_mode"] = []string{"form_post"}
+					map[string]string{"response_mode": "form_post"},
-				data.AuthParams = query.Encode()
+				).Encode()
 			}),
 			formParams:      happyUsernamePasswordFormParams,
 			wantStatus:      http.StatusOK,
@@ -335,6 +396,7 @@ func TestPostLoginEndpoint(t *testing.T) {
 			wantDownstreamRedirectURI:         downstreamRedirectURI,
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClient:              downstreamPinnipedCLIClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   expectedHappyLDAPUpstreamCustomSession,
@@ -343,9 +405,9 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "happy LDAP login when downstream redirect uri matches what is configured for client except for the port number",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				query["redirect_uri"] = []string{"http://127.0.0.1:4242/callback"}
+					map[string]string{"redirect_uri": "http://127.0.0.1:4242/callback"},
-				data.AuthParams = query.Encode()
+				).Encode()
 			}),
 			formParams:                        happyUsernamePasswordFormParams,
 			wantStatus:                        http.StatusSeeOther,
@@ -359,6 +421,33 @@ func TestPostLoginEndpoint(t *testing.T) {
 			wantDownstreamRedirectURI:         "http://127.0.0.1:4242/callback",
 			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClient:              downstreamPinnipedCLIClientID,
+			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
+			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
+			wantDownstreamCustomSessionData:   expectedHappyLDAPUpstreamCustomSession,
+		},
+		{
+			name:          "happy LDAP login when downstream redirect uri matches what is configured for client except for the port number with dynamic client",
+			idps:          oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
+			kubeResources: addFullyCapableDynamicClientAndSecretToKubeResources,
+			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQueryForDynamicClient,
+					map[string]string{"redirect_uri": "http://127.0.0.1:4242/callback"},
+				).Encode()
+			}),
+			formParams:                        happyUsernamePasswordFormParams,
+			wantStatus:                        http.StatusSeeOther,
+			wantContentType:                   htmlContentType,
+			wantBodyString:                    "",
+			wantRedirectLocationRegexp:        "http://127.0.0.1:4242/callback" + `\?code=([^&]+)&scope=openid\+groups&state=` + happyDownstreamState,
+			wantDownstreamIDTokenSubject:      upstreamLDAPURL + "&sub=" + happyLDAPUID,
+			wantDownstreamIDTokenUsername:     happyLDAPUsernameFromAuthenticator,
+			wantDownstreamIDTokenGroups:       happyLDAPGroups,
+			wantDownstreamRequestedScopes:     happyDownstreamScopesRequested,
+			wantDownstreamRedirectURI:         "http://127.0.0.1:4242/callback",
+			wantDownstreamGrantedScopes:       happyDownstreamScopesGranted,
+			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClient:              downstreamDynamicClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   expectedHappyLDAPUpstreamCustomSession,
@@ -367,9 +456,9 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "happy LDAP login when there are additional allowed downstream requested scopes",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				query["scope"] = []string{"openid offline_access pinniped:request-audience"}
+					map[string]string{"scope": "openid offline_access pinniped:request-audience"},
-				data.AuthParams = query.Encode()
+				).Encode()
 			}),
 			formParams:                        happyUsernamePasswordFormParams,
 			wantStatus:                        http.StatusSeeOther,
@@ -383,6 +472,33 @@ func TestPostLoginEndpoint(t *testing.T) {
 			wantDownstreamRedirectURI:         downstreamRedirectURI,
 			wantDownstreamGrantedScopes:       []string{"openid", "offline_access", "pinniped:request-audience"},
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClient:              downstreamPinnipedCLIClientID,
+			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
+			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
+			wantDownstreamCustomSessionData:   expectedHappyLDAPUpstreamCustomSession,
+		},
+		{
+			name:          "happy LDAP login when there are additional allowed downstream requested scopes with dynamic client",
+			idps:          oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
+			kubeResources: addFullyCapableDynamicClientAndSecretToKubeResources,
+			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQueryForDynamicClient,
+					map[string]string{"scope": "openid offline_access pinniped:request-audience"},
+				).Encode()
+			}),
+			formParams:                        happyUsernamePasswordFormParams,
+			wantStatus:                        http.StatusSeeOther,
+			wantContentType:                   htmlContentType,
+			wantBodyString:                    "",
+			wantRedirectLocationRegexp:        downstreamRedirectURI + `\?code=([^&]+)&scope=openid\+offline_access\+pinniped%3Arequest-audience&state=` + happyDownstreamState,
+			wantDownstreamIDTokenSubject:      upstreamLDAPURL + "&sub=" + happyLDAPUID,
+			wantDownstreamIDTokenUsername:     happyLDAPUsernameFromAuthenticator,
+			wantDownstreamIDTokenGroups:       happyLDAPGroups,
+			wantDownstreamRequestedScopes:     []string{"openid", "offline_access", "pinniped:request-audience"},
+			wantDownstreamRedirectURI:         downstreamRedirectURI,
+			wantDownstreamGrantedScopes:       []string{"openid", "offline_access", "pinniped:request-audience"},
+			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClient:              downstreamDynamicClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   expectedHappyLDAPUpstreamCustomSession,
@@ -391,11 +507,13 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "happy LDAP when downstream OIDC validations are skipped because the openid scope was not requested",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				query["scope"] = []string{"email"}
+					map[string]string{
-				// The following prompt value is illegal when openid is requested, but note that openid is not requested.
+						"scope": "email",
-				query["prompt"] = []string{"none login"}
+						// The following prompt value is illegal when openid is requested, but note that openid is not requested.
-				data.AuthParams = query.Encode()
+						"prompt": "none login",
+					},
+				).Encode()
 			}),
 			formParams:                        happyUsernamePasswordFormParams,
 			wantStatus:                        http.StatusSeeOther,
@@ -409,6 +527,7 @@ func TestPostLoginEndpoint(t *testing.T) {
 			wantDownstreamRedirectURI:         downstreamRedirectURI,
 			wantDownstreamGrantedScopes:       []string{}, // no scopes granted
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClient:              downstreamPinnipedCLIClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   expectedHappyLDAPUpstreamCustomSession,
@@ -419,9 +538,9 @@ func TestPostLoginEndpoint(t *testing.T) {
 				WithLDAP(&upstreamLDAPIdentityProvider). // should pick this one
 				WithActiveDirectory(&erroringUpstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				query["scope"] = []string{"openid"}
+					map[string]string{"scope": "openid"},
-				data.AuthParams = query.Encode()
+				).Encode()
 			}),
 			formParams:                        happyUsernamePasswordFormParams,
 			wantStatus:                        http.StatusSeeOther,
@@ -434,6 +553,7 @@ func TestPostLoginEndpoint(t *testing.T) {
 			wantDownstreamRedirectURI:         downstreamRedirectURI,
 			wantDownstreamGrantedScopes:       []string{"openid"},
 			wantDownstreamNonce:               downstreamNonce,
+			wantDownstreamClient:              downstreamPinnipedCLIClientID,
 			wantDownstreamPKCEChallenge:       downstreamPKCEChallenge,
 			wantDownstreamPKCEChallengeMethod: downstreamPKCEChallengeMethod,
 			wantDownstreamCustomSessionData:   expectedHappyLDAPUpstreamCustomSession,
@@ -502,9 +622,21 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "downstream redirect uri does not match what is configured for client",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				query["redirect_uri"] = []string{"http://127.0.0.1/wrong_callback"}
+					map[string]string{"redirect_uri": "http://127.0.0.1/wrong_callback"},
-				data.AuthParams = query.Encode()
+				).Encode()
+			}),
+			formParams: happyUsernamePasswordFormParams,
+			wantErr:    "error using state downstream auth params",
+		},
+		{
+			name:          "downstream redirect uri does not match what is configured for client with dynamic client",
+			idps:          oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
+			kubeResources: addFullyCapableDynamicClientAndSecretToKubeResources,
+			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQueryForDynamicClient,
+					map[string]string{"redirect_uri": "http://127.0.0.1/wrong_callback"},
+				).Encode()
 			}),
 			formParams: happyUsernamePasswordFormParams,
 			wantErr:    "error using state downstream auth params",
@@ -513,9 +645,9 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "downstream client does not exist",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				query["client_id"] = []string{"wrong_client_id"}
+					map[string]string{"client_id": "wrong_client_id"},
-				data.AuthParams = query.Encode()
+				).Encode()
 			}),
 			formParams: happyUsernamePasswordFormParams,
 			wantErr:    "error using state downstream auth params",
@@ -524,9 +656,9 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "downstream client is missing",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				delete(query, "client_id")
+					map[string]string{"client_id": ""},
-				data.AuthParams = query.Encode()
+				).Encode()
 			}),
 			formParams: happyUsernamePasswordFormParams,
 			wantErr:    "error using state downstream auth params",
@@ -535,9 +667,21 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "response type is unsupported",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				query["response_type"] = []string{"unsupported"}
+					map[string]string{"response_type": "unsupported"},
-				data.AuthParams = query.Encode()
+				).Encode()
+			}),
+			formParams: happyUsernamePasswordFormParams,
+			wantErr:    "error using state downstream auth params",
+		},
+		{
+			name:          "response type form_post is unsupported for dynamic clients",
+			idps:          oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
+			kubeResources: addFullyCapableDynamicClientAndSecretToKubeResources,
+			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQueryForDynamicClient,
+					map[string]string{"response_type": "form_post"},
+				).Encode()
 			}),
 			formParams: happyUsernamePasswordFormParams,
 			wantErr:    "error using state downstream auth params",
@@ -546,9 +690,9 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "response type is missing",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				delete(query, "response_type")
+					map[string]string{"response_type": ""},
-				data.AuthParams = query.Encode()
+				).Encode()
 			}),
 			formParams: happyUsernamePasswordFormParams,
 			wantErr:    "error using state downstream auth params",
@@ -557,9 +701,9 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "PKCE code_challenge is missing",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				delete(query, "code_challenge")
+					map[string]string{"code_challenge": ""},
-				data.AuthParams = query.Encode()
+				).Encode()
 			}),
 			formParams:                   happyUsernamePasswordFormParams,
 			wantStatus:                   http.StatusSeeOther,
@@ -572,9 +716,9 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "PKCE code_challenge_method is invalid",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				query["code_challenge_method"] = []string{"this-is-not-a-valid-pkce-alg"}
+					map[string]string{"code_challenge_method": "this-is-not-a-valid-pkce-alg"},
-				data.AuthParams = query.Encode()
+				).Encode()
 			}),
 			formParams:                   happyUsernamePasswordFormParams,
 			wantStatus:                   http.StatusSeeOther,
@@ -587,9 +731,9 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "PKCE code_challenge_method is `plain`",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				query["code_challenge_method"] = []string{"plain"} // plain is not allowed
+					map[string]string{"code_challenge_method": "plain"}, // plain is not allowed
-				data.AuthParams = query.Encode()
+				).Encode()
 			}),
 			formParams:                   happyUsernamePasswordFormParams,
 			wantStatus:                   http.StatusSeeOther,
@@ -602,9 +746,25 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "PKCE code_challenge_method is missing",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				delete(query, "code_challenge_method")
+					map[string]string{"code_challenge_method": ""},
-				data.AuthParams = query.Encode()
+				).Encode()
+			}),
+			formParams:                   happyUsernamePasswordFormParams,
+			wantStatus:                   http.StatusSeeOther,
+			wantContentType:              htmlContentType,
+			wantBodyString:               "",
+			wantRedirectLocationString:   urlWithQuery(downstreamRedirectURI, fositeMissingCodeChallengeMethodErrorQuery),
+			wantUnnecessaryStoredRecords: 2, // fosite already stored the authcode and oidc session before it noticed the error
+		},
+		{
+			name:          "PKCE code_challenge_method is missing with dynamic client",
+			idps:          oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
+			kubeResources: addFullyCapableDynamicClientAndSecretToKubeResources,
+			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQueryForDynamicClient,
+					map[string]string{"code_challenge_method": ""},
+				).Encode()
 			}),
 			formParams:                   happyUsernamePasswordFormParams,
 			wantStatus:                   http.StatusSeeOther,
@@ -617,9 +777,9 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "prompt param is not allowed to have none and another legal value at the same time",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				query["prompt"] = []string{"none login"}
+					map[string]string{"prompt": "none login"},
-				data.AuthParams = query.Encode()
+				).Encode()
 			}),
 			formParams:                   happyUsernamePasswordFormParams,
 			wantStatus:                   http.StatusSeeOther,
@@ -632,9 +792,9 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "downstream state does not have enough entropy",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				query["state"] = []string{"short"}
+					map[string]string{"state": "short"},
-				data.AuthParams = query.Encode()
+				).Encode()
 			}),
 			formParams: happyUsernamePasswordFormParams,
 			wantErr:    "error using state downstream auth params",
@@ -643,9 +803,21 @@ func TestPostLoginEndpoint(t *testing.T) {
 			name: "downstream scopes do not match what is configured for client",
 			idps: oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
 			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
-				query := copyOfHappyDownstreamRequestParamsQuery()
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQuery,
-				query["scope"] = []string{"openid offline_access pinniped:request-audience scope_not_allowed"}
+					map[string]string{"scope": "openid offline_access pinniped:request-audience scope_not_allowed"},
-				data.AuthParams = query.Encode()
+				).Encode()
+			}),
+			formParams: happyUsernamePasswordFormParams,
+			wantErr:    "error using state downstream auth params",
+		},
+		{
+			name:          "downstream scopes do not match what is configured for client with dynamic client",
+			idps:          oidctestutil.NewUpstreamIDPListerBuilder().WithLDAP(&upstreamLDAPIdentityProvider),
+			kubeResources: addFullyCapableDynamicClientAndSecretToKubeResources,
+			decodedState: modifyHappyLDAPDecodedState(func(data *oidc.UpstreamStateParamData) {
+				data.AuthParams = shallowCopyAndModifyQuery(happyDownstreamRequestParamsQueryForDynamicClient,
+					map[string]string{"scope": "openid offline_access pinniped:request-audience scope_not_allowed"},
+				).Encode()
 			}),
 			formParams: happyUsernamePasswordFormParams,
 			wantErr:    "error using state downstream auth params",
@@ -677,8 +849,8 @@ func TestPostLoginEndpoint(t *testing.T) {
 			secretsClient := kubeClient.CoreV1().Secrets("some-namespace")
 			oidcClientsClient := supervisorClient.ConfigV1alpha1().OIDCClients("some-namespace")
 
-			if test.kubeResources != nil {
+			if tt.kubeResources != nil {
-				test.kubeResources(t, supervisorClient, kubeClient)
+				tt.kubeResources(t, supervisorClient, kubeClient)
 			}
 
 			// Configure fosite the same way that the production code would.
@@ -704,7 +876,7 @@ func TestPostLoginEndpoint(t *testing.T) {
 			err := subject(rsp, req, happyEncodedUpstreamState, tt.decodedState)
 			if tt.wantErr != "" {
 				require.EqualError(t, err, tt.wantErr)
-				require.Empty(t, kubeClient.Actions())
+				require.Empty(t, oidctestutil.FilterClientSecretCreateActions(kubeClient.Actions()))
 				return // the http response doesn't matter when the function returns an error, because the caller should handle the error
 			}
 			// Otherwise, expect no error.
@@ -735,7 +907,7 @@ func TestPostLoginEndpoint(t *testing.T) {
 					tt.wantDownstreamPKCEChallenge,
 					tt.wantDownstreamPKCEChallengeMethod,
 					tt.wantDownstreamNonce,
-					downstreamClientID,
+					tt.wantDownstreamClient,
 					tt.wantDownstreamRedirectURI,
 					tt.wantDownstreamCustomSessionData,
 				)
@@ -745,12 +917,12 @@ func TestPostLoginEndpoint(t *testing.T) {
 				expectedLocation := downstreamIssuer + oidc.PinnipedLoginPath +
 					"?err=" + tt.wantRedirectToLoginPageError + "&state=" + happyEncodedUpstreamState
 				require.Equal(t, expectedLocation, actualLocation)
-				require.Len(t, kubeClient.Actions(), tt.wantUnnecessaryStoredRecords)
+				require.Len(t, oidctestutil.FilterClientSecretCreateActions(kubeClient.Actions()), tt.wantUnnecessaryStoredRecords)
 			case tt.wantRedirectLocationString != "":
 				// Expecting an error redirect to the client.
 				require.Equal(t, tt.wantBodyString, rsp.Body.String())
 				require.Equal(t, tt.wantRedirectLocationString, actualLocation)
-				require.Len(t, kubeClient.Actions(), tt.wantUnnecessaryStoredRecords)
+				require.Len(t, oidctestutil.FilterClientSecretCreateActions(kubeClient.Actions()), tt.wantUnnecessaryStoredRecords)
 			case tt.wantBodyFormResponseRegexp != "":
 				// Expecting the body of the response to be a html page with a form (for "response_mode=form_post").
 				_, hasLocationHeader := rsp.Header()["Location"]
@@ -770,7 +942,7 @@ func TestPostLoginEndpoint(t *testing.T) {
 					tt.wantDownstreamPKCEChallenge,
 					tt.wantDownstreamPKCEChallengeMethod,
 					tt.wantDownstreamNonce,
-					downstreamClientID,
+					tt.wantDownstreamClient,
 					tt.wantDownstreamRedirectURI,
 					tt.wantDownstreamCustomSessionData,
 				)
@@ -781,3 +953,18 @@ func TestPostLoginEndpoint(t *testing.T) {
 		})
 	}
 }
+
+func shallowCopyAndModifyQuery(query url.Values, modifications map[string]string) url.Values {
+	copied := url.Values{}
+	for key, value := range query {
+		copied[key] = value
+	}
+	for key, value := range modifications {
+		if value == "" {
+			copied.Del(key)
+		} else {
+			copied[key] = []string{value}
+		}
+	}
+	return copied
+}

internal/oidc/oidc.go

@@ -457,7 +457,7 @@ func PerformAuthcodeRedirect(
 ) {
 	authorizeResponder, err := oauthHelper.NewAuthorizeResponse(r.Context(), authorizeRequester, openIDSession)
 	if err != nil {
-		plog.WarningErr("error while generating and saving authcode", err)
+		plog.WarningErr("error while generating and saving authcode", err, "fositeErr", FositeErrorForLog(err))
 		WriteAuthorizeError(w, oauthHelper, authorizeRequester, err, isBrowserless)
 		return
 	}

internal/testutil/oidctestutil/oidctestutil.go

@@ -25,6 +25,7 @@ import (
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/client-go/kubernetes/fake"
 	v1 "k8s.io/client-go/kubernetes/typed/core/v1"
+	kubetesting "k8s.io/client-go/testing"
 	"k8s.io/utils/strings/slices"
 
 	"go.pinniped.dev/internal/authenticators"
@@ -954,7 +955,7 @@ func RequireAuthCodeRegexpMatch(
 	if includesOpenIDScope(wantDownstreamGrantedScopes) {
 		expectedNumberOfCreatedSecrets++
 	}
-	require.Len(t, kubeClient.Actions(), expectedNumberOfCreatedSecrets)
+	require.Len(t, FilterClientSecretCreateActions(kubeClient.Actions()), expectedNumberOfCreatedSecrets)
 
 	// One authcode should have been stored.
 	testutil.RequireNumberOfSecretsMatchingLabelSelector(t, secretsClient, labels.Set{crud.SecretLabelKey: authorizationcode.TypeLabelValue}, 1)
@@ -1164,3 +1165,20 @@ func castStoredAuthorizeRequest(t *testing.T, storedAuthorizeRequest fosite.Requ
 
 	return storedRequest, storedSession
 }
+
+// FilterClientSecretCreateActions ignores any reads made to get a storage secret corresponding to an OIDCClient, since these
+// are normal actions when the request is using a dynamic client's client_id, and we don't need to make assertions
+// about these Secrets since they are not related to session storage.
+func FilterClientSecretCreateActions(actions []kubetesting.Action) []kubetesting.Action {
+	filtered := make([]kubetesting.Action, 0, len(actions))
+	for _, action := range actions {
+		if action.Matches("get", "secrets") {
+			getAction := action.(kubetesting.GetAction)
+			if strings.HasPrefix(getAction.GetName(), "pinniped-storage-oidc-client-secret-") {
+				continue // filter out OIDCClient's storage secret reads
+			}
+		}
+		filtered = append(filtered, action) // otherwise include the action
+	}
+	return filtered
+}

test/testlib/client.go

@@ -15,6 +15,8 @@ import (
 	"testing"
 	"time"
 
+	"go.pinniped.dev/internal/oidc/oidcclientvalidator"
+
 	"github.com/stretchr/testify/require"
 	"golang.org/x/crypto/bcrypt"
 	authorizationv1 "k8s.io/api/authorization/v1"
@@ -435,7 +437,7 @@ func createOIDCClientSecret(t *testing.T, forOIDCClient *configv1alpha1.OIDCClie
 	_, err := io.ReadFull(rand.Reader, buf[:])
 	require.NoError(t, err)
 	randomSecret := hex.EncodeToString(buf[:])
-	hashedRandomSecret, err := bcrypt.GenerateFromPassword([]byte(randomSecret), 15)
+	hashedRandomSecret, err := bcrypt.GenerateFromPassword([]byte(randomSecret), oidcclientvalidator.DefaultMinBcryptCost)
 	require.NoError(t, err)
 
 	created, err := kubeClient.CoreV1().Secrets(env.SupervisorNamespace).Create(ctx, &corev1.Secret{