Add IDP initiated flow support

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

pkg/auth/saml_service.go

@@ -28,11 +28,11 @@ import (
 	"time"
 
 	"github.com/crewjam/saml"
+	"go.gearno.de/kit/log"
+	"go.gearno.de/kit/pg"
 	"go.probo.inc/probo/pkg/coredata"
 	"go.probo.inc/probo/pkg/crypto/cipher"
 	"go.probo.inc/probo/pkg/gid"
-	"go.gearno.de/kit/log"
-	"go.gearno.de/kit/pg"
 )
 
 type (
@@ -413,84 +413,130 @@ type SAMLUserInfo struct {
 	SAMLConfigID   gid.GID
 }
 
+func (s *SAMLService) loadContextForSPInitiated(
+	ctx context.Context,
+	relayStateToken string,
+	now time.Time,
+) (*coredata.SAMLConfiguration, *coredata.Organization, string, error) {
+	var relayState coredata.SAMLRelayState
+	var samlRequest coredata.SAMLRequest
+	var org coredata.Organization
+	var config coredata.SAMLConfiguration
+
+	err := s.pg.WithTx(ctx, func(tx pg.Conn) error {
+		if err := relayState.Load(ctx, tx, relayStateToken); err != nil {
+			return fmt.Errorf("invalid relay state: %w", err)
+		}
+
+		if relayState.IsExpired(now) {
+			return coredata.ErrRelayStateExpired{Token: relayStateToken, ExpiresAt: relayState.ExpiresAt}
+		}
+
+		if err := samlRequest.Load(ctx, tx, relayState.RequestID, relayState.OrganizationID); err != nil {
+			return fmt.Errorf("invalid SAML request: %w", err)
+		}
+
+		if samlRequest.IsExpired(now) {
+			return coredata.ErrSAMLRequestExpired{RequestID: relayState.RequestID, ExpiresAt: samlRequest.ExpiresAt}
+		}
+
+		if err := org.LoadByID(ctx, tx, coredata.NewNoScope(), relayState.OrganizationID); err != nil {
+			return fmt.Errorf("organization not found: %w", err)
+		}
+
+		scope := coredata.NewScope(org.TenantID)
+		if err := config.LoadByID(ctx, tx, scope, relayState.SAMLConfigID); err != nil {
+			return fmt.Errorf("cannot load SAML configuration: %w", err)
+		}
+
+		if err := relayState.Delete(ctx, tx); err != nil {
+			return fmt.Errorf("cannot delete relay state: %w", err)
+		}
+		if err := samlRequest.Delete(ctx, tx); err != nil {
+			return fmt.Errorf("cannot delete SAML request: %w", err)
+		}
+
+		return nil
+	})
+	if err != nil {
+		return nil, nil, "", err
+	}
+
+	return &config, &org, samlRequest.ID, nil
+}
+
+func (s *SAMLService) loadContextForIDPInitiated(
+	ctx context.Context,
+	samlConfigIDParam string,
+) (*coredata.SAMLConfiguration, *coredata.Organization, error) {
+	if samlConfigIDParam == "" {
+		return nil, nil, fmt.Errorf("IDP-initiated login requires 'c' query parameter with SAML config ID")
+	}
+
+	samlConfigID, err := gid.ParseGID(samlConfigIDParam)
+	if err != nil {
+		return nil, nil, fmt.Errorf("invalid 'c' parameter: %w", err)
+	}
+
+	var config coredata.SAMLConfiguration
+	var org coredata.Organization
+
+	err = s.pg.WithConn(ctx, func(conn pg.Conn) error {
+		if err := config.LoadByID(ctx, conn, coredata.NewNoScope(), samlConfigID); err != nil {
+			return fmt.Errorf("cannot load SAML configuration: %w", err)
+		}
+
+		if err := org.LoadByID(ctx, conn, coredata.NewNoScope(), config.OrganizationID); err != nil {
+			return fmt.Errorf("organization not found: %w", err)
+		}
+
+		return nil
+	})
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return &config, &org, nil
+}
+
 func (s *SAMLService) HandleSAMLAssertion(
 	ctx context.Context,
 	req *http.Request,
 ) (*SAMLUserInfo, error) {
-	relayStateToken := req.FormValue("RelayState")
-	if relayStateToken == "" {
-		return nil, fmt.Errorf("missing RelayState in SAML response")
-	}
-
-	var relayState coredata.SAMLRelayState
-	var samlRequest coredata.SAMLRequest
-	var config coredata.SAMLConfiguration
-	var org coredata.Organization
-
-	now := time.Now()
-
-	err := s.pg.WithTx(
-		ctx,
-		func(tx pg.Conn) error {
-			if err := relayState.Load(ctx, tx, relayStateToken); err != nil {
-				return fmt.Errorf("invalid relay state: %w", err)
-			}
-
-			if relayState.IsExpired(now) {
-				return coredata.ErrRelayStateExpired{Token: relayStateToken, ExpiresAt: relayState.ExpiresAt}
-			}
-
-			if err := samlRequest.Load(ctx, tx, relayState.RequestID, relayState.OrganizationID); err != nil {
-				return fmt.Errorf("invalid SAML request: %w", err)
-			}
-
-			if samlRequest.IsExpired(now) {
-				return coredata.ErrSAMLRequestExpired{RequestID: relayState.RequestID, ExpiresAt: samlRequest.ExpiresAt}
-			}
-
-			if err := org.LoadByID(ctx, tx, coredata.NewNoScope(), relayState.OrganizationID); err != nil {
-				return fmt.Errorf("organization not found: %w", err)
-			}
-
-			if err := relayState.Delete(ctx, tx); err != nil {
-				return fmt.Errorf("cannot delete relay state: %w", err)
-			}
-			if err := samlRequest.Delete(ctx, tx); err != nil {
-				return fmt.Errorf("cannot delete SAML request: %w", err)
-			}
-
-			return nil
-		},
-	)
-	if err != nil {
-		return nil, err
-	}
-
 	samlResponseEncoded := req.FormValue("SAMLResponse")
 	if samlResponseEncoded == "" {
 		return nil, fmt.Errorf("missing SAMLResponse in request")
 	}
 
-	scope := coredata.NewScope(org.TenantID)
-	err = s.pg.WithConn(
-		ctx,
-		func(conn pg.Conn) error {
-			if err := config.LoadByID(ctx, conn, scope, relayState.SAMLConfigID); err != nil {
-				return fmt.Errorf("cannot load SAML configuration: %w", err)
-			}
+	relayStateToken := req.FormValue("RelayState")
+	samlConfigIDParam := req.URL.Query().Get("c")
+	now := time.Now()
 
-			return nil
-		},
-	)
-	if err != nil {
-		return nil, fmt.Errorf("cannot load SAML configuration: %w", err)
+	var config *coredata.SAMLConfiguration
+	var org *coredata.Organization
+	var possibleRequestIDs []string
+	var err error
+
+	if relayStateToken != "" {
+		var requestID string
+		config, org, requestID, err = s.loadContextForSPInitiated(ctx, relayStateToken, now)
+		if err != nil {
+			return nil, err
+		}
+		possibleRequestIDs = []string{requestID}
+	} else {
+		config, org, err = s.loadContextForIDPInitiated(ctx, samlConfigIDParam)
+		if err != nil {
+			return nil, err
+		}
+		possibleRequestIDs = []string{}
 	}
 
 	if !config.Enabled {
 		return nil, ErrSAMLDisabled{OrganizationID: config.OrganizationID}
 	}
 
-	sp, err := s.GetServiceProvider(ctx, &config)
+	sp, err := s.GetServiceProvider(ctx, config)
 	if err != nil {
 		return nil, ErrCannotCreateServiceProvider{Err: err}
 	}
@@ -502,7 +548,6 @@ func (s *SAMLService) HandleSAMLAssertion(
 		req.URL.Host = req.Host
 	}
 
-	possibleRequestIDs := []string{samlRequest.ID}
 	assertion, err := sp.ParseResponse(req, possibleRequestIDs)
 	if err != nil {
 		return nil, fmt.Errorf(
@@ -516,6 +561,7 @@ func (s *SAMLService) HandleSAMLAssertion(
 	if err := ValidateAssertion(assertion, s.GetEntityID(), now); err != nil {
 		return nil, ErrCannotValidateAssertion{Err: err}
 	}
+
 	if assertion.ID != "" {
 		var expiresAt time.Time
 		if assertion.Conditions != nil && !assertion.Conditions.NotOnOrAfter.IsZero() {
@@ -525,22 +571,14 @@ func (s *SAMLService) HandleSAMLAssertion(
 		}
 
 		scope := coredata.NewScope(org.TenantID)
-		err = s.pg.WithTx(
-			ctx,
-			func(tx pg.Conn) error {
-				if err := PreventReplayAttack(ctx, tx, scope, assertion.ID, relayState.OrganizationID, expiresAt); err != nil {
-					return fmt.Errorf("cannot prevent replay attack: %w", err)
-				}
-
-				return nil
-			},
-		)
+		err = s.pg.WithTx(ctx, func(tx pg.Conn) error {
+			return PreventReplayAttack(ctx, tx, scope, assertion.ID, config.OrganizationID, expiresAt)
+		})
 		if err != nil {
 			var replayAttackErr *coredata.ErrAssertionAlreadyUsed
 			if errors.As(err, &replayAttackErr) {
 				return nil, ErrReplayAttackDetected{AssertionID: assertion.ID, Err: replayAttackErr}
 			}
-
 			return nil, fmt.Errorf("cannot prevent replay attack: %w", err)
 		}
 	}
@@ -576,8 +614,8 @@ func (s *SAMLService) HandleSAMLAssertion(
 		FullName:       fullname,
 		Role:           systemRole,
 		SAMLSubject:    samlSubject,
-		OrganizationID: relayState.OrganizationID,
-		SAMLConfigID:   relayState.SAMLConfigID,
+		OrganizationID: config.OrganizationID,
+		SAMLConfigID:   config.ID,
 	}, nil
 }
 

pkg/server/auth/saml_acs_handler.go

@@ -60,10 +60,13 @@ func SAMLACSHandler(samlSvc *authsvc.SAMLService, authSvc *authsvc.Service, auth
 			return
 		}
 
-		if r.FormValue("RelayState") == "" {
-			logger.WarnCtx(ctx, "missing RelayState")
-			http.Error(w, "missing RelayState", http.StatusBadRequest)
-			return
+		relayState := r.FormValue("RelayState")
+		samlConfigID := r.URL.Query().Get("c")
+
+		if relayState != "" {
+			logger.InfoCtx(ctx, "processing SP-initiated SAML login", log.String("relay_state", relayState))
+		} else {
+			logger.InfoCtx(ctx, "processing IDP-initiated SAML login", log.String("config_id", samlConfigID))
 		}
 
 		userInfo, err := samlSvc.HandleSAMLAssertion(ctx, r)