[management] Deny reverse proxy access to pending and blocked users (#7105)

A user in the Pending Approval state could complete SSO and reach any SSO-protected reverse proxy service distributed to a group they belong to, including the All Users group. The reverse proxy authorization path checked the session token signature, that the user exists, that the user's account matches the service's account, and group membership — never the user's account status. The REST API (`permissions/manager.go`) and peer registration both gate on that state, but the proxy gRPC service does not go through the permissions manager, so neither gate applied. A pending user is persisted as blocked and pending approval, so blocked users reached those services the same way. `ValidateSession` now denies on account status, reporting `pending_approval` or `user_blocked` so the proxy access log and the denied page carry the cause rather than a generic refusal. `GenerateSessionToken` refuses to mint a token for such a user at all, so the browser never receives a session cookie and the OIDC callback can tell the user why instead of showing "Service configuration error". `ValidateUserGroupAccess` and `ValidateTunnelPeer` close the same gap; for the tunnel path this covers a user blocked after their peer was registered, since peer group membership alone kept mesh-origin access open. A single helper produces both the denied reason for the RPC responses and the sentinel error for the error-returning callers, so the four entry points cannot drift apart. A user the store cannot resolve is denied rather than passed through. One thing deliberately left out: session cookies are validated locally by the proxy against the service public key with no management round-trip, so a cookie issued before a user is blocked stays valid until it expires (24h by default). That is a revocation-propagation problem rather than this authorization gap, and every option for it (per-request validation with a cache, short-lived tokens with refresh, push-based revocation) changes the proxy hot path or the proxy/management protocol. Worth its own ticket.
2026-10-02 19:49:07 +02:00 · 2026-08-08 20:48:34 +09:00
parent 179e8f6e13
commit f65f7b347e
5 changed files with 735 additions and 99 deletions
@@ -29,6 +29,7 @@ import (

 	"github.com/netbirdio/netbird/shared/management/domain"

+	"github.com/netbirdio/netbird/management/internals/modules/agentnetwork"
 	"github.com/netbirdio/netbird/management/internals/modules/peers"
 	"github.com/netbirdio/netbird/management/internals/modules/reverseproxy/accesslogs"
 	"github.com/netbirdio/netbird/management/internals/modules/reverseproxy/proxy"
@@ -36,7 +37,6 @@ import (
 	"github.com/netbirdio/netbird/management/internals/modules/reverseproxy/sessionkey"
 	"github.com/netbirdio/netbird/management/server/idp"
 	"github.com/netbirdio/netbird/management/server/peer"
-	"github.com/netbirdio/netbird/management/internals/modules/agentnetwork"
 	"github.com/netbirdio/netbird/management/server/types"
 	"github.com/netbirdio/netbird/management/server/users"
 	proxyauth "github.com/netbirdio/netbird/proxy/auth"
@@ -1579,9 +1579,62 @@ func (s *ProxyServiceServer) ValidateState(state string) (verifier, redirectURL
 	return verifier, redirectURL, nil
 }

+// Denied reasons reported to the proxy when access is refused because of the
+// account status of the user behind the request.
+const (
+	deniedReasonPendingApproval = "pending_approval"
+	deniedReasonUserBlocked     = "user_blocked"
+	deniedReasonUserNotFound    = "user_not_found"
+)
+
+var (
+	// ErrUserPendingApproval reports a user whose account still awaits approval
+	// by an administrator and may therefore not hold a proxy session.
+	ErrUserPendingApproval = errors.New("user pending approval")
+
+	// ErrUserBlocked reports a blocked user, who may not hold a proxy session.
+	ErrUserBlocked = errors.New("user blocked")
+
+	errUserUnresolved = errors.New("user could not be resolved")
+)
+
+// checkUserStatus reports whether the user's account status permits reverse
+// proxy access, returning the denied reason for the proxy access log together
+// with the sentinel error callers match on. A user awaiting approval is stored
+// as both pending and blocked, so the pending state is reported first: it is
+// the one an administrator can act on.
+func checkUserStatus(user *types.User) (string, error) {
+	switch {
+	case user == nil:
+		return deniedReasonUserNotFound, errUserUnresolved
+	case user.PendingApproval:
+		return deniedReasonPendingApproval, ErrUserPendingApproval
+	case user.IsBlocked():
+		return deniedReasonUserBlocked, ErrUserBlocked
+	default:
+		return "", nil
+	}
+}
+
+// userStatusDeniedReason returns the denied reason for callers that report a
+// decision rather than an error, and an empty string when the user may proceed.
+func userStatusDeniedReason(user *types.User) string {
+	reason, _ := checkUserStatus(user)
+	return reason
+}
+
+// sameAccount reports whether a user belongs to a service's account. An empty
+// identifier on either side never matches: two unset accounts must not compare
+// equal into a grant.
+func sameAccount(userAccountID, serviceAccountID string) bool {
+	return userAccountID != "" && serviceAccountID != "" && userAccountID == serviceAccountID
+}
+
 // GenerateSessionToken creates a signed session JWT for the given domain and
 // user. The user's group memberships are embedded in the token so policy-aware
 // middlewares on the proxy can authorise without an extra management round-trip.
+// A user the store cannot resolve, or whose account is pending approval or
+// blocked, gets no token at all, so the browser never receives a session cookie.
 func (s *ProxyServiceServer) GenerateSessionToken(ctx context.Context, domain, userID string, method proxyauth.Method) (string, error) {
 	service, err := s.getServiceByDomain(ctx, domain)
 	if err != nil {
@@ -1592,25 +1645,37 @@ func (s *ProxyServiceServer) GenerateSessionToken(ctx context.Context, domain, u
 		return "", fmt.Errorf("no session key configured for domain: %s", domain)
 	}

-	var (
-		email      string
-		groupIDs   []string
-		groupNames []string
-	)
-	if s.usersManager != nil {
-		user, userGroups, uerr := s.usersManager.GetUserWithGroups(ctx, userID)
-		if uerr != nil {
-			log.WithContext(ctx).Debugf("session token mint: lookup user %s: %v", userID, uerr)
-		} else if user != nil {
-			email = user.Email
-			groupIDs, groupNames = pairGroupIDsAndNames(userGroups)
-		}
+	if s.usersManager == nil {
+		return "", errors.New("users manager not configured")
 	}

+	user, userGroups, err := s.usersManager.GetUserWithGroups(ctx, userID)
+	if err != nil {
+		return "", fmt.Errorf("get user %s: %w", userID, err)
+	}
+
+	if user == nil {
+		return "", fmt.Errorf("get user %s: %w", userID, errUserUnresolved)
+	}
+
+	// Bind the OIDC identity to the service's account before signing anything
+	// with that service's session key. The proxy validates an installed cookie
+	// locally against the service public key, so a token minted for a user of
+	// another account would be honoured without a management round-trip.
+	if !sameAccount(user.AccountID, service.AccountID) {
+		return "", fmt.Errorf("user %s does not belong to the service account", userID)
+	}
+
+	if _, err := checkUserStatus(user); err != nil {
+		return "", fmt.Errorf("session token for user %s: %w", userID, err)
+	}
+
+	groupIDs, groupNames := pairGroupIDsAndNames(userGroups)
+
 	return sessionkey.SignToken(
 		service.SessionPrivateKey,
 		userID,
-		email,
+		user.Email,
 		domain,
 		method,
 		groupIDs,
@@ -1628,6 +1693,10 @@ func (s *ProxyServiceServer) ValidateUserGroupAccess(ctx context.Context, domain
 		return fmt.Errorf("user not found: %s", userID)
 	}

+	if _, err := checkUserStatus(user); err != nil {
+		return fmt.Errorf("user %s denied access to domain %s: %w", userID, domain, err)
+	}
+
 	service, err := s.getAccountServiceByDomain(ctx, user.AccountID, domain)
 	if err != nil {
 		return err
@@ -1682,10 +1751,7 @@ func (s *ProxyServiceServer) ValidateSession(ctx context.Context, req *proto.Val
 	sessionToken := req.GetSessionToken()

 	if domain == "" || sessionToken == "" {
-		return &proto.ValidateSessionResponse{
-			Valid:        false,
-			DeniedReason: "missing domain or session_token",
-		}, nil
+		return deniedSessionResponse("missing domain or session_token"), nil
 	}

 	service, err := s.getServiceByDomain(ctx, domain)
@@ -1695,83 +1761,49 @@ func (s *ProxyServiceServer) ValidateSession(ctx context.Context, req *proto.Val
 			"error":  err.Error(),
 		}).Debug("ValidateSession: service not found")
 		//nolint:nilerr
-		return &proto.ValidateSessionResponse{
-			Valid:        false,
-			DeniedReason: "service_not_found",
-		}, nil
+		return deniedSessionResponse("service_not_found"), nil
 	}

 	if err := enforceAccountScope(ctx, service.AccountID); err != nil {
 		return nil, err
 	}

-	pubKeyBytes, err := base64.StdEncoding.DecodeString(service.SessionPublicKey)
-	if err != nil {
-		log.WithFields(log.Fields{
-			"domain": domain,
-			"error":  err.Error(),
-		}).Error("ValidateSession: decode public key")
-		//nolint:nilerr
-		return &proto.ValidateSessionResponse{
-			Valid:        false,
-			DeniedReason: "invalid_service_config",
-		}, nil
-	}
-
-	userID, _, _, _, _, err := proxyauth.ValidateSessionJWT(sessionToken, domain, pubKeyBytes)
-	if err != nil {
-		log.WithFields(log.Fields{
-			"domain": domain,
-			"error":  err.Error(),
-		}).Debug("ValidateSession: invalid session token")
-		//nolint:nilerr
-		return &proto.ValidateSessionResponse{
-			Valid:        false,
-			DeniedReason: "invalid_token",
-		}, nil
+	userID, reason := sessionTokenSubject(domain, service, sessionToken)
+	if reason != "" {
+		return deniedSessionResponse(reason), nil
 	}

 	user, userGroups, err := s.usersManager.GetUserWithGroups(ctx, userID)
-	if err != nil {
+	if err != nil || user == nil {
 		log.WithFields(log.Fields{
 			"domain":  domain,
 			"user_id": userID,
-			"error":   err.Error(),
+			"error":   err,
 		}).Debug("ValidateSession: user not found")
 		//nolint:nilerr
-		return &proto.ValidateSessionResponse{
-			Valid:        false,
-			DeniedReason: "user_not_found",
-		}, nil
+		return deniedSessionResponse(deniedReasonUserNotFound), nil
 	}

-	if user.AccountID != service.AccountID {
+	// A user from another account gets a bare response: none of their identity
+	// belongs in an answer to a proxy serving a different account.
+	if !sameAccount(user.AccountID, service.AccountID) {
 		log.WithFields(log.Fields{
 			"domain":          domain,
 			"user_id":         userID,
 			"user_account":    user.AccountID,
 			"service_account": service.AccountID,
 		}).Debug("ValidateSession: user account mismatch")
-		//nolint:nilerr
-		return &proto.ValidateSessionResponse{
-			Valid:        false,
-			DeniedReason: "account_mismatch",
-		}, nil
+		return deniedSessionResponse("account_mismatch"), nil
 	}

-	if err := s.checkGroupAccess(service, user); err != nil {
-		log.WithFields(log.Fields{
-			"domain":  domain,
-			"user_id": userID,
-			"error":   err.Error(),
-		}).Debug("ValidateSession: access denied")
-		groupIDs, groupNames := pairGroupIDsAndNames(userGroups)
-		//nolint:nilerr
+	groupIDs, groupNames := pairGroupIDsAndNames(userGroups)
+
+	if reason := s.accountUserDeniedReason(domain, service, user); reason != "" {
 		return &proto.ValidateSessionResponse{
 			Valid:          false,
 			UserId:         user.Id,
 			UserEmail:      user.Email,
-			DeniedReason:   "not_in_group",
+			DeniedReason:   reason,
 			PeerGroupIds:   groupIDs,
 			PeerGroupNames: groupNames,
 		}, nil
@@ -1783,7 +1815,6 @@ func (s *ProxyServiceServer) ValidateSession(ctx context.Context, req *proto.Val
 		"email":   user.Email,
 	}).Debug("ValidateSession: access granted")

-	groupIDs, groupNames := pairGroupIDsAndNames(userGroups)
 	return &proto.ValidateSessionResponse{
 		Valid:          true,
 		UserId:         user.Id,
@@ -1793,6 +1824,66 @@ func (s *ProxyServiceServer) ValidateSession(ctx context.Context, req *proto.Val
 	}, nil
 }

+// deniedSessionResponse builds a denial that carries no identity, for the
+// checks that run before a user of this service's account is resolved.
+func deniedSessionResponse(reason string) *proto.ValidateSessionResponse {
+	return &proto.ValidateSessionResponse{
+		Valid:        false,
+		DeniedReason: reason,
+	}
+}
+
+// sessionTokenSubject verifies the session token against the service's session
+// key and returns the user it was minted for, or the reason it cannot be
+// trusted.
+func sessionTokenSubject(domain string, service *rpservice.Service, sessionToken string) (userID, deniedReason string) {
+	pubKeyBytes, err := base64.StdEncoding.DecodeString(service.SessionPublicKey)
+	if err != nil {
+		log.WithFields(log.Fields{
+			"domain": domain,
+			"error":  err.Error(),
+		}).Error("ValidateSession: decode public key")
+		return "", "invalid_service_config"
+	}
+
+	userID, _, _, _, _, err = proxyauth.ValidateSessionJWT(sessionToken, domain, pubKeyBytes)
+	if err != nil {
+		log.WithFields(log.Fields{
+			"domain": domain,
+			"error":  err.Error(),
+		}).Debug("ValidateSession: invalid session token")
+		return "", "invalid_token"
+	}
+
+	return userID, ""
+}
+
+// accountUserDeniedReason gates a user of the service's own account, returning
+// an empty string when access is granted. Account status comes before group
+// membership: a user awaiting approval or blocked has no access regardless of
+// the groups they were auto-assigned.
+func (s *ProxyServiceServer) accountUserDeniedReason(domain string, service *rpservice.Service, user *types.User) string {
+	if reason := userStatusDeniedReason(user); reason != "" {
+		log.WithFields(log.Fields{
+			"domain":  domain,
+			"user_id": user.Id,
+			"reason":  reason,
+		}).Debug("ValidateSession: user status denies access")
+		return reason
+	}
+
+	if err := s.checkGroupAccess(service, user); err != nil {
+		log.WithFields(log.Fields{
+			"domain":  domain,
+			"user_id": user.Id,
+			"error":   err.Error(),
+		}).Debug("ValidateSession: access denied")
+		return "not_in_group"
+	}
+
+	return ""
+}
+
 func (s *ProxyServiceServer) getServiceByDomain(ctx context.Context, domain string) (*rpservice.Service, error) {
 	service, err := s.serviceManager.GetServiceByDomain(ctx, domain)
 	if err == nil {
@@ -1907,7 +1998,20 @@ func (s *ProxyServiceServer) ValidateTunnelPeer(ctx context.Context, req *proto.
 	}

 	groupIDs, groupNames := pairGroupIDsAndNames(peerGroups)
-	principalID, displayIdentity := s.getTunnelPeerInfo(ctx, domain, service, peer)
+	owner := s.resolvePeerOwner(ctx, peer, service.AccountID)
+	principalID, displayIdentity := s.getTunnelPeerInfo(ctx, domain, service, peer, owner)
+
+	if reason := peerOwnerDeniedReason(peer, owner); reason != "" {
+		log.WithFields(log.Fields{"domain": domain, "peer_id": peer.ID, "user_id": peer.UserID, "reason": reason}).Debug("ValidateTunnelPeer: owner status denies access")
+		return &proto.ValidateTunnelPeerResponse{
+			Valid:          false,
+			UserId:         principalID,
+			UserEmail:      displayIdentity,
+			DeniedReason:   reason,
+			PeerGroupIds:   groupIDs,
+			PeerGroupNames: groupNames,
+		}, nil
+	}

 	if err := checkPeerGroupAccess(service, groupIDs); err != nil {
 		log.WithFields(log.Fields{"domain": domain, "peer_id": peer.ID, "error": err.Error()}).Debug("ValidateTunnelPeer: access denied")
@@ -1944,9 +2048,55 @@ func (s *ProxyServiceServer) ValidateTunnelPeer(ctx context.Context, req *proto.
 	}, nil
 }

+// resolvePeerOwner returns the user a peer is linked to, once per request so
+// the status gate and the identity resolution below share a single lookup.
+// Unlinked peers (machine agents) have no owner. A lookup that fails returns
+// nil rather than an error: both callers treat an unresolved owner the same
+// way, and neither may trust one it could not read.
+func (s *ProxyServiceServer) resolvePeerOwner(ctx context.Context, peer *peer.Peer, accountID string) *types.User {
+	if peer.UserID == "" {
+		return nil
+	}
+
+	user, err := s.usersManager.GetUser(ctx, peer.UserID)
+	if err != nil {
+		log.WithContext(ctx).Debugf("ValidateTunnelPeer: look up owner %s of peer %s: %v", peer.UserID, peer.ID, err)
+		return nil
+	}
+
+	// The lookup is by user ID alone, so a peer row pointing outside the
+	// service's account would otherwise resolve a foreign user. Leave the owner
+	// unresolved instead: the gate denies it, and neither the response nor the
+	// minted token carries an identity from another account.
+	if !sameAccount(user.AccountID, accountID) {
+		log.WithContext(ctx).Debugf("ValidateTunnelPeer: owner %s of peer %s belongs to another account", peer.UserID, peer.ID)
+		return nil
+	}
+
+	return user
+}
+
+// peerOwnerDeniedReason gates the mesh fast-path on the account status of the
+// peer's owning user, so a user blocked after registering a peer loses
+// mesh-origin access too. Unlinked peers (machine agents) have no owner to gate
+// on and stay first-class callers. An owner the store cannot resolve denies:
+// an unavailable lookup must not grant access.
+func peerOwnerDeniedReason(peer *peer.Peer, owner *types.User) string {
+	if peer.UserID == "" {
+		return ""
+	}
+
+	if owner == nil {
+		return deniedReasonUserNotFound
+	}
+
+	return userStatusDeniedReason(owner)
+}
+
 // getTunnelPeerInfo returns the principal ID and display name for a peer, e.g. a
-// user or peer ID, and peer name or user email.
-func (s *ProxyServiceServer) getTunnelPeerInfo(ctx context.Context, domain string, service *rpservice.Service, peer *peer.Peer) (string, string) {
+// user or peer ID, and peer name or user email. owner is the already-resolved
+// user the peer is linked to, or nil.
+func (s *ProxyServiceServer) getTunnelPeerInfo(ctx context.Context, domain string, service *rpservice.Service, peer *peer.Peer, owner *types.User) (string, string) {
 	// Resolve the principal: when the peer is linked to a user, the human is the
 	// principal so multiple peers owned by the same user share a single
 	// identity. Unlinked peers (machine agents) are their own principal keyed on
@@ -1963,10 +2113,10 @@ func (s *ProxyServiceServer) getTunnelPeerInfo(ctx context.Context, domain strin
 	principalID := peer.UserID
 	displayIdentity := peer.Name
 	// Stored column first (cheap, but often empty for OIDC-provisioned users).
-	if user, uerr := s.usersManager.GetUser(ctx, peer.UserID); uerr == nil && user != nil {
-		principalID = user.Id
-		if user.Email != "" {
-			displayIdentity = user.Email
+	if owner != nil {
+		principalID = owner.Id
+		if owner.Email != "" {
+			displayIdentity = owner.Email
 		}
 	}
 	// IdP enrichment wins when available — the stored email column is a