wgengine: add exit destination logging enable for wgengine logger (#11952)

Updates tailscale/corp#18625
Co-authored-by: Kevin Liang <kevinliang@tailscale.com>
Signed-off-by: Claire Wang <claire@tailscale.com>

wgengine/netlog/logger.go

@@ -93,7 +93,7 @@ func (nl *Logger) Running() bool {
 // The IP protocol and source port are always zero.
 // The sock is used to populated the PhysicalTraffic field in Message.
 // The netMon parameter is optional; if non-nil it's used to do faster interface lookups.
-func (nl *Logger) Startup(nodeID tailcfg.StableNodeID, nodeLogID, domainLogID logid.PrivateID, tun, sock Device, netMon *netmon.Monitor, health *health.Tracker) error {
+func (nl *Logger) Startup(nodeID tailcfg.StableNodeID, nodeLogID, domainLogID logid.PrivateID, tun, sock Device, netMon *netmon.Monitor, health *health.Tracker, logExitFlowEnabledEnabled bool) error {
 	nl.mu.Lock()
 	defer nl.mu.Unlock()
 	if nl.logger != nil {
@@ -131,7 +131,7 @@ func (nl *Logger) Startup(nodeID tailcfg.StableNodeID, nodeLogID, domainLogID lo
 		addrs := nl.addrs
 		prefixes := nl.prefixes
 		nl.mu.Unlock()
-		recordStatistics(nl.logger, nodeID, start, end, virtual, physical, addrs, prefixes)
+		recordStatistics(nl.logger, nodeID, start, end, virtual, physical, addrs, prefixes, logExitFlowEnabledEnabled)
 	})
 
 	// Register the connection tracker into the TUN device.
@@ -151,7 +151,7 @@ func (nl *Logger) Startup(nodeID tailcfg.StableNodeID, nodeLogID, domainLogID lo
 	return nil
 }
 
-func recordStatistics(logger *logtail.Logger, nodeID tailcfg.StableNodeID, start, end time.Time, connstats, sockStats map[netlogtype.Connection]netlogtype.Counts, addrs map[netip.Addr]bool, prefixes map[netip.Prefix]bool) {
+func recordStatistics(logger *logtail.Logger, nodeID tailcfg.StableNodeID, start, end time.Time, connstats, sockStats map[netlogtype.Connection]netlogtype.Counts, addrs map[netip.Addr]bool, prefixes map[netip.Prefix]bool, logExitFlowEnabled bool) {
 	m := netlogtype.Message{NodeID: nodeID, Start: start.UTC(), End: end.UTC()}
 
 	classifyAddr := func(a netip.Addr) (isTailscale, withinRoute bool) {
@@ -180,7 +180,7 @@ func recordStatistics(logger *logtail.Logger, nodeID tailcfg.StableNodeID, start
 			m.SubnetTraffic = append(m.SubnetTraffic, netlogtype.ConnectionCounts{Connection: conn, Counts: cnts})
 		default:
 			const anonymize = true
-			if anonymize {
+			if anonymize && !logExitFlowEnabled {
 				// Only preserve the address if it is a Tailscale IP address.
 				srcOrig, dstOrig := conn.Src, conn.Dst
 				conn = netlogtype.Connection{} // scrub everything by default

wgengine/userspace.go

@@ -965,8 +965,9 @@ func (e *userspaceEngine) Reconfig(cfg *wgcfg.Config, routerCfg *router.Config,
 	if netLogRunning && !e.networkLogger.Running() {
 		nid := cfg.NetworkLogging.NodeID
 		tid := cfg.NetworkLogging.DomainID
+		logExitFlowEnabled := cfg.NetworkLogging.LogExitFlowEnabled
 		e.logf("wgengine: Reconfig: starting up network logger (node:%s tailnet:%s)", nid.Public(), tid.Public())
-		if err := e.networkLogger.Startup(cfg.NodeID, nid, tid, e.tundev, e.magicConn, e.netMon, e.health); err != nil {
+		if err := e.networkLogger.Startup(cfg.NodeID, nid, tid, e.tundev, e.magicConn, e.netMon, e.health, logExitFlowEnabled); err != nil {
 			e.logf("wgengine: Reconfig: error starting up network logger: %v", err)
 		}
 		e.networkLogger.ReconfigRoutes(routerCfg)

wgengine/wgcfg/config.go

@@ -27,9 +27,11 @@ type Config struct {
 
 	// NetworkLogging enables network logging.
 	// It is disabled if either ID is the zero value.
+	// LogExitFlowEnabled indicates whether or not exit flows should be logged.
 	NetworkLogging struct {
 		NodeID             logid.PrivateID
 		DomainID           logid.PrivateID
+		LogExitFlowEnabled bool
 	}
 }
 

wgengine/wgcfg/nmcfg/nmcfg.go

@@ -63,6 +63,7 @@ func WGCfg(nm *netmap.NetworkMap, logf logger.Logf, flags netmap.WGConfigFlags,
 	if nm.SelfNode.Valid() {
 		cfg.NodeID = nm.SelfNode.StableID()
 		canNetworkLog := nm.SelfNode.HasCap(tailcfg.CapabilityDataPlaneAuditLogs)
+		logExitFlowEnabled := nm.SelfNode.HasCap(tailcfg.NodeAttrLogExitFlows)
 		if canNetworkLog && nm.SelfNode.DataPlaneAuditLogID() != "" && nm.DomainAuditLogID != "" {
 			nodeID, errNode := logid.ParsePrivateID(nm.SelfNode.DataPlaneAuditLogID())
 			if errNode != nil {
@@ -75,6 +76,7 @@ func WGCfg(nm *netmap.NetworkMap, logf logger.Logf, flags netmap.WGConfigFlags,
 			if errNode == nil && errDomain == nil {
 				cfg.NetworkLogging.NodeID = nodeID
 				cfg.NetworkLogging.DomainID = domainID
+				cfg.NetworkLogging.LogExitFlowEnabled = logExitFlowEnabled
 			}
 		}
 	}

wgengine/wgcfg/wgcfg_clone.go

@@ -45,6 +45,7 @@ func (src *Config) Clone() *Config {
 	NetworkLogging struct {
 		NodeID             logid.PrivateID
 		DomainID           logid.PrivateID
+		LogExitFlowEnabled bool
 	}
 }{})