wip: migrate to mono-repo. SPN has already been moved to spn/

service/firewall/interception/nfq/packet.go

@@ -0,0 +1,178 @@
+//go:build linux
+
+package nfq
+
+import (
+	"errors"
+	"fmt"
+	"sync/atomic"
+
+	"github.com/florianl/go-nfqueue"
+	"github.com/tevino/abool"
+
+	"github.com/safing/portbase/log"
+	pmpacket "github.com/safing/portmaster/service/network/packet"
+)
+
+// Firewalling marks used by the Portmaster.
+// See TODO on packet.mark() on their relevance
+// and a possibility to remove most IPtables rules.
+const (
+	MarkAccept       = 1700
+	MarkBlock        = 1701
+	MarkDrop         = 1702
+	MarkAcceptAlways = 1710
+	MarkBlockAlways  = 1711
+	MarkDropAlways   = 1712
+	MarkRerouteNS    = 1799
+	MarkRerouteSPN   = 1717
+)
+
+func markToString(mark int) string {
+	switch mark {
+	case MarkAccept:
+		return "Accept"
+	case MarkBlock:
+		return "Block"
+	case MarkDrop:
+		return "Drop"
+	case MarkAcceptAlways:
+		return "AcceptAlways"
+	case MarkBlockAlways:
+		return "BlockAlways"
+	case MarkDropAlways:
+		return "DropAlways"
+	case MarkRerouteNS:
+		return "RerouteNS"
+	case MarkRerouteSPN:
+		return "RerouteSPN"
+	}
+	return "unknown"
+}
+
+// packet implements the packet.Packet interface.
+type packet struct {
+	pmpacket.Base
+	pktID          uint32
+	queue          *Queue
+	verdictSet     chan struct{}
+	verdictPending *abool.AtomicBool
+}
+
+func (pkt *packet) ID() string {
+	return fmt.Sprintf("pkt:%d qid:%d", pkt.pktID, pkt.queue.id)
+}
+
+// LoadPacketData does nothing on Linux, as data is always fully parsed.
+func (pkt *packet) LoadPacketData() error {
+	return nil
+}
+
+// TODO(ppacher): revisit the following behavior:
+//
+//	The legacy implementation of nfqueue (and the interception) module
+//	always accept a packet but may mark it so that a subsequent rule in
+//	the C17 chain drops, rejects or modifies it.
+//
+//	For drop/return we could use the actual nfQueue verdicts Drop and Stop.
+//	Re-routing to local NS or SPN can be done by modifying the packet here
+//	and using SetVerdictModPacket and reject can be implemented using a simple
+//	raw-socket.
+func (pkt *packet) mark(mark int) (err error) {
+	if pkt.verdictPending.SetToIf(false, true) {
+		defer close(pkt.verdictSet)
+		return pkt.setMark(mark)
+	}
+
+	return errors.New("verdict already set")
+}
+
+func (pkt *packet) setMark(mark int) error {
+	atomic.AddUint64(&pkt.queue.pendingVerdicts, 1)
+
+	defer func() {
+		atomic.AddUint64(&pkt.queue.pendingVerdicts, ^uint64(0))
+		select {
+		case pkt.queue.verdictCompleted <- struct{}{}:
+		default:
+		}
+	}()
+
+	for {
+		if err := pkt.queue.getNfq().SetVerdictWithMark(pkt.pktID, nfqueue.NfAccept, mark); err != nil {
+			// embedded interface is required to work-around some
+			// dep-vendoring weirdness
+			if opErr, ok := err.(interface { //nolint:errorlint // TODO: Check if we can remove workaround.
+				Timeout() bool
+				Temporary() bool
+			}); ok {
+				if opErr.Timeout() || opErr.Temporary() {
+					continue
+				}
+			}
+
+			log.Tracer(pkt.Ctx()).Errorf("nfqueue: failed to set verdict %s for %s (%s -> %s): %s", markToString(mark), pkt.ID(), pkt.Info().Src, pkt.Info().Dst, err)
+			return err
+		}
+		break
+	}
+
+	// DEBUG:
+	// log.Tracer(pkt.Ctx()).Tracef(
+	// 	"nfqueue: marking packet %s (%s -> %s) on queue %d with %s after %s",
+	// 	pkt.ID(), pkt.Info().Src, pkt.Info().Dst, pkt.queue.id,
+	// 	markToString(mark), time.Since(pkt.Info().SeenAt),
+	// )
+	return nil
+}
+
+func (pkt *packet) Accept() error {
+	return pkt.mark(MarkAccept)
+}
+
+func (pkt *packet) Block() error {
+	if pkt.Info().Protocol == pmpacket.ICMP {
+		// ICMP packets attributed to a blocked connection are always allowed, as
+		// rejection ICMP packets will have the same mark as the blocked
+		// connection. This is why we need to drop blocked ICMP packets instead.
+		return pkt.mark(MarkDrop)
+	}
+	return pkt.mark(MarkBlock)
+}
+
+func (pkt *packet) Drop() error {
+	return pkt.mark(MarkDrop)
+}
+
+func (pkt *packet) PermanentAccept() error {
+	// If the packet is localhost only, do not permanently accept the outgoing
+	// packet, as the packet mark will be copied to the connection mark, which
+	// will stick and it will bypass the incoming queue.
+	if !pkt.Info().Inbound && pkt.Info().Dst.IsLoopback() {
+		return pkt.Accept()
+	}
+
+	return pkt.mark(MarkAcceptAlways)
+}
+
+func (pkt *packet) PermanentBlock() error {
+	if pkt.Info().Protocol == pmpacket.ICMP || pkt.Info().Protocol == pmpacket.ICMPv6 {
+		// ICMP packets attributed to a blocked connection are always allowed, as
+		// rejection ICMP packets will have the same mark as the blocked
+		// connection. This is why we need to drop blocked ICMP packets instead.
+		return pkt.mark(MarkDropAlways)
+	}
+	return pkt.mark(MarkBlockAlways)
+}
+
+func (pkt *packet) PermanentDrop() error {
+	return pkt.mark(MarkDropAlways)
+}
+
+func (pkt *packet) RerouteToNameserver() error {
+	return pkt.mark(MarkRerouteNS)
+}
+
+func (pkt *packet) RerouteToTunnel() error {
+	return pkt.mark(MarkRerouteSPN)
+}