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Replace the eBPF WireGuard proxy with loopback endpoint addressing

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This commit is contained in:
Viktor Liu
2026-08-25 12:27:47 +02:00
parent 7f03a2e86f
commit 2a3b0cec08
23 changed files with 958 additions and 536 deletions
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client/firewall/nftables/manager_linux.go
+35 -17
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@@ -672,35 +672,46 @@ func (m *Manager) RemoveOutputDNAT(localAddr netip.Addr, protocol firewall.Proto
return m.router.RemoveOutputDNAT(localAddr, protocol, originalPort, translatedPort)
}
// The proxy hands every relayed peer its own address out of 127.0.0.0/8, so the
// notrack rules match the whole loopback range.
var (
loopbackNet = []byte{127, 0, 0, 0}
loopbackMask = []byte{255, 0, 0, 0}
loopbackXor = []byte{0, 0, 0, 0}
)
const (
chainNameRawOutput = "netbird-raw-out"
chainNameRawPrerouting = "netbird-raw-pre"
)
// SetupEBPFProxyNoTrack creates notrack rules for eBPF proxy loopback traffic.
// SetupWGProxyNoTrack creates notrack rules for WireGuard proxy loopback traffic.
// This prevents conntrack from tracking WireGuard proxy traffic on loopback, which
// can interfere with MASQUERADE rules (e.g., from container runtimes like Podman/netavark).
//
// Every relayed peer has its own loopback endpoint address, so the rules match the
// whole 127.0.0.0/8 range.
//
// Traffic flows that need NOTRACK:
//
// 1. Egress: WireGuard -> fake endpoint (before eBPF rewrite)
// src=127.0.0.1:wgPort -> dst=127.0.0.1:fakePort
// 1. Egress: WireGuard -> peer endpoint
// src=127.0.0.1:wgPort -> dst=127.x.x.x:proxyPort
// Matched by: sport=wgPort
//
// 2. Egress: Proxy -> WireGuard (via raw socket)
// src=127.0.0.1:fakePort -> dst=127.0.0.1:wgPort
// src=127.x.x.x:proxyPort -> dst=127.0.0.1:wgPort
// Matched by: dport=wgPort
//
// 3. Ingress: Packets to WireGuard
// dst=127.0.0.1:wgPort
// Matched by: dport=wgPort
//
// 4. Ingress: Packets to proxy (after eBPF rewrite)
// dst=127.0.0.1:proxyPort
// 4. Ingress: Packets to the proxy
// dst=127.x.x.x:proxyPort
// Matched by: dport=proxyPort
//
// Rules are cleaned up when the firewall manager is closed.
func (m *Manager) SetupEBPFProxyNoTrack(proxyPort, wgPort uint16) error {
func (m *Manager) SetupWGProxyNoTrack(proxyPort, wgPort uint16) error {
m.mutex.Lock()
defer m.mutex.Unlock()
@@ -710,7 +721,6 @@ func (m *Manager) SetupEBPFProxyNoTrack(proxyPort, wgPort uint16) error {
proxyPortBytes := binaryutil.BigEndian.PutUint16(proxyPort)
wgPortBytes := binaryutil.BigEndian.PutUint16(wgPort)
loopback := []byte{127, 0, 0, 1}
// Egress rules: match outgoing loopback UDP packets
m.rConn.AddRule(&nftables.Rule{
@@ -720,9 +730,11 @@ func (m *Manager) SetupEBPFProxyNoTrack(proxyPort, wgPort uint16) error {
&expr.Meta{Key: expr.MetaKeyOIFNAME, Register: 1},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: ifname("lo")},
&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 12, Len: 4}, // saddr
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
&expr.Bitwise{SourceRegister: 1, DestRegister: 1, Len: 4, Mask: loopbackMask, Xor: loopbackXor},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopbackNet},
&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 16, Len: 4}, // daddr
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
&expr.Bitwise{SourceRegister: 1, DestRegister: 1, Len: 4, Mask: loopbackMask, Xor: loopbackXor},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopbackNet},
&expr.Meta{Key: expr.MetaKeyL4PROTO, Register: 1},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: []byte{unix.IPPROTO_UDP}},
&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseTransportHeader, Offset: 0, Len: 2},
@@ -738,9 +750,11 @@ func (m *Manager) SetupEBPFProxyNoTrack(proxyPort, wgPort uint16) error {
&expr.Meta{Key: expr.MetaKeyOIFNAME, Register: 1},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: ifname("lo")},
&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 12, Len: 4}, // saddr
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
&expr.Bitwise{SourceRegister: 1, DestRegister: 1, Len: 4, Mask: loopbackMask, Xor: loopbackXor},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopbackNet},
&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 16, Len: 4}, // daddr
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
&expr.Bitwise{SourceRegister: 1, DestRegister: 1, Len: 4, Mask: loopbackMask, Xor: loopbackXor},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopbackNet},
&expr.Meta{Key: expr.MetaKeyL4PROTO, Register: 1},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: []byte{unix.IPPROTO_UDP}},
&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseTransportHeader, Offset: 2, Len: 2},
@@ -758,9 +772,11 @@ func (m *Manager) SetupEBPFProxyNoTrack(proxyPort, wgPort uint16) error {
&expr.Meta{Key: expr.MetaKeyIIFNAME, Register: 1},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: ifname("lo")},
&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 12, Len: 4}, // saddr
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
&expr.Bitwise{SourceRegister: 1, DestRegister: 1, Len: 4, Mask: loopbackMask, Xor: loopbackXor},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopbackNet},
&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 16, Len: 4}, // daddr
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
&expr.Bitwise{SourceRegister: 1, DestRegister: 1, Len: 4, Mask: loopbackMask, Xor: loopbackXor},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopbackNet},
&expr.Meta{Key: expr.MetaKeyL4PROTO, Register: 1},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: []byte{unix.IPPROTO_UDP}},
&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseTransportHeader, Offset: 2, Len: 2},
@@ -776,9 +792,11 @@ func (m *Manager) SetupEBPFProxyNoTrack(proxyPort, wgPort uint16) error {
&expr.Meta{Key: expr.MetaKeyIIFNAME, Register: 1},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: ifname("lo")},
&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 12, Len: 4}, // saddr
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
&expr.Bitwise{SourceRegister: 1, DestRegister: 1, Len: 4, Mask: loopbackMask, Xor: loopbackXor},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopbackNet},
&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseNetworkHeader, Offset: 16, Len: 4}, // daddr
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopback},
&expr.Bitwise{SourceRegister: 1, DestRegister: 1, Len: 4, Mask: loopbackMask, Xor: loopbackXor},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: loopbackNet},
&expr.Meta{Key: expr.MetaKeyL4PROTO, Register: 1},
&expr.Cmp{Op: expr.CmpOpEq, Register: 1, Data: []byte{unix.IPPROTO_UDP}},
&expr.Payload{DestRegister: 1, Base: expr.PayloadBaseTransportHeader, Offset: 2, Len: 2},
@@ -792,7 +810,7 @@ func (m *Manager) SetupEBPFProxyNoTrack(proxyPort, wgPort uint16) error {
return fmt.Errorf("flush notrack rules: %w", err)
}
log.Debugf("set up ebpf proxy notrack rules for ports %d,%d", proxyPort, wgPort)
log.Debugf("set up wg proxy notrack rules for ports %d,%d", proxyPort, wgPort)
return nil
}