WIP

client/internal/ipcauth/creds_stub.go

@@ -0,0 +1,13 @@
+//go:build !linux && !darwin && !freebsd && !windows
+
+package ipcauth
+
+import "google.golang.org/grpc/credentials"
+
+// NewTransportCredentials returns nil on platforms without a peer-identity
+// primitive. The daemon falls back to insecure credentials and skips per-RPC
+// authorization (logging a warning), preserving pre-hardening behavior until
+// the transport gains an identity primitive.
+func NewTransportCredentials() credentials.TransportCredentials {
+	return nil
+}

client/internal/ipcauth/creds_unix.go

@@ -0,0 +1,48 @@
+//go:build linux || darwin || freebsd
+
+package ipcauth
+
+import (
+	"context"
+	"net"
+
+	"google.golang.org/grpc/credentials"
+)
+
+// NewTransportCredentials returns gRPC transport credentials that extract the
+// caller's kernel-authenticated identity from a Unix-socket connection and
+// expose it via IdentityFromContext. It is non-nil on platforms with a
+// peer-credential primitive.
+func NewTransportCredentials() credentials.TransportCredentials {
+	return unixCreds{}
+}
+
+// unixCreds implements credentials.TransportCredentials over a Unix socket.
+// The server side reads SO_PEERCRED/LOCAL_PEERCRED during the handshake; the
+// client side is a no-op (the kernel supplies the peer identity to the server
+// without any client cooperation).
+type unixCreds struct{}
+
+func (unixCreds) ClientHandshake(_ context.Context, _ string, conn net.Conn) (net.Conn, credentials.AuthInfo, error) {
+	return conn, AuthInfo{}, nil
+}
+
+// ServerHandshake extracts the peer identity and fails closed if it cannot be read.
+func (unixCreds) ServerHandshake(conn net.Conn) (net.Conn, credentials.AuthInfo, error) {
+	id, err := PeerIdentity(conn)
+	if err != nil {
+		return nil, nil, err
+	}
+	return conn, AuthInfo{
+		CommonAuthInfo: credentials.CommonAuthInfo{SecurityLevel: credentials.NoSecurity},
+		Identity:       id,
+	}, nil
+}
+
+func (unixCreds) Info() credentials.ProtocolInfo {
+	return credentials.ProtocolInfo{SecurityProtocol: "netbird-ipc-peercred"}
+}
+
+func (unixCreds) Clone() credentials.TransportCredentials { return unixCreds{} }
+
+func (unixCreds) OverrideServerName(string) error { return nil }

client/internal/ipcauth/creds_windows.go

@@ -0,0 +1,142 @@
+//go:build windows
+
+package ipcauth
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"runtime"
+
+	"golang.org/x/sys/windows"
+	"google.golang.org/grpc/credentials"
+)
+
+var (
+	modadvapi32                    = windows.NewLazySystemDLL("advapi32.dll")
+	procImpersonateNamedPipeClient = modadvapi32.NewProc("ImpersonateNamedPipeClient")
+	procRevertToSelf               = modadvapi32.NewProc("RevertToSelf")
+)
+
+// Windows group-SID attribute flags (winnt.h): a group only counts toward
+// membership when it is enabled and not marked use-for-deny-only.
+const (
+	seGroupEnabled        = 0x00000004
+	seGroupUseForDenyOnly = 0x00000010
+)
+
+// DefaultPipeSDDL restricts the daemon control pipe to LocalSystem (SY), the
+// Administrators group (BA), and interactive logon users (IU). It deliberately
+// excludes Authenticated Users / Everyone so remote or arbitrary service
+// principals cannot connect. This is the Layer-1 channel gate; the interceptor
+// (Layer 2) further restricts by per-profile ownership.
+func DefaultPipeSDDL() string {
+	return "D:P(A;;GA;;;SY)(A;;GA;;;BA)(A;;GA;;;IU)"
+}
+
+// NewTransportCredentials returns gRPC transport credentials that derive the
+// caller's identity from the named-pipe client token, following Microsoft's
+// "Verifying Client Access with ACLs" pattern: ImpersonateNamedPipeClient ->
+// OpenThreadToken -> RevertToSelf. Per threat-model M-NOIMP, impersonation is
+// used only to read the client token for identity, never to perform privileged work.
+func NewTransportCredentials() credentials.TransportCredentials {
+	return winpipeCreds{}
+}
+
+type winpipeCreds struct{}
+
+func (winpipeCreds) ClientHandshake(_ context.Context, _ string, conn net.Conn) (net.Conn, credentials.AuthInfo, error) {
+	return conn, AuthInfo{}, nil
+}
+
+// ServerHandshake extracts the connecting client's identity from the pipe token.
+// Fails closed if the handle or token cannot be read.
+func (winpipeCreds) ServerHandshake(conn net.Conn) (net.Conn, credentials.AuthInfo, error) {
+	// go-winio's pipe connection embeds *win32File, which exposes Fd().
+	fdConn, ok := conn.(interface{ Fd() uintptr })
+	if !ok {
+		return nil, nil, fmt.Errorf("connection %T does not expose a pipe handle", conn)
+	}
+	handle := windows.Handle(fdConn.Fd())
+
+	id, err := pipeClientIdentity(handle)
+	if err != nil {
+		return nil, nil, err
+	}
+	return conn, AuthInfo{
+		CommonAuthInfo: credentials.CommonAuthInfo{SecurityLevel: credentials.NoSecurity},
+		Identity:       id,
+	}, nil
+}
+
+func (winpipeCreds) Info() credentials.ProtocolInfo {
+	return credentials.ProtocolInfo{SecurityProtocol: "netbird-ipc-peercred"}
+}
+
+func (winpipeCreds) Clone() credentials.TransportCredentials { return winpipeCreds{} }
+
+func (winpipeCreds) OverrideServerName(string) error { return nil }
+
+// pipeClientIdentity reads the connecting client's user SID and enabled group
+// SIDs from the named-pipe handle. The impersonation window is kept as small as
+// possible and pinned to the OS thread (impersonation is thread-local).
+func pipeClientIdentity(handle windows.Handle) (Identity, error) {
+	var pid uint32
+	hasPID := windows.GetNamedPipeClientProcessId(handle, &pid) == nil
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	if err := impersonateNamedPipeClient(handle); err != nil {
+		return Identity{}, fmt.Errorf("impersonate named pipe client: %w", err)
+	}
+	defer func() { _ = revertToSelf() }()
+
+	// openAsSelf=true: the token is opened using the daemon's process context
+	// (LocalSystem), not the impersonated client's, so the open always succeeds.
+	var token windows.Token
+	if err := windows.OpenThreadToken(windows.CurrentThread(), windows.TOKEN_QUERY, true, &token); err != nil {
+		return Identity{}, fmt.Errorf("open thread token: %w", err)
+	}
+	defer token.Close()
+
+	tu, err := token.GetTokenUser()
+	if err != nil {
+		return Identity{}, fmt.Errorf("get token user: %w", err)
+	}
+
+	tg, err := token.GetTokenGroups()
+	if err != nil {
+		return Identity{}, fmt.Errorf("get token groups: %w", err)
+	}
+	var groups []string
+	for _, g := range tg.AllGroups() {
+		if g.Attributes&seGroupEnabled == 0 || g.Attributes&seGroupUseForDenyOnly != 0 {
+			continue
+		}
+		groups = append(groups, g.Sid.String())
+	}
+
+	return Identity{
+		SID:    tu.User.Sid.String(),
+		Groups: groups,
+		PID:    int32(pid),
+		HasPID: hasPID,
+	}, nil
+}
+
+func impersonateNamedPipeClient(h windows.Handle) error {
+	r, _, e := procImpersonateNamedPipeClient.Call(uintptr(h))
+	if r == 0 {
+		return e
+	}
+	return nil
+}
+
+func revertToSelf() error {
+	r, _, e := procRevertToSelf.Call()
+	if r == 0 {
+		return e
+	}
+	return nil
+}

client/internal/ipcauth/identity.go

@@ -0,0 +1,93 @@
+// Package ipcauth provides kernel-authenticated caller identity for the daemon's
+// local IPC (gRPC) channel and the transport credentials that populate it.
+//
+// It is the identity foundation shared by two layers of the local-IPC hardening:
+//   - the socket-permission layer (Layer 1, client/cmd), which reads the peer
+//     identity to gate who may connect and to run trust-on-first-use; and
+//   - the per-RPC authorization interceptor (Layer 2), which reads the same
+//     identity from the gRPC context to enforce per-profile ownership.
+//
+// On Unix the identity is read from the kernel via SO_PEERCRED (Linux) or
+// LOCAL_PEERCRED (Darwin/FreeBSD). On Windows it is derived from the named-pipe
+// client token. Platforms without a peer-identity primitive get no credentials
+// and therefore no enforcement (the daemon logs a warning and stays open,
+// preserving today's behavior until the transport is hardened).
+package ipcauth
+
+import (
+	"context"
+	"fmt"
+
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/peer"
+)
+
+// Identity is the kernel-authenticated identity of a local IPC caller.
+//
+// The zero value is not a valid identity; callers obtain one via
+// IdentityFromContext (which reports presence) or PeerIdentity.
+type Identity struct {
+	// UID and GID are the caller's Unix user ID and primary group ID.
+	// Zero on Windows, where SID is authoritative instead.
+	UID uint32
+	GID uint32
+
+	// PID is the caller's process ID, for audit only. HasPID is false when the
+	// platform cannot supply it (e.g. Darwin/FreeBSD xucred carries no PID).
+	PID    int32
+	HasPID bool
+
+	// SID is the caller's Windows security identifier (empty on Unix).
+	SID string
+
+	// Groups holds the caller's Windows group SIDs, captured from the client
+	// token at handshake time (empty on Unix, where supplementary group
+	// membership is resolved on demand via NSS/getent by the authorizer).
+	Groups []string
+}
+
+// IsWindows reports whether this identity is a Windows principal (SID-based)
+// rather than a Unix uid/gid principal.
+func (i Identity) IsWindows() bool {
+	return i.SID != ""
+}
+
+// String renders the identity for audit logs.
+func (i Identity) String() string {
+	if i.IsWindows() {
+		if i.HasPID {
+			return fmt.Sprintf("sid=%s pid=%d", i.SID, i.PID)
+		}
+		return fmt.Sprintf("sid=%s", i.SID)
+	}
+	if i.HasPID {
+		return fmt.Sprintf("uid=%d gid=%d pid=%d", i.UID, i.GID, i.PID)
+	}
+	return fmt.Sprintf("uid=%d gid=%d", i.UID, i.GID)
+}
+
+// AuthInfo carries the peer Identity as a gRPC credentials.AuthInfo so the
+// interceptor can retrieve it from the request context via IdentityFromContext.
+type AuthInfo struct {
+	credentials.CommonAuthInfo
+	Identity Identity
+}
+
+// AuthType identifies the authentication scheme.
+func (AuthInfo) AuthType() string { return "netbird-ipc-peercred" }
+
+// IdentityFromContext extracts the caller's kernel-authenticated identity from
+// the gRPC peer context. The second return value is false when no IPC transport
+// credentials were negotiated (e.g. an unsupported platform, or a caller that
+// did not come through the daemon socket) — callers MUST fail closed in that case.
+func IdentityFromContext(ctx context.Context) (Identity, bool) {
+	p, ok := peer.FromContext(ctx)
+	if !ok {
+		return Identity{}, false
+	}
+	info, ok := p.AuthInfo.(AuthInfo)
+	if !ok {
+		return Identity{}, false
+	}
+	return info.Identity, true
+}

client/internal/ipcauth/identity_test.go

@@ -0,0 +1,47 @@
+package ipcauth
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/peer"
+)
+
+func TestIdentityFromContext_NoPeer(t *testing.T) {
+	_, ok := IdentityFromContext(context.Background())
+	assert.False(t, ok, "bare context must report no identity (fail closed)")
+}
+
+func TestIdentityFromContext_WrongAuthInfo(t *testing.T) {
+	ctx := peer.NewContext(context.Background(), &peer.Peer{})
+	_, ok := IdentityFromContext(ctx)
+	assert.False(t, ok, "peer without our AuthInfo must report no identity")
+}
+
+func TestIdentityFromContext_Present(t *testing.T) {
+	want := Identity{UID: 1000, GID: 1000, PID: 4242, HasPID: true}
+	ctx := peer.NewContext(context.Background(), &peer.Peer{
+		AuthInfo: AuthInfo{
+			CommonAuthInfo: credentials.CommonAuthInfo{SecurityLevel: credentials.NoSecurity},
+			Identity:       want,
+		},
+	})
+
+	got, ok := IdentityFromContext(ctx)
+	assert.True(t, ok)
+	assert.Equal(t, want, got)
+}
+
+func TestIdentity_String(t *testing.T) {
+	assert.Equal(t, "uid=1000 gid=1000 pid=42", Identity{UID: 1000, GID: 1000, PID: 42, HasPID: true}.String())
+	assert.Equal(t, "uid=1000 gid=1000", Identity{UID: 1000, GID: 1000}.String())
+	assert.Equal(t, "sid=S-1-5-21-1 pid=42", Identity{SID: "S-1-5-21-1", PID: 42, HasPID: true}.String())
+	assert.Equal(t, "sid=S-1-5-21-1", Identity{SID: "S-1-5-21-1"}.String())
+}
+
+func TestIdentity_IsWindows(t *testing.T) {
+	assert.True(t, Identity{SID: "S-1-5-18"}.IsWindows())
+	assert.False(t, Identity{UID: 0}.IsWindows())
+}

client/internal/ipcauth/peercred_bsd.go

@@ -0,0 +1,43 @@
+//go:build darwin || freebsd
+
+package ipcauth
+
+import (
+	"fmt"
+	"net"
+
+	"golang.org/x/sys/unix"
+)
+
+// PeerIdentity reads the kernel-authenticated identity of the process on the
+// other end of a Unix socket connection via LOCAL_PEERCRED (xucred). xucred
+// carries the uid and group list but no pid, so audit on these platforms is
+// uid/gid-based (HasPID is false); PID via LOCAL_PEERPID is a possible follow-up.
+func PeerIdentity(c net.Conn) (Identity, error) {
+	uc, ok := c.(*net.UnixConn)
+	if !ok {
+		return Identity{}, fmt.Errorf("connection is not a unix socket: %T", c)
+	}
+	raw, err := uc.SyscallConn()
+	if err != nil {
+		return Identity{}, fmt.Errorf("raw conn: %w", err)
+	}
+
+	var cred *unix.Xucred
+	var credErr error
+	if err := raw.Control(func(fd uintptr) {
+		cred, credErr = unix.GetsockoptXucred(int(fd), unix.SOL_LOCAL, unix.LOCAL_PEERCRED)
+	}); err != nil {
+		return Identity{}, fmt.Errorf("getsockopt control: %w", err)
+	}
+	if credErr != nil {
+		return Identity{}, fmt.Errorf("LOCAL_PEERCRED: %w", credErr)
+	}
+
+	id := Identity{UID: cred.Uid}
+	// Groups[0] is the effective (primary) GID; guard against an empty list.
+	if cred.Ngroups > 0 {
+		id.GID = cred.Groups[0]
+	}
+	return id, nil
+}

client/internal/ipcauth/peercred_linux.go

@@ -0,0 +1,43 @@
+//go:build linux
+
+package ipcauth
+
+import (
+	"fmt"
+	"net"
+
+	"golang.org/x/sys/unix"
+)
+
+// PeerIdentity reads the kernel-authenticated identity of the process on the
+// other end of a Unix socket connection via SO_PEERCRED. The credentials are
+// captured by the kernel at connect() time and cannot be spoofed or changed for
+// the life of the connection.
+func PeerIdentity(c net.Conn) (Identity, error) {
+	uc, ok := c.(*net.UnixConn)
+	if !ok {
+		return Identity{}, fmt.Errorf("connection is not a unix socket: %T", c)
+	}
+	raw, err := uc.SyscallConn()
+	if err != nil {
+		return Identity{}, fmt.Errorf("raw conn: %w", err)
+	}
+
+	var cred *unix.Ucred
+	var credErr error
+	if err := raw.Control(func(fd uintptr) {
+		cred, credErr = unix.GetsockoptUcred(int(fd), unix.SOL_SOCKET, unix.SO_PEERCRED)
+	}); err != nil {
+		return Identity{}, fmt.Errorf("getsockopt control: %w", err)
+	}
+	if credErr != nil {
+		return Identity{}, fmt.Errorf("SO_PEERCRED: %w", credErr)
+	}
+
+	return Identity{
+		UID:    cred.Uid,
+		GID:    cred.Gid,
+		PID:    cred.Pid,
+		HasPID: true,
+	}, nil
+}

client/internal/ipcauth/peercred_stub.go

@@ -0,0 +1,16 @@
+//go:build !linux && !darwin && !freebsd
+
+package ipcauth
+
+import (
+	"fmt"
+	"net"
+	"runtime"
+)
+
+// PeerIdentity is unimplemented on platforms without a Unix-socket peer-credential
+// primitive. Windows derives identity from the named-pipe client token instead
+// (see the Windows transport credentials), so it never calls this.
+func PeerIdentity(net.Conn) (Identity, error) {
+	return Identity{}, fmt.Errorf("peer credential check not supported on %s", runtime.GOOS)
+}

client/internal/ipcauth/peercred_unix_test.go

@@ -0,0 +1,113 @@
+//go:build linux || darwin || freebsd
+
+package ipcauth
+
+import (
+	"net"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// TestPeerIdentity_MatchesCurrentProcess connects to a real Unix socket and
+// verifies the extracted UID/GID match the running process (both ends are us).
+func TestPeerIdentity_MatchesCurrentProcess(t *testing.T) {
+	sock := filepath.Join(t.TempDir(), "peer.sock")
+	ln, err := net.Listen("unix", sock)
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = ln.Close() })
+
+	type result struct {
+		id  Identity
+		err error
+	}
+	done := make(chan result, 1)
+	go func() {
+		c, aerr := ln.Accept()
+		if aerr != nil {
+			done <- result{err: aerr}
+			return
+		}
+		defer func() { _ = c.Close() }()
+		id, ierr := PeerIdentity(c)
+		done <- result{id: id, err: ierr}
+	}()
+
+	client, err := net.Dial("unix", sock)
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = client.Close() })
+
+	res := <-done
+	require.NoError(t, res.err)
+	assert.Equal(t, uint32(os.Getuid()), res.id.UID, "UID should match current process")
+	assert.Equal(t, uint32(os.Getgid()), res.id.GID, "primary GID should match current process")
+}
+
+// TestPeerIdentity_NonUnixConn rejects non-Unix connections (fail closed).
+func TestPeerIdentity_NonUnixConn(t *testing.T) {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = ln.Close() })
+
+	done := make(chan error, 1)
+	go func() {
+		c, aerr := ln.Accept()
+		if aerr != nil {
+			done <- aerr
+			return
+		}
+		defer func() { _ = c.Close() }()
+		_, ierr := PeerIdentity(c)
+		done <- ierr
+	}()
+
+	client, err := net.Dial("tcp", ln.Addr().String())
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = client.Close() })
+
+	assert.Error(t, <-done, "PeerIdentity must reject a non-Unix connection")
+}
+
+// TestUnixCreds_ServerHandshake exercises the transport-credentials path end to end.
+func TestUnixCreds_ServerHandshake(t *testing.T) {
+	creds := NewTransportCredentials()
+	require.NotNil(t, creds)
+
+	sock := filepath.Join(t.TempDir(), "hs.sock")
+	ln, err := net.Listen("unix", sock)
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = ln.Close() })
+
+	type result struct {
+		info interface{ AuthType() string }
+		err  error
+	}
+	done := make(chan result, 1)
+	go func() {
+		c, aerr := ln.Accept()
+		if aerr != nil {
+			done <- result{err: aerr}
+			return
+		}
+		_, ai, herr := creds.ServerHandshake(c)
+		if herr != nil {
+			done <- result{err: herr}
+			return
+		}
+		done <- result{info: ai}
+	}()
+
+	client, err := net.Dial("unix", sock)
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = client.Close() })
+
+	res := <-done
+	require.NoError(t, res.err)
+	ai, ok := res.info.(AuthInfo)
+	require.True(t, ok, "expected ipcauth.AuthInfo, got %T", res.info)
+	assert.Equal(t, uint32(os.Getuid()), ai.Identity.UID)
+	assert.Equal(t, "netbird-ipc-peercred", ai.AuthType())
+}