Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Alternative route table and 0.0.0.0 routing #1324

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Alternative route table and 0.0.0.0 routing #1324

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
3 changes: 3 additions & 0 deletions examples/config.yml
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -243,6 +243,9 @@ tun:
# On linux only, set to true to manage unsafe routes directly on the system route table with gateway routes instead of
# in nebula configuration files. Default false, not reloadable.
#use_system_route_table: false
# Specify the alternative routing table for created routes.
# If unset, defaults to main routing table.
#alternative_routing_table: "my_alt_table"

# TODO
# Configure logging level
Expand Down
130 changes: 100 additions & 30 deletions overlay/tun_linux.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@ import (
"net"
"net/netip"
"os"
"strconv"
"strings"
"sync/atomic"
"unsafe"
Expand Down Expand Up @@ -36,6 +37,7 @@ type tun struct {
routeTree atomic.Pointer[bart.Table[netip.Addr]]
routeChan chan struct{}
useSystemRoutes bool
alternativeRoutingTable string // New field for alternative routing table

l *logrus.Logger
}
Expand Down Expand Up @@ -125,11 +127,12 @@ func newTun(c *config.C, l *logrus.Logger, cidr netip.Prefix, multiqueue bool) (
func newTunGeneric(c *config.C, l *logrus.Logger, file *os.File, cidr netip.Prefix) (*tun, error) {
t := &tun{
ReadWriteCloser: file,
fd: int(file.Fd()),
cidr: cidr,
TXQueueLen: c.GetInt("tun.tx_queue", 500),
fd: int(file.Fd()),
cidr: cidr,
TXQueueLen: c.GetInt("tun.tx_queue", 500),
useSystemRoutes: c.GetBool("tun.use_system_route_table", false),
l: l,
alternativeRoutingTable: c.GetString("tun.alternative_routing_table", ""),
l: l,
}

err := t.reload(c, true)
Expand All @@ -147,16 +150,58 @@ func newTunGeneric(c *config.C, l *logrus.Logger, file *os.File, cidr netip.Pref
return t, nil
}

func (t *tun) getRoutingTableID() (int, error) {
if t.alternativeRoutingTable == "" {
return unix.RT_TABLE_MAIN, nil
}

// Try parsing as a number first
if tableID, err := strconv.Atoi(t.alternativeRoutingTable); err == nil {
return tableID, nil
}

// If it's not a number, look up the table name in /etc/iproute2/rt_tables
content, err := os.ReadFile("/etc/iproute2/rt_tables")
if err != nil {
return 0, fmt.Errorf("failed to read routing tables: %w", err)
}

lines := strings.Split(string(content), "\n")
for _, line := range lines {
line = strings.TrimSpace(line)
if line == "" || strings.HasPrefix(line, "#") {
continue
}

fields := strings.Fields(line)
if len(fields) >= 2 && fields[1] == t.alternativeRoutingTable {
tableID, err := strconv.Atoi(fields[0])
if err != nil {
continue
}
return tableID, nil
}
}

return 0, fmt.Errorf("routing table %s not found", t.alternativeRoutingTable)
}

func (t *tun) reload(c *config.C, initial bool) error {
routeChange, routes, err := getAllRoutesFromConfig(c, t.cidr, initial)
if err != nil {
return err
}

if !initial && !routeChange && !c.HasChanged("tun.mtu") {
if !initial && !routeChange && !c.HasChanged("tun.mtu") && !c.HasChanged("tun.alternative_routing_table") {
return nil
}

// Update alternative routing table if changed
if !initial && c.HasChanged("tun.alternative_routing_table") {
t.alternativeRoutingTable = c.GetString("tun.alternative_routing_table", "")
t.l.Infof("Alternative routing table changed to %s", t.alternativeRoutingTable)
}

routeTree, err := makeRouteTree(t.l, routes, true)
if err != nil {
return err
Expand Down Expand Up @@ -274,7 +319,6 @@ func (t *tun) Activate() error {

var addr, mask [4]byte

//TODO: IPV6-WORK
addr = t.cidr.Addr().As4()
tmask := net.CIDRMask(t.cidr.Bits(), 32)
copy(mask[:], tmask)
Expand Down Expand Up @@ -364,7 +408,11 @@ func (t *tun) setMTU() {
}

func (t *tun) setDefaultRoute() error {
// Default route
// Get the routing table ID
tableID, err := t.getRoutingTableID()
if err != nil {
return fmt.Errorf("failed to get routing table ID: %w", err)
}

dr := &net.IPNet{
IP: t.cidr.Masked().Addr().AsSlice(),
Expand All @@ -379,10 +427,11 @@ func (t *tun) setDefaultRoute() error {
Scope: unix.RT_SCOPE_LINK,
Src: net.IP(t.cidr.Addr().AsSlice()),
Protocol: unix.RTPROT_KERNEL,
Table: unix.RT_TABLE_MAIN,
Table: tableID,
Type: unix.RTN_UNICAST,
}
err := netlink.RouteReplace(&nr)

err = netlink.RouteReplace(&nr)
if err != nil {
return fmt.Errorf("failed to set mtu %v on the default route %v; %v", t.DefaultMTU, dr, err)
}
Expand All @@ -391,7 +440,12 @@ func (t *tun) setDefaultRoute() error {
}

func (t *tun) addRoutes(logErrors bool) error {
// Path routes
// Get the routing table ID
tableID, err := t.getRoutingTableID()
if err != nil {
return fmt.Errorf("failed to get routing table ID: %w", err)
}

routes := *t.Routes.Load()
for _, r := range routes {
if !r.Install {
Expand All @@ -409,6 +463,7 @@ func (t *tun) addRoutes(logErrors bool) error {
MTU: r.MTU,
AdvMSS: t.advMSS(r),
Scope: unix.RT_SCOPE_LINK,
Table: tableID,
}

if r.Metric > 0 {
Expand All @@ -417,21 +472,31 @@ func (t *tun) addRoutes(logErrors bool) error {

err := netlink.RouteReplace(&nr)
if err != nil {
retErr := util.NewContextualError("Failed to add route", map[string]interface{}{"route": r}, err)
retErr := util.NewContextualError("Failed to add route", map[string]interface{}{
"route": r,
"table": t.alternativeRoutingTable,
}, err)
if logErrors {
retErr.Log(t.l)
} else {
return retErr
}
} else {
t.l.WithField("route", r).Info("Added route")
t.l.WithField("route", r).WithField("table", t.alternativeRoutingTable).Info("Added route")
}
}

return nil
}

func (t *tun) removeRoutes(routes []Route) {
// Get the routing table ID
tableID, err := t.getRoutingTableID()
if err != nil {
t.l.WithError(err).Error("Failed to get routing table ID")
return
}

for _, r := range routes {
if !r.Install {
continue
Expand All @@ -448,6 +513,7 @@ func (t *tun) removeRoutes(routes []Route) {
MTU: r.MTU,
AdvMSS: t.advMSS(r),
Scope: unix.RT_SCOPE_LINK,
Table: tableID,
}

if r.Metric > 0 {
Expand All @@ -456,9 +522,9 @@ func (t *tun) removeRoutes(routes []Route) {

err := netlink.RouteDel(&nr)
if err != nil {
t.l.WithError(err).WithField("route", r).Error("Failed to remove route")
t.l.WithError(err).WithField("route", r).WithField("table", t.alternativeRoutingTable).Error("Failed to remove route")
} else {
t.l.WithField("route", r).Info("Removed route")
t.l.WithField("route", r).WithField("table", t.alternativeRoutingTable).Info("Removed route")
}
}
}
Expand Down Expand Up @@ -515,7 +581,6 @@ func (t *tun) updateRoutes(r netlink.RouteUpdate) {
return
}

//TODO: IPV6-WORK what if not ok?
gwAddr, ok := netip.AddrFromSlice(r.Gw)
if !ok {
t.l.WithField("route", r).Debug("Ignoring route update, invalid gateway address")
Expand All @@ -529,30 +594,35 @@ func (t *tun) updateRoutes(r netlink.RouteUpdate) {
return
}

if x := r.Dst.IP.To4(); x == nil {
// Nebula only handles ipv4 on the overlay currently
t.l.WithField("route", r).Debug("Ignoring route update, destination is not ipv4")
return
}
var dst netip.Prefix
if r.Dst == nil || r.Dst.IP == nil {
// This is a default route (0.0.0.0/0)
dst = netip.PrefixFrom(netip.IPv4Unspecified(), 0)
} else {
if x := r.Dst.IP.To4(); x == nil {
// Nebula only handles ipv4 on the overlay currently
t.l.WithField("route", r).Debug("Ignoring route update, destination is not ipv4")
return
}

dstAddr, ok := netip.AddrFromSlice(r.Dst.IP)
if !ok {
t.l.WithField("route", r).Debug("Ignoring route update, invalid destination address")
return
}
dstAddr, ok := netip.AddrFromSlice(r.Dst.IP)
if !ok {
t.l.WithField("route", r).Debug("Ignoring route update, invalid destination address")
return
}

ones, _ := r.Dst.Mask.Size()
dst := netip.PrefixFrom(dstAddr, ones)
ones, _ := r.Dst.Mask.Size()
dst = netip.PrefixFrom(dstAddr, ones)
}

newTree := t.routeTree.Load().Clone()

if r.Type == unix.RTM_NEWROUTE {
t.l.WithField("destination", r.Dst).WithField("via", r.Gw).Info("Adding route")
t.l.WithField("destination", dst).WithField("via", gwAddr).Info("Adding route")
newTree.Insert(dst, gwAddr)

} else {
newTree.Delete(dst)
t.l.WithField("destination", r.Dst).WithField("via", r.Gw).Info("Removing route")
t.l.WithField("destination", dst).WithField("via", gwAddr).Info("Removing route")
}
t.routeTree.Store(newTree)
}
Expand Down