policy/policyutil: exclude exit routes from ReduceFilterRules

Exit nodes handle traffic via AllowedIPs/routing, not packet filter
rules. Skip exit routes (0.0.0.0/0, ::/0) when checking RoutableIPs
overlap in ReduceFilterRules, matching Tailscale SaaS behavior where
exit nodes do not receive filter rules for destinations that only
overlap via exit routes.

Updates #2180
This commit is contained in:
Kristoffer Dalby
2026-03-18 14:40:12 +00:00
parent 9e0e77c90d
commit 044f3fc0ec
2 changed files with 14 additions and 32 deletions

View File

@@ -3,6 +3,7 @@ package policyutil
import (
"github.com/juanfont/headscale/hscontrol/types"
"github.com/juanfont/headscale/hscontrol/util"
"tailscale.com/net/tsaddr"
"tailscale.com/tailcfg"
)
@@ -33,12 +34,19 @@ func ReduceFilterRules(node types.NodeView, rules []tailcfg.FilterRule) []tailcf
continue DEST_LOOP
}
// If the node exposes routes, ensure they are note removed
// when the filters are reduced.
// If the node exposes routes, ensure they are not removed
// when the filters are reduced. Exit routes (0.0.0.0/0, ::/0)
// are skipped here because exit nodes handle traffic via
// AllowedIPs/routing, not packet filter rules. This matches
// Tailscale SaaS behavior where exit nodes do not receive
// filter rules for destinations that only overlap via exit routes.
if node.Hostinfo().Valid() {
routableIPs := node.Hostinfo().RoutableIPs()
if routableIPs.Len() > 0 {
for _, routableIP := range routableIPs.All() {
if tsaddr.IsExitRoute(routableIP) {
continue
}
if expanded.OverlapsPrefix(routableIP) {
dests = append(dests, dest)
continue DEST_LOOP

View File

@@ -453,7 +453,10 @@ func TestReduceFilterRules(t *testing.T) {
},
},
want: []tailcfg.FilterRule{
// Merged: Both ACL rules combined (same SrcIPs)
// Exit routes (0.0.0.0/0, ::/0) are skipped when checking RoutableIPs
// overlap, matching Tailscale SaaS behavior. Only destinations that
// contain the node's own Tailscale IP (via InIPSet) are kept.
// Here, 64.0.0.0/2 contains 100.64.0.100 (CGNAT range), so it matches.
{
SrcIPs: []string{
"100.64.0.1-100.64.0.2",
@@ -464,36 +467,7 @@ func TestReduceFilterRules(t *testing.T) {
IP: "100.64.0.100",
Ports: tailcfg.PortRangeAny,
},
{IP: "0.0.0.0/5", Ports: tailcfg.PortRangeAny},
{IP: "8.0.0.0/7", Ports: tailcfg.PortRangeAny},
{IP: "11.0.0.0/8", Ports: tailcfg.PortRangeAny},
{IP: "12.0.0.0/6", Ports: tailcfg.PortRangeAny},
{IP: "16.0.0.0/4", Ports: tailcfg.PortRangeAny},
{IP: "32.0.0.0/3", Ports: tailcfg.PortRangeAny},
{IP: "64.0.0.0/2", Ports: tailcfg.PortRangeAny},
{IP: "128.0.0.0/3", Ports: tailcfg.PortRangeAny},
{IP: "160.0.0.0/5", Ports: tailcfg.PortRangeAny},
{IP: "168.0.0.0/6", Ports: tailcfg.PortRangeAny},
{IP: "172.0.0.0/12", Ports: tailcfg.PortRangeAny},
{IP: "172.32.0.0/11", Ports: tailcfg.PortRangeAny},
{IP: "172.64.0.0/10", Ports: tailcfg.PortRangeAny},
{IP: "172.128.0.0/9", Ports: tailcfg.PortRangeAny},
{IP: "173.0.0.0/8", Ports: tailcfg.PortRangeAny},
{IP: "174.0.0.0/7", Ports: tailcfg.PortRangeAny},
{IP: "176.0.0.0/4", Ports: tailcfg.PortRangeAny},
{IP: "192.0.0.0/9", Ports: tailcfg.PortRangeAny},
{IP: "192.128.0.0/11", Ports: tailcfg.PortRangeAny},
{IP: "192.160.0.0/13", Ports: tailcfg.PortRangeAny},
{IP: "192.169.0.0/16", Ports: tailcfg.PortRangeAny},
{IP: "192.170.0.0/15", Ports: tailcfg.PortRangeAny},
{IP: "192.172.0.0/14", Ports: tailcfg.PortRangeAny},
{IP: "192.176.0.0/12", Ports: tailcfg.PortRangeAny},
{IP: "192.192.0.0/10", Ports: tailcfg.PortRangeAny},
{IP: "193.0.0.0/8", Ports: tailcfg.PortRangeAny},
{IP: "194.0.0.0/7", Ports: tailcfg.PortRangeAny},
{IP: "196.0.0.0/6", Ports: tailcfg.PortRangeAny},
{IP: "200.0.0.0/5", Ports: tailcfg.PortRangeAny},
{IP: "208.0.0.0/4", Ports: tailcfg.PortRangeAny},
},
},
},