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policy: take RLock for reads so map generation runs concurrently

Browse source 
One exclusive mutex serialized every policy read, so a mass reconnect on
autogroup:self/via/relay policies stalled clients into "unexpected EOF"
retries. Per-node caches become xsync.Maps for lazy population under RLock.

Fixes #3346

(cherry picked from commit 6f317c7576)
This commit is contained in:
Kristoffer Dalby 2026-07-01 09:40:21 +00:00
parent 636f660caf
commit d4f2acf3ab
5 changed files with 98 additions and 74 deletions
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8
CHANGELOG.md
View file

@ -4,6 +4,14 @@
**Minimum supported Tailscale client version: v1.xx.0**
## 0.29.2 (202x-xx-xx)
**Minimum supported Tailscale client version: v1.80.0**
### Changes
- Fix map generation serializing on the policy lock, so a mass reconnect on `autogroup:self`, via or relay policies no longer stalls clients into `unexpected EOF` retry loops [#3358](https://github.com/juanfont/headscale/pull/3358)
## 0.29.1 (2026-06-18)
**Minimum supported Tailscale client version: v1.80.0**

136
hscontrol/policy/v2/policy.go
View file

@ -15,6 +15,7 @@ import (
"github.com/juanfont/headscale/hscontrol/policy/matcher"
"github.com/juanfont/headscale/hscontrol/policy/policyutil"
"github.com/juanfont/headscale/hscontrol/types"
"github.com/puzpuzpuz/xsync/v4"
"github.com/rs/zerolog/log"
"go4.org/netipx"
"tailscale.com/net/tsaddr"
@ -28,7 +29,10 @@ import (
var ErrInvalidTagOwner = errors.New("tag owner is not an Alias")
type PolicyManager struct {
mu sync.Mutex
// RWMutex, not Mutex, so concurrent map generation does not serialise on
// reads. The per-node caches are xsync.Maps so a read can fill them without
// taking the write lock.
mu sync.RWMutex
pol *Policy
users []types.User
nodes views.Slice[types.NodeView]
@ -55,7 +59,7 @@ type PolicyManager struct {
viaTargetTags map[Tag]struct{}
// Lazy map of SSH policies
sshPolicyMap map[types.NodeID]*tailcfg.SSHPolicy
sshPolicyMap *xsync.Map[types.NodeID, *tailcfg.SSHPolicy]
// compiledGrants are the grants with sources pre-resolved.
// The single source of truth for filter compilation. Both
@ -64,12 +68,12 @@ type PolicyManager struct {
userNodeIdx userNodeIndex
// Lazy map of per-node filter rules (reduced, for packet filters)
filterRulesMap map[types.NodeID][]tailcfg.FilterRule
filterRulesMap *xsync.Map[types.NodeID, []tailcfg.FilterRule]
// Lazy map of per-node matchers derived from UNREDUCED filter
// rules. Only populated on the slow path when needsPerNodeFilter
// is true; the fast path returns pm.matchers directly.
matchersForNodeMap map[types.NodeID][]matcher.Match
matchersForNodeMap *xsync.Map[types.NodeID, []matcher.Match]
// needsPerNodeFilter is true when any compiled grant requires
// per-node work (autogroup:self or via grants).
@ -197,9 +201,9 @@ func NewPolicyManager(b []byte, users []types.User, nodes views.Slice[types.Node
pol: policy,
users: users,
nodes: nodes,
sshPolicyMap: make(map[types.NodeID]*tailcfg.SSHPolicy, nodes.Len()),
filterRulesMap: make(map[types.NodeID][]tailcfg.FilterRule, nodes.Len()),
matchersForNodeMap: make(map[types.NodeID][]matcher.Match, nodes.Len()),
sshPolicyMap: xsync.NewMap[types.NodeID, *tailcfg.SSHPolicy](),
filterRulesMap: xsync.NewMap[types.NodeID, []tailcfg.FilterRule](),
matchersForNodeMap: xsync.NewMap[types.NodeID, []matcher.Match](),
}
_, err = pm.updateLocked()
@ -354,9 +358,9 @@ func (pm *PolicyManager) updateLocked() (bool, error) {
// TODO(kradalby): This could potentially be optimized by only clearing the
// policies for nodes that have changed. Particularly if the only difference is
// that nodes has been added or removed.
clear(pm.sshPolicyMap)
clear(pm.filterRulesMap)
clear(pm.matchersForNodeMap)
pm.sshPolicyMap.Clear()
pm.filterRulesMap.Clear()
pm.matchersForNodeMap.Clear()
}
// If nothing changed, no need to update nodes
@ -400,8 +404,8 @@ func (pm *PolicyManager) NodeNeedsPeerRecompute(node types.NodeView) bool {
return true
}
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
if pm.relayTargetIPs != nil && node.InIPSet(pm.relayTargetIPs) {
return true
@ -422,10 +426,10 @@ func (pm *PolicyManager) NodeNeedsPeerRecompute(node types.NodeView) bool {
// /machine/ssh/action/{src}/to/{dst}?local_user={local_user} per the
// SaaS wire format. Cache is invalidated on policy reload.
func (pm *PolicyManager) SSHPolicy(baseURL string, node types.NodeView) (*tailcfg.SSHPolicy, error) {
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
if sshPol, ok := pm.sshPolicyMap[node.ID()]; ok {
if sshPol, ok := pm.sshPolicyMap.Load(node.ID()); ok {
return sshPol, nil
}
@ -434,7 +438,7 @@ func (pm *PolicyManager) SSHPolicy(baseURL string, node types.NodeView) (*tailcf
return nil, fmt.Errorf("compiling SSH policy: %w", err)
}
pm.sshPolicyMap[node.ID()] = sshPol
pm.sshPolicyMap.Store(node.ID(), sshPol)
return sshPol, nil
}
@ -450,8 +454,8 @@ func (pm *PolicyManager) SSHPolicy(baseURL string, node types.NodeView) (*tailcf
func (pm *PolicyManager) SSHCheckParams(
srcNodeID, dstNodeID types.NodeID,
) (time.Duration, bool) {
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
if pm.pol == nil || len(pm.pol.SSHs) == 0 {
return 0, false
@ -584,8 +588,8 @@ func (pm *PolicyManager) Filter() ([]tailcfg.FilterRule, []matcher.Match) {
return nil, nil
}
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
return pm.filter, pm.matchers
}
@ -604,8 +608,8 @@ func (pm *PolicyManager) BuildPeerMap(nodes views.Slice[types.NodeView]) map[typ
return nil
}
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
// Precompute each node's subnet routes and exit-node status once; the
// O(n^2) pair scans below would otherwise recompute them for every pair.
@ -726,7 +730,7 @@ func (pm *PolicyManager) filterForNodeLocked(
return nil
}
if rules, ok := pm.filterRulesMap[node.ID()]; ok {
if rules, ok := pm.filterRulesMap.Load(node.ID()); ok {
return rules
}
@ -738,7 +742,7 @@ func (pm *PolicyManager) filterForNodeLocked(
}
reduced := policyutil.ReduceFilterRules(node, unreduced)
pm.filterRulesMap[node.ID()] = reduced
pm.filterRulesMap.Store(node.ID(), reduced)
return reduced
}
@ -755,8 +759,8 @@ func (pm *PolicyManager) FilterForNode(node types.NodeView) ([]tailcfg.FilterRul
return nil, nil
}
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
return pm.filterForNodeLocked(node), nil
}
@ -776,8 +780,8 @@ func (pm *PolicyManager) MatchersForNode(node types.NodeView) ([]matcher.Match,
return nil, nil
}
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
// For global policies, return the shared global matchers.
// Via grants require per-node matchers because the global matchers
@ -786,7 +790,7 @@ func (pm *PolicyManager) MatchersForNode(node types.NodeView) ([]matcher.Match,
return pm.matchers, nil
}
if cached, ok := pm.matchersForNodeMap[node.ID()]; ok {
if cached, ok := pm.matchersForNodeMap.Load(node.ID()); ok {
return cached, nil
}
@ -794,7 +798,7 @@ func (pm *PolicyManager) MatchersForNode(node types.NodeView) ([]matcher.Match,
// the stored compiled grants for this specific node.
unreduced := pm.filterRulesForNodeLocked(node)
matchers := matcher.MatchesFromFilterRules(unreduced)
pm.matchersForNodeMap[node.ID()] = matchers
pm.matchersForNodeMap.Store(node.ID(), matchers)
return matchers, nil
}
@ -813,7 +817,7 @@ func (pm *PolicyManager) SetUsers(users []types.User) (bool, error) {
// Clear SSH policy map when users change to force SSH policy recomputation
// This ensures that if SSH policy compilation previously failed due to missing users,
// it will be retried with the new user list
clear(pm.sshPolicyMap)
pm.sshPolicyMap.Clear()
changed, err := pm.updateLocked()
if err != nil {
@ -866,9 +870,9 @@ func (pm *PolicyManager) SetNodes(nodes views.Slice[types.NodeView]) (bool, erro
if !needsUpdate {
// This ensures fresh filter rules are generated for all nodes
clear(pm.sshPolicyMap)
clear(pm.filterRulesMap)
clear(pm.matchersForNodeMap)
pm.sshPolicyMap.Clear()
pm.filterRulesMap.Clear()
pm.matchersForNodeMap.Clear()
}
// Always return true when nodes changed, even if filter hash didn't change
// (can happen with autogroup:self or when nodes are added but don't affect rules)
@ -921,8 +925,8 @@ func (pm *PolicyManager) NodeCanHaveTag(node types.NodeView, tag string) bool {
return false
}
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
// pm.pol is written by SetPolicy under pm.mu; reading it before the
// lock races with concurrent policy reloads.
@ -1010,8 +1014,8 @@ func (pm *PolicyManager) TagExists(tag string) bool {
return false
}
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
// pm.pol is written by SetPolicy under pm.mu; reading it before the
// lock races with concurrent policy reloads.
@ -1029,8 +1033,8 @@ func (pm *PolicyManager) NodeCanApproveRoute(node types.NodeView, route netip.Pr
return false
}
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
// If the route to-be-approved is an exit route, then we need to check
// if the node is in allowed to approve it. This is treated differently
@ -1092,8 +1096,8 @@ func (pm *PolicyManager) ViaRoutesForPeer(viewer, peer types.NodeView) types.Via
return result
}
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
// pm.pol is written by SetPolicy under pm.mu; reading it before the
// lock races with concurrent policy reloads.
@ -1311,8 +1315,8 @@ func (pm *PolicyManager) DebugString() string {
// pm.pol, filter, matchers, and the derived maps are all written
// under pm.mu by SetPolicy/SetUsers/SetNodes.
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
var sb strings.Builder
@ -1475,7 +1479,7 @@ func (pm *PolicyManager) invalidateAutogroupSelfCache(oldNodes, newNodes views.S
// Clear cache entries for affected users only.
// For autogroup:self, we need to clear all nodes belonging to affected users
// because autogroup:self rules depend on the entire user's device set.
for nodeID := range pm.filterRulesMap {
pm.filterRulesMap.Range(func(nodeID types.NodeID, _ []tailcfg.FilterRule) bool {
// Find the user for this cached node
var nodeUserID types.UserID
@ -1518,20 +1522,22 @@ func (pm *PolicyManager) invalidateAutogroupSelfCache(oldNodes, newNodes views.S
// If we found the user and they're affected, clear this cache entry
if found {
if _, affected := affectedUsers[nodeUserID]; affected {
delete(pm.filterRulesMap, nodeID)
delete(pm.matchersForNodeMap, nodeID)
pm.filterRulesMap.Delete(nodeID)
pm.matchersForNodeMap.Delete(nodeID)
}
} else {
// Node not found in either old or new list, clear it
delete(pm.filterRulesMap, nodeID)
delete(pm.matchersForNodeMap, nodeID)
pm.filterRulesMap.Delete(nodeID)
pm.matchersForNodeMap.Delete(nodeID)
}
}
return true
})
if len(affectedUsers) > 0 {
log.Debug().
Int("affected_users", len(affectedUsers)).
Int("remaining_cache_entries", len(pm.filterRulesMap)).
Int("remaining_cache_entries", pm.filterRulesMap.Size()).
Msg("Selectively cleared autogroup:self cache for affected users")
}
}
@ -1572,23 +1578,27 @@ func (pm *PolicyManager) invalidateGlobalPolicyCache(newNodes views.Slice[types.
}
if newNode.HasNetworkChanges(oldNode) {
delete(pm.filterRulesMap, nodeID)
delete(pm.matchersForNodeMap, nodeID)
pm.filterRulesMap.Delete(nodeID)
pm.matchersForNodeMap.Delete(nodeID)
}
}
// Remove deleted nodes from cache
for nodeID := range pm.filterRulesMap {
pm.filterRulesMap.Range(func(nodeID types.NodeID, _ []tailcfg.FilterRule) bool {
if _, exists := newNodeMap[nodeID]; !exists {
delete(pm.filterRulesMap, nodeID)
pm.filterRulesMap.Delete(nodeID)
}
}
for nodeID := range pm.matchersForNodeMap {
return true
})
pm.matchersForNodeMap.Range(func(nodeID types.NodeID, _ []matcher.Match) bool {
if _, exists := newNodeMap[nodeID]; !exists {
delete(pm.matchersForNodeMap, nodeID)
pm.matchersForNodeMap.Delete(nodeID)
}
}
return true
})
}
// flattenTags resolves nested tag-owner references. Cycles
@ -1770,8 +1780,8 @@ func (pm *PolicyManager) NodeCapMap(id types.NodeID) tailcfg.NodeCapMap {
return nil
}
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
src := pm.nodeAttrsMap[id]
if len(src) == 0 {
@ -1794,8 +1804,8 @@ func (pm *PolicyManager) NodeCapMaps() map[types.NodeID]tailcfg.NodeCapMap {
return nil
}
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
out := make(map[types.NodeID]tailcfg.NodeCapMap, len(pm.nodeAttrsMap))
maps.Copy(out, pm.nodeAttrsMap)

20
hscontrol/policy/v2/policy_test.go
View file

@ -8,6 +8,7 @@ import (
"github.com/google/go-cmp/cmp"
"github.com/juanfont/headscale/hscontrol/policy/matcher"
"github.com/juanfont/headscale/hscontrol/types"
"github.com/puzpuzpuz/xsync/v4"
"github.com/stretchr/testify/require"
"gorm.io/gorm"
"tailscale.com/net/tsaddr"
@ -122,7 +123,7 @@ func TestInvalidateAutogroupSelfCache(t *testing.T) {
require.NoError(t, err)
}
require.Len(t, pm.filterRulesMap, len(initialNodes))
require.Equal(t, len(initialNodes), pm.filterRulesMap.Size())
tests := []struct {
name string
@ -207,19 +208,20 @@ func TestInvalidateAutogroupSelfCache(t *testing.T) {
}
}
pm.filterRulesMap = make(map[types.NodeID][]tailcfg.FilterRule)
pm.filterRulesMap.Clear()
for _, n := range initialNodes {
_, err := pm.FilterForNode(n.View())
require.NoError(t, err)
}
initialCacheSize := len(pm.filterRulesMap)
initialCacheSize := pm.filterRulesMap.Size()
require.Equal(t, len(initialNodes), initialCacheSize)
pm.invalidateAutogroupSelfCache(initialNodes.ViewSlice(), tt.newNodes.ViewSlice())
// Verify the expected number of cache entries were cleared
finalCacheSize := len(pm.filterRulesMap)
finalCacheSize := pm.filterRulesMap.Size()
clearedEntries := initialCacheSize - finalCacheSize
require.Equal(t, tt.expectedCleared, clearedEntries, tt.description)
})
@ -498,15 +500,19 @@ func TestInvalidateGlobalPolicyCache(t *testing.T) {
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
pm := &PolicyManager{
nodes: tt.oldNodes.ViewSlice(),
filterRulesMap: tt.initialCache,
nodes: tt.oldNodes.ViewSlice(),
filterRulesMap: xsync.NewMap[types.NodeID, []tailcfg.FilterRule](),
matchersForNodeMap: xsync.NewMap[types.NodeID, []matcher.Match](),
}
for id, rules := range tt.initialCache {
pm.filterRulesMap.Store(id, rules)
}
pm.invalidateGlobalPolicyCache(tt.newNodes.ViewSlice())
// Verify cache state
for nodeID, shouldExist := range tt.expectedCacheAfter {
_, exists := pm.filterRulesMap[nodeID]
_, exists := pm.filterRulesMap.Load(nodeID)
require.Equal(t, shouldExist, exists, "node %d cache existence mismatch", nodeID)
}
})

4
hscontrol/policy/v2/sshtest.go
View file

@ -128,8 +128,8 @@ func (pm *PolicyManager) RunSSHTests() error {
return nil
}
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
cache := make(map[types.NodeID]*tailcfg.SSHPolicy)
results := runSSHPolicyTests(pm.pol, pm.users, pm.nodes, cache)

4
hscontrol/policy/v2/test.go
View file

@ -204,8 +204,8 @@ func (pm *PolicyManager) RunTests() error {
return nil
}
pm.mu.Lock()
defer pm.mu.Unlock()
pm.mu.RLock()
defer pm.mu.RUnlock()
results := runPolicyTests(pm.pol, pm.filter, pm.users, pm.nodes)
if results.AllPassed {