Merge branch 'main' into embedded-vnc

client/server/mdm.go

@@ -3,7 +3,6 @@ package server
 import (
 	"context"
 	"fmt"
-	"net/url"
 	"time"
 
 	log "github.com/sirupsen/logrus"
@@ -14,28 +13,6 @@ import (
 	"github.com/netbirdio/netbird/client/proto"
 )
 
-// preSharedKeyRedactedSentinel is the value GetConfig returns in place
-// of an actual PSK, so a UI that round-trips the field back to the
-// daemon (via SetConfig / Login) can be distinguished from a deliberate
-// override. Any incoming PSK that equals this sentinel is treated as
-// a no-op echo, never as a conflict with the policy.
-const preSharedKeyRedactedSentinel = "**********"
-
-// loadMDMPolicy is the indirection used by server handlers to read the
-// active MDM policy. Tests override this to inject a fake policy.
-var loadMDMPolicy = mdm.LoadPolicy
-
-// conflictCheck is a value-aware comparison between a single field in
-// the incoming request and the corresponding MDM-enforced value. It
-// runs only when the field was actually set in the request (presence
-// already filtered upstream); ok=true reports the policy value, ok=false
-// means the policy is silent on the key — both are treated as conflicts
-// to be safe (an MDM key declared as managed must hold a value).
-type conflictCheck struct {
-	key   string
-	check func(*mdm.Policy) (match bool)
-}
-
 // onMDMPolicyChange is invoked by the MDM reload ticker every time the
 // OS-native managed-config store reports a diff vs the last observation.
 //
@@ -168,126 +145,6 @@ func (s *Server) restartEngineForMDMLocked() error {
 	return nil
 }
 
-// conflictBool builds a conflictCheck for a boolean MDM key. If p is nil
-// the field is treated as matching (no override requested); otherwise the
-// check returns true only when the policy contains the key and its
-// boolean value equals *p.
-func conflictBool(key string, p *bool) conflictCheck {
-	return conflictCheck{
-		key: key,
-		check: func(pol *mdm.Policy) bool {
-			if p == nil {
-				return true // absent → match by definition
-			}
-			want, ok := pol.GetBool(key)
-			return ok && want == *p
-		},
-	}
-}
-
-func canonicalURL(s string) string {
-	u, err := url.ParseRequestURI(s)
-	if err != nil {
-		return s
-	}
-	if u.Port() == "" {
-		switch u.Scheme {
-		case "https":
-			u.Host += ":443"
-		case "http":
-			u.Host += ":80"
-		}
-	}
-	return u.String()
-}
-
-// conflictURL is conflictString for URL-typed keys: both sides are
-// normalized via canonicalURL before comparison.
-func conflictURL(key, got string) conflictCheck {
-	return conflictCheck{
-		key: key,
-		check: func(pol *mdm.Policy) bool {
-			if got == "" {
-				return true
-			}
-			want, ok := pol.GetString(key)
-			return ok && canonicalURL(want) == canonicalURL(got)
-		},
-	}
-}
-
-// conflictString builds a conflictCheck for a string MDM key. An empty
-// `got` is treated as "field not set" (no override requested); otherwise
-// the check returns true only when the policy contains the key and its
-// value equals got.
-func conflictString(key, got string) conflictCheck {
-	return conflictCheck{
-		key: key,
-		check: func(pol *mdm.Policy) bool {
-			if got == "" {
-				return true
-			}
-			want, ok := pol.GetString(key)
-			return ok && want == got
-		},
-	}
-}
-
-// conflictStringPtr is conflictString for optional proto fields, where an
-// explicit empty value is still a request to change the setting. If p is
-// nil the field is treated as matching (no override requested); otherwise
-// the check returns true only when the policy contains the key and its
-// value equals *p.
-func conflictStringPtr(key string, p *string) conflictCheck {
-	return conflictCheck{
-		key: key,
-		check: func(pol *mdm.Policy) bool {
-			if p == nil {
-				return true
-			}
-			want, ok := pol.GetString(key)
-			return ok && want == *p
-		},
-	}
-}
-
-// conflictInt64 builds a conflictCheck for an integer MDM key. If p is
-// nil the field is treated as matching; otherwise the check returns
-// true only when the policy contains the key and its int value equals *p.
-func conflictInt64(key string, p *int64) conflictCheck {
-	return conflictCheck{
-		key: key,
-		check: func(pol *mdm.Policy) bool {
-			if p == nil {
-				return true
-			}
-			want, ok := pol.GetInt(key)
-			return ok && want == *p
-		},
-	}
-}
-
-// resolveConflicts walks the per-field checks against the active MDM
-// policy and returns the names of keys whose requested value diverges
-// from the policy-enforced value. Keys not present in the policy are
-// skipped silently (the gate fires only for keys the admin has
-// actually pushed). Returns nil for an empty policy.
-func resolveConflicts(policy *mdm.Policy, checks []conflictCheck) []string {
-	if policy.IsEmpty() {
-		return nil
-	}
-	var conflicts []string
-	for _, c := range checks {
-		if !policy.HasKey(c.key) {
-			continue
-		}
-		if !c.check(policy) {
-			conflicts = append(conflicts, c.key)
-		}
-	}
-	return conflicts
-}
-
 // mdmManagedFieldConflicts returns the names of MDM-managed keys whose
 // requested value in the SetConfigRequest differs from the MDM-enforced
 // value. A field set to the same value the policy already enforces is
@@ -301,29 +158,27 @@ func mdmManagedFieldConflicts(msg *proto.SetConfigRequest, policy *mdm.Policy) [
 		return nil
 	}
 
-	// PSK round-trip echo: collapse the sentinel to empty so the
-	// shared check treats it as "field not set".
-	pskGot := ""
-	if msg.OptionalPreSharedKey != nil && *msg.OptionalPreSharedKey != preSharedKeyRedactedSentinel {
-		pskGot = *msg.OptionalPreSharedKey
+	pskGot := msg.OptionalPreSharedKey
+	if pskGot != nil && *pskGot == mdm.PreSharedKeyRedactedSentinel {
+		pskGot = nil
 	}
 
-	return resolveConflicts(policy, []conflictCheck{
-		conflictURL(mdm.KeyManagementURL, msg.ManagementUrl),
-		conflictString(mdm.KeyPreSharedKey, pskGot),
-		conflictBool(mdm.KeyRosenpassEnabled, msg.RosenpassEnabled),
-		conflictBool(mdm.KeyRosenpassPermissive, msg.RosenpassPermissive),
-		conflictBool(mdm.KeyDisableAutoConnect, msg.DisableAutoConnect),
-		conflictBool(mdm.KeyAllowServerSSH, msg.ServerSSHAllowed),
-		conflictBool(mdm.KeyRemoteJobsAllowed, msg.RemoteJobsAllowed),
-		conflictBool(mdm.KeyAllowServerVNC, msg.ServerVNCAllowed),
-		conflictBool(mdm.KeyDisableVNCApproval, msg.DisableVNCApproval),
-		conflictBool(mdm.KeyDisableClientRoutes, msg.DisableClientRoutes),
-		conflictBool(mdm.KeyDisableServerRoutes, msg.DisableServerRoutes),
-		conflictBool(mdm.KeyBlockInbound, msg.BlockInbound),
-		conflictInt64(mdm.KeyWireguardPort, msg.WireguardPort),
-		conflictBool(mdm.KeyEnableLocalMetrics, msg.EnableLocalMetrics),
-		conflictStringPtr(mdm.KeyLocalMetricsAddress, msg.LocalMetricsAddress),
+	return mdm.ResolveConflicts(policy, []mdm.ConflictCheck{
+		mdm.ConflictURL(mdm.KeyManagementURL, msg.ManagementUrl),
+		mdm.ConflictStringPtr(mdm.KeyPreSharedKey, pskGot),
+		mdm.ConflictBool(mdm.KeyRosenpassEnabled, msg.RosenpassEnabled),
+		mdm.ConflictBool(mdm.KeyRosenpassPermissive, msg.RosenpassPermissive),
+		mdm.ConflictBool(mdm.KeyDisableAutoConnect, msg.DisableAutoConnect),
+		mdm.ConflictBool(mdm.KeyAllowServerSSH, msg.ServerSSHAllowed),
+		mdm.ConflictBool(mdm.KeyRemoteJobsAllowed, msg.RemoteJobsAllowed),
+		mdm.ConflictBool(mdm.KeyAllowServerVNC, msg.ServerVNCAllowed),
+		mdm.ConflictBool(mdm.KeyDisableVNCApproval, msg.DisableVNCApproval),
+		mdm.ConflictBool(mdm.KeyDisableClientRoutes, msg.DisableClientRoutes),
+		mdm.ConflictBool(mdm.KeyDisableServerRoutes, msg.DisableServerRoutes),
+		mdm.ConflictBool(mdm.KeyBlockInbound, msg.BlockInbound),
+		mdm.ConflictInt64(mdm.KeyWireguardPort, msg.WireguardPort),
+		mdm.ConflictBool(mdm.KeyEnableLocalMetrics, msg.EnableLocalMetrics),
+		mdm.ConflictStringPtr(mdm.KeyLocalMetricsAddress, msg.LocalMetricsAddress),
 	})
 }
 
@@ -430,36 +285,30 @@ func loginRequestMDMConflicts(msg *proto.LoginRequest, policy *mdm.Policy) []str
 		return nil
 	}
 
-	// Collapse the two PSK fields + the redaction sentinel down to a
-	// single "got" string the shared check can compare against the
-	// policy: OptionalPreSharedKey wins if set; PreSharedKey (deprecated)
-	// is the fallback; sentinel echo is treated as "field not set".
-	pskGot := ""
-	if msg.OptionalPreSharedKey != nil {
-		pskGot = *msg.OptionalPreSharedKey
-	} else if msg.PreSharedKey != "" { //nolint:staticcheck // SA1019: legacy proto field still accepted by Login
-		pskGot = msg.PreSharedKey //nolint:staticcheck // SA1019
+	pskGot := msg.OptionalPreSharedKey
+	if pskGot == nil && msg.PreSharedKey != "" { //nolint:staticcheck // SA1019: legacy proto field still accepted by Login
+		pskGot = &msg.PreSharedKey //nolint:staticcheck // SA1019
 	}
-	if pskGot == preSharedKeyRedactedSentinel {
-		pskGot = ""
+	if pskGot != nil && *pskGot == mdm.PreSharedKeyRedactedSentinel {
+		pskGot = nil
 	}
 
-	return resolveConflicts(policy, []conflictCheck{
-		conflictURL(mdm.KeyManagementURL, msg.ManagementUrl),
-		conflictString(mdm.KeyPreSharedKey, pskGot),
-		conflictBool(mdm.KeyRosenpassEnabled, msg.RosenpassEnabled),
-		conflictBool(mdm.KeyRosenpassPermissive, msg.RosenpassPermissive),
-		conflictBool(mdm.KeyDisableAutoConnect, msg.DisableAutoConnect),
-		conflictBool(mdm.KeyAllowServerSSH, msg.ServerSSHAllowed),
-		conflictBool(mdm.KeyRemoteJobsAllowed, msg.RemoteJobsAllowed),
-		conflictBool(mdm.KeyAllowServerVNC, msg.ServerVNCAllowed),
-		conflictBool(mdm.KeyDisableVNCApproval, msg.DisableVNCApproval),
-		conflictBool(mdm.KeyDisableClientRoutes, msg.DisableClientRoutes),
-		conflictBool(mdm.KeyDisableServerRoutes, msg.DisableServerRoutes),
-		conflictBool(mdm.KeyBlockInbound, msg.BlockInbound),
-		conflictInt64(mdm.KeyWireguardPort, msg.WireguardPort),
-		conflictBool(mdm.KeyEnableLocalMetrics, msg.EnableLocalMetrics),
-		conflictStringPtr(mdm.KeyLocalMetricsAddress, msg.LocalMetricsAddress),
+	return mdm.ResolveConflicts(policy, []mdm.ConflictCheck{
+		mdm.ConflictURL(mdm.KeyManagementURL, msg.ManagementUrl),
+		mdm.ConflictStringPtr(mdm.KeyPreSharedKey, pskGot),
+		mdm.ConflictBool(mdm.KeyRosenpassEnabled, msg.RosenpassEnabled),
+		mdm.ConflictBool(mdm.KeyRosenpassPermissive, msg.RosenpassPermissive),
+		mdm.ConflictBool(mdm.KeyDisableAutoConnect, msg.DisableAutoConnect),
+		mdm.ConflictBool(mdm.KeyAllowServerSSH, msg.ServerSSHAllowed),
+		mdm.ConflictBool(mdm.KeyRemoteJobsAllowed, msg.RemoteJobsAllowed),
+		mdm.ConflictBool(mdm.KeyAllowServerVNC, msg.ServerVNCAllowed),
+		mdm.ConflictBool(mdm.KeyDisableVNCApproval, msg.DisableVNCApproval),
+		mdm.ConflictBool(mdm.KeyDisableClientRoutes, msg.DisableClientRoutes),
+		mdm.ConflictBool(mdm.KeyDisableServerRoutes, msg.DisableServerRoutes),
+		mdm.ConflictBool(mdm.KeyBlockInbound, msg.BlockInbound),
+		mdm.ConflictInt64(mdm.KeyWireguardPort, msg.WireguardPort),
+		mdm.ConflictBool(mdm.KeyEnableLocalMetrics, msg.EnableLocalMetrics),
+		mdm.ConflictStringPtr(mdm.KeyLocalMetricsAddress, msg.LocalMetricsAddress),
 	})
 }
 

client/server/server.go

@@ -142,6 +142,15 @@ type Server struct {
 	// stopped by the rootCtx cancellation.
 	mdmTicker *mdm.Ticker
 
+	// mdmLoader is the daemon-owned source of the active MDM policy.
+	// Constructed once during Server.Start (with a nil PolicyFetcher on
+	// desktop — the build-tagged Loader.loadPlatform reads the OS
+	// registry / plist directly) and injected into every consumer:
+	// mdmTicker for its periodic reload, the SetConfig / Login MDM
+	// gates for conflict detection, and every Config produced via
+	// getConfig() so its apply() picks up the same overlay.
+	mdmLoader *mdm.Loader
+
 	updateManager *updater.Manager
 
 	jwtCache *jwtCache
@@ -250,8 +259,14 @@ func (s *Server) Start() error {
 	// Runs re-resolves Config (re-running profilemanager.Config.apply which
 	// applies the freshly-read MDM policy as the last layer) and brings
 	// the engine back with the new values.
+	if s.mdmLoader == nil {
+		// Desktop builds pass a nil PolicyFetcher: the Loader's
+		// build-tagged loadPlatform reads the OS source directly
+		// (registry on Windows, plist on macOS, no-op elsewhere).
+		s.mdmLoader = mdm.NewLoader(nil)
+	}
 	if s.mdmTicker == nil {
-		s.mdmTicker = mdm.NewTicker(mdm.DefaultReloadInterval)
+		s.mdmTicker = mdm.NewTicker(mdm.DefaultReloadInterval, s.mdmLoader)
 		go s.mdmTicker.Run(s.rootCtx, s.onMDMPolicyChange)
 	}
 
@@ -497,7 +512,7 @@ func (s *Server) SetConfig(callerCtx context.Context, msg *proto.SetConfigReques
 	// by the active MDM policy. The error carries an MDMManagedFields-
 	// Violation detail listing the offending key names. Non-conflicting
 	// fields in the same request are not applied either.
-	policy := loadMDMPolicy()
+	policy := s.mdmLoader.Load()
 	if err := rejectMDMManagedFieldConflicts(mdmManagedFieldConflicts(msg, policy)); err != nil {
 		return nil, err
 	}
@@ -642,7 +657,7 @@ func (s *Server) Login(callerCtx context.Context, msg *proto.LoginRequest) (*pro
 		if s.checkUpdateSettingsDisabled() {
 			return nil, gstatus.Errorf(codes.Unavailable, errUpdateSettingsDisabled)
 		}
-		policy := loadMDMPolicy()
+		policy := s.mdmLoader.Load()
 		if err := rejectMDMManagedFieldConflicts(loginRequestMDMConflicts(msg, policy)); err != nil {
 			return nil, err
 		}
@@ -1493,6 +1508,12 @@ func (s *Server) getConfig(activeProf *profilemanager.ActiveProfileState) (*prof
 		return nil, false, fmt.Errorf("failed to get config: %w", err)
 	}
 
+	// Apply the daemon-owned MDM policy on top of the just-resolved
+	// Config. profilemanager's apply() initialises the policy to
+	// empty — the Loader lives outside Config, so this overlay step
+	// is driven externally here.
+	config.ApplyMDMPolicy(s.mdmLoader.Load())
+
 	return config, configExisted, nil
 }
 
@@ -1549,6 +1570,9 @@ func (s *Server) logoutFromProfile(ctx context.Context, profile *profilemanager.
 	if err != nil {
 		return fmt.Errorf("profile '%s' not found", profile.ID)
 	}
+	// Honour any MDM-enforced ManagementURL when issuing the logout
+	// RPC: the user-stored value may have been overridden by policy.
+	config.ApplyMDMPolicy(s.mdmLoader.Load())
 
 	return s.sendLogoutRequestWithConfig(ctx, config)
 }
@@ -2257,6 +2281,11 @@ func (s *Server) GetConfig(ctx context.Context, req *proto.GetConfigRequest) (*p
 		log.Errorf("failed to get active profile config: %v", err)
 		return nil, fmt.Errorf("failed to get active profile config: %w", err)
 	}
+	// Overlay the active MDM policy so the response's MDMManagedFields
+	// list reflects what the GUI / CLI must render as read-only.
+	// profilemanager.GetConfig itself returns a Config without the
+	// overlay (Loader lives outside profilemanager).
+	cfg.ApplyMDMPolicy(s.mdmLoader.Load())
 	managementURL := cfg.ManagementURL
 	adminURL := cfg.AdminURL
 

client/server/setconfig_mdm_test.go

@@ -16,14 +16,40 @@ import (
 	"github.com/netbirdio/netbird/client/proto"
 )
 
-// withMDMPolicy temporarily overrides the server-package loadMDMPolicy hook
-// so SetConfig observes the supplied Policy. Restores the original loader
-// at test cleanup.
-func withMDMPolicy(t *testing.T, policy *mdm.Policy) {
+// fakeMDMFetcher implements mdm.PolicyFetcher returning a pre-set
+// policy map. Tests build one per Server instance to inject a
+// scripted MDM overlay via a Loader rather than via package-level state.
+type fakeMDMFetcher struct{ values map[string]any }
+
+func (f *fakeMDMFetcher) Fetch() map[string]any { return f.values }
+
+// withMDMPolicy installs an mdm.Loader on the given Server whose
+// loadPlatform returns the supplied Policy's underlying values. Use
+// after setupServerWithProfile to inject the scripted policy the
+// SetConfig / Login MDM gates will observe.
+func withMDMPolicy(t *testing.T, s *Server, policy *mdm.Policy) {
 	t.Helper()
-	prev := loadMDMPolicy
-	loadMDMPolicy = func() *mdm.Policy { return policy }
-	t.Cleanup(func() { loadMDMPolicy = prev })
+	values := map[string]any{}
+	if policy != nil {
+		for _, k := range policy.ManagedKeys() {
+			if v, ok := policy.GetString(k); ok {
+				values[k] = v
+				continue
+			}
+			if v, ok := policy.GetInt(k); ok {
+				values[k] = v
+				continue
+			}
+			if v, ok := policy.GetBool(k); ok {
+				values[k] = v
+				continue
+			}
+			if v, ok := policy.GetStringSlice(k); ok {
+				values[k] = v
+			}
+		}
+	}
+	s.mdmLoader = mdm.NewLoader(&fakeMDMFetcher{values: values})
 }
 
 // setupServerWithProfile mirrors the boilerplate of TestSetConfig_AllFieldsSaved:
@@ -93,12 +119,11 @@ func extractViolation(t *testing.T, err error) *proto.MDMManagedFieldsViolation
 }
 
 func TestSetConfig_MDMReject_SingleField(t *testing.T) {
-	withMDMPolicy(t, mdm.NewPolicy(map[string]any{
+	s, ctx, profName, username, _ := setupServerWithProfile(t)
+	withMDMPolicy(t, s, mdm.NewPolicy(map[string]any{
 		mdm.KeyManagementURL: "https://mdm.example.com:443",
 	}))
 
-	s, ctx, profName, username, _ := setupServerWithProfile(t)
-
 	_, err := s.SetConfig(ctx, &proto.SetConfigRequest{
 		ProfileName:   profName,
 		Username:      username,
@@ -110,13 +135,12 @@ func TestSetConfig_MDMReject_SingleField(t *testing.T) {
 }
 
 func TestSetConfig_MDMReject_VNCFields(t *testing.T) {
-	withMDMPolicy(t, mdm.NewPolicy(map[string]any{
+	s, ctx, profName, username, _ := setupServerWithProfile(t)
+	withMDMPolicy(t, s, mdm.NewPolicy(map[string]any{
 		mdm.KeyAllowServerVNC:     true,
 		mdm.KeyDisableVNCApproval: false,
 	}))
 
-	s, ctx, profName, username, _ := setupServerWithProfile(t)
-
 	vncAllowed := false
 	disableApproval := true
 	_, err := s.SetConfig(ctx, &proto.SetConfigRequest{
@@ -134,14 +158,13 @@ func TestSetConfig_MDMReject_VNCFields(t *testing.T) {
 }
 
 func TestSetConfig_MDMReject_MultipleFields(t *testing.T) {
-	withMDMPolicy(t, mdm.NewPolicy(map[string]any{
+	s, ctx, profName, username, _ := setupServerWithProfile(t)
+	withMDMPolicy(t, s, mdm.NewPolicy(map[string]any{
 		mdm.KeyManagementURL:    "https://mdm.example.com:443",
 		mdm.KeyBlockInbound:     true,
 		mdm.KeyRosenpassEnabled: true,
 	}))
 
-	s, ctx, profName, username, _ := setupServerWithProfile(t)
-
 	blockInbound := false
 	rosenpassEnabled := false
 	_, err := s.SetConfig(ctx, &proto.SetConfigRequest{
@@ -161,13 +184,12 @@ func TestSetConfig_MDMReject_MultipleFields(t *testing.T) {
 }
 
 func TestSetConfig_MDMReject_LocalMetrics(t *testing.T) {
-	withMDMPolicy(t, mdm.NewPolicy(map[string]any{
+	s, ctx, profName, username, _ := setupServerWithProfile(t)
+	withMDMPolicy(t, s, mdm.NewPolicy(map[string]any{
 		mdm.KeyEnableLocalMetrics:  true,
 		mdm.KeyLocalMetricsAddress: "127.0.0.1:9191",
 	}))
 
-	s, ctx, profName, username, _ := setupServerWithProfile(t)
-
 	enabled := false
 	addr := "0.0.0.0:9999"
 	_, err := s.SetConfig(ctx, &proto.SetConfigRequest{
@@ -188,12 +210,11 @@ func TestSetConfig_MDMReject_LocalMetrics(t *testing.T) {
 // (the manager falls back to the default), so presence must be honored
 // rather than collapsed to "field not set".
 func TestSetConfig_MDMReject_LocalMetricsEmptyAddress(t *testing.T) {
-	withMDMPolicy(t, mdm.NewPolicy(map[string]any{
+	s, ctx, profName, username, _ := setupServerWithProfile(t)
+	withMDMPolicy(t, s, mdm.NewPolicy(map[string]any{
 		mdm.KeyLocalMetricsAddress: "127.0.0.1:9999",
 	}))
 
-	s, ctx, profName, username, _ := setupServerWithProfile(t)
-
 	addr := ""
 	_, err := s.SetConfig(ctx, &proto.SetConfigRequest{
 		ProfileName:         profName,
@@ -205,17 +226,80 @@ func TestSetConfig_MDMReject_LocalMetricsEmptyAddress(t *testing.T) {
 	assert.ElementsMatch(t, []string{mdm.KeyLocalMetricsAddress}, v.GetFields())
 }
 
+func TestSetConfig_MDMReject_EmptyPreSharedKey(t *testing.T) {
+	s, ctx, profName, username, _ := setupServerWithProfile(t)
+	withMDMPolicy(t, s, mdm.NewPolicy(map[string]any{
+		mdm.KeyPreSharedKey: "mdm-enforced-psk",
+	}))
+
+	psk := ""
+	_, err := s.SetConfig(ctx, &proto.SetConfigRequest{
+		ProfileName:          profName,
+		Username:             username,
+		OptionalPreSharedKey: &psk,
+	})
+
+	v := extractViolation(t, err)
+	assert.ElementsMatch(t, []string{mdm.KeyPreSharedKey}, v.GetFields())
+}
+
+func TestSetConfig_MDMAllow_PreSharedKeySentinelEcho(t *testing.T) {
+	s, ctx, profName, username, _ := setupServerWithProfile(t)
+	withMDMPolicy(t, s, mdm.NewPolicy(map[string]any{
+		mdm.KeyPreSharedKey: "mdm-enforced-psk",
+	}))
+
+	psk := mdm.PreSharedKeyRedactedSentinel
+	resp, err := s.SetConfig(ctx, &proto.SetConfigRequest{
+		ProfileName:          profName,
+		Username:             username,
+		OptionalPreSharedKey: &psk,
+	})
+
+	require.NoError(t, err)
+	require.NotNil(t, resp)
+}
+
+func TestLoginRequestMDMConflicts_PreSharedKey(t *testing.T) {
+	policy := mdm.NewPolicy(map[string]any{
+		mdm.KeyPreSharedKey: "mdm-enforced-psk",
+	})
+	empty := ""
+	sentinel := mdm.PreSharedKeyRedactedSentinel
+	same := "mdm-enforced-psk"
+	other := "user-psk"
+
+	tests := []struct {
+		name string
+		msg  *proto.LoginRequest
+		want []string
+	}{
+		{name: "unset", msg: &proto.LoginRequest{}, want: nil},
+		{name: "optional empty", msg: &proto.LoginRequest{OptionalPreSharedKey: &empty}, want: []string{mdm.KeyPreSharedKey}},
+		{name: "optional sentinel echo", msg: &proto.LoginRequest{OptionalPreSharedKey: &sentinel}, want: nil},
+		{name: "optional same value", msg: &proto.LoginRequest{OptionalPreSharedKey: &same}, want: nil},
+		{name: "optional divergent", msg: &proto.LoginRequest{OptionalPreSharedKey: &other}, want: []string{mdm.KeyPreSharedKey}},
+		{name: "legacy empty is unset", msg: &proto.LoginRequest{PreSharedKey: ""}, want: nil},                         //nolint:staticcheck // SA1019: legacy proto field still accepted by Login
+		{name: "legacy sentinel echo", msg: &proto.LoginRequest{PreSharedKey: sentinel}, want: nil},                    //nolint:staticcheck // SA1019: legacy proto field still accepted by Login
+		{name: "legacy divergent", msg: &proto.LoginRequest{PreSharedKey: other}, want: []string{mdm.KeyPreSharedKey}}, //nolint:staticcheck // SA1019: legacy proto field still accepted by Login
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			assert.Equal(t, tc.want, loginRequestMDMConflicts(tc.msg, policy))
+		})
+	}
+}
+
 func TestSetConfig_MDMReject_AllOrNothing(t *testing.T) {
 	// MDM enforces ManagementURL only; user request touches both the
 	// enforced field AND a non-enforced field (RosenpassEnabled).
 	// The whole request must be rejected — non-conflicting fields are not
 	// applied either.
-	withMDMPolicy(t, mdm.NewPolicy(map[string]any{
+	s, ctx, profName, username, cfgPath := setupServerWithProfile(t)
+	withMDMPolicy(t, s, mdm.NewPolicy(map[string]any{
 		mdm.KeyManagementURL: "https://mdm.example.com:443",
 	}))
 
-	s, ctx, profName, username, cfgPath := setupServerWithProfile(t)
-
 	rosenpassEnabled := true
 	_, err := s.SetConfig(ctx, &proto.SetConfigRequest{
 		ProfileName:      profName,
@@ -237,12 +321,11 @@ func TestSetConfig_MDMReject_AllOrNothing(t *testing.T) {
 func TestSetConfig_MDMAllow_NonManagedFields(t *testing.T) {
 	// MDM enforces ManagementURL but the user only writes RosenpassEnabled.
 	// Request must succeed.
-	withMDMPolicy(t, mdm.NewPolicy(map[string]any{
+	s, ctx, profName, username, _ := setupServerWithProfile(t)
+	withMDMPolicy(t, s, mdm.NewPolicy(map[string]any{
 		mdm.KeyManagementURL: "https://mdm.example.com:443",
 	}))
 
-	s, ctx, profName, username, _ := setupServerWithProfile(t)
-
 	rosenpassEnabled := true
 	resp, err := s.SetConfig(ctx, &proto.SetConfigRequest{
 		ProfileName:      profName,
@@ -271,12 +354,11 @@ func TestSetConfig_MDMAllow_ManagementURLPortNormalized(t *testing.T) {
 
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
-			withMDMPolicy(t, mdm.NewPolicy(map[string]any{
+			s, ctx, profName, username, _ := setupServerWithProfile(t)
+			withMDMPolicy(t, s, mdm.NewPolicy(map[string]any{
 				mdm.KeyManagementURL: tc.mdmURL,
 			}))
 
-			s, ctx, profName, username, _ := setupServerWithProfile(t)
-
 			rosenpassEnabled := true
 			resp, err := s.SetConfig(ctx, &proto.SetConfigRequest{
 				ProfileName:      profName,
@@ -293,9 +375,8 @@ func TestSetConfig_MDMAllow_ManagementURLPortNormalized(t *testing.T) {
 
 func TestSetConfig_MDMEmpty_NoEnforcement(t *testing.T) {
 	// No MDM policy active: any field can be written.
-	withMDMPolicy(t, mdm.NewPolicy(nil))
-
 	s, ctx, profName, username, _ := setupServerWithProfile(t)
+	withMDMPolicy(t, s, mdm.NewPolicy(nil))
 
 	resp, err := s.SetConfig(ctx, &proto.SetConfigRequest{
 		ProfileName:   profName,