ipn/ipnlocal: add additional syspolicy enforcement

This adds support for enforcing exit node LAN access, DNS and subnet
routes.

Adding new preference policies was getting repetitive, so this turns
some of the boilerplate into a table.

Updates tailscale/corp#15585
Updates ENG-2240

Change-Id: Iabd3c42b0ae120b3145fac066c5caa7fc4d67824
Signed-off-by: Adrian Dewhurst <adrian@tailscale.com>
pull/10462/head
Adrian Dewhurst 6 months ago committed by Adrian Dewhurst
parent 2731a9da36
commit 1a4d423328

@ -1230,6 +1230,42 @@ func (b *LocalBackend) SetControlClientStatus(c controlclient.Client, st control
b.authReconfig()
}
type preferencePolicyInfo struct {
key syspolicy.Key
get func(ipn.PrefsView) bool
set func(*ipn.Prefs, bool)
}
var preferencePolicies = []preferencePolicyInfo{
{
key: syspolicy.EnableIncomingConnections,
// Allow Incoming (used by the UI) is the negation of ShieldsUp (used by the
// backend), so this has to convert between the two conventions.
get: func(p ipn.PrefsView) bool { return !p.ShieldsUp() },
set: func(p *ipn.Prefs, v bool) { p.ShieldsUp = !v },
},
{
key: syspolicy.EnableServerMode,
get: func(p ipn.PrefsView) bool { return p.ForceDaemon() },
set: func(p *ipn.Prefs, v bool) { p.ForceDaemon = v },
},
{
key: syspolicy.ExitNodeAllowLANAccess,
get: func(p ipn.PrefsView) bool { return p.ExitNodeAllowLANAccess() },
set: func(p *ipn.Prefs, v bool) { p.ExitNodeAllowLANAccess = v },
},
{
key: syspolicy.EnableTailscaleDNS,
get: func(p ipn.PrefsView) bool { return p.CorpDNS() },
set: func(p *ipn.Prefs, v bool) { p.CorpDNS = v },
},
{
key: syspolicy.EnableTailscaleSubnets,
get: func(p ipn.PrefsView) bool { return p.RouteAll() },
set: func(p *ipn.Prefs, v bool) { p.RouteAll = v },
},
}
// applySysPolicy overwrites configured preferences with policies that may be
// configured by the system administrator in an OS-specific way.
func applySysPolicy(prefs *ipn.Prefs) (anyChange bool) {
@ -1238,21 +1274,14 @@ func applySysPolicy(prefs *ipn.Prefs) (anyChange bool) {
anyChange = true
}
// Allow Incoming (used by the UI) is the negation of ShieldsUp (used by the
// backend), so this has to convert between the two conventions.
if shieldsUp, err := syspolicy.GetPreferenceOption(syspolicy.EnableIncomingConnections); err == nil {
newVal := !shieldsUp.ShouldEnable(!prefs.ShieldsUp)
if prefs.ShieldsUp != newVal {
prefs.ShieldsUp = newVal
anyChange = true
}
}
if forceDaemon, err := syspolicy.GetPreferenceOption(syspolicy.EnableServerMode); err == nil {
newVal := forceDaemon.ShouldEnable(prefs.ForceDaemon)
if prefs.ForceDaemon != newVal {
prefs.ForceDaemon = newVal
anyChange = true
for _, opt := range preferencePolicies {
if po, err := syspolicy.GetPreferenceOption(opt.key); err == nil {
curVal := opt.get(prefs.View())
newVal := po.ShouldEnable(curVal)
if curVal != newVal {
opt.set(prefs, newVal)
anyChange = true
}
}
}

@ -5,6 +5,7 @@ package ipnlocal
import (
"context"
"errors"
"fmt"
"net"
"net/http"
@ -1332,6 +1333,34 @@ func (rc *routeCollector) AdvertiseRoute(pfx netip.Prefix) error {
return nil
}
type errorSyspolicyHandler struct {
t *testing.T
err error
key syspolicy.Key
allowKeys map[syspolicy.Key]*string
}
func (h *errorSyspolicyHandler) ReadString(key string) (string, error) {
sk := syspolicy.Key(key)
if _, ok := h.allowKeys[sk]; !ok {
h.t.Errorf("ReadString: %q is not in list of permitted keys", h.key)
}
if sk == h.key {
return "", h.err
}
return "", syspolicy.ErrNoSuchKey
}
func (h *errorSyspolicyHandler) ReadUInt64(key string) (uint64, error) {
h.t.Errorf("ReadUInt64(%q) unexpectedly called", key)
return 0, syspolicy.ErrNoSuchKey
}
func (h *errorSyspolicyHandler) ReadBoolean(key string) (bool, error) {
h.t.Errorf("ReadBoolean(%q) unexpectedly called", key)
return false, syspolicy.ErrNoSuchKey
}
type mockSyspolicyHandler struct {
t *testing.T
// stringPolicies is the collection of policies that we expect to see
@ -1625,28 +1654,40 @@ func TestApplySysPolicy(t *testing.T) {
{
name: "prefs set without policies",
prefs: ipn.Prefs{
ControlURL: "1",
ShieldsUp: true,
ForceDaemon: true,
ControlURL: "1",
ShieldsUp: true,
ForceDaemon: true,
ExitNodeAllowLANAccess: true,
CorpDNS: true,
RouteAll: true,
},
wantPrefs: ipn.Prefs{
ControlURL: "1",
ShieldsUp: true,
ForceDaemon: true,
ControlURL: "1",
ShieldsUp: true,
ForceDaemon: true,
ExitNodeAllowLANAccess: true,
CorpDNS: true,
RouteAll: true,
},
},
{
name: "empty prefs with policies",
wantPrefs: ipn.Prefs{
ControlURL: "1",
ShieldsUp: true,
ForceDaemon: true,
ControlURL: "1",
ShieldsUp: true,
ForceDaemon: true,
ExitNodeAllowLANAccess: true,
CorpDNS: true,
RouteAll: true,
},
wantAnyChange: true,
stringPolicies: map[syspolicy.Key]string{
syspolicy.ControlURL: "1",
syspolicy.EnableIncomingConnections: "never",
syspolicy.EnableServerMode: "always",
syspolicy.ExitNodeAllowLANAccess: "always",
syspolicy.EnableTailscaleDNS: "always",
syspolicy.EnableTailscaleSubnets: "always",
},
},
{
@ -1665,42 +1706,63 @@ func TestApplySysPolicy(t *testing.T) {
syspolicy.ControlURL: "1",
syspolicy.EnableIncomingConnections: "never",
syspolicy.EnableServerMode: "always",
syspolicy.ExitNodeAllowLANAccess: "never",
syspolicy.EnableTailscaleDNS: "never",
syspolicy.EnableTailscaleSubnets: "never",
},
},
{
name: "prefs set with conflicting policies",
prefs: ipn.Prefs{
ControlURL: "1",
ShieldsUp: true,
ForceDaemon: true,
ControlURL: "1",
ShieldsUp: true,
ForceDaemon: true,
ExitNodeAllowLANAccess: false,
CorpDNS: true,
RouteAll: false,
},
wantPrefs: ipn.Prefs{
ControlURL: "2",
ShieldsUp: false,
ForceDaemon: false,
ControlURL: "2",
ShieldsUp: false,
ForceDaemon: false,
ExitNodeAllowLANAccess: true,
CorpDNS: false,
RouteAll: true,
},
wantAnyChange: true,
stringPolicies: map[syspolicy.Key]string{
syspolicy.ControlURL: "2",
syspolicy.EnableIncomingConnections: "always",
syspolicy.EnableServerMode: "never",
syspolicy.ExitNodeAllowLANAccess: "always",
syspolicy.EnableTailscaleDNS: "never",
syspolicy.EnableTailscaleSubnets: "always",
},
},
{
name: "prefs set with neutral policies",
prefs: ipn.Prefs{
ControlURL: "1",
ShieldsUp: true,
ForceDaemon: true,
ControlURL: "1",
ShieldsUp: true,
ForceDaemon: true,
ExitNodeAllowLANAccess: false,
CorpDNS: true,
RouteAll: true,
},
wantPrefs: ipn.Prefs{
ControlURL: "1",
ShieldsUp: true,
ForceDaemon: true,
ControlURL: "1",
ShieldsUp: true,
ForceDaemon: true,
ExitNodeAllowLANAccess: false,
CorpDNS: true,
RouteAll: true,
},
stringPolicies: map[syspolicy.Key]string{
syspolicy.EnableIncomingConnections: "user-decides",
syspolicy.EnableServerMode: "user-decides",
syspolicy.ExitNodeAllowLANAccess: "user-decides",
syspolicy.EnableTailscaleDNS: "user-decides",
syspolicy.EnableTailscaleSubnets: "user-decides",
},
},
{
@ -1713,78 +1775,21 @@ func TestApplySysPolicy(t *testing.T) {
syspolicy.ControlURL: "set",
},
},
{
name: "always incoming connections",
prefs: ipn.Prefs{
ShieldsUp: true,
},
wantPrefs: ipn.Prefs{
ShieldsUp: false,
},
wantAnyChange: true,
stringPolicies: map[syspolicy.Key]string{
syspolicy.EnableIncomingConnections: "always",
},
},
{
name: "never incoming connections",
prefs: ipn.Prefs{
ShieldsUp: false,
},
wantPrefs: ipn.Prefs{
ShieldsUp: true,
},
wantAnyChange: true,
stringPolicies: map[syspolicy.Key]string{
syspolicy.EnableIncomingConnections: "never",
},
},
{
name: "always server mode",
prefs: ipn.Prefs{
ForceDaemon: false,
},
wantPrefs: ipn.Prefs{
ForceDaemon: true,
},
wantAnyChange: true,
stringPolicies: map[syspolicy.Key]string{
syspolicy.EnableServerMode: "always",
},
},
{
name: "never server mode",
prefs: ipn.Prefs{
ForceDaemon: true,
},
wantPrefs: ipn.Prefs{
ForceDaemon: false,
},
wantAnyChange: true,
stringPolicies: map[syspolicy.Key]string{
syspolicy.EnableServerMode: "never",
},
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
t.Run("unit", func(t *testing.T) {
// Be strict when testing the func directly.
msh := &mockSyspolicyHandler{
t: t,
stringPolicies: map[syspolicy.Key]*string{
syspolicy.ControlURL: nil,
syspolicy.EnableIncomingConnections: nil,
syspolicy.EnableServerMode: nil,
},
failUnknownPolicies: true,
}
for p, v := range tt.stringPolicies {
v := v // construct a unique pointer for each policy value
msh.stringPolicies[p] = &v
}
syspolicy.SetHandlerForTest(t, msh)
msh := &mockSyspolicyHandler{
t: t,
stringPolicies: make(map[syspolicy.Key]*string, len(tt.stringPolicies)),
}
for p, v := range tt.stringPolicies {
v := v // construct a unique pointer for each policy value
msh.stringPolicies[p] = &v
}
syspolicy.SetHandlerForTest(t, msh)
t.Run("unit", func(t *testing.T) {
prefs := tt.prefs.Clone()
gotAnyChange := applySysPolicy(prefs)
@ -1802,16 +1807,6 @@ func TestApplySysPolicy(t *testing.T) {
t.Errorf("prefs=%v, want %v", prefs.Pretty(), tt.wantPrefs.Pretty())
}
})
// Create a more relaxed syspolicy for integration tests.
msh := &mockSyspolicyHandler{
t: t,
stringPolicies: make(map[syspolicy.Key]*string, len(tt.stringPolicies)),
}
for p, v := range tt.stringPolicies {
v := v // construct a unique pointer for each policy value
msh.stringPolicies[p] = &v
}
syspolicy.SetHandlerForTest(t, msh)
t.Run("set prefs", func(t *testing.T) {
@ -1851,3 +1846,136 @@ func TestApplySysPolicy(t *testing.T) {
})
}
}
func TestPreferencePolicyInfo(t *testing.T) {
tests := []struct {
name string
initialValue bool
wantValue bool
wantChange bool
policyValue string
policyError error
}{
{
name: "force enable modify",
initialValue: false,
wantValue: true,
wantChange: true,
policyValue: "always",
},
{
name: "force enable unchanged",
initialValue: true,
wantValue: true,
policyValue: "always",
},
{
name: "force disable modify",
initialValue: true,
wantValue: false,
wantChange: true,
policyValue: "never",
},
{
name: "force disable unchanged",
initialValue: false,
wantValue: false,
policyValue: "never",
},
{
name: "unforced enabled",
initialValue: true,
wantValue: true,
policyValue: "user-decides",
},
{
name: "unforced disabled",
initialValue: false,
wantValue: false,
policyValue: "user-decides",
},
{
name: "blank enabled",
initialValue: true,
wantValue: true,
policyValue: "",
},
{
name: "blank disabled",
initialValue: false,
wantValue: false,
policyValue: "",
},
{
name: "unset enabled",
initialValue: true,
wantValue: true,
policyError: syspolicy.ErrNoSuchKey,
},
{
name: "unset disabled",
initialValue: false,
wantValue: false,
policyError: syspolicy.ErrNoSuchKey,
},
{
name: "error enabled",
initialValue: true,
wantValue: true,
policyError: errors.New("test error"),
},
{
name: "error disabled",
initialValue: false,
wantValue: false,
policyError: errors.New("test error"),
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
for _, pp := range preferencePolicies {
t.Run(string(pp.key), func(t *testing.T) {
var h syspolicy.Handler
allPolicies := make(map[syspolicy.Key]*string, len(preferencePolicies)+1)
allPolicies[syspolicy.ControlURL] = nil
for _, pp := range preferencePolicies {
allPolicies[pp.key] = nil
}
if tt.policyError != nil {
h = &errorSyspolicyHandler{
t: t,
err: tt.policyError,
key: pp.key,
allowKeys: allPolicies,
}
} else {
msh := &mockSyspolicyHandler{
t: t,
stringPolicies: allPolicies,
failUnknownPolicies: true,
}
msh.stringPolicies[pp.key] = &tt.policyValue
h = msh
}
syspolicy.SetHandlerForTest(t, h)
prefs := defaultPrefs.AsStruct()
pp.set(prefs, tt.initialValue)
gotAnyChange := applySysPolicy(prefs)
if gotAnyChange != tt.wantChange {
t.Errorf("anyChange=%v, want %v", gotAnyChange, tt.wantChange)
}
got := pp.get(prefs.View())
if got != tt.wantValue {
t.Errorf("pref=%v, want %v", got, tt.wantValue)
}
})
}
})
}
}

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