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339 lines
9.3 KiB
Go
339 lines
9.3 KiB
Go
//go:build linux
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// +build linux
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/*
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Copyright 2019 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package iptables
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import (
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"context"
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"fmt"
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"io"
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"sync"
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"sync/atomic"
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"testing"
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"time"
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"k8s.io/apimachinery/pkg/util/sets"
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utilwait "k8s.io/apimachinery/pkg/util/wait"
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"k8s.io/utils/exec"
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)
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// We can't use the normal FakeExec because we don't know precisely how many times the
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// Monitor thread will do its checks, and we don't know precisely how its iptables calls
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// will interleave with the main thread's. So we use our own fake Exec implementation that
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// implements a minimal iptables interface. This will need updates as iptables.runner
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// changes its use of Exec.
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type monitorFakeExec struct {
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sync.Mutex
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tables map[string]sets.String
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block bool
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wasBlocked bool
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}
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func newMonitorFakeExec() *monitorFakeExec {
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tables := make(map[string]sets.String)
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tables["mangle"] = sets.NewString()
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tables["filter"] = sets.NewString()
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tables["nat"] = sets.NewString()
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return &monitorFakeExec{tables: tables}
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}
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func (mfe *monitorFakeExec) blockIPTables(block bool) {
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mfe.Lock()
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defer mfe.Unlock()
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mfe.block = block
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}
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func (mfe *monitorFakeExec) getWasBlocked() bool {
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mfe.Lock()
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defer mfe.Unlock()
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wasBlocked := mfe.wasBlocked
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mfe.wasBlocked = false
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return wasBlocked
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}
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func (mfe *monitorFakeExec) Command(cmd string, args ...string) exec.Cmd {
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return &monitorFakeCmd{mfe: mfe, cmd: cmd, args: args}
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}
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func (mfe *monitorFakeExec) CommandContext(ctx context.Context, cmd string, args ...string) exec.Cmd {
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return mfe.Command(cmd, args...)
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}
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func (mfe *monitorFakeExec) LookPath(file string) (string, error) {
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return file, nil
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}
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type monitorFakeCmd struct {
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mfe *monitorFakeExec
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cmd string
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args []string
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}
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func (mfc *monitorFakeCmd) CombinedOutput() ([]byte, error) {
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if mfc.cmd == cmdIPTablesRestore {
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// Only used for "iptables-restore --version", and the result doesn't matter
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return []byte{}, nil
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} else if mfc.cmd != cmdIPTables {
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panic("bad command " + mfc.cmd)
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}
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if len(mfc.args) == 1 && mfc.args[0] == "--version" {
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return []byte("iptables v1.6.2"), nil
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}
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if len(mfc.args) != 8 || mfc.args[0] != WaitString || mfc.args[1] != WaitSecondsValue || mfc.args[2] != WaitIntervalString || mfc.args[3] != WaitIntervalUsecondsValue || mfc.args[6] != "-t" {
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panic(fmt.Sprintf("bad args %#v", mfc.args))
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}
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op := operation(mfc.args[4])
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chainName := mfc.args[5]
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tableName := mfc.args[7]
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mfc.mfe.Lock()
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defer mfc.mfe.Unlock()
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table := mfc.mfe.tables[tableName]
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if table == nil {
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return []byte{}, fmt.Errorf("no such table %q", tableName)
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}
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// For ease-of-testing reasons, blockIPTables blocks create and list, but not delete
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if mfc.mfe.block && op != opDeleteChain {
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mfc.mfe.wasBlocked = true
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return []byte{}, exec.CodeExitError{Code: 4, Err: fmt.Errorf("could not get xtables.lock, etc")}
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}
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switch op {
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case opCreateChain:
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if !table.Has(chainName) {
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table.Insert(chainName)
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}
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return []byte{}, nil
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case opListChain:
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if table.Has(chainName) {
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return []byte{}, nil
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}
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return []byte{}, fmt.Errorf("no such chain %q", chainName)
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case opDeleteChain:
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table.Delete(chainName)
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return []byte{}, nil
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default:
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panic("should not be reached")
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}
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}
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func (mfc *monitorFakeCmd) SetStdin(in io.Reader) {
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// Used by getIPTablesRestoreVersionString(), can be ignored
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}
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func (mfc *monitorFakeCmd) Run() error {
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panic("should not be reached")
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}
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func (mfc *monitorFakeCmd) Output() ([]byte, error) {
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panic("should not be reached")
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}
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func (mfc *monitorFakeCmd) SetDir(dir string) {
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panic("should not be reached")
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}
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func (mfc *monitorFakeCmd) SetStdout(out io.Writer) {
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panic("should not be reached")
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}
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func (mfc *monitorFakeCmd) SetStderr(out io.Writer) {
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panic("should not be reached")
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}
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func (mfc *monitorFakeCmd) SetEnv(env []string) {
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panic("should not be reached")
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}
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func (mfc *monitorFakeCmd) StdoutPipe() (io.ReadCloser, error) {
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panic("should not be reached")
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}
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func (mfc *monitorFakeCmd) StderrPipe() (io.ReadCloser, error) {
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panic("should not be reached")
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}
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func (mfc *monitorFakeCmd) Start() error {
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panic("should not be reached")
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}
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func (mfc *monitorFakeCmd) Wait() error {
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panic("should not be reached")
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}
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func (mfc *monitorFakeCmd) Stop() {
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panic("should not be reached")
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}
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func TestIPTablesMonitor(t *testing.T) {
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mfe := newMonitorFakeExec()
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ipt := New(mfe, ProtocolIPv4)
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var reloads uint32
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stopCh := make(chan struct{})
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canary := Chain("MONITOR-TEST-CANARY")
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tables := []Table{TableMangle, TableFilter, TableNAT}
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go ipt.Monitor(canary, tables, func() {
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if !ensureNoChains(mfe) {
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t.Errorf("reload called while canaries still exist")
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}
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atomic.AddUint32(&reloads, 1)
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}, 100*time.Millisecond, stopCh)
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// Monitor should create canary chains quickly
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if err := waitForChains(mfe, canary, tables); err != nil {
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t.Errorf("failed to create iptables canaries: %v", err)
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}
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if err := waitForReloads(&reloads, 0); err != nil {
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t.Errorf("got unexpected reloads: %v", err)
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}
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// If we delete all of the chains, it should reload
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ipt.DeleteChain(TableMangle, canary)
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ipt.DeleteChain(TableFilter, canary)
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ipt.DeleteChain(TableNAT, canary)
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if err := waitForReloads(&reloads, 1); err != nil {
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t.Errorf("got unexpected number of reloads after flush: %v", err)
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}
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if err := waitForChains(mfe, canary, tables); err != nil {
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t.Errorf("failed to create iptables canaries: %v", err)
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}
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// If we delete two chains, it should not reload yet
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ipt.DeleteChain(TableMangle, canary)
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ipt.DeleteChain(TableFilter, canary)
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if err := waitForNoReload(&reloads, 1); err != nil {
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t.Errorf("got unexpected number of reloads after partial flush: %v", err)
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}
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// Now ensure that "iptables -L" will get an error about the xtables.lock, and
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// delete the last chain. The monitor should not reload, because it can't actually
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// tell if the chain was deleted or not.
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mfe.blockIPTables(true)
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ipt.DeleteChain(TableNAT, canary)
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if err := waitForBlocked(mfe); err != nil {
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t.Errorf("failed waiting for monitor to be blocked from monitoring: %v", err)
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}
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// After unblocking the monitor, it should now reload
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mfe.blockIPTables(false)
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if err := waitForReloads(&reloads, 2); err != nil {
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t.Errorf("got unexpected number of reloads after slow flush: %v", err)
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}
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if err := waitForChains(mfe, canary, tables); err != nil {
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t.Errorf("failed to create iptables canaries: %v", err)
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}
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// If we close the stop channel, it should stop running
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close(stopCh)
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if err := waitForNoReload(&reloads, 2); err != nil {
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t.Errorf("got unexpected number of reloads after stop: %v", err)
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}
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if !ensureNoChains(mfe) {
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t.Errorf("canaries still exist after stopping monitor")
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}
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// If we create a new monitor while the iptables lock is held, it will
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// retry creating canaries until it succeeds
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stopCh = make(chan struct{})
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_ = mfe.getWasBlocked()
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mfe.blockIPTables(true)
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go ipt.Monitor(canary, tables, func() {
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if !ensureNoChains(mfe) {
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t.Errorf("reload called while canaries still exist")
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}
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atomic.AddUint32(&reloads, 1)
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}, 100*time.Millisecond, stopCh)
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// Monitor should not have created canaries yet
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if !ensureNoChains(mfe) {
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t.Errorf("canary created while iptables blocked")
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}
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if err := waitForBlocked(mfe); err != nil {
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t.Errorf("failed waiting for monitor to fail creating canaries: %v", err)
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}
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mfe.blockIPTables(false)
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if err := waitForChains(mfe, canary, tables); err != nil {
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t.Errorf("failed to create iptables canaries: %v", err)
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}
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close(stopCh)
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}
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func waitForChains(mfe *monitorFakeExec, canary Chain, tables []Table) error {
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return utilwait.PollImmediate(100*time.Millisecond, time.Second, func() (bool, error) {
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mfe.Lock()
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defer mfe.Unlock()
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for _, table := range tables {
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if !mfe.tables[string(table)].Has(string(canary)) {
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return false, nil
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}
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}
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return true, nil
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})
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}
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func ensureNoChains(mfe *monitorFakeExec) bool {
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mfe.Lock()
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defer mfe.Unlock()
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return mfe.tables["mangle"].Len() == 0 &&
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mfe.tables["filter"].Len() == 0 &&
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mfe.tables["nat"].Len() == 0
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}
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func waitForReloads(reloads *uint32, expected uint32) error {
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if atomic.LoadUint32(reloads) < expected {
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utilwait.PollImmediate(100*time.Millisecond, time.Second, func() (bool, error) {
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return atomic.LoadUint32(reloads) >= expected, nil
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})
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}
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got := atomic.LoadUint32(reloads)
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if got != expected {
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return fmt.Errorf("expected %d, got %d", expected, got)
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}
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return nil
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}
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func waitForNoReload(reloads *uint32, expected uint32) error {
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utilwait.PollImmediate(50*time.Millisecond, 250*time.Millisecond, func() (bool, error) {
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return atomic.LoadUint32(reloads) > expected, nil
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})
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got := atomic.LoadUint32(reloads)
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if got != expected {
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return fmt.Errorf("expected %d, got %d", expected, got)
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}
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return nil
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}
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func waitForBlocked(mfe *monitorFakeExec) error {
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return utilwait.PollImmediate(100*time.Millisecond, time.Second, func() (bool, error) {
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blocked := mfe.getWasBlocked()
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return blocked, nil
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})
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}
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