-
Notifications
You must be signed in to change notification settings - Fork 39.4k
/
iptables.go
773 lines (658 loc) · 26 KB
/
iptables.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
/*
Copyright 2014 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package iptables
import (
"bytes"
"context"
"fmt"
"regexp"
"strings"
"sync"
"time"
"k8s.io/apimachinery/pkg/util/sets"
utilversion "k8s.io/apimachinery/pkg/util/version"
utilwait "k8s.io/apimachinery/pkg/util/wait"
"k8s.io/klog/v2"
utilexec "k8s.io/utils/exec"
utiltrace "k8s.io/utils/trace"
)
// RulePosition holds the -I/-A flags for iptable
type RulePosition string
const (
// Prepend is the insert flag for iptable
Prepend RulePosition = "-I"
// Append is the append flag for iptable
Append RulePosition = "-A"
)
// Interface is an injectable interface for running iptables commands. Implementations must be goroutine-safe.
type Interface interface {
// EnsureChain checks if the specified chain exists and, if not, creates it. If the chain existed, return true.
EnsureChain(table Table, chain Chain) (bool, error)
// FlushChain clears the specified chain. If the chain did not exist, return error.
FlushChain(table Table, chain Chain) error
// DeleteChain deletes the specified chain. If the chain did not exist, return error.
DeleteChain(table Table, chain Chain) error
// ChainExists tests whether the specified chain exists, returning an error if it
// does not, or if it is unable to check.
ChainExists(table Table, chain Chain) (bool, error)
// EnsureRule checks if the specified rule is present and, if not, creates it. If the rule existed, return true.
EnsureRule(position RulePosition, table Table, chain Chain, args ...string) (bool, error)
// DeleteRule checks if the specified rule is present and, if so, deletes it.
DeleteRule(table Table, chain Chain, args ...string) error
// IsIPv6 returns true if this is managing ipv6 tables.
IsIPv6() bool
// Protocol returns the IP family this instance is managing,
Protocol() Protocol
// SaveInto calls `iptables-save` for table and stores result in a given buffer.
SaveInto(table Table, buffer *bytes.Buffer) error
// Restore runs `iptables-restore` passing data through []byte.
// table is the Table to restore
// data should be formatted like the output of SaveInto()
// flush sets the presence of the "--noflush" flag. see: FlushFlag
// counters sets the "--counters" flag. see: RestoreCountersFlag
Restore(table Table, data []byte, flush FlushFlag, counters RestoreCountersFlag) error
// RestoreAll is the same as Restore except that no table is specified.
RestoreAll(data []byte, flush FlushFlag, counters RestoreCountersFlag) error
// Monitor detects when the given iptables tables have been flushed by an external
// tool (e.g. a firewall reload) by creating canary chains and polling to see if
// they have been deleted. (Specifically, it polls tables[0] every interval until
// the canary has been deleted from there, then waits a short additional time for
// the canaries to be deleted from the remaining tables as well. You can optimize
// the polling by listing a relatively empty table in tables[0]). When a flush is
// detected, this calls the reloadFunc so the caller can reload their own iptables
// rules. If it is unable to create the canary chains (either initially or after
// a reload) it will log an error and stop monitoring.
// (This function should be called from a goroutine.)
Monitor(canary Chain, tables []Table, reloadFunc func(), interval time.Duration, stopCh <-chan struct{})
// HasRandomFully reveals whether `-j MASQUERADE` takes the
// `--random-fully` option. This is helpful to work around a
// Linux kernel bug that sometimes causes multiple flows to get
// mapped to the same IP:PORT and consequently some suffer packet
// drops.
HasRandomFully() bool
}
// Protocol defines the ip protocol either ipv4 or ipv6
type Protocol string
const (
// ProtocolIPv4 represents ipv4 protocol in iptables
ProtocolIPv4 Protocol = "IPv4"
// ProtocolIPv6 represents ipv6 protocol in iptables
ProtocolIPv6 Protocol = "IPv6"
)
// Table represents different iptable like filter,nat, mangle and raw
type Table string
const (
// TableNAT represents the built-in nat table
TableNAT Table = "nat"
// TableFilter represents the built-in filter table
TableFilter Table = "filter"
// TableMangle represents the built-in mangle table
TableMangle Table = "mangle"
)
// Chain represents the different rules
type Chain string
const (
// ChainPostrouting used for source NAT in nat table
ChainPostrouting Chain = "POSTROUTING"
// ChainPrerouting used for DNAT (destination NAT) in nat table
ChainPrerouting Chain = "PREROUTING"
// ChainOutput used for the packets going out from local
ChainOutput Chain = "OUTPUT"
// ChainInput used for incoming packets
ChainInput Chain = "INPUT"
// ChainForward used for the packets for another NIC
ChainForward Chain = "FORWARD"
)
const (
cmdIPTablesSave string = "iptables-save"
cmdIPTablesRestore string = "iptables-restore"
cmdIPTables string = "iptables"
cmdIP6TablesRestore string = "ip6tables-restore"
cmdIP6TablesSave string = "ip6tables-save"
cmdIP6Tables string = "ip6tables"
)
// RestoreCountersFlag is an option flag for Restore
type RestoreCountersFlag bool
// RestoreCounters a boolean true constant for the option flag RestoreCountersFlag
const RestoreCounters RestoreCountersFlag = true
// NoRestoreCounters a boolean false constant for the option flag RestoreCountersFlag
const NoRestoreCounters RestoreCountersFlag = false
// FlushFlag an option flag for Flush
type FlushFlag bool
// FlushTables a boolean true constant for option flag FlushFlag
const FlushTables FlushFlag = true
// NoFlushTables a boolean false constant for option flag FlushFlag
const NoFlushTables FlushFlag = false
// MinCheckVersion minimum version to be checked
// Versions of iptables less than this do not support the -C / --check flag
// (test whether a rule exists).
var MinCheckVersion = utilversion.MustParseGeneric("1.4.11")
// RandomFullyMinVersion is the minimum version from which the --random-fully flag is supported,
// used for port mapping to be fully randomized
var RandomFullyMinVersion = utilversion.MustParseGeneric("1.6.2")
// WaitMinVersion a minimum iptables versions supporting the -w and -w<seconds> flags
var WaitMinVersion = utilversion.MustParseGeneric("1.4.20")
// WaitIntervalMinVersion a minimum iptables versions supporting the wait interval useconds
var WaitIntervalMinVersion = utilversion.MustParseGeneric("1.6.1")
// WaitSecondsMinVersion a minimum iptables versions supporting the wait seconds
var WaitSecondsMinVersion = utilversion.MustParseGeneric("1.4.22")
// WaitRestoreMinVersion a minimum iptables versions supporting the wait restore seconds
var WaitRestoreMinVersion = utilversion.MustParseGeneric("1.6.2")
// WaitString a constant for specifying the wait flag
const WaitString = "-w"
// WaitSecondsValue a constant for specifying the default wait seconds
const WaitSecondsValue = "5"
// WaitIntervalString a constant for specifying the wait interval flag
const WaitIntervalString = "-W"
// WaitIntervalUsecondsValue a constant for specifying the default wait interval useconds
const WaitIntervalUsecondsValue = "100000"
// LockfilePath16x is the iptables 1.6.x lock file acquired by any process that's making any change in the iptable rule
const LockfilePath16x = "/run/xtables.lock"
// LockfilePath14x is the iptables 1.4.x lock file acquired by any process that's making any change in the iptable rule
const LockfilePath14x = "@xtables"
// runner implements Interface in terms of exec("iptables").
type runner struct {
mu sync.Mutex
exec utilexec.Interface
protocol Protocol
hasCheck bool
hasRandomFully bool
waitFlag []string
restoreWaitFlag []string
lockfilePath14x string
lockfilePath16x string
}
// newInternal returns a new Interface which will exec iptables, and allows the
// caller to change the iptables-restore lockfile path
func newInternal(exec utilexec.Interface, protocol Protocol, lockfilePath14x, lockfilePath16x string) Interface {
version, err := getIPTablesVersion(exec, protocol)
if err != nil {
klog.Warningf("Error checking iptables version, assuming version at least %s: %v", MinCheckVersion, err)
version = MinCheckVersion
}
if lockfilePath16x == "" {
lockfilePath16x = LockfilePath16x
}
if lockfilePath14x == "" {
lockfilePath14x = LockfilePath14x
}
runner := &runner{
exec: exec,
protocol: protocol,
hasCheck: version.AtLeast(MinCheckVersion),
hasRandomFully: version.AtLeast(RandomFullyMinVersion),
waitFlag: getIPTablesWaitFlag(version),
restoreWaitFlag: getIPTablesRestoreWaitFlag(version, exec, protocol),
lockfilePath14x: lockfilePath14x,
lockfilePath16x: lockfilePath16x,
}
return runner
}
// New returns a new Interface which will exec iptables.
func New(exec utilexec.Interface, protocol Protocol) Interface {
return newInternal(exec, protocol, "", "")
}
// EnsureChain is part of Interface.
func (runner *runner) EnsureChain(table Table, chain Chain) (bool, error) {
fullArgs := makeFullArgs(table, chain)
runner.mu.Lock()
defer runner.mu.Unlock()
out, err := runner.run(opCreateChain, fullArgs)
if err != nil {
if ee, ok := err.(utilexec.ExitError); ok {
if ee.Exited() && ee.ExitStatus() == 1 {
return true, nil
}
}
return false, fmt.Errorf("error creating chain %q: %v: %s", chain, err, out)
}
return false, nil
}
// FlushChain is part of Interface.
func (runner *runner) FlushChain(table Table, chain Chain) error {
fullArgs := makeFullArgs(table, chain)
runner.mu.Lock()
defer runner.mu.Unlock()
out, err := runner.run(opFlushChain, fullArgs)
if err != nil {
return fmt.Errorf("error flushing chain %q: %v: %s", chain, err, out)
}
return nil
}
// DeleteChain is part of Interface.
func (runner *runner) DeleteChain(table Table, chain Chain) error {
fullArgs := makeFullArgs(table, chain)
runner.mu.Lock()
defer runner.mu.Unlock()
// TODO: we could call iptables -S first, ignore the output and check for non-zero return (more like DeleteRule)
out, err := runner.run(opDeleteChain, fullArgs)
if err != nil {
return fmt.Errorf("error deleting chain %q: %v: %s", chain, err, out)
}
return nil
}
// EnsureRule is part of Interface.
func (runner *runner) EnsureRule(position RulePosition, table Table, chain Chain, args ...string) (bool, error) {
fullArgs := makeFullArgs(table, chain, args...)
runner.mu.Lock()
defer runner.mu.Unlock()
exists, err := runner.checkRule(table, chain, args...)
if err != nil {
return false, err
}
if exists {
return true, nil
}
out, err := runner.run(operation(position), fullArgs)
if err != nil {
return false, fmt.Errorf("error appending rule: %v: %s", err, out)
}
return false, nil
}
// DeleteRule is part of Interface.
func (runner *runner) DeleteRule(table Table, chain Chain, args ...string) error {
fullArgs := makeFullArgs(table, chain, args...)
runner.mu.Lock()
defer runner.mu.Unlock()
exists, err := runner.checkRule(table, chain, args...)
if err != nil {
return err
}
if !exists {
return nil
}
out, err := runner.run(opDeleteRule, fullArgs)
if err != nil {
return fmt.Errorf("error deleting rule: %v: %s", err, out)
}
return nil
}
func (runner *runner) IsIPv6() bool {
return runner.protocol == ProtocolIPv6
}
func (runner *runner) Protocol() Protocol {
return runner.protocol
}
// SaveInto is part of Interface.
func (runner *runner) SaveInto(table Table, buffer *bytes.Buffer) error {
runner.mu.Lock()
defer runner.mu.Unlock()
trace := utiltrace.New("iptables save")
defer trace.LogIfLong(2 * time.Second)
// run and return
iptablesSaveCmd := iptablesSaveCommand(runner.protocol)
args := []string{"-t", string(table)}
klog.V(4).Infof("running %s %v", iptablesSaveCmd, args)
cmd := runner.exec.Command(iptablesSaveCmd, args...)
cmd.SetStdout(buffer)
stderrBuffer := bytes.NewBuffer(nil)
cmd.SetStderr(stderrBuffer)
err := cmd.Run()
if err != nil {
stderrBuffer.WriteTo(buffer) // ignore error, since we need to return the original error
}
return err
}
// Restore is part of Interface.
func (runner *runner) Restore(table Table, data []byte, flush FlushFlag, counters RestoreCountersFlag) error {
// setup args
args := []string{"-T", string(table)}
return runner.restoreInternal(args, data, flush, counters)
}
// RestoreAll is part of Interface.
func (runner *runner) RestoreAll(data []byte, flush FlushFlag, counters RestoreCountersFlag) error {
// setup args
args := make([]string, 0)
return runner.restoreInternal(args, data, flush, counters)
}
type iptablesLocker interface {
Close() error
}
// restoreInternal is the shared part of Restore/RestoreAll
func (runner *runner) restoreInternal(args []string, data []byte, flush FlushFlag, counters RestoreCountersFlag) error {
runner.mu.Lock()
defer runner.mu.Unlock()
trace := utiltrace.New("iptables restore")
defer trace.LogIfLong(2 * time.Second)
if !flush {
args = append(args, "--noflush")
}
if counters {
args = append(args, "--counters")
}
// Grab the iptables lock to prevent iptables-restore and iptables
// from stepping on each other. iptables-restore 1.6.2 will have
// a --wait option like iptables itself, but that's not widely deployed.
if len(runner.restoreWaitFlag) == 0 {
locker, err := grabIptablesLocks(runner.lockfilePath14x, runner.lockfilePath16x)
if err != nil {
return err
}
trace.Step("Locks grabbed")
defer func(locker iptablesLocker) {
if err := locker.Close(); err != nil {
klog.Errorf("Failed to close iptables locks: %v", err)
}
}(locker)
}
// run the command and return the output or an error including the output and error
fullArgs := append(runner.restoreWaitFlag, args...)
iptablesRestoreCmd := iptablesRestoreCommand(runner.protocol)
klog.V(4).Infof("running %s %v", iptablesRestoreCmd, fullArgs)
cmd := runner.exec.Command(iptablesRestoreCmd, fullArgs...)
cmd.SetStdin(bytes.NewBuffer(data))
b, err := cmd.CombinedOutput()
if err != nil {
return fmt.Errorf("%v (%s)", err, b)
}
return nil
}
func iptablesSaveCommand(protocol Protocol) string {
if protocol == ProtocolIPv6 {
return cmdIP6TablesSave
}
return cmdIPTablesSave
}
func iptablesRestoreCommand(protocol Protocol) string {
if protocol == ProtocolIPv6 {
return cmdIP6TablesRestore
}
return cmdIPTablesRestore
}
func iptablesCommand(protocol Protocol) string {
if protocol == ProtocolIPv6 {
return cmdIP6Tables
}
return cmdIPTables
}
func (runner *runner) run(op operation, args []string) ([]byte, error) {
return runner.runContext(context.TODO(), op, args)
}
func (runner *runner) runContext(ctx context.Context, op operation, args []string) ([]byte, error) {
iptablesCmd := iptablesCommand(runner.protocol)
fullArgs := append(runner.waitFlag, string(op))
fullArgs = append(fullArgs, args...)
klog.V(5).Infof("running iptables: %s %v", iptablesCmd, fullArgs)
if ctx == nil {
return runner.exec.Command(iptablesCmd, fullArgs...).CombinedOutput()
}
return runner.exec.CommandContext(ctx, iptablesCmd, fullArgs...).CombinedOutput()
// Don't log err here - callers might not think it is an error.
}
// Returns (bool, nil) if it was able to check the existence of the rule, or
// (<undefined>, error) if the process of checking failed.
func (runner *runner) checkRule(table Table, chain Chain, args ...string) (bool, error) {
if runner.hasCheck {
return runner.checkRuleUsingCheck(makeFullArgs(table, chain, args...))
}
return runner.checkRuleWithoutCheck(table, chain, args...)
}
var hexnumRE = regexp.MustCompile("0x0+([0-9])")
func trimhex(s string) string {
return hexnumRE.ReplaceAllString(s, "0x$1")
}
// Executes the rule check without using the "-C" flag, instead parsing iptables-save.
// Present for compatibility with <1.4.11 versions of iptables. This is full
// of hack and half-measures. We should nix this ASAP.
func (runner *runner) checkRuleWithoutCheck(table Table, chain Chain, args ...string) (bool, error) {
iptablesSaveCmd := iptablesSaveCommand(runner.protocol)
klog.V(1).Infof("running %s -t %s", iptablesSaveCmd, string(table))
out, err := runner.exec.Command(iptablesSaveCmd, "-t", string(table)).CombinedOutput()
if err != nil {
return false, fmt.Errorf("error checking rule: %v", err)
}
// Sadly, iptables has inconsistent quoting rules for comments. Just remove all quotes.
// Also, quoted multi-word comments (which are counted as a single arg)
// will be unpacked into multiple args,
// in order to compare against iptables-save output (which will be split at whitespace boundary)
// e.g. a single arg('"this must be before the NodePort rules"') will be unquoted and unpacked into 7 args.
var argsCopy []string
for i := range args {
tmpField := strings.Trim(args[i], "\"")
tmpField = trimhex(tmpField)
argsCopy = append(argsCopy, strings.Fields(tmpField)...)
}
argset := sets.NewString(argsCopy...)
for _, line := range strings.Split(string(out), "\n") {
var fields = strings.Fields(line)
// Check that this is a rule for the correct chain, and that it has
// the correct number of argument (+2 for "-A <chain name>")
if !strings.HasPrefix(line, fmt.Sprintf("-A %s", string(chain))) || len(fields) != len(argsCopy)+2 {
continue
}
// Sadly, iptables has inconsistent quoting rules for comments.
// Just remove all quotes.
for i := range fields {
fields[i] = strings.Trim(fields[i], "\"")
fields[i] = trimhex(fields[i])
}
// TODO: This misses reorderings e.g. "-x foo ! -y bar" will match "! -x foo -y bar"
if sets.NewString(fields...).IsSuperset(argset) {
return true, nil
}
klog.V(5).Infof("DBG: fields is not a superset of args: fields=%v args=%v", fields, args)
}
return false, nil
}
// Executes the rule check using the "-C" flag
func (runner *runner) checkRuleUsingCheck(args []string) (bool, error) {
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
defer cancel()
out, err := runner.runContext(ctx, opCheckRule, args)
if ctx.Err() == context.DeadlineExceeded {
return false, fmt.Errorf("timed out while checking rules")
}
if err == nil {
return true, nil
}
if ee, ok := err.(utilexec.ExitError); ok {
// iptables uses exit(1) to indicate a failure of the operation,
// as compared to a malformed commandline, for example.
if ee.Exited() && ee.ExitStatus() == 1 {
return false, nil
}
}
return false, fmt.Errorf("error checking rule: %v: %s", err, out)
}
const (
// Max time we wait for an iptables flush to complete after we notice it has started
iptablesFlushTimeout = 5 * time.Second
// How often we poll while waiting for an iptables flush to complete
iptablesFlushPollTime = 100 * time.Millisecond
)
// Monitor is part of Interface
func (runner *runner) Monitor(canary Chain, tables []Table, reloadFunc func(), interval time.Duration, stopCh <-chan struct{}) {
for {
_ = utilwait.PollImmediateUntil(interval, func() (bool, error) {
for _, table := range tables {
if _, err := runner.EnsureChain(table, canary); err != nil {
klog.Warningf("Could not set up iptables canary %s/%s: %v", string(table), string(canary), err)
return false, nil
}
}
return true, nil
}, stopCh)
// Poll until stopCh is closed or iptables is flushed
err := utilwait.PollUntil(interval, func() (bool, error) {
if exists, err := runner.ChainExists(tables[0], canary); exists {
return false, nil
} else if isResourceError(err) {
klog.Warningf("Could not check for iptables canary %s/%s: %v", string(tables[0]), string(canary), err)
return false, nil
}
klog.V(2).Infof("iptables canary %s/%s deleted", string(tables[0]), string(canary))
// Wait for the other canaries to be deleted too before returning
// so we don't start reloading too soon.
err := utilwait.PollImmediate(iptablesFlushPollTime, iptablesFlushTimeout, func() (bool, error) {
for i := 1; i < len(tables); i++ {
if exists, err := runner.ChainExists(tables[i], canary); exists || isResourceError(err) {
return false, nil
}
}
return true, nil
})
if err != nil {
klog.Warning("Inconsistent iptables state detected.")
}
return true, nil
}, stopCh)
if err != nil {
// stopCh was closed
for _, table := range tables {
_ = runner.DeleteChain(table, canary)
}
return
}
klog.V(2).Infof("Reloading after iptables flush")
reloadFunc()
}
}
// ChainExists is part of Interface
func (runner *runner) ChainExists(table Table, chain Chain) (bool, error) {
fullArgs := makeFullArgs(table, chain)
runner.mu.Lock()
defer runner.mu.Unlock()
trace := utiltrace.New("iptables ChainExists")
defer trace.LogIfLong(2 * time.Second)
_, err := runner.run(opListChain, fullArgs)
return err == nil, err
}
type operation string
const (
opCreateChain operation = "-N"
opFlushChain operation = "-F"
opDeleteChain operation = "-X"
opListChain operation = "-S"
opCheckRule operation = "-C"
opDeleteRule operation = "-D"
)
func makeFullArgs(table Table, chain Chain, args ...string) []string {
return append([]string{string(chain), "-t", string(table)}, args...)
}
const iptablesVersionPattern = `v([0-9]+(\.[0-9]+)+)`
// getIPTablesVersion runs "iptables --version" and parses the returned version
func getIPTablesVersion(exec utilexec.Interface, protocol Protocol) (*utilversion.Version, error) {
// this doesn't access mutable state so we don't need to use the interface / runner
iptablesCmd := iptablesCommand(protocol)
bytes, err := exec.Command(iptablesCmd, "--version").CombinedOutput()
if err != nil {
return nil, err
}
versionMatcher := regexp.MustCompile(iptablesVersionPattern)
match := versionMatcher.FindStringSubmatch(string(bytes))
if match == nil {
return nil, fmt.Errorf("no iptables version found in string: %s", bytes)
}
version, err := utilversion.ParseGeneric(match[1])
if err != nil {
return nil, fmt.Errorf("iptables version %q is not a valid version string: %v", match[1], err)
}
return version, nil
}
// Checks if iptables version has a "wait" flag
func getIPTablesWaitFlag(version *utilversion.Version) []string {
switch {
case version.AtLeast(WaitIntervalMinVersion):
return []string{WaitString, WaitSecondsValue, WaitIntervalString, WaitIntervalUsecondsValue}
case version.AtLeast(WaitSecondsMinVersion):
return []string{WaitString, WaitSecondsValue}
case version.AtLeast(WaitMinVersion):
return []string{WaitString}
default:
return nil
}
}
// Checks if iptables-restore has a "wait" flag
func getIPTablesRestoreWaitFlag(version *utilversion.Version, exec utilexec.Interface, protocol Protocol) []string {
if version.AtLeast(WaitRestoreMinVersion) {
return []string{WaitString, WaitSecondsValue, WaitIntervalString, WaitIntervalUsecondsValue}
}
// Older versions may have backported features; if iptables-restore supports
// --version, assume it also supports --wait
vstring, err := getIPTablesRestoreVersionString(exec, protocol)
if err != nil || vstring == "" {
klog.V(3).Infof("couldn't get iptables-restore version; assuming it doesn't support --wait")
return nil
}
if _, err := utilversion.ParseGeneric(vstring); err != nil {
klog.V(3).Infof("couldn't parse iptables-restore version; assuming it doesn't support --wait")
return nil
}
return []string{WaitString}
}
// getIPTablesRestoreVersionString runs "iptables-restore --version" to get the version string
// in the form "X.X.X"
func getIPTablesRestoreVersionString(exec utilexec.Interface, protocol Protocol) (string, error) {
// this doesn't access mutable state so we don't need to use the interface / runner
// iptables-restore hasn't always had --version, and worse complains
// about unrecognized commands but doesn't exit when it gets them.
// Work around that by setting stdin to nothing so it exits immediately.
iptablesRestoreCmd := iptablesRestoreCommand(protocol)
cmd := exec.Command(iptablesRestoreCmd, "--version")
cmd.SetStdin(bytes.NewReader([]byte{}))
bytes, err := cmd.CombinedOutput()
if err != nil {
return "", err
}
versionMatcher := regexp.MustCompile(iptablesVersionPattern)
match := versionMatcher.FindStringSubmatch(string(bytes))
if match == nil {
return "", fmt.Errorf("no iptables version found in string: %s", bytes)
}
return match[1], nil
}
func (runner *runner) HasRandomFully() bool {
return runner.hasRandomFully
}
var iptablesNotFoundStrings = []string{
// iptables-legacy [-A|-I] BAD-CHAIN [...]
// iptables-legacy [-C|-D] GOOD-CHAIN [...non-matching rule...]
// iptables-legacy [-X|-F|-Z] BAD-CHAIN
// iptables-nft -X BAD-CHAIN
// NB: iptables-nft [-F|-Z] BAD-CHAIN exits with no error
"No chain/target/match by that name",
// iptables-legacy [...] -j BAD-CHAIN
// iptables-nft-1.8.0 [-A|-I] BAD-CHAIN [...]
// iptables-nft-1.8.0 [-A|-I] GOOD-CHAIN -j BAD-CHAIN
// NB: also matches some other things like "-m BAD-MODULE"
"No such file or directory",
// iptables-legacy [-C|-D] BAD-CHAIN [...]
// iptables-nft [-C|-D] GOOD-CHAIN [...non-matching rule...]
"does a matching rule exist",
// iptables-nft-1.8.2 [-A|-C|-D|-I] BAD-CHAIN [...]
// iptables-nft-1.8.2 [...] -j BAD-CHAIN
"does not exist",
}
// IsNotFoundError returns true if the error indicates "not found". It parses
// the error string looking for known values, which is imperfect; beware using
// this function for anything beyond deciding between logging or ignoring an
// error.
func IsNotFoundError(err error) bool {
es := err.Error()
for _, str := range iptablesNotFoundStrings {
if strings.Contains(es, str) {
return true
}
}
return false
}
const iptablesStatusResourceProblem = 4
// isResourceError returns true if the error indicates that iptables ran into a "resource
// problem" and was unable to attempt the request. In particular, this will be true if it
// times out trying to get the iptables lock.
func isResourceError(err error) bool {
if ee, isExitError := err.(utilexec.ExitError); isExitError {
return ee.ExitStatus() == iptablesStatusResourceProblem
}
return false
}