/
hostport_manager.go
444 lines (388 loc) · 15.2 KB
/
hostport_manager.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
/*
Copyright 2017 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 hostport
import (
"bytes"
"crypto/sha256"
"encoding/base32"
"fmt"
"net"
"strconv"
"strings"
"sync"
v1 "k8s.io/api/core/v1"
utilerrors "k8s.io/apimachinery/pkg/util/errors"
"k8s.io/klog/v2"
iptablesproxy "k8s.io/kubernetes/pkg/proxy/iptables"
"k8s.io/kubernetes/pkg/util/conntrack"
utiliptables "k8s.io/kubernetes/pkg/util/iptables"
"k8s.io/utils/exec"
utilnet "k8s.io/utils/net"
)
// HostPortManager is an interface for adding and removing hostport for a given pod sandbox.
// nolint:golint // no reason to change the type name now "type name will be used as hostport.HostPortManager by other packages"
type HostPortManager interface {
// Add implements port mappings.
// id should be a unique identifier for a pod, e.g. podSandboxID.
// podPortMapping is the associated port mapping information for the pod.
// natInterfaceName is the interface that localhost uses to talk to the given pod, if known.
Add(id string, podPortMapping *PodPortMapping, natInterfaceName string) error
// Remove cleans up matching port mappings
// Remove must be able to clean up port mappings without pod IP
Remove(id string, podPortMapping *PodPortMapping) error
}
type hostportManager struct {
hostPortMap map[hostport]closeable
execer exec.Interface
conntrackFound bool
iptables utiliptables.Interface
portOpener hostportOpener
mu sync.Mutex
}
// NewHostportManager creates a new HostPortManager
func NewHostportManager(iptables utiliptables.Interface) HostPortManager {
h := &hostportManager{
hostPortMap: make(map[hostport]closeable),
execer: exec.New(),
iptables: iptables,
portOpener: openLocalPort,
}
h.conntrackFound = conntrack.Exists(h.execer)
if !h.conntrackFound {
klog.Warningf("The binary conntrack is not installed, this can cause failures in network connection cleanup.")
}
return h
}
func (hm *hostportManager) Add(id string, podPortMapping *PodPortMapping, natInterfaceName string) (err error) {
if podPortMapping == nil || podPortMapping.HostNetwork {
return nil
}
podFullName := getPodFullName(podPortMapping)
// IP.To16() returns nil if IP is not a valid IPv4 or IPv6 address
if podPortMapping.IP.To16() == nil {
return fmt.Errorf("invalid or missing IP of pod %s", podFullName)
}
podIP := podPortMapping.IP.String()
isIPv6 := utilnet.IsIPv6(podPortMapping.IP)
// skip if there is no hostport needed
hostportMappings := gatherHostportMappings(podPortMapping, isIPv6)
if len(hostportMappings) == 0 {
return nil
}
if isIPv6 != hm.iptables.IsIPv6() {
return fmt.Errorf("HostPortManager IP family mismatch: %v, isIPv6 - %v", podIP, isIPv6)
}
if err := ensureKubeHostportChains(hm.iptables, natInterfaceName); err != nil {
return err
}
// Ensure atomicity for port opening and iptables operations
hm.mu.Lock()
defer hm.mu.Unlock()
// try to open hostports
ports, err := hm.openHostports(podPortMapping)
if err != nil {
return err
}
for hostport, socket := range ports {
hm.hostPortMap[hostport] = socket
}
natChains := bytes.NewBuffer(nil)
natRules := bytes.NewBuffer(nil)
writeLine(natChains, "*nat")
existingChains, existingRules, err := getExistingHostportIPTablesRules(hm.iptables)
if err != nil {
// clean up opened host port if encounter any error
return utilerrors.NewAggregate([]error{err, hm.closeHostports(hostportMappings)})
}
newChains := []utiliptables.Chain{}
conntrackPortsToRemove := []int{}
for _, pm := range hostportMappings {
protocol := strings.ToLower(string(pm.Protocol))
chain := getHostportChain(id, pm)
newChains = append(newChains, chain)
if pm.Protocol == v1.ProtocolUDP {
conntrackPortsToRemove = append(conntrackPortsToRemove, int(pm.HostPort))
}
// Add new hostport chain
writeLine(natChains, utiliptables.MakeChainLine(chain))
// Prepend the new chain to KUBE-HOSTPORTS
// This avoids any leaking iptables rule that takes up the same port
writeLine(natRules, "-I", string(kubeHostportsChain),
"-m", "comment", "--comment", fmt.Sprintf(`"%s hostport %d"`, podFullName, pm.HostPort),
"-m", protocol, "-p", protocol, "--dport", fmt.Sprintf("%d", pm.HostPort),
"-j", string(chain),
)
// SNAT if the traffic comes from the pod itself
writeLine(natRules, "-A", string(chain),
"-m", "comment", "--comment", fmt.Sprintf(`"%s hostport %d"`, podFullName, pm.HostPort),
"-s", podIP,
"-j", string(iptablesproxy.KubeMarkMasqChain))
// DNAT to the podIP:containerPort
hostPortBinding := net.JoinHostPort(podIP, strconv.Itoa(int(pm.ContainerPort)))
if pm.HostIP == "" || pm.HostIP == "0.0.0.0" || pm.HostIP == "::" {
writeLine(natRules, "-A", string(chain),
"-m", "comment", "--comment", fmt.Sprintf(`"%s hostport %d"`, podFullName, pm.HostPort),
"-m", protocol, "-p", protocol,
"-j", "DNAT", fmt.Sprintf("--to-destination=%s", hostPortBinding))
} else {
writeLine(natRules, "-A", string(chain),
"-m", "comment", "--comment", fmt.Sprintf(`"%s hostport %d"`, podFullName, pm.HostPort),
"-m", protocol, "-p", protocol, "-d", pm.HostIP,
"-j", "DNAT", fmt.Sprintf("--to-destination=%s", hostPortBinding))
}
}
// getHostportChain should be able to provide unique hostport chain name using hash
// if there is a chain conflict or multiple Adds have been triggered for a single pod,
// filtering should be able to avoid further problem
filterChains(existingChains, newChains)
existingRules = filterRules(existingRules, newChains)
for _, chain := range existingChains {
writeLine(natChains, chain)
}
for _, rule := range existingRules {
writeLine(natRules, rule)
}
writeLine(natRules, "COMMIT")
if err = hm.syncIPTables(append(natChains.Bytes(), natRules.Bytes()...)); err != nil {
// clean up opened host port if encounter any error
return utilerrors.NewAggregate([]error{err, hm.closeHostports(hostportMappings)})
}
// Remove conntrack entries just after adding the new iptables rules. If the conntrack entry is removed along with
// the IP tables rule, it can be the case that the packets received by the node after iptables rule removal will
// create a new conntrack entry without any DNAT. That will result in blackhole of the traffic even after correct
// iptables rules have been added back.
if hm.execer != nil && hm.conntrackFound {
klog.Infof("Starting to delete udp conntrack entries: %v, isIPv6 - %v", conntrackPortsToRemove, isIPv6)
for _, port := range conntrackPortsToRemove {
err = conntrack.ClearEntriesForPort(hm.execer, port, isIPv6, v1.ProtocolUDP)
if err != nil {
klog.Errorf("Failed to clear udp conntrack for port %d, error: %v", port, err)
}
}
}
return nil
}
func (hm *hostportManager) Remove(id string, podPortMapping *PodPortMapping) (err error) {
if podPortMapping == nil || podPortMapping.HostNetwork {
return nil
}
hostportMappings := gatherHostportMappings(podPortMapping, hm.iptables.IsIPv6())
if len(hostportMappings) == 0 {
return nil
}
// Ensure atomicity for port closing and iptables operations
hm.mu.Lock()
defer hm.mu.Unlock()
var existingChains map[utiliptables.Chain]string
var existingRules []string
existingChains, existingRules, err = getExistingHostportIPTablesRules(hm.iptables)
if err != nil {
return err
}
// Gather target hostport chains for removal
chainsToRemove := []utiliptables.Chain{}
for _, pm := range hostportMappings {
chainsToRemove = append(chainsToRemove, getHostportChain(id, pm))
}
// remove rules that consists of target chains
remainingRules := filterRules(existingRules, chainsToRemove)
// gather target hostport chains that exists in iptables-save result
existingChainsToRemove := []utiliptables.Chain{}
for _, chain := range chainsToRemove {
if _, ok := existingChains[chain]; ok {
existingChainsToRemove = append(existingChainsToRemove, chain)
}
}
// exit if there is nothing to remove
if len(existingChainsToRemove) == 0 {
return nil
}
natChains := bytes.NewBuffer(nil)
natRules := bytes.NewBuffer(nil)
writeLine(natChains, "*nat")
for _, chain := range existingChains {
writeLine(natChains, chain)
}
for _, rule := range remainingRules {
writeLine(natRules, rule)
}
for _, chain := range existingChainsToRemove {
writeLine(natRules, "-X", string(chain))
}
writeLine(natRules, "COMMIT")
if err := hm.syncIPTables(append(natChains.Bytes(), natRules.Bytes()...)); err != nil {
return err
}
// clean up opened pod host ports
return hm.closeHostports(hostportMappings)
}
// syncIPTables executes iptables-restore with given lines
func (hm *hostportManager) syncIPTables(lines []byte) error {
klog.V(3).Infof("Restoring iptables rules: %s", lines)
err := hm.iptables.RestoreAll(lines, utiliptables.NoFlushTables, utiliptables.RestoreCounters)
if err != nil {
return fmt.Errorf("failed to execute iptables-restore: %v", err)
}
return nil
}
// openHostports opens all given hostports using the given hostportOpener
// If encounter any error, clean up and return the error
// If all ports are opened successfully, return the hostport and socket mapping
func (hm *hostportManager) openHostports(podPortMapping *PodPortMapping) (map[hostport]closeable, error) {
var retErr error
ports := make(map[hostport]closeable)
for _, pm := range podPortMapping.PortMappings {
if pm.HostPort <= 0 {
continue
}
// We do not open host ports for SCTP ports, as we agreed in the Support of SCTP KEP
if pm.Protocol == v1.ProtocolSCTP {
continue
}
// HostIP IP family is not handled by this port opener
if pm.HostIP != "" && utilnet.IsIPv6String(pm.HostIP) != hm.iptables.IsIPv6() {
continue
}
hp := portMappingToHostport(pm, hm.getIPFamily())
socket, err := hm.portOpener(&hp)
if err != nil {
retErr = fmt.Errorf("cannot open hostport %d for pod %s: %v", pm.HostPort, getPodFullName(podPortMapping), err)
break
}
ports[hp] = socket
}
// If encounter any error, close all hostports that just got opened.
if retErr != nil {
for hp, socket := range ports {
if err := socket.Close(); err != nil {
klog.Errorf("Cannot clean up hostport %d for pod %s: %v", hp.port, getPodFullName(podPortMapping), err)
}
}
return nil, retErr
}
return ports, nil
}
// closeHostports tries to close all the listed host ports
func (hm *hostportManager) closeHostports(hostportMappings []*PortMapping) error {
errList := []error{}
for _, pm := range hostportMappings {
hp := portMappingToHostport(pm, hm.getIPFamily())
if socket, ok := hm.hostPortMap[hp]; ok {
klog.V(2).Infof("Closing host port %s", hp.String())
if err := socket.Close(); err != nil {
errList = append(errList, fmt.Errorf("failed to close host port %s: %v", hp.String(), err))
continue
}
delete(hm.hostPortMap, hp)
} else {
klog.V(5).Infof("host port %s does not have an open socket", hp.String())
}
}
return utilerrors.NewAggregate(errList)
}
// getIPFamily returns the hostPortManager IP family
func (hm *hostportManager) getIPFamily() ipFamily {
family := IPv4
if hm.iptables.IsIPv6() {
family = IPv6
}
return family
}
// getHostportChain takes id, hostport and protocol for a pod and returns associated iptables chain.
// This is computed by hashing (sha256) then encoding to base32 and truncating with the prefix
// "KUBE-HP-". We do this because IPTables Chain Names must be <= 28 chars long, and the longer
// they are the harder they are to read.
// WARNING: Please do not change this function. Otherwise, HostportManager may not be able to
// identify existing iptables chains.
func getHostportChain(id string, pm *PortMapping) utiliptables.Chain {
hash := sha256.Sum256([]byte(id + strconv.Itoa(int(pm.HostPort)) + string(pm.Protocol) + pm.HostIP))
encoded := base32.StdEncoding.EncodeToString(hash[:])
return utiliptables.Chain(kubeHostportChainPrefix + encoded[:16])
}
// gatherHostportMappings returns all the PortMappings which has hostport for a pod
// it filters the PortMappings that use HostIP and doesn't match the IP family specified
func gatherHostportMappings(podPortMapping *PodPortMapping, isIPv6 bool) []*PortMapping {
mappings := []*PortMapping{}
for _, pm := range podPortMapping.PortMappings {
if pm.HostPort <= 0 {
continue
}
if pm.HostIP != "" && utilnet.IsIPv6String(pm.HostIP) != isIPv6 {
continue
}
mappings = append(mappings, pm)
}
return mappings
}
// getExistingHostportIPTablesRules retrieves raw data from iptables-save, parse it,
// return all the hostport related chains and rules
// nolint:gocritic // unnamedResult: consider giving a name to these results
func getExistingHostportIPTablesRules(iptables utiliptables.Interface) (map[utiliptables.Chain]string, []string, error) {
iptablesData := bytes.NewBuffer(nil)
err := iptables.SaveInto(utiliptables.TableNAT, iptablesData)
if err != nil { // if we failed to get any rules
return nil, nil, fmt.Errorf("failed to execute iptables-save: %v", err)
}
existingNATChains := utiliptables.GetChainLines(utiliptables.TableNAT, iptablesData.Bytes())
existingHostportChains := make(map[utiliptables.Chain]string)
existingHostportRules := []string{}
for chain := range existingNATChains {
if strings.HasPrefix(string(chain), string(kubeHostportsChain)) || strings.HasPrefix(string(chain), kubeHostportChainPrefix) {
existingHostportChains[chain] = string(existingNATChains[chain])
}
}
for _, line := range strings.Split(iptablesData.String(), "\n") {
if strings.HasPrefix(line, fmt.Sprintf("-A %s", kubeHostportChainPrefix)) ||
strings.HasPrefix(line, fmt.Sprintf("-A %s", string(kubeHostportsChain))) {
existingHostportRules = append(existingHostportRules, line)
}
}
return existingHostportChains, existingHostportRules, nil
}
// filterRules filters input rules with input chains. Rules that did not involve any filter chain will be returned.
// The order of the input rules is important and is preserved.
func filterRules(rules []string, filters []utiliptables.Chain) []string {
filtered := []string{}
for _, rule := range rules {
skip := false
for _, filter := range filters {
if strings.Contains(rule, string(filter)) {
skip = true
break
}
}
if !skip {
filtered = append(filtered, rule)
}
}
return filtered
}
// filterChains deletes all entries of filter chains from chain map
func filterChains(chains map[utiliptables.Chain]string, filterChains []utiliptables.Chain) {
for _, chain := range filterChains {
delete(chains, chain)
}
}
func getPodFullName(pod *PodPortMapping) string {
// Use underscore as the delimiter because it is not allowed in pod name
// (DNS subdomain format), while allowed in the container name format.
return pod.Name + "_" + pod.Namespace
}
// Join all words with spaces, terminate with newline and write to buf.
// nolint:interfacer
func writeLine(buf *bytes.Buffer, words ...string) {
buf.WriteString(strings.Join(words, " ") + "\n")
}
func (hp *hostport) String() string {
return fmt.Sprintf("%s:%d", hp.protocol, hp.port)
}