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| 1 | +/* |
| 2 | +Copyright 2017 The Kubernetes Authors. |
| 3 | +
|
| 4 | +Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | +you may not use this file except in compliance with the License. |
| 6 | +You may obtain a copy of the License at |
| 7 | +
|
| 8 | + http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | +
|
| 10 | +Unless required by applicable law or agreed to in writing, software |
| 11 | +distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | +See the License for the specific language governing permissions and |
| 14 | +limitations under the License. |
| 15 | +*/ |
| 16 | + |
| 17 | +// Extracted from k8s.io/kubernetes/pkg/kubelet/certificate/transport.go, will be removed |
| 18 | +// when openshift-sdn and the network components move out of the Kubelet. Is intended ONLY |
| 19 | +// to provide certificate rollover until 3.8/3.9. |
| 20 | +package transport |
| 21 | + |
| 22 | +import ( |
| 23 | + "context" |
| 24 | + "crypto/tls" |
| 25 | + "fmt" |
| 26 | + "net" |
| 27 | + "net/http" |
| 28 | + "sync" |
| 29 | + "time" |
| 30 | + |
| 31 | + "github.com/golang/glog" |
| 32 | + |
| 33 | + utilnet "k8s.io/apimachinery/pkg/util/net" |
| 34 | + utilruntime "k8s.io/apimachinery/pkg/util/runtime" |
| 35 | + "k8s.io/apimachinery/pkg/util/wait" |
| 36 | + restclient "k8s.io/client-go/rest" |
| 37 | + "k8s.io/kubernetes/pkg/kubelet/certificate" |
| 38 | +) |
| 39 | + |
| 40 | +// RefreshCertificateAfterExpiry instruments a restconfig with a transport that checks |
| 41 | +// disk to reload expired certificates. |
| 42 | +// |
| 43 | +// The config must not already provide an explicit transport. |
| 44 | +// |
| 45 | +// The returned transport periodically checks the manager to determine if the |
| 46 | +// certificate has changed. If it has, the transport shuts down all existing client |
| 47 | +// connections, forcing the client to re-handshake with the server and use the |
| 48 | +// new certificate. |
| 49 | +// |
| 50 | +// stopCh should be used to indicate when the transport is unused and doesn't need |
| 51 | +// to continue checking the manager. |
| 52 | +func RefreshCertificateAfterExpiry(stopCh <-chan struct{}, period time.Duration, clientConfig *restclient.Config, store certificate.Store) error { |
| 53 | + if clientConfig.Transport != nil { |
| 54 | + return fmt.Errorf("there is already a transport configured") |
| 55 | + } |
| 56 | + tlsConfig, err := restclient.TLSConfigFor(clientConfig) |
| 57 | + if err != nil { |
| 58 | + return fmt.Errorf("unable to configure TLS for the rest client: %v", err) |
| 59 | + } |
| 60 | + if tlsConfig == nil { |
| 61 | + tlsConfig = &tls.Config{} |
| 62 | + } |
| 63 | + manager := &certificateManager{ |
| 64 | + store: store, |
| 65 | + minimumRefresh: period, |
| 66 | + // begin attempting to refresh the certificate before it expires, assuming that rotation occurs before |
| 67 | + // expiration |
| 68 | + expireWindow: 3 * time.Minute, |
| 69 | + } |
| 70 | + tlsConfig.Certificates = nil |
| 71 | + tlsConfig.GetClientCertificate = func(requestInfo *tls.CertificateRequestInfo) (*tls.Certificate, error) { |
| 72 | + cert := manager.Current() |
| 73 | + if cert == nil { |
| 74 | + return &tls.Certificate{Certificate: nil}, nil |
| 75 | + } |
| 76 | + return cert, nil |
| 77 | + } |
| 78 | + |
| 79 | + // Custom dialer that will track all connections it creates. |
| 80 | + t := &connTracker{ |
| 81 | + dialer: &net.Dialer{Timeout: 30 * time.Second, KeepAlive: 30 * time.Second}, |
| 82 | + conns: make(map[*closableConn]struct{}), |
| 83 | + } |
| 84 | + |
| 85 | + // Watch for certs to change, and then close connections after at least one period has elapsed. |
| 86 | + lastCert := manager.Current() |
| 87 | + detectedCertChange := false |
| 88 | + go wait.Until(func() { |
| 89 | + if detectedCertChange { |
| 90 | + // To avoid races with new connections getting old certificates after the close happens, wait |
| 91 | + // at least period before closing connections. |
| 92 | + detectedCertChange = false |
| 93 | + glog.Infof("certificate rotation detected, shutting down client connections to start using new credentials") |
| 94 | + // The cert has been rotated. Close all existing connections to force the client |
| 95 | + // to reperform its TLS handshake with new cert. |
| 96 | + // |
| 97 | + // See: https://github.com/kubernetes-incubator/bootkube/pull/663#issuecomment-318506493 |
| 98 | + t.closeAllConns() |
| 99 | + } |
| 100 | + curr := manager.Current() |
| 101 | + if curr == nil || lastCert == curr { |
| 102 | + // Cert hasn't been rotated. |
| 103 | + return |
| 104 | + } |
| 105 | + lastCert = curr |
| 106 | + detectedCertChange = true |
| 107 | + }, period, stopCh) |
| 108 | + |
| 109 | + clientConfig.Transport = utilnet.SetTransportDefaults(&http.Transport{ |
| 110 | + TLSClientConfig: tlsConfig, |
| 111 | + MaxIdleConnsPerHost: 25, |
| 112 | + DialContext: t.DialContext, // Use custom dialer. |
| 113 | + }) |
| 114 | + |
| 115 | + // Zero out all existing TLS options since our new transport enforces them. |
| 116 | + clientConfig.CertData = nil |
| 117 | + clientConfig.KeyData = nil |
| 118 | + clientConfig.CertFile = "" |
| 119 | + clientConfig.KeyFile = "" |
| 120 | + clientConfig.CAData = nil |
| 121 | + clientConfig.CAFile = "" |
| 122 | + clientConfig.Insecure = false |
| 123 | + return nil |
| 124 | +} |
| 125 | + |
| 126 | +// certificateManager reloads the requested certificate from disk when requested. |
| 127 | +type certificateManager struct { |
| 128 | + store certificate.Store |
| 129 | + minimumRefresh time.Duration |
| 130 | + expireWindow time.Duration |
| 131 | + |
| 132 | + lock sync.Mutex |
| 133 | + cert *tls.Certificate |
| 134 | + lastCheck time.Time |
| 135 | +} |
| 136 | + |
| 137 | +// Current retrieves the latest certificate from disk if it exists, or nil if |
| 138 | +// no certificate could be found. The last successfully loaded certificate will be |
| 139 | +// returned. |
| 140 | +func (m *certificateManager) Current() *tls.Certificate { |
| 141 | + m.lock.Lock() |
| 142 | + defer m.lock.Unlock() |
| 143 | + |
| 144 | + // check whether the cert has expired and whether we've waited long enough since our last |
| 145 | + // check to look again |
| 146 | + cert := m.cert |
| 147 | + if cert != nil { |
| 148 | + now := time.Now() |
| 149 | + if now.After(cert.Leaf.NotAfter.Add(-m.expireWindow)) { |
| 150 | + if now.Sub(m.lastCheck) > m.minimumRefresh { |
| 151 | + glog.V(2).Infof("Current client certificate is about to expire, checking from disk") |
| 152 | + cert = nil |
| 153 | + m.lastCheck = now |
| 154 | + } |
| 155 | + } |
| 156 | + } |
| 157 | + |
| 158 | + // load the cert from disk and parse the leaf cert |
| 159 | + if cert == nil { |
| 160 | + glog.V(2).Infof("Refreshing client certificate from store") |
| 161 | + c, err := m.store.Current() |
| 162 | + if err != nil { |
| 163 | + utilruntime.HandleError(fmt.Errorf("Unable to load client certificate key pair from disk: %v", err)) |
| 164 | + return nil |
| 165 | + } |
| 166 | + m.cert = c |
| 167 | + } |
| 168 | + return m.cert |
| 169 | +} |
| 170 | + |
| 171 | +// connTracker is a dialer that tracks all open connections it creates. |
| 172 | +type connTracker struct { |
| 173 | + dialer *net.Dialer |
| 174 | + |
| 175 | + mu sync.Mutex |
| 176 | + conns map[*closableConn]struct{} |
| 177 | +} |
| 178 | + |
| 179 | +// closeAllConns forcibly closes all tracked connections. |
| 180 | +func (c *connTracker) closeAllConns() { |
| 181 | + c.mu.Lock() |
| 182 | + conns := c.conns |
| 183 | + c.conns = make(map[*closableConn]struct{}) |
| 184 | + c.mu.Unlock() |
| 185 | + |
| 186 | + for conn := range conns { |
| 187 | + conn.Close() |
| 188 | + } |
| 189 | +} |
| 190 | + |
| 191 | +func (c *connTracker) DialContext(ctx context.Context, network, address string) (net.Conn, error) { |
| 192 | + conn, err := c.dialer.DialContext(ctx, network, address) |
| 193 | + if err != nil { |
| 194 | + return nil, err |
| 195 | + } |
| 196 | + |
| 197 | + closable := &closableConn{Conn: conn} |
| 198 | + |
| 199 | + // Start tracking the connection |
| 200 | + c.mu.Lock() |
| 201 | + c.conns[closable] = struct{}{} |
| 202 | + c.mu.Unlock() |
| 203 | + |
| 204 | + // When the connection is closed, remove it from the map. This will |
| 205 | + // be no-op if the connection isn't in the map, e.g. if closeAllConns() |
| 206 | + // is called. |
| 207 | + closable.onClose = func() { |
| 208 | + c.mu.Lock() |
| 209 | + delete(c.conns, closable) |
| 210 | + c.mu.Unlock() |
| 211 | + } |
| 212 | + |
| 213 | + return closable, nil |
| 214 | +} |
| 215 | + |
| 216 | +type closableConn struct { |
| 217 | + onClose func() |
| 218 | + net.Conn |
| 219 | +} |
| 220 | + |
| 221 | +func (c *closableConn) Close() error { |
| 222 | + go c.onClose() |
| 223 | + return c.Conn.Close() |
| 224 | +} |
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