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| 1 | +package cabundleinjector |
| 2 | + |
| 3 | +import ( |
| 4 | + "context" |
| 5 | + "fmt" |
| 6 | + "os" |
| 7 | + "sync/atomic" |
| 8 | + "time" |
| 9 | + |
| 10 | + "k8s.io/klog/v2" |
| 11 | + |
| 12 | + "github.com/openshift/library-go/pkg/controller/fileobserver" |
| 13 | +) |
| 14 | + |
| 15 | +type bundleCache struct { |
| 16 | + v atomic.Pointer[[]byte] |
| 17 | +} |
| 18 | + |
| 19 | +func (c *bundleCache) Load() []byte { |
| 20 | + if dataPtr := c.v.Load(); dataPtr != nil { |
| 21 | + return *dataPtr |
| 22 | + } |
| 23 | + return nil |
| 24 | +} |
| 25 | + |
| 26 | +func (c *bundleCache) Store(data []byte) { |
| 27 | + if data == nil { |
| 28 | + c.v.Store(nil) |
| 29 | + } else { |
| 30 | + c.v.Store(&data) |
| 31 | + } |
| 32 | +} |
| 33 | + |
| 34 | +type bundlesWatcher struct { |
| 35 | + // caBundle contains the signing CA bundle. |
| 36 | + CABundle *bundleCache |
| 37 | + // caBundleLegacy is constructed so that it matches what the old KCM used to do. |
| 38 | + // The signing CA bundle is appended to the service account ca.crt. |
| 39 | + CABundleLegacy *bundleCache |
| 40 | + |
| 41 | + // OnReadFailed can be set for custom read error handling. |
| 42 | + // When the hook returns the original error, it is logged. |
| 43 | + // Logging happens automatically when no hook is set. |
| 44 | + OnReadFailed func(context.Context, error) error |
| 45 | + |
| 46 | + caBundlePath string |
| 47 | + saTokenCABundlePath string |
| 48 | + pollingInterval time.Duration |
| 49 | + resyncInterval time.Duration |
| 50 | + maxReadAttempts int |
| 51 | + |
| 52 | + // readFile is used to read files from disk. |
| 53 | + // Used for mocking during tests mostly. |
| 54 | + readFile func(string) ([]byte, error) |
| 55 | +} |
| 56 | + |
| 57 | +func newBundlesWatcher( |
| 58 | + caBundlePath string, saTokenCABundlePath string, |
| 59 | + pollingInterval time.Duration, |
| 60 | + resyncInterval time.Duration, |
| 61 | + maxReadAttempts int, |
| 62 | +) *bundlesWatcher { |
| 63 | + return &bundlesWatcher{ |
| 64 | + CABundle: &bundleCache{}, |
| 65 | + CABundleLegacy: &bundleCache{}, |
| 66 | + caBundlePath: caBundlePath, |
| 67 | + saTokenCABundlePath: saTokenCABundlePath, |
| 68 | + pollingInterval: pollingInterval, |
| 69 | + resyncInterval: resyncInterval, |
| 70 | + maxReadAttempts: maxReadAttempts, |
| 71 | + readFile: os.ReadFile, |
| 72 | + } |
| 73 | +} |
| 74 | + |
| 75 | +func (w *bundlesWatcher) Start(ctx context.Context) error { |
| 76 | + var ( |
| 77 | + caBundleData []byte |
| 78 | + saTokenCAData []byte |
| 79 | + ) |
| 80 | + reload := func(onError func(context.Context, error) error) error { |
| 81 | + var ( |
| 82 | + legacyCABundleData []byte |
| 83 | + err error |
| 84 | + ) |
| 85 | + caBundleData, saTokenCAData, legacyCABundleData, err = w.readBundles() |
| 86 | + if err != nil { |
| 87 | + // On read errors, keep existing cached content |
| 88 | + // until the next successful read. |
| 89 | + if onError != nil { |
| 90 | + err = onError(ctx, err) |
| 91 | + } |
| 92 | + return err |
| 93 | + } |
| 94 | + |
| 95 | + w.CABundle.Store(caBundleData) |
| 96 | + w.CABundleLegacy.Store(legacyCABundleData) |
| 97 | + return nil |
| 98 | + } |
| 99 | + |
| 100 | + // Read the files initially. This is how the previous implementation worked, so we retain that. |
| 101 | + if err := reload(nil); err != nil { |
| 102 | + return err |
| 103 | + } |
| 104 | + |
| 105 | + // Start watching. |
| 106 | + observer, err := fileobserver.NewObserver(w.pollingInterval) |
| 107 | + if err != nil { |
| 108 | + return fmt.Errorf("failed to start CA bundles observer: %w", err) |
| 109 | + } |
| 110 | + |
| 111 | + observer.AddReactor(func(_ string, _ fileobserver.ActionType) error { |
| 112 | + return reload(w.OnReadFailed) |
| 113 | + }, map[string][]byte{ |
| 114 | + w.caBundlePath: caBundleData, |
| 115 | + w.saTokenCABundlePath: saTokenCAData, |
| 116 | + }, w.caBundlePath, w.saTokenCABundlePath) |
| 117 | + |
| 118 | + go observer.Run(ctx.Done()) |
| 119 | + |
| 120 | + // Periodically re-read the bundles as a safety net |
| 121 | + // in case the file observer reactor callback fails. |
| 122 | + if w.resyncInterval > 0 { |
| 123 | + go func() { |
| 124 | + ticker := time.NewTicker(w.resyncInterval) |
| 125 | + defer ticker.Stop() |
| 126 | + for { |
| 127 | + select { |
| 128 | + case <-ctx.Done(): |
| 129 | + return |
| 130 | + case <-ticker.C: |
| 131 | + if err := reload(w.OnReadFailed); err != nil { |
| 132 | + klog.Errorf("Failed to resync CA bundles: %v", err) |
| 133 | + } |
| 134 | + } |
| 135 | + } |
| 136 | + }() |
| 137 | + } |
| 138 | + |
| 139 | + return nil |
| 140 | +} |
| 141 | + |
| 142 | +func (w *bundlesWatcher) readBundles() ([]byte, []byte, []byte, error) { |
| 143 | + caBundleContent, err := w.readFileWithRetries(w.caBundlePath) |
| 144 | + if err != nil { |
| 145 | + if os.IsNotExist(err) { |
| 146 | + return nil, nil, nil, nil |
| 147 | + } |
| 148 | + return nil, nil, nil, fmt.Errorf("failed to read %q: %w", w.caBundlePath, err) |
| 149 | + } |
| 150 | + |
| 151 | + // This construction matches what the old KCM used to do. |
| 152 | + // It added the entire ca.crt to the service account ca.crt. |
| 153 | + vulnerableLegacyCABundleContent := append([]byte{}, caBundleContent...) |
| 154 | + saTokenCABundleContent, err := w.readFileWithRetries(w.saTokenCABundlePath) |
| 155 | + if err != nil && !os.IsNotExist(err) { |
| 156 | + return nil, nil, nil, fmt.Errorf("failed to read %q: %w", w.saTokenCABundlePath, err) |
| 157 | + } |
| 158 | + if len(saTokenCABundleContent) > 0 { |
| 159 | + vulnerableLegacyCABundleContent = append(vulnerableLegacyCABundleContent, saTokenCABundleContent...) |
| 160 | + vulnerableLegacyCABundleContent = append(vulnerableLegacyCABundleContent, []byte("\n")...) |
| 161 | + } |
| 162 | + |
| 163 | + return caBundleContent, saTokenCABundleContent, vulnerableLegacyCABundleContent, nil |
| 164 | +} |
| 165 | + |
| 166 | +func (w *bundlesWatcher) readFileWithRetries(path string) ([]byte, error) { |
| 167 | + numAttempts := w.maxReadAttempts |
| 168 | + if numAttempts <= 0 { |
| 169 | + numAttempts = 1 |
| 170 | + } |
| 171 | + |
| 172 | + var lastErr error |
| 173 | + for range numAttempts { |
| 174 | + content, err := w.readFile(path) |
| 175 | + if err == nil { |
| 176 | + return content, nil |
| 177 | + } |
| 178 | + lastErr = err |
| 179 | + } |
| 180 | + return nil, lastErr |
| 181 | +} |
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