Lorenz Brun | 878f5f9 | 2020-05-12 16:15:39 +0200 | [diff] [blame] | 1 | // Copyright 2020 The Monogon Project Authors. |
| 2 | // |
| 3 | // SPDX-License-Identifier: Apache-2.0 |
| 4 | // |
| 5 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | // you may not use this file except in compliance with the License. |
| 7 | // You may obtain a copy of the License at |
| 8 | // |
| 9 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | // |
| 11 | // Unless required by applicable law or agreed to in writing, software |
| 12 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | // See the License for the specific language governing permissions and |
| 15 | // limitations under the License. |
| 16 | |
| 17 | // The reconciler ensures that a base set of K8s resources is always available in the cluster. These are necessary to |
| 18 | // ensure correct out-of-the-box functionality. All resources containing the smalltown.com/builtin=true label are assumed |
| 19 | // to be managed by the reconciler. |
| 20 | // It currently does not revert modifications made by admins, it is planned to create an admission plugin prohibiting |
| 21 | // such modifications to resources with the smalltown.com/builtin label to deal with that problem. This would also solve a |
| 22 | // potential issue where you could delete resources just by adding the smalltown.com/builtin=true label. |
| 23 | package kubernetes |
| 24 | |
| 25 | import ( |
| 26 | "context" |
| 27 | "time" |
| 28 | |
Lorenz Brun | b15abad | 2020-04-16 11:17:12 +0200 | [diff] [blame] | 29 | storagev1 "k8s.io/api/storage/v1" |
| 30 | |
Lorenz Brun | 878f5f9 | 2020-05-12 16:15:39 +0200 | [diff] [blame] | 31 | "go.uber.org/zap" |
| 32 | corev1 "k8s.io/api/core/v1" |
| 33 | "k8s.io/api/policy/v1beta1" |
| 34 | rbacv1 "k8s.io/api/rbac/v1" |
| 35 | metav1 "k8s.io/apimachinery/pkg/apis/meta/v1" |
| 36 | "k8s.io/client-go/kubernetes" |
Lorenz Brun | 8e3b8fc | 2020-05-19 14:29:40 +0200 | [diff] [blame] | 37 | |
| 38 | "git.monogon.dev/source/nexantic.git/core/internal/common/supervisor" |
Lorenz Brun | 878f5f9 | 2020-05-12 16:15:39 +0200 | [diff] [blame] | 39 | ) |
| 40 | |
| 41 | const builtinRBACPrefix = "smalltown:" |
| 42 | |
| 43 | // Sad workaround for all the pointer booleans in K8s specs |
| 44 | func True() *bool { |
| 45 | val := true |
| 46 | return &val |
| 47 | } |
| 48 | func False() *bool { |
| 49 | val := false |
| 50 | return &val |
| 51 | } |
| 52 | |
| 53 | func rbac(name string) string { |
| 54 | return builtinRBACPrefix + name |
| 55 | } |
| 56 | |
| 57 | // Extended from https://github.com/kubernetes/kubernetes/blob/master/cluster/gce/addons/podsecuritypolicies/unprivileged-addon.yaml |
| 58 | var builtinPSPs = []*v1beta1.PodSecurityPolicy{ |
| 59 | { |
| 60 | ObjectMeta: metav1.ObjectMeta{ |
| 61 | Name: "default", |
| 62 | Labels: map[string]string{ |
| 63 | "smalltown.com/builtin": "true", |
| 64 | }, |
| 65 | Annotations: map[string]string{ |
| 66 | "kubernetes.io/description": "This default PSP allows the creation of pods using features that are" + |
| 67 | " generally considered safe against any sort of escape.", |
| 68 | }, |
| 69 | }, |
| 70 | Spec: v1beta1.PodSecurityPolicySpec{ |
| 71 | AllowPrivilegeEscalation: True(), |
| 72 | AllowedCapabilities: []corev1.Capability{ // runc's default list of allowed capabilities |
| 73 | "SETPCAP", |
| 74 | "MKNOD", |
| 75 | "AUDIT_WRITE", |
| 76 | "CHOWN", |
| 77 | "NET_RAW", |
| 78 | "DAC_OVERRIDE", |
| 79 | "FOWNER", |
| 80 | "FSETID", |
| 81 | "KILL", |
| 82 | "SETGID", |
| 83 | "SETUID", |
| 84 | "NET_BIND_SERVICE", |
| 85 | "SYS_CHROOT", |
| 86 | "SETFCAP", |
| 87 | }, |
| 88 | HostNetwork: false, |
| 89 | HostIPC: false, |
| 90 | HostPID: false, |
| 91 | FSGroup: v1beta1.FSGroupStrategyOptions{ |
| 92 | Rule: v1beta1.FSGroupStrategyRunAsAny, |
| 93 | }, |
| 94 | RunAsUser: v1beta1.RunAsUserStrategyOptions{ |
| 95 | Rule: v1beta1.RunAsUserStrategyRunAsAny, |
| 96 | }, |
| 97 | SELinux: v1beta1.SELinuxStrategyOptions{ |
| 98 | Rule: v1beta1.SELinuxStrategyRunAsAny, |
| 99 | }, |
| 100 | SupplementalGroups: v1beta1.SupplementalGroupsStrategyOptions{ |
| 101 | Rule: v1beta1.SupplementalGroupsStrategyRunAsAny, |
| 102 | }, |
| 103 | Volumes: []v1beta1.FSType{ // Volumes considered safe to use |
| 104 | v1beta1.ConfigMap, |
| 105 | v1beta1.EmptyDir, |
| 106 | v1beta1.Projected, |
| 107 | v1beta1.Secret, |
| 108 | v1beta1.DownwardAPI, |
| 109 | v1beta1.PersistentVolumeClaim, |
| 110 | }, |
| 111 | }, |
| 112 | }, |
| 113 | } |
| 114 | |
| 115 | var builtinClusterRoles = []*rbacv1.ClusterRole{ |
| 116 | { |
| 117 | ObjectMeta: metav1.ObjectMeta{ |
| 118 | Name: rbac("psp-default"), |
| 119 | Annotations: map[string]string{ |
| 120 | "kubernetes.io/description": "This role grants access to the \"default\" PSP.", |
| 121 | }, |
| 122 | }, |
| 123 | Rules: []rbacv1.PolicyRule{ |
| 124 | { |
| 125 | APIGroups: []string{"policy"}, |
| 126 | Resources: []string{"podsecuritypolicies"}, |
| 127 | ResourceNames: []string{"default"}, |
| 128 | Verbs: []string{"use"}, |
| 129 | }, |
| 130 | }, |
| 131 | }, |
| 132 | } |
| 133 | |
| 134 | var builtinClusterRoleBindings = []*rbacv1.ClusterRoleBinding{ |
| 135 | { |
| 136 | ObjectMeta: metav1.ObjectMeta{ |
| 137 | Name: rbac("default-psp-for-sa"), |
| 138 | Annotations: map[string]string{ |
| 139 | "kubernetes.io/description": "This binding grants every service account access to the \"default\" PSP. " + |
| 140 | "Creation of Pods is still restricted by other RBAC roles. Otherwise no pods (unprivileged or not) " + |
| 141 | "can be created.", |
| 142 | }, |
| 143 | }, |
| 144 | RoleRef: rbacv1.RoleRef{ |
| 145 | APIGroup: rbacv1.GroupName, |
| 146 | Kind: "ClusterRole", |
| 147 | Name: rbac("psp-default"), |
| 148 | }, |
| 149 | Subjects: []rbacv1.Subject{ |
| 150 | { |
| 151 | APIGroup: rbacv1.GroupName, |
| 152 | Kind: "Group", |
| 153 | Name: "system:serviceaccounts", |
| 154 | }, |
| 155 | }, |
| 156 | }, |
| 157 | { |
| 158 | ObjectMeta: metav1.ObjectMeta{ |
| 159 | Name: rbac("apiserver-kubelet-client"), |
| 160 | Annotations: map[string]string{ |
| 161 | "kubernetes.io/description": "This binding grants the apiserver access to the kubelets. This enables " + |
| 162 | "lots of built-in functionality like reading logs or forwarding ports via the API.", |
| 163 | }, |
| 164 | }, |
| 165 | RoleRef: rbacv1.RoleRef{ |
| 166 | APIGroup: rbacv1.GroupName, |
| 167 | Kind: "ClusterRole", |
| 168 | Name: "system:kubelet-api-admin", |
| 169 | }, |
| 170 | Subjects: []rbacv1.Subject{ |
| 171 | { |
| 172 | APIGroup: rbacv1.GroupName, |
| 173 | Kind: "User", |
| 174 | Name: "smalltown:apiserver-kubelet-client", |
| 175 | }, |
| 176 | }, |
| 177 | }, |
| 178 | } |
| 179 | |
Lorenz Brun | b15abad | 2020-04-16 11:17:12 +0200 | [diff] [blame] | 180 | var reclaimPolicyDelete = corev1.PersistentVolumeReclaimDelete |
| 181 | var waitForConsumerBinding = storagev1.VolumeBindingWaitForFirstConsumer |
Lorenz Brun | 878f5f9 | 2020-05-12 16:15:39 +0200 | [diff] [blame] | 182 | |
Lorenz Brun | b15abad | 2020-04-16 11:17:12 +0200 | [diff] [blame] | 183 | var builtinStorageClasses = []*storagev1.StorageClass{ |
| 184 | { |
| 185 | ObjectMeta: metav1.ObjectMeta{ |
| 186 | Name: "local", |
| 187 | Annotations: map[string]string{ |
| 188 | "storageclass.kubernetes.io/is-default-class": "true", |
| 189 | }, |
| 190 | Labels: map[string]string{ |
| 191 | "smalltown.com/builtin": "true", |
| 192 | }, |
| 193 | }, |
| 194 | AllowVolumeExpansion: True(), |
| 195 | Provisioner: csiProvisionerName, |
| 196 | ReclaimPolicy: &reclaimPolicyDelete, |
| 197 | VolumeBindingMode: &waitForConsumerBinding, |
| 198 | }, |
| 199 | } |
| 200 | |
| 201 | var builtinCSIDrivers = []*storagev1.CSIDriver{ |
| 202 | { |
| 203 | ObjectMeta: metav1.ObjectMeta{ |
| 204 | Name: csiProvisionerName, |
| 205 | Labels: map[string]string{ |
| 206 | "smalltown.com/builtin": "true", |
| 207 | }, |
| 208 | }, |
| 209 | Spec: storagev1.CSIDriverSpec{ |
| 210 | AttachRequired: False(), |
| 211 | PodInfoOnMount: False(), |
| 212 | VolumeLifecycleModes: []storagev1.VolumeLifecycleMode{storagev1.VolumeLifecyclePersistent}, |
| 213 | }, |
| 214 | }, |
| 215 | } |
| 216 | |
| 217 | type reconciler func(context.Context, kubernetes.Interface) error |
| 218 | |
| 219 | func runReconciler(clientSet kubernetes.Interface) supervisor.Runnable { |
Lorenz Brun | 8e3b8fc | 2020-05-19 14:29:40 +0200 | [diff] [blame] | 220 | return func(ctx context.Context) error { |
| 221 | log := supervisor.Logger(ctx) |
Lorenz Brun | 8e3b8fc | 2020-05-19 14:29:40 +0200 | [diff] [blame] | 222 | reconcilers := map[string]reconciler{ |
| 223 | "psps": reconcilePSPs, |
| 224 | "clusterroles": reconcileClusterRoles, |
| 225 | "clusterrolebindings": reconcileClusterRoleBindings, |
Lorenz Brun | b15abad | 2020-04-16 11:17:12 +0200 | [diff] [blame] | 226 | "storageclasses": reconcileSCs, |
| 227 | "csidrivers": reconcileCSIDrivers, |
Lorenz Brun | 8e3b8fc | 2020-05-19 14:29:40 +0200 | [diff] [blame] | 228 | } |
| 229 | t := time.NewTicker(10 * time.Second) |
| 230 | reconcile := func() { |
| 231 | for name, reconciler := range reconcilers { |
| 232 | if err := reconciler(ctx, clientSet); err != nil { |
| 233 | log.Warn("Failed to reconcile built-in resources", zap.String("kind", name), zap.Error(err)) |
| 234 | } |
Lorenz Brun | 878f5f9 | 2020-05-12 16:15:39 +0200 | [diff] [blame] | 235 | } |
Lorenz Brun | 8e3b8fc | 2020-05-19 14:29:40 +0200 | [diff] [blame] | 236 | } |
| 237 | supervisor.Signal(ctx, supervisor.SignalHealthy) |
| 238 | reconcile() |
| 239 | for { |
| 240 | select { |
| 241 | case <-t.C: |
| 242 | reconcile() |
| 243 | case <-ctx.Done(): |
| 244 | return nil |
| 245 | } |
Lorenz Brun | 878f5f9 | 2020-05-12 16:15:39 +0200 | [diff] [blame] | 246 | } |
| 247 | } |
| 248 | } |
| 249 | |
Lorenz Brun | b15abad | 2020-04-16 11:17:12 +0200 | [diff] [blame] | 250 | func reconcilePSPs(ctx context.Context, clientSet kubernetes.Interface) error { |
Lorenz Brun | 8e3b8fc | 2020-05-19 14:29:40 +0200 | [diff] [blame] | 251 | pspClient := clientSet.PolicyV1beta1().PodSecurityPolicies() |
Lorenz Brun | 878f5f9 | 2020-05-12 16:15:39 +0200 | [diff] [blame] | 252 | availablePSPs, err := pspClient.List(ctx, metav1.ListOptions{ |
| 253 | LabelSelector: "smalltown.com/builtin=true", |
| 254 | }) |
| 255 | if err != nil { |
| 256 | return err |
| 257 | } |
| 258 | availablePSPMap := make(map[string]struct{}) |
| 259 | for _, psp := range availablePSPs.Items { |
| 260 | availablePSPMap[psp.Name] = struct{}{} |
| 261 | } |
| 262 | expectedPSPMap := make(map[string]*v1beta1.PodSecurityPolicy) |
| 263 | for _, psp := range builtinPSPs { |
| 264 | expectedPSPMap[psp.Name] = psp |
| 265 | } |
| 266 | for pspName, psp := range expectedPSPMap { |
| 267 | if _, ok := availablePSPMap[pspName]; !ok { |
| 268 | if _, err := pspClient.Create(ctx, psp, metav1.CreateOptions{}); err != nil { |
| 269 | return err |
| 270 | } |
| 271 | } |
| 272 | } |
| 273 | for pspName, _ := range availablePSPMap { |
| 274 | if _, ok := expectedPSPMap[pspName]; !ok { |
| 275 | if err := pspClient.Delete(ctx, pspName, metav1.DeleteOptions{}); err != nil { |
| 276 | return err |
| 277 | } |
| 278 | } |
| 279 | } |
| 280 | return nil |
| 281 | } |
| 282 | |
Lorenz Brun | b15abad | 2020-04-16 11:17:12 +0200 | [diff] [blame] | 283 | func reconcileClusterRoles(ctx context.Context, clientSet kubernetes.Interface) error { |
Lorenz Brun | 8e3b8fc | 2020-05-19 14:29:40 +0200 | [diff] [blame] | 284 | crClient := clientSet.RbacV1().ClusterRoles() |
Lorenz Brun | 878f5f9 | 2020-05-12 16:15:39 +0200 | [diff] [blame] | 285 | availableCRs, err := crClient.List(ctx, metav1.ListOptions{ |
| 286 | LabelSelector: "smalltown.com/builtin=true", |
| 287 | }) |
| 288 | if err != nil { |
| 289 | return err |
| 290 | } |
| 291 | availableCRMap := make(map[string]struct{}) |
| 292 | for _, cr := range availableCRs.Items { |
| 293 | availableCRMap[cr.Name] = struct{}{} |
| 294 | } |
| 295 | expectedCRMap := make(map[string]*rbacv1.ClusterRole) |
| 296 | for _, cr := range builtinClusterRoles { |
| 297 | expectedCRMap[cr.Name] = cr |
| 298 | } |
| 299 | for crName, psp := range expectedCRMap { |
| 300 | if _, ok := availableCRMap[crName]; !ok { |
| 301 | if _, err := crClient.Create(ctx, psp, metav1.CreateOptions{}); err != nil { |
| 302 | return err |
| 303 | } |
| 304 | } |
| 305 | } |
| 306 | for crName, _ := range availableCRMap { |
| 307 | if _, ok := expectedCRMap[crName]; !ok { |
| 308 | if err := crClient.Delete(ctx, crName, metav1.DeleteOptions{}); err != nil { |
| 309 | return err |
| 310 | } |
| 311 | } |
| 312 | } |
| 313 | return nil |
| 314 | } |
| 315 | |
Lorenz Brun | b15abad | 2020-04-16 11:17:12 +0200 | [diff] [blame] | 316 | func reconcileClusterRoleBindings(ctx context.Context, clientset kubernetes.Interface) error { |
Lorenz Brun | 878f5f9 | 2020-05-12 16:15:39 +0200 | [diff] [blame] | 317 | crbClient := clientset.RbacV1().ClusterRoleBindings() |
| 318 | availableCRBs, err := crbClient.List(ctx, metav1.ListOptions{ |
| 319 | LabelSelector: "smalltown.com/builtin=true", |
| 320 | }) |
| 321 | if err != nil { |
| 322 | return err |
| 323 | } |
| 324 | availableCRBMap := make(map[string]struct{}) |
| 325 | for _, crb := range availableCRBs.Items { |
| 326 | availableCRBMap[crb.Name] = struct{}{} |
| 327 | } |
| 328 | expectedCRBMap := make(map[string]*rbacv1.ClusterRoleBinding) |
| 329 | for _, crb := range builtinClusterRoleBindings { |
| 330 | expectedCRBMap[crb.Name] = crb |
| 331 | } |
| 332 | for crbName, psp := range expectedCRBMap { |
| 333 | if _, ok := availableCRBMap[crbName]; !ok { |
| 334 | if _, err := crbClient.Create(ctx, psp, metav1.CreateOptions{}); err != nil { |
| 335 | return err |
| 336 | } |
| 337 | } |
| 338 | } |
| 339 | for crbName, _ := range availableCRBMap { |
| 340 | if _, ok := expectedCRBMap[crbName]; !ok { |
| 341 | if err := crbClient.Delete(ctx, crbName, metav1.DeleteOptions{}); err != nil { |
| 342 | return err |
| 343 | } |
| 344 | } |
| 345 | } |
| 346 | return nil |
| 347 | } |
Lorenz Brun | b15abad | 2020-04-16 11:17:12 +0200 | [diff] [blame] | 348 | |
| 349 | func reconcileSCs(ctx context.Context, clientSet kubernetes.Interface) error { |
| 350 | scsClient := clientSet.StorageV1().StorageClasses() |
| 351 | availableSCs, err := scsClient.List(ctx, metav1.ListOptions{ |
| 352 | LabelSelector: "smalltown.com/builtin=true", |
| 353 | }) |
| 354 | if err != nil { |
| 355 | return err |
| 356 | } |
| 357 | availableSCMap := make(map[string]struct{}) |
| 358 | for _, sc := range availableSCs.Items { |
| 359 | availableSCMap[sc.Name] = struct{}{} |
| 360 | } |
| 361 | expectedSCMap := make(map[string]*storagev1.StorageClass) |
| 362 | for _, sc := range builtinStorageClasses { |
| 363 | expectedSCMap[sc.Name] = sc |
| 364 | } |
| 365 | for scName, sc := range expectedSCMap { |
| 366 | if _, ok := availableSCMap[scName]; !ok { |
| 367 | if _, err := scsClient.Create(ctx, sc, metav1.CreateOptions{}); err != nil { |
| 368 | return err |
| 369 | } |
| 370 | } |
| 371 | } |
| 372 | for pspName, _ := range availableSCMap { |
| 373 | if _, ok := expectedSCMap[pspName]; !ok { |
| 374 | if err := scsClient.Delete(ctx, pspName, metav1.DeleteOptions{}); err != nil { |
| 375 | return err |
| 376 | } |
| 377 | } |
| 378 | } |
| 379 | return nil |
| 380 | } |
| 381 | |
| 382 | func reconcileCSIDrivers(ctx context.Context, clientSet kubernetes.Interface) error { |
| 383 | drvClient := clientSet.StorageV1().CSIDrivers() |
| 384 | availableDrvs, err := drvClient.List(ctx, metav1.ListOptions{ |
| 385 | LabelSelector: "smalltown.com/builtin=true", |
| 386 | }) |
| 387 | if err != nil { |
| 388 | return err |
| 389 | } |
| 390 | availableDrvMap := make(map[string]struct{}) |
| 391 | for _, drv := range availableDrvs.Items { |
| 392 | availableDrvMap[drv.Name] = struct{}{} |
| 393 | } |
| 394 | expectedDrvMap := make(map[string]*storagev1.CSIDriver) |
| 395 | for _, drv := range builtinCSIDrivers { |
| 396 | expectedDrvMap[drv.Name] = drv |
| 397 | } |
| 398 | for drvName, drv := range expectedDrvMap { |
| 399 | if _, ok := availableDrvMap[drvName]; !ok { |
| 400 | if _, err := drvClient.Create(ctx, drv, metav1.CreateOptions{}); err != nil { |
| 401 | return err |
| 402 | } |
| 403 | } |
| 404 | } |
| 405 | for pspName, _ := range availableDrvMap { |
| 406 | if _, ok := expectedDrvMap[pspName]; !ok { |
| 407 | if err := drvClient.Delete(ctx, pspName, metav1.DeleteOptions{}); err != nil { |
| 408 | return err |
| 409 | } |
| 410 | } |
| 411 | } |
| 412 | return nil |
| 413 | } |