[TEP-0089] SPIRE for non-falsifiable provenance.

This PR is a part of a larger set of PRs to provide non-falsifiable
provenance through SPIRE.
In particular this PR uses the SPIRE infrastructure which has already
been merged to sign TaskRunStatus.
It also has support to verify if TaskRunStatus has been modified by
another workload between reconciles.

Update pkg/pod/pod.go

Co-authored-by: Jerop Kipruto <[email protected]>

Update pkg/pod/pod.go

Co-authored-by: Jerop Kipruto <[email protected]>

Update pkg/pod/pod.go

Co-authored-by: Jerop Kipruto <[email protected]>

Author: jagathprakash

docs/spire.md

@@ -6,13 +6,58 @@ weight: 1660
 -->
 ⚠️ This is a work in progress: SPIRE support is not yet functional
 
-TaskRun result attestations is currently an alpha experimental feature. Currently all that is implemented is support for configuring Tekton to connect to SPIRE. See TEP-0089 for details on the overall design and feature set.
+TaskRun result attestations is currently an alpha experimental feature. Currently all that is implemented is support for configuring Tekton to connect to SPIRE and enabling TaskRun to sign and verify the TaskRunStatus. See [TEP-0089](https://github.com/tektoncd/community/blob/main/teps/0089-nonfalsifiable-provenance-support.md) for details on the overall design and feature set.
 
 This being a large feature, this will be implemented in the following phases. This document will be updated as we implement new phases.
 1.  Add a client for SPIRE (done).
-2.  Add a configMap which initializes SPIRE (in progress).
-3.  Modify TaskRun to sign and verify TaskRun Results using SPIRE.
-4.  Modify Tekton Chains to verify the TaskRun Results.
+2.  Add a configMap which initializes SPIRE (done).
+3.  Modify TaskRun to sign and verify TaskRunStatus using SPIRE (done). 
+4.  Enabling Chains to verify the TaskRun Results.
+
+When the TaskRun result attestations feature is [enabled](./spire.md#enabling-taskrun-result-attestations) all TaskRuns will produce a signature alongside its results, which can then be used to validate its provenance. For example, a TaskRun result that creates user-specified results `commit` and `url` would look like the following. `SVID`, `RESULT_MANIFEST`, `RESULT_MANIFEST.sig`, `commit.sig` and `url.sig` are generated attestations by the integration of SPIRE and Tekton Controller.
+
+Parsed, the fields would be:
+```
+...
+<truncated>
+...
+📝 Results
+
+ NAME                    VALUE
+ ∙ RESULT_MANIFEST       commit,url,SVID,commit.sig,url.sig
+ ∙ RESULT_MANIFEST.sig   MEUCIQD55MMII9SEk/esQvwNLGC43y7efNGZ+7fsTdq+9vXYFAIgNoRW7cV9WKriZkcHETIaAKqfcZVJfsKbEmaDyohDSm4=
+ ∙ SVID                  -----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+ ∙ commit       aa79de59c4bae24e32f15fda467d02ae9cd94b01
+ ∙ commit.sig   MEQCIEJHk+8B+mCFozp0F52TQ1AadlhEo1lZNOiOnb/ht71aAiBCE0otKB1R0BktlPvweFPldfZfjG0F+NUSc2gPzhErzg==
+ ∙ url          https://github.com/buildpacks/samples
+ ∙ url.sig      MEUCIF0Fuxr6lv1MmkreqDKcPH3m+eXp+gY++VcxWgGCx7T1AiEA9U/tROrKuCGfKApLq2A9EModbdoGXyQXFOpAa0aMpOg=
+```
+
+However, the verification materials are removed from the final results as part of the TaskRun status. It is stored in the termination messages (more details below):
+
+```
+$ tkn tr describe cache-image-pipelinerun-8dq9c-fetch-from-git
+...
+<truncated>
+...
+📝 Results
+ NAME                    VALUE
+ ∙ commit       aa79de59c4bae24e32f15fda467d02ae9cd94b01
+ ∙ url          https://github.com/buildpacks/samples
+```
 
 ## Architecture Overview
 
@@ -64,7 +109,7 @@ When a TaskRun is created:
 ## Enabling TaskRun result attestations
 
 To enable TaskRun attestations:
-1. Make sure `enforce-nonfalsifiability` is set to `"spire"` in the `feature-flags` configmap, see [`install.md`](./install.md#customizing-the-pipelines-controller-behavior) for details
+1. Make sure `enforce-nonfalsifiability` is set to `"spire"` in the `feature-flags` configmap, see [`additional-configs.md`](./additional-configs.md#customizing-the-pipelines-controller-behavior) for details
 1. Create a SPIRE deployment containing a SPIRE server, SPIRE agents and the SPIRE CSI driver, for convenience, [this sample single cluster deployment](https://github.com/spiffe/spiffe-csi/tree/main/example/config) can be used.
 1. Register the SPIRE workload entry for Tekton with the "Admin" flag, which will allow the Tekton controller to communicate with the SPIRE server to manage the TaskRun identities dynamically.
     ```
@@ -127,3 +172,204 @@ To enable TaskRun attestations:
       # spire-node-alias-prefix specifies the SPIRE node alias prefix to use.
       spire-node-alias-prefix: "/tekton-node/"
     ```
+
+## Sample TaskRun attestation
+
+The following example shows how this feature works:
+
+```yaml
+kind: TaskRun
+apiVersion: tekton.dev/v1beta1
+metadata:
+  name: non-falsifiable-provenance
+spec:
+  timeout: 60s
+  taskSpec:
+    steps:
+    - name: non-falsifiable
+      image: ubuntu
+      script: |
+        #!/usr/bin/env bash
+        printf "%s" "hello" > "$(results.foo.path)"
+        printf "%s" "world" > "$(results.bar.path)"
+    results:
+    - name: foo
+    - name: bar
+```
+
+
+The termination message is:
+```
+message: '[{"key":"RESULT_MANIFEST","value":"foo,bar","type":1},{"key":"RESULT_MANIFEST.sig","value":"MEQCIB4grfqBkcsGuVyoQd9KUVzNZaFGN6jQOKK90p5HWHqeAiB7yZerDA+YE3Af/ALG43DQzygiBpKhTt8gzWGmpvXJFw==","type":1},{"key":"SVID","value":"-----BEGIN
+        CERTIFICATE-----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\n-----END
+        CERTIFICATE-----\n","type":1},{"key":"bar","value":"world","type":1},{"key":"bar.sig","value":"MEUCIQDOtg+aEP1FCr6/FsHX+bY1d5abSQn2kTiUMg4Uic2lVQIgTVF5bbT/O77VxESSMtQlpBreMyw2GmKX2hYJlaOEH1M=","type":1},{"key":"foo","value":"hello","type":1},{"key":"foo.sig","value":"MEQCIBr+k0i7SRSyb4h96vQE9hhxBZiZb/2PXQqReOKJDl/rAiBrjgSsalwOvN0zgQay0xQ7PRbm5YSmI8tvKseLR8Ryww==","type":1}]'
+```
+
+Parsed, the fields are:
+- `RESULT_MANIFEST`: List of results that should be present, to prevent pick and choose attacks
+- `RESULT_MANIFEST.sig`: The signature of the result manifest
+- `SVID`: The x509 certificate that will be used to verify the signature trust chain to the authority
+- `*.sig`: The signature of each individual result output
+```
+ ∙ RESULT_MANIFEST       foo,bar
+ ∙ RESULT_MANIFEST.sig   MEQCIB4grfqBkcsGuVyoQd9KUVzNZaFGN6jQOKK90p5HWHqeAiB7yZerDA+YE3Af/ALG43DQzygiBpKhTt8gzWGmpvXJFw==
+ ∙ SVID                  -----BEGIN CERTIFICATE-----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==
+-----END CERTIFICATE-----
+ ∙ bar       world
+ ∙ bar.sig   MEUCIQDOtg+aEP1FCr6/FsHX+bY1d5abSQn2kTiUMg4Uic2lVQIgTVF5bbT/O77VxESSMtQlpBreMyw2GmKX2hYJlaOEH1M=
+ ∙ foo       hello
+ ∙ foo.sig   MEQCIBr+k0i7SRSyb4h96vQE9hhxBZiZb/2PXQqReOKJDl/rAiBrjgSsalwOvN0zgQay0xQ7PRbm5YSmI8tvKseLR8Ryww==
+```
+
+
+However, the verification materials are removed from the results as part of the TaskRun status:
+```console
+$ tkn tr describe non-falsifiable-provenance
+Name:              non-falsifiable-provenance
+Namespace:         default
+Service Account:   default
+Timeout:           1m0s
+Labels:
+ app.kubernetes.io/managed-by=tekton-pipelines
+
+🌡️  Status
+
+STARTED          DURATION     STATUS
+38 seconds ago   36 seconds   Succeeded
+
+📝 Results
+
+ NAME        VALUE
+ ∙ bar       world
+ ∙ foo       hello
+
+🦶 Steps
+
+ NAME                STATUS
+ ∙ non-falsifiable   Completed
+```
+
+## How is the result being verified
+
+The signatures are being verified by the Tekton controller, the process of verification is as follows:
+
+- Verifying the SVID
+  - Obtain the trust bundle from the SPIRE server
+  - Verify the SVID with the trust bundle
+  - Verify that the SVID spiffe ID is for the correct TaskRun
+- Verifying the result manifest
+  - Verify the content of `RESULT_MANIFEST` with the field `RESULT_MANIFEST.sig` with the SVID public key
+  - Verify that there is a corresponding field for all items listed in `RESULT_MANIFEST` (besides SVID and `*.sig` fields)
+- Verify individual result fields
+  - For each of the items in the results, verify its content against its associated `.sig` field
+
+
+# TaskRun Status attestations
+
+Each TaskRun status that is written by the tekton-pipelines-controller will be signed to ensure that there is no external
+tampering of the TaskRun status. Upon each retrieval of the TaskRun, the tekton-pipelines-controller checks if the status is initialized,
+and that the signature validates the current status.
+The signature and SVID will be stored as annotations on the TaskRun Status field, and can be verified by a client.
+
+The verification is done on every consumption of the TaskRun except when the TaskRun is uninitialized. When uninitialized, the 
+tekton-pipelines-controller is not influenced by fields in the status and thus will not sign incorrect reflections of the TaskRun.
+
+The spec and TaskRun annotations/labels are not signed when there are valid interactions from other controllers or users (i.e. cancelling taskrun).
+Editing the object annotations/labels or spec will not result in any unverifiable outcome of the status field.
+
+As the TaskRun progresses, the Pipeline Controller will reconcile the TaskRun object and continually verify the current hash against the `tekton.dev/status-hash-sig` before updating the hash to match the new status and creating a new signature.
+
+An example TaskRun annotations would be:
+
+```console
+$ tkn tr describe non-falsifiable-provenance -oyaml
+apiVersion: tekton.dev/v1beta1
+kind: TaskRun
+metadata:
+  annotations:
+    pipeline.tekton.dev/release: 3ee99ec
+  creationTimestamp: "2022-03-04T19:10:46Z"
+  generation: 1
+  labels:
+    app.kubernetes.io/managed-by: tekton-pipelines
+  name: non-falsifiable-provenance
+  namespace: default
+  resourceVersion: "23088242"
+  uid: 548ebe99-d40b-4580-a9bc-afe80915e22e
+spec:
+  serviceAccountName: default
+  taskSpec:
+    results:
+    - description: ""
+      name: foo
+    - description: ""
+      name: bar
+    steps:
+    - image: ubuntu
+      name: non-falsifiable
+      resources: {}
+      script: |
+        #!/usr/bin/env bash
+        sleep 30
+        printf "%s" "hello" > "$(results.foo.path)"
+        printf "%s" "world" > "$(results.bar.path)"
+  timeout: 1m0s
+status:
+  annotations:
+    tekton.dev/controller-svid: |
+      -----BEGIN CERTIFICATE-----
+      MIIB7jCCAZSgAwIBAgIRAI8/08uXSn9tyv7cRN87uvgwCgYIKoZIzj0EAwIwHjEL
+      MAkGA1UEBhMCVVMxDzANBgNVBAoTBlNQSUZGRTAeFw0yMjAzMDQxODU0NTlaFw0y
+      MjAzMDQxOTU1MDlaMB0xCzAJBgNVBAYTAlVTMQ4wDAYDVQQKEwVTUElSRTBZMBMG
+      ByqGSM49AgEGCCqGSM49AwEHA0IABL+e9OjkMv+7XgMWYtrzq0ESzJi+znA/Pm8D
+      nvApAHg3/rEcNS8c5LgFFRzDfcs9fxGSSkL1JrELzoYul1Q13XejgbMwgbAwDgYD
+      VR0PAQH/BAQDAgOoMB0GA1UdJQQWMBQGCCsGAQUFBwMBBggrBgEFBQcDAjAMBgNV
+      HRMBAf8EAjAAMB0GA1UdDgQWBBR+ma+yZfo092FKIM4F3yhEY8jgDDAfBgNVHSME
+      GDAWgBRKiCg5+YdTaQ+5gJmvt2QcDkQ6KjAxBgNVHREEKjAohiZzcGlmZmU6Ly9l
+      eGFtcGxlLm9yZy90ZWt0b24vY29udHJvbGxlcjAKBggqhkjOPQQDAgNIADBFAiEA
+      8xVWrQr8+i6yMLDm9IUjtvTbz9ofjSsWL6c/+rxmmRYCIBTiJ/HW7di3inSfxwqK
+      5DKyPrKoR8sq8Ne7flkhgbkg
+      -----END CERTIFICATE-----
+    tekton.dev/status-hash: 76692c9dcd362f8a6e4bda8ccb4c0937ad16b0d23149ae256049433192892511
+    tekton.dev/status-hash-sig: MEQCIFv2bW0k4g0Azx+qaeZjUulPD8Ma3uCUn0tXQuuR1FaEAiBHQwN4XobOXmC2nddYm04AZ74YubUyNl49/vnbnR/HcQ==
+  completionTime: "2022-03-04T19:11:22Z"
+  conditions:
+  - lastTransitionTime: "2022-03-04T19:11:22Z"
+    message: All Steps have completed executing
+    reason: Succeeded
+    status: "True"
+    type: Succeeded
+  - lastTransitionTime: "2022-03-04T19:11:22Z"
+    message: Spire verified
+    reason: TaskRunResultsVerified
+    status: "True"
+    type: SignedResultsVerified
+  podName: non-falsifiable-provenance-pod
+  startTime: "2022-03-04T19:10:46Z"
+  steps:
+  ...
+  <TRUNCATED>
+```
+
+## How is the status being verified
+
+The signature are being verified by the Tekton controller, the process of verification is as follows:
+
+- Verify status-hash fields
+  - verify `tekton.dev/status-hash` content against its associated `tekton.dev/status-hash-sig` field. If status hash does 
+    not match invalidate the `tekton.dev/verified = no` annotation will be added
+
+## Further Details
+
+To learn more about SPIRE attestations, check out the [TEP](https://github.com/tektoncd/community/blob/main/teps/0089-nonfalsifiable-provenance-support.md).

examples/v1beta1/pipelineruns/4808-regression.yaml

@@ -92,4 +92,4 @@ spec:
     name: result-test
   params:
   - name: RESULT_STRING_LENGTH
-    value: "3000"
+    value: "2000"

pkg/apis/config/feature_flags.go

@@ -316,6 +316,11 @@ func CheckAlphaOrBetaAPIFields(ctx context.Context) bool {
 	return cfg.FeatureFlags.EnableAPIFields == AlphaAPIFields || cfg.FeatureFlags.EnableAPIFields == BetaAPIFields
 }
 
+// IsSpireEnabled checks if non-falsifiable provenance is enforced through SPIRE
+func IsSpireEnabled(ctx context.Context) bool {
+	return FromContextOrDefaults(ctx).FeatureFlags.EnforceNonfalsifiability == EnforceNonfalsifiabilityWithSpire
+}
+
 func setEnableAPIFields(ctx context.Context, want string) context.Context {
 	featureFlags, _ := NewFeatureFlagsFromMap(map[string]string{
 		"enable-api-fields": want,

pkg/apis/config/feature_flags_test.go

@@ -305,6 +305,28 @@ func TestCheckAlphaOrBetaAPIFields(t *testing.T) {
 	}
 }
 
+func TestIsSpireEnabled(t *testing.T) {
+	ctx := context.Background()
+	if config.IsSpireEnabled(ctx) {
+		t.Errorf("IsSpireEnabled got true but expected to be false")
+	}
+	store := config.NewStore(logging.FromContext(ctx).Named("config-store"))
+	featureflags := &corev1.ConfigMap{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: "feature-flags",
+		},
+		Data: map[string]string{
+			"enable-api-fields":         "alpha",
+			"enforce-nonfalsifiability": config.EnforceNonfalsifiabilityWithSpire,
+		},
+	}
+	store.OnConfigChanged(featureflags)
+	ctx = store.ToContext(ctx)
+	if !config.IsSpireEnabled(ctx) {
+		t.Errorf("IsSpireEnabled got false but expected to be true")
+	}
+}
+
 func verifyConfigFileWithExpectedFeatureFlagsConfig(t *testing.T, fileName string, expectedConfig *config.FeatureFlags) {
 	t.Helper()
 	cm := test.ConfigMapFromTestFile(t, fileName)

pkg/pod/pod.go

@@ -31,6 +31,7 @@ import (
 	"github.com/tektoncd/pipeline/pkg/apis/pipeline/v1beta1"
 	"github.com/tektoncd/pipeline/pkg/internal/computeresources/tasklevel"
 	"github.com/tektoncd/pipeline/pkg/names"
+	"github.com/tektoncd/pipeline/pkg/spire"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime/schema"
@@ -132,6 +133,10 @@ func (b *Builder) Build(ctx context.Context, taskRun *v1beta1.TaskRun, taskSpec
 	// Secrets, along with any arguments needed by Step entrypoints to process
 	// those secrets.
 	commonExtraEntrypointArgs := []string{}
+	// Entrypoint arg to enable or disable spire
+	if config.IsSpireEnabled(ctx) {
+		commonExtraEntrypointArgs = append(commonExtraEntrypointArgs, "-enable_spire")
+	}
 	credEntrypointArgs, credVolumes, credVolumeMounts, err := credsInit(ctx, taskRun.Spec.ServiceAccountName, taskRun.Namespace, b.KubeClient)
 	if err != nil {
 		return nil, err
@@ -322,6 +327,39 @@ func (b *Builder) Build(ctx context.Context, taskRun *v1beta1.TaskRun, taskSpec
 		return nil, err
 	}
 
+	readonly := true
+	if config.IsSpireEnabled(ctx) {
+		// add SPIRE's CSI volume to the explicitly declared use volumes
+		volumes = append(volumes, corev1.Volume{
+			Name: spire.WorkloadAPI,
+			VolumeSource: corev1.VolumeSource{
+				CSI: &corev1.CSIVolumeSource{
+					Driver:   "csi.spiffe.io",
+					ReadOnly: &readonly,
+				},
+			},
+		})
+
+		// mount SPIRE's CSI volume to each Step Container
+		for i := range stepContainers {
+			c := &stepContainers[i]
+			c.VolumeMounts = append(c.VolumeMounts, corev1.VolumeMount{
+				Name:      spire.WorkloadAPI,
+				MountPath: spire.VolumeMountPath,
+				ReadOnly:  true,
+			})
+		}
+		for i := range initContainers {
+			// mount SPIRE's CSI volume to each Init Container
+			c := &initContainers[i]
+			c.VolumeMounts = append(c.VolumeMounts, corev1.VolumeMount{
+				Name:      spire.WorkloadAPI,
+				MountPath: spire.VolumeMountPath,
+				ReadOnly:  true,
+			})
+		}
+	}
+
 	mergedPodContainers := stepContainers
 
 	// Merge sidecar containers with step containers.