Return VSA and rich errors from verification (#38)

* Start of richer results from verification * Pull out VSA code from signing * Expose attestation signing fns * Add VSA test * Notes for policy result * Require separate policy for VSA creation * Load test signing key from tests * Return rich object from policy * Add result object schema and fix tests * Ensure example test runs * Remove data.yaml files from mock policies * Don't run example - TUF policy isn't compatible * Add attestation to manifests for all subjects * Ensure adding attestation doesn't touch statements * Don't export sign function * Remove attestations from VerificationResult * Change bool to Outcome enum in result * Use outputLayout directly * Make clearer that Outcome strings are for VSA * Return multiple SLSA levels from policy * Fix unmarshalling of policy-id (#39) * Rename function * Rename policy.VerificationResult -> policy.Result * Re-add test for canonical input --------- Co-authored-by: James Carnegie <james.carnegie@docker.com> Co-authored-by: James Carnegie <kipz@users.noreply.github.com>
2024-05-22 14:49:23 +01:00
parent 745eea09e8
commit 1a7897a052
33 changed files with 776 additions and 461 deletions
--- a/pkg/policy/evaluator.go
+++ b/pkg/policy/evaluator.go
@@ -5,7 +5,6 @@ import (
 	"fmt"

 	"github.com/docker/attest/pkg/oci"
-	"github.com/open-policy-agent/opa/rego"
 )

 type policyEvaluatorCtxKeyType struct{}
@@ -27,5 +26,5 @@ func GetPolicyEvaluator(ctx context.Context) (PolicyEvaluator, error) {
 }

 type PolicyEvaluator interface {
-	Evaluate(ctx context.Context, resolver oci.AttestationResolver, policy []*PolicyFile, input *PolicyInput) (*rego.ResultSet, error)
+	Evaluate(ctx context.Context, resolver oci.AttestationResolver, pctx *Policy, input *PolicyInput) (*Result, error)
 }
--- a/pkg/policy/mock.go
+++ b/pkg/policy/mock.go
@@ -4,37 +4,29 @@ import (
 	"context"

 	"github.com/docker/attest/pkg/oci"
-	"github.com/open-policy-agent/opa/rego"
 )

 type MockPolicyEvaluator struct {
-	EvaluateFunc func(ctx context.Context, resolver oci.AttestationResolver, policy []*PolicyFile, input *PolicyInput) (*rego.ResultSet, error)
+	EvaluateFunc func(ctx context.Context, resolver oci.AttestationResolver, pctx *Policy, input *PolicyInput) (*Result, error)
 }

-func (pe *MockPolicyEvaluator) Evaluate(ctx context.Context, resolver oci.AttestationResolver, policy []*PolicyFile, input *PolicyInput) (*rego.ResultSet, error) {
+func (pe *MockPolicyEvaluator) Evaluate(ctx context.Context, resolver oci.AttestationResolver, pctx *Policy, input *PolicyInput) (*Result, error) {
 	if pe.EvaluateFunc != nil {
-		return pe.EvaluateFunc(ctx, resolver, policy, input)
+		return pe.EvaluateFunc(ctx, resolver, pctx, input)
 	}
 	return AllowedResult(), nil
 }

 func GetMockPolicy() PolicyEvaluator {
 	return &MockPolicyEvaluator{
-		EvaluateFunc: func(ctx context.Context, resolver oci.AttestationResolver, pfs []*PolicyFile, input *PolicyInput) (*rego.ResultSet, error) {
+		EvaluateFunc: func(ctx context.Context, resolver oci.AttestationResolver, pctx *Policy, input *PolicyInput) (*Result, error) {
 			return AllowedResult(), nil
 		},
 	}
 }

-func AllowedResult() *rego.ResultSet {
-	return &rego.ResultSet{
-		{
-			Bindings: rego.Vars{},
-			Expressions: []*rego.ExpressionValue{
-				{
-					Value: true,
-				},
-			},
-		},
+func AllowedResult() *Result {
+	return &Result{
+		Success: true,
 	}
 }
--- a/pkg/policy/policy.go
+++ b/pkg/policy/policy.go
@@ -12,6 +12,7 @@ import (
 	"github.com/distribution/reference"
 	"github.com/docker/attest/pkg/oci"
 	"github.com/docker/attest/pkg/tuf"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"

 	goyaml "gopkg.in/yaml.v3"
 )
@@ -20,6 +21,26 @@ const (
 	PolicyMappingFileName = "mapping.yaml"
 )

+type Summary struct {
+	Subjects   []intoto.Subject `json:"subjects"`
+	SLSALevels []string         `json:"slsa_levels"`
+	Verifier   string           `json:"verifier"`
+	PolicyURI  string           `json:"policy_uri"`
+}
+
+type Violation struct {
+	Type        string            `json:"type"`
+	Description string            `json:"description"`
+	Attestation *intoto.Statement `json:"attestation"`
+	Details     map[string]any    `json:"details"`
+}
+
+type Result struct {
+	Success    bool        `json:"success"`
+	Violations []Violation `json:"violations"`
+	Summary    Summary     `json:"summary"`
+}
+
 type PolicyMappings struct {
 	Version  string          `json:"version"`
 	Kind     string          `json:"kind"`
@@ -39,7 +60,7 @@ type PolicyMappingFile struct {
 }

 type PolicyMirror struct {
-	PolicyId string     `json:"policy-id"`
+	PolicyId string     `yaml:"policy-id"`
 	Mirror   MirrorSpec `json:"mirror"`
 }

@@ -60,6 +81,11 @@ type PolicyOptions struct {
 	LocalPolicyDir  string
 }

+type Policy struct {
+	InputFiles []*PolicyFile
+	Query      string
+}
+
 type PolicyInput struct {
 	Digest      string `json:"digest"`
 	Purl        string `json:"purl"`
@@ -71,7 +97,7 @@ type PolicyFile struct {
 	Content []byte
 }

-func resolveLocalPolicy(opts *PolicyOptions, mapping *PolicyMapping) ([]*PolicyFile, error) {
+func resolveLocalPolicy(opts *PolicyOptions, mapping *PolicyMapping) (*Policy, error) {
 	if opts.LocalPolicyDir == "" {
 		return nil, fmt.Errorf("local policy dir not set")
 	}
@@ -88,10 +114,13 @@ func resolveLocalPolicy(opts *PolicyOptions, mapping *PolicyMapping) ([]*PolicyF
 			Content: fileContents,
 		})
 	}
-	return files, nil
+	policy := &Policy{
+		InputFiles: files,
+	}
+	return policy, nil
 }

-func loadLocalMappings(opts *PolicyOptions) (*PolicyMappings, error) {
+func LoadLocalMappings(opts *PolicyOptions) (*PolicyMappings, error) {
 	if opts.LocalPolicyDir == "" {
 		return nil, nil
 	}
@@ -108,7 +137,7 @@ func loadLocalMappings(opts *PolicyOptions) (*PolicyMappings, error) {
 	return mappings, nil
 }

-func resolveTufPolicy(opts *PolicyOptions, mapping *PolicyMapping) ([]*PolicyFile, error) {
+func resolveTufPolicy(opts *PolicyOptions, mapping *PolicyMapping) (*Policy, error) {
 	files := make([]*PolicyFile, 0, len(mapping.Files))
 	for _, f := range mapping.Files {
 		filename := f.Path
@@ -121,7 +150,10 @@ func resolveTufPolicy(opts *PolicyOptions, mapping *PolicyMapping) ([]*PolicyFil
 			Content: fileContents,
 		})
 	}
-	return files, nil
+	policy := &Policy{
+		InputFiles: files,
+	}
+	return policy, nil
 }

 func loadTufMappings(tufClient tuf.TUFClient, localTargetsDir string) (*PolicyMappings, error) {
@@ -163,7 +195,7 @@ func findPolicyMatch(named reference.Named, mappings *PolicyMappings) (*PolicyMa
 	return nil, nil
 }

-func ResolvePolicy(ctx context.Context, resolver oci.AttestationResolver, opts *PolicyOptions) ([]*PolicyFile, error) {
+func ResolvePolicy(ctx context.Context, resolver oci.AttestationResolver, opts *PolicyOptions) (*Policy, error) {
 	imageName, err := resolver.ImageName(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get image name: %w", err)
@@ -172,7 +204,7 @@ func ResolvePolicy(ctx context.Context, resolver oci.AttestationResolver, opts *
 	if err != nil {
 		return nil, fmt.Errorf("failed to parse image name: %w", err)
 	}
-	localMappings, err := loadLocalMappings(opts)
+	localMappings, err := LoadLocalMappings(opts)
 	if err != nil {
 		return nil, fmt.Errorf("failed to load local policy mappings: %w", err)
 	}
--- a/pkg/policy/policy_test.go
+++ b/pkg/policy/policy_test.go
@@ -12,6 +12,7 @@ import (
 	"github.com/docker/attest/pkg/policy"
 	"github.com/docker/attest/pkg/tuf"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )

 func loadAttestation(t *testing.T, path string) *attestation.Envelope {
@@ -32,61 +33,37 @@ func TestRegoEvaluator_Evaluate(t *testing.T) {
 	ctx, _ := test.Setup(t)

 	TestDataPath := filepath.Join("..", "..", "test", "testdata")
-	MockTufRepo := filepath.Join(TestDataPath, "local-policy")
 	ExampleAttestation := filepath.Join(TestDataPath, "example_attestation.json")
-	VSA := filepath.Join(TestDataPath, "vsa.json")

 	re := policy.NewRegoEvaluator(true)

-	defaultInput := &policy.PolicyInput{
-		Digest:      "sha256:test-digest",
-		Purl:        "test-purl",
-		IsCanonical: true,
-	}
-
 	defaultResolver := oci.MockResolver{
 		Envs: []*attestation.Envelope{loadAttestation(t, ExampleAttestation)},
 	}

-	vsaResolver := oci.MockResolver{
-		Envs: []*attestation.Envelope{loadAttestation(t, ExampleAttestation), loadAttestation(t, VSA)},
-	}
-
 	testCases := []struct {
 		repo          string
 		expectSuccess bool
-		input         *policy.PolicyInput
+		isCanonical   bool
 		resolver      oci.AttestationResolver
 		policy        *policy.PolicyOptions
 	}{
-		{repo: "testdata/mock-tuf-allow", expectSuccess: true, input: defaultInput, resolver: defaultResolver},
-		{repo: "testdata/mock-tuf-deny", expectSuccess: false, input: defaultInput, resolver: defaultResolver},
-		{repo: "testdata/mock-tuf-verify-sig", expectSuccess: true, input: defaultInput, resolver: defaultResolver},
-		{repo: "testdata/mock-tuf-wrong-key", expectSuccess: false, input: defaultInput, resolver: defaultResolver},
-		{repo: MockTufRepo, expectSuccess: true, input: &policy.PolicyInput{
-			Digest:      "sha256:da8b190665956ea07890a0273e2a9c96bfe291662f08e2860e868eef69c34620",
-			Purl:        "pkg:docker/test-image?digest=sha256%da8b190665956ea07890a0273e2a9c96bfe291662f08e2860e868eef69c34620&platform=linux%2Famd64",
-			IsCanonical: true,
-		}, resolver: vsaResolver},
-		{repo: MockTufRepo, expectSuccess: true, input: &policy.PolicyInput{
-			Digest:      "sha256:da8b190665956ea07890a0273e2a9c96bfe291662f08e2860e868eef69c34620",
-			Purl:        "pkg:docker/test-image@test?platform=linux%2Famd64",
-			IsCanonical: false,
-		}, resolver: vsaResolver},
-		// not a doi
-		{repo: MockTufRepo, expectSuccess: false, input: defaultInput, resolver: vsaResolver, policy: &policy.PolicyOptions{
-			LocalPolicyDir: "testdata/mock-tuf-deny",
-		}},
-		// digest mismatch
-		{repo: MockTufRepo, expectSuccess: false, input: &policy.PolicyInput{
-			Digest:      "sha256:test-digest-wrong",
-			Purl:        "test-purl",
-			IsCanonical: false,
-		}, resolver: vsaResolver},
+		{repo: "testdata/mock-tuf-allow", expectSuccess: true, isCanonical: false, resolver: defaultResolver},
+		{repo: "testdata/mock-tuf-deny", expectSuccess: false, isCanonical: false, resolver: defaultResolver},
+		{repo: "testdata/mock-tuf-verify-sig", expectSuccess: true, isCanonical: false, resolver: defaultResolver},
+		{repo: "testdata/mock-tuf-wrong-key", expectSuccess: false, isCanonical: false, resolver: defaultResolver},
+		{repo: "testdata/mock-tuf-allow-canonical", expectSuccess: true, isCanonical: true, resolver: defaultResolver},
+		{repo: "testdata/mock-tuf-allow-canonical", expectSuccess: false, isCanonical: false, resolver: defaultResolver},
 	}

 	for _, tc := range testCases {
 		t.Run(tc.repo, func(t *testing.T) {
+			input := &policy.PolicyInput{
+				Digest:      "sha256:test-digest",
+				Purl:        "test-purl",
+				IsCanonical: tc.isCanonical,
+			}
+
 			tufClient := tuf.NewMockTufClient(tc.repo, test.CreateTempDir(t, "", "tuf-dest"))
 			if tc.policy == nil {
 				tc.policy = &policy.PolicyOptions{
@@ -95,17 +72,29 @@ func TestRegoEvaluator_Evaluate(t *testing.T) {
 				}
 			}

-			policyFiles, err := policy.ResolvePolicy(ctx, tc.resolver, tc.policy)
+			policy, err := policy.ResolvePolicy(ctx, tc.resolver, tc.policy)
 			assert.NoErrorf(t, err, "failed to resolve policy")
-			rs, err := re.Evaluate(ctx, tc.resolver, policyFiles, tc.input)
+			result, err := re.Evaluate(ctx, tc.resolver, policy, input)
+			require.NoErrorf(t, err, "Evaluate failed")

 			if tc.expectSuccess {
-				assert.NoErrorf(t, err, "Evaluate failed")
-				assert.True(t, rs.Allowed(), "Evaluate should have succeeded")
+				assert.True(t, result.Success, "Evaluate should have succeeded")
 			} else {
-				assert.False(t, rs.Allowed(), "Evaluate should have failed")
+				assert.False(t, result.Success, "Evaluate should have failed")
 			}
 		})
 	}

 }
+
+func TestLoadingMappings(t *testing.T) {
+	opts := &policy.PolicyOptions{
+		LocalPolicyDir: filepath.Join("testdata", "mock-tuf-allow"),
+	}
+	policyMappings, err := policy.LoadLocalMappings(opts)
+	require.NoError(t, err)
+	assert.Equal(t, len(policyMappings.Mirrors), 1)
+	for _, mirror := range policyMappings.Mirrors {
+		assert.Equal(t, "docker-official-images", mirror.PolicyId)
+	}
+}
--- a/pkg/policy/rego.go
+++ b/pkg/policy/rego.go
@@ -23,17 +23,20 @@ import (

 type regoEvaluator struct {
 	debug bool
-	query string
 }

+const (
+	DefaultQuery  = "result := data.attest.result"
+	resultBinding = "result"
+)
+
 func NewRegoEvaluator(debug bool) PolicyEvaluator {
 	return &regoEvaluator{
 		debug: debug,
-		query: "data.attest.allow",
 	}
 }

-func (re *regoEvaluator) Evaluate(ctx context.Context, resolver oci.AttestationResolver, files []*PolicyFile, input *PolicyInput) (*rego.ResultSet, error) {
+func (re *regoEvaluator) Evaluate(ctx context.Context, resolver oci.AttestationResolver, pctx *Policy, input *PolicyInput) (*Result, error) {
 	var regoOpts []func(*rego.Rego)

 	// Create a new in-memory store
@@ -45,7 +48,7 @@ func (re *regoEvaluator) Evaluate(ctx context.Context, resolver oci.AttestationR
 		return nil, err
 	}

-	for _, target := range files {
+	for _, target := range pctx.InputFiles {
 		// load yaml as data (no rego opt for this!?)
 		if filepath.Ext(target.Path) == ".yaml" {
 			yamlData, err := loadYAML(target.Path, target.Content)
@@ -74,12 +77,15 @@ func (re *regoEvaluator) Evaluate(ctx context.Context, resolver oci.AttestationR
 			rego.Dump(os.Stderr),
 		)
 	}
-
+	query := DefaultQuery
+	if pctx.Query != "" {
+		query = pctx.Query
+	}
 	regoOpts = append(regoOpts,
-		rego.Query(re.query),
-		rego.StrictBuiltinErrors(true),
+		rego.Query(query),
 		rego.Input(input),
 		rego.Store(store),
+		rego.GenerateJSON(jsonGenerator[Result]()),
 	)
 	for _, custom := range RegoFunctions(resolver) {
 		regoOpts = append(regoOpts, custom.Func)
@@ -87,11 +93,50 @@ func (re *regoEvaluator) Evaluate(ctx context.Context, resolver oci.AttestationR

 	r := rego.New(regoOpts...)
 	rs, err := r.Eval(ctx)
-	return &rs, err
+	if err != nil {
+		return nil, err
+	}
+
+	if len(rs) == 0 {
+		return nil, fmt.Errorf("no policy evaluation result")
+	}
+	binding, ok := rs[0].Bindings[resultBinding]
+	if !ok {
+		return nil, fmt.Errorf("failed to extract verification result")
+	}
+	result, ok := binding.(Result)
+	if !ok {
+		return nil, fmt.Errorf("failed to extract verification result")
+	}
+
+	return &result, nil
+}
+
+func jsonGenerator[T any]() func(t *ast.Term, ec *rego.EvalContext) (any, error) {
+	return func(t *ast.Term, ec *rego.EvalContext) (any, error) {
+		// TODO: this is horrible - we're converting the AST to JSON and then back to AST, then using ast.As to convert it to a struct
+		// We can't use ast.As directly because it fails if the AST contains a set
+		json, err := ast.JSON(t.Value)
+		if err != nil {
+			return nil, err
+		}
+		v, err := ast.InterfaceToValue(json)
+		if err != nil {
+			return nil, err
+		}
+		var result T
+		err = ast.As(v, &result)
+		if err != nil {
+			return nil, err
+		}
+		return result, nil
+	}
 }

 var dynamicObj = types.NewObject(nil, types.NewDynamicProperty(types.S, types.A))
 var arrayObj = types.NewArray(nil, dynamicObj)
+var setObj = types.NewSet(dynamicObj)
+
 var verifyDecl = &ast.Builtin{
 	Name:             "attestations.verify_envelope",
 	Decl:             types.NewFunction(types.Args(dynamicObj, arrayObj), dynamicObj),
@@ -99,7 +144,7 @@ var verifyDecl = &ast.Builtin{
 }
 var attestDecl = &ast.Builtin{
 	Name:             "attestations.attestation",
-	Decl:             types.NewFunction(types.Args(types.S), dynamicObj),
+	Decl:             types.NewFunction(types.Args(types.S), setObj),
 	Nondeterministic: true,
 }

@@ -153,12 +198,13 @@ func fetchIntotoAttestations(resolver oci.AttestationResolver) func(rego.Builtin
 			values[i] = ast.NewTerm(value)
 		}

-		// Wrap the values in an ast.Array and convert it to an ast.Term.
-		array := ast.NewTerm(ast.NewArray(values...))
+		// Wrap the values in an ast.Set and convert it to an ast.Term.
+		set := ast.NewTerm(ast.NewSet(values...))

-		return array, nil
+		return set, nil
 	}
 }
+
 func verifyIntotoEnvelope(rCtx rego.BuiltinContext, envTerm, keysTerm *ast.Term) (*ast.Term, error) {
 	env := new(att.Envelope)
 	var keys att.Keys
--- a/pkg/policy/testdata/mock-tuf-allow-canonical/doi/policy.rego
+++ b/pkg/policy/testdata/mock-tuf-allow-canonical/doi/policy.rego
@@ -0,0 +1,7 @@
+package attest
+
+import rego.v1
+
+result := {
+  "success": input.isCanonical,
+}
--- a/pkg/policy/testdata/mock-tuf-allow-canonical/mapping.yaml
+++ b/pkg/policy/testdata/mock-tuf-allow-canonical/mapping.yaml
@@ -0,0 +1,16 @@
+# map repos to policies
+version: v1
+kind: policy-mapping
+policies:
+  - origin:
+      domain: docker.io
+      prefix: library/
+    id: docker-official-images
+    description: Docker Official Images
+    files:
+      - path: doi/policy.rego
+mirrors:
+  - policy-id: docker-official-images
+    mirror:
+      domains: [localhost:5001, registry.local:5000]
+      prefix: ""
--- a/pkg/policy/testdata/mock-tuf-allow/doi/policy.rego
+++ b/pkg/policy/testdata/mock-tuf-allow/doi/policy.rego
@@ -2,4 +2,6 @@ package attest

 import rego.v1

-allow := true
+result := {
+  "success": true,
+}
--- a/pkg/policy/testdata/mock-tuf-allow/mapping.yaml
+++ b/pkg/policy/testdata/mock-tuf-allow/mapping.yaml
@@ -9,3 +9,8 @@ policies:
    description: Docker Official Images
    files:
      - path: doi/policy.rego
+mirrors:
+  - policy-id: docker-official-images
+    mirror:
+      domains: [localhost:5001, registry.local:5000]
+      prefix: ""
--- a/pkg/policy/testdata/mock-tuf-deny/doi/policy.rego
+++ b/pkg/policy/testdata/mock-tuf-deny/doi/policy.rego
@@ -2,4 +2,6 @@ package attest

 import rego.v1

-allow := false
+result := {
+  "success": false,
+}
--- a/pkg/policy/testdata/mock-tuf-verify-sig/doi/policy.rego
+++ b/pkg/policy/testdata/mock-tuf-verify-sig/doi/policy.rego
@@ -3,13 +3,17 @@ package attest
 import rego.v1

 keys := [{
-    "id": "a0c296026645799b2a297913878e81b0aefff2a0c301e97232f717e14402f3e4",
-    "key": "-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEgH23D1i2+ZIOtVjmfB7iFvX8AhVN\n9CPJ4ie9axw+WRHozGnRy99U2dRge3zueBBg2MweF0zrToXGig2v3YOrdw==\n-----END PUBLIC KEY-----",
-    "from": "2023-12-15T14:00:00Z",
-    "to": null
+  "id": "a0c296026645799b2a297913878e81b0aefff2a0c301e97232f717e14402f3e4",
+  "key": "-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEgH23D1i2+ZIOtVjmfB7iFvX8AhVN\n9CPJ4ie9axw+WRHozGnRy99U2dRge3zueBBg2MweF0zrToXGig2v3YOrdw==\n-----END PUBLIC KEY-----",
+  "from": "2023-12-15T14:00:00Z",
+  "to": null
 }]

-allow if {
+success if {
  some env in attestations.attestation("foo")
  statement := attestations.verify_envelope(env, keys)
 }
+
+result := {
+  "success": success
+}
--- a/pkg/policy/testdata/mock-tuf-wrong-key/doi/policy.rego
+++ b/pkg/policy/testdata/mock-tuf-wrong-key/doi/policy.rego
@@ -2,18 +2,20 @@ package attest

 import rego.v1

-keys := {
-  "a0c296026645799b2a297913878e81b0aefff2a0c301e97232f717e14402f3e4": {
-    "id": "a0c296026645799b2a297913878e81b0aefff2a0c301e97232f717e14402f3e4",
-    "key": "-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEHyZpSgzvqFqNv7f3x7865OS38rAb\nQMcff55zM2UH/KR3Pr84a8QsGDNgaNGzJQJWjtMSgfV8WnNoffNK+svFNg==\n-----END PUBLIC KEY-----",
-    "from": "2023-12-15T14:00:00Z",
-    "to": null,
-  }
-}
+keys := [{
+  "id": "a0c296026645799b2a297913878e81b0aefff2a0c301e97232f717e14402f3e4",
+  "key": "-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEHyZpSgzvqFqNv7f3x7865OS38rAb\nQMcff55zM2UH/KR3Pr84a8QsGDNgaNGzJQJWjtMSgfV8WnNoffNK+svFNg==\n-----END PUBLIC KEY-----",
+  "from": "2023-12-15T14:00:00Z",
+  "to": null,
+}]

-allow if {
+default success := false
+
+success if {
  some env in attestations.attestation("foo")
  statement := attestations.verify_envelope(env, keys)
 }

-allow := true
+result := {
+  "success": success
+}