Various fixes (#63)

* Fix digest resolution and attestation style

* Add a bunch more tests

* Rename fields for consistency

* Remove copy-pasta

* Value -> pointer

pkg/attest/verify.go

@@ -18,7 +18,12 @@ func Verify(ctx context.Context, src *oci.ImageSpec, opts *policy.PolicyOptions)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create image details resolver: %w", err)
 	}
-
+	if opts.AttestationStyle == "" {
+		opts.AttestationStyle = config.AttestationStyleReferrers
+	}
+	if opts.ReferrersRepo != "" && opts.AttestationStyle != config.AttestationStyleReferrers {
+		return nil, fmt.Errorf("referrers repo specified but attestation source not set to referrers")
+	}
 	pctx, err := policy.ResolvePolicy(ctx, detailsResolver, opts)
 	if err != nil {
 		return nil, fmt.Errorf("failed to resolve policy: %w", err)
@@ -33,7 +38,12 @@ func Verify(ctx context.Context, src *oci.ImageSpec, opts *policy.PolicyOptions)
 	if opts.ReferrersRepo != "" {
 		pctx.Mapping.Attestations = &config.ReferrersConfig{
 			Repo:  opts.ReferrersRepo,
-			Style: config.AttestationSourceReferrers,
+			Style: config.AttestationStyleReferrers,
+		}
+	} else if opts.AttestationStyle == config.AttestationStyleAttached {
+		pctx.Mapping.Attestations = &config.ReferrersConfig{
+			Repo:  opts.ReferrersRepo,
+			Style: config.AttestationStyleAttached,
 		}
 	}
 	// because we have a mapping now, we can select a resolver based on its contents (ie. referrers or attached)

pkg/attestation/referrers_test.go

@@ -10,6 +10,7 @@ import (
 	"github.com/docker/attest/internal/test"
 	"github.com/docker/attest/pkg/attest"
 	"github.com/docker/attest/pkg/attestation"
+	"github.com/docker/attest/pkg/config"
 	"github.com/docker/attest/pkg/mirror"
 	"github.com/docker/attest/pkg/oci"
 	"github.com/docker/attest/pkg/policy"
@@ -21,21 +22,29 @@ import (
 )
 
 var (
-	UnsignedTestImage = filepath.Join("..", "..", "test", "testdata", "unsigned-test-image")
-	NoProvenanceImage = filepath.Join("..", "..", "test", "testdata", "no-provenance-image")
-	PassPolicyDir     = filepath.Join("..", "..", "test", "testdata", "local-policy-pass")
-	PassNoTLPolicyDir = filepath.Join("..", "..", "test", "testdata", "local-policy-no-tl")
-	FailPolicyDir     = filepath.Join("..", "..", "test", "testdata", "local-policy-fail")
-	TestTempDir       = "attest-sign-test"
+	UnsignedTestImage   = filepath.Join("..", "..", "test", "testdata", "unsigned-test-image")
+	NoProvenanceImage   = filepath.Join("..", "..", "test", "testdata", "no-provenance-image")
+	PassPolicyDir       = filepath.Join("..", "..", "test", "testdata", "local-policy-pass")
+	LocalPolicy         = filepath.Join("..", "..", "test", "testdata", "local-policy")
+	LocalPolicyAttached = filepath.Join("..", "..", "test", "testdata", "local-policy-attached")
+	PassNoTLPolicyDir   = filepath.Join("..", "..", "test", "testdata", "local-policy-no-tl")
+	FailPolicyDir       = filepath.Join("..", "..", "test", "testdata", "local-policy-fail")
+	TestTempDir         = "attest-sign-test"
 )
 
 func TestAttestationReferenceTypes(t *testing.T) {
 	ctx, signer := test.Setup(t)
+	ctx = policy.WithPolicyEvaluator(ctx, policy.NewRegoEvaluator(true))
 	platforms := []string{"linux/amd64", "linux/arm64"}
 	for _, tc := range []struct {
-		server      *httptest.Server
-		skipSubject bool
-		useDigest   bool
+		server            *httptest.Server
+		referrersServer   *httptest.Server
+		skipSubject       bool
+		useDigest         bool
+		referrersRepo     string
+		attestationSource config.AttestationStyle
+		expectFailure     bool
+		policyDir         string
 	}{
 		{
 			server: httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
@@ -44,76 +53,135 @@ func TestAttestationReferenceTypes(t *testing.T) {
 			server: httptest.NewServer(registry.New()),
 		},
 		{
-			server:      httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
-			skipSubject: true,
+			server:            httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
+			skipSubject:       true,
+			attestationSource: config.AttestationStyleAttached,
 		},
 		{
 			server:    httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
 			useDigest: true,
 		},
+		{
+			server:            httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
+			expectFailure:     true, //mismatched args
+			attestationSource: config.AttestationStyleAttached,
+			referrersRepo:     "referrers",
+		},
+		{
+			server:            httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
+			expectFailure:     true, // no policy
+			attestationSource: config.AttestationStyleReferrers,
+			referrersRepo:     "referrers",
+		},
+		{
+			server:            httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
+			attestationSource: config.AttestationStyleReferrers,
+		},
+		{
+			server:            httptest.NewServer(registry.New(registry.WithReferrersSupport(false))),
+			attestationSource: config.AttestationStyleReferrers,
+			referrersServer:   httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
+		},
 	} {
-		s := tc.server
-		defer s.Close()
-		u, err := url.Parse(s.URL)
-		require.NoError(t, err)
+		t.Run(fmt.Sprint(tc), func(t *testing.T) {
+			s := tc.server
+			defer s.Close()
 
-		opts := &attestation.SigningOptions{
-			Replace:     true,
-			SkipSubject: tc.skipSubject,
-		}
-		attIdx, err := oci.SubjectIndexFromPath(UnsignedTestImage)
-		require.NoError(t, err)
-		signedIndex, err := attest.Sign(ctx, attIdx.Index, signer, opts)
-		require.NoError(t, err)
-
-		indexName := fmt.Sprintf("%s/repo:root", u.Host)
-		require.NoError(t, err)
-		err = mirror.PushIndexToRegistry(signedIndex, indexName)
-
-		for _, platform := range platforms {
-			// can eval policy in the normal way
-			ref := indexName
-			if tc.useDigest {
-				options := oci.WithOptions(ctx, nil)
-				subjectRef, err := name.ParseReference(indexName)
-				require.NoError(t, err)
-				desc, err := remote.Index(subjectRef, options...)
-				require.NoError(t, err)
-				idxDigest, err := desc.Digest()
-				require.NoError(t, err)
-				ref = fmt.Sprintf("%s/repo@%s", u.Host, idxDigest.String())
+			if tc.referrersServer != nil {
+				defer tc.referrersServer.Close()
 			}
+			u, err := url.Parse(s.URL)
+			require.NoError(t, err)
 
-			policyOpts := &policy.PolicyOptions{
-				LocalPolicyDir: PassPolicyDir,
+			opts := &attestation.SigningOptions{
+				Replace:     true,
+				SkipSubject: tc.skipSubject,
 			}
-			src, err := oci.ParseImageSpec(ref, oci.WithPlatform(platform))
+			attIdx, err := oci.SubjectIndexFromPath(UnsignedTestImage)
 			require.NoError(t, err)
-			results, err := attest.Verify(ctx, src, policyOpts)
-			require.NoError(t, err)
-			assert.Equal(t, attest.OutcomeSuccess, results.Outcome)
 
-			if !tc.skipSubject {
-				// can evaluate policy using referrers
-				if tc.useDigest {
-					p, err := oci.ParsePlatform(platform)
+			indexName := fmt.Sprintf("%s/repo:root", u.Host)
+			require.NoError(t, err)
+
+			if tc.referrersServer != nil {
+				ru, err := url.Parse(s.URL)
+				require.NoError(t, err)
+				repo := fmt.Sprintf("%s/referrers", ru.Host)
+				tc.referrersRepo = repo
+				images, err := attest.SignedAttestationImages(ctx, attIdx.Index, signer, opts)
+				require.NoError(t, err)
+				err = mirror.PushIndexToRegistry(attIdx.Index, indexName)
+				for _, img := range images {
+					err = mirror.PushImageToRegistry(img.Image, fmt.Sprintf("%s:tag-does-not-matter", repo))
 					require.NoError(t, err)
-					options := oci.WithOptions(ctx, p)
+				}
+			} else {
+				signedIndex, err := attest.Sign(ctx, attIdx.Index, signer, opts)
+				require.NoError(t, err)
+				err = mirror.PushIndexToRegistry(signedIndex, indexName)
+				require.NoError(t, err)
+			}
+
+			for _, platform := range platforms {
+				// can eval policy in the normal way
+				ref := indexName
+				if tc.useDigest {
+					options := oci.WithOptions(ctx, nil)
 					subjectRef, err := name.ParseReference(indexName)
 					require.NoError(t, err)
-					desc, err := remote.Image(subjectRef, options...)
+					desc, err := remote.Index(subjectRef, options...)
 					require.NoError(t, err)
-					subjectDigest, err := desc.Digest()
+					idxDigest, err := desc.Digest()
 					require.NoError(t, err)
-					ref = fmt.Sprintf("%s/repo@%s", u.Host, subjectDigest.String())
+					ref = fmt.Sprintf("%s/repo@%s", u.Host, idxDigest.String())
+				}
+
+				policyOpts := &policy.PolicyOptions{
+					LocalPolicyDir: LocalPolicy,
+				}
+				if tc.policyDir != "" {
+					policyOpts.LocalPolicyDir = tc.policyDir
+				}
+
+				if tc.referrersRepo != "" {
+					policyOpts.ReferrersRepo = tc.referrersRepo
+				}
+
+				if tc.attestationSource != "" {
+					policyOpts.AttestationStyle = tc.attestationSource
 				}
 				src, err := oci.ParseImageSpec(ref, oci.WithPlatform(platform))
 				require.NoError(t, err)
-				results, err = attest.Verify(ctx, src, policyOpts)
+				results, err := attest.Verify(ctx, src, policyOpts)
+				if tc.expectFailure {
+					require.Error(t, err)
+					continue
+				}
 				require.NoError(t, err)
 				assert.Equal(t, attest.OutcomeSuccess, results.Outcome)
+
+				if !tc.skipSubject {
+					// can evaluate policy using referrers
+					if tc.useDigest {
+						p, err := oci.ParsePlatform(platform)
+						require.NoError(t, err)
+						options := oci.WithOptions(ctx, p)
+						subjectRef, err := name.ParseReference(indexName)
+						require.NoError(t, err)
+						desc, err := remote.Image(subjectRef, options...)
+						require.NoError(t, err)
+						subjectDigest, err := desc.Digest()
+						require.NoError(t, err)
+						ref = fmt.Sprintf("%s/repo@%s", u.Host, subjectDigest.String())
+					}
+					src, err := oci.ParseImageSpec(ref, oci.WithPlatform(platform))
+					require.NoError(t, err)
+					results, err = attest.Verify(ctx, src, policyOpts)
+					require.NoError(t, err)
+					assert.Equal(t, attest.OutcomeSuccess, results.Outcome)
+				}
 			}
-		}
+		})
 	}
 }
 

pkg/config/types.go

@@ -1,17 +1,17 @@
 package config
 
 type PolicyMappings struct {
-	Version  string          `json:"version"`
-	Kind     string          `json:"kind"`
-	Policies []PolicyMapping `json:"policies"`
-	Mirrors  []PolicyMirror  `json:"mirrors"`
+	Version  string           `json:"version"`
+	Kind     string           `json:"kind"`
+	Policies []*PolicyMapping `json:"policies"`
+	Mirrors  []*PolicyMirror  `json:"mirrors"`
 }
 
-type AttestationSource string
+type AttestationStyle string
 
 const (
-	AttestationSourceAttached  AttestationSource = "attached"
-	AttestationSourceReferrers AttestationSource = "referrers"
+	AttestationStyleAttached  AttestationStyle = "attached"
+	AttestationStyleReferrers AttestationStyle = "referrers"
 )
 
 type PolicyMapping struct {
@@ -23,8 +23,8 @@ type PolicyMapping struct {
 }
 
 type ReferrersConfig struct {
-	Style AttestationSource `json:"style"`
-	Repo  string            `json:"repo"`
+	Style AttestationStyle `json:"style"`
+	Repo  string           `json:"repo"`
 }
 
 type PolicyMappingFile struct {

pkg/oci/registry.go

@@ -47,24 +47,16 @@ func (r *RegistryImageDetailsResolver) ImageDigest(ctx context.Context) (string,
 		if err != nil {
 			return "", fmt.Errorf("failed to parse reference: %w", err)
 		}
-		switch t := subjectRef.(type) {
-		case name.Digest:
-			// TODO should check if this is an index or an image
-			r.digest = t.DigestStr()
-		case name.Tag:
-			options := WithOptions(ctx, r.Platform)
-			desc, err := remote.Image(t, options...)
-			if err != nil {
-				return "", fmt.Errorf("failed to get image manifest: %w", err)
-			}
-			subjectDigest, err := desc.Digest()
-			if err != nil {
-				return "", fmt.Errorf("failed to get image digest: %w", err)
-			}
-			r.digest = subjectDigest.String()
-		default:
-			return "", fmt.Errorf("unsupported reference type: %T", t)
+		options := WithOptions(ctx, r.Platform)
+		desc, err := remote.Image(subjectRef, options...)
+		if err != nil {
+			return "", fmt.Errorf("failed to get image manifest: %w", err)
 		}
+		subjectDigest, err := desc.Digest()
+		if err != nil {
+			return "", fmt.Errorf("failed to get image digest: %w", err)
+		}
+		r.digest = subjectDigest.String()
 	}
 	return r.digest, nil
 }

pkg/policy/policy.go

@@ -63,7 +63,7 @@ func findPolicyMatch(named reference.Named, mappings *config.PolicyMappings) (*c
 		for _, mapping := range mappings.Policies {
 			if mapping.Origin.Domain == reference.Domain(named) &&
 				strings.HasPrefix(reference.Path(named), mapping.Origin.Prefix) {
-				return &mapping, nil
+				return mapping, nil
 			}
 		}
 		// now search mirrors
@@ -73,10 +73,10 @@ func findPolicyMatch(named reference.Named, mappings *config.PolicyMappings) (*c
 				strings.HasPrefix(reference.Path(named), mirror.Mirror.Prefix) {
 				for _, mapping := range mappings.Policies {
 					if mapping.Id == mirror.PolicyId {
-						return &mapping, nil
+						return mapping, nil
 					}
 				}
-				return nil, &mirror
+				return nil, mirror
 			}
 		}
 	}
@@ -92,7 +92,7 @@ func resolvePolicyById(opts *PolicyOptions) (*Policy, error) {
 		if localMappings != nil {
 			for _, mapping := range localMappings.Policies {
 				if mapping.Id == opts.PolicyId {
-					return resolveLocalPolicy(opts, &mapping)
+					return resolveLocalPolicy(opts, mapping)
 				}
 			}
 		}
@@ -104,7 +104,7 @@ func resolvePolicyById(opts *PolicyOptions) (*Policy, error) {
 		}
 		for _, mapping := range tufMappings.Policies {
 			if mapping.Id == opts.PolicyId {
-				return resolveTufPolicy(opts, &mapping)
+				return resolveTufPolicy(opts, mapping)
 			}
 		}
 		return nil, fmt.Errorf("policy with id %s not found", opts.PolicyId)
@@ -146,7 +146,7 @@ func ResolvePolicy(ctx context.Context, detailsResolver oci.ImageDetailsResolver
 	if mirror != nil {
 		for _, mapping := range tufMappings.Policies {
 			if mapping.Id == mirror.PolicyId {
-				return resolveTufPolicy(opts, &mapping)
+				return resolveTufPolicy(opts, mapping)
 			}
 		}
 	}
@@ -172,7 +172,7 @@ func CreateImageDetailsResolver(imageSource *oci.ImageSpec) (oci.ImageDetailsRes
 func CreateAttestationResolver(resolver oci.ImageDetailsResolver, mapping *config.PolicyMapping) (oci.AttestationResolver, error) {
 	switch resolver := resolver.(type) {
 	case *oci.RegistryImageDetailsResolver:
-		if mapping.Attestations != nil && mapping.Attestations.Style == config.AttestationSourceAttached {
+		if mapping.Attestations != nil && mapping.Attestations.Style == config.AttestationStyleAttached {
 			return oci.NewRegistryAttestationResolver(resolver)
 		} else {
 			if mapping.Attestations != nil && mapping.Attestations.Repo != "" {

pkg/policy/types.go

@@ -27,11 +27,12 @@ type Result struct {
 }
 
 type PolicyOptions struct {
-	TufClient       tuf.TUFClient
-	LocalTargetsDir string
-	LocalPolicyDir  string
-	PolicyId        string
-	ReferrersRepo   string
+	TufClient        tuf.TUFClient
+	LocalTargetsDir  string
+	LocalPolicyDir   string
+	PolicyId         string
+	ReferrersRepo    string
+	AttestationStyle config.AttestationStyle
 }
 
 type Policy struct {

test/testdata/local-policy/doi/policy.rego

@@ -0,0 +1,49 @@
+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,
+	"status": "active",
+	"signing-format": "dssev1",
+}]
+
+provs(pred) := p if {
+	res := attest.fetch(pred)
+	not res.error
+	p := res.value
+}
+
+atts := union({
+	provs("https://slsa.dev/provenance/v0.2"),
+	provs("https://spdx.dev/Document"),
+})
+
+opts := {"keys": keys}
+
+statements contains s if {
+	some att in atts
+	res := attest.verify(att, opts)
+	not res.error
+	s := res.value
+}
+
+subjects contains subject if {
+	some statement in statements
+	some subject in statement.subject
+}
+
+result := {
+	"success": count(atts) > 0,
+	"violations": set(),
+	"attestations": statements,
+	"summary": {
+		"subjects": subjects,
+		"slsa_level": "SLSA_BUILD_LEVEL_3",
+		"verifier": "docker-official-images",
+		"policy_uri": "https://docker.com/official/policy/v0.1",
+	},
+}

test/testdata/local-policy/mapping.yaml

@@ -0,0 +1,29 @@
+# map repos to policies
+version: v1
+kind: policy-mapping
+policies:
+  - origin:
+      domain: docker.io
+      prefix: library/
+    id: test-images
+    description: Local test images
+    files:
+      - path: "doi/policy.rego"
+
+mirrors:
+  - policy-id: test-images
+    mirror:
+      domains: ["*"]
+      prefix: "repo"
+  - policy-id: test-images
+    mirror:
+      domains: ["*"]
+      prefix: "library/"
+  - policy-id: test-images
+    mirror:
+      domains: ["*"]
+      prefix: "test-image"
+  - policy-id: test-images
+    mirror:
+      domains: ["*"]
+      prefix: "image-signer-verifier-test"