feat: validate input media type for oras.PackManifest (#574)

Resolves: #571
Signed-off-by: Lixia (Sylvia) Lei <lixlei@microsoft.com>

errdef/errors.go

@@ -22,6 +22,7 @@ var (
 	ErrAlreadyExists      = errors.New("already exists")
 	ErrInvalidDigest      = errors.New("invalid digest")
 	ErrInvalidReference   = errors.New("invalid reference")
+	ErrInvalidMediaType   = errors.New("invalid media type")
 	ErrMissingReference   = errors.New("missing reference")
 	ErrNotFound           = errors.New("not found")
 	ErrSizeExceedsLimit   = errors.New("size exceeds limit")

example_test.go

@@ -111,7 +111,7 @@ func Example_pushFilesToRemoteRepository() {
 	ctx := context.Background()
 
 	// 1. Add files to the file store
-	mediaType := "example/file"
+	mediaType := "application/vnd.test.file"
 	fileNames := []string{"/tmp/myfile"}
 	fileDescriptors := make([]v1.Descriptor, 0, len(fileNames))
 	for _, name := range fileNames {
@@ -124,7 +124,7 @@ func Example_pushFilesToRemoteRepository() {
 	}
 
 	// 2. Pack the files and tag the packed manifest
-	artifactType := "example/files"
+	artifactType := "application/vnd.test.artifact"
 	opts := oras.PackManifestOptions{
 		Layers: fileDescriptors,
 	}

pack.go

@@ -21,6 +21,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"regexp"
 	"time"
 
 	specs "github.com/opencontainers/image-spec/specs-go"
@@ -95,6 +96,12 @@ type PackManifestOptions struct {
 	ConfigAnnotations map[string]string
 }
 
+// mediaTypeRegexp checks the format of media types.
+// References:
+//   - https://github.com/opencontainers/image-spec/blob/v1.1.0-rc4/schema/defs-descriptor.json#L7
+//   - https://datatracker.ietf.org/doc/html/rfc6838#section-4.2
+var mediaTypeRegexp = regexp.MustCompile(`^[A-Za-z0-9][A-Za-z0-9!#$&-^_.+]{0,126}/[A-Za-z0-9][A-Za-z0-9!#$&-^_.+]{0,126}$`)
+
 // PackManifest generates an OCI Image Manifest based on the given parameters
 // and pushes the packed manifest to a content storage using pusher. The version
 // of the manifest to be packed is determined by packManifestVersion
@@ -108,6 +115,8 @@ type PackManifestOptions struct {
 //     "application/vnd.unknown.config.v1+json" will be used.
 //     if opts.ConfigDescriptor is NOT nil, artifactType will be ignored.
 //
+// artifactType and opts.ConfigDescriptor.MediaType MUST comply with RFC 6838.
+//
 // If succeeded, returns a descriptor of the packed manifest.
 func PackManifest(ctx context.Context, pusher content.Pusher, packManifestVersion PackManifestVersion, artifactType string, opts PackManifestOptions) (ocispec.Descriptor, error) {
 	switch packManifestVersion {
@@ -190,28 +199,28 @@ func packArtifact(ctx context.Context, pusher content.Pusher, artifactType strin
 
 // packManifestV1_0 packs an image manifest defined in image-spec v1.0.2.
 // Reference: https://github.com/opencontainers/image-spec/blob/v1.0.2/manifest.md
-func packManifestV1_0(ctx context.Context, pusher content.Pusher, configMediaType string, opts PackManifestOptions) (ocispec.Descriptor, error) {
+func packManifestV1_0(ctx context.Context, pusher content.Pusher, artifactType string, opts PackManifestOptions) (ocispec.Descriptor, error) {
 	if opts.Subject != nil {
 		return ocispec.Descriptor{}, fmt.Errorf("subject is not supported for manifest version %v: %w", PackManifestVersion1_0, errdef.ErrUnsupported)
 	}
-	if configMediaType == "" {
-		configMediaType = MediaTypeUnknownConfig
-	}
 
+	// prepare config
 	var configDesc ocispec.Descriptor
 	if opts.ConfigDescriptor != nil {
+		if err := validateMediaType(opts.ConfigDescriptor.MediaType); err != nil {
+			return ocispec.Descriptor{}, fmt.Errorf("invalid config mediaType format: %w", err)
+		}
 		configDesc = *opts.ConfigDescriptor
 	} else {
-		// Use an empty JSON object here, because some registries may not accept
-		// empty config blob.
-		// As of September 2022, GAR is known to return 400 on empty blob upload.
-		// See https://github.com/oras-project/oras-go/issues/294 for details.
-		configBytes := []byte("{}")
-		configDesc = content.NewDescriptorFromBytes(configMediaType, configBytes)
-		configDesc.Annotations = opts.ConfigAnnotations
-		// push config
-		if err := pushIfNotExist(ctx, pusher, configDesc, configBytes); err != nil {
-			return ocispec.Descriptor{}, fmt.Errorf("failed to push config: %w", err)
+		if artifactType == "" {
+			artifactType = MediaTypeUnknownConfig
+		} else if err := validateMediaType(artifactType); err != nil {
+			return ocispec.Descriptor{}, fmt.Errorf("invalid artifactType format: %w", err)
+		}
+		var err error
+		configDesc, err = pushCustomEmptyConfig(ctx, pusher, artifactType, opts.ConfigAnnotations)
+		if err != nil {
+			return ocispec.Descriptor{}, err
 		}
 	}
 
@@ -242,20 +251,15 @@ func packManifestV1_1_RC2(ctx context.Context, pusher content.Pusher, configMedi
 		configMediaType = MediaTypeUnknownConfig
 	}
 
+	// prepare config
 	var configDesc ocispec.Descriptor
 	if opts.ConfigDescriptor != nil {
 		configDesc = *opts.ConfigDescriptor
 	} else {
-		// Use an empty JSON object here, because some registries may not accept
-		// empty config blob.
-		// As of September 2022, GAR is known to return 400 on empty blob upload.
-		// See https://github.com/oras-project/oras-go/issues/294 for details.
-		configBytes := []byte("{}")
-		configDesc = content.NewDescriptorFromBytes(configMediaType, configBytes)
-		configDesc.Annotations = opts.ConfigAnnotations
-		// push config
-		if err := pushIfNotExist(ctx, pusher, configDesc, configBytes); err != nil {
-			return ocispec.Descriptor{}, fmt.Errorf("failed to push config: %w", err)
+		var err error
+		configDesc, err = pushCustomEmptyConfig(ctx, pusher, configMediaType, opts.ConfigAnnotations)
+		if err != nil {
+			return ocispec.Descriptor{}, err
 		}
 	}
 
@@ -286,10 +290,19 @@ func packManifestV1_1_RC4(ctx context.Context, pusher content.Pusher, artifactTy
 		// artifactType MUST be set when config.mediaType is set to the empty value
 		return ocispec.Descriptor{}, ErrMissingArtifactType
 	}
+	if artifactType != "" {
+		if err := validateMediaType(artifactType); err != nil {
+			return ocispec.Descriptor{}, fmt.Errorf("invalid artifactType format: %w", err)
+		}
+	}
 
+	// prepare config
 	var emptyBlobExists bool
 	var configDesc ocispec.Descriptor
 	if opts.ConfigDescriptor != nil {
+		if err := validateMediaType(opts.ConfigDescriptor.MediaType); err != nil {
+			return ocispec.Descriptor{}, fmt.Errorf("invalid config mediaType format: %w", err)
+		}
 		configDesc = *opts.ConfigDescriptor
 	} else {
 		// use the empty descriptor for config
@@ -369,6 +382,22 @@ func pushManifest(ctx context.Context, pusher content.Pusher, manifest any, medi
 	return manifestDesc, nil
 }
 
+// pushCustomEmptyConfig generates and pushes an empty config blob.
+func pushCustomEmptyConfig(ctx context.Context, pusher content.Pusher, mediaType string, annotations map[string]string) (ocispec.Descriptor, error) {
+	// Use an empty JSON object here, because some registries may not accept
+	// empty config blob.
+	// As of September 2022, GAR is known to return 400 on empty blob upload.
+	// See https://github.com/oras-project/oras-go/issues/294 for details.
+	configBytes := []byte("{}")
+	configDesc := content.NewDescriptorFromBytes(mediaType, configBytes)
+	configDesc.Annotations = annotations
+	// push config
+	if err := pushIfNotExist(ctx, pusher, configDesc, configBytes); err != nil {
+		return ocispec.Descriptor{}, fmt.Errorf("failed to push config: %w", err)
+	}
+	return configDesc, nil
+}
+
 // ensureAnnotationCreated ensures that annotationCreatedKey is in annotations,
 // and that its value conforms to RFC 3339. Otherwise returns a new annotation
 // map with annotationCreatedKey created.
@@ -392,3 +421,11 @@ func ensureAnnotationCreated(annotations map[string]string, annotationCreatedKey
 	copied[annotationCreatedKey] = now.Format(time.RFC3339)
 	return copied, nil
 }
+
+// validateMediaType validates the format of mediaType.
+func validateMediaType(mediaType string) error {
+	if !mediaTypeRegexp.MatchString(mediaType) {
+		return fmt.Errorf("%s: %w", mediaType, errdef.ErrInvalidMediaType)
+	}
+	return nil
+}