Add Cosign signing/verification

Makefile

@@ -11,7 +11,7 @@ else
 CONTAINERSCONFDIR ?= /etc/containers
 endif
 REGISTRIESDDIR ?= ${CONTAINERSCONFDIR}/registries.d
-SIGSTOREDIR ?= /var/lib/containers/sigstore
+LOOKASIDEDIR ?= /var/lib/containers/sigstore
 BINDIR ?= ${PREFIX}/bin
 MANDIR ?= ${PREFIX}/share/man
 
@@ -163,7 +163,7 @@ clean:
 	rm -rf bin docs/*.1 completions/
 
 install: install-binary install-docs install-completions
-	install -d -m 755 ${DESTDIR}${SIGSTOREDIR}
+	install -d -m 755 ${DESTDIR}${LOOKASIDEDIR}
 	install -d -m 755 ${DESTDIR}${CONTAINERSCONFDIR}
 	install -m 644 default-policy.json ${DESTDIR}${CONTAINERSCONFDIR}/policy.json
 	install -d -m 755 ${DESTDIR}${REGISTRIESDDIR}

cmd/skopeo/copy.go

@@ -21,25 +21,26 @@ import (
 )
 
 type copyOptions struct {
-	global              *globalOptions
-	deprecatedTLSVerify *deprecatedTLSVerifyOption
-	srcImage            *imageOptions
-	destImage           *imageDestOptions
-	retryOpts           *retry.RetryOptions
-	additionalTags      []string                  // For docker-archive: destinations, in addition to the name:tag specified as destination, also add these
-	removeSignatures    bool                      // Do not copy signatures from the source image
-	signByFingerprint   string                    // Sign the image using a GPG key with the specified fingerprint
-	signPassphraseFile  string                    // Path pointing to a passphrase file when signing
-	signIdentity        string                    // Identity of the signed image, must be a fully specified docker reference
-	digestFile          string                    // Write digest to this file
-	format              commonFlag.OptionalString // Force conversion of the image to a specified format
-	quiet               bool                      // Suppress output information when copying images
-	all                 bool                      // Copy all of the images if the source is a list
-	multiArch           commonFlag.OptionalString // How to handle multi architecture images
-	preserveDigests     bool                      // Preserve digests during copy
-	encryptLayer        []int                     // The list of layers to encrypt
-	encryptionKeys      []string                  // Keys needed to encrypt the image
-	decryptionKeys      []string                  // Keys needed to decrypt the image
+	global                   *globalOptions
+	deprecatedTLSVerify      *deprecatedTLSVerifyOption
+	srcImage                 *imageOptions
+	destImage                *imageDestOptions
+	retryOpts                *retry.RetryOptions
+	additionalTags           []string                  // For docker-archive: destinations, in addition to the name:tag specified as destination, also add these
+	removeSignatures         bool                      // Do not copy signatures from the source image
+	signByFingerprint        string                    // Sign the image using a GPG key with the specified fingerprint
+	signBySigstorePrivateKey string                    // Sign the image using a sigstore private key
+	signPassphraseFile       string                    // Path pointing to a passphrase file when signing (for either signature format, but only one of them)
+	signIdentity             string                    // Identity of the signed image, must be a fully specified docker reference
+	digestFile               string                    // Write digest to this file
+	format                   commonFlag.OptionalString // Force conversion of the image to a specified format
+	quiet                    bool                      // Suppress output information when copying images
+	all                      bool                      // Copy all of the images if the source is a list
+	multiArch                commonFlag.OptionalString // How to handle multi architecture images
+	preserveDigests          bool                      // Preserve digests during copy
+	encryptLayer             []int                     // The list of layers to encrypt
+	encryptionKeys           []string                  // Keys needed to encrypt the image
+	decryptionKeys           []string                  // Keys needed to decrypt the image
 }
 
 func copyCmd(global *globalOptions) *cobra.Command {
@@ -82,7 +83,8 @@ See skopeo(1) section "IMAGE NAMES" for the expected format
 	flags.BoolVar(&opts.preserveDigests, "preserve-digests", false, "Preserve digests of images and lists")
 	flags.BoolVar(&opts.removeSignatures, "remove-signatures", false, "Do not copy signatures from SOURCE-IMAGE")
 	flags.StringVar(&opts.signByFingerprint, "sign-by", "", "Sign the image using a GPG key with the specified `FINGERPRINT`")
-	flags.StringVar(&opts.signPassphraseFile, "sign-passphrase-file", "", "File that contains a passphrase for the --sign-by key")
+	flags.StringVar(&opts.signBySigstorePrivateKey, "sign-by-sigstore-private-key", "", "Sign the image using a sigstore private key at `PATH`")
+	flags.StringVar(&opts.signPassphraseFile, "sign-passphrase-file", "", "Read a passphrase for signing an image from `PATH`")
 	flags.StringVar(&opts.signIdentity, "sign-identity", "", "Identity of signed image, must be a fully specified docker reference. Defaults to the target docker reference.")
 	flags.StringVar(&opts.digestFile, "digestfile", "", "Write the digest of the pushed image to the specified file")
 	flags.VarP(commonFlag.NewOptionalStringValue(&opts.format), "format", "f", `MANIFEST TYPE (oci, v2s1, or v2s2) to use in the destination (default is manifest type of source, with fallbacks)`)
@@ -229,10 +231,26 @@ func (opts *copyOptions) run(args []string, stdout io.Writer) (retErr error) {
 		decConfig = cc.DecryptConfig
 	}
 
-	passphrase, err := cli.ReadPassphraseFile(opts.signPassphraseFile)
-	if err != nil {
-		return err
+	// c/image/copy.Image does allow creating both simple signing and sigstore signatures simultaneously,
+	// with independent passphrases, but that would make the CLI probably too confusing.
+	// For now, use the passphrase with either, but only one of them.
+	if opts.signPassphraseFile != "" && opts.signByFingerprint != "" && opts.signBySigstorePrivateKey != "" {
+		return fmt.Errorf("Only one of --sign-by and sign-by-sigstore-private-key can be used with sign-passphrase-file")
 	}
+	var passphrase string
+	if opts.signPassphraseFile != "" {
+		p, err := cli.ReadPassphraseFile(opts.signPassphraseFile)
+		if err != nil {
+			return err
+		}
+		passphrase = p
+	} else if opts.signBySigstorePrivateKey != "" {
+		p, err := promptForPassphrase(opts.signBySigstorePrivateKey, os.Stdin, os.Stdout)
+		if err != nil {
+			return err
+		}
+		passphrase = p
+	} // opts.signByFingerprint triggers a GPG-agent passphrase prompt, possibly using a more secure channel, so we usually shouldn’t prompt ourselves if no passphrase was explicitly provided.
 
 	var signIdentity reference.Named = nil
 	if opts.signIdentity != "" {
@@ -244,19 +262,21 @@ func (opts *copyOptions) run(args []string, stdout io.Writer) (retErr error) {
 
 	return retry.RetryIfNecessary(ctx, func() error {
 		manifestBytes, err := copy.Image(ctx, policyContext, destRef, srcRef, &copy.Options{
-			RemoveSignatures:      opts.removeSignatures,
-			SignBy:                opts.signByFingerprint,
-			SignPassphrase:        passphrase,
-			SignIdentity:          signIdentity,
-			ReportWriter:          stdout,
-			SourceCtx:             sourceCtx,
-			DestinationCtx:        destinationCtx,
-			ForceManifestMIMEType: manifestType,
-			ImageListSelection:    imageListSelection,
-			PreserveDigests:       opts.preserveDigests,
-			OciDecryptConfig:      decConfig,
-			OciEncryptLayers:      encLayers,
-			OciEncryptConfig:      encConfig,
+			RemoveSignatures:                 opts.removeSignatures,
+			SignBy:                           opts.signByFingerprint,
+			SignPassphrase:                   passphrase,
+			SignBySigstorePrivateKeyFile:     opts.signBySigstorePrivateKey,
+			SignSigstorePrivateKeyPassphrase: []byte(passphrase),
+			SignIdentity:                     signIdentity,
+			ReportWriter:                     stdout,
+			SourceCtx:                        sourceCtx,
+			DestinationCtx:                   destinationCtx,
+			ForceManifestMIMEType:            manifestType,
+			ImageListSelection:               imageListSelection,
+			PreserveDigests:                  opts.preserveDigests,
+			OciDecryptConfig:                 decConfig,
+			OciEncryptLayers:                 encLayers,
+			OciEncryptConfig:                 encConfig,
 		})
 		if err != nil {
 			return err

cmd/skopeo/sync.go

@@ -29,22 +29,23 @@ import (
 
 // syncOptions contains information retrieved from the skopeo sync command line.
 type syncOptions struct {
-	global              *globalOptions // Global (not command dependent) skopeo options
-	deprecatedTLSVerify *deprecatedTLSVerifyOption
-	srcImage            *imageOptions     // Source image options
-	destImage           *imageDestOptions // Destination image options
-	retryOpts           *retry.RetryOptions
-	removeSignatures    bool                      // Do not copy signatures from the source image
-	signByFingerprint   string                    // Sign the image using a GPG key with the specified fingerprint
-	signPassphraseFile  string                    // Path pointing to a passphrase file when signing
-	format              commonFlag.OptionalString // Force conversion of the image to a specified format
-	source              string                    // Source repository name
-	destination         string                    // Destination registry name
-	scoped              bool                      // When true, namespace copied images at destination using the source repository name
-	all                 bool                      // Copy all of the images if an image in the source is a list
-	dryRun              bool                      // Don't actually copy anything, just output what it would have done
-	preserveDigests     bool                      // Preserve digests during sync
-	keepGoing           bool                      // Whether or not to abort the sync if there are any errors during syncing the images
+	global                   *globalOptions // Global (not command dependent) skopeo options
+	deprecatedTLSVerify      *deprecatedTLSVerifyOption
+	srcImage                 *imageOptions     // Source image options
+	destImage                *imageDestOptions // Destination image options
+	retryOpts                *retry.RetryOptions
+	removeSignatures         bool                      // Do not copy signatures from the source image
+	signByFingerprint        string                    // Sign the image using a GPG key with the specified fingerprint
+	signBySigstorePrivateKey string                    // Sign the image using a sigstore private key
+	signPassphraseFile       string                    // Path pointing to a passphrase file when signing
+	format                   commonFlag.OptionalString // Force conversion of the image to a specified format
+	source                   string                    // Source repository name
+	destination              string                    // Destination registry name
+	scoped                   bool                      // When true, namespace copied images at destination using the source repository name
+	all                      bool                      // Copy all of the images if an image in the source is a list
+	dryRun                   bool                      // Don't actually copy anything, just output what it would have done
+	preserveDigests          bool                      // Preserve digests during sync
+	keepGoing                bool                      // Whether or not to abort the sync if there are any errors during syncing the images
 }
 
 // repoDescriptor contains information of a single repository used as a sync source.
@@ -105,6 +106,7 @@ See skopeo-sync(1) for details.
 	flags := cmd.Flags()
 	flags.BoolVar(&opts.removeSignatures, "remove-signatures", false, "Do not copy signatures from SOURCE images")
 	flags.StringVar(&opts.signByFingerprint, "sign-by", "", "Sign the image using a GPG key with the specified `FINGERPRINT`")
+	flags.StringVar(&opts.signBySigstorePrivateKey, "sign-by-sigstore-private-key", "", "Sign the image using a sigstore private key at `PATH`")
 	flags.StringVar(&opts.signPassphraseFile, "sign-passphrase-file", "", "File that contains a passphrase for the --sign-by key")
 	flags.VarP(commonFlag.NewOptionalStringValue(&opts.format), "format", "f", `MANIFEST TYPE (oci, v2s1, or v2s2) to use when syncing image(s) to a destination (default is manifest type of source, with fallbacks)`)
 	flags.StringVarP(&opts.source, "src", "s", "", "SOURCE transport type")
@@ -582,14 +584,32 @@ func (opts *syncOptions) run(args []string, stdout io.Writer) (retErr error) {
 		return err
 	}
 
-	passphrase, err := cli.ReadPassphraseFile(opts.signPassphraseFile)
-	if err != nil {
-		return err
+	// c/image/copy.Image does allow creating both simple signing and sigstore signatures simultaneously,
+	// with independent passphrases, but that would make the CLI probably too confusing.
+	// For now, use the passphrase with either, but only one of them.
+	if opts.signPassphraseFile != "" && opts.signByFingerprint != "" && opts.signBySigstorePrivateKey != "" {
+		return fmt.Errorf("Only one of --sign-by and sign-by-sigstore-private-key can be used with sign-passphrase-file")
+	}
+	var passphrase string
+	if opts.signPassphraseFile != "" {
+		p, err := cli.ReadPassphraseFile(opts.signPassphraseFile)
+		if err != nil {
+			return err
+		}
+		passphrase = p
+	} else if opts.signBySigstorePrivateKey != "" {
+		p, err := promptForPassphrase(opts.signBySigstorePrivateKey, os.Stdin, os.Stdout)
+		if err != nil {
+			return err
+		}
+		passphrase = p
 	}
 	options := copy.Options{
 		RemoveSignatures:                      opts.removeSignatures,
 		SignBy:                                opts.signByFingerprint,
 		SignPassphrase:                        passphrase,
+		SignBySigstorePrivateKeyFile:          opts.signBySigstorePrivateKey,
+		SignSigstorePrivateKeyPassphrase:      []byte(passphrase),
 		ReportWriter:                          os.Stdout,
 		DestinationCtx:                        destinationCtx,
 		ImageListSelection:                    imageListSelection,

cmd/skopeo/utils.go

@@ -18,6 +18,7 @@ import (
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
+	"golang.org/x/term"
 )
 
 // errorShouldDisplayUsage is a subtype of error used by command handlers to indicate that cli.ShowSubcommandHelp should be called.
@@ -376,3 +377,19 @@ func adjustUsage(c *cobra.Command) {
 	c.SetUsageTemplate(usageTemplate)
 	c.DisableFlagsInUseLine = true
 }
+
+// promptForPassphrase interactively prompts for a passphrase related to privateKeyFile
+func promptForPassphrase(privateKeyFile string, stdin, stdout *os.File) (string, error) {
+	stdinFd := int(stdin.Fd())
+	if !term.IsTerminal(stdinFd) {
+		return "", fmt.Errorf("Cannot prompt for a passphrase for key %s, standard input is not a TTY", privateKeyFile)
+	}
+
+	fmt.Fprintf(stdout, "Passphrase for key %s: ", privateKeyFile)
+	passphrase, err := term.ReadPassword(stdinFd)
+	if err != nil {
+		return "", fmt.Errorf("Error reading password: %w", err)
+	}
+	fmt.Fprintf(stdout, "\n")
+	return string(passphrase), nil
+}

default.yaml

@@ -1,26 +1,26 @@
 # This is a default registries.d configuration file.  You may
 # add to this file or create additional files in registries.d/.
 #
-# sigstore: indicates a location that is read and write
-# sigstore-staging: indicates a location that is only for write
+# lookaside: indicates a location that is read and write
+# lookaside-staging: indicates a location that is only for write
 #
-# sigstore and sigstore-staging take a value of the following:
-#   sigstore:  {schema}://location
+# lookaside and lookaside-staging take a value of the following:
+#   lookaside:  {schema}://location
 #
 # For reading signatures, schema may be http, https, or file.
 # For writing signatures, schema may only be file.
 
 # This is the default signature write location for docker registries.
 default-docker:
-#  sigstore: file:///var/lib/containers/sigstore
-  sigstore-staging: file:///var/lib/containers/sigstore
+#  lookaside: file:///var/lib/containers/sigstore
+  lookaside-staging: file:///var/lib/containers/sigstore
 
 # The 'docker' indicator here is the start of the configuration
 # for docker registries.
 #
 # docker:
 #
 #   privateregistry.com:
-#    sigstore: http://privateregistry.com/sigstore/
-#    sigstore-staging: /mnt/nfs/privateregistry/sigstore
+#    lookaside: http://privateregistry.com/sigstore/
+#    lookaside-staging: /mnt/nfs/privateregistry/sigstore
 

docs/skopeo-copy.1.md

@@ -91,11 +91,15 @@ Do not copy signatures, if any, from _source-image_. Necessary when copying a si
 
 **--sign-by** _key-id_
 
-Add a signature using that key ID for an image name corresponding to _destination-image_
+Add a “simple signing” signature using that key ID for an image name corresponding to _destination-image_
+
+**--sign-by-sigstore-private-key** _path_
+
+Add a sigstore signature using a private key at _path_ for an image name corresponding to _destination-image_
 
 **--sign-passphrase-file** _path_
 
-The passphare to use when signing with the key ID from `--sign-by`. Only the first line will be read. A passphrase stored in a file is of questionable security if other users can read this file. Do not use this option if at all avoidable.
+The passphare to use when signing with `--sign-by` or `--sign-by-sigstore-private-key`. Only the first line will be read. A passphrase stored in a file is of questionable security if other users can read this file. Do not use this option if at all avoidable.
 
 **--sign-identity** _reference_
 

docs/skopeo-sync.1.md

@@ -70,9 +70,17 @@ Print usage statement.
 
 **--remove-signatures** Do not copy signatures, if any, from _source-image_. This is necessary when copying a signed image to a destination which does not support signatures.
 
-**--sign-by**=_key-id_ Add a signature using that key ID for an image name corresponding to _destination-image_.
+**--sign-by** _key-id_
 
-**--sign-passphrase-file**=_path_ The passphare to use when signing with the key ID from `--sign-by`. Only the first line will be read. A passphrase stored in a file is of questionable security if other users can read this file. Do not use this option if at all avoidable.
+Add a “simple signing” signature using that key ID for an image name corresponding to _destination-image_
+
+**--sign-by-sigstore-private-key** _path_
+
+Add a sigstore signature using a private key at _path_ for an image name corresponding to _destination-image_
+
+**--sign-passphrase-file** _path_
+
+The passphare to use when signing with `--sign-by` or `--sign-by-sigstore-private-key`. Only the first line will be read. A passphrase stored in a file is of questionable security if other users can read this file. Do not use this option if at all avoidable.
 
 **--src-creds** _username[:password]_ for accessing the source registry.