Add support for creating sigstore signatures, and providing passphrases

- Allow creating sigstore signatures via --sign-by-sigstore-private-key .
  Like existing --sign-by, it does not work remote (in this case
  because we would have to copy the private key to the server).
- Allow passing a passphrase (which is mandatory for sigstore private keys)
  via --sign-passphrase-file; if it is not provided, prompt interactively.
- Also, use that passphrase for --sign-by as well, allowing non-interactive
  GPG use. (But --sign-passphrase-file can only be used with _one of_
  --sign-by and --sign-by-sigstore-private-key.)

Note that unlike the existing code, (podman build) does not yet
implement sigstore (I'm not sure why it needs to, it seems not to
push images?) because Buildah does not expose the feature yet.

Also, (podman image sign) was not extended to support sigstore.

The test for this follows existing (podman image sign) tests
and doesn't work rootless; that could be improved by exposing
a registries.d override option.

The test for push is getting large; I didn't want to
start yet another registry container, but that would be an
alternative.  In the future, Ginkgo's Ordered/BeforeAll
would allow starting a registry once and using it for two
tests.

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

3 files changed, 16 insertions, 0 deletions

diff --git a/pkg/domain/entities/images.go b/pkg/domain/entities/images.go
index b8b346005..dad2dc6cc 100644
--- a/pkg/domain/entities/images.go
+++ b/pkg/domain/entities/images.go
@@ -205,6 +205,16 @@ type ImagePushOptions struct {
 	// SignBy adds a signature at the destination using the specified key.
 	// Ignored for remote calls.
 	SignBy string
+	// SignPassphrase, if non-empty, specifies a passphrase to use when signing
+	// with the key ID from SignBy.
+	SignPassphrase string
+	// SignBySigstorePrivateKeyFile, if non-empty, asks for a signature to be added
+	// during the copy, using a sigstore private key file at the provided path.
+	// Ignored for remote calls.
+	SignBySigstorePrivateKeyFile string
+	// SignSigstorePrivateKeyPassphrase is the passphrase to use when signing with
+	// SignBySigstorePrivateKeyFile.
+	SignSigstorePrivateKeyPassphrase []byte
 	// SkipTLSVerify to skip HTTPS and certificate verification.
 	SkipTLSVerify types.OptionalBool
 	// Progress to get progress notifications
diff --git a/pkg/domain/infra/abi/images.go b/pkg/domain/infra/abi/images.go
index ff42b0367..94178a8e2 100644
--- a/pkg/domain/infra/abi/images.go
+++ b/pkg/domain/infra/abi/images.go
@@ -304,6 +304,9 @@ func (ir *ImageEngine) Push(ctx context.Context, source string, destination stri
 	pushOptions.ManifestMIMEType = manifestType
 	pushOptions.RemoveSignatures = options.RemoveSignatures
 	pushOptions.SignBy = options.SignBy
+	pushOptions.SignPassphrase = options.SignPassphrase
+	pushOptions.SignBySigstorePrivateKeyFile = options.SignBySigstorePrivateKeyFile
+	pushOptions.SignSigstorePrivateKeyPassphrase = options.SignSigstorePrivateKeyPassphrase
 	pushOptions.InsecureSkipTLSVerify = options.SkipTLSVerify
 	pushOptions.Writer = options.Writer
 
diff --git a/pkg/domain/infra/abi/manifest.go b/pkg/domain/infra/abi/manifest.go
index d20744d76..60f727234 100644
--- a/pkg/domain/infra/abi/manifest.go
+++ b/pkg/domain/infra/abi/manifest.go
@@ -316,6 +316,9 @@ func (ir *ImageEngine) ManifestPush(ctx context.Context, name, destination strin
 	pushOptions.ManifestMIMEType = manifestType
 	pushOptions.RemoveSignatures = opts.RemoveSignatures
 	pushOptions.SignBy = opts.SignBy
+	pushOptions.SignPassphrase = opts.SignPassphrase
+	pushOptions.SignBySigstorePrivateKeyFile = opts.SignBySigstorePrivateKeyFile
+	pushOptions.SignSigstorePrivateKeyPassphrase = opts.SignSigstorePrivateKeyPassphrase
 	pushOptions.InsecureSkipTLSVerify = opts.SkipTLSVerify
 
 	if opts.All {