16 files changed, 206 insertions, 6 deletions
diff --git a/cmd/podman/common/sign.go b/cmd/podman/common/sign.go
new file mode 100644
index 000000000..e8a90ed57
--- /dev/null
+++ b/cmd/podman/common/sign.go
@@ -0,0 +1,36 @@
+package common
+
+import (
+	"fmt"
+
+	"github.com/containers/image/v5/pkg/cli"
+	"github.com/containers/podman/v4/pkg/domain/entities"
+	"github.com/containers/podman/v4/pkg/terminal"
+)
+
+// PrepareSigningPassphrase updates pushOpts.SignPassphrase and SignSigstorePrivateKeyPassphrase based on a --sign-passphrase-file value signPassphraseFile,
+// and validates pushOpts.Sign* consistency.
+// It may interactively prompt for a passphrase if one is required and wasn’t provided otherwise.
+func PrepareSigningPassphrase(pushOpts *entities.ImagePushOptions, signPassphraseFile string) error {
+	// c/common/libimage.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 signPassphraseFile != "" && pushOpts.SignBy != "" && pushOpts.SignBySigstorePrivateKeyFile != "" {
+		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 signPassphraseFile != "" {
+		p, err := cli.ReadPassphraseFile(signPassphraseFile)
+		if err != nil {
+			return err
+		}
+		passphrase = p
+	} else if pushOpts.SignBySigstorePrivateKeyFile != "" {
+		p := terminal.ReadPassphrase()
+		passphrase = string(p)
+	} // pushOpts.SignBy 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.
+	pushOpts.SignPassphrase = passphrase
+	pushOpts.SignSigstorePrivateKeyPassphrase = []byte(passphrase)
+	return nil
+}
diff --git a/cmd/podman/images/push.go b/cmd/podman/images/push.go
index 764936426..1734900de 100644
--- a/cmd/podman/images/push.go
+++ b/cmd/podman/images/push.go
@@ -17,8 +17,9 @@ import (
 // CLI-only fields into the API types.
 type pushOptionsWrapper struct {
 	entities.ImagePushOptions
-	TLSVerifyCLI   bool // CLI only
-	CredentialsCLI string
+	TLSVerifyCLI          bool // CLI only
+	CredentialsCLI        string
+	SignPassphraseFileCLI string
 }
 
 var (
@@ -106,6 +107,14 @@ func pushFlags(cmd *cobra.Command) {
 	flags.StringVar(&pushOptions.SignBy, signByFlagName, "", "Add a signature at the destination using the specified key")
 	_ = cmd.RegisterFlagCompletionFunc(signByFlagName, completion.AutocompleteNone)
 
+	signBySigstorePrivateKeyFlagName := "sign-by-sigstore-private-key"
+	flags.StringVar(&pushOptions.SignBySigstorePrivateKeyFile, signBySigstorePrivateKeyFlagName, "", "Sign the image using a sigstore private key at `PATH`")
+	_ = cmd.RegisterFlagCompletionFunc(signBySigstorePrivateKeyFlagName, completion.AutocompleteDefault)
+
+	signPassphraseFileFlagName := "sign-passphrase-file"
+	flags.StringVar(&pushOptions.SignPassphraseFileCLI, signPassphraseFileFlagName, "", "Read a passphrase for signing an image from `PATH`")
+	_ = cmd.RegisterFlagCompletionFunc(signPassphraseFileFlagName, completion.AutocompleteDefault)
+
 	flags.BoolVar(&pushOptions.TLSVerifyCLI, "tls-verify", true, "Require HTTPS and verify certificates when contacting registries")
 
 	compressionFormat := "compression-format"
@@ -118,6 +127,8 @@ func pushFlags(cmd *cobra.Command) {
 		_ = flags.MarkHidden("digestfile")
 		_ = flags.MarkHidden("quiet")
 		_ = flags.MarkHidden(signByFlagName)
+		_ = flags.MarkHidden(signBySigstorePrivateKeyFlagName)
+		_ = flags.MarkHidden(signPassphraseFileFlagName)
 	}
 	if !registry.IsRemote() {
 		flags.StringVar(&pushOptions.SignaturePolicy, "signature-policy", "", "Path to a signature-policy file")
@@ -153,6 +164,10 @@ func imagePush(cmd *cobra.Command, args []string) error {
 		pushOptions.Password = creds.Password
 	}
 
+	if err := common.PrepareSigningPassphrase(&pushOptions.ImagePushOptions, pushOptions.SignPassphraseFileCLI); err != nil {
+		return err
+	}
+
 	// Let's do all the remaining Yoga in the API to prevent us from scattering
 	// logic across (too) many parts of the code.
 	return registry.ImageEngine().Push(registry.GetContext(), source, destination, pushOptions.ImagePushOptions)
diff --git a/cmd/podman/manifest/push.go b/cmd/podman/manifest/push.go
index df394d275..6afd8ea4c 100644
--- a/cmd/podman/manifest/push.go
+++ b/cmd/podman/manifest/push.go
@@ -20,8 +20,9 @@ import (
 type manifestPushOptsWrapper struct {
 	entities.ImagePushOptions
 
-	TLSVerifyCLI   bool // CLI only
-	CredentialsCLI string
+	TLSVerifyCLI          bool // CLI only
+	CredentialsCLI        string
+	SignPassphraseFileCLI string
 }
 
 var (
@@ -72,6 +73,14 @@ func init() {
 	flags.StringVar(&manifestPushOpts.SignBy, signByFlagName, "", "sign the image using a GPG key with the specified `FINGERPRINT`")
 	_ = pushCmd.RegisterFlagCompletionFunc(signByFlagName, completion.AutocompleteNone)
 
+	signBySigstorePrivateKeyFlagName := "sign-by-sigstore-private-key"
+	flags.StringVar(&manifestPushOpts.SignBySigstorePrivateKeyFile, signBySigstorePrivateKeyFlagName, "", "Sign the image using a sigstore private key at `PATH`")
+	_ = pushCmd.RegisterFlagCompletionFunc(signBySigstorePrivateKeyFlagName, completion.AutocompleteDefault)
+
+	signPassphraseFileFlagName := "sign-passphrase-file"
+	flags.StringVar(&manifestPushOpts.SignPassphraseFileCLI, signPassphraseFileFlagName, "", "Read a passphrase for signing an image from `PATH`")
+	_ = pushCmd.RegisterFlagCompletionFunc(signPassphraseFileFlagName, completion.AutocompleteDefault)
+
 	flags.BoolVar(&manifestPushOpts.TLSVerifyCLI, "tls-verify", true, "require HTTPS and verify certificates when accessing the registry")
 	flags.BoolVarP(&manifestPushOpts.Quiet, "quiet", "q", false, "don't output progress information when pushing lists")
 	flags.SetNormalizeFunc(utils.AliasFlags)
@@ -79,6 +88,8 @@ func init() {
 	if registry.IsRemote() {
 		_ = flags.MarkHidden("cert-dir")
 		_ = flags.MarkHidden(signByFlagName)
+		_ = flags.MarkHidden(signBySigstorePrivateKeyFlagName)
+		_ = flags.MarkHidden(signPassphraseFileFlagName)
 	}
 }
 
@@ -104,6 +115,10 @@ func push(cmd *cobra.Command, args []string) error {
 		manifestPushOpts.Password = creds.Password
 	}
 
+	if err := common.PrepareSigningPassphrase(&manifestPushOpts.ImagePushOptions, manifestPushOpts.SignPassphraseFileCLI); err != nil {
+		return err
+	}
+
 	// TLS verification in c/image is controlled via a `types.OptionalBool`
 	// which allows for distinguishing among set-true, set-false, unspecified
 	// which is important to implement a sane way of dealing with defaults of
diff --git a/docs/source/markdown/podman-manifest-push.1.md b/docs/source/markdown/podman-manifest-push.1.md
index 22e8cae9a..66cdb8324 100644
--- a/docs/source/markdown/podman-manifest-push.1.md
+++ b/docs/source/markdown/podman-manifest-push.1.md
@@ -60,7 +60,15 @@ Delete the manifest list or image index from local storage if pushing succeeds.
 
 #### **--sign-by**=*fingerprint*
 
-Sign the pushed images using the GPG key that matches the specified fingerprint.
+Sign the pushed images with a “simple signing” signature using the specified key. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines)
+
+#### **--sign-by-sigstore-private-key**=*path*
+
+Sign the pushed images with a sigstore signature using a private key at the specified path. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines)
+
+#### **--sign-passphrase-file**=*path*
+
+If signing the image (using either **--sign-by** or **--sign-by-sigstore-private-key**), read the passphrase to use from the specified path.
 
 #### **--tls-verify**
 
diff --git a/docs/source/markdown/podman-push.1.md b/docs/source/markdown/podman-push.1.md
index 3cda982ac..a69bdce0a 100644
--- a/docs/source/markdown/podman-push.1.md
+++ b/docs/source/markdown/podman-push.1.md
@@ -99,7 +99,15 @@ Discard any pre-existing signatures in the image.
 
 #### **--sign-by**=*key*
 
-Add a signature at the destination using the specified key. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines)
+Add a “simple signing” signature at the destination using the specified key. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines)
+
+#### **--sign-by-sigstore-private-key**=*path*
+
+Add a sigstore signature at the destination using a private key at the specified path. (This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines)
+
+#### **--sign-passphrase-file**=*path*
+
+If signing the image (using either **--sign-by** or **--sign-by-sigstore-private-key**), read the passphrase to use from the specified path.
 
 #### **--tls-verify**
 
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 {
diff --git a/test/e2e/push_test.go b/test/e2e/push_test.go
index 0faa040f4..898d21d00 100644
--- a/test/e2e/push_test.go
+++ b/test/e2e/push_test.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"strings"
 
@@ -136,6 +137,45 @@ var _ = Describe("Podman push", func() {
 			Expect(fi.Name()).To(Equal("digestfile.txt"))
 			Expect(push2).Should(Exit(0))
 		}
+
+		if !IsRemote() { // Remote does not support signing
+			By("pushing and pulling with sigstore signatures")
+			// Ideally, this should set SystemContext.RegistriesDirPath, but Podman currently doesn’t
+			// expose that as an option. So, for now, modify /etc/directly, and skip testing sigstore if
+			// we don’t have permission to do so.
+			systemRegistriesDAddition := "/etc/containers/registries.d/podman-test-only-temporary-addition.yaml"
+			cmd := exec.Command("cp", "testdata/sigstore-registries.d-fragment.yaml", systemRegistriesDAddition)
+			output, err := cmd.CombinedOutput()
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "Skipping sigstore tests because /etc/containers/registries.d isn’t writable: %s", string(output))
+			} else {
+				defer func() {
+					err := os.Remove(systemRegistriesDAddition)
+					Expect(err).ToNot(HaveOccurred())
+				}()
+
+				// Verify that the policy rejects unsigned images
+				push := podmanTest.Podman([]string{"push", "-q", "--tls-verify=false", "--remove-signatures", ALPINE, "localhost:5000/sigstore-signed"})
+				push.WaitWithDefaultTimeout()
+				Expect(push).Should(Exit(0))
+				Expect(len(push.ErrorToString())).To(Equal(0))
+
+				pull := podmanTest.Podman([]string{"pull", "-q", "--tls-verify=false", "--signature-policy", "sign/policy.json", "localhost:5000/sigstore-signed"})
+				pull.WaitWithDefaultTimeout()
+				Expect(pull).To(ExitWithError())
+				Expect(pull.ErrorToString()).To(ContainSubstring("A signature was required, but no signature exists"))
+
+				// Sign an image, and verify it is accepted.
+				push = podmanTest.Podman([]string{"push", "-q", "--tls-verify=false", "--remove-signatures", "--sign-by-sigstore-private-key", "testdata/sigstore-key.key", "--sign-passphrase-file", "testdata/sigstore-key.key.pass", ALPINE, "localhost:5000/sigstore-signed"})
+				push.WaitWithDefaultTimeout()
+				Expect(push).Should(Exit(0))
+				Expect(len(push.ErrorToString())).To(Equal(0))
+
+				pull = podmanTest.Podman([]string{"pull", "-q", "--tls-verify=false", "--signature-policy", "sign/policy.json", "localhost:5000/sigstore-signed"})
+				pull.WaitWithDefaultTimeout()
+				Expect(pull).Should(Exit(0))
+			}
+		}
 	})
 
 	It("podman push to local registry with authorization", func() {
diff --git a/test/e2e/sign/policy.json b/test/e2e/sign/policy.json
index ab01137bf..812c14989 100644
--- a/test/e2e/sign/policy.json
+++ b/test/e2e/sign/policy.json
@@ -12,6 +12,12 @@
                     "keyType": "GPGKeys",
                     "keyPath": "/tmp/key.gpg"
                 }
+            ],
+            "localhost:5000/sigstore-signed": [
+                {
+                    "type": "sigstoreSigned",
+                    "keyPath": "testdata/sigstore-key.pub"
+                }
             ]
         }
     }
diff --git a/test/e2e/testdata/sigstore-key.key b/test/e2e/testdata/sigstore-key.key
new file mode 100644
index 000000000..c4eed76a8
--- /dev/null
+++ b/test/e2e/testdata/sigstore-key.key
@@ -0,0 +1,11 @@
+-----BEGIN ENCRYPTED COSIGN PRIVATE KEY-----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+-----END ENCRYPTED COSIGN PRIVATE KEY-----
diff --git a/test/e2e/testdata/sigstore-key.key.pass b/test/e2e/testdata/sigstore-key.key.pass
new file mode 100644
index 000000000..beb5c7687
--- /dev/null
+++ b/test/e2e/testdata/sigstore-key.key.pass
@@ -0,0 +1 @@
+sigstore pass
diff --git a/test/e2e/testdata/sigstore-key.pub b/test/e2e/testdata/sigstore-key.pub
new file mode 100644
index 000000000..1f470f72b
--- /dev/null
+++ b/test/e2e/testdata/sigstore-key.pub
@@ -0,0 +1,4 @@
+-----BEGIN PUBLIC KEY-----
+MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEX/AWbBiFPuAU5+ys+Ce8YFPhTr1a
+nM7A8h6NrQi6w8w8/4dJCzlGH4SN+P93nopATs6jDXs4Lpc2/tiA1SBmzA==
+-----END PUBLIC KEY-----
diff --git a/test/e2e/testdata/sigstore-registries.d-fragment.yaml b/test/e2e/testdata/sigstore-registries.d-fragment.yaml
new file mode 100644
index 000000000..d79f4c935
--- /dev/null
+++ b/test/e2e/testdata/sigstore-registries.d-fragment.yaml
@@ -0,0 +1,3 @@
+docker:
+  localhost:5000/sigstore-signed:
+    use-sigstore-attachments: true
diff --git a/vendor/github.com/containers/image/v5/pkg/cli/passphrase.go b/vendor/github.com/containers/image/v5/pkg/cli/passphrase.go
new file mode 100644
index 000000000..c46650cdc
--- /dev/null
+++ b/vendor/github.com/containers/image/v5/pkg/cli/passphrase.go
@@ -0,0 +1,36 @@
+package cli
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	"github.com/sirupsen/logrus"
+)
+
+// ReadPassphraseFile returns the first line of the specified path.
+// For convenience, an empty string is returned if the path is empty.
+func ReadPassphraseFile(path string) (string, error) {
+	if path == "" {
+		return "", nil
+	}
+
+	logrus.Debugf("Reading user-specified passphrase for signing from %s", path)
+
+	ppf, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer ppf.Close()
+
+	// Read the *first* line in the passphrase file, just as gpg(1) does.
+	buf, err := bufio.NewReader(ppf).ReadBytes('\n')
+	if err != nil && !errors.Is(err, io.EOF) {
+		return "", fmt.Errorf("reading passphrase file: %w", err)
+	}
+
+	return strings.TrimSuffix(string(buf), "\n"), nil
+}
diff --git a/vendor/modules.txt b/vendor/modules.txt
index 2330107ab..8d23648f0 100644
--- a/vendor/modules.txt
+++ b/vendor/modules.txt
@@ -210,6 +210,7 @@ github.com/containers/image/v5/pkg/blobinfocache/boltdb
 github.com/containers/image/v5/pkg/blobinfocache/internal/prioritize
 github.com/containers/image/v5/pkg/blobinfocache/memory
 github.com/containers/image/v5/pkg/blobinfocache/none
+github.com/containers/image/v5/pkg/cli
 github.com/containers/image/v5/pkg/compression
 github.com/containers/image/v5/pkg/compression/internal
 github.com/containers/image/v5/pkg/compression/types