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package main
import (
"io/ioutil"
"net/url"
"os"
"path/filepath"
"strconv"
"strings"
"github.com/containers/image/signature"
"github.com/containers/image/transports"
"github.com/containers/image/transports/alltransports"
"github.com/containers/libpod/cmd/podman/libpodruntime"
"github.com/containers/libpod/libpod/image"
"github.com/containers/libpod/pkg/trust"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"github.com/urfave/cli"
)
var (
signFlags = []cli.Flag{
cli.StringFlag{
Name: "sign-by",
Usage: "Name of the signing key",
},
cli.StringFlag{
Name: "directory, d",
Usage: "Define an alternate directory to store signatures",
},
}
signDescription = "Create a signature file that can be used later to verify the image"
signCommand = cli.Command{
Name: "sign",
Usage: "Sign an image",
Description: signDescription,
Flags: sortFlags(signFlags),
Action: signCmd,
ArgsUsage: "IMAGE-NAME [IMAGE-NAME ...]",
OnUsageError: usageErrorHandler,
}
)
// SignatureStoreDir defines default directory to store signatures
const SignatureStoreDir = "/var/lib/containers/sigstore"
func signCmd(c *cli.Context) error {
args := c.Args()
if len(args) < 1 {
return errors.Errorf("at least one image name must be specified")
}
runtime, err := libpodruntime.GetRuntime(c)
if err != nil {
return errors.Wrapf(err, "could not create runtime")
}
defer runtime.Shutdown(false)
signby := c.String("sign-by")
if signby == "" {
return errors.Errorf("please provide an identity")
}
var sigStoreDir string
if c.IsSet("directory") {
sigStoreDir = c.String("directory")
if _, err := os.Stat(sigStoreDir); err != nil {
return errors.Wrapf(err, "invalid directory %s", sigStoreDir)
}
}
mech, err := signature.NewGPGSigningMechanism()
if err != nil {
return errors.Wrap(err, "error initializing GPG")
}
defer mech.Close()
if err := mech.SupportsSigning(); err != nil {
return errors.Wrap(err, "signing is not supported")
}
systemRegistriesDirPath := trust.RegistriesDirPath(runtime.SystemContext())
registryConfigs, err := trust.LoadAndMergeConfig(systemRegistriesDirPath)
if err != nil {
return errors.Wrapf(err, "error reading registry configuration")
}
for _, signimage := range args {
srcRef, err := alltransports.ParseImageName(signimage)
if err != nil {
return errors.Wrapf(err, "error parsing image name")
}
rawSource, err := srcRef.NewImageSource(getContext(), runtime.SystemContext())
if err != nil {
return errors.Wrapf(err, "error getting image source")
}
manifest, _, err := rawSource.GetManifest(getContext(), nil)
if err != nil {
return errors.Wrapf(err, "error getting manifest")
}
dockerReference := rawSource.Reference().DockerReference()
if dockerReference == nil {
return errors.Errorf("cannot determine canonical Docker reference for destination %s", transports.ImageName(rawSource.Reference()))
}
// create the signstore file
newImage, err := runtime.ImageRuntime().New(getContext(), signimage, runtime.GetConfig().SignaturePolicyPath, "", os.Stderr, nil, image.SigningOptions{SignBy: signby}, false)
if err != nil {
return errors.Wrapf(err, "error pulling image %s", signimage)
}
registryInfo := trust.HaveMatchRegistry(rawSource.Reference().DockerReference().String(), registryConfigs)
if registryInfo != nil {
if sigStoreDir == "" {
sigStoreDir = registryInfo.SigStoreStaging
if sigStoreDir == "" {
sigStoreDir = registryInfo.SigStore
}
}
sigStoreDir, err = isValidSigStoreDir(sigStoreDir)
if err != nil {
return errors.Wrapf(err, "invalid signature storage %s", sigStoreDir)
}
}
if sigStoreDir == "" {
sigStoreDir = SignatureStoreDir
}
repos, err := newImage.RepoDigests()
if err != nil {
return errors.Wrapf(err, "error calculating repo digests for %s", signimage)
}
if len(repos) == 0 {
logrus.Errorf("no repodigests associated with the image %s", signimage)
continue
}
// create signature
newSig, err := signature.SignDockerManifest(manifest, dockerReference.String(), mech, signby)
if err != nil {
return errors.Wrapf(err, "error creating new signature")
}
trimmedDigest := strings.TrimPrefix(repos[0], strings.Split(repos[0], "/")[0])
sigStoreDir = filepath.Join(sigStoreDir, strings.Replace(trimmedDigest, ":", "=", 1))
if err := os.MkdirAll(sigStoreDir, 0751); err != nil {
// The directory is allowed to exist
if !os.IsExist(err) {
logrus.Errorf("error creating directory %s: %s", sigStoreDir, err)
continue
}
}
sigFilename, err := getSigFilename(sigStoreDir)
if err != nil {
logrus.Errorf("error creating sigstore file: %v", err)
continue
}
err = ioutil.WriteFile(filepath.Join(sigStoreDir, sigFilename), newSig, 0644)
if err != nil {
logrus.Errorf("error storing signature for %s", rawSource.Reference().DockerReference().String())
continue
}
}
return nil
}
func getSigFilename(sigStoreDirPath string) (string, error) {
sigFileSuffix := 1
sigFiles, err := ioutil.ReadDir(sigStoreDirPath)
if err != nil {
return "", err
}
sigFilenames := make(map[string]bool)
for _, file := range sigFiles {
sigFilenames[file.Name()] = true
}
for {
sigFilename := "signature-" + strconv.Itoa(sigFileSuffix)
if _, exists := sigFilenames[sigFilename]; !exists {
return sigFilename, nil
}
sigFileSuffix++
}
}
func isValidSigStoreDir(sigStoreDir string) (string, error) {
writeURIs := map[string]bool{"file": true}
url, err := url.Parse(sigStoreDir)
if err != nil {
return sigStoreDir, errors.Wrapf(err, "invalid directory %s", sigStoreDir)
}
_, exists := writeURIs[url.Scheme]
if !exists {
return sigStoreDir, errors.Errorf("writing to %s is not supported. Use a supported scheme", sigStoreDir)
}
sigStoreDir = url.Path
return sigStoreDir, nil
}
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