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moby--moby/graph/manifest.go

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package graph
import (
"encoding/json"
"fmt"
"github.com/Sirupsen/logrus"
"github.com/docker/distribution/digest"
"github.com/docker/docker/registry"
"github.com/docker/docker/trust"
"github.com/docker/libtrust"
)
// loadManifest loads a manifest from a byte array and verifies its content,
// returning the local digest, the manifest itself, whether or not it was
// verified. If ref is a digest, rather than a tag, this will be treated as
// the local digest. An error will be returned if the signature verification
// fails, local digest verification fails and, if provided, the remote digest
// verification fails. The boolean return will only be false without error on
// the failure of signatures trust check.
func (s *TagStore) loadManifest(manifestBytes []byte, ref string, remoteDigest digest.Digest) (digest.Digest, *registry.ManifestData, bool, error) {
payload, keys, err := unpackSignedManifest(manifestBytes)
if err != nil {
return "", nil, false, fmt.Errorf("error unpacking manifest: %v", err)
}
// TODO(stevvooe): It would be a lot better here to build up a stack of
// verifiers, then push the bytes one time for signatures and digests, but
// the manifests are typically small, so this optimization is not worth
// hacking this code without further refactoring.
var localDigest digest.Digest
// Verify the local digest, if present in ref. ParseDigest will validate
// that the ref is a digest and verify against that if present. Otherwize
// (on error), we simply compute the localDigest and proceed.
if dgst, err := digest.ParseDigest(ref); err == nil {
// verify the manifest against local ref
if err := verifyDigest(dgst, payload); err != nil {
return "", nil, false, fmt.Errorf("verifying local digest: %v", err)
}
localDigest = dgst
} else {
// We don't have a local digest, since we are working from a tag.
// Compute the digest of the payload and return that.
logrus.Debugf("provided manifest reference %q is not a digest: %v", ref, err)
localDigest, err = digest.FromBytes(payload)
if err != nil {
// near impossible
logrus.Errorf("error calculating local digest during tag pull: %v", err)
return "", nil, false, err
}
}
// verify against the remote digest, if available
if remoteDigest != "" {
if err := verifyDigest(remoteDigest, payload); err != nil {
return "", nil, false, fmt.Errorf("verifying remote digest: %v", err)
}
}
var manifest registry.ManifestData
if err := json.Unmarshal(payload, &manifest); err != nil {
return "", nil, false, fmt.Errorf("error unmarshalling manifest: %s", err)
}
// validate the contents of the manifest
if err := validateManifest(&manifest); err != nil {
return "", nil, false, err
}
var verified bool
verified, err = s.verifyTrustedKeys(manifest.Name, keys)
if err != nil {
return "", nil, false, fmt.Errorf("error verifying trusted keys: %v", err)
}
return localDigest, &manifest, verified, nil
}
// unpackSignedManifest takes the raw, signed manifest bytes, unpacks the jws
// and returns the payload and public keys used to signed the manifest.
// Signatures are verified for authenticity but not against the trust store.
func unpackSignedManifest(p []byte) ([]byte, []libtrust.PublicKey, error) {
sig, err := libtrust.ParsePrettySignature(p, "signatures")
if err != nil {
return nil, nil, fmt.Errorf("error parsing payload: %s", err)
}
keys, err := sig.Verify()
if err != nil {
return nil, nil, fmt.Errorf("error verifying payload: %s", err)
}
payload, err := sig.Payload()
if err != nil {
return nil, nil, fmt.Errorf("error retrieving payload: %s", err)
}
return payload, keys, nil
}
// verifyTrustedKeys checks the keys provided against the trust store,
// ensuring that the provided keys are trusted for the namespace. The keys
// provided from this method must come from the signatures provided as part of
// the manifest JWS package, obtained from unpackSignedManifest or libtrust.
func (s *TagStore) verifyTrustedKeys(namespace string, keys []libtrust.PublicKey) (verified bool, err error) {
if namespace[0] != '/' {
namespace = "/" + namespace
}
for _, key := range keys {
b, err := key.MarshalJSON()
if err != nil {
return false, fmt.Errorf("error marshalling public key: %s", err)
}
// Check key has read/write permission (0x03)
v, err := s.trustService.CheckKey(namespace, b, 0x03)
if err != nil {
vErr, ok := err.(trust.NotVerifiedError)
if !ok {
return false, fmt.Errorf("error running key check: %s", err)
}
logrus.Debugf("Key check result: %v", vErr)
}
verified = v
}
if verified {
logrus.Debug("Key check result: verified")
}
return
}
// verifyDigest checks the contents of p against the provided digest. Note
// that for manifests, this is the signed payload and not the raw bytes with
// signatures.
func verifyDigest(dgst digest.Digest, p []byte) error {
if err := dgst.Validate(); err != nil {
return fmt.Errorf("error validating digest %q: %v", dgst, err)
}
verifier, err := digest.NewDigestVerifier(dgst)
if err != nil {
// There are not many ways this can go wrong: if it does, its
// fatal. Likley, the cause would be poor validation of the
// incoming reference.
return fmt.Errorf("error creating verifier for digest %q: %v", dgst, err)
}
if _, err := verifier.Write(p); err != nil {
return fmt.Errorf("error writing payload to digest verifier (verifier target %q): %v", dgst, err)
}
if !verifier.Verified() {
return fmt.Errorf("verification against digest %q failed", dgst)
}
return nil
}
func validateManifest(manifest *registry.ManifestData) error {
if manifest.SchemaVersion != 1 {
return fmt.Errorf("unsupported schema version: %d", manifest.SchemaVersion)
}
if len(manifest.FSLayers) != len(manifest.History) {
return fmt.Errorf("length of history not equal to number of layers")
}
if len(manifest.FSLayers) == 0 {
return fmt.Errorf("no FSLayers in manifest")
}
return nil
}