Esempio n. 1
0
func validateSnapshot(role string, oldSnap *data.SignedSnapshot, snapUpdate storage.MetaUpdate, roles map[string]storage.MetaUpdate, kdb *keys.KeyDB) error {
	s := &data.Signed{}
	err := json.Unmarshal(snapUpdate.Data, s)
	if err != nil {
		return errors.New("could not parse snapshot")
	}
	// version specifically gets validated when writing to store to
	// better handle race conditions there.
	if err := signed.Verify(s, role, 0, kdb); err != nil {
		return err
	}

	snap, err := data.SnapshotFromSigned(s)
	if err != nil {
		return errors.New("could not parse snapshot")
	}
	if !data.ValidTUFType(snap.Signed.Type, data.CanonicalSnapshotRole) {
		return errors.New("snapshot has wrong type")
	}
	err = checkSnapshotEntries(role, oldSnap, snap, roles)
	if err != nil {
		return err
	}
	return nil
}
Esempio n. 2
0
// SetSnapshot parses the Signed object into a SignedSnapshots object
// and sets the TufRepo.Snapshot field.
func (tr *TufRepo) SetSnapshot(s *data.Signed) error {
	snap, err := data.SnapshotFromSigned(s)
	if err != nil {
		return err
	}

	tr.Snapshot = snap
	return nil
}
Esempio n. 3
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func TestValidateTargetsModifiedHash(t *testing.T) {
	_, repo, _ := testutils.EmptyRepo()
	store := storage.NewMemStorage()

	r, tg, sn, ts, err := testutils.Sign(repo)
	assert.NoError(t, err)

	snap, err := data.SnapshotFromSigned(sn)
	assert.NoError(t, err)
	snap.Signed.Meta["targets"].Hashes["sha256"][0] = snap.Signed.Meta["targets"].Hashes["sha256"][0] ^ 0xff

	sn, err = snap.ToSigned()
	assert.NoError(t, err)

	root, targets, snapshot, timestamp, err := testutils.Serialize(r, tg, sn, ts)
	assert.NoError(t, err)

	updates := []storage.MetaUpdate{
		{
			Role:    "root",
			Version: 1,
			Data:    root,
		},
		{
			Role:    "targets",
			Version: 1,
			Data:    targets,
		},
		{
			Role:    "snapshot",
			Version: 1,
			Data:    snapshot,
		},
		{
			Role:    "timestamp",
			Version: 1,
			Data:    timestamp,
		},
	}

	err = validateUpdate("testGUN", updates, store)
	assert.Error(t, err)
	assert.IsType(t, ErrBadSnapshot{}, err)
}
Esempio n. 4
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// downloadSnapshot is responsible for downloading the snapshot.json
func (c *Client) downloadSnapshot() error {
	logrus.Debug("downloadSnapshot")
	role := data.RoleName("snapshot")
	if c.local.Timestamp == nil {
		return ErrMissingMeta{role: "snapshot"}
	}
	size := c.local.Timestamp.Signed.Meta[role].Length
	expectedSha256, ok := c.local.Timestamp.Signed.Meta[role].Hashes["sha256"]
	if !ok {
		return ErrMissingMeta{role: "snapshot"}
	}

	var download bool
	old := &data.Signed{}
	version := 0
	raw, err := c.cache.GetMeta(role, size)
	if raw == nil || err != nil {
		logrus.Debug("no snapshot in cache, must download")
		download = true
	} else {
		// file may have been tampered with on disk. Always check the hash!
		genHash := sha256.Sum256(raw)
		if !bytes.Equal(genHash[:], expectedSha256) {
			logrus.Debug("hash of snapshot in cache did not match expected hash, must download")
			download = true
		}
		err := json.Unmarshal(raw, old)
		if err == nil {
			snap, err := data.TimestampFromSigned(old)
			if err == nil {
				version = snap.Signed.Version
			} else {
				logrus.Debug("Could not parse Signed part of snapshot, must download")
				download = true
			}
		} else {
			logrus.Debug("Could not parse snapshot, must download")
			download = true
		}
	}
	var s *data.Signed
	if download {
		raw, s, err = c.downloadSigned(role, size, expectedSha256)
		if err != nil {
			return err
		}
	} else {
		logrus.Debug("using cached snapshot")
		s = old
	}

	err = signed.Verify(s, role, version, c.keysDB)
	if err != nil {
		return err
	}
	logrus.Debug("successfully verified snapshot")
	snap, err := data.SnapshotFromSigned(s)
	if err != nil {
		return err
	}
	c.local.SetSnapshot(snap)
	if download {
		err = c.cache.SetMeta(role, raw)
		if err != nil {
			logrus.Errorf("Failed to write snapshot to local cache: %s", err.Error())
		}
	}
	return nil
}