From 21d44071702e20b1d868fc3482bb29e1198456f3 Mon Sep 17 00:00:00 2001 From: Thomas Waldmann Date: Mon, 12 Jun 2023 23:49:53 +0200 Subject: [PATCH] always implicitly require manifest TAMs remove a lot of complexity from the code that was just there to support legacy borg versions < 1.0.9 which did not TAM authenticate the manifest. since then, borg writes TAM authentication to the manifest, even if the repo is unencrypted. if the repo is unencrypted, it did not check the somehow pointless authentication that was generated without any secret, but if we add that fake TAM, we can also verify the fake TAM. if somebody explicitly switches off all crypto, they can not expect authentication. for everybody else, borg now always generates the TAM and also verifies it. --- src/borg/archiver/key_cmds.py | 2 +- src/borg/archiver/rcreate_cmd.py | 6 +---- src/borg/crypto/key.py | 43 +++++--------------------------- src/borg/item.pyx | 3 +-- src/borg/manifest.py | 25 +++---------------- src/borg/testsuite/key.py | 35 ++++++-------------------- 6 files changed, 19 insertions(+), 95 deletions(-) diff --git a/src/borg/archiver/key_cmds.py b/src/borg/archiver/key_cmds.py index a365848f..bdc93a55 100644 --- a/src/borg/archiver/key_cmds.py +++ b/src/borg/archiver/key_cmds.py @@ -63,7 +63,7 @@ class KeysMixIn: print("Change not needed or not supported.") return EXIT_WARNING - for name in ("repository_id", "crypt_key", "id_key", "chunk_seed", "tam_required", "sessionid", "cipher"): + for name in ("repository_id", "crypt_key", "id_key", "chunk_seed", "sessionid", "cipher"): value = getattr(key, name) setattr(key_new, name, value) diff --git a/src/borg/archiver/rcreate_cmd.py b/src/borg/archiver/rcreate_cmd.py index 8fce7dbb..e6545a03 100644 --- a/src/borg/archiver/rcreate_cmd.py +++ b/src/borg/archiver/rcreate_cmd.py @@ -3,7 +3,7 @@ import argparse from ._common import with_repository, with_other_repository, Highlander from ..cache import Cache from ..constants import * # NOQA -from ..crypto.key import key_creator, key_argument_names, tam_required_file +from ..crypto.key import key_creator, key_argument_names from ..helpers import EXIT_WARNING from ..helpers import location_validator, Location from ..helpers import parse_storage_quota @@ -35,10 +35,6 @@ class RCreateMixIn: repository.commit(compact=False) with Cache(repository, manifest, warn_if_unencrypted=False): pass - if key.tam_required: - tam_file = tam_required_file(repository) - open(tam_file, "w").close() - if key.NAME != "plaintext": logger.warning( "\n" diff --git a/src/borg/crypto/key.py b/src/borg/crypto/key.py index 3fb4818a..d6d6b32e 100644 --- a/src/borg/crypto/key.py +++ b/src/borg/crypto/key.py @@ -136,16 +136,6 @@ def key_factory(repository, manifest_chunk, *, ro_cls=RepoObj): return identify_key(manifest_data).detect(repository, manifest_data) -def tam_required_file(repository): - security_dir = get_security_dir(bin_to_hex(repository.id), legacy=(repository.version == 1)) - return os.path.join(security_dir, "tam_required") - - -def tam_required(repository): - file = tam_required_file(repository) - return os.path.isfile(file) - - def uses_same_chunker_secret(other_key, key): """is the chunker secret the same?""" # avoid breaking the deduplication by a different chunker secret @@ -211,7 +201,6 @@ class KeyBase: self.TYPE_STR = bytes([self.TYPE]) self.repository = repository self.target = None # key location file path / repo obj - self.tam_required = True self.copy_crypt_key = False def id_hash(self, data): @@ -253,39 +242,25 @@ class KeyBase: tam["hmac"] = hmac.digest(tam_key, packed, "sha512") return msgpack.packb(metadata_dict) - def unpack_and_verify_manifest(self, data, force_tam_not_required=False): - """Unpack msgpacked *data* and return (object, did_verify).""" + def unpack_and_verify_manifest(self, data): + """Unpack msgpacked *data* and return manifest.""" if data.startswith(b"\xc1" * 4): # This is a manifest from the future, we can't read it. raise UnsupportedManifestError() - tam_required = self.tam_required - if force_tam_not_required and tam_required: - logger.warning("Manifest authentication DISABLED.") - tam_required = False data = bytearray(data) unpacker = get_limited_unpacker("manifest") unpacker.feed(data) unpacked = unpacker.unpack() if AUTHENTICATED_NO_KEY: - return unpacked, True # True is a lie. + return unpacked if "tam" not in unpacked: - if tam_required: - raise TAMRequiredError(self.repository._location.canonical_path()) - else: - logger.debug("Manifest TAM not found and not required") - return unpacked, False + raise TAMRequiredError(self.repository._location.canonical_path()) tam = unpacked.pop("tam", None) if not isinstance(tam, dict): raise TAMInvalid() tam_type = tam.get("type", "") if tam_type != "HKDF_HMAC_SHA512": - if tam_required: - raise TAMUnsupportedSuiteError(repr(tam_type)) - else: - logger.debug( - "Ignoring manifest TAM made with unsupported suite, since TAM is not required: %r", tam_type - ) - return unpacked, False + raise TAMUnsupportedSuiteError(repr(tam_type)) tam_hmac = tam.get("hmac") tam_salt = tam.get("salt") if not isinstance(tam_salt, (bytes, str)) or not isinstance(tam_hmac, (bytes, str)): @@ -299,7 +274,7 @@ class KeyBase: if not hmac.compare_digest(calculated_hmac, tam_hmac): raise TAMInvalid() logger.debug("TAM-verified manifest") - return unpacked, True + return unpacked def unpack_and_verify_archive(self, data, force_tam_not_required=False): """Unpack msgpacked *data* and return (object, did_verify).""" @@ -357,10 +332,6 @@ class PlaintextKey(KeyBase): chunk_seed = 0 logically_encrypted = False - def __init__(self, repository): - super().__init__(repository) - self.tam_required = False - @classmethod def create(cls, repository, args, **kw): logger.info('Encryption NOT enabled.\nUse the "--encryption=repokey|keyfile" to enable encryption.') @@ -526,7 +497,6 @@ class FlexiKey: self.crypt_key = key.crypt_key self.id_key = key.id_key self.chunk_seed = key.chunk_seed - self.tam_required = key.get("tam_required", tam_required(self.repository)) return True return False @@ -639,7 +609,6 @@ class FlexiKey: crypt_key=self.crypt_key, id_key=self.id_key, chunk_seed=self.chunk_seed, - tam_required=self.tam_required, ) data = self.encrypt_key_file(msgpack.packb(key.as_dict()), passphrase, algorithm) key_data = "\n".join(textwrap.wrap(b2a_base64(data).decode("ascii"))) diff --git a/src/borg/item.pyx b/src/borg/item.pyx index 5da91c2e..04dd884f 100644 --- a/src/borg/item.pyx +++ b/src/borg/item.pyx @@ -467,7 +467,7 @@ cdef class Key(PropDict): crypt_key = PropDictProperty(bytes) id_key = PropDictProperty(bytes) chunk_seed = PropDictProperty(int) - tam_required = PropDictProperty(bool) + tam_required = PropDictProperty(bool) # legacy. borg now implicitly always requires TAM. def update_internal(self, d): # legacy support for migration (data from old msgpacks comes in as bytes always, but sometimes we want str) @@ -650,7 +650,6 @@ class ItemDiff: self._can_compare_chunk_ids = can_compare_chunk_ids self._chunk_1 = chunk_1 self._chunk_2 = chunk_2 - self._changes = {} if self._item1.is_link() or self._item2.is_link(): diff --git a/src/borg/manifest.py b/src/borg/manifest.py index 592b5319..0768ce44 100644 --- a/src/borg/manifest.py +++ b/src/borg/manifest.py @@ -1,6 +1,4 @@ import enum -import os -import os.path import re from collections import abc, namedtuple from datetime import datetime, timedelta, timezone @@ -229,7 +227,6 @@ class Manifest: self.repo_objs = ro_cls(key) self.repository = repository self.item_keys = frozenset(item_keys) if item_keys is not None else ITEM_KEYS - self.tam_verified = False self.timestamp = None @property @@ -241,9 +238,9 @@ class Manifest: return parse_timestamp(self.timestamp) @classmethod - def load(cls, repository, operations, key=None, force_tam_not_required=False, *, ro_cls=RepoObj): + def load(cls, repository, operations, key=None, *, ro_cls=RepoObj): from .item import ManifestItem - from .crypto.key import key_factory, tam_required_file, tam_required + from .crypto.key import key_factory from .repository import Repository try: @@ -254,9 +251,7 @@ class Manifest: key = key_factory(repository, cdata, ro_cls=ro_cls) manifest = cls(key, repository, ro_cls=ro_cls) _, data = manifest.repo_objs.parse(cls.MANIFEST_ID, cdata) - manifest_dict, manifest.tam_verified = key.unpack_and_verify_manifest( - data, force_tam_not_required=force_tam_not_required - ) + manifest_dict = key.unpack_and_verify_manifest(data) m = ManifestItem(internal_dict=manifest_dict) manifest.id = manifest.repo_objs.id_hash(data) if m.get("version") not in (1, 2): @@ -268,17 +263,6 @@ class Manifest: manifest.item_keys = ITEM_KEYS manifest.item_keys |= frozenset(m.config.get("item_keys", [])) # new location of item_keys since borg2 manifest.item_keys |= frozenset(m.get("item_keys", [])) # legacy: borg 1.x: item_keys not in config yet - - if manifest.tam_verified: - manifest_required = manifest.config.get("tam_required", False) - security_required = tam_required(repository) - if manifest_required and not security_required: - logger.debug("Manifest is TAM verified and says TAM is required, updating security database...") - file = tam_required_file(repository) - open(file, "w").close() - if not manifest_required and security_required: - logger.debug("Manifest is TAM verified and says TAM is *not* required, updating security database...") - os.unlink(tam_required_file(repository)) manifest.check_repository_compatibility(operations) return manifest @@ -310,8 +294,6 @@ class Manifest: def write(self): from .item import ManifestItem - if self.key.tam_required: - self.config["tam_required"] = True # self.timestamp needs to be strictly monotonically increasing. Clocks often are not set correctly if self.timestamp is None: self.timestamp = datetime.now(tz=timezone.utc).isoformat(timespec="microseconds") @@ -331,7 +313,6 @@ class Manifest: timestamp=self.timestamp, config=StableDict(self.config), ) - self.tam_verified = True data = self.key.pack_and_authenticate_metadata(manifest.as_dict()) self.id = self.repo_objs.id_hash(data) self.repository.put(self.MANIFEST_ID, self.repo_objs.format(self.MANIFEST_ID, {}, data)) diff --git a/src/borg/testsuite/key.py b/src/borg/testsuite/key.py index 73d9df35..a8fd3768 100644 --- a/src/borg/testsuite/key.py +++ b/src/borg/testsuite/key.py @@ -272,39 +272,19 @@ class TestTAM: with pytest.raises(msgpack.UnpackException): key.unpack_and_verify_manifest(blob) - def test_missing_when_required(self, key): - blob = msgpack.packb({}) - with pytest.raises(TAMRequiredError): - key.unpack_and_verify_manifest(blob) - with pytest.raises(TAMRequiredError): - key.unpack_and_verify_archive(blob) - def test_missing(self, key): blob = msgpack.packb({}) - key.tam_required = False - unpacked, verified = key.unpack_and_verify_manifest(blob) - assert unpacked == {} - assert not verified - unpacked, verified, _ = key.unpack_and_verify_archive(blob) - assert unpacked == {} - assert not verified - - def test_unknown_type_when_required(self, key): - blob = msgpack.packb({"tam": {"type": "HMAC_VOLLBIT"}}) - with pytest.raises(TAMUnsupportedSuiteError): + with pytest.raises(TAMRequiredError): key.unpack_and_verify_manifest(blob) - with pytest.raises(TAMUnsupportedSuiteError): + with pytest.raises(TAMRequiredError): key.unpack_and_verify_archive(blob) def test_unknown_type(self, key): blob = msgpack.packb({"tam": {"type": "HMAC_VOLLBIT"}}) - key.tam_required = False - unpacked, verified = key.unpack_and_verify_manifest(blob) - assert unpacked == {} - assert not verified - unpacked, verified, _ = key.unpack_and_verify_archive(blob) - assert unpacked == {} - assert not verified + with pytest.raises(TAMUnsupportedSuiteError): + key.unpack_and_verify_manifest(blob) + with pytest.raises(TAMUnsupportedSuiteError): + key.unpack_and_verify_archive(blob) @pytest.mark.parametrize( "tam, exc", @@ -360,8 +340,7 @@ class TestTAM: unpacked = msgpack.unpackb(blob) assert unpacked["tam"]["type"] == "HKDF_HMAC_SHA512" - unpacked, verified = key.unpack_and_verify_manifest(blob) - assert verified + unpacked = key.unpack_and_verify_manifest(blob) assert unpacked["foo"] == "bar" assert "tam" not in unpacked