list: support {tam} placeholder. check archive TAM.

list: shows either "verified" or "none", depending on
whether a TAM auth tag could be verified or was
missing (old archives from borg < 1.0.9).

when loading an archive, we now try to verify the archive
TAM, but we do not require it. people might still have
old archives in their repos and we want to be able to
list such repos without fatal exceptions.

src/borg/archive.py

@@ -336,6 +336,7 @@ class Archive:
         self.name = name  # overwritten later with name from archive metadata
         self.name_in_manifest = name  # can differ from .name later (if borg check fixed duplicate archive names)
         self.comment = None
+        self.tam_verified = False
         self.checkpoint_interval = checkpoint_interval
         self.numeric_owner = numeric_owner
         self.noatime = noatime
@@ -378,7 +379,9 @@ class Archive:
 
     def _load_meta(self, id):
         data = self.key.decrypt(id, self.repository.get(id))
-        metadata = ArchiveItem(internal_dict=msgpack.unpackb(data, unicode_errors='surrogateescape'))
+        # we do not require TAM for archives, otherwise we can not even borg list a repo with old archives.
+        archive, self.tam_verified = self.key.unpack_and_verify_archive(data, force_tam_not_required=True)
+        metadata = ArchiveItem(internal_dict=archive)
         if metadata.version != 1:
             raise Exception('Unknown archive metadata version')
         return metadata

src/borg/crypto/key.py

@@ -284,7 +284,9 @@ class KeyBase:
         """Unpack msgpacked *data* and return (object, did_verify)."""
         tam_required = self.tam_required
         if force_tam_not_required and tam_required:
-            logger.warning('Archive authentication DISABLED.')
+            # for a long time, borg only checked manifest for "tam_required" and
+            # people might have archives without TAM, so don't be too annoyingly loud here:
+            logger.debug('Archive authentication DISABLED.')
             tam_required = False
         data = bytearray(data)
         unpacker = get_limited_unpacker('archive')

src/borg/helpers.py

@@ -1815,9 +1815,10 @@ class ArchiveFormatter(BaseFormatter):
         'id': 'internal ID of the archive',
         'hostname': 'hostname of host on which this archive was created',
         'username': 'username of user who created this archive',
+        'tam': 'TAM authentication state of this archive',
     }
     KEY_GROUPS = (
-        ('archive', 'name', 'barchive', 'comment', 'bcomment', 'id'),
+        ('archive', 'name', 'barchive', 'comment', 'bcomment', 'id', 'tam'),
         ('start', 'time', 'end', 'command_line'),
         ('hostname', 'username'),
     )
@@ -1868,6 +1869,7 @@ class ArchiveFormatter(BaseFormatter):
             'bcomment': partial(self.get_meta, 'comment', rs=False),
             'end': self.get_ts_end,
             'command_line': self.get_cmdline,
+            'tam': self.get_tam,
         }
         self.used_call_keys = set(self.call_keys) & self.format_keys
         if self.json:
@@ -1918,6 +1920,9 @@ class ArchiveFormatter(BaseFormatter):
     def get_ts_end(self):
         return self.format_time(self.archive.ts_end)
 
+    def get_tam(self):
+        return 'verified' if self.archive.tam_verified else 'none'
+
     def format_time(self, ts):
         return OutputTimestamp(ts)