block filter and attach flags in custom ffmpeg export args

The ffmpeg argument blocklist missed -filter_complex, -lavfi, -vf,
-af, -filter, and -attach. These flags can read arbitrary files via
source filters like movie= and amovie=, bypassing the existing -i
block. A user with camera access could exploit this through the
custom export endpoint.

frigate/record/export.py

@@ -36,7 +36,9 @@ logger = logging.getLogger(__name__)
 DEFAULT_TIME_LAPSE_FFMPEG_ARGS = "-vf setpts=0.04*PTS -r 30"
 TIMELAPSE_DATA_INPUT_ARGS = "-an -skip_frame nokey"
 
-# ffmpeg flags that can read from or write to arbitrary files
+# ffmpeg flags that can read from or write to arbitrary files.
+# filter flags are blocked because source filters like movie= and
+# amovie= can read arbitrary files from the filesystem.
 BLOCKED_FFMPEG_ARGS = frozenset(
     {
         "-i",
@@ -45,6 +47,12 @@ BLOCKED_FFMPEG_ARGS = frozenset(
         "-passlogfile",
         "-sdp_file",
         "-dump_attachment",
+        "-filter_complex",
+        "-lavfi",
+        "-vf",
+        "-af",
+        "-filter",
+        "-attach",
     }
 )