Close config paths to command execution (#24890)

* check go2rtc stream sources on the internal port

auth() returned admin for internal port requests before the go2rtc src check ran, so anyone who could reach port 5000 could send an unknown src to /api/ws, and go2rtc created a stream from it and started its producer, including ffmpeg sources with #raw= arguments. The internal port now rejects any src that isn't an existing stream, the same as the external port, and still skips the per-camera role checks.

* reject go2rtc stream names that can inject transcode parameters

live.transcode.source names a go2rtc stream that is spliced into an ffmpeg:{name}#video=h264 source, and stream names were never validated, so a stream named with #raw= parameters, whitespace, quotes or a ${VAR} reference added its own ffmpeg arguments. New stream names with these characters are rejected through the API, transcode.source fails validation when its stream name has them, and startup skips the generated transcode stream.

* only export allowlisted environment_vars

apply_config_env_vars wrote every unprefixed environment_vars key into os.environ and exported every FRIGATE_ key, so a config could set LD_PRELOAD or LIGHTER_ANE_EP to load a library into Frigate or its children, or set FRIGATE_RUN_AS_ROOT to turn off the ffmpeg.path writable-tree guard. Only the documented names are now exported, each with a value check, and a name the container already sets is never overwritten. FRIGATE_ keys still feed substitution, but only FRIGATE_JWT_SECRET is exported. Anything else logs a warning naming the key.

* don't trust live stream names as existing go2rtc streams

frigate/util/env.py

@@ -26,6 +26,8 @@ _SECRETS_FILE: dict[str, str] = {}
 _CONTAINER_ENV: dict[str, str] = {
     k: v for k, v in os.environ.items() if k.startswith("FRIGATE_")
 }
+# Empty image defaults, like ROCm's HSA_OVERRIDE_GFX_VERSION, don't count as set.
+_CONTAINER_ENV_NAMES = frozenset(k for k, v in os.environ.items() if v)
 _CREDENTIALS_DIR: dict[str, str] = {}
 
 _SOURCES: tuple[tuple[str, dict[str, str]], ...] = (
@@ -165,38 +167,80 @@ def reload_sources(warn: bool = True) -> None:
     _rebuild(warn)
 
 
-# Security overrides that must come from the container environment, which is
-# controlled by the operator, rather than from the config, which admins can edit
-_PROTECTED_ENV_VARS = frozenset({"GO2RTC_ALLOW_ARBITRARY_EXEC"})
+_INT = re.compile(r"\d+", re.ASCII)
+_WORD = re.compile(r"\w+", re.ASCII)
+_URL = re.compile(r"https?://\S+")
+
+# The only unprefixed names the config may export, with the values each accepts.
+# Anything else, such as LD_PRELOAD, can load code into Frigate or its children.
+_ALLOWED_ENV_VARS: dict[str, re.Pattern[str]] = {
+    "LIBVA_DRIVER_NAME": re.compile(r"[A-Za-z0-9_]+"),
+    "TF_INTRA_OP_PARALLELISM_THREADS": _INT,
+    "TF_INTER_OP_PARALLELISM_THREADS": _INT,
+    "TF_DATASET_THREAD_POOL_SIZE": _INT,
+    "SHM_MAX_FRAMES": _INT,
+    "USE_FP16": _WORD,
+    "HF_HUB_OFFLINE": _WORD,
+    "TRANSFORMERS_OFFLINE": _WORD,
+    "HSA_OVERRIDE_GFX_VERSION": re.compile(r"[0-9.]+"),
+    "HF_ENDPOINT": _URL,
+    "GITHUB_ENDPOINT": _URL,
+    "GITHUB_RAW_ENDPOINT": _URL,
+    "TF_KERAS_MOBILENET_V2_WEIGHTS_URL": _URL,
+}
+
+# Auth reads it from os.environ; every other FRIGATE_ name only feeds substitution.
+_EXPORTED_FRIGATE_VARS = frozenset({"FRIGATE_JWT_SECRET"})
 
 
 def apply_config_env_vars(values: Mapping[str, object]) -> None:
     """Install the environment_vars block as the lowest priority source.
 
-    Unprefixed keys only set os.environ. Protected security overrides are
-    skipped.
+    FRIGATE_ keys feed substitution. Allowlisted unprefixed keys with valid
+    values are exported to os.environ. A name the container already set is
+    never overwritten.
     """
+    exports: dict[str, str] = {}
+
     for key, value in values.items():
-        if key.upper() in _PROTECTED_ENV_VARS:
+        resolved = str(value)
+
+        if key.startswith("FRIGATE_"):
+            _CONFIG_ENV_VARS[key] = resolved
+            continue
+
+        pattern = _ALLOWED_ENV_VARS.get(key)
+
+        if pattern is None:
             logger.warning(
                 "Ignoring %s in environment_vars, it must be set in the container environment",
                 key,
             )
             continue
 
-        resolved = str(value)
+        if not pattern.fullmatch(resolved):
+            logger.warning("Ignoring %s in environment_vars, unsupported value", key)
+            continue
 
-        if key.startswith("FRIGATE_"):
-            _CONFIG_ENV_VARS[key] = resolved
-        else:
-            os.environ[key] = resolved
+        exports[key] = resolved
 
     _rebuild()
 
-    # Export the winning value; auth reads FRIGATE_JWT_SECRET from os.environ.
-    for key in values:
-        if key.startswith("FRIGATE_"):
-            os.environ[key] = FRIGATE_ENV_VARS[key]
+    for key in _EXPORTED_FRIGATE_VARS & values.keys():
+        exports[key] = FRIGATE_ENV_VARS[key]
+
+    for key, value in exports.items():
+        if key in _CONTAINER_ENV_NAMES:
+            logger.info(
+                "Ignoring %s in environment_vars, the container environment sets it",
+                key,
+            )
+            continue
+
+        try:
+            os.environ[key] = value
+        except ValueError:
+            logger.warning("Ignoring %s in environment_vars, unsupported value", key)
 
 
 reload_sources(warn=False)