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

docs/docs/configuration/advanced/reference.md

@@ -240,7 +240,7 @@ logger:
 
 # Optional: set environment variables
 environment_vars:
-  EXAMPLE_VAR: value
+  LIBVA_DRIVER_NAME: i965
 
 # Optional: birdseye configuration
 # NOTE: Can (enabled, mode) be overridden at the camera level

docs/docs/configuration/advanced/system.md

@@ -65,7 +65,16 @@ go2rtc:
 
 This section sets environment variables in the Frigate process for those unable to modify the environment of the container, like within Home Assistant OS. It's meant for process settings such as `LIBVA_DRIVER_NAME` or the TensorFlow thread counts below. Docker users should set environment variables in their `docker run` command (`-e LIBVA_DRIVER_NAME=i965`) or `docker-compose.yml` file (`environment:` section) instead. Values set here are stored in plain text in your config file, so credentials belong in `secrets.yaml`, Docker environment variables, or Docker secrets instead.
 
-Names prefixed with `FRIGATE_` set here also take part in `{FRIGATE_VARIABLE_NAME}` substitution (see [below](#substitution-sources-and-precedence)), but `secrets.yaml` is the better home for them.
+Besides `FRIGATE_` names, only these are accepted, and a variable already set in the container environment keeps its container value:
+
+- `LIBVA_DRIVER_NAME` and `HSA_OVERRIDE_GFX_VERSION`
+- `TF_INTRA_OP_PARALLELISM_THREADS`, `TF_INTER_OP_PARALLELISM_THREADS`, `TF_DATASET_THREAD_POOL_SIZE`, and `SHM_MAX_FRAMES`
+- `USE_FP16`, `HF_HUB_OFFLINE`, and `TRANSFORMERS_OFFLINE`
+- `HF_ENDPOINT`, `GITHUB_ENDPOINT`, `GITHUB_RAW_ENDPOINT`, and `TF_KERAS_MOBILENET_V2_WEIGHTS_URL` (an `http://` or `https://` URL)
+
+Any other name is ignored with a warning and must be set in the container environment.
+
+Names prefixed with `FRIGATE_` set here take part in `{FRIGATE_VARIABLE_NAME}` substitution (see [below](#substitution-sources-and-precedence)), but `secrets.yaml` is the better home for them. Of these, only `FRIGATE_JWT_SECRET` is also set in the process environment.
 
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