Files
hermes-agent/tools/env_passthrough.py

198 lines
7.8 KiB
Python

"""Environment variable passthrough registry.
Skills that declare ``required_environment_variables`` need those vars in
sandboxed execution environments (execute_code, terminal), which strip secrets
from the child process environment by default. This module is the
session-scoped allowlist, fed by two sources: skill declarations (registered
automatically by ``skill_view``) and ``terminal.env_passthrough`` in
config.yaml.
``code_execution_tool.py`` and ``tools/environments/local.py`` consult
:func:`is_env_passthrough` before stripping a variable. When profile
multiplexing is active, forwarded values are resolved through the current
profile's secret scope rather than the process environment.
"""
from __future__ import annotations
import logging
from contextvars import ContextVar
from typing import Iterable
from hermes_cli.config import cfg_get
logger = logging.getLogger(__name__)
# Session-scoped allowlist; ContextVar-backed to prevent cross-session bleed
# in the gateway pipeline.
_allowed_env_vars_var: ContextVar[set[str]] = ContextVar("_allowed_env_vars")
def _get_allowed() -> set[str]:
"""Get or create the allowed env vars set for the current context/session."""
try:
return _allowed_env_vars_var.get()
except LookupError:
val: set[str] = set()
_allowed_env_vars_var.set(val)
return val
# Cache for the config-based allowlist (loaded once per process).
_config_passthrough: frozenset[str] | None = None
def _is_hermes_provider_credential(name: str) -> bool:
"""True if ``name`` is a Hermes-managed provider credential per
``_HERMES_PROVIDER_ENV_BLOCKLIST`` (or a dynamic Hermes-internal secret).
Skill-declared ``required_environment_variables`` must not override this
list — that was the GHSA-rhgp-j443-p4rf bypass, where a malicious skill
registered ``OPENAI_API_KEY`` as passthrough and received it in the
``execute_code`` child, defeating the sandbox's scrubbing guarantee.
Non-Hermes API keys (TENOR_API_KEY, NOTION_TOKEN, …) are not in the
blocklist and remain registerable.
Fail closed: if the authoritative blocklist cannot be imported (partial
install, import-time error), treat the name as protected and refuse
passthrough rather than fall open.
"""
try:
from tools.environments.local import (
_HERMES_PROVIDER_ENV_BLOCKLIST,
_is_hermes_internal_secret,
)
except Exception as e:
logger.warning(
"env passthrough: provider credential blocklist import failed; "
"failing closed and refusing passthrough registration for %r: %s",
name,
e,
)
return True
# Dynamically-generated Hermes-internal secrets (AUXILIARY_*_API_KEY /
# _BASE_URL, GATEWAY_RELAY_*) are injected per task/relay at gateway
# startup, so the static blocklist can't enumerate them.
if _is_hermes_internal_secret(name):
return True
return name in _HERMES_PROVIDER_ENV_BLOCKLIST
def register_env_passthrough(var_names: Iterable[str]) -> None:
"""Register env var names as allowed in sandboxed environments (typically
from a skill's ``required_environment_variables``).
Hermes-managed provider credentials are rejected to preserve the
``execute_code`` sandbox's credential-scrubbing guarantee
(GHSA-rhgp-j443-p4rf); a skill needing a Hermes-managed provider should
use the main-process tools (web_search, web_extract, …) where the
credential stays in the main process. Third-party keys pass normally.
"""
for name in var_names:
name = name.strip()
if not name:
continue
if _is_hermes_provider_credential(name):
logger.warning(
"env passthrough: refusing to register Hermes provider "
"credential %r (blocked by _HERMES_PROVIDER_ENV_BLOCKLIST). "
"Skills must not override the execute_code sandbox's "
"credential scrubbing; see GHSA-rhgp-j443-p4rf.",
name,
)
continue
_get_allowed().add(name)
logger.debug("env passthrough: registered %s", name)
def _load_config_passthrough() -> frozenset[str]:
"""Load ``tools.env_passthrough`` from config.yaml (cached)."""
global _config_passthrough
if _config_passthrough is not None:
return _config_passthrough
result: set[str] = set()
try:
from hermes_cli.config import read_raw_config
cfg = read_raw_config()
passthrough = cfg_get(cfg, "terminal", "env_passthrough")
if isinstance(passthrough, list):
for item in passthrough:
if not isinstance(item, str) or not item.strip():
continue
name = item.strip()
# Same filter as register_env_passthrough: provider credentials
# must not reach sandbox children whether the request came from
# a skill or from config.yaml (GHSA-rhgp-j443-p4rf).
if _is_hermes_provider_credential(name):
logger.warning(
"env passthrough: refusing to register Hermes "
"provider credential %r from config.yaml (blocked "
"by _HERMES_PROVIDER_ENV_BLOCKLIST). Operator "
"configuration must not override the execute_code "
"sandbox's credential scrubbing; see "
"GHSA-rhgp-j443-p4rf.",
name,
)
continue
result.add(name)
except Exception as e:
logger.debug("Could not read tools.env_passthrough from config: %s", e)
_config_passthrough = frozenset(result)
return _config_passthrough
def is_env_passthrough(var_name: str) -> bool:
"""True if *var_name* was registered by a skill or listed in config."""
if var_name in _get_allowed():
return True
return var_name in _load_config_passthrough()
def get_all_passthrough() -> frozenset[str]:
"""Return the union of skill-registered and config-based passthrough vars."""
return frozenset(_get_allowed()) | _load_config_passthrough()
def resolve_passthrough_value(
name: str,
fallback: str | None = None,
) -> str | None:
"""Resolve an allowlisted variable without crossing profile boundaries.
``fallback`` is the value the caller would have forwarded before profile
secret scopes existed (typically a snapshot of ``os.environ`` or the
current profile's ``.env``). An active multiplex scope is authoritative:
a missing key returns ``None`` and never falls back to the process-global
environment; an unscoped read while multiplexing is active raises the
fail-closed ``UnscopedSecretError`` from :mod:`agent.secret_scope`.
Outside multiplexing, an installed scope keeps the overlay semantics and
an unscoped caller keeps its already-resolved fallback.
"""
from agent.secret_scope import (
_is_global_env,
current_secret_scope,
get_secret,
is_multiplex_active,
)
# Global terminal/runtime settings are not profile secrets. ``fallback``
# is already the caller's effective value (including an explicit per-call
# override), so preserve it rather than replacing it with the process-wide
# value while a multiplex scope is active.
if _is_global_env(name) and fallback is not None:
return fallback
scope = current_secret_scope()
multiplex_active = is_multiplex_active()
if scope is None:
if multiplex_active:
return get_secret(name)
return fallback
return get_secret(name, None if multiplex_active else fallback)
def clear_env_passthrough() -> None:
"""Reset the skill-scoped allowlist (e.g. on session reset)."""
_get_allowed().clear()