Hermes-agent

tools/env_passthrough.py

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+"""Environment variable passthrough registry.
+
+Skills that declare ``required_environment_variables`` in their frontmatter
+need those vars available in sandboxed execution environments (execute_code,
+terminal).  By default both sandboxes strip secrets from the child process
+environment for security.  This module provides a session-scoped allowlist
+so skill-declared vars (and user-configured overrides) pass through.
+
+Two sources feed the allowlist:
+
+1. **Skill declarations** — when a skill is loaded via ``skill_view``, its
+   ``required_environment_variables`` are registered here automatically.
+2. **User config** — ``terminal.env_passthrough`` in config.yaml lets users
+   explicitly allowlist vars for non-skill use cases.
+
+Both ``code_execution_tool.py`` and ``tools/environments/local.py`` consult
+:func:`is_env_passthrough` before stripping a variable.
+"""
+
+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 set of env var names that should pass through to sandboxes.
+# Backed by ContextVar to prevent cross-session data 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 (API key,
+    token, or similar) per ``_HERMES_PROVIDER_ENV_BLOCKLIST``.
+
+    Skill-declared ``required_environment_variables`` frontmatter must
+    not be able to override this list — that was the bypass in
+    GHSA-rhgp-j443-p4rf where a malicious skill registered
+    ``ANTHROPIC_TOKEN`` / ``OPENAI_API_KEY`` as passthrough and received
+    the credential in the ``execute_code`` child process, defeating the
+    sandbox's scrubbing guarantee.
+
+    Non-Hermes API keys (TENOR_API_KEY, NOTION_TOKEN, etc.) are NOT
+    in the blocklist and remain legitimately registerable — skills that
+    wrap third-party APIs still work.
+    """
+    try:
+        from tools.environments.local import _HERMES_PROVIDER_ENV_BLOCKLIST
+    except Exception:
+        return False
+    return name in _HERMES_PROVIDER_ENV_BLOCKLIST
+
+
+def register_env_passthrough(var_names: Iterable[str]) -> None:
+    """Register environment variable names as allowed in sandboxed environments.
+
+    Typically called when a skill declares ``required_environment_variables``.
+
+    Variables that are Hermes-managed provider credentials (from
+    ``_HERMES_PROVIDER_ENV_BLOCKLIST``) are rejected here to preserve
+    the ``execute_code`` sandbox's credential-scrubbing guarantee per
+    GHSA-rhgp-j443-p4rf. A skill that needs to talk to a Hermes-managed
+    provider should do so via the agent's main-process tools (web_search,
+    web_extract, etc.) where the credential remains safely in the main
+    process.
+
+    Non-Hermes third-party API keys (TENOR_API_KEY, NOTION_TOKEN, etc.)
+    pass through normally — they were never in the sandbox scrub list.
+    """
+    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()
+                # Mirror the skill-path filter in register_env_passthrough:
+                # Hermes-managed provider credentials must not be passed
+                # through to execute_code / terminal children, regardless of
+                # whether the request came from a skill or from config.yaml.
+                # See 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:
+    """Check whether *var_name* is allowed to pass through to sandboxes.
+
+    Returns ``True`` if the variable was registered by a skill or listed in
+    the user's ``tools.env_passthrough`` 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 clear_env_passthrough() -> None:
+    """Reset the skill-scoped allowlist (e.g. on session reset)."""
+    _get_allowed().clear()
+
+