hermes-agent/tests/gateway/test_api_server_media_data_urls.py
srojk34 16332af60b security(gateway): anchor api_server MEDIA tag resolution to safe paths
_resolve_media_to_data_urls's ad-hoc _MEDIA_TAG_RE matched any bare
token after MEDIA: (no absolute-path anchor) and read the resolved
path directly with no denylist. A relative/traversal path like
MEDIA:../../../../etc/passwd.png slipped through, and any image-
suffixed file the process could read (including under ~/.ssh, ~/.aws,
etc.) was base64-inlined into the API response if its path merely
appeared in the model's own final reply text.

Every other platform adapter's MEDIA: handling already goes through
two shared primitives in gateway/platforms/base.py:
  - MEDIA_TAG_CLEANUP_RE, which anchors the path to ~/, /, or a
    Windows drive letter plus a known deliverable extension.
  - validate_media_delivery_path, which resolves symlinks and rejects
    paths under the credential/system-path denylist.

Reuse both here instead of the local unanchored pattern and naive
Path().expanduser() resolution.
2026-07-03 03:27:47 -07:00

111 lines
4.2 KiB
Python

"""MEDIA: tag → base64 data-URL resolution for the API server (salvage of #2696).
Remote OpenAI-compatible frontends can't read local file paths, so
``MEDIA:<path>`` image tags in final responses are inlined as markdown
data URLs before crossing the HTTP boundary.
"""
import base64
import unittest
import pytest
pytest.importorskip("aiohttp")
from gateway.platforms.api_server import _resolve_media_to_data_urls # noqa: E402
# 1x1 transparent PNG
_PNG_BYTES = base64.b64decode(
"iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR4nGNgYGBgAAAABQAB"
"h6FO1AAAAABJRU5ErkJggg=="
)
class TestResolveMediaToDataUrls(unittest.TestCase):
def _write_png(self, tmpdir_name="hermes_media_test"):
import tempfile
from pathlib import Path
d = Path(tempfile.mkdtemp(prefix=tmpdir_name))
p = d / "shot.png"
p.write_bytes(_PNG_BYTES)
return p
def test_media_tag_inlined(self):
p = self._write_png()
out = _resolve_media_to_data_urls(f"Here you go: MEDIA:{p}")
self.assertIn("data:image/png;base64,", out)
self.assertNotIn("MEDIA:", out)
def test_backtick_wrapped_tag(self):
p = self._write_png()
out = _resolve_media_to_data_urls(f"See `MEDIA:{p}` above")
self.assertIn("data:image/png;base64,", out)
def test_missing_file_left_untouched(self):
text = "MEDIA:/nonexistent/path/shot.png"
self.assertEqual(_resolve_media_to_data_urls(text), text)
def test_non_image_left_untouched(self):
text = "MEDIA:/tmp/archive.zip"
self.assertEqual(_resolve_media_to_data_urls(text), text)
def test_text_without_media_passthrough(self):
self.assertEqual(_resolve_media_to_data_urls("plain text"), "plain text")
self.assertEqual(_resolve_media_to_data_urls(""), "")
def test_oversized_image_skipped(self):
from gateway.platforms import api_server as mod
p = self._write_png()
orig = mod._MEDIA_DATA_URL_MAX_BYTES
mod._MEDIA_DATA_URL_MAX_BYTES = 1
try:
text = f"MEDIA:{p}"
self.assertEqual(_resolve_media_to_data_urls(text), text)
finally:
mod._MEDIA_DATA_URL_MAX_BYTES = orig
def test_multiple_tags(self):
p1 = self._write_png()
p2 = self._write_png("hermes_media_test2")
out = _resolve_media_to_data_urls(f"MEDIA:{p1}\nand MEDIA:{p2}")
self.assertEqual(out.count("data:image/png;base64,"), 2)
def test_relative_traversal_path_not_inlined(self):
"""A relative/traversal path must never be inlined — the anchored
MEDIA_TAG_CLEANUP_RE matcher requires an absolute-path prefix
(~/, /, or a Windows drive letter), so a bare relative token after
MEDIA: is left as literal text rather than resolved against cwd."""
text = "MEDIA:../../../../etc/passwd.png"
self.assertEqual(_resolve_media_to_data_urls(text), text)
def test_credential_path_not_inlined_even_with_image_extension(self):
"""An absolute path under the credential/system-path denylist
(validate_media_delivery_path) must not be inlined even though it
has an allowed image extension and the tag matcher's shape."""
text = "MEDIA:~/.ssh/id_rsa.png"
self.assertEqual(_resolve_media_to_data_urls(text), text)
def test_symlink_escaping_to_denylisted_target_not_inlined(self):
"""A symlink whose resolved target lands under a denylisted system
prefix (/etc) must not be inlined — validate_media_delivery_path
resolves symlinks before the containment/denylist check runs, so
the traversal can't be laundered through an innocuous-looking
image-suffixed symlink name."""
import os
import tempfile
from pathlib import Path
d = Path(tempfile.mkdtemp(prefix="hermes_media_test_symlink"))
link = d / "shot.png"
try:
os.symlink("/etc/hosts", link)
except OSError:
self.skipTest("symlink creation not supported in this environment")
text = f"MEDIA:{link}"
self.assertEqual(_resolve_media_to_data_urls(text), text)
if __name__ == "__main__":
unittest.main()