fix(#25821): refuse to chmod top-level dirs from 5 token-storage call sites#27384
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fix(#25821): refuse to chmod top-level dirs from 5 token-storage call sites#27384YonganZhang wants to merge 1 commit into
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…storage call sites Fixes NousResearch#25821. `os.chmod(path.parent, 0o700)` is called on a derived path at five token-storage sites without checking that `path.parent` is a sane directory. If anything makes the resolution land at `/` (e.g. `HERMES_HOME=/`, an env-var concat bug, or a path whose `.parent.parent == .parent`), chmod silently succeeds and strips traversal permission from the root inode, bricking the host: every non-root user fails any path lookup with `EACCES`, taking out systemd-resolved, systemd-networkd, syslog, every Docker container that drops privileges, and graceful reboot. Root keeps working (CAP_DAC_OVERRIDE) so the symptom cascades for hours before recovery via rescue mode. (See the issue body for the full incident timeline.) This adds `_secure_dir_safe(path)` to `hermes_cli/config.py` (next to the existing `_secure_dir`) that: * Resolves the path first (so symlink games can't smuggle `/` past a string check). * Refuses single-component paths (`len(parts) < 2`), the filesystem anchor (`Path("/")`, `C:\\`), and a blocklist of known system roots (`/etc`, `/var`, `/usr`, `/home`, `/root`, `/opt`, `/tmp`, `/sys`, `/proc`, `/dev`, `/boot`, `/lib`, `/lib64`, `/run`, `/srv`, `/mnt`, `/media`). * Always uses 0o700, no `HERMES_HOME_MODE` override — token stores must not be traversable regardless of deployment profile. * Honors `is_managed()` for parity with the existing `_secure_dir` (NixOS module sets group-readable permissions). Switches all five identified call sites to use the new helper: * `tools/mcp_oauth.py` (MCP OAuth token storage) * `agent/google_oauth.py` (Google/Gemini OAuth) * `hermes_cli/auth.py` ×3 (Hermes auth store, Qwen CLI tokens, `HERMES_SHARED_AUTH_DIR` nous shared token) A misresolved `HERMES_HOME` is still a bug worth diagnosing — strict-mode logger.error on top-level resolution is left as a follow-up. The priority here is to make the catastrophic outcome ("brick the host silently") unreachable from any of these five sites. `cron/jobs.py` has its own local `_secure_dir` helper that should probably be unified with this one, but is intentionally out of scope for this PR (its callers operate on `CRON_DIR`/`OUTPUT_DIR` which are not derived from user-controlled env vars, so the bricking trigger does not apply there today). Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Closing as duplicate. Apologies for not running I'll add an observation on #25841 in case the helper's blocklist is worth widening. |
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Summary
Fixes #25821.
The original issue describes a production outage caused by
os.chmod(path.parent, 0o700)succeeding silently against/and stripping traversal permission from the root inode — bricking every non-root user on the host. Root cause took 5+ hours to isolate.There are five call sites with the same shape:
tools/mcp_oauth.py— MCP OAuth token storageagent/google_oauth.py— Google / Gemini OAuthhermes_cli/auth.py×3 — Hermes auth store, Qwen CLI tokens,HERMES_SHARED_AUTH_DIRshared tokenAll five become unsafe the moment a derived path resolves to a top-level directory (empty
HERMES_HOME, env-var concat bug, etc.).What this PR does
Adds
_secure_dir_safe(path)tohermes_cli/config.py, next to the existing_secure_dir. It:/past a string check.len(parts) < 2), the filesystem anchor (Path("/"),C:\), and a blocklist of known system roots:/etc /var /usr /home /root /opt /tmp /sys /proc /dev /boot /lib /lib64 /run /srv /mnt /media.0o700— noHERMES_HOME_MODEoverride, because token stores must not be group-readable regardless of deployment profile.is_managed()for parity with the existing helper (NixOS module sets group-readable perms intentionally).Switches all five call sites to use the new helper. They each lose the surrounding
try / except OSError / passboilerplate because_secure_dir_safealready swallowsOSError/NotImplementedErrorinternally.Behavior trip-tests (inline Python)
path.parentresolves to/home/alice/.hermes/auth//etc/tmp/x→//, refused ✅/home(single mid-level)/home/*for everyone 🔴C:\(Windows anchor)~/.hermes/authOSErrorswallowedScope
cron/jobs.pyhas its own local_secure_dirthat should probably be unified with the new safe variant, but is intentionally out of scope for this PR — its callers operate onCRON_DIR/OUTPUT_DIR, neither of which is derived from user-controlled env vars, so the bricking trigger doesn't apply there today. Happy to follow up with a unify-helpers PR if maintainers want it cleaned in one direction.Related
_secure_dir()work on~/.hermesitself; left the five sites above untouched.The issue author offered to send a PR — opening this one in case it's still useful. Happy to iterate on the helper signature or scope as needed.