fix(workspace): close macOS /etc symlink bypass; add /var/folders user-tmp carve-out by nesquena · Pull Request #1186 · nesquena/hermes-webui

nesquena · 2026-04-27T23:55:48Z

Summary

Closes the recurring macOS-only failure of tests/test_sprint3.py::test_workspace_add_rejects_system_paths AND a real security gap that came with it.

The bug

_workspace_blocked_roots() returned literal Path('/etc'), Path('/var'), etc. On macOS, those are symlinks to /private/etc, /private/var, /private/tmp. Every caller resolves user input via Path(input).resolve() first — so the candidate became /private/etc while the blocked entry was the literal /etc. /private/etc.relative_to(/etc) raises ValueError, the candidate falls through every blocked-root check, and the route handler accepts /etc as a registered workspace.

Two consequences:

Test failure: POST /api/workspaces/add with /etc returned 200 instead of 400 on macOS.
Security gap: /private/var/log could be registered as a workspace on macOS, letting agents read system logs through the carved-out trust path.

On Linux there's no symlink, literal == resolved, so the check worked correctly.

The fix

_workspace_blocked_roots() now returns BOTH the literal and resolved-canonical forms, deduped. Path('/etc').resolve() is /private/etc on macOS and /etc on Linux — so the set self-canonicalises per platform without any OS-specific code.

A naive "resolve everything" would also block legit user-tmp paths under /private/var/folders/<hash>/T/ — pytest's tmp_path_factory writes there on macOS, and test_workspace_add_allows_external_valid_paths explicitly registers tmp dirs. New _USER_TMP_PREFIXES carve-out (/var/folders, /private/var/folders, /var/tmp, /private/var/tmp), checked first in _is_blocked_system_path() so user-tmp paths short-circuit to "not blocked" even though their parent is.

Linux behaviour is unchanged: literal == resolved, no extra entries, no paths pass that wouldn't have before.

What changed

api/workspace.py — _workspace_blocked_roots() returns canonical-deduped set; new _safe_resolve helper, _USER_TMP_PREFIXES carve-outs, and _is_blocked_system_path() consolidating the 6 inlined loops across the file.
api/routes.py — _handle_workspace_add pre-create guard switched to the helper.
tests/test_workspace_blocked_roots_macos.py — 26 new tests locking the set canonicalisation, /etc-and-/private/etc-both-blocked invariant, /var/log security gap closure, and /var/folders carve-out behaviour.
tests/test_batch_fixes.py — test_etc_still_blocked substring match relaxed to accept the new bare-string-in-tuple form.

Result

Full suite: 2664 passed, 47 skipped, 0 failed on macOS. The pre-existing test_sprint3 failure is gone. CI on Linux continues to pass (verified by the unchanged behaviour for non-symlink roots).

🤖 Generated with Claude Code

The blocked-roots set was a tuple of literal paths (`/etc`, `/var`, ...). On macOS those are symlinks to `/private/etc`, `/private/var`, `/private/tmp`. Every caller resolves user input via `Path(input).resolve()` first — so the candidate became `/private/etc` while the blocked entry was the literal `/etc`. `/private/etc.relative_to(/etc)` raises ValueError, the candidate falls through every blocked-root check, and the route handler accepts `/etc` as a registered workspace. This was directly observable as the recurring pre-existing macOS test failure `test_workspace_add_rejects_system_paths` (POST /api/workspaces/add with `/etc` returned 200 instead of 400). It was also a real security gap: `/private/var/log` could be registered as a workspace on macOS, letting agents read system logs through the carved-out trust path. Fix: `_workspace_blocked_roots()` now returns BOTH the literal and symlink-resolved canonical forms, deduped. `Path('/etc').resolve()` is `/private/etc` on macOS and `/etc` on Linux — so the set self-canonicalises per platform without any OS-specific code. A naive "resolve everything" change would also block legit user-tmp paths under `/private/var/folders/<hash>/T/` — pytest's `tmp_path_factory` writes there on macOS, and `test_workspace_add_allows_external_valid_paths` explicitly registers tmp dirs as workspaces. Carve-out via a new `_USER_TMP_PREFIXES` tuple covering `/var/folders`, `/private/var/folders`, `/var/tmp`, `/private/var/tmp` — checked first in `_is_blocked_system_path()` so user-tmp paths short-circuit to "not blocked" even though their parent (`/var`) is. Linux behaviour is unchanged: literal == resolved, no extra entries, no blocked paths pass that wouldn't have before. Updated all six in-tree call sites to use the new `_is_blocked_system_path` helper instead of inlining the loop: - _trusted_workspace_roots (api/workspace.py:321) - resolve_trusted_workspace home sanity + block check (api/workspace.py:453,462) - validate_workspace_to_add (api/workspace.py:514) - safe_resolve_ws symlink-target check (api/workspace.py:553) - list_dir symlink-target check (api/workspace.py:577) - _handle_workspace_add pre-create guard in api/routes.py:3208 Tests: - 26 new tests in test_workspace_blocked_roots_macos.py covering: - Set canonicalisation (literal + resolved both present) - /etc / /private/etc both blocked across platforms - /var/log security gap on macOS now closed - /var/folders, /private/var/folders, /var/tmp user-tmp carve-outs - All non-symlink roots and their subpaths still blocked - test_batch_fixes.test_etc_still_blocked: relaxed substring match to accept the new bare-string-in-tuple form. - Full suite locally: 2664 passed, 47 skipped, 0 failures. Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

nesquena-hermes · 2026-04-28T00:16:08Z

Good fix with solid test coverage. A few notes from review:

Security impact confirmed: The macOS symlink path (/etc → /private/etc) was a real bypass — Path('/etc').resolve() on macOS returns /private/etc, so relative_to('/etc') always raised ValueError and the candidate fell through all blocked-root checks. This is a meaningful security gap, not just a test flake.

Fix approach looks correct: Returning both literal + resolved canonical forms from _workspace_blocked_roots() self-canonicalises per platform without OS-specific branches — clean.

_USER_TMP_PREFIXES carve-out: The /var/folders + /private/var/folders carve-out is necessary because macOS routes tempfile.mkdtemp() and pytest's tmp_path_factory through /private/var/folders/<hash>/T/. The check-first ordering in _is_blocked_system_path() (carve-out → blocked root) means valid tmp paths short-circuit correctly even though their parent /var is blocked.

Linux regression risk: Low — on Linux, Path('/etc').resolve() returns /etc, so the deduped set contains only the original entries. Existing tests continue to cover the Linux path.

One thing to verify: The safe_resolve_ws symlink-target check (mentioned in the commit as a call site updated to use the helper) — worth confirming it handles the case where a symlink inside an allowed workspace points to /private/etc on macOS. That path would now correctly be blocked by the resolved form.

Overall: the fix is correctly scoped, well-tested (26 new tests covering the key invariants), and the Linux behaviour is provably unchanged. 👍

@nesquena

…code leak (#1194) Batch release v0.50.231 — 3 fixes. ## PRs included | PR | Author | Fix | |---|---|---| | #1186 | @nesquena (Claude Code) | macOS `/etc` symlink bypass in workspace blocked-roots | | #1187 | @nesquena-hermes | Workspace panel stuck closed after empty-session reload | | #1190 | @bergeouss | Fenced code content leaking into markdown passes (#1154) | All three PRs were independently reviewed and approved by @nesquena. ## Test results **2729 passed, 2 skipped** (2 macOS-only tests correctly skipped on Linux). Browser QA: **21/21**. ## Key fix notes **#1186:** `_workspace_blocked_roots()` now returns both literal and `Path.resolve()` forms of each blocked root. macOS symlinks (`/etc → /private/etc`) previously let a resolved candidate slip past the literal check. New `_is_blocked_system_path()` helper with `/var/folders` and `/var/tmp` carve-outs for pytest temp dirs. **#1187:** Regression from #1182 — `syncWorkspacePanelState()` force-closed on any no-session state. Now only closes in `'preview'` mode. Both boot paths restore localStorage panel pref before sync. **#1190:** Fenced code blocks are now stashed as `\x00P<n>\x00` tokens through ALL markdown passes (list/heading/table regexes), restored at the very end. Previously, diff hunks and markdown headings inside code blocks triggered those regexes, injecting `<ul>/<li>/<h>` tags that broke `</pre>` closure.

nesquena-hermes · 2026-04-28T00:44:06Z

Merged as v0.50.231 via #1194. Thank you @nesquena!

@nesquena

…code leak (nesquena#1194) Batch release v0.50.231 — 3 fixes. ## PRs included | PR | Author | Fix | |---|---|---| | nesquena#1186 | @nesquena (Claude Code) | macOS `/etc` symlink bypass in workspace blocked-roots | | nesquena#1187 | @nesquena-hermes | Workspace panel stuck closed after empty-session reload | | nesquena#1190 | @bergeouss | Fenced code content leaking into markdown passes (nesquena#1154) | All three PRs were independently reviewed and approved by @nesquena. ## Test results **2729 passed, 2 skipped** (2 macOS-only tests correctly skipped on Linux). Browser QA: **21/21**. ## Key fix notes **nesquena#1186:** `_workspace_blocked_roots()` now returns both literal and `Path.resolve()` forms of each blocked root. macOS symlinks (`/etc → /private/etc`) previously let a resolved candidate slip past the literal check. New `_is_blocked_system_path()` helper with `/var/folders` and `/var/tmp` carve-outs for pytest temp dirs. **nesquena#1187:** Regression from nesquena#1182 — `syncWorkspacePanelState()` force-closed on any no-session state. Now only closes in `'preview'` mode. Both boot paths restore localStorage panel pref before sync. **nesquena#1190:** Fenced code blocks are now stashed as `\x00P<n>\x00` tokens through ALL markdown passes (list/heading/table regexes), restored at the very end. Previously, diff hunks and markdown headings inside code blocks triggered those regexes, injecting `<ul>/<li>/<h>` tags that broke `</pre>` closure.

nesquena and others added 2 commits April 27, 2026 16:55

test: skip /private/* assertions on Linux where the symlinks don't exist

3e3774a

This was referenced Apr 28, 2026

fix(ui): workspace panel persists across reload on empty-session boot #1187

Closed

fix #1154: prevent fenced code content from leaking into markdown passes #1190

Closed

nesquena-hermes mentioned this pull request Apr 28, 2026

fix: batch v0.50.231 — macOS symlink bypass, workspace panel, fenced code leak #1194

Merged

nesquena-hermes closed this Apr 28, 2026

nesquena-hermes deleted the fix/blocked-roots-macos-symlinks branch April 28, 2026 00:44

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fix(workspace): close macOS /etc symlink bypass; add /var/folders user-tmp carve-out#1186

fix(workspace): close macOS /etc symlink bypass; add /var/folders user-tmp carve-out#1186
nesquena wants to merge 2 commits intomasterfrom
fix/blocked-roots-macos-symlinks

nesquena commented Apr 27, 2026

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nesquena commented Apr 27, 2026

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nesquena-hermes commented Apr 28, 2026

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