fix(security): eliminate info/exclude write (closes #16)#22
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….gitignore (closes #16) Redesign (3rd eliminate in the worktree security series, after leave-branch and core.symlinks=false). The original createWorktree wrote .worktrees/ into <gitDir>/info/exclude to keep the worktree dir out of git status. That write was the entire #16 vulnerability: if gitDir resolved outside repoRoot (separate-git-dir, crafted .git gitfile, linked worktree), the exclude write landed at an attacker-controlled location. Detection-based fixes (boundary checks) broke after 2 iterations: git introspection cannot authenticate external common-dirs — legit linked worktrees gitdir in <main>/.git/worktrees/ is indistinguishable from attack separate-git-dir via path inspection. Two independent Codex runs converged on the same conclusion: eliminate the write, don't detect. Fix: delete the entire git-dir/info/exclude block. git worktree add works WITHOUT it (the exclude was cosmetic, from openai#137 commit 4bca062). Keep .worktrees/ out of git status via an in-repo .worktrees/.gitignore containing *, written inside the already-validated worktreesDir (#14 guard ensures inside repoRoot, not a symlink). No git-dir metadata write = no write outside repoRoot = #16 dead. Regression tests: separate-git-dir repo now works (previously attack case); linked worktree works (previously broken by boundary check); external info/exclude untouched. Verified: worktree 18/18; full npm test 161 pass / 4 pre-existing. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Cycle 1 triage: Codex HIGH (dangling .gitignore symlink redirect), Claude APPROVE (false positive — .worktrees already attacker-writable). Applied the lstat guard on .gitignore (defense-in-depth, 2 lines) in d791eab — closes both perspectives. 18/18 tests. Ready to merge. |
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Security hardening release: leave-branch worktree cleanup (#12) + 4 security fixes (#18 symlink guard, #20 core.symlinks=false neutralize, #22 eliminate info/exclude write, #23 accumulation warn). rescue default --background (#8). test-teardown (#5). All verified with cycle-review. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Closes #16. Third eliminate-redesign in the worktree security series (after leave-branch #12 and core.symlinks=false #20).
The original createWorktree wrote .worktrees/ into /info/exclude. That write was the entire #16 vuln: if gitDir resolved outside repoRoot (separate-git-dir, gitfile, linked worktree), the write landed at attacker location. Detection-based boundary checks broke legit linked worktrees and couldn't distinguish them from attack. Eliminate the write entirely: git worktree add works without it. Use in-repo .worktrees/.gitignore instead. 18/18 tests, 161 pass / 4 pre-existing.