Fix: token fallback file briefly world-readable before chmod#76
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karbassi wants to merge 1 commit into
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Fix: token fallback file briefly world-readable before chmod#76karbassi wants to merge 1 commit into
karbassi wants to merge 1 commit into
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The file-based session fallback wrote the long-lived Monarch token via Path.write_text() (created under the process umask, typically 0644) and only narrowed it to 0600 afterward. That leaves a window where a full-access financial credential is world-readable by other local users. Create the file already locked via os.open(..., O_CREAT, 0o600), keeping the trailing chmod to enforce 0600 on a pre-existing file. Adds a regression test that fails if creation reverts to write_text(). Fixes robcerda#75 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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What
Closes #75.
The file-based session fallback (used when no keyring backend is available — WSL, headless Linux) wrote the long-lived Monarch session token via
Path.write_text()and narrowed permissions to0600only afterward:write_text()creates the file under the process umask (commonly0644), so between the write and thechmodthe token is world-readable by any local user. The payload is a long-lived, full-access financial credential, so the window is worth closing.How
Create the file already locked to
0600viaos.open(..., O_CREAT, 0o600), then stillchmodto enforce0600if the file already existed. No behavior change for keyring users (unaffected path).Test
Adds
TestFileFallbackPermissions, which intercepts creation and fails if the token file is created viawrite_text()or with any mode other than0600. Verified the test fails against the old implementation and passes with the fix.🤖 Generated with Claude Code