[Fix] Eliminate TOCTOU race in context file path validation#185
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Merge validatePathSecurity into readContextFile as a single fd-centric
operation: open fd first, validate via /dev/fd/{fd} realpath, fstat and
read through the fd, never touching the path again after open.
Eliminates three TOCTOU windows:
- validate(path) → read(path) across two IPC steps
- statSync(path) → openSync(path) within text branch
- statSync(path) → readFileSync(path) within binary branch
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Summary
Eliminate TOCTOU race condition in
validatePathSecurity/readContextFileby merging validation and reading into a single fd-centric operation. AfteropenSync, the file descriptor is pinned to an inode — all subsequent operations (realpath resolution, stat, read) go through the fd, never touching the original path again.Type of change
[Fix]bug fixWhy is this needed?
The previous implementation called
validatePathSecurity(path)thenreadContextFile(path)as two separate steps. Between validation and read, a symlink in a user-added context folder (e.g./tmp) could be swapped to point outside allowed folders. Additionally, withinreadContextFileitself,statSync(path)and the subsequentopenSync(path)/readFileSync(path)had their own TOCTOU windows.What changed?
readContextFilenow acceptscontextFolders, opens the fd first, validates viarealpathSync("/dev/fd/${fd}"), usesfstatSync(fd)for size, and reads viareadSync(fd)for both text and binary tiersvalidatePathSecurityremoved — its logic is inlined into the atomic fd-based flowcontext-handlers.tssimplified: singlereadContextFile(path, folders)call replaces the two-step validate-then-readArchitecture impact
context:read-fileparams) is unchangeddocs/architecture-invariants.md: noneLinked issues
Closes #115
Validation
pnpm lintpnpm testpnpm check:ui-contractpnpm check:architecturepnpm buildCommands, screenshots, or notes:
Screenshots or recordings
No UI changes.
Release note
NONE.Checklist
[Feat],[Fix],[UI],[Docs],[Refactor],[Build], or[Chore]