🛡️ Sentinel: [HIGH] Fix TOCTOU vulnerability in config permissions#292
🛡️ Sentinel: [HIGH] Fix TOCTOU vulnerability in config permissions#292acebytes wants to merge 1 commit into
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Co-authored-by: acebytes <2820910+acebytes@users.noreply.github.com>
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| if fd >= 0 { | ||
| fchmod(fd, 0o600) | ||
| close(fd) | ||
| } |
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When open(..., O_NOFOLLOW | O_CLOEXEC) fails (for example, if autopilot.json is a symlink), this block silently skips fchmod and execution continues to contents(atPath:), which still loads the config. That means the intended 0600 enforcement is bypassed for exactly the untrusted-path case this change targets, leaving a symlinked or overly-permissive config file accepted. Please treat open/fchmod failure as a reload error (or read via the same validated fd) instead of continuing.
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| // Enforce 0600 permissions safely to prevent TOCTOU vulnerabilities | ||
| URL(fileURLWithPath: path).withUnsafeFileSystemRepresentation { pathPtr in | ||
| guard let ptr = pathPtr else { return } | ||
| let fd = open(ptr, O_RDONLY | O_NOFOLLOW | O_CLOEXEC) |
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Opening the file with O_RDONLY makes the permission-fix path fail for owner-unreadable configs (for example mode 0200 or 0000): open returns EACCES, fchmod never runs, and reload later errors on read. Before this commit, chmod(path, 0o600) could still repair those modes first, so this is a functional regression in self-healing permission enforcement. Consider using an access mode that can obtain an fd for fchmod without requiring immediate read permission (or retrying with a write-capable open).
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🚨 Severity: HIGH
💡 Vulnerability:
chmod()was used on a potentially untrusted pathpathwhen reloading the autopilot config. This allowed a TOCTOU (Time of Check, Time of Use) symlink vulnerability.🎯 Impact: An attacker could replace the config file with a symlink exactly when
chmodis called, potentially forcing the application to change permissions of arbitrary files the application has access to.🔧 Fix: Replaced
chmod()withopen()usingO_NOFOLLOWandO_CLOEXEC, followed byfchmod()on the secure file descriptor to prevent following symlinks.✅ Verification: Tested via
./scripts/test.sh.PR created automatically by Jules for task 3987718079707111301 started by @acebytes