🛡️ Sentinel: [CRITICAL] Fix TOCTOU vulnerability in chmod#296
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Used `chmod` which follows symlinks, introducing a TOCTOU vulnerability when enforcing config file permissions. An attacker could replace the config file with a symlink (e.g., to `/etc/passwd`) before the `chmod` operation, tricking the daemon into changing permissions of critical system files. Replaced `chmod` with `open()` using `O_NOFOLLOW` | `O_CLOEXEC` followed by `fchmod()`. Co-authored-by: acebytes <2820910+acebytes@users.noreply.github.com>
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| // Enforce 0600 permissions securely without following symlinks (TOCTOU prevention) | ||
| URL(fileURLWithPath: path).withUnsafeFileSystemRepresentation { cPath in | ||
| guard let cPath = cPath else { return } | ||
| let fd = open(cPath, O_RDONLY | O_NOFOLLOW | O_CLOEXEC) |
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Opening the config with O_RDONLY before fchmod introduces a regression when the file is owned by the daemon user but currently lacks read bits (for example mode 000 or 200): open fails with EACCES, the permission fix is skipped, and the subsequent contents(atPath:) read fails, leaving reload in an error state. The previous chmod(path, 0o600) path could recover these files by restoring read permission first, so this change can prevent valid configs from being loaded after restrictive mode changes.
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🚨 Severity: CRITICAL
💡 Vulnerability: Used
chmodwhich follows symlinks, introducing a TOCTOU vulnerability when enforcing config file permissions.🎯 Impact: An attacker could replace the config file with a symlink (e.g., to
/etc/passwd) before thechmodoperation, tricking the daemon into changing permissions of critical system files.🔧 Fix: Replaced
chmodwithopen()usingO_NOFOLLOW|O_CLOEXECfollowed byfchmod().✅ Verification: Ensured code compiles. The journal was successfully updated.
PR created automatically by Jules for task 6285201239005346021 started by @acebytes