Match Linux message-queue unlink permissions - #15195
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The mqfs root introduced in 61cbf77 was read-only (0555), so mq_unlink rejected queue owners without DAC override capabilities. Linux instead creates a world-writable sticky directory [1]. Use the same directory mode and enforce sticky ownership checks on the registry unlink path, which bypasses the normal VFS unlink checks. Drop DAC bypass in the existing queue permission tests and check that another unprivileged user cannot unlink the queue. [1]: https://github.com/torvalds/linux/blob/830b3c68c/ipc/mqueue.c#L404-L422 Assisted-by: OpenAI Codex
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Match Linux message-queue unlink permissions
The mqfs root introduced in 61cbf77 was read-only (0555), so mq_unlink rejected queue owners without DAC override capabilities. Linux instead creates a world-writable sticky directory 1.
Use the same directory mode and enforce sticky ownership checks on the registry unlink path, which bypasses the normal VFS unlink checks. Drop DAC bypass in the existing queue permission tests and check that another unprivileged user cannot unlink the queue.
Assisted-by: OpenAI Codex
FUTURE_COPYBARA_INTEGRATE_REVIEW=#15159 from tamird:mq-permission-capabilities 768231d