https://nalar.dev/tags/memory-files/ Recent content in Memory Files on Nalar Hugo en-us Fri, 18 Sep 2026 00:00:00 +0000 https://nalar.dev/memfd-seals-turn-mutable-anonymous-files-into-explicit-handoff-objects/ Fri, 18 Sep 2026 00:00:00 +0000 https://nalar.dev/memfd-seals-turn-mutable-anonymous-files-into-explicit-handoff-objects/ <p>A process prepares a binary payload in memory, passes a file descriptor to another process, and expects the bytes to remain stable after validation. A plain descriptor does not create that guarantee. If some holder still has write authority, the object can change after a consumer has inspected it, and pathname permissions offer no useful boundary when the object has no ordinary filesystem name.</p> <p>Linux <code>memfd_create()</code> provides an anonymous file backed by memory-like filesystem storage, and file seals can constrain later changes to that file. The useful security property is not anonymity by itself. It is the ability to construct a mutable object, apply irreversible restrictions to that object, then hand out descriptors whose backing file can no longer be changed in the prohibited ways.</p>