Memfd Seals Turn Mutable Anonymous Files into Explicit Handoff Objects
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. Linux memfd_create() 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.