📚 Memory Sealing 'mseal' System Call Merged For Linux 6.10

"Merged this Friday evening into the Linux 6.10 kernel is the new mseal() system call for memory sealing," reports Phoronix: The mseal system call was led by Jeff Xu of Google's Chrome team. The goal with memory sealing is to also protect the memory mapping itself against modification. The new mseal Linux documentation explains: "Modern CPUs support memory permissions such as RW and NX bits. The memory permission feature improves security stance on memory corruption bugs, i.e. the attacker can't just write to arbitrary memory and point the code to it, the memory has to be marked with X bit, or else an exception will happen. Memory sealing additionally protects the mapping itself against modifications. This is useful to mitigate memory corruption issues where a corrupted pointer is passed to a memory management system... Memory sealing can automatically be applied by the runtime loader to seal .text and .rodata pages and applications can additionally seal security-critical data at runtime. A similar feature already exists in the XNU kernel with the VM_FLAGS_PERMANENT flag and on OpenBSD with the mimmutable syscall." The mseal system call is designed to be used by the likes of the GNU C Library "glibc" while loading ELF executables to seal non-writable memory segments or by the Google Chrome web browser and other browsers for protecting security sensitive data structures.

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