Re: [PATCH v2 1/2] mm: Implement memory-deny-write-execute as a prctl
From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2023-01-23 16:22:25
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On Mon, Jan 23, 2023 at 05:10:08PM +0100, David Hildenbrand wrote:
On 23.01.23 17:04, Catalin Marinas wrote:quoted
On Mon, Jan 23, 2023 at 01:53:46PM +0100, David Hildenbrand wrote:quoted
That at least would be then similar to how we handle mmaped files: if the file is not executable, we clear VM_MAYEXEC. If the file is not writable, we clear VM_MAYWRITE.We still allow VM_MAYWRITE for private mappings, though we do clear VM_MAYEXEC if not executable. It would be nice to use VM_MAY* flags for this logic but we can only emulate MDWE if we change the semantics of 'MAY': only check the 'MAY' flags for permissions being changed (e.g. allow PROT_EXEC if the vma is already VM_EXEC even if !VM_MAYEXEC). Another issue is that we end up with some weird combinations like having VM_EXEC without VM_MAYEXEC (maybe that's fine).No, we wouldn't want VM_EXEC if VM_MAYEXEC is not set. I don't immediately see how that would happen.
You are right, this shouldn't happen. What I had in mind was the current MDWE model where after an mmap(PROT_EXEC), any mprotect(PROT_EXEC) is denied. But this series departs slightly from this since we want to allow PROT_EXEC if already executable. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel