Linus Torvalds writes: (Summary) On Wed, Dec 13, 2017 at 10:32 AM, Peter Zijlstra <peterz@infradead.org> wrote:
So I don't mind at all the notion of disallowing access to some special mappings at the vma level. So a VM_NOUSER flag that just disallows get_user_pages entirely I'm ok with.
disallows get_user_pages entirely I'm ok with.
It's the protection keys in particular that I don't like having to worry about. They are subtle and have odd architecture-specific meaning, and needs to be checked at all levels in the page table tree.
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already disallows read(2) from writing to them.So I don't mind at all the notion of disallowing access to some special mappings at the vma level. So a VM_NOUSER flag that just disallows get_user_pages entirely I'm ok with.
disallows get_user_pages entirely I'm ok with.
It's the protection keys in particular that I don't like having to worry about. They are subtle and have odd architecture-specific meaning, and needs to be checked at all levels in the page table tree.