On 27.10.19 11:17, Mike Rapoport wrote:
From: Mike Rapoport <rppt@xxxxxxxxxxxxx> The mappings created with MAP_EXCLUSIVE are visible only in the context of the owning process and can be used by applications to store secret information that will not be visible not only to other processes but to the kernel as well. The pages in these mappings are removed from the kernel direct map and marked with PG_user_exclusive flag. When the exclusive area is unmapped, the pages are mapped back into the direct map.
Just a thought, the kernel is still able to indirectly read the contents of these pages by doing a kdump from kexec environment, right?. Also, I wonder what would happen if you map such pages via /dev/mem into another user space application and e.g., use them along with kvm [1].
[1] https://lwn.net/Articles/778240/ -- Thanks, David / dhildenb
