Re: [RFC PATCH RESEND] userfaultfd: open userfaultfds with O_RDONLY
From: Peter Xu <peterx@redhat.com>
Date: 2022-07-12 14:22:34
Also in:
linux-fsdevel, linux-mm, lkml, selinux
On Fri, Jul 08, 2022 at 11:34:51AM +0200, Ondrej Mosnacek wrote:
Since userfaultfd doesn't implement a write operation, it is more appropriate to open it read-only. When userfaultfds are opened read-write like it is now, and such fd is passed from one process to another, SELinux will check both read and write permissions for the target process, even though it can't actually do any write operation on the fd later. Inspired by the following bug report, which has hit the SELinux scenario described above: https://bugzilla.redhat.com/show_bug.cgi?id=1974559 Reported-by: Robert O'Callahan <redacted> Fixes: 86039bd3b4e6 ("userfaultfd: add new syscall to provide memory externalization") Signed-off-by: Ondrej Mosnacek <redacted>
Acked-by: Peter Xu <peterx@redhat.com> -- Peter Xu