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 <roc@xxxxxxxxxxxxx> > Fixes: 86039bd3b4e6 ("userfaultfd: add new syscall to provide memory externalization") > Signed-off-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx> Acked-by: Peter Xu <peterx@xxxxxxxxxx> -- Peter Xu
