On Wed, Jul 07, 2021 at 08:13:10PM -0700, Linus Torvalds wrote: > On Wed, Jul 7, 2021 at 6:08 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > From: Mike Rapoport <rppt@xxxxxxxxxxxxx> > > Subject: mm: introduce memfd_secret system call to create "secret" memory areas > > > > Introduce "memfd_secret" system call with the ability to create memory > > areas visible only in the context of the owning process and not mapped not > > only to other processes but in the kernel page tables as well. > > Am I missing something? > > From what I can't tell, this must not be enabled for regular users, > because the secret mapping is effectively mlock'ed into the address > space. > > But there does not seem to be any permission checks or any limits, so > this looks like a trivial way for a bad user to force the kernel to > run out of memory. This feature is off by default and should be explicitly enabled by a system administrator. When it is enabled, a user cannot exceed RLIMIT_MEMLOCK. -- Sincerely yours, Mike.
