From: Andrew Morton <akpm@linux-foundation.org>
To: Mike Rapoport <rppt@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Borislav Petkov <bp@alien8.de>,
Catalin Marinas <catalin.marinas@arm.com>,
Christopher Lameter <cl@linux.com>,
Dan Williams <dan.j.williams@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
David Hildenbrand <david@redhat.com>,
Elena Reshetova <elena.reshetova@intel.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
James Bottomley <jejb@linux.ibm.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Matthew Wilcox <willy@infradead.org>,
Matthew Garrett <mjg59@srcf.ucam.org>,
Mark Rutland <mark.rutland@arm.com>,
Michal Hocko <mhocko@suse.com>,
Mike Rapoport <rppt@linux.ibm.com>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Peter Zijlstra <peterz@infradead.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Roman Gushchin <guro@fb.com>, Shakeel Butt <shakeelb@google.com>,
Shuah Khan <shuah@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Tycho Andersen <tycho@tycho.ws>, Will Deacon <will@kernel.org>,
linux-api@vger.kernel.org, linux-arch@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org,
x86@kernel.org
Subject: Re: [PATCH v18 0/9] mm: introduce memfd_secret system call to create "secret" memory areas
Date: Wed, 5 May 2021 12:08:06 -0700 [thread overview]
Message-ID: <20210505120806.abfd4ee657ccabf2f221a0eb@linux-foundation.org> (raw)
In-Reply-To: <20210303162209.8609-1-rppt@kernel.org>
On Wed, 3 Mar 2021 18:22:00 +0200 Mike Rapoport <rppt@kernel.org> wrote:
> This is an implementation of "secret" mappings backed by a file descriptor.
>
> The file descriptor backing secret memory mappings is created using a
> dedicated memfd_secret system call The desired protection mode for the
> memory is configured using flags parameter of the system call. The mmap()
> of the file descriptor created with memfd_secret() will create a "secret"
> memory mapping. The pages in that mapping will be marked as not present in
> the direct map and will be present only in the page table of the owning mm.
>
> Although normally Linux userspace mappings are protected from other users,
> such secret mappings are useful for environments where a hostile tenant is
> trying to trick the kernel into giving them access to other tenants
> mappings.
I continue to struggle with this and I don't recall seeing much
enthusiasm from others. Perhaps we're all missing the value point and
some additional selling is needed.
Am I correct in understanding that the overall direction here is to
protect keys (and perhaps other things) from kernel bugs? That if the
kernel was bug-free then there would be no need for this feature? If
so, that's a bit sad. But realistic I guess.
Is this intended to protect keys/etc after the attacker has gained the
ability to run arbitrary kernel-mode code? If so, that seems
optimistic, doesn't it?
I think that a very complete description of the threats which this
feature addresses would be helpful.
next prev parent reply other threads:[~2021-05-05 19:08 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-03 16:22 [PATCH v18 0/9] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2021-03-03 16:22 ` [PATCH v18 1/9] mm: add definition of PMD_PAGE_ORDER Mike Rapoport
2021-03-03 16:22 ` [PATCH v18 2/9] mmap: make mlock_future_check() global Mike Rapoport
2021-03-03 16:22 ` [PATCH v18 3/9] riscv/Kconfig: make direct map manipulation options depend on MMU Mike Rapoport
2021-03-03 16:22 ` [PATCH v18 4/9] set_memory: allow set_direct_map_*_noflush() for multiple pages Mike Rapoport
2021-03-03 16:22 ` [PATCH v18 5/9] set_memory: allow querying whether set_direct_map_*() is actually enabled Mike Rapoport
2021-03-03 16:22 ` [PATCH v18 6/9] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2021-03-03 16:22 ` [PATCH v18 7/9] PM: hibernate: disable when there are active secretmem users Mike Rapoport
2021-03-03 16:22 ` [PATCH v18 8/9] arch, mm: wire up memfd_secret system call where relevant Mike Rapoport
2021-03-03 16:22 ` [PATCH v18 9/9] secretmem: test: add basic selftest for memfd_secret(2) Mike Rapoport
2021-05-05 19:08 ` Andrew Morton [this message]
2021-05-06 15:26 ` [PATCH v18 0/9] mm: introduce memfd_secret system call to create "secret" memory areas James Bottomley
2021-05-06 16:45 ` David Hildenbrand
2021-05-06 17:05 ` James Bottomley
2021-05-06 17:24 ` David Hildenbrand
2021-05-06 23:16 ` Nick Kossifidis
2021-05-07 7:35 ` David Hildenbrand
2021-05-06 17:33 ` Kees Cook
2021-05-06 18:47 ` James Bottomley
2021-05-07 23:57 ` Kees Cook
2021-05-10 18:02 ` Mike Rapoport
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