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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Fri, 6 Jan 2023 13:10:44 -0800
Message-ID: <CAHk-=wgLWcKq2AdrTmTOxJKn6w4oEpEGdipWAah5Xad5-Yii6Q@mail.gmail.com>
Subject: Re: [PATCH v14 2/7] mm: add VM_DROPPABLE for designating always
 lazily freeable mappings
To:     Andy Lutomirski <luto@kernel.org>
Cc:     "Jason A. Donenfeld" <Jason@zx2c4.com>,
        Yann Droneaud <ydroneaud@opteya.com>,
        Ingo Molnar <mingo@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        patches@lists.linux.dev, Thomas Gleixner <tglx@linutronix.de>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Linux API <linux-api@vger.kernel.org>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>,
        "Carlos O'Donell" <carlos@redhat.com>,
        Florian Weimer <fweimer@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>, Jann Horn <jannh@google.com>,
        Christian Brauner <brauner@kernel.org>, linux-mm@kvack.org
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On Fri, Jan 6, 2023 at 12:54 PM Andy Lutomirski <luto@kernel.org> wrote:
>
> I'm going to suggest a very very different approach: fix secret
> storage in memory for real. That is, don't lock "super secret
> sensitive stuff" into memory, and don't wipe it either. *Encrypt* it.

I don't think you're wrong, but people will complain about key
management, and worry about that part instead.

Honestly, this is what SGX and CPU enclaves is _supposed_ to all do
for you, but then nobody uses it for various reasons.

               Linus