From: Yann Droneaud <ydroneaud@opteya.com>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@kernel.org>,
linux-kernel@vger.kernel.org, patches@lists.linux.dev,
tglx@linutronix.de, linux-crypto@vger.kernel.org,
linux-api@vger.kernel.org, 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
Subject: Re: [PATCH v14 2/7] mm: add VM_DROPPABLE for designating always lazily freeable mappings
Date: Thu, 5 Jan 2023 22:57:48 +0100 [thread overview]
Message-ID: <10302240-51ec-0854-2c86-16752d67a9be@opteya.com> (raw)
In-Reply-To: <Y7STv9+p248zr+0a@zx2c4.com>
Hi,
Le 03/01/2023 à 21:44, Jason A. Donenfeld a écrit :
> On Tue, Jan 03, 2023 at 12:15:57PM -0800, Linus Torvalds wrote:
>> On Tue, Jan 3, 2023 at 12:03 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>>> That buffering cannot be done safely currently
>> .. again, this is "your semantics" (the (b) in my humbug list), not
>> necessarily reality for anybody else.
> Yea that's fair. Except, of course, I maintain that my semantics are
> important ones. :)
I concur.
To hold secret material, we need MADV_WIPEONFORK | MADV_DONTDUMP and the side effect of mlock() (pages' content never written to swap), inherited across fork().
And I want mlock() without paying the price.
Jason's proposed semantics, which I call MADV_WIPEONSWAP, provide a mean to hold /unlimited/ amount secrets in userspace memory (not limited by RLIMIT_MEMLOCK).
The only constraint for userspace is to handle the case pages are wiped, which is already the case of userspace arc4random()'s implementation.
Regards.
--
Yann Droneaud
OPTEYA
next prev parent reply other threads:[~2023-01-05 21:58 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230101162910.710293-1-Jason@zx2c4.com>
2023-01-01 16:29 ` Jason A. Donenfeld
2023-01-03 10:50 ` Ingo Molnar
2023-01-03 15:01 ` Jason A. Donenfeld
2023-01-03 18:15 ` Ingo Molnar
2023-01-03 18:51 ` Jason A. Donenfeld
2023-01-03 18:36 ` Andy Lutomirski
2023-01-03 19:05 ` Jason A. Donenfeld
2023-01-03 20:52 ` Andy Lutomirski
2023-01-03 19:19 ` Linus Torvalds
2023-01-03 19:35 ` Jason A. Donenfeld
2023-01-03 19:54 ` Linus Torvalds
2023-01-03 20:03 ` Jason A. Donenfeld
2023-01-03 20:15 ` Linus Torvalds
2023-01-03 20:25 ` Linus Torvalds
2023-01-03 20:44 ` Jason A. Donenfeld
2023-01-05 21:57 ` Yann Droneaud [this message]
2023-01-05 22:57 ` Jason A. Donenfeld
2023-01-06 1:02 ` Linus Torvalds
2023-01-06 2:08 ` Linus Torvalds
2023-01-06 2:42 ` Jason A. Donenfeld
2023-01-06 20:53 ` Andy Lutomirski
2023-01-06 21:10 ` Linus Torvalds
2023-01-10 11:01 ` Dr. Greg
2023-01-06 21:36 ` Jason A. Donenfeld
2023-01-06 21:42 ` Matthew Wilcox
2023-01-06 22:06 ` Linus Torvalds
2023-01-06 2:14 ` Jason A. Donenfeld
2023-01-09 10:34 ` Florian Weimer
2023-01-09 14:28 ` Linus Torvalds
2023-01-11 7:27 ` Eric Biggers
2023-01-11 12:07 ` Linus Torvalds
2023-01-01 16:29 ` [PATCH v14 3/7] x86: mm: Skip faulting instruction for VM_DROPPABLE faults Jason A. Donenfeld
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