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Donenfeld" , Linus Torvalds Cc: Andy Lutomirski , Ingo Molnar , 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 , Adhemerval Zanella Netto , Carlos O'Donell , Florian Weimer , Arnd Bergmann , Jann Horn , Christian Brauner , linux-mm@kvack.org References: <20230101162910.710293-1-Jason@zx2c4.com> <20230101162910.710293-3-Jason@zx2c4.com> From: Yann Droneaud Organization: OPTEYA In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 0DB3E4000D X-Rspamd-Server: rspam01 X-Stat-Signature: 5uhxjniitdeox7erambc5qp8twepeiuu X-HE-Tag: 1672955888-373517 X-HE-Meta: U2FsdGVkX1+BfoxY2C5GJ0/ZT2m2uXovPIN0tMWnAbN7lUoiFuwpp6CiLJONJl5g5wdBOpq4CH3UccA03QsGyA0N1kn/qe0TKv0USjPohxkxHaHITn70DKoOh07YJhzLiTI3AvKlbI5ImDDuKErGHHGQvenb3Yy6xo24nJ5/OI+gwLJH7OXNxwXrRASTU7xUxWE+0b8Z7KI7dUr4AwQ9ltmDfQOYhSwR1BD4sGgk37Y0wI/OdD9Ux/G2VWRefYHkGJhofN9FoveXp/JkT1qlyN8To2g7z1asS188xiCcE+UzM5f/ND2pvawnjAmOqKgPdcam2Dvw3l5XdnzLgasHrn9zv7ymX/FLwfgy/DIPhYhBedQtfTmrimVFl1cDs+VHFvFK6t4tTrvd6IGUkApeVSxpUTPq38ugCOMAYiBadoTyIqnhw3F/Ij3GKffN6dUQr6cMYbOdEaEb3IKBtGbDL9tEodPDsZKqVp6Cx3csPoIiZBwxbLBt00SRjP77AUhXZIo5gfj6Zw3vjuFQ0W4Ww7ccRIKmjAPvxuorzHsxL3RoY25r9BWcbjsC6N6/OWfUarx4f7Ru3E0deTppGCbiO9QxBGiu5HfnFAjc+/i7SWDlGeFjB1+ow26mnhaAnGs+CdqHoX6oRGiWQQ6gE1FbwgfN/E+yQaoByYiQaq9wzplLUUC5St8HNrcTktY+1wpTV8lL5zgSSjxU8rGkgX5MaMfKQvxucsy//h8MPCXQabE08TTMOj8TBrZQ5w7Jgxo8cmsTpyRrDWY71CKvmK7dUAPjNnq7ib95YjkaFbV/eHESxq3BcWsy/OwWQid5RYA28nmZFs7MniRAG7R7wEWY8A== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000443, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 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