Messages in this thread | | | Date | Thu, 5 Jan 2023 22:57:48 +0100 | Subject | Re: [PATCH v14 2/7] mm: add VM_DROPPABLE for designating always lazily freeable mappings | From | Yann Droneaud <> |
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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
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