| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <6396875c-146a-acf5-dd9e-7f93ba1b4bc3@csgroup.eu>
Date: Thu, 6 Oct 2022 19:42:55 +0200
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"patches@...ts.linux.dev" <patches@...ts.linux.dev>,
Andreas Noever <andreas.noever@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Borislav Petkov <bp@...en8.de>,
Catalin Marinas <catalin.marinas@....com>,
Christoph Böhmwalder
<christoph.boehmwalder@...bit.com>, Christoph Hellwig <hch@....de>,
Daniel Borkmann <daniel@...earbox.net>,
Dave Airlie <airlied@...hat.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"David S . Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Florian Westphal <fw@...len.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"H . Peter Anvin" <hpa@...or.com>,
Heiko Carstens <hca@...ux.ibm.com>,
Helge Deller <deller@....de>,
Herbert Xu <herbert@...dor.apana.org.au>,
Huacai Chen <chenhuacai@...nel.org>,
Hugh Dickins <hughd@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
"James E . J . Bottomley" <jejb@...ux.ibm.com>,
Jan Kara <jack@...e.com>, Jason Gunthorpe <jgg@...pe.ca>,
Jens Axboe <axboe@...nel.dk>,
Johannes Berg <johannes@...solutions.net>,
Jonathan Corbet <corbet@....net>,
Jozsef Kadlecsik <kadlec@...filter.org>,
KP Singh <kpsingh@...nel.org>,
Kees Cook <keescook@...omium.org>,
Marco Elver <elver@...gle.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Michael Ellerman <mpe@...erman.id.au>,
Pablo Neira Ayuso <pablo@...filter.org>,
Paolo Abeni <pabeni@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Richard Weinberger <richard@....at>,
Russell King <linux@...linux.org.uk>,
Theodore Ts'o <tytso@....edu>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Thomas Gleixner <tglx@...utronix.de>,
Thomas Graf <tgraf@...g.ch>,
Ulf Hansson <ulf.hansson@...aro.org>,
Vignesh Raghavendra <vigneshr@...com>,
WANG Xuerui <kernel@...0n.name>, Will Deacon <will@...nel.org>,
Yury Norov <yury.norov@...il.com>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
"kasan-dev@...glegroups.com" <kasan-dev@...glegroups.com>,
"kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
"linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
"linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
"linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>,
"linux-parisc@...r.kernel.org" <linux-parisc@...r.kernel.org>,
"linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
"linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
"linux-um@...ts.infradead.org" <linux-um@...ts.infradead.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
"linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
"loongarch@...ts.linux.dev" <loongarch@...ts.linux.dev>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"sparclinux@...r.kernel.org" <sparclinux@...r.kernel.org>,
"x86@...nel.org" <x86@...nel.org>,
Toke Høiland-Jørgensen
<toke@...e.dk>, Chuck Lever <chuck.lever@...cle.com>,
Jan Kara <jack@...e.cz>
Subject: Re: [PATCH v3 3/5] treewide: use get_random_u32() when possible
Le 06/10/2022 à 19:31, Christophe Leroy a écrit :
>
>
> Le 06/10/2022 à 19:24, Jason A. Donenfeld a écrit :
>> Hi Christophe,
>>
>> On Thu, Oct 6, 2022 at 11:21 AM Christophe Leroy
>> <christophe.leroy@...roup.eu> wrote:
>>> Le 06/10/2022 à 18:53, Jason A. Donenfeld a écrit :
>>>> The prandom_u32() function has been a deprecated inline wrapper around
>>>> get_random_u32() for several releases now, and compiles down to the
>>>> exact same code. Replace the deprecated wrapper with a direct call to
>>>> the real function. The same also applies to get_random_int(), which is
>>>> just a wrapper around get_random_u32().
>>>>
>>>> Reviewed-by: Kees Cook <keescook@...omium.org>
>>>> Acked-by: Toke Høiland-Jørgensen <toke@...e.dk> # for sch_cake
>>>> Acked-by: Chuck Lever <chuck.lever@...cle.com> # for nfsd
>>>> Reviewed-by: Jan Kara <jack@...e.cz> # for ext4
>>>> Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
>>>> ---
>>>
>>>> diff --git a/arch/powerpc/kernel/process.c
>>>> b/arch/powerpc/kernel/process.c
>>>> index 0fbda89cd1bb..9c4c15afbbe8 100644
>>>> --- a/arch/powerpc/kernel/process.c
>>>> +++ b/arch/powerpc/kernel/process.c
>>>> @@ -2308,6 +2308,6 @@ void notrace __ppc64_runlatch_off(void)
>>>> unsigned long arch_align_stack(unsigned long sp)
>>>> {
>>>> if (!(current->personality & ADDR_NO_RANDOMIZE) &&
>>>> randomize_va_space)
>>>> - sp -= get_random_int() & ~PAGE_MASK;
>>>> + sp -= get_random_u32() & ~PAGE_MASK;
>>>> return sp & ~0xf;
>>>
>>> Isn't that a candidate for prandom_u32_max() ?
>>>
>>> Note that sp is deemed to be 16 bytes aligned at all time.
>>
>> Yes, probably. It seemed non-trivial to think about, so I didn't. But
>> let's see here... maybe it's not too bad:
>>
>> If PAGE_MASK is always ~(PAGE_SIZE-1), then ~PAGE_MASK is
>> (PAGE_SIZE-1), so prandom_u32_max(PAGE_SIZE) should yield the same
>> thing? Is that accurate? And holds across platforms (this comes up a
>> few places)? If so, I'll do that for a v4.
>>
>
> On powerpc it is always (from arch/powerpc/include/asm/page.h) :
>
> /*
> * Subtle: (1 << PAGE_SHIFT) is an int, not an unsigned long. So if we
> * assign PAGE_MASK to a larger type it gets extended the way we want
> * (i.e. with 1s in the high bits)
> */
> #define PAGE_MASK (~((1 << PAGE_SHIFT) - 1))
>
> #define PAGE_SIZE (1UL << PAGE_SHIFT)
>
>
> So it would work I guess.
But taking into account that sp must remain 16 bytes aligned, would it
be better to do something like ?
sp -= prandom_u32_max(PAGE_SIZE >> 4) << 4;
return sp;
Powered by blists - more mailing lists