From: Jann Horn <jannh@google.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Topi Miettinen <toiwoton@gmail.com>,
linux-hardening@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>,
kernel list <linux-kernel@vger.kernel.org>,
Kees Cook <keescook@chromium.org>,
Mike Rapoport <rppt@kernel.org>,
Mateusz Jurczyk <mjurczyk@google.com>,
Kernel Hardening <kernel-hardening@lists.openwall.com>
Subject: Re: [PATCH v4] mm: Optional full ASLR for mmap() and mremap()
Date: Wed, 18 Nov 2020 23:42:28 +0100 [thread overview]
Message-ID: <CAG48ez0LyOMnA4Khv9eV1_JpEJhjZy4jJYF=ze3Ha2vSNAfapw@mail.gmail.com> (raw)
In-Reply-To: <20201117165455.GN29991@casper.infradead.org>
On Tue, Nov 17, 2020 at 5:55 PM Matthew Wilcox <willy@infradead.org> wrote:
> On Mon, Oct 26, 2020 at 06:05:18PM +0200, Topi Miettinen wrote:
> > Writing a new value of 3 to /proc/sys/kernel/randomize_va_space
> > enables full randomization of memory mappings created with mmap(NULL,
> > ...). With 2, the base of the VMA used for such mappings is random,
> > but the mappings are created in predictable places within the VMA and
> > in sequential order. With 3, new VMAs are created to fully randomize
> > the mappings. Also mremap(..., MREMAP_MAYMOVE) will move the mappings
> > even if not necessary.
>
> Is this worth it?
>
> https://www.ndss-symposium.org/ndss2017/ndss-2017-programme/aslrcache-practical-cache-attacks-mmu/
Yeah, against local attacks (including from JavaScript), ASLR isn't
very robust; but it should still help against true remote attacks
(modulo crazyness like NetSpectre).
E.g. Mateusz Jurczyk's remote Samsung phone exploit via MMS messages
(https://googleprojectzero.blogspot.com/2020/08/mms-exploit-part-5-defeating-aslr-getting-rce.html)
would've probably been quite a bit harder to pull off if he hadn't
been able to rely on having all those memory mappings sandwiched
together.
next prev parent reply other threads:[~2020-11-18 22:42 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 16:05 [PATCH v4] mm: Optional full ASLR for mmap() and mremap() Topi Miettinen
2020-11-17 16:54 ` Matthew Wilcox
2020-11-17 20:21 ` Topi Miettinen
2020-11-18 17:40 ` Mike Rapoport
[not found] ` <6810b874c8df456b890d1092273b354a@pexch011a.vu.local>
2020-11-18 18:49 ` Cristiano Giuffrida
2020-11-19 9:59 ` Topi Miettinen
[not found] ` <0da9cb0a4d1a494d9ec15404f8decf01@pexch011a.vu.local>
2020-11-19 22:20 ` Cristiano Giuffrida
2020-11-20 8:38 ` Topi Miettinen
2020-11-20 15:27 ` Matthew Wilcox
[not found] ` <d7e759c8ac444aa4b0ba6932563aca00@pexch011a.vu.local>
2020-11-20 14:10 ` Cristiano Giuffrida
2020-11-20 19:37 ` Topi Miettinen
2020-11-18 22:42 ` Jann Horn [this message]
2020-11-19 9:16 ` Topi Miettinen
2020-11-24 18:27 ` Vlastimil Babka
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