From: Alexander Lobakin <alexandr.lobakin@intel.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Alexander Lobakin <alexandr.lobakin@intel.com>,
linux-hardening@vger.kernel.org, x86@kernel.org,
Jesse Brandeburg <jesse.brandeburg@intel.com>,
Kristen Carlson Accardi <kristen@linux.intel.com>,
Kees Cook <keescook@chromium.org>,
Miklos Szeredi <miklos@szeredi.hu>,
Ard Biesheuvel <ardb@kernel.org>, Tony Luck <tony.luck@intel.com>,
Bruce Schlobohm <bruce.schlobohm@intel.com>,
Jessica Yu <jeyu@kernel.org>, kernel test robot <lkp@intel.com>,
Miroslav Benes <mbenes@suse.cz>,
Evgenii Shatokhin <eshatokhin@virtuozzo.com>,
Jonathan Corbet <corbet@lwn.net>,
Masahiro Yamada <masahiroy@kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
Nick Desaulniers <ndesaulniers@google.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Arnd Bergmann <arnd@arndb.de>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Nathan Chancellor <nathan@kernel.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Marios Pomonis <pomonis@google.com>,
Sami Tolvanen <samitolvanen@google.com>,
"H.J. Lu" <hjl.tools@gmail.com>, Nicolas Pitre <nico@fluxnic.net>,
linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
linux-arch@vger.kernel.org, live-patching@vger.kernel.org,
llvm@lists.linux.dev
Subject: Re: [PATCH v9 03/15] kallsyms: Hide layout
Date: Mon, 3 Jan 2022 16:40:23 +0100 [thread overview]
Message-ID: <20220103154023.7326-1-alexandr.lobakin@intel.com> (raw)
In-Reply-To: <Yc40UKmylVh38vl5@zn.tnic>
From: Borislav Petkov <bp@alien8.de>
Date: Thu, 30 Dec 2021 23:36:00 +0100
> On Thu, Dec 23, 2021 at 01:21:57AM +0100, Alexander Lobakin wrote:
> > Subject: Re: [PATCH v9 03/15] kallsyms: Hide layout
>
> That title is kinda laconic...
"kallsyms: randomize /proc/kallsyms output order"?
>
> > From: Kristen Carlson Accardi <kristen@linux.intel.com>
> >
> > This patch makes /proc/kallsyms display in a random order, rather
>
> Avoid having "This patch" or "This commit" in the commit message. It is
> tautologically useless.
>
> Also, do
>
> $ git grep 'This patch' Documentation/process
>
> for more details.
Goes straight from the original series. Worth changing anyways.
>
> > than sorted by address in order to hide the newly randomized address
> > layout.
>
> Sorted by address?
>
> My /proc/kallsyms says
>
> $ awk '{ print $1 }' /proc/kallsyms | uniq -c
> 119086 0000000000000000
>
> so all the addresses are 0. Aha, and when I list them as root, only then
> I see non-null addresses.
>
> So why do we that patch at all?
It displays zeros for non-roots, but the symbols are still sorted by
their addresses. As a result, if you leak one address, you could
determine some others.
This is especially critical with FG-KASLR as its text layout is
random each time and sorted /proc/kallsyms would make the entire
feature useless.
>
> > alobakin:
> > Don't depend FG-KASLR and always do that for unpriviledged accesses
>
> Unknown word [unpriviledged] in commit message, suggestions:
> ['unprivileged', 'underprivileged', 'privileged']
I either have some problems with checkpatch + codespell, or they
missed all that typos you're noticing. Thanks, and apologies =\
>
> > as suggested by several folks.
> > Also, introduce and use a shuffle_array() macro which shuffles an
> > array using Fisher-Yates.
>
> Fisher-Yates what?
>
> /me goes and looks at the wikipedia article.
>
> Aha, a Fisher-Yates shuffle algoithm.
>
> Don't be afraid to explain more in your commit messages and make them
> more reader-friendly.
Sure.
This patch initially was at the tail of the set, after the commits
where this algo is mentioned several times in a more detailed
manner, but I moved it to the head then as the requests for doing
this unconditionally converted it to a pre-requisite.
>
> > We'll make use of it several more times
> > later on.
>
> Not important for this commit.
>
> ...
>
> --
> Regards/Gruss,
> Boris.
>
> https://people.kernel.org/tglx/notes-about-netiquette
Thanks!
Al
next prev parent reply other threads:[~2022-01-03 15:41 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-23 0:21 [PATCH v9 00/15] Function Granular KASLR Alexander Lobakin
2021-12-23 0:21 ` [PATCH v9 01/15] modpost: fix removing numeric suffixes Alexander Lobakin
2021-12-23 16:19 ` Borislav Petkov
2021-12-27 18:22 ` Alexander Lobakin
2021-12-27 21:26 ` Borislav Petkov
2021-12-28 17:03 ` Alexander Lobakin
2022-01-03 13:07 ` Miroslav Benes
2021-12-23 0:21 ` [PATCH v9 02/15] livepatch: use `-z unique-symbol` if available to nuke pos-based search Alexander Lobakin
2021-12-30 11:10 ` Borislav Petkov
2021-12-30 18:31 ` Fāng-ruì Sòng
2022-01-03 13:55 ` Miroslav Benes
2022-01-03 16:06 ` Alexander Lobakin
2022-01-05 3:24 ` Fāng-ruì Sòng
2022-01-03 16:29 ` Alexander Lobakin
2022-01-03 13:44 ` Miroslav Benes
2021-12-23 0:21 ` [PATCH v9 03/15] kallsyms: Hide layout Alexander Lobakin
2021-12-30 22:36 ` Borislav Petkov
2022-01-03 15:40 ` Alexander Lobakin [this message]
2022-01-03 16:59 ` Borislav Petkov
2022-01-05 18:46 ` Borislav Petkov
2021-12-23 0:21 ` [PATCH v9 04/15] arch: introduce ASM function sections Alexander Lobakin
2022-01-17 21:08 ` Borislav Petkov
2022-01-17 21:38 ` Nicolas Pitre
2022-01-17 21:55 ` Borislav Petkov
2021-12-23 0:21 ` [PATCH v9 05/15] x86: support " Alexander Lobakin
2022-01-21 15:08 ` Borislav Petkov
2022-01-26 14:49 ` Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 06/15] x86: decouple ORC table sorting into a separate file Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 07/15] Makefile: Add build and config option for CONFIG_FG_KASLR Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 08/15] x86/tools: Add relative relocs for randomized functions Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 09/15] x86: Add support for function granular KASLR Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 10/15] FG-KASLR: use a scripted approach to handle .text.* sections Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 11/15] x86/boot: allow FG-KASLR to be selected Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 12/15] module: Reorder functions Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 13/15] module: use a scripted approach for FG-KASLR Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 14/15] Documentation: add documentation " Alexander Lobakin
2021-12-23 0:22 ` [PATCH v9 15/15] maintainers: add MAINTAINERS entry " Alexander Lobakin
2021-12-23 15:15 ` [PATCH v9 00/15] Function Granular KASLR Alexander Lobakin
2021-12-23 15:40 ` Peter Zijlstra
2021-12-24 6:38 ` Christoph Hellwig
2021-12-27 18:33 ` Alexander Lobakin
2021-12-30 9:00 ` Christoph Hellwig
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220103154023.7326-1-alexandr.lobakin@intel.com \
--to=alexandr.lobakin@intel.com \
--cc=ardb@kernel.org \
--cc=arnd@arndb.de \
--cc=bp@alien8.de \
--cc=bruce.schlobohm@intel.com \
--cc=corbet@lwn.net \
--cc=dave.hansen@linux.intel.com \
--cc=davem@davemloft.net \
--cc=eshatokhin@virtuozzo.com \
--cc=herbert@gondor.apana.org.au \
--cc=hjl.tools@gmail.com \
--cc=hpa@zytor.com \
--cc=jesse.brandeburg@intel.com \
--cc=jeyu@kernel.org \
--cc=jpoimboe@redhat.com \
--cc=keescook@chromium.org \
--cc=kristen@linux.intel.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=live-patching@vger.kernel.org \
--cc=lkp@intel.com \
--cc=llvm@lists.linux.dev \
--cc=luto@kernel.org \
--cc=masahiroy@kernel.org \
--cc=mbenes@suse.cz \
--cc=mhiramat@kernel.org \
--cc=michal.lkml@markovi.net \
--cc=miklos@szeredi.hu \
--cc=mingo@redhat.com \
--cc=nathan@kernel.org \
--cc=ndesaulniers@google.com \
--cc=nico@fluxnic.net \
--cc=peterz@infradead.org \
--cc=pomonis@google.com \
--cc=samitolvanen@google.com \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=will@kernel.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).