From: peterz@infradead.org
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Jessica Yu <jeyu@kernel.org>,
Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Kees Cook <keescook@chromium.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Miroslav Benes <mbenes@suse.cz>,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH v2] module: Harden STRICT_MODULE_RWX
Date: Wed, 12 Aug 2020 12:40:05 +0200 [thread overview]
Message-ID: <20200812104005.GN2674@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAMj1kXF8fm=9CdQykqDbgYCJSP88ezMs3EOosCW+SDi+Lve0zg@mail.gmail.com>
On Wed, Aug 12, 2020 at 10:56:56AM +0200, Ard Biesheuvel wrote:
> The module .lds has BYTE(0) in the section contents to prevent the
> linker from pruning them entirely. The (NOLOAD) is there to ensure
> that this byte does not end up in the .ko, which is more a matter of
> principle than anything else, so we can happily drop that if it helps.
>
> However, this should only affect the PROGBITS vs NOBITS designation,
> and so I am not sure whether it makes a difference.
>
> Depending on where the w^x check occurs, we might simply override the
> permissions of these sections, and strip the writable permission if it
> is set in the PLT handling init code, which manipulates the metadata
> of all these 3 sections before the module space is vmalloc'ed.
What's curious is that this seems the result of some recent binutils
change. Every build with binutils-2.34 (or older) does not seem to
generate these as WAX, but has the much more sensible WA.
I suppose we can change the kernel check and 'allow' W^X for 0 sized
sections, but I think we should still figure out why binutils-2.35 is
now generating WAX sections all of a sudden, it might come bite us
elsewhere.
next prev parent reply other threads:[~2020-08-12 10:40 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-03 17:13 [PATCH v2] module: Harden STRICT_MODULE_RWX Peter Zijlstra
2020-04-03 20:31 ` Kees Cook
2020-04-08 15:32 ` Jessica Yu
2020-04-08 15:43 ` [PATCH] module: break nested ARCH_HAS_STRICT_MODULE_RWX and STRICT_MODULE_RWX #ifdefs Jessica Yu
2020-04-08 15:57 ` [PATCH v2] module: Harden STRICT_MODULE_RWX Peter Zijlstra
2020-04-08 16:20 ` Jessica Yu
2020-08-08 8:12 ` Mauro Carvalho Chehab
2020-08-10 9:25 ` Jessica Yu
2020-08-10 15:06 ` Jessica Yu
2020-08-11 14:34 ` Mauro Carvalho Chehab
2020-08-11 14:55 ` peterz
2020-08-11 15:27 ` Mauro Carvalho Chehab
2020-08-11 16:01 ` Jessica Yu
2020-08-11 16:57 ` Will Deacon
2020-08-11 17:59 ` peterz
2020-08-11 21:29 ` Peter Zijlstra
2020-08-12 8:56 ` Ard Biesheuvel
2020-08-12 10:40 ` peterz [this message]
2020-08-12 11:41 ` Jessica Yu
2020-08-12 13:14 ` H.J. Lu
2020-08-12 12:56 ` Will Deacon
2020-08-12 14:15 ` Szabolcs Nagy
2020-08-12 16:00 ` Jessica Yu
2020-08-12 16:37 ` Ard Biesheuvel
2020-08-12 16:42 ` Szabolcs Nagy
2020-08-13 9:00 ` Will Deacon
2020-08-12 20:00 ` Peter Zijlstra
2020-08-13 8:36 ` Ard Biesheuvel
2020-08-13 13:04 ` Jessica Yu
2020-08-13 13:07 ` Ard Biesheuvel
2020-08-21 12:20 ` Will Deacon
2020-08-21 12:27 ` Ard Biesheuvel
2020-08-21 12:30 ` Will Deacon
2020-08-22 13:47 ` Ard Biesheuvel
2020-08-24 15:24 ` Jessica Yu
2020-08-25 1:54 ` Masahiro Yamada
2020-08-31 9:46 ` Jessica Yu
2020-08-31 10:42 ` Masahiro Yamada
2020-08-31 13:25 ` Ard Biesheuvel
2020-08-31 15:31 ` Jessica Yu
2020-08-31 15:46 ` Masahiro Yamada
2020-09-03 12:37 ` Jessica Yu
2020-09-01 12:51 ` Will Deacon
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