From: Heiko Carstens <heiko.carstens@de.ibm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Laura Abbott <labbott@redhat.com>,
Kees Cook <keescook@chromium.org>,
Jason Wessel <jason.wessel@windriver.com>,
Jonathan Corbet <corbet@lwn.net>,
Russell King <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
"James E.J. Bottomley" <jejb@parisc-linux.org>,
Helge Deller <deller@gmx.de>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Rob Herring <robh@kernel.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
Jessica Yu <jeyu@redhat.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-parisc@vger.kernel.org, linux-s390@vger.kernel.org,
linux-pm@vger.kernel.org, kernel-hardening@lists.openwall.com
Subject: Re: [PATCH 1/2] security: Change name of CONFIG_DEBUG_RODATA
Date: Thu, 19 Jan 2017 12:33:05 +0100 [thread overview]
Message-ID: <20170119113305.GB5110@osiris> (raw)
In-Reply-To: <20170119105646.GA11176@leverpostej>
On Thu, Jan 19, 2017 at 10:56:46AM +0000, Mark Rutland wrote:
> > +config HARDENED_PAGE_MAPPINGS
> > + bool "Mark kernel mappings with stricter permissions (RO/W^X)"
> > + default y
> > + depends on ARCH_HAS_HARDENED_MAPPINGS
> > + help
> > + If this is set, kernel text and rodata memory will be made read-only,
> > + and non-text memory will be made non-executable. This provides
> > + protection against certain security attacks (e.g. executing the heap
> > + or modifying text).
> > +
> > + Unless your system has known restrictions or performance issues, it
> > + is recommended to say Y here.
>
> It's somewhat unfortunate that this means the feature is no longer
> mandatory on arm64 (and s390+x86). We have a boot-time switch to turn
> the protections off, so I was hoping we could make this mandatory on all
> architectures with support.
>
> It would be good to see if we could make this mandatory for arm and
> parisc, or if it really needs to be optional for either of those.
Looks like the config option is a no-op on parisc just like it is on
s390. Irrelavant of the config option at least on s390 the page tables for
kernel text and rodata will be read-only anyway.
This works since ages and I don't see a reason why this should be
changed. Also trying to disable this with the "rodata=" command line option
does not work at least on s390, and I guess this is true for parisc as
well.
The only thing implemented with CONFIG_DEBUG_RODATA on both architectures
is to emit a message that states memory has been protected
(mark_rodata_ro).
This just avoids a wrong "Kernel memory protection disabled." message.
So yes, I'd really like to keep this option mandatory.
next prev parent reply other threads:[~2017-01-19 11:34 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-19 1:29 [RFC][PATCH 0/2] Better hardening names Laura Abbott
2017-01-19 1:29 ` [PATCH 1/2] security: Change name of CONFIG_DEBUG_RODATA Laura Abbott
2017-01-19 7:53 ` Pavel Machek
2017-01-25 11:21 ` Laura Abbott
2017-01-25 13:51 ` Pavel Machek
2017-01-19 10:56 ` Mark Rutland
2017-01-19 11:33 ` Heiko Carstens [this message]
2017-01-19 21:17 ` Helge Deller
2017-01-25 11:37 ` Laura Abbott
2017-01-19 22:00 ` Kees Cook
2017-01-25 11:25 ` Laura Abbott
2017-01-19 21:57 ` Kees Cook
2017-01-19 1:29 ` [PATCH 2/2] security: Change name of CONFIG_DEBUG_SET_MODULE_RONX Laura Abbott
2017-01-19 11:11 ` Mark Rutland
2017-01-19 11:34 ` Heiko Carstens
2017-01-19 11:43 ` Robin Murphy
2017-01-25 11:44 ` Laura Abbott
2017-01-20 5:46 ` kbuild test robot
2017-01-19 22:08 ` [RFC][PATCH 0/2] Better hardening names Kees Cook
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