Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Message-ID: <9f337efdf226e51e3f5699243623e5de7505ac94.camel@linux.intel.com>
Subject: Re: [RFC PATCH 08/11] x86: Add support for finer grained KASLR
From:   Kristen Carlson Accardi <kristen@linux.intel.com>
To:     Peter Zijlstra <peterz@infradead.org>,
        Kees Cook <keescook@chromium.org>
Cc:     tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
        arjan@linux.intel.com, rick.p.edgecombe@intel.com, x86@kernel.org,
        linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com
Date:   Thu, 06 Feb 2020 09:25:01 -0800
In-Reply-To: <20200206145253.GT14914@hirez.programming.kicks-ass.net>
References: <20200205223950.1212394-1-kristen@linux.intel.com>
         <20200205223950.1212394-9-kristen@linux.intel.com>
         <20200206103830.GW14879@hirez.programming.kicks-ass.net>
         <202002060356.BDFEEEFB6C@keescook>
         <20200206145253.GT14914@hirez.programming.kicks-ass.net>
Content-Type: text/plain; charset="UTF-8"
User-Agent: Evolution 3.30.5 (3.30.5-1.fc29) 
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, 2020-02-06 at 15:52 +0100, Peter Zijlstra wrote:
> On Thu, Feb 06, 2020 at 04:06:17AM -0800, Kees Cook wrote:
> > On Thu, Feb 06, 2020 at 11:38:30AM +0100, Peter Zijlstra wrote:
> > > On Wed, Feb 05, 2020 at 02:39:47PM -0800, Kristen Carlson Accardi
> > > wrote:
> > > > +static long __start___ex_table_addr;
> > > > +static long __stop___ex_table_addr;
> > > > +static long _stext;
> > > > +static long _etext;
> > > > +static long _sinittext;
> > > > +static long _einittext;
> > > 
> > > Should you not also adjust __jump_table, __mcount_loc,
> > > __kprobe_blacklist and possibly others that include text
> > > addresses?
> > 
> > These don't appear to be sorted at build time. 
> 
> The ORC tables are though:
> 
>   57fa18994285 ("scripts/sorttable: Implement build-time ORC unwind
> table sorting")
> 
> > AIUI, the problem with
> > ex_table and kallsyms is that they're preprocessed at build time
> > and
> > opaque to the linker's relocation generation.
> 
> I was under the impression these tables no longer had relocation
> data;
> that since they're part of the main kernel, the final link stage
> could
> completely resolve them.
> 
> That said, I now see we actually have .rela__extable
> .rela.orc_unwind_ip
> etc.

That's right - all of these tables that you mention had relocs and thus
I did not have to do anything special for them. The orc_unwind_ip
tables get sorted during unwind_init(). If they are needed earlier than
that, then they could be re-sorted like we do with the exception table.