linux-kernel - Re: [PATCH RFC] mm: protect suid binaries against rowhammer with copy-on-read mappings

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 18 Mar 2015 14:41:00 +0300
From:	Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:	"Kirill A. Shutemov" <kirill@...temov.name>,
	Konstantin Khlebnikov <koct9i@...il.com>
CC:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andy Lutomirski <luto@...capital.net>
Subject: Re: [PATCH RFC] mm: protect suid binaries against rowhammer with
 copy-on-read mappings

On 18.03.2015 12:57, Kirill A. Shutemov wrote:
> On Wed, Mar 18, 2015 at 11:30:40AM +0300, Konstantin Khlebnikov wrote:
>> From: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
>>
>> Each user gets private copy of the code thus nobody will be able to exploit
>> pages in the page cache. This works for statically-linked binaries. Shared
>> libraries are still vulnerable, but setting suid bit will protect them too.
>
> Hm. Do we have suid/sgid semantic defiend for non-executables?
>
> To me we should do this for all file private mappings of the suid process
> or don't do it at all.

Yeah, this patch doesn't provide full protection.
That's just a proof-of-concept.

>
> And what about forked suid process which dropped privilages. We still have
> code pages shared.

User can get access to that private copy later but new suid
applications will get their own copy at exec.
Original page-cache pages are never exposed in pte.

>
> I don't think it worth it. The only right way to fix the problem is ECC
> memory.
>

ECC seems good protection until somebody figure out how to break it too.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/