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:   Tue, 28 Feb 2017 14:52:28 -0800
From:   Andy Lutomirski <luto@...capital.net>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        netdev <netdev@...r.kernel.org>,
        Willem de Bruijn <willemb@...gle.com>,
        Linux API <linux-api@...r.kernel.org>
Subject: Re: [PATCH RFC v2 00/12] socket sendmsg MSG_ZEROCOPY

On Tue, Feb 28, 2017 at 2:40 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Tue, 2017-02-28 at 14:25 -0800, Andy Lutomirski wrote:
>> On Tue, Feb 28, 2017 at 1:47 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
>> > On Tue, 2017-02-28 at 13:09 -0800, Andy Lutomirski wrote:
>> >
>> >> Does this mean that a user program that does a zerocopy send can cause
>> >> a retransmitted segment to contain different data than the original
>> >> segment?  If so, is that okay?
>> >
>> > Same remark applies to sendfile() already
>>
>> True.
>>
>> >, or other zero copy modes
>> > (vmsplice() + splice() )
>>
>> I hate vmsplice().  I thought I remembered it being essentially
>> disabled at some point due to security problems.
>
> Right, zero copy is hard ;)
>
> vmsplice() is not disabled in current kernels, unless I missed
> something.
>

I think you're right.  That being said, from the man page:

The user pages are a gift to the kernel.  The application  may  not
modify this memory ever, otherwise the page cache and on-disk data may
differ.

This is just not okay IMO.

Powered by blists - more mailing lists