linux-kernel - Re: [PATCH] mm: Add new vma flag VM_LOCAL

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, 15 May 2018 15:01:06 +0300
From:   Boaz Harrosh <boazh@...app.com>
To:     Peter Zijlstra <peterz@...radead.org>
CC:     Matthew Wilcox <willy@...radead.org>,
        Jeff Moyer <jmoyer@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, <x86@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Rik van Riel <riel@...hat.com>, Jan Kara <jack@...e.cz>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Amit Golander <Amit.Golander@...app.com>
Subject: Re: [PATCH] mm: Add new vma flag VM_LOCAL_CPU

On 15/05/18 14:47, Peter Zijlstra wrote:
> On Tue, May 15, 2018 at 01:43:23PM +0300, Boaz Harrosh wrote:
>> Yes I know, but that is exactly the point of this flag. I know that this
>> address is only ever accessed from a single core. Because it is an mmap (vma)
>> of an O_TMPFILE-exclusive file created in a core-pinned thread and I allow
>> only that thread any kind of access to this vma. Both the filehandle and the
>> mmaped pointer are kept on the thread stack and have no access from outside.
>>
>> So the all point of this flag is the kernel driver telling mm that this
>> address is enforced to only be accessed from one core-pinned thread.
> 
> What happens when the userspace part -- there is one, right, how else do
> you get an mm to stick a vma in -- simply does a full address range
> probe scan?
> 
> Something like this really needs a far more detailed Changelog that
> explains how its to be used and how it is impossible to abuse. Esp. that
> latter is _very_ important.
> 

Thank you yes. I will try and capture all this thread in the commit message
and as Christoph demanded supply a user code to demonstrate usage.

Thank you for looking
Boaz