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From: Dan Williams <dan.j.williams@intel.com>
Date: Thu, 11 Jan 2018 07:58:55 -0800
Message-ID: <CAPcyv4jRbHZH9OWD_6DmeA=MGr+2cy83LGqMCjK_nj79Pug4NQ@mail.gmail.com>
Subject: Re: [PATCH 00/18] prevent bounds-check bypass via speculative execution
To: Jiri Kosina <jikos@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Alan Cox <alan.cox@intel.com>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Will Deacon <will.deacon@arm.com>,
        Solomon Peachy <pizza@shaftnet.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Christian Lamparter <chunkeey@googlemail.com>,
        Elena Reshetova <elena.reshetova@intel.com>,
        linux-arch@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
        "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>,
        linux-scsi <linux-scsi@vger.kernel.org>,
        Jonathan Corbet <corbet@lwn.net>, X86 ML <x86@kernel.org>,
        Ingo Molnar <mingo@redhat.com>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        Zhang Rui <rui.zhang@intel.com>,
        "Linux-media@vger.kernel.org" <linux-media@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, Jan Kara <jack@suse.com>,
        Eduardo Valentin <edubezval@gmail.com>,
        Al Viro <viro@zeniv.linux.org.uk>, qla2xxx-upstream@qlogic.com,
        Thomas Gleixner <tglx@linutronix.de>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Arjan van de Ven <arjan@linux.intel.com>,
        Kalle Valo <kvalo@codeaurora.org>,
        Alan Cox <alan@linux.intel.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Greg KH <gregkh@linuxfoundation.org>,
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        "Eric W. Biederman" <ebiederm@xmission.com>,
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        Linus Torvalds <torvalds@linux-foundation.org>,
        "David S. Miller" <davem@davemloft.net>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Alexei Starovoitov <ast@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org

On Thu, Jan 11, 2018 at 1:54 AM, Jiri Kosina <jikos@kernel.org> wrote:
> On Tue, 9 Jan 2018, Josh Poimboeuf wrote:
>
>> On Tue, Jan 09, 2018 at 11:44:05AM -0800, Dan Williams wrote:
>> > On Tue, Jan 9, 2018 at 11:34 AM, Jiri Kosina <jikos@kernel.org> wrote:
>> > > On Fri, 5 Jan 2018, Dan Williams wrote:
>> > >
>> > > [ ... snip ... ]
>> > >> Andi Kleen (1):
>> > >>       x86, barrier: stop speculation for failed access_ok
>> > >>
>> > >> Dan Williams (13):
>> > >>       x86: implement nospec_barrier()
>> > >>       [media] uvcvideo: prevent bounds-check bypass via speculative execution
>> > >>       carl9170: prevent bounds-check bypass via speculative execution
>> > >>       p54: prevent bounds-check bypass via speculative execution
>> > >>       qla2xxx: prevent bounds-check bypass via speculative execution
>> > >>       cw1200: prevent bounds-check bypass via speculative execution
>> > >>       Thermal/int340x: prevent bounds-check bypass via speculative execution
>> > >>       ipv6: prevent bounds-check bypass via speculative execution
>> > >>       ipv4: prevent bounds-check bypass via speculative execution
>> > >>       vfs, fdtable: prevent bounds-check bypass via speculative execution
>> > >>       net: mpls: prevent bounds-check bypass via speculative execution
>> > >>       udf: prevent bounds-check bypass via speculative execution
>> > >>       userns: prevent bounds-check bypass via speculative execution
>> > >>
>> > >> Mark Rutland (4):
>> > >>       asm-generic/barrier: add generic nospec helpers
>> > >>       Documentation: document nospec helpers
>> > >>       arm64: implement nospec_ptr()
>> > >>       arm: implement nospec_ptr()
>> > >
>> > > So considering the recent publication of [1], how come we all of a sudden
>> > > don't need the barriers in ___bpf_prog_run(), namely for LD_IMM_DW and
>> > > LDX_MEM_##SIZEOP, and something comparable for eBPF JIT?
>> > >
>> > > Is this going to be handled in eBPF in some other way?
>> > >
>> > > Without that in place, and considering Jann Horn's paper, it would seem
>> > > like PTI doesn't really lock it down fully, right?
>> >
>> > Here is the latest (v3) bpf fix:
>> >
>> > https://patchwork.ozlabs.org/patch/856645/
>> >
>> > I currently have v2 on my 'nospec' branch and will move that to v3 for
>> > the next update, unless it goes upstream before then.
>
> Daniel, I guess you're planning to send this still for 4.15?

It's pending in the bpf.git tree:

    https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=b2157399cc9

>> That patch seems specific to CONFIG_BPF_SYSCALL.  Is the bpf() syscall
>> the only attack vector?  Or are there other ways to run bpf programs
>> that we should be worried about?
>
> Seems like Alexei is probably the only person in the whole universe who
> isn't CCed here ... let's fix that.

He will be cc'd on v2 of this series which will be available later today.