netdev - Re: [PATCH bpf-next 0/7] Introduce BPF trampoline

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]

Message-ID: <20191105154709.utmzm6qvtlux4hww@ast-mbp.dhcp.thefacebook.com>
Date:   Tue, 5 Nov 2019 07:47:11 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Alexei Starovoitov <ast@...nel.org>, davem@...emloft.net,
        daniel@...earbox.net, peterz@...radead.org, x86@...nel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org, kernel-team@...com,
        Thomas Gleixner <tglx@...utronix.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH bpf-next 0/7] Introduce BPF trampoline

On Tue, Nov 05, 2019 at 10:40:24AM -0500, Steven Rostedt wrote:
> On Tue, 5 Nov 2019 06:31:56 -0800
> Alexei Starovoitov <alexei.starovoitov@...il.com> wrote:
> 
> > Steven,
> > look slike your branch hasn't been updated in 13 days.
> > Are you still planning to fix the bugs and send it in for the merge window?
> > I cannot afford to wait a full release, since I have my own follow for
> > XDP/networking based on this and other folks are building their stuff on top of
> > BPF trampoline too. So I'm thinking for v2 I will switch to using text_poke()
> > and add appropriate guard checks, so it will be safe out of the box without
> > ftrace dependency. If register_ftrace_direct() indeed comes in soon I'll
> > switch to that and will make bpf trampoline to co-operate with ftrace.
> > text_poke approach will make it such that what ever comes first to trace the
> > fentry (either bpf trampoline or ftrace) will grab the nop and the other system
> > will not be able to attach. That's safe and correct, but certainly not nice
> > long term. So the fix will be needed. The key point that switching to text_poke
> > will remove the register_ftrace_direct() dependency, unblock bpf developers and
> > will give you time to land your stuff at your pace.
> 
> Alexei,
> 
> I am still working on it, and if it seems stable enough I will submit
> it for this merge window, but there's no guarantees. It's ready when
> it's ready. I gave 5 talks last week (4 in Lyon, and one is Sofia,
> Bulgaria), thus I did not have time to work on it then. I'm currently
> in the Sofia office, and I got a version working that seems to be
> stable. But I still have to break it up into a patch series, and run it
> through more stress tests.
> 
> If you have to wait you may need to wait. The Linux kernel isn't
> something that is suppose to put in temporary hacks, just to satisfy
> someone's deadline.

Ok. I will switch to text_poke and will make it hack free.
ftrace mechanisms are being replaced by text_poke anyway.