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  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, 4 Apr 2017 21:45:36 -0600
From:   Tycho Andersen <>
To:     Kees Cook <>
Cc:     Daniel Borkmann <>,
        Alexei Starovoitov <>,
        LKML <>,
        Network Development <>,
        Mickaël Salaün <>
Subject: Re: [PATCH] ebpf: verify the output of the JIT

Hi Kees,

On Tue, Apr 04, 2017 at 03:17:57PM -0700, Kees Cook wrote:
> On Tue, Apr 4, 2017 at 3:08 PM, Tycho Andersen <> wrote:
> > The goal of this patch is to protect the JIT against an attacker with a
> > write-in-memory primitive. The JIT allocates a buffer which will eventually
> > be marked +x, so we need to make sure that what was written to this buffer
> > is what was intended.
> >
> > We acheive this by building a hash of the instruction buffer as
> > instructions are emittted and then comparing that to a hash at the end of
> > the JIT compile after the buffer has been marked read-only.
> >
> > Signed-off-by: Tycho Andersen <>
> > CC: Daniel Borkmann <>
> > CC: Alexei Starovoitov <>
> > CC: Kees Cook <>
> > CC: Mickaël Salaün <>
> Cool! This closes the race condition on producing the JIT vs going
> read-only. I wonder if it might be possible to make this a more
> generic interface to the BPF which would be allocate the hash, provide
> the update callback during emit, and then do the hash check itself at
> the end of bpf_jit_binary_lock_ro()?

Yes, probably so. I can look into that for the next version.


Powered by blists - more mailing lists