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Date: Sat, 6 Aug 2011 15:20:52 +0200
From: Tejun Heo <tj@kernel.org>
To: Andrew Lutomirski <luto@mit.edu>
Cc: Matt Helsley <matthltc@us.ibm.com>, Pavel Emelyanov <xemul@parallels.com>,
        Nathan Lynch <ntl@pobox.com>, Oren Laadan <orenl@cs.columbia.edu>,
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        "David S. Miller" <davem@davemloft.net>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
Subject: Re: [EXAMPLE CODE] Parasite thread injection and TCP connection
 hijacking
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Hello,

On Sat, Aug 06, 2011 at 09:15:45AM -0400, Andrew Lutomirski wrote:
> On Sat, Aug 6, 2011 at 9:00 AM, Tejun Heo <tj@kernel.org> wrote:
> > Actually, the only thing we need on x86_64 is two bytes for the
> > syscall instruction because all params are passed through registers
> > anyway.  We can just set up parameters for mmap, turn on single step,
> > point %rip to syscall in the vsyscall page.  So, either way, I don't
> > think this would be too difficult to solve.
> 
> Not any more -- that syscall instruction is gone as of 3.1.  You could
> search through the vdso to find a syscall, but that seems fragile.
> 
> Why not just add a ptrace command to issue a syscall?

Yeah, maybe.  If this thing proves to be useful enough and looking for
a page to poke under proc too cumbersome.  I'm not against it but
don't really see strong need either at this point.

Thanks.

-- 
tejun