Subject: Re: [PATCH 2/2] x86-64: seccomp: fix 32/64 syscall hole

From: Ingo Molnar <[email-masked]>
Date: Wed, 6 May 2009 23:54:50 +0200

* Markus Gutschke (顧孟勤) <[email-masked]> wrote:

> On Wed, May 6, 2009 at 14:29, Ingo Molnar <[email-masked]> wrote:
> > That's a pretty interesting usage. What would be fallback mode you
> > are using if the kernel doesnt have seccomp built in? Completely
> > non-sandboxed? Or a ptrace/PTRACE_SYSCALL based sandbox?
> 
> Ptrace has performance and/or reliability problems when used to 
> sandbox threaded applications due to potential race conditions 
> when inspecting system call arguments. We hope that we can avoid 
> this problem with seccomp. It is very attractive that kernel 
> automatically terminates any application that violates the very 
> well-defined constraints of the sandbox.
> 
> In general, we are currently exploring different options based on 
> general availability, functionality, and complexity of 
> implementation. Seccomp is a good middle ground that we expect to 
> be able to use in the medium term to provide an acceptable 
> solution for a large segment of Linux users. Although the 
> restriction to just four unfiltered system calls is painful.

Which other system calls would you like to use? Futexes might be 
one, for fast synchronization primitives?

	Ingo