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From: daw@taverner.cs.berkeley.edu (David Wagner)
Newsgroups: isaac.lists.linux-kernel
Subject: Re: seccomp for 2.6.11-rc1-bk8
Date: Fri, 21 Jan 2005 18:59:20 +0000 (UTC)
Organization: University of California, Berkeley
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References: <20050121100606.GB8042@dualathlon.random> <20050121120325.GA2934@elte.hu> <20050121093902.O469@build.pdx.osdl.net>
Reply-To: daw-usenet@taverner.cs.berkeley.edu (David Wagner)
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Chris Wright  wrote:
>Only difference is in number of context switches, and number of running
>processes (and perhaps ease of determining policy for which syscalls
>are allowed).  Although it's not really seccomp, it's just restricted
>syscalls...

There is a simple tweak to ptrace which fixes that: one could add an
API to specify a set of syscalls that ptrace should not trap on.  To get
seccomp-like semantics, the user program could specify {read,write}, but
if the user program ever wants to change its policy, it could change that
set.  Solaris /proc (which is what is used for tracing) has this feature.
I coded up such an extension to ptrace semantics a long time ago, and
it seemed to work fine for me, though of course I am not a ptrace expert.

I don't know whether ptrace + this tweak is a better idea than seccomp.
It is just another option out there that achieves similar functionality.
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