linux-kernel - Re: [QUESTION] Kprobes as a module?

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Message-ID: <52488.1337111535@turing-police.cc.vt.edu>
Date:	Tue, 15 May 2012 15:52:15 -0400
From:	valdis.kletnieks@...edu
To:	Namhyung Kim <namhyung.kim@....com>
Cc:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	linux-kernel@...r.kernel.org, Hyeoncheol Lee <cheol.lee@....com>
Subject: Re: [QUESTION] Kprobes as a module?

On Tue, 15 May 2012 17:24:11 +0900, Namhyung Kim said:
> Probably a dumb question :).
> What prevents the kprobes from being built as a module? We want to use
> the kprobes on our systems, but some guys worried about potential
> security problems. So it'd be great if we can enable/load kprobes as
> needed and then disable/unload after using it. Is it a possible senario?

Any troublemaker who has the ability to set a kprobe would probably also
have theability to just re-load the module before setting the kprobe (unless
you go to a *lot* of trouble to compartmentalize the root user).

So it's not clear there's a security benefit from making it a module.  If anything,
it makes it *worse* because you can then surprise a sysadmin who *thought*
they were running a KPROBES=n kernel by loading a module and turning it on...

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