linux-kernel - Re: Intercepting system calls

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Message-ID: <CAFLxGvzGWddcSMK58-+OozyQHDNFd+z0-XSNiC47r+VpmXqnyg@mail.gmail.com>
Date:	Fri, 23 Dec 2011 10:26:15 +0100
From:	richard -rw- weinberger <richard.weinberger@...il.com>
To:	Gaurav Saxena <grvsaxena419@...il.com>
Cc:	"J. R. Okajima" <hooanon05@...oo.co.jp>,
	linux-kernel@...r.kernel.org
Subject: Re: Intercepting system calls

On Fri, Dec 23, 2011 at 10:22 AM, Gaurav Saxena <grvsaxena419@...il.com> wrote:
> Hello Richard
>
> On Fri, Dec 23, 2011 at 2:46 PM, richard -rw- weinberger
> <richard.weinberger@...il.com> wrote:
>> On Fri, Dec 23, 2011 at 10:08 AM, Gaurav Saxena <grvsaxena419@...il.com> wrote:
>>> Ok I have seen details of KPROBES, I think it will suit to my
>>> requirements, I just wanted to know a few things,
>>> Can I use probes to prevent unlink of certain files? Also is
>>> CONFIG_KPROBES set to "y" on linux kernels available with distros like
>>> ubuntu?
>>
>> Kprobes allow you to instrument the kernel.
>> AFAIK it enabled by most distros.
> Can I use probes to return immediately ie. without execution of
> original system call. For example I put a entry probe on unlink and
> then on the probe return value unlink code is executed or not. Is that
> possible ?
> Also can I call a userspace function from kernel code? Would that be insecure ?

Using Kprobes you can do nearly anything.
But I would be surprised if you find a acceptable and sane solution.

-- 
Thanks,
//richard
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