RE: Help in adding userspace function hooks to kernel

["Rajendra Stalekar" <rajendra.stalekar@xxxxxxxxx>]

Hi Pravin and Rajat,

I have already registered a netfilter hook function which accepts/drop TCP packets and call it in init_module. My query here is how do I test the packets are captured or dropped.

If it’s a hook like NF_IP_LOCAL_PROCESS, then it means it is destined for this host, so to test this do I need to write a test socket client-server program at user-level.

Please reply.

 

Regards,

Rajendra Stalekar(extn 2016)

Location:- Akruti

Mobile no:- +91 9860501143

 

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From: kernelnewbies-bounce@xxxxxxxxxxxx [mailto:kernelnewbies-bounce@xxxxxxxxxxxx] On Behalf Of Pravin
Sent: Wednesday, July 11, 2007 10:23 AM
To: Rajat Jain
Cc: kernelnewbies@xxxxxxxxxxxx
Subject: Re: Help in adding userspace function hooks to kernel

 

 

On 7/9/07, Rajat Jain <Rajat.Jain@xxxxxxxxxxxx> wrote:

Hi Pravin,

> ...
> I need to provide a hook from kernel-space to userspace.
> ...
> ...
> I am also looking for possibility for pausing the execution
> kernel thread till userspace function acknowlages the data
> and take certain action on it.
> ...

This is not possible. And well, as others may advice, not at all logical. If you really need access to kernel data-structures and you feel your code needs to be called in middle of some kernel code path, a better decision might be to include your code in the kernel space itself.

Sitting in the userspace, the closest you can get to it is using call_usermodehelper() that allows you call a userspace binary.

Thanx for info
I will re-considar my decision about putting my code in userspace.
I was facing some problems to do my work from kernel space.
my code need to take some decision based on some policy file,
and reading policies from a file.
This is the reason I am not comfortable in putting my code in kernel.
as reading file from kernel space is little tedious thing, and even thats not
recemended. thats y i am confused about how to tackle this problem.
 

 

Thanks,

Rajat

--
Pravin Shinde