Hooking a system call.

[rohan puri]

On Wed, Mar 28, 2012 at 9:16 AM, V.Ravikumar
<ravikumar.vallabhu at gmail.com>wrote:

>
>
> On Mon, Mar 26, 2012 at 1:18 PM, Mulyadi Santosa <
> mulyadi.santosa at gmail.com> wrote:
>
>> Hi...
>>
>> On Mon, Mar 26, 2012 at 11:45, V.Ravikumar <ravikumar.vallabhu at gmail.com>
>> wrote:
>> > As part of auditing purpose I need to intercept/hook open/read/write
>> system
>> > calls.
>> >
>> > As I was lack of knowledge into kernel development.Could somebody help
>> me
>> > out here ?
>> > I'm working on RHEL-5 machine with Linux kernel version 2.6.18
>> > Thanks & Regards,
>> > Ravi
>>
>> IMHO you better use SystemTap, which is based on Kprobes. It can be
>> used to hook into almost every part of kernel system, with very less
>> overhead.
>>
>>
> Yes SystemTap is one of the elegant way to hook system calls.
>
> But I need one help while hooking write system call. I need to print the
> file name also, but file name is not passed to write system call. How can I
> get the file for write (or sys_write ) system call.
>
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>
Hi,

One way to do this is to map the physical page to new virtual page and make
that page RW and then replace with ur handlers. Refer vmap()

-Rohan
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