On 09/23/2011 02:04 PM, rohan puri wrote:

On Fri, Sep 23, 2011 at 2:00 PM, Abhijit Pawar <apawar.linux@gmail.com 
<mailto:apawar.linux@gmail.com>> wrote:

    On 09/23/2011 01:01 PM, Rajat Sharma wrote:

            Untidy way : -
            Yes, you can do that by registering a new binary format
            handler. Whenever
            exec is called, a list of registered binary format
            handlers is scanned, in
            the same way you can hook the load_binary&  load_library
            function pointers
            of the already registered binary format handlers.

        Challenge with this untidy way is to identify the correct
        format, for
        example if you are interested in only hooking ELF format,
        there is no
        special signature withing the registered format handler to
        identify
        that, however if one format handler recognizes the file
        header, its
        load_binary will return 0. This can give you the hint that you are
        sitting on top of correct file format. Long time back I had
        written
        the similar module in Linux to do the same, but can't share
        the code
        :)

        -Rajat

        On Thu, Sep 22, 2011 at 3:14 PM, rohan
        puri<rohan.puri15 at gmail.com <mailto:rohan.puri15@gmail.com>>
         wrote:


            On Thu, Sep 22, 2011 at 1:53 PM, Abhijit
            Pawar<apawar.linux at gmail.com <mailto:apawar.linux@gmail.com>>
            wrote:

                hi list,
                Is there any way to hook the exec system call on Linux
                box apart from
                replacing the call in System Call table?

                Regards,
                Abhijit Pawar

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            Tidy way : -

            You can do that from LSM (Linux security module).

            Untidy way : -
            Yes, you can do that by registering a new binary format
            handler. Whenever
            exec is called, a list of registered binary format
            handlers is scanned, in
            the same way you can hook the load_binary&  load_library
            function pointers
            of the already registered binary format handlers.

            Regards,
            Rohan Puri

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    So If I use the binary format handler, then I can hook the exec
    call. however I need to register this. Does that mean that I need
    to return the negative value so as to have actual ELF handler to
    be loaded?

    Regards,
    Abhijit Pawar

Read this, http://www.linux.it/~rubini/docs/binfmt/binfmt.html 
<http://www.linux.it/%7Erubini/docs/binfmt/binfmt.html> this might help

Regards,
Rohan Puri

Thanks Rohan. I tried creating a hooking module on the similar line. I 
am able to load the module but whenever I am launching any application , 
its load_binary is not being called.
here is the source for the module attached.

Regards,
Abhijit Pawar


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