Thread: howto add sys call using modules only ?

  1. #1
    Registered User
    Join Date
    Jun 2005
    Posts
    1

    howto add sys call using modules only ?

    I am doing a small project in which i m designing a new system call
    to encrypt/decrypt files.

    My problem goes like this:

    1> Previously up until 2.4 , sys_call_table was exported by kernel
    and so obsolete sys call no. could be used to add our customised
    syscall.So patching around that obsolete sys call worked.

    2> I am designing on 2.6.5 and it doesnt export sys_call_table .
    So the obvious thing is to modify kernel sources and do development.
    But this would terribly slow down the work as I have to recompile
    again and again. I thought using modules is better.

    In order to export the sys_call_table in kernel 2.6 i added into the file arch/i386/kernel/i386_ksyms.c the following lines:
    extern void* sys_call_table[];
    EXPORT_SYMBOL(sys_call_table);

    But after recompile , the symbol unresolved problem continues
    when i run my module.

    I googled a lot but couldnt find worthy source. Could u suggest a workaround
    to add sys call using modules only ?

  2. #2
    Registered User
    Join Date
    Aug 2005
    Posts
    5
    try:
    http://mail.nl.linux.org/kernelnewbi.../msg00413.html
    I've tried the first version and I can use symbols but only inside the module I define the new_sys_call_table.
    Hope it works for you too. (I use kernel 2.4, I haven't tried in 2.6)

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