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Help regarding -kernel to user space

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  • Murali Subramanian
    Hi, I am the newbie of Linux Programming. I am seeking the help from you. I had a problem with get the kernel data to my userspace.
    Message 1 of 3 , May 8 6:04 PM
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      Hi,
      I am the newbie of Linux Programming. I am seeking the help from
      you. I had a problem with get the kernel data to my userspace.
      /usr/src/linux/net/ipv4/netfilter/ipt_LOG.c is a kernel file which has
      the ip network informations.
      I want to get the data from my user program. I found two commands
      which is 'copy_to_user() & copy_from_user()'. But i dont know,how to
      use this functions for my user program.

      Please guide me with example or else send me the sample code for using
      these two functions which would be very useful to me...

      with thanks & regards,
      Murali Subramanian.,
    • Nikunj A. Dadhania
      Hi, ... There should be some standard interfaces from which u can get kernel IP information, most of them will be there in /proc/net/ directory. You can open
      Message 2 of 3 , May 9 2:29 AM
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        Hi,

        On Fri, 2003-05-09 at 06:34, Murali Subramanian wrote:
        > Hi,
        > I am the newbie of Linux Programming. I am seeking the help from
        > you. I had a problem with get the kernel data to my userspace.
        > /usr/src/linux/net/ipv4/netfilter/ipt_LOG.c is a kernel file which has
        > the ip network informations.
        There should be some standard interfaces from which u can get kernel IP
        information, most of them will be there in /proc/net/ directory. You can
        open these files in read-only mode and get the required data.

        If you need to write your own interfaces, you will have to refer to
        Linux kernel module programming guide(lkmpg) which are available at
        www.tldp.org


        > I want to get the data from my user program. I found two commands
        > which is 'copy_to_user() & copy_from_user()'. But i dont know,how to
        > use this functions for my user program.
        These functions are _only_ used in kernel space and CANNOT be used in
        user space programs

        >
        > Please guide me with example or else send me the sample code for using
        > these two functions which would be very useful to me...
        The lkmpg has examples to use these functions.

        You could also visit this link.
        http://www.oreilly.com/catalog/linuxdrive2/chapter/book/

        Thanks
        Nikunj
      • Nikunj A. Dadhania
        ... Forgot one more thing, all the ip network informations data structures which you are interested in could only be accessed by your module if and only if
        Message 3 of 3 , May 9 2:33 AM
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          On Fri, 2003-05-09 at 06:34, Murali Subramanian wrote:
          > Hi,
          > I am the newbie of Linux Programming. I am seeking the help from
          > you. I had a problem with get the kernel data to my userspace.
          > /usr/src/linux/net/ipv4/netfilter/ipt_LOG.c is a kernel file which has
          > the ip network informations.
          Forgot one more thing, all the ip network informations data structures
          which you are interested in could only be accessed by your module if and
          only if they are global.

          After writing this module(may be a character driver with ioctl), you
          will also need to write a user level utilities to get information from
          the kernel.

          hope this information helps you.

          thanks
          nikunj
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