Skip to content

Instantly share code, notes, and snippets.

@rmi1974

rmi1974/how_to_find_a_binaries_dependencies_using_dynamic_linker.md

Last active March 5, 2022 13:00
Show Gist options

  • Select an option

    Learn more about clone URLs
  • Save rmi1974/f970e9e9ea16537b812e4024a55fa892 to your computer and use it in GitHub Desktop.

Select an option

Learn more about clone URLs
Save rmi1974/f970e9e9ea16537b812e4024a55fa892 to your computer and use it in GitHub Desktop.
Download ZIP

Revisions

  1. rmi1974 revised this gist Mar 5, 2022. No changes.
  2. rmi1974 created this gist Dec 11, 2021.
    33 changes: 33 additions & 0 deletions how_to_find_a_binaries_dependencies_using_dynamic_linker.md
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,33 @@
    # How to find a binary's dependencies using dynamic linker

    Courtesy of [exocus project on github][1]

    You can invoke ld-linux with the LD_TRACE_LOADED_OBJECTS environment variable set to 1 and it will list all of the resolved library dependencies for a binary. For example, running

    ```shell
    LD_TRACE_LOADED_OBJECTS=1 /lib64/ld-linux-x86-64.so.2 /bin/grep
    ```

    will output the following.

    ```console
    linux-vdso.so.1 => (0x00007ffc7495c000)
    libpcre.so.0 => /lib64/libpcre.so.0 (0x00007f89b2f3e000)
    libc.so.6 => /lib64/libc.so.6 (0x00007f89b2b7a000)
    libpthread.so.0 => /usr/lib/libpthread.so.0 (0x00007f0e95e8c000)
    /lib64/ld-linux-x86-64.so.2 (0x00007f89b3196000)
    ```

    The linus-vdso.so.1 dependency refers to kernel space routines that are exported to user space, but the other four are shared library files on disk that are required in order to run grep. Notably, one of these dependencies is the /lib64/ld-linux-x86-64.so.2 linker itself. The location of this file is typically hardcoded into an ELF binary's INTERP header and the linker is invoked by the kernel when you run the program. We'll come back to that in a minute, but for now the main point is that we can find a binary's direct dependencies using the linker.

    Of course, these direct dependencies might have additional dependencies of their own. We can iteratively find all of the necessary dependencies by following the same approach of invoking the linker again for each of the library dependencies.

    ---

    **Links**

    * [exocus project on github][1]

    [//]: # (invisible, for link references)
    [1]: https://github.com/intoli/exodus#how-it-works