Skip to content

Latest commit

 

History

History
27 lines (18 loc) · 1.43 KB

Relative_interpreter.md

File metadata and controls

27 lines (18 loc) · 1.43 KB
Raw

Relative interpreter

A dynamically linked ELF executable normally has to specify the absolute path of the dynamic loader that it expects to use. This path will typically be something like /lib64/ld-linux-x86-64.so.2, though it can be set to something else at link time via -Wl,--dynamic-linker=, or after the fact via polyfill-glibc --set-interpreter=.

It is not normally possible to use the $ORIGIN placeholder as part of the path to the dynamic linker, however an experimental tool in the polyfill-glibc repository makes this possible. The tool can be built using the command:

$ ninja build/x86_64/set_relative_interp

Note

The tool is currently only available for x86_64. If other architectures are of interest to you, open a GitHub issue so that we can gauge demand.

Once built, the tool takes two command line arguments: the path of an executable to modify, and an interpreter path starting with $ORIGIN, for example:

$ build/x86_64/set_relative_interp a.out '$ORIGIN/libs/ld-linux-x86-64.so.2'

Warning

Be careful to avoid having your shell expand $ORIGIN.

The modified executable will look for a dynamic loader in two places:

  1. The LD_SO_PATH environment variable, if set.
  2. The path specified as the 2nd argument to set_relative_interp.

If the modified executable does not have an rpath or runpath attribute, then it'll gain an rpath equal to the directory containing the dynamic loader.