Superlinker is a tool that can combine executables and shared libraries into even larger products, just like object files are combined into executable

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2024-10-18 22:30:05

Superlinker is a tool that can combine executables and shared libraries into even larger products, just like object files are combined into executables and shared libraries.

Superlinker is structured essentially like a compiler whose inputs and outputs are interpreted programs (ELF ET_DYN PIE executables or shared libraries). Its frontend lifts an ELF ET_DYN object into an abstract and simple intermediate representation, and its backend lowers this representation back to an ELF ET_DYN object. While memory mappings (PT_LOAD segments) are retained essentially intact, none of the ELF headers are copied from the inputs to the outputs. Of the many possible transformations, the currently implemented one rebases and merges several ELF objects. This approach is quite robust.

Additionally, Superlinker is able to merge the dynamic linker itself into an executable, which enables transforming system-dependent executables into executables that run anywhere. (The resulting executable is still an ET_DYN object to retain the benefits of ASLR, but it has no load-time dependencies.) This is implemented with an executable shim that emulates the kernel ABI for PT_INTERP loaded objects, and so is not tied to a specific libc, but currently only tested with musl libc.