Comment by toast0
11 hours ago
> But I'm always a bit sceptical about such approaches. They are not universal. You still need glibc/musl to be the same on the target system. Also, if you compile againt new glibc version, but try to run on old glibc version, it might not work.
Why would you include most of your dynamic libraries but not your libc?
You could still run into problems if you (or your libraries) want to use syscalls that weren't available on older kernels or whatever.
You can include it, but
- either you use chroot, proot or similar to make /lib path contain your executable’s loader
- or you hardcode different loader path into your executable
Both are difficult for an end user.
This isn't that hard (that's not to say this is easy, it is tricky). Your executable should be a statically linked stub loader with an awful lot of data, the stub loader dynamically links your real executable (and libraries, including libc) from the data and runs it.
To add to this, in case of any remaining confusion. You can implement your own execve in userspace. [0] But the kernel's execve is a piece of machinery that invokes the loader so obviously it follows that you're free to make any changes you'd like to the overall process.
Bonus points if you add compression or encryption and manage to trip a virus scanner or three. [1]
[0] https://grugq.github.io/docs/ul_exec.txt
[1] https://blackhat.com/presentations/bh-usa-07/Yason/Whitepape...