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Comment by btdmaster

1 day ago

Yes you can do this, thanks for mentioning I was interested and checked how you would go about it.

1. Delete the shared symbol versioning as per https://stackoverflow.com/a/73388939 (patchelf --clear-symbol-version exp mybinary)

2. Replace libc.so with a fake library that has the right version symbol with a version script e.g. version.map GLIBC_2.29 { global: *; };

With an empty fake_libc.c `gcc -shared -fPIC -Wl,--version-script=version.map,-soname,libc.so.6 -o libc.so.6 fake_libc.c`

3. Hope that you can still point the symbols back to the real libc (either by writing a giant pile of dlsym C code, or some other way, I'm unclear on this part)

Ideally glibc would stop checking the version if it's not actually marked as needed by any symbol, not sure why it doesn't (technically it's the same thing normally, so performance?).

Ah you can use https://github.com/NixOS/patchelf/pull/564

So you can do e.g. `patchelf --remove-needed-version libm.so.6 GLIBC_2.29 ./mybinary` instead of replacing glibc wholesale (step 2 and 3) and assuming all of used glibc by the executable is ABI compatible this will just work (it's worked for a small binary for me, YMMV).