Re: [PATCH] libbpf: don't preserve ownership during install

[Martin Kaiser <martin@kaiser.cx>]

Thus wrote sashiko-bot@kernel.org (sashiko-bot@kernel.org):

> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] The use of the GNU-specific `cp --preserve` extension breaks `make install` on platforms with BSD or BusyBox `cp` implementations (e.g., macOS, FreeBSD, Alpine).
> --

> --- Patch [1]: [PATCH] libbpf: don't preserve ownership during install ---
> commit 20b6f948388a1067581300a57d47fc33d1950c11
> Author: Martin Kaiser <martin@kaiser.cx>

> libbpf: don't preserve ownership during install

> This commit modifies the libbpf install_lib target in the Makefile to
> prevent leaking the source tree owner's UID into the root filesystem. It
> replaces the cp -p flag with the --preserve=mode,timestamps flag to only
> preserve specific file attributes during installation.

> > diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> > --- a/tools/lib/bpf/Makefile
> > +++ b/tools/lib/bpf/Makefile
> > @@ -231,7 +231,7 @@ endef
> >  install_lib: all_cmd
> >  	$(call QUIET_INSTALL, $(LIB_TARGET)) \
> >  		$(call do_install_mkdir,$(libdir_SQ)); \
> > -		cp -fpR $(LIB_FILE) $(DESTDIR)$(libdir_SQ)
> > +		cp -fR --preserve=mode,timestamps $(LIB_FILE) $(DESTDIR)$(libdir_SQ)

> [Severity: Medium]
> Will this break the installation process on platforms that do not use GNU
> coreutils?

> The --preserve argument is a GNU-specific extension. It appears this might
> cause the make install target to fail with an unrecognized option error on
> systems relying on BSD or BusyBox implementations of cp, such as macOS,
> FreeBSD, or Alpine Linux.


commit 1375152bb02a ("tools: lib: thermal: don't preserve owner in install")
makes a similar change for tools/lib/thermal/Makefile.

I'd assume that it's reasonable to require coreutils for kernel compilation.

AFAICS, kernel builds on Alpine linux require the alpine-sdk package which
contains coreutils.

Thanks,
Martin