Re: [BUG] bpftool: Build failure due to opensslv.h

[Namhyung Kim <namhyung@kernel.org>]

Hello,

On Tue, Nov 25, 2025 at 09:03:38AM +0000, Alan Maguire wrote:
> On 24/11/2025 20:42, Namhyung Kim wrote:
> > On Thu, Nov 20, 2025 at 09:24:49AM +0000, Quentin Monnet wrote:
> >> 2025-11-19 17:56 UTC-0800 ~ Namhyung Kim <namhyung@kernel.org>
> >>> Hello,
> >>>
> >>> On Tue, Oct 28, 2025 at 10:20:22AM +0000, Alan Maguire wrote:
> >>>> On 28/10/2025 09:05, Quentin Monnet wrote:
> >>>>> 2025-10-27 11:27 UTC-0700 ~ Namhyung Kim <namhyung@kernel.org>
> >>>>>> On Mon, Oct 27, 2025 at 11:41:01AM +0000, Quentin Monnet wrote:
> >>>>>>> 2025-10-26 21:01 UTC-0700 ~ Namhyung Kim <namhyung@kernel.org>
> >>>>>>>> Hello,
> >>>>>>>>
> >>>>>>>> I'm seeing a build failure like below in Fedora 40 and others.  I'm not
> >>>>>>>> sure if it's reported already but it failed to build perf tools due to
> >>>>>>>> errors in the bootstrap bpftool.
> >>>>>>>>
> >>>>>>>>     CC      /build/util/bpf_skel/.tmp/bootstrap/sign.o
> >>>>>>>>   sign.c:16:10: fatal error: openssl/opensslv.h: No such file or directory
> >>>>>>>>      16 | #include <openssl/opensslv.h>
> >>>>>>>>         |          ^~~~~~~~~~~~~~~~~~~~
> >>>>>>>>   compilation terminated.
> >>>>>>>>   make[3]: *** [Makefile:256: /build/util/bpf_skel/.tmp/bootstrap/sign.o] Error 1
> >>>>>>>>   make[3]: *** Waiting for unfinished jobs....
> >>>>>>>>   make[2]: *** [Makefile.perf:1213: /build/util/bpf_skel/.tmp/bootstrap/bpftool] Error 2
> >>>>>>>>   make[1]: *** [Makefile.perf:289: sub-make] Error 2
> >>>>>>>>   make: *** [Makefile:76: all] Error 2
> >>>>>>>>
> >>>>>>>> I think it's from the recent signing change.  I'm not familiar with
> >>>>>>>> openssl but I guess there's a proper feature check for it.  Is this a
> >>>>>>>> known issue?
> >>>>>>>
> >>>>>>>
> >>>>>>> Hi Namhyung,
> >>>>>>
> >>>>>> Hello!
> >>>>>>
> >>>>>>>
> >>>>>>> This looks related to the program signing change indeed, commit
> >>>>>>> 40863f4d6ef2 ("bpftool: Add support for signing BPF programs")
> >>>>>>> introduced a dependency on OpenSSL's development headers for bpftool.
> >>>>>>> It's not gated behind a feature check. On Fedora, I think the headers
> >>>>>>> come with openssl-devel, do you have this package installed?
> >>>>>>
> >>>>>> No I don't, but I guess it should be able to build on such systems.  Or
> >>>>>> is it required for bpftool?  Anyway I feel like it should have a feature
> >>>>>> check and appropriate error messages.
> >>>>>>
> >>>>>
> >>>>> +Cc KP
> >>>>>
> >>>>> We usually have feature checks when optional features bring in new
> >>>>> dependencies for bpftool, but we haven't discussed it this time. My
> >>>>> understanding was that program signing is important enough that it
> >>>>> should always be present in newer versions of bpftool, making OpenSSL
> >>>>> one of the required dependencies going forward.
> >>>>>
> >>>>> We don't currently have feature checks to tell when required
> >>>>> dependencies are missing for bpftool (it's just the build failing, in
> >>>>> that case). I know perf does a great job at it, we could look into it
> >>>>> for bpftool, too.
> >>>>>
> >>>>
> >>>> One issue here is that some distros package openssl v3 such that the
> >>>> #include files are in /usr/include/openssl3 and libraries in
> >>>> /usr/lib64/openssl3 so that older versions can co-exist. Maybe we could
> >>>> figure out a feature test that handles that too?
> >>>
> >>> What's the state of this?  Is the fix in the bpf tree now?
> >>
> >>
> >> Hi Namhyung, Alan just submitted a v2 of his patch (targetting
> >> bpf-next), see:
> >>
> >> https://lore.kernel.org/all/20251120084754.640405-2-alan.maguire@oracle.com/
> >  
> > Hello Quentin,
> > 
> > I'm afraid it doesn't fix my issue.  It seems to fix another problem
> > about the error API.  But I still see the build failure.
> >
> 
> This header file is delivered by openssl-devel (could be openssl-dev on
> some distros). Looking at [1], it seems like that package has been a
> requirement to build kernels from 4.3 on. Is it missing on your system,
> installed to an unusual path like /usr/include/opensslv3, or is the
> package perhaps missing some header files?

I think some of my test environments don't have openssl dev packages.
I didn't know it was required for kernel builds but it wasn't for perf.
If you guys require it for bpftool, maybe I can make perf disable BPF
support in case openssl is missing.

Thanks,
Namhyung

> 
> Alan
> 
> [1] https://docs.kernel.org/process/changes.html
> 
> > Thanks,
> > Namhyung
> > 
> > 
>