Re: [PATCH] samples/seccomp: Add standalone config option

From: Kees Cook
Date: Thu Jul 07 2016 - 13:54:44 EST


On Wed, Jul 6, 2016 at 2:53 AM, Olof Johansson <olof@xxxxxxxxx> wrote:
> Add a separate Kconfig option for SAMPLES_SECCOMP.
>
> Main reason for this is that, just like other samples, it's forced to be a module.
>
> Without this, since the sample is a target only controlled by
> CONFIG_SECCOMP_FILTER, the samples will be built before include files are
> put in place properly. For example, from an arm64 allmodconfig built with
> "make -sk -j 32" (without specific target), the following happens:
>
> samples/seccomp/bpf-fancy.c:13:27: fatal error: linux/seccomp.h: No such file or directory
> samples/seccomp/bpf-helper.h:20:50: fatal error: linux/seccomp.h: No such file or directory
> samples/seccomp/dropper.c:20:27: fatal error: linux/seccomp.h: No such file or directory
> samples/seccomp/bpf-direct.c:21:27: fatal error: linux/seccomp.h: No such file or directory
>
> So, just stick to the same format as other samples.
>
> Signed-off-by: Olof Johansson <olof@xxxxxxxxx>
> ---
> samples/Kconfig | 7 +++++++
> samples/seccomp/Makefile | 2 +-
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
>
> Hi Kees,
>
> This has been showing up for a while on my builder, and I finally had
> a bit of time to sit down and look at it.
>
> It'd be nice to see this in 4.7, but please consider for 4.8 at the least.

I feel like we're too late in 4.7, but I've applied this for 4.8.
Thanks for tracking it down!

-Kees

>
>
> Thanks!
>
> -Olof
>
> diff --git a/samples/Kconfig b/samples/Kconfig
> index 559a58b..ccc50be 100644
> --- a/samples/Kconfig
> +++ b/samples/Kconfig
> @@ -85,4 +85,11 @@ config SAMPLE_CONNECTOR
> with it.
> See also Documentation/connector/connector.txt
>
> +config SAMPLE_SECCOMP
> + tristate "Build seccomp sample code -- loadable modules only"
> + depends on SECCOMP_FILTER && m
> + help
> + Build samples of seccomp filters using various methods of
> + BPF filter construction.
> +
> endif # SAMPLES
> diff --git a/samples/seccomp/Makefile b/samples/seccomp/Makefile
> index 1b4e4b8..ae7ff6f 100644
> --- a/samples/seccomp/Makefile
> +++ b/samples/seccomp/Makefile
> @@ -1,7 +1,7 @@
> # kbuild trick to avoid linker error. Can be omitted if a module is built.
> obj- := dummy.o
>
> -hostprogs-$(CONFIG_SECCOMP_FILTER) := bpf-fancy dropper bpf-direct
> +hostprogs-$(CONFIG_SAMPLE_SECCOMP) := bpf-fancy dropper bpf-direct
>
> HOSTCFLAGS_bpf-fancy.o += -I$(objtree)/usr/include
> HOSTCFLAGS_bpf-fancy.o += -idirafter $(objtree)/include
> --
> 2.8.0.rc3.29.gb552ff8
>



--
Kees Cook
Chrome OS & Brillo Security