samples/seccomp: Add standalone config option

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@lixom.net>
Signed-off-by: Kees Cook <keescook@chromium.org>

2 files changed, 8 insertions, 1 deletions

diff --git a/samples/Kconfig b/samples/Kconfig
index 559a58baff6e..ccc50beaf17b 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 1b4e4b8f5e47..ae7ff6f24f36 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