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Message-ID: <202110081543.1B6BF22@keescook>
Date: Fri, 8 Oct 2021 15:44:20 -0700
From: Kees Cook <keescook@...omium.org>
To: Mickaël Salaün <mic@...ikod.net>
Cc: Al Viro <viro@...iv.linux.org.uk>,
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Mickaël Salaün <mic@...ux.microsoft.com>
Subject: Re: [PATCH v13 3/3] selftest/interpreter: Add tests for
trusted_for(2) policies
On Fri, Oct 08, 2021 at 12:21:12PM +0200, Mickaël Salaün wrote:
>
> On 07/10/2021 21:48, Kees Cook wrote:
> > On Thu, Oct 07, 2021 at 08:23:20PM +0200, Mickaël Salaün wrote:
>
> [...]
>
> >> diff --git a/tools/testing/selftests/interpreter/Makefile b/tools/testing/selftests/interpreter/Makefile
> >> new file mode 100644
> >> index 000000000000..1f71a161d40b
> >> --- /dev/null
> >> +++ b/tools/testing/selftests/interpreter/Makefile
> >> @@ -0,0 +1,21 @@
> >> +# SPDX-License-Identifier: GPL-2.0
> >> +
> >> +CFLAGS += -Wall -O2
> >> +LDLIBS += -lcap
> >> +
> >> +src_test := $(wildcard *_test.c)
> >> +TEST_GEN_PROGS := $(src_test:.c=)
> >> +
> >> +KSFT_KHDR_INSTALL := 1
> >> +include ../lib.mk
> >> +
> >> +khdr_dir = $(top_srcdir)/usr/include
> >> +
> >> +$(khdr_dir)/asm-generic/unistd.h: khdr
> >> + @:
> >> +
> >> +$(khdr_dir)/linux/trusted-for.h: khdr
> >> + @:
> >> +
> >> +$(OUTPUT)/%_test: %_test.c $(khdr_dir)/asm-generic/unistd.h $(khdr_dir)/linux/trusted-for.h ../kselftest_harness.h
> >> + $(LINK.c) $< $(LDLIBS) -o $@ -I$(khdr_dir)
> >
> > Is all this really needed?
>
> Yes, all this is needed to be sure that the tests will be rebuild when a
> dependency change (either one of the header files or a source file).
>
> >
> > - CFLAGS and LDLIBS will be used by the default rules
>
> Yes, but it will only run the build command when a source file change,
> not a header file.
>
> > - khdr is already a pre-dependency when KSFT_KHDR_INSTALL is set
>
> Yes, but it is not enough to rebuild the tests (and check the installed
> files) when a header file change.
>
> > - kselftest_harness.h is already a build-dep (see LOCAL_HDRS)
>
> Yes, but without an explicit requirement, changing kselftest_harness.h
> doesn't force a rebuild.
>
> > - TEST_GEN_PROGS's .c files are already build-deps
>
> It is not enough to trigger test rebuilds.
>
> >
> > kselftest does, oddly, lack a common -I when KSFT_KHDR_INSTALL is set
> > (which likely should get fixed, though separately from here).
> >
> > I think you just want:
> >
> >
> > src_test := $(wildcard *_test.c)
> > TEST_GEN_PROGS := $(src_test:.c=)
> >
> > KSFT_KHDR_INSTALL := 1
> > include ../lib.mk
> >
> > CFLAGS += -Wall -O2 -I$(BUILD)/usr/include
> > LDLIBS += -lcap
> >
> > $(OUTPUT)/%_test: $(BUILD)/usr/include/linux/trusted-for.h
> >
> >
> > (untested)
> >
> Yep, I re-checked and my Makefile is correct. I didn't find a way to
> make it lighter while correctly handling dependencies.
> I'll just move the -I to CFLAGS.
Okay, thanks for double-checking these. I'll try to fix up kselftests to
DTRT here.
--
Kees Cook
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