linux-kernel - Re: [PATCH v2 6/8] selinux: do not include <linux/*.h> headers from host programs

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Message-ID: <CABj0suDY3duFeZx8ghEJm3vTuJvcVuoYZ6BpYn9SCaHetw3oNA@mail.gmail.com>
Date: Fri, 6 Sep 2024 17:07:52 +0200
From: "Daniel Gomez (Samsung)" <d+samsung@...ces.com>
To: Paul Moore <paul@...l-moore.com>
Cc: da.gomez@...sung.com, Masahiro Yamada <masahiroy@...nel.org>, 
	Nathan Chancellor <nathan@...nel.org>, Nicolas Schier <nicolas@...sle.eu>, 
	Lucas De Marchi <lucas.demarchi@...el.com>, 
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>, 
	Rodrigo Vivi <rodrigo.vivi@...el.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
	William Hubbs <w.d.hubbs@...il.com>, Chris Brannon <chris@...-brannons.com>, 
	Kirk Reiser <kirk@...sers.ca>, Samuel Thibault <samuel.thibault@...-lyon.org>, 
	Stephen Smalley <stephen.smalley.work@...il.com>, Ondrej Mosnacek <omosnace@...hat.com>, 
	Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>, 
	Oliver Upton <oliver.upton@...ux.dev>, James Morse <james.morse@....com>, 
	Suzuki K Poulose <suzuki.poulose@....com>, Zenghui Yu <yuzenghui@...wei.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jirislaby@...nel.org>, 
	Nick Desaulniers <ndesaulniers@...gle.com>, Bill Wendling <morbo@...gle.com>, 
	Justin Stitt <justinstitt@...gle.com>, Simona Vetter <simona.vetter@...ll.ch>, 
	linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org, 
	intel-xe@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org, 
	speakup@...ux-speakup.org, selinux@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	linux-serial@...r.kernel.org, llvm@...ts.linux.dev, 
	Finn Behrens <me@...enk.dev>, gost.dev@...sung.com
Subject: Re: [PATCH v2 6/8] selinux: do not include <linux/*.h> headers from
 host programs

On Fri, Sep 6, 2024 at 4:56 PM Paul Moore <paul@...l-moore.com> wrote:
>
> On Fri, Sep 6, 2024 at 7:01 AM Daniel Gomez via B4 Relay
> <devnull+da.gomez.samsung.com@...nel.org> wrote:
> >
> > From: Masahiro Yamada <masahiroy@...nel.org>
> >
> > Commit bfc5e3a6af39 ("selinux: use the kernel headers when building
> > scripts/selinux") is not the right thing to do.
> >
> > It is clear from the warning in include/uapi/linux/types.h:
> >
> >   #ifndef __EXPORTED_HEADERS__
> >   #warning "Attempt to use kernel headers from user space, see https://kernelnewbies.org/KernelHeaders"
> >   #endif /* __EXPORTED_HEADERS__ */
> >
> > If you are inclined to define __EXPORTED_HEADERS__, you are likely doing
> > wrong.
> >
> > Adding the comment:
> >
> >   /* NOTE: we really do want to use the kernel headers here */
> >
> > does not justify the hack in any way.
> >
> > Currently, <linux/*.h> headers are included for the following purposes:
> >
> >  - <linux/capability.h> is included to check CAP_LAST_CAP
> >  - <linux/socket.h> in included to check PF_MAX
> >
> > We can skip these checks when building host programs, as they will
> > be eventually tested when building the kernel space.
> >
> > I got rid of <linux/stddef.h> from initial_sid_to_string.h because
> > it is likely that NULL is already defined. If you insist on making
> > it self-contained, you can add the following:
> >
> >   #ifdef __KERNEL__
> >   #include <linux/stddef.h>
> >   #else
> >   #include <stddef.h>
> >   #endif
> >
> > scripts/selinux/mdp/mdp.c still includes <linux/kconfig.h>, which is
> > also discouraged and should be fixed by a follow-up refactoring.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> > ---
> >  scripts/selinux/genheaders/Makefile              |  4 +---
> >  scripts/selinux/genheaders/genheaders.c          |  3 ---
> >  scripts/selinux/mdp/Makefile                     |  2 +-
> >  scripts/selinux/mdp/mdp.c                        |  4 ----
> >  security/selinux/include/classmap.h              | 19 ++++++++++++-------
> >  security/selinux/include/initial_sid_to_string.h |  2 --
> >  6 files changed, 14 insertions(+), 20 deletions(-)
>
> Similar to patch 7/8, please read my comments on your previous posting
> of this patch, it doesn't appear that you've made any of the changes I
> asked for in your previous posting.

Sorry for the noise, Paul. I’ll review this one as well.

>
> https://lore.kernel.org/selinux/317c7d20ab8a72975571cb554589522b@paul-moore.com
>
> --
> paul-moore.com