linux-kernel - Re: [RFC PATCH] x86/boot: Get rid of linux/init.h include

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20241122170227.GAZ0C5I-F8AUpwCAcG@fat_crate.local>
Date: Fri, 22 Nov 2024 18:02:27 +0100
From: Borislav Petkov <bp@...en8.de>
To: Ingo Molnar <mingo@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>, x86-ml <x86@...nel.org>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] x86/boot: Get rid of linux/init.h include

On Fri, Nov 22, 2024 at 05:55:52PM +0100, Ingo Molnar wrote:
> > --- a/arch/x86/boot/compressed/head_32.S
> > +++ b/arch/x86/boot/compressed/head_32.S
> > @@ -24,7 +24,6 @@
> >   */
> >  	.text
> >  
> > -#include <linux/init.h>
> >  #include <linux/linkage.h>
> >  #include <asm/segment.h>
> >  #include <asm/page_types.h>
> > @@ -32,6 +31,10 @@
> >  #include <asm/asm-offsets.h>
> >  #include <asm/bootparam.h>
> >  
> > +#ifdef KERNEL_PROPER_HEADER
> > +#error Do not include kernel proper namespace headers
> > +#endif
> 
> The canonical solution in such cases is to use the existing header 
> guard, ie:
> 
>  #ifdef _LINUX_INIT_H
>  # error Do not include kernel proper namespace headers
>  #endif
> 
> Then we can skip defining KERNEL_PROPER_HEADER as well, and this change 
> will be purely to x86 code.

Yap, I know, thought about it.

However, if we have to protect against every header, then we will have to do
a big

if defined...

which doesn't really work.

For the above example:

#if defined(_LINUX_INIT_H) || defined(_LINUX_LINKAGE_H)

and that would protect against the two headers which are included here.

If someone includes another one, it won't fire.

So we need a generic way to identify a kernel proper header. Either with
a define like KERNEL_PROPER_HEADER or some other magic (I don't know if there
is something like that), perhaps some preprocessor hackery which can figure
out whether some of the include paths have a include/linux/ in them and then
error out if so...

Maybe I should talk to toolchain folks...

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette