linux-kernel - Re: [mingo@...e.hu: [git pull] headers

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 for Android: free password hash cracker in your pocket

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

Message-ID: <alpine.LFD.2.00.0901271539090.3123@localhost.localdomain>
Date:	Tue, 27 Jan 2009 15:43:29 -0800 (PST)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Ingo Molnar <mingo@...e.hu>
cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Sam Ravnborg <sam@...nborg.org>,
	Jaswinder Singh Rajput <jaswinderrajput@...il.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [mingo@...e.hu: [git pull] headers_check fixes]

On Wed, 28 Jan 2009, Ingo Molnar wrote:
> 
> It would be much better if we exported _much_ less and reduced our 
> cross-section to user-space. Also, the include/linux/Kbuild rules are all 
> but transparent: it would also be nice if whatever we exported was be 
> visible straight in the header itself, to make it obvious to people who 
> modify/extend those files that those definitions are going to be exported 
> to user-space.
> 
> Some __user_export tag on structures perhaps? I have no good ideas here - 
> #ifdefs are ugly and tags obscure the purity of the code.

I agree, and we probably could do so with some sparse extension (just make 
the rule be that in order to make a __user pointer, the base type needs to 
have been tagged with __user_visible). So we _could_ do something like 
that, and have a sane checking model where sparse would warn if it sees a 
user pointer of something that wasn't marked as being a user-visible type.

But I doubt it's really worth it. A lot of the usage cases for users end 
up being about constants etc that we really can't check sanely and 
automatically. And some historical user-space usage is literally just 
about user space finding the kernel headers really helpful (ie using the 
list.h headers for user-space lists, or the inline asms for atomic stuff 
for threaded apps that don't rely on ptrace locking).

		Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/