linux-kernel - Re: [KERNEL] Re: [KERNEL] Re: [KERNEL] Re: [KERNEL] Re: [KERNEL] Re: [KERNEL] Re: Kernel 4.3 breaks security in systems using capabilities

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]

Date:	Fri, 6 Nov 2015 18:56:20 +0100
From:	Klaus Ethgen <Klaus+lkml@...gen.de>
To:	Theodore Ts'o <tytso@....edu>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Richard Weinberger <richard.weinberger@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Christoph Lameter <cl@...ux.com>,
	Andy Lutomirski <luto@...nel.org>,
	Serge Hallyn <serge.hallyn@...ntu.com>,
	Kees Cook <keescook@...omium.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [KERNEL] Re: [KERNEL] Re: [KERNEL] Re: [KERNEL] Re: [KERNEL] Re:
 [KERNEL] Re:  Kernel 4.3  breaks security in systems using capabilities

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

Am Fr den  6. Nov 2015 um 16:53 schrieb Theodore Ts'o:
> On Fri, Nov 06, 2015 at 02:58:36PM +0100, Klaus Ethgen wrote:
> > But that left out completely the, I think more important, usecase of
> > _removing_ SUID completely and _replacing_ it with very tight capability
> > setting. And that is what I always talked about.
> 
> I don't believe this is ever going to be possible.  And I'm not
> talking about it from a technical perspective, but from a practical
> and cultural perspective.
> 
> The problem with removing SUID and inheritance completely is that you
> have to anticipate all possible use cases where a system administrator
> might want to use a root shell.  This means analyzing all possible use
> cases for all possible system administrators how they might need to
> use a root shell to fix or management a system,

That is not my interest at all. I wan't to get rid of all the SUID
_binaries_ that are used by _normal_ users. (And me counting as normal
user in the most time too.)

I do not want to remove root or something like that. For that task,
capabilities is definitively the wrong tool.

> and then either (a)
> provide a new, specialized tool that solves that particular use case,
> while respecting the rules of least privilege, or (b) figure out how
> to expand that executable's fI mask, and worse, if that executable
> fork and exec's helper programs, those helper programs will need to
> have expanded fI masks.  And that's if all of the commands that a
> system administrator needs to run are compiled executables.  Now
> consider what happens when a system administrator needs to run python,
> perl, or shell scripts with elevated privileges.

Independent of, that I do not want to address this, I never want to have
a shell (sh, perl, python, ruby, ...) in such a construct.

> In the light of that, using things like ambient capabilities, or using
> setuid binary that immediately drops all caps that it needs, is
> probably the best we're going to get.

I do never want that! Even to think about such a way to give any shell
raised rights is horrible! And that horrible idea is it that makes all
the ambient capabilities that bad.

Regards
   Klaus
- -- 
Klaus Ethgen                              http://www.ethgen.ch/
pub  4096R/4E20AF1C 2011-05-16   Klaus Ethgen <Klaus@...gen.de>
Fingerprint: 85D4 CA42 952C 949B 1753  62B3 79D0 B06F 4E20 AF1C
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1
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=9dzb
-----END PGP SIGNATURE-----
--
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/