linux-kernel - Re: [PATCH v2] kernel: Conditionally support non-root users, groups and capabilities

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Date:	Thu, 29 Jan 2015 19:59:09 +0100
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Iulia Manda <iulia.manda21@...il.com>
Cc:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>,
	Josh Triplett <josh@...htriplett.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Michal Hocko <mhocko@...e.cz>
Subject: Re: [PATCH v2] kernel: Conditionally support non-root users, groups
 and capabilities

Hi Iulia,

On Thu, Jan 29, 2015 at 7:43 PM, Iulia Manda <iulia.manda21@...il.com> wrote:
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index 68b68d7..b2d2116 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -324,6 +324,7 @@ config COMPAT
>         select COMPAT_BINFMT_ELF if BINFMT_ELF
>         select ARCH_WANT_OLD_COMPAT_IPC
>         select COMPAT_OLD_SIGACTION
> +       select NON_ROOT

> @@ -10,6 +10,7 @@ config LUSTRE_FS

> +       select NON_ROOT

> @@ -6,6 +6,7 @@ config NFSD

> +       select NON_ROOT

>  config BSD_PROCESS_ACCT
>         bool "BSD Process Accounting"
> +       select NON_ROOT

>  config TASKSTATS

> +       select NON_ROOT

Is there a specific reason why you chose to use "select NON_ROOT"
instead of "depends on NON_ROOT" for all these options?
As configuring NON_ROOT=n is quite a drastic decision, I don't
think you should let that be revertable such easily by all those selects.

> @@ -1140,6 +1142,7 @@ config CHECKPOINT_RESTORE
>
>  menuconfig NAMESPACES
>         bool "Namespaces support" if EXPERT
> +       depends on NON_ROOT

> @@ -1352,11 +1355,25 @@ menuconfig EXPERT
>
>  config UID16
>         bool "Enable 16-bit UID system calls" if EXPERT
> -       depends on HAVE_UID16
> +       depends on HAVE_UID16 && NON_ROOT

Ah, finally a few "depends on".

> +config NON_ROOT
> +       bool "Multiple users, groups and capabilities support" if EXPERT
> +       default y
> +       help
> +         This option enables support for non-root users, groups and
> +         capabilities.
> +
> +         If you say N here, all processes will run with UID 0, GID 0, and all
> +         possible capabilities.  Saying N here also compiles out support for
> +         system calls related to UIDs, GIDs, and capabilities, such as setuid,
> +         setgid, and capset.
> +
> +         If unsure, say Y here.

I think it would be clearer to use positive instead of negative logic.
What about calling the option "MULTIUSER" instead of "NON_ROOT"?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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