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From:   Kees Cook <keescook@chromium.org>
Date:   Thu, 21 Mar 2019 09:38:20 -0700
Message-ID: <CAGXu5jKj-Pq4krHmKd__4MoXBe1FK399cDZnSxdPigZo78tPfA@mail.gmail.com>
Subject: Re: mount.nfs: Protocol error after upgrade to linux/master
To:     Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc:     Casey Schaufler <casey@schaufler-ca.com>,
        Jakub Kicinski <jakub.kicinski@netronome.com>,
        linux-security-module <linux-security-module@vger.kernel.org>,
        Trond Myklebust <trond.myklebust@hammerspace.com>,
        "open list:NFS, SUNRPC, AND..." <linux-nfs@vger.kernel.org>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        LKML <linux-kernel@vger.kernel.org>
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On Tue, Mar 19, 2019 at 3:56 AM Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
>
> Since Kees Cook seems to be busy now, here is my version...
>
> From 885553e4793d9af2d4e9e99c7d137b0ec7b5f8ad Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Date: Tue, 19 Mar 2019 19:52:31 +0900
> Subject: [PATCH] LSM: Revive CONFIG_DEFAULT_SECURITY_* for "make oldconfig"
>
> Commit 70b62c25665f636c ("LoadPin: Initialize as ordered LSM") removed
> CONFIG_DEFAULT_SECURITY_{SELINUX,SMACK,TOMOYO,APPARMOR,DAC} from
> security/Kconfig and changed CONFIG_LSM to provide a fixed ordering as a
> default value. That commit expected that existing users (upgrading from
> Linux 5.0 and earlier) will edit CONFIG_LSM value in accordance with
> their CONFIG_DEFAULT_SECURITY_* choice in their old kernel configs. But
> since users might forget to edit CONFIG_LSM value, this patch revives
> the choice (only for providing the default value for CONFIG_LSM) in order
> to make sure that CONFIG_LSM reflects CONFIG_DEFAULT_SECURITY_* from their
> old kernel configs.
>
> Reported-by: Jakub Kicinski <jakub.kicinski@netronome.com>
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> ---
>  security/Kconfig | 36 +++++++++++++++++++++++++++++++++++-
>  1 file changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/security/Kconfig b/security/Kconfig
> index 1d6463f..743e594 100644
> --- a/security/Kconfig
> +++ b/security/Kconfig
> @@ -239,9 +239,43 @@ source "security/safesetid/Kconfig"
>
>  source "security/integrity/Kconfig"
>
> +choice
> +       prompt "Default security module [superseded by 'Ordered list of enabled LSMs' below]"
> +       default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
> +       default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
> +       default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
> +       default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
> +       default DEFAULT_SECURITY_DAC
> +
> +       help
> +         This choice is there only for converting CONFIG_DEFAULT_SECURITY in old
> +         kernel config to CONFIG_LSM in new kernel config. Don't change this choice
> +         unless you are creating a fresh kernel config, for this choice will be
> +         ignored after CONFIG_LSM is once defined.
> +
> +       config DEFAULT_SECURITY_SELINUX
> +               bool "SELinux" if SECURITY_SELINUX=y
> +
> +       config DEFAULT_SECURITY_SMACK
> +               bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
> +
> +       config DEFAULT_SECURITY_TOMOYO
> +               bool "TOMOYO" if SECURITY_TOMOYO=y
> +
> +       config DEFAULT_SECURITY_APPARMOR
> +               bool "AppArmor" if SECURITY_APPARMOR=y
> +       config DEFAULT_SECURITY_DAC
> +               bool "Unix Discretionary Access Controls"
> +
> +endchoice
> +
>  config LSM
>         string "Ordered list of enabled LSMs"
> -       default "yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor"
> +       default "yama,loadpin,safesetid,integrity,selinux" if DEFAULT_SECURITY_SELINUX
> +       default "yama,loadpin,safesetid,integrity,smack" if DEFAULT_SECURITY_SMACK
> +       default "yama,loadpin,safesetid,integrity,tomoyo" if DEFAULT_SECURITY_TOMOYO
> +       default "yama,loadpin,safesetid,integrity,apparmor" if DEFAULT_SECURITY_APPARMOR
> +       default "yama,loadpin,safesetid,integrity"
>         help
>           A comma-separated list of LSMs, in initialization order.
>           Any LSMs left off this list will be ignored. This can be

This is mostly good. I'd like to keep the other LSMs listed though
(similar to what I had originally) so that if a legacy-major doesn't
initialize, later ones will be. I want to remove the concept of
"major" LSMs. The only thing that should matter is init order...

-Kees

> --
> 1.8.3.1
>
>


-- 
Kees Cook