linux-kernel - Re: [PATCH] LSM: Allow syzbot to ignore security= parameter.

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Message-ID: <CACT4Y+Yd1YN=OELBmzUDvwdg5KuV2WnN9WZpjk5O_yuS0i1yOA@mail.gmail.com>
Date:   Mon, 4 Feb 2019 09:07:54 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:     Casey Schaufler <casey@...aufler-ca.com>,
        Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <sds@...ho.nsa.gov>,
        syzbot <syzbot+21016130b0580a9de3b5@...kaller.appspotmail.com>,
        tyhicks@...onical.com, John Johansen <john.johansen@...onical.com>,
        James Morris <jmorris@...ei.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-security-module@...r.kernel.org,
        Serge Hallyn <serge@...lyn.com>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        Jeffrey Vander Stoep <jeffv@...gle.com>,
        SELinux <selinux@...ho.nsa.gov>,
        Russell Coker <russell@...er.com.au>,
        Laurent Bigonville <bigon@...ian.org>,
        syzkaller <syzkaller@...glegroups.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] LSM: Allow syzbot to ignore security= parameter.

On Fri, Feb 1, 2019 at 2:09 PM Tetsuo Handa
<penguin-kernel@...ove.sakura.ne.jp> wrote:
>
> On 2019/02/01 19:50, Dmitry Vyukov wrote:
> > On Fri, Feb 1, 2019 at 11:44 AM Tetsuo Handa
> > <penguin-kernel@...ove.sakura.ne.jp> wrote:
> >>
> >> On 2019/02/01 19:09, Dmitry Vyukov wrote:
> >>> Thanks for the explanations.
> >>>
> >>> Here is the change that I've come up with:
> >>> https://github.com/google/syzkaller/commit/aa53be276dc84aa8b3825b3416542447ff82b41a
> >>
> >> You are not going to apply this updated config to upstream kernels now, are you?
> >> Removing CONFIG_DEFAULT_SECURITY="apparmor" from configs used by upstream kernels
> >> will cause failing to enable AppArmor (unless security=apparmor is specified).
> >
> >
> > We do use  security=apparmor, see:
> > https://github.com/google/syzkaller/blob/master/dashboard/config/upstream-apparmor.cmdline
> > https://github.com/google/syzkaller/blob/master/dashboard/config/upstream-selinux.cmdline
> > https://github.com/google/syzkaller/blob/master/dashboard/config/upstream-smack.cmdline
> >
>
> Oh, security= parameter is explicitly specified on all targets?
> Then, we can abuse CONFIG_DEBUG_AID_FOR_SYZBOT option. ;-)
>
> LSM folks, may we use this patch for linux-next.git ?
> CONFIG_DEBUG_AID_FOR_SYZBOT is a linux-next.git-only kernel config option used by syzbot.


Then we also need this on syzbot side, right? Otherwise it seems that
all instances will default to a single security module.
https://github.com/google/syzkaller/commit/ffec3d1894ffd05966b50efa49ca19af76c9ea81


> From c7d21f9c1c0b610ddea4233b89edf7d3140b8baf Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
> Date: Fri, 1 Feb 2019 22:03:55 +0900
> Subject: [PATCH linux-next] LSM: Allow syzbot to ignore security= parameter.
>
> LSM is going to get infrastructure managed security blob support in Linux
> 5.1, and it becomes possible to run TOMOYO with SELinux/Smack/AppArmor.
> But for compatibility reason, since security= parameter makes it
> impossible to run TOMOYO with SELinux/Smack/AppArmor, syzbot can't
> test that combination. Therefore, this patch allows syzbot to temporarily
> ignore security= parameter. This patch is meant for linux-next.git only,
> and will be removed after infrastructure managed security blob support
> went to linux.git.
>
> Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
> ---
>  security/security.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/security/security.c b/security/security.c
> index ef03643..0632feb 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -346,12 +346,14 @@ int __init security_init(void)
>  }
>
>  /* Save user chosen LSM */
> +#ifndef CONFIG_DEBUG_AID_FOR_SYZBOT
>  static int __init choose_major_lsm(char *str)
>  {
>         chosen_major_lsm = str;
>         return 1;
>  }
>  __setup("security=", choose_major_lsm);
> +#endif
>
>  /* Explicitly choose LSM initialization order. */
>  static int __init choose_lsm_order(char *str)
> --
> 1.8.3.1
>