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From: Casey Schaufler <casey@schaufler-ca.com>
To: Kees Cook <keescook@chromium.org>,
	John Johansen <john.johansen@canonical.com>
Cc: "Mickaël Salaün" <mic@digikod.net>,
	"James Morris" <jmorris@namei.org>,
	"Tetsuo Handa" <penguin-kernel@i-love.sakura.ne.jp>,
	"Paul Moore" <paul@paul-moore.com>,
	"Stephen Smalley" <sds@tycho.nsa.gov>,
	"Schaufler, Casey" <casey.schaufler@intel.com>,
	LSM <linux-security-module@vger.kernel.org>,
	LKLM <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 16/18] LSM: Allow arbitrary LSM ordering
Date: Mon, 17 Sep 2018 16:40:50 -0700	[thread overview]
Message-ID: <ddb2a534-0845-55c1-329c-70adcc3847b8@schaufler-ca.com> (raw)
In-Reply-To: <CAGXu5j+haqMgKxkH12M3O358oBR-jU0uWTZSrCrm462mtgf26A@mail.gmail.com>

On 9/17/2018 4:28 PM, Kees Cook wrote:
> On Mon, Sep 17, 2018 at 4:26 PM, John Johansen
> <john.johansen@canonical.com> wrote:
>> On 09/17/2018 04:20 PM, Kees Cook wrote:
>>> On Mon, Sep 17, 2018 at 4:10 PM, Mickaël Salaün <mic@digikod.net> wrote:
>>>> Landlock, because it target unprivileged users, should only be called
>>>> after all other major (access-control) LSMs. The admin or distro must
>>>> not be able to change that order in any way. This constraint doesn't
>>>> apply to current LSMs, though.
>>> Good point! It will be easy to add LSM_ORDER_LAST, though, given the
>>> machinery introduced in this series.
>>>
>> And when we have two LSMs that want to use that?
> We'll cross that bridge when we come to it, but perhaps "last
> exclusive"? (lsm.enable/disable to choose)

If we define restrictions on use of LSM_ORDER_LAST like we have
for LSM_ORDER_FIRST (only for capabilities) before anyone starts
abusing it we may be OK. Since an LSM_ORDER_LAST has to know that
it can't count on getting called (a non-last module may return -EACCES)
I don't see any way that having multiple LSM_ORDER_LAST modules in
any given order would be a real problem. Of course, a module could be
doing state management that *really* requires it be last, but that
would be a badly designed module and someone sensible would NAK it.


  reply	other threads:[~2018-09-17 23:40 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-16  0:30 [PATCH 00/18] LSM: Prepare for explict LSM ordering Kees Cook
2018-09-16  0:30 ` [PATCH 01/18] vmlinux.lds.h: Avoid copy/paste of security_init section Kees Cook
2018-09-16  0:30 ` [PATCH 02/18] LSM: Rename .security_initcall section to .lsm_info Kees Cook
2018-09-16  0:30 ` [PATCH 03/18] LSM: Remove initcall tracing Kees Cook
2018-09-16  0:30 ` [PATCH 04/18] LSM: Convert from initcall to struct lsm_info Kees Cook
2018-09-16  0:30 ` [PATCH 05/18] vmlinux.lds.h: Move LSM_TABLE into INIT_DATA Kees Cook
2018-09-16  0:30 ` [PATCH 06/18] LSM: Convert security_initcall() into DEFINE_LSM() Kees Cook
2018-09-16  0:30 ` [PATCH 07/18] LSM: Add minor LSM initialization loop Kees Cook
2018-09-16  1:27   ` Jann Horn
2018-09-16  1:49     ` Kees Cook
2018-09-16  0:30 ` [PATCH 08/18] integrity: Initialize as LSM_TYPE_MINOR Kees Cook
2018-09-16  0:30 ` [PATCH 09/18] LSM: Record LSM name in struct lsm_info Kees Cook
2018-09-16  0:30 ` [PATCH 10/18] LSM: Plumb visibility into optional "enabled" state Kees Cook
2018-09-16  0:30 ` [PATCH 11/18] LSM: Lift LSM selection out of individual LSMs Kees Cook
2018-09-16  1:32   ` Jann Horn
2018-09-16  1:47     ` Kees Cook
2018-09-16  0:30 ` [PATCH 12/18] LSM: Introduce ordering details in struct lsm_info Kees Cook
2018-09-16  0:30 ` [PATCH 13/18] LoadPin: Initialize as LSM_TYPE_MINOR Kees Cook
2018-09-16  0:30 ` [PATCH 14/18] Yama: " Kees Cook
2018-09-16  0:30 ` [PATCH 15/18] capability: " Kees Cook
2018-09-16  0:30 ` [PATCH 16/18] LSM: Allow arbitrary LSM ordering Kees Cook
2018-09-16 18:49   ` Casey Schaufler
2018-09-16 23:00     ` Kees Cook
2018-09-17  0:46       ` Tetsuo Handa
2018-09-17 15:06       ` Casey Schaufler
2018-09-17 16:24         ` Kees Cook
2018-09-17 17:13           ` Casey Schaufler
2018-09-17 18:14             ` Kees Cook
2018-09-17 19:23               ` Casey Schaufler
2018-09-17 19:55                 ` John Johansen
2018-09-17 21:57                   ` Casey Schaufler
2018-09-17 22:36                     ` John Johansen
2018-09-17 23:10                       ` Mickaël Salaün
2018-09-17 23:20                         ` Kees Cook
2018-09-17 23:26                           ` John Johansen
2018-09-17 23:28                             ` Kees Cook
2018-09-17 23:40                               ` Casey Schaufler [this message]
2018-09-17 23:30                           ` Casey Schaufler
2018-09-17 23:47                             ` Mickaël Salaün
2018-09-18  0:00                               ` Casey Schaufler
2018-09-17 23:25                         ` John Johansen
2018-09-17 23:25                       ` Casey Schaufler
2018-09-18  0:00                       ` Kees Cook
2018-09-18  0:24                         ` Casey Schaufler
2018-09-18  0:45                           ` Kees Cook
2018-09-18  0:57                             ` Casey Schaufler
2018-09-18  0:59                               ` Kees Cook
2018-09-18  1:08                             ` John Johansen
2018-09-17 19:35               ` John Johansen
2018-09-16  0:30 ` [PATCH 17/18] LSM: Provide init debugging Kees Cook
2018-09-16  0:30 ` [PATCH 18/18] LSM: Don't ignore initialization failures Kees Cook

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