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From: Randy Dunlap <rdunlap@infradead.org>
To: Kees Cook <keescook@chromium.org>, James Morris <jmorris@namei.org>
Cc: John Johansen <john.johansen@canonical.com>,
	Jordan Glover <Golden_Miller83@protonmail.ch>,
	Stephen Smalley <sds@tycho.nsa.gov>,
	Paul Moore <paul@paul-moore.com>,
	Casey Schaufler <casey@schaufler-ca.com>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	"Schaufler, Casey" <casey.schaufler@intel.com>,
	linux-security-module <linux-security-module@vger.kernel.org>,
	Jonathan Corbet <corbet@lwn.net>,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH security-next v4 23/32] selinux: Remove boot parameter
Date: Wed, 3 Oct 2018 16:59:15 -0700	[thread overview]
Message-ID: <6037a1f0-7af1-9847-91f6-6444f04f5b21@infradead.org> (raw)
In-Reply-To: <CAGXu5jJDBhFrdCBHH4MZVDmG88mMxSaSx0w9anCcyx24YHLO5w@mail.gmail.com>

On 10/3/18 4:55 PM, Kees Cook wrote:
> On Wed, Oct 3, 2018 at 2:34 PM, James Morris <jmorris@namei.org> wrote:
>> On Wed, 3 Oct 2018, Kees Cook wrote:
>>
>>> On Wed, Oct 3, 2018 at 11:28 AM, James Morris <jmorris@namei.org> wrote:
>>>> On Wed, 3 Oct 2018, Kees Cook wrote:
>>>>
>>>>> On Wed, Oct 3, 2018 at 11:17 AM, James Morris <jmorris@namei.org> wrote:
>>>>>> On Tue, 2 Oct 2018, John Johansen wrote:
>>>>>>> To me a list like
>>>>>>>   lsm.enable=X,Y,Z
>>>>>>
>>>>>> What about even simpler:
>>>>>>
>>>>>> lsm=selinux,!apparmor,yama
>>>>>
>>>>> We're going to have lsm.order=, so I'd like to keep it with a dot
>>>>> separator (this makes it more like module parameters, too). You want
>>>>> to mix enable/disable in the same string? That implies you'd want
>>>>> implicit enabling (i.e. it complements the builtin enabling), which is
>>>>> opposite from what John wanted.
>>>>>
>>>>
>>>> Why can't this be the order as well?
>>>
>>> That was covered extensively in the earlier threads. It boils down to
>>> making sure we do not create a pattern of leaving LSMs disabled by
>>> default when they are added to the kernel. The v1 series used
>>> security= like this:
>>>
>>> +       security=       [SECURITY] An ordered comma-separated list of
>>> +                       security modules to attempt to enable at boot. If
>>> +                       this boot parameter is not specified, only the
>>> +                       security modules asking for initialization will be
>>> +                       enabled (see CONFIG_DEFAULT_SECURITY). Duplicate
>>> +                       or invalid security modules will be ignored. The
>>> +                       capability module is always loaded first, without
>>> +                       regard to this parameter.
>>>
>>> This meant booting "security=apparmor" would disable all the other
>>> LSMs, which wasn't friendly at all. So "security=" was left alone (to
>>> leave it to only select the "major" LSM: all major LSMs not matching
>>> "security=" would be disabled). So I proposed "lsm.order=" to specify
>>> the order things were going to be initialized in, but to avoid kernels
>>> booting with newly added LSMs forced-off due to not being listed in
>>> "lsm.order=", it had to have implicit fall-back for unlisted LSMs.
>>> (i.e. anything missing from lsm.order would then follow their order in
>>> CONFIG_LSM_ORDER, and anything missing there would fall back to
>>> link-time ordering.) However, then the objection was raised that this
>>> didn't provide a way to explicitly disable an LSM. So I proposed
>>> lsm.enable/disable, and John argued for CONFIG_LSM_ENABLE over
>>> CONFIG_LSM_DISABLE.
>>
>> Ok, but it may end up being clearer, simpler, and thus more secure to just
>> have a single way to configure LSM.
>>
>> For example:
>>
>>   - All LSMs which are built are NOT enabled by default
>>
>>   - You specify enablement and order via a Kconfig:
>>
>>         CONFIG_LSM="selinux,yama"
>>
>>   - This can be entirely overridden by a boot param:
>>
>>         lsm="apparmor,landlock"
> 
> This doesn't work with how SELinux and AppArmor do their bootparams,
> unfortunately. (And Paul and Stephen have expressed that the
> documented selinux on/off must continue to work.) For example, let's
> say you've built an Ubuntu kernel with:
> 
> CONFIG_SELINUX=y
> ...
> CONFIG_LSM="yama,apparmor"
> 
> (i.e. you want SELinux available, but not enabled, so it's left out of
> CONFIG_LSM)
> 
> Then someone boots the system with:
> 
> selinux=1 security=selinux
> 
> In what order does selinux get initialized relative to yama?
> (apparmor, flagged as a "legacy major", would have been disabled by
> the "security=" not matching it.)
> 

To me, "security=selinux" means SELinux and nothing else, so I think that
all of these params are inviting a lot of confusion.

Sorry, I don't have a good answer for this.

> 
> The LSM order needs to be defined externally to enablement because
> something may become enabled when not listed in the order.
> 
> Now, maybe I misunderstood your earlier suggestion, and what you meant
> was to do something like:
> 
> CONFIG_LSM="yama,apparmor,!selinux"
> 
> to mean "put selinux here in the order, but don't enable it". Then the
> problem becomes what happens to an LSM that has been built in but not
> listed in CONFIG_LSM?
> 
> Related to that, this means that when new LSMs are added, they will
> need to be added to any custom CONFIG_LSM= or lsm= parameters. If
> that's really how we have to go, I'll accept it, but I think it's a
> bit unfriendly. :P
> 
> Another reason I don't like it is because it requires users to know
> about all the LSMs to make changes. One LSM can't be added/removed
> without specifying ALL of the LSMs. (i.e. there is no trivial way to
> enable/disable a single LSM without it growing its own enable/disable
> code as in SELinux/AppArmor. I'd hoped to make that easier for both
> users and developers.) Again, I can live with it, but I think it's
> unfriendly.
> 
> I just want to have a direct I can go that meets all the requirements.
> :) I'm fine to ignore my sense of aesthetics if everyone can agree on
> the code.


-- 
~Randy

  parent reply	other threads:[~2018-10-03 23:59 UTC|newest]

Thread overview: 184+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-02  0:54 [PATCH security-next v4 00/32] LSM: Explict LSM ordering Kees Cook
2018-10-02  0:54 ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 01/32] LSM: Correctly announce start of LSM initialization Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 02/32] vmlinux.lds.h: Avoid copy/paste of security_init section Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 03/32] LSM: Rename .security_initcall section to .lsm_info Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 04/32] LSM: Remove initcall tracing Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02 21:14   ` James Morris
2018-10-02 21:14     ` James Morris
2018-10-02  0:54 ` [PATCH security-next v4 05/32] LSM: Convert from initcall to struct lsm_info Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 06/32] vmlinux.lds.h: Move LSM_TABLE into INIT_DATA Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02 21:15   ` James Morris
2018-10-02 21:15     ` James Morris
2018-10-02  0:54 ` [PATCH security-next v4 07/32] LSM: Convert security_initcall() into DEFINE_LSM() Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02 21:16   ` James Morris
2018-10-02 21:16     ` James Morris
2018-10-02  0:54 ` [PATCH security-next v4 08/32] LSM: Record LSM name in struct lsm_info Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 09/32] LSM: Provide init debugging infrastructure Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02 21:17   ` James Morris
2018-10-02 21:17     ` James Morris
2018-10-02  0:54 ` [PATCH security-next v4 10/32] LSM: Don't ignore initialization failures Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02 21:20   ` James Morris
2018-10-02 21:20     ` James Morris
2018-10-02 21:38     ` Kees Cook
2018-10-02 21:38       ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 11/32] LSM: Introduce LSM_FLAG_LEGACY_MAJOR Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 12/32] LSM: Provide separate ordered initialization Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 13/32] LoadPin: Rename "enable" to "enforce" Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  1:06   ` Randy Dunlap
2018-10-02  1:06     ` Randy Dunlap
2018-10-02  4:47     ` Kees Cook
2018-10-02  4:47       ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 14/32] LSM: Plumb visibility into optional "enabled" state Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 15/32] LSM: Lift LSM selection out of individual LSMs Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 16/32] LSM: Prepare for arbitrary LSM enabling Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 17/32] LSM: Introduce CONFIG_LSM_ENABLE Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 18/32] LSM: Introduce lsm.enable= and lsm.disable= Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 19/32] LSM: Prepare for reorganizing "security=" logic Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 20/32] LSM: Refactor "security=" in terms of enable/disable Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 21/32] LSM: Finalize centralized LSM enabling logic Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  1:18   ` Randy Dunlap
2018-10-02  1:18     ` Randy Dunlap
2018-10-02  4:49     ` Kees Cook
2018-10-02  4:49       ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 22/32] apparmor: Remove boot parameter Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 23/32] selinux: " Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02 12:12   ` Paul Moore
2018-10-02 12:12     ` Paul Moore
2018-10-02 13:42     ` Stephen Smalley
2018-10-02 13:42       ` Stephen Smalley
2018-10-02 14:44       ` Kees Cook
2018-10-02 14:44         ` Kees Cook
2018-10-02 14:58         ` Stephen Smalley
2018-10-02 14:58           ` Stephen Smalley
2018-10-02 16:33           ` Jordan Glover
2018-10-02 16:33             ` Jordan Glover
2018-10-02 16:54             ` Kees Cook
2018-10-02 16:54               ` Kees Cook
2018-10-02 18:33               ` Stephen Smalley
2018-10-02 18:33                 ` Stephen Smalley
2018-10-02 19:02                 ` Kees Cook
2018-10-02 19:02                   ` Kees Cook
2018-10-02 18:57               ` John Johansen
2018-10-02 18:57                 ` John Johansen
2018-10-02 19:17                 ` Kees Cook
2018-10-02 19:17                   ` Kees Cook
2018-10-02 19:47                   ` John Johansen
2018-10-02 19:47                     ` John Johansen
2018-10-02 20:29                     ` Kees Cook
2018-10-02 20:29                       ` Kees Cook
2018-10-02 21:11                       ` John Johansen
2018-10-02 21:11                         ` John Johansen
2018-10-02 22:06                   ` James Morris
2018-10-02 22:06                     ` James Morris
2018-10-02 23:06                     ` Kees Cook
2018-10-02 23:06                       ` Kees Cook
2018-10-02 23:46                       ` John Johansen
2018-10-02 23:46                         ` John Johansen
2018-10-02 23:54                         ` Kees Cook
2018-10-02 23:54                           ` Kees Cook
2018-10-03  0:05                           ` John Johansen
2018-10-03  0:05                             ` John Johansen
2018-10-03  0:12                             ` Kees Cook
2018-10-03  0:12                               ` Kees Cook
2018-10-03 13:15                               ` John Johansen
2018-10-03 13:15                                 ` John Johansen
2018-10-03 13:39                           ` Stephen Smalley
2018-10-03 13:39                             ` Stephen Smalley
2018-10-03 17:26                             ` Kees Cook
2018-10-03 17:26                               ` Kees Cook
2018-10-03 19:43                               ` Stephen Smalley
2018-10-03 19:43                                 ` Stephen Smalley
2018-10-04  5:38                               ` John Johansen
2018-10-04  5:38                                 ` John Johansen
2018-10-04 16:02                                 ` Kees Cook
2018-10-04 16:02                                   ` Kees Cook
2018-10-08 14:25                                 ` Paul Moore
2018-10-08 14:25                                   ` Paul Moore
2018-10-03 18:17                         ` James Morris
2018-10-03 18:17                           ` James Morris
2018-10-03 18:20                           ` Kees Cook
2018-10-03 18:20                             ` Kees Cook
2018-10-03 18:28                             ` James Morris
2018-10-03 18:28                               ` James Morris
2018-10-03 20:10                               ` Kees Cook
2018-10-03 20:10                                 ` Kees Cook
2018-10-03 20:36                                 ` Kees Cook
2018-10-03 20:36                                   ` Kees Cook
2018-10-03 21:19                                   ` James Morris
2018-10-03 21:19                                     ` James Morris
2018-10-04  5:56                                   ` John Johansen
2018-10-04  5:56                                     ` John Johansen
2018-10-04 16:18                                     ` Kees Cook
2018-10-04 16:18                                       ` Kees Cook
2018-10-04 17:40                                       ` Jordan Glover
2018-10-04 17:40                                         ` Jordan Glover
2018-10-04 17:42                                         ` Kees Cook
2018-10-04 17:42                                           ` Kees Cook
2018-10-03 21:34                                 ` James Morris
2018-10-03 21:34                                   ` James Morris
2018-10-03 23:55                                   ` Kees Cook
2018-10-03 23:55                                     ` Kees Cook
2018-10-03 23:59                                     ` Randy Dunlap [this message]
2018-10-03 23:59                                       ` Randy Dunlap
2018-10-04  0:03                                       ` Kees Cook
2018-10-04  0:03                                         ` Kees Cook
2018-10-04  6:22                                       ` John Johansen
2018-10-04  6:22                                         ` John Johansen
2018-10-04  6:18                                     ` John Johansen
2018-10-04  6:18                                       ` John Johansen
2018-10-04 17:49                                     ` James Morris
2018-10-04 17:49                                       ` James Morris
2018-10-05  0:05                                       ` Kees Cook
2018-10-05  0:05                                         ` Kees Cook
2018-10-05  4:58                                         ` James Morris
2018-10-05  4:58                                           ` James Morris
2018-10-05 16:29                                           ` James Morris
2018-10-05 16:29                                             ` James Morris
2018-10-05 16:35                                           ` Kees Cook
2018-10-05 16:35                                             ` Kees Cook
2018-10-02 23:28                     ` John Johansen
2018-10-02 23:28                       ` John Johansen
2018-10-02 16:34           ` Kees Cook
2018-10-02 16:34             ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 24/32] LSM: Build ordered list of ordered LSMs for init Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 25/32] LSM: Introduce CONFIG_LSM_ORDER Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:54 ` [PATCH security-next v4 26/32] LSM: Introduce "lsm.order=" for boottime ordering Kees Cook
2018-10-02  0:54   ` Kees Cook
2018-10-02  0:55 ` [PATCH security-next v4 27/32] LoadPin: Initialize as ordered LSM Kees Cook
2018-10-02  0:55   ` Kees Cook
2018-10-02  0:55 ` [PATCH security-next v4 28/32] Yama: " Kees Cook
2018-10-02  0:55   ` Kees Cook
2018-10-02  0:55 ` [PATCH security-next v4 29/32] LSM: Introduce enum lsm_order Kees Cook
2018-10-02  0:55   ` Kees Cook
2018-10-02  0:55 ` [PATCH security-next v4 30/32] capability: Initialize as LSM_ORDER_FIRST Kees Cook
2018-10-02  0:55   ` Kees Cook
2018-10-02  0:55 ` [PATCH security-next v4 31/32] LSM: Separate idea of "major" LSM from "exclusive" LSM Kees Cook
2018-10-02  0:55   ` Kees Cook
2018-10-02  0:55 ` [PATCH security-next v4 32/32] LSM: Add all exclusive LSMs to ordered initialization Kees Cook
2018-10-02  0:55   ` Kees Cook

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