linux-kernel - Re: [Regression?] 1ea0ce4069 ("selinux: allow changing labels for cgroupfs") stops Android from booting

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Message-ID: <CAFJ0LnG_cZnC9Ajjvn9G=KkU57+nUx7iAG4qBkEQX1PJrZqJ1A@mail.gmail.com>
Date:   Fri, 24 Feb 2017 19:44:51 -0800
From:   Nick Kralevich <nnk@...gle.com>
To:     John Stultz <john.stultz@...aro.org>
Cc:     Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <sds@...ho.nsa.gov>,
        Jeffrey Vander Stoep <jeffv@...gle.com>,
        Antonio Murdaca <amurdaca@...hat.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Android Kernel Team <kernel-team@...roid.com>
Subject: Re: [Regression?] 1ea0ce4069 ("selinux: allow changing labels for
 cgroupfs") stops Android from booting

Can you try adding the androidboot.selinux=permissive line to the kernel
command line, to boot in permissive mode? I suspect the policy just needs
to be adjusted.

-- Nick

On Fri, Feb 24, 2017 at 6:01 PM, John Stultz <john.stultz@...aro.org> wrote:
> On Thu, Feb 23, 2017 at 4:01 PM, Paul Moore <paul@...l-moore.com> wrote:
>> On Thu, Feb 23, 2017 at 1:43 PM, John Stultz <john.stultz@...aro.org> wrote:
>>> Hey folks,
>>>    I've not been able to figure out why yet, but I wanted to raise the
>>> issue that last night I found I couldn't boot Android on my Hikey
>>> board with Linus' HEAD kernel. It seems to cause logd to crash
>>> repeatedly so I'm not able to get debug info from logcat.
>>>
>>> I do see the following over and over on the console:
>>>
>>> [   12.505838] init: computing context for service 'logd'
>>> [   12.506355] init: starting service 'logd'...
>>> [   12.507683] init: property_set("ro.boottime.logd", "12500792498")
>>> failed: property already set
>>> [   12.508701] init: Created socket '/dev/socket/logd', mode 666, user
>>> 1036, group 1036
>>> [   12.509294] init: Created socket '/dev/socket/logdr', mode 666,
>>> user 1036, group 1036
>>> [   12.509891] init: Created socket '/dev/socket/logdw', mode 222,
>>> user 1036, group 1036
>>> [   12.510132] init: Opened file '/proc/kmsg', flags 0
>>> [   12.510187] init: Opened file '/dev/kmsg', flags 1
>>> [   12.510353] init: couldn't write 1941 to
>>> /dev/cpuset/system-background/tasks: No such file or directory
>>> [   12.533046] init: Service 'logd' (pid 1941) exited with status 255
>>>
>>>
>>> I did some bisection and narrowed it down to 1ea0ce4069 ("selinux:
>>> allow changing labels for cgroupfs"), which was merged in yesterday.
>>> I've not yet been able to figure out the root cause, but reverting
>>> that patch makes things work again.
>>>
>>> So I wanted to raise the issue here so folks were aware.
>>>
>>> If there is anything folks want me to test or try, please let me know.
>>
>> Unfortunately I don't have an Android test system to play with, have
>> any of the SEAndroid folks on the To/CC line seen a similar problem?
>
> So from my very limited knowledge here, adding the patch in question
> seems to make the cgroup mount get the SBLABEL_MNT flag?
> Which I'm guessing this is causing additional selinux restrictions on
> processes accessing cgroup mounts, which causes some of the early
> initialization processes to fail?
>
> Should this change mean the selinux policy needs to be updated?
>
> thanks
> -john



-- 
Nick Kralevich | Android Security | nnk@...gle.com | 650.214.4037