linux-kernel - Re: selinux vs devtmpfs (vs udev)

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Date:	Tue, 31 Aug 2010 17:49:30 +0200
From:	Harald Hoyer <harald@...hat.com>
To:	Eric Paris <eparis@...hat.com>
CC:	Daniel J Walsh <dwalsh@...hat.com>,
	Kay Sievers <kay.sievers@...y.org>,
	linux-kernel@...r.kernel.org, selinux@...ho.nsa.gov,
	greg@...ah.com, sds@...ho.nsa.gov
Subject: Re: selinux vs devtmpfs (vs udev)

On 08/31/2010 05:26 PM, Eric Paris wrote:
> On Tue, 2010-08-31 at 11:22 -0400, Daniel J Walsh wrote:
>> On 08/31/2010 11:16 AM, Eric Paris wrote:
>
>>> I suggest a third options: Calculate the default at startup and on every
>>> policy load and fix object labels if they are the default.  I'm sure Dan
>>> knows a code example of how to do the calculation.  The pseudocode looks
>>> something like:
>>
>>
>>>
>>> lookup the label on /dev
>>> lookup the label on the initial task
>>> ask the kernel what the resulting label on a file transition with those
>>> two pieces of information will be.
>>
>>
>> NOOOOO
>>
>> libvirt is going in and changing fixed_disk_device_t:s0 to svirt_t:c0,c124
>>
>> We do not want udev to see this and ask what label a device should have
>> if libvirtd_t created a chr_file in device_t.
>
> initial task == /sbin/init
>
> actually I should look if the kernel init_cred (what devtmpfs uses to
> make security decisions) is initrc_t or kernel_t.  I'm guessing it is
> kernel_t but I'm not certain how that gets set.....
>
> -Eric
>

https://bugzilla.redhat.com/show_bug.cgi?id=575128#c14
https://bugzilla.redhat.com/attachment.cgi?id=442223&format=raw

udev/udev-node.c

+			/* set selinux file context on add events */
+			if (strcmp(udev_device_get_action(dev), "add") == 0)
+				udev_selinux_lsetfilecon(udev, file, mode);
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