Messages in this thread | | | Date | Tue, 31 Aug 2010 16:39:22 +0200 | From | Harald Hoyer <> | Subject | Re: selinux vs devtmpfs (vs udev) |
| |
On 08/31/2010 04:11 PM, Daniel J Walsh wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 08/31/2010 04:44 AM, Harald Hoyer wrote: >> On 08/31/2010 01:14 AM, Eric Paris wrote: >>> On Sat, 2010-08-28 at 11:57 +0200, Kay Sievers wrote: >>>> On Sat, Aug 28, 2010 at 01:00, Eric Paris<eparis@redhat.com> wrote: >>> >>>>> In the new new days of devtmpfs things aren't as nice. The kernel is >>>>> magically creating files in /dev. These are getting created with the >>>>> 'default' SELinux context. So herein lies the problem. >>>>> >>>>> The first program that tries to access these files get denied by >>>>> SELinux. Now udev actually has logic in it to fix the label on any >>>>> closed device file, so udev will at that point swoop in, fix the label, >>>>> and the next program that tries to use the file will work just >>>>> fine. Oh >>>>> fun! >>> >>>> Udev should still label all device nodes, even when they are created >>>> by the kernel. Devtmpfs or not should not make a difference here. >>>> >>>> I guess it's a udev bug introduced with: >>>> >>>> http://git.kernel.org/?p=linux/hotplug/udev.git;a=commitdiff;h=578cc8a8085a47c963b5940459e475ac5f07219c >>>> >>>> >>>> and we just need to fix that. >>> >>> Looks like the likely cause. I see a note in one of the bugzillas that >>> says: >>> >>> Aug 30 14:03:09 pippin udevd-work[347]: preserve file '/dev/dri/card0', >>> because it has correct dev_t >>> >>> Which is certainly the part of code in question. Do you have a quick >>> fix in mind that you plan to push upstream or should I ask the RH udev >>> guy to come up with something? >>> >>> -Eric >>> >> >> The RH udev guy says: >> >> This patch was introduced, because Red Hat engineers requested, that the >> selinux context should not be modified, after they set their own custom >> context (virtual machine management). >> >> So, either we differentiate between "add" and "change" events, or we >> should check against the "kernel default" selinux context, before we >> call udev_selinux_lsetfilecon(). >> > So the problem is happening because the kernel creates the device rather > then udev, and then udev does not change the context because it can not > differentiate between this and libvirt putting down a label.
Is there an easy test to differentiate?
| |