Bug 240342

Summary: ifconfig denied access to storage device on xen guest creation
Product: Red Hat Enterprise Linux 5 Reporter: Chris Evich <cevich>
Component: xenAssignee: Xen Maintainance List <xen-maint>
Severity: medium Docs Contact:
Priority: low    
Version: 5.0   
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2007-07-16 20:42:03 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Description Flags
Wrapper script to run strace against /sbin/ifconfig.real
Trace of ifconfig made using the attached wrapper. none

Description Chris Evich 2007-05-16 16:30:25 UTC
Description of problem:
I have a rhel4 full-virt. guest setup with it's storage backed by the
/dev/vg1/rhel4 LV.  On domain creation, I'm getting a SELinux denied the access
of ifconfig to access /dev/vg1/rhel4?!?!?!?!?

Version-Release number of selected component (if applicable):

How reproducible:
every time

Steps to Reproduce:
1. Setup a full-virt guest backed by a LV
2. xm create <name>
Actual results:
Domain is created, access is denied for ifconfig to the guests storage device.

Expected results:
Domain is created, no access is needed to a block device by ifconfig.

Additional info:
avc: denied { read, write } for comm="ifconfig" dev=tmpfs egid=0 euid=0
exe="/sbin/ifconfig" exit=0 fsgid=0 fsuid=0 gid=0 items=0 name="vg1-rhel4"
path="/dev/mapper/vg1-rhel4" pid=4715 scontext=system_u:system_r:ifconfig_t:s0
sgid=0 subj=system_u:system_r:ifconfig_t:s0 suid=0 tclass=blk_file
tcontext=system_u:object_r:fixed_disk_device_t:s0 tty=(none) uid=0

Comment 1 Chris Evich 2007-05-16 16:30:25 UTC
Created attachment 154841 [details]
Wrapper script to run strace against /sbin/ifconfig.real

Comment 2 Chris Evich 2007-05-16 16:39:53 UTC
Created attachment 154842 [details]
Trace of ifconfig made using the attached wrapper.

Had to relabel the wrapper script, but using it did produce the same AVC denial

Comment 4 Daniel Walsh 2007-05-18 12:56:48 UTC
Does this cause the xen guest to fail?  Or are you just seeing an AVC message?

Comment 5 Chris Evich 2007-05-18 14:04:00 UTC
As far as I can tell the guest starts up and runs fine.  It cannot access the
network since dom0's iptables rh-firewall-1 is up, but that's another bug
(vif-common.sh appends rule instead of inserting it at top).  So, the only thing
I'm being bothered with is the AVC message.  What really concerns me isn't the
xen stuff here, it's the fact that ifconfig is trying to access the block device
in the first place.  Not sure if this is an ifconfig problem or a xm/xen problem.

Comment 6 Daniel Walsh 2007-07-16 20:37:39 UTC
This is a leaked file descriptor from xen.  xen has an open file descriptor to
the fixed device and when it execs the ifconfig script, the program transitions
to the other domain.  When an SELinux kernel starts to transition and
executable, it checks the access of all open file descriptors, in this case
generating avc messages.  The kernel then closes the file descriptors and
continues with the execution.  So this is really a xen problem.

Comment 7 Daniel Berrangé 2007-07-16 20:42:03 UTC
This is fixed in RHEL-5.1  RPMs.

*** This bug has been marked as a duplicate of 230790 ***