virt January 2010

virt@lists.centos.org

26 participants
14 discussions

KVM Guest not using MAC address specified in XML file
by Neil Aggarwal 11 Jan '10

11 Jan '10

Hello: I have a server running Centos 5.4 with KVM. When I specify a MAC address in a guest's XML file: <interface type='bridge'> <mac address='00:00:00:00:10:67'/> <source bridge='br0'/> <target dev='v1067'/> </interface> I get a different answer from ifconfig: v1067 Link encap:Ethernet HWaddr D2:7A:F7:E5:09:B0 Any ideas why the address is different? Thanks, Neil -- Neil Aggarwal, (281)846-8957, http://UnmeteredVPS.net CentOS 5.4 VPS with unmetered bandwidth only $25/month! No overage charges, 7 day free trial, PayPal, Google Checkout

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QEMU/KVM: SELinux denial on /dev/zero when starting a VM
by Mathieu Baudier 08 Jan '10

08 Jan '10

Hi, on an up to date CentOS 5.4 x86_64 (test machine), I systematically get the following SELinux denial when I start a QEMU/KVM virtual machine via virt-manager: SELinux is preventing qemu-kvm (qemu_t) "execute" to /dev/zero (zero_device_t). (full alert below) Running the command suggested by the alert (restorecon -v '/dev/zero') does not solve the problem. This does not prevent the VM to run, but I would like to better understand what is happening here and the potential impact on performance. And if there is not impact, find a way to get rid of this warning... Thanks in advance for any idea! Mathieu Summary: SELinux is preventing qemu-kvm (qemu_t) "execute" to /dev/zero (zero_device_t). Detailed Description: SELinux denied access requested by qemu-kvm. It is not expected that this access is required by qemu-kvm and this access may signal an intrusion attempt. It is also possible that the specific version or configuration of the application is causing it to require additional access. Allowing Access: Sometimes labeling problems can cause SELinux denials. You could try to restore the default system file context for /dev/zero, restorecon -v '/dev/zero' If this does not work, there is currently no automatic way to allow this access. Instead, you can generate a local policy module to allow this access - see FAQ (http://fedora.redhat.com/docs/selinux-faq-fc5/#id2961385) Or you can disable SELinux protection altogether. Disabling SELinux protection is not recommended. Please file a bug report (http://bugzilla.redhat.com/bugzilla/enter_bug.cgi) against this package. Additional Information: Source Context system_u:system_r:qemu_t:SystemLow-SystemHigh Target Context system_u:object_r:zero_device_t Target Objects /dev/zero [ chr_file ] Source qemu-kvm Source Path /usr/libexec/qemu-kvm Port <Unknown> Host alma Source RPM Packages kvm-83-105.el5_4.13 Target RPM Packages Policy RPM selinux-policy-2.4.6-255.el5_4.1 Selinux Enabled True Policy Type targeted MLS Enabled True Enforcing Mode Enforcing Plugin Name catchall_file Host Name alma Platform Linux alma 2.6.18-164.9.1.el5 #1 SMP Tue Dec 15 20:57:57 EST 2009 x86_64 x86_64 Alert Count 10 First Seen Tue 05 Jan 2010 05:12:20 AM CET Last Seen Tue 05 Jan 2010 05:22:03 AM CET Local ID 8fb024fb-aa09-4177-84d7-55e5156e9538 Line Numbers Raw Audit Messages host=alma type=AVC msg=audit(1262665323.833:106): avc: denied { execute } for pid=8901 comm="qemu-kvm" path="/dev/zero" dev=tmpfs ino=2421 scontext=system_u:system_r:qemu_t:s0-s0:c0.c1023 tcontext=system_u:object_r:zero_device_t:s0 tclass=chr_file host=alma type=SYSCALL msg=audit(1262665323.833:106): arch=c000003e syscall=9 success=no exit=-13 a0=0 a1=2000 a2=7 a3=2 items=0 ppid=1 pid=8901 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=4294967295 comm="qemu-kvm" exe="/usr/libexec/qemu-kvm" subj=system_u:system_r:qemu_t:s0-s0:c0.c1023 key=(null)

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Re: [CentOS-virt] Xen box down
by Christopher G. Stach II 07 Jan '10

07 Jan '10

----- "Ben M." <centos(a)rivint.com> wrote: > Error is: "duplicate or bad block in use" It's probably just that fsck can't automatically fix some dirtiness and not a big deal. If you aren't prompted for a password or to log in to fix manually, get to the grub menu, edit the grub command line, stick ``single'' and/or ``init=/bin/sh'' on the end, boot, and run fsck manually. If you just want the machine up in a possibly slightly fucked state, just answer "yes" to everything. If not and you care a little bit about maybe getting some data back, see the next paragraph. (It's usually not that bad unless you have a skilled enemy or very bad luck.) You can probably have someone do all of it over the phone. If it doesn't even get that far or fsck can't fix it automatically, you're probably screwed. Whenever that has happened to me, I just do a block level dump of the partition/disk and recover from that image. It's a lot easier. Anyway, it is probably fine. If it isn't, you can always try pulling each of the disks or setting it back to use a single disk to try and isolate the problem. Also, switch to MD RAID. :) -- Christopher G. Stach II http://ldsys.net/~cgs/

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Xen box down
by Ben M. 05 Jan '10

05 Jan '10

My stock CentOS 5.4 box won't come up after a reboot as reported from my office. Error is: "duplicate or bad block in use" Before rebooting xm dmsg had printk suppressed messages. The box is remote, 2 hour drive. Some advice on what hardware to bring with me and how to approach this via fsck would be welcome. Its an nvidia dmraid boot on WD Velocirapters. And Happy New Year to all. - Ben M.

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virt January 2010