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On 10/14/2011 08:17 PM, Trey Dockendorf wrote:
> I recently began getting periodic emails from SEalert that SELinux
> is preventing /usr/libexec/qemu-kvm "getattr" access from the
> directory I store all my virtual machines for KVM.
>
> All VMs are stored under /vmstore , which is it's own mount point,
> and every file and folder under /vmstore currently has the correct
> context that was set by doing the following:
>
> semanage fcontext -a -t virt_image_t "/vmstore(/.*)?" restorecon -R
> /vmstore
>
> So far I've noticed then when taking snapshots and also when using
> virsh to make changes to a domain's XML file. I haven't had any
> problems for the 3 or 4 months I've run this KVM server using
> SELinux on Enforcing, and so I'm not really sure what information
> is helpful to debug this. The server is CentOS 6 x86_64 updated to
> CR. This is the raw audit entry, (hostname removed)
>
> node=kvmhost.tld type=AVC msg=audit(1318634450.285:28): avc: denied
> { getattr } for pid=1842 comm="qemu-kvm" name="/" dev=dm-2 ino=2
> scontext=system_u:system_r:svirt_t:s0:c772,c779
> tcontext=system_u:object_r:fs_t:s0 tclass=filesystem
> node=kvmhost.tld type=SYSCALL msg=audit(1318634450.285:28):
> arch=c000003e syscall=138 success=no exit=-13 a0=9 a1=7fff1cf153f0
> a2=0 a3=7fff1cf15170 items=0 ppid=1 pid=1842 auid=4294967295
> uid=107 gid=107 euid=107 suid=107 fsuid=107 egid=107 sgid=107
> fsgid=107 tty=(none) ses=4294967295 comm="qemu-kvm"
> exe="/usr/libexec/qemu-kvm"
> subj=system_u:system_r:svirt_t:s0:c772,c779 key=(null)
>
> I've attached the alert email as a quote below, (hostname removed)
>
> Any help is greatly appreciated, I've had to deal little with
> SELinux fortunately, but at the moment am not really sure if my
> snapshots are actually functional or if this is just some false
> positive.
>
> Thanks - Trey
>
> Summary
>>
>> SELinux is preventing /usr/libexec/qemu-kvm "getattr" access on
>> /vmstore.
>>
>> 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
>>
>> You can generate a local policy module to allow this access - see
>> FAQ
>>> Please file a bug report.
>>
>> Additional Information
>>
>> Source Context: system_u:system_r:svirt_t:s0:c772,c779
>>
>> Target Context: system_u:object_r:fs_t:s0
>>
>> Target Objects: /vmstore [ filesystem ]
>>
>> Source: qemu-kvm
>>
>> Source Path: /usr/libexec/qemu-kvm
>>
>> Port: <Unknown>
>>
>> Host: kvmhost.tld
>>
>> Source RPM Packages: qemu-kvm-0.12.1.2-2.160.el6_1.8
>>
>> Target RPM Packages:
>>
>> Policy RPM: selinux-policy-3.7.19-93.el6_1.7
>>
>> Selinux Enabled: True
>>
>> Policy Type: targeted
>>
>> Enforcing Mode: Enforcing
>>
>> Plugin Name: catchall
>>
>> Host Name: kvmhost.tld
>>
>> Platform: Linux kvmhost.tld 2.6.32-71.29.1.el6.x86_64 #1 SMP
>> Mon Jun 27
>>> 19:49:27 BST 2011 x86_64 x86_64
>>
>> Alert Count: 1
>>
>> First Seen: Fri Oct 14 18:20:50 2011
>>
>> Last Seen: Fri Oct 14 18:20:50 2011
>>
>> Local ID: c73c7440-06ee-4611-80ac-712207ef9aa6
>>
>> Line Numbers:
>>
>> Raw Audit Messages :
>>
>>
>>> node=kvmhost.tld type=AVC msg=audit(1318634450.285:28): avc:
>>> denied { getattr } for pid=1842 comm="qemu-kvm" name="/"
>>> dev=dm-2 ino=2 scontext=system_u:system_r:svirt_t:s0:c772,c779
>>> tcontext=system_u:object_r:fs_t:s0 tclass=filesystem
>>
>> node=kvmhost.tld type=SYSCALL msg=audit(1318634450.285:28):
>> arch=c000003e
>>> syscall=138 success=no exit=-13 a0=9 a1=7fff1cf153f0 a2=0
>>> a3=7fff1cf15170 items=0 ppid=1 pid=1842 auid=4294967295 uid=107
>>> gid=107 euid=107 suid=107 fsuid=107 egid=107 sgid=107 fsgid=107
>>> tty=(none) ses=4294967295 comm="qemu-kvm"
>>> exe="/usr/libexec/qemu-kvm"
>>> subj=system_u:system_r:svirt_t:s0:c772,c779 key=(null)
>>
>>
>>
> _______________________________________________ CentOS mailing
> list CentOS@xxxxxxxxxx
> http://lists.centos.org/mailman/listinfo/centos
THis is a bug in policy. It can be allowed for now.
We have 6.2 selinux-policy preview package available on
http://people.redhat.com/dwalsh/SELinux/RHEL6
I believe all that is happening is qemu-kvm is noticing you have a
file system mounted, and doing a getattr on it.
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