map serial port throws "chardev: opening backend "tty" failed"

Hi Otto! Could attach virtual machine configuration?

Thanks

Hi, here is the xml:

<domain type='kvm'>
  <name>web2</name>
  <uuid>17c99639-2299-ce13-c1b6-c7a627dd181e</uuid>
  <memory>2097152</memory>
  <currentMemory>2097152</currentMemory>
  <vcpu>1</vcpu>
  <os>
    <type arch='x86_64' machine='pc-0.11'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/bin/kvm</emulator>
    <disk type='block' device='disk'>
      <source dev='/dev/vmdata/web2'/>
      <target dev='vda' bus='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </disk>
    <interface type='bridge'>
      <mac address='52:54:00:68:45:ab'/>
      <source bridge='br305'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </interface>
    <serial type='dev'>
      <source path='/dev/ttyS14'/>
      <target port='0'/>
    </serial>
    <console type='dev'>
      <source path='/dev/ttyS14'/>
      <target port='0'/>
    </console>
    <input type='mouse' bus='ps2'/>
    <graphics type='vnc' port='-1' autoport='yes' listen='127.0.0.1' keymap='de'/>
    <sound model='es1370'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </sound>
    <video>
      <model type='cirrus' vram='9216' heads='1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </video>
  </devices>
</domain>

Hi Angel.

As you suggested to me in d-u-s i post this in launchpad.
Adding a parallel port, type device and source to /dev/parport0 throw the same error.

The xml definition:
<domain type='kvm'>
<name>vm-debian</name>
<uuid>711a217a-bd0c-003a-53b3-03d2828c743c</uuid>
<description>Maquina virtual con Debian</description>
<memory>524288</memory>
<currentMemory>524288</currentMemory>
<vcpu>1</vcpu>
<os>
<type arch='x86_64' machine='pc-0.12'>hvm</type>
<boot dev='hd'/>
</os>
<features>
<acpi/>
<apic/>
<pae/>
</features>
<clock offset='utc'/>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>restart</on_crash>
<devices>
<emulator>/usr/bin/kvm</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2'/>
<source file='/var/lib/libvirt/images/vd-debian.qcow2'/>
<target dev='hda' bus='ide'/>
<address type='drive' controller='0' bus='0' unit='0'/>
</disk>
<controller type='ide' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
</controller>
<interface type='bridge'>
<mac address='52:54:00:f7:81:2a'/>
<source bridge='br0'/>
<target dev='vnet0'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
</interface>
<serial type='pty'>
<target port='0'/>
</serial>
<parallel type='dev'>
<source path='/dev/parport0'/>
<target port='0'/>
</parallel>
<console type='pty'>
<target port='0'/>
</console>
<input type='mouse' bus='ps2'/>
<graphics type='vnc' port='-1' autoport='yes' keymap='es'/>
<video>
<model type='cirrus' vram='9216' heads='1'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
</video>
</devices>
</domain>

I can attach the log and debugin messages if it is necessary.

I don't run any version of Ubuntu but Debian Squeeze.

Testing with another virtual machine at diferent computer, same configuration this is the log:

LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin HOME=/ QEMU_AUDIO_DRV=none /usr/bin/kvm -S -M pc-0.12 -enable-kvm -m 512 -smp 1,sockets=1,cores=1,threads=1 -name vm0 -uuid 44f38697-90a8-04b2-27e5-abd3a9f3c29d -nodefaults -chardev socket,id=monitor,path=/var/lib/libvirt/qemu/vm0.monitor,server,nowait -mon chardev=monitor,mode=readline -rtc base=utc -boot c -drive file=/var/lib/libvirt/images/vdisk0.qcow2,if=none,id=drive-virtio-disk0,boot=on,format=qcow2 -device virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0 -device virtio-net-pci,vlan=0,id=net0,mac=52:54:00:2a:8d:ae,bus=pci.0,addr=0x5 -net tap,fd=36,vlan=0,name=hostnet0 -chardev pty,id=serial0 -device isa-serial,chardev=serial0 -chardev tty,id=parallel0,path=/dev/parport0 -device isa-parallel,chardev=parallel0 -usb -device usb-tablet,id=input0 -vnc 127.0.0.1:0 -k es -vga cirrus -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3
char device redirected to /dev/pts/4
chardev: opening backend "tty" failed

Same here

I request that the importance be heightened, as this also affects installation of new VMs, effectively making that impossible. I'd say that approaches a major fault...

i second that. it makes lucid currently unusable for us.

There seems to be a problem with the apparmor profile of libvirt (see bug #54579). After adding the line

/dev/ttyS* rw,

to /etc/apparmor.d/abstractions/libvirt-qemu and reloading the profile it worked for me.

Guenther, did you have AppArmor denials in your kern.log?

Can people try adding this to /etc/apparmor.d/abstractions/libvirt-qemu:
  owner /dev/ttyS* rw,

If that doesn't work, can you try:
  /dev/ttyS* rw,

Jamie, yes I have messages in kern.log:

Jun 8 08:55:01 srv4 kernel: [1100074.508951] type=1503 audit(1275980101.566:71): operation="open" pid=9648 parent=1 profile="libvirt-a4352cb3-c2b3-133a-4867-86c55a89709b" requested_mask="r::" denied_mask="r::" fsuid=0 ouid=0 name="/dev/ttyS0"

It looks like there has been some recent upstream work on this for SELinux. I will be taking a look at that for an update to AppArmor.

I have a similar bug, but I'm not sure if it's identical or unrelated..

The error I receive from libvirt is about the pty instead of tty.

ie:

Jul 15 16:11:56 arya libvirtd: 16:11:56.746: error : qemudWaitForMonitor:1536 : internal error unable to start guest: chardev: opening backend "pty" failed

However I don't have any notices in /var/log/kern.log about apparmor.

What do you think?

First sorry for the bad english. I have a similar problem with Ubuntu Lucid 10.04 amd64 Desktop edition using KVM.
Any virtual machine with a serial port (host device /dev/ttyS0) configured fails to start. Removing the serial port the VM works very well.
I use virt manager for the creation and management of the virtual machines .

This is the configuration file of the VM running Ubuntu Lucid 10.04 amd64 (like the host) but server edition

<domain type='kvm'>
  <name>deluge</name>
  <uuid>d8ada746-0538-089e-1215-0a1188977c81</uuid>
  <memory>262144</memory>
  <currentMemory>262144</currentMemory>
  <vcpu>1</vcpu>
  <os>
    <type arch='x86_64' machine='pc-0.12'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/bin/kvm</emulator>
    <disk type='block' device='disk'>
      <driver name='qemu' type='raw' cache='none'/>
      <source dev='/dev/lvmforkvm/deluge'/>
      <target dev='vda' bus='virtio'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
    </disk>
    <interface type='bridge'>
      <mac address='00:54:00:35:b8:12'/>
      <source bridge='br0'/>
      <model type='virtio'/>
    </interface>
    <serial type='dev'>
      <source path='/dev/ttyS0'/>
      <target port='0'/>
    </serial>
    <console type='dev'>
      <source path='/dev/ttyS0'/>
      <target port='0'/>
    </console>
    <input type='mouse' bus='ps2'/>
    <graphics type='vnc' port='-1' autoport='yes'/>
    <video>
      <model type='cirrus' vram='9216' heads='1'/>
    </video>
  </devices>
</domain>

And this is the error message that virt manager shows

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/engine.py", line 588, in run_domain
    vm.startup()
  File "/usr/share/virt-manager/virtManager/domain.py", line 150, in startup
    self._backend.create()
  File "/usr/lib/python2.6/dist-packages/libvirt.py", line 300, in create
    if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
libvirtError: monitor socket did not show up.: Connection refused

I agree with Fjodor, the importance should be heightened. Without serial port virtualization a lot of functionalities could be lost. For example i need the serial port for the installation of a fax server (hylafax) that is using a modem connected to the host's physical serial port (/dev/ttyS0).
If you need to do some tests I can do that

This bug was fixed in the package libvirt - 0.8.3-1ubuntu1

---------------
libvirt (0.8.3-1ubuntu1) maverick; urgency=low

  * Merge from debian unstable with security fixes
  * Fixes:
    - LP: #588369
    - LP: #585964
  * Remaining changes:
    - debian/control:
      + Build-Depends on qemu-kvm, not qemu
      + Build-Depends on open-iscsi-utils, not open-iscsi
      + Build-Depends on libxml2-utils
      + Build-Depends on libapparmor-dev and Suggests apparmor
      + Bump bridge-utils, dnsmasq-base, netcat-openbsd, and iptables
        to Depends of libvirt-bin
      + Drop lvm2, qemu-kvm and qemu to Suggests
      + We call libxen-dev libxen3-dev, so change all references
      + Rename Vcs-* to XS-Debian-Vcs-*
    - debian/libvirt-bin.postinst:
      + rename the libvirt group to libvirtd
      + add each admin user to the libvirtd group
      + reload apparmor profiles
    - debian/libvirt-bin.postrm:
      + rename the libvirt group to libvirtd
      + remove apparmor symlinks on purge
    - debian/README.Debian: add AppArmor section based on the upstream
      documentation
    - debian/rules:
      + update DEB_DH_INSTALLINIT_ARGS for upstart
      + add DEB_MAKE_CHECK_TARGET := check
      + use --with-apparmor
      + copy apparmor and apport hook to debian/tmp
    - add debian/libvirt-bin.upstart
    - debian/libvirt-bin.dirs: add /etc/apparmor.d/abstractions,
      /etc/apparmor.d/disable, /etc/apparmor.d/force-complain,
      /etc/apparmor.d/libvirt, /etc/cron.daily and
      /usr/share/apport/package-hooks
    - add debian/libvirt-bin.cron.daily
    - add debian/libvirt-bin.apport
    - debian/libvirt-bin.install: install apparmor profiles, abstractions
      and apport hook
    - debian/apparmor:
      - add TEMPLATE
      - add libvirt-qemu abstraction
      - add usr.lib.libvirt.virt-aa-helper
      - add usr.sbin.libvirtd
    - debian/patches/series:
      + don't apply 0002-qemu-disable-network.diff.patch
      + don't apply 0005-Terminate-nc-on-EOF.patch. Use
        9009-autodetect-nc-params.patch instead
      + 9000-delayed_iff_up_bridge.patch (refreshed)
      + 9001-dont_clobber_existing_bridges.patch
      + 9002-better_default_uri_virsh.patch (refreshed)
      + 9003-better-default-arch.patch (refreshsed)
      + 9004-libvirtd-group-name.patch
      + 9005-increase-unix-socket-timeout.patch (refreshed)
      + 9006-default-config-test-case.patch
      + 9007-fix-daemon-conf-ftbfs.patch (updated)
      + 9008-run-as-root-by-default.patch (refreshed)
      + 9009-autodetect-nc-params.patch (refreshed)
      + 9010-dont-disable-ipv6.patch (refreshsed)
      + 9011-move-ebtables-script.patch (refreshed)
  * Dropped the following patches included/fixed upstream:
    - 9012-fix-nodeinfotest-ftbfs.patch
    - 9013-apparmor-lp457716.patch
  * Disable virtualbox support since virtualbox-ose is not in main
    - debian/control: remove virtualbox-ose build dependency
    - debian/rules: use --without-vbox
  * debian/patches/9012-apparmor-dont-ignore-open.patch: fix logic when
    using virDomainDiskDefForeachPath() and add tests. This can be removed
    in 0.8.4.
  * debian/apparmor/usr.sbin.libvirtd: add capability fseti...

It seems I have the same error (on Lucid 64bit). I get 'opening backend "tty" failed' in my virtual machine log, and I get a kernel message in my syslog:

Aug 25 17:50:18 gaia kernel: [ 9109.444187] type=1505 audit(1282751418.474:90): operation="profile_remove" pid=10366 name="libvirt-c2d4403f-0e69-38f4-7641-ef6459dfc8a8" namespace="root"

I tried to edit /etc/apparmor.d/abstractions/libvirt-qemu, but to no avail.

I see there is a fix, but not for Lucid (0.7.5-5ubuntu27.2 seems to be current there). Any hint for how I could get this fixed under Lucid would be most appreciated.

I've followed comment #9 so I've added the following line to the end of /etc/apparmor.d/abstractions/libvirt-qemu
owner /dev/ttyS* rw,

And now it works fine :)
Thank you for the fix ;)

As I can see on my installation the following happens:

requested_mask="r::" denied_mask="r::"

but

virt-aa-helper.c:
    865 for (i = 0; i < ctl->def->nserials; i++)
    866 if (ctl->def->serials[i] && ctl->def->serials[i]->data.file.path)
    867 if (vah_add_file(&buf,
    868 ctl->def->serials[i]->data.file.path, "w") != 0)
    869 goto clean;
    870
    871 if (ctl->def->console && ctl->def->console->data.file.path)
    872 if (vah_add_file(&buf, ctl->def->console->data.file.path, "w") != 0)
    873 goto clean;

so apparmor profiles contain e.g. /dev/ttyS0 w, which allows writing to the file, but not reading :-/

Since I am being bit by this every time libvirt update is issued I have put the libvirt binary with the patch attached to my ppa:rye/ppa archive.

lucid has seen the end of its life and is no longer receiving any updates. Marking the lucid task for this ticket as "Won't Fix".