Re: [patch] xen udev rule interfering with openvpn

[Teck Choon Giam <giamteckchoon@gmail.com>]

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On Sun, May 13, 2012 at 7:37 AM, Teck Choon Giam
<giamteckchoon@gmail.com> wrote:
> On Sun, May 13, 2012 at 6:30 AM, Ian Campbell <Ian.Campbell@citrix.com> wrote:
>> On Sat, 2012-05-12 at 23:00 +0100, Teck Choon Giam wrote:
>>> On Sat, May 12, 2012 at 3:29 PM, Teck Choon Giam
>>> <giamteckchoon@gmail.com> wrote:
>>> > On Sat, May 12, 2012 at 7:53 AM, Teck Choon Giam
>>> > <giamteckchoon@gmail.com> wrote:
>>> >> On Fri, May 11, 2012 at 10:53 PM, Ian Jackson <Ian.Jackson@eu.citrix.com> wrote:
>>> >>> Ian Campbell writes ("Re: [Xen-devel] [patch] xen udev rule interfering with openvpn"):
>>> >>>> libxl/xend: name tap devices vifX.Y-emu
>>> >>>
>>> >>> Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
>>> >>
>>> >> This is my backport version which excludes the following:
>>> >>
>>> >> Lastly also move libxl__device_* to a better place in the header, otherwise the
>>> >> comment about evgen stuff isn't next to the associated functions (noticed jsut
>>> >> because I was going to add nic_devname near to the setdefault functions)
>>> >>
>>> >> I have tested with xm and xl with and without vifname set in domU
>>> >> config for hvmdomain and pvdomain.
>>> >
>>> > Sorry, when re-test one of the test case failed... xm create hvmdomain
>>> > with vifname set.  I must have missed certain test case :(
>>>
>>> The same test case failed for xen unstable latest changeset 25326:cd4dd23a831d.
>>
>> Oh dear.
>>
>>> My tests as below:
>>
>> Which ones fail?
>>
>>> 1. xm create pvdomain without vifname set
>>> 2. xl create pvdomain without vifname set
>>> 3. xm create hvmdomain without vifname set
>>> 4. xl create hvmdomain without vifname set
>>> 5. xm create pvdomain with vifname set
>>> 6. xl create pvdomain with vifname set
>>> 7. xm create hvmdomain with vifname set
>
> xm create hvmdomain with vifname set
>
>
> I track down the problem already.  It happens that xm and xl behave
> differently when creating $dev device?
>
> In short, just set $dev down before:
> do_or_die ip link set "$dev" name "$vifname"
> Then set $vifname up after the above fix my problem.
>
> Is the above suitable in upstream/unstable?  If yes, can you fix that
> in xen-unstable or you need me to submit a patch for review for
> xen-unstable?
>
> With the below partial of my latest backport patch fix the problem but
> I have to re-run all tests to double confirm all are fix and good to
> go :p

Attached is my final backport for xen-4.1-testing which passed all my
tests as stated below:

1. xm create pvdomain without vifname set
2. xl create pvdomain without vifname set
3. xm create hvmdomain without vifname set
4. xl create hvmdomain without vifname set
5. xm create pvdomain with vifname set
6. xl create pvdomain with vifname set
7. xm create hvmdomain with vifname set
8. xl create hvmdomain with vifname set

My initial backport patch failed for test no. 7 and when I perform
test for all the above in latest xen-unstable it failed in test no. 7
as well.

For review and comments please.

Thanks.

Kindest regards,
Giam Teck Choon


>
> diff --git a/tools/hotplug/Linux/vif-common.sh
> b/tools/hotplug/Linux/vif-common.sh
> index c9c5d41..86c0aaa 100644
> --- a/tools/hotplug/Linux/vif-common.sh
> +++ b/tools/hotplug/Linux/vif-common.sh
> @@ -85,12 +85,25 @@ elif [ "$type_if" = tap ]; then
>     : ${INTERFACE:?}
>
>     # Get xenbus_path from device name.
> -    # The name is built like that: "tap${domid}.${devid}".
> -    dev_=${dev#tap}
> +    # The name is built like that: "vif${domid}.${devid}-emu".
> +    dev_=${dev#vif}
> +    dev_=${dev_%-emu}
>     domid=${dev_%.*}
>     devid=${dev_#*.}
>
>     XENBUS_PATH="/local/domain/0/backend/vif/$domid/$devid"
> +    vifname=$(xenstore_read_default "$XENBUS_PATH/vifname" "")
> +    if [ "$vifname" ]
> +    then
> +        vifname="${vifname}-emu"
> +        if [ "$command" == "add" ] && ! ip link show "$vifname" >&/dev/null
> +        then
> +            ip link set "$dev" down
> +            do_or_die ip link set "$dev" name "$vifname"
> +            ip link set "$vifname" up
> +        fi
> +        dev="$vifname"
> +    fi
>  fi
>
>
> Thanks.
>
> Kindest regards,
> Giam Teck Choon
>
>
>
>>> 8. xl create hvmdomain with vifname set
>>>
>>> Thanks.
>>>
>>> Kindest regards,
>>>
>>>
>>> >
>>> > Kindest regards,
>>> > Giam Teck Choon
>>> >
>>> >
>>> >
>>> >>
>>> >> For your review and comments please.
>>> >>
>>> >> Thanks.
>>> >>
>>> >> Kindest regards,
>>> >> Giam Teck Choon
>>> >>
>>> >>
>>> >>
>>> >>
>>> >> libxl/xend: name tap devices vifX.Y-emu
>>> >>
>>> >> This prevents the udev scripts from operating on other tap devices (e.g.
>>> >> openvpn etc)
>>> >>
>>> >> Correct the documentation for the "vifname" option which suggested it applied
>>> >> to HVM tap devices only, which is not the case.
>>> >>
>>> >> Reported by Michael Young.
>>> >>
>>> >> Also fix the use of vifname with emulated devices. This is slightly complex.
>>> >> The current hotplug scripts rely on being able to parse the "tapX.Y" (now
>>> >> "vifX.Y-emu") name in order to locate the xenstore backend dir relating to the
>>> >> corresponding vif. This is because we cannot inject our own environment vars
>>> >> into the tap hotplug events. However this means that if the tap is initially
>>> >> named with a user specified name (which will not match the expected scheme) we
>>> >> fail to do anything useful with the device. So now we create the initial tap
>>> >> device with the standard "vifX.Y-emu" name and the hotplug script will handle
>>> >> the rename to the desired name. This is also how PV vif devices work -- they
>>> >> are always created by netback with the name vifX.Y and renamed in the script.
>>> >>
>>> >> xen-unstable changeset: 25290:7a6dcecb1781
>>> >> Signed-off-by: Giam Teck Choon <giamteckchoon@gmail.com>
>>> >> ---
>>> >>  tools/hotplug/Linux/vif-common.sh     |   15 +++++++++++++--
>>> >>  tools/hotplug/Linux/xen-backend.rules |    2 +-
>>> >>  tools/libxl/libxl_dm.c                |   17 ++++++-----------
>>> >>  tools/python/xen/xend/image.py        |    6 +-----
>>> >>  4 files changed, 21 insertions(+), 19 deletions(-)
>>> >>
>>> >> diff --git a/tools/hotplug/Linux/vif-common.sh
>>> >> b/tools/hotplug/Linux/vif-common.sh
>>> >> index c9c5d41..fff22bb 100644
>>> >> --- a/tools/hotplug/Linux/vif-common.sh
>>> >> +++ b/tools/hotplug/Linux/vif-common.sh
>>> >> @@ -85,12 +85,23 @@ elif [ "$type_if" = tap ]; then
>>> >>     : ${INTERFACE:?}
>>> >>
>>> >>     # Get xenbus_path from device name.
>>> >> -    # The name is built like that: "tap${domid}.${devid}".
>>> >> -    dev_=${dev#tap}
>>> >> +    # The name is built like that: "vif${domid}.${devid}-emu".
>>> >> +    dev_=${dev#vif}
>>> >> +    dev_=${dev_%-emu}
>>> >>     domid=${dev_%.*}
>>> >>     devid=${dev_#*.}
>>> >>
>>> >>     XENBUS_PATH="/local/domain/0/backend/vif/$domid/$devid"
>>> >> +    vifname=$(xenstore_read_default "$XENBUS_PATH/vifname" "")
>>> >> +    if [ "$vifname" ]
>>> >> +    then
>>> >> +        vifname="${vifname}-emu"
>>> >> +        if [ "$command" == "add" ] && ! ip link show "$vifname" >&/dev/null
>>> >> +        then
>>> >> +            do_or_die ip link set "$dev" name "$vifname"
>>> >> +        fi
>>> >> +        dev="$vifname"
>>> >> +    fi
>>> >>  fi
>>> >>
>>> >>  ip=${ip:-}
>>> >> diff --git a/tools/hotplug/Linux/xen-backend.rules
>>> >> b/tools/hotplug/Linux/xen-backend.rules
>>> >> index 40f2658..405387f 100644
>>> >> --- a/tools/hotplug/Linux/xen-backend.rules
>>> >> +++ b/tools/hotplug/Linux/xen-backend.rules
>>> >> @@ -13,4 +13,4 @@ KERNEL=="blktap-control",
>>> >> NAME="xen/blktap-2/control", MODE="0600"
>>> >>  KERNEL=="gntdev", NAME="xen/%k", MODE="0600"
>>> >>  KERNEL=="pci_iomul", NAME="xen/%k", MODE="0600"
>>> >>  KERNEL=="tapdev[a-z]*", NAME="xen/blktap-2/tapdev%m", MODE="0600"
>>> >> -SUBSYSTEM=="net", KERNEL=="tap*", ACTION=="add",
>>> >> RUN+="/etc/xen/scripts/vif-setup $env{ACTION} type_if=tap"
>>> >> +SUBSYSTEM=="net", KERNEL=="vif*-emu", ACTION=="add",
>>> >> RUN+="/etc/xen/scripts/vif-setup $env{ACTION} type_if=tap"
>>> >> diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
>>> >> index 1ffcc90..2c030ca 100644
>>> >> --- a/tools/libxl/libxl_dm.c
>>> >> +++ b/tools/libxl/libxl_dm.c
>>> >> @@ -134,11 +134,9 @@ static char **
>>> >> libxl_build_device_model_args_old(libxl__gc *gc,
>>> >>                 char *smac = libxl__sprintf(gc,
>>> >> "%02x:%02x:%02x:%02x:%02x:%02x",
>>> >>                                            vifs[i].mac[0],
>>> >> vifs[i].mac[1], vifs[i].mac[2],
>>> >>                                            vifs[i].mac[3],
>>> >> vifs[i].mac[4], vifs[i].mac[5]);
>>> >> -                char *ifname;
>>> >> -                if (!vifs[i].ifname)
>>> >> -                    ifname = libxl__sprintf(gc, "tap%d.%d",
>>> >> info->domid, vifs[i].devid);
>>> >> -                else
>>> >> -                    ifname = vifs[i].ifname;
>>> >> +                const char *ifname = libxl__sprintf(gc, "vif%d.%d-emu",
>>> >> +                                                    info->domid,
>>> >> +                                                    vifs[i].devid);
>>> >>                 flexarray_vappend(dm_args,
>>> >>                                 "-net", libxl__sprintf(gc,
>>> >> "nic,vlan=%d,macaddr=%s,model=%s",
>>> >>                                                        vifs[i].devid,
>>> >> smac, vifs[i].model),
>>> >> @@ -271,12 +269,9 @@ static char **
>>> >> libxl_build_device_model_args_new(libxl__gc *gc,
>>> >>                 char *smac = libxl__sprintf(gc,
>>> >> "%02x:%02x:%02x:%02x:%02x:%02x",
>>> >>                                            vifs[i].mac[0],
>>> >> vifs[i].mac[1], vifs[i].mac[2],
>>> >>                                            vifs[i].mac[3],
>>> >> vifs[i].mac[4], vifs[i].mac[5]);
>>> >> -                char *ifname;
>>> >> -                if (!vifs[i].ifname) {
>>> >> -                    ifname = libxl__sprintf(gc, "tap%d.%d",
>>> >> info->domid, vifs[i].devid);
>>> >> -                } else {
>>> >> -                    ifname = vifs[i].ifname;
>>> >> -                }
>>> >> +                const char *ifname = libxl__sprintf(gc, "vif%d.%d-emu",
>>> >> +                                                    info->domid,
>>> >> +                                                    vifs[i].devid);
>>> >>                 flexarray_append(dm_args, "-net");
>>> >>                 flexarray_append(dm_args, libxl__sprintf(gc,
>>> >> "nic,vlan=%d,macaddr=%s,model=%s",
>>> >>                             vifs[i].devid, smac, vifs[i].model));
>>> >> diff --git a/tools/python/xen/xend/image.py b/tools/python/xen/xend/image.py
>>> >> index f1464ac..3c8d80c 100644
>>> >> --- a/tools/python/xen/xend/image.py
>>> >> +++ b/tools/python/xen/xend/image.py
>>> >> @@ -917,11 +917,7 @@ class HVMImageHandler(ImageHandler):
>>> >>             ret.append("-net")
>>> >>             ret.append("nic,vlan=%d,macaddr=%s,model=%s" %
>>> >>                        (nics, mac, model))
>>> >> -            vifname = devinfo.get('vifname')
>>> >> -            if vifname:
>>> >> -                vifname = "tap-" + vifname
>>> >> -            else:
>>> >> -                vifname = "tap%d.%d" % (self.vm.getDomid(), nics-1)
>>> >> +            vifname = "vif%d.%d-emu" % (self.vm.getDomid(), nics-1)
>>> >>             ret.append("-net")
>>> >>             ret.append("tap,vlan=%d,ifname=%s,bridge=%s" %
>>> >>                        (nics, vifname, bridge))
>>
>>

[-- Attachment #2: backport-unstable-25290-to-xen-4.1-testing.patch --]
[-- Type: application/octet-stream, Size: 6130 bytes --]

libxl/xend: name tap devices vifX.Y-emu

This prevents the udev scripts from operating on other tap devices (e.g.
openvpn etc)

Correct the documentation for the "vifname" option which suggested it applied
to HVM tap devices only, which is not the case.

Reported by Michael Young.

Also fix the use of vifname with emulated devices. This is slightly complex.
The current hotplug scripts rely on being able to parse the "tapX.Y" (now
"vifX.Y-emu") name in order to locate the xenstore backend dir relating to the
corresponding vif. This is because we cannot inject our own environment vars
into the tap hotplug events. However this means that if the tap is initially
named with a user specified name (which will not match the expected scheme) we
fail to do anything useful with the device. So now we create the initial tap
device with the standard "vifX.Y-emu" name and the hotplug script will handle
the rename to the desired name. This is also how PV vif devices work -- they
are always created by netback with the name vifX.Y and renamed in the script.

xen-unstable changeset: 25290:7a6dcecb1781
Signed-off-by: Giam Teck Choon <giamteckchoon@gmail.com>
---
 tools/hotplug/Linux/vif-common.sh     |   17 +++++++++++++++--
 tools/hotplug/Linux/xen-backend.rules |    2 +-
 tools/libxl/libxl_dm.c                |   17 ++++++-----------
 tools/python/xen/xend/image.py        |    6 +-----
 4 files changed, 23 insertions(+), 19 deletions(-)

diff --git a/tools/hotplug/Linux/vif-common.sh b/tools/hotplug/Linux/vif-common.sh
index c9c5d41..86c0aaa 100644
--- a/tools/hotplug/Linux/vif-common.sh
+++ b/tools/hotplug/Linux/vif-common.sh
@@ -85,12 +85,25 @@ elif [ "$type_if" = tap ]; then
     : ${INTERFACE:?}
 
     # Get xenbus_path from device name.
-    # The name is built like that: "tap${domid}.${devid}".
-    dev_=${dev#tap}
+    # The name is built like that: "vif${domid}.${devid}-emu".
+    dev_=${dev#vif}
+    dev_=${dev_%-emu}
     domid=${dev_%.*}
     devid=${dev_#*.}
 
     XENBUS_PATH="/local/domain/0/backend/vif/$domid/$devid"
+    vifname=$(xenstore_read_default "$XENBUS_PATH/vifname" "")
+    if [ "$vifname" ]
+    then
+        vifname="${vifname}-emu"
+        if [ "$command" == "add" ] && ! ip link show "$vifname" >&/dev/null
+        then
+            ip link set "$dev" down
+            do_or_die ip link set "$dev" name "$vifname"
+            ip link set "$vifname" up
+        fi
+        dev="$vifname"
+    fi
 fi
 
 ip=${ip:-}
diff --git a/tools/hotplug/Linux/xen-backend.rules b/tools/hotplug/Linux/xen-backend.rules
index 40f2658..405387f 100644
--- a/tools/hotplug/Linux/xen-backend.rules
+++ b/tools/hotplug/Linux/xen-backend.rules
@@ -13,4 +13,4 @@ KERNEL=="blktap-control", NAME="xen/blktap-2/control", MODE="0600"
 KERNEL=="gntdev", NAME="xen/%k", MODE="0600"
 KERNEL=="pci_iomul", NAME="xen/%k", MODE="0600"
 KERNEL=="tapdev[a-z]*", NAME="xen/blktap-2/tapdev%m", MODE="0600"
-SUBSYSTEM=="net", KERNEL=="tap*", ACTION=="add", RUN+="/etc/xen/scripts/vif-setup $env{ACTION} type_if=tap"
+SUBSYSTEM=="net", KERNEL=="vif*-emu", ACTION=="add", RUN+="/etc/xen/scripts/vif-setup $env{ACTION} type_if=tap"
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 1ffcc90..2c030ca 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -134,11 +134,9 @@ static char ** libxl_build_device_model_args_old(libxl__gc *gc,
                 char *smac = libxl__sprintf(gc, "%02x:%02x:%02x:%02x:%02x:%02x",
                                            vifs[i].mac[0], vifs[i].mac[1], vifs[i].mac[2],
                                            vifs[i].mac[3], vifs[i].mac[4], vifs[i].mac[5]);
-                char *ifname;
-                if (!vifs[i].ifname)
-                    ifname = libxl__sprintf(gc, "tap%d.%d", info->domid, vifs[i].devid);
-                else
-                    ifname = vifs[i].ifname;
+                const char *ifname = libxl__sprintf(gc, "vif%d.%d-emu",
+                                                    info->domid,
+                                                    vifs[i].devid);
                 flexarray_vappend(dm_args,
                                 "-net", libxl__sprintf(gc, "nic,vlan=%d,macaddr=%s,model=%s",
                                                        vifs[i].devid, smac, vifs[i].model),
@@ -271,12 +269,9 @@ static char ** libxl_build_device_model_args_new(libxl__gc *gc,
                 char *smac = libxl__sprintf(gc, "%02x:%02x:%02x:%02x:%02x:%02x",
                                            vifs[i].mac[0], vifs[i].mac[1], vifs[i].mac[2],
                                            vifs[i].mac[3], vifs[i].mac[4], vifs[i].mac[5]);
-                char *ifname;
-                if (!vifs[i].ifname) {
-                    ifname = libxl__sprintf(gc, "tap%d.%d", info->domid, vifs[i].devid);
-                } else {
-                    ifname = vifs[i].ifname;
-                }
+                const char *ifname = libxl__sprintf(gc, "vif%d.%d-emu",
+                                                    info->domid,
+                                                    vifs[i].devid);
                 flexarray_append(dm_args, "-net");
                 flexarray_append(dm_args, libxl__sprintf(gc, "nic,vlan=%d,macaddr=%s,model=%s",
                             vifs[i].devid, smac, vifs[i].model));
diff --git a/tools/python/xen/xend/image.py b/tools/python/xen/xend/image.py
index f1464ac..3c8d80c 100644
--- a/tools/python/xen/xend/image.py
+++ b/tools/python/xen/xend/image.py
@@ -917,11 +917,7 @@ class HVMImageHandler(ImageHandler):
             ret.append("-net")
             ret.append("nic,vlan=%d,macaddr=%s,model=%s" %
                        (nics, mac, model))
-            vifname = devinfo.get('vifname')
-            if vifname:
-                vifname = "tap-" + vifname
-            else:
-                vifname = "tap%d.%d" % (self.vm.getDomid(), nics-1)
+            vifname = "vif%d.%d-emu" % (self.vm.getDomid(), nics-1)
             ret.append("-net")
             ret.append("tap,vlan=%d,ifname=%s,bridge=%s" %
                        (nics, vifname, bridge))

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