Fw: [Bug 66691] New: iproute2: macvlan: Wrong root device shown if in different netns

Fw: [Bug 66691] New: iproute2: macvlan: Wrong root device shown if in different netns

[Stephen Hemminger]

This isn't a iproute2 bug, it is only reporting what the kernel tells it

Begin forwarded message:

Date: Fri, 6 Dec 2013 00:07:15 -0800
From: "bugzilla-daemon@bugzilla.kernel.org" <bugzilla-daemon@bugzilla.kernel.org>
To: "stephen@networkplumber.org" <stephen@networkplumber.org>
Subject: [Bug 66691] New: iproute2: macvlan: Wrong root device shown if in different netns


https://bugzilla.kernel.org/show_bug.cgi?id=66691

            Bug ID: 66691
           Summary: iproute2: macvlan: Wrong root device shown if in
                    different netns
           Product: Networking
           Version: 2.5
    Kernel Version: 3.10
          Hardware: All
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Other
          Assignee: shemminger@linux-foundation.org
          Reporter: helmut.schaa@googlemail.com
        Regression: No

In the root net namespace if have the following devices:

> ip link
[...]
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
mode DEFAULT group default qlen 1000
    link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff
3: gre0: <NOARP> mtu 1476 qdisc noop state DOWN mode DEFAULT group default 
    link/gre 0.0.0.0 brd 0.0.0.0
[...]

Let's add a macvlan on top of eth0:

> ip link
[...]
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
mode DEFAULT group default qlen 1000
    link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff
3: gre0: <NOARP> mtu 1476 qdisc noop state DOWN mode DEFAULT group default 
    link/gre 0.0.0.0 brd 0.0.0.0
[...]
17: mac0@eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode
DEFAULT group default 
    link/ether 46:aa:b4:fb:44:a6 brd ff:ff:ff:ff:ff:ff

And now lets move it into its own net namespace and list the devices in the new
namespace.

> ip link set mac0 netns myns
> ip netns exec myns ip link
[...]
2: gre0: <NOARP> mtu 1476 qdisc noop state DOWN mode DEFAULT group default 
    link/gre 0.0.0.0 brd 0.0.0.0
[...]
17: mac0@gre0: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN mode
DEFAULT group default 
    link/ether 46:aa:b4:fb:44:a6 brd ff:ff:ff:ff:ff:ff

mac0 shows gre0 as its base device which is not correct. However gre0 has the
same ifindex in the new namespace as eth0 in the root namespace and the ifindex
is used for finding the base device.

commit aa79e66eee5d525e2fcbd2a5fcb87ae3dd4aa9e9 "net: Make ifindex generation
per-net namespace" changed the ifindex generation to only be unique within a
namespace.

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Re: Fw: [Bug 66691] New: iproute2: macvlan: Wrong root device shown if in different netns

[Kevin Wilson]

Hi,
Shouldn't the macvlan be network nsmespace local device, like the vlan
and VXLAN device (which have NETIF_F_NETNS set)?
When a nework device has the NETIF_F_NETNS flag set, it cannot be
moved from one network namespace to another.

Kevin W.

On Sat, Dec 7, 2013 at 1:38 AM, Kevin Wilson <wkevils@gmail.com> wrote:
> Hi,
> Shouldnt the macvlan be network nsmespace local device, like the vlan and
> vxlan device (which have NETIF_F_NETNS set)?
>
>
> On Friday, December 6, 2013, Stephen Hemminger <stephen@networkplumber.org>
> wrote:
>> This isn't a iproute2 bug, it is only reporting what the kernel tells it
>>
>> Begin forwarded message:
>>
>> Date: Fri, 6 Dec 2013 00:07:15 -0800
>> From: "bugzilla-daemon@bugzilla.kernel.org"
>> <bugzilla-daemon@bugzilla.kernel.org>
>> To: "stephen@networkplumber.org" <stephen@networkplumber.org>
>> Subject: [Bug 66691] New: iproute2: macvlan: Wrong root device shown if in
>> different netns
>>
>>
>> https://bugzilla.kernel.org/show_bug.cgi?id=66691
>>
>>             Bug ID: 66691
>>            Summary: iproute2: macvlan: Wrong root device shown if in
>>                     different netns
>>            Product: Networking
>>            Version: 2.5
>>     Kernel Version: 3.10
>>           Hardware: All
>>                 OS: Linux
>>               Tree: Mainline
>>             Status: NEW
>>           Severity: normal
>>           Priority: P1
>>          Component: Other
>>           Assignee: shemminger@linux-foundation.org
>>           Reporter: helmut.schaa@googlemail.com
>>         Regression: No
>>
>> In the root net namespace if have the following devices:
>>
>>> ip link
>> [...]
>> 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state
>> UP
>> mode DEFAULT group default qlen 1000
>>     link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff
>> 3: gre0: <NOARP> mtu 1476 qdisc noop state DOWN mode DEFAULT group default
>>     link/gre 0.0.0.0 brd 0.0.0.0
>> [...]
>>
>> Let's add a macvlan on top of eth0:
>>
>>> ip link
>> [...]
>> 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state
>> UP
>> mode DEFAULT group default qlen 1000
>>     link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff
>> 3: gre0: <NOARP> mtu 1476 qdisc noop state DOWN mode DEFAULT group default
>>     link/gre 0.0.0.0 brd 0.0.0.0
>> [...]
>> 17: mac0@eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode
>> DEFAULT group default
>>     link/ether 46:aa:b4:fb:44:a6 brd ff:ff:ff:ff:ff:ff
>>
>> And now lets move it into its own net namespace and list the devices in
>> the new
>> namespace.
>>
>>> ip link set mac0 netns myns
>>> ip netns exec myns ip link
>> [...]
>> 2: gre0: <NOARP> mtu 1476 qdisc noop state DOWN mode DEFAULT group default
>>     link/gre 0.0.0.0 brd 0.0.0.0
>> [...]
>> 17: mac0@gre0: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN
>> mode
>> DEFAULT group default
>>     link/ether 46:aa:b4:fb:44:a6 brd ff:ff:ff:ff:ff:ff
>>
>> mac0 shows gre0 as its base device which is not correct. However gre0 has
>> the
>> same ifindex in the new namespace as eth0 in the root namespace and the
>> ifindex
>> is used for finding the base device.
>>
>> commit aa79e66eee5d525e2fcbd2a5fcb87ae3dd4aa9e9 "net: Make ifindex
>> generation
>> per-net namespace" changed the ifindex generation to only be unique within
>> a
>> namespace.
>>
>> --
>> You are receiving this mail because:
>> You are the assignee for the bug.
>> --
>> To unsubscribe from this list: send the line "unsubscribe netdev" in
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>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>

Re: Fw: [Bug 66691] New: iproute2: macvlan: Wrong root device shown if in different netns

[Michal Kubecek]

On Sat, Dec 07, 2013 at 11:18:52AM +0200, Kevin Wilson wrote:
> Shouldn't the macvlan be network nsmespace local device, like the vlan
> and VXLAN device (which have NETIF_F_NETNS set)?
> When a nework device has the NETIF_F_NETNS flag set, it cannot be
> moved from one network namespace to another.

I don't think so. A setup where a macvlan is in a different namespace is
used quite often, e.g. to provide a network device to an LXC container.

                                                          Michal Kubecek

Re: Fw: [Bug 66691] New: iproute2: macvlan: Wrong root device shown if in different netns

[Helmut Schaa]

On Fri, Dec 6, 2013 at 9:05 PM, Stephen Hemminger
<stephen@networkplumber.org> wrote:
> This isn't a iproute2 bug, it is only reporting what the kernel tells it

But iproute2 assumes that the ifindex is unique within all net
namespaces. This isn't true anymore
after commit aa79e66eee5d525e2fcbd2a5fcb87ae3dd4aa9e9 "net: Make
ifindex generation
per-net namespace".

However, in order to do the right thing iproute2 would have to know
the ifindex of the
link device _and_ its associated netns.

Not sure how to deal with that ...
Helmut

Re: Fw: [Bug 66691] New: iproute2: macvlan: Wrong root device shown if in different netns

[Pavel Emelyanov]

On 12/16/2013 02:38 PM, Helmut Schaa wrote:
> On Fri, Dec 6, 2013 at 9:05 PM, Stephen Hemminger
> <stephen@networkplumber.org> wrote:
>> This isn't a iproute2 bug, it is only reporting what the kernel tells it
> 
> But iproute2 assumes that the ifindex is unique within all net
> namespaces. This isn't true anymore
> after commit aa79e66eee5d525e2fcbd2a5fcb87ae3dd4aa9e9 "net: Make
> ifindex generation
> per-net namespace".
> 
> However, in order to do the right thing iproute2 would have to know
> the ifindex of the
> link device _and_ its associated netns.
> 
> Not sure how to deal with that ...

Helmut, what would you expect to see from "ip netns exec myns ip link"
in case there were no device with ifindex 2 in the myns netns?

> Helmut
> .
> 

Re: Fw: [Bug 66691] New: iproute2: macvlan: Wrong root device shown if in different netns

[Helmut Schaa]

On Mon, Dec 16, 2013 at 11:41 AM, Pavel Emelyanov <xemul@parallels.com> wrote:
> On 12/16/2013 02:38 PM, Helmut Schaa wrote:
>> On Fri, Dec 6, 2013 at 9:05 PM, Stephen Hemminger
>> <stephen@networkplumber.org> wrote:
>>> This isn't a iproute2 bug, it is only reporting what the kernel tells it
>>
>> But iproute2 assumes that the ifindex is unique within all net
>> namespaces. This isn't true anymore
>> after commit aa79e66eee5d525e2fcbd2a5fcb87ae3dd4aa9e9 "net: Make
>> ifindex generation
>> per-net namespace".
>>
>> However, in order to do the right thing iproute2 would have to know
>> the ifindex of the
>> link device _and_ its associated netns.
>>
>> Not sure how to deal with that ...
>
> Helmut, what would you expect to see from "ip netns exec myns ip link"
> in case there were no device with ifindex 2 in the myns netns?

No idea, maybe something like "mac0@unknown" would be enough to express
that the link dev is not available within this netns.

My point was that it is confusing to show a clearly wrong link device.

Helmut

Re: Fw: [Bug 66691] New: iproute2: macvlan: Wrong root device shown if in different netns

[Pavel Emelyanov]

On 12/16/2013 02:47 PM, Helmut Schaa wrote:
> On Mon, Dec 16, 2013 at 11:41 AM, Pavel Emelyanov <xemul@parallels.com> wrote:
>> On 12/16/2013 02:38 PM, Helmut Schaa wrote:
>>> On Fri, Dec 6, 2013 at 9:05 PM, Stephen Hemminger
>>> <stephen@networkplumber.org> wrote:
>>>> This isn't a iproute2 bug, it is only reporting what the kernel tells it
>>>
>>> But iproute2 assumes that the ifindex is unique within all net
>>> namespaces. This isn't true anymore
>>> after commit aa79e66eee5d525e2fcbd2a5fcb87ae3dd4aa9e9 "net: Make
>>> ifindex generation
>>> per-net namespace".
>>>
>>> However, in order to do the right thing iproute2 would have to know
>>> the ifindex of the
>>> link device _and_ its associated netns.
>>>
>>> Not sure how to deal with that ...
>>
>> Helmut, what would you expect to see from "ip netns exec myns ip link"
>> in case there were no device with ifindex 2 in the myns netns?
> 
> No idea, maybe something like "mac0@unknown" would be enough to express
> that the link dev is not available within this netns.

Actually, I think the problem is deeper. For example, we have a veth device
driver, the devices of that kind always exist in pairs, and one device typically
sits in one namespaces, while the other device -- in another namespace.

Right now, given one veth device, there's no way to find out where its peer is.
This creates certain difficulties for the checkpoint-restore project (CRIU)
I'm working on.

Let me add Eric in a loop to ask for his thoughts about the issue.

> My point was that it is confusing to show a clearly wrong link device.

I totally agree.

> Helmut

Thanks,
Pavel