On 29.03.2016 14:10, Thomas Haller wrote: > On Tue, 2016-03-29 at 13:13 +0200, Stjepan Groš wrote: >> On 29.03.2016 12:52, Thomas Haller wrote: >>> On Sat, 2016-02-27 at 09:34 +0100, Stjepan Groš wrote: >>>> Hi! >>> Hi Stjepan, >>> >>> after the changes done to master, I took your MIF branch, and re- >>> merged >>> master into it. The result is here: >>> >>> https://cgit.freedesktop.org/NetworkManager/NetworkManager/log/?h=t >>> h/mif >>> >>> I didn't actually test it, so don't expect it to work. >>> >>> >>> Anyway, I hope it might be useful for you. >>> Thomas >> >> Hi Thomas, >> >> thanks for the merge. I'll take a look at it. >> >> In the last few days I also managed to merge HEAD with MIF branch and >> to remove some stuff that probably will not be needed (like >> activating specific network namespaces from within >> NMNetnsController). I have to admit that on several occasions I was >> thinking of throwing everything away and starting from scratch, but >> that wouldn't take me far... > I think for prototyping this is fine. We should identify places that > can be individually fixed on master to prepare master for namespace > support. Kinda making small steps on master to move it towards the > namespace branch. > >> Anyway, I just pushed all the changes I have to GitHub. Quick test >> shows that NM works. >> >> I hit the following obstacles/problems/things: > Oh, I see. > > > >> 1. I have yet to try to figure out how did you intend >> NMPlatform/NMPNetns to work in order to better integrate that into >> MIF Branch. (maybe your merge will help here) >> >> 2. You create singleton NMPlatform object while network namespace >> support needs many. So, how/where/what to do. > Currently on master there is only one NM_PLATFORM_GET instance. But in > your branch, you will create multiple platform instances.
I already did that, there is still NM_PLATFORM_GET for NMManager object.
>
>
>> 3. How to create new network namespace from outside of NMPlatform
>> object.
> There are two separate things: NMPNetns and NMNetns.
>
> NMPNetns is a very simple object to hold the file descriptor of the
> namespace, it does setns() and you can use nmp_netns_new() to create a
> new namespace (unshare).
I think nmp_netns_new() has to accept name of network namespace that
will be created in /var/run/netns directory.
>
> NMNetns is a higher level object to represent the namespace. It is not
> concerned with unshare()/setns() or the file descriptor. It consists of
> instances of NMPNetns, NMPlatform, NMRouteManager, NMPolicy(?), etc.
> As in your branch, it also takes over some work from NMManager.
>
> On the higher layer you don't need to switch to a namespace -- that's
> why I dropped nm_netns_controller_activate_netns(). When a lower layer
> object does something for which it needs a certain namespace, it must
> switch itself (via its NMPNetns instance).
>
>
>> 4. When creating new network namespace in NMPlatform NETLINK sockets
>> are created, but before they are created network namespace has to be
>> switched.
> NMPlatform *
> _create_new_platform_in_new_namespace ()
> {
> NMPNetns
> *netnsp;
> NMPlatform *platoform;
>
> /* create a new namespace and switch to it */
> netnsp = nmp_netns_new ();
> if (!netnsp)
> return NULL;
>
> /* create a new platform instance in the new namespace */
> platform = nm_linux_platform_new();
>
> /* return to the previous namespace: */
> nmp_netns_pop (netnsp);
>
> /* The namespace is also referenced by the platform instance.
> Depending on what we want, we can drop our reference at this
> point. It's still accessible via nm_platform_netns_get(). */
> g_object_unref (netnsp);
> return platform;
> }
Yes, something like that.
>
>
>
>> 5. NMPolicy isn't singleton any more, and it is not tied to NMManager
>> object but to the NMNetns object.
> I didn't really understand what to do with policy. NMPolicy is mostly
> concerned about the default-route and resolv.conf. Do you even need
> that in other namespaces? Maybe it should only exist in the main
> namespace.
You definitely need separate resolv.conf in network namespace in order
to be able to have different DNS servers.
"ip netns exec" bind mounts resolv.conf from /etc/netns/<netnsname> if
it exists over /etc/resolv.conf.
>
>> 6. Certain aspects of NMManager are global for every network
>> namespace, others are not. For example, sleeping state (or should it
>> be separate for every network namespace so that some network
>> namespaces can be suspended?).
>>
>> 7. Related to 7, the best approach would be to refactor NMManager
>> itself, but that would make very hard to keep HEAD and MIF branches
>> in sync.
> Right, this was the biggest confusion I had. Your NMNetns takes over
> some work of NMManager, while NMManager is global. I guess that makes
> sense.
> But currently it's unclear which instance (NMManager,
> NMNetnsController, NMNetns, NMPolicy) does what, and how the interact
> with namespaces.
>
> I think this is difficult to get right. I think that NMNetns should be
> as simple as possible and more tell NMManager what to do.
If you make NMNetns as simple as possible then NMManager must take care
of network related changes within different network namespaces, i.e. new
devices, IP addresses,etc. This, in turn, migh require all the methods
from NMManager to be extended with additional argument - network
namespace - which could possibly complicate things.
It seems to me that it is lot easier to basically transform NMManager
into NMNetns because root network namespace is just one possible network
namespace. All the current functionality done by NMManager within root
network namespace should be done in every network namespace. Of course,
NMManager should stay, but only with the functionality common to all
network namespaces.
Now, it could be that the approach of making NMNetns as simple as
possible is better approach, but only way to find out is to try to make
it so - which I think is non-trivial.
SG
>
>> Anyway, I got to the step where I can invoke D-Bus method to create
>> new network namespace and I have to debug that use case now.
> Thomas
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