[PATCH net-next v4 0/4] netns: allow to identify peer netns
Eric W. Biederman
ebiederm at xmission.com
Thu Oct 30 18:41:03 UTC 2014
Nicolas Dichtel <nicolas.dichtel at 6wind.com> writes:
> The goal of this serie is to be able to multicast netlink messages with an
> attribute that identify a peer netns.
> This is needed by the userland to interpret some informations contained in
> netlink messages (like IFLA_LINK value, but also some other attributes in case
> of x-netns netdevice (see also
> http://thread.gmane.org/gmane.linux.network/315933/focus=316064 and
> Ids of peer netns are set by userland via a new genl messages. These ids are
> stored per netns and are local (ie only valid in the netns where they are set).
> To avoid allocating an int for each peer netns, I use idr_for_each() to retrieve
> the id of a peer netns. Note that it will be possible to add a table (struct net
> -> id) later to optimize this lookup if needed.
> Patch 1/4 introduces the netlink API mechanism to set and get these ids.
> Patch 2/4 and 3/4 implements an example of how to use these ids in rtnetlink
> messages. And patch 4/4 shows that the netlink messages can be symetric between
> a GET and a SET.
> iproute2 patches are available, I can send them on demand.
A quick reply. I think this patchset is in the right general direction.
There are some oddball details that seem odd/awkward to me such as using
genetlink instead of rtnetlink to get and set the ids, and not having
ids if they are not set (that feels like a maintenance/usability challenge).
I would like to give your patches a deep review, but I won't be able to
do that for a couple of weeks. I am deep in the process of moving,
and will be mostly offline until about the Nov 11th.
> Here is a small screenshot to show how it can be used by userland.
> First, setup netns and required ids:
> $ ip netns add foo
> $ ip netns del foo
> $ ip netns
> $ touch /var/run/netns/init_net
> $ mount --bind /proc/1/ns/net /var/run/netns/init_net
> $ ip netns add foo
> $ ip netns exec foo ip netns set init_net 0
> $ ip netns
> $ ip netns exec foo ip netns
> init_net (id: 0)
> Now, add and display an ipip tunnel, with its link part in init_net (id 0 in
> netns foo) and the netdevice in foo:
> $ ip netns exec foo ip link add ipip1 link-netnsid 0 type ipip remote 10.16.0.121 local 10.16.0.249
> $ ip netns exec foo ip l ls ipip1
> 6: ipip1 at NONE: <POINTOPOINT,NOARP> mtu 1480 qdisc noop state DOWN mode DEFAULT group default
> link/ipip 10.16.0.249 peer 10.16.0.121 link-netnsid 0
> The parameter link-netnsid shows us where the interface sends and receives
> packets (and thus we know where encapsulated addresses are set).
> RFCv3 -> v4:
> rebase on net-next
> add copyright text in the new netns.h file
> RFCv2 -> RFCv3:
> ids are now defined by userland (via netlink). Ids are stored in each netns
> (and they are local to this netns).
> add get_link_net support for ip6 tunnels
> netnsid is now a s32 instead of a u32
> RFCv1 -> RFCv2:
> remove useless ()
> ids are now stored in the user ns. It's possible to get an id for a peer netns
> only if the current netns and the peer netns have the same user ns parent.
> MAINTAINERS | 1 +
> include/net/ip6_tunnel.h | 1 +
> include/net/ip_tunnels.h | 1 +
> include/net/net_namespace.h | 5 ++
> include/net/rtnetlink.h | 2 +
> include/uapi/linux/Kbuild | 1 +
> include/uapi/linux/if_link.h | 1 +
> include/uapi/linux/netns.h | 38 +++++++++
> net/core/net_namespace.c | 195 +++++++++++++++++++++++++++++++++++++++++++
> net/core/rtnetlink.c | 38 ++++++++-
> net/ipv4/ip_gre.c | 2 +
> net/ipv4/ip_tunnel.c | 8 ++
> net/ipv4/ip_vti.c | 1 +
> net/ipv4/ipip.c | 1 +
> net/ipv6/ip6_gre.c | 1 +
> net/ipv6/ip6_tunnel.c | 9 ++
> net/ipv6/ip6_vti.c | 1 +
> net/ipv6/sit.c | 1 +
> net/netlink/genetlink.c | 4 +
> 19 files changed, 308 insertions(+), 3 deletions(-)
> Comments are welcome.
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