"W. Trevor King" <wking@xxxxxxxxxx> writes: 2> On Sat, Jul 23, 2016 at 02:38:56PM -0700, James Bottomley wrote: >> On Sat, 2016-07-23 at 14:14 -0700, W. Trevor King wrote: >> > namespaces(7) and clone(2) both have: >> > >> > When a network namespace is freed (i.e., when the last process >> > in the namespace terminates), its physical network devices are >> > moved back to the initial network namespace (not to the parent >> > of the process). >> > >> > So the initial network namespace (the head of net_namespace_list?) >> > is special [1]. To understand how physical network devices will >> > be handled, it seems like we want to treat network devices as a >> > depth-1 tree, with all non-initial net namespaces as children of >> > the initial net namespace. Can we extend this series' >> > NS_GET_PARENT to return: >> > >> > * EPERM for an unprivileged caller (like this series currently does >> > for PID namespaces), >> > * ENOENT when called on net_namespace_list, and >> > * net_namespace_list when called on any other net namespace. >> >> What's the practical application of this? independent net >> namespaces are managed by the ip netns command. It pins them by a >> bind mount in a flat fashion; if we make them hierarchical the tool >> would probably need updating to reflect this, so we're going to need >> a reason to give the network people. Just having the interfaces not >> go back to root when you do an ip netns delete doesn't seem very >> compelling. > > I'm not suggesting we add support for deeper nesting, I'm suggesting > we use NS_GET_PARENT to allow sufficiently privileged users to > determine if a given net namespace is the initial net namespace. You > could do this already with something like: > > 1. Create a new net namespace. > 2. Add a physical network device to that namespace. > 3. Delete that namespace. > 4. See if the physical network device shows up in your > initial-net-namespace candidate. > 5. Delete the physical network device (hopefully it ended up somewhere > you can find it ;). > > But using an NS_GET_PARENT call seems much safer and easier. Have you had the problem in practice where you can't tell which network namespace is the initial network namespace. This all seems like a theoretical problem rather than a real one. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
