Messages in this thread | | | Date | Fri, 29 Feb 2008 09:38:11 -0600 | From | serge@hallyn ... | Subject | Re: [PATCH 0/2] Fix /proc/net in presence of net namespaces |
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Quoting Pavel Emelyanov (xemul@openvz.org): > [snip] > > >> However at least for visibility and inspection we want that. > >> We want to inspect what is happening to other processes. If we didn't > >> care then all of the pid namespaces could just be disjoint. > > > > But the way Pavel has it coded, only tasks in the init namespace can > > view /proc/.net/* for any other net namespaces. > > This is not essential part of the patch :) I did so to make my > life in init namespace easier. This part can be dropped. > > [snip] > > >> Think of user space processes inspecting /proc etc. > > > > Well a task in one pid namespace cannot view the /proc for another pid > > namespace, right? > > No. Pid namespace provides another pid-to-task map, but have noting > to do with VFS visibility. > > >> Having directory > >> names change out form under you for no apparent reason is pretty nasty. > > > > Yes, but they won't just 'change out' from under you, you ask for it... > > But here like I said I do prefer an approach where /proc/net is bind > > mounted by the user. But I have no good reason to back it up... > > If you make /proc/net be a bund mount then you have to force all of > the users to update their init scripts. I tried to make so with sysctl > filesystem, but this thread was not very popular :)
Ok.
A symlink is far preferable to sneaky redirection imo.
> Another way to do so - is to mount this one from inside the kernel, > but are you ready to fight with Al Viro for this? :)
Nope :) Especially since it's an ugly idea.
> [snip] > > >> So I think /proc/.netns/ or simply /proc/netns/ is a good choice. We > >> just need a non-global id for our directory entries so we don't paint > >> ourselves into a corner. > > > > But I don't see how this is going to work. If you're using a pid_nr > > inside a pid namespace, then you're not guaranteeing that the pid_nr > > will be unique, so you may not be able to create th e/proc/.netns/X > > directory. If you're using the global pid, then you're not guaranteeing > > that it will be available upon a container restart. > > Right - this is the same as using other ids, which I propose. > > >> And honestly pid visibility is a very natural choice for which network > >> namespaces you can see. You can see the namespace of any process you > >> can see. Which especially means your children. It is an arbitrary > >> rule, it is a simple rule to explain, and it works recursively unlike > > > > But apparently not simple enough for a simpleton like me to understand, > > sorry :( > > > >> any init_net is special rule. > >> > >> Eric
I suspect I'm misunderstanding Eric's proposal, though.
-serge
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