Messages in this thread | | | From | (Eric W. Biederman) | Subject | Re: [PATCH] Make /proc/net a symlink on /proc/self/net (v2) | Date | Thu, 06 Mar 2008 08:57:41 -0700 |
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Pavel Emelyanov <xemul@openvz.org> writes:
> Current /proc/net is done with so called "shadows", but current > implementation is broken and has little chances to get fixed. > > The problem is that dentries subtree of /proc/net directory has > fancy revalidation rules to make processes living in different > net namespaces see different entries in /proc/net subtree, but > currently, tasks see in the /proc/net subdir the contents of any > other namespace, depending on who opened the file first. > > The proposed fix is to turn /proc/net into a symlink, which points > to /proc/self/net, which in turn shows what previously was in > /proc/net - the network-related info, from the net namespace the > appropriate task lives in. > > # ls -l /proc/net > lrwxrwxrwx 1 root root 8 Mar 5 15:17 /proc/net -> self/net > > In other words - this behaves like /proc/mounts, but unlike > "mounts", "net" is not a file, but a directory. > > Fixed a task_struct leak in get_proc_task_net, pointed out by Paul. > > Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Before I forget.
As a future patch we need to implement a d_revalidate rule for /proc/<pid>/task/net that will notice we have unshared a network namespace and flush all cached dentries for the old network namespace.
Since unsharing happens rarely if at all this d_revalidate should be relatively cheap, and since the change is real and for everyone it will not suffer from the inconsistencies that plagued us when working with d_revalidate on /proc/net.
Eric
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