[lkml]   [2007]   [Dec]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 2.6.24-rc3] Fix /proc/net breakage
Andrew Morton wrote:
> On Fri, 07 Dec 2007 04:51:37 +0000 David Woodhouse <> wrote:
>> On Mon, 2007-11-26 at 15:17 -0700, Eric W. Biederman wrote:
>>> Well I clearly goofed when I added the initial network namespace support
>>> for /proc/net. Currently things work but there are odd details visible
>>> to user space, even when we have a single network namespace.
>>> Since we do not cache proc_dir_entry dentries at the moment we can
>>> just modify ->lookup to return a different directory inode depending
>>> on the network namespace of the process looking at /proc/net, replacing
>>> the current technique of using a magic and fragile follow_link method.
>>> To accomplish that this patch:
>>> - introduces a shadow_proc method to allow different dentries to
>>> be returned from proc_lookup.
>>> - Removes the old /proc/net follow_link magic
>>> - Fixes a weakness in our not caching of proc generic dentries.
>>> As shadow_proc uses a task struct to decided which dentry to return we
>>> can go back later and fix the proc generic caching without modifying any code that
>>> uses the shadow_proc method.
>>> Signed-off-by: Eric W. Biederman <>
>>> ---
>>> fs/proc/generic.c | 12 ++++++-
>>> fs/proc/proc_net.c | 86 +++--------------------------------------------
>>> include/linux/proc_fs.h | 3 ++
>>> 3 files changed, 19 insertions(+), 82 deletions(-)
>> (commit 2b1e300a9dfc3196ccddf6f1d74b91b7af55e416)
>> This seems to have broken the use of /proc/bus/usb as a mountpoint. It
>> always appears empty now, whatever's supposed to be mounted there.
> Yes. Denis and Eric are tossing around competing patches but afaik nobody
> is happy with any of them. Guys, could we get this sorted soonish please?

Andrew, I become too relaxed after receiving
"Tested-by: Giacomo Catenazzi <>"

Eric, I believe that reverting an original behavior is better than your
new one as
- you introduce search into the depth by calling have_submounts(dentry)
during revalidation for all(!) /proc dentries
- your shadowing behavior will be broken if you'll mount something in
the depth of shadowed tree (this can be done as a DoS attempt)

As a last minute call, may be it will be better to pin network namespace
like a pid namespace during mount to avoid this crap at all?


 \ /
  Last update: 2007-12-07 12:13    [W:0.258 / U:0.768 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site