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    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?


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      Last update: 2007-12-07 12:13    [W:0.022 / U:16.884 seconds]
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