From: Al Viro <viro@ZenIV.linux.org.uk>
To: tux2002@front.ru
Cc: linux-kernel@vger.kernel.org
Subject: Re: Re: [PATCH] subsystem: pr??oc filesystem
Date: Sun, 16 Dec 2012 14:28:10 +0000 [thread overview]
Message-ID: <20121216142810.GB4939@ZenIV.linux.org.uk> (raw)
In-Reply-To: <5dca9c1a0bb851ebaa08ffb05941f90454ea3d6a@mail.qip.ru>
On Sun, Dec 16, 2012 at 04:02:03PM +0400, tux2002@front.ru wrote:
> Not, this permissions saved for all users for later, check please.
... and that's why it's bogus. umask of whoever had done lookup for
/proc/<something> affects everybody else. For as long as the thing stays
in dcache. At which point it's up for grabs (in that sense) again.
Do (umask 777; ls -l /proc) with your kernel and watch the results.
Note that you don't need to be root to cause that - anyone can do it.
Realize that dentries and inodes in /proc/<pid>/* are created on demand
whenever somebody does a lookup. So running ps(1) suddenly makes you
a creator of a bunch of those. Unless somebody else had done ps(1) (or
ls -l /proc, or...) first. Basing any security decisions on _that_ is
insane.
prev parent reply other threads:[~2012-12-16 14:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-13 13:15 [PATCH] subsystem: proc filesystem tux2002
2012-12-13 16:22 ` Al Viro
2012-12-16 12:02 ` Re: [PATCH] subsystem: proc filesystem tux2002
2012-12-16 14:28 ` Al Viro [this message]
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