From: Al Viro <viro@ZenIV.linux.org.uk>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
Oleg Nesterov <oleg@redhat.com>,
Dmitry Kasatkin <d.kasatkin@samsung.com>,
linux-security-module <linux-security-module@vger.kernel.org>,
John Johansen <john.johansen@canonical.com>,
Mimi Zohar <zohar@linux.vnet.ibm.com>,
James Morris <jmorris@namei.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
kernel-team <kernel-team@lists.ubuntu.com>
Subject: Re: Kernel panic at Ubuntu: IMA + Apparmor
Date: Fri, 25 Apr 2014 22:21:28 +0100 [thread overview]
Message-ID: <20140425212128.GB18016@ZenIV.linux.org.uk> (raw)
In-Reply-To: <874n1h16le.fsf@x220.int.ebiederm.org>
On Fri, Apr 25, 2014 at 01:45:17PM -0700, Eric W. Biederman wrote:
> IMA-appraisal is fundamentally broken because I can take a mandatory
> file lock and prevent IMA-apprasial.
>
> Using kernel_read is what allows this.
>
> > Isn't it a clear motivating case???
>
> kernel_read is not appropriate for IMA use. The rest of this is just
> the messenger.
>
> IMA needs to use a cousin of kernel_read that operates at a lower level
> than vfs_read. A function that all of the permission checks and the
> fsnotify work.
It's worse than that, actually ;-/ IMA hooks in __fput() have interesting
interplay with revoke-related stuff as well. Another very messy thing in
the same area is that it actually does ->read() from under ->i_mutex, leading
to all kinds of interesting locking issues...
I doubt that your "let's open-code vfs_read() guts" would be a good idea;
if nothing else, it might make more sense to make rw_verify_area() skip
the mandlock and security theatre when called in such situation.
What a mess... ;-/
next prev parent reply other threads:[~2014-04-25 21:21 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-25 13:00 Kernel panic at Ubuntu: IMA + Apparmor Dmitry Kasatkin
2014-04-25 14:48 ` Dmitry Kasatkin
2014-04-25 18:23 ` Oleg Nesterov
2014-04-25 19:04 ` Eric W. Biederman
2014-04-25 19:25 ` Oleg Nesterov
2014-04-25 19:40 ` Eric W. Biederman
2014-04-25 20:01 ` Oleg Nesterov
2014-04-25 20:20 ` Dmitry Kasatkin
2014-04-25 20:45 ` Eric W. Biederman
2014-04-25 20:52 ` Dmitry Kasatkin
2014-04-25 21:27 ` Eric W. Biederman
2014-04-25 21:46 ` Dmitry Kasatkin
2014-04-25 21:56 ` Dmitry Kasatkin
2014-04-25 22:38 ` Eric W. Biederman
2014-04-26 8:58 ` Dmitry Kasatkin
2014-04-26 13:56 ` Al Viro
2014-04-26 16:54 ` Dmitry Kasatkin
2014-04-26 17:42 ` Al Viro
2014-04-26 19:03 ` Dmitry Kasatkin
2014-04-25 22:11 ` Eric W. Biederman
2014-04-26 8:49 ` Dmitry Kasatkin
2014-04-25 21:21 ` Al Viro [this message]
2014-04-25 21:43 ` Eric W. Biederman
2014-04-25 21:55 ` Al Viro
2014-04-25 22:25 ` Eric W. Biederman
2014-04-29 13:00 ` Mimi Zohar
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