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Date:   Sun, 14 Apr 2019 17:39:50 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Amir Goldstein <amir73il@gmail.com>
Cc:     Jan Kara <jack@suse.cz>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        LSM List <linux-security-module@vger.kernel.org>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        James Morris <jmorris@namei.org>,
        Miklos Szeredi <miklos@szeredi.hu>,
        Matthew Bobrowski <mbobrowski@mbobrowski.org>,
        Kentaro Takeda <takedakn@nttdata.co.jp>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        John Johansen <john.johansen@canonical.com>
Subject: Re: fanotify and LSM path hooks
Message-ID: <20190414163950.GQ2217@ZenIV.linux.org.uk>
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On Sun, Apr 14, 2019 at 07:04:14PM +0300, Amir Goldstein wrote:

> Another problem is that they seem to be bypassed by several subsystems.
> cachefiles, ecryptfs, overlayfs and nfsd all call the vfs_rename() helper, but
> only cachefiles bothers to call the security_path_rename() hook.
> This is of course true for all other security_path_ hooks.
> I think that is something that requires fixing regardless of the fanotify pre
> modification hooks. I wonder if tomoyo and apparmor developers
> (LSM that implement security_path_ hooks) are aware of those missing
> hooks?

First of all, _what_ path?  You do realize that there is no such thing
as *the* pathname of dentry, right?  The same filesystem may be mounted
in any number of places, some of which might be visible in a given
namespace (including "none of them" - and you are not even guaranteed
that they are visible in any namespace at all).

It's not "bypassed", it's "inapplicable and deeply flawed in general".