Re: [patch 06/15] sysfs: dont call notify_change

From: Miklos Szeredi <miklos@szeredi.hu>
To: gregkh@suse.de
Cc: miklos@szeredi.hu, akpm@linux-foundation.org, hch@infradead.org,
	viro@ZenIV.linux.org.uk, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [patch 06/15] sysfs: dont call notify_change
Date: Tue, 06 May 2008 08:28:39 +0200	[thread overview]
Message-ID: <E1JtGfH-0008Bv-MI@pomaz-ex.szeredi.hu> (raw)
In-Reply-To: <20080506041555.GA4655@suse.de> (message from Greg KH on Mon, 5 May 2008 21:15:55 -0700)

> > sysfs_chmod_file() calls notify_change() to change the permission bits
> > on a sysfs file.  Replace with explicit call to sysfs_setattr() and
> > fsnotify_change().
> > 
> > This is equivalent, except that security_inode_setattr() is not
> > called.  This function is called by drivers, so the security checks do
> > not make any sense.
> 
> Are you sure?  As a user, you can chmod the sysfs file and it will
> stick,

Right, but that's not sysfs_chmod_file() but sys_chmod(), which calls
notify_change(), which calls security_inode_setattr().

sysfs_chmod_file() is just called by a couple of drivers to change the
file mode during operation, it's never called by user action directly.

Miklos