From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932678Ab1CYX4E (ORCPT ); Fri, 25 Mar 2011 19:56:04 -0400 Received: from kroah.org ([198.145.64.141]:41995 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932633Ab1CYXxN (ORCPT ); Fri, 25 Mar 2011 19:53:13 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Fri Mar 25 16:48:44 2011 Message-Id: <20110325234844.575654158@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Fri, 25 Mar 2011 16:47:46 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Josef Bacik , Al Viro , Chuck Ebbert Subject: [53/55] fs: call security_d_instantiate in d_obtain_alias V2 In-Reply-To: <20110325234853.GA21145@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.37-stable review patch. If anyone has any objections, please let us know. ------------------ From: Josef Bacik commit 24ff6663ccfdaf088dfa7acae489cb11ed4f43c4 upstream. While trying to track down some NFS problems with BTRFS, I kept noticing I was getting -EACCESS for no apparent reason. Eric Paris and printk() helped me figure out that it was SELinux that was giving me grief, with the following denial type=AVC msg=audit(1290013638.413:95): avc: denied { 0x800000 } for pid=1772 comm="nfsd" name="" dev=sda1 ino=256 scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:object_r:unlabeled_t:s0 tclass=file Turns out this is because in d_obtain_alias if we can't find an alias we create one and do all the normal instantiation stuff, but we don't do the security_d_instantiate. Usually we are protected from getting a hashed dentry that hasn't yet run security_d_instantiate() by the parent's i_mutex, but obviously this isn't an option there, so in order to deal with the case that a second thread comes in and finds our new dentry before we get to run security_d_instantiate(), we go ahead and call it if we find a dentry already. Eric assures me that this is ok as the code checks to see if the dentry has been initialized already so calling security_d_instantiate() against the same dentry multiple times is ok. With this patch I'm no longer getting errant -EACCESS values. Signed-off-by: Josef Bacik Signed-off-by: Al Viro Cc: Chuck Ebbert Signed-off-by: Greg Kroah-Hartman --- fs/dcache.c | 3 +++ 1 file changed, 3 insertions(+) --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1201,9 +1201,12 @@ struct dentry *d_obtain_alias(struct ino spin_unlock(&tmp->d_lock); spin_unlock(&dcache_lock); + security_d_instantiate(tmp, inode); return tmp; out_iput: + if (res && !IS_ERR(res)) + security_d_instantiate(res, inode); iput(inode); return res; }