Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755565AbYHYQou (ORCPT ); Mon, 25 Aug 2008 12:44:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753833AbYHYQom (ORCPT ); Mon, 25 Aug 2008 12:44:42 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:39179 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753940AbYHYQom (ORCPT ); Mon, 25 Aug 2008 12:44:42 -0400 Date: Mon, 25 Aug 2008 11:43:04 -0500 From: "Serge E. Hallyn" To: Li Zefan Cc: Andrew Morton , Paul Menage , LKML , Linux Containers Subject: Re: [PATCH] devcgroup: fix race against rmdir() Message-ID: <20080825164304.GA13583@us.ibm.com> References: <48B2174E.9060608@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48B2174E.9060608@cn.fujitsu.com> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2257 Lines: 79 Quoting Li Zefan (lizf@cn.fujitsu.com): > During the use of a dev_cgroup, we should guarantee the corresponding > cgroup won't be deleted (i.e. via rmdir). This can be done through > css_get(&dev_cgroup->css), but here we can just get and use the > dev_cgroup under rcu_read_lock. > > And also remove checking NULL dev_cgroup, it won't be NULL since a task > always belongs to a cgroup. > > Signed-off-by: Li Zefan Looks good. Thanks, Li. Acked-by: Serge Hallyn > --- > security/device_cgroup.c | 18 +++++++++--------- > 1 files changed, 9 insertions(+), 9 deletions(-) > > diff --git a/security/device_cgroup.c b/security/device_cgroup.c > index 7bd296c..46f2397 100644 > --- a/security/device_cgroup.c > +++ b/security/device_cgroup.c > @@ -508,12 +508,11 @@ int devcgroup_inode_permission(struct inode *inode, int mask) > return 0; > if (!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode)) > return 0; > - dev_cgroup = css_to_devcgroup(task_subsys_state(current, > - devices_subsys_id)); > - if (!dev_cgroup) > - return 0; > > rcu_read_lock(); > + > + dev_cgroup = task_devcgroup(current); > + > list_for_each_entry_rcu(wh, &dev_cgroup->whitelist, list) { > if (wh->type & DEV_ALL) > goto acc_check; > @@ -533,6 +532,7 @@ acc_check: > rcu_read_unlock(); > return 0; > } > + > rcu_read_unlock(); > > return -EPERM; > @@ -543,12 +543,10 @@ int devcgroup_inode_mknod(int mode, dev_t dev) > struct dev_cgroup *dev_cgroup; > struct dev_whitelist_item *wh; > > - dev_cgroup = css_to_devcgroup(task_subsys_state(current, > - devices_subsys_id)); > - if (!dev_cgroup) > - return 0; > - > rcu_read_lock(); > + > + dev_cgroup = task_devcgroup(current); > + > list_for_each_entry(wh, &dev_cgroup->whitelist, list) { > if (wh->type & DEV_ALL) > goto acc_check; > @@ -566,6 +564,8 @@ acc_check: > rcu_read_unlock(); > return 0; > } > + > rcu_read_unlock(); > + > return -EPERM; > } > -- > 1.5.4.rc3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/