From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: [PATCH v2 cgroup/for-3.11] cgroup: disallow rename(2) if sane_behavior Date: Fri, 14 Jun 2013 11:18:22 -0700 Message-ID: <20130614181822.GC6593@mtj.dyndns.org> References: <20130614034717.GA31533@htj.dyndns.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=OKWMYtPhY4KquWEfy305BtzAb+4/EpDi8uuj3y0IRQI=; b=k+XQlzC+rAxFp91dq1za9nVTrvQhg4I63aUKQ9NGw/b1AqTjfTC2QzDveAJ9X6ouRa Z1nu8rajnEysytupY+nPijHAKf9KbWQnuUkRw0iQmpImVmKsmm+6lC5EFMxsRn3Be9rV PrAlhTOCOJKmqQjX1PNGJH3gePvLGAAP8UCDeTNmJtWyEjIIkm35zDvgn3bYmkkhNYQG guTD4qm+7U2MwguSUsbUqNfCNqH5D0KsijZ8axW5i0FELb8jAGRK3Q8Gj5qjp7kUfTBT MWivM5U//8g/KEVC+p8ccq4suQjTuhDRJsxlKM0YrCI7M7ImXv1LjHcHziNU/Mcij1/G ObAg== Content-Disposition: inline In-Reply-To: <20130614034717.GA31533-Gd/HAXX7CRxy/B6EtB590w@public.gmane.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Li Zefan Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Kay Sievers , Lennart Poettering cgroup's rename(2) isn't a proper migration implementation - it can't move the cgroup to a different parent in the hierarchy. All it can do is swapping the name string for that cgroup. This isn't useful and can mislead users to think that cgroup supports proper cgroup-level migration. Disallow rename(2) if sane_behavior. v2: Fail with -EPERM instead of -EINVAL so that it matches the vfs return value when ->rename is not implemented as suggested by Li. Signed-off-by: Tejun Heo Cc: Li Zefan --- include/linux/cgroup.h | 2 ++ kernel/cgroup.c | 7 +++++++ 2 files changed, 9 insertions(+) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 1760476..f975227 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -270,6 +270,8 @@ enum { * - "release_agent" and "notify_on_release" are removed. * Replacement notification mechanism will be implemented. * + * - rename(2) is disallowed. + * * - memcg: use_hierarchy is on by default and the cgroup file for * the flag is not created. */ diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 2e9da7b..c2c64005 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2508,6 +2508,13 @@ static int cgroup_rename(struct inode *old_dir, struct dentry *old_dentry, cgrp = __d_cgrp(old_dentry); + /* + * This isn't a proper migration and its usefulness is very + * limited. Disallow if sane_behavior. + */ + if (cgroup_sane_behavior(cgrp)) + return -EPERM; + name = cgroup_alloc_name(new_dentry); if (!name) return -ENOMEM;