From: Andy Lutomirski <luto@amacapital.net>
To: Aditya Kali <adityakali@google.com>
Cc: Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>,
Serge Hallyn <serge.hallyn@ubuntu.com>,
cgroups@vger.kernel.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Linux Containers <containers@lists.linux-foundation.org>,
jnagal@google.com
Subject: Re: [PATCHv1 0/8] CGroup Namespaces
Date: Tue, 14 Oct 2014 15:42:55 -0700 [thread overview]
Message-ID: <CALCETrVnjrBt3odufhAirf45_REq-S9T=HpoEWqmFef2M6PucA@mail.gmail.com> (raw)
In-Reply-To: <1413235430-22944-1-git-send-email-adityakali@google.com>
On Mon, Oct 13, 2014 at 2:23 PM, Aditya Kali <adityakali@google.com> wrote:
> Second take at the Cgroup Namespace patch-set.
>
> Major changes form RFC (V0):
> 1. setns support for cgroupns
> 2. 'mount -t cgroup cgroup <mntpt>' from inside a cgroupns now
> mounts the cgroup hierarcy with cgroupns-root as the filesystem root.
> 3. writes to cgroup files outside of cgroupns-root are not allowed
> 4. visibility of /proc/<pid>/cgroup is further restricted by not showing
> anything if the <pid> is in a sibling cgroupns and its cgroup falls outside
> your cgroupns-root.
>
> More details in the writeup below.
>
> Background
> Cgroups and Namespaces are used together to create “virtual”
> containers that isolates the host environment from the processes
> running in container. But since cgroups themselves are not
> “virtualized”, the task is always able to see global cgroups view
> through cgroupfs mount and via /proc/self/cgroup file.
>
> $ cat /proc/self/cgroup
> 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/batchjobs/c_job_id1
>
> This exposure of cgroup names to the processes running inside a
> container results in some problems:
> (1) The container names are typically host-container-management-agent
> (systemd, docker/libcontainer, etc.) data and leaking its name (or
> leaking the hierarchy) reveals too much information about the host
> system.
> (2) It makes the container migration across machines (CRIU) more
> difficult as the container names need to be unique across the
> machines in the migration domain.
> (3) It makes it difficult to run container management tools (like
> docker/libcontainer, lmctfy, etc.) within virtual containers
> without adding dependency on some state/agent present outside the
> container.
>
> Note that the feature proposed here is completely different than the
> “ns cgroup” feature which existed in the linux kernel until recently.
> The ns cgroup also attempted to connect cgroups and namespaces by
> creating a new cgroup every time a new namespace was created. It did
> not solve any of the above mentioned problems and was later dropped
> from the kernel. Incidentally though, it used the same config option
> name CONFIG_CGROUP_NS as used in my prototype!
>
> Introducing CGroup Namespaces
> With unified cgroup hierarchy
> (Documentation/cgroups/unified-hierarchy.txt), the containers can now
> have a much more coherent cgroup view and its easy to associate a
> container with a single cgroup. This also allows us to virtualize the
> cgroup view for tasks inside the container.
>
> The new CGroup Namespace allows a process to “unshare” its cgroup
> hierarchy starting from the cgroup its currently in.
> For Ex:
> $ cat /proc/self/cgroup
> 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/batchjobs/c_job_id1
> $ ls -l /proc/self/ns/cgroup
> lrwxrwxrwx 1 root root 0 2014-07-15 10:37 /proc/self/ns/cgroup -> cgroup:[4026531835]
> $ ~/unshare -c # calls unshare(CLONE_NEWCGROUP) and exec’s /bin/bash
> [ns]$ ls -l /proc/self/ns/cgroup
> lrwxrwxrwx 1 root root 0 2014-07-15 10:35 /proc/self/ns/cgroup ->
> cgroup:[4026532183]
> # From within new cgroupns, process sees that its in the root cgroup
> [ns]$ cat /proc/self/cgroup
> 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/
>
> # From global cgroupns:
> $ cat /proc/<pid>/cgroup
> 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/batchjobs/c_job_id1
>
> # Unshare cgroupns along with userns and mountns
> # Following calls unshare(CLONE_NEWCGROUP|CLONE_NEWUSER|CLONE_NEWNS), then
> # sets up uid/gid map and exec’s /bin/bash
> $ ~/unshare -c -u -m
>
> # Originally, we were in /batchjobs/c_job_id1 cgroup. Mount our own cgroup
> # hierarchy.
> [ns]$ mount -t cgroup cgroup /tmp/cgroup
> [ns]$ ls -l /tmp/cgroup
> total 0
> -r--r--r-- 1 root root 0 2014-10-13 09:32 cgroup.controllers
> -r--r--r-- 1 root root 0 2014-10-13 09:32 cgroup.populated
> -rw-r--r-- 1 root root 0 2014-10-13 09:25 cgroup.procs
> -rw-r--r-- 1 root root 0 2014-10-13 09:32 cgroup.subtree_control
>
> The cgroupns-root (/batchjobs/c_job_id1 in above example) becomes the
> filesystem root for the namespace specific cgroupfs mount.
>
> The virtualization of /proc/self/cgroup file combined with restricting
> the view of cgroup hierarchy by namespace-private cgroupfs mount
> should provide a completely isolated cgroup view inside the container.
>
> In its current form, the cgroup namespaces patcheset provides following
> behavior:
>
> (1) The “root” cgroup for a cgroup namespace is the cgroup in which
> the process calling unshare is running.
> For ex. if a process in /batchjobs/c_job_id1 cgroup calls unshare,
> cgroup /batchjobs/c_job_id1 becomes the cgroupns-root.
> For the init_cgroup_ns, this is the real root (“/”) cgroup
> (identified in code as cgrp_dfl_root.cgrp).
>
> (2) The cgroupns-root cgroup does not change even if the namespace
> creator process later moves to a different cgroup.
> $ ~/unshare -c # unshare cgroupns in some cgroup
> [ns]$ cat /proc/self/cgroup
> 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/
> [ns]$ mkdir sub_cgrp_1
> [ns]$ echo 0 > sub_cgrp_1/cgroup.procs
> [ns]$ cat /proc/self/cgroup
> 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/sub_cgrp_1
>
> (3) Each process gets its CGROUPNS specific view of
> /proc/<pid>/cgroup.
> (a) Processes running inside the cgroup namespace will be able to see
> cgroup paths (in /proc/self/cgroup) only inside their root cgroup
> [ns]$ sleep 100000 & # From within unshared cgroupns
> [1] 7353
> [ns]$ echo 7353 > sub_cgrp_1/cgroup.procs
> [ns]$ cat /proc/7353/cgroup
> 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/sub_cgrp_1
>
> (b) From global cgroupns, the real cgroup path will be visible:
> $ cat /proc/7353/cgroup
> 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/batchjobs/c_job_id1/sub_cgrp_1
This is a little weird. Not sure it's a problem.
>
> (c) From a sibling cgroupns (cgroupns root-ed at a sibling cgroup), no cgroup
> path will be visible:
> # ns2's cgroupns-root is at '/batchjobs/c_job_id2'
> [ns2]$ cat /proc/7353/cgroup
> [ns2]$
> This is same as when cgroup hierarchy is not mounted at all.
> (In correct container setup though, it should not be possible to
> access PIDs in another container in the first place.)
>
> (4) Processes inside a cgroupns are not allowed to move out of the
> cgroupns-root. This is true even if a privileged process in global
> cgroupns tries to move the process out of its cgroupns-root.
>
> # From global cgroupns
> $ cat /proc/7353/cgroup
> 0:cpuset,cpu,cpuacct,memory,devices,freezer,hugetlb:/batchjobs/c_job_id1/sub_cgrp_1
> # cgroupns-root for 7353 is /batchjobs/c_job_id1
> $ echo 7353 > batchjobs/c_job_id2/cgroup.procs
> -bash: echo: write error: Operation not permitted
>
>
> (6) When some thread from a multi-threaded process unshares its
> cgroup-namespace, the new cgroupns gets applied to the entire
> process (all the threads). This should be OK since
> unified-hierarchy only allows process-level containerization. So
> all the threads in the process will have the same cgroup. And both
> - changing cgroups and unsharing namespaces - are protected under
> threadgroup_lock(task).
This seems odd to me. Does unsharing the cgroupns unshare for all
tasks in the process? If not, then I think that it shouldn't change
the cgroup either.
What did you end up doing to grant permission to unshare the cgroup ns?
--Andy
next prev parent reply other threads:[~2014-10-14 22:43 UTC|newest]
Thread overview: 157+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <adityakali-cgroupns>
2014-07-17 19:52 ` [PATCH 0/5] RFC: CGroup Namespaces Aditya Kali
2014-07-17 19:52 ` [PATCH 1/5] kernfs: Add API to get generate relative kernfs path Aditya Kali
2014-07-24 15:10 ` Serge Hallyn
2014-07-17 19:52 ` [PATCH 2/5] sched: new clone flag CLONE_NEWCGROUP for cgroup namespace Aditya Kali
2014-07-24 17:01 ` Serge Hallyn
2014-07-31 19:48 ` Aditya Kali
2014-08-04 23:12 ` Serge Hallyn
2014-07-17 19:52 ` [PATCH 3/5] cgroup: add function to get task's cgroup on default hierarchy Aditya Kali
2014-07-24 16:59 ` Serge Hallyn
2014-07-17 19:52 ` [PATCH 4/5] cgroup: export cgroup_get() and cgroup_put() Aditya Kali
2014-07-24 17:03 ` Serge Hallyn
2014-07-17 19:52 ` [PATCH 5/5] cgroup: introduce cgroup namespaces Aditya Kali
2014-07-17 19:57 ` Andy Lutomirski
2014-07-17 20:55 ` Aditya Kali
2014-07-18 16:51 ` Andy Lutomirski
2014-07-18 18:51 ` Aditya Kali
2014-07-18 18:57 ` Andy Lutomirski
2014-07-21 22:11 ` Aditya Kali
2014-07-21 22:16 ` Andy Lutomirski
2014-07-23 19:52 ` Aditya Kali
2014-07-18 16:00 ` [PATCH 0/5] RFC: CGroup Namespaces Serge Hallyn
2014-07-24 16:10 ` Serge Hallyn
2014-07-24 16:36 ` Serge Hallyn
2014-07-25 19:29 ` Aditya Kali
2014-07-25 20:27 ` Andy Lutomirski
2014-07-29 4:51 ` Serge E. Hallyn
2014-07-29 15:08 ` Andy Lutomirski
2014-07-29 16:06 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 0/8] " Aditya Kali
2014-10-13 21:23 ` [PATCHv1 1/8] kernfs: Add API to generate relative kernfs path Aditya Kali
2014-10-16 16:07 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 2/8] sched: new clone flag CLONE_NEWCGROUP for cgroup namespace Aditya Kali
2014-10-16 16:08 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 3/8] cgroup: add function to get task's cgroup on default hierarchy Aditya Kali
2014-10-16 16:13 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 4/8] cgroup: export cgroup_get() and cgroup_put() Aditya Kali
2014-10-16 16:14 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 5/8] cgroup: introduce cgroup namespaces Aditya Kali
2014-10-16 16:37 ` Serge E. Hallyn
2014-10-24 1:03 ` Aditya Kali
2014-10-25 3:16 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 6/8] cgroup: restrict cgroup operations within task's cgroupns Aditya Kali
2014-10-17 9:28 ` Serge E. Hallyn
2014-10-22 19:06 ` Aditya Kali
2014-10-19 4:57 ` Eric W. Biederman
2014-10-13 21:23 ` [PATCHv1 7/8] cgroup: cgroup namespace setns support Aditya Kali
2014-10-16 21:12 ` Serge E. Hallyn
2014-10-16 21:17 ` Andy Lutomirski
2014-10-16 21:22 ` Aditya Kali
2014-10-16 21:47 ` Serge E. Hallyn
2014-10-19 5:23 ` Eric W. Biederman
2014-10-19 18:26 ` Andy Lutomirski
2014-10-20 4:55 ` Eric W.Biederman
2014-10-21 0:20 ` Andy Lutomirski
2014-10-21 4:49 ` Eric W. Biederman
2014-10-21 5:03 ` Andy Lutomirski
2014-10-21 5:42 ` Eric W. Biederman
2014-10-21 5:49 ` Andy Lutomirski
2014-10-21 18:49 ` Aditya Kali
2014-10-21 19:02 ` Andy Lutomirski
2014-10-21 22:33 ` Aditya Kali
2014-10-21 22:42 ` Andy Lutomirski
2014-10-22 0:46 ` Aditya Kali
2014-10-22 0:58 ` Andy Lutomirski
2014-10-22 18:37 ` Aditya Kali
2014-10-22 18:50 ` Andy Lutomirski
2014-10-22 19:42 ` Tejun Heo
2014-10-17 9:52 ` Serge E. Hallyn
2014-10-13 21:23 ` [PATCHv1 8/8] cgroup: mount cgroupns-root when inside non-init cgroupns Aditya Kali
2014-10-17 12:19 ` Serge E. Hallyn
2014-10-14 22:42 ` Andy Lutomirski [this message]
2014-10-14 23:33 ` [PATCHv1 0/8] CGroup Namespaces Aditya Kali
2014-10-19 4:54 ` Eric W. Biederman
2015-07-22 18:10 ` Vincent Batts
2014-10-31 19:18 ` [PATCHv2 0/7] " Aditya Kali
2014-10-31 19:18 ` [PATCHv2 1/7] kernfs: Add API to generate relative kernfs path Aditya Kali
2014-10-31 19:18 ` [PATCHv2 2/7] sched: new clone flag CLONE_NEWCGROUP for cgroup namespace Aditya Kali
2014-10-31 19:18 ` [PATCHv2 3/7] cgroup: add function to get task's cgroup on default hierarchy Aditya Kali
2014-10-31 19:18 ` [PATCHv2 4/7] cgroup: export cgroup_get() and cgroup_put() Aditya Kali
2014-10-31 19:18 ` [PATCHv2 5/7] cgroup: introduce cgroup namespaces Aditya Kali
2014-11-01 0:02 ` Andy Lutomirski
2014-11-01 0:58 ` Eric W. Biederman
2014-11-03 23:42 ` Aditya Kali
2014-11-03 23:40 ` Aditya Kali
2014-11-04 1:56 ` Aditya Kali
2014-10-31 19:19 ` [PATCHv2 6/7] cgroup: cgroup namespace setns support Aditya Kali
2014-10-31 19:19 ` [PATCHv2 7/7] cgroup: mount cgroupns-root when inside non-init cgroupns Aditya Kali
2014-11-01 0:07 ` Andy Lutomirski
2014-11-01 2:59 ` Eric W. Biederman
2014-11-01 3:29 ` Andy Lutomirski
2014-11-03 23:12 ` Aditya Kali
2014-11-03 23:15 ` Andy Lutomirski
2014-11-03 23:23 ` Aditya Kali
2014-11-03 23:48 ` Andy Lutomirski
2014-11-04 0:12 ` Aditya Kali
2014-11-04 0:17 ` Andy Lutomirski
2014-11-04 0:49 ` Aditya Kali
2014-11-04 13:57 ` Tejun Heo
2014-11-06 17:28 ` Aditya Kali
2014-11-01 1:09 ` Eric W. Biederman
2014-11-03 22:46 ` Aditya Kali
[not found] ` <CAGr1F2Hd_PS_AscBGMXdZC9qkHGRUp-MeQvJksDOQkRBB3RGoA@mail.gmail.com>
2014-11-03 22:56 ` Andy Lutomirski
2014-11-04 13:46 ` Tejun Heo
2014-11-04 15:00 ` Andy Lutomirski
2014-11-04 15:50 ` Serge E. Hallyn
2014-11-12 17:48 ` Aditya Kali
2014-11-04 1:59 ` Aditya Kali
2014-11-04 13:10 ` [PATCHv2 0/7] CGroup Namespaces Vivek Goyal
2014-11-06 17:33 ` Aditya Kali
2014-11-26 22:58 ` Richard Weinberger
2014-12-02 19:14 ` Aditya Kali
2014-12-05 1:55 ` [PATCHv3 0/8] " Aditya Kali
2014-12-05 1:55 ` [PATCHv3 1/8] kernfs: Add API to generate relative kernfs path Aditya Kali
2014-12-05 1:55 ` [PATCHv3 2/8] sched: new clone flag CLONE_NEWCGROUP for cgroup namespace Aditya Kali
2014-12-05 1:55 ` [PATCHv3 3/8] cgroup: add function to get task's cgroup on default hierarchy Aditya Kali
2014-12-05 1:55 ` [PATCHv3 4/8] cgroup: export cgroup_get() and cgroup_put() Aditya Kali
2014-12-05 1:55 ` [PATCHv3 5/8] cgroup: introduce cgroup namespaces Aditya Kali
2014-12-12 8:54 ` Zefan Li
2014-12-05 1:55 ` [PATCHv3 6/8] cgroup: cgroup namespace setns support Aditya Kali
2014-12-05 1:55 ` [PATCHv3 7/8] cgroup: mount cgroupns-root when inside non-init cgroupns Aditya Kali
2014-12-12 8:55 ` Zefan Li
2014-12-05 1:55 ` [PATCHv3 8/8] cgroup: Add documentation for cgroup namespaces Aditya Kali
2014-12-12 8:54 ` Zefan Li
2015-01-05 22:54 ` Aditya Kali
2014-12-14 23:05 ` Richard Weinberger
2015-01-05 22:48 ` Aditya Kali
2015-01-05 22:52 ` Richard Weinberger
2015-01-05 23:53 ` Eric W. Biederman
2015-01-06 0:07 ` Richard Weinberger
2015-01-06 0:10 ` Aditya Kali
2015-01-06 0:17 ` Richard Weinberger
2015-01-06 23:20 ` Aditya Kali
2015-01-06 23:39 ` Richard Weinberger
2015-01-07 9:28 ` Richard Weinberger
2015-01-07 14:45 ` Eric W. Biederman
2015-01-07 19:30 ` Serge E. Hallyn
2015-01-07 22:14 ` Eric W. Biederman
2015-01-07 22:45 ` Tejun Heo
2015-01-07 23:02 ` Eric W. Biederman
2015-01-07 23:06 ` Tejun Heo
2015-01-07 23:09 ` Eric W. Biederman
2015-01-07 23:16 ` Tejun Heo
2015-01-07 23:27 ` Eric W. Biederman
2015-01-07 23:35 ` Tejun Heo
2015-02-11 3:46 ` Serge E. Hallyn
2015-02-11 4:09 ` Tejun Heo
2015-02-11 4:29 ` Serge E. Hallyn
2015-02-11 5:02 ` Eric W. Biederman
2015-02-11 5:17 ` Tejun Heo
2015-02-11 6:29 ` Eric W. Biederman
2015-02-11 14:36 ` Tejun Heo
2015-02-11 16:00 ` Serge E. Hallyn
2015-02-11 16:03 ` Tejun Heo
2015-02-11 16:18 ` Serge E. Hallyn
2015-02-11 5:10 ` Tejun Heo
2015-01-07 18:57 ` Aditya Kali
2014-12-05 3:20 ` [PATCHv3 0/8] CGroup Namespaces Aditya Kali
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