From: Christian Brauner <christian.brauner@ubuntu.com>
To: linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>,
Johannes Weiner <hannes@cmpxchg.org>,
cgroups@vger.kernel.org
Subject: Re: [PATCH 1/3] cgroup: unify attach permission checking
Date: Thu, 19 Dec 2019 01:39:54 +0100 [thread overview]
Message-ID: <20191219003953.y26rclexqwijxmvz@wittgenstein> (raw)
In-Reply-To: <20191218173516.7875-2-christian.brauner@ubuntu.com>
On Wed, Dec 18, 2019 at 06:35:14PM +0100, Christian Brauner wrote:
> The core codepaths to check whether a process can be attached to a
> cgroup are the same for threads and thread-group leaders. Only a small
> piece of code verifying that source and destination cgroup are in the
> same domain differentiates the thread permission checking from
> thread-group leader permission checking.
> Since cgroup_migrate_vet_dst() only matters cgroup2 - it is a noop on
> cgroup1 - we can move it out of cgroup_attach_task().
> All checks can now be consolidated into a new helper
> cgroup_attach_permissions() callable from both cgroup_procs_write() and
> cgroup_threads_write().
>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Li Zefan <lizefan@huawei.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: cgroups@vger.kernel.org
> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
> ---
> kernel/cgroup/cgroup.c | 46 +++++++++++++++++++++++++++++-------------
> 1 file changed, 32 insertions(+), 14 deletions(-)
>
> diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
> index 735af8f15f95..5ee06c1f7456 100644
> --- a/kernel/cgroup/cgroup.c
> +++ b/kernel/cgroup/cgroup.c
> @@ -2719,11 +2719,7 @@ int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
> {
> DEFINE_CGROUP_MGCTX(mgctx);
> struct task_struct *task;
> - int ret;
> -
> - ret = cgroup_migrate_vet_dst(dst_cgrp);
> - if (ret)
> - return ret;
> + int ret = 0;
>
> /* look up all src csets */
> spin_lock_irq(&css_set_lock);
> @@ -4690,6 +4686,33 @@ static int cgroup_procs_write_permission(struct cgroup *src_cgrp,
> return 0;
> }
>
> +static inline bool cgroup_same_domain(const struct cgroup *src_cgrp,
> + const struct cgroup *dst_cgrp)
> +{
> + return src_cgrp->dom_cgrp == dst_cgrp->dom_cgrp;
> +}
> +
> +static int cgroup_attach_permissions(struct cgroup *src_cgrp,
> + struct cgroup *dst_cgrp,
> + struct super_block *sb, bool thread)
> +{
> + int ret;
This needs to be
ret = 0
> +
> + ret = cgroup_procs_write_permission(src_cgrp, dst_cgrp, sb);
> + if (ret)
> + return ret;
> +
> + ret = cgroup_migrate_vet_dst(dst_cgrp);
> + if (ret)
> + return ret;
> +
> + if (thread &&
> + !cgroup_same_domain(src_cgrp->dom_cgrp, dst_cgrp->dom_cgrp))
> + ret = -EOPNOTSUPP;
> +
> + return 0;
and this
return ret;
next prev parent reply other threads:[~2019-12-19 0:39 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 17:35 [PATCH 0/3] clone3 & cgroups: allow spawning processes into cgroups Christian Brauner
2019-12-18 17:35 ` [PATCH 1/3] cgroup: unify attach permission checking Christian Brauner
2019-12-18 23:46 ` Christian Brauner
2019-12-19 0:39 ` Christian Brauner [this message]
2019-12-18 17:35 ` [PATCH 2/3] clone3: allow spawning processes into cgroups Christian Brauner
2019-12-20 20:36 ` Oleg Nesterov
2019-12-18 17:35 ` [PATCH 3/3] selftests/cgroup: add tests for cloning " Christian Brauner
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