From: Christian Brauner <christian.brauner@ubuntu.com>
To: linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
Tejun Heo <tj@kernel.org>
Cc: "Oleg Nesterov" <oleg@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Christian Brauner" <christian.brauner@ubuntu.com>,
"Li Zefan" <lizefan@huawei.com>,
"Johannes Weiner" <hannes@cmpxchg.org>,
cgroups@vger.kernel.org, "Michal Koutný" <mkoutny@suse.com>
Subject: [PATCH v6 1/6] cgroup: unify attach permission checking
Date: Wed, 5 Feb 2020 14:26:18 +0100 [thread overview]
Message-ID: <20200205132623.670015-2-christian.brauner@ubuntu.com> (raw)
In-Reply-To: <20200205132623.670015-1-christian.brauner@ubuntu.com>
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
Acked-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v1 */
Link: https://lore.kernel.org/r/20191218173516.7875-2-christian.brauner@ubuntu.com
/* v2 */
Link: https://lore.kernel.org/r/20191223061504.28716-2-christian.brauner@ubuntu.com
- Christian Brauner <christian.brauner@ubuntu.com>:
- Fix return value of cgroup_attach_permissions. It used to return 0
when it should've returned -EOPNOTSUPP.
- Fix call to cgroup_attach_permissions() in cgroup_procs_write(). It
accidently specified that a thread was moved causing an additional
check for domain-group equality to be executed that is not needed.
/* v3 */
Link: https://lore.kernel.org/r/20200117002143.15559-2-christian.brauner@ubuntu.com
unchanged
/* v4 */
Link: https://lore.kernel.org/r/20200117181219.14542-2-christian.brauner@ubuntu.com
unchanged
/* v5 */
Link: https://lore.kernel.org/r/20200121154844.411-2-christian.brauner@ubuntu.com
unchanged
/* v6 */
- Michal Koutný <mkoutny@suse.com>:
- Invert logic to use threadgroup argument to match other codepaths.
---
kernel/cgroup/cgroup.c | 39 +++++++++++++++++++++++++--------------
1 file changed, 25 insertions(+), 14 deletions(-)
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 735af8f15f95..5f84177e2065 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 +4686,26 @@ static int cgroup_procs_write_permission(struct cgroup *src_cgrp,
return 0;
}
+static int cgroup_attach_permissions(struct cgroup *src_cgrp,
+ struct cgroup *dst_cgrp,
+ struct super_block *sb, bool threadgroup)
+{
+ int 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 (!threadgroup && (src_cgrp->dom_cgrp != dst_cgrp->dom_cgrp))
+ ret = -EOPNOTSUPP;
+
+ return ret;
+}
+
static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
@@ -4712,8 +4728,8 @@ static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
src_cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
spin_unlock_irq(&css_set_lock);
- ret = cgroup_procs_write_permission(src_cgrp, dst_cgrp,
- of->file->f_path.dentry->d_sb);
+ ret = cgroup_attach_permissions(src_cgrp, dst_cgrp,
+ of->file->f_path.dentry->d_sb, true);
if (ret)
goto out_finish;
@@ -4757,16 +4773,11 @@ static ssize_t cgroup_threads_write(struct kernfs_open_file *of,
spin_unlock_irq(&css_set_lock);
/* thread migrations follow the cgroup.procs delegation rule */
- ret = cgroup_procs_write_permission(src_cgrp, dst_cgrp,
- of->file->f_path.dentry->d_sb);
+ ret = cgroup_attach_permissions(src_cgrp, dst_cgrp,
+ of->file->f_path.dentry->d_sb, false);
if (ret)
goto out_finish;
- /* and must be contained in the same domain */
- ret = -EOPNOTSUPP;
- if (src_cgrp->dom_cgrp != dst_cgrp->dom_cgrp)
- goto out_finish;
-
ret = cgroup_attach_task(dst_cgrp, task, false);
out_finish:
--
2.25.0
next prev parent reply other threads:[~2020-02-05 13:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-05 13:26 [PATCH v6 0/6] clone3 & cgroups: allow spawning processes into cgroups Christian Brauner
2020-02-05 13:26 ` Christian Brauner [this message]
2020-02-05 13:26 ` [PATCH v6 2/6] cgroup: add cgroup_get_from_file() helper Christian Brauner
2020-02-05 13:26 ` [PATCH v6 3/6] cgroup: refactor fork helpers Christian Brauner
2020-02-05 13:26 ` [PATCH v6 4/6] cgroup: add cgroup_may_write() helper Christian Brauner
2020-02-05 13:26 ` [PATCH v6 5/6] clone3: allow spawning processes into cgroups Christian Brauner
2020-02-05 13:26 ` [PATCH v6 6/6] selftests/cgroup: add tests for cloning " Christian Brauner
2020-02-12 23:01 ` [PATCH v6 0/6] clone3 & cgroups: allow spawning processes " Tejun Heo
2020-02-13 12:52 ` Christian Brauner
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