linux-kernel - [PATCH] cgroup: disallow disabled controllers on the default hierarchy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 5 Jun 2014 17:16:30 +0800
From:	Li Zefan <lizefan@...wei.com>
To:	Tejun Heo <tj@...nel.org>
CC:	LKML <linux-kernel@...r.kernel.org>,
	Cgroups <cgroups@...r.kernel.org>, Michal Hocko <mhocko@...e.cz>,
	Johannes Weiner <hannes@...xchg.org>
Subject: [PATCH] cgroup: disallow disabled controllers on the default hierarchy

After booting with cgroup_disable=memory, I still saw memcg files
in the default hierarchy, and I can write to them, though it won't
take effect.

  # dmesg
  ...
  Disabling memory control group subsystem
  ...
  # mount -t cgroup -o __DEVEL__sane_behavior xxx /cgroup
  # ls /cgroup
  ...
  memory.failcnt                   memory.move_charge_at_immigrate
  memory.force_empty               memory.numa_stat
  memory.limit_in_bytes            memory.oom_control
  ...
  # cat /cgroup/memory.usage_in_bytes
  0

Signed-off-by: Li Zefan <lizefan@...wei.com>
---
 kernel/cgroup.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index d5032d2..57b647a 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3070,6 +3070,9 @@ int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
 {
 	int ret;
 
+	if (ss->disabled)
+		return 0;
+
 	if (!cfts || cfts[0].name[0] == '\0')
 		return 0;
 
@@ -4679,8 +4682,6 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early)
 
 	BUG_ON(online_css(css));
 
-	cgrp_dfl_root.subsys_mask |= 1 << ss->id;
-
 	mutex_unlock(&cgroup_mutex);
 }
 
@@ -4760,10 +4761,13 @@ int __init cgroup_init(void)
 
 		/*
 		 * cftype registration needs kmalloc and can't be done
-		 * during early_init.  Register base cftypes separately.
+		 * during early_init, and the disable flag is set after
+		 * early_init.  Register base cftypes separately.
 		 */
-		if (ss->base_cftypes)
+		if (!ss->disabled) {
+			cgrp_dfl_root.subsys_mask |= 1 << ss->id;
 			WARN_ON(cgroup_add_cftypes(ss, ss->base_cftypes));
+		}
 	}
 
 	cgroup_kobj = kobject_create_and_add("cgroup", fs_kobj);
-- 
1.8.0.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/