linux-kernel - [PATCH v2 -next] cgroup: update some statememt about delegation

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]

Message-ID: <20240815131408.3151804-1-chenridong@huawei.com>
Date: Thu, 15 Aug 2024 13:14:08 +0000
From: Chen Ridong <chenridong@...wei.com>
To: <tj@...nel.org>, <lizefan.x@...edance.com>, <hannes@...xchg.org>,
	<longman@...hat.com>, <mkoutny@...e.com>
CC: <cgroups@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 -next] cgroup: update some statememt about delegation

The comment in cgroup_file_write is missing some interfaces, such as
'cgroup.threads'. All delegatable files are listed in
'/sys/kernel/cgroup/delegate', so update the comment in cgroup_file_write.
Besides, add a statement that files outside the namespace shouldn't be
visible from inside the delegated namespace.

Signed-off-by: Chen Ridong <chenridong@...wei.com>
---
 Documentation/admin-guide/cgroup-v2.rst | 10 ++++++----
 kernel/cgroup/cgroup.c                  |  2 +-
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index f2d1ec7d6aba..3618168de371 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -533,10 +533,12 @@ cgroup namespace on namespace creation.
 Because the resource control interface files in a given directory
 control the distribution of the parent's resources, the delegatee
 shouldn't be allowed to write to them.  For the first method, this is
-achieved by not granting access to these files.  For the second, the
-kernel rejects writes to all files other than "cgroup.procs" and
-"cgroup.subtree_control" on a namespace root from inside the
-namespace.
+achieved by not granting access to these files.  For the second, files
+outside the namespace should be hidden from the delegatee by the means
+of at least mount namespacing, and the kernel rejects writes to all files
+on a namespace root from inside the cgroup namespace, except for those
+files listed in "/sys/kernel/cgroup/delegate" (including "cgroup.procs",
+"cgroup.threads", "cgroup.subtree_control", etc.).
 
 The end results are equivalent for both delegation types.  Once
 delegated, the user can build sub-hierarchy under the directory,
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index a3fa645f8433..16b9749e131e 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -4131,7 +4131,7 @@ static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf,
 	 * If namespaces are delegation boundaries, disallow writes to
 	 * files in an non-init namespace root from inside the namespace
 	 * except for the files explicitly marked delegatable -
-	 * cgroup.procs and cgroup.subtree_control.
+	 * eg. cgroup.procs, cgroup.threads and cgroup.subtree_control.
 	 */
 	if ((cgrp->root->flags & CGRP_ROOT_NS_DELEGATE) &&
 	    !(cft->flags & CFTYPE_NS_DELEGATABLE) &&
-- 
2.34.1