From 6e23854a2c0c6acedb76eaeb306090aaacf58245 Mon Sep 17 00:00:00 2001
From: Joe Lawrence <joe.lawrence@redhat.com>
Date: Thu, 24 Feb 2022 13:03:17 -0500
Subject: [KPATCH CVE-2022-0492] cgroup-v1: kpatch fixes for CVE-2022-0492
Kernels:
4.18.0-348.el8
4.18.0-348.2.1.el8_5
4.18.0-348.7.1.el8_5
4.18.0-348.12.2.el8_5
Changes since last build:
arches: x86_64 ppc64le
cgroup-v1.o: changed function: cgroup1_parse_param
cgroup-v1.o: changed function: cgroup_release_agent_write
---------------------------
Kpatch-MR: https://gitlab.com/redhat/prdsc/rhel/src/kpatch/rhel-8/-/merge_requests/26
Approved-by: Yannick Cote (@ycote1)
Kernels:
4.18.0-348.el8
4.18.0-348.2.1.el8_5
4.18.0-348.7.1.el8_5
4.18.0-348.12.2.el8_5
Modifications: none
commit 07650ec60ef7ae3d33cde8faed38770c838ff4b1
Author: Waiman Long <longman@redhat.com>
Date: Tue Feb 8 19:21:47 2022 -0500
cgroup-v1: Require capabilities to set release_agent
Bugzilla: https://bugzilla.redhat.com/2052166
CVE: CVE-2022-0492
Y-Commit: 55f79b1a4b02276a6edda7cb7ef5ec0c585141a1
O-Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2052167
O-CVE: CVE-2022-0492
commit 24f6008564183aa120d07c03d9289519c2fe02af
Author: Eric W. Biederman <ebiederm@xmission.com>
Date: Thu, 20 Jan 2022 11:04:01 -0600
cgroup-v1: Require capabilities to set release_agent
The cgroup release_agent is called with call_usermodehelper. The function
call_usermodehelper starts the release_agent with a full set fo capabilities.
Therefore require capabilities when setting the release_agaent.
Reported-by: Tabitha Sable <tabitha.c.sable@gmail.com>
Tested-by: Tabitha Sable <tabitha.c.sable@gmail.com>
Fixes: 81a6a5cdd2c5 ("Task Control Groups: automatic userspace notification of idle cgroups")
Cc: stable@vger.kernel.org # v2.6.24+
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Bruno Meneguele <bmeneg@redhat.com>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
kernel/cgroup/cgroup-v1.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 852f1349f9d9..fdf337ccda6b 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -544,6 +544,14 @@ static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
+ /*
+ * Release agent gets called with all capabilities,
+ * require capabilities to set release agent.
+ */
+ if ((of->file->f_cred->user_ns != &init_user_ns) ||
+ !capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
cgrp = cgroup_kn_lock_live(of->kn, false);
if (!cgrp)
return -ENODEV;
@@ -951,6 +959,12 @@ int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param)
/* Specifying two release agents is forbidden */
if (ctx->release_agent)
return invalfc(fc, "release_agent respecified");
+ /*
+ * Release agent gets called with all capabilities,
+ * require capabilities to set release agent.
+ */
+ if ((fc->user_ns != &init_user_ns) || !capable(CAP_SYS_ADMIN))
+ return invalfc(fc, "Setting release_agent not allowed");
ctx->release_agent = param->string;
param->string = NULL;
break;
--
2.34.1