From b801f1e22c23c259d6a2c955efddd20370de19a6 Mon Sep 17 00:00:00 2001
From: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Date: Fri, 3 Apr 2020 14:11:39 +0200
Subject: [PATCH 1/3] time/namespace: Fix time_for_children symlink
Looking at the contents of the /proc/PID/ns/time_for_children symlink shows
an anomaly:
$ ls -l /proc/self/ns/* |awk '{print $9, $10, $11}'
...
/proc/self/ns/pid -> pid:[4026531836]
/proc/self/ns/pid_for_children -> pid:[4026531836]
/proc/self/ns/time -> time:[4026531834]
/proc/self/ns/time_for_children -> time_for_children:[4026531834]
/proc/self/ns/user -> user:[4026531837]
...
The reference for 'time_for_children' should be a 'time' namespace, just as
the reference for 'pid_for_children' is a 'pid' namespace. In other words,
the above time_for_children link should read:
/proc/self/ns/time_for_children -> time:[4026531834]
Fixes: 769071ac9f20 ("ns: Introduce Time Namespace")
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dmitry Safonov <dima@arista.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Andrei Vagin <avagin@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/a2418c48-ed80-3afe-116e-6611cb799557@gmail.com
---
kernel/time/namespace.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index e6ba064ce7730..3b30288793fe7 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -447,6 +447,7 @@ const struct proc_ns_operations timens_operations = {
const struct proc_ns_operations timens_for_children_operations = {
.name = "time_for_children",
+ .real_ns_name = "time",
.type = CLONE_NEWTIME,
.get = timens_for_children_get,
.put = timens_put,
From eeec26d5da8248ea4e240b8795bb4364213d3247 Mon Sep 17 00:00:00 2001
From: Dmitry Safonov <dima@arista.com>
Date: Mon, 6 Apr 2020 18:13:42 +0100
Subject: [PATCH 2/3] time/namespace: Add max_time_namespaces ucount
Michael noticed that userns limit for number of time namespaces is missing.
Furthermore, time namespace introduced UCOUNT_TIME_NAMESPACES, but didn't
introduce an array member in user_table[]. It would make array's
initialisation OOB write, but by luck the user_table array has an excessive
empty member (all accesses to the array are limited with UCOUNT_COUNTS - so
it silently reuses the last free member.
Fixes user-visible regression: max_inotify_instances by reason of the
missing UCOUNT_ENTRY() has limited max number of namespaces instead of the
number of inotify instances.
Fixes: 769071ac9f20 ("ns: Introduce Time Namespace")
Reported-by: Michael Kerrisk (man-pages) <mtk.manpages@gmail.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andrei Vagin <avagin@gmail.com>
Acked-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: stable@kernel.org
Link: https://lkml.kernel.org/r/20200406171342.128733-1-dima@arista.com
---
Documentation/admin-guide/sysctl/user.rst | 6 ++++++
kernel/ucount.c | 1 +
2 files changed, 7 insertions(+)
diff --git a/Documentation/admin-guide/sysctl/user.rst b/Documentation/admin-guide/sysctl/user.rst
index 650eaa03f15ea..c458245893395 100644
--- a/Documentation/admin-guide/sysctl/user.rst
+++ b/Documentation/admin-guide/sysctl/user.rst
@@ -65,6 +65,12 @@ max_pid_namespaces
The maximum number of pid namespaces that any user in the current
user namespace may create.
+max_time_namespaces
+===================
+
+ The maximum number of time namespaces that any user in the current
+ user namespace may create.
+
max_user_namespaces
===================
diff --git a/kernel/ucount.c b/kernel/ucount.c
index a53cc2b4179c0..29c60eb4ec9bf 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -69,6 +69,7 @@ static struct ctl_table user_table[] = {
UCOUNT_ENTRY("max_net_namespaces"),
UCOUNT_ENTRY("max_mnt_namespaces"),
UCOUNT_ENTRY("max_cgroup_namespaces"),
+ UCOUNT_ENTRY("max_time_namespaces"),
#ifdef CONFIG_INOTIFY_USER
UCOUNT_ENTRY("max_inotify_instances"),
UCOUNT_ENTRY("max_inotify_watches"),
From 0f538e3e712a517bd351607de50cd298102c7c08 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 7 Apr 2020 17:46:43 +0200
Subject: [PATCH 3/3] ucount: Make sure ucounts in /proc/sys/user don't regress
again
Commit 769071ac9f20 "ns: Introduce Time Namespace" broke reporting of
inotify ucounts (max_inotify_instances, max_inotify_watches) in
/proc/sys/user because it has added UCOUNT_TIME_NAMESPACES into enum
ucount_type but didn't properly update reporting in
kernel/ucount.c:setup_userns_sysctls(). This problem got fixed in commit
eeec26d5da82 "time/namespace: Add max_time_namespaces ucount".
Add BUILD_BUG_ON to catch a similar problem in the future.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andrei Vagin <avagin@gmail.com>
Link: https://lkml.kernel.org/r/20200407154643.10102-1-jack@suse.cz
---
kernel/ucount.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 29c60eb4ec9bf..11b1596e2542a 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -82,6 +82,8 @@ bool setup_userns_sysctls(struct user_namespace *ns)
{
#ifdef CONFIG_SYSCTL
struct ctl_table *tbl;
+
+ BUILD_BUG_ON(ARRAY_SIZE(user_table) != UCOUNT_COUNTS + 1);
setup_sysctl_set(&ns->set, &set_root, set_is_seen);
tbl = kmemdup(user_table, sizeof(user_table), GFP_KERNEL);
if (tbl) {