From: "Michael Weiß" <michael.weiss@aisec.fraunhofer.de>
To: Thomas Gleixner <tglx@linutronix.de>,
Andrei Vagin <avagin@gmail.com>,
Dmitry Safonov <0x7f454c46@gmail.com>,
Christian Brauner <christian.brauner@ubuntu.com>
Cc: linux-kernel@vger.kernel.org,
"Michael Weiß" <michael.weiss@aisec.fraunhofer.de>
Subject: [PATCH v2 2/4] time: make getboottime64 aware of time namespace
Date: Thu, 8 Oct 2020 07:39:42 +0200 [thread overview]
Message-ID: <20201008053944.32718-3-michael.weiss@aisec.fraunhofer.de> (raw)
In-Reply-To: <20201008053944.32718-1-michael.weiss@aisec.fraunhofer.de>
getboottime64() provides the time stamp of system boot. In case of
time namespaces, the offset to the boot time stamp was not applied
earlier. However, getboottime64 is used e.g., in /proc/stat to print
the system boot time to userspace. In container runtimes which utilize
time namespaces to virtualize boottime of a container, this leaks
information about the host system boot time.
Therefore, we make getboottime64() to respect the time namespace offset
for boottime by subtracting the boottime offset.
Signed-off-by: Michael Weiß <michael.weiss@aisec.fraunhofer.de>
---
kernel/time/timekeeping.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 4c47f388a83f..67530cdb389e 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -17,6 +17,7 @@
#include <linux/clocksource.h>
#include <linux/jiffies.h>
#include <linux/time.h>
+#include <linux/time_namespace.h>
#include <linux/tick.h>
#include <linux/stop_machine.h>
#include <linux/pvclock_gtod.h>
@@ -2154,6 +2155,8 @@ void getboottime64(struct timespec64 *ts)
{
struct timekeeper *tk = &tk_core.timekeeper;
ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
+ /* shift boot time stamp according to the timens offset */
+ t = timens_ktime_to_host(CLOCK_BOOTTIME, t);
*ts = ktime_to_timespec64(t);
}
--
2.20.1
next prev parent reply other threads:[~2020-10-08 5:40 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 5:39 [PATCH v2 0/4] time namespace aware system boot time Michael Weiß
2020-10-08 5:39 ` [PATCH v2 1/4] timens: additional helper function to add boottime in nsec Michael Weiß
2020-10-08 5:39 ` Michael Weiß [this message]
2020-10-09 13:28 ` [PATCH v2 2/4] time: make getboottime64 aware of time namespace Christian Brauner
2020-10-09 13:55 ` J. Bruce Fields
2020-10-09 20:08 ` Thomas Gleixner
2020-10-12 21:13 ` J. Bruce Fields
2020-10-12 21:36 ` Thomas Gleixner
2020-10-14 22:05 ` J. Bruce Fields
2020-10-16 12:37 ` Thomas Gleixner
2020-10-10 7:19 ` Andrei Vagin
2020-10-10 11:50 ` Michael Weiß
2020-10-10 16:37 ` Thomas Gleixner
2020-10-13 20:05 ` Christian Brauner
2020-10-08 5:39 ` [PATCH v2 3/4] fs/proc: apply timens offset for start_boottime of processes Michael Weiß
2020-10-08 5:39 ` [PATCH v2 4/4] selftests/timens: added selftest for /proc/stat btime Michael Weiß
2020-10-09 13:21 ` [PATCH v2 0/4] time namespace aware system boot time Christian Brauner
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