[tip: timers/core] timerfd: Make timerfd_settime() time namespace aware

[tip-bot2 for Andrei Vagin]

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     20a40308f2ce12392e2cfa662494b5079ea67bdf
Gitweb:        https://git.kernel.org/tip/20a40308f2ce12392e2cfa662494b5079ea67bdf
Author:        Andrei Vagin <avagin@xxxxxxxxx>
AuthorDate:    Tue, 12 Nov 2019 01:27:02 
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Mon, 13 Jan 2020 08:10:51 +01:00

timerfd: Make timerfd_settime() time namespace aware

timerfd_settime() accepts an absolute value of the expiration time if
TFD_TIMER_ABSTIME is specified. This value is in the task's time namespace
and has to be converted to the host's time namespace.

Co-developed-by: Dmitry Safonov <dima@xxxxxxxxxx>
Signed-off-by: Andrei Vagin <avagin@xxxxxxxxx>
Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20191112012724.250792-14-dima@xxxxxxxxxx

---
 fs/timerfd.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/timerfd.c b/fs/timerfd.c
index ac7f59a..c5509d2 100644
--- a/fs/timerfd.c
+++ b/fs/timerfd.c
@@ -26,6 +26,7 @@
 #include <linux/syscalls.h>
 #include <linux/compat.h>
 #include <linux/rcupdate.h>
+#include <linux/time_namespace.h>
 
 struct timerfd_ctx {
 	union {
@@ -196,6 +197,8 @@ static int timerfd_setup(struct timerfd_ctx *ctx, int flags,
 	}
 
 	if (texp != 0) {
+		if (flags & TFD_TIMER_ABSTIME)
+			texp = timens_ktime_to_host(clockid, texp);
 		if (isalarm(ctx)) {
 			if (flags & TFD_TIMER_ABSTIME)
 				alarm_start(&ctx->t.alarm, texp);