[PATCHv7 02/33] time: Add timens_offsets to be used for tasks in timens

[Dmitry Safonov]

From: Andrei Vagin <avagin@xxxxxxxxxx>

Introduce offsets for time namespace. They will contain an adjustment
needed to convert clocks to/from host's.

A new namespace is created with the same offsets as the time namespace
of the current process.

Signed-off-by: Andrei Vagin <avagin@xxxxxxxxxx>
Co-developed-by: Dmitry Safonov <dima@xxxxxxxxxx>
Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>
---
 include/linux/time_namespace.h | 22 ++++++++++++++++++++++
 kernel/time/namespace.c        |  2 ++
 2 files changed, 24 insertions(+)

diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
index 873b908c9ba8..3d429c7ecca5 100644
--- a/include/linux/time_namespace.h
+++ b/include/linux/time_namespace.h
@@ -12,11 +12,17 @@
 struct user_namespace;
 extern struct user_namespace init_user_ns;
 
+struct timens_offsets {
+	struct timespec64 monotonic;
+	struct timespec64 boottime;
+};
+
 struct time_namespace {
 	struct kref kref;
 	struct user_namespace *user_ns;
 	struct ucounts *ucounts;
 	struct ns_common ns;
+	struct timens_offsets offsets;
 } __randomize_layout;
 extern struct time_namespace init_time_ns;
 
@@ -37,6 +43,20 @@ static inline void put_time_ns(struct time_namespace *ns)
 	kref_put(&ns->kref, free_time_ns);
 }
 
+static inline void timens_add_monotonic(struct timespec64 *ts)
+{
+	struct timens_offsets *ns_offsets = &current->nsproxy->time_ns->offsets;
+
+	*ts = timespec64_add(*ts, ns_offsets->monotonic);
+}
+
+static inline void timens_add_boottime(struct timespec64 *ts)
+{
+	struct timens_offsets *ns_offsets = &current->nsproxy->time_ns->offsets;
+
+	*ts = timespec64_add(*ts, ns_offsets->boottime);
+}
+
 #else
 static inline struct time_namespace *get_time_ns(struct time_namespace *ns)
 {
@@ -61,6 +81,8 @@ static inline int timens_on_fork(struct nsproxy *nsproxy, struct task_struct *ts
 	return 0;
 }
 
+static inline void timens_add_monotonic(struct timespec64 *ts) {}
+static inline void timens_add_boottime(struct timespec64 *ts) {}
 #endif
 
 #endif /* _LINUX_TIMENS_H */
diff --git a/kernel/time/namespace.c b/kernel/time/namespace.c
index 2662a69e0382..c2a58e45fc4b 100644
--- a/kernel/time/namespace.c
+++ b/kernel/time/namespace.c
@@ -14,6 +14,7 @@
 #include <linux/slab.h>
 #include <linux/cred.h>
 #include <linux/err.h>
+#include <linux/mm.h>
 
 static struct ucounts *inc_time_namespaces(struct user_namespace *ns)
 {
@@ -60,6 +61,7 @@ static struct time_namespace *clone_time_ns(struct user_namespace *user_ns,
 	ns->ucounts = ucounts;
 	ns->ns.ops = &timens_operations;
 	ns->user_ns = get_user_ns(user_ns);
+	ns->offsets = old_ns->offsets;
 	return ns;
 
 fail_free:
-- 
2.23.0