time: add get_timespec64 and put_timespec64

Add helper functions to convert between struct timespec64 and
struct timespec at userspace boundaries.

This is a preparatory patch to use timespec64 as the basic type
internally in the kernel as timespec is not y2038 safe on 32 bit systems.
The patch helps the cause by containing all data conversions at the
userspace boundaries within these functions.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 28 insertions, 0 deletions

diff --git a/kernel/time/time.c b/kernel/time/time.c
index 7c89e437c4d7..adb9853ca6b0 100644
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -890,3 +890,31 @@ struct timespec64 timespec64_add_safe(const struct timespec64 lhs,
 
 	return res;
 }
+
+int get_timespec64(struct timespec64 *ts,
+		   const struct timespec __user *uts)
+{
+	struct timespec kts;
+	int ret;
+
+	ret = copy_from_user(&kts, uts, sizeof(kts));
+	if (ret)
+		return -EFAULT;
+
+	ts->tv_sec = kts.tv_sec;
+	ts->tv_nsec = kts.tv_nsec;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(get_timespec64);
+
+int put_timespec64(const struct timespec64 *ts,
+		   struct timespec __user *uts)
+{
+	struct timespec kts = {
+		.tv_sec = ts->tv_sec,
+		.tv_nsec = ts->tv_nsec
+	};
+	return copy_to_user(uts, &kts, sizeof(kts)) ? -EFAULT : 0;
+}
+EXPORT_SYMBOL_GPL(put_timespec64);