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-rw-r--r--include/linux/time64.h21
1 files changed, 21 insertions, 0 deletions
diff --git a/include/linux/time64.h b/include/linux/time64.h
index f38d382ffec1..a620ee610b9f 100644
--- a/include/linux/time64.h
+++ b/include/linux/time64.h
@@ -33,6 +33,17 @@ struct itimerspec64 {
#define KTIME_MAX ((s64)~((u64)1 << 63))
#define KTIME_SEC_MAX (KTIME_MAX / NSEC_PER_SEC)
+/*
+ * Limits for settimeofday():
+ *
+ * To prevent setting the time close to the wraparound point time setting
+ * is limited so a reasonable uptime can be accomodated. Uptime of 30 years
+ * should be really sufficient, which means the cutoff is 2232. At that
+ * point the cutoff is just a small part of the larger problem.
+ */
+#define TIME_UPTIME_SEC_MAX (30LL * 365 * 24 *3600)
+#define TIME_SETTOD_SEC_MAX (KTIME_SEC_MAX - TIME_UPTIME_SEC_MAX)
+
static inline int timespec64_equal(const struct timespec64 *a,
const struct timespec64 *b)
{
@@ -100,6 +111,16 @@ static inline bool timespec64_valid_strict(const struct timespec64 *ts)
return true;
}
+static inline bool timespec64_valid_settod(const struct timespec64 *ts)
+{
+ if (!timespec64_valid(ts))
+ return false;
+ /* Disallow values which cause overflow issues vs. CLOCK_REALTIME */
+ if ((unsigned long long)ts->tv_sec >= TIME_SETTOD_SEC_MAX)
+ return false;
+ return true;
+}
+
/**
* timespec64_to_ns - Convert timespec64 to nanoseconds
* @ts: pointer to the timespec64 variable to be converted