| Message ID | 20220623165226.1335679-1-Jason@zx2c4.com |
|---|---|
| State | New |
| Headers | show |
| Series | timekeeping: contribute wall clock to rng on time change | expand |
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 8e4b3c32fcf9..ad55da792f13 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1346,6 +1346,9 @@ int do_settimeofday64(const struct timespec64 *ts) if (!ret) audit_tk_injoffset(ts_delta); + ktime_get_real_ts64(&xt); + add_device_randomness(&xt, sizeof(xt)); + return ret; } EXPORT_SYMBOL(do_settimeofday64); @@ -2475,6 +2478,9 @@ int do_adjtimex(struct __kernel_timex *txc) ntp_notify_cmos_timer(); + ktime_get_real_ts64(&ts); + add_device_randomness(&ts, sizeof(ts)); + return ret; }
The rng's random_init() function contributes the real time to the rng at boot time, so that events can at least start in relation to something particular in the real world. But this clock might not yet be set that point in boot, so nothing is contributed. In addition, the relation between minor clock changes from, say, NTP, and the cycle counter is potentially useful entropic data. This commit addresses this by mixing in a time stamp on calls to settimeofday and adjtimex. No entropy is credited in doing so, so it doesn't make initialization faster, but it is still useful input to have. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> --- kernel/time/timekeeping.c | 6 ++++++ 1 file changed, 6 insertions(+)