From: Jason A. Donenfeld Jason@zx2c4.com
commit b8ac29b40183a6038919768b5d189c9bd91ce9b4 upstream.
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 Reviewed-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Eric Biggers ebiggers@google.com Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/time/timekeeping.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -23,6 +23,7 @@ #include <linux/pvclock_gtod.h> #include <linux/compiler.h> #include <linux/audit.h> +#include <linux/random.h>
#include "tick-internal.h" #include "ntp_internal.h" @@ -1256,8 +1257,10 @@ out: /* signal hrtimers about time change */ clock_was_set();
- if (!ret) + if (!ret) { audit_tk_injoffset(ts_delta); + add_device_randomness(ts, sizeof(*ts)); + }
return ret; } @@ -2336,6 +2339,7 @@ int do_adjtimex(struct __kernel_timex *t ret = timekeeping_validate_timex(txc); if (ret) return ret; + add_device_randomness(txc, sizeof(*txc));
if (txc->modes & ADJ_SETOFFSET) { struct timespec64 delta; @@ -2353,6 +2357,7 @@ int do_adjtimex(struct __kernel_timex *t audit_ntp_init(&ad);
ktime_get_real_ts64(&ts); + add_device_randomness(&ts, sizeof(ts));
raw_spin_lock_irqsave(&timekeeper_lock, flags); write_seqcount_begin(&tk_core.seq);