diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-10-25 10:40:08 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-10-25 10:40:08 -0700 |
| commit | 91f28da8c9a054286d6917ce191349455c479478 (patch) | |
| tree | e095a831ada79f835d1d9310df529007665a498e /kernel | |
| parent | d76913908102044f14381df865bb74df17a538cb (diff) | |
| parent | c6e169bc146a76d5ccbf4d3825f705414352bd03 (diff) | |
Merge tag '20201024-v4-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/prandom
Pull random32 updates from Willy Tarreau:
"Make prandom_u32() less predictable.
This is the cleanup of the latest series of prandom_u32
experimentations consisting in using SipHash instead of Tausworthe to
produce the randoms used by the network stack.
The changes to the files were kept minimal, and the controversial
commit that used to take noise from the fast_pool (f227e3ec3b5c) was
reverted. Instead, a dedicated "net_rand_noise" per_cpu variable is
fed from various sources of activities (networking, scheduling) to
perturb the SipHash state using fast, non-trivially predictable data,
instead of keeping it fully deterministic. The goal is essentially to
make any occasional memory leakage or brute-force attempt useless.
The resulting code was verified to be very slightly faster on x86_64
than what is was with the controversial commit above, though this
remains barely above measurement noise. It was also tested on i386 and
arm, and build- tested only on arm64"
Link: https://lore.kernel.org/netdev/20200808152628.GA27941@SDF.ORG/
* tag '20201024-v4-5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/prandom:
random32: add a selftest for the prandom32 code
random32: add noise from network and scheduling activity
random32: make prandom_u32() output unpredictable
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/time/timer.c | 9 |
1 files changed, 2 insertions, 7 deletions
diff --git a/kernel/time/timer.c b/kernel/time/timer.c index dda05f4b7a1f..de37e33a868d 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -1706,6 +1706,8 @@ void update_process_times(int user_tick) { struct task_struct *p = current; + PRANDOM_ADD_NOISE(jiffies, user_tick, p, 0); + /* Note: this timer irq context must be accounted for as well. */ account_process_tick(p, user_tick); run_local_timers(); @@ -1717,13 +1719,6 @@ void update_process_times(int user_tick) scheduler_tick(); if (IS_ENABLED(CONFIG_POSIX_TIMERS)) run_posix_cpu_timers(); - - /* The current CPU might make use of net randoms without receiving IRQs - * to renew them often enough. Let's update the net_rand_state from a - * non-constant value that's not affine to the number of calls to make - * sure it's updated when there's some activity (we don't care in idle). - */ - this_cpu_add(net_rand_state.s1, rol32(jiffies, 24) + user_tick); } /** |