Merge tag 'random-5.17-rc3-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

Pull random number generator fixes from Jason Donenfeld:
 "For this week, we have:

   - A fix to make more frequent use of hwgenerator randomness, from
     Dominik.

   - More cleanups to the boot initialization sequence, from Dominik.

   - A fix for an old shortcoming with the ZAP ioctl, from me.

   - A workaround for a still unfixed Clang CFI/FullLTO compiler bug,
     from me. On one hand, it's a bummer to commit workarounds for
     experimental compiler features that have bugs. But on the other, I
     think this actually improves the code somewhat, independent of the
     bug. So a win-win"

* tag 'random-5.17-rc3-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random:
  random: only call crng_finalize_init() for primary_crng
  random: access primary_pool directly rather than through pointer
  random: wake up /dev/random writers after zap
  random: continually use hwgenerator randomness
  lib/crypto: blake2s: avoid indirect calls to compression function for Clang CFI

1 files changed, 22 insertions, 17 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 68613f0b6887..3404a91edf29 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -762,7 +762,7 @@ static bool crng_init_try_arch(struct crng_state *crng)
 	return arch_init;
 }
 
-static bool __init crng_init_try_arch_early(struct crng_state *crng)
+static bool __init crng_init_try_arch_early(void)
 {
 	int i;
 	bool arch_init = true;
@@ -774,7 +774,7 @@ static bool __init crng_init_try_arch_early(struct crng_state *crng)
 			rv = random_get_entropy();
 			arch_init = false;
 		}
-		crng->state[i] ^= rv;
+		primary_crng.state[i] ^= rv;
 	}
 
 	return arch_init;
@@ -788,22 +788,20 @@ static void crng_initialize_secondary(struct crng_state *crng)
 	crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
 }
 
-static void __init crng_initialize_primary(struct crng_state *crng)
+static void __init crng_initialize_primary(void)
 {
-	_extract_entropy(&crng->state[4], sizeof(u32) * 12);
-	if (crng_init_try_arch_early(crng) && trust_cpu && crng_init < 2) {
+	_extract_entropy(&primary_crng.state[4], sizeof(u32) * 12);
+	if (crng_init_try_arch_early() && trust_cpu && crng_init < 2) {
 		invalidate_batched_entropy();
 		numa_crng_init();
 		crng_init = 2;
 		pr_notice("crng init done (trusting CPU's manufacturer)\n");
 	}
-	crng->init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
+	primary_crng.init_time = jiffies - CRNG_RESEED_INTERVAL - 1;
 }
 
-static void crng_finalize_init(struct crng_state *crng)
+static void crng_finalize_init(void)
 {
-	if (crng != &primary_crng || crng_init >= 2)
-		return;
 	if (!system_wq) {
 		/* We can't call numa_crng_init until we have workqueues,
 		 * so mark this for processing later. */
@@ -814,6 +812,7 @@ static void crng_finalize_init(struct crng_state *crng)
 	invalidate_batched_entropy();
 	numa_crng_init();
 	crng_init = 2;
+	crng_need_final_init = false;
 	process_random_ready_list();
 	wake_up_interruptible(&crng_init_wait);
 	kill_fasync(&fasync, SIGIO, POLL_IN);
@@ -980,7 +979,8 @@ static void crng_reseed(struct crng_state *crng, bool use_input_pool)
 	memzero_explicit(&buf, sizeof(buf));
 	WRITE_ONCE(crng->init_time, jiffies);
 	spin_unlock_irqrestore(&crng->lock, flags);
-	crng_finalize_init(crng);
+	if (crng == &primary_crng && crng_init < 2)
+		crng_finalize_init();
 }
 
 static void _extract_crng(struct crng_state *crng, u8 out[CHACHA_BLOCK_SIZE])
@@ -1697,8 +1697,8 @@ int __init rand_initialize(void)
 {
 	init_std_data();
 	if (crng_need_final_init)
-		crng_finalize_init(&primary_crng);
-	crng_initialize_primary(&primary_crng);
+		crng_finalize_init();
+	crng_initialize_primary();
 	crng_global_init_time = jiffies;
 	if (ratelimit_disable) {
 		urandom_warning.interval = 0;
@@ -1856,7 +1856,10 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
 		 */
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
-		input_pool.entropy_count = 0;
+		if (xchg(&input_pool.entropy_count, 0) && random_write_wakeup_bits) {
+			wake_up_interruptible(&random_write_wait);
+			kill_fasync(&fasync, SIGIO, POLL_OUT);
+		}
 		return 0;
 	case RNDRESEEDCRNG:
 		if (!capable(CAP_SYS_ADMIN))
@@ -2205,13 +2208,15 @@ void add_hwgenerator_randomness(const char *buffer, size_t count,
 			return;
 	}
 
-	/* Suspend writing if we're above the trickle threshold.
+	/* Throttle writing if we're above the trickle threshold.
 	 * We'll be woken up again once below random_write_wakeup_thresh,
-	 * or when the calling thread is about to terminate.
+	 * when the calling thread is about to terminate, or once
+	 * CRNG_RESEED_INTERVAL has lapsed.
 	 */
-	wait_event_interruptible(random_write_wait,
+	wait_event_interruptible_timeout(random_write_wait,
 			!system_wq || kthread_should_stop() ||
-			POOL_ENTROPY_BITS() <= random_write_wakeup_bits);
+			POOL_ENTROPY_BITS() <= random_write_wakeup_bits,
+			CRNG_RESEED_INTERVAL);
 	mix_pool_bytes(buffer, count);
 	credit_entropy_bits(entropy);
 }