Make arc4random() depend on less subsystems by decoupling extract_entropy()

from the enqueue_randomness() logic.

Add add_event_data() which just enqueues some data into the event buffer
which can be used by extract_entropy(). On top of this remove the
timeout_del() call in dequeue_randomness() it does serve any meaningful
reason.
OK kettenis@ deraadt@ mpi@

diff --git a/sys/dev/rnd.c b/sys/dev/rnd.c
index 483ee30..4ad4a73 100644 (file)
--- a/sys/dev/rnd.c
+++ b/sys/dev/rnd.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: rnd.c,v 1.227 2024/06/04 08:26:11 claudio Exp $       */
+/*     $OpenBSD: rnd.c,v 1.228 2024/06/14 10:17:05 claudio Exp $       */
 
 /*
  * Copyright (c) 2011,2020 Theo de Raadt.
@@ -172,8 +172,8 @@ const struct filterops randomwrite_filtops = {
 /*
  * This function mixes entropy and timing into the entropy input ring.
  */
-void
-enqueue_randomness(u_int val)
+static void
+add_event_data(u_int val)
 {
        struct rand_event *rep;
        int e;
@@ -182,6 +182,12 @@ enqueue_randomness(u_int val)
        rep = &rnd_event_space[e];
        rep->re_time += cpu_rnd_messybits();
        rep->re_val += val;
+}
+
+void
+enqueue_randomness(u_int val)
+{
+       add_event_data(val);
 
        if (rnd_cold) {
                dequeue_randomness(NULL);
@@ -248,9 +254,6 @@ dequeue_randomness(void *v)
        u_int32_t buf[2];
        u_int startp, startc, i;
 
-       if (!rnd_cold)
-               timeout_del(&rnd_timeout);
-
        /* Some very new damage */
        startp = rnd_event_prod - QEVCONSUME;
        for (i = 0; i < QEVCONSUME; i++) {
@@ -304,10 +307,8 @@ extract_entropy(u_int8_t *buf)
 
        /*
         * Modify pool so next hash will produce different results.
-        * During boot-time enqueue/dequeue stage, avoid recursion.
-       */
-       if (!rnd_cold)
-               enqueue_randomness(extract_pool[0]);
+        */
+       add_event_data(extract_pool[0]);
        dequeue_randomness(NULL);
 
        /* Wipe data from memory */