The branch main has been updated by kevans:
URL:
https://cgit.FreeBSD.org/src/commit/?id=5e79bba562bc303eed669dbd0d391b6c6a9c289b
commit 5e79bba562bc303eed669dbd0d391b6c6a9c289b
Author: Kyle Evans <kev...@freebsd.org>
AuthorDate: 2021-09-20 05:46:21 +0000
Commit: Kyle Evans <kev...@freebsd.org>
CommitDate: 2021-09-23 06:03:02 +0000
kern: random: collect ~16x less from fast-entropy sources
Previously, we were collecting at a base rate of:
64 bits x 32 pools x 10 Hz = 2.5 kB/s
This change drops it to closer to 64-ish bits per pool per second, to
work a little better with entropy providers in virtualized environments
without compromising the security goals of Fortuna.
Reviewed by: #csprng (cem, delphij, markm)
Differential Revision: https://reviews.freebsd.org/D32021
---
sys/dev/random/random_harvestq.c | 26 +++++++++++++++++++++++---
1 file changed, 23 insertions(+), 3 deletions(-)
diff --git a/sys/dev/random/random_harvestq.c b/sys/dev/random/random_harvestq.c
index 74a75aa20e3f..46c069126949 100644
--- a/sys/dev/random/random_harvestq.c
+++ b/sys/dev/random/random_harvestq.c
@@ -72,6 +72,13 @@ __FBSDID("$FreeBSD$");
#define _RANDOM_HARVEST_UMA_OFF (1u << RANDOM_UMA)
#endif
+/*
+ * Note that random_sources_feed() will also use this to try and split up
+ * entropy into a subset of pools per iteration with the goal of feeding
+ * HARVESTSIZE into every pool at least once per second.
+ */
+#define RANDOM_KTHREAD_HZ 10
+
static void random_kthread(void);
static void random_sources_feed(void);
@@ -199,7 +206,8 @@ random_kthread(void)
}
}
/* XXX: FIX!! This is a *great* place to pass hardware/live
entropy to random(9) */
- tsleep_sbt(&harvest_context.hc_kthread_proc, 0, "-", SBT_1S/10,
0, C_PREL(1));
+ tsleep_sbt(&harvest_context.hc_kthread_proc, 0, "-",
+ SBT_1S/RANDOM_KTHREAD_HZ, 0, C_PREL(1));
}
random_kthread_control = -1;
wakeup(&harvest_context.hc_kthread_proc);
@@ -229,11 +237,23 @@ random_sources_feed(void)
uint32_t entropy[HARVESTSIZE];
struct epoch_tracker et;
struct random_sources *rrs;
- u_int i, n;
+ u_int i, n, npools;
bool rse_warm;
rse_warm = epoch_inited;
+ /*
+ * Evenly-ish distribute pool population across the second based on how
+ * frequently random_kthread iterates.
+ *
+ * For Fortuna, the math currently works out as such:
+ *
+ * 64 bits * 4 pools = 256 bits per iteration
+ * 256 bits * 10 Hz = 2560 bits per second, 320 B/s
+ *
+ */
+ npools = howmany(p_random_alg_context->ra_poolcount, RANDOM_KTHREAD_HZ);
+
/*
* Step over all of live entropy sources, and feed their output
* to the system-wide RNG.
@@ -241,7 +261,7 @@ random_sources_feed(void)
if (rse_warm)
epoch_enter_preempt(rs_epoch, &et);
CK_LIST_FOREACH(rrs, &source_list, rrs_entries) {
- for (i = 0; i < p_random_alg_context->ra_poolcount; i++) {
+ for (i = 0; i < npools; i++) {
n = rrs->rrs_source->rs_read(entropy, sizeof(entropy));
KASSERT((n <= sizeof(entropy)), ("%s: rs_read returned
too much data (%u > %zu)", __func__, n, sizeof(entropy)));
/*
_______________________________________________
dev-commits-src-main@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/dev-commits-src-main
To unsubscribe, send any mail to "dev-commits-src-main-unsubscr...@freebsd.org"
