From 29f9b2a93ea2a227d45009ec61f9c99aaefdd20c Mon Sep 17 00:00:00 2001 From: Mark Murray Date: Fri, 24 Aug 2018 14:53:46 +0000 Subject: [PATCH] Limit the amount of "fast" entropy. We don't need nearly as much for security, and the excess just slows things down badly. PR: 230808 Submitted by: rwmaillists@googlemail.com, but tweeked by me Reported by: Danilo Egea Gondolfo Reviewed by: cem,delphij Approved by: re(rgrimes) Approved by: so(delphij) MFC after: 1 Month Differential Revision: https://reviews.freebsd.org/D16873 --- sys/dev/random/random_harvestq.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/sys/dev/random/random_harvestq.c b/sys/dev/random/random_harvestq.c index 4f1494f9627..d8620c84f1d 100644 --- a/sys/dev/random/random_harvestq.c +++ b/sys/dev/random/random_harvestq.c @@ -57,6 +57,10 @@ __FBSDID("$FreeBSD$"); #include #include +#include +#include + +#include #include #include @@ -213,8 +217,12 @@ random_sources_feed(void) /* It's an indenting error. Yeah, Yeah. */ #endif local_read_rate = atomic_readandclear_32(&read_rate); + /* Perform at least one read per round */ + local_read_rate = MAX(local_read_rate, 1); + /* But not exceeding RANDOM_KEYSIZE_WORDS */ + local_read_rate = MIN(local_read_rate, RANDOM_KEYSIZE_WORDS); LIST_FOREACH(rrs, &source_list, rrs_entries) { - for (i = 0; i < p_random_alg_context->ra_poolcount*(local_read_rate + 1); i++) { + for (i = 0; i < p_random_alg_context->ra_poolcount*local_read_rate; 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))); /* It would appear that in some circumstances (e.g. virtualisation),