From 9f17d1116d27696ec76c48c5c77df34cba521380 Mon Sep 17 00:00:00 2001 From: Michael Brown Date: Fri, 17 Feb 2023 16:56:11 +0000 Subject: [rng] Allow entropy source to be selected at runtime As noted in commit 3c83843 ("[rng] Check for several functioning RTC interrupts"), experimentation shows that Hyper-V cannot be trusted to reliably generate RTC interrupts. (As noted in commit f3ba0fb ("[hyperv] Provide timer based on the 10MHz time reference count MSR"), Hyper-V appears to suffer from a general problem in reliably generating any legacy interrupts.) An alternative entropy source is therefore required for an image that may be used in a Hyper-V Gen1 virtual machine. The x86 RDRAND instruction provides a suitable alternative entropy source, but may not be supported by all CPUs. We must therefore allow for multiple entropy sources to be compiled in, with the single active entropy source selected only at runtime. Restructure the internal entropy API to allow a working entropy source to be detected and chosen at runtime. Enable the RDRAND entropy source for all x86 builds, since it is likely to be substantially faster than any other source. Signed-off-by: Michael Brown --- src/crypto/null_entropy.c | 40 ---------------------------------------- 1 file changed, 40 deletions(-) delete mode 100644 src/crypto/null_entropy.c (limited to 'src/crypto/null_entropy.c') diff --git a/src/crypto/null_entropy.c b/src/crypto/null_entropy.c deleted file mode 100644 index d1e1a6f73..000000000 --- a/src/crypto/null_entropy.c +++ /dev/null @@ -1,40 +0,0 @@ -/* - * Copyright (C) 2012 Michael Brown . - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public License as - * published by the Free Software Foundation; either version 2 of the - * License, or any later version. - * - * This program is distributed in the hope that it will be useful, but - * WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA - * 02110-1301, USA. - * - * You can also choose to distribute this program under the terms of - * the Unmodified Binary Distribution Licence (as given in the file - * COPYING.UBDL), provided that you have satisfied its requirements. - */ - -FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ); - -/** @file - * - * Nonexistent entropy source - * - * - * This source provides no entropy and must NOT be used in a - * security-sensitive environment. - */ - -#include - -PROVIDE_ENTROPY_INLINE ( null, min_entropy_per_sample ); -PROVIDE_ENTROPY_INLINE ( null, entropy_enable ); -PROVIDE_ENTROPY_INLINE ( null, entropy_disable ); -PROVIDE_ENTROPY_INLINE ( null, get_noise ); -- cgit v1.2.3-55-g7522