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random: Avoid magic numbers

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Move RANDOM_FORTUNA_{NPOOLS,DEFPOOLSIZE} from fortuna.c to fortuna.h
and use RANDOM_FORTUNA_DEFPOOLSIZE in random_harvestq.c rather than
having a magic (albeit explained in a comment) number.  The NPOOLS
value will be used in a later commit.

Reviewed by:	cem
MFC after:	1 week
Sponsored by:	Amazon
Differential Revision:	https://reviews.freebsd.org/D46693

(cherry picked from commit 32fce09268ddd97efb4412529ba57293554c5985)
This commit is contained in:
Colin Percival 2024-09-17 22:12:04 -07:00
parent a112b062e0
commit 0e9cdcc514
3 changed files with 9 additions and 6 deletions
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2
sys/dev/random/fortuna.c
View file

@ -72,8 +72,6 @@
#include <dev/random/fortuna.h>
/* Defined in FS&K */
#define RANDOM_FORTUNA_NPOOLS 32 /* The number of accumulation pools */
#define RANDOM_FORTUNA_DEFPOOLSIZE 64 /* The default pool size/length for a (re)seed */
#define RANDOM_FORTUNA_MAX_READ (1 << 20) /* Max bytes from AES before rekeying */
#define RANDOM_FORTUNA_BLOCKS_PER_KEY (1 << 16) /* Max blocks from AES before rekeying */
CTASSERT(RANDOM_FORTUNA_BLOCKS_PER_KEY * RANDOM_BLOCKSIZE ==

4
sys/dev/random/fortuna.h
View file

@ -27,6 +27,10 @@
#ifndef SYS_DEV_RANDOM_FORTUNA_H_INCLUDED
#define SYS_DEV_RANDOM_FORTUNA_H_INCLUDED
/* Defined in FS&K */
#define RANDOM_FORTUNA_NPOOLS 32 /* The number of accumulation pools */
#define RANDOM_FORTUNA_DEFPOOLSIZE 64 /* The default pool size/length for a (re)seed */
#ifdef _KERNEL
typedef struct mtx mtx_t;
#define RANDOM_RESEED_INIT_LOCK(x) mtx_init(&fortuna_state.fs_mtx, "reseed mutex", NULL, MTX_DEF)

9
sys/dev/random/random_harvestq.c
View file

@ -55,6 +55,7 @@
#include <crypto/rijndael/rijndael-api-fst.h>
#include <crypto/sha2/sha256.h>
#include <dev/random/fortuna.h>
#include <dev/random/hash.h>
#include <dev/random/randomdev.h>
#include <dev/random/random_harvestq.h>
@ -260,8 +261,8 @@ random_sources_feed(void)
* stuck for a few seconds with random_kthread gradually collecting a
* small chunk of entropy every 1 / RANDOM_KTHREAD_HZ seconds.
*
* The value 64 below is RANDOM_FORTUNA_DEFPOOLSIZE, i.e. chosen to
* fill Fortuna's pools in the default configuration. With another
* We collect RANDOM_FORTUNA_DEFPOOLSIZE bytes per pool, i.e. enough
* to fill Fortuna's pools in the default configuration. With another
* PRNG or smaller pools for Fortuna, we might collect more entropy
* than needed to fill the pools, but this is harmless; alternatively,
* a different PRNG, larger pools, or fast entropy sources which are
@ -271,8 +272,8 @@ random_sources_feed(void)
* try again for a large amount of entropy.
*/
if (!p_random_alg_context->ra_seeded())
npools = howmany(p_random_alg_context->ra_poolcount * 64,
sizeof(entropy));
npools = howmany(p_random_alg_context->ra_poolcount *
RANDOM_FORTUNA_DEFPOOLSIZE, sizeof(entropy));
/*
* Step over all of live entropy sources, and feed their output