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New sysctl kern.entropy.gather=1 to trigger entropy gathering. 

Invokes all on-demand RNG sources.  This enables HWRNG driver
developers to use a dtrace probe on rnd_add_data to examine the data
coming out of the HWRNG:

dtrace -n 'fbt::rnd_add_data:entry /args[0]->name == "amdccp0"/ {
   ...examine buffer args[1] length args[2]...
}'
This commit is contained in:
riastradh 2020-05-05 15:31:42 +00:00
parent c7f0fa2cd2
commit ec335737ff
1 changed files with 36 additions and 2 deletions
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38
sys/kern/kern_entropy.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: kern_entropy.c,v 1.9 2020/05/03 06:33:59 riastradh Exp $ */
/* $NetBSD: kern_entropy.c,v 1.10 2020/05/05 15:31:42 riastradh Exp $ */
/*-
* Copyright (c) 2019 The NetBSD Foundation, Inc.
@ -77,7 +77,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_entropy.c,v 1.9 2020/05/03 06:33:59 riastradh Exp $");
__KERNEL_RCSID(0, "$NetBSD: kern_entropy.c,v 1.10 2020/05/05 15:31:42 riastradh Exp $");
#include <sys/param.h>
#include <sys/types.h>
@ -245,6 +245,7 @@ static void entropy_consolidate(void);
static void entropy_gather_xc(void *, void *);
static void entropy_notify(void);
static int sysctl_entropy_consolidate(SYSCTLFN_ARGS);
static int sysctl_entropy_gather(SYSCTLFN_ARGS);
static void filt_entropy_read_detach(struct knote *);
static int filt_entropy_read_event(struct knote *, long);
static void entropy_request(size_t);
@ -362,6 +363,10 @@ entropy_init(void)
CTLFLAG_PERMANENT|CTLFLAG_READWRITE, CTLTYPE_INT, "consolidate",
SYSCTL_DESCR("Trigger entropy consolidation now"),
sysctl_entropy_consolidate, 0, NULL, 0, CTL_CREATE, CTL_EOL);
sysctl_createv(&entropy_sysctllog, 0, &entropy_sysctlroot, NULL,
CTLFLAG_PERMANENT|CTLFLAG_READWRITE, CTLTYPE_INT, "gather",
SYSCTL_DESCR("Trigger entropy gathering from sources now"),
sysctl_entropy_gather, 0, NULL, 0, CTL_CREATE, CTL_EOL);
/* XXX These should maybe not be readable at securelevel>0. */
sysctl_createv(&entropy_sysctllog, 0, &entropy_sysctlroot, NULL,
CTLFLAG_PERMANENT|CTLFLAG_READONLY|CTLFLAG_PRIVATE, CTLTYPE_INT,
@ -1170,6 +1175,35 @@ sysctl_entropy_consolidate(SYSCTLFN_ARGS)
return error;
}
/*
* sysctl -w kern.entropy.gather=1
*
* Trigger gathering entropy from all on-demand sources, and wait
* for synchronous sources (but not asynchronous sources) to
* complete. Writable only by superuser.
*/
static int
sysctl_entropy_gather(SYSCTLFN_ARGS)
{
struct sysctlnode node = *rnode;
int arg;
int error;
KASSERT(E->stage == ENTROPY_HOT);
node.sysctl_data = &arg;
error = sysctl_lookup(SYSCTLFN_CALL(&node));
if (error || newp == NULL)
return error;
if (arg) {
mutex_enter(&E->lock);
entropy_request(ENTROPY_CAPACITY);
mutex_exit(&E->lock);
}
return 0;
}
/*
* entropy_extract(buf, len, flags)
*