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vmgenid(4): Integrate as a random(4) source

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The number is public and has no "entropy," but should be integrated quickly
on VM rewind events to avoid duplicate sequences.

Approved by:	csprng(markm)
Differential Revision:	https://reviews.freebsd.org/D22946
This commit is contained in:
Conrad Meyer 2020-01-01 00:35:02 +00:00
parent 80a1b8c5e3
commit 767991d2be
4 changed files with 31 additions and 0 deletions
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7
sys/dev/random/fortuna.c
View File

@ -358,6 +358,13 @@ random_fortuna_process_event(struct harvest_event *event)
* during accumulation/reseeding and reading/regating.
*/
pl = event->he_destination % RANDOM_FORTUNA_NPOOLS;
/*
* If a VM generation ID changes (clone and play or VM rewind), we want
* to incorporate that as soon as possible. Override destingation pool
* for immediate next use.
*/
if (event->he_source == RANDOM_PURE_VMGENID)
pl = 0;
/*
* We ignore low entropy static/counter fields towards the end of the
* he_event structure in order to increase measurable entropy when

1
sys/dev/random/random_harvestq.c
View File

@ -354,6 +354,7 @@ static const char *random_source_descr[ENTROPYSOURCE] = {
[RANDOM_PURE_CCP] = "PURE_CCP",
[RANDOM_PURE_DARN] = "PURE_DARN",
[RANDOM_PURE_TPM] = "PURE_TPM",
[RANDOM_PURE_VMGENID] = "VMGENID",
/* "ENTROPYSOURCE" */
};

22
sys/dev/vmgenc/vmgenc_acpi.c
View File

@ -52,12 +52,14 @@ __FBSDID("$FreeBSD$");
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/random.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <contrib/dev/acpica/include/acpi.h>
#include <dev/acpica/acpivar.h>
#include <dev/random/random_harvestq.h>
#include <dev/vmgenc/vmgenc_acpi.h>
#ifndef ACPI_NOTIFY_STATUS_CHANGED
@ -79,6 +81,20 @@ struct vmgenc_softc {
uint8_t vmg_cache_guid[GUID_BYTES];
};
static void
vmgenc_harvest_all(const void *p, size_t sz)
{
size_t nbytes;
while (sz > 0) {
nbytes = MIN(sz,
sizeof(((struct harvest_event *)0)->he_entropy));
random_harvest_direct(p, nbytes, RANDOM_PURE_VMGENID);
p = (const char *)p + nbytes;
sz -= nbytes;
}
}
static void
vmgenc_status_changed(void *context)
{
@ -97,6 +113,8 @@ vmgenc_status_changed(void *context)
/* Update cache. */
memcpy(sc->vmg_cache_guid, guid, GUID_BYTES);
vmgenc_harvest_all(sc->vmg_cache_guid, sizeof(sc->vmg_cache_guid));
EVENTHANDLER_INVOKE(acpi_vmgenc_event);
acpi_UserNotify("VMGenerationCounter", acpi_get_handle(dev), 0);
}
@ -219,6 +237,9 @@ vmgenc_attach(device_t dev)
memcpy(sc->vmg_cache_guid, __DEVOLATILE(void *, sc->vmg_pguid),
sizeof(sc->vmg_cache_guid));
random_harvest_register_source(RANDOM_PURE_VMGENID);
vmgenc_harvest_all(sc->vmg_cache_guid, sizeof(sc->vmg_cache_guid));
AcpiInstallNotifyHandler(h, ACPI_DEVICE_NOTIFY, vmgenc_notify, dev);
return (0);
}
@ -238,3 +259,4 @@ static driver_t vmgenc_driver = {
static devclass_t vmgenc_devclass;
DRIVER_MODULE(vmgenc, acpi, vmgenc_driver, vmgenc_devclass, NULL, NULL);
MODULE_DEPEND(vmgenc, acpi, 1, 1, 1);
MODULE_DEPEND(vemgenc, random_harvestq, 1, 1, 1);

1
sys/sys/random.h
View File

@ -102,6 +102,7 @@ enum random_entropy_source {
RANDOM_PURE_CCP,
RANDOM_PURE_DARN,
RANDOM_PURE_TPM,
RANDOM_PURE_VMGENID,
ENTROPYSOURCE
};
_Static_assert(ENTROPYSOURCE <= 32,