git: 8635f8697763 - main - random: Make the entropy source registration interface more uniform
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Date: Mon, 08 Sep 2025 15:26:31 UTC
The branch main has been updated by markj:
URL: https://cgit.FreeBSD.org/src/commit/?id=8635f86977638eed966ec59cd319521fffb4df70
commit 8635f86977638eed966ec59cd319521fffb4df70
Author: Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2025-09-08 14:41:47 +0000
Commit: Mark Johnston <markj@FreeBSD.org>
CommitDate: 2025-09-08 15:21:43 +0000
random: Make the entropy source registration interface more uniform
Most pure sources work under a "pull" model wherein a dedicated thread
polls the source at regular intervals (every 100ms). A couple of
sources, however, will instead call random_harvest_direct() to provide
entropy samples. Such sources were not calling random_source_register()
and thus weren't in the global random source list.
Modify "push" sources to use random_source_register() like other sources
do. Such sources omit an implementation of rs_read and are thus skipped
by the above-mentioned thread. This makes it easier to allow pure
sources to provide a min-entropy estimate in a uniform way.
Reviewed by: cem
MFC after: 2 weeks
Sponsored by: Stormshield
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D52229
---
sys/dev/random/random_harvestq.c | 29 ++++++++++-------------------
sys/dev/random/randomdev.h | 2 ++
sys/dev/tpm/tpm20.c | 13 ++++++++++---
sys/dev/vmgenc/vmgenc_acpi.c | 8 +++++++-
sys/sys/random.h | 3 ---
5 files changed, 29 insertions(+), 26 deletions(-)
diff --git a/sys/dev/random/random_harvestq.c b/sys/dev/random/random_harvestq.c
index 20727471f9c7..eb3808d692bb 100644
--- a/sys/dev/random/random_harvestq.c
+++ b/sys/dev/random/random_harvestq.c
@@ -278,8 +278,15 @@ random_sources_feed(void)
epoch_enter_preempt(rs_epoch, &et);
CK_LIST_FOREACH(rrs, &source_list, rrs_entries) {
for (i = 0; i < npools; i++) {
+ if (rrs->rrs_source->rs_read == NULL) {
+ /* Source pushes entropy asynchronously. */
+ continue;
+ }
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)));
+ KASSERT((n <= sizeof(entropy)),
+ ("%s: rs_read returned too much data (%u > %zu)",
+ __func__, n, sizeof(entropy)));
+
/*
* Sometimes the HW entropy source doesn't have anything
* ready for us. This isn't necessarily untrustworthy.
@@ -866,20 +873,6 @@ random_harvest_direct_(const void *entropy, u_int size, enum random_entropy_sour
random_harvestq_fast_process_event(&event);
}
-void
-random_harvest_register_source(enum random_entropy_source source)
-{
-
- hc_source_mask |= (1 << source);
-}
-
-void
-random_harvest_deregister_source(enum random_entropy_source source)
-{
-
- hc_source_mask &= ~(1 << source);
-}
-
void
random_source_register(const struct random_source *rsource)
{
@@ -890,10 +883,9 @@ random_source_register(const struct random_source *rsource)
rrs = malloc(sizeof(*rrs), M_ENTROPY, M_WAITOK);
rrs->rrs_source = rsource;
- random_harvest_register_source(rsource->rs_source);
-
printf("random: registering fast source %s\n", rsource->rs_ident);
+ hc_source_mask |= (1 << rsource->rs_source);
RANDOM_HARVEST_LOCK();
CK_LIST_INSERT_HEAD(&source_list, rrs, rrs_entries);
RANDOM_HARVEST_UNLOCK();
@@ -906,8 +898,7 @@ random_source_deregister(const struct random_source *rsource)
KASSERT(rsource != NULL, ("invalid input to %s", __func__));
- random_harvest_deregister_source(rsource->rs_source);
-
+ hc_source_mask &= ~(1 << rsource->rs_source);
RANDOM_HARVEST_LOCK();
CK_LIST_FOREACH(rrs, &source_list, rrs_entries)
if (rrs->rrs_source == rsource) {
diff --git a/sys/dev/random/randomdev.h b/sys/dev/random/randomdev.h
index 6d742447ea8b..0fa92f8c9575 100644
--- a/sys/dev/random/randomdev.h
+++ b/sys/dev/random/randomdev.h
@@ -52,7 +52,9 @@ random_check_uint_##name(SYSCTL_HANDLER_ARGS) \
}
#endif /* SYSCTL_DECL */
+#ifdef MALLOC_DECLARE
MALLOC_DECLARE(M_ENTROPY);
+#endif
extern bool random_bypass_before_seeding;
extern bool read_random_bypassed_before_seeding;
diff --git a/sys/dev/tpm/tpm20.c b/sys/dev/tpm/tpm20.c
index 876dd0bcc40d..067e7ccae8f9 100644
--- a/sys/dev/tpm/tpm20.c
+++ b/sys/dev/tpm/tpm20.c
@@ -25,8 +25,8 @@
* POSSIBILITY OF SUCH DAMAGE.
*/
-#include <sys/cdefs.h>
#include <sys/random.h>
+#include <dev/random/randomdev.h>
#include "tpm20.h"
@@ -184,6 +184,13 @@ tpm20_ioctl(struct cdev *dev, u_long cmd, caddr_t data,
return (ENOTTY);
}
+#ifdef TPM_HARVEST
+static const struct random_source random_tpm = {
+ .rs_ident = "TPM",
+ .rs_source = RANDOM_PURE_TPM,
+};
+#endif
+
int
tpm20_init(struct tpm_sc *sc)
{
@@ -206,7 +213,7 @@ tpm20_init(struct tpm_sc *sc)
tpm20_release(sc);
#ifdef TPM_HARVEST
- random_harvest_register_source(RANDOM_PURE_TPM);
+ random_source_register(&random_tpm);
TIMEOUT_TASK_INIT(taskqueue_thread, &sc->harvest_task, 0,
tpm20_harvest, sc);
taskqueue_enqueue_timeout(taskqueue_thread, &sc->harvest_task, 0);
@@ -223,7 +230,7 @@ tpm20_release(struct tpm_sc *sc)
#ifdef TPM_HARVEST
if (device_is_attached(sc->dev))
taskqueue_drain_timeout(taskqueue_thread, &sc->harvest_task);
- random_harvest_deregister_source(RANDOM_PURE_TPM);
+ random_source_deregister(&random_tpm);
#endif
if (sc->buf != NULL)
diff --git a/sys/dev/vmgenc/vmgenc_acpi.c b/sys/dev/vmgenc/vmgenc_acpi.c
index 2ad8929dfd34..18519a8e4f22 100644
--- a/sys/dev/vmgenc/vmgenc_acpi.c
+++ b/sys/dev/vmgenc/vmgenc_acpi.c
@@ -56,6 +56,7 @@
#include <contrib/dev/acpica/include/acpi.h>
#include <dev/acpica/acpivar.h>
+#include <dev/random/randomdev.h>
#include <dev/random/random_harvestq.h>
#include <dev/vmgenc/vmgenc_acpi.h>
@@ -210,6 +211,11 @@ acpi_GetPackedUINT64(device_t dev, ACPI_HANDLE handle, char *path,
}
+static const struct random_source random_vmgenid = {
+ .rs_ident = "VM Generation ID",
+ .rs_source = RANDOM_PURE_VMGENID,
+};
+
static int
vmgenc_attach(device_t dev)
{
@@ -234,7 +240,7 @@ 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);
+ random_source_register(&random_vmgenid);
vmgenc_harvest_all(sc->vmg_cache_guid, sizeof(sc->vmg_cache_guid));
AcpiInstallNotifyHandler(h, ACPI_DEVICE_NOTIFY, vmgenc_notify, dev);
diff --git a/sys/sys/random.h b/sys/sys/random.h
index 5abf762cd200..2a68f0c99b6d 100644
--- a/sys/sys/random.h
+++ b/sys/sys/random.h
@@ -142,9 +142,6 @@ random_harvest_direct(const void *entropy, u_int size, enum random_entropy_sourc
random_harvest_direct_(entropy, size, origin);
}
-void random_harvest_register_source(enum random_entropy_source);
-void random_harvest_deregister_source(enum random_entropy_source);
-
#if defined(RANDOM_ENABLE_UMA)
#define random_harvest_fast_uma(a, b, c) random_harvest_fast(a, b, c)
#else /* !defined(RANDOM_ENABLE_UMA) */