Module Name: src
Committed By: riastradh
Date: Tue Mar 11 14:30:28 UTC 2025
Modified Files:
src/lib/libc/gen: arc4random.c
src/sys/kern: kern_entropy.c
src/sys/sys: sysctl.h
Log Message:
Assign static MIB numbers for kern.entropy.epoch.
This sidesteps any need for dynamically sized memory in userland to
resolve sysctl names to read it out, or for a new syscall interface
to sysctl resolution by name.
It would really be better to expose this through a page shared with
userland, so querying it doesn't cost a syscall, but this will serve
for now.
PR lib/59148: arc4random calls malloc so it can't be used in an ELF
constructor
To generate a diff of this commit:
cvs rdiff -u -r1.49 -r1.50 src/lib/libc/gen/arc4random.c
cvs rdiff -u -r1.72 -r1.73 src/sys/kern/kern_entropy.c
cvs rdiff -u -r1.239 -r1.240 src/sys/sys/sysctl.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/lib/libc/gen/arc4random.c
diff -u src/lib/libc/gen/arc4random.c:1.49 src/lib/libc/gen/arc4random.c:1.50
--- src/lib/libc/gen/arc4random.c:1.49 Tue Mar 11 13:35:54 2025
+++ src/lib/libc/gen/arc4random.c Tue Mar 11 14:30:27 2025
@@ -1,4 +1,4 @@
-/* $NetBSD: arc4random.c,v 1.49 2025/03/11 13:35:54 riastradh Exp $ */
+/* $NetBSD: arc4random.c,v 1.50 2025/03/11 14:30:27 riastradh Exp $ */
/*-
* Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -51,7 +51,7 @@
*/
#include <sys/cdefs.h>
-__RCSID("$NetBSD: arc4random.c,v 1.49 2025/03/11 13:35:54 riastradh Exp $");
+__RCSID("$NetBSD: arc4random.c,v 1.50 2025/03/11 14:30:27 riastradh Exp $");
#include "namespace.h"
#include "reentrant.h"
@@ -64,7 +64,6 @@ __RCSID("$NetBSD: arc4random.c,v 1.49 20
#include <assert.h>
#include <sha2.h>
-#include <stdatomic.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
@@ -511,35 +510,10 @@ crypto_onetimestream_selftest(void)
static unsigned
entropy_epoch(void)
{
- static atomic_int mib0[3];
- static atomic_bool initialized = false;
- int mib[3];
+ const int mib[] = { CTL_KERN, KERN_ENTROPY, KERN_ENTROPY_EPOCH };
unsigned epoch = (unsigned)-1;
size_t epochlen = sizeof(epoch);
- /*
- * Resolve kern.entropy.epoch if we haven't already. Cache it
- * for the next caller. Initialization is idempotent, so it's
- * OK if two threads do it at once.
- */
- if (atomic_load_explicit(&initialized, memory_order_acquire)) {
- mib[0] = atomic_load_explicit(&mib0[0], memory_order_relaxed);
- mib[1] = atomic_load_explicit(&mib0[1], memory_order_relaxed);
- mib[2] = atomic_load_explicit(&mib0[2], memory_order_relaxed);
- } else {
- size_t nmib = __arraycount(mib);
-
- if (sysctlnametomib("kern.entropy.epoch", mib, &nmib) == -1)
- return (unsigned)-1;
- if (nmib != __arraycount(mib))
- return (unsigned)-1;
- atomic_store_explicit(&mib0[0], mib[0], memory_order_relaxed);
- atomic_store_explicit(&mib0[1], mib[1], memory_order_relaxed);
- atomic_store_explicit(&mib0[2], mib[2], memory_order_relaxed);
- atomic_store_explicit(&initialized, true,
- memory_order_release);
- }
-
if (sysctl(mib, __arraycount(mib), &epoch, &epochlen, NULL, 0) == -1)
return (unsigned)-1;
if (epochlen != sizeof(epoch))
Index: src/sys/kern/kern_entropy.c
diff -u src/sys/kern/kern_entropy.c:1.72 src/sys/kern/kern_entropy.c:1.73
--- src/sys/kern/kern_entropy.c:1.72 Tue Aug 27 00:56:47 2024
+++ src/sys/kern/kern_entropy.c Tue Mar 11 14:30:28 2025
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_entropy.c,v 1.72 2024/08/27 00:56:47 riastradh Exp $ */
+/* $NetBSD: kern_entropy.c,v 1.73 2025/03/11 14:30:28 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 1.72 2024/08/27 00:56:47 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_entropy.c,v 1.73 2025/03/11 14:30:28 riastradh Exp $");
#include <sys/param.h>
#include <sys/types.h>
@@ -358,7 +358,7 @@ entropy_init(void)
CTLFLAG_PERMANENT, CTLTYPE_NODE, "entropy",
SYSCTL_DESCR("Entropy (random number sources) options"),
NULL, 0, NULL, 0,
- CTL_KERN, CTL_CREATE, CTL_EOL);
+ CTL_KERN, KERN_ENTROPY, CTL_EOL);
/* Create the sysctl knobs. */
/* XXX These shouldn't be writable at securelevel>0. */
@@ -402,7 +402,7 @@ entropy_init(void)
sysctl_createv(&entropy_sysctllog, 0, &entropy_sysctlroot, NULL,
CTLFLAG_PERMANENT|CTLFLAG_READONLY, CTLTYPE_INT,
"epoch", SYSCTL_DESCR("Entropy epoch"),
- NULL, 0, &E->epoch, 0, CTL_CREATE, CTL_EOL);
+ NULL, 0, &E->epoch, 0, KERN_ENTROPY_EPOCH, CTL_EOL);
/* Initialize the global state for multithreaded operation. */
mutex_init(&E->lock, MUTEX_DEFAULT, IPL_SOFTSERIAL);
Index: src/sys/sys/sysctl.h
diff -u src/sys/sys/sysctl.h:1.239 src/sys/sys/sysctl.h:1.240
--- src/sys/sys/sysctl.h:1.239 Sat Jan 20 13:15:46 2024
+++ src/sys/sys/sysctl.h Tue Mar 11 14:30:28 2025
@@ -1,4 +1,4 @@
-/* $NetBSD: sysctl.h,v 1.239 2024/01/20 13:15:46 christos Exp $ */
+/* $NetBSD: sysctl.h,v 1.240 2025/03/11 14:30:28 riastradh Exp $ */
/*
* Copyright (c) 1989, 1993
@@ -275,6 +275,7 @@ struct ctlname {
#define KERN_BOOTTIME 83 /* struct: time kernel was booted */
#define KERN_EVCNT 84 /* struct: evcnts */
#define KERN_SOFIXEDBUF 85 /* bool: fixed socket buffer sizes */
+#define KERN_ENTROPY 86 /* node: entropy(9) subsystem */
/*
* KERN_CLOCKRATE structure
@@ -780,6 +781,12 @@ typedef int (*hashstat_func_t)(struct ha
void hashstat_register(const char *, hashstat_func_t);
/*
+ * kern.entropy.* variables
+ */
+
+#define KERN_ENTROPY_EPOCH 1 /* int: PRNG reseed epoch */
+
+/*
* CTL_VM identifiers in <uvm/uvm_param.h>
*/
