Author: cem
Date: Tue Mar 17 22:27:16 2020
New Revision: 359053
URL: https://svnweb.freebsd.org/changeset/base/359053
Log:
Implement sysctl kern.boot_id
Boot IDs are random, opaque 128-bit identifiers that distinguish distinct
system boots. A new ID is generated each time the system boots. Unlike
kern.boottime, the value is not modified by NTP adjustments. It remains fixed
until the machine is restarted.
PR: 244867
Reported by: Ricardo Fraile <rfraile AT rfraile.eu>
MFC after: I do not intend to, but feel free
Modified:
head/sys/kern/kern_mib.c
Modified: head/sys/kern/kern_mib.c
==============================================================================
--- head/sys/kern/kern_mib.c Tue Mar 17 21:29:03 2020 (r359052)
+++ head/sys/kern/kern_mib.c Tue Mar 17 22:27:16 2020 (r359053)
@@ -448,6 +448,32 @@ SYSCTL_PROC(_kern, KERN_HOSTID, hostid,
CTLTYPE_ULONG | CTLFLAG_RW | CTLFLAG_PRISON | CTLFLAG_MPSAFE |
CTLFLAG_CAPRD,
NULL, 0, sysctl_hostid, "LU", "Host ID");
+static struct mtx bootid_lk;
+MTX_SYSINIT(bootid_lock, &bootid_lk, "bootid generator lock", MTX_DEF);
+
+static int
+sysctl_bootid(SYSCTL_HANDLER_ARGS)
+{
+ static uint8_t boot_id[16];
+ static bool initialized = false;
+
+ mtx_lock(&bootid_lk);
+ if (!initialized) {
+ if (!is_random_seeded()) {
+ mtx_unlock(&bootid_lk);
+ return (ENXIO);
+ }
+ arc4random_buf(boot_id, sizeof(boot_id));
+ initialized = true;
+ }
+ mtx_unlock(&bootid_lk);
+
+ return (SYSCTL_OUT(req, boot_id, sizeof(boot_id)));
+}
+SYSCTL_PROC(_kern, OID_AUTO, boot_id,
+ CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_MPSAFE | CTLFLAG_CAPRD,
+ NULL, 0, sysctl_bootid, "", "Random boot ID");
+
/*
* The osrelease string is copied from the global (osrelease in vers.c) into
* prison0 by a sysinit and is inherited by child jails if not changed at jail
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