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Implement sysctl kern.boot_id

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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
This commit is contained in:
Conrad Meyer 2020-03-17 22:27:16 +00:00
parent 725cc1de9a
commit 34086d5bda
1 changed files with 26 additions and 0 deletions
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26
sys/kern/kern_mib.c
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@ -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