Date: Tue, 17 Mar 2020 22:27:17 +0000 (UTC) From: Conrad Meyer <cem@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r359053 - head/sys/kern Message-ID: <202003172227.02HMRHLM086023@repo.freebsd.org>
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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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