Date: Tue, 17 Mar 2020 16:36:25 -0600 From: Ian Lepore <ian@freebsd.org> To: Conrad Meyer <cem@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r359053 - head/sys/kern Message-ID: <047c4edb4ff9fa6c40be6492c2f082e374f7a941.camel@freebsd.org> In-Reply-To: <202003172227.02HMRHLM086023@repo.freebsd.org> References: <202003172227.02HMRHLM086023@repo.freebsd.org>
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On Tue, 2020-03-17 at 22:27 +0000, Conrad Meyer wrote: > 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 This seems a bit complex. Why run a sysinit to init a mutex so that you can safely do a lazy init of boot_id? Seems like it would be much easier to just use a sysinit at SI_SUB_LAST to init boot_id before sysctl can reference it. -- Ian
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