Date: Thu, 20 Sep 2012 08:44:10 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-security@freebsd.org, obrien@freebsd.org Cc: Arthur Mesh <arthurmesh@gmail.com>, Ian Lepore <freebsd@damnhippie.dyndns.org>, Doug Barton <dougb@freebsd.org>, Ben Laurie <benl@freebsd.org>, RW <rwmaillists@googlemail.com> Subject: Re: Proposed fix; stage 1 (Was: svn commit: r239569 - head/etc/rc.d) Message-ID: <201209200844.10470.jhb@freebsd.org> In-Reply-To: <20120919220819.GB25606@dragon.NUXI.org> References: <CAG5KPzzRxzVX-%2B9fYjRdqjY-wScbM6AA7GYtLmktgMG0Zg8iyQ@mail.gmail.com> <E1TDHb0-000FIh-0Z@groundzero.grondar.org> <20120919220819.GB25606@dragon.NUXI.org>
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On Wednesday, September 19, 2012 6:08:19 pm David O'Brien wrote:
> Also, I'm having trouble finding the source for 'swi' harvesting.
> Do you know where it is?
It has certainly not been used since 5.0. I wasn't able to find it
in my limited grubbing around in 4.x sources either.
The untested change below would add it so that all calls to swi_sched() would
harvest something similar to what happens for hardware interrupts. Note that
the current code already explicitly forbids INTR_ENTROPY from being set for
swi handlers, so the current random_harvest() call in intr_schedule_thread()
should never trigger for an swi. I just copied the random_harvest() code from
the hardware interrupt case. I leave it up to someone else to explicitly ok
that this data goes into the RANDOM_INTERRUPT queue with the claim of 2 bits
of entropy:
Index: sys/kern/kern_intr.c
===================================================================
--- kern_intr.c (revision 240605)
+++ kern_intr.c (working copy)
@@ -1144,11 +1144,21 @@ swi_sched(void *cookie, int flags)
{
struct intr_handler *ih = (struct intr_handler *)cookie;
struct intr_event *ie = ih->ih_event;
+ struct intr_entropy entropy;
int error;
CTR3(KTR_INTR, "swi_sched: %s %s need=%d", ie->ie_name, ih->ih_name,
ih->ih_need);
+ if (harvest.swi) {
+ CTR3(KTR_INTR, "swi_sched: pid %d (%s) gathering entropy",
+ curproc->p_pid, curthread->td_name);
+ entropy.event = (uintptr_t)ih;
+ entropy.td = curthread;
+ random_harvest(&entropy, sizeof(entropy), 2, 0,
+ RANDOM_INTERRUPT);
+ }
+
/*
* Set ih_need for this handler so that if the ithread is already
* running it will execute this handler on the next pass. Otherwise,
--
John Baldwin
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