Date: Fri, 26 Sep 2003 10:59:21 -0500 From: "Jacques A. Vidrine" <nectar@FreeBSD.org> To: freebsd-net@freebsd.org Subject: Re: Alternative fix for FreeBSD-SA-03:14.arp Message-ID: <20030926155921.GG41896@madman.celabo.org> In-Reply-To: <20030926152349.GI662@saboteur.dek.spc.org> References: <20030926152349.GI662@saboteur.dek.spc.org>
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On Fri, Sep 26, 2003 at 04:23:49PM +0100, Bruce M Simpson wrote:
> Hi,
>
> Based on discussion between ru@ and I, there's a patch attached which
> tries to fix the problem without deleting GENMASK routes, and is
> stricter about not touching STATIC routes.
>
> Comments and reviews solicited, appreciated...
>
> Thanks!
> BMS
> --- if_ether.c.orig Mon Sep 22 21:11:59 2003
> +++ if_ether.c Fri Sep 26 13:43:20 2003
> @@ -922,9 +922,19 @@
> if (why && create) {
> log(LOG_DEBUG, "arplookup %s failed: %s\n",
> inet_ntoa(sin.sin_addr), why);
> - return 0;
> +
> + if ((rt->rt_refcnt == 0) &&
> + (rt->rt_flags & RTF_STATIC) == 0 &&
> + (rt->rt_flags & (RTF_HOST|RTF_WASCLONED)) ==
> + (RTF_HOST|RTF_WASCLONED)) {
> + rtrequest(RTM_DELETE, (struct sockaddr *)rt_key(rt),
> + rt->rt_gateway, rt_mask(rt),
> + rt->rt_flags, 0);
> + }
> +
> + return (0);
> } else if (why) {
> - return 0;
> + return (0);
> }
> return ((struct llinfo_arp *)rt->rt_llinfo);
> }
Trivial nit. In this file, the style is
Test for flag set: if (rt->rt_flags & RTF_STATIC)
Test for flag not set: if ((rt->rt_flags & RTF_STATIC) == 0)
The comparison operators make it harder to read, especially those
comparison operations that don't involve a zero operand.
[Personally, for flag not set, I prefer `!(rt->rt_flags & RTF_STATIC)'
but that goes against the style of this file, at least.]
This seems OK to me, although I find it hard to understand how we
get into the situation where the genmask route entry (which we are
protecting) would have the RTF_WASCLONED bit set. That's likely to do
with my lack of familiarity with genmask routes.
Cheers,
--
Jacques Vidrine . NTT/Verio SME . FreeBSD UNIX . Heimdal
nectar@celabo.org . jvidrine@verio.net . nectar@freebsd.org . nectar@kth.se
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