Attachment 672505 Details for Bug 891784 – [PATCH] ipv6: Enforce RFC 4191 Default Gateway replacement

[patch] [PATCH] ipv6: Enforce RFC 4191 Default Gateway replacement

-ipv6-Enforce-RFC-4191-Default-Gateway-replacement.patch (text/plain), 2.06 KB, created by Neil Horman on 2013-01-04 18:57:52 UTC

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Creator: Neil Horman

Created: 2013-01-04 18:57:52 UTC

Size: 2.06 KB

patch

obsolete

>From 22757d0f8b5f98e1f6931073d257b254d26ac83e Mon Sep 17 00:00:00 2001
>From: Neil Horman <nhorman@tuxdriver.com>
>Date: Fri, 4 Jan 2013 13:23:33 -0500
>Subject: [PATCH v2] ipv6: Enforce RFC 4191 Default Gateway replacement
>
>RFC 4191 introduces the notion of router preference bits in router
>advertizements, which we appear to handle incorrectly.  When two adverts arrive
>at a host, if the advert contains a higher priority than the current existing
>default router, we currently simply update the pref bits in the existing default
>route to reflect the higher preference.  This operates under the assumption that
>the advert is for the same gateway as what we already have configured.  What we
>should be doing is keeping the old default route, but adding a new route for the
>arriving adv with the higher preference value, so that we route to the proper
>preferred gateway, in the case where two independent routers exist on the same
>subnet.
>
>Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
>CC: "David S. Miller" <davem@davemloft.net>
>CC: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
>---
> net/ipv6/ndisc.c | 20 +++++++++++++++-----
> 1 file changed, 15 insertions(+), 5 deletions(-)
>
>diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
>index 6574175..20e78fa 100644
>--- a/net/ipv6/ndisc.c
>+++ b/net/ipv6/ndisc.c
>@@ -1130,9 +1130,21 @@ static void ndisc_router_discovery(struct sk_buff *skb)
> 			return;
> 		}
> 	}
>-	if (rt && lifetime == 0) {
>-		ip6_del_rt(rt);
>-		rt = NULL;
>+
>+	if (rt) {
>+		if (!lifetime) {
>+			ip6_del_rt(rt);
>+			rt = NULL;
>+		}
>+
>+		/*
>+		 * If we have a route who's preference is less tha
>+		 * the one in this adv., keep the old one but install
>+		 * the new one being advertized with the higher pref.
>+		 * see RFC 4191 section 2.1
>+		 */
>+		if (rt && (IPV6_EXTRACT_PREF(rt->rt6i_flags) < pref))
>+			rt = NULL;
> 	}
> 
> 	if (rt == NULL && lifetime) {
>@@ -1155,8 +1167,6 @@ static void ndisc_router_discovery(struct sk_buff *skb)
> 			return;
> 		}
> 		neigh->flags |= NTF_ROUTER;
>-	} else if (rt) {
>-		rt->rt6i_flags = (rt->rt6i_flags & ~RTF_PREF_MASK) | RTF_PREF(pref);
> 	}
> 
> 	if (rt)
>-- 
>1.7.11.7
>

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Attachments on bug 891784: 672267 | 672505 | 673170