From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Dichtel Subject: Re: [PATCH 1/2] ipv6: avoid blackhole and prohibited entries upon prefix purge [v2] Date: Mon, 07 Jan 2013 16:43:12 +0100 Message-ID: <50EAED10.90904@6wind.com> References: <0CC79564-4AF2-42F9-8D06-1BCC912A1AF7@ipflavors.com> <1357415941.1678.4163.camel@edumazet-glaptop> <2A507F9D-3D53-475F-8FA9-9E6CFEE9C97A@ipflavors.com> <50EAA28B.1080300@6wind.com> <3EF640F8-5242-486E-B7A3-9DA2A88F5A4F@ipflavors.com> Reply-To: nicolas.dichtel@6wind.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org, Eric Dumazet , yoshfuji@linux-ipv6.org, davem@davemloft.net To: Romain KUNTZ Return-path: Received: from mail-bk0-f50.google.com ([209.85.214.50]:58684 "EHLO mail-bk0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753273Ab3AGPnR (ORCPT ); Mon, 7 Jan 2013 10:43:17 -0500 Received: by mail-bk0-f50.google.com with SMTP id jf3so8590570bkc.37 for ; Mon, 07 Jan 2013 07:43:16 -0800 (PST) In-Reply-To: <3EF640F8-5242-486E-B7A3-9DA2A88F5A4F@ipflavors.com> Sender: netdev-owner@vger.kernel.org List-ID: Le 07/01/2013 12:30, Romain KUNTZ a =E9crit : > Hello Nicolas, > > On Jan 7, 2013, at 11:25 , Nicolas Dichtel wrote: > >> Le 05/01/2013 22:44, Romain KUNTZ a =E9crit : >>> Mobile IPv6 provokes a kernel Oops since commit 64c6d08e (ipv6: >>> del unreachable route when an addr is deleted on lo), because >>> ip6_route_lookup() may also return blackhole and prohibited >>> entry. However, these entries have a NULL rt6i_table argument, >>> which provokes an Oops in __ip6_del_rt() when trying to lock >>> rt6i_table->tb6_lock. >>> >>> Beside, when purging a prefix, blakhole and prohibited entries >>> should not be selected because they are not what we are looking >>> for. >>> >>> We fix this by adding two new lookup flags (RT6_LOOKUP_F_NO_BLK_HOL= E >>> and RT6_LOOKUP_F_NO_PROHIBIT) in order to ensure that such entries >>> are skipped during lookup and that the correct entry is returned. >>> >>> [v2]: use 'goto out;' instead of 'goto again;' to avoid unnecessary >>> oprations on rt (as suggested by Eric Dumazet). >>> >>> Signed-off-by: Romain Kuntz >>> --- >>> include/net/ip6_route.h | 2 ++ >>> net/ipv6/addrconf.c | 4 +++- >>> net/ipv6/fib6_rules.c | 4 ++++ >>> 3 files changed, 9 insertions(+), 1 deletions(-) >>> >>> diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h >>> index 27d8318..3c93743 100644 >>> --- a/include/net/ip6_route.h >>> +++ b/include/net/ip6_route.h >>> @@ -30,6 +30,8 @@ struct route_info { >>> #define RT6_LOOKUP_F_SRCPREF_TMP 0x00000008 >>> #define RT6_LOOKUP_F_SRCPREF_PUBLIC 0x00000010 >>> #define RT6_LOOKUP_F_SRCPREF_COA 0x00000020 >>> +#define RT6_LOOKUP_F_NO_BLK_HOLE 0x00000040 >>> +#define RT6_LOOKUP_F_NO_PROHIBIT 0x00000080 >>> >>> /* >>> * rt6_srcprefs2flags() and rt6_flags2srcprefs() translate >>> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c >>> index 408cac4a..1891e23 100644 >>> --- a/net/ipv6/addrconf.c >>> +++ b/net/ipv6/addrconf.c >>> @@ -948,7 +948,9 @@ static void ipv6_del_addr(struct inet6_ifaddr *= ifp) >>> fl6.flowi6_oif =3D ifp->idev->dev->ifindex; >>> fl6.daddr =3D prefix; >>> rt =3D (struct rt6_info *)ip6_route_lookup(net, &fl6, >>> - RT6_LOOKUP_F_IFACE); >>> + RT6_LOOKUP_F_IFACE | >>> + RT6_LOOKUP_F_NO_BLK_HOLE | >>> + RT6_LOOKUP_F_NO_PROHIBIT); >>> >>> if (rt !=3D net->ipv6.ip6_null_entry && >> Is it not simpler to test the result here (net->ipv6.ip6_blk_hole_en= try and >> net->ipv6.ip6_prohibit_entry) like for the null_entry? >> It will also avoid adding more flags. > > Your proposal would only solve part of the problem (the Oops in __ip6= _del_rt()). Another problem here is that blackhole and prohibited rules= should not be selected when trying to purge a prefix (correct me if I'= m wrong) because they are not what we are looking for. This can prevent= the targeted prefix from being purged. In fact, I'm not sure to get the scenario. This part of the code just t= ries to remove the connected prefix, added by the kernel when the address wa= s added. Can you describe your scenario?